Emissions automobile

The oxidation of CO to CO2, whieh is essential to eontrolling automobile emissions, has been extensively studied beeause of the relative simplieity of this reaetion. CO oxidation was the first reaetion to be studied using the surfaee seienee approaeh and is perhaps the most well understood heterogeneous eatalytie reaetion [58]. The simplieity of CO oxidation by O2 endears itself to surfaee seienee studies. Both reaetants are diatomie moleeules whose adsorption... 

Automobile Automobilebumpers Automobile catalysts Automobile emissions Automobile finishes Automobile gasolines Automobiles... 

The most widespread and persistent urban pollution problem is ozone. The causes of this and the lesser problem of CO and PMjq pollution in our urban areas are largely due to the diversity and number of urban air pollution sources. One component of urban smog, hydrocarbons, comes from automobile emissions, petroleum refineries, chemical plants, dry cleaners, gasoline stations, house painting, and printing shops. Another key component, nitrogen oxides, comes from the combustion of fuel for transportation, utilities, and industries. 

In view of the unforeseen growth in automobile emissions in urban areas combined with the serious air pollution problems in many urban areas, the Congress has made significant changes to the motor vehicle provisions on the 1977 Clean Air Act. 

For the noble metals used in oxidation, the loading is about 0.1 oz per car, with calls for a million ounces per year. The current world production rates of platinum, palladium, and rhodium are 1.9, 1.6, and 0.076 million ounces respectively the current U,S. demand for platinum, palladium, rhodium, and ruthenium are 0.52, 0.72, 0.045, and 0.017 million ounces respectively (72, 73). The supply problem would double if NO reduction requires an equal amount of noble metal. Pollution conscious Japan has adopted a set of automobile emission rules that are the same as the U.S., and Western Europe may follow this creates a demand for new car catalysts approaching the U.S. total. The bulk of world production and potential new mines are in the Soviet Union and South Africa. The importation of these metals, assuming the current price of platinum at 155/oz and palladium at 78/oz, would pose a balance of payment problem. The recovery of platinum contained in spent catalysts delivered to the door of precious metal refiners should be above 95% the value of platinum in spent catalysts is greater than the value of lead in old batteries, and should provide a sufficient incentive for scavengers. 

Catalyst in fuel cells and automobile emission control. 

C05-0080. California s automobile emission standards require that exhaust gases contain less than 220 parts per million hydrocarbons and less than 1.2% CO (both of these values are in moles per mole of air). At standard atmospheric pressure, what are the partial pressures, in torr and in atmospheres, that correspond to these values ... 

In the USA, the Clean Air Act of 1970 established air-quality standards for six major pollutants particulate matter, sulfur oxides, carbon monoxide, nitrogen oxides, hydrocarbons, and photochemical oxidants. It also set standards for automobile emissions - the major source of carbon monoxide, hydrocarbons, and nitrogen oxides. An overview of the major standards is given in Tab. 10.2. The levels of, for example, the European Union (1996) are easily achieved with the present catalysts. The more challenging standards, up to those for the ultralow emission vehicle, are within reach, but zero-emission will probably only be attainable for a hydrogen-powered vehicle. 

Acid rain is actually a catchall phrase for any kind of acidic precipitation, including snow, sleet, mist, and fog. Acid rain begins when water comes into contact with sulfur and nitrogen oxides in the atmosphere. These oxides can come from natural sources such as volcanic emissions or decaying plants. But there are man-made sources as well, such as power plant and automobile emissions. In the United States, two-thirds of all the sulfur dioxide and one-fourth of the nitrogen oxides in the atmosphere are produced by coal-burning power plants. 

In roadside soils, lead was present in the more soluble forms such as PbCIBr and PbS04 from automobile emissions compared to soils near smelters or in mining sites (Adriano, 2001), which contained oxides, sulfides and carbonates (galena, anglesite and cerussite) with low solubility. However, after oxidation of sulfide into sulfate, the soils became very acidic, resulting in the increase in both solubility and bioavailability of the trace metals. 

Since the early work of Langmuir (1), the chemisorption of carbon monoxide on platinum surfaces has been the subject of numerous investigations. Besides its scientific interest, an understanding of CO chemisorption on Pt is of considerable practical importance for example, the catalytic reaction of CO over noble metals (such as Pt) is an essential part of automobile emission control. 

