Enhanced performance of chemical looping combustion of methane with Fe2O3/Al2O3/TiO2 oxygen carrier

Abstract

Iron-based oxygen carriers supported on alumina or alumina/titania were prepared and evaluated for chemical looping combustion of methane. The reduction conversion of Fe₂O₃/Al₂O₃ and Fe₂O₃/Al₂O₃/TiO₂ particles was markedly increased with increasing inlet concentration and was slightly enhanced by elevated operating temperatures. According to the shrinking core model, the mass transfer coefficients (k_g) of Fe₂O₃/Al₂O₃ and Fe₂O₃/Al₂O₃/TiO₂ reduction with methane are found to be 0.07 and 0.12 mm s⁻¹. Complete combustion of methane is almost achieved for experiments conducted with Fe₂O₃/Al₂O₃ and Fe₂O₃/Al₂O₃/TiO₂ operated as the Fe₂O₃/CH₄ molar ratio reached about 5.4 and 4.4, respectively. Carbon deposition during methane combustion was avoided by using Fe₂O₃/Al₂O₃/TiO₂ as an oxygen carrier. More heat was generated for the combustion of methane by Fe₂O₃/Al₂O₃/TiO₂ oxygen carriers because methane more fully reacted with the Fe₂O₃ contained in the Fe₂O₃/Al₂O₃/TiO₂ oxygen carriers.