Platinum Metals Review - Volume 30, Issue 2, 1986

The surface reconstruction on rhodium-platinum catalyst gauzes has been examined using scanning electron microscope techniques. The nucleation and growth of the large cage-like features which develop on the gauze surfaces during operation in the ammonia oxidation process have been studied in detail. It is concluded that a vapour phase mechanism involving transport of platinum oxide is responsible for the observed reaction, and the reason why this process operates only over a limited range of temperature and pressure is explained. Some comments are also made on the related reconstruction observed on gauzes used during the production of hydrogen cyanide by the Andrussow process.

The development of platinum coated refractory metal anodes for impressed current corrosion protection will be recorded in the history of technology as an event of extreme importance. The progress recently made in electronics technology has enabled further new developments in corrosion protection, leading now to miniaturised systems.

The catalytic properties of selected palladium binary alloy membranes have been studied during hydrogenation and dehydrogenation reactions. When hydrogen, from a variety of hydrogen-rich sources, is introduced through such membrane catalysts the yield and selectivity of hydrogenation products may be increased, the energy requirement reduced and finite natural resources conserved.

The anodic dissolution of palladium in deoxygenated acidic chloride solutions has been studied and the reaction order determined. A mechanism which is consistent with the empirical rate expression was developed, and is reported.

The properties of platinum make it very suitable for many exacting applications where absolute consistency must be maintained in fluctuating conditions over long periods of time. One of the earliest uses of platinum and its alloys was for the manufacture of standard weights and measures, while the platinum resistance thermometer is still used to fix a wide range of temperatures on the International Practical Temperature Scale. Additionally, for a long period platinum contributed to the definition of the candela, the international unit of luminous intensity. This article gives a brief account of some of the pioneering work carried out by people seeking to establish a primary standard of light by utilising the unique properties of platinum.