Effects of acid concentrations and acid treatment time on structural and textural characteristics of mesoporous zeolite 13X

Abstract

Mesoporous zeolites containing mesopores with sizes ranging between 2 and 50 nm connected to micropores have gained increasing interests due to their potentials for various applications. Acid treatment has been shown to be a relatively simple method for modifying low-silica zeolite pore structure from micropores to mesopores. In this study, the effects of acid concentration (0.2, 0.3 and 0.4 M HCl) and treatment time (15, 30, 45, 60 and 120 min) on the structural and textural characteristics of commercial zeolite 13X were investigated. The data indicated that the faujasite structure of the zeolite still remained when treated with 0.2 M HCl. In contrast, the acid treatment with 0.3 M HCl and 0.4 M HCl caused the disruption of the crystalline structure. Regarding the treatment time, the faujasite structure of the commercial zeolite still remained when treated with 0.2 M HCl for the treatment time as long as 120 min. In addition, the N2 adsorption isotherms of the zeolite treated with 0.2 M HCl for 15 min and 120 min were not significantly different, indicating that the alteration of the pore size might occur during the first 15 min of the acid treatment. Finally, the results showed that the acid treatment caused the alteration from micropores to mostly small mesopores with the pore sizes of 3–4 nm.