MXPA98001721A - Sulfur recovery process using a azu disliaging agent - Google Patents

Abstract

The recovery of an insoluble polymer sulfur species from the reaction solution of a hydrogen sulfide conversion process is improved by adding a sulfur release agent to the hydrogen sulphide conversion reaction solution either at the initiation of the process or after the conversion of hydrogen sulfide. The conversion of hydrogen sulfide initially produces a soluble complex having the polymeric sulfur bound thereto. The sulfur release agent disintegrates the soluble complex to produce an insoluble polymer species easily separable from the reaction solution by conventional physical means in order to obtain the desired sulfur product.

Description

"SULFUR RECOVERY PROCESS USING A SULFUR DEFLECTION AGENT" BACKGROUND OF THE INVENTION TECHNICAL FIELD The present invention relates generally to a process for converting hydrogen sulfide to sulfur and hydrogen and, more particularly, to a process for improving the recovery of sulfur from the reaction solution of a hydrogen sulfide conversion process, wherein Hydrogen sulfide is converted to sulfur and hydrogen by contacting it with a quinone and an H2S complex-forming agent in solution.

INFORMATION FROM THE BACKGROUND The conversion of hydrogen sulfide to sulfur and hydrogen by contacting hydrogen sulphide with a selected anthraquinone in solution is generally known. For example, the following publications disclose processes for recovering sulfur and hydrogen from a gas stream containing hydrogen sulfide and, as such, are incorporated herein by reference: 1) Plummer, "Sulfur and Hydrogen from H2S", Hydrocarbon Processing, April 1987; 2) U.S. Patent Number 4,592,905 issued to Plummer et al., And 3) U.S. Patent Number 5,334,363 issued to Plummer. In accordance with each of the prior art processes listed above, the hydrogen sulfide contained in a gas stream, such as a hydrocarbon refinery waste gas, is dissolved in a reaction solution having a solvent appropriate and a selected anthraquinone dissolved therein. Hydrogen sulfide and anthraquinone react in solution to produce insoluble sulfur, and the corresponding anthraquinone anthraquinone. The insoluble sulfur is recovered from the reaction solution as a solid or liquid product of commercial quality. The anthrahydroquinone is dehydrogenated with a selected catalyst, regenerating the anthraquinone for recycling to the hydrogen sulfide reaction, while producing hydrogen gas as a beneficial product. The hydrogen sulphide conversion process of US Pat. No. 5,334,363 discloses the addition of an H2S complex forming agent in the reaction solution to stimulate the conversion of anthraquinone and hydrogen sulfide to the corresponding anthrahydroquinone and sulfur. Unfortunately, the increased conversion regimes of anthraquinone and hydrogen sulfide are not translated to the increased sulfur recoveries because the H 2 S complex forming agent and the anthrahydroquinone undesirably retain the sulfur resulting in solution, after the production thereof. , forming a soluble complex with sulfur. Thus, there is a need for a means to increase the sulfur yields in the above-described hydrogen sulphide conversion process. Accordingly, an object of the present invention is to provide a hydrogen sulfide conversion process having increased sulfur yields. In particular, an object of the present invention is to provide a means for improving the removal of sulfur from the reaction solution of a hydrogen sulfide conversion process. More particularly, it is an object of the present invention to provide a means for disintegrating a soluble sulfur-containing complex in the reaction solution of a hydrogen sulphide conversion process in order to recover the insoluble sulfur therefrom. A further object of the present invention is to provide a means for improving the removal of the sulfur from the reaction solution of a hydrogen sulfide conversion process, without considerably reducing the conversion rate of the hydrogen sulfide thereof.

These objects and others are achieved in accordance with the invention which will be described below.

