Treatment of N 2 O in pulsed microwave torch discharge M. Jasi´ nski, D. Czylkowski, Z. Zakrzewski, J. Mizeraczyk Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80–231 Gda´ nsk, Poland e–mail: mj@imp.gda.pl Received 23 April 2004 Results of using a moderate–power (several hundred Watts) pulsed microwave torch plasma (MTP) to the conversion of atmospheric-pressure nitrous oxide (N2O) into nitro- gen oxides (NO, NO2 and N2O4) are presented. The pulsed regime allowed to decrease the average power used, resulting in a higher value of energy efficiency by about 10% (reaching several hundred g[N2O]/kWh) at the same efficiency of the decomposition of N2O (70 ÷ 90%) as at the continuous operation of MTP. The removal rate increased up to 200 g[N2O]/h. The obtained results suggest the pulsed MTP promising for efficient decomposition of various gaseous pollutants, e.g. fluorocarbons. PACS : 52.75.Hn, 52.80.Tn Key words : microwave torch discharge, treatment of N2O, pulsed regime 1 Introduction The greenhouse gases emitted to the atmosphere causes environmental prob- lems, such as the global warming up and depletion of the ozone layer. One of the severe burdens to the atmosphere pollution is emission of nitrous oxide N 2 O. Conventional methods, e.g. thermal decomposition, catalytic decomposition and oxidation proved not to be efficient enough when used for the reduction of N 2 O emission [1, 2]. Recently it was shown that the thermal and non–thermal plasmas [3–11] have a potential to convert nitrogen oxides in less harmful compounds. Some investiga- tions were carried out to convert N 2 O into NO, NO 2 or N 2 O 4 using the gliding discharge [10, 11]. The obtained products (NO, NO 2 and N 2 O 4 ) are proposed to be used further for the production of nitric acid. Recently, Jasi´ nski et al proposed the microwave torch plasma operated in continuous wave regime (cw MTP) as an effective tool for processing various kinds of hydrocarbons and their derivatives [12–14], and nitrogen oxides (NO, NO 2 and N 2 O) [3, 15]. As observed in [15] the cw MTP is favourable for N 2 O decomposition. In this paper, results of testing the capability of the atmospheric–pressure pulsed microwave torch plasma (pulsed MTP) generated at moderate power (several hun- dred W) to decompose nitrous oxide N 2 O are presented. A pulsed operation of MTP devices becomes of increasing interest because of the expected higher efficiency of such devices when using to gas treatment. Czechoslovak Journal of Physics, Vol. 54 (2004), Suppl. C C859