Zeolite Synthesis Using Flexible Diquaternary Alkylammonium Ions (CnH2n+1)2HN+(CH2)5N+H(CnH2n+1)2 with n = 1-5 as Structure-Directing Agents

Abstract

The use of a series of flexible, linear diquaternary alkylammonium ions (CnH2n+1)(2)HN+(CH2)(5)N+H(CnH2n+1)(2) with n = 1-5 as structure-directing agents in zeolite syntheses is described. Among the ammonium ions studied here, the (CH3)(2)HN+(CH2)(5)N+H(CH3)(2) and [(CH3)(2)CH](2)HN+(CH2)(5)N+H-[CH(CH3)(2)](2) ions were found to be new structure-directing agents for the crystallization of levyne and MCM-22, respectively. The overall synthesis results of this study reveal that the phase selectivity of the crystallization can differ according to both the length of the dialkyl substituents on the ammonium ion and the oxide composition of synthesis mixtures. The host-guest interactions in nonasil, ZSM-12, mordenite, and levyne containing (CH3)(2)HN+(CH2)(5)N+H(CH2)(5)N+H(CH3)(2) as a guest molecule are investigated by H-1-C-13 CP MAS NMR and Raman spectroscopies, and Computer modeling studies, and it is shown that the organic guest molecules adopt distinct conformations in order to fit in the pores of each zeolite host.