高等学校化学学报 ›› 2018, Vol. 39 ›› Issue (1): 12.doi: 10.7503/cjcu20170590

• 研究论文: 无机化学 • 上一篇    下一篇

开放骨架结构磷酸铝合成中N原子环境变化对甲胺结构导向效应的影响

常晓文1, 闫文付1(), 师唯2, 徐如人1   

  1. 1. 吉林大学无机合成与制备化学国家重点实验室, 化学学院, 长春 130012
    2. 南开大学化学学院先进能源材料化学教育部重点实验室, 天津 300071
  • 收稿日期:2017-08-31 出版日期:2018-01-10 发布日期:2017-12-19
  • 作者简介:联系人简介: 闫文付, 男, 博士, 教授, 博士生导师, 主要从事无机微孔材料的晶化机理及手性分子筛的合成与应用研究. E-mail:yanw@jlu.edu.cn
  • 基金资助:
    国家自然科学基金(批准号: 21571075, 21320102001, 21621001)、 国家“八六三”计划项目(批准号: 2016YFB0701100)、 高等学校学科创新引智计划(批准号: B17020)和吉林大学高层次科技创新团队项目资助

Influence of Environment Change Around N-atom on the Structure-directing Effect of Methylamine in the Synthesis of Open-framework Aluminophosphates

CHANG Xiaowen1, YAN Wenfu1,*(), SHI Wei2, XU Ruren1   

  1. 1. State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, China
    2. Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education), Nankai University, Tianjing 300071, China
  • Received:2017-08-31 Online:2018-01-10 Published:2017-12-19
  • Contact: YAN Wenfu E-mail:yanw@jlu.edu.cn
  • Supported by:
    † Supported by the National Natural Science Foundation of China(Nos.21571075, 21320102001, 21621001), the National Key Research and Development Program of China(No.2016YFB0701100), the Program of Introducing Talents of Discipline to Universities, China(No.B17020) and the Program of Science and Technology Innovative Research Team of Jilin University, China

摘要:

以甲胺(MA)和二甲胺(DMA)为结构导向剂, 在200 ℃加热摩尔组成为n(Al2O3):n(P2O5):n(R):n(H2O)=1:1:1:277(R=MA, DMA)的混合物, 分别得到了高结晶度的三维阴离子开放骨架磷酸铝AlPO4-53和AlPO4-21. 质子化的甲胺和二甲胺分别位于AlPO4-53和AlPO4-21的骨架中以平衡骨架的负电荷. 利用X射线粉末衍射分析、 元素分析和液相酸碱度测量等表征手段, 研究了2个合成体系的晶化过程以及晶化过程中液相的Al, P浓度和pH值随时间的演化. 理论计算结果表明, 质子化甲胺和二甲胺的N原子上的电荷分别为-0.263和-0.558 e(Mulliken), 形式电荷密度分别为22.3和16.0 e/nm3, AlPO4-53和AlPO4-21的骨架电荷密度分别为-3.3和-3.1 e/nm3. 结果表明, 改变N原子的环境会影响其上的电荷量, 从而改变有机胺的结构导向效应, 有机胺的形式电荷密度和无机骨架电荷密度之间存在着匹配关系.

关键词: 沸石, 磷酸铝, 结构导向效应, 模板效应, 形式电荷密度, 骨架电荷密度

Abstract:

By heating the initial mixture with the molar composition of n(Al2O3):n(P2O5):n(R):n(H2O)=1:1:1:277(R=methylamine or dimethylamine) at 200 ℃, highly crystalline three-dimensional anionic open-framework aluminophosphate of AlPO4-53 or AlPO4-21 was obtained. Protonated methylamine and dimethylamine were located in the framework of AlPO4-53 and AlPO4-21 to balance the negative charge of the framework, respectively. The crystallization processes of both initial mixtures were investigated by X-ray diffraction analysis(XRD), elemental analysis and pH measurement. Theoretical calculation shows that the charge on the N atom of protonated methylamine and dimethylamine is -0.263 and -0.558 e(Mulliken), respectively. The corresponding formal charge density is 22.3 and 16.0 e/nm3, respectively. The framework charge density of AlPO4-53 and AlPO4-21 is -3.3 and -3.1 e/nm3, respectively. These results indicate that the environment change around N atom can affect the amount of charge on it, which accordingly affects its structure-directing ability. A charge matching between the formal charge density of organic amines and the framework charge density was observed.

Key words: Zeolite, Aluminophosphate, Structure-directing effect, Template effect, Formal charge density, Framework charge density

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