COMPENDIUM OF THE INVENTION The present invention is a process for improving the sulfur yields of a hydrogen sulfide conversion process and, more particularly, a process for improving the recovery of a polymeric sulfur species from the reaction solution of a hydrogen sulfide conversion process. According to one embodiment of the invention, the sulfur recovery process is integral with the hydrogen sulphide conversion process and comprises preparing a reaction solution containing an H2S complex-forming agent, a quinone, a release agent of Sulfur and a polar organic solvent. The reaction solution is contacted with a gas stream containing hydrogen sulfide and the hydrogen sulfide is reacted with the H2S complexing agent and the quinone therein to produce a species of polymeric sulfur and a hydroquinone which corresponds to the quinone. The polymeric sulfur species remains dissolved in the reaction solution as a complex containing soluble sulfur with the H2S complex-forming agent and the hydroquinone. However, the sulfur release agent is more intimately bound to the H 2 S complex-forming agent than the polymeric sulfur species. Consequently, the sulfur release agent reacts with the complex to disintegrate it, releasing the polymeric sulfur species, hydroquinone and complex H2S complexing agent from the complex. The resulting free polymeric sulfur species, which is insoluble in the reaction solution, is separated therefrom by conventional physical means to obtain the desired sulfur product. The hydroquinone retained within the reaction solution is dehydrogenated catalytically to regenerate the quinone and produce hydrogen gas. The reaction solution having the regenerated quinone dissolved therein is recycled back to the hydrogen sulphide conversion reactor. In accordance with an alternative embodiment of the invention, the sulfur recovery process is a discrete step of the hydrogen sulphide conversion process. The hydrogen sulphide conversion process is carried out essentially in the same manner as the above-described embodiment, but the sulfur release agent is not initially added to the reaction solution containing the H2S complex-forming agent, the quinone and the solvent. The discrete sulfur recovery process is carried out by adding the sulfur release agent to the reaction solution only after the reaction solution has been contacted with the gas stream containing hydrogen sulfide to form the species of polymeric sulfur as a complex with the H2S complex-forming agent and the hydroquinone. The remainder of the hydrogen sulphide conversion process is carried out essentially in the same manner as above, by disintegrating the complex, removing the free polymer sulfur species, and regenerating the quinone in the reaction solution. The invention will be further comprised of the accompanying drawing and the description.

BRIEF DESCRIPTION OF THE DRAWING The Figure is a graphic illustration of the recovery of sulfur as a function of the sulfur release agent pKa.

