5 October 2007
Mazda Motor Corporation announced a three-way catalyst developed using nanotechnology, which substantially reduces the amount of precious metals that are used, such as platinum and palladium. It is the world’s first catalyst that uses “single-nanotechnology”, according to Mazda, but no details were given if and when the new technology would be commercialized.
The new catalyst enables to reduce the amount of platinum and palladium used in automotive catalysts by 70 to 90% while maintaining the performance level and durability of conventional catalysts. By single-nanotechnology, Mazda is referring to a technique that can control even smaller particles than nanotechnology.
One of the common deterioration modes of emission control catalysts is sintering, where exposure to high exhaust temperatures causes the dispersed precious metal to agglomerate into larger particles. This reduces the catalytic surface area and the catalyst activity. To ensure adequate catalyst performance at the end of its required durability period, high loadings of precious metals are often used to counter the loss of activity of the aged catalyst.
In the new Mazda catalyst, the catalytic surface area is increased through a proprietary catalyst material structure and a very fine dispersion of precious metals, with metal particles having diameters of less than 5 nm. These nano-sized catalyst particles are fixed to the surface of the carrier material—with the base ceramic carrier particles having diameters on the order of tens of nanometers—resulting in minimal deterioration over time. For comparison, metal particles in the conventional catalyst could grow to diameters in excess of 10 nm, and the base ceramic carrier particles had diameters up to several hundreds of nanometers.