Characterization of acid activated montmorillonite and vermiculite clays by thermal desorption and differential scanning calorimetric techniques

Abstract

Montmorillonite and vermiculite clays, activated with hydrochloric acid solutions of different concentrations, have been characterized by thermal desorption and differential scanning calorimetric (DSC) techniques using ammonia and pyridine as probe molecules. The amount of adsorbed ammonia is found to be about twice the amount of pyridine on all the samples as determined by thermal desorption studies. DSC studies reveal the heterogeneity of acidic sites on the activated catalysts. DSC thermograms show the existence of three distinct acidic sites with different strength on the surface of the catalysts.