A TPD and IR study of the surface species formed from ammonia on zeolite H-ZSM-5, H-mordenite and H-beta

被引：95

作者：

Lónyi, F ^{[1
]}

Valyon, J ^{[1
]}

机构：

[1] Hungarian Acad Sci, Inst Chem, Chem Res Ctr, H-1525 Budapest, Hungary

来源：

THERMOCHIMICA ACTA | 2001年 / 373卷 / 01期

基金：

匈牙利科学研究基金会;

关键词：

zeolite acidity; acidity of H-beta; adsorption of NH3; TPD and IR spectra;

D O I：

10.1016/S0040-6031(01)00458-0

中图分类号：

O414.1 [热力学];

学科分类号：

摘要：

Ammonia was found to react with the Bronsted acid sites of H-zeolites forming NH4+ ions, coordinate to Lewis acid sites and, at higher coverage, to NH4+ ions forming protonated ammonia associations, such as, NH4+(NH3)(n). Besides the Lewis acid NH4+ ions, one kind of strong Lewis acid site was detected in zeolite H-ZSM-5 and H-mordenite, while strong and weak Lewis acid sites were substantiated to exist in zeolite H-beta. The strong acid Lewis sites were assigned to extra-framework alumina (EFA1) species generated by the partial dehydroxylation of the H-zeolites. The weak Lewis acid sites of H-beta were tentatively ascribed to framework Al atoms coordinatively unsaturated due to framework defects. (C) 2001 Elsevier Science B.V. All rights reserved.

引用

页码：53 / 57

页数：5

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