Pollutants, in exhaust gas

Evaluation of the concentrations of four toxic pollutants in exhaust gas (ordeA of magnitude). ... 

Fig. 1.9 Structure of intelligent catalyst and comparison of the catalytical activity of the intelligent catalyst and the conventional Al203-supported one for the removal of pollutants in exhaust gas...

Type of pollutant Weight % of volatile organic compounds contained In exhaust gas Relative risk factor... 

Experimentally measured pure-component adsorption characteristics of O2, N2, CO2, and SO2 on H-mordenite were correlated to predict the behavior of multicomponent mixture of these gases. These correlations, based upon the relationships developed by Myers and Prausnitz, were successfully substantiated experimentally. The CO2 and SO2, which are the predominantly adsorbed components, controlled the fate of the multi-component sorption. This prevailed even at the concentration levels where the pure-component data indicate comparable affinity for both the strongly and the weakly adsorbed species. Hence, indications are that adsorption may be effectively useful in exhaust gas cleanup processes. The temperature sensitivity of the pure components contributes significantly to the selectivity of the sieve for the various components, and the data obtained indicate that this also tends to favor the desired applications in pollution combat. 

Catalytic combustion applications can be classified as either primary or secondary pollution control, that is, emissions prevention or emissions clean-up. The most common example of catalytic combustion for emissions clean-up is the catalytic converter in the exhaust system of automobiles. Catalytic combustion is also increasingly used for the removal of volatile organic compounds (VOCs) from industrial exhaust streams. The use of catalytic combustion in exhaust gas clean-up is discussed in other sections of this Handbook this section deals only with primary control applications. 

Satisfactory conversion of all three pollutants (HC, CO, NO ) by means of three-way catalysts is only possible if the oxygen partial pressure in exhaust gas - with three-way concepts determined by the A/F ratio - is kept within certain limits the so-called A/F window (see Fig. 1). 

Aldehydes, both aliphatic and aromatic, are powerful air pollutants. They are present in exhaust gas and are also formed from exhaust gas in smog-forming reactions in the air. They have been reported to be eye irritants and irritants to mucous membranes, plant toxicants, and participants in photochemical smog reactions. 

In Japan, the Ministry of Health announced in January 1997 that the expected value of a newly installed furnace will be less than 0.1 ng. The Environmental Protection Agency is in the process of determining guidelines for dioxin concentration in exhaust gas based on the air pollution protection law. 

The purpose of such scmbbing operations may be any of the following gas purification (eg, removal of air pollutants from exhaust gases or contaminants from gases that will be further processed), product recovery, or production of solutions of gases for various purposes. Several examples of appHed absorption processes are shown in Table 1. 

Add-on Control Device an air pollution control device such as carbon absorber or incinerator that reduces the pollution in an exhaust gas. The control device usually does not affect the process being controlled and thus is "add-on" technology, as opposed to a scheme to control pollution though altering the basic... 

Dioxin-like compounds are known to be one of the most harmful persistent organic pollutants of the chlorine based compounds. Dioxins are repeatedly synthesized and decomposed by complicated mechanisms and temperature changes at different locations in municipal solid waste incineration processes and the final streams discharged are commonly exhaust gas and incineration ash. Dioxins in different discharge types and compositions of effluents could be affected by incineration conditions such as temperature, feeding and discharging methods and incinerator type [47]. 

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