Preparation of modified ZSM-5 catalyst with high performance for shape-selective alkylation of toluene with methanol

Abstract

A metal and nonmetal composite-modified catalyst was prepared by immersion method of extrusion molding article of HZSM-5 molecular sieve with different amount of pore-forming agent. XRD and MIP had been used to characterize the structure of synthesized catalyst. The shape-selective alkylation of toluene with methanol catalyzed by the catalysts was investigated in a continuous flow fixed-bed reactor. The experimental results showed that the modified HZSM-5 catalysts with high amount of pore forming agent had good performances. Under the optimized reaction conditions of temperature 540℃, WHSV 2 h−1, n (methanol): n (toluene)=1:2 and n (toluene+methanol): n (H2O): n (H2)=1:1.3:4, the toluene conversion and the selectivity to p -xylene still were 28%~34% and 92%~96% respectively during the 1200 h online reaction. The performance of the used catalyst almost recovered after in-situ regeneration, and were characterized by means of N2 adsorption, TG-DTG, NH3-TPD, Raman, UV-Vis and NMR.