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In-situ local structure analysis of Au/zeolite catalysis during heat treatment

  • Only SPring-8

Inquiry number

SOL-0000001207

Beamline

BL01B1 (XAFS I)

Scientific keywords

A. Sample category inorganic material
B. Sample category (detail) amorphous, glass
C. Technique absorption and its secondary process
D. Technique (detail) XAFS, EXAFS, XANES
E. Particular condition polarization (linear), high-T (~500 C), time-resolved (slow)
F. Photon energy X-ray (4-40 keV)
G. Target information local structure, structural change, function and structure, function

Industrial keywords

level 1---Application area Chemical product, others
level 2---Target catalysis
level 3---Target (detail)
level 4---Obtainable information local structure, electronic state, chemical state
level 5---Technique XAFS, NEXAFS

Classification

A80.34 catalysis, M40.10 XAFS

Body text

In this solution, in-situ EXAFS method at Au L3-edge was applied to study local structure change of Au/zeolite, catalysis for CO-O2 reaction, during pretreatment process at high temperature. The in-situ EXAFS method is a powerful technique to study local structure change (distance, coordination number, species of neighbor atoms) of selected elements during reaction process. To follow the transient structure change with temperature increase, quick XAFS (QXAFS) mode was used. Figure 1 shows radial structure function of Au atom after Fourier transform of EXAFS spectra during heat treatment Figure 2 shows dependence of nearest neighboring Au-Au coordination number on the temperature. EXAFS analysis revealed that on the Au/H-Y zeolite and Au/USY zeolite, formation of Au metal clusters with appropriate size by heat treatment lead to the high catalytic activity.

Fig.1 Radial structure function of Au atom

Fig.2 Dependence of nearest neighboring Au-Au coordination number on the temperature

[ K. Okumura, K. Yoshino, K. Kato and M. Niwa, The Journal of Physical Chemistry B 109, 12380-12386 (2005)", Fig. 6, 8,
©2005 American Chemical Society ]

Source of the figure

Original paper/Journal article

Journal title

J. Phys. Chem. B, 109 (2005) 12380

Figure No.

6, 8

Technique

XAFS spectra of dense samples are taken in a transmission mode. This method is performed by measuring x-ray absorption as a function of x-ray energy around an absorption edge of a selected element. At present, most of the transmission XAFS measurements in BL01B1 are performed in a QXAFS mode, and high quality data can be taken in a short measurement time. Acquisition time per QXAFS is 1 min in this solution.

Source of the figure

No figure

Required time for experimental setup

4 hour(s)

Instruments

Instrument Purpose Performance
XAFS Measurement System Measurement of XAFS spectra 3.8-113 keV
Ionization Chamber Measurement of transmission mode XAFS concentration > 1000 ppm

References

Document name
K. Okumura et al., J. Phys. Chem. B, 109 (2005) 12380

Related experimental techniques

Questionnaire

The measurement was possible only in SPring-8. Impossible or very difficult in other facilities.
This solution is an application of a main instrument of the beamline.
This solution is application of a new instrument installed in the past two years.
With user's own instruments.

Ease of measurement

Middle

Ease of analysis

Middle

How many shifts were needed for taking whole data in the figure?

Less than one shift

Last modified 2022-05-06 15:21