The sorption of acetaldehyde on silica gels

Abstract

Isothermal studies of the adsorption of acetaldehyde on silica gel have been carried out from 21 to 51°. From these data, isosteric heats of adsorption were determined from θ= 0·1 to 1·0 Over this range, q_st varies from 10 to 16 kcal. mole^–1. On γ-alumina and aluminium-impregnated silica gel, crotonaldehyde is formed on acetaldehyde adsorption at 21°. The degree of conversion into crotonaldehyde on silica gel at 190° is shown to depend on the pretreatment temperature, up to 1000°, and aluminium content of the gel. Infrared spectra of the adsorption at 21° of acetaldehyde on ‘disced’ silica gel and also of the ether extract after adsorption on silica gel powder have been determined. Aldol was detected in the extract. It is believed that the condensation reactions which give aldol and then crotonaldehyde take place in pores after the adsorption of a complete monolayer. Within the monolayer acetaldehyde is probably bound to silica gel by hydrogen bonds.