The Effect of Promoters Ca、Sr and Ba to CO Oxidation on the Co/γ-Al₂O₃ Catalyst（Ⅰ）

A series or Co-M /γ-Al₂O₃ catalysts （M =Ca、Sr and Ba, Co₃O₄/Al₂O₃= 8wt%,M/Co = 15mol%） were prepared by wetness impregnation method. The alumiha was impregnated with solution of Co（NO₃）₂·6H₂O and M（NO₃）₂（M = Ca、Sr or Ba） and was calcincd at 400℃ or 600℃ for 3h. The oxidation activity of CO was determined in a gas flow System. The effect of promoters Ca. Sr and Ba was studied by XRD、DTA、 TPR and BET surface measurements. As a result, the temperature of conversion 100% of CO decreased about 20-100℃ on the samples contained Ca、Sr and Ba. The activity or the samples calcined at 400℃ was better than that at 600℃,because some phases of Co²⁺-A1³⁺ spinel were formed at 600℃ calcination temperature.The order or promotivc effect is Ba＞Sr＞＞Ca. The main active phases were surface Co³⁺ and Co₃O₄. All promoters Ca、Sr and Ba existed as nitrates.The reason that Ba（NO₃）₂ exhibited pronounced effect was discussed.