# US 2014/0197040 A1 · Process for recovering alkali metals and sulfur from alkali metal sulfides and polysulfides > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0197040 A1 - Document ID: US20140197040A1 - Status: Published application - Kind: A1 - Application number: 14/210,891 - Filed: 2014-03-14 - Published: 2014-07-17 - Earliest claimed: 2008-10-09 - Assignees: Ceramatec, Inc. - Applicants: Ceramatec, Inc. - Inventors: John Howard Gordon; Javier Alvare - Web page: https://patentgrep.com/patent/US20140197040A1 ## CPC - C25C 1/02: of light metals - B01D 61/44: Ion-selective electrodialysis - B01D 61/461: {comprising only a single cell, only one anion or cation exchange membrane or one pair of anion and cation membranes} - C01B 17/22: Alkali metal sulfides or polysulfides - C01B 17/34: Polysulfides of sodium or potassium - C10G 32/02: by electric or magnetic means - C25B 1/00: Electrolytic production of inorganic compounds or non-metals - C25B 1/01: Products - C25C 3/02: of alkali or alkaline earth metals - C25C 7/06: Operating or servicing - C10G 2300/202: Heteroatoms content, i.e. S, N, O, P - C25C: PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} - C10G: CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION (cracking to hydrogen or synthesis gas C01B; cracking or pyrolysis of hydrocarbon gases to individual hydrocarbons or mixtures thereof of definite or specified constitution C07C; cracking to cokes C10B); RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES - C25B: ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR (anodic or cathodic protection C23F13/00; single-crystal growth C30B) ## Abstract Alkali metals and sulfur may be recovered from alkali monosulfide and polysulfides in an electrolytic process that utilizes an electrolytic cell having an alkali ion conductive membrane. An anolyte solution includes an alkali monosulfide, an alkali polysulfide, or a mixture thereof and a solvent that dissolves elemental sulfur. A catholyte includes molten alkali metal. Applying an electric current oxidizes sulfide and polysulfide in the anolyte compartment, causes alkali metal ions to pass through the alkali ion conductive membrane to the catholyte compartment, and reduces the alkali metal ions in the catholyte compartment. Liquid sulfur separates from the anolyte solution and may be recovered. The electrolytic cell is operated at a temperature where the formed alkali metal and sulfur are molten. ## Claims ### Claim 1 A process for oxidizing alkali metal monosulfides and polysulfides electrochemically comprising: obtaining an electrolytic cell comprising an alkali ion conductive membrane configured to selectively transport alkali ions, the membrane separating an anolyte compartment configured with an anode and a catholyte compartment configured with a cathode; introducing into the anolyte compartment 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; introducing into the catholyte compartment a catholyte wherein the catholyte comprises a molten alkali metal; applying an electric current to the electrolytic cell at an operating temperature thereby: i. oxidizing monosulfide or polysulfide in the anolyte compartment to form liquid elemental sulfur; ii. causing alkali metal ions to pass through the alkali ion conductive membrane from the anolyte compartment to the catholyte compartment; and iii. reducing the alkali metal ions in the catholyte compartment to form liquid elemental alkali metal; allowing liquid elemental sulfur to become saturated in the anolyte solution and to form a second liquid phase. ### Claim 2 (depends on 1) The process according to claim 1 where the liquid elemental sulfur separates from the anolyte solution in a settling zone that is within the electrolytic cell. ### Claim 3 (depends on 1) The process according to claim 1 where the liquid elemental sulfur separates from the anolyte solution in a settling zone that is external to the cell. ### Claim 4 (depends on 1) The process according to claim 1 where the separation of liquid elemental sulfur from the anolyte solution includes one or more of the separation techniques selected from gravimetric, filtration, and centrifugation. ### Claim 5 (depends on 1) The process according to claim 1, wherein the alkali ion conductive membrane is substantially impermeable to anions, the catholyte solvent, the anolyte solvent, and dissolved sulfur. ### Claim 6 (depends on 1) The process according to claim 1, wherein the alkali ion conductive membrane comprises in part an alkali metal conductive ceramic or glass ceramic. ### Claim 7 (depends on 1) The process according to claim 1, wherein the alkali ion conductive membrane comprises a solid MSICON (Metal Super Ion CONducting) material, where M is Na or Li. ### Claim 8 (depends on 1) The process according to claim 1, wherein the anolyte solvent comprises one or more solvents selected from N,N-dimethylaniline, quinoline, tetrahydrofuran, 2-methyl tetrahydrofuran, benzene, cyclohexane, fluorobenzene, thrifluorobenzene, toluene, xylene, tetraethylene glycol dimethyl ether (tetraglyme), diglyme, isopropanol, ethyl propional, dimethyl carbonate, dimethoxy ether, dimethylpropyleneurea, formamide, methyl formamide, dimethyl formamide, acetamide, methyl acetamide, dimethyl acetamide, triethylamine, diethyl acetamide, ethanol and ethyl acetate, propylene carbonate, ethylene carbonate, and diethyl carbonate. ### Claim 9 (depends on 1) The process according to claim 1, wherein the anolyte solvent comprises from about 60-100 vol. % polar solvent and 0-40 vol. % apolar solvent. ### Claim 10 A process for oxidizing alkali metal polysulfides and monosulfides electrochemically comprising: obtaining a first electrolytic cell comprising an alkali ion conductive membrane configured to selectively transport alkali ions, the membrane separating an anolyte compartment configured with an anode and a catholyte compartment configured with a cathode; introducing into the anolyte compartment 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; introducing