MECHANISM OF THE GAS-PHASE ISOMERIZATION OF DIHALOBENZENES OVER ZEOLITE-BETA

被引：28

作者：

PARDILLOS, J ^{[1
]}

BRUNEL, D ^{[1
]}

COQ, B ^{[1
]}

MASSIANI, P ^{[1
]}

DEMENORVAL, LC ^{[1
]}

FIGUERAS, F ^{[1
]}

机构：

[1] ECOLE NATL SUPER CHIM,CHIM ORGAN PHYS & CINET CHIM APPL LAB,CNRS,URA 418,8 RUE ECOLE NORMALE,F-34075 MONTPELLIER 2,FRANCE

来源：

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY | 1990年 / 112卷 / 04期

关键词：

D O I：

10.1021/ja00160a002

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

The mechanism of the gas-phase isomerization of dihalobenzenes has been investigated over a wide pore zeolite β. A Langmuir-Hinshelwood rate law is obeyed, showing reaction in the adsorbed phase. Most of the products are formed according to a consecutive reaction scheme, as found in the homogeneous phase, with a small participation of a direct ortho ⥨ para conversion. The electronic effect of substituents on the aromatic ring suggests a protonated intermediate, the isomerization of which is the rate-determining step. The influence of the acidity of the zeolite was studied by changing the Al content of the solid: the rate of isomerization goes through a maximum in function with the Al content, as expected for an acidic mechanism, but the rate of deactivation is not correlated with the Al content. The study of the adsorption of dichlorobenzene by CP-MAS-NMR and by FT-IR spectrometry confirms the existence of a protonated species, formed by interaction with the more acidic protons of the zeolite. Free radicals are detected by ESR upon adsorption of dichlorobenzene on the acidic zeolite. The participation of these radicals in the catalytic process could account for the particularities of the gas-phase reaction compared to liquid-phase catalysis. © 1993, IEEE. All rights reserved. © 1990, American Chemical Society. All rights reserved.

引用

页码：1313 / 1318

页数：6

共 28 条

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