Synthesis of MgAl2O4 by sol-gel method and investigation of catalytic performances in CO2 methanation

Abstract

Abstract CO2 levels in the atmosphere are increasing as a result of human activities such as industrial activities, fossil fuel usage, and deforestation. The CO2 methanation reaction, which converts CO2 into methane, may play a crucial role in addressing this issue. Like most commercial syntheses, the CO2 methanation process requires a catalyst. Spinel catalysts, particularly magnesium aluminate (MgAl2O4), have gained attention for their potential in CO2 methanation. In this study, MgAl2O4 nanoparticles were synthesized using a sol–gel method with a molar ratio of Mg:Al = 1:2, and calcined at temperatures ranging from 700 to 900 °C. The structural properties of the nanoparticles were characterized using differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller analysis, X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and transmission electron microscopy. The results showed that the particles had nearly spherical morphology, with agglomeration occurring at higher temperatures. The surface area decreased with increasing calcination temperature, from 188 m²/g at 700 °C to 94 m²/g at 900 °C. NiCo-MgAl2O4 catalysts were prepared by impregnation and characterized by CO2 temperature-programmed desorption and hydrogen temperature-programmed reduction. Catalytic performance tests revealed that the NiCo-MgAl2O4 catalyst calcined at 800 °C achieved the highest CO2 conversion (~85%) and methane selectivity. Spent catalyst analysis showed that carbon deposition negatively affected catalyst performance over time. This study emphasizes the role of strong basic sites in CO2 activation and methane formation, suggesting future improvements in catalyst stability. Graphical Abstract