Enhancing the selectivity of benzene hydroxylation by tailoring the chemical affinity of the MCM-41 catalyst surface for the reactive molecules

A method of controlling selectivity to a target product in an oxidation reaction in which the target product is more reactive than the reactant is put forward in this paper. The affinity of the catalyst surface for substrates with different polarity is controlled through tailoring the surface hydrophobicity/hydrophilicity of the catalyst, thereby enhancing the selectivity. The hydroxylation of benzene is taken as the probe reaction and modified MCM-41 materials are employed as the catalysts. The catalytic performances of transition metal-substituted MCM-41, AI(III) and Ti(IV) cosubstituted MCM-41 and Ti-grafted MCM-41 materials that possess both well-ordered and long-range pore structures, indicate that the surface hydrophobicity/hydrophilicity of the catalysts does indeed significantly affect the affinity of the catalyst surface for reactant molecules with different polarity, thereby influencing the selectivity in the hydroxylation of benzene. (C) 2002 Elsevier Science (USA).