The effect of nickel particle spacing and metal–support interaction on the activity and stability of Ni/Al2O3 catalysts for CH4/CO2 reforming

Abstract

Ni-based catalysts play a key role in the dry reforming of methane (DRM). However, catalyst deactivation due to carbon deposition, exacerbated by nickel nanoparticle sintering, remains a significant challenge. Inhibiting nickel particle sintering improves the catalyst's resistance to deactivation. In this study, the effects of nickel nanoparticle spacing and its metal–support interactions (MSIs) on the sintering of nickel particles as well as the DRM activity were systematically investigated through integrated experimental and density functional theory analyses. It was shown that the dispersion and spatial separation of nickel particles mainly depend on the surface area and pore architecture of the support. While an increase in the support surface area widens the spacing between nickel particles, the support porosity also modulates the distribution of particles. The limited pore size restricts the entry of particles into channels, promoting the accumulation of particles on the surface, thereby decreasing interparticle distances and elevating the sintering tendency. An elevated surface area enhances nickel interparticle spacing, optimizing active site availability while promoting NiAl₂O₄ formation, which stabilizes nickel particles via intensified MSIs. Increased interparticle spacing elevates the surface-absorbed oxygen concentration, enhances CO₂ chemisorption capacity, and strengthens Ni–CO₂ adsorption energetics. Furthermore, the addition of lanthanum strengthens Ni–Al₂O₃ interactions, effectively suppressing nickel particle migration, and this stabilization effect intensifies in low-surface-area Al₂O₃ supports. This study is expected to provide new ideas for designing high-performance Ni-based catalysts.