In situ Ce-doped catalyst derived from NiCeAl-LDHs with enhanced low-temperature performance for CO2 methanation

Abstract

In this work, a Ni-supported CeO2-Al2O3 catalyst, called NiCeAl-RMO (reduced metal-oxide), was prepared via air calcination and H2 reduction of NiCeAl-LDH (layered double hydroxide). The NiCeAl-RMO catalyst shows superior CO2 methanation activity, especially at low temperature (250 °C), and it performed 78.6% CO2 conversion with ∼ 100% CH4 selectivity. Compared with NiAl-RMO, the NiCeAl-RMO catalyst prepared via the Ce-doping strategy has significantly improved CO2 methanation activity. Characterizations revealed that Ce doping would increase the amount of active Ni0 species, cause a large number of oxygen vacancies, and generate new moderate basicity sites on the catalyst. In addition, in situ DRIFTS found that, unlike the RWGS + CO methanation mechanism over NiAl-RMO, the CO2 methanation mechanism over NiCeAl-RMO followed the formate pathway by generating bidentate carbonate species, which was revealed as a key intermediate for enhancing the low-temperature activity of CO2 methanation.