The Influence of Silica to Alumina Ratio on Y Zeolite Activity by Simultaneous TG and DSC Analysis

Abstract

Simultaneous TG and DSC analyses of n-butylamine adsorption/desorption were carried out over several zeolites with different degrees of dealumination. The samples used consisted of high crystalline zeolites, preparedvia steam/leaching sequential treatments, and characterized by various techniques. Catalyticactivity measured as the initial rate of cracking of 1,3,5-triisopropylbenzene did not correlate with total acidity, however, the energy required to the complete desorption of the probe molecule, determined by integration of DSC curves, correlates with the catalytic activity of zeolites with any or little extra-framework alumina content. High amounts of extra-framework alumina give significant constraint effect to acessibility to acid sites as shown by applying the Crank's method to the TG curves. This method allowed to determine the intra-crystalline diffusivity of the probe molecule, which seems to be the controlling step to the cracking reaction.