Effects of surface properties of Ti-MCM-41 and solvent polarity on chemical selectivity for benzene hydroxylation

A variety of Ti-MCM-41 samples with different structural characteristics an d surface properties have been prepared by taking advantage of the substitu tability of the framework and the modifiability of the surface. When the sa mples were used as a catalyst for benzene hydroxylation, the chemical selec tivity was found to be affected by the following two factors. When the Ti-M CM-41 catalyst surface was covered with alkali metal ions and the surface h ydrophilicity/hydrophobicity of Ti-MCM-41 was altered by inserting Al ions into the framework, the accessibility of the active sites on Ti-MCM-41 to r eactant (benzene) and intermediate product (phenol) can be controlled, givi ng rise to enhanced chemical selectivity. The chemical selectivity of Ti-MC M-41 also can be controlled by varying the polarity of the solvent. When bo th the factors were varied together, the chemical selectivity of Ti-MCM-41 catalyst in benzene hydroxylation can be considerably enhanced.