Dual Acid–Metal Functionality of Cu–ZrO₂@SiO₂ Catalysts for the Selective CO₂ Hydrogenation into Methanol and DME

Integrating metallic sites with tailored acid-base and redox functionalities is sensitive to the selective hydrogenation of CO 2 to methanol and DME. Herein, we designed a series of confined Cu-ZrO 2 @SiO 2 catalysts with different Cu-Zr ratios (3:1, 3:2, 3:3), to enhance Cu–Zr interfacial interactions and regulate surface acidity by spatially confining active sites. While low Zr content retained a partial spherical morphology and high methanol selectivity (97%) at 220 °C, increasing the Zr loading induced a structural distortion into a “cotton-like” morphology. This transformation promoted a high contribution of defect-related oxygen species (62%) and total acidity (1128 μmol∙g -1 ) associated with distorted Zr–O–Si interfacial environments. The optimized Cu-Zr (3:3) catalyst exhibited a superior balance of functionalities, achieving 81% methanol and 17% DME selectivity, with 15% CO 2 conversion (220 °C). At high temperatures (280 °C), this catalyst also maintained high selectivity for methanol (65%) and DME (20%), outperforming a conventional impregnated Cu-ZrO 2 /SiO 2 reference catalyst, which converted only 9% CO 2 , with 76% methanol selectivity and negligible DME production under the same conditions. XPS and EPR revealed that this enhanced activity probably stems from a unique electronic environment: a high fraction of electronically perturbed Cu species, strongly coupled to Zr-derived sites, which facilitates CO 2 activation and suppresses the reverse water-gas-shift reaction. This catalyst demonstrated 72-hour stability with a space-time-yield (223 mg MeOH ∙g cat -1 ∙h -1 ) significantly higher than that of the impregnated catalyst (121 mg MeOH ∙g cat -1 ∙h -1 ). These results indicate that spatially coupling Cu redox sites with Zr-derived acidity within a SiO 2 –confined architecture provides an effective strategy to tune product selectivity in CO 2 hydrogenation.