|Mazda’s new catalyst structure. Click to enlarge.
Mazda Motor Corporation will introduce the new Mazda3 (known as Mazda Axela in Japan) 5-door hatchback at the Bologna Motor Show on 3 December. The introduction of the second generation Mazda3 5-door hatchback follows on the unveiling of the 4-door sedan version last week at the Los Angeles Auto Show.
The gasoline-powered versions of the Mazda3 feature the first vehicle catalyst constructed with Mazda’s new catalyst structure for automotive exhaust systems that substantially reduces the amount of precious metals such as platinum and palladium that are required. (Earlier post.)
The standard three-way catalyst (TWC) device for emissions treatment consists of a mixture of platinum (Pt), rhodium (Rh) and palladium (Pd). Catalytic activity of the noble metals is roughly proportional to their exposed surface area. To obtain the greatest extent of catalytic activity from a small amount of noble metal, manufacturers fabricate particles that are small in size, with a high specific surface area.
However, exposure to exhaust gas heat causes the precious metal to agglomerate into larger particles. This reduces the catalyst’s effective surface area and catalytic activity, which requires the use of a significant amount of precious metals to counter and maintain an efficient purification performance.
To address the problem, Mazda developed a catalyst material structure featuring features single, nanosized precious metal particles embedded in fixed positions. As a result, there is no agglomeration of the precious metal particles, and the amount of high-priced precious metals used in three-way catalytic converters can be reduced by 70-90%, according to Mazda.
Similarly, Nissan just released its new Cube featuring a new ultra-low precious metal catalyst. (Earlier post.) With Nissan’s technology, the precious metal attached to the substrates are separated by a “wall material” which prevents clustering of the precious metals, leading to improved cleaning efficiency. Nissan says its new under-floor TWC to be introduced in the next generation Cube uses half the amount of precious metals, from 1.3 grams down to .65 gram.
Mazda3 engines. The engine lineup for the Mazda3 hatchback has been tailored for European customers and now includes the newly developed 2.2-liter turbo diesel engine, just launched in the Mazda6, in addition to the existing 1.6-liter and 2.0-liter gasoline engines and the 1.6-liter turbo diesel.
The new 2.2-liter turbo diesel will be offered in two variants, a high power version with a maximum output of 136 kW (182 hp), and a standard power version with a maximum output of 100 kW (148 hp). Both comply with Euro5 regulations. Fuel economy and CO2 emissions are also improved compared to the current 2.0-liter version.
For the North American version introduced at the Los Angeles Auto Show, Mazda is offering two gasoline engines: the MZR 2.0-liter four-in-line engine (110 kW / 148 hp and 183 Nm / 135 lb-ft) and the new MZR 2.5-liter four-cylinder engine borrowed from the 2009 Mazda6 (125 kW / 167 hp and 228 Nm / 168 lb-ft).