Construction of Ti-containing zeolite with highly enhanced catalytic activity by active species surface implanting strategy

Herein, highly efficient Ti-containing zeolite catalyst (Ti/Al-HSZ) has been prepared by an active catalysis species surface implanting strategy (ACS-SIS) through the combination of precedent acid treatment and subsequent recrystallization. Compared with commercial titanosilicate zeolite catalysts and Ti-HSZ catalyst synthesized by one-step method, Ti/Al-HSZ-c-3.5d-AT catalyst presents highly enhanced catalytic activity and turnover number values in the epoxidation of linear and cycloalkenes by using 30% H₂O₂ as oxygen agent under mild reaction conditions. Particularly for the conversion of bulky linear alkene and cycloalkene (1-dodecene and cycloheptene), the catalytic activity of Ti/Al-HSZ-4M‐3.5d‐AT can attained more than three times than that over Ti-HSZ-3.5d-AT. Based on systematical comparison and analysis, on one hand, the excellent catalytic performance of Ti/Al-HSZ is ascribed to its unique hollownest morphology that acts as ideal reaction space by providing with plenty of hierarchical porous structure and high external surface, which is beneficial for the diffusion and mass transfer of bulky substrate. On the other hand, the high content of active open Ti species locating on the surface of catalyst is particularly beneficial for the formation of transition state to accelerate the epoxidation reaction. Not only the Ti source utilization rate but also the Ti_open incorporated rate of Ti/Al-HSZ-4M‐3.5d‐AT prepared by ACS-SIS is much higher than that of Ti-HSZ prepared by one-step hydrothermal synthesis route. The effects of acid treatment and recrystallization on the zeolite framework, morphology, chemical composition, and Ti coordination states have been thoroughly discussed. The ACS-SIS is believed to be an effective route to construct excellent solid heterogeneous catalyst to meet the urgent need of green chemistry for sustainable development.