Ammonia-regulated dynamic evolution of Ti precursor incorporating into dealuminized beta for efficient 1-Hexene epoxidation

Demetalation-metalation method has gained prominence for its higher metal loading, efficiency and shortened synthetic period, particularly in the incorporation of metal atoms with large radii into zeolite framework in recent years. An ammonia-regulated approach has been developed for selectively evolved deep-substituted Ti precursors in dealuminized beta zeolites, which enables a controlled promotion of metalation of Ti atoms. Additionally, this ammonia-regulated approach could also enhance 1-hexene kinetic adsorption by constructing mesopores, which is demonstrated by the lower reaction order of 1-hexene. The synthesized ammonia-regulated N-Ti-beta exhibits rich framework Ti species and a high specific surface area, leading to significantly improved 1-hexene epoxidation performance (conversion of 61%, selectivity of 98%, and a high H2O2 utilization efficiency of 93%). This study not only provides a new strategy to dynamically regulate evolution of Ti precursors by ammonia but also holds promise for advancing related industrial processes in demetalation-metalation methods.