Particle size tuning of Ni/CeO2 catalysts and their performance in methane dry reforming reaction

Nickel-based catalysts are prone to sintering and carbon deposition during methane dry reforming (DRM), which limits their industrial application. This study addresses these challenges by designing Ni/CeO₂ catalysts with controlled Ni nanoparticle sizes. By varying calcination temperatures, selecting different calcination atmospheres, and comparing preparation methods (equal-volume impregnation vs. combustion method), a series of Ni-based catalysts with different particle sizes were synthesized. The physicochemical properties of the catalysts were elucidated through various characterization techniques. ICP-OES confirmed that the actual Ni loading closely matched the nominal value. XRD and TEM analyses verified that the combustion method yielded smaller NiO nanoparticles with higher dispersion compared to the impregnation method. This advantage stems from the rapid, self-sustaining redox reaction in the combustion process, which effectively inhibits NiO nuclei migration and agglomeration. Consequently, catalysts prepared by the combustion method exhibited superior catalytic activity and stability in DRM. The enhanced performance is directly linked to the smaller Ni particle size, which provides a greater number of active sites and promotes stronger metal-support interactions, thereby improving resistance to sintering and carbon deposition. Furthermore, kinetic studies showed that the smaller Ni nanoparticles were more active, possessing a lower apparent activation energy for methane reforming than the larger particles. These findings provide a clear strategy for the rational design of coke- and sintering-resistant Ni/CeO₂ catalysts for carbon-based energy conversion.