Thermodynamics of oxidation of an alumina-supported cobalt catalyst by water in F-T synthesis

摘要

H2O and H-2 are the product and the reactant respectively in Fischer-Tropsch (F-T) synthesis reaction, at the same time they are the reactant and the product respectively in the oxidation of cobalt. The thermodynamics of the oxidation of cobalt metal was analyzed using thermodynamic data in the reaction process of F-T synthesis. Direct oxidation of cobalt oxides by water cannot happen spontaneously under the real conditions of F-T synthesis because of the positive value of Delta G, which becomes larger and larger with the increase of temperatures. However, with the participation of alumina used as catalyst support, oxidation of cobalt by water may occur spontaneously because of the negative value of Delta G. Moreover, the pressure equilibrium constants are all less than the thermodynamic equilibrium constants, indicating that the oxidation of cobalt can be spontaneous completely under industrial and laboratory conditions. (C) 2015 Elsevier B.V. All rights reserved.