摘要
为研究用于国六认证演示试验的选择性催化还原(SCR)催化剂的排放性能，通过发动机台架试验和整车试验，从氮氧化物(NOx)转化效率、氨存储性能、瞬态循环排放和实际道路排放等方面对比分析了新鲜态SCR催化剂和老化后SCR催化剂的排放特征。结果表明：新鲜态SCR催化剂在850 ℃、含10%水蒸气的空气中老化30 h可以制备得到满足车载诊断系统（OBD）演示试验要求的老化态SCR催化剂，老化态SCR催化剂对NH3的吸附能力大幅下降，瞬态循环测试中NOx平均转化效率相比新鲜态催化剂下降21.1%，氨泄漏的体积浓度最高为304.98×10-6，作为排放污染物的NH3同样需要引起关注并加以限定；在整车实际道路排放方面，老化态催化剂在不同工况下的NOx老化率相当，其中90%分位值的NOx排放为1 982.67 mg/（kW·h），相比新鲜态催化剂增加近6.31倍，NOx窗口比排放的通过率为0%，但体积浓度超过500×10-6占比仅为0.2%，远低于国六限值5%的要求，后续排放法规升级需要针对NOx的瞬态体积浓度重点加严。
Abstract
In order to study the emission performance of selective catalytic reduction (SCR) catalyst used in the China Ⅵ certification demonstration test, the emission characteristics of fresh SCR catalyst and aged SCR catalyst were compared and analyzed from the aspects of nitrogen oxide (NOx) conversion efficiency, ammonia storage performance, transient cycle emission and actual road emission through engine bench test and vehicle test. The results show that the aged SCR catalyst can be prepared through 30 h aging of the fresh SCR catalyst in air containing 10% water vapor at 850 ℃, which meets the requirements of the onboard diagnostic system (OBD) demonstration test. The adsorption capacity of aging SCR catalyst to NH3 reduces greatly, the average NOx conversion efficiency of transient cycle test decreases by 21.1% compared with that of the fresh catalyst, and the volume concentration of ammonia leakage is up to 304.98×10-6 which should also be paid attention to and limited as the exhaust pollutant. In terms of actual vehicle on-road emission, the NOx aging rates of aged catalyst under different working conditions are similar and the NOx emission of 90% decile value is 1 982.67 mg/(kW·h), which is nearly 6.31 times higher than that of fresh catalyst. The NOx window specific emission passing rate is 0%. However, the volume concentration of more than 500×10-6 accounts for only 0.2%, which is far lower than the China Ⅵ limit value of 5%. The subsequent upgrade of emission regulations needs to focus on the transient volume concentration of NOx.
关键词
选择性催化还原 /
催化剂 /
排放性能 /
水热老化
Key words
selective catalytic reduction /
catalyst /
emission performance /
hydrothermal aging
刘卫林，庞国民，郭亚辰，赵亮.
国六柴油机水热老化SCR催化剂的排放性能研究[J]. 车用发动机. 2024, 0(5): 32 https://doi.org/10.3969/j.issn.1001-2222.2024.05.005
LIU Weilin,PANG Guomin,GUO Yachen，ZHAO Liang.
Emission Performance of Hydrothermal Aging SCR Catalysts for China Ⅵ Diesel Engine[J]. Vehicle Engine. 2024, 0(5): 32 https://doi.org/10.3969/j.issn.1001-2222.2024.05.005
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