JP2016519712A - Process for recovering alkali metals and sulfur from alkali metal sulfides and polysulfides - Google Patents

Abstract

In an electrolysis method using an electrolysis cell (120) having an alkali ion conductive membrane, alkali metal (126) and sulfur (128) can be recovered from alkali monosulfide and polysulfide (122). The anolyte solution includes an alkali monosulfide, an alkali polysulfide, or a mixture thereof, and a solvent that dissolves elemental sulfur. The catholyte contains a molten alkali metal. When an electric current is passed, sulfides and polysulfides in the anolyte chamber are oxidized, whereby alkali metal ions pass through the alkali ion conductive membrane and enter the catholyte chamber, and alkali metal ions in the catholyte chamber. Is reduced. Liquid sulfur may be separated from the anode solution and recovered. The electrolysis cell operates at a temperature at which the formed alkali metal and sulfur melt.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of US Provisional Patent Application No. 61 / 781,557, filed March 14, 2013, which is incorporated by reference. This application claims US patent application Ser. No. 12 / 576,977 filed Oct. 9, 2009, which claims the benefit of US Provisional Patent Application No. 61 / 103,973 filed Oct. 9, 2008. Is a continuation-in-part application.

Government License Rights This invention was made with government support under grants based on US Department of Energy grant number DE-FE000004. The government has certain rights in the invention.

The present invention relates to a process for removing nitrogen, sulfur and heavy metals from shale oil, bitumen, heavy oil or refined streams containing sulfur, nitrogen and metals. More specifically, the present invention relates to a method for regenerating an alkali metal from an alkali metal sulfide (monosulfide and polysulfide). The invention further relates to the removal and recovery of sulfur from alkali metal sulfides and polysulfides.

BACKGROUND OF THE INVENTION The demand for energy and the demand for hydrocarbons that are the source of that energy is increasing. However, the hydrocarbon feedstock used to supply energy has difficulty in removing sulfur and metals that hinder its use. Sulfur can cause air pollution and reduce the action of catalysts designed to remove hydrocarbons and nitrogen oxides from automobile exhaust. Similarly, other metals in hydrocarbon streams are also commonly used for sulfur removal via standard and improved hydrodesulfurization processes where hydrogen reacts under extreme conditions to decompose organic sulfur molecules containing sulfur. The action of the catalyst used in the process can be reduced.

  There is a huge reserve of shale oil in the United States that is increasingly important in meeting US energy demand. Reserves in excess of 1 trillion barrels exist in a relatively small area known as the Green River Formation located in Colorado, Utah and Wyoming. As the price of crude oil rises, more attention has been paid to this resource, but there are still technical challenges to be solved. The main challenge is to solve the relatively high level of nitrogen contained in the shale oil chemistry after dry distillation, and to solve the sulfur and metal content.

Shale oil is characteristically rich in nitrogen, sulfur and heavy metals, making subsequent hydroprocessing difficult. According to America's Strategic Unconventional Fuels, Vol. III-Resource and Technology Profiles, p. 111-25 (Non-Patent Document 1), shale oil is usually about 2% nitrogen and about 1% sulfur together with multiple metals. %include. Heavy metals contained in shale oil are a major problem for reforming. Sulfur and nitrogen are typically removed via a hydrotreatment that passes through a catalyst such as Co—Mo / Al ₂ O ₃ or Ni—Mo / Al ₂ O ₃ at high temperature and pressure. These catalysts deactivate as the metal coats the catalyst.

  Other examples of hydrocarbon fuel sources where sulfur removal is a problem include bitumen, which is present in large quantities in Alberta, Canada, and heavy oil, such as in Venezuela. In order to sufficiently remove sulfur from bitumen and make it useful as an energy source, excess hydrogen must be introduced under extreme conditions, which is an inefficient and economically undesirable method.

  Over the past few years, sodium has been recognized as effective in the treatment of high sulfur petroleum fractions, crude oil, heavy oil, bitumen and shale oil. Sodium can react with petroleum and its impurities and dramatically reduce sulfur, nitrogen and metal content through the formation of sodium sulfide compounds (sulfides, polysulfides and hydrosulfides). Examples of this method are described in U.S. Pat. Nos. 3,785,965, 3,787,315, 3,788,978, 4,076,613, and 5,695,632. No. 5,935,421, and No. 6,210,564 (Patent Documents 1 to 7).

An alkali metal such as sodium or lithium is reacted with petroleum at about 350 ° C. and 300-2000 psi. For example, following the initial reaction with an alkali metal, 1-2 moles of sodium and 1-1.5 moles of hydrogen per mole of sulfur may be required.
R—S—R ′ + 2Na + H ₂ → R—H + R′—H + Na ₂ S
R, R ′, R ″ −N + 3Na + 1.5H ₂ → R−H + R′−H + R ″ −H + Na ₃ N
In the formula, R, R ′ and R ″ represent an organic molecule or a part of an organic ring.

The products of sodium sulfide and sodium nitride from the above reaction can be further reacted with hydrogen sulfide according to the following reaction.
Na ₂ S + H ₂ S → 2NaHS (liquid at 375 ° C.)
Na ₃ N + 3H ₂ S → 3NaHS + NH ₃

  Nitrogen is removed in the form of ammonia and can be discharged and recovered. Sulfur is removed in the form of alkaline hydrosulfides such as NaHS and separated for further processing. Heavy metals and organic phases can be separated by specific gravity separation. Although the above reaction was expressed using sodium, it can be replaced with lithium.

  Heavy metals contained in organometallic molecules such as porphyrin complexes are reduced to a metallic state by alkali metals. Heavy metals, once reduced, can be separated from petroleum because they are no longer chemically bonded to organic structures. In addition, if the metal is removed from the porphyrin structure, the nitrogen heteroatoms in the structure can be subjected to further denitrification.

  In the following, a non-limiting description is given of the aforementioned method for treating petroleum organic compounds with alkali metals. A liquid phase alkali metal is contacted with an organic molecule containing a heteroatom and a metal in the presence of hydrogen. Since the free energy of the reaction between sulfur, nitrogen and metal is stronger in the reaction with alkali metal than in the reaction with hydrogen, the reaction occurs rapidly even if the organic compound and hydrogen do not reach full saturation. In order to remove heteroatoms and metals to prevent coking and polymerization, the reaction must be filled with hydrogen, but a gas other than hydrogen may be used instead to prevent polymerization. When the alkali metal compound is formed, the heavy metal is reduced to the metal state, and thus it is necessary to separate it. This is accomplished by a washing step using either water vapor or hydrogen sulfide to form a hydroxide phase when using water vapor and a hydrosulfide phase when using hydrogen sulfide. At the same time, it is estimated that alkali nitride reacts to form ammonia and more alkali hydroxide or hydrosulfide. The reformed petroleum which is an organic phase can be separated from the salt phase by specific gravity separation such as centrifugation or filtration.

