An Active Manganese Promoted Ni/Al2O3 Catalyst for Low Temperature CO2 Methanation

As well known, the industrial methanation process needs highly active and stable catalysts obtained from cheap and abundant elements. In this work, we propose a high-loaded Ni/Al2O3 catalyst promoted by manganese. Among them, the 20Ni(2)Mn/ Al2O3 catalyst exhibits the best -CO2 conversion (90.5%) and excellent methanation stability at 250 degrees C. In addition, the roles of the Mn promoter on -CO2 conversion and selectivity were investigated in detail. The features of natural and promoted catalysts are described through XRD, XRF, BET, TEM, -H-2-TPR, -CO2-TPD, and operando DRIFTS techniques. Based on various characterization results, the addition of Mn will greatly reduce the Ni particle size and improve the Ni dispersion on the alumina support. Furthermore, compared to the unpromoted catalyst, Mn promoted catalysts show better reducibility and have more medium basic sites. And these medium basic sites are favorable to the adsorption and activation of -CO2. In-situ DRIFTS experiments for -CO2 methanation reveal that manganese could promote the monodentate carbonate hydrogenated to formate rapidly, which could be faster converted towards -CH4, contributing to significantly improved activity of the Mn promoted Ni/Al2O3 catalyst. [GRAPHICS] .

Automated summary

In this work, a high-loaded Ni/Al2O3 catalyst promoted by manganese was proposed. Among them, the 20Ni(2)Mn/Al2O3 catalyst showed the best CO2 conversion (90.5%) and excellent methanation stability at 250 degrees C. The addition of Mn greatly reduced the Ni particle size and improved the Ni dispersion on the alumina support, leading to better reducibility and more medium basic sites, which favor the adsorption and activation of CO2. Manganese could promote the rapid hydrogenation of monodentate carbonate to formate, which could be quickly converted to CH4, contributing to the significantly improved activity of the Mn promoted Ni/Al2O3 catalyst.