Methanol synthesis over Cu/CeO2–ZrO2 catalysts: the key role of multiple active components

Abstract

High surface area ceria–zirconia synthesized by a glycothermal approach was used as a support for copper nanoparticles. Cu–CeO₂/ZrO₂ catalysts containing 5–25 wt% copper demonstrate high carbon dioxide-to-methanol conversion rates (120–180 g_MeOH kg_cat⁻¹ h⁻¹) at 260 °C and 50 bar. The sample containing 5 wt% copper in the form of small nanoparticles (≤5 nm) demonstrates the highest activity normalized per mass of copper, while higher copper loading results in copper segregation and correspondingly lower activity. We attribute the high activity to a unique synergetic effect between the active components, copper, ceria and zirconia, where activation of hydrogen and carbon dioxide and subsequent methanol synthesis take place. The redox properties of the ceria–zirconia support and its ability to form oxygen vacancy sites play a crucial role in carbon dioxide activation.