Ti-MCM-41催化剂的表面性质及介质极性对

用不同的铝源改性Ti MCM 41催化剂 ,得到了具有长程有序结构、n(Si) /n(Ti) =2 5的不同Si/Al比的改性Ti MCM 41.通过研究芳烃羟化反应随催化剂表面性质的变化规律发现 ,调变催化剂的表面性质 ,可控制反应物苯及目的产物苯酚与Al Ti MCM 41催化活性中心接近的程度 ,从而可实现对芳烃羟化反应化学选择性的控制 .介质极性对芳烃的化学亲和选择性也有影响 ,只有富含供电子氧原子且其极性大于苯的介质才有利于芳烃的羟化反应

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 and surface properties have been prepared by taking advantage of the substitutability of the framework and the modifiability of the surface. When the samples were used as a catalyst for benzene hydroxylation, the chemical selectivity was found to be affected by the following two factors. When the Ti MCM 41 catalyst surface was covered with alkali metal ions and the surface hydrophilicity/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 reactant (benzene) and intermediate product (phenol) can be controlled, giving rise to enhanced chemical selectivity. The chemical selectivity of Ti MCM 41 also can be controlled by varying the polarity of the solvent. When both the factors were varied together, the chemical selectivity of Ti MCM 41 catalyst in benzene hydroxylation can be considerably enhanced.