柴油机LNT浓燃过程中铑表面CO还原NO的详细反应机理  

Detailed mechanism of NO reduction by CO over rhodium during rich period of diesel LNT

作　　者：苏庆运[1] 王胜[1] 李艳宾[1] 帅石金[2] 王建昕[2] 

机构地区：[1]大连理工大学内燃机研究所,大连116024 [2]清华大学汽车安全与节能国家重点实验室,北京100084

出　　处：《汽车安全与节能学报》2012年第1期51-57,共7页Journal of Automotive Safety and Energy

基　　金：国家自然科学基金(50906008);清华大学汽车安全与节能国家重点实验室开放基金(KF11181);天津大学内燃机燃烧学国家重点实验室开放基金

摘　　要：研究了在柴油机尾气稀燃NOx捕集(LNT)技术再生阶段中,考虑了反应的副产物N2O,用CO还原NO的反应过程。建立了铑催化剂表面CO还原NO及N2O的详细化学反应机理。分别对CO-NO反应及不同进气比例下的CO-N2O反应,进行了数值模拟,其结果与实验吻合良好。结果表明:N2O是CO还原NO过程中的重要中间产物,且在一定条件下可继续被CO还原。在475～620K温度区间内,NO还原过程主要是通过N2O路径实现的。对于单独的CO-N2O反应,研究了进气中CO浓度的影响,并通过对基元反应速率的分析,确定了反应的限速步为N2O解离。The process of diesel exhaust NO reduction using CO as the reductant during the rich period of lean NOx trap （LNT） was investigated considering an important byproduct N2O. Detailed mechanisms for CO-NO and CO-N2O reactions over rhodium catalyst were proposed to numerically simulate experimental results, with different feed gas ratios for the CO-N2O reaction. Good agreement was obtained for both of the two reactions. The results show that N2O, as an important intermediate during NO reduction, undergoes further reactions with CO under certain conditions. Most of the N2 is produced through the N2O route during NO reduction at 475-620 K. The influence of the feed gas CO concentration on the isolated CO-N2O reaction was probed, and the rate-limiting step was determined to be the decomposition of N2O according to the analysis of the elementary reaction rate.

关 键 词：柴油机 稀燃NOx捕集器(LNT) 氧化亚氮 一氧化碳 铑催化剂 详细机理 

分 类 号：U461.91[机械工程—车辆工程]