Nano-crystalline, hierarchical zeolite Ti-Beta: Hydrothermal synthesis and catalytic performance in alkenes epoxidation reactions

Aluminum-free hierarchical Ti-beta was hydrothermally synthesized from a basic precursor using tetraethyl ammonium hydroxide and sodium fluorine as the structure directing agent and mineralization agent, respectively. The physicochemical properties are analyzed by XRD, TEM, UV-Vis, Si-29 NMR et al. The catalytic activity was evaluated via the epoxidation of cyclohexene and 1-oectene. The Ti-beta achieved are plate-like nano-crystals with crystal size of about 100 x 300 x 300 nm. More importantly, intracrystalline mesopores in the 10-40 nm range were simultaneously created, and most of the titanium could be isomorphously substituted into the zeolite matrix. The Ti-beta is defects-free, the thermal stability is excellent. Due to the improved accessibility of the active sites inside the crystals, the activity increased by more than 30% compared with the conventional Ti-beta formed from the HF-procedure.