Low loading copper-based catalysts for effective CO2 hydrogenation to methanol

• Efficient CO 2 -to-methanol synthesis achieved with low-Cu catalyst (10 wt % optimal) • Zinc addition modifies activity, with a 1:1 Cu/Zn ratio maximizing methanol yield. • High WHSV can mitigate equilibrium constraints, resulting in high methanol yield. • 10 % wt Cu/ZrO 2 achieves STY = 3.9 g CH 3 OH .g Cu -1 .h −1 outperforming high-loading catalysts. Methanol synthesis via CO 2 hydrogenation is an emerging Power-to-Liquid (PtL) technology aimed to accelerate the energy transition and the defossilization of key sectors, particularly maritime transport. This study focuses on the study of low loading formulations, to minimize the catalyst cost. Key operational variables including temperature ( T ), Weight Hourly Space Velocity ( WHSV ), copper and zinc loadings, and aging state were systematically varied. An overall active phase loading of 10 % wt emerged as optimal. Within this total loading, a 5 % wt Cu-5 % wt Zn/ZrO 2 catalysts delivered higher methanol productivity than 10 % wt Cu/ZrO 2 ; however, the bimetallic catalysts showed pronounced deactivation under water-rich atmospheres, establishing 10 % wt Cu/ZrO 2 as the most promising catalysts. Operating temperature and WHSV exerted a strong, synergistic influence on CH 3 OH formation; in particular, increasing WHSV shifted the reaction away from thermodynamic control and boosted methanol synthesis. Finally, the catalytic performance of these low-loading catalysts was benchmarked against high-copper-loading methanol catalysts reported in the literature by critically compare their activities as a function of the residence time (τ) calculated at reaction conditions. This assessment revealed that the proposed formulation is highly competitive when compared to most conventional formulation, with a maximum methanol space time yield (STY CH 3 OH ) of 3.9 g CH 3 OH gCu -1 h -1 . This comparison confirms that the catalysts proposed in this study could offer a remarkably more efficient use of the active phase than the conventional high-copper-loading catalysts.