CaO-Enhanced Hematite Oxygen Carrier for the Study of the Characteristics of Flour Chemical Looping Gasification

This study synthesized Ca-modified hematite oxygen carriers (OCs) via the impregnation method and investigated their performance in the chemical looping gasification of flour at 900 °C. The results indicated that CaO modification led to the formation of Ca2Fe2O5 in the oxygen carriers. When the hematite/CaO mass ratio was optimized to 4:1, the proportion of combustible gases in the product gas reached 50%. With the increase in the flour-to-oxygen carrier mass ratio, the CO2 yield rose, while the quality of combustible gases declined. The increase of water content in flour will increase the yield and quality of gas components. Quantum chemical calculations revealed that H2 exhibits stronger adsorption at Fe sites on Ca2Fe2O5 (001) than on Fe2O3 (001), confirming that CaO-modified hematite enhances the oxygen carrier activity. H2 dissociation on Ca2Fe2O5 forms Fe–H and O–H bonds, promoting the formation of Fe and H2O alongside surface oxygen dissociation.