Platinum Metals Review - Volume 35, Issue 3, 1991

A metal catalysed, electrophilic approach to methane oxidation is discussed. This involves the oxidation of methane to the corresponding methyl ester in trifluoroacetic acid; the oxidant is hydrogen peroxide and the catalyst is the palladium(II) ion. The latter species activates methane by the electrophilic cleavage of a C-H bond, and then acts as a two-electron oxidant towards the resultant metal-bound methyl group. The hydrogen peroxide reoxidises palladium(0) back to palladium(II)

The first international conference dedicated entirely to magneto-optic recording, MORIS’91, Magneto-Optic Recording International Symposium, was held in Tokyo, Japan, from 16th to 19th April 1991. The scope of the conference covered a broad range of topics, including current and potential magneto-optic materials, their processing and properties, and the physics and technology of magneto-optic recording. Rare earth alloys are currently used as first generation magneto-optic materials, but platinum/cobalt and palladium/cobalt multilayered thin films show great promise for future use as second generation media. A selection of the papers presented are reviewed here.

The hydrogen content gradients that occur during hydrogen permeation through palladium-silver membranes produce complementary strain gradients of lattice expansion, which induce opposing Gorsky Effect components of Diffusion Flux. A body of observations of related “uphill effects” and allied diffusion phenomena have recently been studied, using sheet and tube membranes; these phenomena have been correlated with hydrogen pressure-hydrogen content relationships of the Pd77Ag23Hn system.

The recent surge of interest in palladium, an element whose history has not been afforded the same coverage in this Journal as that given to platinum, has prompted this account of the discovery and preliminary investigation of this important member of the platinum group of metals. The first written reports about palladium resulted in controversy, confusion and embarrassment; its inclusion in jewellery in the early twentieth century, and more especially some recent claims concerning palladium electrodes, had similar effects. A number of the people who contributed in various ways to the introduction of this metal to the scientific community in the early nineteenth century are also considered, briefly.