Synthesis Of MCM-56 Zeolites And Their Applications On Hydrodealkylation Of Heavy Aromatics

MWW zeolites, with their unique framework topology composing two entirely different micropore systems (two-dimensional 10MR channel and 12 MR pocket), have good catalytic activity in many reactions. MCM-56 zeolites with high crystallinity were obtained by a postsynthesis method with hexamethyleneimine as an influence of gel ingredient and crystallization conditions on synthesis were investigated. And the crystallization time, crystallization temperature, gel ingredient, and stirring speed on the formation of MCM-56 was investigated systematically in the autoclave. The obtained samples were characterized by XRD, XRF, SEM, FT-IR and BET methods. The results showed that MCM-56 samples (SiO2/Al2O3=25-40)can be synthesized with high crystallinity, the zeolite showed thin platelet morphology, which was generally aggregated to particles of 10-15μm.The H-type zeolites were prepared from synthesized zeolites by ion exchange method. The catalysts, which were made up of metal-oxide as the active composition and HMCM-56 zeolite as the carrier, were prepared by impregnation. The influence factors, including various ratio of SiO2/Al2O3 of carriers and loading of active compositon on the catalytic performance were researched. The results showed that the conversion of C2+ and selectivity of BTX can be 59.35% and 87.11% on 3% MoO3/HMCM-56(SiO2/Al2O3=25) which calcined at 540℃with the reaction condition of 460℃,3MPa,3.62h-1 and H2/CH=1600. The MoO3/HMCM-56 catalyst was stable and showed desirable catalytic properties for the hydrodealkylation of heavy aromatics.