Platinum Metals Review - Volume 39, Issue 1, 1995

Recent concerns over the health effects of particulate emissions from vehicles have focused on diesel engines. While European legislation to limit their emissions is now in place it is expected that future legislation will be more demanding. Using a platinum catalyst it has been possible to demonstrate in various trials the practical application of a novel system for the removal of both the soot and hydrocarbon components from diesel powered vehicle exhaust. The background to the development of this successful technology is described here.

Photodynamic therapy is a clinical technique employing the combination of light, oxygen and a sensitising compound to induce the photochemical destruction of unwanted tissue. Light therapy has been known for some time, but it was not until the earlier part of this century that the first clinical work was performed using sensitisers and light. More recently a sensitising compound of a complex mixture of porphyrins has been tested on various cancers, and been awarded regulatory approval for its use. In this paper the synthesis and properties of some novel and easily prepared water soluble ruthenium phthalocyanine complexes are reported. One of these complexes, JM 2929, has been extensively studied and has photosensitising properties which when used in combination with light and oxygen in vitro and in vivo during photodynamic therapy displays remarkable cytotoxic effects.

The changes of topography and structure in palladium-5 per cent nickel alloy catchment gauzes, which are used to capture the platinum lost from the catalyst gauzes employed in the ammonia oxidation reaction to produce nitric acid, have been studied by scanning electron microscopy, electron probe microarea analysis, X-ray diffraction and other techniques. The structure of the palladium-5per cent nickel alloy gauze is reconstructed by recrystallisation and this is controlled by vapour deposition (adsorption) and diffusion re-alloying. The initial solid solution of palladium (nickel) changed into palladium (platinum) solid solution, the nickel being gradually oxidised to nickel oxide until no nickel remained. The lattice constants of the palladium (platinum) solid solution increased with the ratio of platinum:palladium. Ladder-like (layered) growth was a main mechanism in the formation of new lattice planes and crystals, while screw-type growth played an important role in the formation of new crystals.