Structural formation process of Ni/SiO2 and Cu/SiO2 catalysts prepared by s
olution exchange of wet silica gel was investigated. Microstructures of Cu/
SiO2 and Ni/SiO2 were quite different from each other. In the case of Cu/Si
O2, Cu particles with diameter of ca. 3-5 nm dispersed homogeneously at les
s Cu content, and the particle size of Cu as well as pore size of silica ge
l support increased with increasing Cu content. In the Ni/SiO2, the Ni part
icles with diameter of ca. 6-10 nm gathered densely to form aggregates in s
ilica matrix resulting in sea-island structure, whereas the size of Ni part
icle slightly increased with increasing Ni content. The difference in the s
tructure of the metal-silica composites is probably caused by the differenc
e in interaction between silica gel network and metal ions during drying an
d heating processes.