The Research Of Saw-plate Pulse Corona Discharge Combined With Catalyst Removal Nitrogen Oxides

More and more people paying attention to the atmospheric environment.As one of the main gaseous pollution elements,nitrogen oxide?NO_x?causes harm not only to human health,but also to the environment.Much more attention has been paid to its management.Non-thermal plasma technology,combined with catalytic technology removing the nitrogen oxides,has been widely studied because of its simple process,high efficiency and low energy consumption.It is very promising to improve the process on removal of nitrogen oxides under the condition of oxygen enrichment;therefore,further research is needed.In this paper,the main nitrogen oxides NO was treated as the treatment object by using the saw-plate pulsed corona discharge reactor.First,the structure of the reactor was optimized;on this base,the influence of the electrical parameters and gas parameters on nitrogen oxide removal was analyzed.Then the experiments on NO_x removal were carried out by combining catalytic.Using 5A molecular sieve as catalyst carrier,we analyzed of the load of different active materials?Cr,Cu,Mn,Fe?and doped rare earth elements Ce on the catalytic activity.The catalysts were characterized by SEM and XRD,to determine the optimal amount of load.Finally,analysis of the impact of adding different reducing agent?CH4,C2H2?and different concentration on the removal of nitrogen oxide were conducted.Experiments show that the homogenous corona discharge can be produced in a saw plate pulsed corona discharge plasma reactor,and it is not easy to produce spark discharge at higher voltage with good discharge stability.When the number of saws is 4,the saw plate spacing is 2cm,saw saw spacing is 2cm,the sawtooth spacing is 6mm,pulse corona discharge plasma can be considered to have high energy and large volume.Increasing the pulse voltage is helpful to improve the conversion rate of NO and the removal rate of NO_x,promoting NO oxidation to NO₂,pulse repetition frequency reaches 80 Hz,the removal efficiency was the best.With the increase of O₂ concentration,the conversion rate of NO and the removal rate of NO_x decreased gradually,and then stabilized.The existence of O₂ interfered the NO reduction process.The addition of the H2 O can produce more active free radicals H,OH and HO₂,and improve removal rate.8%Fe/ molecular sieve catalyst had the best effect.The conversion rate of NO reached 46.3%,and the removal rate of NO_x was up to 32.8%;activity of Fe/ molecular sieve catalyst increased with the addition of rare earth element Ce.The conversion rate of NO and NO_x removal rate of 3%Ce-Fe/ zeolite catalyst were 49.7% and 37.3% respectively.The addition of reducing agent can improve the removal rate of NO_x by pulsed discharge plasma cooperating with Ce-Fe/ molecular sieve catalyst.The higher the concentration of reducing agent,the better the effect.The effect of C2H2 is better than CH4.When C2H2 was added to 1000 ppm,the conversion rate of NO was increased to 57.4%,and the removal rate of NO_x was improved to 43.6%.