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

Abstract

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.