涂覆方式对DOC催化剂起燃特性的影响

Influence of Coating Method on Light-Off Characteristics of DOC Catalyst

以中型柴油机为平台,以现行国六排放法规为依据,研究柴油氧化催化剂(DOC)起燃特性的影响因素。针对DOC催化剂不同的涂覆方式及贵金属不同比例,设计了3种不同涂覆方式的DOC催化剂,记为方案A、方案B、方案C,3种方案的贵金属总含量相同,方案A和方案B中前后区的贵金属Pt和Pd比例不同,方案C中提高了Pt的比例。进行了两个阶段的老化试验,研究了在不同工况条件下3种涂覆方式DOC的起燃特性。结果表明:A、B、C 3种涂覆方式的DOC催化剂都能满足起燃性能,B、C两个涂覆方案的HC转化效率较高,催化剂起燃性能较好,对于保证起燃以及对HC泄漏的控制有一定的优势。

The influencing factors for the light-off characteristics of diesel oxidation catalyst(DOC)were studied on a medium-duty diesel engine according to the current ChinaⅥemission regulation.According to the different coating methods and noble metal proportion of DOC catalyst,three different schemes were designed which were labeled as Plan A Plan B and Plan C respectively.The total noble metal content of three schemes was the same.The proportions of Pt and Pd were different in front and back zone for Plan A and Plan B,and the proportion of Pt increased in Plan C.Besides,the aging tests were carried out in two stages respectively,and the light-off characteristics were studied under different working conditions.The results show that the DOC catalysts of three coating methods from Plan A,Plan B and Plan C can meet the light-off performance requirements.Plan B and Plan C have higher HC conversion efficiency and better light-off performance,which have certain advantages for guaranteeing light-off and controlling HC leakage.