【作者】 秦宏宇；

【导师】 鲍晓峰；

【作者基本信息】 中国环境科学研究院 ， 环境工程， 2011， 硕士

【摘要】 随着汽车数量的迅速增长,汽车污染排放已成为很多大中城市空气污染的主要来源。柴油车与汽油车相比具有耐用性好、维护成本低、温室气体排量小等特点,在当前能源危机的形势下,推广应用柴油车是一项有效的应对措施。柴油车排放的主要污染物为氮氧化物(NOx)和颗粒物(PM),目前降低NOx排放的后处理措施主要包括NOx选择性还原技术(SCR)和NOx储存-还原技术(NSR),颗粒物排放则较多地采用过滤器来控制。四效催化技术能够将PM、HC、CO和NOx同时净化,是目前先进的柴油车尾气后处理技术。本文综述了四效催化技术的发展现状,在分析了整体式和组合式四效催化方法在实际应用中所存在的一些不足的基础之上,提出了一种新型的再生方法,以车用柴油为原料制取富氢气体,并以此种气体来对氮氧化物储存-还原催化剂和颗粒物过滤器进行再生,从而实现对柴油车尾气四效催化技术进一步的完善。本文首先通过模拟配气实验研究了NOx储存-还原(NSR)催化剂储存NOx的性能,并分析了NSR催化剂再生所需的最适反应条件。结果表明：300℃下催化剂的储存性能最佳,温度升高到600℃时催化剂能够完全脱附,O2能够极大地促进储存反应的进行；使用浓度为5%的H2对催化剂进行再生时,再生过程不受温度影响,仅2min左右就可将催化剂再生完全。根据模拟配气实验得出的NOx储存-还原催化剂再生所需的最适反应条件,开发了一套等离子体制氢系统。系统中等离子体反应器通过高电压、低电流的电弧放电将空气离解,引发柴油的部分氧化反应,产生富氢气体(H2浓度5.3%)。而后以排气代替空气来制氢,同样成功制取出富氢气体(H2浓度3.3%)。最后,在柴油发动机上考察了富氢气体在NOx储存-还原催化剂和颗粒过滤器再生中的应用。结果表明：富氢气体(H2浓度5%)能够对NOx储存-还原催化剂和颗粒过滤器在短时间内(分别为240s和165s左右)再生完全,等离子体制氢系统所制取的富氢气体完全能够满足再生要求。更多还原

【Abstract】 Vehicular emissions have become the major source of air pollution in many cities with the rapid growth of vehicle population. Compared with gasoline vehicles, diesel vehicles have advantages such as high durability, lower cost of maintenance and less greenhouse gas emissions. Today, the promotion of diesel vehicles is considered an effective way to mitigate the energy crisis. The major pollutants in diesel emissions are nitrogen oxides (NOx) and particulate matters (PM). The aftertreatment technologies for NOx control mainly include selective catalytic reduction (SCR) and NOx storage-reduction (NSR), while PM is usually reduced by particulate filter.At present, four-way catalytic technology is considered an advanced diesel aftertreatment technology which can reduce HC, CO, NOx and PM at the same time. The development of four-way catalytic technology was reviewed in this thesis, and a new kind of regeneration method was proposed based on the analysis of shortages of combined and integrated four-way catalytic technologies in practice. The method uses hydrogen-rich gas produced with diesel fuel to regenerate the NOx storage-reduction catalyst and particulate filter, further improving the four-way catalytic technology of diesel exhaust aftertreatment.Firstly, the storage capability of NOx storage-reduction catalyst was investigated by simulating exhaust gases and the optimal conditions for NSR catalyst regeneration was analyzed in this thesis. Results show that 300℃is the optimal temperature for NOx storage and the presence of O2 significantly promotes the progress of NOx storage reaction, while at 600℃the NOx adsorbed by the catalyst will be completely released. The NSR catalyst can be regenerated in about two minutes whenφ(H2)=5% and it will not be affected by the temperature.According to the optimal conditions for NSR catalyst regeneration found in the simulation experiment, a system that can produce hydrogen with plasma technology was developed. In the system the plasma reactor can ionize air by arc discharge with high voltage and low current to arouse the partial oxidation reaction of diesel fuel to produce hydrogen-rich gas (φ(H2)=5.3%). When the air was replaced by engine exhaust, the hydrogen-rich gas (φ(H2)=3.3%) was also produced successfully.Finally, the use of hydrogen-rich gas for the regeneration of NOx storage-reduction catalyst and particulate filter was studied on a diesel engine. Results show that hydrogen-rich gas (φ(H2)=5%) can completely regenerate the devices mentioned above in a short time (about 240 and 165 seconds, respectively). Thus, the hydrogen-rich gas produced by plasma technology can meet the requirements of regeneration.更多还原