Reactions of hydrogen atoms with acetone monolayers adsorbed on graphite monolayer covered Pt(111) surfaces

Acetone monolayers were prepared on C covered Pt(111) surfaces and exposed to gaseous H(D) atoms at 90 K. Reaction products were investigated with HREELS and TDS methods. Two major reaction pathways were identified. (1) transformation of acetone to isopropanol via two consecutive hydrogenation steps; (2) H abstraction from acetone methyl groups with subsequent rehydrogenation of the methylene group. Since two-fold H abstraction from the isopropanol product restores the acetone surface reactant, an equilibrium between acetone and isopropanol is established on the surface. This equilibrium is perturbed by side reactions in which propane, propene and water are formed, e.g. via OH abstraction from isopropanol. The cross-sections of the H induced reactions of a few tenths of an angstrom squared are compatible with the operation of an Eley-Rideal mechanism, (C) 1999 Elsevier Science B.V. All rights reserved.