CATALYTIC PROPERTIES AND SURFACE-STATES OF COBALT-CONTAINING OXIDATION CATALYSTS

The catalytic total oxidation of methane was performed on various catalysts consisting of cobalt oxide (Co3O4) deposited on alumina-based supports. During the tests, deactivation occurred mainly because of the reactivity of the active phase towards the support, leading to a poorly active cobalt aluminate. Ageing was also performed in order to study the stability of the catalysts. Physico-chemical techniques were used to define more precisely the causes of the deactivation. Modifications of the nature of the cobalt species present on the surface of the catalyst were followed by X-ray photoelectron spectroscopy. Under the conditions used, the best catalyst was Co3O4 deposited on a thermostable, i.e. high-temperature-resistant, spinel for which tetrahedral sites able to accommodate Co2+ cations are occupied by Zn2+ cations. © 1990.