Infrared study of the adsorption of ethyl acetate on silica immersed in carbon tetrachloride

Abstract

The adsorption of ethyl acetate onto silica immersed in carbon tetrachloride has been studied by infrared spectroscopy. For silica which had been preheated at 863 K adsorption involved the formation of hydrogen bonds between isolated surface silanol groups and the oxygen atoms of carbonyl groups in ethyl acetate molecules. For silica preheated at 453 K the existence of other types of hydroxyl group on the oxide surface did not affect the adsorption of ethyl acetate onto isolated silanol group sites. However, a second mode of adsorption involved the formation of hydrogen bonds between pairs of adjacent hydroxyl groups and single ethyl acetate molecules. The adsorption of ethyl acetate onto pair sites constituted a stronger mode of adsorption than that involving single silanol groups and was particularly significant at low surface coverages.