Ni- and MgO-based catalysts derived from mixed carbonates of magnesium and nickel for CO2 methanation

Abstract

CO<inf>2</inf> methanation is promising both for using captured carbon dioxide and storing renewable energy and Ni(0) supported on magnesium oxide is known to be an efficient catalyst for this reaction. Here, Ni-MgO catalysts were synthesized starting from MgO and nickel(II) nitrate using a simple and innovative one-pot method with the assistance of CO<inf>2</inf>. This involved the preparation of mixed magnesium and nickel carbonates precursors under a CO<inf>2</inf> atmosphere, which were subsequently thermally converted into mixed oxides containing 4.2 to 12.8 Ni wt.%. After reduction at 900 °C, Ni0-MgO with 8.5 wt.% Ni displayed the highest activity (70% conversion and 98% methane selectivity) at 350 °C, 1 bar and 9000 mL/h.gcat. Such catalyst was stable for >20 h. Nitrogen adsorption/desorption, XRD, TEM, TPR and TPD techniques were used to analyze the structural and physicochemical properties of the materials before reduction, after reduction and after methanation. Detailed characterizations revealed that the superior performance of the Ni0-MgO catalyst (with 8.5 wt.% Ni) originated from its better textural properties, the relatively smaller Ni nanoparticle size as well as high proportion of low- and medium-strength basic sites. In addition, a decrease of Ni particle size during methanation from 5 h to 20 h was observed, which is attributed to Ni redistribution at the Ni-MgO interface and underpins the excellent stability of 5ONiOP. © 2026 Elsevier Ltd.