A Cooperative OSDA Blueprint for Highly Siliceous Faujasite Zeolite Catalysts with Enhanced Acidity Accessibility

Abstract A cooperative OSDA strategy is demonstrated, leading to novel high‐silica FAU zeolites with a large potential for disruptive acid catalysis. In bottom‐up synthesis, the symbiosis of choline ion (Ch + ) and 15‐crown‐5 (CE) was evidenced, in a form of full occupation of the sodalite (sod) cages with the trans Ch + conformer, induced by the CE presence. CE itself occupied the supercages along with additional gauche Ch + , but in synthesis without CE, no trans was found. The cooperation, and thus the fraction of trans Ch + , was closely related to the Si/Al ratio, a key measure for FAU stability and acidity. As such, a bottom‐up handle for lowering the Al‐content of FAU and tuning its acid site distribution is shown. A mechanistic study demonstrated that forming sod cages with trans Ch + is key to the nucleation of high‐silica FAU zeolites. The materials showed superior performances to commercial FAU zeolites and those synthesized without cooperation, in the catalytic degradation of polyethylene.