Performance of Ni/Si-MCM-41 catalysts in CO₂ methanation

The production of methane from the methanation reaction between H-2 and CO2, also known as the Sabatier reaction, is one way to diversify the global energy matrix, providing a use for CO2. This work evaluates the performance in this reaction of Ni catalysts supported on type MCM-41 silica, synthesized y a wet impregnation method. Catalytic tests were performed for 2.5 h under atmospheric pressure. The reaction variables considered were the catalyst nickel mass content (5% and 10%), temperature (T = 400 and 550 degrees C), reactant ratio (H-2/CO2 = 4 and 2.5), and space velocity (VHSV = 5 and 10 L g(-1) h(-1)). The catalysts were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDS) analyses before the reactions, and by thermogravimetric analysis (TGA), SEM, and EDS analyses after the reactions. The reaction variables were evaluated using an experimental design with 2 factors and 4 variables, in order to determine the effects of the reaction conditions on catalyst selectivity, reactant conversion, and reaction yields in terms of CH4 and CO. The best result was obtained using a reactant ratio of 2.5, space velocity of 5 L g(-1) h(-1), and reaction temperature of 550 degrees C, resulting in 93.7% selectivity for methane, 69.4% CO2 conversion, 74% H-2 conversion, and methane yield of 20.69%. Findings show Ni/Si-MCM-41 catalyst's applicability in methanation, advancing CH4 production technology, and addressing local demand while reducing CO2 emissions.