Chemical-looping methane hydrogen production performance of Cu, La, Ce modified Fe₂O₃/Al₂O₃ oxygen carrier

Chemical looping methane steam reforming (CL-MSR) has garnered significant attention owing to its ability to sequentially produce syngas with high selectivity and high-purity hydrogen through redox cycling. To overcome the limitations of single iron-based oxygen carriers, including poor cycling stability, low reactivity and susceptibility to sintering, this study employed a dip-coating method to modify Fe2O3/Al2O3 oxygen carriers by incorporating three distinct metal additives: Cu, La and Ce. The composite oxygen carriers were systematically characterized and evaluated under redox conditions to investigate the structure-activity relationships between the physicochemical properties, reactivity, and hydrogen production performance. Results revealed that the spinel-phase CuFe2O4 exhibited higher reactivity than the perovskite-phase LaFeO3 and CeO2, promoting the deeper reduction of Fe2O3. Fe58Cu2Al exhibited an oxygen storage capacity as high as 6.5 mmol/g. During the CH4 reaction stage, Fe58Cu2Al achieved the highest oxygen loss of 12.1 g/100 g oxygen carrier, accompanied by a syngas yield of 5.15 mmol/g—1.33 times and 1.59 times greater than that of Fe60Al. In the hydrogen production stage, the 2% Cu-modified oxygen carrier demonstrated optimal performance, yielding 5.13 mmol/g of hydrogen, which was 1.51 times that of the pristine sample. Even after ten cycles, the H2 yield remained at 3.61 mmol/g, surpassing the single-cycle output of the pristine sample and the H2 purity consistently exceeded 98%.