Method of removing hydrogen sulfide from gases

Claim 2

A process for the removal of H 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 reaction solution comprising an effective amount of an oxidizing reactant selected from the group consisting of oxidizing polyvalent metal chelates of nitrilotriacetic acid, and mixtures thereof, and producing a sweet gas stream and an aqueous admixture containing sulfur, reduced reactant, and decomposition products of said reactant; (b) removing aqueous admixture from the contacting zone, and removing solid sulfur containing residual aqueous admixture from said aqueous admixture; (c) regenerating said aqueous admixture, producing a regenerated oxidizing reactant solution, and returning regenerated oxidizing reactant solution to the contacting zone; (d) concomitantly washing solid sulfur from step (b) with an aqueous washing liquid and producing improved sulfur and an aqueous solution containing a polyvalent metal chelate of nitrilotriacetic acid, or mixtures thereof; (e) contacting aqueous solution produced in step (d) with sufficient acid selected from the group consisting of HCl, H 2 SO 4 , H 3 PO 4 , and mixtures thereof, to dissociate at least the bulk of the polyvalent metal chelate or chelates in solution and under conditions to precipitate a solid containing nitrilotriacetic acid, and precipitating and recovering said solid.

Claim 3

The process of claim 1 wherein the solid precipitated is neutralized with a basic material selected from alkali metal hydroxides and ammonium hydroxide.

Claim 4

The process of claim 1 wherein the oxidizing reactant is the Fe+++ chelate of nitrilotriacetic acid.

Claim 5

A process for the removal of H 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 reaction solution comprising an effective amount of an oxidizing reactant selected from the group consisting of oxidizing polyvalent metal chelates of nitrilotriacetic acid, and mixtures thereof, and producing a sweet gas stream and an aqueous admixture containing solid sulfur, reduced reactant, and decomposition products of said reactant; (b) removing aqueous admixture from the contacting zone; (c) regenerating said aqueous admixture and producing a regenerated aqueous oxidizing reactant solution containing solid sulfur; (d) removing solid sulfur containing residual aqueous oxidizing reactant solution from regenerated solution from step (c), and returning regenerated aqueous reaction solution having reduced sulfur content to the contacting zone; (e) concomitantly washing solid sulfur from step (d) with an aqueous washing liquid and producing improved sulfur and an aqueous solution containing a regenerated polyvalent metal chelate of nitrilotriacetic acid, or mixtures thereof; (f) contacting aqueous solution produced in step (e) with sufficient acid selected from the group consisting of HCl, H 2 SO 4 , H 3 PO 4 , and mixtures thereof, to dissociate at least the bulk of the polyvalent metal chelate or chelates in solution and under conditions to precipitate a solid containing nitrilotriacetic acid, and precipitating and recovering said solid.

Claim 6

A process for the removal of H 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 reaction solution comprising an effective amount of an oxidizing reactant selected from the group consisting of oxidizing polyvalent metal chelates of nitrilotriacetic acid, and mixtures thereof, and producing a sweet gas stream and an aqueous admixture containing solid sulfur, reduced reactant, and decomposition products of said reactant; (b) removing aqueous admixture from the contacting zone; (c) regenerating said aqueous admixture and producing a regenerated aqueous oxidizing reactant solution containing solid sulfur; (d) removing solid sulfur containing residual aqueous oxidizing reactant solution from regenerated solution from step (c), and returning regenerated aqueous reaction solution having reduced sulfur content to the contacting zone; (e) concomitantly washing solid sulfur from step (d) with an aqueous washing liquid and producing improved sulfur and an aqueous solution containing a regenerated polyvalent metal chelate of nitrilotriacetic acid, or mixtures thereof; (f) contacting aqueous solution produced in step (e) with sufficient acid selected from the group consisting of HCl, H 2 SO 4 , H 3 PO 4 , and mixtures thereof, to dissociate at least the bulk of the polyvalent metal chelate or chelates in solution and under conditions to precipitate a solid containing nitrilotriacetic acid, and precipitating and recovering said solid.

Claim 7

The process of claim 4 wherein the solid precipitated is neutralized with a basic material selected from alkali metal hydroxides and ammonium hydroxide.

Claim 8

The process of claim 4 wherein the oxidizing reactant is the Fe+++ chelate of nitrilotriacetic acid.

Claim 9

A process for the removal of H 2 S from a sour gaseous stream comprising: (a) contacting the sour gaseous stream is a contacting zone with an aqueous reaction solution at a temperature below the melting point of sulfur, the reaction solution comprising an effective amount of oxidizing polyvalent metal chelates of nitrilotriacetic acid, and mixtures thereof, and producing a sweet gas stream and an aqueous admixture containing sulfur, reduced reactant, and decomposition products of said reactant; (b) removing aqueous admixture from the contacting zone; (c) separating removed aqueous admixture into an aqueous reactant solution having reduced sulfur content and an aqueous reactant slurry containing increased sulfur content; (d) regenerating said aqueous reactant solution, and returning regenerated reactant solution to the contacting zone; (e) concomitantly recovering solid sulfur containing residual aqueous admixture from said aqueous reactant slurry; (f) washing solid sulfur from step (e) with an aqueous wash and producing improved sulfur and an aqueous solution containing a polyvalent metal chelate of nitrilotriacetic acid, or mixtures thereof; (g) contacting aqueous solution produced in step (f) with sufficient acid selected from the group consisting of HCl, H 2 SO 4 , H 3 PO 4 , and mixtures thereof, to dissociate at least the bulk of the polyvalent metal chelate or chelates in solution and under conditions to precipitate a solid containing nitrilotriacetic acid, and precipitating and recovering said solid.

