DOC催化剂配方对轻型柴油机气态物排放性能的影响  

Effect of DOC catalyst composition on emission reduction performance for light-duty diesel engine

作　　者：楼狄明[1] 张静[1] 孙瑜泽 谭丕强[1] 胡志远[1] Lou Diming;Zhang Jing;Sun Yuze;Tan Piqiang;Hu Zhiyuan(School of Automotive Studies,Tongji University,Shanghai 201804,China)

机构地区：[1]同济大学汽车学院,上海201804

出　　处：《农业工程学报》2018年第6期74-79,共6页Transactions of the Chinese Society of Agricultural Engineering

基　　金：上海市科学技术委员会科研计划项目(16DZ1206700)

摘　　要：基于发动机台架测试,研究了DOC氧化型催化转化器(diesel oxidation catalytic converter,DOC)配方对安装有DOC+催化型颗粒捕集器(catalyzed diesel particulate filter,CDPF)+选择性催化还原系统(selective catalytic reduction,SCR)后处理系统的轻型柴油机气态物排放性能的影响,结果表明:DOC配方的改变对发动机经济性无显著影响;随贵金属负载量的增加以及Pt/Pd比例的减少,CO和总碳氢化合物(THC)的T50降低,CO和THC的低温段转化率(<300℃)升高,但随温度的继续升高,贵金属负载量或Pd的增加对CO和THC转化率的有利影响逐渐减弱,高温段平均转化率(≥300℃)差距较小;NO转化率随贵金属负载量的增加而增加;NO转化率对Pt含量更为敏感,Pt含量高的配方能促NO的氧化,与CO和THC转化率变化规律相反;当SCR入口温度低时,高的NO2浓度有利于提高SCR对NOx的转化效率,当SCR入口温度高时,SCR对NOx的转化效率均达到了90%以上且无明显差距;未发现DOC配方改变对外特性下CDPF压降的显著影响。Diesel engines are used extensively due to their superior economy and strong power performance,but the air pollution these engines produced is hard to overlook.With regulatory legislations for diesel engine emissions becoming stricter worldwide,integrated after-treatment systems are becoming increasingly important.The reduction performance of after-treatment systems can be affected by many factors.In this study,we investigated the effects of diesel oxidation catalytic converter(DOC)catalyst composition on gaseous emissions characteristics for the after-treatment systems.The after-treatment systems consisted of a diesel oxidation catalytic converter(DOC),a catalyzed diesel particulate filter(CDPF),and a selective catalytic reduction(SCR).An engine dynamometer test was conducted on a light-duty diesel engine which equipped with DOC+CDPF+SCR systems.All DOCs used were coated with Pt-Pd catalyst material.The experiment was performed under steady-state conditions of Yunnei D20TCI diesel engine with a displacement of 1.9 liters.This experiment used four sampling points located between the front and rear ends of each after-treatment device.During the full-load test,the data were collected every 200 revolutions from 1 000 to 3 200 r/min.The partial load test was conducted at the maximum torque speed(2000 r/min)with five loads:10%,25%,50%,75%and 100%.During the test,the data of different Precious Group Metal(PGM)load and Pt/Pd ratio of DOC were collected.Five sets of DOC catalyst composition were used:2120(Pt/Pd,5:1),1410(5:1),880(5:1),880(7:1),880(10:1)g/m3.The results showed that the light-off temperatures(T50)of carbon monoxide(CO)and total hydrocarbon compounds(THC)elevate with the decrease of PGM load.And the T50 of CO and THC both increased with the growth of Pt/Pd ratio.No significant gap existed between the various DOC catalyst composition,indicating that the Pt/Pd ratio of DOC had little influence on the engine’s economic performance.The CO oxidation activities increased monotonically as the PGM load,or Pt/Pd r

关 键 词：催化剂 柴油机 排放控制 DOC+CDPF+SCR 气态物排放 

分 类 号：X511[环境科学与工程—环境工程] X734.2