Active sites in CO2 hydrogenation over confined VOx-Rh catalysts

Science China Chemistry - Metal oxide-promoted Rh-based catalysts have been widely used for CO2 hydrogenation, especially for the ethanol synthesis. However, this reaction usually suffers low CO2...     

The Interplay between Structure and Product Selectivity of CO2 Hydrogenation

Identification of the active structure under reaction conditions is of great importance for the rational design of heterogeneous catalysts. However, this is often hampered by their structural complexity. The interplay between the surface structure of Co₃O₄ and the CO₂ hydrogenation is described. Co₃O₄ with morphology‐dependent crystallographic surfaces presents different reducibility and formation energy of oxygen vacancies, thus resulting in distinct steady‐state composition and product selectivity. Co₃O₄‐0 h rhombic dodecahedra were completely reduced to Co⁰ and CoO, which presents circa 85 % CH₄ selectivity. In contrast, Co₃O₄‐2 h nanorods were partially reduced to CoO, which exhibits a circa 95 % CO selectivity. The crucial role of the Co₃O₄ structure in determining the catalytic performance for higher alcohol synthesis over CuCo‐based catalysts is demonstrated. As expected, Cu/Co₃O₄‐2 h shows nine‐fold higher ethanol yield than Cu/Co₃O₄‐0 h owing to the inhibition for methanation.