Sulfur compound removal with impregnated carbon

Sulfur Compound Removal with Impregnated Carbon... 

Sulfur Compound Removal with Impregnated Carton, 1126 Mercury Removal with Impregnated Carbon, 1127... 

BMS A process for removing mercury from the effluent from the Castner-Kellner process. Chlorine is used to oxidize metallic mercury to the mercuric ion, and this is then adsorbed on activated carbon impregnated with proprietary sulfur compounds. Developed by Billingsfors Bruks, Sweden. 

Gasoline contains several types of sulfur compounds, including mercaptans. These compounds can be removed from gasoline using activated carbons impregnated with sodium hydroxide. Usually active carbons containing 10 to 15% sodium hydroxide are used. The removal of mercaptans involves adsorption on the carbon surface and a chemical reaction with sodium hydroxide. 

Two types of impregnating agents are used to increase the effectiveness of carbon for the removal of traces of H2S and low molecular-weight sulfur compounds. The types are alkaline materials such as sodium hydroxide or sodium carbonate, which hold the sulfur compounds by acid-base reaction, and metal oxides, which hold the sulfur as metal sulfides or sulfates. Examples of the two types are Calgon Carbon Corporation s Type IVP (Improved Vapor Pha.se), which is reported to be impregnated with sodium hydroxide (Bourke and Mazzoni, 1989), and Type FCA, which is stated to be a metal-oxide impregnated carbon (Calgon, 1978). 

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). 

Besides basic compoimds, an improved capacity for MM removal can be also obtained by surface impregnation with compounds, which are able to promote redox surfece reaction. It was found that the modification of the activated carbon surface with Fe203, KI and KIO3 (all about 4 wt%) increased the capacity of activated carbon by a iactor 3-5 [134]. On the other hand, the same treatment of activated carbon fibers increased the capac% over 200 times. It is interesting and very unique for the results, which have been reported in the literature that this process led to the deposition of elemental sulfur on the surface, which was confirmed using SEM/EDAX experiments. 

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