Automobile emission control

The trends in the automobile emission standards for the USA and Eitrope since 1966 are given in Table 11.7. Compliance with the standards set has been made possible by the use of automobile emission control catalysts. These were first used in the US during 1975 and in Europe from 1993. As a resirlt of continuous improvement to design and manufacture, the catalysts have been able to conform with the increasing severity of the regulations. 

TABLE 11.7. Exhaust Emission Limits for US and European Union. 

In simple terms, the two-way catalyst is solely an oxidation catalyst, which is used to convert carbon monoxide and residual hydrocarbons to carbon dioxide. The three-way catalyst also provides a capability for reduction, which is required for the removal of nitrogen oxides. 

TABLE 11.8. Variation of Exhaust Gas Composition with A/F Ratio. 

Many chemical reactions can take place in the engine effluent to remove undesirable impurities and some of these are shown in Table 11.9. Reactions A-C can all take place in a catalytic converter although, if possible, reactions C-D should be avoided. 

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Catalyst in fuel cells and automobile emission control. 

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. 

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. 

Leclerc, J. P., and Schweich, D., Modelling catalytic monoliths for automobile emission control, in Chemical Reactor Technology for Environmentally Safe Reactors and Products (H. I. de Lasa, G. Dogu, and A. Ravella, Eds.), pp. 547-575. Kluwer Academic Publishers, Netherlands (1993). 

Cooper, B. J., Renny, L. V., and White, R. J., Lead Poisoning of Automobile Emission Control Catalysts—Influence of Emission System and Catalyst Design Characteristics on the Poisoning Mechanism, Am. Chem. Soc.. Symp. Automot. Catal., Chicago Meet., 1975. 

Rhodium compounds are somewhat toxic and have been used in oncological chemotherapy, but they are less effective than platinum complexes. The expense and rarity of rhodium means that it is rarely a significant pollution hazard, particularly as it is of low inherent toxicity. The occupational exposure limit to dust is lmgm and the LD50 for oral ingestion is 200mgkg for several species. At these levels, rhodium and its compounds exhibit weak carcinogenicity and adverse reproductive effects have been observed. Nevertheless, rhodium dust and water-soluble rhodium compounds are now found at roadsides as a result of erosion of automobile emission control catalysts. 

C.J. Pereira. J.E. Kubsh, and L.L. Hegedus, Computer-aided design of catalytic monoliths for automobile emission control, Chenu Eng. Sci. 43 2087 (1988). 

Another type of electrical conductivity observed in ceramics is ionic conductivity, which often occurs appreciably at elevated temperature a widely used material exhibiting this behavior is zirconia doped with other oxides such as calcia (CaO) or yttria (Y2O3). For this material, atomic oxygen is the mobile ionic species. Doped zirconia finds widespread use as oxygen sensors, especially as part of automobile emission control systems, where the oxygen content of the exhaust gas is monitored to control the air-to-fuel ratio. Other applications of ionic conducting ceramics are as the electrolyte phases in solid-oxide fuel cells and in sodium-sulfur batteries. 

AECC - Automobile Emissions Control by Catalyst, Avenue de Tervueren 13 A, 1040 Brussels, Belgium... 

Searles Robert Automobile Emissions Control by Catalyst Belgium... 

M.P. Walsh, Experience in the United States with Automobile Emission Control, Platinum Metals Review, July 1986, vol. 30, n°3,106-115. 

Final Proposals for European Common Market Automobile Emission Control Standards... 

G. J. K. Acres and B. J. Cooper, Automobile Emission Control Systems, Platinum... 

DEVELOPMENT OF A COPPER CHROMITE CATALYST FOR CARBON MONOXIDE AUTOMOBILE EMISSION CONTROL... 

Development of a Copper Chromite Catalyst for Carbon Monoxide Automobile Emission Control",... 

Leclerc J.P., and D. Schweich Modelling catalytic monoliths for automobile emission control, in "Chemical reactor technology for enviromnentally safe reactors and products", H.I. de Lasa et al. Ed., Kluwer Academic Pub., tlie Netherlands, p. 547-576, 1993. 

J.P. Leclerc, D.Schweich, Modeling Catalytic Monoliths For Automobile Emission Control, H.I. de Lasa et al. (eds.) Chemical Reactor for Enviromnentally Safe Reactors and Products, 547-576, (1993) Kluwer Academic Publishers. 

Kummer, J.T. Catalysts for automobile emission control. Prog. Energy Combust. Sci. 1980, 6, 177-199. 

Modeling Catalytic Monoliths for Automobile Emission Control... 

Process Industries Furnaces used for the fabrication of spark plug insulators, catalyst supports for automobile emission control systems, dinnerware, magnetic ceramics, and electrical ceramics are lined with ceramics. Ceramic high-temperature furnace linings and thermal insulation are used in petroleum and chemical processing, cement production, heat treatments, and paper production. 

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