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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。
Nitrogen oxide (NOx) removal under oxygen-enriched conditions is one of the most difficult research topics in vehicle exhaust purification. The Ag / Al2O3 catalyst was prepared. Based on the laboratory activity evaluation, a NOx selective catalytic reduction (SCR) test was carried out on a lean burn gasoline engine bench, and the effect of different reducing agents (ethanol and n-octane) Effect of NOx Removal Efficiency. The results showed that the NOx conversion was higher than 40% at 400 ℃ in the absence of added reductant. When ethanol was used as the reductant, the activity at low temperature was obviously increased and the activity range was greatly broadened. In the laboratory evaluation and the bench test, the conversion rate of NOx was up to 90%, the THC / NOx ratio was 6, and the optimum reaction space velocity was 30000h-1, SCR catalyst will lead to an increase of THC and CO emissions.