Kinetics of hydrogen chemisorption on high surface area Pd/Ce0.8Zr0.2O2

[摘要] The effect of pre-reduction conditions on the H-2 chemisorption kinetics of high surface area Pd(0.53 wt.%)/Ce0.8Zr0.2O2 was investigated by means of temperature-progammed reduction, oxygen-storage capacity, IR spectroscopy and volumetric hydrogen measurements. In the 2080 degrees C range, the pre-reduction rate was very fast and dependent on temperature, with an apparent activation energy of 58 U mol(-1). Distinction between PdO reduction and H spillover processes is only possible at low H-2 pressures. The total H-2 uptake and the chemisorption rate strongly decrease by the use of high H-2 pressures during the pre-reduction process. Irreversible reduction with the concomitant oxygen vacancies formation occurs at low temperature, as demonstrated by in situ IR experiments. However, H-2 uptake on the Pd(0.53 wt.%)/Ce0.8Zr0.2O2 during pre-reduction and chemisorption is recovered by reoxidation at 400 degrees C. (c) 2005 Elsevier B.V. All rights reserved.

[发布日期] 2005-12-08

[效力级别]  Proceedings Paper

[关键词] metals;hydrogen;chemsorption;ceria based materials