Water-gas shift: in situ spectroscopic studies of noble metal promoted ceria catalysts for CO removal in fuel cell reformers and mechanistic implications

Jacobs, Gary; Patterson, Patricia M.; Williams, Leann; Chenu, Emilie; Sparks, Dennis E.; Thomas, Gerald A.; Davis, Burtron H.

doi:10.1016/j.apcata.2003.11.025

Cited by 129 publications

(118 citation statements)

References 19 publications

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“…The corresponding low surface coverage of Au by CO suggests that CO adsorption may be the rate-determining step of the WGS reaction. As a matter of fact, a CO reaction order of 1 is often observed for Au-based WGS catalysts [40]. This is in contrast with Pt/CeO 2 catalysts, for which a strong carbonyl band is observed even around 500 K [30] and the CO reaction order is typically 0 [5,15].…”

Section: Ceria Oxidation State and Nature Of The Surface Speciesmentioning

confidence: 47%

Quantitative analysis of the reactivity of formate species seen by DRIFTS over a Au/Ce(La)O2 water–gas shift catalyst: First unambiguous evidence of the minority role of formates as reaction intermediates

Meunier¹,

Reid

Goguet

et al. 2007

Journal of Catalysis

177

123

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(2007). Quantitative analysis of the reactivity of formate species seen by DRIFTS over a Au/Ce(La)O2 water-gas shift catalyst: First unambiguous evidence of the minority role of formates as reaction intermediates. Journal of Catalysis, 247(2)(2), 277-287. DOI: 10.1016DOI: 10. /j.jcat.2007 Published in: Journal of Catalysis Queen's University Belfast -Research Portal: Link to publication record in Queen's University Belfast Research Portal General rights Copyright for the publications made accessible via the Queen's University Belfast Research Portal is retained by the author(s) and / or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights. AbstractThe reactivity of the species formed at the surface of a Au/Ce(La)O 2 catalyst during the water-gas shift (WGS) reaction were investigated by operando diffuse reflectance Fourier transform spectroscopy (DRIFTS) at the chemical steady state during isotopic transient kinetic analyses (SSITKA). The exchanges of the reaction product CO 2 and of formate and carbonate surface species were followed during an isotopic exchange of the reactant CO using a DRIFTS cell as a single reactor. The DRIFTS cell was a modified commercial cell that yielded identical reaction rates to that measured over a quartz plug-flow reactor. The DRIFTS signal was used to quantify the relative concentrations of the surface species and CO 2 . The analysis of the formate exchange curves between 428 and 493 K showed that at least two levels of reactivity were present. "Slow formates" displayed an exchange rate constant 10-to 20-fold slower than that of the reaction product CO 2 . "Fast formates" were exchanged on a time scale similar to that of CO 2 . Multiple nonreactive readsorption of CO 2 took place, accounting for the kinetics of the exchange of CO 2 (g) and making it impossible to determine the number of active sites through the SSITKA technique. The concentration (in mol g −1 ) of formates on the catalyst was determined through a calibration curve and allowed calculation of the specific rate of formate decomposition. The rate of CO 2 formation was more than an order of magnitude higher than the rate of decomposition of formates (slow + fast species), indicating that all of the formates detected by DRIFTS could not be the main reaction intermediates in the production of CO 2 . This work stresses the importance of full quantitative analyses (measuring both rate constants and adsorbate concentrations) when investigating the role of adsorbates as potential reaction intermediates, and illustrates how even reactive species seen by DRIFTS may be unimportant in the overall reaction scheme.