DESCRIPTION OF THE PREFERRED MODALITIES The present invention is a sulfur recovery process that is practiced integrally in association with a hydrogen sulfide (H2S) conversion process. In accordance with the H2S conversion process that incorporates the sulfur recovery process therein, a selected quinone, an H2S complex forming agent and a sulfur release agent are dissolved in a selected polar organic solvent to form a solution of reaction. The concentration of the selected quinone in the reaction solution is between about 1 percent and about 80 percent by weight, and preferably between about 5 percent to about 50 percent by weight. The molar ratio of the H 2 S complexing agent to the selected quinone in the reaction solution is between about 1:50 and about 2: 1, and preferably between about 1:10 and about 1: 1. The molar ratio of the sulfur release agent to the total quinone in the reaction solution is between about 1:50 and about 2: 1, and preferably between about 1:10 and about 1: 1. The total quinone is defined herein as the sum of the selected quinone and any hydroquinone present in the reaction solution. Suitable polar organic solvents are compounds having a polarity greater than about 3 Debye units and include N-methyl-2-pyrrolidinone, N, N-dimethylacetamide, N, N-dimethylformamide, sulfolane (tetrahydrothiophen-1, 1-dioxide), acetonitrile, 2-nitropropane, propylene carbonate and mixtures thereof. N-methyl-2-pyrrolidinone (NMP) is preferred among these solvents. Appropriate selected quinones include anthraquinones, benzoquinones, naphtaquinones, and mixtures thereof. Preferred selected quinones are those that have relatively high solubilities in the polar organic solvents listed above, and include anthraquinones such as ethyl anthraquinone, tertiary butyl anthraquinone, tertiary amyl anthraquinone, secondary amyl anthraquinone or mixtures thereof. Suitable H 2 S-complexing agents are compounds having a pK at 25 ° C of less than about 13, preferably less than about 9.5, and most preferably less than about 6.0. Compounds that meet these criteria include amines, amides, ureas, nitrogen-containing heterocyclic aromatics, guanidines, imidazoles, and mixtures thereof. The aforementioned H2S complexing agents can also be substituted with alkyl, aryl and organic alcohol groups. Specific examples of suitable H2S complexing agents are n-methylacetamide, pyridine (PY), substituted pyridines, diethylmethylamine (DEMA), tributylamine (TBA), tri-propylamine (TPA), methyldiethanolamine (MDEA) and tetramethylurea. Preferred among these H2S complexing agents are DEMA, TBA, PY, and substituted pyridines. Suitable sulfur cleavage agents are compounds having a pKa at 25 ° C of less than about 5, preferably less than about 3, and more preferably less than about 2. Compounds that meet these criteria are typically acidic. organic or inorganic containing one or more acid groups. Non-aqueous acids are preferred to aqueous acids since it is desirable to control the water content of the reaction solution, within parameters defined in accordance with the teachings of U.S. Patent Number 5,334,363. Specific examples of suitable acids include trifluoroacetic acid, sulfamic acid, malonic acid, oxalic acid and mixtures thereof. The reaction solution, containing the selected solvent, the quinone, the complexing agent H2S, the sulfur release agent is fed to an H2S conversion reactor together with a stream of feed gas containing the H2S gas. If the feed gas stream also contains large amounts of other gases that are inert to the process, such as nitrogen, carbon dioxide, ammonia, methane or other - lo ¬ Low molecular weight hydrocarbon gases, the feed gas stream is initially contacted with the reaction solution in an absorber in front of the H2S conversion reactor. In any case, the reaction solution preferably solubilizes the H2S in the feed gas stream during its contact. The reaction solution is maintained in the H 2 S conversion reactor at a temperature from about 0 ° C to about 70 ° C, a partial pressure of H 2 S from about 0.05 to about 4.0 atmospheres, and for a sufficient period of time to convert the H2S and quinone reagents in the reaction solution in polymeric sulfur and hydroquinone products. In the course of the conversion reaction, it is believed that the H 2 S-complexing agent advantageously induces the formation of complexes which serve as intermediates in the conversion of H 2 S to polymeric sulfur and hydroquinone products. During the conversion of the reactants, the reaction solution contains the hydroquinone and the polymeric sulfur products in addition to the unreacted constituents including the sulfur release agent, the polar organic solvent, the H2S complex-forming agent, any unreacted quinone , and any of the unreacted constituents of the feed gas stream. Even when the polymeric sulfur produced by the conversion process is desirably in the form of a species of free insoluble polymeric sulfur, having the formula Sg, which is easily separable from the reaction solution by conventional physical means, such as filtration or centrifugation , the polymeric sulfur produced by the present conversion process is more commonly in the form of a polymeric species formed into a complex having the formula Sx, where x is between 2 and 30 inclusive. Since the polymeric sulfur species, Sx, is linked by either the H2S complex-forming agent or the hydroquinone or both, in a complex containing soluble sulfur, the polymeric sulfur species in complex form is not readily susceptible to Removal of the reaction solution by conventional physical means. Consequently, the sulfur release agent is reacted with the complex containing the soluble sulfur in the reaction solution to release the polymeric sulfur species formed in complex from the complex. The sulfur debinding reaction is carried out at a temperature between about 0 ° C and about 70 ° C, and preferably between about 20 ° C and about 60 ° C. The sulfur cleavage reaction disintegrates the complex to produce a free polymeric sulfur species having the formula Sg, while also releasing the H2S complex forming agent and hydroquinone. Because the species of the free polymeric sulfur, Sg, is insoluble in the reaction solution, it can be easily removed therefrom by conventional physical means such as centrifugation or filtration in order to obtain the final sulfur product. The remainder of the reaction solution, containing the polar organic solvent, the hydroquinone, the H2S complex-forming agent, the sulfur-releasing agent, any unreacted quinone and any of the unreacted constituents of the feed gas stream, such as H2S and carbon dioxide, is removed from the H2S conversion reactor, heated to a temperature of from about 70 ° C to about 150 ° C and preferably from about 90 ° C to about 100 ° C, at a pressure of about 0.01 to about 2 atmospheres, and preferably from about 0.1 to about 1.0 atmosphere and is fed to an instant evaporation tank. The constituents of the unreacted feed gas, if any, are recovered from the reaction solution in the flash tank and recycled to the H2S conversion reactor., if desired, either a portion or all of the sulfur release agent and the H2S complex forming agent can also be recovered from the reaction solution at this point and recycled into the H2S conversion reactor with the feed gas constituents unreacted, if desired. The remaining reaction solution containing the solvent and the hydroquinone, as well as any unreacted quinone, if any, is removed from the flash tank and preferably further heated to a temperature of about 150 ° C to about 350 °. C, at a pressure at least sufficient to prevent boiling of the solvent. The heated reaction solution is then fed to a dehydrogenation reactor where the hydroquinone is catalytically converted to quinone and hydrogen gas under the aforementioned temperature and pressure conditions, in a manner known to a person skilled in the art. The reaction solution containing the resulting quinone, in addition to any H 2 S-complexing agent without recovering previously and the sulfur debinding agent, is recycled to the H 2 S conversion reactor and hydrogen is recovered as a product gas. In an alternative embodiment, the present invention is a sulfur recovery process applied to the reaction solution of an H2S conversion process as a discrete stage thereof. According to this embodiment, the selected quinone and the H 2 S complex forming agent are dissolved in the selected polar organic solvent, and the resulting reaction solution is contacted with the gas stream containing H 2 S in essentially the same way as described above, but in the absence of the sulfur release agent. During the formation of the soluble complex containing the polymeric sulfur species, hydroquinone, and the H2S complex-forming agent, the sulfur recovery step of the H2S conversion process is initiated by adding the sulfur release agent to the sulfur solution. reaction. As in the above embodiment, the reaction between the complex and the sulfur release agent disintegrates the complex to produce the free insoluble polymeric sulfur species, while releasing the H 2 S complex-forming agent and the hydroquinone. The free polymeric sulfur species is separated from the reaction solution by conventional physical means to obtain the final sulfur product, thereby completing the sulfur recovery step. The H2S conversion process continues as before catalytically dehydrogenating the hydroquinone species to regenerate the quinone to be recycled to the H2S conversion reactor.

