Chemical Modification of HZSM-5 for Selective Methylation

Abstract

Commercial HZSM-5 was modified by treating with phosphoric acid and boric acid for the selective methylation of benzene. The study of the performance with respect to the selectivity of the major products, toluene and xylene is the interest of the work. Catalysts were characterized based on BET surface area and XRD, SEM and NH3-TPD analysis to observe the change in properties due to their modification. Although benzene conversion is the highest with HZSM-5 catalyst, but in terms of selectivity, BZSM-5 and PZSM-5 are found to be the suitable catalyst for toluene and xylenes respectively. Xylene selectivity declines for HZSM-5 with the increase in temperature where as the PZSM-5 and BZSM-5 show slightly increasing tendency.