into the catholyte compartment a catholyte, wherein the catholyte comprises a molten alkali metal; applying an electric current to the electrolytic cell thereby: i. oxidizing sulfide or polysulfide in the anolyte compartment to form a higher level polysulfide; ii. causing alkali metal ions to pass through the alkali ion conductive membrane from the anolyte compartment to the catholyte compartment; and iii. reducing the alkali metal ions in the catholyte compartment to form elemental alkali metal; transporting anolyte solution from the first electrolytic cell to a second electrolytic cell comprising an alkali ion conductive membrane configured to selectively transport alkali ions, the membrane separating an anolyte compartment configured with an anode and a catholyte compartment configured with a cathode and a catholyte; applying an electric current to the second electrolytic cell thereby: i. oxidizing polysulfide in the anolyte compartment to form liquid elemental sulfur; ii. causing alkali metal ions to pass through the alkali ion conductive membrane from the anolyte compartment to the catholyte compartment; and iii. reducing the alkali metal ions in the catholyte compartment to form liquid elemental alkali metal; allowing liquid elemental sulfur to become saturated in the anolyte solution and to form a second liquid phase. ### Claim 11 (depends on 10) The process according to claim 10 where the liquid elemental sulfur separates from the anolyte solution in a settling zone that is within the electrolytic cell. ### Claim 12 (depends on 10) The process according to claim 10 where the liquid elemental sulfur separates from the anolyte solution in a settling zone that is external to the cell. ### Claim 13 (depends on 10) The process according to claim 10 where the separation of liquid elemental sulfur from the anolyte solution includes one or more of the separation techniques selected from gravimetric, filtration, and centrifugation. ### Claim 14 (depends on 10) The process according to claim 10, wherein the alkali ion conductive membrane is substantially impermeable to anions, the catholyte solvent, the anolyte solvent, and dissolved sulfur. ### Claim 15 (depends on 10) The process according to claim 10, wherein the alkali ion conductive membrane comprises in part an alkali metal conductive ceramic or glass ceramic. ### Claim 16 (depends on 10) The process according to claim 10, wherein the alkali ion conductive membrane comprises a solid MSICON (Metal Super Ion CONducting) material, where M is Na or Li. ### Claim 17 (depends on 10) The process according to claim 10, wherein the anolyte solvent comprises one or more solvents selected from N,N-dimethylaniline, quinoline, tetrahydrofuran, 2-methyl tetrahydrofuran, benzene, cyclohexane, fluorobenzene, thrifluorobenzene, toluene, xylene, tetraethylene glycol dimethyl ether (tetraglyme), diglyme, isopropanol, ethyl propional, dimethyl carbonate, dimethoxy ether, dimethylpropyleneurea, formamide, methyl formamide, dimethyl formamide, acetamide, methyl acetamide, dimethyl acetamide, triethylamine, diethyl acetamide, ethanol and ethyl acetate, propylene carbonate, ethylene carbonate, and diethyl carbonate. ### Claim 18 (depends on 10) The process according to claim 10, wherein the anolyte solvent comprises from about 60-100 vol. % polar solvent and 0-40 vol. % apolar solvent. ### Claim 19 An electrolytic cell for oxidizing alkali metal polysulfides comprising: an anolyte compartment configured with an anode and containing 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, the anolyte compartment further comprising an anolyte solution inlet and an anolyte solution outlet; a catholyte compartment configured with a cathode and containing a catholyte, wherein the catholyte comprises a molten alkali metal, the catholyte compartment further comprising a catholyte outlet; an alkali ion conductive membrane configured to selectively transport alkali ions, wherein the alkali ion conductive membrane is substantially impermeable to anions, the anolyte solvent, and dissolved sulfur; a source of electric potential electrically coupled to the anode and the cathode and configured to: oxidize monosulfide or polysulfide in the anolyte compartment to form liquid elemental sulfur; cause alkali metal ions to pass through the alkali ion conductive membrane from the anolyte compartment to the catholyte compartment; and reduce the alkali metal ions in the catholyte compartment to form liquid elemental alkali metal; and an elemental sulfur settling zone where liquid elemental sulfur separates from the anolyte solution. ### Claim 20 (depends on 19) The electrolytic cell according to claim 19, wherein the alkali ion conductive membrane comprises in part an alkali metal conductive ceramic or glass ceramic. ### Claim 21 (depends on 19) The electrolytic cell according to claim 19, wherein the alkali ion conductive membrane comprises a solid MSICON (Metal Super Ion CONducting) material, where M is Na or Li. ### Claim 22 (depends on 19) The electrolytic cell according to claim 19, wherein the anolyte solvent comprises one or more solvents selected from N,N-dimethylaniline, quinoline, tetrahydrofuran, 2-methyl tetrahydrofuran, benzene, cyclohexane, fluorobenzene, thrifluorobenzene, toluene, xylene, tetraethylene glycol dimethyl ether (tetraglyme), diglyme, isopropanol, ethyl propional, dimethyl carbonate, dimethoxy ether, dimethylpropyleneurea, formamide, methyl formamide, dimethyl formamide, acetamide, methyl acetamide, dimethyl acetamide, triethylamine, diethyl acetamide, ethanol and ethyl acetate, propylene carbonate, ethylene carbonate, and diethyl carbonate. ### Claim 23 (depends on 19) The electrolytic cell according to claim 19, wherein the anolyte solvent comprises from about 60-100 vol. % polar solvent and 0-40 vol. % apolar solvent. ### Claim 24 (depends on 19) The electrolytic cell according to claim 19, further comprising a sulfur outlet for removal of elemental sulfur from the electrolytic cell.