Effect of preparation parameters on the catalytic performance of hydrothermally synthesized Co₃O₄ in the decomposition of N₂O

With hexadecyl trimethyl ammonium bromide (CTAB) as the template, cobaltosic oxide precursors were hydrothermally synthesized. Co₃O₄ catalysts were then prepared by calcining the cobaltosic oxide precursors, which was further modified by impregnation with K₂CO₃ solution and used in the decomposition of N₂O. The catalysts were characterized by means of X-ray diffraction (XRD), nitrogen physisorption, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H₂-TPR), and oxygen temperature-programmed desorption (O₂-TPD); the effect of CTAB concentration, CTAB/cobalt molar ratio and urea/cobalt molar ratio on the catalytic activity of Co₃O₄ was investigated. The results indicated that the Co₃O₄ catalyst prepared by using 0.05 mol/L CTAB solution, with a CTAB to cobalt molar ratio of 1 and a urea to cobalt molar ratio of 4, exhibits high activity in N₂O decomposition. The catalytic performance of Co₃O₄ can be further enhanced by modifying with K. Over the 0.02 K/Co₃O₄ catalyst, the N₂O conversion remains over 91% at 400 ℃ after conducting the N₂O decomposition reaction for 50 h in the presence of oxygen and steam.