Scrubbing processes fluorine removal

Zeolites have also proven applicable for removal of nitrogen oxides (NO ) from wet nitric acid plant tail gas (59) by the UOP PURASIV N process (54). The removal of NO from flue gases can also be accomplished by adsorption. The Unitaka process utilizes activated carbon with a catalyst for reaction of NO, with ammonia, and activated carbon has been used to convert NO to N02, which is removed by scrubbing (58). Mercury is another pollutant that can be removed and recovered by TSA. Activated carbon impregnated with elemental sulfur is effective for removing Hg vapor from air and other gas streams the Hg can be recovered by ex situ thermal oxidation in a retort (60). The UOP PURASIV Hg process recovers Hg from clilor-alkali plant vent streams using more conventional TSA regeneration (54). Mordenite and clinoptilolite zeolites are used to remove HQ from Q2, clilorinated hydrocarbons, and reformer catalyst gas streams (61). Activated aluminas are also used for such applications, and for the adsorption of fluorine and boron—fluorine compounds from alkylation (qv) processes (50). 

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