In situ infrared approach to unravel reaction intermediates and pathways on catalyst surfaces

CO2 Methanation over Rh/CeO2 Studied with Infrared Modulation Excitation Spectroscopy and Phase Sensitive Detection

“…This assignment is questionable due to the small splitting and in fact the authors previously assigned carboxylates to one peak at 1506 cm −1 for its asymmetric vibration and a (weak) peak at 1310 cm −1 for the symmetric vibration [15] referencing to studies on Pt/ceria catalysts by Jin et al [24]. Instead, the peaks could correspond to monodentate carbonate (m-CO 3 ) or polydentate carbonate (p-CO 3 ), for which the low ν as−s split would rather suggest the polydentate configuration [25][26][27][28]. As shown in our previous study, CeO 2 is expected to alternate between a partially reduced and oxidized state during the H 2 modulation [13].…”

Boosting the Hydroformylation Activity of a Rh/CeO2 Single-Atom Catalyst by Tuning Surface Deficiencies

“…While Rh-catalyzed hydroformylation is usually carried out at 80–120 °C to achieve high activity, ,, the pseudo in situ FTIR spectroscopy of adsorbed CO with C 3 H 6 and H 2 was conducted at room temperature to minimize the rapid scrambling of adsorbed species and allow for the observation of conversion of adsorbed species to products in a time scale of seconds to minutes . Thus, the reactivity of adsorbed CO on 0.06% Rh/CeO 2 with C 3 H 6 and H 2 was first studied at 25 °C.…”

“…While Rh-catalyzed hydroformylation is usually carried out at 80−120 °C to achieve high activity, 5,25,52 the pseudo in situ FTIR spectroscopy of adsorbed CO with C 3 H 6 and H 2 was conducted at room temperature to minimize the rapid scrambling of adsorbed species and allow for the observation of conversion of adsorbed species to products in a time scale of seconds to minutes. 62 Thus, the reactivity of adsorbed CO on 0.06% Rh/CeO 2 with C 3 H 6 and H 2 was first studied at 25 °C. For 0.06% Rh/CeO 2 -400 °C, the bands (2084 and 2018 cm −1 ) attributed to Rh(CO) 2 were gradually shifted to opposite directions (2082 and 2020 cm −1 ) with a weak signal at 1715 cm −1 due to the aldehyde group that appeared at 11 min after purging H 2 and propylene (Figure 6a).…”

Infrared spectroscopic monitoring of solid-state processes

“…monitoring of chemical processes with simultaneous measurement of reaction products, 70 it is very frequent that studies titled ‘ in situ ’ are focused on monitoring the evolution of chemical species during reactions, 71 especially products, which is often evident even from the publication title. 72 For the sake of terminological simplification without losing the essence, exclusively the term ‘ in situ ’ will be used further in this text.…”