Theoretical study of oxidation–reduction reaction of Fe2O3 supported on MgO during chemical looping combustion

• Published in: Applied surface science Vol. 266; pp. 350 - 354
• Main Authors: Qin, Wu, Chen, Qiuluan, Wang, Yang, Dong, Changqing, Zhang, Junjiao, Li, Wenyan, Yang, Yongping
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.2013; Elsevier
• Subjects: Chemical-looping combustion; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; DFT; Exact sciences and technology; Fe2O3; MgO; Physics; Chemical-looping combustion; DFT; MgO; CO; Fe2O3; Inorganic compounds; Iron oxide; Magnesium oxide; Transition element compounds; Theoretical study; Combustion; O; Redox reactions; Density functional method; Fe
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2012.12.023

► Properties of Fe2O3/MgO composite. ► CO/O2 adsorption on Fe2O3/MgO composite. ► Mechanism of CO oxidation by Fe2O3 related to the fuel reactor of the CLC system. ► Mechanism of Fe2O2 oxidation by O2 related to the air reactor of the CLC system. We applied density-functional theory (DFT) in periodic system to investigate the two reactions (CO+Fe2O3/MgO→CO2+Fe2O2/MgO, O2+Fe2O2/MgO→O+Fe2O3/MgO) in chemical looping combustion system. While Fe2O3 was supported on MgO(100) surface Fe2O3 gathered together to form a cluster shape on MgO(100), denoted as Fe2O3/MgO, where the Fe2O3 was activated by MgO(100). Then CO interacted with Fe2O3/MgO and carbonate generated during a stepwise reaction with the calculated maximum barrier energy of 0.95eV, far less than that of the reaction between CO and the pure Fe2O3 cluster (2.59eV). CO was oxidized by Fe2O3/MgO and then Fe2O3/MgO transformed into the reduced state Fe2O2/MgO, corresponding to the reaction in the fuel reactor in the CLC system. Then the breaking of the adsorbed O2 molecule on Fe2O2/MgO made an O atom bind to a Fe site with the barrier energy of 0. 20eV, which played as the key step for the oxidizing of Fe2O2/MgO by O2 into Fe2O3/MgO, corresponding to the reaction in the air reactor in the CLC system.