Editor’s Note: This is Part 6 of a 6-Part Series on PGMs that has run on Tuesdays.
The platinum group metals (PGMs) — platinum, palladium, rhodium, iridium, ruthenium and osmium — are a family of structurally and chemically similar elements that are most valued for their wide range of industrial, medical, and electronic applications. In this our final installment about the platinum group metals (PGMs), we’ll discuss current and emerging applications in making transportation and power generation cleaner and more energy efficient using PGMs.
Platinum catalysts play a critical role in extracting gasoline from crude oil. Platinum catalysts are used in a process is called catalytic reforming, which creates high-octane gasoline for cars. Palladium and other PGMs are used in hydroprocessing, which improves the quality of oil and gas products by adding hydrogen atoms to molecules without breaking them.
Palladium is also used in hydrocracking, a process which upgrades low-quality heavy gas oils into high-quality, clean-burning jet fuel, diesel, and gasoline. Hydrocrackers are also able to convert high-sulfur materials into low-sulfur fuels for vehicles and airplanes. Hydrocracking is not yet widespread, but as worldwide demand for low-sulfur materials and middle distillates such as jet fuel, kerosene, and diesel increases, more refiners are likely to adapt this process.
Fuel cells are electrochemical devices that convert the energy of a chemical reaction directly into electricity, with heat and water as by-products. Platinum and ruthenium are necessary ingredients in this technology as is palladium, which is used to generate the ultra pure hydrogen fuel cells need to operate effectively.
Fuel cells are commonly associated with automobiles but have other power-generating applications. Fuel Cell Today defines fuel cells for transport as any units that provide propulsive power to a vehicle, directly or indirectly (i.e. as range extenders). This includes forklift trucks and airport baggage trucks, two- and three-wheeler vehicles such as scooters, light duty vehicles (LDVs), such as cars and vans, buses and trucks, trains, ferries, manned light aircraft, unmanned aerial vehicles (UAVs) and unmanned undersea vehicles (UUVs). Most major automakers have targeted 2015 for initial commercial sales of fuel cell LDVs.
Fuel cell systems for stationary power generation have been installed in commercial buildings and soon may be available for residential use. Fuel cells are well suited for combined heat and power (CHP), uninterruptible power systems (UPS) and primary power units. Fuel cells are also being tested for use at landfill and wastewater treatment plants.
The PGMs are best known as an essential component in catalytic converters, air pollution control devices that have revolutionized the automotive industry. Catalytic converters are formed of ceramic or metal and coated with chemicals and a combination of platinum, rhodium and/or palladium. The PGMs are responsible for the conversion reactions that turn pollutants into harmless gases.
According to the International Platinum Group Metals Association (IPA), catalytic converters, or autocatalysts, accounted for 51% of total world demand for PGMs in 2010. The IPA site also reports that more than 98% of new cars sold worldwide each year are now fitted with these devices, which convert over 90% of harmful polluting gases into less harmful carbon dioxide (CO2) and water vapor.
Catalytic converters are a valuable recycling target because they contain three PGMs. Most recycled catalytic converters in the U.S. contain recoverable amounts of PGMs ranging from 1-2 grams for a small car to 12-15 grams for a big truck. The value of the recovered PGMs ranges from $25 to a few hundred dollars per vehicle. In 2010, the total value of platinum, palladium, and rhodium reclaimed from the recycling of spent catalytic converters was $3 billion.
The trade of ground-up material sold as catalysts can be very dangerous because it may be contaminated with lead or spent nickel-cadmium batteries. To avoid considerable financial losses, companies need to quickly and accurately determine the contents of PGMs in spent catalytic converters at the collector’s site or in the refineries. X-ray fluorescence is a reliable technology to test the composition and quality of the recycled metals.
This concludes our Platinum Group Metals series. If you want more information on other groups of metals, let us know below in the comment section.