Organosilane-Assisted Synthesis of Hierarchical Porous ZSM-5 Zeolite as a Durable Catalyst for Light-Olefins Production from Chloromethane

Hierarchical porous ZSM-5 (HP-ZSM-5) zeolites with both micro- and mesoporosity were synthesized by an organosilane-assisted method. Their catalytic activities were evaluated in the transformation of chloromethane into light-olefins (CMTO). The synthesized HP-ZSM-5 zeolites were characterized by X-ray diffraction, Ar-sorption, scanning electron microscopy, NH 3 -temperature programmed desorption, 27 Al NMR, Py-IR, and uptake experiments of ethylene. The organosilane treatment had a significant effect on the microstructure, pore chemistry, and catalytic performance of HP-ZSM-5. Compared with that of the microporous ZSM-5, the abundant mesopore and appropriate acidity of HP-ZSM-5 samples are in favor of the inhibition of secondary reactions in the CMTO process, such as hydrogen-transfer and aromatization. The selectivity of light-olefins reached 68.1% and the lifetime (the duration of chloromethane conversion > 98%) was up to 72 h, which is 4.5 times longer than that of the conventional ZSM-5.