ALBERT

Description: 〈p〉Publication date: Available online 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Pierre Pichat〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Studies of the adsorption and reactions of appropriate molecules are a valuable means to probe active surfaces. This overview deals with the use of nitrogen monoxide – a molecule that has less been utilized than some others as a surface probe – to investigate TiO〈sub〉2〈/sub〉 and TiO〈sub〉2〈/sub〉-containing materials, with or without photo-excitation. It shows that diverse information can be derived from: (1) the infrared spectra of adsorbed NO; (2) the isotopic exchange of N〈sup〉18〈/sup〉O; (3) the formation of N〈sub〉2〈/sub〉O and N〈sub〉2〈/sub〉; (4) the use of NO (or N〈sup〉18〈/sup〉O) in oxidation reactions in place of O〈sub〉2〈/sub〉; and (5) the evaluation of the electron transfer to NO through density functional theory calculations, ultraviolet photoemission spectroscopy, and photoconductance measurements. Valuable knowledge may thus be potentially acquired on: the accessibility and reactivity of surface OH groups, the lability of surface O atoms, the self-cleaning efficacy, the environment and dispersion of TiO〈sub〉2〈/sub〉 in composite materials, the existence of bandgap electronic states, and the electron transfer capacity, depending on the investigation technique employed, the conditions and the type of TiO〈sub〉2〈/sub〉 sample.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118311921-ga1.jpg" width="348" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 30 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): G. Bonura, A.A. Khassin, T.M. Yurieva, C. Cannilla, F. Frusteri, L. Frusteri〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A series of coprecipitated binary Cu-ZrO〈sub〉2〈/sub〉 catalysts was found to show an interesting activity–selectivity pattern during methanol synthesis from catalytic hydrogenation of carbon oxides (〈em〉P〈/em〉〈sub〉R〈/sub〉, 20–30 atm; 〈em〉T〈/em〉〈sub〉R〈/sub〉, 200–240 °C). The effects of various pre–treatments as well as the copper/zirconia ratio on the structural and chemical properties of these samples were examined. The isoconversional Ozawa-Flynn-Wall method was applied to study the reduction behaviour, while the best fit modelling was used to establish the plausible mechanism of copper reduction. The extent of methanol formation rate was found to be dependent on the structure formed upon catalyst reduction, both in CO and in CO〈sub〉2〈/sub〉 hydrogenation conditions. The pre–calcination of the sample at a temperature as high as 650 °C negatively affected the methanol formation rate under CO hydrogenation conditions, while under the same activation treatment an increased specific activity was observed in CO〈sub〉2〈/sub〉 hydrogenation conditions, although with a minor methanol selectivity, since the rate of the WGS reaction was stronger enhanced. The incorporation of Zn into the catalyst formulation resulted in a visible increasing of the methanol formation rate, owing to the formation of a copper–zinc mixed oxide during calcination, which leads to higher metal dispersion also depressing the methane formation rate.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118307028-ga1.jpg" width="286" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 31 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Haibiao Yu, Xinping Wang, Ye Li〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉For the Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/CaCO〈sub〉3〈/sub〉 catalysts used for N〈sub〉2〈/sub〉O decomposition, the activity of the catalyst prepared by stepwise precipitation is much superior to the catalysts prepared by impregnation or coprecipitation in the same composition. HRTEM observation and EDX analysis indicate that the stepwise precipitation leads to cobalt existing as little Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 crystallites tightly bound to the CaCO〈sub〉3〈/sub〉 particles. The special structure made the Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 ideal accessibility and better interaction with the support in the catalyst, and the CaCo〈sub〉2.5〈/sub〉(SP) catalyst with this structure is much more active than the CaCo〈sub〉2.5〈/sub〉 catalyst reported in literature prepared in traditional method. At 300 °C, N〈sub〉2〈/sub〉O in the feed gas 2000 ppmv N〈sub〉2〈/sub〉O/Ar was completely converted over the CaCo〈sub〉2.5〈/sub〉(SP) at 20,000 h〈sup〉−1〈/sup〉. Moreover, the CaCo〈sub〉2.5〈/sub〉(SP) catalyst exhibited better resistance to sintering at 800 °C and quite high activity under the presence of 5 vol% O〈sub〉2〈/sub〉 and 2 vol% H〈sub〉2〈/sub〉O at 350 °C as well.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118311611-ga1.jpg" width="361" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 14 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Mikhail P. Popov, Daniel V. Maslennikov, Igor I. Gainutdinov, Igor P. Gulyaev, Andrey N. Zagoruiko, Alexander P. Nemudry〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉AC heated oxygen-permeable microtubular membranes with the composition Ba〈sub〉0.5〈/sub〉Sr〈sub〉0.5〈/sub〉Co〈sub〉0.78〈/sub〉W〈sub〉0.02〈/sub〉Fe〈sub〉0.2〈/sub〉O〈sub〉3-〈/sub〉〈em〉〈sub〉δ〈/sub〉〈/em〉 were used to provide catalytic reforming of methane into C〈sub〉2〈/sub〉- hydrocarbons. The methane conversion degree about 60% and acetylene yield about 27% at 1200 °C was achieved. Microtubular solid oxide fuel cells based on gadolinium-doped ceria with perovskite-like cathode material composed of Ba〈sub〉0.5〈/sub〉Sr〈sub〉0.5〈/sub〉Co〈sub〉0.75〈/sub〉Mo〈sub〉0.05〈/sub〉Fe〈sub〉0.2〈/sub〉O〈sub〉3-〈/sub〉〈em〉〈sub〉δ〈/sub〉〈/em〉 were prepared. The MT-SOFC demonstrates maximum power densities of 50, 100, 200 mW/cm〈sup〉2〈/sup〉 at 550, 600, 650 °C, respectively with humidified H〈sub〉2〈/sub〉 as fuel and ambient air as oxidant.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118315244-ga1.jpg" width="250" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 14 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Xinyu Jia, Ning Rui, Xiaoshan Zhang, Xue Hu, Chang-jun Liu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉CO methanation over supported Ni catalysts has recently attracted increasing attentions. However, the low temperature activity and stability of Ni catalysts still need to be improved. In this work, a dielectric barrier discharge (DBD) plasma decomposition of nickel nitrate has been performed at atmospheric pressure and around 150 °C. Followed by the hydrogen reduction thermally at 500 °C, a highly dispersed Ni/ZrO〈sub〉2〈/sub〉 catalyst with intensified Ni-ZrO〈sub〉2〈/sub〉 interaction and significantly improved activity for CO methanation has been obtained. The DBD plasma decomposed catalyst effectively promotes CO dissociation as well as further hydrogenation. In addition, more reactive atomic carbon is formed on the Ni active sites. Such carbon species can be quickly removed by H〈sub〉2〈/sub〉 gasification, keeping the Ni surface clean. A better balance between CO dissociation and carbon gasification has been achieved with enhanced carbon resistance. Therefore the DBD plasma decomposed catalyst can remain active under lower H〈sub〉2〈/sub〉/CO ratios, while the calcined catalyst needs higher H〈sub〉2〈/sub〉/CO feed ratio to overcome the catalyst deactivation.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118308538-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 12 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): E. Gracia, M.T. García, A. De Lucas, J.F. Rodríguez, I. Gracia〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Use of copper wire bits as simple catalyst in a click chemistry reaction using supercritical CO〈sub〉2〈/sub〉 has been achieved. The use of this catalyst in the reaction between polylactic acid (PLA) and coumarin allows to remove the whole amount of catalyst in the final product with a simple purification step using a green solvent where no toxic solvent is used in order to synthetize the product.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118312999-ga1.jpg" width="443" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 4 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Fengfeng Chen, Qingwen Lu, Ting Fan, Ruiqi Fang, Yingwei Li〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Here we report a novel approach to synthesize Au NPs immobilized on N-doped carbon materials. In this strategy, an ionic liquid (IL) [Bmim][AuCl〈sub〉4〈/sub〉] was selected as the precursor for Au NPs and porous framework of ZIF-8 as the host for the IL. Raman spectroscopy, transmission electron microscopy, N〈sub〉2〈/sub〉 physical absorption and Fourier infrared spectra confirmed that the IL was successfully incorporated in the ZIF-8 pores. Followed by a thermal treatment under inert atmosphere, highly dispersed Au NPs were obtained and stabilized by nitrogen species from the carbonization of organic ligand in the metal-organic frameworks (MOFs). The [Bmim][AuCl〈sub〉4〈/sub〉]@ZIF-8-6.25%-〈em〉T〈/em〉 materials exhibited high catalytic activity for the selective aerobic oxidation of alcohols, affording excellent yields (up to 〉99%) under atmospheric air and base-free conditions. Catalytic reaction along with catalyst characterization results revealed a strong interaction between Au NPs and N species. TEM, XRD and XPS characterization results further suggested that the N species could not only prevent the Au NPs from aggregation, but also further enhance the reaction activity.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118308022-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 4 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Motaz Khawaji, David Chadwick〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The dependence of the selective oxidation catalytic activity of Au-Pd supported on titanate nanotubes on the catalyst preparation method has been investigated. The most active Au-Pd/Ti-NT catalyst for the selective oxidation of benzyl alcohol is shown to be that prepared using colloidal synthesis and immobilization with PVA as a stabilizer, which has markedly superior catalytic activity compared to catalysts prepared by deposition-precipitation, adsorption, and dry impregnation methods. Au-Pd NPs stabilized by graphene oxide sheets and immobilized on Ti-NT has also been studied and while not optimum shows promising catalytic activity. The superior catalytic activity of the catalysts prepared by colloidal synthesis is attributed to the high metal dispersion on the external surfaces of Ti-NT, the narrow particle size distribution, and the high degree of Au-Pd alloying. This work also demonstrates that in the adsorption method of preparation using HAuCl〈sub〉4〈/sub〉.3H〈sub〉2〈/sub〉O and PdCl〈sub〉2〈/sub〉 precursors, the uptake of Pd ions in solution by Ti-NT is proportional to the sodium content in Ti-NT, which implies that Na is involved in an ion-exchange reaction with Pd ions.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118308824-ga1.jpg" width="254" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 29 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Shuang Zhu, Lingju Guo, Pan Li, Bin Zhang, Gaofeng Zhao, Tao He〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The adsorption of CO〈sub〉2〈/sub〉 on the surface of heterogeneous catalysts is crucial for the subsequent photoreduction reactions. As the direct one-electron reduction of CO〈sub〉2〈/sub〉 is extraordinarily difficult because of the –1.9 V reduction potential, adsorption induced CO〈sub〉2〈/sub〉 bending to form 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si4.gif" overflow="scroll"〉〈mrow〉〈msubsup〉〈mrow〉〈mi mathvariant="normal"〉C〈/mi〉〈mi mathvariant="normal"〉O〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉δ〈/mi〉〈mo〉−〈/mo〉〈/mrow〉〈/msubsup〉〈/mrow〉〈/math〉 is considered one efficient approach to decrease the overpotential of the intermediate formation during CO〈sub〉2〈/sub〉 reduction. However, it is still unclear what material and surface are in favor of the formation of adsorption-induced bending of CO〈sub〉2〈/sub〉, which is important for the design of active surfaces. Here we perform the first principle study on the adsorption of CO〈sub〉2〈/sub〉 on the surface of some typical photocatalysts and co-catalysts. It is found that the CO〈sub〉2〈/sub〉 bending upon adsorption can only occur on certain crystal surfaces of some materials, even on the perfect surface without any defects. If the exposed crystal surface has a linear metal-oxygen-metal (M〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉M) structure, the carbonate-like configuration upon CO〈sub〉2〈/sub〉 adsorption may be easier to be formed than that on the other exposed surfaces. TiO〈sub〉2〈/sub〉 (001), CeO〈sub〉2〈/sub〉 (111), CeO〈sub〉2〈/sub〉 (110) and MgO (100) seem more attractive among all the surfaces under study, as the bent CO〈sub〉2〈/sub〉 configuration on these two surfaces are more stable than the linear one. Moreover, the barrier that CO〈sub〉2〈/sub〉 changes from linear configuration to bent is relatively small. Our results are in good agreement with the experimental results that TiO〈sub〉2〈/sub〉 (001) and MgO (100) exhibit high photocatalytic activity.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉The bending of CO〈sub〉2〈/sub〉 upon adsorption can only occur on certain crystal surfaces of some materials, such as the exposed crystal surface has a linear metal-oxygen-metal structure, corresponding to the active surface.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118309374-ga1.jpg" width="255" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Géraldine L.-M. Léonard, Artium Belet, Bruno Grignard, Cédric Calberg, Bernard Gilbert, Christine Jérôme, Benoît Heinrichs〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Different types of heterogeneous catalysts designed for a cyclocarbonation reaction between an epoxidized source and CO〈sub〉2〈/sub〉 under supercritical conditions have been synthesized. The process implied a quaternization step where a (haloalkyl)trimethoxysilane reacted with tributylamine leading to a tributyl(trimethoxysilylalkyl)ammonium halide, with iodine and bromine as halogens. Then, a grafting step onto commercial fumed silica through condensation reaction between the silane part and Si-OH surficial groups provided the immobilized catalyst. The efficiency of grafting has been validated by liquid 〈sup〉1〈/sup〉H NMR, solid 〈sup〉29〈/sup〉Si NMR and TG-DSC-MS analyzes. The benchmark cyclocarbonation reaction of polyethylene glycol diglycidylether at 80 °C and 100 bar during 4 h showed that the best immobilized catalyst was tributylpropylammonium iodide (IC3Q-EH5). It has also been shown that immobilization provided -surprisingly !- better conversions than the corresponding homogeneous catalyst’s: this phenomenon has been explained through an epoxide-ring-opening activating effect thanks to Si-OH surficial groups. Furthermore, kinetic studies performed by 〈em〉in situ〈/em〉 Raman spectroscopy on IC3Q-EH5 showed that temperature had a strong influence on the yield of the reaction while CO〈sub〉2〈/sub〉 pressure had only a small effect. Recycling of the catalyst has also been considered, but no precise conclusions could be conducted because of the high catalyst dispersion. Finally, the addition of a fluorinated alcohol co-catalyst allowed obtaining a similar yield but at 80 °C and 55 bar during only 2,5 h with the best candidate.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118308782-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 29 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Kang-Qiang Lu, Xin Lin, Zi-Rong Tang, Yi-Jun Xu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Photocatalytic water splitting for hydrogen evolution provides an attractive strategy for clean, low-cost, and environment-friendly production of hydrogen from solar energy. Here, the film composite of Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanoparticles decorated well-defined one-dimensional (1D) silicon nanowires arrays (SiNWs@Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉) are constructed by employing SiNWs arrays as a building block 〈em〉via〈/em〉 a facile calcination approach. In comparison with bare SiNWs arrays, the resultant SiNWs@Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 arrays composite exhibits distinctly enhanced photocatalytic performance for the evolution of hydrogen. The enhanced photoactivity is attributed to the formation of a direct Z-scheme band alignment in the SiNWs@Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 film composite, which results in an improved spatial separation and migration of photoinduced electron-hole pairs as compared to bare SiNWs under light irradiation. Our work is anticipated to promote ongoing interest in the design of high-performance artificial 1D-based Z-scheme film photocatalysts with enhanced performance.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉A Z-scheme photocatalytic system consisting of well-dispersed Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanoparticles grown on vertically aligned 1D SiNWs arrays have been fabricated, which shows simultaneously improved photoactivity and photostability for H〈sub〉2〈/sub〉 evolution.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118308903-ga1.jpg" width="312" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: Available online 26 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Miao Lai, Jie Zhao, Qingcai Chen, Shuaijun Feng, Yujie Bai, Yingxuan Li, Chuanyi Wang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the photocatalytic volatile organic compounds (VOCs) degradation, the accumulation of intermediate products on the surface of catalysts could cause a decrease in activity through retarding reactant (e.g. O〈sub〉2〈/sub〉) supply to surface active sites. Herein, Bi decorated TiO〈sub〉2〈/sub〉 photocatalysts (Bi/TiO〈sub〉2〈/sub〉) for photocatalytic toluene degradation were prepared and systematically studied. It is found that metallic Bi modification improves the ability of photocatalysts to capture O〈sub〉2〈/sub〉. As a result, the activities of the Bi/TiO〈sub〉2〈/sub〉 photocatalysts are obviously higher than that of the TiO〈sub〉2〈/sub〉 for photocatalytic toluene degradation, and the productions of photogenerated reactive oxygen species (〈sup〉〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/rad"〉〈/sup〉O〈sub〉2〈/sub〉〈sup〉−〈/sup〉 and H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉) over the Bi/TiO〈sub〉2〈/sub〉 photocatalysts are almost equal to that over the TiO〈sub〉2〈/sub〉 despite the fact that the separation efficiency of photoinduced charge carriers is decreased after the addition of Bi. Adsorbed benzaldehyde is the main surface intermediate on the surface of the Bi/TiO〈sub〉2〈/sub〉 photocatalysts, whereas plenty of more readily oxidized aliphatic carboxylate species was monitored on the surface of the TiO〈sub〉2〈/sub〉, which can be attributed to insufficient O〈sub〉2〈/sub〉 supply to the TiO〈sub〉2〈/sub〉 surface. This further indicates the positive role of the promoted O〈sub〉2〈/sub〉 supply by Bi in the photocatalytic toluene degradation. The present work offers a new window for addressing the catalyst deactivation in the photocatalytic VOCs degradation.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Metallic Bi modification improves the ability of photocatalysts to capture O〈sub〉2〈/sub〉, thereby accelerating the removal of surface intermediates.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118316377-ga1.jpg" width="244" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: Available online 26 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Bastien O. Burek, Jana Timm, Detlef W. Bahnemann, Jonathan Z. Bloh〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Sacrificial electron donors are frequently used in photocatalytic reactions to enhance the performance of the reaction, typically short-chain alcohols as well as their respective aldehydes and acids are used. This study focuses on the differences between the individual electron donors regarding their oxidation rates, mechanistic pathways, the influence of the intermediates and their direct impact on the H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 generation. The individual H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 formation rates of 16 different electron donors, photonic and faradaic efficiencies for H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 production are carefully discussed. Furthermore, a new multi-reaction pathway for 〈em〉t〈/em〉-butanol oxidation is postulated and critically examined.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092058611830912X-ga1.jpg" width="478" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): N.T.T Nguyen, F. Matei-Rutkovska, M. Huchede, K. Jaillardon, G. Qingyi, C. Michel, J.M.M. Millet〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Catalysts able to selectively dehydrate 2,3-butanediol into butadiene have been designed. These catalysts, based on rare-earth orthophosphates showed that 58% selectivity to butadiene could be obtained at total conversion at only 300 °C, and were relatively stable. While the deactivation could be delayed by addition of water to the gas feeds, it could not be avoided and a regeneration was necessary. This regeneration was achieved by a simple heat treatment under air for a few hours at 450 °C. All results showed that Lewis acid sites corresponding to the rare earth cations are involved in the dehydration of 2,3-butanediol into butadiene. This dehydration occurs with the intermediate formation of 3-buten-2ol, probably over acid-base concerted sites and the subsequent dehydration of 3BDOL to butadiene over weak Brønsted acid sites. All types of sites appear present on the catalysts surface and distributed in a relatively optimal way.