DBD Plasma Combined With Cu/γ-Al₂O₃ To Selectively Catalyze Carbonyl Sulfide

The rapid economic growth is inseparable from the rapid development of the chemical industry.During the development of the chemical industry,the treatment of industrial exhaust has become a problem that cannot be ignored in industrial production.Industrial exhaust gas contains a variety of toxic and harmful gases.These gases have different physical and chemical properties,so the difficulty of treatment is also different.Carbonyl sulfide（COS）gas is an impurity that exists in many industrial exhaust gases.Because of its low reactivity and long life,it is more difficult to remove than other sulfur-containing gases.Its existence affects the quality of industrially produced products,and also causes serious damage to the environment and harms human health.In the traditional COS removal technology,there are problems such as secondary pollution and unstable treatment.Therefore,it is particularly important to find a COS purification technology with high efficiency and no secondary pollution.In this paper,dielectric barrier discharge is used in conjunction with Cu/γ-Al₂O₃catalytic technology to degrade COS gas.The removal effect of COS was mainly investigated by three systems of dielectric barrier discharge alone,Cu/γ-Al₂O₃thermal catalysis,and dielectric barrier discharge combined with Cu/γ-Al₂O₃catalyst.In addition,different inlet concentrations,gas flow rates,humidity,The influence of oxygen concentration on the conversion of COS with the cooperation of the Cu/γ-Al₂O₃catalyst with dielectric barrier discharge.The gas composition changes before and after the reaction were analyzed,and the difference between the Cu/γ-Al₂O₃catalyst before and after the reaction was analyzed by various characterization methods,and the mechanism of the degradation of COS by the cooperation of the dielectric barrier discharge with Cu/γ-Al₂O₃was discussed by combining the optical fiber spectrogram and DFT calculation.After experiment and research,the following results and conclusions are obtained:COS generates H₂S,SO₂,CO,and CO₂under the action of a single dielectric barrier discharge,and generates a yellowish-brown solid with the main component of S and a small amount of（SN）₄on the reaction tube and electrode.When using Cu/γ-Al₂O₃thermal catalyst to treat COS,although the removal rate can reach 97.5%when the temperature is increased to250℃,970 ppm of H₂S will be generated.The 5 wt%Cu/γ-Al₂O₃catalyst and the dielectric barrier discharge have the best effect in the treatment of COS.The removal efficiency of98.9%is achieved at 16 k V,and there is no generation of H₂S and SO₂in the gas products.In addition,adding a catalyst to the dielectric barrier discharge plasma can also reduce energy consumption.The removal rate of COS decreases with the increase of inlet concentration,gas flow rate,humidity and oxygen concentration.In experiments of different oxygen concentrations,it is found that the dielectric barrier discharge combined with Cu/γ-Al₂O₃catalyst can inhibit the formation of O₃.A fiber optic spectrometer was used to capture the spectrum during the reaction,and Gaussian software was used to simulate and calculate the reaction barrier of the reaction path under the action of an electric field.It is found that in the composite system of dielectric barrier discharge combined with Cu/γ-Al₂O₃,a low energy barrier cyclic reaction is established between Cu S,Cu₂S and COS,which is the key to the absence of H₂S and SO₂during the reaction..