Cu and Ga dual sites on Ce0.9Zr0.1O2 for CO2 hydrogenation to methanol

Abstract

Cu-based catalysts are highly attractive for CO₂ hydrogenation to methanol due to their efficiency, selectivity, and cost-effectiveness. To further accelerate methanol synthesis, dual-site activation mechanisms are particularly effective. In this direction, solid solutions serve as effective supports, enhancing methanol production through improved hydrogenation, though the exact nature of the active sites in CuGa-based solid solutions remains unclear. In this study, we examine the synergistic interactions between Ga and Cu nanoparticles/clusters deposited on Ce_0.9Zr_0.1O₂ for CO₂-to-methanol hydrogenation. Through in situ diffuse reflectance infrared Fourier transform spectroscopy and temperature-programmed (TPR/TPD), we analyze the nature of the active sites and elucidate the reaction pathway. The results demonstrate that CO₂ adsorption and activation are favored by the appropriate Cu/Ga ratio, while Ga sites, in addition to Cu, play a critical role in promoting H₂ dissociation under methanol synthesis conditions. Furthermore, the oxygen vacancies in the CuGa/Ce_0.9Zr_0.1O₂ catalyst play a crucial role in stabilizing the key *HCOO intermediate, facilitating its further hydrogenation to methanol via the formate pathway. This synergy between Ga and Cu optimizes both CO₂ activation and hydrogenation steps, emphasizing Ga as an active site alongside Cu and highlighting the catalyst’s potential for efficient methanol production from CO₂.