关键词: SAPO-5分子筛结构, 模板剂状态, 硅源, 晶化时间, MAS NMR

Abstract: A series of SAPO-5 molecular sieves have been synthesized by varying the aging time and silicon source, their structures have been characterlzed by XRD and ²⁷Al MAS NMR spectra. The state of the template in molecular sieves were studied by ¹³C CP MAS NMR. The results reveal that when using silicon gel as silicon source, prolonging aging time can improve the structure of SMO-5 within a linlit of 48 h, when beyond this limit,the produced SAPO-5 is gradually decomposed and some of them is changed into SAPO-34 with a chabazite structure. However, when using Si(OEt)₄ as silicon source, prolonging aging time can improve the structure of SAPO-5 and make Si occupy the framework in the crystallization time of 0 to 72 h. These differences may result from that SiO₂ gel has a higher activity than Si(OEt)₄.The results of ¹³C MAS NMR of the tcmplate in SAPO-5 show that SAPO-5 has some influence on the state of the template. Probably for the methyl group in Et₃N existing at the gate of the pore,the framework can exert some effect on it,so its delay time is different from that of the methylene group connected with nitrogen. Its NMR line intensity decreases with the crystallinity of SAPO-5 and can be used as a pro be to study the crystallinity of SAPO-5.

Key words: Structure of SAPO-5 molecular sieve, Template state, Silicon souroc, Agingtime, MAS NMR