Barrierenentladung zum Abbau von Schadstoffen in motorischen Verbrennungsabgasen

In order to meet future polutant emission limits for internal combustion engines, plasmachemical methods for exhaust gas treatment are currently taken into consideration world-wide. Especially non-thermal atmospheric pressure gas discharges, such as barrier discharges, point towards possibilities of extending the limits of present catalytic methods. In barrier discharges at atmospheric pressure and at slightly raised ambient temperature oxidative and reductive radicals are produced by high energy electron collisions with gas molecules. The subsequent radical chemistry removes the pollutants contained in the exhaust gas. This thesis describes concepts of plasmachemical reactors and investigates parameters of the plasmachemical removal of nitric oxides as well as the plasmachemical oxidation of hydrocarbons. As a result the efficiency of the radical production had been increased by a factor two by applying fast rising voltage pulses. In synthetic gas mixtures including hydrocarbons the lightoff temperature of a down-stream catalyst had been reduced by 90°C depending on the distance between the plasmachemical reactor and the catalyst. During the cold start phase (0-50 sec.) of the european MVEG-III test cycle, carried out on a roll test bench of the FEV-Motorentechnik, Aachen, 43% of the cold start hydrocarbon-emssion had been reduced by plasmachemical oxidation without a catalyst