Claim 10

A process for the removal of H 2 S from a sour gaseous stream comprising: (a) contacting the sour gaseous stream is a contacting zone with an aqueous reaction solution at a temperature below the melting point of sulfur, the reaction solution comprising an effective amount of oxidizing polyvalent metal chelates of nitrilotriacetic acid, and mixtures thereof, and producing a sweet gas stream and an aqueous admixture containing sulfur, reduced reactant, and decomposition products of said reactant; (b) removing aqueous admixture from the contacting zone; (c) separating removed aqueous admixture into an aqueous reactant solution having reduced sulfur content and an aqueous reactant slurry containing increased sulfur content; (d) regenerating said aqueous reactant solution, and returning regenerated reactant solution to the contacting zone; (e) concomitantly recovering solid sulfur containing residual aqueous admixture from said aqueous reactant slurry; (f) washing solid sulfur from step (e) with an aqueous wash and producing improved sulfur and an aqueous solution containing a polyvalent metal chelate of nitrilotriacetic acid, or mixtures thereof; (g) contacting aqueous solution produced in step (f) with sufficient acid selected from the group consisting of HCl, H 2 SO 4 , H 3 PO 4 , and mixtures thereof, to dissociate at least the bulk of the polyvalent metal chelate or chelates in solution and under conditions to precipitate a solid containing nitrilotriacetic acid, and precipitating and recovering said solid.

Claim 11

The process of claim 5 wherein the solid precipitated is neutralized with a basic material selected from alkali metal hydroxides and ammonium hydroxide.

Claim 12

The process of claim 7 wherein the oxidizing reactant is the Fe+++ chelate of nitrilotriacetic acid.

Claim 13

A process for the removal of H 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 reaction solution comprising an effective amount of an oxidizing reactant selected from the group consisting of oxidizing polyvalent metal chelates of nitrilotriacetic acid, and mixtures thereof, and producing a sweet gas stream and an aqueous admixture containing sulfur, reduced reactant, and decomposition products of said reactant; (b) removing aqueous admixture from the contacting zone; regenerating said aqueous admixture and producing a regenerated aqueous oxidizing reactant solution containing solid sulfur; (c) separating regenerated oxidizing reactant solution containing solid sulfur into a regenerated aqueous reaction solution having reduced sulfur content and an aqueous reactant slurry containing increased sulfur content, and returning the regenerated aqueous reaction solution to the contacting zone; (d) concomitantly recovering solid sulfur containing residual aqueous admixture from aqueous reactant slurry from step (c); (e) washing solid sulfur from step (d) with an aqueous washing liquid and producing improved sulfur and an aqueous solution containing the polyvalent metal chelate of nitrilotriacetic acid, or mixtures thereof; (f) contacting aqueous solution produced in step (e) with sufficient acid selected from the group consisting of HCl, H 2 SO 4 , H 3 PO 4 , and mixtures thereof, to dissociate at least the bulk of the polyvalent metal chelate or chelates in solution and under conditions to precipitate a solid containing nitrilotriacetic acid, and precipitating and recovering said solid.

Claim 14

A process for the removal of H 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 reaction solution comprising an effective amount of an oxidizing reactant selected from the group consisting of oxidizing polyvalent metal chelates of nitrilotriacetic acid, and mixtures thereof, and producing a sweet gas stream and an aqueous admixture containing sulfur, reduced reactant, and decomposition products of said reactant; (b) removing aqueous admixture from the contacting zone; regenerating said aqueous admixture and producing a regenerated aqueous oxidizing reactant solution containing solid sulfur; (c) separating regenerated oxidizing reactant solution containing solid sulfur into a regenerated aqueous reaction solution having reduced sulfur content and an aqueous reactant slurry containing increased sulfur content, and returning the regenerated aqueous reaction solution to the contacting zone; (d) concomitantly recovering solid sulfur containing residual aqueous admixture from aqueous reactant slurry from step (c); (e) washing solid sulfur from step (d) with an aqueous washing liquid and producing improved sulfur and an aqueous solution containing the polyvalent metal chelate of nitrilotriacetic acid, or mixtures thereof; (f) contacting aqueous solution produced in step (e) with sufficient acid selected from the group consisting of HCl, H 2 SO 4 , H 3 PO 4 , and mixtures thereof, to dissociate at least the bulk of the polyvalent metal chelate or chelates in solution and under conditions to precipitate a solid containing nitrilotriacetic acid, and precipitating and recovering said solid.

Claim 15

The process of claim 10 wherein the oxidizing reactant is the Fe+++ chelate of nitrilotriacetic acid.

Claim 16

The process of claim 10 wherein the solid precipitated is neutralized with a basic material selected from alkali metal hydroxides and ammonium hydroxide.