Although the present invention is not restricted to any specific mechanism, it is believed that the complex formed by the H2S conversion process has the general formula: (H2S complex forming agent) -Sx- (hydroquinone); where x = 2 to 30 The sulfur release agent binds more favorably to the H2S complex forming agent than the polymeric sulfur species, Sx, thereby disintegrating the complex by displacing the H2S complex forming agent and the hydroquinone thereof to obtain the polymeric species insoluble free, Sg. The ability of the sulfur release agent to displace the complexing agent H2S and the hydroquinone of the complex is a function of the acid resistance of the sulfur release agent which is expressed in terms of kPa at 25 ° C. The ability of the sulfur release agent to disintegrate the complex is also believed to be a function of spherical factors, since the sulfur release agent preferably has a spatial configuration that favors the bond with the H2S complex-forming agent.

The present invention has been described above, wherein the H 2 S complex-forming agent and the sulfur-release agent are separate and distinct compounds. It is within the scope of the present invention, however, to provide a single amphoteric compound that functions both as an H2S complex forming agent and a sulfur release agent. An appropriate amphoteric H 2 S complex forming agent and a sulfur release agent have a base group with a pK at 25 ° C of less than about 13, preferably less than about 9.5, and more preferably less than about 6.0 The appropriate amphoteric and sulfur-cleaving H2S complex forming agent also has an acidic group with a pKa at 25 ° C of less than about 5, preferably less than about 3, and especially preferably less than about 2. An exemplary amphoteric and sulfur-releasing H2S complex forming agent is aminobenzoic acid, which has a base group with a pKa of 9.2 at 25 ° C and an acid group with a pKa of 2.4 at 25 ° C. Another exemplary amphoteric and sulfur-cleaving H2S complex forming agent is 1-nicotinic acid, which has a base group with a pK ^ of 9.1 at 25 ° C and an acid group with a pKa of 1.8 at 25 ° C. .

The following examples demonstrate the practice and utility of the present invention, but should not be construed as limiting the scope thereof.

