物理化学学报 >> 2017, Vol. 33 >> Issue (7): 1483-1491.doi: 10.3866/PKU.WHXB201704133

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氢预处理对Zn/HZSM-5分子筛催化乙烯芳构化反应性能的影响

位春蕾1,2,高洁1,2,王凯1,2,董梅1,*(),樊卫斌1,*(),秦张峰1,王建国1   

  1. 1 中国科学院山西煤炭化学研究所,煤转化国家重点实验室,太原030001
    2 中国科学院大学,北京100049
  • 收稿日期:2017-02-16 发布日期:2017-05-31
  • 通讯作者: 董梅,樊卫斌 E-mail:mdong@sxicc.ac.cn;fanwb@sxicc.ac.cn
  • 基金资助:
    国家自然科学基金(21273264);国家自然科学基金(21273263);国家重点基础研究发展规划项目(973)(2011CB201403);山西省自然科学基金(2012011005-2)

Effect of Hydrogen pre-treatment on the catalytic properties of Zn/HZSM-5 zeolite for ethylene aromatization reaction

Chun-Lei WEI1,2,Jie GAO1,2,Kai WANG1,2,Mei DONG1,*(),Wei-Bin FAN1,*(),Zhang-Feng QIN1,Jian-Guo WANG1   

  1. 1 State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P. R. China
    2 University of Chinese Academy of Sciences, Beijing 100049, P. R. China
  • Received:2017-02-16 Published:2017-05-31
  • Contact: Mei DONG,Wei-Bin FAN E-mail:mdong@sxicc.ac.cn;fanwb@sxicc.ac.cn
  • Supported by:
    the National Natural Science Foundation of China(21273264);the National Natural Science Foundation of China(21273263);Major State Basic Research Development Program of China(973)(2011CB201403);Natural Science Foundation of Shanxi Province, China(2012011005-2)

摘要:

采用浸渍法制备了Zn/HZSM-5分子筛催化剂,进行了不同温度的氢气预处理,通过X射线衍射(XRD)、氮气吸附-脱附、傅里叶变换红外(FT-IR)光谱、NH3程序升温脱附(NH3-TPD)、X射线光电子能谱(XPS)等表征技术,系统考察氢气预处理对Zn/HZSM-5分子筛结构、孔道、酸性、Zn存在状态以及在乙烯芳构化反应中的催化性能等的影响。研究结果表明,氢气预处理温度显著影响Zn/HZSM-5中Zn物种的含量和存在状态:600℃以下的氢处理,几乎不影响分子筛上Zn物种的总含量,而600℃以上氢处理时会造成Zn物种的大量流失;XPS研究显示,氢预处理的温度不同,分子筛上ZnOH+与ZnO的相对比例变化显著。结合乙烯芳构化反应性能,可以发现ZnOH+物种的含量与芳烃选择性存在较好的线性关系,说明其是促进烯烃脱氢、芳构化的主要活性中心,Zn存在状态的变化使得氢气预处理温度显著影响乙烯芳构化反应产物的分布。

关键词: 分子筛, 乙烯芳构化, 氢预处理, 锌物种

Abstract:

After hydrogen pre-treatment at different temperatures, the textural and physicochemical properties of Zn/HZSM-5 were studied by X-ray diffraction (XRD), N2 adsorption-desorption, Fourier transform infrared (FT-IR) spectroscopy, temperature programmed desorption of NH3 (NH3-TPD), and X-ray photoelectron spectroscopy (XPS) techniques. The results showed that the temperatures for hydrogen pretreatment of Zn/HZSM-5 exerted a significant influence on both the contents and state of zinc species. The pre-treatment with hydrogen at temperature higher than 600℃ resulted in a significant leaching of zinc species from the catalysts, which occurred due to the reduction and sublimation of zinc species. The XPS characterization revealed that the hydrogen pre-treatment at different temperatures causes the redistribution of ZnOH+ and ZnO species in the zeolite. A linear correlation between the amount of ZnOH+ species and the selectivity to aromatics over the Zn/HZSM-5 catalysts pretreated with hydrogen at different temperatures was observed, suggesting that ZnOH+ species may promote the formation of aromatics in ethylene aromatization reaction.

Key words: Molecular sieves, Ethylene aromatization, Hydrogen pretreatment, Zn species

MSC2000: 

  • O643