SIZE EFFECTS IN ETHYLENE OXIDATION ON SILVER CATALYSTS - INFLUENCE OF SUPPORT AND CS PROMOTER

被引：93
|
作者：
GONCHAROVA, SN [1 ]
PAUKSHTIS, EA [1 ]
BALZHINIMAEV, BS [1 ]
机构：
[1] RUSSIAN ACAD SCI, BORESKOV INST CATALYSIS, SIBERIAN BRANCH, NOVOSIBIRSK 630090, RUSSIA
来源：
APPLIED CATALYSIS A-GENERAL | 1995年 / 126卷 / 01期
关键词：
ETHYLENE EPOXIDATION; ETHYLENE PI-COMPLEX; SILVER CATALYST; SILVER PARTICLE SIZE DISTRIBUTION; SIZE EFFECT;
D O I：
10.1016/0926-860X(95)00036-4
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：
A new method for preparing supported silver catalysts with a narrow particle size distribution has been developed. For crystals with a diameter ranging from 100 to 1000 Angstrom the dependencies of reaction rates on size have been studied for epoxidation and deep oxidation of ethylene. For particles 300-500 Angstrom in size the reaction rate was found to increase sharply. The concentration of ethylene pi-complexes with Ag+ cations increased proportionally to the reaction rate. These pi-complexes are assumed to be the only intermediates directing the reaction towards epoxidation. The ratio of the reaction rate to the concentration of pi-complexes was found to remain constant within a wide range of AE crystal sizes including bulk silver samples. The influence of the support (alpha-Al2O3, SiO2) on the size effect relates to the secondary processes of ethylene oxide conversion. The factors that cause the catalytic size effect and the promoting effect of Cs are discussed.
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页码：67 / 84
页数：18
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