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118309313-ga1.jpg" width="258" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Svetlana A. Yashnik, Gleb A. Urzhuntsev, Andrei I. Stadnichenko, Dmitry A. Svintsitskiy, Arcady V. Ishchenko, Andrei I. Boronin, Zinfer R. Ismagilov〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉We studied on the function of Pd species located in mesopores and inside zeolite channels (micropores) of the montmorillonite-modified zeolite catalyst for the hydrodesulfurization of diesel fraction with 350 ppm of sulfur as DBT, 4-MDBT, and 4,6-DMDBT. It was shown that the ex-dihydrogentetrachloropalladate impregnated catalyst as well as the ex-tetraamminepalladium(II) chloride ion-exchanged catalyst have high efficiency of sulfur removal from the diesel fuel in temperature range 280–300 〈sup〉о〈/sup〉C.〈/p〉 〈p〉The sulfur tolerance of catalyst depended on the method of Pd adding. The catalyst prepared by ion-exchange with tetraamminepalladium chloride solution exhibited the highest sulfur tolerance. According to FTIR of adsorbed CO, this catalyst contains a small Pd metal atoms or cluster in electron-deficient state inside zeolite channels. They probably ensure sulfur tolerance due to hydrogen spillover.〈/p〉 〈p〉The montmorillonite addivite significantly modifies performance of the Pd-Zeolite catalyst in hydrotreating of diesel fraction. It leads to a decrease of cracking function, while those of hydrogenolysis of sulfurorganic molecules and hydrogenation of aromatic molecules are strengthened in comparison with the unmodified catalyst. This effect is explained by the change of acidic properties of the catalyst, limitations of diffusion of various molecules into the zeolite channels, and diffusion of Pd from the zeolite channels.〈/p〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118313385-ga1.jpg" width="388" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Ce Yang, Zhenwei Wu, Guanghui Zhang, Huaping Sheng, Jun Tian, Zhengli Duan, Hyuntae Sohn, A. Jeremy Kropf, Tianpin Wu, Theodore R. Krause, Jeffrey T. Miller〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Silica supported Pd (∼2 nm), Pd〈sub〉3〈/sub〉Fe (∼2 nm) and Pd〈sub〉3〈/sub〉Fe_large (∼12 nm) catalysts were synthesized and tested for propane dehydrogenation at 510 °C. At the 10% conversion, Pd and Pd〈sub〉3〈/sub〉Fe catalysts exhibited propylene selectivity of 45% and 94%, respectively. Moreover, the latter showed a turnover rate (TOR) of 0.2 s〈sup〉−1〈/sup〉, which is five times higher than that of the Pd catalyst (0.04 s〈sup〉−1〈/sup〉). Pd K edge XAS, XRD, and CO adsorbed IR were used to characterize the geometric structure of the catalysts. By combined comparison of XRD and XAS spectra of Pd〈sub〉3〈/sub〉Fe and Pd〈sub〉3〈/sub〉Fe_large catalysts, we successfully identified the crystalline phase in the 2 nm Pd〈sub〉3〈/sub〉Fe catalyst. The CO adsorbed IR suggests that the formation of Pd〈sub〉3〈/sub〉Fe breaks the ensemble of Pd, which is responsible for the increase of selectivity. The Pd L edge XAS was used to characterize the electronic structure of the catalysts. The Pd〈sub〉3〈/sub〉Fe catalyst exhibits an increase of the edge energy compared with the Pd catalyst, which indicates the change of d-band structure in the bimetallic catalyst. The change in the electronic structure is likely the reason for the increase in TOR.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118311076-ga1.jpg" width="374" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Cristian Ledesma, Eduardo López, Trifon Trifonov, Ángel Rodríguez, Jordi Llorca〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The steam reforming and oxidative steam reforming of dimethyl ether (DME) were tested at 573–773 K over a CuZn/ZrO〈sub〉2〈/sub〉 catalyst in microreactors with three different types of channels: ceramic square channels with side lengths of 900 and 400 μm, and silicon microchannels of 2 μm of diameter. The channels were first coated with ZrOCl〈sub〉2〈/sub〉 (ceramic channels) or Zr(i-PrO)〈sub〉4〈/sub〉 (silicon microchannels) and calcined at 773 K for 2 h to obtain a homogeneous and well-adhered ZrO〈sub〉2〈/sub〉 layer, as determined by SEM, and then Cu and Zn (Cu:Zn = 1:1 M, 20 wt% total metal) were co-impregnated. Operation at highly reduced residence time (10〈sup〉−3〈/sup〉 s) while achieving hydrogen yields similar to those recorded over the ceramic channels was possible for the silicon microchannels due to the three orders of magnitude increased contact area. In addition, the amount of catalyst used for coating the silicon microchannels was two orders of magnitude lower with respect to the conventional ceramic channels. Outstanding specific hydrogen production rates of 0.9 L〈sub〉N〈/sub〉 of H〈sub〉2〈/sub〉 per min and cm〈sup〉3〈/sup〉 of reactor volume were achieved as well as stable operation for 80 h, which demonstrates the feasibility of using on-site, on-demand hydrogen generation from DME for portable fuel cell applications.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118302062-fx1.jpg" width="257" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Matthew M. Yung, Anne K. Starace, Michael B. Griffin, Jonathan D. Wells, Ryan E. Patalano, Kylie R. Smith, Joshua A. Schaidle〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Zeolite catalysts used for biomass catalytic fast pyrolysis (CFP) deactivate rapidly, similar to a fluidized catalytic cracking (FCC) catalyst used in refining. To operate effectively when there is rapid deactivation, biomass CFP can take place in a riser FCC-style reactor in which the catalyst has a short contact time (seconds) with reactants before it is regenerated. The regeneration, therefore, has two major needs for effective operation: 1) heat balance, since the heat required for the CFP reactions is brought into the reactor by the hot catalyst and 2) relatively short (minutes) regeneration to restore the catalyst activity to be near its initial state. In order to understand effective conditions to regenerate zeolites used for CFP, a series of experiments were performed to determine the effect of regeneration temperature on the activity of ZSM-5 (SiO〈sub〉2〈/sub〉/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 = 30). After use for pine pyrolysis vapor upgrading, the catalyst was oxidized in 4% O〈sub〉2〈/sub〉 at temperatures between 500–700 °C and reevaluated for the upgrading of pine pyrolysis vapors to assess the extent of regeneration. Additional testing was performed using ethylene aromatization as a surrogate reaction to probe regeneration efficiency. Regeneration experiments were performed for either a fixed length of time (20 min) or until there was no further CO〈sub〉2〈/sub〉 measured in the effluent gas. Results from the ethylene aromatization reactions were shown to serve as an excellent surrogate for CFP reactivity and indicated that the use of model compound studies can effectively be used to understand reaction and regeneration processes from biomass CFP. Both sets of results indicate that a spent ZSM-5 used for biomass CFP could be fully regenerated at 650°C and 700°C within 20 min, whereas regeneration temperatures of 550 °C and 600 °C required longer regeneration temperatures and in the case of regeneration at 500 °C, there may be coke species that are not removed and the catalyst activity may never be fully restored. Characterization by pyridine diffuse reflectance infrared spectroscopy, thermogravimetric analysis coupled with infrared spectroscopy, and N〈sub〉2〈/sub〉 physisorption showed that higher regeneration temperatures are more effective for restoring Brønsted acid sites and catalyst mesoporosity by rapidly removing aromatic coke deposits. Additionally, regeneration at 650 °C and 700 °C led to a slightly higher total porosity as compared to the pristine catalyst, which was attributed to the formation of additional mesoporosity from catalyst steaming.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118307491-ga1.jpg" width="356" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 19 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Xiaoyan Liu, Guojun Lan, Panpan Su, Lihua Qian, Tomas Ramirez Reina, Liang Wang, Ying Li, Jian Liu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The hydrogenation of levulinic acid to γ-valerolactone with water as solvent is a crucial reaction for producing fine chemicals. However, the development of highly stable catalysts is still a major challenge. Here, we prepared a Ru nanoparticles incorporated in mesoporous-carbon (Ru-MC) catalyst to achieve high stability in acidic aqueous medium. The Ru-MC showed excellent catalytic performance (12024 h〈sup〉−1〈/sup〉 turnover frequency) in the hydrogenation of LA-to-GVL. Compared with Ru supported on mesoporous carbon catalyst (Ru/MC) prepared by conventional wet impregnation method, the Ru-MC showed excellent reusability (more than 6 times) and thermal stability (up to 600 °C). Based on H〈sub〉2〈/sub〉-TPR-MS characterization, it was proposed that the incorporated structure significantly increased the interaction between Ru nanoparticles and carbon support, which effectively prevent the leaching and sintering of Ru nanoparticles and contributed to increased high reusability and thermal stability of the Ru-MC.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118316754-ga1.jpg" width="117" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Xiaoyin Chen, Yimeng Lyu, Uzoma Nwabara, Johannes W. Schwank〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To elucidate the reactions involved in the three-way catalyst under stoichiometric conditions, the reactivity of CO + NO has been studied by continuous flow and surface reactions over Pd supported on Ce〈sub〉0.75〈/sub〉Zr〈sub〉0.25〈/sub〉O〈sub〉2〈/sub〉 (CZO) and Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 model catalysts with different Pd particles sizes and oxidation states. Pd/CZO showed higher activity with complete NO removal at 125 °C than Pd/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 at 300 °C As a primary by-product, N〈sub〉2〈/sub〉O was produced on both catalysts prior to reaching complete CO conversion in a 1:1 NO/CO feed ratio. NO inhibition through N〈sub〉2〈/sub〉O formation was intensified when 2:1 NO/CO feed ratio was used, where the complete CO conversion can’t be achieved during the course of the reaction. When 1:1 NO/CO feed ratio was used over Pd/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, a concave feature in the CO light-off curve was observed, where the CO light-off curve showed a downward inflections after complete NO conversion had been reached, and then started to increase again with further increase in temperature. The inflection of CO conversion coincided with the maximum yield of N〈sub〉2〈/sub〉O vs. reaction temperature. It was also found that the CO + NO reactivity was affected by the Pd oxidation state and particles size. 〈em〉in situ〈/em〉 DRIFT experiments showed that the formation of NCO and NCO-derived N〈sub〉2〈/sub〉O intermediate species is closely related to the inflection of CO conversion. A pathway of N〈sub〉2〈/sub〉O formation via the NCO intermediate species has been proposed to be responsible for the fallback in CO conversion when the reaction temperature increased, as both interactions of “NCO〈sub〉ad〈/sub〉 + N〈sub〉ad〈/sub〉” and “NCO〈sub〉ad〈/sub〉 + NO〈sub〉ad〈/sub〉," which produce N〈sub〉2〈/sub〉 and N〈sub〉2〈/sub〉O, respectively, consume NO but generate CO.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118309271-ga1.jpg" width="254" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Gokhan Celik, Saurabh A. Ailawar, Seval Gunduz, Paul L. Edmiston, Umit S. Ozkan〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The widespread utilization and commercialization of hydrodechlorination (HDC) over Pd-based catalysts as a remediation technique has been impeded because of catalyst deactivation problems such as formation of carbonaceous deposits under the reductive environment of HDC. In this study, we investigated the use of a novel animated material, swellable organically-modified silica (SOMS), as a catalyst scaffold for HDC of trichloroethylene (TCE) to develop a catalytic system resistant to carbon formation. The state of aggregation of adsorbed TCE on Pd/SOMS was characterized. It was found that the unique nature of SOMS scaffold caused condensation of adsorbents in the SOMS matrix. This is of particular importance considering the fact that the increase of local concentration of reactants due to condensation may enhance the kinetics of catalytic reactions. To determine the resistance to the formation of carbonaceous materials under reaction conditions, in-situ vibrational spectroscopy experiments (diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and laser Raman spectroscopy) were undertaken over Pd-incorporated SOMS in the absence and presence of water vapor in the reactant stream. The commonly used HDC catalyst Pd/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 was also studied for comparison purposes. Formation of carbonaceous deposits of different nature were observed over Pd/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 whereas no detectable carbon formation was observed over Pd/SOMS. It was confirmed that surface hydroxyl groups which are in basic character act as coking agents. The carbon formation resistant behavior of Pd/SOMS is closely related to the nature and low concentration of surface hydroxyl groups.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118305601-fx1.jpg" width="243" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 19 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Ksenia E. Salnikova, Valentina G. Matveeva, Yurii V. Larichev, Alexey V. Bykov, Galina N. Demidenko, Irina P. Shkileva, Mikhail G. Sulman〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report the hydrogenation of furfural (FF) to furfuryl alcohol (FA) with Pd-containing catalysts stabilized by hypercrosslinked polystyrene (HPS). FF is one of the major ingredients of biooil produced by biomass pyrolysis, while FA is a source of value-added chemicals, thus, creating an effective path from biomass to important compounds. Different palladium precursors (PdCl〈sub〉2〈/sub〉(CH〈sub〉3〈/sub〉CN)〈sub〉2〈/sub〉, Pd(CH〈sub〉3〈/sub〉COO)〈sub〉2〈/sub〉 ) were used for the catalysts synthesis. The nature of the precursor influences the size of palladium nanoparticles. The TEM and SAXS data showed that when using PdCl〈sub〉2〈/sub〉(CH〈sub〉3〈/sub〉CN)〈sub〉2〈/sub〉, a monomodal distribution of particles size with mean diameter 5.4 ± 1.2 nm was observed, whereas for Pd(CH〈sub〉3〈/sub〉COO)〈sub〉2〈/sub〉, multimodal particle size distribution with the mean particle sizes up to 13.8 ± 5.4 nm was observed. The comparison of the catalytic activities of Pd-containing catalysts indicated that the more disperse sample of palladium showed higher values of FF conversion and selectivity to FA because of small particles.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118312331-ga1.jpg" width="279" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Deniz Kaya, Dheerendra Singh, Serkan Kincal, Deniz Uner〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The enhanced rates of reduction and re-oxidation of ceria in the presence of Pd, was investigated on both bulk ceria as well as ceria deposited over γ-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉. Pd addition and surface area enhancement by γ-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 decreased the reduction temperature of CeO〈sub〉2〈/sub〉 as monitored by temperature programmed reduction (TPR) in H〈sub〉2〈/sub〉. Temperature programmed oxidation (TPO) and temperature programmed thermal decomposition (TPtD) measurements revealed similar results of more favorable temperatures of oxidation and thermal decomposition. Pd assisted oxygen removal from CeO〈sub〉2〈/sub〉 through a reverse spillover process as monitored by the temperature programmed thermal decomposition experiments was evident from the decomposition temperature of PdO to Pd. The adsorption microcalorimetry measurements at 323 K revealed that hydrogen adsorption initiated over Pd extends to CeO〈sub〉2〈/sub〉 by migration (or spillover). Oxygen adsorption, however, was restricted to Pd surface at 323 K. Also at the same temperature, initial H〈sub〉2〈/sub〉O adsorption was accompanied by very high heats at low coverages indicating surface oxidation. At higher pressures, H〈sub〉2〈/sub〉O adsorption extended to coverages representative of the monolayer over γ-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, the heats of adsorption measured at these high coverages corresponded to water condensation.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118305340-fx1.jpg" width="98" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Dimitriy Vovchok, James Tata, Ivan Orozco, Feng Zhang, Robert M. Palomino, Wenqian Xu, Leah Harper, Sheima J. Khatib, José A. Rodriguez, Sanjaya D. Senanayake〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cu/ZSM-5 catalysts were found to exhibit activity for the water-gas shift (WGS) reaction at temperatures over 300 °C. Nominal Cu loadings of 1, 5, and 10% on ZSM-5 were synthesized using the wetness impregnation technique and evaluated for WGS activity; with a clear trend favoring increased Cu loading (10% 〉 5% 〉 1%). X-ray diffraction (XRD) confirmed high dispersion of small Cu at low loadings while CuO crystallized at higher loadings. 〈em〉In-situ〈/em〉 XRD showed an evolving transformation of CuO → Cu metal, with the appearance of a metallic copper phase at the optimum reaction conditions, particularly at the highest copper loading. 〈em〉In-situ〈/em〉 diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) revealed the ability of the surface to activate H〈sub〉2〈/sub〉O and adsorb CO, by the presence of HO-Al/Si and transient CO-Cu〈sup〉+〈/sup〉 surface species in two distinct locations (5 membered rings (2157 cm〈sup〉−1〈/sup〉) 〈em〉vs〈/em〉 channel intersections (2138 cm〈sup〉−1〈/sup〉) within the ZSM-5 framework, that likely formed during the CuO → Cu transition. The lowest loaded Cu-ZSM-5 (1%) showed only the 5 membered ring occupied Cu〈sup〉+〈/sup〉 while the higher loadings showed both, with comparable temperature dependent behavior for the channel intersection Cu〈sup〉+〈/sup〉. The amounts of Cu〈sup〉+〈/sup〉 species in each location were observed to be dependent on temperature while the 5-membered ring showed better thermal stability. 〈em〉In-situ〈/em〉 ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) was used to further confirm the gradual changes to the chemical state of copper (CuO → Cu〈sub〉2〈/sub〉O → Cu) under reaction conditions.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118312112-ga1.jpg" width="218" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 14 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Clara García, Stephan Pollitt, Marte van der Linden, Vera Truttmann, Christoph Rameshan, Raffael Rameshan, Ernst Pittenauer, Günter Allmaier, Peter Kregsamer, Michael Stöger-Pollach, Noelia Barrabés, Günther Rupprechter〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Using oxide supported atomically precise gold nanoclusters is an emerging field in heterogeneous catalysis. Such well-defined nanocatalysts represent a rather new model system enabling fundamental insights in catalytic reactions. In the present work, the stability of Au〈sub〉25〈/sub〉 and Au〈sub〉144〈/sub〉 clusters, supported either on TiO〈sub〉2〈/sub〉 or SiO〈sub〉2〈/sub〉, was examined upon thermal air pretreatment and, for the first time, upon liquid phase oxidation reaction. A pronounced influence of the support (TiO〈sub〉2〈/sub〉 vs. SiO〈sub〉2〈/sub〉) and cluster size (Au〈sub〉25〈/sub〉 vs. Au〈sub〉144〈/sub〉) was revealed by XAS, DRS and STEM. Upon pretreatment, Au〈sub〉144〈/sub〉 was more stable which may be related to its specific cluster core structure and staple configuration. The catalytic properties in liquid phase cyclohexane oxidation were clearly size dependent, with Au〈sub〉144〈/sub〉 yielding higher TOF values, particularly in the case of SiO〈sub〉2〈/sub〉 supported catalysts. However, with respect to selectivity, TiO〈sub〉2〈/sub〉 supported catalysts led to higher KA production than SiO〈sub〉2〈/sub〉 supported ones. This can be explained by the different reaction pathways, as observed by 〈em〉in situ〈/em〉 ATR. HERFD-XAS measurements of Au〈sub〉144〈/sub〉/TiO〈sub〉2〈/sub〉 catalysts revealed a pronounced cluster structure modification towards bulk gold during the reaction, in contrast to a high stability of Au〈sub〉144〈/sub〉/SiO〈sub〉2〈/sub〉. This study demonstrates the important role the support material has on the reactivity and stability of gold nanoclusters, which is key for their catalytic function.