A facile hydrolysis-controllable strategy for fast synthesis of Ti-MWW with steam-environment crystallization method

Numerous strategies have been developing to synthesis the Ti-MWW zeolites, but more effective synthesis process is still a significant challenge. In our study, with the synergy of PI and IPA (Isopropyl Alcohol) , the Ti-MWW zeolites with adjustable active sites were directly developed by titanium-silicon composite with homodisperse titanium species in the continuous circulation of SDA steam. The Ti-MWW achieved were flaky nanocrystal Ti-MWW with the size of 20–400 nm, and the mesopores with ca. 20 nm pore size and 0.76 cm3 g−1 total pore volumes were simultaneously created, and the crystallization period was decreased to 2 days for a comparison with 7–14 days required in conventional method. Furthermore, the catalytic tests showed that Ti-MWW exhibit a higher activity almost 7 times than Ti-MWW prepared by conventional dry–gel method in the liquid-phase epoxidation of 1-hexene with hydrogen peroxide due to the improved accessibility of the active sites inside the crystals and the number of active sites. The physicochemical properties were analyzed by XRD, SEM, BET, UV–Vis, FT-IR, ICP et al., and the mechanism for incorporation of titanium species into framework have been investigated in details. This facile and efficient synthetic strategy would considerably facilitate the preparation of zeolites with high catalytic performance in industrial production on a large-scale in the future.