物理化学学报 >> 2015, Vol. 31 >> Issue (2): 344-352.doi: 10.3866/PKU.WHXB201412163

催化和表面科学 上一篇    下一篇

Ce改性对Y型分子筛酸性及其催化转化性能的调变机制

张畅1, 秦玉才1, 高雄厚2, 张海涛2, 莫周胜3, 初春雨1, 张晓彤1, 宋丽娟1,3   

  1. 1. 辽宁石油化工大学, 辽宁省石油化工催化科学与技术重点实验室, 辽宁 抚顺 113001;
    2. 中国石油天然气股份有限公司石油化工研究院兰州化工研究中心, 兰州 730060;
    3. 中国石油大学华东, 化学工程学院, 山东 青岛 266555
  • 收稿日期:2014-10-08 修回日期:2014-12-15 发布日期:2015-01-26
  • 通讯作者: 宋丽娟, 高雄厚 E-mail:lsong56@263.net;gaoxionghou@petrochina.com.cn
  • 基金资助:

    国家自然科学基金(21076100, 21376114)和中国石油天然气股份有限公司炼油催化剂重大专项(10-01A-01-01-01)资助项目

Modulation of the Acidity and Catalytic Conversion Properties of Y Zeolites Modified by Cerium Cations

ZHANG Chang1, QIN Yu-Cai1, GAO Xiong-Hou2, ZHANG Hai-Tao2, MO Zhou-Sheng3, CHU Chun-Yu1, ZHANG Xiao-Tong1, SONG Li-Juan1,3   

  1. 1. Key Laboratory of Petrochemical Catalytic Science and Technology of Liaoning Province, Liaoning ShiHua University, Fushun 113001, Liaoning Province, P. R. China;
    2. Lanzhou Petrochemical Research Center, Petrochemical Research Institute, Petro China Company Limited, Lanzhou 730060, P. R.China;
    3. College of Chemistry and Chemical Engineering, China University of Petroleum East China, Qingdao 266555, Shandong Province, P. R. China
  • Received:2014-10-08 Revised:2014-12-15 Published:2015-01-26
  • Contact: SONG Li-Juan, GAO Xiong-Hou E-mail:lsong56@263.net;gaoxionghou@petrochina.com.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21076100, 21376114) and Major Program of Petroleum Refining of Catalyst of Petro China Company Limited, China (10-01A-01-01-01).

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摘要：

采用液相离子交换(LPIE)法制备了不同离子交换度的CeY分子筛. 运用电感耦合等离子发射光谱(ICPAES)、X射线衍射(XRD)、N2吸附等温线和氨气程序升温脱附(NH3-TPD)等方法对其进行表征, 采用原位傅里叶变换红外(in situ FTIR)光谱技术分别以吡啶和噻吩作为探针分子研究了Ce改性对Y型分子筛酸性能和催化转化性能的影响规律. 结果表明, Ce离子改性不改变Y 型分子筛晶体的基本骨架, 但改变其精细结构. 分子筛改性过程中Ce物种优先定位于方钠石(SOD)笼, 随着稀土离子含量增大, 逐渐出现在超笼中. Ce离子交换过程中产生一定量的Brönsted (B)酸中心, 且其量与强度随着Ce含量的增大均呈现先增加后平稳的趋势. 同时, Ce离子交换产生与非骨架铝物种和铈物种有关的两种强度不同的Lewis (L)酸中心, 且两者均随着Ce含量的增大而增大. 噻吩吸附红外光谱表明, 由于Ce离子改性产生的强B酸中心可导致噻吩在室温条件下即可发生质子化反应, 质子化的噻吩分子可进一步发生低聚反应. 而稀土物种与B酸中心的协同作用有利于低聚反应的发生.

关键词: 原位傅里叶变换红外光谱, CeY, 酸性, 噻吩, 催化转化

Abstract:

Y-type zeolites with different cerium ion content were prepared by liquid phase ion exchange (LPIE) and their structural properties were characterized by inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray diffraction (XRD), N2 adsorption isotherm, and temperature-programmed desorption of ammonia (NH3-TPD). The influence of cerium ion modification of the Y-type zeolites on the acidity and catalytic behavior was studied by in situ Fourier transform infrared spectroscopy (in situ FTIR) techniques with pyridine and thiophene as probe molecules. The results indicate that the original crystal structures of the zeolites remain unchanged after modification with cerium ions. During the modification process the Ce species tend to be located in sodalite (SOD) cages after calcination and remain in the supercages upon a gradual increase in Ce cation content. The amount and strength of the Brönsted (B) acid sites in the zeolites generated by the modification increases initially and then stabilizes with an increase in Ce ion content. The strong and weak Lewis (L) acid sites related to the non-framework aluminum and the rare earth species increase continuously during the modification process. Thiophene adsorption FTIR spectra indicate that the adsorbed thiophene molecules protonate at the strong Brönsted acid sites of the zeolites. The protonated products then oligomerize. The synergy between Ce species and B acid sites is favorable for the thiophene oligomerization reaction.

Key words: In situ Fourier transform Infrared spectroscopy, CeY, Acidity, Thiophene, Catalytic conversion