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118315232-ga1.jpg" width="488" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 26 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Thuan-Nguyen Pham-Truong, Christine Ranjan, Hyacinthe Randriamahazaka, Jalal Ghilane〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Seeking for highly efficient and cost-effective catalysts towards electrochemical activation of small molecules is the key process in the development of renewable technologies. In this work the ionic liquid has been proposed as a promising candidate for elaborating of hybrid materials for multi-purposes in the fields of electrocatalysis. Precisely, the polymer brushes based ionic liquid, poly(imidazolium), were used as a platform for host guesting carbon-dots material and their electrocatalytic activity towards the oxygen reduction reaction was evaluated. The obtained results demonstrate that the presence of the poly(IL) shifts the ORR performance over carbon dots from 2 electron pathway, with hydrogen peroxide as the main product, to nearly 4 electron pathway. Thus, a switch from hydrogen peroxide generation (〉80%) to water production is obtained in the presence of the poly(IL) layer over a broad potential range. This synergetic effect is correlated to the chemical structure and the morphology of the immobilized polymer ionic liquid. Finally, the poly(IL) was demonstrated to be a powerful strategy for boosting the catalytic activity for a given carbon-dots catalyst towards efficient 4 electron ORR.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118312653-ga1.jpg" width="257" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Bryan J. Hare, Debtanu Maiti, Swetha Ramani, Adela E. Ramos, Venkat R. Bhethanabotla, John N. Kuhn〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Perovskite-type oxides show clear potential for thermochemical solar-driven CO〈sub〉2〈/sub〉 conversion. These materials exhibit the exact characteristics (e.g., structural endurance and high oxygen redox capacity and exchange kinetics) required by the low temperature reverse water-gas shift chemical looping process. In this study, the La〈sub〉0.75〈/sub〉Sr〈sub〉0.25〈/sub〉FeO〈sub〉3〈/sub〉 (LSF) perovskite oxide was combined with various supports, including popular redox materials CeO〈sub〉2〈/sub〉 and ZrO〈sub〉2〈/sub〉 along with more abundant alternatives such as Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, SiO〈sub〉2〈/sub〉, and TiO〈sub〉2〈/sub〉, for potential application at industrial scale. Supporting LSF on SiO〈sub〉2〈/sub〉 by 25% mass resulted in the largest increase of 150% in CO yields relative to unsupported perovskite after reduction at 600 °C. This is a result of significantly reduced perovskite oxide particle size confirmed by SEM/TEM imaging and crystallite size from Scherrer analyses of XRD patterns. Due to solid-state reactions, minor secondary phases were observed at the LSF:support interface when using SiO〈sub〉2〈/sub〉 or TiO〈sub〉2〈/sub〉. Oxygen vacancy formation occurred only on the perovskite oxide phase, as suggested by low temperature experiments and consistent with density functional theory calculations. The role of each metal oxide support towards suppressing or enhancing the CO〈sub〉2〈/sub〉 conversion is elucidated. Through utilization of SiO〈sub〉2〈/sub〉 as support, the reverse water-gas shift chemical looping process using perovskite-based composites was significantly improved.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118307223-fx1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Ning Yu, Muhammad Mahfuzur Rahman, Jixiang Chen, Junming Sun, Mark Engelhard, Xavier Isidro Pereira Hernandez, Yong Wang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Steam reforming of simulated bio-oil (ethanol, acetone, phenol, and acetic acid) and phenol has been studied on K-Ni-Cu-Mg-Ce-O/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 composite catalysts. Complementary characterization techniques, such as nitrogen sorption, XRD, H〈sub〉2〈/sub〉-TPR, H〈sub〉2〈/sub〉-TPD, CO-TPD, CO-DRIFTS, and in situ XPS, were used to correlate surface structure and functionality to catalytic performance of potassium (K) doped catalysts. K doping of the Ni-Cu-Mg-Ce-O/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 catalyst created a Ni°/Ni〈sup〉2+〈/sup〉 mixed active phase, which not only enhanced steam reforming activity, but also suppressed the methanation reaction. In addition, K doping changed the surface acid-basic properties of the catalyst, which instead favor the gasifcation and water-gas shift reactions. With the combination of these effects, K doping of Ni-Cu-Mg-Ce-O/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 catalysts led to higher C1 yield and much lower methane formation, favoring hydrogen production in steam reforming of both phenol and simulated bio-oil.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118304097-fx1.jpg" width="308" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Gwang-Nam Yun, So-Jin Ahn, Atsushi Takagaki, Ryuji Kikuchi, S. Ted Oyama〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The hydrodeoxygenation (HDO) of the cyclic five-membered ester γ-valerolactone (GVL) was studied on a Ni〈sub〉2〈/sub〉P/MCM-41 catalyst. The activation of the passivated catalyst in H〈sub〉2〈/sub〉 was followed by in situ near-edge X-ray absorption spectroscopy (NEXAFS) which indicated reduction of the catalyst after 3 h at 550 °C. In situ infrared measurements under reactive H〈sub〉2〈/sub〉 and inert N〈sub〉2〈/sub〉 showed the presence of adsorbed GVL and pentanoic acid (PA) as the most abundant surface intermediates. The results supported a previous reaction network that showed that ring-opening of GVL to produce pentanoic acid was the rate-determining step. This was confirmed by transient infrared measurements which showed that the number of CH〈sub〉2〈/sub〉 groups in the adsorbed species increased under H〈sub〉2〈/sub〉 flow, consistent with PA formation but not an alkoxide. The results provide understanding of the key steps in the reaction mechanism.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118313129-ga1.jpg" width="241" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Peng He, Aiguo Wang, Shijun Meng, Guy M. Bernard, Lijia Liu, Vladimir K. Michaelis, Hua Song〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The presented work investigates the co-aromatization of methane and propane over Zn/HZSM-5 catalysts. The impact of Al sites, such as framework and extra-framework aluminum (EFAL) sites, on the methane participation pathway during the co-aromatization reaction is explored. The Al sites in the catalysts are manipulated by using ZSM-5 support materials with variable SiO〈sub〉2〈/sub〉/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 molar ratios. Post-synthetic treatments, such as the ammonium hexafluorosilicate (AHFS) treatment to remove EFAL and the steam treatment to convert some of the framework Al sites to EFAL sites, are also employed to prepare catalysts and evaluate the contribution of these Al sites to the methane participation pathway. A higher concentration of Al in the catalysts would facilitate the methane participation in the phenyl ring formation. An average carbon number increment of 0.93, a substitution index reduction of 0.028, and an enhanced aromatic carbon fraction by 0.036 among the product molecules are witnessed over the Zn/HZSM-5 (23:1) catalyst during the co-aromatization reaction. This phenomenon is further enhanced when some of the framework Al atoms are converted to the EFAL sites by the steam treatment. The changes of substitution index and aromatic carbon fraction are expanded to 0.045 and 0.055. When the total Al concentration is low in the catalyst, however, the increased EFAL site number at the cost of framework Al sites does not improve methane participation, indicating that the framework Al sites are also crucial for the methane participation. The chemical environment of the Al sites in the catalysts is probed by 〈sup〉27〈/sup〉Al solid-state NMR and XAS studies. The NH〈sub〉3〈/sub〉-TPD and DRIFTS investigations of the catalysts demonstrate that the framework Al sites and the EFAL sites are closely related to the Brönsted and Lewis acid sites, respectively. The TEM and XRD studies reveal the intact crystalline structure of the catalysts upon the AHFS and steam treatments. The impact of the Al environments on the methane participation pathway in the co-aromatization reaction may be due to the acid properties of the catalysts.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉The inframwork 〈sup〉[4]〈/sup〉Al and extraframework 〈sup〉[6]〈/sup〉Al sites in Zn/HZSM-5 catalysts are probed by 〈sup〉27〈/sup〉Al SSNMR. The presence of extraframework Al sites enhances methane participation into phenyl ring formation during its co-aromatization with propane.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118306710-fx1.jpg" width="486" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): C.E. Kliewer, S.L. Soled, G. Kiss〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Deactivation mechanisms for a rhenium-promoted titania-supported cobalt catalyst are investigated during Fischer-Tropsch (FT) synthesis. Bench-scale reactor tests, chemisorption studies, thermogravimetric analyses (TG), and transmission electron microscopy (TEM) are used to probe environmental effects on catalytic activity.〈/p〉 〈p〉Bench-scale reactor studies show a steady decrease in activity with time. While a fraction of this loss can be recovered with a low temperature reduction (rejuvenation) inside the reactor, multiple data indicate this phenomenon is primarily attributable to water-induced oxidation of small cobalt particles.〈/p〉 〈p〉Data from long-term FT runs indicate the presence of three non-rejuvenable deactivation mechanisms: metal agglomeration, strong metal-support interaction (SMSI), and mixed metal oxide formation. High conversion studies implicate byproduct water in the agglomeration process, and ex-situ TEM data conclusively reveals that growth occurs via a coalescence mechanism. Combined kinetic and chemisorption studies reveal that SMSI results from the gradual buildup of titania decoration on the surface of the active cobalt and is exacerbated with multiple rejuvenation cycles. TGA data indicate that mixed metal oxide formation occurs in long-duration, pilot plant runs. In all cases, the aggregate of reactor kinetic, chemisorption, TG, and TEM results point to chemically-assisted deactivation phenomena attributable to the byproduct water.〈/p〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Four deactivation mechanisms are observed in long duration (∼ 6 month) FT synthesis runs involving a Co-Re/TiO〈sub〉2〈/sub〉 catalyst: rejuvenable deactivation via small metal particle oxidation and non-rejuvenable deactivation by metal particle growth, strong metal-support interaction (SMSI), and mixed metal oxide formation. Of these, metal particle growth via a chemically-assisted byproduct water-based oxidation is the dominant reason for activity loss.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118305911-ga1.jpg" width="383" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Seval Gunduz, Doruk Dogu, Dhruba J. Deka, Katja E. Meyer, Anshuman Fuller, Anne C. Co, Umit S. Ozkan〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Solid electrolyte cells can be operated in three basic modes: fuel cell, electrolyzer and ion pump. In the fuel cell mode, a fuel such as hydrogen, CO and light hydrocarbons is electrochemically oxidized to generate power. Electrolyzer and ion pump modes, however, need application of power from an external source in order to perform the desired tasks. In this article, we present a brief overview of the studies that use an oxygen ion conducting electrolyte for catalytic applications, with two specific examples from our own studies: use of a solid electrolyte cell in the ion pump mode for alkane oxidative dehydrogenation and in the electrolyzer mode for CO〈sub〉2〈/sub〉 reduction. The solid electrolyte cell assembly used in these studies consists of a button cell containing yttria-stabilized zirconia solid oxide electrolyte, a modified strontium titanate (ST) catalyst as the working electrode, i.e., anode for the ODH reaction and cathode for the CO〈sub〉2〈/sub〉 reduction reaction, and a lanthanum strontium manganite (LSM) catalyst as the counter electrode.〈/p〉 〈p〉Physical properties of the titanate materials were studied using XRD, conductivity measurement and temperature-programmed oxidation with CO〈sub〉2〈/sub〉. Lanthanum doped strontium titanate (La〈sub〉0.2〈/sub〉Sr〈sub〉0.8〈/sub〉TiO〈sub〉3±〈/sub〉〈em〉〈sub〉δ〈/sub〉〈/em〉), with or without Cl, was seen to have a higher electrical conductivity compared to un-doped strontium titanate (SrTiO〈sub〉3〈/sub〉). Cl doping, however, was seen to improve the electrocatalytic activity for both ODH and CO〈sub〉2〈/sub〉 reduction reactions, giving higher yields of ethylene and CO compared to Cl-free La〈sub〉0.2〈/sub〉Sr〈sub〉0.8〈/sub〉TiO〈sub〉3±〈/sub〉〈em〉〈sub〉δ〈/sub〉〈/em〉. The comparison of the catalytic and electrocatalytic ODH reactions clearly pointed out that oxygen in ionic form was more selective to ethylene than molecular oxygen at similar conversion values.〈/p〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118314202-ga1.jpg" width="340" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Nurbanu Cakiryilmaz, Huseyin Arbag, Nuray Oktar, Gulsen Dogu, Timur Dogu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A new mesoporous catalyst support material was synthesized by incorporation of zirconia into the structure of MCM-41 through a one-pot procedure. Catalytic performances of MCM-41 and Zr incorporated MCM-41 (25Zr-MCM-41) supported Ni or Cu catalysts were investigated in steam reforming of acetic acid reaction, at 750 °C. Some deformation in the ordered pore structure of MCM-41 was observed as a result of Zr incorporation. The activity test results showed that the catalytic performances of the zirconia incorporated MCM-41 were more stable than the MCM-41 supported materials. The catalysts containing 5% and 10% Ni gave highly promising results to achieve high hydrogen selectivity. However, the performance of the catalysts containing 5% Ni was more stable. Comparison of performances of Cu and Ni based catalysts showed that Cu was not a good catalyst for the steam reforming reaction of acetic acid. In the presence of copper, mainly decarboxylation reaction of acetic acid took place, yielding large quantities of methane. Results proved that, 5% Ni impregnated 25Zr-MCM-41 was a highly promising catalytic material for hydrogen production through steam reforming of acetic acid.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118307247-fx1.jpg" width="260" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Qiang Zhang, Aravind Asthagiri〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We present a comparison study between the implicit and explicit solvation approach for density functional theory (DFT) predictions of the oxygen reduction reaction (ORR) activity on Pt (111) and other metal surfaces under acidic conditions. DFT calculations with a self-consistent polarizable continuum model implement in VASPsol results in more accurate predictions of onset potentials for Pt(111) than vacuum DFT calculations due to the extra stabilization of the surface intermediates (OOH*, O*, OH*). Implicit solvation also preserves the scaling relationship among ORR intermediates and volcano-shape activity relationships that correlate ORR onset potential or activity to the free energy absorption of O* or OH*. Moreover, VASPsol predicts variation in the solvation energies across different surfaces, suggesting the use of universal solvation corrections may not be valid. However, VASPsol exhibits significant weaker OH* solvation energies (by ∼ 0.4 eV) on Pt (111) compared to literature values using an explicit water bilayer and therefore underestimates the onset potential on Pt (111). We attribute this lack of OH* solvation energies by VASPsol to its inability to address hydrogen bonds and the absence of intermediate stabilization of the bilayer structure. Strategies to mitigate this problem, including tuning VASPsol parameters and a hybrid approach incorporating one to two water molecules, are also examined but not found to alleviate the underestimation of the solvation of OH*.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118310885-ga1.jpg" width="363" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Nathaniel Olson, Nitish Deshpande, Seval Gunduz, Umit S. Ozkan, Nicholas A. Brunelli〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The isomerization of glucose to fructose is an important step in the conversion of biomass to valuable fuels and chemicals. A key challenge for the isomerization reaction is achieving high selectivity towards fructose using recyclable and inexpensive catalysts. In this study, the isomerization of glucose to fructose is investigated through using imogolite nanotubes as a catalyst. Imogolite is a single-walled aluminosilicate nanotube characterized by surface areas of 200-400 m〈sup〉2〈/sup〉/g and pore widths near 1 nm. Imogolite is a highly tunable structure and can be modified through substitution of Si with Ge or through functionalization of methyl groups to the inner surface. These modifications change the surface properties of the nanotubes and enable tuning of the catalytic performance. Imogolite nanotubes are successfully used as a heterogeneous catalyst for the isomerization of glucose to fructose. Of the compositions tested, aluminosilicate imogolite is the most active material for the conversion of glucose, achieving a glucose conversion of 30% and a fructose selectivity of 45%. Catalyst recycling experiments reveals that organic content accumulates on the nanotubes that results in a minor reduction in conversion while maintaining similar catalytic selectivity. The catalyst can be washed with aqueous ammonia, allowing the productivity of fructose to be recovered. Overall, imogolite nanotubes are an active and tunable catalytic platform with moderate selectivity for the isomerization of glucose to fructose.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118313397-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 26 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Hiroya Okamoto, Masanori Kodera, Takashi Hisatomi, Masao Katayama, Tsutomu Minegishi, Kazunari Domen〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Precise engineering of the cocatalyst-photocatalyst interface and optimization of the cocatalyst dispersion are essential for improving the activity of particulate semiconductor photocatalysts. Herein, we report the effects of varying the conditions used to load cobalt oxide (CoO〈em〉〈sub〉x〈/sub〉〈/em〉) as a cocatalyst on the O〈sub〉2〈/sub〉 evolution activity of a particulate BaTaO〈sub〉2〈/sub〉N photocatalyst, based on trials in an aqueous silver nitrate solution under visible light irradiation. Annealing under an N〈sub〉2〈/sub〉 flow after loading the Co species increased the O〈sub〉2〈/sub〉 evolution rate threefold compared to that obtained following conventional annealing under an NH〈sub〉3〈/sub〉 flow. Subsequent annealing under an H〈sub〉2〈/sub〉 atmosphere exposed the BaTaO〈sub〉2〈/sub〉N surface as a result of the aggregation of CoO〈em〉〈sub〉x〈/sub〉〈/em〉 particles, and further enhanced the photocatalytic O〈sub〉2〈/sub〉 evolution by a factor of two, yielding an apparent quantum efficiency of 0.55% at 420 nm. These results indicate the importance of intimate contact between cocatalyst particles and the photocatalyst, as well as the necessity of exposing the photocatalyst surface to make it available for reduction reactions during photocatalytic water oxidation.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118314834-ga1.jpg" width="434" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 21 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Jonathan C. Espíndola, Kacper Szymański, Raquel O. Cristóvão, Adélio Mendes, Vítor J.P. Vilar, Sylwia Mozia〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, the efficiency of three different hybrid systems coupling ultrafiltration (UF) with (i) UVC/H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉, (ii) UVC/TiO〈sub〉2〈/sub〉, and (iii) UVC was evaluated for the treatment of a secondary effluent (SE) from a municipal wastewater treatment plant and a surface water (SW) from Miedwie Lake, both spiked with 5 mg L〈sup〉−1〈/sup〉 of oxytetracycline (OTC). A ceramic membrane made of TiO〈sub〉2〈/sub〉 was tested. The effect of H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 concentration (30 to 120 mg L〈sup〉-1〈/sup〉) on the UVC/H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉-UF system and of P25-TiO〈sub〉2〈/sub〉 loading (0.5 to 1.5 g L〈sup〉-1〈/sup〉) in suspension on the photocatalytic UVC/TiO〈sub〉2〈/sub〉-UF system were investigated. A photonic flux of 5.1 J s〈sup〉-1〈/sup〉 was provided in all systems. The maximum pure water flux (PWF) was 111 L m〈sup〉-2〈/sup〉 h〈sup〉-1〈/sup〉. Adsorption on the photocatalyst particles and/or on the membrane surface was found to be an important contribution for the removal of OTC and dissolved organic carbon (DOC). The UF membrane contributed significantly to photocatalyst and pollutants rejection in the photocatalytic membrane reactor (PMR) with the UVC/TiO〈sub〉2〈/sub〉 system; whereas when using the UVC/H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 process, with the highest H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 dose, the membrane effect was negligible. Using SE as reaction matrix in the UVC/TiO〈sub〉2〈/sub〉-UF system with 1.0 g L〈sup〉-1〈/sup〉 of TiO〈sub〉2〈/sub〉, the complete OTC removal was achieved in 5 h with a mineralization of 49%. For the same reaction period, a DOC removal of 52% was achieved with the UVC/H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉-UF system (120 mg H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 L〈sup〉-1〈/sup〉). A similar permeate flux decrease (〈em〉ca.