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CAT Beamline

CAT

The CAT end station of the CAT-ACT beamline at ANKA is dedicated to catalytic research using X-ray spectroscopic techniques. It will be operated by the Grunwaldt group at the Institute for Chemical Technology and Polymer Chemistry (http://www.itcp.kit.edu/grunwaldt/) and the Institute of Catalysis Research and Technology (http://www.ikft.kit.edu/234.php).

Synchrotron radiation based techniques have evolved as key speciation methods in catalysis research, especially with respect to in-situ and in-operando X-ray based characterization techniques as a basis for a rational design of heterogeneous catalysts. Knowledge of oxidation state and coordination environment of the catalytically active centers, nanoparticle morphology etc. contributed significantly to a deeper understanding of heterogeneously catalyzed reactions and serves today as a basis for the design of new catalysts and for first-principles kinetic modeling. The beamline design places emphasis on in situ X-ray Absorption Spectroscopy (XAS) in terms of X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure spectroscopy (EXAFS) in a photon energy range from 5 keV up to 60 keV. These techniques are combined with X-Ray Diffraction (XRD), Infrared Spectroscopy and other correlative spectroscopic methods. Special infrastructure for catalytic studies under reaction conditions in gas phase, liquid phase and at elevated pressure has been or is currently being built up.

Key references:

  1. J.-D. Grunwaldt, M. Caravati, S. Hannemann, A.Baiker, „In situ X-ray Absorption Spectroscopy under Reaction Conditions: Suitability of Different Reaction Cells for Combined Catalyst Characterization and Time-resolved Studies“, Phys. Chem. Chem. Phys. 6, 3037 (2004).
  2. J.-D. Grunwaldt, A. Baiker, “In situ Spectroscopic Investigation of Heterogeneous Catalysts and Reaction Media at High Pressure”, Phys. Chem. Chem. Phys. 7, 3526 (2005).
  3. S. Hannemann, M. Casapu, J.-D. Grunwaldt, P. Haider, P. Trüssel, A. Baiker, and E. Welter, “A versatile in situ spectroscopic cell fluorescence/transmission EXAFS and X-ray diffraction of heterogeneous catalysts in gas and liquid phase”, J. Synchrotron Radiat. 14, 345 (2007).
  4. J.-D. Grunwaldt, In situ Analysis of Heterogeneous Catalysts in Chemical Energy Conversion, in: R. Schlögl (Ed.) Chemical Energy Storage, Walter de Gruyter GmbH, Berlin/Boston, ISBN: 978-3-11-026632-0, 2012, pp. 311.
  5. A. Zimina, K .Dardenne, M. A. Denecke, J.- D. Grunwaldt, E. Huttel, H. Lichtenberg, S. Mangold, T. Pruessmann, J. Rothe, R. Steininger, T.Vitova, “ The CAT-ACT Beamline at ANKA: A new high energy X-ray spectroscopy facility for CATalysis and ACTinide research“, J. Phys. Conf. Ser., accepted for publication (2015)

Layout

CAT Layout

Schematic Beamline Layout

 

Methods

Available Methods, Obtainable Parameters

The CAT beamline offers  hard X-ray spectroscopy for in-situ and in-operando studies
including the following methods:

X-ray Absorption Spectroscopy for elements between K and Er:

  • Information about the local atomic geometry (EXAFS)
  • Chemical state of the absorbing atom (XANES)
  • Investigations on ordered (crystalline) and disordered (amorphous, liquid) materials
  • Dilute species and light elements (XAS in fluorescence mode)
  • In situ and operando cells for measurements under reaction conditions

 

 

Under Construction/planned

 

Fluorescence Spectroscopy:

  • High sensitivity for low concentrations
  • XAS measurements in fluorescence mode, X-ray Emission Spectroscopy

 

Diffraction experiments investigation of longe range order, crystalline phases and crystallite sizes, support materials

 

Infrared Spectroscopy

  • Analysis of species adsorbed on catalyst surfaces

Characteristics

Energy range

3.1 keV – 60 keV

Energy resolution (dE/E)

Si(111) 1x10-3; Si(311) 1x10-4 

(theoretical values) 

Source

Wiggler 2.5 T (40 poles,  48 mm period length, 15 mm vacuum gap)

Optics

Vertically collimating Si mirror with Rh/Pt coatings

DCM with Si(111) and Si(311) LN2 cooled crystal pairs, fixed exit

Toroidal focusing Si mirror with Rh/Ir coatings

Beam size at sample position

approx. 1 mm (hor) x 1mm (vert)  below 35 keV with mirrors

above ~ 35 keV mirrorless operation

Flux at sample position

Currently further optimized (2nd phase of commissioning)

Experimental station

 

3 ionization chambers for XAS in transmission mode

combined XRD-XAS setup with MediPix Detector

combined IR-XAS  setup with DRIFTS spectrometer

Implementation of detector for X-ray fluorescence measurements planned

Sample environment

sample cells and infrastructure for experiments under reaction conditions (reactive gas supply and gas dosing units, liquid phase, high pressure, high temperature)