Deuterium isotope effects for hydrocarbon reactions catalyzed over platinum single crystal surfaces

The initial rates of isobutane, neopentane, cyclohexane, n-hexane, and n-heptane skeletal rearrangement reactions catalyzed in the presence of deuterium gas over the flat(111), stepped(13,1,1), and kinked(10,8,7) platinum single crystal surfaces were measured at atmospheric pressures and 520 to 640 K. Inverse isotope effects [(R/sub D//R/sub H/) = 1.3 to 3.3] were detected for a variety of hydrogenolysis, isomerization, and C5 cyclization reactions. The inverse isotope effects that appear to arise from a combination of kinetic and thermodynamic isotope effects displayed magnitudes that were not dependent on the platinum surface structure. 6 figures, 3 tables