Abstract: The mesoporous molecular sieve Ti-HMS was synthesized using long-chain dodecylamine as the template. The crystallization process, structural properties, and catalytic performance of Ti-HMS were compared with that of microporous molecular sieve TS-1 prepared by modified classical synthesis. With the increase in crystallization temperature, the relative crystallinity of Ti-HMS decreased, and the pH value of the mother liquid changed little during the crystallization process, which might be attributed to its crystallization mechanism differed from TS-1. Unlike TS-1 having typical crystalline character, the Ti-HMS molecular sieve exhibited amorphous characteristics except for the lattice fringe in some area of its HRTEM image. The UV-Vis spectrum indicated that the framework Ti species of Ti-HMS were in distorted tetrahedral environment. In oxidation of bulky sulfur compounds such as benzothiophene, the Ti-HMS molecular sieve had very high catalytic activity, with a benzothiophene removal rate of about 100%. However, TS-1 was inactive for this reaction because of the diffusion restriction. In addition, Ti-HMS showed lower activity than TS-1 for selective oxidation of small molecular reactants owing to its weaker oxidative ability and lower shape selective catalytic performance.

Key words: mesoporous molecular sieve, microporous molecular sieve, crystallization, thiophene, benzothiophene, oxidation