Research On The Reaction Kinetics Of NO_x Removal From Automobile Exhaust By Non-thermal Plasma

With the rapid development of the automobile carrying trade in our country, the automobile exhaust has become the main source of air pollution in the cities. It is very urgent to treat the engine exhaust. To both the rare petrol engine and diesel engine, the removal of NOx is very important to exhaust treating because the concentration of NOx in them is very high. Compared with the common catalytic technology at present, non-thermal plasma technology, which is a new kind of technology in the field of exhaust treating, has special advantages when it is used to treat gas pollutant. But at present, there has been no mature theory on the reaction kinetics of NOx removal from the automobile engine by non-thermal plasma. To research its reaction kinetics is just the purpose of this paper.Firstly, the theoretic basis of non-thermal plasma was synthetically analyzed in this paper. On the base of comparing the characteristics of plasma caused by different kinds of gas discharge, the dielectric barrier discharge (DBD) plasma technology was applied in the research. The common character of DBD , the physical and chemical process of DBD were introduced in detail. Secondly, the treating of two kinds of simulated exhaust consisting of N₂ /NO and N₂ /O₂ / NO respectively by non-thermal plasma was studied via experiment. The influence of the discharge voltage, the resident time of the simulated exhaust in the DBD reactor and the initial concentration of NO were detected in the course of NOx removal. Then the possible reaction approaches of NOx removal from automobile exhaust by non-thermal plasma were analyzed, from which the main reactions in the two kinds of simulated exhaust were selected. The kinetics model was set up, in which the kinetics figure was consistent with the experiment data. Thus the reaction mechanism can be proved to be reasonable. The reaction kinetics of the rest main composition in the two kinds of simulated exhaust was forecasted by the kinetics model. And it was found that the injection of O₂ was unfavorable to NO_x removal.