Natural magnetite formed by the isomorphism substitutions of transition metals, including Fe, Ti, Co, etc., was activated by mechanical grinding followed by H₂ reduction. The temperature-programmed reduction of hydrogen (H₂-TPR) and temperature-programmed surface reaction of carbon dioxide (CO₂-TPSR) were carried out to investigate the processes of oxygen loss and CO₂ 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 H₂ atmosphere. Meanwhile, the activity and selectivity of CO₂ reduction into carbon were enhanced. The deposited carbon on the activated natural magnetite was confirmed as amorphous. The amount of carbon after CO₂ reduction at 300°C for 90 min over the activated natural magnetite was 2.87wt% higher than that over the natural magnetite.

由过渡金属（包括Fe，Ti，Co等）的同构替代形成的天然磁铁矿，通过机械研磨，然后还原H ₂进行活化。进行了氢气的程序升温还原（H ₂ -TPR）和二氧化碳的程序升温表面反应（CO ₂ -TPSR），以研究氧气损失和CO ₂还原的过程。通过X射线衍射（XRD），场发射扫描电子显微镜（FE-SEM）和能量色散X射线光谱（EDS）对样品进行表征。结果表明，机械研磨天然磁铁矿后，H ₂含量降低，尖晶石相的稳定性和缺氧度明显增加。大气层。同时，提高了CO ₂还原为碳的活性和选择性。确认在活性天然磁铁矿上沉积的碳为无定形。活化的天然磁铁矿在300℃下90分钟CO ₂还原后的碳含量比天然磁铁矿高2.87wt％。