Sulfuric acid, diesel exhaust

Most of the nanoparticles emitted from diesel vehicles appear to nucleate from sulfuric acid and water during the cooling and dilution of the exhaust with ambient air (Kittelson 1998 Shi and Harrison 1999 Collings and Graskow 2000 Tobias et al. 2001). However, based on results from Shi and Harrison (1999), the measured rate of particle formation in diesel exhaust is much greater than the rate calculated from binary... 

Diesel Exhaust Emissions 316 Solvents 321 Sulfuric Acid 324 Cyanides 325 Thermal Stressors 328 Work at High Altitudes 337 Biohazards 340 References 342... 

NOx emissions can be curtailed by equipping vehicles with modem catalytic converter technology. However, sulfur oxides in the exhaust reduce the efficiency of NOx conversion. Sulfur oxides also impede diesel particulate traps. Both SOx and NOx contribute to acid rain, causing other adverse environmental consequences. 

Other undesirable components of both petrol and diesel fuel are sulfur-containing compounds that may be present in small quantities. These give rise to sulfur dioxide in the exhaust gas. In addition to being another acid pollutant, it is also detrimental to the life of the catalytic converter. Consequently, the principal petroleum companies have developed and brought to the market ultra-low sulfur ( green ) petrol and diesel. The action to reduce dramatically sulfur levels in motor fuel has also been made in response to regulations in the USA and the European Union. 

Another approach to the problem of NOx emissions from diesel vehicles is the use of NOx traps. NO2 is acidic and is adsorbed by basic oxide, such as BaO, to form Ba(N03)2. The NO2 is released and reduced to N2 during the periodic engine rich excursion. Basic oxides will, of course, bind sulfur oxides as well, and high temperature intervals with rich exhaust gas must be included in the engine control strategy to desulfate the catalyst. The lean-NOx-trapping concept is currently not in wide commercial use while development efforts are continuing. 

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