Reversible Strong Metal‐Support Interactions in Co/TiO ₂ Catalysts Driven by CO ₂

Abstract Strong metal–support interactions can significantly influence catalytic performance. On titania supports, these interactions often involve the formation of a substoichiometric TiO X overlayer during high‐temperature reduction, which can be reversed by treatments under dioxygen. Under CO 2 hydrogenation conditions, where water is produced, complete removal of the TiO X overlayer has been reported, raising questions about its stability in the presence of a mild oxidant such as CO 2 . In this study, in situ and operando techniques were employed to examine the effect of varying conditions on both the titania overlayer and cobalt species in a Co/TiO 2 catalyst. After reduction at 350 °C, the overlayer consisted of stoichiometric anatase TiO 2 , while cobalt remained partially reduced. Exposure to CO 2 /H 2 at 220 °C enabled complete cobalt reduction without affecting the TiO 2 overlayer. In contrast, pure CO 2 at 220 °C caused overlayer removal and full cobalt oxidation. The impact of this CO 2 ‐mediated reversibility on CO 2 hydrogenation was also evaluated. Although steady‐state activity was largely unaffected, the transient regime showed substantial changes in selectivity and behavior. These results demonstrate that different treatments can strongly influence both the stability and reactivity of Co/TiO 2 catalysts, highlighting the importance of dynamic SMSI effects in CO 2 hydrogenation.