Enhancing chemical looping oxygen uncoupling capacity of Ca-Mn based perovskite oxygen carrier materials by co-doping Co/Mg

Abstract

Ca-Mn based perovskites are particularly suitable for large-scale chemical looping applications due to their low cost and tunable performance characteristics in chemical looping with oxygen uncoupling (CLOU). However, these materials still struggle to simultaneously achieve long-term stability and efficient oxygen uncoupling performance. Herein, an innovative Co/Mg co-doping strategy was proposed. The optimization threshold for the single Co doped system could achieve 110% enhancement in oxygen uncoupling performance compared to undoped CaMnO₃, but exhibiting irreversible phase separation and severe sintering above 800 °C. The Co/Mg co-doped system was further developed to significantly improve high-temperature cycling stability, maintaining the superior oxygen uncoupling performance. It was found that Mg doping substantially enhanced the activity of the primary redox pairs (Mn⁴⁺/Mn³⁺, Co³⁺/Co²⁺), demonstrating the stable oxygen uncoupling capacity of 1.67 wt%–2.12 wt% at 900 °C. The developed Ca-Mn based perovskite oxygen carrier achieves an optimal balance between efficient oxygen uncoupling capacity and high-temperature structural stability, providing a novel material for enhanced fuel conversion for CLOU application.

Keywords

chemical looping with oxygen uncoupling / oxygen carrier / Ca-Mn based perovskite / co-doping Co/Mg

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