Impact of hybrid CO2-CO feeds on methanol synthesis over In2O3-based catalysts

Catalysts for CO2-to-methanol are typically evaluated in a single-pass regime using pure CO2streams. In a practical process however, CO shall be present as a feed impurity or as a recycled byproduct. Herein, the sensitivity to CO was evaluated on In2O3 catalysts in bulk, supported, or metal-promoted forms, using cycle experiments with variable CO2 and CO contents at H2/(CO + CO2) = 4. The methanol productivity was decreased (−20-−40 %) on all catalysts except In2O3/monoclinic-ZrO2, the activity of which was boosted by 10 %. In-depth characterization of the catalysts uncovered controlled formation of oxygen vacancies and resistance to sintering as the main reasons for the activation of the latter and an interplay of CO/H2O-induced sintering and CO inhibition as the origin of performance loss. Focusing on the most representative systems, operation protocols were explored to maximize their methanol yield. We emphasize that assessment with hybrid CO2-CO feeds is key for the design of industrially-viable catalysts for sustainable methanol production.