Synergistic effect to enhance hydrogen generation of Fe2O3/Ce0.8Sm0.1Gd0.1O1.9 in water-gas shift with chemical looping

Summary Fe 2 O 3 is recognized as a promising oxygen carrier, but the susceptibility to sintering over the redox cycles limits its application. Although depositing Fe 2 O 3 on CeO 2 can simultaneously improve the activity and durability, the formation of CeFeO 3 will decrease the oxygen capacity and thus the efficiency of chemical looping water-gas shift reaction. Doping foreign elements can effectively mitigate the reaction between Fe 2 O 3 and CeO 2 and improve redox reactivity. This work employs Gd 3+ and Sm 3+ as doping elements and investigates the doping effect on hydrogen generation of Fe 2 O 3 /CeO 2 in water-gas shift with chemical looping. The characterizations demonstrate that both Gd and Sm are incorporated into the lattice of CeO 2 and increase the oxygen defect concentration, which boosts the redox reactivities. In addition, the interaction between the dopants and CeO 2 promotes the reduction depth by suppressing the solid reaction between Fe 2 O 3 and CeO 2 and improves the reoxidation reaction between reduced oxygen carriers with steam. As a result, Fe 2 O 3 /Ce 0.8 Sm 0.1 Gd 0.1 O 1.9 shows a high hydrogen yield (8.73 mmol.g −1 ) and hydrogen production rate (582.2 μmol.g −1 .min −1 ), which is 1.67 times higher than that of Fe 2 O 3 /CeO 2 . The performance remains stable over 40 cycles. The introduction of foreign cations may provide an effective method and significantly impact the oxygen carrier design.