Diquaternary Ammonium Compounds in Zeolite Synthesis: Cyclic and Polycyclic N-Heterocycles Connected by Methylene Chains

Abstract

An additional dimension has been added to our long-standing studies in high silica zeolite synthesis via a guest/host synergism. We have created and studied the impact of making symmetric diquaternary ammonium compounds, by varying the chain length between nitrogen charge centers, and the heterocycle size and geometry containing the nitrogen. This allows the introduction of a second spatial parameter in the use of the charged organo-cation guest in the zeolite synthesis. The series of 15 diquaternary ammonium compounds (5 heterocycles synthesized onto chain lengths of C4−C6) were tested in a total of 135 zeolite syntheses reactions. Nine screening reactions were employed for each guest molecule, and the conditions built upon past successes in finding novel high silica zeolites via introduction of boron, aluminum, or germanium as substituting tetrahedral framework atoms for silicon. Eighteen different zeolite structures emerged from the studies. The use of specific chain lengths for derivatives of the pyrrolidine ring system produced novel zeolite materials SSZ-74 and 75.

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