Graham, palladium

The remarkable solubility of hydrogen in palladium discovered by T. Graham following the observation of hydrogen diffusion through red-hot platinum and iron by H. St. C. Deville and L. Troost, 1863. 

The absorption of molecular hydrogen by metallic palladium has been the subject of theoretical and practical interest ever since 1866 when T. Graham reported that, on being cooled from red heat, Pd can absorb (or occlude as... 

Recently Hoover 29> compared various extrapolation methods for obtaining true solution resistances concentrated aqueous salt solutions were used for the comparisons. Two Jones-type cells were employed, one with untreated electrodes and the other with palladium-blacked electrodes. The data were fitted to three theoretical and four empirical extrapolation functions by means of computer programs. It was found that the empirical equations yielded extrapolated resistances for cells with untreated electrodes which were 0.02 to 0.15 % lower than those for palladium-blacked electrodes. Equations based on Grahame s model of a conductance cell 30-7> produced values which agreed to within 0.01 %. It was proposed that a simplified equation based on this model be used for extrapolations. Similar studies of this kind are needed for dilute nonaqueous solutions. 

Some 100 years after Cavendish s discovery of hydrogen, and only 3 years after it was realized that hydrogen sorbed from chemical or electrochemical sources causes blistering and embrittlement to steel vessels, Graham [29] observed the ability of palladium to absorb hydrogen and wrote in Philosophical Transactions of the Royal Society of London ... 

The reversible absorption was observed to proceed in presence of either metallic palladium or in palladium-silver alloys much less hydrogen was absorbed in Cu sponge (1 vol. Cu 0.6 vol. H.), and not at all in Os-Ir. The reaction of hydrogen with palladium, so being described by Graham, was ... 

Strictly speaking, we know only two real sensations the discovery (by Graham in 1863) of the hydrogen uptake by palladium with PdH0.6 formation and the practically occasional discovery of the reversible absorption of hydrogen at moderate conditions by some alloys and intermetallic compounds (IMCs) (Neumann Zijlsta Westendorp Wiswall Reilly). 

Graham,3 on the other hand, considered it probable that the hydrogen enters palladium in the physical condition of liquid. ... 

Spongy Palladium is readily obtained by heating ammonium chlor-palladite, (NH4)2PdCl4, in hydrogen. It is then in a particularly suitable condition for exhibiting catalytic activity. Graham 2 prepared it by ignition of the cyanide, and Berry 8 by reduction of the chloride with sodium formate in hot aqueous solution. 

Graham also found palladium sponge to exhibit a selective absorption for alcohol in preference to water, a power not manifested either by platinum sponge or by spongy iron. For example, palladium sponge was left in contact with a mixture of alcohol and water in a sealed tube for two days. At the expiration of this time the supernatant liquid was removed and found to contain less alcohol, whilst the portion retained by the palladium contained more alcohol in proportion than the original mixture. 

The use of palladium-based membranes results from the 1866 discovery by Thomas Graham(2) that metallic palladium absorbs an unusually lar e amount of hydrogen. Hydrogen permeates through Pd-based membranes in the form of highly active atomic hydrogen which can react with other... 

Metal membranes. Since Thomas Graham [1866] discovered that metallic palladium absorbs a large amount of hydrogen, the metal hydride system of which palla um is an important example has been extensively studied. Hydrogen dissolved in a metal hydride system (according to the mechanism to be describ below) is considered to behave in an atomic or ionic form which is more reactive than molecular hydrogen in a gas phase. 

N. Bartlett, B. Zemva and L. Graham, Redox Reactions in the XeF2/Platinum Fluoride and XeF2/Palladium Fluoride Systems and the Conversion of XeF2 to XeF4 and Xe, J. Fluorine Chem. 7 (1976) 301-320. 

The first step in the application of nonporous metal membranes was made by T. Graham [15], who discovered palladium permeability for hydrogen only. He mentioned that... 

The discovery of hydrogen selective diffusion through a palladium membrane by Sir Thomas Graham in 1866 and its subsequent development, a palladium-hydrogen system, have been extensively investigated (Lewis, 1967). A self-sustained palladium dense metal membrane tube with thickness... 

The first report on the reaction of hydrogen with a metal dates from 1866, when Graham observed the absorption of hydrogen by palladium up to 935 times its own volume. 

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