Highly active Ni/Al₂O₃ catalyst for CO₂ methanation by the decomposition of Ni-MOF@Al₂O₃ precursor via cold plasma

In this work, a novel Ni/Al₂O₃-P catalyst for CO₂ methanation was prepared via an oxygen plasma decomposition of the Ni-MOF@Al₂O₃ core–shell precursor. The obtained catalyst showed a higher Ni dispersion (26.5%) and contained less NiAl₂O₄ spinel when compared with the Ni/Al₂O₃ prepared by the traditional method. The Ni/Al₂O₃-P catalyst showed significantly enhanced efficiency toward CO₂ methanation as compared with those catalysts with a similar nickel loading but are prepared using the traditional method. For example, the space time yield of methane (STY_CH4) of the Ni/Al₂O₃-P catalyst was as high as 21103.6 mg∙g_Ni^-1∙h⁻¹ at 400 °C and GHSV as 12000 ml∙g⁻¹∙h⁻¹, which is 3.4 times higher than that of the reported catalyst (6190.5 mg∙g_Ni^-1∙h⁻¹) with a similar nickel loading under similar reaction conditions. Moreover, Density Functional Theory (DFT) studies together with the CO₂-TPD results revealed that both nickel surface and Ni-Al₂O₃ interface could activate CO₂, while the NiAl₂O₄ surface could not.