The Thermo-photocatalysis Properties Of Pt-La₂O₃/TiO₂Catalyst

With the development of global economy, people pay more attention on ecological environment and energy, what urgent needs to solve the environment pollution and energy shortage is to achieve sustainable development, improve the people’s living and guarantee the national security. TiO2photocatalyst which remove organic pollutants of liquid and gas phase has made a lot of progress in the environmental protection field. Photocatalysis is a very promising technology for environment pollution deep purification.Due to the limitation of photocatalysis technology, catalytic oxidation technology do not come true industrialized scale application in wastewater treatment filed. When photocatalyst utilize sunlight, the light from sun not only provides ultraviolet and visible light, but also offers infrared which can lead to improvement of catalyst temperature. Using high strength sources and long time to illuminate cause improvement of local temperature, which can improve remove effect.The rare earth metal doping can the scope of spectrum of TiO2response and improve the utilization rate of the sun light. The precious metal which can catalytic oxidation CO and VOCs pollutants at low temperature has very big development prospect. Combining rare earth doped TiO2with precious mental, no doubt that is great progress of environment deep purification.In this paper, Using TBOT and lanthanum nitrate as raw material, TiO2was prepared by using sol-gel method. On this basis, using hexachloroplatinic acid hexahydrate as raw material, Pt-La2O3/TiO2photocatalyst was prepared by photoreducction. XRD、SEM、DRS、TEM、 GC-MS、EDS and N2adsorption isotherm were used to characterize the obtained photocatalyst.Doped Pt made the average particle size of La2O3-TiO2smaller and the surface area bigger so that the property of visible light absorption was enhanced and the photocatalytic activity was improved. Under UV, Pt-La2O3/TiO2photocatalyst that had the highest photocatalytic activity was prepared by using8ml solution of hexachloroplatinic acid hexahydrate. Under Vis, Pt-La2O3/TiO2photocatalyst that had the highest photocatalytic activity was prepared by using7ml solution of hexachloroplatinic acid hexahydrate. The time of photoreduction and sacrificial agent(methanol) concentration had great influence on the size of doped Pt and the particle size of Pt had directly impact on photocatalytic activity. The existence form of doped Pt on TiO2surface was mainly affected by photodeposition time.Doped Pt had two main forms on La2O3/TiO2surface. One kind was Pt elemental and another was Pt oxide. The time of photoreduction that more than120min had not any effect on Pt elemental generation and Pt oxide was main product. Active order is Pt0/TiO2>PtOX/TiO2 >TiO2. The generation of Pt elemental availed the improvement of photocatalytic activity, in addition Pt elemental which could change the reaction path was a hot catalyst.Improving reaction temperature could effectively improve the property of catalysts(Pt、 La2O3-TiO2、Pt-La2O3/TiO2) on the toluene removal rate and catalytic reaction rate. Thermocatalytic was not obvious at low temperature. when temperature reached180℃, thermocatalytic activity increased quickly. Hot catalytic activity kept high activity even at high temperature. Pt-La2O3/TiO2had higher catalytic activity than Pt and La2O3/TiO2on the degradation rate of gas toluene at different temperature. Photo-thermocatalytic was not simply sum of photocatalytic and thermocatalytic.