Disproportionation of CO on iron-cobalt alloys—I: Thermodynamic study

Catalyst poisoning observed during carbon formation by CO disproportionation can be related to competing carbiding and oxidizing reactions. Hence the thermodynamic stability of the catalytic metal (Fe, Co or Ni) under the conditions of the disproportionation is essential to prevent the formation of oxides or carbides catalytically inactive. We show that alloying the metal, which decreases its thermodynamic activity, increases the (T, p_co, p_co2) domain of its stability. A thermodynamic approach of the carbon-oxygen-iron cobalt alloy system predicts that a maximum expansion of the domain of stability of the metallic phase would be obtained with an alloy containing 50% cobalt, 50% iron. These results are discussed by comparison with some previous experimental results.