2064.     LARSON, A. T., AND BROOKS, A. P.  Ammonia Catalysts.  Ind. Eng. Chem., vol. 18, 1926, pp. 1305-1307; Chem. Abs., vol. 21, 1927, p. 802.

        Fe, Co, Ni, W, and Mo have been studied in the temperature range 450°-550° as NH₃ synthesis catalysts.  Ni and Co were found inactive; at 550° W and Mo were the most active, and at 450° Fe and a mixture of Fe and Mo.  The studies with Fe included a study of the promoter action of 16 difficultly reducible oxides added singly to the Fe.  Only 5 of these oxides of Al, Si, Zr, Tl, and Cl, had any promoter action under the conditions used.  Mixing these oxides showed that when the oxides are closely related chemically, the combined effect is about the same as that given by each constituent.  If the oxides differ considerably in their basic or acidic properties, the promoter action of the mixture is greater than that of either constituent alone.  Promoters of mixtures of potash-alumina, potash-silica, and potash-zircon produced very active Fe catalysts.