Hydrogen production by a Fe-based oxygen carrier and methane-steam redox process: Thermodynamic analysis

The performance of iron oxide FeO/Fe3O4 redox pair as an oxygen carrier was investigated for hydrogen (H2) and/or syngas (H2+CO) production through a methane-steam chemical looping process using thermodynamic analysis and process simulation by Aspen Plus to find optimal reactions conditions (ORC). The reaction system was divided in two reactors. In the fuel reactor (FR) the following reactions were targeted: ¼ CH4(g) + Fe3O4 = 3FeO + ¼ CO2(g) + ½ H2O(g) and CH4(g) + Fe3O4 = 3FeO + 2H2(g) + CO(g) where the CH4/Fe3O4 molar ratio was varied from 0.25 to 1 and 300-900 °C. In the steam oxidation reactor (SR), the solid products from FR were combined with steam to produce: 3FeO + H2O(g) = Fe3O4 + H2(g) in a T range of 300-900 °C. Results indicate that ORC in the reduction reactor consists in T = 650-700 °C and CH4/Fe3O4 = 0.75-1, While for the SR were T = 520-600 °C.