THE CATALYTIC EXCHANGE WITH DEUTERIUM OF POLYMETHYLCYLCOPENTANES ON METAL FILMS. EVIDENCE FOR $pi$-BONDED INTERMEDIATES
A new mechanistic theory was developed to explain several reactions of hydrocarbons on metal catalysts. Interconversion can take place on the surface not only betweea onded monoadsorbed and diadsorbed intermediates but also between pi -bonded species provided that the reactant hydrocarbons contain three or more adjacent nonquaternary carbon atoms. Evidence for this theory was ohtained by the catalytic exchange with deuterium of several polymethylcyclopentanes on films of rhodium, palladium, plati num, and nickel, using a mass-spectrometric analytical technique. Studies on cis-trans isomerization, followed by gas-liquid chromatography, provided further support for the theory. Palladium gave the most striking evidence for pi -bonded intermediates. Rhodium was the most active metal for the exchange reactions and at low temperatures the role of onded intermediates was much greater than that of the pi -bonded which only participated in the reactions at higher temperatures comparable to those needed to bring about exchange on palladium. The behavior of nickel and platinum was intermediate between that of rhodium and palladium. Evidence is presented to show that on rhodium and nickel alpha alpha -diadsorbed intermediates permit the exchange process to propagate from the hydrogens on one side of cyclopentane rings to those on the other side. Platinum can cause exchange by alpha gamma -diadsorbed intermediates at the same temperatures as required to form pi -bonded species. Explanations are given for some apparently anomalous features of the distrib''tions of deuterocompounds formed oped rhodium. The application of the theory to several aspects of the reactions of hydrocarbons on metal catalysts is discussed. (auth)
- Research Organization:
- Queen's Univ., Belfast
- NSA Number:
- NSA-16-031601
- OSTI ID:
- 4787563
- Journal Information:
- J. Catalysis, Journal Name: J. Catalysis Vol. Vol: 1
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
ATOMS
BINDING ENERGY
CARBON
CATALYSIS
CHEMISTRY
CHROMATOGRAPHY
CONFIGURATION
CYCLOALKANES
DEUTERIUM
DEUTERIUM COMPOUNDS
DISTRIBUTION
GASES
HYDROCARBONS
HYDROGEN
ISOMERS
ISOTOPIC EXCHANGE
LAYERS
LIQUIDS
MASS SPECTROMETERS
METALS
METHYL RADICALS
NICKEL
PALLADIUM
PENTANE
PLATINUM
REACTION KINETICS
RHODIUM
SURFACES