Infrared study of acid–base properties of thorium dioxide
- 1 January 1983
- 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. 79 (9) , 2219-2227
- https://doi.org/10.1039/f19837902219
Abstract
Adsorption of CO2, C5H5N, CH3OCH3 and CD3OCD2H on ThO2 has been studied by Fourier-transform infrared spectroscopy. CO2 adsorption gives rise to several types of species: polydentate carbonates, bidentate carboxylates, bidentate carbonates, hydrogenocarbonates, monodentate carbonates and linear CO2 species. The carbonate species have been identified on the basis of the splitting of the v3 vibration and of thermal-stability considerations. These results show that thorium dioxide is a basic oxide. Considering the va(CO2) mode of linear CO2 species, the v8a mode of pyridine, the v(CH) band of CD3OCD2H and the v(COC) modes of CH3OCH3, it is concluded that some Th4+ ions are very weak Lewis-acid sites. The OH groups giving rise to the 3740 cm–1 band are basic (some are involved in the formation of hydrogenocarbonate species), while some of the OH groups corresponding to the 3655 cm–1 band are very weak proton donors.Keywords
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