Recently there has been a growing emphasis on the use of transient methods to study the mechanism and kinetics of catalytic reactions (16, 17, 18). These transient studies gained new impetus with the introduction of computer-controlled catalytic converters for automobile emission control (19) in this large-scale catalytic process the composition of the feedstream is oscillated as a result of a feedback control scheme, and the frequency response characteristics of the catalyst appear to play an important role (20). Preliminary studies (e.g., 15) indicate that the transient response of these catalysts is dominated by the relaxation of surface events, and thus it is necessary to use fast-response, surface-sensitive techniques in order to understand the catalyst s behavior under transient conditions. 

Hexane may be expected to comprise around 2% of the VOCs in urban air polluted with hydrocarbons from automobile emissions or other combustion byproducts (Barrefors and Petersson 1993). The -hexane concentrations in urban air will typically be approximately 60% of the concentrations of benzene (Daisey et al. 1994). Close proximity to the exhaust systems of cars or other gasoline-powered vehicles can lead to exposures to increased concentrations of -hexane. Under rush-hour conditions, the concentrations in the interior air of buses will tend to be lower (55 g/m3 or 19.8 ppbv) than the interior levels in cars (69 g/m3 or 24.9 ppbv) or the air around persons riding motorcycles (106 g/m3 or... 

EPA. 1994h. Automobile Emissions an Overview. EPA 400-F-92-007. Ann Arbor, MI U.S. EPA, Office of Mobile Sources, National Vehicle and Fuel Emissions Laboratory. 

Automobile emissions are being decreased with improvements in the... 

In order to show how the properties of the cavity can be used to develop a chemi-cal/biological sensor, the nature of sensor needs to be outlined. What is a sensor In simplistic terms, it is a device that is equipped with proper electronics to quantify changes in a given state of a system. It may be an accelerometer of an automobile, emission gas temperature of a jetliner, environment, bio-metabolism of living bodies, space storms, etc. What is required is a way to detect subtle changes. ... 

The reduction in the lead content of gasoline and the introduction of reformulated gasoline have been very successful in reducing automobile emissions, due to changes in gasoline composition, with further improvements in fuel quality proposed for the early decades of this new millennium. These projections are accompanied by a noticeable and measurable decrease in crude oil quality, and the reformulated gasoline will help meet environmental regulations for emissions for liquid fuels but will be subject to continuous review because of the potential for environmental impact. 

After the pioneering studies of Haagen-Smit, an extensive scientific literature developed on the properties, measurement, and effects of photochemical smog. The attempt to control engine emission has had a profound effect on the automobile and petroleum industries. Estimated costs and associated benefits of automobile emission control each run into the billions per year. ... 

National Academy of Sciences, National Academy of Engineering. Air Quality and Automobile Emission Control. A Report by the Coordinating Committee on Air Quality Studies. Vol. 4. The Costs and Benefits of Automobile Emission Control. U.S. Senate Committee Print Serial No. 93 24. Washington, D.C. U.S. Government Printing OfRce, 1974. 470 pp. 

National Academy of Sciences. National Academy of Engineering. Coordinating Committee on Air Quality Studies. Air Quality and Automobile Emission Control. 

The first three components suggest regional sources of acidic anthropogenic aerosol, the marker elements of a copper smelter, and seasalt, respectively. The fourth component or the ammonium In component three do not provide a ready Interpretation of a known emission or meteorological source of variability. The negative correlation of nitrate with component two Is consistent with separate Influences of the copper smelter and automobile emissions. 

Three components are similar to the results for the West Seattle-Maple Leaf PLS model except that the acid aerosol component no longer has high a loading from nitrate. This specie Is ordinarily associated with automobile emissions. The Tolt site Is remote enough that auto emissions are not as Important an Influence on Che variability In rainwater composition as In Seattle. The fourth component for this PLS model might represent emissions from a cement plant which does not Influence Che West Seattle site. The soil factor is apparently local In nature since It appears In the PCA results but not the PLS results. 

Included in the first group of general industrial contaminants are all of the aromatic hydrocarbons (no. 12-31, see Table III], most of the phenolic compounds (no. 32-42), most of the chlorinated species (no. 43-54), and some industrial solvents (no. 85,88,89,95). Almost all of these compounds have been Isolated and identified in urban watersheds (2,25,26) where they appear to arise from automobile emissions, water chlorination, and general urban activities. 

The importance of lowering automobile emissions has already resulted in changes in car manufacturing. Electric cars, which were popular 100 years ago but fell by the wayside because they could not keep up with gasoline-powered cars, are making a comeback. Although battery-powered vehicles are useful for short, slow trips aroimd a crowded campus, for instance, they continue to be plagued by limited speeds and durations. Automobile manufacturers have alleviated these problems by com-... 

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