Preparation of Co-Al mixed oxide supported gold catalysts and their catalytic activity for N2O decomposition

Au/Co-Al catalysts were prepared by using the ion-exchanged and co-precipitation methods, and their activities for the catalytic decomposition of N₂O were tested. BET, XRD, and H₂-TPR techniques were used to characterize the catalysts. The results show that the activity of Au/Co-Al catalyst prepared by using ion-exchanged method is higher than that using co-precipitation method. For the catalysts prepared by ion-exchanged method, the effects of preparation parameters, such as Au loading, pretreatment of HAuCl₄ solution, and calcination temperatures, upon N₂O conversion were investigated. The optimal preparation parameters of Au/Co-Al catalysts are that 1.1% of Au loading, pH value of HAuCl₄ solution adjusted to 9.0, and 300℃ of calcination temperature. It is indicated that the addition of Na species in Co-Al mixed oxide promoted the reduction of Co³⁺ to Co²⁺ and enhanced the catalytic activity for N₂O decomposition.