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Gas Shift Reaction (gas + shift_reaction)
Kinds of Gas Shift Reaction Selected AbstractsSupport-dependent activity of noble metal substituted oxide catalysts for the water gas shift reactionAICHE JOURNAL, Issue 10 2010Parag A. Deshpande Abstract The water gas shift reaction was carried out over noble metal ion substituted nanocrystalline oxide catalysts with different supports. Spectroscopic studies of the catalysts before and after the reaction showed different surface phenomena occurring over the catalysts. Reaction mechanisms were proposed based upon the surface processes and intermediates formed. The dual site mechanism utilizing the oxide ion vacancies for water dissociation and metal ions for CO adsorption was proposed to describe the kinetics of the reaction over the reducible oxides like CeO2. A mechanism based on the interaction of adsorbed CO and the hydroxyl group was proposed for the reaction over ZrO2. A hybrid mechanism based on oxide ion vacancies and surface hydroxyl groups was proposed for the reaction over TiO2. The deactivation of the catalysts was also found to be support dependent. Kinetic models for both activation and deactivation were proposed. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Ceria in catalysis: From automotive applications to the water,gas shift reactionAICHE JOURNAL, Issue 5 2010Raymond J. Gorte Abstract Ceria is a crucial component of automotive catalysts, where its ability to be reduced and re-oxidized provides oxygen storage capacity. Because of these redox properties, ceria can greatly enhance catalytic activities for a number of important reactions when it is used as a support for transition metals. For reactions that use steam as an oxidant (e.g., the water,gas-shift reaction and steam reforming of hydrocarbons), rates for ceria-supported metals can be several orders of magnitude higher than that for ceria or the transition metal alone. Because the redox properties of ceria are strongly dependent on treatment history and the presence of additives, there are significant opportunities for modifying catalysts based on ceria to further improve their performance. This article will review some of the contributions from my laboratory on understanding and using ceria in these applications. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Theoretical study of a membrane reactor for the water gas shift reaction under nonisothermal conditionsAICHE JOURNAL, Issue 12 2009Marķa E. Adrover Abstract A simulation of a membrane reactor for the water gas shift reaction is carried out by means of a 1D pseudo-homogeneous nonisothermal mathematical model. The composite membrane consists of a dense layer of Pd (selective to H2) supported over a porous ceramic layer. The effect of temperature, overall heat-transfer coefficient, and mode of operation on the membrane reactor performance and stability are analyzed, and the results obtained are compared with those corresponding to a reactor with no hydrogen permeation. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] High-temperature kinetics of the homogeneous reverse water,gas shift reactionAICHE JOURNAL, Issue 5 2004F. Bustamante Abstract The high-temperature rate of reaction of the homogeneous, reverse water,gas shift reaction (rWGSR) has been evaluated in quartz reactors with rapid feed preheating under both low- and high-pressure conditions. The form of the power-law rate expression was consistent with the Bradford mechanism. The Arrhenius expressions for the reaction rate constant, corresponding to the empty reactor, were in very good agreement with the low-pressure results of Graven and Long, but yielded rate constants roughly four times greater than those obtained in our packed reactor and those reported by Kochubei and Moin and by Tingey. Reactor geometry was not responsible for these differences because computational fluid dynamics simulations revealed similar residence time distributions and comparable conversions when the same kinetic expression was used to model the rWGSR in each reactor. Most likely, the empty NETL reactor and the Graven and Long reactor did not attain an invariant value of the concentration of the chain carrier (H) at low reaction times, which led to an overestimation of the rate constant. Conversions attained in an Inconel® 600 reactor operating at comparable conditions were approximately two orders of magnitude greater than those realized in the quartz reactor. This dramatic increase in conversion suggests that the Inconel® 600 surfaces, which were depleted of nickel during the reaction, catalyzed the rWGSR. © 2004 American Institute of Chemical Engineers AIChE J, 50: 1028,1041, 2004 [source] Membrane reactor modelling, validation and simulation for the WGS reaction using metal doped silica membranesASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010S. Battersby Abstract In this work, a Matlab Simulink© model was developed to analyse and predict the performance of a metal doped silica membrane reactor for H2 production via both the high and low temperature water gas shift reaction. An activated transport model for mixed gas separation with combined reaction was developed to model the effects within a membrane reactor unit. The membrane reactor was modelled as a number of perfectly mixed compartments containing a catalyst bed and a gas selective membrane. The combined model provided a good fit to experimentally measured results for higher conversions up to equilibrium, which is generally the case for industrial applications. Simulation results showed that H2 separation and H2 recovery improved with pressure, due to the H2 concentration driving force across the membrane. For a single stage membrane reactor unit, a maximum conversion of 93% could be achieved with a H2 recovery rate of 95%. In addition, the membrane reactor efficiency increased at higher temperatures and lower H2O:CO feed ratios, allowing for CO conversion improvements by the membrane reactor. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Water gas shift reaction via Pd-based membranesASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009Silvano Tosti Abstract The water gas shift reaction has been studied in tubular Pd-based membranes: a thin walled dense tube and a composite Pd-ceramic tube have been considered. A computer code based on a finite element model has been developed for modelling the membrane reactor. The model accounts for the reaction kinetic, the hydrogen diffusion through the porous ceramic support and permeation through the PdAg membrane and for the partial pressure gradients of hydrogen generated at the permeate side of the membrane when a flow of purge gas is introduced. The code has been used to assess the influence of temperature, lumen pressure, presence of wall effects and sweep gas mode on the reaction conversion and hydrogen yield of the membrane reactors. At 200 kPa of lumen pressure and counter-current sweep mode, it was found that both reaction conversion and hydrogen yield increase with temperature: the dense and the composite membranes exhibit very close values of conversion (more than 99% at 400 °C) and hydrogen yield (96,97% at 400 °C). In co-current mode, the highest values of both reaction conversion and hydrogen yield have been assessed at 350 °C, while it was demonstrated that the beneficial effects of increasing the lumen pressure up to 400 kPa are maximum at 300 °C. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Autothermal Catalytic Partial Oxidation of Glycerol to Syngas and to Non-Equilibrium ProductsCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 1 2009David Abstract Glycerol, a commodity by-product of the biodiesel industry, has value as a fuel feedstock and chemical intermediate. It is also a simple prototype of sugars and carbohydrates. Through catalytic partial oxidation (CPOx), glycerol can be converted into syngas without the addition of process heat. We explored the CPOx of glycerol using a nebulizer to mix droplets with air at room temperature for reactive flash volatilization. Introducing this mixture over a noble-metal catalyst oxidizes the glycerol at temperatures over 600,°C in 30,90,ms. Rhodium catalysts produce equilibrium selectivity to syngas, while platinum catalysts produce mainly autothermal non-equilibrium products. The addition of water to the glycerol increases the selectivity to H2 by the water gas shift reaction and reduces non-equilibrium products. However, water also quenches the reaction, resulting in a maximum in H2 production at a steam/carbon ratio of 2:3 over a Rh-Ce catalyst. Glycerol without water produces a variety of chemicals over Pt, including methylglyoxal, hydroxyacetone, acetone, acrolein, acetaldehyde, and olefins. [source] | ||||||||||