Active Form of the Catalyst for the Liquid Phase Air Oxidation of Hydrocarbons

Abstract

In the liquid phase air oxidation of hydrocarbons catalyzed by metal salts, an active catalyst is formed at the end of the induction period. In order to clarify this active catalyst, catalytic activities for the oxidation of m-xylene, and Rf values of paper chromatography were compared for several green colored cobalt catalysts of different sources. One of the catalysts was withdrawn from an oxidation reaction system of xylene catalyzed by cobaltous salt. The others were prepared by two methods: 1) reaction of cobaltous salt with hydrogen peroxide or hydroperoxide in the presence of aromatic acid and 2) reaction of cobaltous salt with benzaldehyde or perbenzoic acid.Rf values of paper chromatography were identical with these green cobalt catalysts which were different from the cobaltous salt employed as their starting materials. When these catalysts were used in the oxidation of m-xylene, the induction period was extremely shortened, which is not the case with untreated cobaltous salt.A further investigation; i.e., elementary analysis, conductometric titration and iodometry, on cobaltous adipate, cobaltous caprate and pure green catalysts prepared from these salts, indicated that the green catalyst consisted of Co2(A)3(OH)2 unit containing Co(II) and Co(III) in the ratio of 1:1.