国六柴油机水热老化SCR催化剂的排放性能研究  

Emission Performance of Hydrothermal Aging SCR Catalysts for ChinaⅥDiesel Engine

作　　者：刘卫林 庞国民 郭亚辰 赵亮 LIU Weilin;PANG Guomin;GUO Yachen;ZHAO Liang(CATARC Automotive Test Center(Tianjin)Co.,Ltd.,Tianjin 300300,China)

机构地区：[1]中汽研汽车检验中心(天津)有限公司,天津300300

出　　处：《车用发动机》2024年第5期32-41,共10页Vehicle Engine

基　　金：基于远程监控数据的柴油车尿素消耗合理性分析方法研究(TJKY2425035)。

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(NO_(x))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NH 3的吸附能力大幅下降,瞬态循环测试中NO_(x)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NH 3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NO_(x)老化率相当,其中90%分位值的NO_(x)排放为1982.67 mg/(kW·h),相比新鲜态催化剂增加近6.31倍,NO_(x)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NO_(x)的瞬态体积浓度重点加严。In order to study the emission performance of selective catalytic reduction(SCR)catalyst used in the ChinaⅥcertification demonstration test,the emission characteristics of fresh SCR catalyst and aged SCR catalyst were compared and analyzed from the aspects of nitrogen oxide(NO_(x))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 on-board diagnostic system(OBD)demonstration test.The adsorption capacity of aging SCR catalyst to NH 3 reduces greatly,the average NO_(x)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 NO_(x)aging rates of aged catalyst under different working conditions are similar and the NO_(x)emission of 90%decile value is 1982.67 mg/(kW·h),which is nearly 6.31 times higher than that of fresh catalyst.The NO_(x)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 ChinaⅥlimit value of 5%.The subsequent upgrade of emission regulations needs to focus on the transient volume concentration of NO_(x).

关 键 词：选择性催化还原 催化剂 排放性能 水热老化 

分 类 号：TK421.5[动力工程及工程热物理—动力机械及工程]