不同反应气氛下负载型Cu-Co/ZSM-5催化剂的柴油车NOx净化性能

摘要

Under the simulated environment of diesel vehicle exhaust ,the de-NOx capability of C3 H8 based on the supported Cu-Co/ZSM-5 catalysts prepared with the impregnation method under different atmospheres was researched with a micro-reac-tor .The experimental results showed that 3% Cu-3% Co/ZSM-5 catalyst exhibiting good light-off characteristic of purified NOx and high temperature selectivity had different catalytic performance under different reaction atmospheres .The oxygen of not more than 6% volume fraction facilitated the reduction of NOx with C3 H8 and NOx conversion rate increased with the increase of O2 content .The produced oxygen with high volume fraction at 300~400 ℃ reaction harmed NOx reduction with C3 H8 and NOx conversion rate decreased with the increase of O2 content .The optimal O2 concentration for the catalyst performance was 2% ~8% volume fraction .Furthermore ,the higher concentration of C3 H8 was more favorable for the reduction of NOx .CO and CO2 volume fraction had no evident effect on NOx reduction with C3 H8 .The catalyst had good performance of reducing NOx ,but needed a well-matched air-fuel ratio .%在模拟柴油车尾气气氛下 ,利用微反装置研究了浸渍法制备的Cu-Co/ZSM-5催化剂在不同反应气氛下的C3 H8 选择性催化净化NOx 性能.结果表明 ,具有良好的净化NOx 起燃性能和高温选择性的3% Cu-3% Co/ZSM-5催化剂在不同的反应气氛下催化性能各异.O2 体积分数较低时(≤6% ) ,O2 的存在有利于C3 H8 催化还原NOx ,催化剂的NOx 转化率随O2 体积分数的增加而增加 ;高温(300~400 ℃)反应时O2 体积分数较高(≥6% )对C3 H8 催化还原NOx 是不利的 ,O2 的增加使催化剂的NOx 转化选择性变差 ,NOx 转化率下降.催化剂最适于的O2 体积分数为2% ~8% .C3 H8 体积分数越高 ,越有利于NOx 的还原.反应气氛中的CO2 和CO的体积分数变化对催化剂的C3 H8 催化还原NOx 活性没有明显的影响 ,该催化剂仍具有较高的稳定NOx 净化性能.催化剂在使用过程中应匹配好发动机的空燃比.