高等学校化学学报 ›› 1987, Vol. 8 ›› Issue (2): 97.

• 论文 •    下一篇

碱金属化合物改性ZSM-5沸石的择形催化作用

曾昭槐, 郑超文   

  1. 中山大学化学系
  • 收稿日期:1985-10-08 出版日期:1987-02-24 发布日期:1987-02-24
  • 基金资助:

    中国科学院科学基金

Studies of the Shape-Selective Catalysis of ZSM-5 Zeolites Modified with Alkali Compounds

Zeng Zhaohuai, Zheng Chaowen   

  1. Department of Chemistry, Zhongshan University, Guangzhou
  • Received:1985-10-08 Online:1987-02-24 Published:1987-02-24

摘要: 经碱金属化合物改性的HZSM-5分子筛,能提高甲苯烷基化生成对二甲苯的选择性,降低二甲苯异构化活性。改性后沸石的表面总酸度下降,酸强度减弱,孔结构变化不明显。

Abstract: Toluene was alkylated with methanol to produce xyienes rich in the para iso-mcr over ZSM-5 zeolites modified with alkali compounds by ion-exchang, impregnation, and mechanical mixing. At reaction conditions, the conversion of toluene and para isomer in the xylene product were 33.9% and 79.4% respectively using the zeolite catalyst which was modified by sodium cation exchang followed by rapid impregnation with sodium acetate. The selectivity of p-xylene was also enhanced by poisoning the catalysts with nitrogenous bases. It was observed that the higher the p-xylene selectivity in toluene alkylation with methanol, the lower the catalytic activity in xylene isomerization over the same catalysts. The results of studies on surface properties by TPD, pyridine pulse poisoning, and BETweight methods indicated that the total acidity was decreased, the acid strength was weakened, and the relative sorption capacity of p-xylene vs. m-xylene was enhanced after modifying with alkali compounds.

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