Nissan Develops New Catalyst Material with Half the Precious Metal Components
27 July 2007
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| 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.
Good news, these precious metals are scarce and hence expensive. They are recycled, but with car ownership in China, Eastern Europe & Russia and India all booming, this sharply reduced the need for primary precious metals in three-way catalysts.
Note that the NOx-store catalysts used for some diesel and stratified GDI engines contain several times as much of these metals as regular three-way catalysts do. This is one reason why they are so much more expensive, pricing these fuel-saving engine strategies out of the lower end of the market.
Posted by: Rafael Seidl | 27 July 2007 at 07:43 AM
It would be nice if they could reduce the price to the point where we will see more catalytic converters on motorcycles.
Posted by: Neil | 27 July 2007 at 10:46 AM
@Neil -
afaik, virtually all motorcycles sold in the US, Europe and Japan have four-stroke spark ignition engines and three-way catalysts. The emissions standards are not as severe as they are for cars, though I suspect there is a technical reason for that. Emissions regulators probably don't have a soft spot for motorbikes and within reason, they have never allowed cost as an argument for using anything other than the best available technology to clean up the air.
Posted by: Rafael Seidl | 27 July 2007 at 04:31 PM