Modulation Excitation Spectroscopy: A Powerful Tool to Elucidate Active Species and Sites in Catalytic Reactions.

ConspectusA rational design of catalysts requires a knowledge of the active species and sites. Often, catalyst surfaces are dominated by spectators, which do not participate in the reaction, while the catalytically active species and sites are hidden. Modulation-excitation spectroscopy (MES) allows discrimination between active and spectator species by applying a concentration modulation, which is translated into the active (that is, actively responding) species by phase-sensitive detection (PSD).

Importance of Metal-Support Interactions for CO Hydrogenation: An Near-Ambient Pressure X-ray Photoelectron Spectroscopy Study on Gold-Loaded InO and CeO Catalysts.

Metal-support interactions, which are essential for the design of supported metal catalysts, used, e.g., for CO activation, are still only partially understood.

Refining the mechanism of CO and H activation over gold-ceria catalysts by IR modulation excitation spectroscopy.

The activation and utilization of the greenhouse gas CO is of great interest for the energy transition as a fossil-free carbon source for mitigating climate change. CO hydrogenation the reverse water-gas shift reaction (RWGSR) converts CO to CO, a crucial component of syngas, enabling further transformation by means of the Fischer-Tropsch process. In this study, we unravel the detailed mechanism of the RWGSR on low-loaded Au/CeO catalysts using IR modulation excitation spectroscopy (MES), by periodically modulating the concentration of the reactants, followed by phase-sensitive detection (PSD).

Unraveling the Active Vanadium Sites and Adsorbate Dynamics in VO/CeO Oxidation Catalysts Using Transient IR Spectroscopy.

The oxidative dehydrogenation (ODH) of propane over supported vanadia catalysts is an attractive route toward propene (propylene) with the potential of industrial application and has been extensively studied over decades. Despite numerous mechanistic studies, the active vanadyl site of the reaction has not been elucidated. In this work, we unravel the ODH reaction mechanism, including the nuclearity-dependent vanadyl and surface dynamics, over ceria-supported vanadia (VO/CeO) catalysts by applying (isotopic) modulation excitation IR spectroscopy supported by Raman and UV-vis spectroscopies.