稀燃汽油机Ag/Al_2O_3催化剂上选择性还原NO_x  

Selective catalytic reduction of NO_x on Ag/Al_2O_3 catalyst in lean-burn gasoline engines

作　　者：朱永青[1] 李俊华[1] 康守方[1] 李临生[2] 王建昕[2] 

机构地区：[1]清华大学环境科学与工程系,北京100084 [2]清华大学汽车工程系,北京100084

出　　处：《清华大学学报（自然科学版）》2007年第3期361-364,共4页Journal of Tsinghua University(Science and Technology)

基　　金：国家自然科学基金重点资助项目(20437010);国家自然科学基金资助项目(20507012)

摘　　要：富氧条件下氮氧化物(NOx)去除是目前机动车尾气净化的研究难点之一。制备了Ag/Al2O3催化剂,在试验室活性评价的基础上,进行了稀燃汽油机台架上NOx选择性催化还原(selective catalytic reduction,SCR)试验,评价了不同还原剂(乙醇和正辛烷)对NOx去除效率的影响。结果表明,在无外加还原剂条件下,400℃时NOx转化率大于40%;以乙醇为还原剂时,低温活性得到明显提高,活性区间大大加宽。实验室评价和台架试验中NOx转化率可达90%左右,还原剂以总碳氢(THC)计,THC/NOx最佳比例为6,最佳反应空速为30000h-1;但是外加还原剂时SCR催化剂会带来THC和CO排放的增加。Selective catalytic reduction （SCR） catalysts are a new class of catalysts for NOx removal from vehicle exhaust in the presence of O2. The Ag/Al2O3 monolith catalyst was prepared and studied with various reductants （ethanol and normal octane）. The results indicate that the NOx conversion reaches 40% without any reductants （above 400℃） with ethanol being a good reductant with the Ag/Al2O3 catalyst due to its remarkable low-temperature activity and wide activity window. The NOx conversion reaches 90% in the laboratory even on a lean-burn gasoline engine test bench. The catalytic activity is highest when the ratio of total hydrocarbon （THC）/NOx ratio is about 6 and the airspeed is about 30 000 h^-1）. However, the THC and CO emissions increase when the reductants are added to the flow stream.

关 键 词：稀燃汽油机 NOx 选择性催化还原(SCR) 乙醇 

分 类 号：TK421.5[动力工程及工程热物理—动力机械及工程]