Deuterium Exchange Reactions of Isobutane, n-Hexane, and n-Heptane Catalyzed over Platinum Single Crystal Surfaces

Article abstract of DOI:10.1021/j100232a019

Isotopic exchange reactions of isobutane, n-heptane, and n-hexane with deuterium gas have been investigated near atmospheric pressure in the temperature range 500-650 K over the flat (111) and kinked (10,8,7) crystal faces of platinum.The exchange kinetics at low conversion displayed zero activation energy, a first-order dependence on D2 pressure, and a strong negative-order dependence on the surface coverage by strongly bound carbonaceous species.Initial exchange rates and product distributions were not influenced appreciably by the presence of steps and kinks on the platinum surface, and the exchange product distributions varied little with temperature, D2 pressure, and surface composition.Hydrocarbon (HC) conversion and deuterium exchange rates measured simultaneously for n-hexane reactions catalyzed over Pt(111) revealed that deuterium exchange always occurs more rapidly as compared to all other competing chemical reactions.