Sustainable Mining and Metallurgy

CO₂ hydrogenation to methane is an important technical means to achieve carbon emission reduction and provide clean energy (CH₄). The key to realize this technology is the preparation of high-performance catalysts. In this paper, a Ni-Cu-Al trimetallic nickel-based hydrotalcite derived catalyst (NCA) with high selectivity and excellent reaction stability for CO₂ methanation was designed. The hydrotalcites with different Ni/Al molar ratios were prepared by urea hydrolysis method by adjusting the ratio of Ni to Al on the laminate. The hydrotalcites were used as precursors to prepare NCA catalysts. The performance of each catalyst was evaluated by XRD, TGA and BET characterization methods, and the long-term stability of the catalyst was tested. The results show that with the increase of the molar ratio of Ni/Al, the crystallinity of the catalyst is better, the thermal stability is increased, and the incorporation of copper can improve the stability of the catalyst. Under the temperature of 300℃ and pressure of 0.1MPa, the conversion rates of CO₂ over the several catalysts were above 60%, and the conversion rate of CO₂ over the catalyst with Ni/Al molar ratio of 3.5 was 82.6%. After 70h of reaction, the conversion rate did not change significantly, which shows that the catalyst has good stability.