Enhancement of surface morphology and catalytic kinetics of NiAl₂O₄ spinel-derived Ni catalyst to promote dry reforming of methane at low temperature for the direct application to a solid oxide fuel cell

Dry reforming of methane at low temperatures of 400 ∼ 700 °C is examined by using conventional Ni/Al₂O₃ catalyst and spinel-derived Ni catalyst anchored on aluminum oxide through powder-based solid-state reaction. The spinel-derived Ni catalyst exhibits uniform particle distribution with a size of 10 nm (10 times smaller than the conventional Ni/Al₂O₃ catalyst) and the highest catalytic performance under all operating conditions with apparent activation energies of 42.51 kJ/mol for CH₄ conversion and 45.39 kJ/mol for CO₂ conversion. Kinetics analysis elucidates that the conventional Ni/Al₂O₃ catalyst changes its rate-limiting factor from diffusion limitation to kinetics limitation with decreasing temperature near 550 °C. In contrast, the spinel-derived Ni catalyst has a single rate-limiting factor of diffusion limitation at all temperatures avoiding surface kinetics limitation. In addition, it is shown that the spinel-derived Ni catalyst exhibits better stability than the conventional Ni/Al₂O₃ catalyst, attributed to the enhanced interaction between active Ni particles and Al₂O₃ support.