The Preparation Of M-TiO₂/HZSM-5Photocatalysts And Its Photocatalytic Applications

TiO2is a typical photocatalyst, which has been extensively concerned due to its manyadvantages such as high photosensitivity and chemical stability, has become a mostwidely-used photocatalytic material. However, the fine TiO2particles have the tendency ofaggregation. In addition, the bare TiO2generally has very small adsorption capacity towardorganic compounds. These inherent disadvantages make it less efficient in photocatalysis.This paper concerns the effect of ZSM-5zeolitic support’s properties on the preparation andperformance of TiO2/ZSM-5composite photocatalyst. The structural features of thephotocatalysts were investigated by X-ray diffraction(XRD), transmission electronmicroscope(TEM), X-ray photoelectron spectroscopy(XPS), Fourier Transform InfraredSpectroscopy(FTIR), ultraviolet visible diffuse reflection(DRUV-Vis); and the adsorptionand photo-degradation of methyl orange(MO) were studied in the aqueous solution. Resultsshowed that the nanoAu particles were incorporated in TiO2/HZSM-5. The introduction of Auparticles not only maintained the adsorption capacity of photocatalysts, but also promoted thephotodegradation efficiency of MO. The effects of Au content, TiO2content, catalyst amount,pH and calcination temperature were examined and the repeatability of photocatalytic activitywas also tested. The adsorption capacity and photodegradation activity of the samples aremeasured using methyl orange (MO) aqueous solution. Focuses are given to the effect of theadsorption of zeolitic supports toward MO on TiO2photocatalytic activity. The main resultsobtained in this dissertation are as follows: 1. Methyl orange molecules are mainly nitric acid adsorbed on the treated ZSM-5zeolite carrier of the outer surface of the strong acid sites, through acid-treated HZSM-5carrier having a large cation can be combined with the photocatalytic reaction in the valenceband electrons, thereby inhibits electron hole pairs TiO2composite, improved the efficiencyof photocatalytic composite photocatalyst nanoTiO2/ZSM-5, the results showed that TiO2loading is25%, the calcination temperature was500℃, UV irradiation32minutes, theconcentration of Photocatalytic methyl orange solution20mg/L degradation efficiency of88.2%.2．Nano-ZSM-5zeolite carrier due to a greater outer surface and surface acidity bitmore, so nanoTiO2/ZSM-5photocatalyst adsorption amount of methyl orange increases.Adsorption and sustained action using ZSM-5zeolite carrier pore structure of watermolecules can be controlled sol-gel process and improve the catalyst loading and dispersionof TiO2. Prepared Supported TiO2composite photocatalyst for methyl orange has a higherphotocatalytic degradation activity.3．electron-withdrawing effect of Au nanoparticles can effectively suppress electronhole pairs TiO2composite, improved photocatalytic performance composite photocatalyst.UV-visible diffuse reflectance spectra show that the load shortened Au nanoparticle TiO2bandgap energy of the composite photocatalyst Au-TiO2/ZSM-5photocatalytic reaction undervisible light irradiation. Au loading of the catalyst surface was0.32%, the load capacity is25%TiO2calcined at500℃, the ultraviolet light32minutes, the concentration of methylorange photocatalytic degradation efficiency of20mg/L solution is96.6%. Under the sameconditions, the visible light120minutes photocatalytic degradation efficiency is96%.