The Effect of HO and CO on the Adsorption Behavior of H and CO on Hematite.

The adsorption of gas reactant molecules (H, CO, etc.) to the surface of hematite is the premise of chemical reaction. In order to further promote the basic research on the reaction mechanism of hematite reduction by a H-CO gas mixture, the adsorption behavior of H (or CO) under the conditions of pre-adsorbed HO (or CO) was systematically studied by the density functional theory (DFT) combined with reduction experiments. The results indicate that the gas molecules (H, CO, HO and CO) adsorbed on the Fe atom of the FeO (001) surface rather than the O atom, and the adsorption energy of the FeO-CO adsorption system was relatively minimum (-1.317 eV), indicating that the FeO-CO adsorption system was more stable. In addition, the adsorption energy of the H molecule adsorbed to the FeO-HO adsorption system was -0.132 eV, which was smaller than that of the H molecule directly adsorbed to FeO (-0.013 eV), indicating that the HO molecule pre-adsorption was beneficial to the H molecule adsorption. Compared with the HO molecule, the CO molecule had relatively less influence on the adsorption and subsequent behavior of CO with FeO. From the experiment analysis results, on the whole, CO had a greater impact on the gas diffusion, while HO had a greater impact on the interfacial chemical reaction (gas adsorption), which was consistent with the DFT calculation results.