Zn-based metal-organic frameworks as sacrificial agents for the synthesis of Zn/ZSM-5 catalysts and their applications in the aromatization of methanol

摘要

Zn/ZSM-5 was prepared by using a combinative method of steam-assisted crystallization (SAC) and hard templating. Zn-based MOFs, including coordination polymer of Oslo number 1-Zn (CPO-1-Zn) and zeolitic imidazolate framework-8 (ZIF-8), were used as the sacrificial agents. These MOFs-derived catalysts were compared with Zn/ZSM-5 made by impregnation. Physicochemical characterization revealed that all Zn/ZSM-5 catalysts had finely dispersed Zn2+ species, i.e., ZnO and Zn(OH)(+). However, the concentration of Lewis acidic Zn2+ species and the compositions of Zn(OH)(+) and ZnO were different. Applying ZIF-8 as the sacrificial agent generated a higher concentration of Lewis acidic Zn2+ species and a higher ratio of Zn(OH)(+)-to-ZnO in Zn/ZSM-5, which showed a better performance in the aromatization of methanol.