〈/em〉 40%) was observed in both cases. Furthermore, the highest reduction of permeate flux (60%) was observed when using the UVC-UF system. Using SW as reaction matrix, higher OTC degradation rates and percentage of mineralization were reached for the same reaction period, when compared with SE, due to the lower COD and inorganic salts concentration present in the surface water.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118311210-ga1.jpg" width="285" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 19 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Jon A. Onrubia-Calvo, Beñat Pereda-Ayo, Unai De-La-Torre, Juan R. González-Velasco〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Here we report the effects of strontium doping of perovskites (La〈sub〉1-x〈/sub〉Sr〈sub〉x〈/sub〉CoO〈sub〉3〈/sub〉) on NO〈sub〉x〈/sub〉 storage and reduction (NSR) as well as the effects of supporting the perovskite onto an alumina support. The NSR capacity of La〈sub〉0.7〈/sub〉Sr〈sub〉0.3〈/sub〉CoO〈sub〉3〈/sub〉 improved with strontium doping: this material displayed a good balance between NO oxidation capacity and adsorption sites accessibility. Increased accessibility was mainly due to the strontium oxide segregates. In addition, different loadings of La〈sub〉0.7〈/sub〉Sr〈sub〉0.3〈/sub〉CoO〈sub〉3〈/sub〉 perovskite (10, 20, 30, 40 and 50%) were impregnated onto alumina in order to increase the exposed surface area of the perovskite. This had the effect of increasing the NSR capacity of the perovskite. The results of X-Ray diffraction, UV–vis–NIR spectroscopy, N〈sub〉2〈/sub〉 adsorption-desorption, electron microscopy, and temperature programmed techniques, demonstrated that the cobalt ions preferably formed cobalt aluminate (CoAl〈sub〉2〈/sub〉O〈sub〉4〈/sub〉) in the case of low perovskite loadings (〈20%). Meanwhile, a well-developed perovskite phase was observed with the higher loadings (〉30%). The specific NO oxidation rate per gram of perovskite increased dramatically with the incorporation onto an alumina support. 30% LSCO/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 sample had an oxidation rate of 138 μmol min〈sup〉-1〈/sup〉 (g LSCO)〈sup〉-1〈/sup〉 at 350 °C, more than double the rate of the bulk La〈sub〉0.7〈/sub〉Sr〈sub〉0.3〈/sub〉CoO〈sub〉3〈/sub〉 (49 μmol min〈sup〉−1〈/sup〉 (g LSCO)〈sup〉−1〈/sup〉). Likewise, the 30% LSCO/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 sample had a higher NO〈sub〉x〈/sub〉 storage capacity than its bulk counterpart at 400 °C: 306 vs. 115 μmol (g LSCO)〈sup〉−1〈/sup〉. The higher oxidation capacity of the alumina-supported samples also facilitated the diffusion of the intermediate compounds from oxidation to adsorption sites. Impregnating alumina with perovskite could be used to improve the efficiency of perovskite mediated NO〈sub〉x〈/sub〉 removal in automobile applications. Furthermore, adding palladium onto optimum alumina-supported perovskite sample, i.e. 1.5% Pd-30% LSCO/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, resulted in a clear improvement in NO〈sub〉x〈/sub〉 storage and reduction capacity. This last sample demonstrated a nitrogen yield as high as 65%, an improvement over the model Pt-based NSR catalyst.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118317346-ga1.jpg" width="343" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Amin Delparish, Sinan Koc, Burcu Selen Caglayan, Ahmet K. Avci〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Oxidative steam reforming (OSR) of glycerol to synthesis gas (syngas) was studied in a microchannel reactor that involved a thin layer of Rh/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 catalyst coated to the inner wall of a rectangular channel. The effects of reaction temperature (550–700 °C), molar inlet ratios of carbon-to-oxygen (C/O = 0.75, 1.125; C and O: moles of carbon and oxygen atoms at the inlet, respectively) and steam-to-carbon (S/C = 3-5) and microchannel reactor configuration on product distribution and syngas composition were investigated. In all experiments, complete, coke-free conversion of glycerol to gaseous carbon containing species was observed. The only exception was seen at 550 °C and C/O = 1.125 that led to 93% glycerol conversion and solid carbon deposition, the latter being verified by XPS and Raman spectroscopy analyses. Decrease in C/O from 1.125 to 0.75 promoted oxidation of H〈sub〉2〈/sub〉, CO, CH〈sub〉4〈/sub〉, C〈sub〉2〈/sub〉H〈sub〉4〈/sub〉, C〈sub〉2〈/sub〉H〈sub〉6〈/sub〉 and other carbon containing species on the catalyst surface, with the magnitude of promotion being increased notably with temperature. Despite O〈sub〉2〈/sub〉-enriched feeding, Rh remained at metallic state as revealed by XPS characterization of the spent samples. Lowering C/O also elevated yields of CO〈sub〉2〈/sub〉 and steam, the latter which drived water-gas shift (WGS), an important side reaction that affected product distribution on Rh/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 in favor of H〈sub〉2〈/sub〉. Yields of C〈sub〉1〈/sub〉-C〈sub〉2〈/sub〉 hydrocarbons decreased at higher temperatures and at lower C/O and S/C ratios due to their consumption via total oxidation and steam reforming routes, respectively. Microchannel reactor packed with particulate form of catalyst gave yields of CO〈sub〉2〈/sub〉 and H〈sub〉2〈/sub〉 lower and yields of CO and C〈sub〉1〈/sub〉-C〈sub〉2〈/sub〉 hydrocarbons higher than those obtained in the coated configuration under identical conditions. These findings seemed to correlate with the extents of oxidation reactions and WGS, which were believed to vary mainly with different heat transport characteristics of the reactor schemes. H〈sub〉2〈/sub〉/CO ratios close to the ideal value of 1 for Fischer-Tropsch synthesis were obtained at 700 °C, S/C = 3–4 and C/O = 1.125.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118303109-fx1.jpg" width="469" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Marcin Rybicki, Joachim Sauer〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The dependence of deprotonation energies of zeolitic Brønsted acid sites on the dielectric constants of these materials is investigated using quantum chemical calculations. The deprotonation energy decreases as the reciprocal value of average static dielectric constant of the zeolite framework increases with a correlation coefficient R〈sup〉2〈/sup〉 equal to 0.74 (252 data points for 19 zeolite frameworks). We decompose the deprotonation energy of these nanoporous materials into an 〈em〉intrinsic〈/em〉 deprotonation energy and a proton “solvation” energy within zeolites which is the origin of the observed 1/ε dependence. The 〈em〉intrinsic〈/em〉 deprotonation energy is shown to be a superior acidity descriptor. In agreement with experiments, it indicates that two-dimensional zeolites (nanosheets) are not more acidic than three-dimensional ones (bulk materials). We use our large data set to examine the dependence of the 〈em〉intrinsic〈/em〉 deprotonation energy on structure parameters (Al〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Si bond angle, O〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉H bond distance, confinement coefficient) and on the structure relaxation energy but for none of them a correlation has been found.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118304498-fx1.jpg" width="491" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Elisa Leyva, Edgar Moctezuma, Mariana López, Kim M. Baines, Brenda Zermeño〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The photocatalytic degradation of 〈em〉β〈/em〉-blockers in TiO〈sub〉2〈/sub〉 was investigated. Metoprolol (MET) was selected as a model compound since its structure is quite similar to several compounds utilized as〈em〉 β〈/em〉-blockers. MET degradation as a function of time was investigated by means of several analytical techniques. Analyzing the degradation mixtures by total organic carbon (TOC) analyzer and high-performance liquid chromatography (HPLC), it was evident that after one hour of irradiation, MET was transformed into other more recalcitrant intermediates. Latter intermediates were slowly degraded achieving 80% mineralization after four hours of irradiation. Gas chromatography – mass spectrometry (GC–MS) analysis of mixtures obtained upon irradiation at short reaction times (an hour or less) allowed the identification of several new intermediate organic compounds. Among those, several aromatic and low molecular weight amines. Polyhydroxylated compounds were also identified but only in trace amounts. Infrared (IR) and ultraviolet-visible (UV–vis) spectroscopy studies indicated that MET is first transformed into several hydroxylated aromatic compounds. Eventually, after several hours of irradiation, these compounds are transformed into low molecular weight unsaturated acids. HPLC analysis of reaction mixtures and coinjection of standard solutions allowed the detection of several intermediates, namely 1,4-hydroquinone, 4-(2-methoxyethyl)phenol, 2-(4-hydroxyphenyl)ethanol, 4-hydroxybenzandehyde, 1,2,4-benzenetriol, catechol and oxalic acid. Nuclear magnetic resonance (NMR) studies in deuterated solvents allowed the unequivocal detection of some of the aromatics in the reaction mixture. These NMR studies also demonstrated the transformation of aromatics into low molecular alkenes and acids. MET degradation routes and a detailed reaction mechanism is presented based on the intermediates identified. Fundamental aspects about MET degradation will be quite useful for future applications of photocatalysis in the degradation of other 〈em〉β〈/em〉-blockers, pharmaceuticals and organic compounds with structures similar to MET.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118314196-ga1.jpg" width="286" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Ali Mehdad, Rolf E. Jentoft, Friederike C. Jentoft〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A series of single-phase mixed metal carbides of molybdenum and tungsten (Mo〈sub〉2-x〈/sub〉W〈sub〉x〈/sub〉C, 0 〈 x 〈 2) was synthesized. Precursors with intimately mixed metals were prepared by flash-freezing aqueous solutions of molybdenum and tungsten salts in liquid nitrogen and subsequent freeze-drying. The powders of freeze-dried samples had small particles that facilitated reduction and carburization. Direct carburization of freeze-dried precursors at a final temperature of 650 °C resulted in formation of single-phase metal carbides with hexagonal structures and CO adsorption capacities of 15–27 μmol/g. All carbides were catalytically active for conversion of toluene at a total pressure of 21 bar, and a H〈sub〉2〈/sub〉:toluene molar ratio of 33. At a reaction temperature of 250 °C, only methylcyclohexane formed at TOFs of 0.13 (Mo〈sub〉0.5〈/sub〉W〈sub〉1.5〈/sub〉C) ― 2.1 s〈sup〉−1〈/sup〉 (Mo〈sub〉2〈/sub〉C). Activation energies for ring hydrogenation were in the range of 40–60 kJ/mol. At 400 °C, catalysts deactivated for 24 h before stabilizing. At steady state, methylcyclohexane and small alkanes formed via ring hydrogenation and hydrogenolysis, indicating the presence of sites with metallic character. Disproportionation of toluene to benzene and xylenes indicated the presence of weakly acidic sites. An excess of benzene was attributed to the presence of carbon vacancies on the surface, which formed more readily in the tungsten-containing carbides.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118307752-ga1.jpg" width="499" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Sungyup Jung, Alexandros N. Karaiskakis, Elizabeth J. Biddinger〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Furfural (FF) is a biomass-derived oxygenate and a platform chemical that can produce a biofuel candidate, 2-methyl furan (MF), and valuable chemicals by hydrogenation and hydrogenolysis. Electrochemical hydrogenation and hydrogenolysis (ECH) is a promising method for upgrading of FF to produce MF and valuable chemicals such as furfuryl alcohol (FA). The production rate, selectivity and faradaic efficiency (FE) of products on microcrystalline and nanocrystalline Cu electrodes were compared with a bare Cu electrode at different potentials. At near onset potentials of ECH of FF, the production rate of FA + MF on nanocrystalline Cu was 2.4 times that of bare Cu, with a negligible amount of side product, hydrogen gas. As the magnitude of applied potential increased to much beyond the onset potential, the production rate for FA + MF more than doubled on the nanocrystalline Cu catalyst compared to bare Cu, when a significant quantity of FF was present. The nanocrystalline Cu catalyst also maintained stable and repeatable FE and production rate for desired products during repeated cycles of ECH of FF.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118315554-ga1.jpg" width="435" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Gurkan Karakas, Alper Sevinc〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The high temperature catalytic oxidation (HTCO) performance of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 supported Pt, Cu, Cu-Ce and Fe catalysts were systematically studied with a perspective of selective oxidation of nitrogenous compounds to nitric oxide for quantitative determination of bound nitrogen. The catalyst samples were prepared via impregnation and characterized by XRD and BET. In addition, temperature programmed reaction experiments with acetonitrile and oxygen were conducted to evaluate the catalytic activity and selectivity toward N〈sub〉2〈/sub〉, N〈sub〉2〈/sub〉O and NO. The catalyst samples were also tested for model components; urea, EDTA, pyridine, glutamic acid and ammonium sulfate representing different functional groups.〈/p〉 〈p〉The conversion of acetonitrile was tended to increase in the order of Cu-Ce/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉〉Cu/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉〉Pt/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉〉Fe/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 at around 500 °C and almost complete conversion of acetonitrile was achieved at 700 °C over the all catalyst samples studied. Temperature programmed reaction experiments indicated that two reaction routes, direct oxidation of cyanide species and oxidation of ammonia formed by hydrolysis of cyanide species determine NO selectivity. Direct oxidation of cyanide species is favored over Pt/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 catalyst which exhibit highest NO yield (93%) at 700 °C. The second route, hydrolysis of cyanide species to ammonia which is further oxidized to N〈sub〉2〈/sub〉, NO and NO〈sub〉2〈/sub〉 was evidenced by TPR-FTIR analyses over Fe/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, Cu/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and Cu-Ce/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 catalysts. Among these catalysts, highest NO yield (90%) was observed over Fe/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 at 700 °C which is comparable to Pt/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 catalyst. For Cu and Cu-Ce/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 catalyst, lower yields were obtained due to higher N〈sub〉2〈/sub〉 selectivity. Similar results were obtained from benchmark tests performed by model nitrogen components representing different functional groups. Pt/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and Fe/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 catalysts possessed higher oxidation activities and nitrogen recoveries than Cu and Cu-Ce catalysts. As a result, Fe/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 catalyst is highly effective, lower cost alternative to existing Pt based catalysts which are used for bound nitrogen determination.〈/p〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118305297-fx1.jpg" width="259" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): N. Catherin, E. Blanco, L. Piccolo, D. Laurenti, F. Simonet, C. Lorentz, E. Leclerc, V. Calemma, C. Geantet〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The discovery of sulfur-resistant catalysts for selective ring opening (SRO) is an important challenge for refiners, considering the future legislation on cetane index of diesel fuels. In the present work, we studied the properties of RuS〈sub〉2〈/sub〉 supported on several zeolites in gas-phase decalin hydroconversion at high hydrogen pressure (5 MPa) in the presence of 0.8% H〈sub〉2〈/sub〉S concentration. Catalytic bifunctionality was investigated by changing the Ru loading or support acidity. The addition of RuS〈sub〉2〈/sub〉 strongly improved catalytic activity of an HY zeolite, decreased coke deposition and dehydrogenation and increased selectivity towards RO products. The mechanism mainly proceeds from skeletal isomerization induced by the acidity of the zeolite but the hydrogen activation properties of RuS〈sub〉2〈/sub〉 are beneficial to the activity and stability of the catalyst.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118313105-ga1.jpg" width="342" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 19 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Aleksey A. Pimerzin, Andrey A. Roganov, Sergey P. Verevkin, Maria E. Konnova, Vladimir A. Pilshchikov, Andrey A. Pimerzin〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The composite material on the base of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and SAPO-11 was prepared with a various concentration on SAPO-11 and investigated as a carrier of bifunctional Pt-based catalyst for 〈em〉n〈/em〉-alkanes hydroisomerization. The Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-SAPO-11 composite material with an optimal composition and acidic properties was used to prepare bifunctional catalysts with different hydrogenation/dehydrogenation sites. The effectiveness of the Pt, Pd, Ni and CoMoS active sites of bifunctional catalysts supported on the composite Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-SAPO-11 carrier were investigated and compared in 〈em〉n〈/em〉-hexadecane hydroisomerization. Synthesized materials were investigated using X-ray powder diffraction, scanning electronic and high-resolution transition electronic microscopies, N〈sub〉2〈/sub〉 physisorption, NH〈sub〉3〈/sub〉-TPD and pyridine-FTIR spectroscopy. A CoMoS active phase was studied as hydrogenation/dehydrogenation hydrogenated-dehydrogenated active sites of bifunctional hydroisomerization catalysts.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092058611831229X-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 323〈/p〉 〈p〉Author(s): Z.R. Ismagilov, E.V. Matus, I.Z. Ismagilov, O.B. Sukhova, S.A. Yashnik, V.A. Ushakov, M.A. Kerzhentsev〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hydrogen production through autothermal reforming (ATR) of hydrocarbon fuels (ethanol, methane) over Ni-based catalysts was studied with a special focus on the role of metal-support interaction. The strength of Ni-support interaction was regulated by means of tailored modification of cerium oxide and aluminum oxide supports. The electronic, redox and structural properties of pre- and post-reaction Ni/Ce〈sub〉1-x〈/sub〉M〈sub〉x〈/sub〉O〈sub〉y〈/sub〉 and Ni/Ce〈sub〉1-x〈/sub〉M〈sub〉x〈/sub〉O〈sub〉y〈/sub〉/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 (M = Zr, Gd, La, Mg) catalysts were studied in detail by TG-DTA, BET, XRD, HRTEM-EDX, HAADF-STEM, TPR, XPS and UV–vis DRS methods. It was found that the mode of Ni-support interaction controls the state, dispersion, and reducibility of Ni active component, and consequently, catalyst performance in ATR of hydrocarbon fuels. Among the tested modifiers (M = Zr, Gd, La, Mg), La has a more pronounced positive effect on the state and functionality of Ni/Ce〈sub〉1-x〈/sub〉M〈sub〉x〈/sub〉O〈sub〉y〈/sub〉 and Ni/Ce〈sub〉1-x〈/sub〉M〈sub〉x〈/sub〉O〈sub〉y〈/sub〉/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 catalysts. The introduction of La as a modifier in the support composition enhances the metal-support interaction, which leads to a diminution of Ni〈sup〉n+〈/sup〉 reducibility. On the other hand, the improvement of the Ni dispersion and catalyst stability under the ATR reactions is achieved. The addition of a Pd-promoter makes it possible to optimize the reducibility of Ni〈sup〉n+〈/sup〉 strongly interacting with the support and provides the ability of Ni catalysts to the self-activation. The optimal support composition for Ni nanoparticles was designed that provides hydrogen yields which are close to the thermodynamic equilibrium values: ∼55% (Ce〈sub〉0.8〈/sub〉La〈sub〉0.2〈/sub〉O〈sub〉1.9〈/sub〉, АTP C〈sub〉2〈/sub〉H〈sub〉5〈/sub〉OH at 600〈sup〉о〈/sup〉C) and ∼65% (30Ce〈sub〉0.2〈/sub〉Zr〈sub〉0.2〈/sub〉La〈sub〉0.6〈/sub〉O〈sub〉1.7〈/sub〉/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, АTP CH〈sub〉4〈/sub〉 at 850〈sup〉о〈/sup〉C).〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118307739-ga1.jpg" width="219" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 17 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Jordi Ampurdanés, Muralidhar Chourashiya, Atsushi Urakawa〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The polymer electrolyte membrane (PEM)-based electrolysis technology is a promising mean to split water and store renewable energy in the form of clean fuel, hydrogen. However, its high price due to the use of platinum group metals (PGMs) as catalyst materials generally makes the technology cost-restrictive. Herein we present the performance evaluation of cobalt oxide in PEM electrolysis as cathode catalyst where hydrogen evolution reaction (HER) takes place. Performance comparison of non-PGM catalysts (CoO, Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 and MoS〈sub〉2〈/sub〉) revealed that better performance was attained with Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 and it was further improved by mixing with an electrically conducting carbon material (Vulcan). An optimum amount of the carbon additive was found, and the best performance was recorded at 47 wt% Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 over the total amount. At 2.05 V, 47 wt% Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉-based catalyst (0.55 A/cm〈sup〉2〈/sup〉) outperformed 47 wt% MoS〈sub〉2〈/sub〉-based one (0.51 A/cm〈sup〉2〈/sup〉). More importantly, the performance of the former at 2.3 V (1.12 A/cm〈sup〉2〈/sup〉) surpassed even that of Pt-black (1.11 A/cm〈sup〉2〈/sup〉). 〈em〉In situ〈/em〉 XAS study of the Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉-based material under PEM electrolysis conditions revealed dynamic interchange of Co〈sup〉3+〈/sup〉 and Co〈sup〉2+〈/sup〉 fractions, which was attributed to ultimately boost the HER performance.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118307405-ga1.jpg" width="277" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 11 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Konstantinos A. Goulas, Shahar Dery, Paul Dietrich, Gregory R. Johnson, Adam Grippo, Young Chung Wang, Elad Gross〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The impact of tandem dehydrogenation-aldol condensation reactions on the structure of oxide-supported PdCu catalysts was studied by a combination of X-ray tomography measurements, ensemble-averaging spectroscopy techniques and reactivity measurements. X-ray tomography measurements generated 3D images at submicron resolution of the packed catalyst in the flow reactor following its exposure to various reaction conditions. Quantitative analysis of the tomography data revealed that exposure of the catalyst to reaction conditions induced structural deformation of the mixed Mg-Al oxide supports, accompanied by sintering of the PdCu nanoparticles into micron-sized aggregates. Improved stability was achieved once the PdCu particles were supported on an oxide, such as anatase TiO〈sub〉2〈/sub〉, which does not undergo restructuring or phase transition under reaction conditions. This study demonstrates that structural information extracted by X-ray tomography measurements may uncover important structure-reactivity correlations and identify the reasons for catalysts deactivation.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118315037-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 12 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Rebecca McVicker, Nishtha Agarwal, Simon J. Freakley, Qian He, Sultan Althahban, Stuart H. Taylor, Christopher. J. Kiely, Graham J. Hutchings〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Methane upgrading into energy-dense liquid derivatives (such as methanol or mid-range hydrocarbons) is a highly desirable process to increase its utilisation. The selective oxidation of methane using hydrogen peroxide has been investigated using unsupported gold-palladium nanoparticles prepared using colloidal methods. The effect of the reaction conditions and the catalyst parameters have been systematically investigated. Poly(vinyl)pyrrolidone (PVP) stabilised Au-Pd colloids produce methyl hydroperoxide as the primary reaction product, which is subsequently converted to methanol with high oxygenate selectivity. The stability and re-use characteristics of the colloidal catalyst have also been assessed for methane oxidation with hydrogen peroxide.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118314433-ga1.jpg" width="247" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 12 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Yang Wang, Wen-Cui Li, Yu-Xi Zhou, Rao Lu, An-Hui Lu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hexagonal boron nitride (〈em〉h〈/em〉-BN) is a burgeoning catalyst for oxidative dehydrogenation of propane (ODHP) with impressive light olefins selectivity, which deserves further study to optimize the heat and mass transfer process with the aim of promoting the potential industrial application since ODHP is a highly exothermic process. Herein, 〈em〉h〈/em〉-BN wash-coated cordierite monolithic catalyst was designed through a chemical vapor deposition method using boron acid and urea as precursors, which was used for ODHP reaction and exhibited a ∼16.8% conversion of propane and 82.1% selectivity towards propylene, with only 3.7% selectivity of CO and no detected CO〈sub〉2〈/sub〉, at temperature of 535 ℃ and a high gas hourly space velocity (GHSV) of 576,000 mL/g〈sub〉BN〈/sub〉h. The typical structure of 〈em〉h〈/em〉-BN/Cordierite with well-developed straight-channel and short diffusive pathway of the thin wash-coated 〈em〉h〈/em〉-BN layer guarantee the mass transfer process at high GHSV, achieving a high propylene space time yield of 18.6 g〈sub〉C3H6〈/sub〉 g〈sub〉BN〈/sub〉〈sup〉−1〈/sup〉 h〈sup〉−1〈/sup〉 and improving the selectivity towards propylene and ethylene by suppressing secondary reactions of deep oxidation. Meanwhile, the high GHSV and excellent thermal conductivity of 〈em〉h〈/em〉-BN contribute to the heat transfer during reactions.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118309660-ga1.jpg" width="228" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 12 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Hye Won Jeong, Kyu Jun Park, Yiseul Park, Dong Suk Han, Hyunwoong Park〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Although one-dimensional TiO〈sub〉2〈/sub〉 nanotube arrays (TNA) grown on Ti substrates via electrochemical anodization are extensively studied in photoelectrochemistry, the photo(electro)catalytic activity of TNA detached from the Ti substrates remains unexplored. Herein, we synthesize TNA samples with various pore sizes (40–100 nm) and tube lengths (4–15 μm) via two-step electrochemical anodization, and transfer them to transparent conducting oxide (i.e. fluorine-doped tin oxide; FTO) substrates in normal (〈em〉n〈/em〉) alignment (front plane outward) and reverse (〈em〉r〈/em〉) alignment (backplane outward). The front and back planes of the as-fabricated TNA film are the same based on X-ray diffraction (anatase structure), X-ray photoelectron spectroscopy (Ti and O), and UV–vis transmittance data, though the tubes are open in the front and closed in the back. Regardless of the direction of irradiation (〈em〉SE〈/em〉: FTO → TNA vs. 〈em〉EE〈/em〉: TNA → FTO), longer tubes generate a higher photocurrent (〈em〉I〈/em〉〈sub〉ph〈/sub〉) due to the large light absorption. However, for the same alignment of TNA (either 〈em〉n-〈/em〉 or 〈em〉r〈/em〉-TNA), 〈em〉SE〈/em〉 irradiation leads to a very large 〈em〉I〈/em〉〈sub〉ph〈/sub〉 (e.g., 〈em〉nSE〈/em〉 〉 〈em〉nEE〈/em〉), whereas 〈em〉n〈/em〉-TNA consistently generates a larger 〈em〉I〈/em〉〈sub〉ph〈/sub〉 than 〈em〉r〈/em〉-TNA for a given irradiation direction (i.e., 〈em〉n〈/em〉 〉 〈em〉r〈/em〉). The photocatalytic decomposition of phenol follows the same tendency (〈em〉n〈/em〉 〉 〈em〉r〈/em〉); however, the Faraday efficiency (based on the photocharge) is higher with 〈em〉EE〈/em〉 (〈em〉nEE〈/em〉 28%, 〈em〉rEE〈/em〉 20%) than 〈em〉SE〈/em〉 (〈em〉rSE〈/em〉 11%, 〈em〉nSE〈/em〉 7%) irradiation. These photoelectrochemical and photocatalytic behaviors are explained in terms of charge carrier generation (FTO/TNA vs. TNA/solution), dissimilar charge carrier transfer pathways (〈em〉e〈/em〉〈sup〉−〈/sup〉 transfer through tube framework vs. 〈em〉h〈/em〉〈sup〉+〈/sup〉 transfer via radial direction), and charge injection at the tube (open vs. clogged tube mouth)/solution interface. The time-resolved photoluminescence (TRPL) emission and incident photon-to-current efficiency (IPCE) are also studied to gain insight into the charge transfer kinetics.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118309180-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 6 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Lingli Xing, Yuexi Yang, Wei Ren, Dongyue Zhao, Ye Tian, Tong Ding, Jing Zhang, Lirong Zheng, Xingang Li〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Herein, we facilely synthesized the Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/CeO〈sub〉2〈/sub〉 nanosheets on monolithic Ni foam (Co/Ce-NS) 〈em〉via〈/em〉 the tandem hydrothermal and impregnation methods. The constructed hierarchically meso-macroporous nano-structures increase the soot-catalysts contact chances, and promote mass transfer of gaseous reactants and products in catalytic soot combustion. The deposition of Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanoparticles onto CeO〈sub〉2〈/sub〉 nanosheets enhances the redox properties of the catalysts, because the Co-Ce interaction generates active surface adsorbed oxygen species for soot combustion. Our results reveal that the adsorbed oxygen species on the Co-Ce interfaces are more active than these on surface CeO〈sub〉2〈/sub〉 or Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉. The 0.6Co/Ce-NS catalyst with the optimal cobalt loading has more superficial Co〈sup〉2+〈/sup〉-□-Ce〈sup〉3+〈/sup〉 couples than other catalysts, consequently generating more active surface adsorbed oxygen species for catalytic soot oxidation. The 0.6Co/Ce-NS catalyst exhibits comparable catalytic activity with the 1%Pt/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 catalyst under the loose contact condition. Moreover, the 0.6Co/Ce-NS catalyst has the excellent thermal stability and water resistance. Therefore, the hierarchically meso-macroporous Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/CeO〈sub〉2〈/sub〉 nanosheet monolithic catalysts have potential industrial application in catalytic soot elimination and other related heterogeneous catalytic systems.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118315086-ga1.jpg" width="455" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 6 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Shahzad Ali, Abdul Razzaq, Su-Il In〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Transformation of CO〈sub〉2〈/sub〉, a notorious greenhouse gas, to solar fuels is a promising strategy to alleviate the interlinked issues of global warming, environmental pollution, and climatic changes. Additionally, CO〈sub〉2〈/sub〉 conversion to useful chemicals/fuels also possess a great potential to well match the energy demand in a sustainable manner. Hence, such exceptional benefits of harnessing CO〈sub〉2〈/sub〉, by capitalizing sunlight, to valuable chemicals/fuels through photocatalysis, as one of the effective approach in the respective domain, have triggered great interest among researchers and scientific community. In this regard, utilization of customary and standard photocatalytic materials, specifically metal oxides like TiO〈sub〉2〈/sub〉, are modified to provide enhanced performance, which is usually restricted due to limited intrinsic optical and physicochemical properties. To overcome such a critical issue of limited performance, several strategies like metals and non-metals doping, hetero-junctions, composites and nanostructures formation of photocatalytic materials have been investigated. Recently, with the invention of graphene and its derivatives, graphene based photocatalytic materials have been a topic of great interest, specifically for photocatalysts development and photocatalysis application. Graphene and its derivatives, due to their extraordinary physiochemical and electrical properties like high surface area, stability, anticorrosion capacity, photosensitivity, and excellent conductivity, can overcome constraints faced by traditional photocatalysts. Thus, Graphene based photocatalysts can be a feasible strategy to break new grounds in the field of photocatalytic CO〈sub〉2〈/sub〉 reduction (PCCR) to useful chemicals/ fuels, i.e. conversion of sunlight to fuels. Herein, a summarized overview is presented for the latest development in graphene-based photocatalysts, focusing various strategies and researches being investigated in relation to the, utility of graphene and its derivatives for solar fuels generation, particularly C〈sub〉1〈/sub〉 chemicals like CO, CH〈sub〉4〈/sub〉, CH〈sub〉3〈/sub〉OH, and insights to their role in improving efficacy of photocatalysts.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118313051-ga1.jpg" width="200" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 5 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): O.B. Belskaya, L.N. Stepanova, A.I. Nizovskii, A.V. Kalinkin, S.B. Erenburg, S.V. Trubina, K.O. Kvashnina, N.N. Leont’eva, T.I. Gulyaeva, M.V. Trenikhin, V.I. Bukhtiyarov, V.A. Likholobov〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The MgAl(Sn) layered double hydroxides (LDH) with the atomic ratios Mg/(Al + Sn) = 3 and Sn/(Sn + Al) = 0, 0.002, 0.005, 0.01, 0.05, 0.1, 0.3, 0.5, 0.7, 1.0 were synthesized and the ratio Sn/(Sn + Al) ≤ 0.1 was shown to provide the formation of systems with uniform phase composition. Mixed oxides derived from LDH retain the high specific surface area of 150-200 m〈sup〉2〈/sup〉/g and the basic properties when some aluminium atoms are replaced with tin. It was found that the Sn-containing mixed oxides are able to restore the layered structure during rehydration and intercalate the anion precursors of platinum into the interlayer space of the formed LDH. The emerging platinum sites initiate the reduction of tin at temperatures below 723 K. TEM, EXAFS and XPS studies demonstrated that tin introduction in the support increases the dispersion of supported platinum. An extreme dependence of the activity of Pt/MgAl(Sn)O〈sub〉x〈/sub〉 catalysts in propane and n-decane dehydrogenation on the tin content in the support was revealed. The active catalysts are characterized by the phase and elemental uniformity of the support, highly disperse state of Pt(0), and the absence of a noticeable amount of reduced tin and bimetallic particles.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118313506-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 4 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Pan Li, Shuang Zhu, Haifeng Hu, Lingju Guo, Tao He〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Photocatalytic conversion of CO〈sub〉2〈/sub〉 into hydrocarbons by utilization of the solar energy is considered a promising approach to mitigate energy crisis and the environmental issues. Since the defects in a catalyst play an important role in CO〈sub〉2〈/sub〉 reduction, herein, the porous ZnO nanoplates with vacancy defects are synthesized by annealing ZnS(en)〈sub〉0.5〈/sub〉 precursor in air at different temperature. The defect amount in ZnO changes with the annealing temperature, resulting in different photocatalytic activity for CO〈sub〉2〈/sub〉 reduction. The related mechanism has been studied both experimentally and theoretically. Raman spectra and chemical composition of the obtained catalysts are used to determine the defects. Transient techniques are used to investigate the separation of photogenerated charge carriers. CO〈sub〉2〈/sub〉 adsorption capacity for different catalysts is also measured. First-principles calculation is used to study the adsorption and activation of CO〈sub〉2〈/sub〉 on the ZnO surface. We envision that this work may afford an efficient approach to develop the semiconductor photocatalysts with superior activity via defects engineering.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Vacancy defects in the porous ZnO nanoplates facilitate separation of charge carriers, and are in favor of adsorption and activation of CO〈sub〉2〈/sub〉, resulting in greatly enhanced photocatalytic activity.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118309386-ga1.jpg" width="287" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: Available online 26 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Masakuni Ozawa, Masaki Misaki, Masaki Iwakawa, Masatomo Hattori, Katsutoshi Kobayashi, Kimitaka Higuchi, Sigeo Arai〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Core-shell type CeO〈sub〉2〈/sub〉/ZrO〈sub〉2〈/sub〉 (csCZ) support was investigated as a novel item for reducing platinum content in three way catalysts (TWC). A composite csCZ support was characterized by X-ray diffraction, scanning transmission electron microscopy and energy dispersive spectroscopy. The analysis revealed that the dispersed phase of CeO〈sub〉2〈/sub〉 appeared to form a relatively thin layer and aggregates on the surface of ZrO〈sub〉2〈/sub〉. Pt-concentrated areas and agglomerate were stabilized on the areas that were Ce-rich on ZrO〈sub〉2〈/sub〉 core particle. The H〈sub〉2〈/sub〉-TPR profile of Pt/csCZ with Pt content of 0.1 and 0.01 wt.% showed single peak in each reaction temperature, demonstrating extremely active than those of Pt/CeO〈sub〉2〈/sub〉-NPs, when the same low content Pt loading samples were compared. 0.1 wt.% Pt/csCZ showed better activity than that of 0.1 wt.% Pt/CeO〈sub〉2〈/sub〉, and TWC activities of low content Pt catalyst are enhanced by designed nanostructured core-shell type CeO〈sub〉2〈/sub〉/ZrO〈sub〉2〈/sub〉 support. The agglomeration of Pt will be inhibited due to the separated morphological feature of CeO〈sub〉2〈/sub〉 NPs on ZrO〈sub〉2〈/sub〉, which bring an important effect of csCZ support on Pt reduction.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Can “Core-shell type CeO〈sub〉2〈/sub〉-ZrO〈sub〉2〈/sub〉 “reduce Pt content in exhaust catalyst?〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118314494-ga1.jpg" width="314" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: Available online 13 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Tayyebeh Soltani, Ahmad Tayyebi, Byeong-Kyu Lee〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The fabrication of p–n junctions with built-in electric field effect between n-type BiVO〈sub〉4〈/sub〉 (BVO) and p- type BiFeO〈sub〉3〈/sub〉 (BFO) can be efficient strategy to separate photogenerated carriers and enhances photocurrent density and photostability in BVO. We developed a facile ultrasonic/hydrothermal route to successfully synthesize BFO/BVO p–n junction that greatly improved the performance of n-type BVO and p-type BFO for photocatalytic degradation of tetracycline (TC) and photoelectrochemical (PEC) water splitting. The photodegradation of TC by BVO and BFO was highly dependent on solution pH, but that by BFO/BVO was not. The BFO/BFO p–n junction nanostructures improved the photocatalytic degradation of TC from 31% and 22% with BFO to 84% and 95% with BFO/BVO p–n junction at pH 6.7 and 9.5, respectively, and also from 37% with BVO to 84% with BFO/BVO p–n junction at pH = 2.5. The BFO/BVO nanostructures showed good photocurrent density of 0.36 mA cm 〈sup〉−2〈/sup〉 under UV–vis light and 0.23 mA cm〈sup〉-2〈/sup〉 under visible light at 1.0 V vs. Ag/AgCl, which are 3.0- and 3.28-fold greater than those of BVO. The structures also showed great stability (more than 88% of the initial photocurrent density) over 1 h, whereas BVO had poor stability (63%). The difference between photocurrent densities from front- and back-side illumination in the BFO/BVO p–n junction was substantially reduced to 0.04 mA cm〈sup〉-2〈/sup〉 as compared to 0.11 mA cm〈sup〉-2〈/sup〉 in BVO due to the formation of a p–n heterojunction between p-type BFO and n-type BVO. The stable BFO/BVO p–n junction also showed the highest charge carrier density as compared to BVO.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118303274-ga1.jpg" width="318" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 12 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Yuanyuan Ma, Qiaofeng Han, Te-Wei Chiu, Xin Wang, Junwu Zhu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Exploring a simple method to prepare efficient photocatalyst is very important technology for practical application. Herein, α-Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, β-Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and C/Bi/α-Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 were easily obtained by calcining bismuth citrate under different conditions. Especially, C/Bi/α-Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 obtained at 450 °C in nitrogen atmosphere exhibited superior photocatalytic activity for methyl orange (MO) and malachite green (MG) degradation under visible light irradiation, higher than β-Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and α-Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 calcined in air at 350 °C and above 450 °C, respectively. The presence of non-burned carbon in N〈sub〉2〈/sub〉 atmosphere benefits to complete transformation of β-Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 into α-Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 at a annealing temperature low to 300 °C, as well as partial reduction of Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 into Bi nanoparticles. More importantly, the remaining carbon and metal Bi could enhance visible light absorption of α-Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, generate hot charge carriers and boost electron migration efficiency, which thus dramatically improve photocatalytic activity of α-Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉. Furthermore, these bismuth oxides exhibit exceptionally strong adsorption ability for cationic dyes like MG and methyl violet (MV) with help of trace amount of ethylene diamine tetraacetic acid disodium salt (EDTA-2Na) and the maximum adsorption capacity for MG on α-Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 reached 312 mg/g. The as-prepared C/Bi/α-Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 also possesses good stability and recyclibility in photocatalysis and adsorption.