Example 1 A reaction solution containing a solvent of N-methyl-2-pyrrolidinone (NMP), t-butylanthraquinone (TBAQ) and diethylmethylamine (DEMA) is prepared as the H2S complex-forming agent. The reaction solution is contacted at 60 ° C and 1.5 atmospheres with a stream of H2S gas in an H2S conversion reactor, thereby converting the reaction solution into the following composition, wherein the t-butylanthroquinone is designated as HTBAQH and TBAQ + HTBAQH is designated as TAQ:% by weight TAQ 23.61 NMP 70.83 Water (1.0 mole of water / mole of TAQ) 1.52 DEMA (0.275 mole of DEMA / mole of TAQ) 2.03 Dissolved Polymer Sulfur 2.01 Total 100.00 The HTBAQH It comprises 75.7 mole percent of TAQ in the solution.

A trifluoroacetic acid sulfur release agent is then added to the reaction solution at 22 ° C in a concentration of 1.0 mol per mole of HTBAQH. Trifluoroacetic acid has a pKa of 0.23 at 25 ° C. The trifluoroacetic acid is mixed well in the reaction solution and the reaction solution is then stored for 30 minutes at the above-mentioned temperature. The reaction solution is filtered to remove the precipitated Sg. The amount of the precipitated Sg is determined as being 90.6 weight percent of the polymeric sulfur dissolved in the reaction solution, before the addition of the sulfur release agent.

Example 2 The procedure of Example 1 is repeated with the exception that the sulfur release agent is sulfamic acid. Sulfamic acid has a pKa of 0.99 at 25 ° C. The amount of Sg precipitated is determined as being 64.0 weight percent of the polymeric sulfur dissolved in the reaction solution, before the addition of the sulfur release agent.

Example 3 The procedure of Example 1 is repeated with the exception that the sulfur release agent is acetic acid. Acetic acid has a pKa of 4.76 at 25 ° C. Sg is not recovered from the reaction solution.

Example 4 The procedure of Example 1 is repeated with the exception that the sulfur release agent is hydrochloric acid. The hydrochloric acid which is at 37 weight percent and has a pKa of 0.00 to 25 ° C, dissolves in water. The amount of the precipitated Sg is determined as being 100.0 weight percent of the polymeric sulfur dissolved in the reaction solution before the addition of the sulfur release agent. The sulfur release agents of Examples 1 to 4 are all mono-acids, and will function satisfactorily with the exception of acetic acid. It should be noted, however, that aqueous hydrochloric acid is less preferred than trifluoroacetic acid or sulfamic acid for commercial applications due to the high water content of aqueous hydrochloric acid.

Example 5 A reaction solution containing a solvent of NMP, TBAQ, DEMA and tri-propylamine (TPA) is prepared as an additional H2S complexing agent. The reaction solution is contacted with the H2S gas stream in an H2S conversion reactor in the manner of Example 1, thereby converting the reaction solution into the following composition: % by weight TAQ 23.04 NMP 70.60 Water (1.23 moles' of water / mole of TAQ) 1.92 TPA (0.126 mole of TPA / mole of TAQ) 2.02 DEMA (0.04 mole of DEMA / mole of TAQ) 0.30 Dissolved Polymer Sulfur 2.12 Total 100.00 The HTBAQH comprises 74.5 mole percent of TAQ in the solution. An oxalic acid sulfur release agent is added to the reaction solution at 22 ° C in a concentration of 1.0 mol per mole of HTBAQH. Oxalic acid has a pKa of 1.27 at 25 ° C. The oxalic acid is mixed well in the reaction solution and the reaction solution is then stored for 30 minutes at the above-mentioned temperature. The reaction solution is then filtered to remove the precipitated Sg. The amount of the precipitated Sg is determined as being 100.0 weight percent of the polymeric sulfur dissolved in the solution in the reaction, before the addition of the sulfur release agent.

