Effect of Mn-Doped MgO Support on the Catalytic Performance of Ni-Based Catalysts in CO2 Methanation

Methanation of CO2 is a promising strategy for converting CO2 into valuable fuels or products, and the current critical challenge lies in the scientific design of non-precious metal catalysts capable of achieving high activity at low reaction temperatures. Hence, the Mn-doped MgO support was synthesized through the co-precipitation method, followed by the preparation of the Ni/Mn–MgO catalysts via the impregnation method for use in CO2 methanation, in order to investigate the effect of Mn doping on the morphology, structure and catalytic performance of the resultant catalysts. The results demonstrated that an appropriate amount of Mn doping could improve the dispersion of active metal Ni in the support, weaken the interaction between Ni and the support, increase the specific surface area of the catalyst, advance the generation of surface defect oxygen species, and consequently enhance the number of weak and moderate alkaline sites. Obviously, the catalyst Ni/Mn–MgO-0.10 exhibited the excellent catalytic performance with CO2 conversion of 70% and CH4 yield of 66% under 350°C, and still maintained the stable catalytic activity after 60 h of stability testing.