Preparation Of Supported TiO₂ Photocatalyst By Molecular Sieves Of KIT-6 And Its Photocatalysis Properites Research

This paper studied the TiO2/KIT-6,the preparation and characterzation of Fe doped TiO2/KIT-6 composite catalysts. Benzaldehyde was synthesized by photocatalytic oxidation of benzyl alcohol using TiO2/KIT-6 as catalyst.Ordered mesoporous silica (KIT-6) as support, nanosized TiO2 into KIT-6 can improve the surface of TiO2 and increase the contct area between catalysts and reactants, so as to achieve the purpose of rapid degradation. Fe-TiO2/KIT-6 doped metal element improving catalytic activity from two aspect, on the one hand, carriers were provided by using doping so as to prevent the composite of electronic and cavities thus photocatalytic activity can be improved. On the other hang, ordered mesoporous silica can improve the photocatalytic activity by increase the contact area between catalysts and reactants.Firstly, TiO2/KIT-6 composites with various titania content and various roasting temperature were prepared via the sol-gel method. TiO2/KIT-6 composites were characterized by X-ray diffraction(XRD),N2 adsorption, TEM,FT-IR. The results showed that the titania crystalline phase was anatase. The BET surface area and pore volume of the composites decreased with the increase of titania content. The average crystal size of these titania particles increased as the titania content increased. The photocatalytic activities of TiO2/KIT-6 composites which were different TiO2 loading and repeated usage were studied by the photocatalytic degradation of Rhodamine B. The degradation of Rhodamine B followed first-order reaction kinetics. The 30% TiO2/KIT-6 which was baked under 550℃had the best degradation effect, the best degeneration rate of Rhodamine B is 94.5% under optimal conditions:adding 0.01g TiO2/KIT-6 composites into 70 mL of the 20 mg/L Rhodamine B which reacted for 25 min.Secondly, a series of Fe-TiO2/KIT-6 composite photocatalysts with different concentration were prepared by deposition precipitation method. The catalysts were characterized by XRD and N2 adsorption. The photocatalytic activity experiment about Rhodimin B which was used as probe molecule were carried out. The results showed that, the photocatalytic activity to Rhodamine B is first increase then decrease with the increase of the admixture of Fe. When the molar fraction of Fe is 1.0%(relative to TiO2/KIT-6), The catalyst Fe-TiO2/KIT-6 has the best photocatalytic activity, the best degeneration rate of Rhodamine B is 97.6% under optimal conditions:adding 0.01g TiO2/KIT-6 catalysts into 90 mL of the 20 mg/L Rhodamine B which reacted for 25 min.Then, benzyl alcohol was photocatalytic oxidation by different concentration of TiO2/KIT-6 which was used as catalyst. The influence of benzaldehyde yield was inspected from O2 velocity, different solvents, different illumination time to different load of the catalyst. The results showed that, O2 flow for 25mL/min, reaction for 7h, the conversion rate of pure TiO2 in acetonitrile solution is 23.1% and the selectivity of benzaldehyde is 42.8%. While in the same condition, the conversion rate of 40% TiO2/KIT-6 in acetonitrile solution is 43.9% and the selectivity of benzaldehyde is 98.2%. That is to say, the selectivity and the conversion of reactant can be greatly improved when TiO2 load on KIT-6.