LaHY分子筛表面酸性与催化活性关联的研究

STUDY ON THE CORRELATION BETWEEN CATALYTIC ACTIVITY AND SURFACE ACIDITY OF LaHY ZEOLITES

本文研究了LaHY分子筛表面酸性的类型、强度及酸量按强度的分布对正庚烷裂解、环己烯转化等催化活性的影响,进行了酸性与活性的关联。并结合在LaHY表面上异丙苯裂解和邻二甲苯异构化的研究,讨论了在酸式催化反应中进行酸性与活性关联的方法,得到了有关LaHY表面酸性及活性表面的概念。

The dependence of the catalytic activity of LaHY for n-heptane cracking and cumene dealkylation as well as cyclohexene conversion on surface acid type, acid strength and acid strength distribution has been studied.By varying the protonic acid Lewis acid ratio and transforming Lewis sites into protonic sites as well as poisoning of LaHY by 2,6-dimethyl-pyridine, it was shown that protonic acid sites are the principal active sites for n-heptane cracking at 350℃.It was also observed that the dependence of activity on acid strength varied from reaction to reaction, for example, the ranges of acid strength(Hammett Ho function) requierd for n-heptane cracking, cumene dealkylation and cyclohexene conversion were Ho≤-8.2, Ho≤-3.0 andHo≤+3.3 respectively. In the case of cyclohexene conversion, almost all the acid sites with Ho≤-3.3 were active, but acid sites of different strength made different contributions to the total catalytic activity. The specific catalytic activities of each acid strength region were determined and the results showed that the specific activity increased with increasing acid strength.