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  • Artikel  (41)
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  • Wiley  (41)
  • Institute for Advanced Sustainability Studies (IASS)
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  • Chemical Engineering and Technology  (12)
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  • 1
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    Performance evaluation of two high shear impellers in an unbaffled stirred tank (2015)
    Wiley
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    Publikationsdatum: 2015-06-20
    Beschreibung: High shear impellers (HSIs) are mixers used in industrial stirred tanks to incorporate powders into liquid and break down particle agglomerates. In this work, a detail numerical study of two commercial ring-style HSIs of laboratory scale (Hockmeyer® Equipment Corp. D-Blade of two and four rings) was carried out at 50≤ Re ≤75, and their performance was compared with the Rushton Turbine (RT). It was found that power and pumping numbers or their ratio, cannot be simply connected for selecting properly an impeller in applications where highly localized viscous dissipation is desirable. The ratio of the average viscous dissipation in the impeller swept volume, , to the mean in the entire volume, , at two constant values of power input, P , was found to be lower for HSIs to that evaluated for RT. However, when P increases from 4.25 to 12.92 W , the dimensionless average viscous dissipation in the blade swept volume, at the higher P was found to be similar for the HSI of two rings and the RT, corroborating the high local viscous dissipation of this HSI when operated at higher speeds.
    Print ISSN: 0930-7516
    Digitale ISSN: 1521-4125
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Publiziert von Wiley
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  • 2
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    Performance Evaluation of Two High-Shear Impellers in an Unbaffled Stirred Tank (2015)
    Wiley
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    Publikationsdatum: 2015-08-06
    Print ISSN: 0930-7516
    Digitale ISSN: 1521-4125
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Publiziert von Wiley
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  • 3
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    Catalytic Hydrogenation of Carbon Dioxide to Methane in Wall-Cooled Fixed Bed Reactors (2016)
    Wiley
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    Publikationsdatum: 2016-08-11
    Beschreibung: The methanation of CO 2 was studied in a wall-cooled single-tube fixed bed reactor with a nickel based catalyst. Heat transfer and kinetic parameters were experimentally determined. Temperature profiles were recorded at different conditions: (i) inlet gas mixtures with CO 2 diluted in H 2 or N 2 , (ii) tubes with 2 or 4 cm in diameter, and (iii) pressures of 1 or 4 bar at 160 to 200 °C. Modelling of CO 2 conversion and temperature profiles by a two-dimensional reactor model was successfully achieved. The study is completed by modelling technical reactors both for upgrading of biogas and for conversion of a CO 2 /H 2 feed gas free of CH 4 ; design data of reactors for a production of 450 m 3 SNG h – 1 are given.
    Print ISSN: 0930-7516
    Digitale ISSN: 1521-4125
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Publiziert von Wiley
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  • 4
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    Controllability Analysis of Process Alternatives for Biobutanol Purification (2015)
    Wiley
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    Publikationsdatum: 2015-06-26
    Beschreibung: Biobutanol has characteristics similar to petroleum fuel and is considered as a superior biofuel compared to ethanol. The development of technologies for biobutanol production by fermentation has resulted in higher final biobutanol concentrations together with less energy intensive separation and purification techniques. These new technological developments have the potential to provide a production process for biobutanol that is economically viable in comparison to the petrochemical pathway for its production. In this work, we analyze the control properties of four different possible process designs for the purification of biobutanol. Our results, using singular value decomposition technique, indicated that the scheme where only biobutanol flow is purified, and both ethanol and acetone leaving the purification process mixed with water and biobutanol traces, showed the best control properties.
    Print ISSN: 0930-7516
    Digitale ISSN: 1521-4125
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Publiziert von Wiley
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  • 5
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    Yield Optimization in a Cycled Trickle-Bed Reactor: Ethanol Catalytic Oxidation as a Case Study (2012)
    Wiley
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    Publikationsdatum: 2012-04-15
    Beschreibung: The effect of slow ON-OFF liquid flow modulation on the yield of consecutive reactions is investigated for oxidation of aqueous ethanol solutions using a 0.5 % Pd/Al 2 O 3 commercial catalyst in a laboratory trickle-bed reactor. Experiments with modulated liquid flow rate (MLFR) were performed under the same hydrodynamic conditions (degree of wetting, liquid holdup) as experiments with constant liquid flow rate (CLFR). Thus, the impact of the duration of wet and dry cycles as well as the period can be independently investigated. Depending on cycling conditions, acetaldehyde or acetic acid production is favored with MLFR compared to CLFR. Results suggest both the opportunity and challenge of finding a way to tune the cycling parameters for producing the most appropriate product. ON-OFF liquid flow modulation in a trickle-bed reactor and its impact on the yield of ethanol oxidation in presence of a Pd/Al 2 O 3 catalyst is studied. High cycling frequencies benefit the yield toward the intermediate product, while intermediate frequencies significantly increase the final product yield. As demonstrated, product distribution can be considerably modified through frequency tuning.
