Ni-Fe bimetallic oxides on La modified A1_2O_3 as an oxygen carrier for liquid fuel based chemical looping combustion

摘要

Ni-Fe on La-gamma Al2O3 based oxygen carriers were synthesized using a sequenced incipient wetness method. The prepared oxygen carrier was characterized using SEM-EDS, N-2 adsorption, XRD, TPR and NH3-TPD. The SEM and N-2 adsorption isotherms show excellent dispersion of NiO on the La2O3-Al2O3 indicating the positive effects of La addition on gamma Al2O3 support. The TPR peaks below 600 degrees 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 mu mol 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 degrees C.