Effects of various catalytic promoters on the fast redox reaction of MgFe₂O₄ oxygen carrier materials for chemical looping combustion

This study focuses on improving the oxygen transfer properties of a MgFe₂O₄ oxygen carrier in chemical looping combustion by introducing the catalytic promoters gadolinium-doped ceria, palladium, and platinum. MgFe₂O₄ synthesized by solid-state reactions exhibited reversible redox behavior but suffered from agglomeration and a slow reaction rate. The introduction of palladium and platinum significantly enhanced the oxygen transfer rate in the oxidation and reduction reactions, and the palladium-incorporated composite achieved an oxygen-transfer capacity of 23.40 wt.%, which was similar to that of pure MgFe₂O₄ (23.96 wt.%). This improvement can be explained by the participation of PdO as an additional oxygen source. Gadolinium-doped ceria provided microstructural stability and suppressed agglomeration, but the oxygen-transfer rate and capacity were lower due to its oxygen storage property. The palladium-incorporated composite maintained its microstructure after redox cycling, showing excellent redox stability and oxygen transfer properties. These results demonstrate that catalytic promoters such as palladium and platinum not only accelerate the reaction rate, but also improve long-term structural stability, providing important insights into optimizing oxygen carrier materials in chemical looping combustion.