介质阻挡放电废气中萘的降解特性和机理

Degradation properties and mechanism of naphthalene from exhaust gas using dielectric barrier discharge

针对大气中日益严重的多环芳烃（PAHS）污染问题，采用介质阻挡放电对模拟废气中萘的降解特性和机理进行了研究，分析萘的初始体积分数、停留时间和废气组分对萘降解效率和降解产物的影响，并通过对降解副产物的分析，探索其降解机理．研究结果表明：萘初始体积分数的增加引起了萘降解效率下降，但提高了降解的能量利用率；随着反应停留时间的延长，萘的降解效率趋于平稳，COx选择率逐步提高；当废气中氧气的体积分数为3％时，70％以上的萘能被降解，但COx选择率却只有30％；当氧气体积分数为3％～20％时，萘的降解效率相对稳定，但COx选择率却稳步提高；当氧气体积分数为20％时，COx选择率达到77％．根据降解副产物的分析，氮气激发态在萘的初始降解过程中起到重要的作用，而且O自由基能够通过与萘分子的直接碰撞反应促进萘的降解，而萘的深度降解则依靠O、OH等自由基的氧化．

Effects of the initial volume fraction of naphthalene, residence time and exhaust gas components on naphthalene degradation process were analyzed. The naphthalene degradation mechanism was explored through byproducts analysis. Degradation efficiency decreases with the increasing initial volume fraction, while the energy utilization efficiency improves. When the residence time is prolonged, the degradation efficiency trends to be stable, while the COx selection rate enhances step by step. The degradation efficiency can reach above 70% as the volume fraction of oxygen gas from exhausted gas is 3%, but the COx selection rate is only 30%. The degradation efficiency is relatively stable when the volume fraction of oxygen gas is 3%-20%, while the COx selection rate gradually increases and goes to 77% at 20% volume fraction of oxygen gas. According to the degradation byproducts, nitrogen gas excited state plays an important role during the initial degradation of naphthalene. And O radical can promote the naphthalene degradation through some direct collision reactions. However, complete degradation of naphthalene depends on O and OH radicals.