Kinetics of the catalytic dehydration of ethanol over alumina

Abstract

The kinetics of the vapour-phase catalytic dehydration of ethanol over alumina have been studied in a static system in the temperature range which favours the formation of ethylene and water. The first-order rate constant, k, for the reaction is given by k= 3 × 10⁸ exp –26,600/RT sec.^–1 for surface coverages, θ, up to 0·8 At catalytic temperatures in the range 334–418° the heat of adsorption and the entropy of adsorption (referred to a standard state of 1 atm.) are shown to be approximately –16·1 kcal. mole^–1 and –19·4 cal. deg.^–1 mole^–1, respectively. It is suggested that the latter value is consistent with a mobile layer of ethanol, and an estimate of the partition function of the activated complex of about 10⁹ at 360° also implies that anchorage of ethanol molecules at fixed surface sites is not required for the dehydration reaction.