Computational design and experimental validation of transition-metal doped CuFe2O4 as oxygen carriers in chemical-looping combustion

Owing to low cost and minimal energy penalty, chemical-looping combustion (CLC) is regarded as a promising combustion technology for fossil fuel utilization and CO2 capture. As oxygen carrier plays a key role in delivering oxygen and heat, the development of oxygen carrier with high performance is fundamental for the application of CLC. Here, a tradeoff between formation energy and transportation barrier of oxygen vacancy was found for the rational design of spinel CuFe2O4-based oxygen carriers by using a new descriptor (Φ, coupling electronegativity and atomic radius). The reactivity of CuFe2O4 is found to be strongly relevant to the proposed descriptor Φ. Compared with the undoped CuFe2O4, the formation energy and transportation barrier of oxygen vacancies in doped CuFe2O4 are reduced, which implies that oxygen migrates more easily in doped CuFe2O4. Cr and Co dopants with great potential are screened out, and they can reduce the energy barrier of CO oxidation over CuFe2O4 from 47.91 kJ/mol to 20.19 kJ/mol and 21.54 kJ/mol, respectively. Thermogravimetric analysis (TGA) experiments show that Cr dopant can improve the low-temperature reactivity of CuFe2O4, while Co dopant can facilitate the transition of CuFe2O4 to Fe3O4 and Cu (1.5CuFe2O4 + 2CO → 1.5Cu + Fe3O4 + 2CO2).