(475e) Direct Synthesis of Mesoporous ZSM-5 Zeolite Single-Crystals

ZSM-5 zeolite with MFI framework is used as catalysts for several reactions carried out in chemical industry. Decreasing zeolite crystal size and introducing mesoporosity into the zeolite structure can improve its performance in catalytic reaction through decreasing the micropore diffusion path-length and increasing the external surface area. In this study, three different ZSM-5 zeolites were prepared by single templating procedure, and the reaction of methanol to gasoline-range hydrocarbons  and hexane cracking were evaluated over synthesized ZSM-5 crystals in a fixed-bed continuous flow reactor. Good correlation was observed between catalytic performance, product distribution, mesoporosity, and crystal size of ZSM-5 zeolites. Both nanocrystal and mesoporous ZSM-5 zeolites showed long-term catalytic stability compared with the conventional one. The nanocrystal and mesoporous ZSM-5 catalysts showed high selectivities for light olefins and alkyl aromatics, respectively, in the conversion of methanol to hydrocarbon. In addition, it is found that the selectivity to light olefin increases by decreasing the number of acid sites on the external surface.