国六柴油机用铜基和钒基SCR催化剂特性台架对比研究

Comparison between Copper-Based and Vanadium-Based SCR Catalyst of China Ⅵ Diesel Engine Based on Bench Test

在发动机测试台架上对比研究不同温度、空速、氨氮比下铜基分子筛SCR催化剂和钒基SCR催化剂的NOx转化效率和氨存储特性。试验结果表明,对于铜基SCR催化剂,在低温区域200~250℃,温度对氮氧转化率影响明显,而空速影响甚微。温度对氨储存量影响极大,铜基SCR催化剂氨存储量随温度上升而快速下降,200℃时为1.5g/L,250℃为0.77g/L。对比而言,铜基催化剂低温性能优异,转化效率达到84%,明显高于钒基催化剂低温40%~60%转化效率;中温段(250~450℃)性能稳定,转化效率达到98%;高温段(450℃以上)效率较高,达到96%,且随着温度升高效率降低幅度较小。铜基分子筛催化剂性能整体优于钒基催化剂,从技术角度考虑,为国六后处理催化剂的优先选择。本试验研究工作获得的基础数据,可用于发动机数据标定。

The bench test was conducted to investigate NOxconversion efficiency and NH3 storage characteristics of copperbased molecular sieve and vanadium-based SCR catalysts under different temperatures,space velocities and ANRs.The results showed that the low temperature area between 200℃and 250℃had an obvious effect on NOxconversion and the space velocity had little influence for copper-based SCR catalyst.In addition,temperature had a remarkable influence on NH3 storage amount,and the NH3 storage amount of copper-based SCR catalyst decreased rapidly with the increase of temperature.NH3 storage amount was 1.5 g/L at 200 ℃,but decreased to 0.77 g/L at 250 ℃.Compared with vanadium-based catalyst with40%-60%conversion rate at low temperature,copper-based catalyst showed much better low-temperature performance with conversion efficiency up to 84%.Besides,copper-based catalyst had stable performance with conversion efficiency of 98% at middle temperature about 250℃to 450℃and could also achieve conversion efficiency of 96%at high temperature higher than 450℃,and the decrease scope of conversion efficiency for copper-based catalyst is minor with the increase of temperature.Accordingly,copper-based molecular sieve catalyst had better performance than vanadium-based catalyst,which should be the priority choice for the post-treatment of China Ⅵ diesel engine from a technical point of view.The basic data obtained in this test study could be used to calibrate the engine.