Direct Conversion of CO₂ into Alcohols Using Cu-Based Zeolite Catalysts

The direct hydrogenation of CO₂ into alcohols is an attractive but challenging catalytic reaction. Herein, it was shown that Cu nanoparticles supported on MFI and BEA zeolites have high catalytic activity and selectivity for converting CO₂ into ethanol and isopropanol. Furthermore, we investigated the effect of introducing mesopores via carbon templating and encapsulating the Cu nanoparticles via subsequent recrystallization. All the catalysts were characterized by N₂ physisorption, XRD, SEM, TEM, NH₃ TPD, XPS, and XRF, before we tested them in a high-pressure water-filled autoclave with a constant partial pressure of CO₂ (1 MPa) and an increasing partial pressure of H₂ (3-5 MPa). In general, the mesoporous zeolite catalysts resulted in a higher CO₂ conversion and selectivity toward ethanol than their non-mesoporous equivalents, while the recrystallized catalyst with encapsulated Cu nanoparticles had a higher selectivity towards isopropanol. For example, Cu@m-S1 showed the highest isopropanol productivity among the recrystallized mesoporous zeolites, corresponding to 20.51 mmol g^-1  h^-1 under the given reaction conditions. These findings highlight the importance of mesopores in zeolite catalysts for CO₂ hydrogenation to alcohols and point a new direction for further research and development.