Preparation Of Co-Zr Bicomponent Catalysts And Catalytic Oxidation Of Toluene By Tussah Silk Assisted Method

It is well known that urbanization and industrialization have resulted in the rapid increasing emissions of volatile organic compounds（VOCs）,which are a major contributor to the formation of secondary pollutants and photochemical smog.Air quality in many parts of the world has fallen dramatically as a result of emissions of pollutants.The emission of these pollutants has led to a large decline in air quality in numerous regions around the world,which has ultimately led to concerns regarding their impact on human health and general well-being.The strategy of catalytic oxidation is considered to be an effective chemical method to remove VOCs pollution in the atmosphere.The development of high performance and low cost non-noble metal oxide catalysts has become a research hotspot.In this work,Co₃O₄-Zr O₂bimetallic oxide catalyst was prepared by direct decomposition method assisted by tussah silk fibroin and hydrothermal method assisted by tussah silk fibroin and urea.Their physicochemical structures and properties were characterized by XRD,SEM,EDS,TEM,XPS and N₂ads-desorption techniques.The evaluation of the catalysts oxidation of toluene was carried out in the presence of abundant oxygen,the mass fraction of toluene of 0.1%,and the space velocity of 20000 m L·g^-1h^-1.The results showed that the temperature of complete conversion of toluene over Co₁Zr₁-c catalyst was the lowest at 315 ^oC.The catalyst was prepared by isomolar Co/Zr assisted decomposition of tussah silkcloth with average molecular weight of 8-12 k Da.The catalyst particles were in regular polyhedral shape and the specific surface area was 136m²·g^-1.However,the temperature of toluene conversion was reduced to 270℃for Co₁Zr₁-HF catalyst prepared by hydrothermal method assisted by urea and silk fiber mixture.The toluene conversion temperatures of Co₁Zr₁-H（urea hydrothermal method）and Co₁Zr₁-F（silk fiber hydrothermal method）catalysts prepared by hydrothermal method with a single auxiliary agent were 310℃and 285℃,respectively.XRD and XPS results show that Co₁Zr₁-HF catalysts are tetragonal Co₃O₄and cubic Zr O₂composite metal oxides,which are rich in adsorbed oxygen(O_ads)species and polyvalent cobalt ions.SEM,EDS and TEM results show that Co₁Zr₁-HF is a spherical particle with developed insect-like pore structure with a certain degree of dispersion.Performance of the best Co₁Zr₁-HF catalyst,specific surface area of 177 m²·g^-1on the surface adsorption oxygen content is the most abundant species,oxygen adsorption and lattice oxygen content as high as 3.19,Co³⁺and Co²⁺species are also found at the same time,the large specific surface area,high adsorption oxygen content,more valence particles coexist,and the interactions among components related to its efficient performance of the conversion of toluene,the stability of the catalyst at the same time also has a certain.