催化学报

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以正丁胺为模板剂合成SAPO-34及其在氨甲基化反应中的应用

乔昱焱a,b, 吴鹏飞a,b, 向骁a,b, 杨淼a, 王全义a, 田鹏a, 刘中民a   

  1. a 中国科学院大连化学物理研究所, 甲醇制烯烃国家工程实验室, 辽宁大连 116023;
    b 中国科学院大学, 北京 100039
  • 收稿日期:2016-11-28 修回日期:2016-12-25 出版日期:2017-03-18 发布日期:2017-03-22
  • 通讯作者: Peng Tian, Zhongmin Liu
  • 基金资助:

    国家自然科学基金(21676262, 21476228, 21506207);中国科学院前沿科学重点研究项目(QYZDB-SSW-JSC040).

SAPO-34 synthesized with n-butylamine as a template and its catalytic application in the methanol amination reaction

Yuyan Qiaoa,b, Pengfei Wua,b, Xiao Xianga,b, Miao Yanga, Quanyi Wanga, Peng Tiana, Zhongmin Liua   

  1. a National Engineering Laboratory for Methanol to Olefins, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China;
    b University of Chinese Academy of Sciences, Beijing 100039, China
  • Received:2016-11-28 Revised:2016-12-25 Online:2017-03-18 Published:2017-03-22
  • Supported by:

    This work was supported by the National Natural Science Foundation of China(21676262, 21476228, 21506207) and the Key Research Program of Frontier Sciences of CAS (QYZDB-SSW-JSC040).

摘要:

以正丁胺为模板剂首次合成了纯相的SAPO-34分子筛.考察了硅投料量、硅源种类以及晶化温度等条件对所得样品性质的影响.发现反应温度为200℃时,不加入硅源,合成产物为磷酸铝层状相kanemite;加入硅溶胶后,产物中开始有SAPO-34晶体出现,且随着硅投料量的增加,kanemite逐渐消失,SAPO-34分子筛成为主要产物,最终在SiO2/Al2O3摩尔比为0.6-1.4时得到纯相的SAPO-34.不同的硅源对SAPO-34产品的形貌和尺寸影响较大.反应温度为160℃时,合成体系中无法晶化得到SAPO-34,当提高至240℃后,由于层状相在高温下不能稳定存在,此时可以在较宽的硅投料区间内合成得到纯相SAPO-34产品.在200和240℃时,考察了使用同样的初始凝胶合成SAPO-34样品的晶化过程.发现在200℃时,合成体系中最初大量生成了kanemite,随后逐渐减少,SAPO-34晶体开始生成并最终成为唯一产物.而在240℃时,无机原料很快被溶解,之后大量的SAPO-34晶体快速生成,产物的收率和相对结晶度迅速增加,且整个晶化过程中并无层状相生成.这再次证明了高温对层状相的生成有着明显的抑制作用,因此提高晶化温度可以成为一种有效调节产品晶相的方法,特别是在容易产生层状相杂质的合成体系中.鉴于胺热合成方法的诸多优点,例如较高的收率、较好的吸附分离及催化反应效果,几种伯胺(正丁胺、正丙胺、环己胺)被用于充当模板剂和溶剂来合成得到了SAPO分子筛产品.其中,正丙胺为一种新的合成SAPO-34的模板剂.对SAPO-34产品进行X射线衍射、X射线荧光分析、扫描电镜、N2物理吸附、NH3程序升温脱附、热重和固体核磁共振等表征.结果显示,得到的SAPO-34产品具有很好的结晶度、孔结构以及合适的酸性.使用氨甲基化反应对正丁胺合成的SAPO-34进行催化反应评价.结果显示,该样品对甲胺和二甲胺具有很高的择形选择性,是一种具有潜在前景的甲胺合成催化剂.

关键词: SAPO-34分子筛, 正丁胺, 伯胺, 合成, 高温, 氨甲基化反应

Abstract:

SAPO-34 was synthesized with n-butylamine (BA) as a template for the first time. Crystallization temperature and initial Si amount were important factors leading to successful syntheses. Lamellar AlPO-kanemite tends to form as the major phase or as an impurity of SAPO-34 at lower crystallization temperatures, though a higher initial Si amount may offer a positive effect on the crystallization of SAPO-34 that mitigates the low temperature. Higher temperature (240℃) can effectively suppress the generation of lamellar materials and allow the synthesis of pure SAPO-34 with a wider range of Si incorporation. The crystallization processes at 200 and 240℃ were investigated and compared. We used the aminothermal method to synthesize SAPO-34-BA at 240℃ and also found n-propylamine is a suitable template for the synthesis of SAPO-34. The SAPO-34-BA products were characterized by many techniques. SAPO-34-BA has good thermal stability, crystallinity and porosity. BA remained intact in the crystals with ~1.8 BA molecule per chabazite cage. The catalytic performance of SAPO-34 was tested in the methanol amination reaction, which showed high methanol conversion and selectivity for methylamine plus dimethylamine under the conditions investigated, suggesting that this material is a good candidate for the synthesis of methylamines.

Key words: SAPO-34 molecular sieve, n-Butylamine, Primary amine, Synthesis, High temperature, Methanol amination