Pure-silica ZSM-22 zeolite rapidly synthesized by novel ionic liquid-directed dry-gel conversion

Abstract

Shortening the crystallization process of zeolites is significant for their applications because of the energy savings. Here, we report a rapid synthetic route for pure-silica ZSM-22 zeolite with TON topology. The synthesis was achieved by dry-gel conversion, where the dry gel was prepared under an unusual acidic condition for hydrolyzing the silica precursor with 1,3-alkylimidazolium ionic liquid as the structure-directing agent (SDA). Highly crystallized pure-silica ZSM-22 can be synthesized within 2 days of crystallization, dramatically shorter than 10% of the conventional hydrothermal strategy. Using a similar procedure, Al-containing ZSM-22 can also be synthesized by simply adding aluminum salt in the initial gel. In addition, understanding of the structure-directing role of ionic liquids is attempted through characterizations of IR, TG, ¹H and ¹³C NMR spectra.