研究了柴油机NOx存储还原技术(NSR)浓燃再生阶段中NO还原反应.发展了铂催化剂表面H2还原NO的详细化学反应机理,包括6种气相组分、10种表面组分及28步基元反应,其中包含了主要含氮产物N2及副产物N2O和NH3的生成路径.此机理与CHEMKIN软件中的活塞流反应器(PFR)模型耦合进行数值模拟,反应器出口各组分体积分数预测结果与文献中实验数据吻合良好.在NO体积分数为500×10-6、反应器入口温度为270℃的条件下分析了进气中H2体积分数((100～2500)×10-6)对含氮产物选择性的影响.结果表明,H2体积分数小于500×10-6时,N2和N2O为主要的含氮产物;随着H2体积分数逐渐升高,当ψ(NO)/ψ(H2)高于1.5时,NH3成为主要产物.由敏感性分析结果可知,NH3对H2吸附反应的敏感性系数最大,提高该反应速率将促进NH3的生成.
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