K改性Ni-Co-Al三元复合氧化物催化分解N2O

制备了(Ni+Co)/Al=3、Ni/Co=0.2(原子比)的NiCoAl三元类水滑石样品,焙烧获得NiCoAl复合氧化物,表面浸渍K₂CO₃溶液制备了K改性催化剂,用于N₂O分解反应,考察了K负载量、焙烧温度等制备参数和O₂、H₂O等反应气氛对催化剂活性的影响。用BET、XRD、H₂-TPR、XPS等技术表征了催化剂的组成结构。结果表明,K的表面改性提高了催化剂对N₂O分解反应的催化活性,其中,400℃预焙烧NiCoAl类水滑石制得复合氧化物,初湿浸渍K₂CO₃溶液,K的负载量为K/(Ni+Co)=0.05,400℃ 再焙烧制备的催化剂活性较高,有氧有水条件下500℃ 反应时N₂O可完全分解;在NiCoAl复合氧化物表面负载K₂CO₃组分,降低了催化剂表面Co、Ni元素的电子结合能,弱化了表面Co-O、Ni-O化学键,从而提高了催化剂活性和抗水性能。

Catalytic decomposition of N2O over potassium promoted Ni-Co-Al ternary mixed oxides

NiCoAl ternary mixed oxides derived from hydrotalcite-like compounds(HLc) with(Ni+Co)/Al atomic ratio of 3 and Ni/Co of 0.2 were incipiently impregnated by potassium carbonate solution to prepare K-promoted NiCoAl mixed oxides for catalytic decomposition of N2O.The effects of catalyst preparation parameters such as K loadings,calcination temperatures,and reaction atmospheres on catalytic activity were investigated.The catalysts were characterized by BET,XRD,H2-TPR,and XPS techniques.The results show that the catalytic activity of NiCoAl mixed oxides is largely enhanced by the addition of K species in the presence of oxygen and steam,and the optimal catalyst preparation parameters are K/(Ni+Co) atomic ratio of 0.05 and calcination temperature of 400 ℃.XPS and H2-TPR data show that the electron binding energy of active Co3O4 and NiO species over K-promoted catalysts surface shifted to lower value,indicating the surface Co-O and Ni-O bonds were weakened,thus the reduction peaks of Co3+ to Co2+ and Ni2+ to Ni0 moved to lower temperature,and the catalytic activity and resistance towards water is improved.