水滑石基Ni(Mn,Cu)Fe复合氧化物的制备及其低温NH3-SCR应用

Preparation of Ni(Mn,Cu)Fe mixed metal oxides from LDH precursors and application in low-temperature NH3-SCR

为了提升NiFe复合氧化物(NiFe-LDO)催化剂的低温脱硝性能,采用尿素水热分解法将过渡金属Mn和Cu原位引进NiFe类水滑石(NiFe-LDH)层板,借助Ni(Mn,Cu)Fe类水滑石(Ni(Mn,Cu)Fe-LDH)经500℃焙烧衍生构筑Ni(Mn,Cu)Fe复合氧化物(Ni(Mn,Cu)Fe-LDO)催化剂,考察协同功能组分Mn和Cu原位引入NiFe-LDH对衍生构筑复合氧化物催化剂低温脱硝性能的影响。研究结果表明:经Mn和Cu掺杂衍生构筑的Ni(Mn,Cu)Fe-LDO催化剂呈现出更好的低温脱硝性能,NiCuFe-LDO催化剂在210~360℃时,NO转化率均超过90%,N2选择性可达95%以上;而NiMnFe-LDO催化剂在150℃时NO转化率可达90%,180℃时NO转化率接近99%,150~360℃活性温窗范围内催化剂的N2选择性均可以稳定在96%以上,同时,其还呈现较好的高空速适应性和较强的抗水抗硫性能;Mn和Cu的引入不同程度地优化了Ni(Mn,Cu)Fe-LDO催化剂的氧化还原性和酸碱性,这是因为Ni3+和Mn3+间的电子转移加速了催化剂表面氧化还原循环,导致NiMnFe-LDO具有更优异的低温NH3-SCR性能。

To improve the performance of NiFe-LDO in NH3-SCR at low temperatures,the transition metal Mn and Cu were in-situ doped into the NiFe-LDH laminates by the hydrothermal decomposition of urea.With the obtained NiMnFe-LDH and NiCuFe-LDH as precursors,the NiMnFe-LDO and NiCuFe-LDO catalysts were prepared after the calcination process at 500℃.Additionally,the effect of in-situ introduction of Mn and Cu on the denitration performances of the catalyst at low temperatures were investigated.The results show that the Mndoped and Cu-doped Ni(Mn,Cu)Fe-LDO catalysts afford better redox property and remarkable denitration activity at low temperatures.For NiCuFe-LDO catalyst,the conversion of NO exceeds 90%and the selectivity of N2 reaches more than 95%in the range of 210-360℃.Comparatively,except for its excellent N2 selectivity(>96%),NiMnFe-LDO catalyst possesses a wider active temperature window(150-360℃)and higher NO conversion efficiency(with NO conversion beyond 90%at 150℃and around 99%at 180℃).Moreover,NiMnFe-LDO catalyst also presentes good high gas hourly space velocity adaptability and outstanding resistance ability to H2 O and SO2.The introduction of Mn and Cu is beneficial to the redox as well as acid-base property optimization of Ni(Mn,Cu)Fe-LDO catalyst,which accelerates the redox cycle on the catalyst surface because of the electron transfer between Ni3+and Mn3+and thus endows the catalyst with superior denitration activity.