Controlling lattice oxygen activity of oxygen carrier materials by design: A review and perspective

Chemical looping is a class of emerging process intensification technologies that enable emission reduction of a wide range of chemical processes. The performance of oxygen carrier materials is critical to the effectiveness of the chemical looping processes. Over the past two decades, understanding of how oxygen carriers behave over chemical looping cycles continued to improve, leading to encouraging advancements in recent years, including several newly developed chemical looping applications showing promise to achieve lower CO2 footprints compared to conventional reactor technologies. Amongst the key material design considerations, having appropriate lattice oxygen activity is critical for maximising the product yield and selectivity of chemical looping processes. In this minireview, material design approaches enabling the development of oxygen carriers with well-defined and well-regulated lattice oxygen activity are overviewed and critically assessed. Besides the significant progress made, there remain key knowledge gaps in the area of lattice oxygen engineering. Lastly, the potential roles which computational tools could play in designing oxygen carriers with targeted lattice oxygen activities are discussed.