Control of the rhodium particle size of the silica-supported catalysts by using microemulsion

The control of the rhodium particle size of silica-supported catalysts by u sing microemulsion was investigated in terms of the structure of surfactant s and organic solvents. The use of nonionic surfactants and anionic surfact ants is effective for the preparation of catalysts having narrow size distr ibution. Especially, in nonionic surfactants, the rhodium particle size var ied in the range of 3.0-8.2 nm according to the structure of surfactants an d organic solvents regardless of rhodium content. The length of the hydroph ilic group of surfactants and the carbon number of n-alcohol as an organic solvent were effective factors for the size control. The rhodium particle s ize increased with decreasing length of the hydrophilic groups of surfactan ts and with increasing carbon number of n-alcohol. (C) 2000 Elsevier Scienc e B.V. All rights reserved.