| The rapid growth of automobile exhaust emissions have become a major source of air pollution.Three-way thermo-catalytic converter is the most effective vehicle exhaust removal technology.How to develop a new type of three-way catalyst and improve the catalytic efficiency is both the pressure under such circumstances and the goal of researchers always pursue.Photocatalysis becomes more concerned due to its mild reaction conditions,low energy consumption,high reaction efficiency and less pollution secondary,but its low processing capacity make it unable to substitute for automobile exhaust catalytic with thermal treatment.This paper introduced the UV-irradiation to TiO2 and TiO2 modified three-way catalysts loading with Pt into thermal catalytic reaction system in order to facilitate the interaction between TiO2 carrier and active components under UV irradiation and increase the performance.Specific tasks will be undertaken as follows:Pt/TiO2 and Pt/CeO2-TiO2 catalysts were prepared and photo-thermal synergy properties investigated under UV irradiation catalyst in probes reaction of CO+NO,CO+O2 and C3H6+O2,characterized the chemical reactions of gas adsorption behaviors on both the catalyst surface under UV irradiation,studied three catalytic reaction mechanism under UV light over Pt/TiO2 and Pt/CeO2-TiO2 combined with the catalyst crystal structure,surface area,morphology,and surface chemical state of light absorption.In this paper,the following main results and conclusions were obtained:(1)Compared with the Pt/TiO2,Pt/CeO2-TiO2 exhibited higher catalytic activity in reaction of CO+NO,CO+O2 and C3H6+O2 reaction system;(2)UV irradiation can both increase catalytic activity,catalytic activity,stability and the selective reduction of NO to N2 of these three reactions over Pt/TiO2 and Pt/CeO2-TiO2 catalysts,showing good photo-thermal synergies;(3)Pt/CeO2-TiO2 catalyst showed higher activity than Pt/TiO2 under UV irradiation.Based on the XPS,FT-IR and EPR results,it is proposed that the photo-generated electrons of TiO2 excited by UV irradiation transfer to the Pt surface,resulting in the increase of the surface electron density of Pt sites,which promotes to the adsorption and activation of CO,NO,C3H6 on Pt sites,and then the proceeding of the three reactions.The introduction of CeO2 not only benefits to the dispersion of Pt nanoparticles on support and the increase in the surface area of catalyst,but also facilitates the TiO2 photo-generated electrons migrate to Pt surface induced by the process of oxygen storage and release oxygen in CeO2,maintaining a high electron density of Pt catalyst system(metal state),and further enhance the activity.In a word,the photo-generated electrons of TiO2 semiconductor support can act as an electronic additive to be applied to the three-way thermo-catalytic reaction system over TiO2-based catalysts.This viewpoint can provide a new research ideaand approach for automobile exhaust removal techniques. |
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