Abstract: Taking advantage of the substitutability of the framework and the modifiability of the surface, the structural characteristics and the surface properties of MCM-41 were adjusted and controlled by transition-metal substitution.Owing to the accessibility of active site.and lower diffusion resistance, transition-metal substituted MCM-41 materials were chosen as catalysts for the hydroxylation of aromatics.Isomorphous substituted MCM-41 materials with well-ordered structrues were hydrothermally synthesized by adding Al or Ti, Fe, Cr and Ni compounds to the reaction mixtrue.Not only do the long-range characterisitcs and local structures vary with the nature and amount of the heteroatom, but the characteristics of the pore structure can also be adjusted to some extent by isomorphous substitution.Meanwhile, the surface acidity and the surface hydrophilicity of MCM-41 increased after inserting Al or transition metal elements into the framework, while the results of benzene and methanol-TPDshow that the surface hydrophobicity of MCM-41 decreased.Transition-metal substituted MCM-41 materials were used as catalysts for the liquidphase hydroxylation of aromatics.The catalytic activities of substituted MCM-41 are influenced by both the redox properties of the transition elements and the surface hydrophilicity/hydrohobicity.owing to its Lewis acid nature and the hydrophobic surface, Ti-MCM-41gives high conversion of benzene and high chemical selectivity to the intermediate productphenol.The chemical selectivity can be controlled by matching the hydrophilicity/hydrophobicity of the MCM-41 catalyst, and the polarity of the solvent to the polarities of the reacantbenzene and intermediate product-phenol.MCM-41 exhitits some geometrical selectivity because of the narrow distribution of pore diameters.The accessible active sites, lower diffusio n resistance and unique surface properties result in a better catalytic performance than microporous TS-1 in the hydroxylation of benzene.The MCM-41 catalysts can be reactived by calcination.

Key words: Transition metal substitutied, MCM-41, Surface properties, Hydroxylation of benzene