A case study of divergent structure directing effects of geometric isomers: the discovery of a new structure directing agent for an all-silica RTH zeolite prepared in fluoride media

Abstract

This report describes experimental work that is a follow-up to predictions presented in a previous study on the zeolite SSZ-73 (SAS). In that study we observed trace amounts of RTH phases in some of our preparations of SSZ-73. We hypothesized that the RTH phase could be due to a geometric isomer of the polycyclic structure directing agent (SDA) used to prepare SSZ-73. In this work we have performed detailed NMR analyses that confirm the presumed isomeric structure of the molecule used in the preparation of SSZ-73. We have then used an alternate procedure to prepare an SDA that is enriched (66–75%) in the geometric isomer believed to be responsible for the RTH-type phase. Syntheses with this SDA in fluoride media give an RTH zeolite as the major product. Solid-state NMR of the RTH products indicates the isomers are occluded in the final product in approximately the same ratio that they are present in the synthesis preparation.