Influence of Calcination and Reduction Conditions of Ni-Al-LDH Catalysts for CO2 Methanation

CO2 methanation offers a sustainable route to reduce greenhouse gas emissions by converting carbon dioxide into methane, a valuable renewable fuel. This exothermic reaction not only mitigates its environmental impact but also provides energy-efficient benefits, as the heat generated can be reused in industrial applications. In this study, CO2 methanation was carried out in a continuous flow reactor with a CO2:H2 molar ratio of 1:4 and a gas hourly space velocity (GHSV) of 12,000 h−1, using a Ni-Al-LDH catalyst with a molar ratio of 2.3. The research focused on how calcination and reduction conditions affect catalyst structure and activity. Characterization techniques such as BET, XRD, TPR, H2-TPD, and CO2-TPD revealed that these conditions significantly influence surface area, crystallinity, phase composition, and metal dispersion. A higher reduction temperature decreased the surface area and increased both the crystallite size and basicity. The findings highlight that thermal treatment play a crucial role in optimizing the catalytic properties of NiAl catalyst. The sample calcined at 600 °C showed greater activity at lower reaction temperatures, while the catalyst calcined at 400 °C performed better above 300 °C. Additionally, the evaluation of the effect of the reduction atmosphere during catalyst activation showed that H2 is a more effective reducing gas at lower reaction temperatures, whereas biogas showed a better performance at higher temperatures. Importantly, XRD results showed the catalysts maintained their structural integrity post-reaction, with no significant carbon deposition in the H2 atmosphere, confirming their potential for long-term application in CO2 methanation.