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研究了柴油机NO_x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H_2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N_2及副产物N_2O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,H_2体积分数小于500×10~(-6)时,N_2和N_2O为主要的含氮产物;随着H_2体积分数逐渐升高,当Φ(NO)/Φ(H_2)高于1.5时,NH_3成为主要产物。由敏感性分析结果可知,NH_3对H_2吸附反应的敏感性系数最大,提高该反应速率将促进NH_3的生成。
The NO reduction in diesel engine NO_x storage reduction technology (NSR) was studied. A detailed chemical reaction mechanism has been developed for the reduction of NO by H_2 on a platinum catalyst surface, including six kinds of gas phase components, ten kinds of surface components and a 28-step elementary reaction, including the formation of N_2 and N_2O and NH3, the main nitrogenous products . The mechanism was coupled with the PFR model in CHEMKIN software to simulate the results. The predicted volume fraction of each component at reactor exit was in good agreement with the experimental data in the literature. Under the conditions of NO volume fraction of 500 × 10 ~ -6 and reactor inlet temperature of 270 ℃, the selectivity to nitrogenous products in the inlet gas (100 ~ 2500 × 10 -6) Impact. The results showed that N_2 and N_2O were the main nitrogenous products when the volume fraction of H_2 was less than 500 × 10 ~ (-6). With the increase of H_2 volume fraction, when Φ (NO) / Φ (H_2) was higher than 1.5 , NH_3 becomes the main product. Sensitivity analysis results show that NH 3 has the highest sensitivity coefficient to H 2 adsorption reaction, increasing the reaction rate will promote the formation of NH 3.