Simulation of toluene decomposition in a pulse-periodic discharge operating in a mixture of molecular nitrogen and oxyge
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TEMPERATURE PLASMA
Simulation of Toluene Decomposition in a PulsePeriodic Discharge Operating in a Mixture of Molecular Nitrogen and Oxygen A. N. Trushkin and I. V. Kochetov Troitsk Institute for Innovation and Fusion Research (TRINITI), ul. Pushkovykh 12, Troitsk, Moscow oblast, 142090 Russia Received July 20, 2011; in final form, October 17, 2011
Abstract—The kinetic model of toluene decomposition in nonequilibrium lowtemperature plasma gener ated by a pulseperiodic discharge operating in a mixture of nitrogen and oxygen is developed. The results of numerical simulation of plasmachemical conversion of toluene are presented; the main processes responsi ble for C6H5CH3 decomposition are identified; the contribution of each process to total removal of toluene is determined; and the intermediate and final products of C6H5CH3 decomposition are identified. It was shown that toluene in pure nitrogen is mostly decomposed in its reactions with metastable N2(A3∑ +u ) and N2(a'1∑ −u ) molecules. In the presence of oxygen, in the N2 : O2 gas mixture, the largest contribution to C6H5CH3 removal is made by the hydroxyl radical OH which is generated in this mixture exclusively due to plasmachemical reactions between toluene and oxygen decomposition products. Numerical simulation showed the existence of an optimum oxygen concentration in the mixture, at which toluene removal is max imum at a fixed energy deposition. DOI: 10.1134/S1063780X12040083
1. INTRODUCTION Toluene (C6H5CH3) is among organic solvents most commonly used in modern chemical, light, tex tile, numerous paint and varnish industries, and oth ers. Toluene vapor emission into an air medium of industrial facilities and through ventilation exhausts into the atmosphere has an adverse effect on human health and environmental conditions. The character istic feature of these ventilation flows consists in a comparatively low concentration of toluene vapor, which, nevertheless, exceeds the maximum allowable sanitary norms by several orders of magnitude. In this case, the use of conventional methods of gas purifica tion (thermal burning, catalytic oxidation, absorption, and adsorption methods) becomes inefficient and economically unprofitable. This situation stimulates the search for new more advanced methods for neu tralizing gas exhausts. Currently, active studies on the development of nonequilibrium plasma methods of gas purification are performed in all developed coun tries. These methods are based on the formation of a high concentration of chemically active and ecologi cally safe particles in polluted gas using nonequilib rium lowtemperature plasma without appreciable heating of a treated gas flow. Generated chemically active particles react with pollutant molecules and decompose harmful impurities. In this case, toluene vapor is a very popular object of laboratory studies, used to test the efficiency of nonequilibrium plasma chemical purification of air from harmful impurities,
since toluene vapor is also a very complicated object from the viewpoin
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