In the conventional hydrogenation treatment, H ₂ S and NH ₃ are formed instead of the formation of Na ₂ S for desulfurization or the formation of Na ₃ N for denitrification, respectively. Reactions that form hydrogen sulfide and ammonia are less thermodynamically favorable compared to the formation of sodium or lithium compounds, and the parent molecule is moved to a significant degree to allow the desulfurization or denitrogenation reaction to proceed. Must be destabilized. According to T. Kabe, A Ishihara, W. Qian, in Hydrodesulfurization and Hydrodenitrogenation, pp. 37, 110-112, Wiley-VCH, 1999 (non-patent document 2), this destabilization is almost saturated in the benzo ring. Occurs after. More hydrogen is required for the desulfurization and denitrogenation reactions to bring about this ring saturation, compared to removal with sodium or lithium to achieve the same level of sulfur and nitrogen removal. Therefore, more severe conditions are required. As mentioned above, desulfurization or denitrogenation using hydrogen without sodium or lithium is further complicated by coating of the catalyst surface due to heavy metal and coke deposition. Because sodium is present in the liquid phase, it has easy access to the sulfur, nitrogen and metals that are desired to react.

  If the alkali metal sulfide is separated from the petroleum, sulfur and metals are substantially removed and nitrogen is also removed moderately. Also, both viscosity and density decrease (API specific gravity increases). Bitumen or heavy oil can be considered synthetic crude oil (SCO) and can be transported through a pipeline for further refining. Similarly, shale oil will be significantly modified after such processes. Subsequent purification is simpler because troublesome metals have been removed.

  Although the use of alkali metals such as sodium in the removal of sulfur has proven effective, no practical and cost-effective method for regenerating alkali metals has yet been proposed, , Has not led to commercial implementation. Several researchers have proposed sodium regeneration using electrolytic cells using sodium ion conductive beta alumina membranes. However, beta alumina is expensive and fragile, and the use of beta alumina as a membrane separator is not effective for metal production. In addition, since the cell utilizes a sulfur anode, the polarity of the cell is high and separate excess energy is required.

  Sodium metal is produced almost exclusively in Downs cells such as the cell described in US Pat. No. 1,501,756. Such a cell electrolyzes sodium chloride dissolved in a molten salt electrolyte to form molten sodium at the cathode and chlorine gas at the anode. The cell is operated at a temperature close to 600 ° C. that is compatible with the electrolyte used. Unlike sulfur anodes, chlorine anodes are used commercially with molten salt in the simultaneous production of sodium and saline in the simultaneous production of sodium hydroxide.

  Other cell technologies include those that limit the melting range of the electrolyte and the operation of the electrolysis cell to below 200 ° C., such as US Pat. No. 6,787,019 to Jacobsen et al. And US Pat. No. 6,368,486 (Patent Document 10). In these disclosures, a low temperature co-electrolyte is used with an alkali halide to form a low temperature molten electrolyte.

  Gordon, in US Pat. No. 8,088,270, uses a solvent that dissolves sulfur at the cell operating temperature, dissolves sodium polysulfide in the solvent to form an anolyte, Teaching that this is introduced into a cell having an alkali ion conductive membrane and electrolyzed, sulfur is formed at the anode and alkali metal is formed at the cathode, a part of the anolyte is taken out of the cell and cooled until sulfur is deposited. doing.

  The object of the present invention is to provide a cost-effective and efficient method for the regeneration of alkali metals used in the desulfurization, denitrification and demetallation of hydrocarbon streams. As described herein, the present invention removes impurities from the desulfurization / denitrogenation / demetallation reactions, separates unwanted material products, and makes these materials available for later use. Can be recovered.

  Another object of the present invention is to teach improvements in a method and apparatus for recovering alkali metals from alkali metal sulfides produced by sulfur removal reforming processes.

U.S. Pat. No. 3,785,965 U.S. Pat. No. 3,787,315 U.S. Pat. No. 3,788,978 U.S. Pat. No. 4,076,613 US Pat. No. 5,695,632 US Pat. No. 5,935,421 US Pat. No. 6,210,564 US Pat. No. 1,501,756 US Pat. No. 6,787,019 US Pat. No. 6,368,486 U.S. Pat. No. 8,088,270

America's Strategic Unconventional Fuels, Vol. III-Resource and Technology Profiles, p. 111-25 T. Kabe, A Ishihara, W. Qian, in Hydrodesulfurization and Hydrodenitrogenation, pp. 37, 110-112, Wiley-VCH, 1999

  The present invention provides a method for removing nitrogen, sulfur and heavy metals from shale oil, bitumen, heavy oil or refined streams containing sulfur, nitrogen and metals. The present invention further provides an electrolytic method for regenerating alkali metal from alkali metal sulfides, polysulfides, nitrides and polynitrides. The present invention further provides an electrolysis method for removing sulfur from a polysulfide solution.

  One non-limiting embodiment within the scope of the present invention includes a method for electrochemical oxidation of alkali metal sulfides and polysulfides. This method utilizes an electrolysis cell having an alkali ion conductive membrane configured to selectively transport alkali ions. The alkali ion conductive membrane separates an anolyte chamber configured to have an anode and a catholyte chamber configured to have a cathode. An anolyte solution is introduced into the anolyte chamber. The anolyte solution comprises an anolyte solvent that partially dissolves the alkali metal sulfides and / or polysulfides and elemental sulfur and alkali metal sulfides and polysulfides. A catholyte solution is introduced into the catholyte chamber. The catholyte solution contains alkali metal ions and catholyte solvent. The catholyte solvent may comprise one of many non-aqueous solvents such as tetraethylene glycol dimethyl ether (tetraglyme), diglyme, dimethyl carbonate, dimethoxy ether, propylene carbonate, ethylene carbonate, diethyl carbonate. The catholyte may also include an alkali metal salt such as an alkali metal iodide or chloride. When a current is passed through the electrolysis cell, sulfides and / or polysulfides in the anolyte chamber are oxidized to form higher polysulfides, and the higher polysulfides are oxidized to elemental sulfur. Further, due to the current, alkali metal ions pass through the alkali ion conductive film and enter the catholyte chamber from the anolyte chamber, and the alkali metal ions in the catholyte chamber are reduced to form elemental alkali metal.

  Sulfur can be recovered in liquid form when the temperature exceeds the melting point of sulfur and the sulfur content of the anolyte exceeds the solubility of the solvent. Since most of the anolyte solvent has a lower specific gravity than sulfur, liquid sulfur precipitates down. This precipitation may occur in the precipitation compartment in the cell and the sulfur may be discharged from the outlet. Alternatively, a part of the anode solution may be moved to the precipitation compartment outside the cell, and sulfur precipitation may be performed more efficiently than in the cell.

  Since the melting temperature of sulfur is approximately 115 ° C., the cell operates optimally at temperatures above that temperature, eg, temperatures above 120 ° C. Moreover, when the alkali metal is sodium at the temperature or higher, the alkali metal also melts. When operated near high temperatures, such as in the range of 125-150 ° C., sulfur formed from polysulfides at the anode is completely dissolved. Then, if the anolyte flows into the precipitation compartment at a low temperature of 5-20 ° C. inside or outside the cell, the solubility of sulfur in the solvent decreases, and the sulfur liquid phase that precipitates with a higher specific gravity from the anolyte Is formed. When the anolyte returns to the anode forming sulfur via polysulfide electrochemical oxidation, the anolyte has a solubility capable of dissolving the formed sulfur, thus preventing adhesion and polarization of the anode or membrane surface.

