BlueTec

BlueTec is Daimler-Benz's name for its two nitrogen oxide (NOx) reducing systems, for use in their Diesel automobile engines. One is a urea catalyst called AdBlue, the other is called DeNOx and uses an oxidising catalytic converter and particulate filter combined with other NOx reducing systems. Both systems were designed to slash emissions further than ever before. Mercedes-Benz introduced the systems in the E-Class (using the 'DeNOx' system) and GL-Class (using 'AdBlue') at the 2006 North American International Auto Show as the E 320 and GL 320 Bluetec. This system makes these vehicles 45-state and 50-state legal respectively in the United States, and is expected to meet all emissions regulations through 2009. DaimlerChrysler has entered into agreement with Volkswagen, Audi and BMW to share BlueTec technology with them. Together they try to push diesel technology to the masses in the United States.

The BlueTec was on the Ward's 10 Best Engines list for 2007.

A Jeep Grand Cherokee with the same Bluetec engine is also expected, and Mercedes announced tentative plans for a BLUETEC/electric hybrid W221 S-Class. The BlueTec system was created because the processes that give diesel engines efficient fuel economy also create extra emissions. High compression ratios and lean air-fuel mixtures make high combustion temperatures, which results in more nitrogen oxides and particulate matter (also known as smoke) being released into the atmosphere. While the particulate matter can be controlled with higher injection pressures and particulate filters, the big challenge is limiting NOx (Tier 2 regulations in the US are 0.05 gram per mile of NOx, which is ⅛ of the 0.40 limit in the European Union).

The Bluetec system will use two catalytic converters specifically targeting NOx. The first converter traps the NOx, and later releases it to the second converter which then converts it to nitrogen (N2) and water (H2O). This will make a diesel car legal in 45 states. But to make it pass the more stringent regulations of California, Maine, Massachusetts, New York and Vermont, AdBlue (NH4) will have to be introduced into the system, making the conversion more complete.

NH_4 + H_2O + NO_x \rightarrow \; N_2 + 3H_2O 

The whole exhaust system would work like so:


 * 1) A Diesel Oxidation Catalyst reduces carbon monoxide (CO) and hydrocarbons (HC) released from the exhaust.
 * 2) A DeNOx catalytic converter begins a preliminary removal of oxides of nitrogen.
 * 3) A particulate filter will trap and store smoke particles, burning them off when the filter gets full.
 * 4) A Selective Catalytic Reduction (SCR) catalytic converter will take the remaining nitrogen oxides and covert them to nitrogen and water. AdBlue will be injected into it to help the conversion.