Use of flexible diquaternary structure-directing agents in zeolite synthesis: Discovery of zeolites TNU-9 and TNU-10 and their catalytic properties

Abstract

This review summarizes our recent work on zeolite syntheses in the presence of linear diquaternary alkylammonium ions, with the object of controlling the conformations of these flexible, hydrophilic organic structure-directing agents by varying the type and concentration of inorganic components in synthesis mixtures. After describing how we have been concerned about the search for novel zeolite structures through this synthetic strategy, we discuss the cooperative structure-directing effects of 1,4-bis(N-methylpyrrolidinium)butane and specific levels of Na+ ions and lattice negative charges introduced by Al substitution on the crystallization of new medium-pore zeolites TNU-9 and TNU-10. The physicochemical and catalytic properties of these two materials are also outlined.