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118313877-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈p〉C/Bi/α-Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 was obtained by calcining bismuth citrate in N〈sub〉2〈/sub〉, which exhibited superior visible light photocatalytic activity and adsorption ability with help of trace amount of EDTA-2Na.〈/p〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 316〈/p〉 〈p〉Author(s): Xiao Dong, Peng Zheng, Ai-Guo Zheng, Hui-Feng Li, Guo-Fu Xia, Ming-Feng Li, Ren-Yang Zheng, Bo-Qing Xu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Pt-Co/SiO〈sub〉2〈/sub〉 and Pt-Ir-Co/SiO〈sub〉2〈/sub〉 catalysts were prepared via galvanic replacement (GR) and employed for the hydrogenolytic ring-opening of methylcyclopentane (MCP). Selective deposition of the noble metals at the less expensive Co nanoparticle (NP) surface by GR greatly enhanced the utilization efficiency of the more active Pt or Pt and Ir atoms for the selective catalysis to the ring-opening reaction of MCP, as justified by comparison with catalysts from conventional impregnation preparation. The chemistry of GR was quantitatively studied by comprehension of the composition changes both in the preparation solution and in the solid samples. The structural features of GR catalysts were characterized as highly dispersed Pt or Pt and Ir clusters selectively deposited on Co NP surface. Compared to their counterparts from impregnation preparation, the GR catalysts showed much higher mass-specific activity normalized by overall noble metal loading (MSA〈sub〉NM〈/sub〉), due to the significantly enhanced utilization efficiency of Pt or Pt and Ir. In addition, the trimetallic Pt-Ir-Co/SiO〈sub〉2〈/sub〉 catalyst showed a distinctly higher MSA〈sub〉NM〈/sub〉 than the bimetallic Pt-Co/SiO〈sub〉2〈/sub〉 and Ir-Co/SiO〈sub〉2〈/sub〉 ones. This observation features a synergy between the highly dispersed Pt and Ir clusters in the catalysis, besides the enhanced noble metal utilization efficiency. Our catalytic data seem to suggest that a dicarbene mechanism was prevailing over the GR catalysts for the ring-opening reaction of MCP.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118303328-fx1.jpg" width="291" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 319〈/p〉 〈p〉Author(s): Zhao Yan, Shuzhuang Liu, Yuanyuan Zhang, Ting Wang, Shizhong Luo, Wei Chu, Fangli Jing〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The NiZrAl mixed metal oxides catalysts with varied Zr/Al ratio were derived from the layered double hydroxides (LDH) through the thermal decomposition. The different techniques such as TG, XRD, N〈sub〉2〈/sub〉 adsorption/desorption, XPS, TPR, H〈sub〉2〈/sub〉 chemisorption, SEM and TEM 〈em〉etc.〈/em〉 were applied to study the thermal decomposition behaviors of the corresponding LDH, crystalline phases changes before and after reaction, the porous structure, chemical state of surface element, reducibility, properties of active phase metallic Ni and the morphology. The results showed that the LDH structure could be kept during the experimental range from 0.1 to 1.0, although high Zr/Al ratio made the structure feature weaken. The porous structure of the calcined catalysts exhibited an significant change when Zr/Al ratio reached 0.5. Both Ni dispersion and surface increased linearly with the increased Zr/Al, however, more amount of surface Ni was reduced and less amount of coke was formed over the sample NiZr〈sub〉0.5〈/sub〉Al. It consequently gave the best conversion to gaseous products and the highest selectivity of hydrogen by promoting the water gas shift reaction and suppressing the CO methanation reaction.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118303249-fx1.jpg" width="235" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 316〈/p〉 〈p〉Author(s): Ke Zhang, Sergio Fernandez, Jeremy T. O’Brien, Tatiana Pilyugina, Sarah Kobaslija, Michele L. Ostraat〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper reports a straightforward approach to synthesizing hierarchical beta zeolites by exposing microporous zeolites to hydrothermal conditions amenable for beta crystallization, which simultaneously creates hierarchical pore structure while maintaining crystallinity and framework integrity without the use of organic structure-directing agents, pore-directing agents, or mesoporous templates. The obtained hierarchical beta zeolites possess enlarged mesopores and exhibit improved catalytic performance for the conversion of bulky molecules in the liquid-phase conversion of benzyl alcohol with mesitylene. A sequential hierarchical structure formation and recrystallization mechanism is proposed to elucidate the creation of mesopores in beta zeolites with excellent preservation of acidity and microporosity.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092058611730812X-fx1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 13 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Wenwen Zhang, Yuxiang Zhu, Haimei Xu, Marianne Gaborieau, Jun Huang, Yijiao Jiang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The influence of calcination temperature on ZrO〈sub〉2〈/sub〉 and its catalytic activity in glucose conversion was studied in this research. It shows that different structure of ZrO〈sub〉2〈/sub〉 can be obtained by tuning calcination temperature, which results in the various surface catalytic properties. Quantitative evaluation of acidity by NH〈sub〉3〈/sub〉-TPD and solid-state NMR spectroscopy shows that ZrO〈sub〉2〈/sub〉 calcined at 300 °C, which is in amorphous state and has a higher BET surface area, possesses more Brønsted and Lewis acid sites than ZrO〈sub〉2〈/sub〉 samples calcined at other temperatures. Amorphous ZrO〈sub〉2〈/sub〉 shows a better catalytic performance in glucose conversion, nearly 100% glucose conversion with an HMF selectivity of about 40%. Increasing calcination temperature leads to a result of sintering, crystallizing, and pore collapsing of ZrO〈sub〉2〈/sub〉. There is a distinct decrease in Brønsted acid sites, along with a decrease of the total number of acid sites in ZrO〈sub〉2〈/sub〉 as calcination temperature increases. At the same time, a new type of Lewis acid appears at a downfield shift, resulting in different reaction rates.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118313208-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 319〈/p〉 〈p〉Author(s): N.D. Charisiou, K.N. Papageridis, G. Siakavelas, V. Sebastian, S.J. Hinder, M.A. Baker, K. Polychronopoulou, M.A. Goula〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The glycerol steam reforming (GSR) reaction for H〈sub〉2〈/sub〉 production was studied comparing the performance of Ni supported on ZrO〈sub〉2〈/sub〉 and SiO〈sub〉2〈/sub〉-ZrO〈sub〉2〈/sub〉 catalysts. The surface and bulk properties were determined by ICP, BET, XRD, TPD, TPR, TPO, XPS, SEM and STEM-HAADF. It was suggested that the addition of SiO〈sub〉2〈/sub〉 stabilizes the ZrO〈sub〉2〈/sub〉 monoclinic structure, restricts the sintering of nickel particles and strengthens the interaction between Ni〈sup〉2+〈/sup〉 species and support. It also removes the weak acidic sites and increases the amount of the strong acidic sites, whereas it decreases the amount of the basic sites. Furthermore, it influences the gaseous products’ distribution by increasing H〈sub〉2〈/sub〉 yield and not favouring the transformation of CO〈sub〉2〈/sub〉 in CO. Thus, a high H〈sub〉2〈/sub〉/CO ratio can be achieved accompanying by negligible value for CO/CO〈sub〉2〈/sub〉. From the liquid products quantitative analysis, it was suggested that acetone and acetaldehyde were the main products for the Ni/Zr catalyst, for 750 °C, whereas for the Ni/SiZr catalyst allyl alcohol was the only liquid product for the same temperature. It was also concluded that the Ni/SiZr sample seems to be more resistant to deactivation however, for both catalysts a substantial amount of carbon exists on the catalytic surface in the shape of carbon nanotubes and amorphous carbon.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118305108-fx1.jpg" width="265" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 316〈/p〉 〈p〉Author(s): Hong Nie, Huifeng Li, Qinghe Yang, Dadong Li〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉For environmental protection and efficient utilization of oil resources, higher requirements for the selectivity, activity and stability of hydrotreating catalysts are proposed. To effectively solve this issue, the influence of structure and stability of active phase on catalytic performance of hydrotreating catalysts was reviewed. It was realized that the active phase structure essentially depends on the extent of metal-support interaction, and can be properly designed by adjusting catalyst preparation parameters (e.g. support properties and metal precursors in the impregnating solution) and sulfidation conditions (e.g. pressure, temperature and gas composition). As the hydrotreating conditions for gasoline, diesel and residue become severer, the active phase structures need much higher stability. The selectivity of gasoline hydrodesulfurization can be notably increased by selective post-treatment of the active phase structure. Well-dispersed active phase slabs with moderate metal-support interaction are needed for highly active and stable CoMo and NiMo diesel catalysts. New generation NiMo catalyst by strengthening metal-support interaction exhibits better residue hydrodesulfurization activity and stability.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092058611830573X-fx1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 319〈/p〉 〈p〉Author(s): Hongge Cui, Xinli Tong, Linhao Yu, Ming Zhang, Yongtao Yan, Xuli Zhuang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An efficient tandem process for the oxidative condensation of furfural (FUR) with ethanol catalyzed by the copper/azodicarboxylate system has been developed. Firstly, the hydrogen transferring between FUR and ethanol is investigated under the nitrogen atmosphere by combining the azodicarboxylate and alkali carbonates, in which the main products are furfuryl alcohol and furan-2-acrolein. In the following, the cuprous halides and molecular oxygen are supplemented into the reaction system in order to improve the yield of furan-2-acrolein; therein, it is found that furfuryl alcohol is further oxidized and the selectivity of furan-2-acrolein is obviously elevated when CuI and o-phenanthroline (Phen) are used as the co-catalysts. Under optimal reaction conditions, 82.5% conversion of FUR with 87.7% selectivity of furan-2-acrolein is obtained with the assistance of diethyl azodicarboxylate (DEAD) and potassium carbonate. At last, a possible catalytic mechanism is proposed for the oxidative condensation reaction between FUR and ethanol in the presence of O〈sub〉2〈/sub〉.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉A Cu-azodicarboxylate catalyzed efficient oxidative condensation of biomass-derived furfural with ethanol has been successfully performed in the presence of molecular oxygen.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118303195-fx1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 319〈/p〉 〈p〉Author(s): Zhiquan Yu, Anjie Wang, Shan Liu, Yunlong Yao, Zhichao Sun, Xiang Li, Yingya Liu, Yao Wang, Donald M. Camaioni, Johannes A. Lercher〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉SiO〈sub〉2〈/sub〉, HZSM-5 and Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 were used to support nickel phosphides to prepare hydrodeoxygenation (HDO) catalysts. The nickel loading was kept at 20 wt% while the Ni/P molar ratio was varied among 3, 2, and 1 in the preparation by incipient wetness impregnation. XRD characterization revealed that Ni〈sub〉3〈/sub〉P, Ni〈sub〉12〈/sub〉P〈sub〉5〈/sub〉, and Ni〈sub〉2〈/sub〉P as the major crystal phases were obtained at Ni/P ratio of 3, 2, and 1, respectively, on SiO〈sub〉2〈/sub〉 and HZSM-5. When Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 was used as the support, nickel metal rather than nickel phosphides was generated. Among SiO〈sub〉2〈/sub〉-supported nickel phosphides, Ni〈sub〉3〈/sub〉P exhibited highest hydrogenation activity and catalytic performance in phenol HDO. Ni〈sub〉3〈/sub〉P/HZSM-5 showed the high catalytic performance in HDO of phenol as well as catechol and o-cresol, with Ni〈sub〉3〈/sub〉P as the hydrogenation site and the acid sites in HZSM-5 zeolite as the dehydration site. The strong acidity in HZSM-5 also facilitated the isomerization of cycloalkanes at elevated temperatures.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Support affects the formation of metal phosphides as well as their performance in hydrodeoxygenation. Ni〈sub〉3〈/sub〉P/HZSM-5 shows significantly high performance in aqueous phase hydrodeoxygenation of phenol, catechol, and o-cresol.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118305807-fx1.jpg" width="383" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 319〈/p〉 〈p〉Author(s): Xinghua Zhang, Jiejie Tang, Qi Zhang, Qiying Liu, Yuping Li, Lungang Chen, Chenguang Wang, Longlong Ma〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉MoO〈sub〉3〈/sub〉 catalyst was prepared by calcination using (NH〈sub〉4〈/sub〉)〈sub〉6〈/sub〉Mo〈sub〉7〈/sub〉O〈sub〉24〈/sub〉·4H〈sub〉2〈/sub〉O as precursor and was characterized by XRD, XPS, H〈sub〉2〈/sub〉-TPR and low temperature N〈sub〉2〈/sub〉 adsorption. Hydrodeoxygenation of phenol was conducted to investigate the catalytic performance of MoO〈sub〉3〈/sub〉 catalyst at lower H〈sub〉2〈/sub〉 pressure. Effects of reaction temperature, reaction time and N〈sub〉2〈/sub〉 partial pressure on the phenol conversion and product distribution were tested carefully. MoO〈sub〉3〈/sub〉 catalyst was found to preferentially produce arenes with high selectivity, while at lengthened reaction time cyclohexane selectivity was increased gradually. Oxygen vacancy site of MoO〈sub〉3〈/sub〉 (Mo〈sup〉5+〈/sup〉) was deemed to be the active center in the hydrodeoxygenation of phenol, which accounts for the cleavage of C〈sub〉AR〈/sub〉-OH to benzene. In addition, MoO〈sub〉3〈/sub〉 catalyzed HDO reactions were further tested using different phenolic compounds as reactants. Experimental results suggest MoO〈sub〉3〈/sub〉 catalyst can be widely applied in the conversion of diverse lignin-derived phenolic compounds conversion to aromatic hydrocarbons.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118303481-fx1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 316〈/p〉 〈p〉Author(s): Liying Sun, Yaquan Wang, Hengbao Chen, Chao Sun, Fanjun Meng, Fei Gao, Xiao Wang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A series of ZnZSM-5 zeolites with hierarchical pores were prepared by a seed-induced method with the addition of cetyltrimethylammonium bromide (CTAB). The influence of the amounts of CTAB on the physicochemical properties of the zeolites was investigated by XRD, FTIR, SEM, TEM, N〈sub〉2〈/sub〉 adsorption and desorption, ICP-OES, XPS, NH〈sub〉3〈/sub〉-TPD and TG analysis. The results showed that Zn was partially incorporated in the zeolite framework; the addition of CTAB in the synthesis reduced the primary crystal size of the zeolite, but increased the specific surface area and mesopore volume. The catalytic performance of the prepared zeolites was evaluated for methanol to aromatics reaction in a fixed bed reactor. The lifetime of the catalysts was greatly enhanced by the addition of CTAB in the synthesis. The incorporation of Zn increased the selectivity of aromatics.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉The presence of Zn species and CTAB during synthesis had an important effect on the aggregate morphology and catalytic performance.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118300154-fx1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 319〈/p〉 〈p〉Author(s): Hui Wang, Hongfei Lin, Ying Zheng, Siauw Ng, Hilary Brown, Yu Xia〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This work presents a cost-effective abundant kaolin-based cracking catalyst that has high deoxygenation, mild cracking, and low dehydrogenation performances for waste cooking oil (WCO) upgraded into organic liquid products (OLPs). Acid treated kaolin (ATK) exhibited high yield of 74.4% and high quality liquid products with high oxygen removal of 93.8% and low aromatic contents of 22.5%. The reference catalyst, a commercial petroleum catalyst (CC) could eliminate the most of oxygen (90.8%) but produced too many unexpected aromatics (55.8%). The density of weak Lewis acids was related to the deoxygenation capability. The density of Bronsted acids contributed to hydrogen transfer reactions. The total amount of Bronsted acids was correlated to cracking capability. The cracking by CC primarily followed carbonium ion reaction mechanism, whereas those by the kaolin-based catalysts complied more with free radical reaction mechanism. The deoxygenation active sites were characterized by CH〈sub〉3〈/sub〉COOH-TPD for the first time.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118305169-fx1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 26 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Sai Zhang, Pengcheng Gu, Ran Ma, Chunting Luo, Tao Wen, Guixia Zhao, Wencai Cheng, Xiangke Wang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Graphitic carbon nitride (g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉), a conjugated polymer semiconductor, has drawn increasing attention in environmental photocatalysis over the past decade, owing to its highly chemical stability, low cost and suitable electronic structure with a mild energy gap (∼ 2.7 eV). Whereas, its practical applications in wastewater purification are still faced with huge challenges, such as insufficient visible light absorption, low electronic conductivity, poor surface area and fast recombination of photoinduced charge carriers. The modification of g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 by coupling with other nanomaterials or forming unique nanostructures have been confirmed as valuable strategies. In this review, we give a comprehensive introduction about the recent developments in engineering g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 by constructing heterostructures or diverse morphologies to improve its photodegradation performance for the photocatalytic degradation of persistent organic pollutants. Such heterojunctions contain metal/g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉, g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉/C-based material and many other binary or ternary composites, and these special morphologies normally include nanorods, nanowires, nanotubes, nanosheets, porous architectures and other different tunable nanostructures. Several enhanced photocatalytic mechanisms for these nanohybrids under visible light irradiation have been explicated in detail, and future perspectives are also concluded in this review.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118308885-ga1.jpg" width="200" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 316〈/p〉 〈p〉Author(s): Bingyu Lin, Yunjie Guo, Chenfeng Cao, Jun Ni, Jianxin Lin, Lilong Jiang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Carbon-supported Ru catalyst is arguably the most promising applications of Ru catalysts in ammonia synthesis. However, the insufficient stability of Ru/C catalyst greatly limits its applications, and the elimination of surface oxygen species by carbon preactivation has been imagined to be an efficient method for preparing Ru/C catalyst with high stability. However, herein we demonstrate that the presence of some oxygen functional groups in carbon support of Ba-promoted Ru/C catalyst was beneficial not only to the dispersion of Ru particles, but also to the low-temperature hydrogen adsorption. Furthermore, the formation of CO during heat treatment, which was closely related to oxygen groups, enhanced the ammonia synthesis activities of carbon-supported Ru catalyst with Ba promoter. Therefore, Ru catalyst supported on carbon with a large number of surface oxygen groups showed higher activity. Understanding the effect of carbon support surface on the activity and stability of Ru/C provides a basis for the rational design of the optimal carbon-supported metal catalyst for ammonia synthesis and related reactions.