掺杂元素对Mn基催化剂SCR性能及抗硫性能的影响

Influence of different doped metal cations on the activity and SO2 resistance of Mn based catalysts for NH3-SCR reaction

采用溶胶凝胶法制备M-Mn/TiO2催化剂,M=Fe、Ce、Ni、Sm、Cu,考察掺杂元素对催化剂SCR性能和抗硫性能的影响,并采用XRD、H2-TPR表征手段考察掺杂组分对催化剂性质的影响。结果表明,掺杂金属元素后,催化剂的晶粒尺寸和还原性能发生变化,表现为Fe、Ni的掺杂明显降低催化剂粒径尺寸而Ce、Sm、Cu的掺杂增加了粒径尺寸;Cu和Ni的掺杂有利于提高催化剂的还原性能。SCR实验结果表明,Cu、Sm的掺杂在整个反应温度区间内都会抑制催化剂脱硝活性,而Fe、Ni、Ce的掺杂主要抑制低温活性,在高温阶段则会促进反应的进行。掺杂金属元素后催化剂T80活性窗口顺序为:Fe-Mn/TiO2>Ni-Mn/TiO2>Ce-Mn/TiO2≈Mn/TiO2>Sm-Mn/TiO2>Cu-Mn/TiO2。Sm-Mn/TiO2和Ce-Mn/TiO2能保持与Mn/TiO2基本相似的抗硫性能,但掺杂Fe、Cu、Ni会导致催化剂在较短时间内因硫中毒失活,尤其是Fe-Mn/TiO2催化剂的活性中心受SO2硫酸盐化影响最大,但是水洗再生之后其活性基本恢复,且Fe-Mn/TiO2和Ni-Mn/TiO2催化剂的抗硫中毒性能在水洗后得到提高。

The SCR performance and SO2 resistance of Mn/TiO2 catalysts doped with Fe,Ce,Ni,Sm and Cu elements synthesized by sol-gel method were investigated,and the physicochemical properties of catalysts were also characterized by XRD and H2-TPR.The results showed that the particle size and the reducibility were changed by doping elements.The particle size was decreased when Fe and Ni doped while increased when Se,Sm,and Cu doped.The modification of Cu and Ni was beneficial to the enhanced reducibility of catalysts.The SCR results exhibited that the modification of metal elements mainly inhibited the activity at low temperature whereas increased the activity at high temperature except for Cu and Sm.The T80 catalytic temperature window of catalysts after doping the metal elements followed:Fe-Mn/TiO2>Ni-Mn/TiO2>Ce-Mn/TiO2≈Mn/TiO2>Sm-Mn/TiO2>Cu-Mn/TiO2.Sm-Mn/TiO2and Ce-Mn/TiO2 kept the similar SO2 resistance with Mn/TiO2,while samples with Fe,Cu and Ni showed poor SO2 tolerance.For Fe-Mn/TiO2 catalyst,the metal active sites were easily poisoned by SO2,but the activity could be restored by the water washing method.Furthermore,the SO2 resistance of Fe-Mn/TiO2 and Ni-Mn/TiO2 could be improved after the regeneration.