Mechanisms and interactions in the reduction of Fe2O3 by H2/CO mixed gas: Atomic insights from ReaxFF molecular dynamics simulations and experiments

The experiment explored the reduction process of H2/CO mixed gas, and found the promoting effect of CO when the proportion of CO is 20% at 850 ℃. The ReaxFF molecular dynamics (MD) simulation method was used to observe the reduction process and provide an atomic-level explanation. The accuracy of the parameters used in the simulation was verified by DFT calculation. The simulation shows that the initial reduction efficiency of H2 is much higher than that of CO (from 800 to 950 ℃). As the reduction proceeds, cementite will appear in the surface iron obtained after CO participates in the reduction at 850 ℃. Due to the active properties, the C atoms in cementite are easy to further react with the O atoms in Fe2O3. The generation of internal CO may destroy the dense structure of the surface layer, thereby affecting the overall reduction swelling. The surface structures obtained after H2 and CO reduction have been compared, and it is found that the structure obtained by CO has a larger surface area, thus promoting the subsequent reaction of H2.