分别以三乙胺、环己胺和四乙基氢氧化铵为结构导向剂,二缩三乙二醇为溶剂,研究了3种溶剂热合成体系在常压和自生压力条件下的晶化行为.在常压加热条件下,从分别含有三乙胺、环己胺和四乙基氢氧化铵的初始凝胶中快速晶化出了高结晶度的磷酸铝分子筛AlPO4-5.在自生压力加热条件下,从相同的初始凝胶中分别晶化出了三维开放骨架磷酸铝JDF-20、二维层状磷酸铝UT-5以及含有磷酸铝分子筛AlPO4-5的混相.含有三乙胺的初始凝胶晶化过程的原位热重-质谱研究表明,常压条件下磷酸铝分子筛AlPO4-5主要在150~300 ℃之间生成.实验表明,自生压力会对有机胺(铵)的结构导向效应产生显著影响,这加深了对分子筛以及开放骨架生成过程及机理的认识.%The crystallization behavior of the initial gels containing the structure-directing agents of triethyl-amine,cyclohexylamine or tetraethylammonium hydroxide under ambient pressure and autogenous pressure at elevated temperature was investigated. At 300 or 180 ℃ under ambient pressure, highly crystalline alumino-phosphate molecular sieve AlPO4-5 was rapidly crystallized from the initial gels containing triethylamine, cy-clohexylamine or tetraethylammonium hydroxide. When the same initial gels were loaded into autoclaves and heated at 180 ℃ in an oven, three-dimensional open-framework aluminophosphate JDF-20, layered alumino-phosphate UT-5,and a mixture containing aluminophosphate molecular sieve AlPO4-5,were obtained,respec-tively. The crystallization process of the initial gel containing triethylamine under ambient pressure was investi-gated with in situ thermogravimetric-mass spectroscopy analysis.It was confirmed that the formation of alumino-phosphate molecular sieve AlPO4-5 under ambient pressure was mainly occurred in the stage of 150—300℃. We found that the pressure can significantly affect the structure-directing effect of amines. This finding greatly enhanced the understanding on the formation process and crystallization mechanism of zeolites and open-framework crystals.
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