Method of removing hydrogen sulfide from gases utilizing a stabilized iron chelate solution

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 solution containing an effective amount of a reactant selected from the group consisting of oxidizing iron chelate compounds, and mixtures thereof, and a stabilizing amount of a composition selected from the group consisting of sodium thiocyanate, sodium dithionite, and mixtures thereof, and producing a sweet gas stream and an aqueous admixture containing crystalline sulfur and a reduced reactant; (b) removing at least a portion of the crystalline sulfur from the aqueous admixture; (c) regenerating the aqueous admixture in a regeneration zone to produce a regenerated reactant; (d) returning aqueous admixture containing regenerated reactant from the regeneration zone to the contacting zone.

Claim 3

The process of claim 1 wherein the stream from which the H 2 S is removed is selected from naturally-occurring gases, synthesis gases, process gases and fuel gas.

Claim 4

The process of claim 1 wherein the sour gaseous stream is selected from natural gas, a stream derived from the gasification of coal, or a hydrocarbon stream.

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 solution containing an effective amount of a reactant selected from the group consisting of oxidizing iron chelate compounds, and mixtures thereof, and a stabilizing amount of a composition selected from the group consisting of sodium thiocyanate, sodium dithionite, and mixtures thereof, and producing a sweet gas stream and an aqueous admixture crystalline sulfur and a reduced reactant; (b) regenerating the aqueous admixture in a regeneration zone to produce an aqueous admixture containing a regenerated reactant; (c) removing at least a portion of the crystalline sulfur from aqueous admixture from step (b) to produce an aqueous admixture having reduced sulfur content. (d) returning aqueous admixture having reduced sulfur content to the contacting zone.

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 solution containing an effective amount of a reactant selected from the group consisting of oxidizing iron chelate compounds, and mixtures thereof, and a stabilizing amount of a composition selected from the group consisting of sodium thiocyanate, sodium dithionite, and mixtures thereof, and producing a sweet gas stream and an aqueous admixture crystalline sulfur and a reduced reactant; (b) regenerating the aqueous admixture in a regeneration zone to produce an aqueous admixture containing a regenerated reactant; (c) removing at least a portion of the crystalline sulfur from aqueous admixture from step (b) to produce an aqueous admixture having reduced sulfur content. (d) returning aqueous admixture having reduced sulfur content to the contacting zone.

Claim 7

The process of claim 4 wherein the stream from which the H 2 S is removed is selected from naturally-occurring gases, synthesis gases, process gases and fuel gas.

Claim 8

The process of claim 4 wherein the sour gaseous stream is selected from natural gas, a stream derived from the gasification of coal, or a hydrocarbon stream.

Claim 9

A process for the removal of H 2 S and CO 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 2 -selective absorbent mixture containing an effective amount of a reactant selected from the group consisting of oxidizing iron chelate compounds, and mixtures thereof, and a stabilizing amount of a composition selected from the group consisting of sodium thiocyanate, sodium dithionite, and mixtures thereof, and producing a sweet gaseous stream and an absorbent admixture containing absorbed CO 2 , crystalline sulfur, and reduced reactant; (b) removing at least a portion of the crystalline sulfur from the absorbent admixture, and leaving a solution containing absorbed CO 2 and reduced reactant; (c) stripping the solution containing absorbed CO 2 and said reduced reactant to remove CO 2 , and regenerating said solution, producing a lean CO 2 -selective absorbent solution regenerated reactant; and (d) returning lean CO 2 -selective absorbent solution containing regenerated reactant to the contacting zone.

Claim 10

A process for the removal of H 2 S and CO 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 2 -selective absorbent mixture containing an effective amount of a reactant selected from the group consisting of oxidizing iron chelate compounds, and mixtures thereof, and a stabilizing amount of a composition selected from the group consisting of sodium thiocyanate, sodium dithionite, and mixtures thereof, and producing a sweet gaseous stream and an absorbent admixture containing absorbed CO 2 , crystalline sulfur, and reduced reactant; (b) removing at least a portion of the crystalline sulfur from the absorbent admixture, and leaving a solution containing absorbed CO 2 and reduced reactant; (c) stripping the solution containing absorbed CO 2 and said reduced reactant to remove CO 2 , and regenerating said solution, producing a lean CO 2 -selective absorbent solution regenerated reactant; and (d) returning lean CO 2 -selective absorbent solution containing regenerated reactant to the contacting zone.

