Kinetic modeling of CO oxidation over La1−xAxMn0.6Cu0.4O3 (A = Sr and Ce) nanoperovskite-type mixed oxides

In this paper, catalytic oxidation of CO over the perovskite-type oxides La1−xAxMn0.6Cu0.4O3 (A = Sr and Ce, x = 0, 0.1, 0.2, 0.3 and 0.4) was investigated. The catalysts were synthesized by sol–gel auto-combustion method and were further characterized by XRD, BET, FT-IR, H2-TPR and SEM. XRD patterns revealed that the oxides were single-phase perovskite-type oxides. Traces of Cu2O3, Sr2O3 and Ce2O3 were also detected in perovskites with high contents of Sr and Ce. Specific surface areas of perovskites were also determined to be about 16 and 32 m2/g. Reducibility of the perovskites, also, is strongly affected by substitution of La in A site by Sr and Ce. Perovskite catalysts show a high activity in catalytic oxidation of CO; substitution of Sr and Ce further enhanced CO oxidation activity. Highest activity was achieved by La0.7Ce0.3Mn0.6Cu0.4O3: Nearly complete elimination of CO was achieved at 145 °C with this catalyst. Kinetic studies for CO oxidation were performed based on Langmuir–Hinshelwood mechanisms. According to kinetic calculations, the most probable mechanism is the LH–OS–ND (adsorption of the reagents on same types of sites and non-dissociative adsorption of oxygen) which can predict the experimental data with correlation coefficient of R2 = 0.9933.