  In a non-limiting embodiment that is within the scope of the present invention, a molten alkali metal bath that operates at a temperature above the melting temperature of the alkali metal and has a partition between the anolyte chamber and the catholyte chamber. A cell is provided for electrolyzing an alkali metal sulfide or polysulfide that fully or partially immerses the cathode. In this case, the catholyte substantially contains a molten alkali metal, but may further contain a solvent and an alkali metal salt. The partition is permeable to alkali metal cations and is substantially impermeable to anions, solvents and dissolved sulfur. The partition partly includes an alkali metal conductive ceramic or glass ceramic. The partition may be conductive to alkali ions including lithium and sodium.

  In another non-limiting embodiment, a cell for electrolyzing an alkali metal polysulfide is provided comprising an anolyte chamber and a catholyte chamber, the anolyte solution comprising a polar solvent and a dissolved alkali metal polysulfide. Is done. The anodic solution contains a solvent that dissolves elemental sulfur to some extent. The anolyte may contain a solvent, one or more of which may be N, N-dimethylaniline, quinoline, tetrahydrofuran, 2-methyltetrahydrofuran, benzene, cyclohexane, fluorobenzene, trifluorobenzene, toluene, xylene. , Tetraethylene glycol dimethyl ether (tetraglyme), diglyme, isopropanol, ethyl propional, dimethyl carbonate, dimethoxy ether, dimethylpropylene urea, formamide, methylformamide, dimethylformamide, acetamide, methylacetamide, dimethylacetamide, triethylamine, diethylacetamide, ethanol And ethyl acetate, propylene carbonate, ethylene carbonate, and diethylcar Sulfonate, and the like.

  In one non-limiting embodiment, a method is disclosed for electrochemically oxidizing sulfides and polysulfides at an anode from an anolyte solution partially including an anolyte solvent that dissolves elemental sulfur to some extent. In this method, the anolyte solvent for dissolving elemental sulfur to some extent is N, N-dimethylaniline, quinoline, tetrahydrofuran, 2-methyltetrahydrofuran, benzene, cyclohexane, fluorobenzene, trifluorobenzene, toluene, xylene, Tetraethylene glycol dimethyl ether (tetraglyme), diglyme, isopropanol, ethyl propional, dimethyl carbonate, dimethoxy ether, dimethylpropylene urea, formamide, methylformamide, dimethylformamide, acetamide, methylacetamide, dimethylacetamide, triethylamine, diethylacetamide, ethanol and Ethyl acetate, propylene carbonate, ethylene carbonate, and di It is one or more of the chill carbonate.

  In another non-limiting embodiment, an alkali metal monosulfide or polysulfide comprising an anolyte chamber and a catholyte chamber, wherein the anolyte solution comprises a polar solvent and a dissolved alkali metal monosulfide or polysulfide. A cell for electrolyzing sulfide is provided. The anodic solution contains a solvent that dissolves elemental sulfur to some extent. The anolyte may contain a solvent, one or more of which may be N, N-dimethylaniline, quinoline, tetrahydrofuran, 2-methyltetrahydrofuran, benzene, cyclohexane, fluorobenzene, trifluorobenzene, toluene, xylene. , Tetraethylene glycol dimethyl ether (tetraglyme), diglyme, isopropanol, ethyl propional, dimethyl carbonate, dimethoxy ether, dimethylpropylene urea, formamide, methylformamide, dimethylformamide, acetamide, methylacetamide, dimethylacetamide, triethylamine, diethylacetamide, ethanol And ethyl acetate, propylene carbonate, ethylene carbonate, and diethylcar Sulfonate, and the like.

  In one non-limiting embodiment, a method is disclosed for electrochemically oxidizing monosulfides or polysulfides at an anode from an anolyte solution partially including an anolyte solvent that partially dissolves elemental sulfur. . In this method, the anolyte solvent for dissolving elemental sulfur to some extent is N, N-dimethylaniline, quinoline, tetrahydrofuran, 2-methyltetrahydrofuran, benzene, cyclohexane, fluorobenzene, trifluorobenzene, toluene, xylene, Tetraethylene glycol dimethyl ether (tetraglyme), diglyme, isopropanol, ethyl propional, dimethyl carbonate, dimethoxy ether, dimethylpropylene urea, formamide, methylformamide, dimethylformamide, acetamide, methylacetamide, dimethylacetamide, triethylamine, diethylacetamide, ethanol and Ethyl acetate, propylene carbonate, ethylene carbonate, and di It is one or more of the chill carbonate.

  In one non-limiting embodiment, the anolyte solvent comprises about 60-100% by volume polar solvent and 0-40% by volume nonpolar solvent. Blending different anolyte solvents facilitates optimization of elemental sulfur solubility and sulfide and polysulfide solubility.

  Another non-limiting embodiment is a method for removing dissolved elemental sulfur from a solvent / alkali metal polysulfide mixture, cooling, reducing the solubility of sulfur in the solvent, and Disclosed is a method comprising forming a second liquid phase comprising elemental sulfur and then separating the liquid phase sulfur from the liquid phase solvent mixture. Separation of liquid phase sulfur from the liquid phase anolyte includes one or more of specific gravity, centrifugation. Alkali metal polysulfides are species such as sodium polysulfide and lithium polysulfide.

The present invention can provide a number of advantages, including but not limited to:
The alkali metal is removed from the cell in liquid form continuously or semi-continuously.
Sulfur is removed from the cell continuously or semi-continuously in liquid form.
By removing high alkali metal polysulfides and dissolved sulfur continuously or semi-continuously from the electrolysis cell, the anode polarization due to sulfur is reduced.
Separating the sulfur continuously or semi-continuously from the stream containing the mixture of solvent, sulfur and alkali metal polysulfide so that the solvent and alkali metal polysulfide can be substantially recovered and returned to the electrolysis process. .
The electrolytic cell operates at temperature and pressure because the structural material of the electrolytic cell can include materials that are not resistant to high temperatures.

  References to features, advantages, or similar terms made throughout this specification are intended to imply that all of the features and advantages that can be realized using the present invention should be in one embodiment of the present invention. It does not mean that it exists. Rather, words relating to features and advantages are understood to mean that a particular feature, advantage, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, features and advantages throughout the specification as well as descriptions of similar language need not necessarily be, but may relate to the same embodiment or all embodiments.

  Furthermore, the described features, advantages, and characteristics of the invention may be combined in any suitable manner in one or more embodiments. Those skilled in the relevant art will recognize that the invention can be practiced without one or more of the specific features or advantages of a particular embodiment. In other cases, additional features and advantages may be recognized in embodiments that are not present in all embodiments of the invention.

  These features and advantages of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention described hereinafter.

  In order that the features and advantages of the invention described above as well as the manner of obtaining other features and advantages may be readily understood, a more detailed description of the invention briefly described above is provided by way of example in the accompanying drawings. With reference to specific embodiments. Given that the drawings represent only typical embodiments of the invention and are not to be construed as limiting the scope of the invention, the invention will be described with additional specificity and detail through the use of the accompanying drawings. explain.

