|Nissan’s new material halves the use of precious metals. Click to enlarge.|
Nissan Motor Co., Ltd. has developed a new catalyst for gasoline-powered cars that utilizes only half the precious metal components compared to conventional catalysts currently available. Nissan will introduce the new catalyst in future products starting in fiscal 2008.
This technology, developed as part of the Renault-Nissan Alliance, results in no changes in the performance of the catalyst despite using significantly less precious metal.
The standard three-way catalyst (TWC) device for emissions treatment consists of a mixture of platinum (Pt), rhodium (Rh) and palladium (Pd). Within the catalyst, the chemical reaction between the precious metals and exhaust gases contributes to the conversion of nitrogen oxides (NOx), carbon monoxide (CO) and hydrocarbons (HC) into non-toxic compounds such as nitrogen (N2), water (H20), and carbon dioxide (CO2).
In conventional catalysts, the high temperatures within the catalyst causes the precious metals to cluster, thereby reducing the exposed metal surface area, and leading to less-effective aftertreatment of the exhaust. To compensate for this thermal degradation, existing TWCs contain a higher amount of precious metals in order to maintain an efficient level of cleaning.
Nissan has succeeded in developing a material that keeps the fine metal particles separated to prevent them from clustering under high-temperature conditions. This enables the catalyst to maintain performance while utilizing only half the amount of precious metals.