Stabilizing Cu + in Cu/SiO 2 Catalysts with a Shattuckite-Like Structure Boosts CO 2 Hydrogenation into Methanol

Cu-based catalysts are widely employed for CO or CO 2 hydrogenation into methanol. However, their catalytic performance highly depends on supports, and the real evolution of Cu species is still covered by active components. Herein, we supply a Cu/SiO 2 catalyst prepared by flame spray pyrolysis (FSP), showing catalytic performance comparable to that of the active Cu/ZrO 2 catalyst for methanol synthesis from CO 2 . It reaches 79% selectivity at a CO 2 conversion of 5.2%, which is an outstanding selectivity among previously reported Cu/SiO 2 catalysts, considering they are generally treated as nearly inert catalysts. In situ X-ray absorption spectroscopy (XAS) analysis shows that 5 times more Cu + species in the FSP-Cu/SiO 2 are stabilized in comparison to those in the traditional ammonia evaporation (AE) made catalyst even after reduction at 350 °C. A unique shattuckite-like precursor with a slightly distorted Cu–O–Si texture structure formed in the FSP-made catalyst is responsible for the enriched Cu + species. Variations of intermediate formation and methanol production are found to have a good relationship with the amount of Cu + species. According to the results of high-pressure in situ DRIFTS, we attribute this to the promotional effect of Cu + on the stabilization of CO* intermediates, which inhibits CO desorption and facilitates further hydrogenation to CH 3 OH via the RWGS + CO-Hydro pathway. These results bring insights into the Cu reduction behavior and the function of Cu + species during methanol production on Cu-based catalysts without the assistance of active supports.