采用分子筛SCR催化器降低柴油机NO_x排放的试验研究

在1台6缸柴油机上进行了十三工况各选定氨氮比(N_(SR))下的两种分子筛SCR催化剂催化活性的试验研究,分析了两种分子筛SCR催化剂的低温催化活性和NO_x转化效率受温度、空速以及HC转化效率影响的规律。结果表明:t=250℃时,空速对NO_x转化效率影响较小;由于受温度的影响,在N_(SR)值为1.0的情况下Cu基与Fe基分子筛的NO_x转化效率最高分别为88%和78%,Cu基SCR催化剂较Fe基SCR催化剂有较好的低温催化性能;t=250℃时,Fe基分子筛催化剂的抗HC中毒能力不如Cu基分子筛催化剂。t=350℃时,NO_x转化效率受空速与温度的双重影响,两种SCR催化剂的最高NO_x转化效率分别出现在空速为115 060 h~(-1)和90 400 h~(-1)时;t=350℃时,Fe基分子筛催化剂比Cu基分子筛催化剂对HC更加敏感。

Experimental Study on Reducing NOx Emission of Diesel Engine with Molecular Sieve SCR Catalyst

On a 6-cylinder diesel engine,the activity of two molecular sieve catalysts with the given NSR was researched by the ESC experiment.The low-temperature activity of two molecular sieve catalysts and the influence of temperature,air speed and HC on NO_x conversion efficiency were analyzed.The results show that the air speed has little influence on NO,conversion at the temperature of 250℃.The highest efficiencies of NO_x conversion for Cu-based and Fe-based molecular sieve are 88% and 78%respectively at the NSR of 1.0,and hence Cu-based SCR catalyst has a better low-temperature performance than Febased SCR catalyst.Furthermore,Cu-based molecular catalyst has the better ability of anti-hydrogen poisoning.At the temperature of 350℃,the efficiency of NO_x conversion is influenced by air speed and temperature and the efficiencies for two molecular sieve catalysts reach the highest respectively at the air speed of 115 060 h^-1 and 90 400 h^-1.Fe-based molecular catalyst is more sensitive to HC than Cu-based molecular catalyst.