Claim 11

A process for the removal of H 2 S and CO 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 2 -selective absorbent mixture containing an effective amount of a reactant selected from the group consisting of oxidizing iron chelate compounds, and mixtures thereof, and a stabilizing amount of a composition selected from the group consisting of sodium thiocyanate, sodium dithionite, and mixtures thereof, and producing a sweet gaseous stream and an absorbent mixture containing absorbed CO 2 , crystalline sulfur, and reduced reactant; (b) stripping the absorbent mixture containing absorbed CO 2 , crystalline sulfur, and said reduced reactant, and regenerated said absorbent mixture, producing a lean CO 2 -selective absorbent solution containing a regenerated reactant and sulfur, (c) removing at least a portion of the crystalline sulfur from the lean CO 2 -selective absorbent solution containing the sulfur and the regenerated reactant, and leaving a lean CO 2 -selective absorbent solution containing regenerated reactant, and (d) returning lean CO 2 -selective absorbent solution containing regenerated reactant to the contacting zone.

Claim 12

A process for the removal of H 2 S and CO 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 2 -selective absorbent mixture containing an effective amount of a reactant selected from the group consisting of oxidizing iron chelate compounds, and mixtures thereof, and a stabilizing amount of a composition selected from the group consisting of sodium thiocyanate, sodium dithionite, and mixtures thereof, and producing a sweet gaseous stream and an absorbent mixture containing absorbed CO 2 , crystalline sulfur, and reduced reactant; (b) stripping the absorbent mixture containing absorbed CO 2 , crystalline sulfur, and said reduced reactant, and regenerated said absorbent mixture, producing a lean CO 2 -selective absorbent solution containing a regenerated reactant and sulfur, (c) removing at least a portion of the crystalline sulfur from the lean CO 2 -selective absorbent solution containing the sulfur and the regenerated reactant, and leaving a lean CO 2 -selective absorbent solution containing regenerated reactant, and (d) returning lean CO 2 -selective absorbent solution containing regenerated reactant to the contacting zone.

Claim 13

The process of claim 2 wherein the iron chelate compound is the Fe (III) chelate of nitrilotriacetic acid.

Claim 14

The process of claim 2 wherein the iron chelate compound is the Fe (III) chelate of N-(2-hydroxyethyl)ethylenediamine triacetic acid.

Claim 15

The process of claim 3 wherein the iron chelate compound is the Fe (III) chelate of nitrilotriacetic acid.

Claim 16

The process of claim 3 wherein the iron chelate compound is the Fe (III) chelate of N-(2-hydroxyethyl)ethylenediamine triacetic acid.

Claim 17

The process of claim 5 wherein the iron chelate compound is the Fe (III) chelate of nitrilotriacetic acid.

Claim 18

The process of claim 5 wherein the iron chelate compound is the Fe (III) chelate of N-(2-hydroxyethyl)ethylenediamine triacetic acid.

Claim 19

The process of claim 6 wherein the iron chelate compound is the Fe (III) chelate of nitrilotriacetic acid.

Claim 20

The process of claim 6 wherein the iron chelate compound is the Fe (III) chelate of N-(2-hydroxyethyl)ethylenediamine triacetic acid.

Claim 21

The process of claim 7 wherein the stream from which the H 2 S is removed is selected from naturally-occurring gases, synthesis gases, process gases and fuel gas.

Claim 22

The process of claim 7 wherein the sour gaseous stream is selected from natural gas, a stream derived from the gasification of coal, or a hydrocarbon stream.

Claim 23

The process of claim 17 wherein the iron chelate compound is the Fe (III) chelate of nitrolotriacetic acid.

Claim 24

The process of claim 17 wherein the iron chelate compound is the Fe (III) chelate of N-(2-hydroxyethyl)ethylenediamine triacetic acid.

Claim 25

The process of claim 18 wherein the iron chelate compound is the Fe (III) chelate of nitrilotriacetic acid.

Claim 26

The process of claim 18 wherein the iron chelate compound is the Fe (III) chelate of N-(2-hydroxyethyl)ethylenediamine triacetic acid.

Claim 27

The process of claim 8 wherein the sour gaseous stream is selected from natural gas, a stream derived from the gasification of coal, or a hydrocarbon stream.

Claim 28

The process of claim 8 wherein the sour gaseous stream is selected from natural gas, a stream derived from the gasification of coal, or a hydrocarbon stream.

Claim 29

The process of claim 23 wherein the iron chelate is the Fe (III) chelate of nitrilotriacetic acid.

Claim 30

The process of claim 23 wherein the iron chelate compound is the Fe (III) chelate of N-(2-hydroxyethyl)ethylenediamine triacetic acid.

Claim 31

The process of claim 24 wherein the iron chelate compound is the Fe (III) chelate of nitrilotriacetic acid.

Claim 32

The process of claim 24 wherein the iron chelate compound is the Fe (III) chelate of N-(2-hydroxyethyl)ethylenediamine triacetic acid.