Oxidative performance and surface properties of Co-containaing mixed oxides having the K2NiF4 structure

The complexed oxides Nd2–xSrxCoO4 (0.4≤x≤1.2) and LnSrCoO4 (Ln = Pr, Nd Eu) having the K2NiF4 structure were synthesized by the citric-acid-complexion method. The results of XRD confirmed that the complexed oxides have the K2NiF4 structure. Other phases were found when x = 0.4 and x = 1.2. The influences of Nd, Pr, Eu on the activities of LnSrCoO4 for CO oxidation and C3H8 oxidation were different. The oxidative activities average crystalline size and lattice distortion of Nd2–xSrxCoO4 increased with increasing x value in the oxides. When x > 0.8, the lattice distortion decreased with increasing x. The results of O2–TPD showed that amount of desorption of lattice oxygen over Nd2–xSrxCoO4 increased with x, however, the amount of chemidesorption of oxygen decreased. With increasing x, the high-temperature reduction peak in H2–TPR of Nd2–xSrxCoO4 shifted to higher temperatures, however, the low-temperature reduction peak shifted to lower temperatures, which showed that the activity of the lattice oxygen and the thermal stability of Nd2–xSrxCoO4 increased with increasing x.