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Microstructural and Auger Microanalytical Characterization of Cu-Hf and Cu-Ti Catalysts

Published online by Cambridge University Press:  16 May 2006

M. Pisarek
Affiliation:
Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, 02-507 Warsaw, Poland
M. Janik-Czachor
Affiliation:
Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
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Abstract

Degradation processes occurring at the surface and in the bulk of Cu-based amorphous alloys during cathodic hydrogen charging were used for promoting the catalytic activity of such alloys. These processes modifying the structure, composition, and morphology of the substrate proved to be useful methods for transforming Cu-Hf and inactive Cu-Ti amorphous alloy precursors into active and durable catalysts. Indeed, their catalytic activity for dehydrogenation of 2-propanol increased up to a conversion level of ∼60% at selectivities to acetone of about 99% for Cu-Ti and to conversion of ∼90% at selectivities of ∼95% for Cu-Hf. Previous attempts carried out by aging in air or hydrogen charging from the gas phase resulted in a maximum conversion level up to 15% for Cu-Hf and up to 3% for Cu-Ti. High resolution Auger spectroscopy allowed changes occurring during the activation process to be identified, namely, the formation of small Cu particles on the HfO2 surface and the formation of highly porous particles containing mostly Cu and some Ti and O (Cu-Ti-O) on a Cu-Ti substrate. Differences in the chemistry and structure of both catalysts are discussed, and the implications for catalytic function are considered. A probable configuration of active sites on the Cu-Ti-O/Ti-O-Cu catalyst for dehydrogenation of 2-propanol is proposed.

