The isomerization of isobutane and neopentane over evaporated films of platinum and palladium

Anderson, John R.

doi:10.1016/0021-9517(63)90010-1

Cited by 22 publications

(2 citation statements)

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“…the probability of any particular fragmentation process based on molecular composition only. The first term in square brackets in eqn (3) allows for the preferential dissociation of C-H compared with C-D bonds. The second term in square brackets incorporates the principle 2 o that the factors A and B have to be raised to powers corresponding to the number of D or H atoms respectively in the molecule.…”

Section: Discussionmentioning

confidence: 99%

Hydrogenolysis of saturated hydrocarbons on evaporated platinum films

Dowie¹,

Whan²,

Kemball³

1972

J. Chem. Soc., Faraday Trans. 1

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The reactions of ethane, propane, n-butane, isobutane 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 acceleratory, 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 coniposi tion on bond rupture has also been developed for analysis of the mass spectral data.

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Section: Discussionmentioning

confidence: 99%

Hydrogenolysis of saturated hydrocarbons on evaporated platinum films

Dowie¹,

Whan²,

Kemball³

1972

J. Chem. Soc., Faraday Trans. 1

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“…In type A isomerization, the number of branchings in the carbon skeleton remains constant, and rearrangement occurs via an alkyl shift through the formation of a carbocation on acid sites . In type B isomerization, which is more characteristic of bifunctional metal/acid catalysts, ,, the number of branchings in the carbon skeleton increases or decreases through a mechanism involving a cyclopropanoid species, a metallocyclobutane species, or a substituted cylcopentane species . Type A rearrangement would result in the formation of mainly spiro[5.6]decane and a small amount of bicyclo[5.3.0]decane and/or bicyclo[4.3.1]decane .…”

Section: Resultsmentioning

confidence: 99%

Understanding the Mechanisms of Decalin Hydroprocessing Using Comprehensive Two-Dimensional Chromatography

Blanco

Felice

Catherin

et al. 2016

Ind. Eng. Chem. Res.

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Comprehensive two-dimensional gas chromatography (GC × GC) is a powerful technique for analyzing mixtures of hundreds of hydrocarbons. In the context of fuel upgrading through selective ring opening, we propose a methodology for GC × GC analysis of complex mixtures resulting from the hydroprocessing of a single model gas oil compound, decalin, over two different types of bifunctional catalysts based on a transition-metal sulfide (NiWS on amorphous silica–alumina) or a noble metal (Ir on La,Na–Y zeolite). The reactions lead to several products families, the dominant ones being ring-opening products (ROPs) and skeletal-isomerization products (SkIPs). First, it is shown that the ROP distribution can be characterized in terms of isomerization degree by using the cumulative distribution function of the GC × GC (GC Image) software. Second, in a more quantitative approach, the products families have been subdivided into chemical groups, according to the isomerization degrees of the individual compounds, which were almost all tentatively identified by two-dimensional gas chromatography coupled with mass spectrometry (GC × GC-MS) through the use of literature data. This allows us to thoroughly analyze the influence of the catalyst nature and the presence of H2S in the reactant feed on the products distribution, and thereby gain insight into the mechanism of decalin hydroconversion over bifunctional catalysts. In particular, it is shown that metal sulfidation suppresses the metal-catalyzed C–C hydrogenolysis pathway at the benefit of undesirable acid-catalyzed isomerization steps. The methodologic work presented here for decalin is believed to be applicable to other bicyclic (naphthenic or aromatic) compounds.

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Metal Catalysed Skeletal Reactions of Hydrocarbons

Maire

Garin

1984

Advances in Comparative and Environmental Physiology

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The isomerization of isobutane and neopentane over evaporated films of platinum and palladium

Cited by 22 publications

References 0 publications

Hydrogenolysis of saturated hydrocarbons on evaporated platinum films

Hydrogenolysis of saturated hydrocarbons on evaporated platinum films

Understanding the Mechanisms of Decalin Hydroprocessing Using Comprehensive Two-Dimensional Chromatography

Metal Catalysed Skeletal Reactions of Hydrocarbons

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