SCR对柴油机炭烟纳观结构及氧化活性的影响

Effects of SCR on Nanostructure and Oxidation Activity ofDiesel Exhaust Soot

研究选择性催化还原(selective catalytic reduction,SCR)对柴油机炭烟纳观结构和氧化活性的影响,结果表明:SCR处理前,炭烟微晶长度(L)随负荷增加而提高,随转速增加而减小,微晶层间距(D)、微晶曲率(T)及表观活化能(E a)的变化规律与之相反。排气无NH 3时,SCR处理后,炭烟L提高,D、T和E a均降低,且L、D、T和E a变化率随转速提高而减小,随负荷增加而增大;排气有NH 3时,SCR处理后,L、D、T和E a的变化率均减小;SCR对炭烟纳观结构参数与E a相关性影响不大。

This study investigated the effects of selective catalytic reduction(SCR)on the nanostructure and oxidative activity of diesel exhaust soot.The results show that the raw soot that sampled at the pre-SCR site tends to exhibit larger fringe length(L)at high engine load,while the values of L becomes smaller with the increased engine speed.However,the values of separation distance(D),tortuosity(T)and apparent activation energy(E a)show opposite trends compared with the trends of L while varying the engine operating condition.The SCR treatment without ammonia(NH 3)addition increases L and decreases D,T and E a.In addition,the rates of change become smaller with the increase in engine speed and they become larger with the increase in engine load.The SCR treatment with NH 3 addition decreases the rates of change for the values of L,D,T,E a.The SCR treatment exerts negligible effect on the correlation between nanostructure parameters and oxidative reactivity.