1 illustrates an overall method for removing nitrogen, sulfur and heavy metals from a petroleum source containing sulfur, nitrogen and metals using alkali metals and regenerating the alkali metals. 2A and 2B show a schematic method for converting alkali metal hydrosulfide to alkali metal polysulfide and recovering hydrogen sulfide. FIG. 2 shows a schematic cross-sectional view of an electrolysis cell that utilizes many of the features that are within the scope of the present invention. Overview of multiple electrolysis cells operating in series for alkali metal extraction and oxidation from alkali metal sulfide to polysulfide, low polysulfide to high polysulfide, and high polysulfide to sulfur FIG.

DETAILED DESCRIPTION OF THE INVENTION The present embodiments of the present invention will be best understood by referring to the drawings. In the drawings, equivalent parts are denoted by the same reference numerals. It will be readily appreciated that the components of the invention schematically illustrated and illustrated in the figures of the drawings can be arranged and designed in a variety of different structures. Accordingly, the following detailed description of the method and cell embodiments of the present invention shown in FIGS. 1-4 is not intended to limit the scope of the claimed invention, but of the present embodiment of the invention. It is just a representative example.

  FIG. 1 schematically illustrates an overall non-limiting embodiment of a method for removing nitrogen, sulfur and heavy metals and regenerating alkali metals from petroleum sources containing sulfur, nitrogen and metals using alkali metals. Shown in In the method 100 of FIG. 1, a petroleum source 102 such as a high sulfur content petroleum fraction, crude oil, heavy oil, bitumen or shale oil is introduced into a reaction vessel 104. Similarly, an alkali metal (M) 106 such as sodium or lithium is introduced into the reaction vessel together with a large amount of hydrogen 108. Alkali metals and hydrogen react with petroleum and its impurities to dramatically reduce sulfur, nitrogen and metal content through the formation of sodium sulfide compounds (sulfides, polysulfides and hydrosulfides) and sodium nitride compounds Lower. Examples of this method are known in the art, for example, U.S. Pat. Nos. 3,785,965, 3,787,315, 3,788,978, 4,076. , 613, 5,695,632, 5,935,421 and 6,210,564, but are not limited thereto.

Alkali metal (M) and hydrogen react with petroleum at about 350 ° C. and 300-2000 psi according to the following initial reaction.
R−S−R ′ + 2M + H ₂ → R−H + R′−H + M ₂ S
R, R ′, R ″ −N + 3M + 1.5H ₂ → R−H + R′−H + R ″ −H + M ₃ N
In the formula, R, R ′ and R ″ represent an organic molecule or a part of an organic ring.

The products of sodium sulfide and sodium nitride from the above reaction can further react with hydrogen sulfide 110 according to the following reaction.
M ₂ S + H ₂ S → 2MHS (liquid at 375 ° C.)
M ₃ N + 3H ₂ S → 3MHS + NH ₃

  Nitrogen is removed in the form of ammonia 112 and can be discharged and recovered. Sulfur is removed from petroleum sources in the form of alkaline hydrosulfides (MHS) such as sodium hydrogen sulfide (NaHS) or lithium hydrogen sulfide (LiHS). The reaction product 113 is transferred to the separation container 114. In the separation vessel 114, the heavy metal 116 and the organic phase 118 of the reformed petroleum are separated by a specific gravity separation method.

Alkaline hydrosulfide (MHS) is separated for further processing. The alkaline hydrosulfide stream can be the primary source of alkali metals and sulfur obtained from the process of the present invention. When the alkali hydrosulfide reacts with the medium to become a high polysulfide (ie, M ₂ S _x ; 4 ≦ x ≦ 6), hydrogen sulfide is released and the resulting mixture has an alkali metal and sulfide content. Increasing and the ratio of sulfur to alkali metal decreases. The hydrogen sulfide 110 can be used in upstream cleaning steps where it is necessary to remove alkali sulfides and alkali nitrides and metals from the initially treated petroleum.

FIG. 2A shows a schematic diagram of the method. For example, in the case of sodium, the following reaction can occur.
Na ₂ S _x + 2NaHS → H ₂ S + 2 [Na ₂ S _{(x + 1) / 2} ]
Here, x: y represents an average ratio of sodium atoms and sulfur atoms in the solution. In the method shown in FIG. 2A, a high sulfur-containing alkali polysulfide is converted to a low sulfur-containing alkali polysulfide.

Alternatively, instead of reacting alkali metal hydrosulfide and alkali metal polysulfide, alkali metal hydrosulfide and sulfur can be reacted. FIG. 2B shows a schematic diagram of the method. For example, in the case of sodium, the following reaction can occur.
YS + 2NaHS → H ₂ S + Na ₂ S _{(Y + 1)}
In the formula, Y is the molar amount of sulfur added to sodium hydrogen sulfide.

  The alkali metal polysulfide may be further processed in an electrolytic cell to remove and recover sulfur and to remove and recover alkali metal. One electrolysis cell 120 is shown in FIG. Electrolytic cell 120 receives alkaline polysulfide 122. Under the influence of the power source 124, alkali metal ions are reduced to form alkali metal (M) 126, which can be recovered and used as a supply source of the alkali metal 106. Sulfur 128 is also recovered from the electrolytic cell 120 process. A detailed description of one possible electrolysis cell that can be used in methods that are within the scope of the present invention is provided with respect to FIG. A more detailed description of the recovery of sulfur 128 follows below with respect to FIG.

  2A and 2B are containers in which the reaction occurs, which is an anolyte chamber of the electrolysis cell 120 shown in FIG. 1, a concentration tank 312 shown in FIG. 4, or a separation container that contributes to the capture and recovery of the generated hydrogen sulfide gas 110. obtain. Alternatively, the sulfur generated by the method shown in FIG. 1 can be used as an input material as shown in FIG. 2B.

  FIG. 3 shows a schematic cross-sectional view of an electrolysis cell 300 that utilizes many of the features that are within the scope of the present invention. The cell is generally an electrical insulator and consists of a housing 310 that is chemically resistant to solvents and sodium sulfide. In this case, the cation conductive film 312 having a tube shape separates the catholyte chamber 314 and the anolyte chamber 316. Within the catholyte chamber is a cathode 324. The cathode 324 can be configured to penetrate the housing 310 or have a lead 326 that extends through the housing 310 such that a connection to a cathode of a DC power source (not shown) is made. Within the anolyte chamber 316 is an anode 326, which in this case is shown as a cylindrical porous mesh electrode surrounding the tube membrane 312. Lead 328 passes through the housing for connection to the anode of the DC power source. The anolyte solution flows through the anolyte inlet 330. The anolyte consists of a mixture of solvent and alkali metal sulfide. The anolyte enters through the inlet 330 and exits through the outlet 332. In some cases, a second liquid phase of sulfur melted with the anolyte may also be present. The second discharge port from the anolyte chamber may be provided at a position lower than the anolyte discharge port 332. The lower second outlet can be further used to remove molten sulfur that settles and accumulates at the cell bottom. The space between the cathode 324 and the membrane 312 is usually filled with molten alkali metal. When the cell is activated, alkali metal ions pass through the membrane 312 and are reduced at the cathode 324 in the catholyte chamber 314 to form alkali metal, and the alkali metal stream passes through the catholyte outlet 334.

  The cell may have a plurality of anodes, cathodes and membranes. The anodes in the cell are all in parallel and the cathodes are all in parallel.

