FT-IR ASSESSMENT THROUGH PYRIDINE ADSORPTION OF THE SURFACE-ACIDITY OF ALKALI-DOPED MOO3 TIO2

被引:44
作者
MARTIN, C [1 ]
MARTIN, I [1 ]
DELMORAL, C [1 ]
RIVES, V [1 ]
机构
[1] UNIV SALAMANCA,FAC FARM,DEPT QUIM INORGAN,AV CAMPO CHARRO S-N,E-37007 SALAMANCA,SPAIN
关键词
D O I
10.1006/jcat.1994.1079
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
Adsorption of pyridine on MoO3/TiO2 doped with alkali metal cations (Li, Na, K, and Rb) has been studied by FT-IR spectroscopy in order to assess the effect of the nature and concentration of alkali cations on the surface acidity. It has been found that incorporation of the alkali cations leads to a decrease in the surface acidity and of the ratio between the concentration of Bronsted and Lewis surface acid sites. These decreases are due to (i) formation of weak Lewis acid sites (alkali cations) with lower electron affinity than Mo6+ and Ti4+ and (ii) cancellation of Bronsted sites (Mo-OH) because of formation of alkali molybdates. These effects are more pronounced as the alkali content increases and/or the polarizing character of the alkali cation is increased. (C) 1994 Academic Press, Inc.
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页码:415 / 421
页数:7
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