Example 6 The procedure of Example 5 is repeated with the exception that the sulfur release agent is malonic acid. Malonic acid has a pKa of 2.85 at 25 ° C. The amount of the precipitated Sg is determined as being 74.9 weight percent of the polymeric sulfur dissolved in the reaction solution, before the addition of the sulfur release agent. The sulfur release agents of Examples 5 and 6 are dicarboxylic acids and both function satisfactorily.

Example 7 A reaction solution containing a solvent of NMP, TBAQ and pyridine (PY) is prepared as the H2S complex-forming agent. The reaction solution is contacted with a stream of H 2 S gas in the H 2 S conversion reactor in the manner of Example, thereby converting the reaction solution into the following composition: % by weight TAQ 22.73 NMP 68.16 Water (1.23 moles of water / mole of TAQ) 1.90 PY (1.00 mole of PY / mole of TAQ 6.80 Dissolved Polymer Sulfur 0.39 Total 100.00 The HTBAQH comprises 57.5 mole percent of TAQ in the solution. Add a malonic acid sulfur release agent to the reaction solution at 22 ° C in a concentration of 0.97 mol per mole of HTBAQH The oxalic acid has a pKa of 2.85 at 25 ° C. The malonic acid mixes well in the reaction solution and the reaction solution are then stored for 30 minutes at the above-mentioned temperature The reaction solution is then filtered to remove the precipitated Sg The amount of Sg precipitated is detrmined as being 77.6 weight percent of the polymeric sulfur dissolved in the reaction solution, before the addition of the sulfur release agent.

Example 8 The procedure of Example 7 is repeated with the exception that the sulfur debinding agent is oxalic acid in a concentration of 0.56 mol per mol of HTBAQH. Oxalic acid has a pKa of 1.27 at 25 ° C. The amount of Sg precipitated is determined as being 100.0 weight percent of the polymeric sulfur dissolved in the reaction solution, before the addition of the sulfur release agent. The results of Examples 1 to 8 are presented in the Figure, where it is demonstrated that the effectiveness of the sulfur release agent is correlated with its pKa with the effectiveness of the sulfur release agent increasing with the pKa decreased or the acidity increased of the sulfur release agent. It is further demonstrated that the sulfur release agents contain two acid functions that are more effective than the sulfur release agents that contain only one acid function.

Example 9 A reaction solution containing a solvent of NMP, TBAQ and DEMA is prepared as the H2S complex-forming agent. The reaction solution has the following composition: I < sn weight TAQ 24. 30 NMB 72. 89 Water (1.0 mole of water / mole of TBAQ) 1. 65 DEMA (0.144 mol DEMA / mol of TBAQ) 1. 1 6 Total 00. 00 The reaction solution is contacted with one mole of H 2 S per mole of TBAQ at 20 ° C and 0.8 atmosphere in an H2S conversion reactor. After 24 hours, the reaction solution is filtered to remove the precipitated Sg. The conversion of TBAQ to HTBAQH is determined to be 91.6 mole percent and recovery of Sg is determined to be 16.6 weight percent of the total polymeric sulfur produced in the H2S conversion reactor.

Example 10 The procedure of Example 9 is repeated with the exception that a trifluoroacetic acid sulfur binding agent is added to the reaction solution at a concentration of 0.11 mol per mole of TBAQ, before the reaction solution is brought into contact with H2S. The conversion of TBAQ to HTBAQH is determined to be 89.9 mole percent and recovery of Sg is determined to be 73.1 mole percent of the total polymeric sulfur produced in the H2S conversion reactor. A comparison of Examples 9 and 10 shows that the use of a sulfur debulking agent in accordance with the present invention increases the recovery of Sg.

Example 11 A reaction solution containing a solvent of NMP, TBAQ and PY is prepared as the H2S complex-forming agent. The reaction solution has the following composition: or by weight TBAQ 23.26 NMP 69.78 PY (1.00 mol of PY / ol of TBAQ) 6.96 Total 100.00 The reaction solution is contacted with one mole of H 2 S per mole of TBAQ at 20 ° C and 0.8 atmosphere in an H2S conversion reactor. After 24 hours, the reaction solution is filtered to remove the precipitated Sg. The conversion of TBAQ to HTBAQH is determined to be 90.0 mole percent and recovery of Sg is determined as being 79.1 weight percent of the total polymeric sulfur produced in the H2S conversion reactor.

