Catalysis by polyoxometalates. Part 3.—Influence of vanadium(V) on the thermal stability of 12-metallophosphoric acids from in situ infrared studies
- 1 January 1991
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions
- Vol. 87 (24) , 3913-3920
- https://doi.org/10.1039/ft9918703913
Abstract
The 12-molybdo(tungsto)phosphoric acids, and the related compounds 1-vanado-11-molybdo(tungsto)phosphoric acids, all having the Keggin structure, have been studied at different temperatures in a special infrared cell allowing experiments in a controlled atmosphere. The effects of dehydration and the thermal stability are discussed. The anhydrous acids are evidenced only for the two 12-molybdo- and 12-tungsto-phosphoric acids: for the vanado compounds, the results are in agreement with the release of vanadium from the host Keggin structure, when increasing the temperature and duration of the treatments in a dry atmosphere. The effect of exposure to water vapour after the thermal treatments is also discussed.Keywords
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