 |
|
|
|
|
|
 |
 |
 |
 |
 |
|
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
Commodity
Description/Technical Characteristics
Origin and history
Palladium is a very rare precious metal. In nature it is generally found as part of the so-called Platinum Group Metals (PGMs) and together with other metals such as gold, nickel or copper. The PGMs are Platinum (Pt), Palladium (Pd), Rhodium (Rh), Ruthenium (Ru), Iridium (Ir) and Osmium (Os). They are classified under one heading due to their similar chemical and physical properties and because they are often found together. PGM are called also the noble metals as a result of their superior ability to withstand oxidation and corrosion. Platinum and palladium are the major metals of the Platinum Group. Although palladium is mined with platinum and is similar to it in many aspects, there are important differences between the two metals.
Palladium is a scarce and costly metal and, as the other PGMs, it shows unusual properties. The specific chemical and physical properties of this metal are of essential use for a number of different industrial applications. Like platinum, palladium is widely used in "green" applications, particularly in catalysts for the automobile industry. However, its market is very tiny and prices are extremely volatile.
Description/Technical Characteristics
Palladium is the least dense and lowest melting of the Platinum Group Metals. It is a silver-white metal and does not tarnish in air. When annealed, it is soft and ductile. Cold working greatly increases its strength and hardness. It resists high temperature corrosion and oxidation but it is attacked by nitric and sulfuric acid. Palladium has been named the "amazing soaking sponge" because at room temperature it has the unusual property of absorbing up to 900 times its own volume of hydrogen. Hydrogen readily diffuses through heated palladium and this provides a means of purifying the gas. Finely divided it is a good catalyst and is used for hydrogenation and dehydrogenation reactions.
|
Palladium |
Pd |
The origin and history of palladium are closely linked to those of platinum and the rest of the PGMs. Although PGMs are regarded as a "new" metals in their present form, they have a long history. Ancient Egyptians and Pre-Columbian Indian civilizations already valued PGMs alloys as very important elements. The "modern" discovery of these metals is attributed to Spanish conquerors in the 17th century. Actually the name platinum was given by the Spanish word, platina, meaning little silver. Spaniards had discovered alluvial deposits of the rare white metal when they were mining gold in the Choco region in Colombia. Paradoxically, they considered it as a nuisance for mining gold.
W. H. Wollaston, a British chemist, discovered palladium in 1803. It was named after the asteroid "Pallas" which was discovered at about the same time and from the Greek name "Pallas", goddess of wisdom. The techniques used by Wollaston in the separation of PGMs are considered to be the basis for modern PGMs metallurgy.
The production of PGMs requires very complex processing techniques that were not available until the end of the 19th century. Moreover, the high melting points of PGMs were an additional obstacle to work with them. It was only with the development of new refining techniques that these metals were more widely used for new industrial applications.
The importance of palladium, based on its catalytic properties, increased considerably since the 1970s when demand for autocatalysts grew, thanks to the introduction of automotive emission standards in the developed countries. However, during the nineties, use of palladium in autocatalyst soared, since it replaced more expensive and less efficient platinum and emission standards tightened all over the world. Due to the remarkable increase in palladium prices in the late nineties and 2000, preference for palladium in autocatalysts is being reversed.
One of the most important obstacles for a more widespread use of palladium in its history has been its limited supply. At present time, production of palladium is concentrated in a few areas in the world, mainly in the Russian Federation and South Africa. This concentration of production fills the market with uncertainties concerning prices and availability of supply.
