Sulfur process

A process for the removal of H.sub.2 S from a sour gaseous stream comprising:

• (a) contacting the sour gaseous stream in a contacting zone with an aqueous reaction solution at a temperature below the melting point of sulfur, the mixture comprising an effective amount of the ferric chelate of nitrilotriacetic acid and a modifying amount of a modifier selected from compounds having the formula C.sub.n H.sub.2n-1 OH, wherein n is a whole number from 4 through 18, and mixtures thereof, to produce a sweet gas stream and an aqueous admixture containing crystalline sulfur and a reduced reactant;
• (b) regenerating the aqueous admixture in a regeneration zone with oxygen to produce a regenerated reactant;
• (c) removing at least a portion of the crystalline sulfur from the aqueous admixture;
• and
• (d) returning aqueous admixture from step (c) to the contacting zone.

A process for the removal of H.sub.2 S and CO.sub.2 from a sour gaseous stream comprising:

• (a) contacting the sour gaseous stream in a contacting zone at a temperature below the melting point of sulfur with a lean CO.sub.2 -selective absorbent mixture containing an effective amount of the Fe(III) chelate of nitrilotriacetic acid and a modifying amount of a modifier selected from compounds having the formula C.sub.n H.sub.2n-1 OH, wherein n is a whole number from 4 through 22, and mixtures thereof, and producing a sweet gaseous stream and an absorbent admixture containing absorbed CO.sub.2, sulfur, and Fe(II) chelate of nitrilotriacetic acid,
• (b) removing sulfur from the absorbent admixture, and leaving a solution containing absorbed CO.sub.2 and Fe(II) chelate of nitrilotriacetic acid,
• (c) stripping the solution containing absorbed CO.sub.2 and said Fe(II) chelate, and regenerating Fe(III) chelate of nitrilotriacetic acid in said solution with oxygen, producing a lean CO.sub.2 -selective absorbent solution containing the Fe(III) chelate of nitrilotriacetic acid, and
• (d) returning lean CO.sub.2 -selective absorbent solution containing Fe(III) chelate of nitrilotriacetic acid to the contacting zone.

A process for the removal of H.sub.2 S and CO.sub.2 from a sour gaseous stream comprising:

• (a) contacting the sour gaseous stream in a contacting zone at a temperature below the melting point of sulfur with a lean CO.sub.2 -selective absorbent solution containing an effective amount of the Fe(III) chelate of nitrilotriacetic acid and a modifying amount of a modifier selected from compounds having the formula C.sub.n H.sub.2n-1 OH, wherein n is a whole number from 4 through 22, and mixtures thereof, and producing a sweet gaseous stream and an absorbent mixture containing absorbed CO.sub.2, sulfur, and Fe(II) chelate of nitrilotriacetic acid,
• (b) stripping the solution containing absorbed CO.sub.2, sulfur, and said Fe(II) chelate, and then regenerating the Fe(III) chelate of nitrilotriacetic acid in said solution with oxygen, producing a lean CO.sub.2 -selective absorbent solution containing the Fe(III) chelate of nitrilotriacetic acid, and sulfur,
• (c) removing sulfur from the lean CO.sub.2 -selective absorbent solution containing the sulfur and the Fe(III) chelate of nitrilotriacetic acid, and leaving a lean CO.sub.2 -selective absorbent solution containing the Fe(III) chelate of nitrilotriacetic acid, and
• (d) returning lean CO.sub.2 -selective absorbent solution containing the Fe(III) chelate of nitrilotriacetic acid to the contacting zone.

A process for the removal of H.sub.2 S and CO.sub.2 from a sour gaseous stream comprising:

• (a) contacting the sour gaseous stream in a contacting zone at a temperature below the melting point of sulfur with a lean CO.sub.2 -selective absorbent mixture containing an effective amount of the Fe(III) chelate of nitrilotriacetic acid and a modifying amount of a modifier selected from compounds having the formula C.sub.n H.sub.2n-1 OH, wherein n is a whole number from 4 through 22, and mixtures thereof, and producing a sweet gaseous stream and an absorbent admixture containing absorbed CO.sub.2, sulfur, and Fe(II) chelate of nitrilotriacetic acid,
• (b) removing sulfur from the absorbent admixture, and leaving a solution containing absorbed CO.sub.2 and Fe(III) chelate of nitrilotriacetic acid,
• (c) stripping the solution containing absorbed CO.sub.2 and said Fe(II) chelate and regenerating the Fe(III) chelate of nitrilotriacetic acid in said solution with oxygen, producing a lean CO.sub.2 -selective absorbent solution containing the Fe(III) chelate of nitrilotriacetic acid, and
• (d) returning the lean CO.sub.2 -selective absorbent solution containing the Fe(III) chelate of nitrilotriacetic acid to the contacting zone.

A process for the removal of H.sub.2 S and CO.sub.2 from a sour gaseous stream comprising:

• (a) contacting the sour gaseous stream in a contacting zone at a temperature below the melting point of sulfur with a lean CO.sub.2 -selective absorbent solution containing an effective amount of the Fe(III) chelate of nitrilotriacetic acid and a modifying amount of a modifier selected from compounds having the formula C.sub.n H.sub.2n-1 OH, wherein n is a whole number from 4 through 22, and mixtures thereof, and producing a sweet gaseous stream and an absorbent mixture containing absorbed CO.sub.2, sulfur, and the Fe(II) chelate of nitrilotriacetic acid,
• (b) stripping the solution containing absorbed CO.sub.2, sulfur and the said Fe(II) chelate and regenerating the Fe(III) chelate of nitrilotriacetic acid in said solution with oxygen, producing a lean CO.sub.2 -selective absorbent solution containing the Fe(III) chelate of nitrilotriacetic acid and sulfur,
• (c) removing sulfur from the lean CO.sub.2 -selective absorbent solution containing the sulfur and the Fe(III) chelate of nitrilotriacetic acid, and leaving a lean CO.sub.2 -selective absorbent solution containing the Fe(III) chelate of nitrilotriacetic acid, and
• (d) returning lean CO.sub.2 -selective absorbent solution containing the Fe(III) chelate of nitrilotriacetic acid to the contacting zone.