Chemical Conversion

Removing air pollutants by chemical conversion is used for VOCs, hydrogen sulfide, and nitrogen oxides.

VOCs

When the concentration of VOCs in an air stream must be eliminated or severely reduced, the VOC can be destroyed thermally or catalytically by oxidation. For thermal destruction technologies, see Section 5.21. The VOCs include hydrocarbons (gasoline vapor, solvents, and aro-matics), halogenated organics (solvents and vinyl chloride monomer), oxygenates (ketones, esters, and aldehydes), and odorous compounds (amines, mercaptans, and others from the effluent treatment or food processing) (see Table 5.20.8) (Spivey 1987). The oxidation products are carbon dioxide, water, and an acidic component (HX [X = Cl,Br,I]) from halocarbons; SOx from sulfur compounds; NOx from amines, nitriles, and nitrogen heterocycles; and P2O5 from phosphorus compounds. Excess oxygen ensures

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