CO adsorption energy on planar Au/TiO2 model catalysts under catalytically relevant conditions

被引:39
作者
Diemant, T. [1 ]
Hartmann, H. [1 ]
Bansmann, J. [1 ]
Behm, R. J. [1 ]
机构
[1] Univ Ulm, Inst Catalysis & Surface Chem, D-89069 Ulm, Germany
关键词
IR absorption-reflection spectroscopy; adsorption energy; coadsorption; model catalyst; gold; titanium oxide; carbon monoxide; oxygen;
D O I
10.1016/j.jcat.2007.09.024
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
The adsorption of CO on planar Au/TiO2 model catalysts was studied by polarization-modulation infrared reflection-absorption spectroscopy (PM-IRAS) under catalytically relevant pressure (10-50 mbar) and temperature (30-120 degrees C) conditions, both in pure CO and in CO/O-2 reaction gas mixtures. The adsorption energy of CO on the Au particles was determined by a quantitative analysis of the temperature dependence of the CO absorption intensity in adsorption isobars. The data reveal considerable effects of the An particle size when pure CO is used; the initial adsorption energy decreases from 74 kJ mol(-1) (2 nm mean Au particle diameter) to 62 kJ mol(-1) (4 nm). For CO/O-2 gas mixtures, the initial CO adsorption energy is, irrespective of the Au particle size, constant at 63 kJ mol(-1) (i.e., the CO adsorption energy is reduced for smaller An particles), but this effect vanishes for larger Au particles. (C) 2007 Elsevier Inc. All rights reserved.
引用
收藏
页码:171 / 177
页数:7
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