Particle size of NiO in silica with well defined mesoporous structure can b
e controlled from 3.5 to 10 nm regardless of NiO content up to 30 wt% by so
lution exchange of wet silica gel derived from sol-gel process. Ni surface
area of samples reduced at 500 degrees C can be enlarged by decreasing the
NiO particle size. resulting in 30 m(2)g(-1) at 30 wt% loading. The catalys
ts showed superior activities for gas-phase hydrogenation of benzene.