Diesel nitrogen oxides emissions

It is believed that SCR by hydrocarbons is an important way for elimination of nitrogen oxide emissions from diesel and lean-burn engines. Gerlach etal. [115] studied by infrared in batch condition the mechanism of the reaction between nitrogen dioxide and propene over acidic mordenites. The aim of their work was to elucidate the relevance of adsorbed N-containing species for the F>cNOx reaction to propose a mechanism. Infrared experiments showed that nitrosonium ions (NO+) are formed upon reaction between NO, NOz and the Brpnsted acid sites of H—MOR and that this species is highly reactive towards propene, forming propenal oxime at 120°C. At temperatures above 170°C, the propenal oxime is dehydrated to acrylonitrile. A mechanism is proposed to explain the acrylonitrile formation. The nitrile can further be hydrolysed to yield... 

Catalyst activities, specific, 10 47t Catalyst additives, nitrogen oxide emissions and, 11 719 Catalyst-based diesel particulate filter (CB-DPF) technology, 10 61-62 Catalyst bed(s)... 

In Europe, extremely fuel-efficient diesels, ranging from Volkswagens to BMWs, achieving from 40 to 99 mpg, account for about 55% of all cars sold. Diesels of this type tend to be small and very inexpensive to operate. This is important in Europe, where parking places are hard to find and fuel is quite expensive. European diesel fuel has long had lower sulfur content that that sold in the U.S., which makes the European version cleaner. New systems are also in place that utilize filters to reduce nitrogen-oxide emissions, such as Daimler s BlueTec. 

Hydrocarbon, carbon monoxide, and particulate matter are all reduced in both direct and indirect inject diesel engines fueled with biodiesel when compared with diesel, whereas nitrogen oxide emissions are increased (30-33). 

Extensive investigations at the Institute for Mechanical Engineering and Vehicle Technology at the University of Applied Science in Trier as well as practical tests showed that soot emissions were lowered by more than 90% upon the application of water-diesel micro emulsions (see Fig. 11.5(a)). Interestingly, the NO -particulate matter trade-off is avoided, i.e. nitrogen oxide emissions are also lowered significantly (Fig. 11.5(b)). The surfactants used for the formation of the microemulsion are oxidised species, which, as already mentioned above, decrease the soot formation further. 

The density of heavy fuels is greater than 0.920 kg/1 at 15°C. The marine diesel consumers focus close attention on the fuel density because of having to centrifuge water out of the fuel. Beyond 0.991 kg/1, the density difference between the two phases —aqueous and hydrocarbon— becomes too small for correct operation of conventional centrifuges technical improvements are possible but costly. In extreme cases of fuels being too heavy, it is possible to rely on water-fuel emulsions, which can have some advantages of better atomization in the injection nozzle and a reduction of pollutant emissions such as smoke and nitrogen oxides. 

Compliance with the EuroIII standards (2000) forced the fitting of Diesel oxidation catalysts (DOC) in the exhaust line [for the after-treatment of unburnt hydrocarbons (HC) and carbon monoxide (CO)]. Additionally, the exhaust gas recirculation (EGR) was adapted to reduce the engine-out emissions of nitrogen oxides (NOx). 

NO control, diesel engine, 10 61. See also Nitrogen oxide (NO ) exhaust control NO emissions, 10 32, 35, 36, 46, 137 NO production, 13 855, 856-857 NO reduction catalysts, 12 430 NO reduction technology, post regenerator, 11 719-720 NOXSO process, 22 779 Nozzle disk centrifuge... 

Daimler-Benz has accumulated data on NECAR III emissions with a dynamometer programmed for a mix of urban and suburban driving. The results were promising since there were zero emissions for nitrogen oxide and carbon monoxide, and extremely low hydrocarbon emissions of only. 0005 per gram per mile. NECAR III did produce significant quantities of carbon dioxide similar to the emissions of a direct-injection diesel engine where the fuel is injected directly into the combustion chamber. Direct-injection produces less combustion residue and unburned fuel. 

Because of the low-sulfur, -nitrogen, and -aromatic content of Fischer-Tropsch fuels, there is renewed interest in these products. In two recent studies, Fischer-Tropsch diesel was evaluated and compared to an ultra-low sulfur California diesel and to a 49 cetane number, low-sulfur diesel. In the two studies, carbon monoxide, nitrogen oxide, hydrocarbon, particulate, and carbon dioxide emissions were reduced in vehicles fuels by Fischer-Tropsch diesel. The fuel economy, however, was also reduced. The low aromatic content and high concentration of waxlike hydrocarbons in Fischer-Tropsch diesel can lead to the need for special handling and treatment of the fuel to prevent gelling when used in cold-temperature conditions. 

When biodiesel is blended with diesel fuel, the emissions results change somewhat. A significant decrease in hydrocarbon and carbon monoxide emissions is typical, no change or a small increase in oxides of nitrogen emissions, and significant reduction in particulate emissions. Emissions of toxins would also decrease according to the percentage substitution of diesel fuel. 

When oxidized in a fuel cell, the only significant emission is water vapor. When combusted in an internal-combustion engine (spark-ignition or diesel) some oxides of nitrogen and peroxides may be produced, depending on the calibration of the fuel system and configuration of the engine. None of the toxic emissions typical of petroleum fuels are present [1.35]. 

Emissions from gasoline and diesel engines are commonly classified into three categories volatile organic compounds, toxics and nitrogen oxides. The composition of exhaust gas from a vehicle is dependent on its fuel properties and the vehicle s emission control technology. Table 4.1 summarizes the primary fuel properties of interest and their qualitative effects on emissions. 

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