The Synthesis Of CuO-CeO₂ Catalysts Via Flame Spray Pyrolysis For The Catalytic Combustion Of C₃H₆

Volatile organic compounds（VOCs）,as one of the main air pollutants,do great harm to the environment.Therefore,effective and practical VOCs governance technology has been widely concerned by researchers.Catalytic combustion technology is a highly efficient,low energy consumption end treatment technology,which can handle with wide range of VOCs.The development of high performance,low cost and continuously stable catalysts is the core research focus in the field of catalytic combustion.Transition metal oxides are more competitive than precious metal catalysts due to their excellent performance and cost advantages.In this paper,CuO-CeO₂ composite oxides were synthesized as catalysts,and the catalytic activity was evaluated by C₃H₆ catalytic combustion experiments.Based on the flame spray pyrolysis（FSP）method,the preparation method was improved and the preparation parameters were optimized to improve the catalytic activity of CuO-CeO₂ composite oxides catalysts.The relationship among the preparation parameters,microstructure and catalytic activity of the material was established with careful characterization techniques.Based on the FSP method,various CuO-CeO₂ composite oxide catalysts were prepared by changing the molar ratio of Cu in metallic precursors.The effect of the molar ratio of Cu on the physical structure,surface chemistry,reduction properties and the C₃H₆ catalytic combustion activity of catalyst was systematically studied.Results show that CuO-CeO₂ solid solution oxides with good structure can be synthesized by the FSP method,which can promote the catalytic activity of catalysts at low temperature.In a certain range,increasing the proportion of Cu increases the content of CuO-CeO₂ solid solution in catalysts and improves the catalytic performance of catalysts.Excessive Cu loading produces independent CuO grains,weakens the synergistic effect of CuO and CeO₂,and reduces the catalytic activity of the CuO-CeO₂ catalyst.In this paper,the optimal Cu loading content of the FSP method is 35 mol%,which is better than other preparation methods in the same study（less than 25 mol%）.At different temperature intervals of C₃H₆ catalytic reaction process,different active components in the catalysts play a leading role respectively.Various CuO-CeO₂ composite oxide catalysts were prepared under different molar concentration of metallic precursors in the precursor solution by the FSP method.The effect of the concentration of metallic precursor on the physical structure,surface chemistry,reduction properties and C₃H₆ catalytic combustion activity of the catalyst was systematically studied.Results show that the concentration of metallic precursor affects the content of CuO-CeO₂ solid solution oxides in catalysts and the catalytic performance of catalysts at low temperature.In a certain range,increasing the concentration of metallic precursors promotes the formation of CuO-CeO₂ solid solution oxides.Meanwhile,the catalyst structure is also optimized to obtain larger specific surface area and smaller grain size.Once the concentration is too high,it starts to show negative effect on the microstructure and surface chemical state,and reduce the catalytic activity of the material.In this paper,the optimal concentration of metallic precursors for the FSP method is 0.20 mol·L^-1.The excellent C₃H₆ catalytic activity of the CuO-CeO₂ composite oxides catalyst is due to the synergistic effect of active components and microstructure.In the catalytic process of C₃H₆,the influence of reaction conditions on the catalytic performance of the catalyst was studied by changing the concentration of O₂and C₃H₆ respectively.O₂ and C₃H₆ have a competitive adsorption relationship on the surface of the CuO-CeO₂ composite oxides catalyst.Increasing the O₂ concentration will reduce the C₃H₆ catalytic combustion activity.In the 600 min catalytic reaction process,the CuO-CeO₂ composite oxides catalyst maintains excellent catalytic activity,and the amorphous CuO group on the material surface crystallizes to form independent CuO grains.600 min catalytic reaction has impact on physical structure and surface chemistry.The lattice oxygen component of the material increases,the content of hydroxyl oxygen decreases,and the surface absorbed oxygen almost remains unchanged.The specific surface area decreases and the grain size increases.The recycling and regeneration of waste catalysts were innovatively explored through the FSP method.The regenerated catalysts also obtained CuO-CeO₂ solid solution oxide components and high catalytic performance.