Depleted uranium (DU) is a radioactive by-product from the production of nuclear energy. Most uranium in the crust of the earth is isotope U-238 which is mildly radioactive. About three quarters of one percent of natural uranium is U-235 which is highly radioactive. In order to fuel conventional nuclear power reactors, uranium ore is refined to increase the percent of U-235 to from three to five percent. This product is called low enriched uranium. The DU left over from the enrichment process is about three tenths of one percent U-235.
Civilian use of DU includes counterweights in aircraft, radiation shielding for medical radiation therapy and industrial radiography equipment, and containers that are used to transport radioactive materials. The military uses of DU include armor-plating on vehicles and armor piercing projectiles. Professor Geoff Cloke, Professor Richard Layfield and Dr. Nikolaos Tsoureas all work at the University of Sussex in the U.K. They have just published a paper in the Journal of the American Chemical Society that suggests that DU could also be used as an important chemical catalyst.
Ethylene is a gaseous organic compound with the chemical formula of C2H4. Ethylene contains a carbon to carbon double bond. It is widely used in industry and is the most produced organic compound in the world. One of the major uses for ethylene is in the production of plastic.
Ethane is a gaseous organic compound with the chemical formula of C2H6. It is a component of natural gas. It can be used as a ripening agent for foods, a refrigerant, a substance that can be used in the production of welding gas. It can also be used to make ethylene.
The scientists from the University of Sussex have discovered that a catalyst that contains DU can be used to convert ethylene into ethane. This work indicates that the large-scale storage of DU can be reduced and the synthesis of complex alkenes facilitated.
Prof Layfield said, “The ability to convert alkenes into alkanes is an important chemical reaction that means we may be able to take simple molecules and upgrade them into valuable commodity chemicals, like hydrogenated oils and petrochemicals which can be used as an energy source. The fact that we can use depleted uranium to do this provides proof that we don't need to be afraid of it as it might actually be very useful for us.”
The team from the University of Sussex collaborated with researchers from the Université de Toulouse and Humboldt-Universität zu Berlin. They discovered that an organometallic molecule based on DU could be used as a catalyst to add a hydrogen molecule to the carbon-carbon double bond in ethylene to create ethane, the simplest of the family of alkenes.
Prof. Cloke said, "Nobody has thought to use DU in this way before. While converting ethylene into ethane is nothing new, the use or uranium is a key milestone. The key to the reactivity were two fused pentagonal rings of carbon, known as pentalene, which help the uranium to inject electrons into ethylene and activate it towards addition of hydrogen.”