Kinetic study of the chemisorption of diborane on silica gel: application of the Elovich equation

Abstract

The reaction kinetics of dehydrated silica gel with diborane have been studied. The course of the reaction can be described by the Elovich equation, a logarithmic rate law, according to which the activation energy for chemisorption is dependent on the surface coverage of the hydroxyl groups. The surface reaction fits the induced heterogeneity model. The symmetrical cleavage of the physisorbed diborane requires an average activation energy of 15 KJ mol^–1. The activation energy at zero coverage is linear related to concentration of the free hydroxyl groups. The effect of the porosity of silica gel on the activation energy has been studied.