A recent experimental study of 1- and 2-propanol in water feed over Pt/Al2O3 yielded dehydrogenation of 2-propanol to acetone, but formation of CO2 and ethane from 1-propanol. To rationalize this reactivity difference of primary and secondary alcohols, we explored computationally the dehydrogenation of land 2-propanol over Pt(111) as model. As product of 2-propanol, our calculations confirm acetone which adsorbs only weakly; thus, desorption occurs readily as the subsequent dehydrogenation would exhibit a high barrier. For 1-propanol we determined propionyl as strongly adsorbed intermediate which eventually undergoes C-C bond breaking. (C) 2011 Elsevier Inc. All rights reserved.