Optimized conditions for reduction of iron (III) oxide into metallic form under hydrogen atmosphere: A thermodynamic approach

Abstract

Incomplete reduction of Fe2O3(s) iron oxide into metallic Fe(s), under hydrogen, is a challenge for iron-based catalysts limiting their industrialization for methane reforming or decomposition. This work provides thermodynamic models generated using the HSC 7.1 Chemistry software, based on minimization of total Gibbs free energy and provides amount of species resulting from the reduction of iron oxide under hydrogen. Molar ratios of Fe2O3 to H2(g) were varied from stoichiometric till hydrogen excess. An optimum molar ratio for highest reduction degree of iron oxides into metal was defined. Results show that direct reduction of Fe2O3(s) into Fe(s) is not possible, but a series of H2-induced reduction steps along with other side-reactions take place yielding, partially reduced iron oxides species. An optimized Fe2O3:H2 molar ratio exceeding 0.25:3 is needed to favor reduction of FeO(s) into Fe(s)0. For validation, simulated values were compared with experimental ones from literature (reduced amounts of iron oxide).