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

Abstract 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, 29 Si 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 × 300 × 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.