Boosting CO₂ methanation on ceria supported transition metal catalysts via chelation coupled wetness impregnation

The incipient wetness impregnation (IWI) method is widely used in the preparation of supported transition metal catalysts for its high throughput and cost-effective synthesis, yet suffers from poor metal-support interaction, restricting its further application at an industrial scale. Herein, a universal strategy of chelation coupled impregnation (CCI) is presented. The as-prepared Ni/CeO₂(CCI) showed superior catalytic performance for CO₂ conversion (84.3%) and CH₄ selectivity (100%) under the experimental conditions (WGHSV = 24,000 mL g^-1 h^-1 and H₂/CO₂ = 4:1) even at low temperatures (T = 275 °C). The surface characterization results confirmed that the agglomeration of metal active sites in Ni/CeO₂(CCI) was restricted and more surface oxygen vacancies were generated on CeO₂. Further, the in-situ diffuse reflectance infrared Fourier transform spectroscopy (in-situ DRIFTS) analysis suggested that the surface oxygen vacancies that served as active sites could facilitate the direct dissociation of CO₂ more favorably than the associative route, thus significantly promoting CO₂ methanation activity.