Molecular engineering of microporous crystals: (V) Investigation of the structure-directing ability of piperazine in forming two layered aluminophosphates

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• 作者：Xiaoqiang Tong^a ; ¹ ; Jun Xu^b ; ¹ ; Chao Wang^b ; Huiying Lu^a ; Pai Huang^a ; Wenfu Yan^a ; ^{yanw@jlu.edu.cn} ; Jihong Yu^a ; Feng Deng^b ; Ruren Xu^a ; ^{rrxu@jlu.edu.cn}
• 关键词：Zeolite ; Aluminophosphate ; Templating effect ; Structure-directing role ; Piperazine
• 刊名：Microporous and Mesoporous Materials
• 出版年：2012
• 期刊代码：78_13871811
• 类别：ch
• 出版时间：1 June, 2012
• 卷：155
• 期：Complete
• 页码：153-166
• 文件大小：1573 K

摘要

The crystallization process of the layered aluminophosphates AP2pip and AlPO-CJ9 from initial mixtures with compositions of Al₂O₃:P₂O₃:1.1 piperazine:277 H₂O and Al₂O₃:P₂O₃:4.0 piperazine:277 H₂O, respectively, was investigated using multiple techniques. During the crystallization of AP2pip, the formation and dissolution of highly polymerized but structurally disordered fragments containing four-coordinated P sites to Al-centered polyhedra were observed. ²⁷Al 鈫?#xA0;³¹P CP/MAS HETCOR NMR analysis showed that the local P-site environment in the small building fragments formed in the initial mixture is same as that in the final crystal structure of AP2pip. The concentration of these small building fragments is very low. During the crystallization of AlPO-CJ9, the formation of small building fragments with the local P-site environment same or very similar to that observed in the final structure of AlPO-CJ9 were observed. The concentration of these small building fragments is high. These small fragments contained at least two complete coordination layers. The difference in the structure-directing role played by piperazine in the two synthesis systems was investigated in detail by designing several control experiments and analyzing the arrangements of the piperazine molecules in the interlayer region of AP2pip and AlPO-CJ9.