Sulfonic functionalized SBA-15 catalysts in the gas phase glycerol dehydration. Thermal stability and catalyst deactivation

Abstract

The catalytic conversion of glycerol to acrolein was studied using sulfonic functionalized mesoporous silica SBA-15. The catalysts were prepared by the co-condensation method, conducting the silica synthesis and functionalization of its surface with thiol-propyl groups in the same stage. In a next step, the oxidation of thiol groups to sulfonic groups was made varying the concentration of H2O2 in order to obtain catalysts with different levels of acidity on the surface. The solids were characterized by BET, SEM, FTIR, XPS, and potentiometric titration with n-butilamine. The thermal stability was analyzed by thermogravimetry (TGA) and temperature-programmed desorption (TPD). The reaction tests were performed at different temperatures between 275 °C and 350 °C, and under feed flow conditions that allowed the study of the deactivation phenomena by coke deposition. The best temperature in order to maximize the acrolein yield was 300 °C. Higher temperatures led to a rapid deactivation by a combined effect of coke deposition and decomposition of functional groups.