PROCESS FOR RECOVERING ALKALI METALS AND SULFUR FROM ALKALI METAL SULFIDES AND POLYSULFIDES

摘要

Alkali metals and sulfur may be recovered from an oil desulfurization process which utilized alkali metal 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.

主权项

1. A process for electrochemically oxidizing alkali metal monosulfides and polysulfides obtained from an oil desulfurization process comprising:
separating one or more solids containing at least one of the alkali metal monosulfides and alkali metal polysulfides from a liquid comprising the solids; thermally treating the solids in a nonoxidizing environment; adding the thermally treated solids to a solvent to at least partially dissolve at least one of the alkali metal monosulfides and alkali metal polysulfides to create a plurality of alkali ions and at least one of a sulfide and a polysulfide; 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 anolyte solvent that partially dissolves elemental sulfur, the plurality of alkali ions and at least one of a sulfide and a polysulfide; 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 at least one of a sulfide and a polysulfide in the anolyte compartment to form liquid elemental sulfur;ii. causing the plurality of alkali ions to pass through the alkali ion conductive membrane from the anolyte compartment to the catholyte compartment; andiii. reducing the plurality of alkali 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.