In-situ local structure analysis of Au/zeolite catalysis during heat treatment
Inquiry number
SOL-0000001207
Beamline
BL01B1 (XAFS I)
Scientific keywords
A. Sample category | inorganic material |
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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 |
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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 |
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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