Three-dimensional porous Mn–Ni/Al2O3 microspheres for enhanced low temperature CO hydrogenation to produce methane

Abstract CO methanation has attracted much attention because it transforms CO in syngas and coke oven gas into CH4. Here, porous Al2O3 microspheres were successfully used as catalyst supports meanwhile the Mn was used as a promoter of Ni/Al2O3 catalysts. The as-obtained Ni/Al2O3 and Mn–Ni/Al2O3 samples display a micro-spherical morphology with a center diameter near 10 μm. Versus the Ni/Al2O3 catalyst, the 10Mn–Ni/Al2O3 catalyst exhibits a high specific surface area of 92.5 m2/g with an average pore size of 7.0 nm. The 10Mn–Ni/Al2O3 catalyst has the best performance along with can achieve a CO conversion of 100% and a CH4 selectivity of 90.7% at 300 °C. Even at 130 °C, the 10Mn–Ni/Al2O3 catalyst shows a CO conversion of 44.0% and a CH4 selectivity of 84.1%. The higher low-temperature catalytic activity may be since the catalyst surface contains more CO adsorption sites and thus has a stronger adsorption performance for CO. Density functional theory (DFT) calculations confirm that the Mn additive enhances the adsorption of CO, especially for the 10Mn–Ni/Al2O3 catalyst with the strongest adsorption energy.