The Structure and Properties of Supported Cobalt Catalysts

Abstract 1) The chemical states of cobalt in the supported catalysts may be classified into two types. One is the type in which the cobalt is not combined with the carrier but remains free on its surface. In the other type, cobalt oxide forms a complex with the carrier and resists reduction by hydrogen. 2) The ratio of the amounts of the two types varied both with the kind of carrier and with the method of preparation used. 3) The hydrothermally-formed cobalt-alumina and cobalt-silica catalysts form CoAl2O4 and cobalt hydrosilicate compounds respectively. 4) The course of the reduction of cobalt oxide in the catalyst is as follows: In the temperature range from 200 to 300°C, the cobalt(II, III) oxide is mainly reduced to cobalt(II) oxide, and later cobalt(II) oxide is reduced to β-Co between 300 and 500°C. The reduction temperature of cobalt(II, III) oxide is different for the various types of catalysts. 5) The catalyst which consists of a complex between the metal and its carrier-oxide is less active than the free metal catalyst for the hydrogena-tion reaction, and it is almost completely inactive in the hydrogenolysis reaction. 6) The results of the various analyses of the supported cobalt catalysts are in good agreement with one other.