化学气相沉积法制备Ti／HMS催化剂及甲基接枝改性

Ti/HMS Catalysts Prepared by the Chemical Vapor Deposition Method and Modified by Methyl-grafting

用化学气相沉积法制备了Ti/HMS介孔分子筛催化剂,并对其进行甲基接枝改性.用XRD、N2-吸附、ICP-AES、FTIR,UV-vis和29SiCP/MAS NMR等手段对样品进行了表征,考察了催化剂的丙烯环氧化性能.结果表明:气相沉积法载钛和接枝改性减小了HMS分子筛表面的孔径和比表面,但是分子筛的介孔特征仍然保持;随着沉积时间的增加(0.5～2h),催化剂的钛含量逐渐增加,催化活性也随之增加,但当沉积时间超过2h后,钛含量和催化活性均保持不变;接枝改性后催化剂的环氧化活性和选择性均显著提高;气相沉积法合成Ti/HMS比水热法合成Ti-HMS具有更高的环氧化催化活性.

Ti/HMS mesoporous sieve catalysts were prepared by a chemical vapor deposition method （CVD） and modified by methyl-grafting. The catalysts were characterized by XRD, N2-adsorption, ICP-AES, IR, UV-Vis and 29Si CP/MAS NMR, respectively, and evaluated by the epoxidation of propylene. It was revealed that both the mesopore size and surface area of HMS were decreased after the incorporation of titanium and methyl-grafting treatment, but the mesoporous characteristic was still maintained. Both the titanium content and epoxidation performance were increased with the deposition time （0.542 h）, and all kept invariable after further deposition. The cumene hydroperoxide （CHP） conversion and the selectivity were all enhanced after the methyl-grafting treatment. Ti/HMS prepared by CVD displays better catalytic activity to epoxidation than Ti-HMS prepared hydrothermally.