Example 12 The procedure of Example 11 is repeated with the exception that a malonic acid sulfur debinding agent is added to the reaction solution at a concentration of 0.55 mol per mole of TBAQ, before the reaction solution is brought into contact with the H2S. The conversion of TBAQ to HTBAQH is determined to be 79.5 mole percent and recovery of Sg is determined to be 91.8 weight percent of the total polymeric sulfur produced in the H2S conversion reactor. A comparison of Examples 11 to 12 shows that the use of the sulfur release agent according to the present invention increases the recovery of Sg. Examples 1 to 8 demonstrate a previously described embodiment of the present invention, wherein the sulfur release agent is added to the reaction solution after conversion of TBAQ to H2S. Examples 10 and 12 demonstrate another previously described embodiment of the present invention, wherein the sulfur release agent is incorporated into the initial reaction solution containing TBAQ and the H2S complex-forming agent before the conversion of TBAQ into H2S. The comparison of Examples 1 to 6 with Examples 7 and 8 demonstrates that the sulfur debonding agents are effective in the presence of both the high basicity H2S complexing agents (DEMA and TPA) and the H 2 S complex-forming agents of low basicity (PY). Comparison of Examples 9 and 10 with Examples 11 and 12 demonstrates the same result. Although the above preferred embodiments of the invention have been described and shown, it will be understood that alternatives and modifications, such as those suggested and others, may be made therein and are within the scope of the present invention.

Claims (36)

CLAIMS:

1. A process for converting the hydrogen sulfide gas into a species of polymeric sulfur comprising: providing a reaction solution containing an H2S complex-forming agent and a quinone; contacting the reaction solution with the hydrogen sulfide gas; reacting the hydrogen sulfide gas with the H2S-complexing agent and the quinone, in order to produce a soluble sulfur-containing constituent dissolved in the reaction solution; add a sulfur release agent to the reaction solution; reacting the sulfur release agent with the soluble sulfur-containing constituent to produce a species of free polymeric sulfur insoluble in the reaction solution; and separating the species of free polymeric sulfur from the reaction solution.

2. The process of claim 1, further comprising converting the quinone to a corresponding hydroquinone.

3. The process of claim 1, wherein the sulfur release agent has a pKa less than about 5 to about 25 ° C.

4. The process of claim 1, wherein the sulfur release agent has a pKa of less than about 3 to about 25 ° C.

The process of claim 1, wherein the sulfur release agent has a pKa of less than about 2 to about 25 ° C.

6. The process of claim 1, wherein the sulfur release agent is a mono-acid or a poly-acid.

The process of claim 1, wherein the sulfur release agent is selected from the group consisting of trifluoroacetic acid, sulphamic acid, malonic acid, oxalic acid, and mixtures thereof.

The process of claim 2, wherein the sulfur release agent and the total quinone consisting of the quinone and hydroquinone which are contained in the reaction solution in a molar ratio between about 1:50 and about 2: 1.

9. The process of claim 1, wherein the sulfur debonding agent is reacted with the constituent containing the soluble sulfur at a temperature between about 0 ° C and about 70 ° C.

The process of claim 1, wherein the H 2 S complex forming agent and the quinone are contained in the reaction solution in a molar ratio between about 1:50 and about 2: 1.

The process of claim 1, wherein the H 2 S complex-forming agent is selected from the group consisting of amines, amides, ureas, nitrogen-containing heterocyclic aromatics, guanidines, imidazoles and mixtures thereof, and amines, amides, ureas, nitrogen-containing heterocyclic aromatics, imidazole guanidines and mixtures thereof, substituted with alkyl, aryl or organic alcohol groups.

The process of claim 1, wherein the H 2 S complex-forming agent has a pK ^ less than about 13 to about 25 ° C.

The process of claim 1, wherein the H 2 S complex-forming agent has a pK ^ less than about 9.5 to about 25 ° C.

The process of claim 1, wherein the H2S complex-forming agent has a pK ^ less than about 6.0, at about 25 ° C.

