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    Kinetics, thermochemistry and mechanism of hydrogenolysis of aliphatic aldehydes on Ni–SiO2
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (09-12), 1978) Scott, Kevin F.; Abdulla, Mohammad A.; Hussein, Falah H.
    An investigation of the kinetics of the hydrogenolysis reaction of aliphatic aldehydes on Ni–SiO2 by stopped-flow chromatography is described and the rate plots fitted to theoretical equations which reveal that the reaction proceeds in two kinetically discernible stages, one apparently by a Langmuir–Hinshelwood mechanism and the other by a Rideal–Eley mechanism. These conclusions are supported by the dependences of the rates on the hydrogen pressure. Thermochemical measurements using a microcalorimetric device, have enabled the determination of the thermochemistry of a reaction leading to a surface species. A discussion of the prevailing mechanism is presented.
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    Hydrogenolysis of Cyclopentane and Hydrogenation of Benzene on Palladium Catalysts of Widely Varying Dispersion
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (1), 1978) Fuentes, Sergio; Figueras, Francois
    Adsorption of hydrogen and oxygen, titration of preadsorbed oxygen, benzene hydrogenation and cyclopcntane hydrogenolysis were performed on palladium catalysts of widely varying dispersion. A change in the stoichiometry of oxygen adsorption is found when increasing the metallic dispersion. On clean supports, free of sulphur and iron, the turn over number for both reactions of hydrocarbons is constant and independant of the dispersion of Pd. After a suitable reduction, sulphur may preferentially inhibit hydrogenolysis, while iron preferentially inhibits hydrogenation. On an industrial silica support the turn over for hydrogenolysis changes with dispersion ; this elTect is attributed to contamination of Pd by iron from the support.
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    Hydrogenolysis of some Saturated Hydrocarbons over a Platinum Black Catalyst
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (11), 1974) Guczi, L.; Sarkany, A.; Tetenyi, P.
    Deuterium exchange reactions of methane, ethane, propane and neopentane, and the hydrogenolysis and isomerization of ethane, propane, n-butane and isobutane on platinum black have been studied in the temperature range 363–743 K. There is a gap of 150 K between the temperature of deuterium exchange and that of hydrogenolysis and isomerization. Only at high hydrogen pressure (about 50 kN m–2) and at low catalytic activity is the hydrogenolysis characterized by selective loss of a terminal methyl group, except for n-butane in which there is an equal chance of any of the C—C bond rupturing. The selectivity for isomerization has a maximum at high hydrogen pressure. These values together with kinetic data suggest that the ability of platinum in an exchange reaction to convert weakly bonded intermediates into strongly bonded ones is much less than that of nickel. The phenomenon of π-olefin and π-allyl bond conversion is applied in part to explain the results obtained. Brief comparison is given between the catalytic properties of platinum and those of nickel for the reactions investigated.
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    Hydrogenolysis of Ethane on Evaporated Copper-Nickel Alloy Films
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (4), 1972) Plunkett, T. J.; Clarke, J. K. A.
    The hydrogenolysis of ethane has been studied on a series of copper-nickel film catalysts at temperatures greater than 320°C, where the alloys are single-phased. A gradual fall in activity with nickel content is found with no break at median compositions and, while activity persists to ca. 4 % nickel content, copper films are inactive. This behaviour is not amenable to description by the simple (rigid) band approach to the electronic structure of alloys but emphasizes the retention of catalytic character of individual nickel atoms
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    Hydrogenolysis of Saturated Hydrocarbons on Evaporated Platinum Films
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (11), 1972) Dowie, R. S.; Whan, D. A.; Kemball, C.
    The reactions of ethane, propane, n-butane, isobutanc and neopentane have been examined in the presence of deuterium on platinum films. Details of the products of exchange, hydrogenolysis and, where possible, isomerization are reported. The kinetic behaviour of the hydrogenolysis reaction showed a trend in that reactions of ethane were acccleratory, those of propane maintained a constant rate and those of molecules with four or more carbon atoms decelerated with time. The retardation in rates was much more marked with branched chain than with linear hydrocarbons. The results are discussed in terms of the nature of the adsorbed species accumulating on the surface, species possessing some carbonium ion character being likely precursors to the material responsible for the observed poisoning. Little additional mechanistic information was obtained from an analysis of the deuterium contents of the various molecules as exchange was fast compared to hydrogenolysis or isomerization, leading to rapid isotopic equilibration. A fragmentation correction scheme taking into account the influence of molecular composition on bond rupture has also been developed for analysis of the mass spectral data.