  With reference to FIG. 3, the electrolysis cell housing 310 is preferably an electrically insulating material such as a primary polymer. This material is also preferably resistant to solvents. Polytetrafluoroethylene (PTFE) is particularly suitable, as is Kynar® polyvinylidene fluoride or high density polyethylene (HDPE). The cell housing 310 may also be manufactured from non-insulating and non-chemical resistant materials, as long as the inside of the housing 310 is lined with an insulating chemical resistant material. Other suitable materials are inorganic materials such as alumina, silica, aluminosilicates and other insulating refractory or ceramic materials.

The cationic conductive membrane 312 is preferably substantially permeable only to cations and substantially impermeable to anions, polyanions and dissolved sulfur. The membrane 312 may be partially made from an alkali metal ion conductive material. When the metal recovered by the cell is sodium, a particularly suitable material for the partition is what is known as NaSICON, which has a relatively high ionic conductivity at room temperature. A typical NaSICON composition is substantially Na _{1 + x} Zr ₂ Si _x P _3-x O ₁₂ (where 0 <x <3). Other NaSICON compositions are also known in the art. Alternatively, when the metal recovered in the cell is lithium, the most suitable material for the partition is substantially Li _{(1 + x + 4y)} Al _x Ti _(1-xy) (PO ₄ ) ₃ (where 0 < Lithium titanium phosphate (LTP) having a composition of x <0.4 and 0 <y <0.2. Other suitable materials are by ion-conducting glass and glass-ceramic species, the general composition is Li _{1 + x} Al _x Ge _2-x PO ₄ . Other lithium conductive materials are also known in the art. In the membrane 312, the liquid in the anolyte chamber 316 and the catholyte chamber 314 cannot permeate from one chamber to the other, but substantially only alkali ions (M ⁺ ) such as sodium ions or lithium ions. It may have a thickness portion with negligible through voids to pass from the anolyte chamber 316 through the catholyte chamber 314. The membrane may also be partially composed of an alkali metal conductive glass ceramic, such as a material manufactured by Ohara Glass, Inc., Japan.

  The anode 326 is disposed in the anolyte chamber 316. The anode can be made from conductive materials such as stainless steel, nickel, iron, iron alloys, nickel alloys and other anode materials known in the art. The anode 326 is connected to the positive electrode of the DC power source. The anode 326 may be a mesh monolithic structure or a monolithic characteristic that allows the anolyte to pass through the anode structure. The anolyte solution is supplied to the anolyte chamber through the inlet 330 and discharged from the chamber through the outlet 332. The electrolysis cell 300 can also be operated in a semi-continuous manner in which it is supplied to the anolyte chamber and partially discharged through the same passage.

  The conductive cathode 324 is in the form of a strip, band, rod or mesh. The cathode 324 can be composed of many electrical conductors such as steel, iron, copper or graphite. A portion of the cathode may be disposed within the catholyte chamber 314 and a portion may be disposed outside the catholyte chamber 314 and cell housing 310 for electrical contact. Alternatively, the lead 325 may extend from the cathode to the outside of the cell housing 310 for electrical contact.

  The catholyte chamber 314 is an alkali ion conductive liquid that may contain a polar solvent. Non-limiting examples of suitable polar solvents are tetraethylene glycol dimethyl ether (tetraglyme), diglyme, dimethyl carbonate, dimethoxy ether, propylene carbonate, ethylene carbonate, diethyl carbonate and the like. Suitable alkali metal salts are chloride, bromide, iodide, perchlorate, hexafluorophosphate, etc., which are dissolved in a polar solvent to form a catholyte solution. In most cases, the catholyte is a molten alkali metal bath.

  A non-limiting example of the operation of the electrolysis cell 300 is shown below. An anolyte solution is supplied to the anolyte chamber 316. Depending on the composition, a voltage higher than a decomposition voltage in the range of about 1.8 V to about 2.5 V is applied to the electrodes 324 and 326 so that a potential is generated between the anode 326 and the cathode 324. At the same time, alkali metal ions such as sodium ions pass through the membrane 312 and enter the catholyte chamber 314. The electrons supplied through the cathode 324 in the catholyte chamber 314 reduce sodium ions to a metal state, thereby providing sulfide. And polysulfides are oxidized at the anode 326, low polysulfide anions become high polysulfide anions, and / or elemental sulfur is formed at the anode. While sulfur is formed, all or part of it dissolves in the anolyte solvent. Upon saturation or cooling of the sulfur, the sulfur can form a second liquid phase of sulfur that settles to the bottom of the anolyte chamber 316 of the electrolysis cell. Sulfur may be removed with the anolyte solution and precipitated in a vessel outside the cell, or removed directly from the precipitation compartment 336 via an optional sulfur outlet 338 as shown in FIG.

  The mode of operation may be that the anolyte of one electrolytic cell flows from the second cell to the second cell, from the second cell to the third cell, etc., and in each subsequent cell, the polysulfide form is As the grade becomes higher, the ratio of sodium to sulfide decreases. FIG. 4 illustrates the extraction of alkali metal, oxidation of alkali metal sulfide to low alkali metal polysulfide, oxidation of low alkali metal polysulfide to high alkali metal polysulfide, and high alkali metal polysulfide. FIG. 4 is a non-limiting schematic diagram of four electrolysis cells 402, 404, 406, 408 operating in series for oxidation to high alkali metal polysulfide and oxidation of high alkali metal polysulfide to sulfur. . The electrolysis cells 402, 404, 406 and 408 can be operated such that only the final cell produces sulfur and alkali metal is produced at all cathodes of the cell.

In a non-limiting example, an alkali metal monosulfide such as sodium sulfide (Na ₂ S) can be introduced into the first electrolysis cell 402. Under the influence of the DC power source, sodium ions move from the anolyte chamber to the catholyte chamber, and alkali ions are reduced to form an alkali metal. Sulfides are oxidized in the anolyte chamber to form low sulfides such as Na ₂ S ₄ . The low alkali metal polysulfide is sent to the anolyte chamber of the second electrolysis cell 404. Under the influence of the DC power source, sodium ions move from the anolyte chamber to the catholyte chamber, and alkali ions are reduced to form an alkali metal. The low polysulfide is oxidized in the anolyte chamber to form a high polysulfide such as Na ₂ S ₆ . The high alkali metal polysulfide is sent to the anolyte chamber of the third electrolysis cell 406. Under the influence of the DC power source, sodium ions move from the anolyte chamber to the catholyte chamber, and alkali ions are reduced to form an alkali metal. High polysulfides are oxidized in the anolyte chamber to form high polysulfides such as Na ₂ S ₈ . The high alkali metal polysulfide is sent to the anolyte chamber of the fourth electrolysis cell 408. Under the influence of the DC power source, sodium ions move from the anolyte chamber to the catholyte chamber, and alkali ions are reduced to form an alkali metal. High polysulfides are oxidized in the anolyte chamber to form sulfur, which is then removed from the anolyte chamber and recovered.

  It is understood that the foregoing examples of different polysulfides are described as representative examples of the basic principle that higher polysulfides can be formed by polysulfide oxidation and removal of sodium ions, and a combination of both. Will be done.

