Carbon Dioxide Reforming of Methane Over Co/Al2O3 Catalysts Doped with Manganese

The manganese-promoted cobalt supported on gamma alumina was prepared following the incipient wetness impregnation method and employed as a catalyst for carbon dioxide reforming of methane. The addition of manganese has changed the physicochemical properties of the original material. The Co3O4 crystallite size was decreased from 12.14 to 8.66 nm, suggesting a higher metal dispersion. The activation of the catalyst precursor was more effective with less energy required. Notably, the carbon dioxide adsorption over the catalyst surface was greatly enhanced in the presence of 1 wt% manganese. Taken all together, the manganese-promoted catalyst showed an outperformance with higher activity and stability in comparison with the pristine. At 973 K, 1 atm, CH4/CO2 ratio of 1, the addition of 1 wt% Mn into 5Co/Al2O3 led to notable increases in CH4 (15.2%) and CO2 (17.68%) conversions. Also, the stability of Mn-promoted was much higher compared to pristine catalyst with only 0.3 wt% of undesirable coke formed. Meanwhile, it was 4.94 wt% in the case of 5Co/Al2O3 at the same operating condition. Furthermore, the role of carbon dioxide adsorption in carbon dioxide reforming of methane was investigated. At a proper combination of carbon dioxide activation and methane dissociation, the catalytic activity can be significantly enhanced with much lower activation energies for the feedstock gases. Nevertheless, when the adsorption of carbon dioxide was dominant, catalytic activity was much lower and the deactivation occurred rapidly.

Automated summary

The addition of manganese to the cobalt catalyst supported on gamma alumina improved its physicochemical properties, leading to higher metal dispersion and enhanced carbon dioxide adsorption. The manganese-promoted catalyst exhibited higher activity and stability in carbon dioxide reforming of methane compared to the pristine catalyst. The presence of manganese also resulted in notable increases in CH4 and CO2 conversions. The role of carbon dioxide adsorption in catalytic activity was investigated, showing that a proper combination of carbon dioxide activation and methane dissociation can significantly enhance catalytic activity with lower activation energies.