N2O decomposition over K-promoted Co-Al catalysts prepared from hydrotalcite-like precursors

N2O decomposition was investigated over a series of K-promoted Co-Al catalysts. The activity tests showed that doping with K greatly enhanced the catalytic activity of the Co-Al catalyst, and the enhancement was critically dependent on the amount of K and the calcination temperature. When the catalyst had a K/Co atomic ratio of 0.04 and was calcined at 700–800 °C, a full N2O conversion could be reached at a reaction temperature of 300 °C. Moreover, even under the simultaneous presence of 4% O2 and 2.6% water vapor, such high-temperature treated K/Co-Al catalyst exhibited high reactivity and stability, with the N2O conversion remaining at a constant value of 92% over 40 h run at 360 °C. In contrast, non-doped Co-Al catalyst showed a severe activity loss under such reaction conditions. A combination of characterization techniques was employed to reveal the promoting role of K and the effect of calcination temperature. The results suggest that doping with K increases the electron density of Co and weakens the Co–O bond, thus promoting the activation of N2O on the Co sites and facilitating the desorption of oxygen from the catalyst surface. High-temperature calcinations made the desorption of O2 proceed more readily.