Unraveling interlayer effects of exfoliated NiAl-LDH nanosheet catalysts for efficient CO2 methanation

Abstract

The carbon dioxide (CO<inf>2</inf>) methanation process offers a promising route for recycling CO<inf>2</inf> into fuels and chemicals. However, achieving low-temperature CO<inf>2</inf> methanation remains a critical challenge. In this study, NiAl-layered double hydroxides (LDHs) with a nanosheet-like structure were exfoliated using different solvents (DI H<inf>2</inf>O, EtOH, Ace, IPA), resulting in NiAl-X (X = DI H<inf>2</inf>O, EtOH, Ace, IPA) exfoliated nanosheet-like structures. The physicochemical properties of the exfoliated NiAl catalysts were characterized using various techniques, and the dispersion of Ni metal from LDH exfoliation was evaluated in different solvents. The NiAl–EtOH catalyst exhibits the excellent performance, achieving 90.38% CO<inf>2</inf> conversion, 100% CH<inf>4</inf> selectivity, and high CH<inf>4</inf> yield at low temperature of 270 °C. The NiAl–EtOH catalyst exhibited excellent CO<inf>2</inf> conversion and CH<inf>4</inf> selectivity stability over 200 h at the optimized temperature of 270 °C. The DRIFTS study reveals CO<inf>2</inf> methanation over NiAl–EtOH proceeds via the formate reaction pathway.