Tuning the Ca content of Ni–Ca–Al layered-double hydroxide catalysts for low-temperature CO 2 methanation

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 12; no. 39; pp. 26820 - 26832
• Main Authors: Dias, Yan Resing, Perez-Lopez, Oscar W.
• Format: Journal Article
• Language: English
• Published: 08.10.2024
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/D4TA04231J

CO 2 valorization as carbon feedstock is a good strategy to reduce its environmental effects and produce fuels and chemicals such as CH 4 , which can be used as synthetic natural gas (SNG). Layered double hydroxide (LDH)-derived Ni–Ca–Al catalysts with variable Ca content (3–33% mol) were synthesized through co-precipitation, characterized by N 2 physisorption, X-ray diffractometry (XRD), temperature-programmed analyses (H 2 -TPR, CO 2 -TPD, H 2 -TPD, and TPO), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) and evaluated in CO 2 methanation (200–400 °C, 1 atm, and a GHSV of 60 000 mL (g cat h) −1 ). Outstanding performance was observed at temperatures as low as 200 °C, where the catalyst containing 6% Ca achieved 79.4% CO 2 conversion and 100% CH 4 selectivity, attributed to the improved metal–support interaction that provided a high surface area, dispersion, and small-sized crystallites, thus presenting plenty of Ni active sites, and to the high basicity in the weak-medium range, which facilitated the adsorption and activation of H 2 and CO 2 . A stability test (250 °C for 10 h) demonstrated high resistance to deactivation by sintering and carbon deposition. Therefore, the Ni–Ca–Al LDH-derived catalysts were proved as feasible catalysts for CO 2 methanation, where the proper adjustment of Ca content in the lattice improves their properties, allowing the process to be performed closer to thermodynamic equilibrium at low temperatures and preventing high energy spending.