Preparation method for supported metal catalysts using w/o microemulsion: Study on immobilization conditions of metal particles by hydrolysis of alkoxide

• Published in: Catalysis today Vol. 45; no. 1; pp. 203 - 208
• Main Authors: Kishida, Masahiro, Ichiki, Ken-ichiro, Hanaoka, Toshiaki, Nagata, Hideo, Wakabayashi, Katsuhiko
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 19.10.1998; Elsevier Science
• Subjects: Catalysis; Catalyst preparation method; Catalysts: preparations and properties; Chemistry; Exact sciences and technology; General and physical chemistry; Immobilization of nanoparticles; Microemulsion; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Microemulsion; Catalyst preparation method; Immobilization of nanoparticles; Catalytic reaction; Cationic surfactant; Immobilization; Nanostructure; Transition metal Complexes; Experimental study; Hydrogenation; Silica; Supported catalyst; Quaternary ammonium compound; Hydrolysis; Heterogeneous catalysis; Hexyl alcohol; Water oil microemulsion; Rhodium Complexes; Preparation; Gas solid interface; Carbon monoxide
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/S0920-5861(98)00216-8

It was previously found that the silica-supported rhodium catalyst prepared using water-in-oil microemulsion had rhodium particles partly, or wholly, embedded in silica. In this work, consequently, we investigated the effect of hydrolysis conditions of tetraethylorthosilicate, employed as the source of silica, on the atomic ratio of surface rhodium in contact with the gas phase, to total surface rhodium of nanoparticles. This ratio is denoted as R in this paper. R became higher when the catalyst was prepared under the following hydrolysis conditions: a shorter hydrolysis time and a smaller amount of tetraethylorthosilicate. On the other hand, R showed the minimum value when the water content in the preparation solution was 33 vol%. From these results, it is demonstrated that it was important to form silica as early as possible in hydrolysis of TEOS in order to increase R values. In addition, the effect of R on the catalytic behavior in CO hydrogenation was investigated. At R values below 30%, the turnover frequencies increased with a decrease in R.