利用水热合成法在α-Al2O3陶瓷管表面制备了连续完整的钛硅(TS-1)沸石膜,并且利用该膜催化剂催化丙烯直接环氧化合成环氧丙烷(PO).采用SEM、XRD、FT-IR和UV-Vis等表征手段及丙烯环氧化反应测试,详细研究了合成液中Ti/Si比对TS-1沸石膜形貌、结构及催化性能的影响.结果表明,合成液中Ti/Si比在0.01~0.04范围内,所合成的TS-1沸石膜均具备典型MFI型拓扑结构.但当Ti/Si比>0.02时,随着Ti/Si比升高,TS-1沸石膜表面沸石颗粒排列变得杂乱,且TS-1沸石沉积量逐渐减少,沸石晶间缺陷增多,丙烯渗透速率增大.而且,当Ti/Si比=0.03、0.04时,由于所合成的TS-1沸石膜中存在大量非骨架钛,导致在丙烯环氧化反应中PO选择性和PO生成速率明显降低.当Ti/Si比为0.02时,合成的TS-1沸石膜骨架钛含量最高,其催化性能最佳,H2O2转化率、PO选择性和生成速率分别为12.43%、95.80%和15.78 mmol/(h·g).TS-1沸石膜在丙烯环氧化反应中重复使用8次,其催化性能保持相对稳定.%Titanium silicalite-1(TS-1) zeolite membranes were successfully prepared on porousα-Al2O3 tubes using hydrothermal synthesis method for epoxidation of propylene to propylene oxide (PO). SEM, XRD, FT-IR, and UV-vis spectroscopy were used to investigate the effects of Ti/Si molar ratio on surface morphology and structure of the TS-1 zeolite membrane. When the Ti/Si molar ratio was set between 0.01 and 0.04, continuous and compact TS-1 zeolite membranes were deposited on the porous support. The obtained TS-1 membranes dis-played typical characteristics diffraction peaks of MFI structure. With the increase of the Ti/Si molar ratio, the deposition amounts of the TS-1 zeolites decreased. As a result, some intercrystalline defects were formed and the propylene permeance increased. For the TS-1 membranes prepared with the Ti/Si molar ratio of 0.03~0.04, poor PO selectivity and low PO formation rate were observed in the epoxidation reaction of propylene. This was at-tributed to the formation of extra-framework TiO2 in the TS-1 membranes that could catalyze the decomposition of hydrogen peroxide. In contrast, the TS-1 membrane prepared with the Ti/Si ratio of 0.02 exhibited the best catalytic performance. The conversion of hydrogen peroxide, PO selectivity and PO formation rate were 12.43%, 95.80% and 15.78 mmol/(h·g), respectively. Moreover, the regeneration tests revealed that the catalytic ability of the TS-1 membrane was relatively stable after regeneration for 8 times. And the TS-1 membrane was easier to be separated and recovered after reaction.
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