Abstract: With the increasing tightening of ammonia escape limits in emission regulations, it is crucial to study the ammonia storage performance of selective catalyst reduction (SCR) catalysts. The copper-based SCR zeolite catalysts prepared by in-situ coating are used, and In-situ FTIRs and NH3-TPD are used to characterize the chemical adsorption features, and the engine bench-top performance tests are conducted in accordance with the cycle of China VI. The results show that the NOX conversion is close to 100% in 200～450 ℃, and the NH3 desorption corresponded to weak, medium-strong and strong acid sites, respectively. Among them, the adsorbed species NH4 + forms on the strong acid sites is thermally stable. The effect of space velocity on ammonia storage in the SCR catalytic coating is small, and the ratio of ammonia escape to reaction ammonia consumption before and after spray stopping is positively correlated with the ratio of reaction ammonia consumption. The ratio of ammonia escape to reaction ammonia consumption before and after spraying stopping is 40 000 h-1>60 000 h-1>20 000 h-1 in the order of high to low in the range of 300～400 ℃. The correlation between ammonia storage and ammonia escape, NOX conversion rate, and the influences of space velocity, temperature, and urea injection are explored to provide a reference for the development of SCR catalyst formulation and urea injection control strategy.

Key words: In-situ coated; Zeolite SCR catalyst; Ammonia storage performance; Catalytic coating; Space velocity; Ammonia escape

摘要： 随着排放法规对氨逃逸限值日益加严，研究选择性催化还原（SCR）催化剂的储氨性 能至关重要。以原位涂覆制备的铜基分子筛 SCR 催化剂为研究对象，采用 In-situ FTIRs 和 NH3-TPD 表征化学吸附特征，并根据国 VI 排放法规循环进行发动机台架性能测试。结果表 明，在 200～450 ℃内 NOX 转化率接近 100%，NH3 脱附分别对应弱酸、中强酸和强酸位。其 中，强酸位上形成的吸附物种 NH4 +热稳定性好。空速对 SCR 催化涂层氨存储影响较小，且 停喷前后氨逃逸量占比与反应耗氨量占比成正相关性。300～400 ℃内，停喷前/停喷后氨逃 逸量与反应耗氨量占比由高到低依次均是 40 000 h-1> 60 000 h-1 > 20 000 h-1。探明了氨存储与 氨逃逸、NOX 转化率之间的关联性，以及空速、温度、尿素喷射等因素的影响规律，对 SCR 催化剂配方和尿素喷射控制策略开发提供参考。

关键词: 原位涂覆；分子筛 SCR 催化剂；储氨性能；催化涂层；空速；氨逃逸