V2O5-WO3-MoO3/TiO2催化剂在柴油机NH3-SCR系统中的性能

针对柴油机运行工况特点及柴油机尾气成分特点,以工业纯锐钛型二氧化钛、偏钒酸铵、偏钨酸铵、钼酸铵为主要原料制备了颗粒状V₂O₅-WO₃-MoO₃/TiO₂催化剂,以Lister Petter TR1重型直喷式单缸柴油机为依托搭建试验台,研究了在真实柴油机尾气环境下催化剂的脱硝性能。结果表明,柴油机负载增大,催化剂脱硝活性呈现下降趋势。1800 r·min^-1时,脱硝活性最大值87.1%在负载25%、反应温度380℃、空速20000 h^-1、氨氮比1.0处取得。柴油机负载不同,导致催化剂活性温度窗口(脱硝活性>70%)发生较大变化,与负载25%相比,负载50%活性温度窗口减小约60℃。增大柴油机负载可以提高NH₃/N₂O反应起始温度,但是同时会导致高温区间(>400℃)N₂O生成量增大。

Performance of V2Os-WO3-MoO3/TiO2 catalyst for diesel engine NH3-SCR system

A catalyst of V₂O₅-WO₃-MoO₃/TiO₂ was prepared from industrial pure chemicals in which ammonium metavanadate was the main active component,ammonium tungstate and ammonium molybdate were active and structure coagents,anatase titanium dioxide was catalyst support.The catalyst could be suitable for the application in various diesel engine working conditions and the complicated exhaust compositions.It was tested on a Lister Petter TR1 type fuel injection single cylinder diesel engine to investigate conversion of NO_x and catalytic selectivity.The results show that the NO_x conversion declined with the increase of diesel engine loads.As the diesel engine running at 1800 r·min^-1,the maximum conversion of NO_x was 87.1% at load 25% and at the conditions of SV(space velocity)20000 h^-1,reaction temperature 380℃ and NH₃:NO_x 1.0.For different loads,reaction temperature had greatly effect on NO_x conversion.The temperature window(NO_x conversion>70%)of the catalyst was 340-440℃ at load 25% and changed to 400-440℃ at load 50%,reducing about 60℃.Increase of diesel engine load could improve initial temperature of NH₃/N₂O reaction,while it could lead to increase of N₂O generated at high temperature(>400℃).