Effect of precipitants on the catalytic activity of Co-Ce composite oxide for N2O catalytic decomposition

Co-Ce composite oxide catalysts have been prepared by the co-precipitation method using K2CO3 (Co-Ce-A), KOH (Co-Ce-B) and NH3 center dot H2O (Co-Ce-C) as precipitants. The effect of different precipitants on the catalytic activity for N2O catalytic decomposition was investigated in a fixed-bed continuous flow reactor. The structure and properties of the catalysts were characterized by XRD, TEM, FT-IR, Raman, XRF, BET, EC, H-2-TPR and O-2-TPD. The results show that under the reaction conditions of N2O 0.1% and GHSV 10,000 h(-1), the catalyst prepared by using K2CO3 as precipitant exhibits better N2O catalytic decomposition activity than that prepared by using KOH or NH3 center dot H2O as precipitant. The XRD, TEM and BET results reveal that all the samples exist as a Co3O4 phase with the spinel structure though the precipitated precursors are different, while Co-Ce-A shows higher specific surface area and smaller crystalline size. Further characterizations results suggest that compared with Co-Ce-B and Co-Ce-C, Co-Ce-A possesses not only stronger interaction between Co and Ce species, but also higher electrical conductivity resulting from the more amount of residual K, which improves the reduction of Co3+-Co2+ and facilitates the desorption of surface oxygen species. Therefore, Co-Ce-A exhibits enhanced N2O catalytic decomposition activity.