ACIDIC PROPERTIES OF OXIDES CONTAINING NIOBIA ON SILICA AND NIOBIA IN SILICA

被引：60

作者：

BURKE, PA ^{[1
]}

KO, EI ^{[1
]}

机构：

[1] CARNEGIE MELLON UNIV,DEPT CHEM ENGN,PITTSBURGH,PA 15213

来源：

JOURNAL OF CATALYSIS | 1991年 / 129卷 / 01期

关键词：

D O I：

10.1016/0021-9517(91)90007-Q

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：

A series of composite oxides containing niobia (Nb2O5) and silica (SiO2) was prepared by either incipient wetness impregnation to form surface phase oxides or by coprecipitation to form mixed oxides. At low Nb2O5 concentrations, both the surface phase and mixed oxides showed strong Lewis acidity as determined by thermogravimetric and infrared studies of adsorbed pyridine. A surface phase oxide containing 0.25 monolayer of Nb2O5 on SiO2 further showed strong Brønsted acidity. With increasing Nb2O5 concentration and/or treatment temperature, Nb2O5 in these composite oxides became more bulk-like and showed a corresponding decrease in acid strength. These acidic properties are discussed in terms of proposed structural models which contain tetrahedral niobia, octahedral niobia, and Nb0 bonds as basic building blocks. © 1991.

引用

页码：38 / 46

页数：9

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