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Commercial Catalyst (commercial + catalyst)

Distribution by Scientific Domains

Chemistry	100%

Selected Abstracts

Study of the Catalytic Layer in Polybenzimidazole-based High Temperature PEMFC: Effect of Platinum Content on the Carbon Support

FUEL CELLS, Issue 2 2010
J. Lobato
Abstract In this work, the effect of platinum percentage on the carbon support of commercial catalyst for electrodes to be used in a Polybenzimidazole (PBI)-based PEMFC has been studied. Three percentages were studied (20, 40 and 60%). In all cases, the same quantity of PBI in the catalyst layer was added, which is required as a ,binder'. From Hg porosimetry analyses, pore size distribution, porosity, mean pore size and tortuosity of all electrodes were obtained. The amount of mesopores gets larger as the platinum percentage in the catalytic layer decreases, which reduces the overall porosity and the mean pore size and increases the tortuosity. The electrochemical characterisation was performed by voltamperometric studies, assessing the effective electrochemical surface area (ESA) of the electrodes, by impedance spectroscopy (IS), determining the polarisation resistance, and by the corresponding fuel cell measurements. The best results were obtained for the electrodes with a content of 40% Pt on carbon, as a result of an adequate combination of catalytic activity and mass transfer characteristics of the electrode. It has been demonstrated that the temperature favours the fuel cell performance, and the humidification does not have remarkable effects on the performance of a PBI-based polymer electrolyte membrane fuel cell (PEMFC). [source]

Investigation of multiphase hydrogenation in a catalyst-trap microreactor

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 3 2009
S. McGovern
BACKGROUND: Multiphase hydrogenation plays a critical role in the pharmaceutical industry. A significant portion of the reaction steps in a typical fine chemical synthesis are catalytic hydrogenations, generally limited by resistances to mass and heat transport. To this end, the small-scale and large surface-to-volume ratios of microreactor technology would greatly benefit chemical processing in the pharmaceutical and other industries. A silicon microreactor has been developed to investigate mass transfer in a catalytic hydrogenation reaction. The reactor design is such that solid catalyst is suspended in the reaction channel by an arrangement of catalyst traps. The design supports the use of commercial catalyst and allows control of pressure drop across the bed by engineering the packing density. RESULTS: This paper discusses the design and operation of the reactor in the context of the liquid-phase hydrogenation of o-nitroanisole to o-anisidine. A two-phase ,flow map' is generated across a range of conditions depicting three flow regimes, termed gas-dominated, liquid-dominated, and transitional, all with distinctly different mass transfer behavior. Conversion is measured across the flow map and then reconciled against the mass transfer characteristics of the prevailing flow regime. The highest conversion is achieved in the transitional flow regime, where competition between phases induces the most favorable gas,liquid mass transfer. CONCLUSION: The results are used to associate a mass transfer coefficient with each flow regime to quantify differences in performance. This reactor architecture may be useful for catalyst evaluation through rapid screening, or in large numbers as an alternative to macro-scale production reactors. Copyright © 2008 Society of Chemical Industry [source]

Effect of supercritical deposition synthesis on dibenzothiophene hydrodesulfurization over NiMo/Al2O3 nanocatalyst

AICHE JOURNAL, Issue 10 2009
Mehrdad Alibouri
Abstract The synthesis of two NiMo/Al2O3 catalysts by the supercritical carbon dioxide/methanol deposition (NiMo-SCF) and the conventional method of wet coimpregnation (NiMo-IMP) were conducted. The results of the physical and chemical characterization techniques (adsorption,desorption of nitrogen, oxygen chemisorption, XRD, TPR, TEM, and EDAX) for the NiMo-SCF and NiMo-IMP demonstrated high and uniform dispersed deposition of Ni and Mo on the Al2O3 support for the newly developed catalyst. The hydrodesulfurization (HDS) of fuel model compound, dibenzothiophene, was used in the evaluation of the NiMo-SCF catalyst vs. the commercial catalyst (NiMo-COM). Higher conversion for the NiMo-SCF catalyst was obtained. The kinetic analysis of the reaction data was carried out to calculate the reaction rate constant of the synthesized and commercial catalysts in the temperature rang of 543,603 K. Analysis of the experimental data using Arrhenius' law resulted in the calculation of frequency factor and activation energy of the HDS for the two catalysts. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

