Nitrogen dioxide vehicle emissions

Lenner, M., Nitrogen Dioxide in Exhaust Emissions from Motor Vehicles, Atmos. Environ., 21, 37-43 (1987). 

In spite of the new vehicle emission EUROx regulations, 20% of Europe s urban population is also living in areas where the atmospheric concentrations of nitrogen dioxide (N02) exceed established air quality standards [18]. This is due to several factors related to the diesel-powered cars [19] (1) their increasing market penetration across Europe [20] (2) the NO emission factors of diesel cars exceed the emission levels as established during the type approval of these vehicles in the laboratory [19, 21-25] and (3) the fraction of N02 in the NO emissions of diesel... 

Tertiary gas standards for the provision of traceable measurements to the United Kingdom s vehicle emissions testing programme (the MoT test ). These comprise specific concentrations of mixtures of carbon monoxide, carbon dioxide and propane in a diluent gas of nitrogen. 

Burgard, D.A., Dalton, T.R., Bishop, G.A., Starkey, J.R. and Stedman, D.H. (2006) Nitrogen dioxide, sulfur dioxide, and ammonia detector for remote sensing of vehicle emissions. Rev. Sci. Instrum., 77. 014101-1-014101. 

There are strong indications that sulphur dioxide (SO2) emissions increased by about a factor of two between 1950 and 1970 in most of Europe and the same general trend also holds for nitrogen oxides (NO,). The emissions of sulphur dioxide have generally levelled off since 1970, while the nitrogen oxides increase with the number of motor vehicles. 

The criteria for selection of a suitable oxidation catalyst for heavy-duty ethanol-fiielled vehicles in city traffic involve aspects such as regulated emissions (CO, NOx, hydrocarbons and particulates), emissions of unbumed ethanol, formation of acetaldehyde, acetic acid, and nitrogen dioxide. The oxidation of nitric oxide to nitrogen dioxide can be a problem when using highly active precious metal catalysts. This is especially the case when using platinum as active material (Pettersson et ai, 1994). NO2 is more toxic than NO and should be minimized at street levels. The catalyst with the highest activity for ethanol conversion is not necessarily the best choice if the minimum environmental impact is the objective. 

The selection of the optimal catalyst for heavy-duty ethanol vehicles in city traffic from the enviromuental point-of-view is a question of choosing tlie oxidation catalyst which produces the least hazardous combination of reaction products. It is not sufficient to consider only the activity for eliminating the regulated emissions. Considering fonnation of acetaldehyde, acetic acid and nitrogen dioxide, as well as emissions of unburaed ethanol and carbon monoxide, tliere are some interesting catalyst combinations, which will be investigated further both in laboratory and frill-scale experiments. 

Nitrogen Dioxide Nitrogen dioxide (NO2) is produced by rapid oxidation of nitric oxide (NO), which is formed during high-temperature combustion processes in vehicles, power plants, and so forth. NO2 is also formed further away from the emission source through oxidation of NO by ambient O3 ... 

Air legislation is targeting emissions from industrial operations, greenhouse gases, lead, motor vehicle emissions, nitrogen oxides, ODS, sulfur dioxide, and suspended particulate matter. Water legislation in the EU is divided into effect- and source-oriented direc-... 

Recent years have seen substantial cuts in emissions of NOx in developed countries, which has been reflected in a commensurate reduction in ambient concentrations of NOx. However, ambient concentrations of nitrogen dioxide have decreased very much less, as this is a secondary pollutant whose concentrations are determined by the oxidizing capacity of the air as well as the emissions of NOx. Most Western European countries are, however, now seeing a slow dechne in nitrogen dioxide in response to substantial cuts in vehicle emissions of NOx. 

Nitrogen dioxide, which results from motor vehicles and (to a lesser extent) electric utility emissions, is also a lung and eye irritant. Nitrogen dioxide is partially responsible for the brown color of smog. It is a precursor to ozone formation and contributes to acid rain. Long-term exposure can result in acute respiratory disease in children. 

Most measures to counteract acid deposition involve lowering the amount of acidic substances released into the atmosphere. Nitrogen oxides are removed from vehicle emissions using catalytic converters, and sulfur dioxide emissions from coal-fired power stations can be decreased in several ways. 

Human-made sources cover a wide spectrum of chemical and physical activities and are the major contributors to urban air pollution. Air pollutants in the United States pour out from over 10 million vehicles, the refuse of over 250 million people, the generation of billions of kilowatts of electricity, and the production of innumerable products demanded by eveiyday living. Hundreds of millions of tons of air pollutants are generated annu ly in the United States alone. The five main classes of pollutants are particulates, sulfur dioxide, nitrogen oxides, volatile organic compounds, and carbon monoxide. Total emissions in the United States are summarized by source categoiy for the year 1993 in Table 25-10. 

Catalytic Converter an air pollution abatement device that removes pollutants from motor vehicle exhaust either by oxidizing them into carbon dioxide and water or reducing them to nitrogen. A typical catalytic oxidizer for auto emission control is illustrated in the sidebar figure. 

Transportation accounts for about one-fourth of the primary energy consumption in the United States. And unlike other sectors of the economy that can easily switch to cleaner natural gas or electricity, automobiles, trucks, nonroad vehicles, and buses are powered by internal-combustion engines burning petroleum products that produce carbon dioxide, carbon monoxide, nitrogen oxides, and hydrocarbons. Efforts are under way to accelerate the introduction of electric, fuel-cell, and hybrid (electric and fuel) vehicles to replace sonic of these vehicles in both the retail marketplace and in commercial, government, public transit, and private fleets. These vehicles dramatically reduce harmful pollutants and reduce carbon dioxide emissions by as much as 50 percent or more compared to gasoline-powered vehicles. 

Almost all the major car, bus, and truck manufacturers have developed compressed natural gas engines and vehicles. These manufacturers have been able to offer better performance (due to higher octane) and far lower emissions of nitrogen oxides, carbon monoxide, particulate matter, and carbon dioxide to the atmosphere. In 1998, Honda introduced the cleanest internal combustion engine vehicle ever commercially produced the natural gas Civic GX with emissions at one-tenth the state of California s Ultra Low Emission Vehicle standard. Primarily due to the high octane of natural gas, Honda achieved these results without sacrificing performance. 

In Mexico City, several air quality parameters are measured continuously by an Automated Monitoring Network operated by the Under Secretariat of Ecology. Carbon monoxide, particulate matter, sulfur dioxide, nitrogen oxide, and ozone are the contaminants exceeding Air Quality Standards. Emissions produced by 2.7 million vehicles and 35,000 commercial and industrial outfits are not easily dispersed in a Valley located at 2240 m and surrounded by two mountain chains which hinder air circulation. An Integral Program, recently established to alleviate pollution, is briefly described. 

The biggest attraction of fuel-cell-powered vehicles for car manufacturers is the fact that they no longer emit nitrogen oxides or hydrocarbons (or carbon dioxide if they are fuelled with pure hydrogen). (Burning hydrogen in internal combustion engines results in NOx emissions fuel-cell vehicles emit only water.) This effectively does away with one of the main environmental discussion points about traffic. In California, these zero-emission cars have been demanded since the foundation of the California Fuel Cell Partnership in 1999. 

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. 

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