Zeolite synthesis in the presence of flexible diquaternary alkylammonium ions (C 2H 5) 3N +(CH 2) nN +(C 2H 5) 3 with n=3–10 as structure-directing agents

Abstract

The use of flexible diquaternary alkylammonium ions (C 2H 5) 3N +(CH 2) n N +(C 2H 5) 3 (Et 6-diquat- n with n=3–10) as structure-directing agents for zeolite synthesis in the presence of alkali metal cation is described. Among the organic structure-directing agents studied here, a considerable diversity in the phase selectivity was observed only for the Et 6-diquat-5 ion: this cation can produce five different zeolite structures (i.e., P1, SSZ-16, SUZ-4, ZSM-57, and mordenite), depending on the oxide composition of synthesis mixtures. Analysis of the variable-temperature 1H CRAMPS NMR spectra obtained from the Et 6-diquat-5 molecules in these five zeolites reveals that the host–guest interactions occurring within the respective materials maintain in a manner different from one another even at 160 °C at which the zeolite hosts crystallize.