15. A process for converting the hydrogen sulfide gas to a species of polymeric sulfur comprising: providing a reaction solution containing an H2S complex-forming agent, a quinone and a sulfur release agent; contacting the reaction solution with the hydrogen sulfide gas; reacting the hydrogen sulfide gas with the H2S-complexing agent and the quinone, in order to produce a soluble sulfur-containing constituent dissolved in the reaction solution; reacting the sulfur release agent with the soluble sulfur-containing constituent to produce a species of free polymeric sulfur insoluble in the reaction solution; and separating the species of free polymeric sulfur from the reaction solution.

16. The process of claim 15, further comprising converting the quinone to a corresponding hydroquinone.

The process of claim 15, wherein the sulfur release agent has a pKa of less than about 5, at about 25 ° C.

18. The process of claim 15, wherein the sulfur release agent has a pKa of less than about 3, at about 25 ° C.

The process of claim 15, wherein the sulfur release agent has a pKa of less than about 2, at about 25 ° C.

The process of claim 15, wherein the sulfur release agent is a mono-acid or a poly-acid.

21. The process of claim 15, wherein the sulfur release agent is selected from the group consisting of trifluoroacetic acid, sulphamic acid, malonic acid, oxalic acid, and mixtures thereof.

22. The process of claim 16, wherein the sulfur release agent and the total quinone consisting of the quinone and hydroquinone are contained in the reaction solution in a molar ratio of between about 1:50 and about 2: 1. .

23. The process of claim 15, wherein the sulfur release agent is reacted with the soluble sulfur-containing constituent at a temperature between about 0 ° C and about 70 ° C.

The process of claim 15, wherein the H 2 S complex forming agent and the quinone are contained in the reaction solution in a molar ratio of between about 1:50 and about 2: 1.

The process of claim 15, wherein the H 2 S complex-forming agent is selected from the group consisting of amines, amides, ureas, nitrogen-containing heterocyclic aromatics, guanidines, imidazoles and mixtures thereof, and amines, amides, ureas, nitrogen-containing heterocyclic aromatics, imidazole guanidines and mixtures thereof, substituted with alkyl, aryl or organic alcohol groups.

26. The process of claim 15, wherein the H 2 S complex-forming agent has a pK ^ less than about 13, at about 25 ° C.

27. The process of claim 15, wherein the H 2 S complex-forming agent has a pK ^ less than about 9.5 to about 25 ° C.

28. The process of claim 15, wherein the H 2 S complex forming agent has a K 2 of less than about 6.0, at about 25 ° C.

29. A process for converting the hydrogen sulfide gas to a species of polymeric sulfur comprising: providing a reaction solution containing a quinone and an amphoteric and sulfur-cleaving H2S complex forming agent; contacting the reaction solution with the hydrogen sulfide gas; reacting the hydrogen sulfide gas with the amphoteric and sulfur cleavage H2S complexing agent to produce the free polymeric insoluble sulfur species in the reaction solution; and separating the species of free polymeric sulfur from the reaction solution.

30. The process of claim 29, wherein the amphoteric and sulfur de-sulfur complex H2S-forming agent has a pKa of less than about 5 and a pK less than about 13, at 25 ° C.

31. The process of claim 29, wherein the amphoteric and sulfur de-sulfur complex H2S-forming agent is selected from the group consisting of aminobenzoic acid, 1-nicotinic acid, and mixtures thereof.

32. The process of claim 29 further comprising converting the quinone to a corresponding hydroquinone.

33. The process of claim 32 wherein the amphoteric and sulfur-cleaving H2S complex forming agent and the total quinone consisting of the quinone and hydroquinone are contained in the reaction solution in a molar ratio of between about 1: 50 and approximately 2: 1.

34. The process of reivindication 29, wherein the amphoteric sulfur-cleaving H2S complex forming agent is reacted with the hydrogen sulfide gas at a temperature between about 0 ° C and about 70 ° C.

35. The process of claim 29, wherein the H2S complexing and sulfur debonding agent and the quinone are contained in the reaction solution in a molar ratio of between about 1:50 and about 2: 1.

36. All the inventions described herein.