Catalysts at Work

The importance of catalysts

More than 90% of all chemical products have seen a catalyst in at least one production step. Heterogeneous catalysts play a main role in large-scale production of chemicals, including the current transition from fossil to sustainably produced products, as well as in the field of energy storage.

The catalysts required for this application area must be developed efficiently; this requires a thorough understanding of their characteristics. Operando conditions allow the investigation of catalyst properties under reaction conditions, which is essential for understanding the catalytic mechanism at the molecular level.

Since catalysis takes place mainly on surfaces, these are usually amorphous solids of high surface area and small particle size. Techniques based on X-rays are ideal. Classical X-ray diffraction is often not applicable; instead, X-ray absorption spectroscopy (XAS) has established itself in catalysis. This requires white X-rays, which are only made available at synchrotron radiation sources in high intensity.

Activity and spectra measurements combined

Ideally, the catalytic and X-ray experiments are combined. To optimize this, the CATACT beamline at the KIT light source was designed. It focuses on in situ X-ray absorption spectroscopy (XAS) in the form of X-ray absorption near-edge structure (XANES) and advanced X-ray absorption fine structure spectroscopy (EXAFS). This covers a photon energy range from 5 keV to 60 keV. These techniques are combined with X-ray diffraction (XRD), infrared spectroscopy and other correlative spectroscopic methods. A special infrastructure for catalytic investigations under reaction conditions in the gas phase, in the liquid phase and at elevated pressure has been or is currently being set up.

Special CATACT design

Ideally, the catalytic and X-ray experiments are combined. To optimize this, the CATACT beamline at the KIT light source was designed. It focuses on in situ X-ray absorption spectroscopy (XAS) in the form of X-ray absorption near-edge structure (XANES) and advanced X-ray absorption fine structure spectroscopy (EXAFS). This covers a photon energy range from 5 keV to 60 keV. These techniques are combined with X-ray diffraction (XRD), infrared spectroscopy and other correlative spectroscopic methods. A special infrastructure for catalytic investigations under reaction conditions in the gas phase, in the liquid phase and at elevated pressure has been or is currently being set up.

More measurements for a clearer picture

Furthermore, we measure at a large number of other measuring stations (PETRA III, SLS, SOLEIL, ESRF, BESSY, MAXIV, DIAMOND, etc.), which then allow a higher sensitivity, a better time resolution or a better spatial resolution based on the XANES/EXAFS experiment on CatAct. In addition, we carry the idea further: QEXAFS, XES, HERFD-XAS, Tomography, Ptychography, PDF, NAP-XPS, ED-XRD or SAXS are just a few other methods - depending on the experimental investigation.