In-Situ Microscopic Study of Morphology Changes in Natural Hematite and Cu-Spinel Particles During Cyclic Redox Gas Exposures for Chemical Looping Applications

Efficiency of the chemical looping combustion technology is adversely influenced by surface properties of oxygen carrier materials during oxidation–reduction process changes at elevated temperatures. In this work, natural hematite (Fe2O3) and alumina (Al2O3) supported Cu-spinel (CuFe2O4) oxygen carrier particles were isothermally exposed to redox gas cycles (air and 10 vol% CO–90 vol% Ar) at approximately 800 °C and studied using a high temperature confocal scanning laser microscope for real time alterations in surface morphology, roughness, and particle volume. 3D topological scans from each cyclic gas exposure indicated hematite particles exhibited noticeable volume expansion in reduction and shrinkage in oxidation, corresponding to respective phase transformations. Materials surface changes during the redox gas cycles are discussed.