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.