  The multi-cell embodiment described with respect to FIG. 4 can form alkali metals and sulfur more efficiently than the single-cell embodiment. The reason for energy efficiency is that less energy is required to oxidize the low polysulfide compared to the high polysulfide. Whereas the voltage required to oxidize polysulfide to sulfur is about 2.2 volts, monosulfides and low polysulfides can be oxidized at lower volts, such as 1.7 volts.

When the alkali metal is sodium, the following typical reaction can occur in the electrolysis cell 300.
Cathode:
Na ⁺ + e- → Na
anode:
1) Na ₂ S _x → Na ⁺ + e ⁻ + 1 / 2Na ₂ S _(2x)
2) Na ₂ S _x → Na ⁺ + e ⁻ + 1 / 2Na ₂ S _x + x / 16S ₈
Where x ranges from 0 to about 8.

  Although most sodium is produced commercially from the electrolysis of molten salt sodium chloride rather than sodium polysulfide, the decomposition voltage and energy requirements for chloride are It is about half compared with.

Table 1. Decomposition voltage and energy of sodium and lithium chlorides and sulfides (watt hours / mole)

The open circuit potential of the sodium / polysulfide cell is as low as 1.8 V, the low polysulfide Na ₂ S ₃ is decomposed, and the voltage increases as the sulfur content increases. Therefore, it can be said that it is desirable to operate part of the electrolysis using an anolyte having a low sulfur content. In one embodiment, a flat NaSICON or lithium titanium phosphate (LTP) film is used to regenerate sodium or lithium, respectively. NaSICON and LTP have excellent low-temperature conductivity as shown in Table 2. The conductivity value of beta alumina was estimated from the conductivity and activation energy at 300 ° C. reported in May. G. May, J. Power Sources, 3, 1 (1978).

(Table 2) Conductivity of NaSICON, LTP and beta alumina at 25 ° C and 120 ° C

  It may be beneficial to run two or more groups of cells. A non-limiting example is shown in FIG. Multiple cells operate in the anolyte using lower sulfides and polysulfides, and another cell group operates using higher polysulfides. In the latter, free sulfur becomes the product that needs to be removed.

  The following example is now provided that illustrates one particular embodiment within the scope of the present invention. This embodiment is illustrative in nature and should not be construed as limiting the scope of the invention.

The electrolytic flow cell uses a 1 inch diameter NaSICON membrane with an active surface of about 3.2 cm ² . NaSICON is sealed to a scaffold made of non-conductive material that is also resistant to the environment. One suitable scaffold material is alumina. Glass may be used as the sealing material. The electrolyte flow path is through a gap between the electrode and the membrane. The anode (sulfur electrode) can be composed of aluminum. The cathode may be either aluminum or stainless steel. It is within the scope of the present invention to construct a fluid cell having a bipolar design. The anolyte solution and the catholyte solution each have a reservoir and a pump. The anolyte reservoir has a stirrer. The entire system preferably has a temperature control with a maximum temperature of 150 ° C. and is further configured to be immersed in a dry cover gas. The system also preferably has a power supply that can apply up to 5 VDC and up to 100 mA / cm ² .

  The material is selected as much as possible with a structure that is corrosion resistant to the expected conditions. The fluid cell is designed so that the gap between the electrode and the membrane can be changed.

In view of the foregoing, it will be appreciated that the disclosed invention includes one or more of the following advantages.
The alkali metal is removed from the cell in liquid form continuously or semi-continuously.
Sulfur is removed from the cell continuously or semi-continuously in liquid form.
By removing high alkali metal polysulfides and dissolved sulfur continuously or semi-continuously from the electrolysis cell, the anode polarization due to sulfur is reduced.
Separation of sulfur continuously or semi-continuously from a stream comprising a mixture of solvent, sulfur and alkali metal polysulfide so that the solvent and alkali metal polysulfide can be substantially recovered and returned to the electrolysis process .
The electrolytic cell operates at temperature and pressure because the structural material of the electrolytic cell can include materials that are not resistant to high temperatures.

  While particular embodiments of the present invention have been illustrated and described, numerous changes can be devised without departing significantly from the spirit of the invention, and the scope of protection is limited only by the appended claims. It is.

CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of US Provisional Patent Application No. 61 / 781,557, filed March 14, 2013, which is incorporated by reference.

