Particle-size Control of Rhodium Dispersed on Silica and Its Effects on Decomposition of 1-Propanol

The techniques to control metal-particle size were investigated by using tetraethyl silicate and rhodium nitrate dissolved in ethylene glycol. The particles in the reduced catalyst were in an even size level, and the mean particle size increased with an increase in the concentration of rhodium in the catalyst, varying from 0.34 to 6.89% in weight. The effects of metal-particle size on the decomposition of 1-propanol were explained in terms of the fraction of the metal atoms being located at the corners and edges in the metal crystallites. During the decomposition of the alcohol, 1-propanol adsorbed on the corner and edge atoms to form propionaldehyde (ads), and then the adsorbed species moved to rhodium atoms on the surface planes of the crystallites to be decomposed to carbon monoxide and ethylene, since propionaldehyde was decomposed to carbon monoxide and ethylene at the surface plane atoms of nickel crystallites in Ni/SiO2 catalyst. Recent studies on the relationship between metal-particle size and its effects on catalytic behavior were also surveyed and discussed in the present communication.