晶种法制备MWW型沸石分子筛用于甲烷脱氢芳构化反应研究OA

Methane dehydroaromatization(MDA)represents a promising non-petroleum route for aromatic production.Exploring the effects of the pore structures of catalysts on their MDA reaction catalytic performances is crucial for developing high-efficiency catalysts.MWW-type zeolites(MCM-56 and MCM-22)were synthesized by seed-assisted method.The phases,morphologies and pore structures of Mo/MCM-56 and Mo/MCM-22 catalysts were characterized by XRD,TEM,SEM,and N2 adsorption/desorption.Furthermore,the effects of different pore channel systems of MWW-type zeolites on catalytic performances of Mo/MCM-56 and Mo/MCM-22 catalysts for MDA reaction were investigated.The results show that the seed-assisted method significantly reduces crystallization time of zeolites,and the structures of MWW zeolites are closely related to the structures of seeds.After reacting for 9.0 h under the same conditions(700℃,100 kPa),Mo/MCM-22 demonstrates higher aromatic selectivity(around 95%)and aromatic yield(around 7.5%),and superior catalytic stability compared to Mo/MCM-56.Therefore,it is speculated that the 12-membered ring supercages,formed through condensation of adjacent two-dimensional MWW zeolite nanosheets in Mo/MCM-22 catalyst,serves as the primary sites for MDA reaction.The study reveals that different pore channel systems of MWW zeolites have significant effects on the catalytic performance of catalysts for MDA reaction,providing new ideas for designing highly selective and stable MDA catalysts.