Electrical conductivity of γ-Al2O3 at atmospheric pressure under dehydrating/hydrating conditions

被引：50

作者：

Caldararu, M ^{[1
]}

Postole, G ^{[1
]}

Hornoiu, C ^{[1
]}

Bratan, V ^{[1
]}

Dragan, M ^{[1
]}

Ionescu, NI ^{[1
]}

机构：

[1] Romanian Acad, Inst Chem Phys IG Murgulescu, Bucharest 77208 12, Romania

来源：

APPLIED SURFACE SCIENCE | 2001年 / 181卷 / 3-4期

关键词：

AC electrical conductivity; gamma-Al2O3; protonic conduction; water adsorption;

D O I：

10.1016/S0169-4332(01)00393-2

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：

Changes of electrical conductance and capacity of gamma -Al2O3 were studied in situ during dehydration/rehydration in gas flow. The measurements were performed at atmospheric pressure by following a standard protocol of experiments, and were coupled with simultaneous monitoring of the composition of the inlet/effluent gas. The electrical properties are dominated by the protonic conduction. It was shown that at low temperature this occurs by vehicle mechanism, being facilitated by the presence of water molecule adsorbed on gamma -Al2O3 surface; the decrease of electrical conductance on heating is obviously connected with dehydration. At higher temperature (t > 200 degreesC) conduction is dominated by proton hopping between OH groups (Grotthuss mechanism). It is suggested that in current operating conditions in catalysis, gamma -Al2O3 is only partially dehydrated/dehydroxylated, the bulk acting as a source of water/OH groups for the surface; this process controls the acidity of alumina and alumina-supported catalysts. (C) 2001 Elsevier Science B.V. All rights reserved.

引用

页码：255 / 264

页数：10

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