Catalytic methanol oxidation over copper: Observation of reaction-induced nanoscale restructuring by means of in situ time-resolved X-ray absorption spectroscopy

Chemistry - A European Journal

Volumn 6, Issue 10, 2000, Pages 1870-1876

  Böttger, Ingolf ^a   Schedel Niedrig, Thomas ^a   Timpe, Olaf ^a   Gottschall, Rainer ^a   Hävecker, Michael ^a   Ressler, Thorsten ^a   Schlögl, Robert ^a  

^a FRITZ HABER INSTITUT DER MAX PLANCK GESELLSCHAFT   (Germany)

Author keywords

Copper; Heterogeneous catalysis; Oxidation; X ray absorption

Indexed keywords

ARTICLE; CATALYSIS; CRYSTALLIZATION; MOLECULAR INTERACTION; OXIDATION; REACTION ANALYSIS; STRUCTURE ANALYSIS;

EID: 0034660442     PISSN: 09476539     EISSN: None     Source Type: Journal    
DOI: 10.1002/(sici)1521-3765(20000515)6:10<1870::aid-chem1870>3.0.co;2-0     Document Type: Article

References (41)

1. Gmelins Handbuch der anorganischen Chemie: Kupfer, Verlag Chemie, Weinheim, Teil B, 1958, 24; Gmelins Handbuch der anorganischen Chemie: Kupfer, Verlag Chemie, Weinheim, Teil D, 1963, 26.
2. Gmelins Handbuch der anorganischen Chemie: Kupfer, Verlag Chemie, Weinheim, Teil B, 1958, 24; Gmelins Handbuch der anorganischen Chemie: Kupfer, Verlag Chemie, Weinheim, Teil D, 1963, 26.
3. A. Phillips, E. N. Skinner, Am. Inst. Min. Met. Eng. Techn Publ. 1941, 1280, 1.
4. F. R. Rhines, C. H. Mathewson, Trans. Am. Inst. Min. Met. Eng. Inst. Metals Divis 1934, 11, 337.
5. E. A. Enofev, F. N. Streltsov, A. N. Solovov, O. F. Velichkina, A. Tabanakov, Zavod. Lab. 1988, 54.
6. N. H. Santander, O. Kubaschewski, "The Thermodynamics of the Cu-O System", High Temp. High Pressures 1975, 7, 573.
7. H. Werner, D. Herein, G. Schulz, U. Wild, R. Schlögl, Catal. Lett. 1997, 49, 109.
8. T. Lederer, D. Arvanitis, G. Comelli, L. Tröger, K. Baberschke, Phys. Rev. B 1993, 48, 15390.
9. J. Urban, H. Sack-Kongehl, K. Weiss, Catal. Lett. 1997, 49, 101.
10. A. Knop-Gericke, M. Hävecker, T. Neisius, T. Schedel-Niedrig, Nucl. Instr. Meth. A 1998, 406, 311.
11. M. Hävecker, A. Knop-Gericke, T. Schedel-Niedrig, R. Schlögl, Angew. Chem. 1998, 110, 2049; Angew. Chem. Int. Ed. 1998, 37, 1939.
12. M. Hävecker, A. Knop-Gericke, T. Schedel-Niedrig, R. Schlögl, Angew. Chem. 1998, 110, 2049; Angew. Chem. Int. Ed. 1998, 37, 1939.
13. A. Knop-Gericke, M. Hävecker, T. Schedel-Niedrig, Appl. Surf. Sci. 1999, 142, 438.
14. M. Hävecker, A. Knop-Gericke, T. Schedel-Niedrig, R. Schlögl, Catal. Lett. in press.
15. I. Böttger, T. Schedel-Niedrig, T. Neisius, E. Kitzelmann, G. Weinberg, D. Demuth, R. Schlögl, Phys. Chem. Chem. Phys. in press.
16. T. Neisius, PhD Thesis, Technische Universität Berlin, 1997.
17. M. Hagelstein, C. Ferrero, U. Hatje, T. Ressler, W. Metz, J. Synchrotron Rad. 1995, 2, 174.
18. T. Ressler, M. Hagelstein, U. Hatje, W. Metz, J. Phys. Chem. B 1997, 101, 6680.
19. T. Ressler, M. Hagelstein, U. Hatje, W. Metz, J. Phys. IV France 1997, 7, 731.
20. ESRF Beamline Handbook, 1995, p. 123.
21. 12 photons per second at the sample and a time resolution below 100 μs can be reached.
22. J. Find, PhD Thesis, Technische Universität Berlin, 1998.
23. J. Wölk, R. Gottschal, G. Mestl, R. Schlögl, unpublished results.
24. A special designed reactor equipped with gas-flow controllers and a mass spectrometer as product gas monitor is used. A Cu catalyst (14.7 wt% copper) as well as thin polycrystalline copper foils (3 μm thick, 99.98 + %, Goodfellow) are used. The supported catalyst was prepared by using copper carbonate (malachite) supported on carbon and was pressed to a self-supported ≈1-mm-thick pellet. Scanning electron microscopy (SEM) images of the calcinated (heated in air at 400 K for 2 h) and subsequently reduced supported copper catalyst (heated in methanol atmosphere at 670 K overnight) show that the copper spreading on the carbon support cluster decreases after the reduction treatment; this is attributable to a lower surface free energy of small spherical metal particles.
