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NOx Adsorbers

18 October 2003

Starting in November 2003, Toyota will offer in the European market its Avensis model equipped with the D-CAT (Diesel Clean Advanced Technology) emission control system. The D-CAT package includes the DPNR (Diesel PM and NOx Reduction) system, which is a combination of a diesel particulate filter with a NOx adsorber-catalyst. The launch of Avensis 2.0 D-CAT marks the first commercial introduction of this type of diesel emission control system. The D-CAT version will be initially available only in the UK and Germany, due to the availability of ultra low sulfur diesel fuel in those markets.

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When equipped with the D-CAT, the Toyota Avensis will be the cleanest diesel car in the world in regards to both NOx and PM emissions. With PM at 0.002 g/km and NOx at 0.12 g/km—90% and 50%, respectively, below the Euro 4 standard—the Avensis beats any other diesel car on the market, including those fitted with particulate filters, according to Toyota.

For comparison, the D-CAT’s NOx emissions would place it in the US Tier 2 Bin 8, while the PM would be in Tier 2 Bin 1. This comparison has limited validity, as the test cycles in Europe and in the United States are different. Nevertheless, the Avensis D-CAT could be also perceived as an important step proving the technical viability of diesels in the future US light-duty market.

The Avensis 2.0 D-CAT is based on the 2.0 D-4D model, introduced in March 2003. To accommodate the D-CAT package, Toyota had to add or modify 30 major components in the D-4D engine, including the cylinder head, common rail system, exhaust manifold and turbocharger. The performance of both cars is the same, with 2 liter, 115 hp engine, 0-100 km/h in 11.2 seconds, and 180 km/h maximum speed. Both the D-4D and the D-CAT are also Euro 4 compliant (and so, at this time there is no additional tax benefit for purchasing the D-CAT version).

The D-CAT package features close integration of the DPNR unit with the engine, through a number of major components and strategies (see the NOx Adsorbers paper for more details):

  • The DPNR particulate filter/NOx adsorber-catalyst unit
  • New common-rail fuel injection system
  • Exhaust port fuel injection
  • Low temperature combustion (LTC)
  • Exhaust gas recirculation (EGR)

Toyota Avensis is also available with a number of gasoline engines: 1.6-liter, 1.8-liter, 2.0-liter direct injection, and 2.4-liter direct injection with a 5-speed automatic transmission. Only the 2.0-liter direct injection gasoline version is available in Japan. The Avensis has been developed in Europe and is manufactured, including the Japanese market version, in Burnaston, UK.

In parallel to the Avensis, Toyota will introduce the DPNR system on a light-duty Hino Dutro hybrid truck in the Japanese market. The launch of DPNR-equipped Dutro is also expected this Fall. Hino is a part of the Toyota group.

Source: Toyota