This presentation will describe the use of quantitative operando IR spectroscopy to determine the role of CO- and CO₂-derived adsorbates as reaction intermediates or spectator species for various reactions. Spectral corrections of diffuse reflection FT-IR spectroscopy (DRIFTS) signals and potential pitfalls will be first presented. CO hydrogenation over cobalt-based Fischer-Tropsch catalysts will show the presence of formates with various reactivities, the most reactive fraction of these formates being likely responsible for the formation of minor product methanol, but not that of hydrocarbons. Carbonyl multi-bonded to cobalt sites were shown to be responsible for hydrocarbon formation, while linear CO were spectators. Various formates and methoxy species observed during CO₂ hydrogenation to methanol over Cu/ZrO₂ will be discussed. Linear CO bound to metallic Pt will be shown to be main reaction intermediates in the room temperature-oxidation of CO, while CO bound to oxidic Pt species are spectators. These data underline the complexity in interpreting adsorbate reactivities on surfaces presenting different sites or phases.

CV: https://orcid.org/0000-0001-7953-2883