Air Oxidation Kinetics of Commercial-Grade Iron Powder As an Oxygen Carrier for Chemical Looping Methane Reforming

Iron-based oxygen carriers are potential candidates for hydrogen production through chemical looping methane reforming (CLMR) for the low cost and high H₂ yield. The oxidation kinetics of commercial-grade iron powder is tested in a thermogravimetric analyzer (TGA) between 500 and 900 ℃. Iron oxides prepared at various temperatures are analyzed with X-ray diffraction (XRD). The oxidation rate is generally low despite a noticeable increase at temperatures above 700 ℃. Multiple iron oxide phases are found in the oxidized iron particles, mainly including hematite (Fe₂O₃), magnetite (Fe₃O₄), and wüstite (FeO). The composition of Fe₂O₃ increases with higher reaction temperatures and a longer reaction time. Significant particle sintering occurs at temperatures above 600 ℃. These preliminary results suggest that the low oxidation rate, complex oxidation products, and high-temperature sintering need to be addressed in order to utilize iron as an effective oxygen carrier in CLMR.