2005 Volume 48 Issue 2 Pages 90-96
Ni/SiO2 catalysts were prepared by fume pyrolysis of Ni-silica sols prepared under different conditions, and the porosities and Ni dispersions were evaluated by comparison with catalysts prepared by vacuum drying. Fume pyrolysis of Ni-doped silica polymers with Ni-O-Si bonds created by the sol-gel process resulted in the formation of microporous and highly dispersed catalysts. Similar features were also obtained from a mixed solution of pure silica polymers and Ni ions without Ni-O-Si bonds. However, the pore structure was independent of the sol viscosity in the former, whereas an increase in the viscosity led to an increase in the pore volume in the latter. The catalysts obtained by vacuum drying of the same sols had mesopores and the viscosity effect on the porosity was different. In addition, the Ni particles were larger. The differences in the pore structure were probably attributable to whether or not the precursory particles in the solutions grew during the drying processes.
