强化SCR脱硝催化剂转化零价汞的初步研究

Preliminary Study on Mercury Conversion Performance of Modified SCR Catalyst

常规的选择性还原脱硝(SCR)催化剂对烟气中的零价汞具有一定的催化氧化作用,从而有利于提高下游的除汞效率。但在烟气HCl浓度较低时,SCR催化剂对燃煤烟气中的零价汞催化氧化效果较差。为了提高SCR催化剂对零价汞的催化氧化效果,在现有SCR催化剂基础上,通过负载其它金属元素的方法,对其进行改性掺杂。结果发现,负载锰氧化物的Mn/SCR催化剂,对零价汞的催化氧化作用明显提高,而将其再掺杂Mo后,其催化氧化性能得到更进一步提高。在反应温度350℃的条件下,加入7.5 mg/m3HCl,Mo-Mn/SCR对零价汞的催化氧化效率接近90%,而常规SCR催化剂只有35%左右。另外,Mo只有在与Mn结合使用,其促进作用才能较显著地体现出来。对改性后的SCR催化剂的脱硝性能研究表明,掺杂Mo-Mn元素对于SCR的脱硝性能无明显影响。

Conventional SCR catalysts show a poor catalytic oxidation efficiency of elemental mercury（Hg0） emitted from coal-fired flue gas.To enhance the co-benefit of SCR catalyst for both NO removal and Hg0 conversion,SCR catalyst was doped with various elements and Mn was found to be the better,and cooperation of Mo on Mn doped SCR catalyst showed the highest efficiency among the employed catalysts.Under the condition of temperature 350 ℃ and 7.5 mg/m3 HCl,Hg0 oxidation efficiency over Mo-Mn/SCR catalyst was up to 90%,while the conventional SCR catalyst was only about 35%.Results also indicated that doping Mo-Mn on SCR displayed insignificant effect on NOx removal efficiency.