基于Mn-MOF制备MeO_(x)/MnO_(x)催化剂的低温NH_(3)-SCR活性研究

Investigation of low temperature NH_(3)-SCR activity of MeOx/MnOx catalyst prepared based on Mn-MOF

采用不同金属硝酸盐浸渍Mn-MOF前体制备一系列MeO_(x)/MnO_(x)(Me=Co,Cr)复合金属氧化物催化剂用于低温NH3-SCR反应。分析金属掺杂和空速对锰基催化剂脱硝效率和N_(2)O生成量的影响。通过XRD、SEM、N2吸附-脱附、XPS、H_(2)-TPR、NH3-TPD等表征测试对制得的催化剂物理化学性质进行分析,结果表明,两种金属掺杂可不同程度上改善MnO_(x)脱硝性能和抗硫性能。与MnO_(x)催化剂相比,掺杂催化剂的外观呈现无规则的多孔结构。更大的比表面积为活性分子提供更多的活性位点,有利于脱硝反应进行。掺杂催化剂中Mn元素相以Mn_(3)O_(4)相为主,且峰强度较低,表明Mn元素相呈现高分散态。掺杂金属与锰氧化物产生相互作用,改变了锰元素的价态,提高了Mn^(4+)和表面氧的含量。金属离子掺杂增强了催化剂的氧化还原性能,改善了MnO_(x)的表面活性。因此,金属硝酸盐浸渍Mn-MOF前体法在制备低温NH3-SCR脱硝催化剂领域具有很好的应用前景。

A series of MeO_(x)/MnO_(x)(Me=Co,Cr)mixed metal oxide catalysts were prepared by impregnating the Mn-MOF precursors with different metal nitrates.The catalytic activities of catalysts were tested in a lowtemperature NH3-SCR denitrification device.The effects of different metal doping and gaseous hourly space velocity(GHSV)were analyzed about the denitrification efficiency and N_(2)O production of manganese-based catalyst.In addition,the physicochemical properties of the prepared catalysts were analyzed by XRD,SEM,N2 adsorption-desorption,XPS,H_(2)-TPR,and NH3-TPD.The results showed that the doping of the two metals improved the denitrification performance and sulfur resistance of the MnO_(x)catalyst to different degrees.Compared with the MnO_(x)catalyst,the doping catalysts had an irregular porous structure.The large specific surface area of the doped catalysts provided more active sites for the active molecules,which were beneficial to the denitrification reaction.The Mn element phase in the doped catalysts was dominated by the Mn_(3)O_(4)phase.Due to its low peak intensity in XRD results,it indicated that the Mn element phase showed a highly dispersed state.The doped metal interacted with manganese oxide and changed the valence state of manganese.As a result,the Mn^(4+)and the surface oxygen content were increased of the catalysts.In addition,the doping of metal ions enhanced redox properties and improved surface activity of the MnO_(x)catalyst.Therefore,the preparation of low-temperature NH3-SCR denitrification catalysts by metal nitrate impregnation of Mn-MOF precursors had great application prospect.