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118300087-fx1.jpg" width="312" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 29 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): J.C. Durán-Álvarez, R. Del Angel, D. Ramírez-Ortega, D. Guerrero-Araque, R. Zanella〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Deposition-precipitation has demonstrated to efficiently support tiny and well dispersed Au nanoparticles on the surface of various semiconductors, although its efficiency is low when the isoelectric point (IEP) of the support falls below 3.0. This work proposes an alternative method for the deposition of Au metallic nanoparticles on WO〈sub〉3〈/sub〉 (IEP ∼ 0.5), which is based on the cationic adsorption process. WO〈sub〉3〈/sub〉 and [Au(en)〈sub〉2〈/sub〉]Cl〈sub〉3〈/sub〉 complex were synthesized by known methods, and the adsorption efficiency of the complex on the WO〈sub〉3〈/sub〉 surface was tested using different pH values (1, 4, 7 and 10) and reaction times (2, 12 and 16 h). Complete deposition of Au on WO〈sub〉3〈/sub〉 was achieved upon 16 h and pH = 10. Using the optimal reaction conditions, several Au loadings were successfully deposited on WO〈sub〉3〈/sub〉, namely 0.1, 0.5, 1.0 and 3.0 wt.%, giving as a result highly dispersed 3–4 nm Au nanoparticles on the WO〈sub〉3〈/sub〉 surface. The functionality of the synthesized materials was evaluated via the photocatalytic production of hydrogen. The highest performance was obtained using the (0.5 wt.%) Au/WO〈sub〉3〈/sub〉 material. Electrochemical characterization showed how Au nanoparticles modified the Fermi level toward more negative values, increasing the photocatalytic reduction of water molecules at the optimal Au loading.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118316055-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 16 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Vyacheslav N. Kuznetsov, Nadezhda I. Glazkova, Ruslan V. Mikhaylov, Anna V. Kozhevina, Nick Serpone〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We herein report on the photophysics of color centers in visible-light-active (VLA) rutile titania ceramics and titania powder resulting from the photoformation and separation of charge carriers explored by a diffuse reflectance (DR) spectroscopic and kinetic study using a cryostat-type accessory for a Cary 5000 spectrophotometer after exposure of the titanias to UV radiation and Vis-light illumination. The action spectrum of the photoformation of Ti〈sup〉3+〈/sup〉 at 90 K accorded fully with the absorption spectrum of intrinsic defects in the as-synthesized TiO〈sub〉2〈/sub〉. The photoinduced absorption spectra consisted of a set of individual absorption bands attributable to several different Ti〈sup〉3+〈/sup〉 centers. Analysis of the dependencies of the photoformation of separate centers on the wavelength of illumination and light exposure provided extraction of specific Ti〈sup〉3+〈/sup〉 centers putatively attributed to centers with 〈strong〉〈em〉excess negative charge〈/em〉〈/strong〉 {2Ti〈sup〉3+〈/sup〉 + V〈sub〉o〈/sub〉〈sup〉2+〈/sup〉} 〈strong〉⟵→〈/strong〉 {Ti〈sup〉δ+〈/sup〉 + V〈sub〉o〈/sub〉〈sup〉2+〈/sup〉} with 3 〉 δ 〉 2 formed at significantly high concentration upon maximal exposure to Vis-light illumination. Thermoprogrammed annealing (TPA) spectra of Ti〈sup〉3+〈/sup〉 color centers photoinduced in VLA TiO〈sub〉2〈/sub〉 displayed temperature dependencies of the rate of detrapping of the photoinduced holes observed optically through annihilation of the Ti〈sup〉3+〈/sup〉 centers. The TPA spectra in the range 90–500 K consisted of a set of first-order peaks corresponding to the traps, whose depths ranged from ∼0.2 eV (peak at 130 K in powder specimen) to 1.06 eV (peak at 455 K in the ceramics). The highest rate of recombination of holes released to the valence band with Ti〈sup〉3+〈/sup〉 centers, an event attributable to the Ti〈sup〉δ+〈/sup〉 centers, provided TPA spectra that clearly manifested the existence of shallow traps. We also report mass spectrometric evidence of the photoformation of electrons and holes in VLA TiO〈sub〉2〈/sub〉 under Vis-light illumination through an examination of the photoadsorption of molecular oxygen and the photodesorption of photoadsorbed oxygen from the surface of powdered VLA titania specimens. Moreover, kinetics of the photodesorption of O〈sub〉2〈/sub〉 under orange light illumination, after the photoadsorption of O〈sub〉2〈/sub〉 stimulated by blue light excitation, provided experimental proof of the occurrence of an additional specific channel toward the photoactivation of VLA TiO〈sub〉2〈/sub〉 via the photoexcitation of photoinduced Ti〈sup〉3+〈/sup〉 color centers.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118311532-ga1.jpg" width="267" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 316〈/p〉 〈p〉Author(s): Rong Guo, Zhengkai Cao, Xiangchen Fang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The CoMo type and NiMo type catalysts with high amounts of Bronsted (B) acid sites, referred to as FHUDS-5 and FHUDS-6 respectively, were investigated for their hydrogenation performances including alkylation, hydrodesulfurization (HDS), and hydrodenitrogenation (HDN). The results demonstrated that, as hydroprocessing different diesel feedstocks, appropriate types of catalyst or their stacking system should be considered to achieve optimal HDS performance. As processing the feedstock with high sulfur content but low contents of nitrogen and aromatics, the CoMo type FHUDS-5 exhibited the highest HDS efficiency. On the other hand, the NiMo type catalyst FHUDS-6 presented the highest HDS and HDN efficiency as processing the feedstock with high amounts of nitrogen and aromatics. As processing the feedstock with medium contents of nitrogen and aromatics, the catalysts stacking system of FHUDS-6/FHUDS-5 presented the highest HDS efficiency due to their synergistic effects. The commercial applications for these hydroprocessing catalysts for the ultra-deep HDS on diesel at different refinery plants were also reported.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118305558-fx1.jpg" width="360" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 316〈/p〉 〈p〉Author(s): Hualiang An, Guangjie Zhang, Xinqiang Zhao, Yanji Wang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ca-Zn-Al oxide was prepared by co-precipitation method and the effect of preparation conditions on its catalytic performance was investigated. The Ca-Zn-Al oxide exhibited an excellent catalytic activity and stability for one-pot synthesis of dimethyl carbonate (DMC) from urea, 1,2-propylene glycol (PG), and methanol. XRD characterization and activity evaluation results indicated that new crystalline phases Ca〈sub〉3〈/sub〉Al〈sub〉4〈/sub〉ZnO〈sub〉10〈/sub〉 and ZnAl〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 could create a synergistic effect with CaO and ZnO, being responsible for the excellent catalytic performance of Ca-Zn-Al oxide. Response surface methodology (RSM) was used to investigate the effect of operating variables and to optimize conditions for the first-step reaction of PG and urea to propylene carbonate. Then the effect of reaction conditions for the transesterification of propylene carbonate with methanol to DMC was also investigated. As a result, a DMC yield of 84.7% was obtained under the appropriate reaction conditions. The Ca-Zn-Al oxide could be reused for four times without a significant change in its catalytic activity.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118301925-fx1.jpg" width="263" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 319〈/p〉 〈p〉Author(s): Zhe An, Wenlong Wang, Suhua Dong, Jing He〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The synthesis of 2,5-dimethylfuran (DMF) from 5-hydroxymethylfurfural (HMF) is a highly attractive route to a renewable fuel. Herein, we propose that non-noble Co-based catalysts derived from layered double hydroxides (LDHs) can efficiently convert HMF into 2,5-dimethylfuran (DMF). Homogeneous elemental distributions of the Co-containing LDH precursors facilitate good dispersion of Co and the metal oxide species and also strong interaction between them on the resulting catalyst, therefore exhibiting superior reactivity under mild condition. Through fine modulation of the metal nanostructure, a high DMF yield of 74.2% at a mild reaction temperature of 130 °C with 0.7 MPa H〈sub〉2〈/sub〉 can be achieved. The well-distributed Co sites on the metal-support interface are deduced to be responsible for the efficient HMF and H〈sub〉2〈/sub〉 activations. The Co-based catalysts present good active both on hydrogenation of C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/dbnd"〉O and C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O, which have great potential for biomass utilization.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Well-distributed Cobalt-based catalysts derived from layered double hydroxides are proposed for efficient selective hydrogenation of 5-hydroxymethyfurfural to 2,5-methylfuran.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118303213-fx1.jpg" width="306" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 316〈/p〉 〈p〉Author(s): Junjie Ding, Jiashu Chen, Zebao Rui, Yilang Liu, Pintian Lv, Xikun Liu, Hongqi Li, Hongbing Ji〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Catalytic removal of trace HCHO at room temperature over supported noble metal catalysts has been an interesting topic. For practical application, both the intrinsic activity of the catalyst and mass transfer should be taken into consideration due to the low indoor HCHO concentration. Herein, we provide a facile way for simultaneously enhancing HCHO adsorption, storage and oxidation over Pt/ZSM-5 by aqueous NaOH treatment, as well as synchronous pore structure and surface hydroxyl groups amelioration. With proper amount of NaOH modification, Pt/ZSM-5 shows a high HCHO conversion above 99% and a (〉) 1000 h good stability at 30 °C, a space velocity of 30000 mL h〈sup〉−1〈/sup〉 g〈sup〉−1〈/sup〉 and initial 50 ppm HCHO with a low 0.2 〈em〉wt.〈/em〉% Pt loading amount, which is among the best of state-of-the-art novel metal catalysts. These results show that the consideration of both morphology manipulation and surface hydroxyl groups tailoring is important in designing an efficient HCHO oxidation catalyst.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118300397-fx1.jpg" width="268" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Vito Cristino, Gelsomina Longobucco, Nicola Marchetti, Stefano Caramori, Carlo Alberto Bignozzi, Annalisa Martucci, Alessandra Molinari, Rita Boaretto, Claudia Stevanin, Roberto Argazzi, Maurizio Dal Colle, Renzo Bertoncello, Luisa Pasti〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this contribution we have explored the applications of WO〈sub〉3〈/sub〉 based nanomaterials to the degradation of Ketoprofen and Levofloxacin, selected among the most widely used anti-inflammatory and analgesic species and antibiotics and representing thus ubiquitous water contaminants of emerging concern. Compared to conventional photocatalytic conditions, which were not effective in the oxidative degradation of Ketoprofen, the application of the electric bias was successful in promoting a 50% Ketoprofen degradation after 5 h illumination, with a degradation rate constant of 0.22 h〈sup〉−1〈/sup〉. A similar improvement was found with Levofloxacin. The degradation rate was further accelerated by exploiting WO〈sub〉3〈/sub〉 films modified with β25 zeolites which achieved, on the same time scale, 〉65% degradation with Ketoprofen and ca. 90% with Levofloxacin. The complete disappearance of the oxidation intermediates of these two drugs was observed on a time scale of ca. 20 h, indicative of the achievement of complete drug mineralization at the illuminated β25/WO〈sub〉3〈/sub〉 interface under 1 sun illumination.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092058611830765X-ga1.jpg" width="214" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 13 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): J. Krýsa, M. Baudys, X. Vislocka, M. Neumann-Spallart〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Immobilized composite powders of titania with various carbon content were tested with respect to their efficiency of degradation of impurities in air (toluene, acetaldehyde, NO) under UVA illumination in a single-pass flow-through reactor and ISO conditions. Addition of active carbon (AC) to titania resulted in increased conversion efficiencies of some pollutants. In the case of toluene as a test pollutant, an AC/TiO〈sub〉2〈/sub〉 ratio of 0.23 in the photocatalyst led to 47% conversion efficiency (against 36% without carbon). The presence of water in the gaseous reaction mixture was found to be essential for the degradation reactions to occur with an optimum at 50% RH. In gas phase degradation experiments with NO, a carbon to titania ratio of 0.7 led to the best results. For long time irradiation, accumulation of one of the reaction products, HNO〈sub〉3〈/sub〉, in the catalyst layer was noticed resulting in a lower production of NO〈sub〉2〈/sub〉. Photocatalytic removal of acetaldehyde was not improved by carbon loading; pure titania showed already a conversion efficiency of 75%. In general, although carbon loading helped in adsorption and preconcentration of pollutants, light absorption by carbon counteracted this effect.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Removed NO and NOx and formed NO〈sub〉2〈/sub〉 for composite photocatalysts of various AC/TiO〈sub〉2〈/sub〉 ratio.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118306278-ga1.jpg" width="219" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 316〈/p〉 〈p〉Author(s): Ke Zhang, Lin Li, Yuan Liu, Yuejin Li, Xiaoling Wang〈/p〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 319〈/p〉 〈p〉Author(s): Hongye Zhao, Jianxiu Hao, Yanpeng Ban, Yufei Sha, Huacong Zhou, Quansheng Liu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hydrogenation of biomass-derived ethyl levulinate (EL) to gamma-valerolactone (GVL) is an important step in the conversion of sustainable biomass resources into value-added chemicals. Exploration of highly efficient and easily obtainable catalysts is crucial for the large-scale application. In this work, a series of cobalt catalysts were prepared by one-step reduction route in different solvents and applied into the conversion of biomass-derived EL to GVL. Common solvents, including water, methanol, ethanol, glycol and glycerin were attempted as the solvent. Both the solvent effect on the catalyst synthesis and the hydrogenation reaction parameters during the conversion of EL into GVL were systematically investigated. The catalysts were characterized by SEM-EDS, TEM, powder XRD, N〈sub〉2〈/sub〉 adsorption-desorption, and XPS. The results demonstrated that the solvents had significant influences on the morphology and structure of the as-prepared catalysts, which changed from dendrite (in water) to spheres (in glycerin). All the catalysts prepared in different solvents were effective for the conversion of EL. Under the optimized conditions, a high GVL yield of 91.4% was achieved when using cobalt catalyst prepared in ethanol at relatively mild reaction conditions. Furthermore, the catalyst could be reused at least 6 times without significant loss of the catalytic activity. As far as we know, this is the first work on the application of cobalt catalysts, synthesized by one-step solution phase reduction method, in the conversion of EL into GVL in biomass utilization.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Novel and efficient cobalt catalysts with controlled shapes were synthesized by one-step solution phase reduction method in various solvents and applied into the conversion of biomass derived EL into GVL.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118314263-ga1.jpg" width="233" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: Available online 26 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Yuanxin Deng, Yifei Xiao, Yi Zhou, Teng Zeng, Mingyang Xing, Jinlong Zhang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Realizing the efficient treatment of acid drainage using semiconductor photocatalysis at low pH values remains a challenging and necessary project for widespread heavy metal ions and organic aromatic pollutants. Here, the synergistic photocatalytic remediation of hexavalent chromium and phenol under visible light was studied with the purpose of both environmental remediation and sustainable development in mind. Using a structural engineering strategy, the typical CdS-based heterojunction with outer nanocrystal cluster protection is unprecedentedly endowed with the efficient and recyclable capability of a visible-light-driven photocatalysis for the remediation of pollutants in strong acidic conditions. Owing to the structure-enabled acidic stability, the simultaneous remediation of Cr(VI) and phenol can be undertaken in an efficient and recyclable mode at pH = 2.0–7.0. This study fundamentally evolves a representative photocatalytic system into one with more industrial and practical applications foracid drainage purification.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118309222-ga1.jpg" width="412" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 13 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Hanuk Lee, Jae-Woo Park〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Titanium-doped stainless steel nanotubes (SSNT@Ti) were synthesized by electrochemical anodization and chemical reduction. Benzoic acid was subjected to degradation by photolysis, photocatalysis, photolytic oxidation, and photocatalytic oxidation using SSNT@Ti under simulated solar irradiation in a laboratory-scale system. Photocatalytic oxidation employing SSNT@Ti along with hydrogen peroxide (H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉) as an oxidant exhibited the highest degradation rate (8.08 × 10〈sup〉−3〈/sup〉 s〈sup〉-1〈/sup〉). Pseudo-first-order rate constants were expressed as functions of initial benzoic acid concentration, irradiation intensity, and initial H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 concentration. An empirical kinetic model was developed based on the kinetic equations in respect of each factor, which resulted in good prediction of the photocatalytic oxidative degradation rates (R〈sup〉2〈/sup〉 = 0.98). Compared to the other photocatalysts reported in the literature, this economical SSNT@Ti showed competitive photocatalytic ability. The 〈sup〉〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/rad"〉〈/sup〉O〈sub〉2〈/sub〉- and ∙OH played dominant roles for the degradation of benzoic acid in the photocatalysis and photocatalytic oxidation, respectively. SSNT@Ti was stable during five repeated experiments, and it maintained its catalytic activity.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118302803-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Baoyue Cao, Jianghong Zhao, Yan Yu, Wei Li, Shan Xu, Ruilin Sun, Xiangting Wang, Jinyi Guo, Chunsheng Zhou, Hongxia Zhang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The current artificial photocatalysts often suffer from photocorrosion-induced irreversible damage and low efficiency. Here we report that under the UV irradiation of aqueous isopropanol solution, which photolysis to produce acetone and consume photoelectron in time and be oxidized to form acetone. And then the platinum nanoparticles can coordinate with product acetone on their surfaces to create a unique photocatalysis system for high efficient hydrogen evolution. In this system, the inherent close bonding between photoactive surface complexes and metallic platinum sites creates an efficient donor-acceptor system for charge transfer and leads to high efficiency, with hydrogen generation rate of 8.01 mmol⋅ h〈sup〉−1〈/sup〉. Furthermore, in the presence of isopropanol the photoactive acetonyl-platinum complexes are generated reproducibly via a continuous isopropanol-to-acetone conversion and thus work sustainably. This finding indicates the possibility of artificially creating self-reproducible systems to drive photocatalytic reactions efficiently and robustly.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118303894-ga1.jpg" width="318" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 316〈/p〉 〈p〉Author(s): Zhong-Pan Hu, Hui Zhao, Chong Chen, Zhong-Yong Yuan〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Porous carbons derived from castanea mollissima shell are prepared by a simple alkali activation method, and employed as metal-free catalysts for catalytic dehydrogenation of propane to propylene, exhibiting high catalytic performance. The chemical compositions and structural properties of the obtained carbon catalysts are characterized by XRD, SEM, TEM, XPS, TG, He-TPD, Raman spectroscopy and nitrogen sorption techniques, revealing the presence of rich micro-/meso-/macropores and numerous oxygenated functional groups. The catalytic results suggest that the porous carbons obtained by activation of castanea mollissima shell with KOH at 700 °C exhibit the best catalytic performance. And the porous structure with high surface area and abundant oxygen-containing groups of the carbon catalysts are responsible for the high catalytic performance. This catalyst is derived from biomass, has much low cost, and can be widely used in various reactions including propane dehydrogenation.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Biomass carbons with hierarchical porous structure and high surface area are prepared by KOH activation of castanea mollissima shell, exhibiting high catalytic activity, selectivity and stability in direct dehydrogenation of propane to propylene.