Control of Hierarchical Structure and Framework-Al Distribution of ZSM-5 via Adjusting Crystallization Temperature and Their Effects on Methanol Conversion

Incorporating mesoporosity into zeolite catalysts has been regarded as an innovative technology that improves diffusivity and catalytic lifetime. Here, we propose a facile synthesis of the hierarchically structured ZSM-5with accompanying intracrystalline mesopores, which was achieved by controlling the growth rate of the zeolite nanocrystals without using extra additives. As the crystallization temperature is strongly related to the formation of primary nanocrystals and their further growth, which fills gaps between those nanocrystals, the hierarchically structured ZSM-5zeolite was synthesized at low crystallization temperatures (<140 °C). 27Al MAS NMR and UV-vis-DRS analyses revealed that the hierarchically structured ZSM-5prepared in the present study contained Al located in the straight channel at a higher proportion than the conventional microporous ZSM-5. The substitution of Al was calculated to be more difficult at the channel intersection than at other T-sites, supporting the experimental result...