催化学报

催化学报 ›› 2007, Vol. 28 ›› Issue (7): 617-621.

• 研究论文 • 上一篇    下一篇

硅烷化处理的纳米ZSM-5的结构表征及催化性能

王坤院,王祥生,李钢,龙化云   

  1. 大连理工大学催化化学与工程系精细化工国家重点实验室, 辽宁大连 116012
  • 收稿日期:2007-07-25 出版日期:2007-07-25 发布日期:2011-07-25

Characterization and Catalytic Activity of Silylated Nanoscale ZSM-5

WANG Kunyuan, WANG Xiangsheng*, LI Gang, LONG Huayun   

  1. State Key Laboratory of Fine Chemicals, Department of Catalytical Chemistry and Engineering, Dalian University of Technology, Dalian 116012, Liaoning, China
  • Received:2007-07-25 Online:2007-07-25 Published:2011-07-25

PDF

1025

被引次数

53

摘要： 采用多次浸渍法和化学反应沉积法对纳米HZSM-5分子筛外表面进行了硅烷化处理,考察了改性后纳米ZSM-5对甲苯歧化的催化活性. 采用改进的Hammett指示剂法和吡啶吸附红外光谱研究了催化剂的酸性位,采用X射线衍射和29SiMAS NMR对催化剂的结构进行了表征. 研究结果表明,硅烷化处理降低了纳米ZSM-5酸性位的浓度,从而降低了纳米ZSM-5的催化活性. 硅烷化处理还减少了纳米ZSM-5中Si的Q4物种,降低了纳米ZSM-5的相对结晶度,同时硅烷化处理产生了脱铝作用. 骨架铝含量的减少导致催化剂的酸性位减少,催化活性降低.

关键词: 纳米ZSM-5沸石, 硅烷化, 甲苯, 歧化

Abstract: Multiple impregnations and chemical reaction deposition were used to modify the external surface of nanoscale ZSM-5 with tetraethoxysilane. Toluene disproportionation over this silylated ZSM-5 was investigated. The acid sites of the catalysts were measured by modified Hammett indicators and FT-IR spectroscopy of adsorbed pyridine. The catalyst structure was characterized by X-ray diffraction and29SiMAS NMR. The results showed that silanization of the zeolite decreased the concentration of acid sites, which led to the decrease in catalytic activity. The silanization also decreased the amount of Q4 species of Si and the relative crystallinity of the zeolite. Dealumination was observed on the surface of nanoscale ZSM-5. The decrease in the number of framework aluminum resulted in a decline in the number of acid sites and catalytic activity.

Key words: nanoscale ZSM-5 zeolite, silanization, toluene, disproportionation