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

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 (kg) 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.