Reactivity and stability optimization of oxygen carriers in chemical looping systems

Chemical looping technology (CLT) produces flue gas enriched with carbon dioxide, which can then be captured, utilized, or stored. The oxygen carrier (OC) plays a central role in the chemical looping process, but its low activity and short lifespan hinder its industrial application. The existing review literature on CLT primarily focuses on the application of specific OCs and their developmental trends, but lacks a comprehensive summary of OC activity and cycle life. To address the gaps in existing literature, this paper explores the activity and recycling lifespan of OCs in relation to their defects. Furthermore, strategies to improve OC reactivity are discussed, beginning with the selection of active species aided by Ellingham diagrams. The advantages of non-metallic and solid waste-based OCs in chemical looping reactions are compared, along with a summary of strategies to enhance their activity. To prolong the service life of OCs, this paper outlines the primary mechanisms of carrier failure, which are primarily attributed to the combined effects of wear and stress. For different types of stress, targeted solutions are proposed: a supported carrier approach for chemical stress, a core-shell structure for mechanical stress, and elemental doping for thermal stress. Finally, the paper explores the application prospects of solid waste-based OCs and their development towards achieving a tripartite stress equilibrium, thus opening new avenues for the practical application of OCs. These studies contribute to advancing the efficient utilization of chemical looping systems in environmental protection and sustainable energy supply.