Ni-Fe bimetallic oxides on La modified Al₂O₃ as an oxygen carrier for liquid fuel based chemical looping combustion

Ni-Fe on La-γAl₂O₃ based oxygen carriers were synthesized using a sequenced incipient wetness method. The prepared oxygen carrier was characterized using SEM-EDS, N₂ adsorption, XRD, TPR and NH₃-TPD. The SEM and N₂ adsorption isotherms show excellent dispersion of NiO on the La₂O₃-Al₂O₃ indicating the positive effects of La addition on γAl₂O₃ support. The TPR peaks below 600 °C confirms the formation of mainly NiO species on La₂O₃-Al₂O₃. The NH₃-TPD indicated the presence of both weak and strong acid sites on the support. The NH₃ desorption kinetics provided information on the type of NH₃ desorption including an estimate of the desorption energy. The optimum properties were found on the oxygen carrier with 5 wt% nickel loading, which exhibited the highest oxygen transferability (0.055 g O/g) as well as strong acid sites (105 μmol NH₃/g). Finally, the performance of the oxygen carrier was evaluated in a CREC riser simulator using hexane as a model compound for liquid fuel. The prepared oxygen carrier exhibited an excellent performance, which was reflected by the high CO₂ yield (0.70) observed at a temperature of 650 °C.