Influence of template content on selective synthesis of SAPO-18, SAPO-18/34 intergrowth and SAPO-34 molecular sieves used for methanol-to-olefins process
Influence of template content on selective synthesis of SAPO-18, SAPO-18/34 intergrowth and SAPO-34 molecular sieves used for methanol-to-olefins process
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DOI：
10.1039/c6ra23048b
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发表时间：
2016-11
期刊：
影响因子：
3.9
通讯作者：
Ya Wang;Sheng-Li Chen;Yongyong Jiang;Ying-qian Cao;Fen Chen;Wei-Ke Chang;Yueqi Gao
中科院分区：
文献类型：
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作者：
Ya Wang;Sheng-Li Chen;Yongyong Jiang;Ying-qian Cao;Fen Chen;Wei-Ke Chang;Yueqi Gao
采用不同用量的模板（四乙基氢氧化铵，TEAOH）选择性合成了SAPO-18、SAPO-18/34互生长分子筛和SAPO-34分子筛。采用XRD、XRF、TG-DSC、13C (29Si) CP/MAS NMR和NH3-TPD对样品进行了表征。随着TEAOH用量的增加，合成产物从SAPO-5/18依次转变为SAPO-18、SAPO-18/34、SAPO-34。SAPO-18笼中TEAOH主要起填充空间的作用。而在SAPO-34中，TEAOH主要用于补偿框架的负电荷。与SAPO-18和SAPO-18/34相比，SAPO-34具有更多的Si（4Al）结构。对于甲醇制烯烃反应，SAPO-18的丙烯和C4产率最高，SAPO-34的乙烯产率最高。SAPO-18/34和SAPO-34的工作寿命明显长于SAPO-18。
SAPO-18, SAPO-18/34 intergrowth and SAPO-34 molecular sieves have been selective synthesized using different amount of template (tetraethyl ammonium hydroxide, TEAOH). The samples were characterized by XRD, XRF, TG-DSC, 13C (29Si) CP/MAS NMR and NH3-TPD. The synthesized products switched from SAPO-5/18, to SAPO-18, SAPO-18/34, and finally to SAPO-34 with the increasing of TEAOH amount. The TEAOH in SAPO-18 cages mainly acted the role of space filling. While in SAPO-34, the TEAOH was mainly used to compensate the negative charge of the framework. SAPO-34 possessed much more Si(4Al) structure compared to SAPO-18 and SAPO-18/34. For methanol to olefins reaction, SAPO-18 yielded the highest propene and C4 than that over SAPO-18/34 and SAPO-34, SAPO-34 had the highest ethene yield among the three catalysts. The working lifetimes of SAPO-18/34 and SAPO-34 were significantly longer than that of SAPO-18.