Dealumination of Zeolite BEA under Microwave Irradiation

An efficient, quicker, milder, and easier method for controlled dealumination of zeolite BEA. using an aqueous solution of toluene-4-sulfonic acid under microwave irradiation is reported. The effect of various parameters like concentration of toluene-4-sulfonic acid solution, reaction time, and temperature on the extent of dealumination was investigated Dealumination with microwave heating was found to be much more effective and faster than with conventional thermal heating. Aluminum removed from the framework of the zeolite was readily extracted and estimated by back titration method. BEA zeolite samples before and after dealumination were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Al-27 MAS NMR, Temperature Programmed Desorption of ammonia, low temperature nitrogen adsorption, and Brunauer-Emmett-Teller (BET) surface area. To understand the relationship between acidity and activity of parent and dealuminated zeolites, the esterification of p-cresol with phenylacetic acid has been studied under Microwave irradiation. BEA dealuminated with 0.1 M solution of toluene-4-sulfonic acid for just 2 min under microwave heating showed highest activity for the said esterification.