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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  and
M. Janik-Czachor
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.

Keywords

Cu-based amorphous alloysCu segregationcatalytic dehydrogenationactive sitesaverage characterizationlocal characterizationSEMAuger microanalysis (AESSAM)
Type
MATERIALS APPLICATIONS
Information
Microscopy and Microanalysis , Volume 12 , Issue 3 , June 2006 , pp. 228 - 237
Copyright
© 2006 Microscopy Society of America

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References

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