Adsorption and desorption of methyl alcohol on magnesium oxide

Abstract

Methyl alcohol absorbs on MgO to give a coverage of one molecule for each “ion pair” on the surface. Infra-red studies of successive additions of the alcohol indicate the build-up of various alcohol species on the surface which can be characterized mainly by their CO stretching bands and also by the presence of OH and CH bands. Infra-red and gas chromatographic desorption studies in vacuo at room temperature and at elevated temperatures are used to investigate the stability of the adsorbed species. The four major adsorbed species are characterized by CO stretching frequencies at 1030, 1060, 1114 and 1080 cm^–1. This latter species is stable to above 600 K and its disappearance is accompanied by the evolution of alcohol decomposition products. Comparative studies with deuterated alcohols confirm the assignments and indicate that some exchange reactions involving hydrogens of the methyl group occur at elevated temperatures.