Unique catalysis of Ni-Al hydrotalcite derived catalyst in CO2 methanation: cooperative effect between Ni nanoparticles and a basic support

Ni-Al hydrotalcite derived catalyst (Ni-Al2O3-HT) exhibited a narrow Ni particle-size distribution with an average particle size of 4.0 nm. Methanation of CO2 over this catalyst initiated at 225 degrees C and reached 82.5% CO2 conversion with 99.5% CH4 selectivity at 350 degrees C, which was much better than its impregnated counterpart. Characterizations by means of CO2 microcalorimetry and Al-27 NMR indicated that large amount of strong basic sites existed on Ni-Al2O3-HT, originated from the formation of Ni-O-Al structure. The existence of strong basic sites facilitated the activation of CO2 and consequently promoted the activity. The combination of highly dispersed Ni with strong basic support led to its unique and high efficiency for this reaction.