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

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 μmolCO2 ⋅ gFe-1 ${{\rm{g}}_{{\rm{Fe}}}^{ - 1} }$ ⋅ 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 Fe3O4/FeCx ratio. As the Fe3O4/FeCx ratio increases, the proportion of short‐chain hydrocarbons (CH4, C2–4) 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. CaCO3 supported Fe‐based catalysts were prepared by co‐precipitation method, and the effects of Mn and Al doping on the catalyst properties were studied. It was found that the doping of Mn and Al promoted the performance of CaCO3 supported Fe‐based catalysts. Further characterization shows that doping Mn and Al can increase the ratio of Fe3O4/FeCx in the spent catalyst. It was found that the doping of Mn and Al affected the ratio of Fe3O4 and FexC in the waste catalyst and increased the relative content of Fe3O4, especially when MnAl was co‐doped. This eventually led to a decrease in the proportion of C5+ and an increase in the content of CH4 and C2–4 in the product.