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Section: Ceria Oxidation State and Nature Of The Surface Speciesmentioning

confidence: 47%

Quantitative analysis of the reactivity of formate species seen by DRIFTS over a Au/Ce(La)O2 water–gas shift catalyst: First unambiguous evidence of the minority role of formates as reaction intermediates

Meunier¹,

Reid

Goguet

et al. 2007

Journal of Catalysis

177

123

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“…formates could be intermediates in other circumstances such as WGS conditions, under which large concentrations of water prevail [20]). The determination of the true intermediates (e.g.…”

Section: Resultsmentioning

confidence: 99%

“…Various reaction mechanisms have been proposed regarding this reaction, some of which involved surface formate and/or carbonate species [16][17][18][19][20]. However, the conclusions of many of the IR studies were partly based on the observation of the surface species typically obtained under WGS reaction conditions and the decomposition/reactivity of these species in vacuum or atypical feed gases.…”

Section: Introductionmentioning

confidence: 99%

DRIFTS-MS-SSITKA Study of the Reverse Water-Gas Shift Reaction

Meunier¹,

Tibiletti²,

Goguet³

et al. 2006

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Étude de la réaction retour du gaz à l'eau par DRIFT-MS-SSITKA -Une méthode operando pour l'étude des mécanismes de réaction en catalyse hétérogène a été développée par l'utilisation du réacteur de la cellule infra rouge en mode de réflexion diffuse et une méthode échange isotopique à l'état stationnaire (SSITKA). Cette méthode permet l'étude simultanée de l'échange isotopique des espèces adsorbées en surface (par DRIFTS) et celle du produit de la réaction (par spectrométrie de masse). Cet article décrit nos premiers travaux en ce domaine concernant la réaction en retour du gaz à l'eau (WGS, CO 2 + H 2 → CO + H 2 O), en soulignant le besoin d'utiliser des méthodes stationnaires pour que la réactivité réelle des espèces de surface puisse être déterminée. Abstract -DRIFTS-MS-SSITKA Study of the Reverse Water-Gas Shift Reaction

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“…Formate (HCOO) as additional reactive surface intermediate has been discussed in the literature [72][73][74]; it is bonded to the surface through its oxygen atom. Carboxyl and formate intermediates are isomers and both have been detected experimentally over different transition metals [73,[75][76][77][78][79]. Tibiletti et al [78] identified formate, carbonate and carboxyl species at the surface of a Pt/CeO2 catalyst during the forward water-gas shift (WGS) and the reverse reaction (RWGS).…”

Section: Cooh On Ni Surfacementioning

confidence: 99%

Surface Reaction Kinetics of Steam- and CO2-Reforming as Well as Oxidation of Methane over Nickel-Based Catalysts

et al. 2015

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An experimental and kinetic modeling study on the Ni-catalyzed conversion of methane under oxidative and reforming conditions is presented. The numerical model is based on a surface reaction mechanism consisting of 52 elementary-step like reactions with 14 surface and six gas-phase species. Reactions for the conversion of methane with oxygen, steam, and CO2 as well as methanation, water-gas shift reaction and carbon formation via Boudouard reaction are included. The mechanism is implemented in a one-dimensional flow field description of a fixed bed reactor. The model is evaluated by comparison of numerical simulations with data derived from isothermal experiments in a flow reactor over a powdered nickel-based catalyst using varying inlet gas compositions and operating temperatures. Furthermore, the influence of hydrogen and water as co-feed on methane dry reforming with CO2 is also investigated.

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Water-gas shift: in situ spectroscopic studies of noble metal promoted ceria catalysts for CO removal in fuel cell reformers and mechanistic implications

Cited by 129 publications

References 19 publications

Quantitative analysis of the reactivity of formate species seen by DRIFTS over a Au/Ce(La)O2 water–gas shift catalyst: First unambiguous evidence of the minority role of formates as reaction intermediates

Quantitative analysis of the reactivity of formate species seen by DRIFTS over a Au/Ce(La)O2 water–gas shift catalyst: First unambiguous evidence of the minority role of formates as reaction intermediates

DRIFTS-MS-SSITKA Study of the Reverse Water-Gas Shift Reaction

Surface Reaction Kinetics of Steam- and CO2-Reforming as Well as Oxidation of Methane over Nickel-Based Catalysts

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