贵金属负载型核壳结构催化剂的制备及其催化性能

Core-shell structured zeolites with ZSM-5 as core and dendritic SiO ₂ as shell were successfully prepared using cetyltrimetylammonium bromide (CTAB) as surfactant, urea as alkaline source and tetraethyl orthosilicate (TEOS) as silicate source in the microemulsion system composed of cyclohexane and n-pentanol. The effects of the preparation conditions such as temperature, time, addition of urea and TEOS on the preparation of the catalyst were investigated. The zeolites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N ₂ adsorption-desorption. The results indicated that the obtained core-shell structured zeolites exhibited excellent monodispersity, integrity and hydrothermal stability when the preparation temperature was between 100-120, reaction time was 4 h, the molar ratio of urea ℃ to TEOS was 1 and the molar ratio of TEOS to ZSM-5 was 0.9-1.2. Finally, the noble metal Pt was loaded on the dendritic mesoporous SiO ₂ shell and the obtained bifunctional catalysts of Pt/ZSM-5@MS exhibited high catalytic activity and reusability in the one-pot preparation of methyl isobutyl ketone (MIBK) from acetone.