NO对铜-锰尖晶石脱汞性能的影响机理

Effect of NO on the performance of Cu-Mn spinel sorbent in the removal of Hg0 from flue gas

采用实验与量子化学计算相结合的方法研究了烟气中NO对铜-锰尖晶石脱汞性能的影响机理。结果表明,NO在高于250℃时抑制铜-锰尖晶石对Hg0的脱除,主要归因于NO与Hg0之间的竞争吸附作用;而在温度低于250℃时,NO对铜-锰尖晶石的Hg0脱除性能影响较小。吸附剂表面上吸附的汞主要以Cu-Hg合金和Hg(NO3)2的形式存在。铜-锰尖晶石表面上部分NO被氧化成NO2并与吸附态汞反应形成Hg(NO3)2。吸附剂表面上Cu和Mn原子为NO与Hg0的吸附活性位点,NO的吸附能大于Hg 0的吸附能;因此,NO与Hg0之间存在竞争吸附。由于Cu、Mn、N原子之间的强烈轨道杂化作用,NO与铜-锰尖晶石吸附剂表面之间具有较强的相互作用。

The effect of NO on the performance of Cu-Mn spinel sorbent in the removal of Hg0 from flue gas was investigated by using experimental and density functional theory(DFT)calculation methods.The results indicate that NO shows slightly inhibitory effect on the Hg0 removal on the CuMn2O4 sorbent at high temperature(>250℃),probably due to the competitive adsorption between NO and Hg 0 on the sorbent surface.At low temperature(<250℃),NO has little influence on the Hg0 removal.The mercury species adsorbed on the CuMn2O4 sorbent exist mainly in the forms of Cu-Hg amalgam and Hg(NO3)2.NO can be oxidized into NO2 over the CuMn2O4 sorbent and NO2 then react with adsorbed mercury to form Hg(NO3)2.Cu and Mn atoms are identified as the active sites for the adsorption of NO and Hg0.There is a strong interaction between NO and CuMn2O4 surface,which is closely associated with the orbital hybridization of Cu,Mn,and N atoms.