Method for producing polysulfides by means of electronlytic oxidation

• US 20020053520A1
• Filed: 08/27/2001
• Published: 05/09/2002
• Est. Priority Date: 02/26/1999
• Status: Active Grant

• Current Assignee: Asahi Glass Company, Limited (AGC, Inc.), Kawasaki Kasei Chemicals Ltd. (Air Water Incorporated), Nippon Paper Industries Company Limited (Nippon Paper Group Incorporated)
• Original Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Inventors: Shimohira, Tetsuji, Tanaka, Junji, Watanabe, Keigo, Nanri, Yasunori, Andoh, Tatsuya
• Granted Patent: US 6,517,699 B2
• Time in Patent Office: Days
• US Class Current: 205/414
• CPC Class Codes: C25B 1/00 Electrolytic production of inorganic compounds or non-metals
• CPC Class Codes: C25B 11/031 Porous electrodes
• CPC Class Codes: C25B 11/075 consisting of a single catalytic element or catalytic compound
• CPC Class Codes: C25B 11/089 Alloys
• CPC Class Codes: C25B 15/025 of electrolyte parameters
• CPC Class Codes: C25B 9/13 Single electrolytic cells with circulation of an electrolyte
• CPC Class Codes: C25B 9/19 with diaphragms
• CPC Class Codes: D21C 11/0057 Oxidation of liquors, e.g. in order to reduce the losses of sulfur compounds, followed by evaporation or combustion if the liquor in question is a black liquor deodorisation of gases D21C11/08; combustion D21C11/12, D21C11/14
• CPC Class Codes: D21C 11/0078 Treatment of green or white liquors with other means or other compounds than gases, e.g. in order to separate solid compounds such as sodium chloride and carbonate from these liquors; Further treatment of these compounds fractionating of spent liquors D21C11/0042

Abstract

The present invention has an object to obtain a cooking liquor containing polysulfide-sulfur at a high concentration by minimizing by-production of thiosulfate ions. The present invention is a method for producing polysulfides, which comprises introducing a solution containing sulfide ions into an anode compartment of an electrolytic cell comprising the anode compartment provided with a porous anode, a cathode compartment provided with a cathode, and a diaphragm partitioning the anode compartment and the cathode compartment, for electrolytic oxidation to obtain polysulfide ions, characterized in that the porous anode is disposed so that a space is provided at least partly between the porous anode and the diaphragm, and the apparent volume of the porous anode is from 60% to 99% based on the volume of the anode compartment.

Claims

1. A method for producing polysulfides, which comprises introducing a solution containing sulfide ions into an anode compartment of an electrolytic cell comprising the anode compartment provided with a porous anode, a cathode compartment provided with a cathode, and a diaphragm partitioning the anode compartment and the cathode compartment, for electrolytic oxidation to obtain polysulfide ions, wherein the porous anode is disposed so that a space is provided at least partly between the porous anode and the diaphragm, and the apparent volume of the porous anode is from 60% to 99% based on the volume of the anode compartment.

2. The method for producing polysulfides according to claim 1, wherein the porous anode has a physically continuous three dimensional network structure.

3. The method for producing polysulfides according to claim 2, wherein the porous anode is such that at least its surface is made of nickel or a nickel alloy containing nickel in an amount of at least 50 wt %.

4. The method for producing polysulfides according to claim 1, wherein the surface area of the porous anode is from 2 to 100 m²/m² per effective current-carrying area of the diaphragm.

5. The method for producing polysulfides according to claim 3, wherein the surface area of the porous anode is from 2 to 100 m²/m² per effective current-carrying area of the diaphragm.

6. The method for producing polysulfides according to claim 1, wherein the electrolytic oxidation is carried out under a condition such that the pressure in the anode compartment is higher than the pressure in the cathode compartment.

7. The method for producing polysulfides according to claim 3, wherein the electrolytic oxidation is carried out under a condition such that the pressure in the anode compartment is higher than the pressure in the cathode compartment.

8. The method for producing polysulfides according to claim 4, wherein the electrolytic oxidation is carried out under a condition such that the pressure in the anode compartment is higher than the pressure in the cathode compartment.

9. The method for producing polysulfides according to claim 5, wherein the electrolytic oxidation is carried out under a condition such that the pressure in the anode compartment is higher than the pressure in the cathode compartment.

10. The method for producing polysulfides according to claim 1, wherein the current density in the electrolytic oxidation is from 0.5 to 20 kA/m² per effective current-carrying area.

11. The method for producing polysulfides according to claim 1, wherein the solution containing sulfide ions, is made to pass through the anode compartment at an average superficial velocity of from 1 to 30 cm/sec.

12. The method for producing polysulfides according to claim 1, wherein the solution containing sulfide ions is white liquor or green liquor in a pulp production process.

13. The method for producing polysulfides according to claim 8, wherein the electrolytically oxidized white liquor or green liquor flowing out from the anode compartment is supplied to the next step without recycling it to the anode compartment.