[Invention 1001]
Obtaining an electrolysis cell comprising an alkali ion conductive membrane configured to selectively transport alkali ions, wherein the membrane comprises an anolyte chamber configured to have an anode and a cathode; Separating the catholyte chamber configured in
Introducing an anolyte solution comprising an alkali metal monosulfide, an alkali metal polysulfide, or a mixture thereof and an anolyte solvent that partially dissolves elemental sulfur into the anolyte chamber;
Introducing a catholyte containing molten alkali metal into the catholyte chamber;
Passing a current through the electrolysis cell at an operating temperature, whereby
i. The monosulfide or polysulfide in the anolyte chamber is oxidized to form liquid elemental sulfur,
ii. Alkali metal ions pass from the anolyte chamber through the alkali ion conductive membrane into the catholyte chamber,
iii. The alkali metal ions in the catholyte chamber are reduced to form a liquid elemental alkali metal;
Saturating liquid elemental sulfur in the anode solution to form a second liquid phase
A method for electrochemically oxidizing alkali metal monosulfides and polysulfides.
[Invention 1002]
The method of the invention 1001, wherein the liquid elemental sulfur separates from the anode solution in a precipitation compartment in the electrolysis cell.
[Invention 1003]
The method of the invention 1001, wherein the liquid elemental sulfur separates from the anolyte solution in a precipitation compartment outside the cell.
[Invention 1004]
The method of the present invention 1001, wherein the separation of the liquid elemental sulfur from the anolyte solution comprises one or more of separation techniques selected from specific gravity, filtration, and centrifugation.
[Invention 1005]
The method of invention 1001, wherein the alkali ion conductive membrane is substantially impermeable to anions, the catholyte solvent, the anolyte solvent, and dissolved sulfur.
[Invention 1006]
The method of the invention 1001, wherein the alkali ion conductive membrane comprises in part an alkali metal conductive ceramic or glass ceramic.
[Invention 1007]
The method of claim 1001, wherein the alkali ion conductive membrane comprises a solid MSICON (Metal Super Ion Conducting) material and M is Na or Li.
[Invention 1008]
The anolyte solvent is N, N-dimethylaniline, quinoline, tetrahydrofuran, 2-methyltetrahydrofuran, benzene, cyclohexane, fluorobenzene, trifluorobenzene, toluene, xylene, tetraethylene glycol dimethyl ether (tetraglyme), diglyme. , Isopropanol, ethyl propional, dimethyl carbonate, dimethoxy ether, dimethylpropylene urea, formamide, methylformamide, dimethylformamide, acetamide, methylacetamide, dimethylacetamide, triethylamine, diethylacetamide, ethanol and ethyl acetate, propylene carbonate, ethylene carbonate, and Diethyl carbonate or The method of the present invention 1001, comprising one or more solvents selected from
[Invention 1009]
The method of the present invention 1001, wherein the anolyte solvent comprises about 60-100 volume% polar solvent and 0-40 volume% non-polar solvent.
[Invention 1010]
Obtaining a first electrolysis cell comprising an alkali ion conductive membrane configured to selectively transport alkali ions, the membrane comprising an anode liquid chamber configured to have an anode, and a cathode Separating the catholyte chamber configured to have
Introducing an anolyte solution comprising an alkali metal monosulfide, an alkali metal polysulfide, or a mixture thereof and an anolyte solvent that partially dissolves elemental sulfur into the anolyte chamber;
Introducing a catholyte containing molten alkali metal into the catholyte chamber;
A step of passing a current through the electrolysis cell, whereby
i. The sulfide or polysulfide in the anolyte chamber is oxidized to form a higher polysulfide,
ii. Alkali metal ions pass from the anolyte chamber through the alkali ion conductive membrane into the catholyte chamber,
iii. The alkali metal ions in the catholyte chamber are reduced to form elemental alkali metals;
Sending an anode solution from the first electrolysis cell to a second electrolysis cell comprising an alkali ion conductive membrane configured to selectively transport alkali ions, the membrane having an anode Separating an anolyte chamber configured as described above and a catholyte chamber configured to have a cathode and a catholyte,
A step of passing a current through the second electrolysis cell, whereby
i. The polysulfide in the anolyte chamber is oxidized to form liquid elemental sulfur,
ii. Alkali metal ions pass from the anolyte chamber through the alkali ion conductive membrane into the catholyte chamber,
iii. The alkali metal ions in the catholyte chamber are reduced to form a liquid elemental alkali metal;
Saturating liquid elemental sulfur in the anode solution to form a second liquid phase
A process for electrochemically oxidizing alkali metal polysulfides and monosulfides.
[Invention 1011]
The method of the present invention 1010, wherein the liquid elemental sulfur separates from the anode solution in a precipitation compartment in the electrolysis cell.
[Invention 1012]
The method of the invention 1010, wherein the liquid elemental sulfur separates from the anolyte solution in a precipitation compartment outside the cell.
[Invention 1013]
The method of the present invention 1010, wherein separation of the liquid elemental sulfur from the anolyte solution comprises one or more of separation techniques selected from specific gravity, filtration, and centrifugation.
[Invention 1014]
The method of invention 1010, wherein the alkali ion conductive membrane is substantially impermeable to anions, the catholyte solvent, the anolyte solvent, and dissolved sulfur.
[Invention 1015]
The method of the present invention 1010, wherein the alkali ion conductive membrane partially comprises an alkali metal conductive ceramic or glass ceramic.
[Invention 1016]
The method of the present invention 1010, wherein the alkali ion conductive membrane comprises a solid MSICON (Metal Super Ion Conducting) material and M is Na or Li.
[Invention 1017]
The anolyte solvent is N, N-dimethylaniline, quinoline, tetrahydrofuran, 2-methyltetrahydrofuran, benzene, cyclohexane, fluorobenzene, trifluorobenzene, toluene, xylene, tetraethylene glycol dimethyl ether (tetraglyme), diglyme, isopropanol, From ethyl propional, dimethyl carbonate, dimethoxy ether, dimethylpropylene urea, formamide, methylformamide, dimethylformamide, acetamide, methylacetamide, dimethylacetamide, triethylamine, diethylacetamide, ethanol and ethyl acetate, propylene carbonate, ethylene carbonate, and diethyl carbonate Contains one or more selected solvents The method of the present invention 1010.
[Invention 1018]
The method of the present invention 1010, wherein the anolyte solvent comprises about 60-100% by volume polar solvent and 0-40% by volume non-polar solvent.
[Invention 1019]
An anolyte compartment configured to have an anode and containing an anolyte solution comprising an alkali metal monosulfide, alkali metal polysulfide, or mixture thereof and an anolyte solvent that partially dissolves elemental sulfur An anolyte chamber further comprising an anolyte inlet and an anolyte outlet;
A catholyte chamber configured to have a cathode and containing a catholyte containing molten alkali metal, further comprising a catholyte outlet;
An alkali ion conductive membrane configured to selectively transport alkali ions and substantially impermeable to anions, said anolyte solvent, and dissolved sulfur;
A potential source electrically coupled to the anode and the cathode;
The monosulfide or polysulfide in the anolyte chamber is oxidized to form liquid elemental sulfur,
Alkali metal ions pass from the anolyte chamber through the alkali ion conductive membrane into the catholyte chamber,
The alkali metal ions in the catholyte chamber are reduced to form a liquid elemental alkali metal.
A potential source configured as
An elemental sulfur precipitation compartment in which liquid elemental sulfur separates from the anode solution;
An electrolytic cell for oxidizing an alkali metal polysulfide.
[Invention 1020]
The electrolytic cell of the present invention 1019, wherein the alkali ion conductive membrane includes alkali metal conductive ceramic or glass ceramic in part.
[Invention 1021]
The electrolytic cell of the present invention 1019, wherein the alkali ion conductive film includes a solid MSICON (Metal Super Ion Conducting) material, and M is Na or Li.
[Invention 1022]
The anolyte solvent is N, N-dimethylaniline, quinoline, tetrahydrofuran, 2-methyltetrahydrofuran, benzene, cyclohexane, fluorobenzene, trifluorobenzene, toluene, xylene, tetraethylene glycol dimethyl ether (tetraglyme), diglyme, isopropanol, From ethyl propional, dimethyl carbonate, dimethoxy ether, dimethylpropylene urea, formamide, methylformamide, dimethylformamide, acetamide, methylacetamide, dimethylacetamide, triethylamine, diethylacetamide, ethanol and ethyl acetate, propylene carbonate, ethylene carbonate, and diethyl carbonate Contains one or more selected solvents Electrolytic cell of the present invention 1019.
[Invention 1023]
The electrolysis cell of the invention 1019, wherein the anolyte solvent comprises about 60-100 volume% polar solvent and 0-40 volume% non-polar solvent.
[Invention 1024]
The electrolysis cell of the invention 1019 further comprising a sulfur outlet for removing elemental sulfur from the electrolysis cell.
These features and advantages of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention described hereinafter.

Claims (24)

