Improved performance of hierarchical porous Mo/H-IM-5 catalyst in methane non-oxidative aromatization

摘要

Two novel hierarchical porous IM-5-S and IM-5-M materials were synthesized using mesoporous silica SBA-15 and MCM-48 as the silica sources, and for comparison conventional IM-5-C zeolite was also synthesized with the same synthesis composition. IM-5-S and IM-5-M samples exhibited larger crystal sizes and different textural properties than the conventional IM-5-C zeolite. Moreover, Mo-modified catalysts, Mo-IM-5-S, Mo-IM-5-M, and Mo-IM-5-C, were prepared for the non-oxidative aromatization of methane. The physical properties and acidities of the samples were characterized by XRD, SEM, TEM, BET, and NH3-TPD. Compared with Mo-IM-5-C, the Mo-IM-5-S and Mo-IM-5-M catalysts showed higher yields of aromatics and better stabilities. The preferable catalytic behaviors of Mo-modified mesoporous IM-5 catalysts may be attributed to the generation of secondary mesoporous systems within the zeolite crystals, which may influence the location and state of the active Mo species, simultaneously lead to easier access to the active sites for reactants and be favorable for the diffusion of products formed in the microporous channels during the methane aromatization reaction.