Functional Carbonaceous Materials Combined With Photocatalysis/Thermal Catalysis For VOCs Removal Obtained Via Sol-Gel Method

With the developing of economics and society, indoor air pollution caused by VOCs (Volatile organic compounds) has caused widespread concern. Most indoor volatile organic compounds are toxic. Worldwide environment organizationss have confirmed that indoor air quality is an important factor that affecting human health., which includes formaldehyde, benzene, toluene, alcohols, ketones, chlorinated organics, mainly from paint, solvents, preservatives, deodorants and disinfectants. More than 20 species can damage or cause directly on human cancer, such as formaldehyde, benzene and benzene and other organic peroxides.At present, TiO2 Photocatalysis have made great progress in the field of water and gas phase and was considered as a promising environmental purification technology. At the same time absorbent material is widely applied, such as activated carbon. Considering both the advantages and shortcomings of photocatlysis and adsorption, combining them together for a high efficient composites will be a promising technologies. in recent years, the thermal catalytic of noble metal has been caused widely concern, which can destroy VOCs at low temperature and is very potential, combining adsorption, photocatalytic and thermal catalytic is great new idea for controlling indoor air quality.In this paper, rare earth La doped TiO2 catalyst were synthesized by sol-gel, toluene oxidation was reacted in self-designed device, studying the influence of noble metals doped and reaction temperature on the toluene photocatalytic degradation. Composite materials were characterized by SEM, XRD and XPS.GC-MS was used to analyze composite materials on the toluene place types and distribution of intermediate products. The following are the results:1. La doped TiO2 photocatalyst were prepared by sol-gel method. The activity of the photocatalyst was investigated through degradation of Toluene under artificial visible light. X-ray Photoelectron Spectroscopy(XPS), Uv-vis Diffuse Reflectance Spectra(DRS), X-ray Diffraction analysis(XRD), Scanning Electron Microscope(SEM) and N2 adsorption isotherm were used for catalyst characterization. The results showed that La doped TiO2 exhibited significant improvement of visible light activity. La doping could improve dispersion of TiO2, inhibit particle size agglomeration and retard phase transformation. Doped La can extend the light response of TiO2 to visible light region. Inaddition, narrower band gap formed by La-doping was beneficial to the high visible light photocatalytic activity.2. Pt deposited on the catalyst surface existed in the style of adsorbed oxygen and simple substance. As Pt deposition through light Pt-La2O3/TiO2 prepared composite catalyst, hydroxyl groups OH-stretching on the catalyst surface vibration significantly increased. Pt incorporation did not change phase structure of TiO2, Pt incorporation decreases grain size and increase the catalyst surface area. Pt uniformly distributed on the surface of nano-Pt La2O3/TiO2 and agglomeration did not happened, size distribution of catalyst were uniform, about 5nm-10nm. Pt can make catalyst absorb more visible light. Pt-La2O3/TiO2 performed much higher visible light photocatalytic activity than La2O3/TiO2 and TiO2.3. Through the results of toluene degradation In the different systems (LaTiO2, Pt/LaTiO2, Pt/LaTiO2/VACF), We can find ACF loading can make Pt/LaTiO2/ACF adsorbed much toluene compared to the others, Pt/LaTiO2/ACF can degraded the initial concentration of 13872.3 mg/m3 of toluene within 60min. Combining adsorption, photocatalytic and thermal catalytic can greatly enhance the catalyst activity. Degradation intermediates contents and species were different in the degradation process by TiO2/ACF and Pt/La0.28TiO2/ACF. As TiO2/ACF, nine species intermediates products existed, concluding alcohols, ethers, phenols, acids, ketones, etc, the same small amount of long-chain alkanes, intermediate species in broad, high content. Pt/La0.28Ti02/ACF has eitht intermediate products, all of them were long-chain alkanes, we can find that benzene ring can be opened completely in the toluene degradation process, Pt/La0.28TiO2/ACF performed higher catalytic activity compared to TiO2/ACF.