Electron spin resonance studies of free and supported 12-heteropoly acids. Part 4.—The reduction of H3+n(PVnMo12–nO40)·xH2O and the influence of supports on their properties
- 1 January 1986
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases
- Vol. 82 (11) , 3491-3499
- https://doi.org/10.1039/f19868203491
Abstract
The reduction of PVnMo12–n heteropoly acids (HPA) with n= 1–3 has been studied, and a sequence of V4+ e.s.r. signals obtained is described. The main signal is a single symmetric line of 150–300 G width originating from interacting metal atoms. Although the vanadium ion is much more easily reduced, at high reduction temperatures an Mo5+ signal originating from the destroyed Keggin anion is additionally observed. The destruction of the Keggin anion structure is increased when loading the HPA on a support, which simultaneously improves the conditions for the formation of O– 2 oxygen radicals. On alumina the typical properties of HPA were shown to change, as observed by e.s.r. spectroscopy.Keywords
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