Infra-red study of adsorption of carbon dioxide and water on magnesium oxide

Abstract

The infra-red spectra from 4000 to 750 cm^–1 of various carbonato species adsorbed on magnesium oxide are presented. When CO₂ is adsorbed at temperatures above 300°C a bidentate species is formed. The interaction on the MgO surface of CO₂ with H₂O and D₂O results in the unidentate carbonate species when CO₂ is adsorbed first but a bi-carbonate species HO—CO^–₂ is formed when water is adsorbed first. Correlations have been made of the low-frequency carbonate bands (1200–800 cm^–1) and the carbonate bands in the region 1800–1200 cm^–1. Infra-red absorption bands in the region 1200–800 cm^–1, are better defined when D₂O rather than H₂O is used for the interaction studies.