Efficient conversion of glycerol to aromatics over stable nanosized x-ZF/ZM-y catalysts using ZIF-8 as a template

A series of novel nanosized x-ZF/ZM-y zeolites for glycerol to aromatics (GTA) were synthesized by using ZIF-8 as a template. The crystallization time and ZIF-8 dosage were systematically studied to clarify the crystallization process, structural characteristics and physicochemical properties of the prepared x-ZF/ZM-y. The results indicated that the growth of x-ZF/ZM-y zeolites involved two stages: attachment-impregnation and crystallization. The addition of ZIF-8 could introduce the active Zn species (ZnOH + ) and induce the formation of smaller HZSM-5 nanocrystals in x-ZF/ZM-y, which could effectively facilitate the dehydrogenation-aromatization and aldol condensation steps in GTA and enhance the coke resistance. Furthermore, the ZIF-8 dosage had important influences on the catalytic performances of x-ZF/ZM-y. In particular, the 0.45-ZF/ZM-48 with 0.45 g ZIF-8 dosage and 48 h crystallization time all existed as nanocrystals of 20–40 nm, and possessed a proper redistribution of acid sites, resulting in 59.5% total aromatics yield and 11 h catalyst lifetime over 0.45-ZF/ZM-48 owing to the synergistic effect among the ZnOH + , inter-crystalline mesopores and HZSM-5 nanocrystals. The best 0.45-ZF/ZM-48 catalyst showed excellent catalytic activity (59.5% aromatics yield) as well as high catalytic stability (11 h lifetime) in GTA reaction for the synergistic effect among active Zn species (ZnOH + ), inter-crystalline mesopores and HZSM-5 nanocrystals. • Nanosized x-ZF/ZM-y with active Zn, HZSM-5 nanocrystals and inter-crystalline mesopore were synthesized by addition of ZIF-8. • The introduced Zn species remarkably promote the catalytic activity of x-ZF/ZM-y in GTA reaction. • The smaller HZSM-5 nanocrystals and the inter-crystalline mesopores significantly enhance catalytic stability of x-ZF/ZM-y. • The crystallization time and ZIF-8 dosage had vital influences on the properties and catalytic performances of x-ZF/ZM-y. • The 0.45-ZF/ZM-48 shows superior performances for synergism among ZnOH + , inter-crystalline mesopores and HZSM-5 nanocrystals.