Platinum Metals Review - Volume 36, Issue 1, 1992

Regulations to control the exhaust emissions from motor vehicles are being adopted by more and more countries around the world, and in future more stringent regulations will be introduced, particularly in the U.S.A. and Europe. This, together with the need to show good pollution control under real-world driving conditions, has led to the widespread introduction of closed-loop, three-way catalysts based on the use of platinum group metal technology. The increasing concern about emissions of carbon dioxide, as well as the three traditional pollutants, offers an opportunity for catalyst technology to control nitrogen oxides from both fuel efficient lean burn petrol engines and from diesel engines, thus complementing the use of platinum group metals catalysts to control nitrogen oxides and other emissions. This paper reviews the development of “lean-NOx” technology based on the use of zeolite supported catalysts; it highlights the promise shown and the shortcomings still to be overcome.

In order to ensure the high quality necessary for use in scientific instruments, most high-technology optical glasses are melted in platinum containers. In general, this noble metal has excellent corrosion and erosion resistance, as well as low solubility, when in contact with molten glass. Therefore the dangers of discoloration and reduction in optical transmission are low. Glass melts may be contaminated by the uptake of corrosion and erosion products if the glass is melted in ceramic materials. The use of platinum, instead of ceramics, for both containers and stirrers enables glass melts to be stirred more thoroughly and hence become more homogeneous. In this way a better quality and higher yields of glass are obtained. Even totally new glass systems which have superior optical properties, but which would attack ceramics very quickly, can be melted in platinum vessels and produced to extremely high quality. Generally, platinum or its alloys enables optical glass to be produced with high purity, homogeneity and the absence of streaks and bubbles.

Platinum group organometallics have recently been the subject of intensive investigation designed to establish the basic characteristics of their decomposition, which results in the formation of metallic or metalcontaining coatings. This review has been compiled from a literature search and indicates some of the applications that are, or could be, of commercial significance.

It is generally accepted that the first description of “platina” to appear in Europe was by a young Spanish naval officer, Antonio de Ulloa, whose famous work “Relación del Viaje a la América Meridional” was published in 1748. Important though this was, of even greater significance was the fact that the primary metallurgy of platinum must have been established much earlier, enabling it to be extracted, purified and manufactured. These processes appear to have been kept secret from other European countries, and until recently their details had not been deduced. Now manuscripts discovered in the Colombian Archives enable known methods of purification to be linked to the description of the primitive manufacturing process.