Type
MATERIALS APPLICATIONS
Copyright
© 2006 Microscopy Society of America

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References

REFERENCES

Briggs, D. & Grant, J.T. (2003). Surface Analysis by Auger and X-Ray Photoelectron Spectroscopy. Chichester, UK: IM Publications.
Chung, M.-J., Han, S.-H., Park, K.-Y., & Ihm, S.-K. (1993). Differing characteristics of Cu and ZnO in dehydrogenation of ethanol: A deuterium exchange study. J Mol Catal 79, 335345.Google Scholar
Ertl, G. & Kueppers, J. (1985). Low Energy Electrons and Surface Chemistry, pp. 1764. Weinheim: VCH.
Fridman, V.Z., Darydor, A.A., & Titievsky, K. (2004). Dehydrogenation of cyclohexanol on copper-containing catalysts II. The pathways of the cyclohevanol dehydrogenation reaction to cyclohexanone on copper-active sites in oxidation state Cu0 and Cu+. J Catal 222, 545557.Google Scholar
Fromm, E. & Gebhardt, E. (1976). Gase und Kohlenstoff in Metallen. pp. 406416. Berlin, Heidelberg, New York: Springer-Verlag.
Ismail, N., Gebert, A., Uhlemann, M., Eckert, J., & Schultz, L. (2001). Effect of hydrogen on Zr66Cu17.5Al7.5Ni10 metallic glass. J Alloy Comp 314, 170176.Google Scholar
Ismail, N., Uhlemann, M., Gebert, A., & Eckert, J. (2000). Hydrogenation and its effect on the crystallization behaviour of Zr55Cu30Al10Ni5 metallic glass. J Alloy Comp 298, 146152.Google Scholar
Jana, N.R. & Pal, T. (1998). Growing small metal particle as redox catalyst. Current Sci 75, 145149.Google Scholar
Janik-Czachor, M., Szummer, A., Bukowska, J., Molnar, A., Mack, P., Filipek, S.M., Kedzierzawski, P., Kudelski, A., Pisarek, M., Dolata, M., & Varga, M. (2002). Modification of surface activity of Cu-based amorphous alloys by chemical processes of metal degradation. Appl Catal A 235, 157170.Google Scholar
Janik-Czachor, M., Szummer, A., Bukowska, J., Molnar, A., Mack, P., Filipek, S.M., Kedzierzawski, P., Kudelski, A., Pisarek, M., Dolata, M., & Varga, M. (2003). Modification of surface activity of Cu-based amorphous alloys by chemical processes of metal degradation. Appl Catal A 253, 539541 (erratum).Google Scholar
Kraus, M. (1997). Handbook of heterogeneous catalysis. In Dehydrogenation of Alcohols, Ertl, G., Knozinger, H. & Weitkamp, J. (Eds.), pp. 21592165. Weinheim: VCH.
Madix, R.J. (1980). Reaction kinetics and mechanism on metal single crystal surfaces. Adv Catal 29, 150.Google Scholar
Majorowski, S. & Baranowski, B. (1982). Diffusion coefficients of hydrogen and deuterium in highly concentrated palladium hydride and deuteride phases. J Phys Chem Sol 43, 11191128.Google Scholar
Molnar, A., Bertoti, J., Szepvolgyi, J., Mulas, G., & Cocco, G. (1998). Surface characterization of Cu-M (M = Ti, Zr, or Hf) alloy powder catalysts. J Phys Chem B 102, 92589265.Google Scholar
Mroz, S. (1996). Studies of composition of surfaces and interfaces with the use of Auger electron spectroscopy. Acta Phys Pol 89, 183194.Google Scholar
Nondek, L. & Sedlacek, J. (1975). Mechanism of dehydrogenation of secondary alcohols on chromia. J Catal 40, 3439.Google Scholar
Nowakowski, R., Seidel, C., & Fuchs, H. (2004). In situ STM studies of the ordering process of a nonplanar derivative of PTCDI on Ag (110). Surface Science 562, 5364.Google Scholar
Patterson, W.R., Roth, J.A., & Burwell, L., Jr. (1971). Isotopic exchange reactions involving alcohols, ketones, and deuterium on copper catalyst. J Am Chem Soc 93, 839846.Google Scholar
Pisarek, M. (2004). Doctor's thesis. Application of chemical processes to modification of Cu-based amorphous alloy precursors for catalysts. Warsaw University of Technology, p. 59.
Pisarek, M., Janik-Czachor, M., Gebert, A., Monar, M., Kedzierzawski, P., & Rac, B. (2004a). Effect of cathodic hydrogen charging on catalytic activity of Cu-Hf amorphous alloys. Appl Catal A 267, 18.Google Scholar
Pisarek, M., Janik-Czachor, M., Kedzierzawski, P., Molnar, M., Rac, B., & Szummer, A. (2004b). Modification of catalytic activity of Cu-Ti amorphous alloy ribbons by cathodic hydrogen charging. Pol J Chem 78, 13791389.Google Scholar
Pisarek, M., Janik-Czachor, M., Molnar, A., & Hughes, K. (2005). Catalytic activity of Cu-based amorphous alloy ribbons modified by cathodic hydrogen charging. Appl Catal A 283, 177184.Google Scholar
Pisarek, M., Janik-Czachor, M., Molnar, M., Mack, P., & Szummer, A. (2003). Effect of ageing in air and cathodic hydrogen charging on catalytic activity of Cu-based amorphous alloys: Cu-Zr, Cu-Hf. In Proceedings of XXXI School of Materials Science, Krakow-Krynica, Poland, October 7–10, 2003. pp. 537543 (in Polish).
Rioux, R.M. & Vannice, M.A. (2003). Hydrogenation/dehydrogenation reactions: Isopropanol dehydrogenation over copper catalysts. J Catal 216, 362376.Google Scholar
Sen, B. & Vannice, M.A. (1988). Metal-support effects on acetone hydrogenation over platinum catalysts. J Catal 113, 5271.Google Scholar
Szummer, A., Janik-Czachor, M., Molnar, A., Marchuk, I., Varga, M., & Filipek, S.M. (2001b). Effect of hydrogenation under high pressure on the structure and catalytic properties of Cu-Zr amorphous alloys. J Mol Catal A Chem 176, 205212.Google Scholar
Szummer, A., Pisarek, M., Dolata, M., Molnar, A., Janik-Czachor, M., Varga, M., & Sikorski, K. (2001a). Effect of ageing in air-corrosion on morphology and catalytic properties of Cu-based amorphous ribbons. Mater Sci Forum 337, 1528.Google Scholar
Zallen, R. (1984). The physics of amorphous solids. In Preparation of Amorphous Solids, (§1.2). New York: John Wiley and Sons, Inc.