Manganese-promoted Ni/Al2O3 catalysts for effective CO2 methanation

Hydrogenation of CO₂ to methane is a feasible solution to the growing global environmental and energy challenges. Nickel-based catalysts are efficient and cost effective for CO₂ methanation. Hernin, we synthesized Mn-promoted Ni/Al₂O₃ catalysts with facilitated CO₂ methanation and elucidated the crucial role of Mn. After Mn doping, NiMn/Al₂O₃ catalysts showed improved NiO dispersion. Subsequently, H₂ reduction and CO₂ methanation treatments resulted in reduction of NiO and MnO₂ into Ni and MnO, and incorporation of Ni²⁺ into MnO lattice, forming NiMnO_x and creating numerous Ni-NiMnO_x interfaces. The abundant oxygen vacancies from NiMnO_x could enhance CO₂ activation. Moreover, oxygen vacancies at the interface also promote electron transfer from Ni and MnO, leading to electron-poor Ni nanoparticles and thus significantly promoting the *CO methanation. Ultimately, the electron-poor Ni nanoparticles and abundant oxygen vacancies at the Ni-NiMnO_x interface jointly facilitate CO₂ methanation.