The Effect of Mn, Al Doping on the CO2 Hydrogenation Performance of CaCO3 -Supported Fe-Based Catalysts

Abstract

With increasingly serious environmental problems caused by the greenhouse effect, it has also become essential to reduce the concentration of CO₂ in the atmosphere. In this paper, CaCO₃ -supported Fe-based catalysts doped with Mn, Al, and K are prepared by a straightforward method and used for CO₂ hydrogenation. The fresh and spent catalysts were characterized by SEM-EDS, BET, TG, CO₂ -TPD, XRD, and XPS. The experimental results show that the highest CO₂ conversion rate of Fe10Mn2Al10Ca is 35.99 %, the maximum FTY value is 293.98 μmol_CO2 ⋅ $g_{\mathrm{Fe}}^{-1}$ ⋅ s^-1 , the maximum O/P value is 6.61, and the lowest CO selectivity is 32.21 %. At the same time, according to the characterization results, the doping of Mn and Al increased the Fe₃ O₄ /FeC_x ratio. As the Fe₃ O₄ /FeC_x ratio increases, the proportion of short-chain hydrocarbons (CH₄ , C_2-4 ) in the products increases, and the proportion of long-chain hydrocarbons (C₅₊ ) decrease. Therefore, the co-doping of Mn and Al promotes the conversion of CO and reduces its selectivity, and promotes the formation of light olefins. Finally, it is hoped that this study can provide a reference for further research on CaCO₃ -supported Fe catalysts.

Keywords: CO2 hydrogenation; co-doping; heterogeneous catalysis; reduction; supported catalysts.