Synergistic Promotion of Ni/La2O3 Catalysts by Copper for Efficient Dry Reforming of Methane

Abstract

The catalytic performance of Ni/La₂O₃ and Ni–Cu/La₂O₃ for dry reforming of methane (DRM) was investigated, focusing on reducibility, stability, and coke resistance. Cu incorporation lowered the Ni reduction temperature, as revealed by temperature-programmed reduction (TPR), enhancing hydrogen spillover and oxygen vacancy formation. X-ray photoelectron spectroscopy (XPS) confirms that Cu stabilizes the oxygen lattice, minimizes carbonate accumulation, and facilitates CO₂ activation. Catalytic tests at 850°C demonstrated 78% CH₄ conversion and 96% CO₂ conversion for Ni–Cu/La₂O₃, compared to 55% and 72% for Ni/La₂O₃, respectively. X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) confirmed that Cu prevents Ni sintering, maintaining high dispersion. Carbon deposition analysis showed 0.50 wt.% total carbon for Ni–Cu/La₂O₃, slightly higher than Ni/La₂O₃ (0.42 wt.%), but with a 40% reduction in graphitic carbon. The synergistic effect between Cu and Ni optimizes Ni dispersion, modulates electronic properties, and weakens Ni–La₂O₃ interactions, improving CH₄ activation and carbon removal. Ni–Cu/La₂O₃ exhibits outstanding activity and resistance to deactivation, making it a highly effective and stable catalyst for CO₂ conversion and syngas production in DRM, with a strong synergy between Ni and Cu, along with the stabilizing influence of the La₂O₃ support, enhancing its overall performance and durability.