Nickel–lanthana-based catalysts synthesised from LaNiO3 perovskite precursors are interesting materials for low-temperature CO2 methanation due to their unique combination of active sites for hydrogen activation and oxygenated carbon compounds adsorption. The key point is to understand which of those states offers the optimal interface for catalytic methanation based on the interconnection between catalyst activity, crystal size, apparent activation energy, phases, and carbon surface chemistry. This study reveals the answer to the question above using a carbon-state-gated interface normalisation. It integrates thermal activation gain with respect to the impregnated Ni/La2O3 catalyst, light-off gain ratio, size-adjusted activity gain corrected by the apparent activation energy value, and oxygenates gate factor based on La 3d splitting and surface carbonate-to-lanthanum ratio. As a result of calculations, LaNiO3-600 is found to be the preferred interface state since it yields 50% CO2 conversion at 285 °C, which is 96 °C lower than the impregnated Ni/La2O3 catalyst, with 25.2% light-off gain, apparent activation energy of 87 kJ mol−1, and the highest size-normalised activity gain of 12.83 °C nm−1. It is concluded that the performance advantage is not associated with nickel crystallite size itself but results from coupling between accessible metallic nickel and lanthanum surface available for oxygenates adsorption rather than being blocked by carbonate cover.
