Carbon Nanotubes Supported Transition Metal Oxide Catalysts For Catalytic Oxidation Of Ethyl Acetate

Ethyl acetate is a low-toxic volatile organic compound.As a substitute for traditional benzene-based industrial solvents,it has developed rapidly and is widely used in various manufacturing industries.The excessive emissions of ethyl acetate will cause serious harm to the quality of the ecological environment and human health.To achieve the goal of removing ethyl acetate with high efficiency,a series of carbon nanotubes（CNTs）supported transition metal oxide catalysts were prepared.Their performance for the catalytic oxidation of ethyl acetate was deeply studied.The supported transition metal oxide catalysts were prepared by impregnation and evaporation methods using CNTs as the support.Cobalt oxide exhibits higher catalytic activity than manganese and cerium oxide catalysts.The results of optimizing the catalyst loading show that 10Co/CNTs is the optimal catalyst.To improve the catalytic activity of10Co/CNTs,three composite oxide catalysts were prepared,namely 6Co-4Ce/CNTs,6Co-4Mn/CNTs and 3Co-7Mn/CNTs.The experimental results of ethyl acetate oxidation showed that 3Co-7Mn/CNTs displayed the better performance than 10Co/CNTs catalyst.3Co-7Mn/CNTs can completely remove 100 ppm ethyl acetate(100000 m L·g^-1·h^-1)and obtain 96%CO₂ selectivity at 195°C with good catalytic stability.The addition of manganese improved the interaction of metal oxides in 3Co-7Mn/CNTs,which was beneficial to the dispersion of metal oxides.3Co-7Mn/CNTs has rich Co³⁺,Mn³⁺and surface active oxygen species,which are conducive to the catalytic oxidation of ethyl acetate.In order to further improve the interaction between support and oxides in the catalysts,CNTs supported Mn O₂ catalyst in-situ（Mn O₂-CNTs）were prepared.The loading of Mn O₂will affect the morphology,pore structure and thermal stability of Mn O₂-CNTs.When the loading is too high,a large amount of Mn O₂ will cover the surface structure of CNTs.It made the catalyst mainly exhibit the properties of Mn O₂,which reduced the catalytic activity of ethyl acetate oxidation.4Mn O₂-CNTs has the optimal loading of Mn O₂,which can achieve100%removal of ethyl acetate and 99%CO₂ selectivity at 160°C.After 50 h of continuous reaction,there is no significant change in catalytic performance.Compared with activated carbon-based catalysts,the support properties of CNTs are favorable for the oxidation of ethyl acetate.4Mn O₂-CNTs has good thermal stability,and Mn O₂ has the strong interaction with CNTs.These increase the relative concentration of Mn³⁺and surface active oxygen species in the catalyst,and promote the catalytic activity of ethyl acetate oxidation.