【作者】 黄齐飞；

【导师】 宋崇林；

【作者基本信息】 天津大学 ， 动力机械与工程， 2008， 博士

【摘要】 低温等离子体辅助催化型颗粒物捕集器（NTP/CDPF）技术具有协同脱除PM和NOx的优势,是柴油机尾气后处理领域的研究热点之一。本文通过对钙钛矿La-K-Co-Fe体系催化剂的表征和活性评价,筛选出活性较高的模型催化剂,并探讨了催化反应机理;同时,研究了NTP对柴油机尾气的净化规律。为考查实际净化效果,在柴油机台架上研究了NTP/CDPF催化净化系统对柴油机有害污染物的净化效果及NTP和催化剂对颗粒物捕集器再生温度的影响,为NTP/CDPF系统的推广应用奠定了理论基础。论文主要结论如下:1. K、Fe分别对LaCoO₃中La和Co的部分取代会导致催化剂晶格发生畸变,同时可使部分B位Co^2+<sup>3+氧化为Co³⁺。2. La_1-xK_xCoO₃能大幅降低碳烟与O2反应的最大燃烧速率温度（Tmax）和活化能（Ea）,而LaFeyCo1-yO₃对反应的影响不显著,其中La0.6K0.4CoO₃可将Tmax降低至400℃,Ea降低至41.6kJ/mol;钙钛矿催化剂La_1-xK_xCoO₃(x≤_0.5)和LaFeyCo1-yO₃(y≤_0.8)均能降低碳烟在NOx气氛中的起燃温度（Ti）和峰值温度（Tp）,其中La_0.9K0.1CoO₃可使碳烟的起燃温度降低至100℃,峰值温度降低至105℃。3.取代元素与取代量的不同对催化剂去除柴油机尾气中NOx的净化效率及最佳效率温度范围影响极大。La_1-xK_xCoO₃(0.1≤x≤_0.5)在375℃～525℃范围内具有较高的催化活性,而LaFeyCo1-yO₃（0.1≤y≤0.6）在275℃³75℃范围内具有较高催化活性,其中La_0.8K0.3CoO₃和LaFe_0.5Co_0.5O₃对NOx的净化效率可达50%。4.当输入能量较低（电压:7.5kV）时,NTP对NOx的净化效率可达75%,但对PM和CO的净化效率较低。当输入能量较高（电压:10kV）时,NOx的浓度增大,PM的净化效率却高达86%,干碳烟的净化效率接近100%,SOF的净化效率达80%,饱和烷烃和芳香烃的净化效率分别为90%和65%,THC的净化效率可达83%。NTP在柴油机排气污染物净化过程中存在输入能量窗口问题。5. NTP/CDPF（钙钛矿型）催化净化系统能有效净化柴油机尾气中NOx、PM、HC和CO等污染物。在实验工况范围内,对PM的去除效率可达82%,对NOx的净化效率可达31%,对HC的净化效率可达88%,对CO的净化效率可达12%。催化净化系统的空速越高,净化效率越低。6.再生措施、颗粒物加载程度和催化剂种类是控制CDPF再生温度的重要因素,NTP可使钙钛矿CDPF的再生温度降低至30_0.5℃。更多还原

【Abstract】 Due to the potential of simultaneously reducing particulate matter （PM） and nitrogen oxides （NOx） emissions, non-thermal plasma coupled with catalytic diesel particulate filter technology （NTP/CDPF） has been given more attentions for its application on the exhaust aftertreatment systems. In the present study, the prototype catalyst combined with highest activity was screened out through the characterization and catalytic activity evaluation of La-K-Co-Fe perovskite-type catalysts and catalytic reaction mechanism was discussed. Also, the removal effects of NTP on diesel exhaust emissions are investigated. The practical application of NTP/CDPF system on diesel exhaust emissions are performed on a bench test, and the influences of NTP and the catalysts on the regeneration temperature of diesel particulate matters were studied The investigations will benefit the further use of NTP/CDPF system and provide a theoretical foundation.The major conclusions of this dissertation can be summarized as follows:1. The partial substitution of K, Fe for La, Co in LaCoO₃ respectively results in perovskite cell deformation and can oxidize a part of Co^2+<sup>3+ at B site to Co³⁺.2. La_1-xK_xCoO₃ is able to significantly reduce the temperature at which the soot combustion rate is maximum （Tmax） and reaction activation energy （Ea） of soot oxidation with O2, while LaFeyCo1-yO₃ has little influence on the reaction. Among them, La0.6K0.4CoO₃ can decrease Tmax to 400℃and Ea to 41.6kJ/mol. Both La_1-xK_xCo1-yFeyO₃ （x≤0.5） and LaFeyCo1-yO₃ （y≤0.7） can decrease Ti （temperature at which the soot ignites） and Tp （temperature at which CO2 concentration is the highest） values in NOx atomsphere. Among all the developed perovskite-type catalysts, La_0.9K0.1CoO₃ is discovered to have the highest catalytic activity in simultaneous reduction of PM and NOx emissions, it could decrease Ti to 100℃and Tp to 105℃3. For NOx removal, the dopant and doping amount play an important role on the reduction efficiency and the effective temperature window of these catalysts. La_1-xK_xCoO₃ （0.1≤x≤0.5） exhibits higher catalytic activity in the range of 375℃～ 525℃, while LaFeyCo1-yO₃ （0.1≤y≤0.6） shows higher catalystic activity in the range of 275℃³75℃. La0.7K0.3CoO₃ and LaFe_0.5Co_0.5O₃ could produce 50% reduction in NOx respectively.4. By means of NTP,75% reduction in NOx occur at lower input energy （voltage: 7.5kV）, while the removal efficiencies of PM and CO are rather low. With increasing of the input energy to 10kV, the use of NTP leads to an increase of NOx concentration in exhaust gas, however PM, dry soot, SOF, aromatic, PAHs and HC are efficiently removed with removal efficiencies of 86%, 100%, 80%, 90%, 65% and 83% respectively. The trade-off between NOx and other pollutants exists when altering the input energy of NTP.5. NTP/CDPF system is available to abate the toxic exhaust emissions, such as NOx、PM、HC and CO, from diesel engine. Under the engine operation conditions selected, the reductions in PM, NOx, HC and CO reach 82%, 31%, 88% and 12% respectively. Meanwhile, the removal efficiencies decrease with enhancing the space velocity in the system.6. Regeneration method, PM mass trapped in the DPF and catalyst type are the most important factors to control the Treg of DPF, and NTP could decrease the Treg of perovskite-type DPF to 30_0.5℃.更多还原