Automobiles exhaust gases

Electrochemistry plays an important role in the large domain of. sensors, especially for gas analysis, that turn the chemical concentration of a gas component into an electrical signal. The longest-established sensors of this kind depend on superionic conductors, notably stabilised zirconia. The most important is probably the oxygen sensor used for analysing automobile exhaust gases (Figure 11.10). The space on one side of a solid-oxide electrolyte is filled with the gas to be analysed, the other side... 

This has obvious potential for removing undesirable NO and CO from automobile exhaust gases. 

The major route of formation of these nitro compounds is via the reaction of VOCs with the NO arising from hot flue gases, such as automobile exhaust gases and gas streams used for drying food stuffs, etc. In these combustion systems the aliphatics can react with nitro compounds or arenes to produce nitro-PAH and nitroarenes. Some of the NO produced are thus converted into C-nitroso compounds. The interactions and reaction chemistry of these compounds is complex and difficult to interpret. 

In this section the models employed for simulation of catalytic monolith reactor are discussed, focusing on effective description of heat and mass transfer phenomena in monolith channel. The number of different mathematical models developed for converters of automobile exhaust gases over the last decades is huge—cf., e.g. Heck et al. (1976), Young and Finlayson (1976), Oh and Cavendish (1982), Zygourakis and Aris (1983), Chen et al. (1988),... 

Fig. 7. The variation with time of the concentrations of a number of components in an irradiated mixture of automobile exhaust gases and air.111...

Formula CO MW 28.01 CAS [630-08-0] produced when substances bum in insufficient air occurs in automobile exhaust gases and closed confinements high risk of exposure under fire conditions a colorless gas with no odor liquefies at -191.5°C solidifies at -205°C slightly soluble in water soluble in alcohol, acetone, chloroform, and acetic acid highly toxic. 

Amongst other developments, a gold-oxide composite has been developed as a sensor for hydrocarbon monitoring in automobile exhaust gases,119,120 and Au In2C>3 ceramics have been used for detection of ammonia and other reducing gases.121... 

Habboush AE, Farroha SM, Naoum OF, et al. 1988. The collection and direct analysis of low molecular weight aldehydes from automobile exhaust gases by GLC. Int J Environ Anal Chem 32 79-85. 

Figure 5.1-7 Raman spectrum of automobile exhaust gases for the simultaneous detennination of different components.

A multichannel Raman spectrometer for the study of dynamic processes in analytical chemistry has been described by D Orazio and Hirschberger (1983), they recorded the Raman spectra of automobil exhaust gases (Figs. 5.1-8a — 5.1-8c). 

A possible practical way to eliminate oxides of nitrogen (such as NO2) from automobile exhaust gases uses cyanuric acid, C3N3(0H)3. When heated to the relatively low temperature of 625°F, cyanuric acid converts to gaseous iso-cyanic acid (HNCO). Isocyanic acid reacts with NO2 in the exhaust to form nitrogen, carbon dioxide, and wateg all of which are normal constituents of the air. 

Stupfel M, Romary F, Magnier M, et al. 1971. Comparative acute toxicity of several atmospheric pollutants, in male and female mice Automobile exhaust gases, nitrogen oxides, sulfur dioxide, ozone, ammonia and carbon dioxide. C R Seances Soc Biol Fil 19 1869-1872. 

Wayne, L. G., and J. G. Romanofsky (1961). Rates of reaction of the oxides of nitrogen in the photooxidation of diluted automobile exhaust gases. In "Chemical Reactions in the lower and upper Atmosphere (R. D. Cadle, ed.), pp. 71-86. Wiley (Interscience), New York. 

Composition of the gas fed to the preheat section of the reactor (Table I) was selected by averaging data from numerous sources on the composition of automobile exhaust gases. Propylene simulated all hydrocarbons in the exhaust gas. For some experiments, the catalysts were aged in a 260-in.3 converter attached to the exhaust pipe from a 350-in.3 V8 engine under a water brake dynamometer load equivalent to 50 mph. 

Meantime, while a cure was being sought, it was apparent that hydrocarbons in automobile exhaust gases could be transformed into harmless products before reaching the atmosphere and that oxidation catalysts were the most practical tools to do it. 

There is considerable literature concerning catalysis of the NO + CO and NO + H2 reactions over Rh and Pt in various forms. A general conclusion is that the latter reaction is substantially fester than the former with Rh [1,2] and especially Pt [1-4] under equivalent conditions. With respect to NO removal, the presence of CO inhibits the NO + H2 reaction [1-6], see also [7], Rather surprisingly there appears to be no definitive studies of the mixed NO, CO, H2 reaction system [7] even though all three gases are simultaneously present in automobile exhaust gases. 

J.K. Walker, C.L. O Hara "Analysis of Automobile Exhaust Gases by Mass Spectrometry", Anal. Chem. 27 (5), 825-828, 1955. 

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