Silica-supported MoO3 catalyst prepared by slurry impregnation method exhibits higher activity and dispersion capacity compared to the MoO3/SiO2 prepared conventionally. Slurry MoO3/water is used instead of the solution ammonium heptamolybdate. Highly dispersed amorphous Mo catalysts are obtained, which is closely related the catalytic activities, without calcination, waste solutions, and calcining nitrogeous gases. The dependence of catalytic activity on Mo loading for the slurry prepared catalysts was similar to the samples prepared by the conventional impregnation method, indicating the slurry method is a simple and clean alternative to the conventional one.