Research On Efficient Catalytic Oxidation Of Ester VOCs At Room Temperature

Volatile organic compounds?VOCs?of esters are a class of the main atmospheric pollutants,which are mainly derived from the production process of petrochemical industry,pharmaceutical industry,synthetic leather industry and other industries.The emissions of VOCs not only seriously affect the ecological environment,but also directly and seriously harm human health.Therefore,the treatment of VOCs of esters is imminent.The development of safe and energy-efficient catalytic oxidation of VOCs technology at room temperature is of forward-looking and practical significance.Ethyl acetate is a representative VOC of esters,which was selected as a probe molecule in this paper.The activated carbon fiber?ACF?was uesd as the carrier,which was pretreated with 10%H₂SO₄ by single factor optimization.The catalytic ozonation properties of ethyl acetate by Au,Ag,Pt and Pd loaded on ACF were investigated and Pd/ACF was screened out as the best catalyst.Pd/ACF catalyst was prepared by impregnation method.The degradation performance of catalytic ozonated ethyl acetate with different palladium loading rates of 0.1wt%,0.5wt%,1wt%and 4wt%were investigated.The results showed that when the load rate was 1wt%,the catalytic ozonation performance reached the maximum,and the conversion rate of ethyl acetate was 60%.The morphology,structure,valence state and composition of the catalysts were characterized by BET,pore size analysis,X ray diffraction analysis?XRD?,scanning electron microscopy?SEM?and energy spectrum analysis?EDS?,X ray photoelectron spectroscopy?XPS?and fourier transform infrared spectroscopy?FTIR?.The results show that the specific surface area of the catalyst decreases with the increase of the load rate.The average pore size of the ACF didn't change greatly,which means that the precious metal was mainly distributed on the surface of ACF and almost had no influence on the micropores.The surface elements in the catalyst are mainly C and O,and there are a small amount of N,P and Pd elements.The valence state of the Pd loaded on the ACF is mainly+4.The effects of operating conditions such as reaction temperature,space velocity,concentration ratio of ethyl acetate and ozone on the degradation efficiency of ethyl acetate were discussed.The appropriate reaction conditions of catalytic ozonation of ethyl acetate with Pd/ACF:temperature from 30 to 50?,feed space velocity15000-30000 h^-1,ozone and ethyl acetate concentration ratio of 3:1.Kinetic simulation of catalytic ozonation of ethyl acetate with power law model was carried out and activation energy was 113 kJ/mol.The Pd-based ACF catalysts with large specific surface area,well-developed pore structure and abundant functional groups on the surface can be applied in the field of VOCs treatment at room temperature,which will have broad application value.