Obtaining an electrolysis cell comprising an alkali ion conductive membrane configured to selectively transport alkali ions, wherein the membrane comprises an anolyte chamber configured to have an anode and a cathode; Separating the catholyte chamber configured in
Introducing an anolyte solution comprising an alkali metal monosulfide, an alkali metal polysulfide, or a mixture thereof and an anolyte solvent that partially dissolves elemental sulfur into the anolyte chamber;
Introducing a catholyte containing molten alkali metal into the catholyte chamber;
Flowing a current through the electrolysis cell at an operating temperature, whereby
i. The monosulfide or polysulfide in the anolyte chamber is oxidized to form liquid elemental sulfur,
ii. Alkali metal ions pass from the anolyte chamber through the alkali ion conductive membrane into the catholyte chamber,
iii. The alkali metal ions in the catholyte chamber are reduced to form a liquid elemental alkali metal;
A method for electrochemically oxidizing alkali metal monosulfides and polysulfides comprising the step of saturating liquid elemental sulfur in the anode solution to form a second liquid phase.   The method of claim 1, wherein the liquid elemental sulfur separates from the anode solution in a precipitation compartment within the electrolysis cell.   The method of claim 1, wherein the liquid elemental sulfur separates from the anode solution in a precipitation compartment outside the cell.   The method of claim 1, wherein separation of the liquid elemental sulfur from the anolyte solution comprises one or more of separation techniques selected from specific gravity, filtration, and centrifugation.   The method of claim 1, wherein the alkali ion conductive membrane is substantially impermeable to anions, the catholyte solvent, the anolyte solvent, and dissolved sulfur.   The method according to claim 1, wherein the alkali ion conductive film partially includes an alkali metal conductive ceramic or glass ceramic.   The method of claim 1, wherein the alkali ion conductive membrane comprises a solid MSICON (Metal Super Ion Conducting) material and M is Na or Li.   The anolyte solvent is N, N-dimethylaniline, quinoline, tetrahydrofuran, 2-methyltetrahydrofuran, benzene, cyclohexane, fluorobenzene, trifluorobenzene, toluene, xylene, tetraethylene glycol dimethyl ether (tetraglyme), diglyme. , Isopropanol, ethyl propional, dimethyl carbonate, dimethoxy ether, dimethylpropylene urea, formamide, methylformamide, dimethylformamide, acetamide, methylacetamide, dimethylacetamide, triethylamine, diethylacetamide, ethanol and ethyl acetate, propylene carbonate, ethylene carbonate, and Diethyl carbonate Comprising one or more solvents, the method according to claim 1 is al selected.   The method of claim 1, wherein the anolyte solvent comprises about 60-100 vol% polar solvent and 0-40 vol% nonpolar solvent. Obtaining a first electrolysis cell comprising an alkali ion conductive membrane configured to selectively transport alkali ions, said membrane comprising an anode liquid chamber configured to have an anode, a cathode Separating the catholyte chamber configured to have an anode comprising an alkali metal monosulfide, alkali metal polysulfide, or mixture thereof and an anolyte solvent that partially dissolves elemental sulfur Introducing a solution into the anolyte chamber;
Introducing a catholyte containing molten alkali metal into the catholyte chamber;
A step of passing a current through the electrolysis cell, whereby
i. The sulfide or polysulfide in the anolyte chamber is oxidized to form a higher polysulfide,
ii. Alkali metal ions pass from the anolyte chamber through the alkali ion conductive membrane into the catholyte chamber,
iii. A process in which the alkali metal ions in the catholyte chamber are reduced to form elemental alkali metals. A second electrolysis cell comprising an alkali ion conductive membrane configured to selectively transport alkali ions. A step of feeding an anolyte solution from the first electrolysis cell, wherein the membrane has an anolyte chamber configured to have an anode, a catholyte chamber configured to have a cathode and a catholyte solution; Separating the process,
Passing a current through the second electrolysis cell, whereby:
i. The polysulfide in the anolyte chamber is oxidized to form liquid elemental sulfur,
ii. Alkali metal ions pass from the anolyte chamber through the alkali ion conductive membrane into the catholyte chamber,
iii. The alkali metal ions in the catholyte chamber are reduced to form a liquid elemental alkali metal;
A method for electrochemical oxidation of alkali metal polysulfides and monosulfides comprising the step of saturating liquid elemental sulfur in the anode solution to form a second liquid phase.   The method of claim 10, wherein the liquid elemental sulfur separates from the anolyte solution in a precipitation compartment within the electrolysis cell.   The method of claim 10, wherein the liquid elemental sulfur separates from the anolyte solution in a precipitation compartment outside the cell.   11. The method of claim 10, wherein the separation of the liquid elemental sulfur from the anolyte solution comprises one or more of separation techniques selected from specific gravity, filtration, and centrifugation.   11. The method of claim 10, wherein the alkali ion conductive membrane is substantially impermeable to anions, the catholyte solvent, the anolyte solvent, and dissolved sulfur.   The method according to claim 10, wherein the alkali ion conductive membrane partially includes an alkali metal conductive ceramic or glass ceramic.   The method of claim 10, wherein the alkali ion conductive membrane comprises a solid MSICON (Metal Super Ion Conducting) material and M is Na or Li.   The anolyte solvent is N, N-dimethylaniline, quinoline, tetrahydrofuran, 2-methyltetrahydrofuran, benzene, cyclohexane, fluorobenzene, trifluorobenzene, toluene, xylene, tetraethylene glycol dimethyl ether (tetraglyme), diglyme, isopropanol, From ethyl propional, dimethyl carbonate, dimethoxy ether, dimethylpropylene urea, formamide, methylformamide, dimethylformamide, acetamide, methylacetamide, dimethylacetamide, triethylamine, diethylacetamide, ethanol and ethyl acetate, propylene carbonate, ethylene carbonate, and diethyl carbonate Contains one or more selected solvents The method of claim 10.   The method of claim 10, wherein the anolyte solvent comprises about 60-100 volume% polar solvent and 0-40 volume% non-polar solvent. An anolyte compartment configured to have an anode and containing an anolyte solution comprising an alkali metal monosulfide, alkali metal polysulfide, or mixture thereof and an anolyte solvent that partially dissolves elemental sulfur An anolyte chamber further comprising an anolyte inlet and an anolyte outlet;
A catholyte chamber configured to have a cathode and containing a catholyte containing molten alkali metal, further comprising a catholyte outlet;
An alkali ion conductive membrane configured to selectively transport alkali ions and substantially impermeable to anions, said anolyte solvent, and dissolved sulfur;
A potential source electrically coupled to the anode and the cathode;
The monosulfide or polysulfide in the anolyte chamber is oxidized to form liquid elemental sulfur,
Alkali metal ions pass from the anolyte chamber through the alkali ion conductive membrane into the catholyte chamber,
A potential source configured to reduce the alkali metal ions in the catholyte chamber to form a liquid elemental alkali metal;
An electrolytic cell for oxidizing alkali metal polysulfides, comprising an elemental sulfur precipitation compartment in which liquid elemental sulfur separates from the anode solution.   The electrolytic cell according to claim 19, wherein the alkali ion conductive film partially includes an alkali metal conductive ceramic or glass ceramic.   The electrolysis cell according to claim 19, wherein the alkali ion conductive film comprises a solid MSICON (Metal Super Ion Conducting) material, and M is Na or Li.   The anolyte solvent is N, N-dimethylaniline, quinoline, tetrahydrofuran, 2-methyltetrahydrofuran, benzene, cyclohexane, fluorobenzene, trifluorobenzene, toluene, xylene, tetraethylene glycol dimethyl ether (tetraglyme), diglyme, isopropanol, From ethyl propional, dimethyl carbonate, dimethoxy ether, dimethylpropylene urea, formamide, methylformamide, dimethylformamide, acetamide, methylacetamide, dimethylacetamide, triethylamine, diethylacetamide, ethanol and ethyl acetate, propylene carbonate, ethylene carbonate, and diethyl carbonate Contains one or more selected solvents The electrolytic cell of claim 19.   20. The electrolysis cell of claim 19, wherein the anolyte solvent comprises about 60-100% by volume polar solvent and 0-40% by volume nonpolar solvent.   The electrolysis cell of claim 19 further comprising a sulfur outlet for removing elemental sulfur from the electrolysis cell.

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