Direct N2O decomposition over La2NiO4-based perovskite-type oxides

Direct decomposition of N2O by perovskite-structure catalysts including La2NiO4, LaSrNiO4, and La0.7Ce0.3SrNiO4 was investigated. The catalysts were prepared by the Pechini method and characterized by x-ray diffraction (XRD), BET, scanning electron microscopy (SEM), and O-2-TPD. Experimental results indicate that the properties of La2NiO4 are significantly improved by partially substituting La with Sr and Ce. N2O decomposition efficiencies achieved with LaSrNiO4 and La0.7Ce0.3SrNiO4 are 44 and 36%, respectively, at 400oC. As the temperature was increased to 600oC, N2O decomposition efficiency achieved with LaSrNiO4 and La0.7Ce0.3SrNiO4 reached 100% at an inlet N2O concentration of 1,000 ppm, while the space velocity was fixed at 8,000 hr(-1). In addition, effects of various parameters including oxygen, water vapor, and space velocity were also explored. The results indicate that N2O decomposition efficiencies achieved with LaSrNiO4 and La0.7Ce0.3SrNiO4 are not significantly affected as space velocity is increased from 8,000 to 20,000 hr(-1), while La0.7Ce0.3SrNiO4 shows better tolerance for O-2 and H2O(g). On the other hand, N-2 yield with LaSrNiO4 as catalyst can be significantly improved by doping Ce. At a gas hour space velocity of 8,000 hr(-1,) and a temperature of 600oC, high N2O decomposition efficiency and N-2 yield were maintained throughout the durability test of 60 hr, indicating the long-term stability of La0.7Ce0.3SrNiO4 for N2O decomposition. [GRAPHICS]