Novel nickel-based catalyst for low temperature hydrogen production from methane steam reforming in membrane reformer

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010
Yazhong Chen
Abstract Hydrogen production from various hydrocarbon fuels, particularly biomass-derived fuels, has attracted worldwide attention due to its potential for application to fuel cells, a device which converts chemical energy into electricity efficiently and cleanly. However, current technology, such as natural gas steam reforming, could not meet the specific requirements of hydrogen for fuel cells. Therefore, novel processes are intensively investigated, aiming to develop economic and efficient ones for the specific purpose. An important direction is the integrated membrane reformer for one-step high-purity hydrogen production. However, for the commercial realization of this technology, there are still some difficulties to overcome. By comparison with previous investigations with a similar membrane, this work showed that catalyst also played an important role in determining membrane reformer performance. We proposed that when thickness of membrane was several micrometers, the permeance of membrane became less important than the kinetics of catalyst, due to the fact that under such conditions, hydrogen permeation rate was faster than the kinetics of steam reforming reaction when commercial catalyst was applied, but further evidence is indispensable. In this initial work, we focused on developing efficient nickel catalyst for low temperature steam reforming. Nickel-based catalyst was developed by deposition,coprecipitation and used as pre-reduced, showing high performance for methane steam reforming at low temperatures and good durability, which may find practical application for the integrated membrane reforming process. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

Production of hydrogen via glycerol steam reforming in a Pd-Ag membrane reactor over Co-Al2O3 catalyst

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010
A. Iulianelli
Abstract Generally, biodiesel fuel, when converted from vegetables oils, produces around 10 wt% of glycerol as a byproduct, which could be used for producing hydrogen by a steam-reforming reaction. Different scientific works have been realized in conventional reactors on the steam reforming of glycerol (GSR) in the aqueous or the gas phase. High reaction pressure and a relatively small catalyst deactivation are noticed when GSR is carried out in an aqueous phase, whereas the catalyst deactivation is the main disadvantage in the gas phase. In this work, GSR reaction was performed in a perm-selective Pd-Ag membrane reactor (MR) packed with a Co-Al2O3 commercial catalyst in order to extract a CO-free hydrogen stream and also enhance the performances in terms of glycerol conversion and hydrogen yield with respect to a traditional reactor (TR), both working at weight hourly space velocity (WHSV) = 1.01 h,1, 400 °C and H2O/C3H8O3 = 6/1. In MR, a maximum glycerol conversion of around 45.0% was achieved at 1.0 bar as reaction pressure, whereas it was around 94% at 4.0 bar. Moreover, as best value, more than 60.0% of CO-free hydrogen recovery was achieved in the MR at 4.0 bar and 22.8 of sweep factor (sweep gas to glycerol ratio). Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

Effect of supercritical deposition synthesis on dibenzothiophene hydrodesulfurization over NiMo/Al2O3 nanocatalyst

Catalysts for water,gas shift processing of coal-derived syngases,

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2010
San Shwe Hla
Abstract Although the gasification of coal is an efficient means of producing syngas, the carbon content of coal is such that gasification produces significantly higher ratios of carbon oxides to hydrogen than those obtained by the steam reforming of natural gas. The CO:H2 ratio can be adjusted, and more hydrogen produced, by the subsequent application of the water,gas shift (WGS) reaction. This article presents a review of technologies associated with the catalytic WGS reaction in a fixed-bed reactor that might be incorporated into a coal gasification-based system for H2 production with CO2 capture. The main output from this review is the identification of key project areas requiring further research. The performance of existing, commercially available catalysts,designed for use in natural gas reforming processes,with coal-derived syngases is an important aspect of developing technologies for coal-based H2 production. This article presents an experimental assessment of the performance of selected commercially available WGS catalysts, two high-temperature catalysts (HT01 and HT02) and a sour shift catalyst (SS01), with such syngases. For the three commercial catalysts investigated in this study, CO reaction order is found to be in a range of 0.75,1. The effect of changes in H2O concentration over HT01 is insignificant, whereas H2O reaction orders determined using HT02 and SS01 are found to be significantly positive even at high H2O:C ratios. The CO conversion rate is significantly reduced by increasing CO2 concentration, whereas increasing H2 concentration also causes a slight reduction in CO conversion rate for the three commercial catalysts investigated. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd. [source]