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1631238 
Journal Article 
Dehydrogenation of isopropyl alcohol on carbon-supported Pt and Cu-Pt catalysts 
Rioux, RM; Vannice, MA 
2005 
Yes 
Journal of Catalysis
ISSN: 0021-9517
EISSN: 1090-2694 
233 
1 
147-165 
WOS:000230122100016 
The kinetics of isopropyl alcohol (IPA) dehydrogenation over
carbon-supported Pt and three bimetallic Cu-Pt catalysts were examined and compared with previous
results for carbon-supported Cu. Adsorption of H(2) and CO, dissociative chemisorption of N(2)O,
and the titration of adsorbed O atoms by H(2) and CO were used to determine surface compositions
and metal dispersion. Monometallic platinum catalysts had a higher specific activity than
monometallic Cu catalysts and the bimetallic catalysts; for example, at 448 K and 14 Torr IPA,
for an activated carbon heat treated at 1223 K as the support, the turnover frequency (TOF) on
the Pt catalyst was 0.11 s(-1), the TOF on the Cu catalyst was 0.020 s(-1), and the TOFs on the
three bimetallic catalysts were between 0.006 and 0.043 s-1. Reaction orders were typically
between 0 and 1 for IPA and slightly negative for acetone and H(2). Increasing the Cu loading
reduced the number of surface Pt atoms, and 2 the kinetic behavior became similar to that of
monometallic copper catalysts. The apparent activation energy for acetone production from IPA on
Pt/C was 6.8 kcal mol(-1), compared with 21 kcal mol(-1) for the monometallic Cu/C catalysts.
Apparent activation energies for the Cu-Pt/C catalysts (7-9 kcal mol(-1)) were comparable to
those of Pt/C at lower temperatures and decreased further to similar to 3 kcal mol(-1) above 443
K. This decrease is not due to diffusional limitations and can be explained by a decrease in the
surface coverage of IPA. A Langmuir-Hinshelwood model invoking cleavage of the alcohol O-H bond
to form a surface isopropoxide species as the rate-deterraining step fit the data well and
accounted for the shift in the apparent activation energy. Physically meaningful values of
enthalpies and entropies of adsorption were obtained from the fitting parameters contained in the
L-H rate expression. Additional evidence for adsorbed IPA and acetone was provided by infrared
spectra of the catalysts obtained under reaction conditions. (c) 2005 Elsevier Inc. All rights
reserved. 
isopropanol dehydrogenation; dehydrogenation of alcohols; Pt/C and Pt-Cu/C catalysts; kinetics of dehydrogenation; carbon supports