Abstract:
Natural magnetite formed by the isomorphism substitutions of transition metals, including Fe, Ti, Co, etc., was activated by mechanical grinding followed by H
2 reduction. The temperature-programmed reduction of hydrogen (H
2-TPR) and temperature-programmed surface reaction of carbon dioxide (CO
2-TPSR) were carried out to investigate the processes of oxygen loss and CO
2 reduction. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDS). The results showed that the stability of spinel phases and oxygen-deficient degree significantly increased after natural magnetite was mechanically milled and reduced in H
2 atmosphere. Meanwhile, the activity and selectivity of CO
2 reduction into carbon were enhanced. The deposited carbon on the activated natural magnetite was confirmed as amorphous. The amount of carbon after CO
2 reduction at 300°C for 90 min over the activated natural magnetite was 2.87wt% higher than that over the natural magnetite.