Co₃O₄ supported on Sr doped hydroxyapatite as catalysts for N₂O catalytic decomposition

Hydroxyapatite (HAP) and a series of Sr-doped HAP supports (Ca₉Sr₁, Ca₈Sr₂ and Ca₇Sr₃) were synthesized by co-precipitation method, and the supported Co₃O₄ catalysts were prepared by impregnation method. The prepared samples were characterized by XRD, N₂-physisorption, Raman, FT-IR, H₂-TPR, XPS, O₂-TPD and CO₂-TPD, and the N₂O decomposition performance of the catalysts were studied using a continuous flow microreactor. The experiment results show that the order of catalytic activity is Co/Ca₈Sr₂ > Co/Ca₉Sr₁ > Co/HAP > Co/Ca₇Sr₃. When the Sr/Ca ratios are 1∶9 and 2∶8, the structure of the HAP carrier is better maintained. Sr doping not only promotes the dispersion of Co₃O₄, but also increases the number of Co²⁺ and surface oxygen vacancies on the catalysts. Furthermore, an appropriate amount of Sr doping can increase the surface alkali content and basic site density of the catalyst, which is more conducive to N₂O activation and O₂ desorption.