催化学报

催化学报 ›› 2020, Vol. 41 ›› Issue (11): 1772-1781.DOI: 10.1016/S1872-2067(20)63604-X

• 论文 • 上一篇    下一篇

低成本合成纳米堆积的SAPO-34分子筛及其在糠醇催化醇解反应中的应用

郭倩倩a,b, 杨帆c, 刘晓晖a,b, 孙孟清b, 郭勇a,b, 王艳芹a,b   

  1. a 华东理工大学化学与分子工程学院, 上海市功能性材料化学重点实验室, 上海 200237;
    b 华东理工大学化学与分子工程学院, 工业催化研究所, 上海 200237;
    c 华东理工大学化工学院, 大型工业反应器工程教育部工程研究中心, 上海 200237
  • 收稿日期:2020-02-29 修回日期:2020-03-30 出版日期:2020-11-18 发布日期:2020-08-15
  • 通讯作者: 刘晓晖
  • 基金资助:
    国家自然科学基金（21872050，21832002，21808063）；上海市自然科学基金（18ZR1408500，10dz2220500）.

Low-cost synthesis of nanoaggregate SAPO-34 and its application in the catalytic alcoholysis of furfuryl alcohol

Qianqian Guoa,b, Fan Yangc, Xiaohui Liua,b, Mengqing Sunb, Yong Guoa,b, Yanqin Wanga,b   

  1. a Shanghai Key Laboratory of Functional Materials Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China;
    b Research Institute of Industrial Catalysis, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China;
    c Engineering Research Center of Large Scale Reactor Engineering and Technology, Ministry of Education, School of Chemical Engineer, East China University of Science and Technology, Shanghai 200237, China
  • Received:2020-02-29 Revised:2020-03-30 Online:2020-11-18 Published:2020-08-15
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (21872050, 21832002, 21403065) and the Science and Technology Commission of Shanghai Municipality (18ZR1408500, 10dz2220500).

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摘要： SAPO-34分子筛因其规则的孔结构、独特的择形性和适宜的酸性，在石油化工领域有着重要的应用.本文不添加四乙基氢氧化铵（TEAOH）之外的模板剂，仅改变原料的加入顺序，通过水热合成法制备了两种不同形貌的SAPO-34分子筛（纳米堆积SAPO-34和立方体SAPO-34）.结果表明，前驱体的存在形式和成核速率是导致形貌不同的主要原因.拟薄水铝石和正硅酸乙酯在碱性条件下水解，铝和硅的前驱体分别以Al（OH）4-和SiO2（OH）-的形式存在，二者相互结合生成分子筛生长的基本单元：具有Si-O-Al键的硅铝酸化合物，它们倾向于形成更多的如低聚物、非晶态颗粒或纳米晶等的二级单元，这些二级单元均有利于晶核的快速生成，并在范德华力的作用下进行自组装，形成聚集体堆积的球形纳米晶，纳米晶继续长大，最终生成了结晶度较高的纳米聚集体SAPO-34.而在酸性体系中，铝和硅的前驱体分别以Al3+和（OH）3Si（OH2）+的形式存在，TEAOH加入后，铝会在硅表面沉积，从而显著减慢Si-O-Si键的断裂，使得晶核生成的速度减慢，最终通过一层一层生长的机制进行晶体生长而形成较大的立方体SAPO-34.
为了进一步探讨形貌结构对SAPO-34分子筛酸催化性能的影响，我们选择分子尺寸略大于传统SAPO-34孔道尺寸（约0.38nm）的生物质基糠醇（FAL，约0.53nm）为模型反应物，分别研究了纳米堆积SAPO-34和立方体SAPO-34分子筛在糠醇醇解制备乙酰丙酸乙酯（EL）反应中的催化性能.与传统的立方体SAPO-34相比，纳米堆积SAPO-34分子筛由于纳米晶的堆积具有较大的外比表面积和堆积介孔孔容，从而具有更多的外表面酸性，因此在糠醇醇解反应中表现出更高的EL收率（74.1%），而立方SAPO-34仅有19.9%的EL收率.此外，纳米堆积SAPO-34分子筛也因其具有较大的外比表面和堆积介孔孔容，利于反应过程中乙氧基甲基呋喃中间体、产物及副产物的传质，减少了碳的沉积，从而改善了其稳定性.

关键词: 纳米堆积SAPO-34, 外比表面, 低成本, 催化醇解, 糠醇

Abstract: Silicoaluminophosphate-34 (SAPO-34) molecular sieves have important applications in the petrochemical industry as a result of their shape selectivity and suitable acidity. In this work, nanoaggregate SAPO-34 with a large external surface area was obtained by dissolving pseudoboehmite and tetraethylorthosilicate in an aqueous solution of tetraethylammonium hydroxide and subsequently adding phosphoric acid. After hydrolysis in an alkaline solution, the aluminum and silicon precursors exist as Al(OH)4- and SiO2(OH)-, respectively; this is beneficial for rapid nucleation and the formation of nanoaggregates in the following crystallization process. Additionally, to study the effect of the external surface area and pore size on the catalytic performance of different SAPO-34 structures, the alcoholysis of furfuryl alcohol to ethyl levulinate (EL) was chosen as a model reaction. In a comparison with the traditional cube-like SAPO-34, nanoaggregate SAPO-34 generated a higher yield of 74.1% of EL, whereas that with cube-like SAPO-34 was only 19.9%. Moreover, the stability was remarkably enhanced for nanoaggregate SAPO-34. The greater external surface area and larger number of external surface acid sites are helpful in improving the catalytic performance and avoiding coke deposition.

Key words: Nanoaggregate SPAO-34, External surface area, Low cost, Catalytic alcoholysis, Furfuryl alcohol