ALBERT

Beschreibung: 〈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〉

Beschreibung: 〈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〉

Beschreibung: 〈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〉

Beschreibung: 〈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〉

Beschreibung: 〈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〉

Beschreibung: 〈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〉

Beschreibung: 〈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〉

Beschreibung: 〈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〉

Beschreibung: 〈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〉

Beschreibung: 〈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〉