Density Function Study Of Fe₂O₃Synergy With Inser In Chemical-Looping Combustion System

The accumulation of greenhouse gas in the atmosphere would impact the global change, and it has drawn increasing attention. Chemical-looping combustion is effective for CO2capture separation for its significance inherent advantages of low power consumption, which will reduce CO2gas emissions. Density functional theory (DFT) calculations were used to investigate the reactions mechanism systemly in the fuel reactor and air reactor. CO+Fe2O3and Fe2O2+O2clusters were chose for reacion model, while ZrO2(101), Al2O3(001), MgO(100) were chose for the inser.All calculations in this paper were base on package (DMol) of Material Studio, The electron exchange and correlation were treated within the generalized gradient approximation (GGA) using the PW91function. The valence electron functions were expanded into a double-numerical basis with polarizationfunctions (DNP). Here the Fe2O3cluster loads on the ZrO2(101), Al2O3(001) or MgO(100) to form composite carrier. After the chemical looping combustion of CO in the fuel reactor that corresponds to the CO oxidation reaction, and the Fe2O3is reduced into Fe2O2on the inser. Then we focus on the oxidation of the reduced oxygen carrier Fe2O2/(ZrO2, Al2O3, MgO) by O2theoretically, which corresponds to the oxidation reaction in the air reactor in the CLC system. It is found that DOS of the Fe2O3cluster supported on inser (ZrO2,Al2O3, MgO) becomes continuous with less sharp peaks, which implies that Fe2O3will be more chemically active. And bidentate carbonate species are produced by forming a new C-O bond, finally the bidentate carbonate species are dissociated from the surface with generating a CO2, While comparing the activation energy of the CO2formation on the pure Fe2O3cluster (2.590eV), the activation energy (0.826eV,1.080eV,0.980eV, respectively) of the CO2formation on Fe2O3/(ZrO2, Al2O3and MgO), which is far less than thaton the pure Fe2O3cluster, and the reaction barrier is1.139eV、0.790eV、0.200eV, respectively for Fe2O2+O2on the inser (ZrO2, Al2O3, MgO),and the product Fe2O3clusters were ground state that reported in the literature.