Highly Active Ni-Based Catalyst Derived from Double Hydroxides Precursor for Low Temperature CO₂ Methanation

The Ni nanoparticles supported on Al2O3 metal oxides with different Ni2+/Al3+ molar ratios from 1/1 to 6/1 (denoted as NixAL-MO) derived from Ni–Al hydrotalcite precursors (NixAl-LDHs) were prepared and applied to CO2 methanation at a low temperature. By adjusting the Ni2+/Al3+ ratios, the alkaline and reducibility of the catalysts were designed, and the catalysts showed efficient catalytic performance at a low temperature. The Ni5AL-MO catalyst demonstrated the highest CO2 conversion of 89.4% at 250 °C. The superior catalytic property was related to the basic property, readily reducible NiO species, and the cooperation of metal nanoparticles and basic sites. The reaction intermediate species formed on the catalyst surface were identified by in situ FTIR analysis, and the reduction mechanism of CO2 was revealed. Moreover, the Ni5Al-MO catalyst had excellent resistance to carbon deposition and metal sintering after a long reaction duration. The NixAl-LDHs as the catalyst precursor show a promising potential for CO2 methanation at a low temperature.