催化学报

催化学报 ›› 2020, Vol. 41 ›› Issue (4): 622-630.DOI: 10.1016/S1872-2067(19)63466-2

• 中国科学院青年创新促进会专栏 • 上一篇    下一篇

无溶剂熔融辅助法合成SAPO-11及其在长链烷烃加氢异构反应的应用

余淦a,b,c, 陈新庆b,c, 薛文杰b, 葛丽霞b, 王婷b, 丘明煌b, 魏伟a,b, 高鹏b, 孙予罕a,b   

  1. a 上海科技大学, 物质科学与技术学院, 上海 201210;
    b 中国科学院上海高等研究院, 中国科学院低碳转化与工程重点实验室, 上海 201210;
    c 中国科学院大学, 北京 100049
  • 收稿日期:2019-09-30 修回日期:2019-10-27 出版日期:2020-04-18 发布日期:2019-12-12
  • 通讯作者: 陈新庆, 孙予罕
  • 基金资助:
    国家自然科学基金（21776295）；中国科学院青年创新促进会（2017355）.

Melting-assisted solvent-free synthesis of SAPO-11 for improving the hydroisomerization performance of n-dodecane

Gan Yua,b,c, Xinqing Chenb,c, Wenjie Xueb, Lixia Geb, Ting Wangb, Minghuang Qiub, Wei Weia,b, Peng Gaob, Yuhan Suna,b   

  1. a School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China;
    b CAS Key Laboratory of Low-Carbon Conversion Science and Engineering, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China;
    c University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2019-09-30 Revised:2019-10-27 Online:2020-04-18 Published:2019-12-12
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (21776295) and the Youth Innovation Promotion Association, CAS (2017355).

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摘要： 长链正构烷烃加氢异构化是润滑油基础油生产的有效方法，可有效改善润滑油的低温物理化学性质.在具有酸位点的载体上负载具有加氢脱氢功能的贵金属制备双功能催化剂得到了广泛研究.SAPO-11分子筛具有一维的孔结构和适宜的酸度，在加氢异构反应中扮演着重要角色.根据加氢异构反应的孔口机理和锁钥机理，位于分子筛晶体外层附近的Brönsted酸位点，对正链烷烃碳骨架的异构化起主要作用.因此，优化分子筛载体的物理化学性质是提高加氢异构性能的关键.近年来，以酸或碱作为蚀刻剂的后处理方法已被广泛用于改变分子筛的物理化学性质.然而，目前的后处理方法主要涉及酸性或碱性水溶液，产生大量废水.此外，蚀刻溶液的使用也导致分子筛的低产率.鉴于此，我们提出了采用无溶剂熔融辅助合成法来处理SAPO-11分子筛，并将其应用于加氢异构反应.该方法以固体草酸作为蚀刻剂，通过与分子筛原粉机械搅拌混合均匀后，直接在水热反应釜中反应，处理过程不会有废水产生.本文以不同量的固体草酸处理原粉，处理得到的样品负载0.5 wt% Pt金属制备一系列贵金属/分子筛双功能催化剂，以正十二烷作为模型反应物，研究制备的催化剂在不同实验条件下的加氢异构化性能.
XRD和SEM表征结果表明，处理前后的SAPO-11分子筛保持了高的结晶度和比较完整的形貌.XRF数据表明处理前后分子筛的元素组成变化不明显.基于特征峰的峰面积计算结果表明，处理后SAPO-11分子筛暴露出更多（002）晶面，有利于更多的分子筛孔口进行加氢异构反应.BET和Py-IR表征表明，经过草酸处理后，SAPO-11原粉颗粒内部的片状晶体的重叠部分被暴露出来，这导致处理后的样品的微孔孔容占比和Brönsted总酸量的增加.加氢异构反应数据表明，n-C12转化率随着SAPO-11分子筛样品Brönsted总酸量的增加而增加，i-C12选择性随SAPO-11分子筛样品的微孔孔容占比的增大而增大.该无溶剂熔融辅助合成法同时优化了Pt-SAPO-11催化剂的酸性质和微孔孔结构性质，提高了反应转化率和选择性，正十二烷异构体的产率从55.3%大幅提高到80.1%，催化性能显著提高.该方法在双功能催化剂加氢异构反应中具有广泛应用的前景.

关键词: 加氢异构, 分子筛, SAPO-11, 无溶剂熔融辅助, 后处理, 双功能催化剂

Abstract: A novel melting-assisted solvent-free route using solid oxalic acid was proposed for the post-treatment of SAPO-11 zeolite, followed by loading with 0.5 wt% Pt by the incipient wetness impregnation method. Subsequently, the performance of the obtained bifunctional catalysts toward the hydroisomerization of n-dodecane was examined. The prepared samples were characterized by XRD, SEM, BET, XRF, Py-IR, and solid-state NMR. From the results, it was found that the high crystallinity and uniform morphology were retained after the post-treatment and that more (002) crystal faces were exposed, which was beneficial since more acid sites were provided. More importantly, the total Brönsted acid sites and the ratio (Ra) of the micropore area to the total surface area were optimized by this method. Thus, the catalytic performance was enhanced significantly, and the prepared Pt-SAPO-11-10% catalyst had the highest i-dodecane yield of 80.1% compared to 55.3% of Pt-SAPO-11. Expectedly, this facile and cost-effective method is promising for the hydroisomerization of normal paraffin in the production of lubricant base oils.

Key words: Hydroisomerization, Zeolite, SAPO-11, Melting-assist, Bifunctional catalyst