Synthesis of Al-enriched beta zeolite nanocrystals by using DABCO di-cationic quaternary ammonium as organic structure directing agent

Abstract

Al-enriched Beta zeolite nanocrystals with densely populated acid sites and enhanced mass transfer efficiency have been demonstrated to show promising catalytic performance. In this work, low Si/Al ratio (8–9) Beta nanocrystals (about 20 nm) was synthesized by using DABCO based di-cationic quaternary ammonium salts as organic structure directing agent with high solid yield (＞95 %). The hydrothermal synthesis process was followed by monitoring the intermediate products at different time intervals, through which the key role of the di-cationic quaternary ammonium for the formation of Beta nuclei was identified. The promising catalytic performance of the Al-rich Beta nanocrystals in 1,3,5-triisopropylbenzene transalkylation with benzene was attributed to the high density and enhanced accessibility of acid sites.