Solid-solid reaction of CuFe2O4 with C in chemical looping system: A comprehensive study

Oxygen carriers are critical in chemical-looping system to transfer oxygen and heat. Spinel CuFe2O4 is a promising oxygen carrier due to its low decomposition temperature, good resistance to sintering and oxygen deficiency. In this study, a comprehensive investigation of solid-solid reaction of CuFe2O4 with C was conducted on a fixed-bed reactor. The XRD, Raman and SEM proved the primary structure of CuFe2O4 with uniform external morphology in size and shape. The weight loss of CuFe2O4 in TG showed that it could release O-2 at about 700 degrees C. The XRD and Raman results of solid products for various time intervals showed that CuFe2O4 was mainly transformed into CuFeO2 and Fe3O4 with a rapid reaction rate at the initial stage, and then CuFeO2 was reduced to Cu and Fe3O4, Fe3O4 was slowly reduced to FeO eventually. The DFT results indicated that C was in favor of adsorbing on O-terminated surface, and CuFe2O4 transformed into CuFeO2 and Fe3O4 accompanied by the formation of COx.