Rapid synthesis of ZSM-22 zeolites using imidazolium-based ionic liquids as OSDAs in fluoride media

Abstract

Developing facile and rapid synthesis route for zeolites is becoming increasingly desirable due to economical considerations. Here, we report on the one-pot rapid synthesis of ZSM-22 in fluoride media using imidazolium-based ionic liquids as organic structure directing agents (OSDAs). Pure-silica and aluminum-containing ZSM-22 zeolites were rapidly synthesized in 24 h using 1, 3-alkylimidazolium ionic liquids as OSDAs in various crystallization conditions. The crystallization time of present synthesis route surpasses most of the currently reported methods. Different synthesis parameters were investigated and the optimum synthetic conditions were refined. The XRD and SEM results showed that the products were highly crystalline pure ZSM-22 zeolites with a long rod shape. 29Si MAS NMR indicated defect-free zeolite framework was achieved thanks to the using of fluoride as mineralizer. 27Al MAS NMR verified the Al was existed in tetrahedrally coordinated states indicating its successful incorporation into the zeolitic framework. The present work demonstrates a possible and fast synthesis route of ZSM-22 and potential applications will be expected.