Enhanced photothermal synergistic catalysis of dry reforming of methane on high metal dispersion MOF-derived Ni/CeO₂ catalysts

A series of MOF-derived Ni/CeO₂ (MD-Ni/CeO₂) catalysts with varying loadings (0.5 wt%-5wt%) were successfully synthesized for photothermal synergistic catalysis of dry reforming of methane (PTSC-DRM). BET and HR-TEM results indicated that MD-Ni/CeO₂ exhibited high specific surface area and nickel dispersion. A systematic study was conducted to investigate the effect of nickel loading on the activity and stability through catalytic evaluation and characterization. The results demonstrated that higher loadings tend to cause carbon deposition on the catalyst, while lower loadings are not favorable for H₂ production. The MD-Ni/CeO₂ catalyst with a 3 wt% loading was identified as the optimal concentration, achieving CO₂ and CH₄ conversion of 72.42 % and 66.93 % at 650°C, respectively, along with H₂ and CO yields of 169.22 and 182.26 mmol·g⁻¹·h⁻¹. It also maintained good stability during a continuous catalytic evaluation over 70 h. XPS, CO pulse adsorption, and H₂-TPR results indicate that the 3 wt% MD-Ni/CeO₂ catalyst possesses relatively stable nickel nanoparticles, the highest concentration of oxygen vacancies, and the most active oxygen species. This enhances the synergistic effect between Ni and CeO₂, thereby improving light absorption capacity and carbon dioxide activation ability, which in turn enhances catalytic activity and stability. Furthermore, density functional theory revealed the promoting effect of oxygen vacancies on CO₂ adsorption on MD-Ni/CeO₂.