Hierarchical Ti-MWW for Efficient Propylene Epoxidation With Cumene Hydroperoxide

Micro-mesoporous Ti-MWW zeolites with a hierarchical structure were synthesized to overcome the diffusion limitations in the epoxidation reaction involving large-molecules. One-pot dissolution-recrystallization process of three-dimensional Ti-MWW constructed bimodal pores and abundant Ti sites on the external surface of Ti-MWW, which were efficient for cumene hydroperoxide-based propylene epoxidation to propylene oxide (PO), achieving a high PO yield as 91%, far superior to the sole 35% performance value afforded by the pristine Ti-MWW catalyst. Poisoning experiments confirm that the reaction predominantly occurs on the external surface. The recrystallization process further increases the fraction of open Ti sites, boosting epoxidation activity. Moreover, the robust zeolite framework endowed superior stability compared to the conventional mesoporous titanosilicate catalysts, remaining high activity under harsh conditions.