Reaction mechanism of preferential oxidation of carbon monoxide on Pt, Fe, and Pt–Fe/mordenite catalysts

Kotobuki, Masashi; Watanabe, Akiko; Uchida, Hiroyuki; Yamashita, Hisao; Watanabe, Masahiro

doi:10.1016/j.jcat.2005.09.026

Cited by 124 publications

(100 citation statements)

References 18 publications

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“…[1][2][3][4] For this type of catalyst, a dual-site adsorption mechanism has been proposed, where CO adsorbed on noble-metal sites reacts with oxygen activated on reducible oxide at the metal/oxide interface. 5,6 In this mechanism, however, H 2 is not involved. Actually, the H 2 in the reaction mixture has a significant impact on CO oxidation, in terms of both activity and selectivity.…”

Section: Introductionmentioning

confidence: 96%

Microkinetic Study of CO Oxidation and PROX on Ir−Fe Catalyst

Li¹,

Wang²,

Zhang³

et al. 2011

Ind. Eng. Chem. Res.

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A microkinetic analysis of the preferential oxidation of CO in H 2 over Ir-Fe/SiO 2 catalyst is reported. Based on the results of in situ diffuse reflectance infrared spectroscopy, microcalorimetry, Mössbauer spectroscopy, and steady-state kinetic experiments in a microreactor, a microkinetic model is proposed that predicts the experimental results well. The model suggests that the reaction between adsorbed H and O for the formation of OH is rate-limiting for the PROX reaction, whereas the surface reaction between adsorbed CO and O is rate-determining for CO oxidation. In addition, the model predicts that the oxidation of adsorbed CO by surface OH is the dominant pathway for the PROX reaction. The surface coverages of different intermediates are also predicted by the model. According to this model, we can conclude that the presence of H 2 increases the surface concentration of OH and, hence, lowers the activation energy and increases the rate of the PROX reaction.

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Section: Introductionmentioning

confidence: 96%

Microkinetic Study of CO Oxidation and PROX on Ir−Fe Catalyst

Li¹,

Wang²,

Zhang³

et al. 2011

Ind. Eng. Chem. Res.

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“…Catalysts proposed for CO-PROX process include noble metal-based systems, mostly Pt but also Au-supported on metal oxides [23][24][25][26][27][28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Improved CO-PROX Performance of CuO/CeO2 Catalysts by Using Nanometric Ceria as Support

2018

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Abstract:Despite of the huge number of papers about the catalytic preferential oxidation of CO (CO-PROX) for the purification of H 2 streams, there is still a need for more effective catalysts in order to reduce the large required catalyst volume of CO-PROX unity. In this work, large surface area nanometric ceria was used as support for CuO/CeO 2 catalysts with CuO load up to 10 wt % easily dispersed by wet impregnation. Catalysts were characterized by ICP-MS, XRD, SEM/EDS, N 2 physisorption, H 2 temperature programmed reduction (TPR), and CO 2 temperature programmed desorption (TPD) and tested under different reaction conditions (including under feed containing inhibiting species such as CO 2 and H 2 O). Catalytic tests revealed that our samples show high activity and selectivity even under stringent reaction conditions; moreover, they result among the most active catalysts when compared to those reported in the scientific literature. The high activity can be related to the enhanced amount of highly dispersed copper sites in strong interaction with ceria related to the nature of the nanometric support, as evidenced by the characterization techniques. Despite the high concentration of active copper sites, catalytic performance is limited by CO 2 desorption from ceria in the neighborhood of copper sites, which prevents a further improvement. This suggests that new catalyst formulations should also provide a lower affinity towards CO 2 .

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“…Therefore, the Au/Al 2 O 3 -MO x catalyst are very effective for the inhibition of the hot spot formation in CO oxidation reaction, mainly due to the low oxygen affinity of Au [12], which resulted from MOx modification. Herein, we think that there maybe a so-called bifounctional mechanism exist over the Au/Al 2 O 3 -MO x catalyst in PROX reaction, just as the Pt-Fe/Mordenite catalysts reported previously [13]. Where Au sites are available for the adsorption of CO as well as H 2 , and the FeO x site acts as an O 2 dissociative-adsoption site.…”

Section: Introductionmentioning

confidence: 67%