Did You Know – rare earths in catalytic converters improve their effectiveness
An automotive catalytic converter (autocat) transforms the primary pollutants in engine exhaust gases into non-toxic compounds. It is called a 3-way catalyst because it achieves three different chemical reactions:
- Oxidizing carbon monoxide into non-harmful carbon dioxide
- Oxidizing complex unburned hydrocarbonates into carbon dioxide and water
- Converting oxides of nitrogen (NOx) with carbon monoxide into harmless nitrogen and carbon dioxide.
|Rare Earth Oxide||Atomic Formula|
|Main Rare Earths used in this application|
|Rare Earths that may be added in smaller quantities|
The 3-way catalyst consists of a mixture of precious metals, zirconium and rare earth (mostly cerium) wash coated into a brick inserted in the vehicle’s exhaust pipe.
This market segment has been growing steadily above 5% per annum in the past 10 years and is expected to continue to grow as emission control regulations around the world are strengthened.
Additional catalytic systems are being developed, especially for addressing the higher oxides of nitrogen (NOx) emissions by diesel cars (linked to their higher combustion temperature). One of the most promising technologies (called Lean Nox Trap) uses cerium as a major catalyst and is particularly suitable for compact diesel cars.