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Decker, Sébastien; Frennet, Alfred

doi:10.1023/a:1019006215844

Cited by 3 publications

(2 citation statements)

References 14 publications

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“…223 Very similar heats were recorded 222 for palladium powder and for palladium on various supports (∼63 kJ mol −1 ), but this value rose sharply to ∼100 kJ mol −1 when the particle size fell below 3 nm; at this point the heat of formation of the hydride phase (∼36 kJ mol −1 ) also increased. For Pd/Al 2 O 3 , it was higher at 97% dispersion than at 26% dispersion 140 (125 compared to 110 kJ mol −1 ), in qualitative agreement with the previous study.…”

Section: Characterisation Of Chemisorbed Hydrogensupporting

confidence: 53%

“…Indeed it is stated that this information can all be extracted by analysis of the adsorption isochore. 223 Calorimetry provides either an integral value, i.e., the average value to saturation or whatever coverage is reached, or a differential value, obtained by sensing the heat released as small doses are admitted: the latter procedure permits extrapolation to zero coverage and may also reveal steps and plateaux indicative of different states of adsorption. 224 Care is however necessary to ensure uniform distribution of the gas through the catalyst sample and this may not be achieved at low temperature.…”

Section: Characterisation Of Chemisorbed Hydrogenmentioning

confidence: 99%

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Chemisorption and Reactions of Hydrogen

Metal-Catalysed Reactions of Hydrocarbons

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PREFACEThe hydrogen molecule is dissociatively chemisorbed with great facility by a number of metals within the Transition Series: elsewhere the process is more highly activated, but chemisorbed atoms once formed are stable. The contrast between hydrogen and the alkanes is very striking: the σ H H bond can sometimes be broken at temperatures close to 20 K, the activation energy being minimal, whereas with methane each σ C H bond is effectively shielded by the other hydrogen atoms, so that much higher temperatures are needed for its chemisorption by dissociation.The strengths of hydrogen-metal bonds at the surfaces of metals of Groups 8 to 10 are of similar order, but they tend to increase on moving towards the centre of each Transition Series. These trends are shown more distinctly by other molecules such as oxygen and nitrogen, where a clear parallelism with analogous bulk compounds is shown: but within the Transition Series stoichiometric hydrides are formed only by metals of Groups 3, 4 and 5. Because of commercial interest and experimental convenience, certain metals have commanded disproportionate attention: tungsten, platinum and nickel in the massive form and platinum also in the microscopic form. For these same reasons, other metals have escaped attention almost entirely (e.g. manganese and osmium).All the catalysed reactions to be considered in the following chapters involve hydrogen (or deuterium) as reactant or product, and a knowledge of its chemisorption, and of reaction between its isotopic and spin variants, will prove helpful in understanding its reaction with hydrocarbons. For this reason most emphasis will be placed on the interaction of hydrogen with metals of Groups 8 to 10.While the utility of hydrogen in catalysed reactions is due in part to its small size and easy migration, these features add greatly to the difficulty of describing 93 94 CHAPTER 3

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Section: Characterisation Of Chemisorbed Hydrogensupporting

confidence: 53%

Section: Characterisation Of Chemisorbed Hydrogenmentioning

confidence: 99%

Chemisorption and Reactions of Hydrogen

Metal-Catalysed Reactions of Hydrocarbons

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Kinetic Evaluation of the Set of Reactions in the Selective Hydrogenation of 1-Butyne and 1,3-Butadiene in Presence of n-Butenes

Alves

Bressa

Martı́nez

et al. 2013

Ind. Eng. Chem. Res.

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The selective hydrogenation in the liquid phase of 1-butyne and 1,3-butadiene in the presence of n-butenes over a commercial Pd/Al2O3 egg-shell catalyst has been studied. Although hydrogenation of the n-butenes and their isomerization are normally undesirable, kinetics of these reactions should also be evaluated in order to carry out the process at efficient operating conditions. Here, the effect of temperature, in the range 25–65 °C, on the specific rate coefficients of 1,3-butadiene hydrogenation reactions and 1-butene, cis-2-butene, and trans-2-butene hydrogenation and isomerization reactions was evaluated from measurements in a batch reactor system. Further experiments were conducted for the evaluation of selectivity between 1-butyne and 1,3-butadiene hydrogenations at 44 °C. The present results and previous kinetic characterization allow evaluating the most relevant parameters of a set of kinetic expressions for the 10 overall reactions that govern the system transformation.

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The effect of substrate nature on the acid-base and adsorption characteristics of active surface sites of supported palladium catalysts

Efremov

Филиппов

2014

Prot Met Phys Chem Surf

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Cited by 3 publications

References 14 publications

Chemisorption and Reactions of Hydrogen

Chemisorption and Reactions of Hydrogen

Kinetic Evaluation of the Set of Reactions in the Selective Hydrogenation of 1-Butyne and 1,3-Butadiene in Presence of n-Butenes

The effect of substrate nature on the acid-base and adsorption characteristics of active surface sites of supported palladium catalysts

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