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118300105-fx1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 319〈/p〉 〈p〉Author(s): Qianqian Huang, Weiqiang Yu, Fang Lu, Rui Lu, Xiaoqin Si, Jin Gao, Jie Xu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Metal nanoparticles catalysts are widely used in hydrogenation of carboxylic acids and their derivatives, which are significant reactions to produce high-value compounds such as alcohols and lactones. These reactions were usually carried out in liquid phase at harsh conditions with high temperature and pressure, however, catalysts deactivation frequently occurred since small metal NPs were inclined to migrate and aggregate as well as dissolve and leach in such acid systems. Thus, it’s a great challenge to prepare catalysts with highly dispersed small metal NPs with good stability and durability. Herein we propose a novel one-pot co-synthesis method to prepare highly dispersed and stabilized nanometal catalysts that small Ru NPs embedded in carbon species coated on silica nanospheres. Ru precursors were doped directly in the synthesis of RF coated silica spheres along with the polymerization of resorcinol–formaldehyde, and following the process of carbothermal reduction. Aqueous hydrogenation of itaconic acid was used as a probe reaction, which could produce high-value products such as methylsuccinic acid and methyl butyrolactone. The as-prepared catalysts had uniform dispersion of small Ru NPs with core-shell structure of resin coated silica nanospheres, exhibited good hydrogenation activity and stability with no obvious loss of yield for methyl butyrolactone and less sintering in recycling tests.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Ru NPs embedded in carbon shell coated on silica nanospheres were fabricated via one-pot co-synthesis strategy combined with carbothermal reduction, and performed high activity and stability in the hydrogenation of itaconic acid to methyl butyrolactone.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118303183-fx1.jpg" width="216" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 316〈/p〉 〈p〉Author(s): Liancheng Bing, Guangjian Wang, Kaifeng Yi, Aixiu Tian, Fang Wang, Chunze Wu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cu-SAPO-34 catalysts with three different Cu contents (0.6 wt%, 1.1 wt% and 1.9 wt%) were prepared via one-pot synthesis method. Cu-SAPO-34 with Cu content at 1.1 wt% was found to be the best catalyst when considering both low temperature activity and high temperature stability. Then an economical and green way was attempted for the synthesis of Cu-SAPO-34 catalysts by recycling waste mother liquids. The synthesized samples were characterized by XRD, BET, SEM, NH〈sub〉3〈/sub〉-TPD, H〈sub〉2〈/sub〉-TPR, and EPR. It was found that, after three recycles of mother liquids, the one-pot synthesized Cu-SAPO-34 catalyst exhibited high crystallinity, textural properties, acidity, and available copper, as well as superior catalytic activity for the selective catalytic reduction of NO with NH〈sub〉3〈/sub〉 as compared to the initial Cu-SAPO-34 catalyst.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118300877-fx1.jpg" width="377" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 319〈/p〉 〈p〉Author(s): Sadra Souzanchi, Laleh Nazari, Kasanneni Tirumala Venkateswara Rao, Zhongshun Yuan, Zhongchao Tan, Chunbao (Charles) Xu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Isomerization reactions of glucose into fructose in aqueous media were studied in a continuous-flow tubular reactor using different heterogeneous solid base catalysts, including calcined-rehydrated hydrotalcite, magnesium oxide, Amberlyst A21 ion exchange resin and two commercial hydrotalcite catalysts. The catalysts were characterized and their activities for glucose isomerization were compared. The most active catalyst was found to be magnesium oxide, which showed the highest glucose conversion (36.3%) and highest fructose yield (22.8%) at 100 °C. Among all catalysts, the calcined-rehydrated hydrotalcite showed the highest selectivity towards fructose, reaching 78% at 100 °C. It was also found that increasing the reaction temperature had positive effects on glucose conversion and fructose yield for both activated hydrotalcite and MgO catalysts. The fructose yield at 120 °C attained 19.5% and 25.1% with the activated hydrotalcite and MgO catalysts, respectively. The catalytic activity of hydrotalcite calcined at 450 °C for glucose isomerization reaction was found to be greater that calcined at 350 °C. The hyrdotalcite and magnesium oxide catalysts were observed to be stable in the four hours of continuous tests on stream. TGA analyses of the used catalysts proved the formation of undesired insoluble by-products, mainly humins, on the surface of the used catalysts.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Activity of the solid base catalysts tested in glucose isomerization reaction at 100 °C.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118303250-fx1.jpg" width="334" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 316〈/p〉 〈p〉Author(s): Jianren Wei, Wanling Shen, Jun Zhao, Chengwei Zhang, Yonghua Zhou, Hongyang Liu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, boron, sulfur and phosphor doped g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 materials (defined as CNBF, CNSF and CNPF, respectively) were successfully prepared by thermal copolymerization of dicyandiamide and imidazole ionic liquids. The CNBF catalysts exhibited significantly enhanced activity in various Knoevenagel condensation of aldehyde with malononitrile, which were typical base-catalyzed reactions, comparing with CNSF and CNPF catalysts. The detailed characterizations of Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), High angle annular dark field-scanning transmission electron microscopy (HADDF-STEM) and 〈sup〉11〈/sup〉B solid-state MAS NMR showed that boron was evenly doped in tri-s-triazine rings of g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 by substituting the carbon sites. In addition, CO〈sub〉2〈/sub〉 Temperature programed desorption (CO〈sub〉2〈/sub〉-TPD) characterizations indicated that the basic site concentration of CNBF catalysts was proportional to the doped boron content. Excluding the effect of specific surface area, the catalytic activity of CNBF catalysts followed the order CNBF-0.1 〈 CNBF-0.3 〈 CNBF-0.5 〈 CNBF-0.7, which was the same as that of boron content and basic site concentration. The catalytic performance revealed that boron-doping was an effective strategy to enhance the basicity of g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉. This study will put forward the further application of boron-doped or boron-dominant two dimensional materials towards metal-free heterogeneous base catalysis.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Boron-doping is an effective strategy to enhance the basicity of g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 in Knoevenagel condensation as metal-free catalyst.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118301147-fx1.jpg" width="366" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 316〈/p〉 〈p〉Author(s): Fang Jin, Yangchun Fan, Ming Yuan, Feng Min, Guiying Wu, Yigang Ding, Gilbert F. Froment〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The single-event kinetic modeling approach is extended to the ethene oligomerization process with products including paraffins and olefins, cyclic molecules and aromatics. The reaction network of olefin oligomerization on ZSM-5 with elementary steps of de/protonation, isomerization, alkylation, 〈em〉β〈/em〉-scission, cyclization and hydride transfer is computer-generated and consists of 10,456 elementary steps involving 2567 species within the up to C〈sub〉8〈/sub〉 range. The fast elementary steps: de/protonation and isomerization are considered to reach quasi-equilibrium. The single-event kinetics approach allows the reduction of the number of independent kinetic parameters to 30. The kinetics of the model was then applied to 13 groups of isomers continuity equation with the kinetic data obtained from experimentation in a fixed bed isothermal reactor. Five space times and three temperatures were investigated. The model parameters were obtained using a combination of the genetic algorithm and the Levenberg-Marquardt approach. The single-events model is capable of correctly simulating the experimental data.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118305893-fx1.jpg" width="437" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 13 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Xinhan Zhang, Zhimin Yuan, Jiachuan Chen, Guihua Yang, Dionysios D. Dionysiou, Baibiao Huang, Zaiyong Jiang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉As far as we know, the CO〈sub〉2〈/sub〉 photoconversion reaction with H〈sub〉2〈/sub〉O includes two important steps. One step is CO〈sub〉2〈/sub〉 photoreduction (photogenerated electrons) while the other step is the oxidation of water (photogenerated holes). It is obvious that the oxidation of water is also the key step in the CO〈sub〉2〈/sub〉 photoconversion reaction. However, little research has been done to improve the oxidation of water, thereby indirectly improving the photocatalytic CO〈sub〉2〈/sub〉 reduction property of TiO〈sub〉2〈/sub〉. Moreover, CO〈sub〉2〈/sub〉 adsorption capacity is also considered as an important limiting factor for the CO〈sub〉2〈/sub〉 photoconversion activity. Therefore, in this paper, CoPi (an amorphous cobalt-phosphate-based material) with high CO〈sub〉2〈/sub〉 adsorption capacity was successfully immobilized on the surface of TiO〈sub〉2〈/sub〉 nanosheets and served as a hole-cocatalyst to trap holes, thereby delaying the recombination of photogenerated electrons and holes and providing more CO〈sub〉2〈/sub〉 gas to take part in the CO〈sub〉2〈/sub〉 reduction reaction. Hence, the TiO〈sub〉2〈/sub〉/CoPi exhibited much better CO〈sub〉2〈/sub〉 photoconversion performance in water compared to pristine TiO〈sub〉2〈/sub〉.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118314032-ga1.jpg" width="312" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 319〈/p〉 〈p〉Author(s): Hui Xin, Wenjun Zhou, Keyao Zhou, Xiangze Du, Dan Li, Changwei Hu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nickel phosphides were known to be promising substitute for noble metal used in various catalysts. The traditional method of controlling the growth of nickel phosphide species, including Ni〈sub〉2〈/sub〉P, Ni〈sub〉3〈/sub〉P, and Ni〈sub〉12〈/sub〉P〈sub〉5〈/sub〉, was either modulating Ni/P molar ratio or changing support. Here, we report a new method to control the growth of nickel phosphide species by tuning the types of surface oxygenated group types on activated carbon. The pretreatment of activated carbon with HNO〈sub〉3〈/sub〉 remarkably increased the content of 〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/dbnd"〉O groups. In the preparation process of activated carbon supported nickel phosphide catalyst, the 〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/dbnd"〉O groups might interact with P to form P〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/dbnd"〉O groups. The formed P〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/dbnd"〉O inhibited the reduction of P species at low temperature, and thus inhibited the formation of the nickel phosphides; whereas at 873 K reduction, the formation of pure Ni〈sub〉2〈/sub〉P on activated carbon was enhanced. However, the content of -OH groups content increased on activated carbon treated by NH〈sub〉3〈/sub〉∙H〈sub〉2〈/sub〉O, which might be favorable for the simultaneous formation of Ni〈sub〉2〈/sub〉P and Ni〈sub〉12〈/sub〉P〈sub〉5〈/sub〉 with 1/1 ratio, and the thus formed catalyst displayed excellent catalytic hydrodeoxygenation activity for palmitic acid. Our results demonstrated how simple base and acid pretreatment could be used to tune the interfacial group distribution, hereby providing a strategy to rationally design transition metal phosphide supported catalysts.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118303201-fx1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 316〈/p〉 〈p〉Author(s): Na Wang, Jianli Li, Ruijue Hu, Yulong Zhang, Haiquan Su, Xiaojun Gu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A series of catalysts were prepared using molybdenum sulfide clusters as precursors and their catalytic performance for higher alcohols synthesis was evaluated. It was found that the cluster precursors could provide well-dispersed MoS〈sub〉2〈/sub〉 particles and a number of coordinated unsaturated Mo sites with all the catalysts in varying degrees, which were favorable for the formation of intermediate active phases thereby enhancing catalytic performance. In particular, K-NiMo〈sub〉3〈/sub〉S〈sub〉x〈/sub〉 catalyst obtained by using heterobimetallic cluster NiMo〈sub〉3〈/sub〉S〈sub〉13〈/sub〉 as precursor exhibited the highest activity with the space-time-yield (STY) of total alcohols (497 mg/g/h) and the selectivity of higher alcohols (59.71%), which could be attributed to the interaction effect of the Ni promoter and Mo species and the resultant formation of active phase NiMo〈sub〉3〈/sub〉S〈sub〉x〈/sub〉. Thus, the most key factor for obtaining highly efficient molybdenum sulfide catalysts was to produce a number of coordinated unsaturated sites, on which abundant NiMoS active phase can be formed and the formation of bulk inactive phase should be avoided.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118301937-fx1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 316〈/p〉 〈p〉Author(s): Jin-Hyuk Lee, In-Gu Lee, Wonjin Jeon, Jong-Hyeon Ha, Kwan-Young Lee〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Upgrading of bio-tar derived from fast pyrolysis of sawdust was performed over activated charcoal supported nickel-based catalysts (Ni/AC, NiMo/AC, MgNiMo/AC) under supercritical ethanol conditions. The catalytic activities of the catalysts was compared with those of representative bio-oil upgrading catalysts (Ru/AC, HZSM-5). The MgNiMo/AC catalyst exhibited the highest catalytic performance among the catalysts with a decrease of oxygen content in bio-tar from 31.3 wt% up to 10.8 wt% and the yield of liquid product (75 wt%). The effects of reaction temperature (275–350 °C), reaction time (0–120 min) and bio-tar to ethanol ratio (1/9–4/6) were also studied over the MgNiMo/AC catalyst. In addition, reaction of vanillin which is one of major compounds present in bio-tar was carried out under the same bio-tar upgrading conditions in order to understand the production mechanism of phenolic chemicals.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586117306235-fx1.jpg" width="396" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 316〈/p〉 〈p〉Author(s): Hong-Zi Tan, Zhi-Qiao Wang, Zhong-Ning Xu, Jing Sun, Yu-Ping Xu, Qing-Song Chen, Yumin Chen, Guo-Cong Guo〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Dimethyl carbonate (DMC, (CH〈sub〉3〈/sub〉O)〈sub〉2〈/sub〉CO), as an important and environmentally friendly chemical intermediate, has been widely used in industrial fields. Several large-scale industrial routes of DMC production, e.g., phosgene route, transesterification route, and the liquid-phase oxidative carbonylation of methanol, have been developed to date. Nevertheless, these industrial routes suffer from different drawbacks, such as the use of hypertoxic phosgene as raw material, high production cost, and explosion risk. Currently, vapor-phase methyl nitrite (MN) carbonylation to DMC, a route developed by the UBE Company, can be the most promising new-generation industrial route. This route exhibits many advantages, including environmental friendliness, low cost, and high efficiency. The key to industrialization is the development of an efficient and stable catalyst. Heterogeneous supported Pd-based catalysts have been widely investigated in this system. In this review, we provide detailed introduction regarding the existing DMC synthesis methods and the vapor-phase MN carbonylation to DMC route with related catalyst research progress. Opportunities and challenges for synthesizing DMC are also presented.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118300725-fx1.jpg" width="382" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 27 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Teng Li, Scott Sergio Go Ong, Jianghao Zhang, Chuhua Jia, Junming Sun, Yong Wang, Hongfei Lin〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Biphasic tandem catalytic process (biTCP) is a generalized “one-pot” synthesis approach to produce hydrophobic biofuels or biobased chemicals from relatively hydrophilic biomass feedstocks. In this work, we report our findings on employing the biTCP to convert carbohydrates (such as fructose) to value-added furan derivative chemicals, 2,5-dimethyltetrahydrofuran (DMTHF), 2,5-dimethylfuran (DMF) or 5-methylfurfural (MF). Through the studies of kinetics and probe reactions, the reaction mechanism was explored, in which the key intermediates, such as 5-methylfurfural (MF) and DMF, were identified during the conversion of fructose to DMTHF. The catalytic effects of the different catalysts, H〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 and Pd/AC, partitioned in water and organic phases, respectively, were elucidated. The effect of various organic solvents and process conditions were systematically studied to maximize the production yield of DMTHF. At the optimum conditions, a ∼ 70% yield of DMTHF was achieved from fructose with the hydrophobic Pd/AC and the hydrophilic Brønsted acid catalysts in the water-diethyl ether biphasic solution at 130 °C in 12 h. In addition, the effect of the co-solvent, dimethyl sulfoxide (DMSO), which modulated the distribution of furan products, was also investigated. Finally, the deactivation mechanism of the Pd/AC catalyst was discussed.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118311556-ga1.jpg" width="226" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 29 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): José Lucas Vieira, Marilia Almeida-Trapp, Axel Mithöfer, Winfried Plass, Jean Marcel R. Gallo〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Recent studies have shown that niobium oxide promotes the conversion of glucose and xylose, respectively, to 5-hydroxymetylfufural (HMF) and furfural with moderate or poor selectivities. Herein, we show that niobium oxide acts differently in both reactions. For the conversion of glucose, Nb〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 is an efficient Lewis acid catalyst and an inefficient Brønsted acid. Interestingly, it is more active in the epimerization to mannose than in the isomerization to fructose. It is shown that associating Nb〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 with a Brønsted acid catalyst (such as HCl or Amberlyst〈sup〉®〈/sup〉), the selectivity to HMF can reach up to 50 %. Improving further this selectivity is challenging since Nb〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 has high selectivity to mannose, which is converted to HMF with low selectivity (comparable to glucose). For the xylose conversion, niobium oxide behaves as an actual bifunctional Lewis/Brønted acid catalyst, being efficient in the isomerization/epimerization and in the dehydration. Hence, no additional Brønsted acid catalyst is required. Furfural selectivities of up to 46 % are obtained, which is comparable to catalytic systems previously reported using mineral acids. Catalyst stability studies have shown that Nb〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 has similar deactivation in water and organic solvent, furthermore, the stability can be improved further if niobium oxide is dispersed on a silica support.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118302293-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 29 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Luiz G. Possato, Elen Pereira, Rosembergue G.L. Gonçalves, Sandra H. Pulcinelli, Leandro Martins, Celso V. Santilli〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study presents an easy route to induce pore formation, increase the specific surface area, and control the crystallite size of magnesium oxides obtained using the sol-gel method with addition of Pluronic P123 surfactant. The structural characteristics of the materials were evaluated using X-ray diffraction, N〈sub〉2〈/sub〉 physisorption isotherms, mercury intrusion porosimetry, scanning electron microscopy, and CO〈sub〉2〈/sub〉 temperature programmed desorption. The catalytic properties were assessed using the Knoevenagel condensation reaction. The results showed a systematic decrease of the magnesium oxide crystallinity with increased concentration of the surfactant used in the synthesis. This was associated with increase of the magnesium oxide BET area from 2 m〈sup〉2〈/sup〉/g to over 50 m〈sup〉2〈/sup〉/g, as well as the formation of pores in the macropore region, as confirmed by microscopy images. In addition, the surface modification resulted in CO〈sub〉2〈/sub〉 chemisorption increasing from 378 μmol, for the pristine MgO sample, to 1529 μmol, for the porous sample, accompanied by an increase in the concentration of strong basic sites. The most porous sample presented the highest catalytic activity in the Knoevenagel condensation reaction.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118302463-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