    Print ISSN: 0930-7516
    Digitale ISSN: 1521-4125
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Publiziert von Wiley
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  • 6
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    Microbial kinetics and enzymatic activities in hybrid moving bed biofilm reactor-membrane bioreactor systems (2016)
    Wiley
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    Publikationsdatum: 2016-02-23
    Beschreibung: A membrane bioreactor (MBR), a hybrid moving bed biofilm reactor-membrane bioreactor (hybrid MBBR-MBR a ) containing carriers in the anoxic and aerobic compartments and a hybrid MBBR-MBR b containing carriers only in the aerobic zone were used in parallel and compared for treating municipal wastewater. The hydraulic retention time was 18 h. The microbial kinetics and the evolution of the enzymatic activities of α-glucosidase and acid and alkaline phosphatase as well as the bacterial diversity and bacterial community structure were studied to explain the removal of organic matter and nutrients. The MBR and the hybrid MBBR-MBR b showed the highest reduction percentages of chemical oxygen demand. Moreover, the hybrid MBBR-MBR b had the highest removal performance of total nitrogen.
    Print ISSN: 0930-7516
    Digitale ISSN: 1521-4125
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Publiziert von Wiley
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  • 7
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    New Insights into Acrylic Polymer Precipitation by Supercritical Fluids (2013)
    Wiley
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    Publikationsdatum: 2013-12-07
    Beschreibung: Nanosystems based on polymers have attracted much attention due to the almost infinite diversity. In the past decades, the application of supercritical fluids for polymeric particle precipitation has been developed as an alternative to conventional processes. Here, precipitation of an acrylic copolymer was attempted by the rapid expansion of supercritical solutions (RESS) and successful by supercritical antisolvent (SAS) processes. In addition, the nanoparticles were characterized with different techniques. The polymer concentration, pressure, temperature, liquid solution flow rate and nozzle diameter effects were also evaluated with regard to particle size and the particle size distribution of this polymer. An acrylic copolymer used for drug delivery to the intestines was processed by supercritical CO 2 to improve its final features. The effects of the operating conditions were evaluated regarding morphology, particle size and particle size distribution, in order to optimize the nanoparticle production.
    Print ISSN: 0930-7516
    Digitale ISSN: 1521-4125
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Publiziert von Wiley
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
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    Yield Optimization in a Cycled Trickle-Bed Reactor: Ethanol Catalytic Oxidation as a Case Study (2012)
    Wiley
    Details
    Publikationsdatum: 2012-03-31
    Beschreibung: The effect of slow ON-OFF liquid flow modulation on the yield of consecutive reactions is investigated for oxidation of aqueous ethanol solutions using a 0.5 % Pd/Al 2 O 3 commercial catalyst in a laboratory trickle-bed reactor. Experiments with modulated liquid flow rate (MLFR) were performed under the same hydrodynamic conditions (degree of wetting, liquid holdup) as experiments with constant liquid flow rate (CLFR). Thus, the impact of the duration of wet and dry cycles as well as the period can be independently investigated. Depending on cycling conditions, acetaldehyde or acetic acid production is favored with MLFR compared to CLFR. Results suggest both the opportunity and challenge of finding a way to tune the cycling parameters for producing the most appropriate product. ON-OFF liquid flow modulation in a trickle-bed reactor and its impact on the yield of ethanol oxidation in presence of a Pd/Al 2 O 3 catalyst is studied. High cycling frequencies benefit the yield toward the intermediate product, while intermediate frequencies significantly increase the final product yield. As demonstrated, product distribution can be considerably modified through frequency tuning.
    Print ISSN: 0930-7516
    Digitale ISSN: 1521-4125
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Publiziert von Wiley
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
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    Chiral Resolution of Racemic Cyclopropanecarboxylic Acids in Supercritical Carbon Dioxide (2014)
    Wiley
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    Publikationsdatum: 2014-10-09
    Beschreibung: The chiral resolution of two racemic cyclopropanecarboxylic acids with the resolving agents ( S )-2-( N -benzylamino)butan-1-ol and ( R )-1-phenylethanamine was investigated. The resolutions were based on diastereomer salt crystallization in supercritical carbon dioxide. Unreacted compounds were removed by an extraction step. Experiments were performed in a continuously stirred tank reactor and good enantioselectivities were obtained in a single step. Pressure, temperature, and density were found to strongly affect both the optical purity and the selectivity of the resolutions. The crystal structures of the formed diastereomer salts were also studied via X-ray diffraction. The modified Pope-Peachy method, a resolution technique, is applied to realize the organic solvent-free chiral resolution of two racemic acids using supercritical CO 2 as reaction medium. A fast reaction system is presented and in vacuo and in situ methods to achieve enantiomer separation of the racemic acids are compared. Good enantioselectivities were obtained in a single step.
    Print ISSN: 0930-7516
    Digitale ISSN: 1521-4125
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Publiziert von Wiley
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  • 10
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    Absorption of CO2 with amino acids-based ionic liquids and the corresponding amino acids precursors (2017)
    Wiley
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    Publikationsdatum: 2017-08-08
    Beschreibung: A comparative study for CO 2 absorption among amino acids (AAs) and ionic liquids (ILs) containing Tetramethylammonium [TMA] and Tetrabutylphosphonium [TBP] as cations and the corresponding deprotonated amino acid as anions ([TMA][AA] and [TBP][AA]) is reported. Amino acids show an excellent performance for CO 2 capture, better than the corresponding [TMA][AA], but AAs are less efficient than [TBP][AA]. In addition [TBP][AA] present faster kinetic of absorption than the corresponding AA. [TBP][Lysinate] shows the highest CO2 absorption capacity. A novel, fast and low energy demanding method for the microwave-assisted regeneration of the absorbents from the CO 2 saturated solution is also described for the first time.
    Print ISSN: 0930-7516
    Digitale ISSN: 1521-4125
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Publiziert von Wiley
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