Cerium – Rare Earth Element
A Reactive Metal that can Help Reduce Particulate Pollution
The chemistry and uses of an unknown element with a bright future!
Cerium is a little known element, at the moment. It has the potential to become a widely used and important product in the very near future. It may prove to be a real money spinner for the nations where its ores are found: China, USA, India, Brazil and Australia. This is mainly because it can be used to reduce particulate emissions from diesel combustion engines, produces a safe red dye which can be used in paints, and is a constituent of several electrical applications.
Not So Rare
Cerium is called a rare earth metal, but it is more abundant on the earth than copper and lead. It is found in the group on the periodic table called the Lanthanides, the first row of f-block elements, below the transition metals. It is in this group because of its electronic structure. Its atomic number is 58, meaning it has 58 protons in its nucleus and 58 electrons surrounding the nucleus in different energy levels. The two outermost electrons are in the first f-shell energy level, and these are the electrons which determine many of its properties.
Discovery
The element was first discovered in 1803 by Swedish scientists Von Hisinger and Berzelius. They named it after an asteroid Ceres which had been discovered in 1801. As an element, cerium does not have any uses. This is because it tarnishes easily, is very reactive with water and will ignite if scratched by a knife. Its compounds, however, are very useful.
Red Paint
Cerium sulfide has a rich red colour and is stable up to 350 Celsius. It is also non-toxic, which makes it much better than other compounds currently used in red paints like cadmium, lead and mercury. It can also be mixed with other rare earth metals to make different shades of red, some of which have not been available before.
Reducing Particulates
Another important compound of cerium is its oxide. When a little cerium oxide is added to diesel fuel, it catalyses the burning up of carbon particulates. This is a serious problem in many countries, especially in continental Europe where many cars as well as buses, vans, taxis and lorries run on diesel fuel. A diesel car releases 330mg of particulates for every mile it travels, compared to 25mg in a petrol car. These particulates have been cited as the cause for the upsurge in respiratory diseases such as asthma and bronchitis. Reducing the release of particulates is an important breakthrough for those affected.
Important Element
When applications such as flat-screen TVs, low energy light bulbs and compact discs are added to the list of uses of cerium compounds, it becomes obvious just how important this element is becoming.
