Abstract
Compared to the conventional Zeolite Beta (Beta-C), hierarchically porous zeolite Beta (Beta-MS) was gained with the diffusion length in zeolite channels down to several nanometers. When it was used as a catalyst for the conversion of methanol to hydrocarbons (MTH), Beta-MS exhibited a remarkably longer lifetime in comparison to Beta-C. At conversions ranging from 20% to 100%, Beta-MS gave higher selectivity toward higher aliphatics (C4−C7) but lower ethene selectivity in comparison to Beta-C (ACS Catal. 2015, 5, 5837). In further, we also synthesized hierarchical ZSM-5 zeolites, with different diffusion length (controlled by the different mesoporosity). The hierarchical ZSM-5 with much more mesopores showed a shorter diffusion length than the one with less mesopores. And as a result, they showed different selectivity of products in the conversion of methanol to hydrocarbons. Therefore, we conclude that a hierarchical structure with short diffusion length could decreases the residence time of methylbenzenes in zeolite micropores, and disfavor the products from the aromatics cycle in the catalytic mechanism of MTH.