ESR characterization of V4+ as a counter-ion of the 12-molybdophosphate. Influence of thermal treatments

被引：52

作者：

Bayer, R ^{[1
]}

Marchal, C ^{[1
]}

Liu, FX ^{[1
]}

Teze, A ^{[1
]}

Herve, G ^{[1
]}

机构：

[1] UNIV VERSAILLES,LAB ELECTROCHIM & CHIM SOLIDES INORGAN,EP CNRS 67,F-78035 VERSAILLES,FRANCE

来源：

JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL | 1996年 / 110卷 / 02期

关键词：

polpoxometalates; molybdophosphate; vanadium; ESR;

D O I：

10.1016/1381-1169(96)00064-7

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：

Vanadyl cations were introduced as counter-ions of the 12-molybdophosphate Keggin anion and crystals of [VO(H2O)(5)]H[PMo12O40]. 23H(2)O were obtained. Dehydration under nitrogen of this hydrate occurs step by step which were studied by thermogravimetry and ESR characterization of vanadium after thermal treatment. Vanadyl exists as an aquo complex [VO(H2O)(5)](2+) up to 75 degrees C. Between 75 and 210 degrees C, loss of the water molecules leads to VO2+ becoming bound to the outer oxygen atoms of the molybdophosphate. All these transformations are readily reversible in the presence of water. At 320 degrees C, a progressive decomposition of the Keggin structure occurs, characterized by a decrease of the intensity of the ESR signal of V4+ and the emergence of a signal of Mo5+. This transformation is only partly reversible in the presence of water vapor.

引用

页码：65 / 76

页数：12

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