三向催化剂 (TWC) 的故障引入了"超级发射器"
Xinping Yang1, Miao Tian1, Yunjing Wang1
1State Environmental Protection Key Laboratory of Vehicle Emission Control and Simulation, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; Vehicle Emission Control Center, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
Environment international
|August 16, 2024
概括
从出租车出发的车辆排放物与失败的三向催化剂 (TWCs) 是"超级排放者". TWC故障显著增加了排放量,抵消了压缩天然气 (CNG) 燃料替代的好处,迫切需要废弃车辆.
科学领域:
- 环境化学环境化学
- 大气科学 大气科学
- 分析化学 分析化学
背景情况:
- 汽车废气是主要的城市有机污染物来源.
- 旧的出租车有故障的三向催化剂 (TWC) 被确定为旧的出租车.
- 超级发射器 超级发射器
- 压缩天然气 (CNG) 是汽油出租车常见的替代燃料,但其与TWC故障相关的影响还未得到充分研究.
研究的目的:
- 调查燃料类型 (汽油与CNG) 和TWC功能 (最佳与失败) 对车辆排气成分的综合影响.
- 量化挥发性有机化合物 (VOC) 和中等挥发性有机化合物 (IVOC) 的排放量.
- 评估对臭氧形成潜力 (OFP) 和二次有机气溶 (SOA) 形成的影响.
主要方法:
- 使用Tenax TA管收集了汽油和CNG出租车的废气样本,其中包括运行和故障的TWC.
- 样品使用全面的二维气体染色学质谱法 (GC×GC-MS) 进行分析.
- 量化了216种有机化合物,包括80种VOC和132种IVOC.
主要成果:
- 与正常车辆相比,失败的TWC充当了超级排放者,增加了排放因子 (EF) 的3070倍,OFP的60112倍,SOA的3492倍.
- 对于失败的TWC出租车,CNG排气的有机EF总量是汽油的16倍,这表明TWC失败超过了CNG的好处.
- 在TWC后观察到臭氧和SOA的显著减少,但与IVOC,特别是乙烯的缩有关,这与CNG替代和TWC失败有关.
结论:
- 车辆TWC故障是城市空气污染的关键因素,超过了CNG燃料替代的减排效益.
- 有失败的TWCs的车辆的紧急废弃是必要的,以显著减轻空气污染.
- 目前的VOC测量可能错过了关键污染物,如纳二烯,一种与TWC故障和CNG使用密切相关的IVOC.
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