Decomposition of ethyl alcohol vapour on aluminas

Abstract

The vapour-phase decomposition of ethyl alcohol has been examined from 120 to 460° on catalytic aluminas, mainly with the α- and γ-phase structures. Between 120 and 240° the main products of decomposition on γ-alumina were diethyl ether and water vapour, E_A= 14·2 ± 0·2 kcal, mole^–1, while from 260 to 370° these were ethylene and water vapour, E_A= 11·0 ± 0·2 kcal. mole.^–1. Partial pressures of ethyl alcohol from 1 to 45 mm. were used, and the effects of water vapour and ethylene additions studied. On α-alumina from 360 to 460° dehydrogenation as well as dehydration products were formed, E_A= 11·2 ± 0·2 to 12·8 ± 0·2 kcal. mole^–1 depending on the condition of the catalyst with respect to the amount of carbon deposited during the reaction. The effect of heat treatment on γ-alumina from 360 to 1100° has been examined and shown to have a marked effect on the nature of the reaction products for samples heated above 800°. Catalyst activity per unit area at 360° increased as the heat-treatment temperature was raised from 900 to 1000 and then to 1100°. The increase was due to the intervention of reactions producing acetaldehyde and diethyl ether, since the amount of alcohol reacting to ethylene remained substantially constant for each sample. The physical properties of most catalysts were determined by X-ray, nitrogen adsorption, and lump density methods.