Activity, stability and deactivation behavior of Au/CeO2 catalysts in the water gas shift reaction at increased reaction temperature (300°C)

El-Moemen, Ayman Abd; Karpenko, A.; Denkwitz, Y.; Behm, R. Jürgen

doi:10.1016/j.jpowsour.2008.07.084

Cited by 64 publications

(47 citation statements)

References 57 publications

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“…The catalyst was prepared by a deposition-precipitation procedure described elsewhere [12]. EXAFS/XANES data were recorded before and after the pre-treatment as well as during reaction at the Au L 3 -edge (11919 eV) in the fluorescence mode, using a Si drift diode detector (KETEK GmbH).…”

Section: Methodsmentioning

confidence: 99%

Geometric and electronic structure of Au on Au/CeO₂catalysts during the CO oxidation: Deactivation by reaction induced particle growth

Abdel‐Mageed

Kučerová

El-Moemen

et al. 2016

J. Phys.: Conf. Ser.

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Abstract. Changes of the geometric and electronic structure of gold on Au/CeO 2 catalysts induced by different pre-treatments (oxidative and reductive) and by the CO oxidation reaction at 80°C were followed by operando XANES / EXAFS measurements. The results showed that i) oxidative pre-treatment (O 2 ) leads to larger Au nanoparticles than reductive pre-treatment (CO), that ii) Au is predominantly metallic during CO oxidation, irrespective of the preceding pre-treatment, and that iii) there is a reaction induced Au particle growth. Correlations with the activity of the respective catalysts and its temporal evolution give insights into the origin of deactivation of these catalysts under reaction conditions, in particular on reaction induced changes in the Au particle size.

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Section: Methodsmentioning

confidence: 99%

Geometric and electronic structure of Au on Au/CeO₂catalysts during the CO oxidation: Deactivation by reaction induced particle growth

Abdel‐Mageed

Kučerová

El-Moemen

et al. 2016

J. Phys.: Conf. Ser.

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“…[11][12][13][14][15][16][17][18][19][20][21] Despite their high activity, under reaction conditions, these materials may often undergo significant deactivation problems [5,8,9,12,15,[17][18][19]21] . This is a major, very challenging, issue, which is actually limiting their practical applications.…”

Section: Introductionmentioning

confidence: 99%

Contributions of Electron Microscopy to Understanding CO Adsorption on Powder Au/Ceria–Zirconia Catalysts

Cíes

Delgado

López‐Haro

et al. 2010

Chemistry A European J

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The influence of the highly dispersed gold phase on the CO-support interaction occurring in two 2.5 wt % Au/Ce(0.62)Zr(0.38)O(2) catalysts with medium (Au/CZ-MD) and high (Au/CZ-HD) metal dispersion is quantitatively assessed. For this purpose, we have followed an approach in which high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), computer modelling, volumetric adsorption and FTIR spectroscopy studies are combined. This approach has already been fruitfully applied to the investigation of the specific CO-metal adsorption in Au/ceria-zirconia catalysts. As deduced from the experimental studies reported herein, the presence of gold dramatically increases the amount of CO strongly chemisorbed on the support. Moreover, this amount is sensitive to the metal dispersion, thus suggesting the occurrence of a mechanism in which the CO molecules that are initially adsorbed on the gold nanoparticles are further transferred to the support by means of a spillover process. An annular model is proposed for the growth of the CO phase adsorbed on the ceria-zirconia mixed oxide in the presence of Au. By assuming this model, we have estimated the width of the annulus, Delta r, of the adsorbed CO grown around the Au nanoparticles in Au/CZ-MD and Au/CZ-HD catalysts. This value is found to be very close to Delta r approximately 2 nm in both cases, the coincidence lending some additional support to the model. To further confirm this proposal, we have investigated the influence of CO pre-adsorption on the D(2)-Au/CZ-MD interaction, at 298 K. As revealed by FTIR spectroscopy, the kinetics of the deuterium spillover is significantly disturbed by the pre-adsorbed CO, which is fully consistent with an annular model for the CO adsorption. We conclude from the global analysis of the results reported here and those already available on CO-Au adsorption that the appropriate combination of nanostructural, computer modelling and chemical techniques is a powerful tool allowing us to gain a comprehensive picture of the complex series of processes involved in the CO adsorption on this relevant family of gold catalysts.

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“…27 The formation of surface carbonates resulting in the loss of activity has been well reported. [62][63][64][65][66][67][68] In the reducible oxides, the formation of carbonates limits the rate at which ceria gets reoxidized. 65 This becomes especially relevant following Eqs.…”

Section: Modeling the Catalyst Deactivationmentioning

confidence: 99%

Support‐dependent activity of noble metal substituted oxide catalysts for the water gas shift reaction

Deshpande

Madras

2010

AIChE Journal

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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 CeO 2 . A mechanism based on the interaction of adsorbed CO and the hydroxyl group was proposed for the reaction over ZrO 2 . A hybrid mechanism based on oxide ion vacancies and surface hydroxyl groups was proposed for the reaction over TiO 2 . The deactivation of the catalysts was also found to be support dependent. Kinetic models for both activation and deactivation were proposed.

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Activity, stability and deactivation behavior of Au/CeO2 catalysts in the water gas shift reaction at increased reaction temperature (300°C)

Cited by 64 publications

References 57 publications

Geometric and electronic structure of Au on Au/CeO₂catalysts during the CO oxidation: Deactivation by reaction induced particle growth

Geometric and electronic structure of Au on Au/CeO₂catalysts during the CO oxidation: Deactivation by reaction induced particle growth

Contributions of Electron Microscopy to Understanding CO Adsorption on Powder Au/Ceria–Zirconia Catalysts

Support‐dependent activity of noble metal substituted oxide catalysts for the water gas shift reaction

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Activity, stability and deactivation behavior of Au/CeO2 catalysts in the water gas shift reaction at increased reaction temperature (300°C)

Cited by 64 publications

References 57 publications

Geometric and electronic structure of Au on Au/CeO2catalysts during the CO oxidation: Deactivation by reaction induced particle growth

Geometric and electronic structure of Au on Au/CeO2catalysts during the CO oxidation: Deactivation by reaction induced particle growth

Contributions of Electron Microscopy to Understanding CO Adsorption on Powder Au/Ceria–Zirconia Catalysts

Support‐dependent activity of noble metal substituted oxide catalysts for the water gas shift reaction

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Geometric and electronic structure of Au on Au/CeO₂catalysts during the CO oxidation: Deactivation by reaction induced particle growth

Geometric and electronic structure of Au on Au/CeO₂catalysts during the CO oxidation: Deactivation by reaction induced particle growth