INSOLUBLE HETEROPOLY COMPOUNDS AS HIGHLY-ACTIVE CATALYSTS FOR LIQUID-PHASE REACTIONS

被引：300

作者：

OKUHARA, T

NISHIMURA, T

WATANABE, H

MISONO, M

机构：

[1] Department of Synthetic Chemistry, Faculty of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo

来源：

JOURNAL OF MOLECULAR CATALYSIS | 1992年 / 74卷 / 1-3期

关键词：

D O I：

10.1016/0304-5102(92)80242-9

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

Liquid-phase alkylation of m-xylene or trimethylbenzene with cyclohexene was studied using heteropoly compounds and other typical solid acids as the catalysts; the results are discussed in relation to the surface properties of the catalysts. Cs2.5H0.5PW12O40 (abbreviated as Cs2.5-salt) was remarkably more active than H3PW12O40, zeolites, Nafion-H, SO42-/ZrO2, H2SO4, and AlCl3-HCl. Solid-state P-31 NMR revealed that Cs2.5-salt mainly consists of polyanions with one proton (Cs2HPW12O40) and those without a proton (Cs3PW12O40). The quantity of acid sites of Cs2.5-salt was determined to be 161-mu-mol g-1 by temperature-programmed desorption (TPD) of NH3, which was much greater than the estimated quantity of surface acid sites of H3PW12O40, and less than that of zeolites and SO42-/ZrO2. The acid strength of Cs2.5-salt measured by Hammett indicators and TPD of NH3 was smaller than that of SO42-/ZrO2. It is presumed that the high activity of Cs2.5-salt is brought about by its large number of surface acid sites and its acid-base bifunctional nature, in which a caesium ion possibly increases the basicity of the heteropoly anion.

引用

页码：247 / 256

页数：10

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