Carbon dioxide iron sponge process

The iron sponge process uses the ehemical reaction of ferric oxide with Hi.S to sweeten gas streams. This process is applied to gases with low H S concentrations (300 ppm) operating at low to moderate pressures (. vO-SOO psig). Carbon dioxide is not removed by this process. 

Iron Sponge Also called Dry box. An obsolete process for removing hydrogen sulfide from gas streams by reaction with iron oxide monohydrate. The ferric sulfide that is formed is periodically re-oxidized to regenerate ferric oxide and elemental sulfur. When this process becomes inefficient because of pore-blockage, the sulfur is either oxidized to sulfur dioxide for conversion to sulfuric acid, or is extracted with carbon disulfide. 

On the other hand, absorption onto a solid surface may be employed and solids employed for this purpose include activated carbon, charcoal, and iron sponge. Finally, acid gases may be chemically converted by reactants such as ferric oxide, zinc oxide, calcium oxide, and vanadium pentoxide. Some of these processes remove both carbon dioxide and hydrogen sulfide, whereas others selectively remove hydrogen sulfide (Speight, 2007). 

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