Honda Motor Co., Ltd., announced today it has developed a next-generation diesel engine that reduces exhaust gas emissions to a level equal to a petrol engine. Honda¡¯s next-generation diesel engine employs a NOx catalytic converter that Honda calculates will enable sufficent reduction in NOx emissions to meet U.S. Tier II Bin 5 emissions requirements) when the new engine is launched in three years¡¯ time. The catalytic converter features the world¡¯s first system using the reductive reaction of ammonia generated within the catalytic converter to ¡°detoxify¡± nitrogen oxide (NOx) by turning it into nitrogen (N2).

The new catalytic converter has a two-layer structure: one layer adsorbs NOx from the exhaust gas and converts a portion of it into ammonia, while the other layer adsorbs the resulting ammonia, and uses it later in a reaction that converts the remaining NOx in the exhaust into nitrogen (N2). Ammonia is a highly effective reagent for reducing NOx into N2 in an oxygen-rich, lean-burn atmosphere, but in other manufacturers¡¯ NOx exhaust aftertreatment systems, is injected from an ¡®Adblue¡¯ storage tank, as in Mercedes-Benz¡¯ new Bluetec diesel for the US market. This ability to generate and store ammonia within the catalytic converter has enabled Honda to create a compact, lightweight NOx reduction system. The system also features enhanced NOx reduction performance at 200¨C300oC, the main temperature range of diesel engines.

Honda designed the catalytic converter for use with its 2.2 i-CTDi diesel engine, introduced in 2003 on the European Accord model. With the new system announced today, the 2.2 i-CTDi delivers cleaner exhaust to the NOx catalytic converter, by optimizing the combustion chamber configuration, reducing fuel injection time with a 2,000-bar common rail injection system and boosting the efficiency of the EGR (exhaust gas recirculation) system, and has reduced the amount of NOx and soot while increasing power output.

Honda also plans to address other technical challenges in developing clean diesel engines, such as handling diesel fuels with different cetane numbers and meeting U.S. On-Board Diagnostic System requirements. Honda plans to introduce its next-generation diesel engine in the US within three years.

Petrol engines presently employ three-way catalytic converters that offer NOx reduction rates as high as 99%, but this performance is possible only at the stoichiometric air-fuel ratio. In the oxygen-rich environment of a lean-burn diesel engine, three-way catalytic converters only reduce NOx levels by approximately 10%. Honda¡¯s new catalytic converter efficiently reduces NOx in a lean-burn atmosphere, enabling diesel engines to rival petrol engines' emissions performance.