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

Marcin Pisarek 1,2Maria Janik-Czachor 2

1. Warsaw University of Technology, Faculty of Materials Science and Engineering (InMat), Wołoska 141, Warszawa 02-507, Poland
2. Polish Academy of Sciences, Institute of Physical Chemistry, Kasprzaka 44/52, Warszawa 01-224, Poland

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 an 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 ageing 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.

This work was financially by the Foundation for Polish Science through a generous fellowship for M.Pisarek.

 

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Presentation: Poster at E-MRS Fall Meeting 2006, Symposium B, by Marcin Pisarek
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-04-27 10:46
Revised:   2009-06-07 00:44