Silica-supported Rh catalysts were prepared, using W/O microemulsion composed of organic solvent, surfactant and water for the purpose of controlling Rh particle size regardless of Rh content of the catalysts. In this study, the effects of surfactants were investigated and it was found that Rh particle size could be widely varied from 3.0 to 7.0 nm by altering the type of the syrfactants. It is likely that all Rh particles were not exposed on the surface of the catalyst by this method of preparation. because the carrier was synthesized after the Rh particles were formed. The ratio of the exposed surface to the total surface of the Rh particles, accordingly, was evaluated by the ratio of the Rh particle size, calculated by CO chemisorption, to that measured by TEM. It was found that the ratios were scarcely affected by the surfactants and showed a constant value of 60%, apart from that the surfactant contained a large amount of Na. The sprecific surface areas of the catalysts were also varied to a great extent by the surfactants and time of hydrolysis of tetraethyl orthosilicate. The specific surface areas decreased as time of hydrolysis increased. These results suggest that the rate of hydrolysis and the growth of the silica formed were dependent upon the type of the surfactants.
|Number of pages
|Sekiyu Gakkaishi (Journal of the Japan Petroleum Institute)
|Published - Dec 1 1996
All Science Journal Classification (ASJC) codes
- Fuel Technology
- Energy Engineering and Power Technology