Preparation And Catalytic Oxidation Of Toluene/Propane Over CuO Micro-Nano Structure

With the rapid development of economy in recent decades,the environmental problems have gradually become prominent in China.Volatile organic compounds(VOCs)is an important part of atmospheric pollutants,which seriously threaten the normal growth of humans,animals and plants.Toluene,a common organic substance with aromatic odor,can be found almost everywhere in various construction facilities and daily necessities.However,toluene is toxic and carcinogenic.Propane,a typical light hydrocarbon emission,is often used as an alternative fuel for traditional gasoline or diesel.But its structure is stable,high content,and volatile,which is not conducive to remove.Toluene and propane contribute significantly to the formation potential of VOCs and ozone,thus,the removal of toluene and propane has always been an important challenge in environmental treatment.The catalytic oxidation method not only has the advantages of simple operation,low energy consumption,and few by-products,but also can effectively convert various VOCs pollutants such as toluene/propane into non-toxic carbon dioxide and water,so it has been extensively studied by scientific researchers.Transition metal catalysts are good substitutes for precious metals due to their low price and abundant reserves.Copper oxide-based catalysts,one of transition metal catalysts,have the advantages of environmental friendliness and high redox potential,so they are widely used in the removal of various VOCs.In summary,the copper oxide-based catalyst is a potential high-efficiency catalyst for the removal of toluene and propane.Based on this,we prepared copper oxide catalysts with different micro-nano structures,adjusted the morphology,oxygen vacancy content and other factors.These catalysts were used to study the catalytic performance and explored the reaction mechanism of toluene and propane.XRD and SEM showed that we successfully prepared copper oxide catalysts with different morphologies:CuO-nanosheet,CuO-nanoball and CuO-nanorod.TEM showed that different morphologies of copper oxide expose different crystal faces.XPS and EPR stated that CuO-nanosheet had the highest content of Cu+and oxygen vacancies,followed by CuO-nanoball and CuO-nanorod.H2-TPR and O2-TPD clarified that CuO-nanosheet had the best low-temperature reducibility,the most adsorbed oxygen species and the best lattice oxygen mobility.The activity data of toluene or propane showed that the toluene or propane activity of copper oxide with different morphologies was quite different.The prepared copper oxide samples are all more active than commercial copper oxide.Copper oxide nanosheet has the best catalytic activity for toluene(T50=203℃,T90=238℃)and propane(T50=328℃,T80=352℃).The activity data showed that more oxygen vacancy content and Cu+,better low-temperature reducibility,and better lattice oxygen mobility are the key factors for the catalysis of copper oxide with different morphologies to toluene and propane.In situ DRIFTS showed that the catalytic oxidation of toluene and propane maybe both proceeded by the MvK mechanism.In summary,we have successfully prepared copper oxide samples with different micro-nano structures and studied their performance in the catalytic oxidation of toluene and propane.This provides new ideas for the development of simple and efficient nonprecious metal catalysts for the removal of VOCs.