Decomposition of carbon dioxide using mechanically-milled magnetite

Abstract

In recent years, various studies have been reported on decomposition of carbon dioxide into carbon using iron oxide. This study investigates the ability of mechanically-milled magnetite powder to decompose carbon dioxide as well as the effect of mechanical milling on the crystal structure change. Mechanical milling was performed on magnetite powder using a high-energy vibration ball-milling machine. After 6–12 h of milling, Fe and αFe 2O 3 phases appear in addition to the magnetite phase, followed by disappearance of the αFe 2O 3 phase after 24 h of milling, and an FeO phase appears after 72–168 h. The Fe 3O 4 content phase gradually decreases with milling. The carbon dioxide decomposition with the milled powder was carried out in a quartz tube for 3 h at 773 K. The carbon content of the sample after the CO 2 decomposition increases slightly with the milling time up to 48 h and shows drastic increase when the milling time is longer than 72 h, indicating that the production of FeO phase contributes to the ability of CO 2 decomposition. After the decomposition the sample contains graphite (or other types of carbon), undissolved Fe (both bcc and fcc structure) and Fe 3O 4 phase.