Siliceous MCM 41 samples with two different pore size and metal substituted MCM 41 samples with different metals have been synthesized at different pH of the mixture, and characterized by X ray powder diffraction and nitrogen adsorption analysis. The results show that all the samples exhibit a typical XRD diffraction of MCM 41 and an adsorption isotherm of type Ⅳ, but there exists a considerable amount of amorphous silica in the samples. The sample prepared at pH=11(MCM 3) shows the best in quality am...