Effect of dehydration of a silica surface on chemisorption of methanol

Abstract

Using IR spectroscopy we investigate the chemisorption of methanol on surfaces of pyrogenous silica with different degrees of dehydration. We show that this dependence has an extremal character with minimum chemisorption of alcohol in silicas that have been thermally evacuated at 200–250°C. The presence of preadsorbed triethylamine molecules on the surface of thermally evacuated silica does not change the general degree of substitution of free silanol groups by methoxyl ones in the presence of TEA does not exceed 50% and also depends on the sequence in which the reagents are admitted.