Adsorption of alcohols on γ-alumina (1 1 0 C)

Adsorption of methanol, ethanol, propanol and isopropanol on the gamma-alumina (110 C surface is investigated with semiempirical (PM3) cluster calculations. It is found that all four alcohols chemisorb to the alumina surface when they come close to the surface with suitable orientation. The chemisorption is an exothermic process when the 011 hydrogen interacts with a surface oxygen atom that is in turn close to a cation vacancy. In this case only O-H interaction is required for successful dehydrogenation. If the surface oxygen has no adjacent vacancies, both the oxygen and hydrogen from the alcohol OH must interact with the surface for successful dehydrogenation. Alkoxide formation by abstraction of the alcohol OH proton is found to be favored over alkoxide production by nucleophilic attack of the alcohol C-alpha by a surface Lewis base site followed by C-OH bond scission. (C) 2002 Elsevier Science B.V. All rights reserved.