Assessment of redox behavior of nickel ferrite as oxygen carriers for chemical looping process

This study investigated the suitability of using nickel ferrite (NiFe2O4) oxygen carriers for a chemical looping process. NiFe2O4 powder was prepared by ball milling equimolar NiO and Fe2O3 in a high temperature solid-state reaction. Material characteristics of NiFe2O4 samples were investigated by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area measurements, and scanning electron microscopy (SEM). Redox cycling of NiFe2O4 oxygen carriers was performed by thermogravimetric (TGA) measurement under pure CH4 gas and O2/Air atmospheres, respectively. After five successive cycles, NiFe2O4 powder with a single phase of spinel structure demonstrated higher redox cycling behavior and better stability than standard NiO and Fe2O3. We also addressed the mechanism underlying the redox cycling by NiFe2O4 spinel powder. Our results demonstrate the feasibility of using the proposed preparation of NiFe2O4 as an oxygen carrier in a reversible chemical looping process (CLP).