REVERSIBLE ACTIVITY ENHANCEMENT OF SIO2-SUPPORTED GROUP-VIII METAL-CATALYSTS BY PRETREATMENT TEMPERATURE

被引:5
作者
INUKAI, JJ [1 ]
ASAKURA, K [1 ]
IWASAWA, Y [1 ]
机构
[1] UNIV TOKYO, FAC SCI, DEPT CHEM, 7-3-1 HONGO, BUNKYO KU, TOKYO 113, JAPAN
关键词
D O I
10.1006/jcat.1993.1250
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
Reversible enhancement in activity for hydrogenation of ethene, H2-D2 equilibrium reaction, and hydrogenolysis of ethane by high-temperature evacuation was observed for Ni, Pd, Pt, Rh, and Ru catalysts. There existed a respective threshold activation temperature (670 ∼ 880 K) for each catalyst. Those catalysts were repeatedly used, and this phenomenon was reversible. Change of neither dispersion, particle size, nor particle shape by the high-temperature treatment leading to the enhancement was observed. A strong particle-size dependence of reaction rate for hydrogenation of ethene on Pd/SiO2 was observed after the catalyst had received the high-temperature treatment, while after low-temperature pretreatment, no dependence of the rate on particle size was observed. Adsorbed CO on the high-temperature treated Rh samples showed much different vibrational spectra from those for the low-temperature treated samples. The threshold enhancement temperature for each metal is related to the sublimation energies. This phenomenon is suggested to arise from roughening of the metal particle surface by the high-temperature treatment. © 1993 Academic Press, Inc.
引用
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页码:22 / 31
页数:10
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