The Research On Catalytic Removal Of Toluene By CuO/TiO₂ Composites

As important precursors of haze and ozone pollution,volatile organic compounds（VOCs）have seriously endangered the ecological environment and human health.Therefore,VOCs have become the focus of air pollution prevention and control in China.Toluene,which is one of the most common VOCs,is widely used in life and production,and it is crucial to develop an efficient technology for toluene removal.In order to compensate for the lower efficiency of photocatalysis and the higher energy consumption of thermal catalysis,photothermal catalysis has received more and more attention.In this study,CuO/TiO ₂ composites were successfully synthesized by traditional sol-gel method and liquid-phase precipitation method,and the catalytic performance in toluene removal was investigated.The effects of experimental conditions on the toluene removal pr ocess were also studied.The morphological structure,redox performance,and photo-electronic properties of the catalysts were analyzed.The light-driven photothermal catalytic process,ambient temperature photocatalytic process,and thermal catalytic proc ess were investigated on the optimal sample.In addition,the degradation pathway and reaction mechanism of toluene on the catalyst were studied by in situ DR IFTs.The experimental results showed that the catalytic activity of CuO/TiO ₂ composites obtained by liquid-phase precipitation was better than that of the composites obtained by sol-gel method.The toluene removal efficiency was 80%and the CO₂ yield was 85%under UV-visible illumination on 2Cu2Ti（P）sample which had the best cata lytic activity.Characterization analysis revealed that the CuO/TiO₂ composites had better crystallinity,narrower band gap,stronger absorption ability of light,and lower recombination of photogenerated electron-hole,which prepared by liquid-phase preci pitation.Furthermore,the light intensity and air flow rate play important roles on the removal process.Importantly,the photocatalytic efficiency of 2Cu2Ti（P）was 60%under UV-visible illumination and room temperature,and the efficiency increased to 80%and the temperature increased to 140℃with the assistant of light-driven heat.The removal efficiency increased to 90%and the temperature increased to 180℃under UV-visible-IR illumination.The results revealed that photocatalysis played a dominant role in the light-driven photothermal catalytic process on2Cu2Ti（P）catalyst,and the heat generated by light can promoted the catalytic process and reduced carbo n deposition on the catalyst surface.Under the illumination,O ₂^-radicals played a vital role in photocatalysis,and toluene was oxidized to produce benzyl alcohol,benzaldehyde and benzoic acid,and these intermediates were eventually mineralized by ring opening to CO₂ and H₂O.In this study,composites with superior catalytic performance were successfully prepared using a liquid phase precipitation method.Combined with characterization and mechanistic analysis,it provides a simple and easily controllable strategy for composites and a theoretical basis for degradation of VOCs in practical conditions.