摘要
研究了La_(1-1·333X)Th_XNiO_(3-λ)(0≤x≤0.75)催化剂的固态性质与催化氢氧化性能的关系。发现在LaNiO_3中掺入Th^(4+)能形成阳离子空位,稳定体系中Ni^(3+)浓度和降低氧空位的有序化程度,从而提高了催化剂的NO选择性。氨氧化制硝酸的主要活性氧种可能是定位在氧空位上的O^-离子。催化机理遵从Redox机理,阳离子空位的形成有利于Redox过程的进行。
The relationship between the physico-chemical properties and catalytic activity for ammonia oxidation of La1-1.333xThxNiO3-λ has been studied. The mixed oxides La1-1.333xThxNiO3-λ, could keep the single phase of perovskite type structure in the range of x<0.3, and both of the concentration of Ni3+ and the cation vacancy increased with increasing the x value. While in the range of x≥0.3, the NiO, ThO2,La2O3, ThO phases appeared together with the perovskite phase. The active sites for ammonia oxidation are Ni3+ and disordered oxygen vacancy, the role of the former is to adsorb and activate ammonia, and the latter is to adsorb and activate oxygen. The cation vacancy can stabilize Ni3+ and reduce the ordering level of oxygen vacancy. The catalytic reaction follows the redox mechanism.
