Kinetics of the water–gas shift reaction over nanostructured copper–ceria catalysts

Kušar, Henrik; Hočevar, Stanko; Levec, Janez

doi:10.1016/j.apcatb.2005.09.019

Cited by 71 publications

(36 citation statements)

References 20 publications

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“…Thus, the behavior of intermediates formed on transition metal surfaces upon H 2 /CO 2 exposure and under reaction conditions is of high interest. Substantial previous research has investigated these issues with copper, the basis of commercial Cu/ZnO methanol synthesis catalysts [5][6][7][8][9][10]. This work has included microkinetic modeling of the kinetics in order to aid in identifying the optimum catalysis conditions.…”

Section: Introductionmentioning

confidence: 99%

Isotope Effects in Methanol Synthesis and the Reactivity of Copper Formates on a Cu/SiO2 Catalyst

et al. 2008

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Here we investigate isotope effects on the catalytic methanol synthesis reaction and the reactivity of copper-bound formate species in CO 2 -H 2 atmospheres on Cu/SiO 2 catalysts by simultaneous IR and MS measurements, both steady-state and transient. Studies of isotopic variants (H/D, 12 C/ 13 C) reveal that bidentate formate dominates the copper surface at steady state. The steadystate formate coverages of HCOO (in 6 bar 3:1 H 2 :CO 2 ) and DCOO (in D 2 :CO 2 ) are similar and the steady-state formate coverages in both systems decrease by *80% from 350 K to 550 K. Over the temperature range 413 K-553 K, the steady-state methanol synthesis rate shows a weak H/D isotope effect (1.05 ± 0.05) with somewhat higher activation energies in H 2 :CO 2 (79 kJ/mole) than D 2 :CO 2 (71 kJ/mole) over the range 473 K-553 K. The reverse water gas shift (RWGS) rates are higher than methanol synthesis and also shows a weak positive H/D isotope effect with higher activation energy for H 2 /CO 2 than D 2 /CO 2 (108 vs. and 102 kJ/mole) The reactivity of the resulting formate species in 6 bar H 2 , 6 bar D 2 and 6 bar Ar is strongly dominated by decomposition back to CO 2 and H 2 . H 2 and D 2 exposure compared to Ar do not enhance the formate decomposition rate. The decomposition profiles on the supported catalyst deviate from first order decay, indicating distributed surface reactivity. The average decomposition rates are similar to values previously reported on single crystals. The average activation energies for formate decomposition are 90 ± 17 kJ/mole for HCOO and 119 ± 11 kJ/mole for DCOO. By contrast to the catalytic reaction rates, the formate decomposition rate shows a strong H/D kinetic isotope effect (H/D *8 at 413 K), similar to previously observed values on Cu(110).

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Section: Introductionmentioning

confidence: 99%

Isotope Effects in Methanol Synthesis and the Reactivity of Copper Formates on a Cu/SiO2 Catalyst

et al. 2008

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“…Tanaka et al (2003) found CuMn 2 O 4 and CuAl 2 O 4 mixed oxide catalyst having conversion of CO more than the commercial catalyst. Henrik Kusar et al (2006) have found the copper ceria catalyst to be non-pyrophoric and stable. Studies on Mn promoted Cu/Al 2 O 3 by Dinesh et al (2006) showed that with 8.55 wt% of Mn, 513 K and space time of 5.33 hour, CO conversion of 90% could be achieved.…”

Section: Low Temperature Shift Catalystsmentioning

confidence: 99%

“…The use of the commercial copper based catalysts, due to kinetic limitations will occupy more volume. Moreover the Cu catalyst is pyrophoric in reduced state and gets deactivated in the presence of condensed water due to leaching of active component or formation of surface carbonates [Henrik Kusar et al(2006), Wheeler et al(2004), Mhadeshwar and Vlachos (2005)]. The catalysts should also be capable of withstanding thermal cycling and faster response during startup and shutdown.…”

Section: Noble Metal Catalystsmentioning

confidence: 99%

A Review of the Water Gas Shift Reaction Kinetics

J¹,

Loganathan²,

Shantha³

2010

International Journal of Chemical Reactor Engineering

194

154

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The world's progression towards the Hydrogen economy is facilitating the production of hydrogen from various resources. In the carbon based hydrogen production, Water gas shift reaction is the intermediate step used for hydrogen enrichment and CO reduction in the synthesis gas. This paper makes a critical review of the developments in the modeling approaches of the reaction for use in designing and simulating the water gas shift reactor. Considering the fact that the rate of the reaction is dependent on various parameters including the composition of the catalyst, the active surface and structure of the catalyst, the size of the catalyst, age of the catalyst, its operating temperature and pressure and the composition of the gases, it is difficult to narrow down the expression for the shift reaction. With different authors conducting experiments still to validate the kinetic expressions for the shift reaction, continuous research on different composition and new catalysts are also reported periodically. Moreover the commercial catalyst manufacturers seldom provide information on the catalyst. This makes the task of designers difficult to model the shift reaction. This review provides a consolidated listing of the various important kinetic expressions published for both the high temperature and the low temperature water gas shift reaction along with the details of the catalysts and the operating conditions at which they have been validated.

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“…[82] However, these properties are very dependent on the synthesis method and mixed oxide compositions, which influence the chemical and electronic interactions between both oxides. [83] Other promising catalysts for WGS MR applications are the Pt-based catalysts, which generally reveal a lower inhibition effect by the forward WGS reaction products over a wide temperature range, i.e.…”

Section: Selection Of Wgs Catalysts For Membrane Reactor Applicationsmentioning

confidence: 99%

The water‐gas shift reaction: from conventional catalytic systems to Pd‐based membrane reactors—a review

Mendes

Madeira

et al. 2009

Asia-Pacific J Chem Eng

201

109

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The water-gas shift (WGS) reaction is a well-known step for upgrading carbon monoxide to hydrogen in the production of synthesis gas. For more than 90 years after its first industrial application, many issues in respect of the catalyst, process configuration, reactor design, reaction mechanisms and kinetics have been investigated. More recently, a renewed interest in the WGS reaction carried out in hydrogen perm-selective membrane reactors (MRs) has been observed because of the growing use of polymeric electrolyte membrane (PEM) fuel cells that operate using high-purity hydrogen. Moreover, MRs are viewed as an interesting technology in order to overcome the equilibrium conversion limitations in traditional reactors.This article reviews the most relevant topics of WGS MR technology -catalysis and membrane science. The most used catalysts and relevant progress achieved so far are described and critically reviewed. The effects of the most important parameters affecting the WGS in MRs are detailed. In addition, an overview on the most used membranes in MRs is also presented and discussed. 

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Kinetics of the water–gas shift reaction over nanostructured copper–ceria catalysts

Cited by 71 publications

References 20 publications

Isotope Effects in Methanol Synthesis and the Reactivity of Copper Formates on a Cu/SiO2 Catalyst

Isotope Effects in Methanol Synthesis and the Reactivity of Copper Formates on a Cu/SiO2 Catalyst

A Review of the Water Gas Shift Reaction Kinetics

The water‐gas shift reaction: from conventional catalytic systems to Pd‐based membrane reactors—a review

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