介孔分子筛SiW_(12)/SBA-15的制备及性能研究

采用后合成法制备了SiW_(12)/SBA-15催化剂,并用X射线衍射、N_2吸附脱咐法、热失重法分析催化剂的物理性能。结果表明,SiW_(12)/SBA-15仍保持了介孔分子筛SBA-15的晶体结构,比表面积和孔径分别为589 m~2/g和6.1 nm,且SiW_(12)/SBA-15催化剂在400～450℃温度区失去结晶水,在650～700℃范围内SiW_(12)的Keggin结构破坏。选用月桂酸和乙醇的酯化反应考察SiW_(12)/SBA-15的催化活性和再生性能。SiW_(12)/SBA-15具有良好的催化活性和再生性能,得到最佳的酯化反应条件为:反应温度90℃、催化剂质量分数1%、酸醇摩尔比1:2.5、反应时间5 h。

SYNTHESIS AND PROPERTIES OF MESOPOROUS MOLECULAR SIEVE SiW12/SBA-15

Catalyst SiW_(12)/SBA-15 has been prepared by post-synthetic process and characterized by power X-ray diffraction(XRD),nitrogen gas sorption(BET) and thermogravimetric analysis(TA/ DTA).The results show that the structure of SiW_(12)/SBA-15 catalyst remains that of mesoporous molecular sieves SBA-15,with specific surface area of 589 m~2/g and pore size of 6.1 nm.SiW_(12)/SBA-15 catalyst loses the crystallization water between 400℃and 450℃,and the Keggin structure of SiW_(12) is destroyed between 650℃and 700℃.The esterification reaction of lauric acid with ethanol over SiW_(12)/SBA-15 is investigated.The results show that SiW_(12)/SBA-15 has high stability and can be easily regenerated after deactivation.The optimal reaction conditions have been obtained as follows:reaction temperature 90℃,mass ratio of catalyst to reactant 1%,molar ratio of lauric acid to ethanol 1: 2.5 and reaction time 5 h.