Selectivity loss of Pt/CeO2 PROX catalysts at low CO concentrations: mechanism and active site study

被引：41
作者：
Polster, Christopher S. [1 ]
Zhang, Rong [1 ]
Cyb, Michael T. [1 ]
Miller, Jeffrey T. [2 ]
Baertsch, Chelsey D. [1 ]
机构：
[1] Purdue Univ, Sch Chem Engn, W Lafayette, IN 47907 USA
[2] Argonne Natl Lab, CSE, Argonne, IL 60439 USA
来源：
JOURNAL OF CATALYSIS | 2010年 / 273卷 / 01期
关键词：
Platinum; Ceria; Pt/CeO2; PROX; Active site density; Anaerobic reaction; Anaerobic titration; CO oxidation; H-2; oxidation; Redox mechanism; CERIA-SUPPORTED CATALYSTS; PREFERENTIAL OXIDATION; CARBON-MONOXIDE; OXIDE CATALYSTS; HYDROGEN PROX; H-2; CUO-CEO2; ALUMINA; SYSTEM; EXCESS;
D O I：
10.1016/j.jcat.2010.04.017
中图分类号：
O64 [物理化学（理论化学）、化学物理学];
学科分类号：
070304 ; 081704 ;
摘要：
CO and H-2 oxidation were studied over a series of Pt/CeO2 catalysts with differing Pt loadings and dispersions. Kinetic rate analysis confirms the presence of dual Langmuir-Hinshelwood (L-H) and Mars and van Krevelen (M-vK) pathways and is used to explain the loss in CO oxidation selectivity at low CO concentrations. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) shows the strong CO coverage dependence on both CO and O-2 concentrations and explains the transition from L-H to M-vK reaction character. Redox site measurements are performed on Pt/CeO2 catalysts by anaerobic titrations under conditions where the M-vK pathway dominates the reaction rate. Similar redox site densities per interfacial Pt atom suggest that interfacial Pt-O-Ce sites are responsible for M-vK redox activity. (C) 2010 Elsevier Inc. All rights reserved.
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收藏
页码：50 / 58
页数：9
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