Characteristics of gold-zeolite Y catalysts in CO oxidation and ethylene hydrogenation
AuHY zeolites have been prepared using various gold salts by ion-exchange of cationic gold entities or by adsorption/impregnation using anionic gold species. Au is initially present as Au(III) or Au(I), depending on the gold source used and the initial oxidation state is largely retained in the gold-zeolite as evidenced by M鰏sbauer effect spectroscopy performed at 6K. Ion-exchange Au(III)/HY is initially very inactive for CO oxidation, but activity develops with increasing time on stream, during which induction period, some degree of reduction of the gold is considered to take place. The induction period can be considerably shortened by applying a reductive pre-treatment using sodium borohydride or other reducing agents. CO oxidation activity can be increased in the case of Au(CN)2-derived zeolite-Y, by the co-ionexchange of transition metal ions, Cr3+, Fe3+ or Ni2+. Comparative studies of CO oxidation and ethylene hydrogenation by these various AuY zeolites strongly suggest that there are different sites requirements for the two reactions.
T. Magadzu G. R. Hearne M. S. Scurrell
Molecular Sciences Institute, School of Chemistry School of Physics, University of the Witwatersrand Johannesburg, P O WITS 2050, South Africa
国际会议
北京
英文
2007-08-12（万方平台首次上网日期，不代表论文的发表时间）