Preferential CO oxidation in hydrogen (PROX) on ceria-supported catalysts, part II: Oxidation states and surface species on Pd/CeO2 under reaction conditions, suggested reaction mechanism

Pozdnyakova, Olga; Teschner, Detre; Wootsch, Attila; Kröhnert, Jutta; Steinhauer, Bernd; Sauer, Hervé; Tóth, Lajos; Jentoft, Friederike C.; Knop‐Gericke, Axel; Paál, Z.; Schlögl, Robert

doi:10.1016/j.jcat.2005.10.015

Cited by 205 publications

(55 citation statements)

References 47 publications

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“…Noble metal catalysts, including Pt, Ru, Rh, Pd and Au, have shown high activities and good stabilities for the PROX of CO [4][5][6][7][8][9]. However, noble metal catalysts inevitably have disadvantages of high cost and limited availability.…”

Section: Introductionmentioning

confidence: 99%

Cobalt and Copper Composite Oxides as Efficient Catalysts for Preferential Oxidation of CO in H2-Rich Stream

Liu

Zhang

et al. 2008

Catal Lett

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A series of Co-Cu composite oxides with different Co/Cu atomic ratios were prepared by a co-precipitation method. XRD, N 2 sorption, TEM, XPS, H 2 -TPR, CO-TPR, CO-TPD and O 2 -TPD were used to characterize the structure and redox properties of the composite oxides. Only spinel structure of Co 3 O 4 phase was confirmed for the Co-Cu composite oxides with Co/Cu ratios of 4/1 and 2/1, but the particle sizes of these composite oxides decreased evidently compared with Co 3 O 4 . These composite oxides could be reduced at lower temperatures than Co 3 O 4 by either H 2 or CO. CO and O 2 adsorption amounts over the composite oxides were significantly higher than those over Co 3 O 4 . These results indicated a strong interaction between cobalt and copper species in the composite samples, possibly suggesting the formation of Cu x Co 3-x O 4 solid solution. For the preferential oxidation of CO in a H 2 -rich stream, the Co-Cu composite oxides (Co/Cu = 4/1-1/1) showed distinctly higher catalytic activities than both Co 3 O 4 and CuO, and the formation of Cu x Co 3-x O 4 solid solution was proposed to contribute to the high catalytic activity of the composite catalysts. The Co-Cu composite oxide was found to exhibit higher catalytic activity than several other Co 3 O 4 -based binary oxides including Co-Ce, Co-Ni, Co-Fe and Co-Zn oxides.

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Section: Introductionmentioning

confidence: 99%

Cobalt and Copper Composite Oxides as Efficient Catalysts for Preferential Oxidation of CO in H2-Rich Stream

Liu

Zhang

et al. 2008

Catal Lett

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“…According to the literature they are bicarbonates, bidentate carbonates, monodentate carbonates and bridged carbonates 35,[65][66][67][68]. Due to the complexity of the fine structures of the carbonates in this region, exact identification was questionable and the frequencies varied widely, as re-…”

mentioning

confidence: 99%

Mechanistic Insights into CO₂ Methanation over Ru-Substituted CeO₂

et al. 2016

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CO 2 methanation is an important probe reaction to understand CO 2 interactions with catalytic surfaces. Importance of this reaction is further increased by its association with CO 2 utilization. This study reports mechanistic aspects of CO 2 methanation over combustion synthesized Ru-substituted CeO 2 catalyst. Temperature programmed reaction experiments were carried out to understand the interaction of CO 2 , H 2 and their stoichiometric mixture with the catalyst surface. In situ FTIR spectroscopy was used to identify the intermediates of the reaction. It was observed that CO 2 adsorption took place on the surface of Ce 0.95 Ru 0.05 O 2 and the formation of surface carbonate intermediates took place only when H 2 was present in the gas phase. In absence of H 2 , CO 2 did not show any indication for chemisorption. This behavior was explained in terms of the reaction between CO 2 and the surface hydroxyls leading to formation of vacancy. Upon dissociation, carbonates led to chemisorbed CO which eventually formed methane upon reaction with gas phase H 2 . The exact identity of carbonate species and the pathway for methanation step were ambiguous following purely experimental studies. Density functional theory calculations were carried out to augment the experimental observations. Complete energy landscapes developed on the basis of differentiation of oxidized and reduced forms of the catalyst showed that the reaction followed a pathway consisting of surface carbonate species formed by the interaction of oxide surface and chemisorbed CO, and a sequential methanation via the surface methoxy species formation. The study provides physical insights into the role of oxidation state of the catalyst and the surface anionic vacancies in governing the reaction pathway.2

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“…4 (b)). There is a rapid decrease in the CO 2 selectivity over Cu/CeO 2 -TD at 125 C. Hydrogen oxidation occurs under a high excess of oxygen and at a high reaction temperature [32]. Therefore, the selectivity toward CO 2 decreases continuously with an increase in the reaction temperature.…”

Section: Catalytic Activity For Co-proxmentioning

confidence: 99%

Copper catalysts prepared via microwave-heated polyol process for preferential oxidation of CO in H2-rich streams

Chuang

Shih

et al. 2013

International Journal of Hydrogen Energy

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Preferential CO oxidation in hydrogen (PROX) on ceria-supported catalysts, part II: Oxidation states and surface species on Pd/CeO2 under reaction conditions, suggested reaction mechanism

Cited by 205 publications

References 47 publications

Cobalt and Copper Composite Oxides as Efficient Catalysts for Preferential Oxidation of CO in H2-Rich Stream

Cobalt and Copper Composite Oxides as Efficient Catalysts for Preferential Oxidation of CO in H2-Rich Stream

Mechanistic Insights into CO₂ Methanation over Ru-Substituted CeO₂

Copper catalysts prepared via microwave-heated polyol process for preferential oxidation of CO in H2-rich streams

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Preferential CO oxidation in hydrogen (PROX) on ceria-supported catalysts, part II: Oxidation states and surface species on Pd/CeO2 under reaction conditions, suggested reaction mechanism

Cited by 205 publications

References 47 publications

Cobalt and Copper Composite Oxides as Efficient Catalysts for Preferential Oxidation of CO in H2-Rich Stream

Cobalt and Copper Composite Oxides as Efficient Catalysts for Preferential Oxidation of CO in H2-Rich Stream

Mechanistic Insights into CO2 Methanation over Ru-Substituted CeO2

Copper catalysts prepared via microwave-heated polyol process for preferential oxidation of CO in H2-rich streams

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Mechanistic Insights into CO₂ Methanation over Ru-Substituted CeO₂