25. -1). In order to modify the oxygen contribution in the gas stream, the flow of synthetic air was changed.
26. o signals through air or graphite are used as the background absorption signals for the Cu(poly) catalyst or the carbon-supported catalyst, respectively. The energy calibration of the EXAFS spectra within a series is performed by means of reference spectra for Cu(poly) foil oxidized in air at the same temperature to CuO which are measured before and after an EXAFS series, and additionally, by means of a reference CuO EXAFS spectrum. The first three peaks at the threshold of the copper K-absorption edge at 8.9980 keV, 9.0128 keV, and 9.0517 keV, respectively, and, additionally, the mininum between the second and third peak of the reference spectra are used as energy calibration points.
27. A. G. McKale, B. W. Veal, A. P. Paulikas, S. K. Chan, G. S. Knapp, J. Am. Chem. Soc. 1988, 110, 3763.
28. [27, 28] which are used afterwards for the one shell fits.
29. J. J. Rehr, R. C. Albers, Phys. Rev. B 1990, 41, 8139.
30. J. J. Rehr, R. C. Albers, S. I. Zabinsky, Phys. Rev. Lett. 1992, 69, 3397.
31. [27, 28] Coordination numbers in the range of 10.8 ± 1.0 to 12.4 ± 1.0 and nearest-neighbour bond lengths of 2.55 ± 0.02 Å are obtained for the polycrystalline copper bulk sample, indicative of densely packed face-centered cubic copper metal. The coordination numbers of 7.4 ± 1.0 to 8.9 ± 1.0 of the particles are found to be somewhat smaller, while the nearest-neighbor Cu-Cu bond length of 2.55 ± 0.02 Å is found to be the same as in the copper foil.
32. The alterations are given relative to the RDF maximum position of bulk copper metal of 2.57 ± 0.02 Å (570 ≤ T ≤ 670 K) set to zero at the ordinate axis in the figure.
33. [27, 28]
34. A constant RDF maximum position is found over a long-time period of about 1600 s (27 minutes) within the statistical variation under steady-state reaction conditions (i. e. at constant methanol turnover), which strongly indicates that external effects related to the X-ray source for example, can be excluded.
35. In the course of a temperature increase from 573 to 673 K, the thermal expansion of the first Cu-Cu coordination shell distance in the bulk metal is 0.0046 Å (from 2.5852 to 2.5898 Å; derived by means of XRD analysis), which is about a factor of 6 smaller than the observed change of the RDFs maximum position of 0.03 ± 0.01 Å. This strongly indicates that a methanol turnover (i. e. an oxygen) induced bulk lattice distortion is observed in the catalyst systems that cannot be explained only by the thermal lattice expansion or contraction caused by a possible temperature change in the course of the methanol oxidation reaction.
36. M. Lenglet, K. Kartouni, J. Machefert, J. M. Claude, P. Steinmetz, E. Beauprez, J. Heinrich, N. Celati, Mater. Res. Bull. 1995, 30, 393.
37. B. S. Clausen, H. Topsøe, J. Catal. 1993, 141, 368.
38. B. S. Clausen, L. Gråbæk, G. Steffenesen, P. L. Hansen, H. Topsøe, Catalysis Today 1994, 21, 49.
39. E. C. Marques, D. R. Sandstrom, F. w. Lytle, R.B Greegor, J. Chem. Phys. 1982, 77, 1027.
40. M. Mavrikakis, B. Hammer, J. K. Nørskov, Phys. Rev. Lett. 1998, 81, 2819.
41. F. Besenbacher, I. Chorkendorff, B. S. Clausen, B. Hammer, A. M. Molenbroek, J. K. Nørskov, Science 1998, 279, 1913.