Method for producing polysulfides by electrolytic oxidation

A polysulfide and electrolytic cell technology, which is used in the field of preparing polysulfide cooking liquid

Inactive Publication Date: 2002-04-10
KAWASAKI KASEI CHEMICALS LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in this air oxidation process, thiosulfate ions may be formed through side reactions (e.g. Equations 2 and 3), which are useless for pulp cooking
Therefore, it was usually difficult to produce polysulfide cooking liquor with high PS-S concentration at high selectivity in the past

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] A nickel plate was used as the anode current collector, a carbon fiber felt (carbon felt) was used as the anode, a Raney nickel electrode was used as the cathode, and a fluorinated cation exchange membrane (trade name Fremion, manufactured by Asahi Glass Company Ltd.) was used as the diaphragm to assemble A two-compartment electrolytic cell. The anode chamber and the cathode chamber are cuboids of the same size (100mm high, 20mm wide, 5mm thick), and the diaphragm area is 20cm 2 . The carbon fiber felt used as the anode has a size of 100 mm × 20 mm, and its initial thickness is 8 mm. The carbon fiber felt is filled in the anode chamber, and then the cathode is squeezed from the side of the cathode chamber to the diaphragm so that the thickness of the carbon fiber felt becomes 5 mm.

[0038] The physical properties of the anode thus filled into the anode compartment are as follows:

[0039] Carbon fiber diameter: 12μm

[0040] Surface area relative to diaphragm area:...

Embodiment 2

[0050] Carry out constant current electrolysis in the same manner as in Example 1, the difference is: the current is changed to 12A (current density per unit diaphragm area: 6kA / m 2 ), the flow rate of the anolyte was changed to 120ml / min. As shown in table 2, after operating for 90 minutes, the polysulfide solution that obtains PS-S concentration is 10.5g / l, and the selectivity of this moment is 94%, and current efficiency is 88%, and divalent polysulfide ion (S x 2- ) has an average value of x of 2.9.

[0051] Electrolysis time

Embodiment 3

[0053] Carry out constant current electrolysis in the same manner as in Example 1, the difference is: the current is changed to 16A (current density per unit diaphragm area: 8kA / m 2 ), the flow rate of the anolyte was changed to 170ml / min. As shown in table 3, after visible operation 75 minutes, obtain PS-S concentration and be the polysulfide solution of 11g / l, the selectivity of this moment is 91%, and current efficiency is 84%, divalent polysulfide ion (S x 2- ) has an average value of x of 3.3.

[0054] Electrolysis time

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Abstract

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, of which at least the surface is made of carbon, a cathode compartment provided with a cathode, and a diaphragm partitioning the anode compartment and the cathode compartment, and carrying out electrolytic oxidation to obtain polysulfide ions.

Description

technical field [0001] The invention relates to a method for producing polysulfides by electrolytic oxidation, in particular to a method for preparing polysulfide cooking liquor by electrolytic oxidation of white liquor during pulp production. Background technique [0002] It is very important to increase the yield of chemical pulp for efficient utilization of wood resources. Polysulfide cooking is a technique used to increase the yield of kraft pulp, the most commonly used type of chemical pulp. [0003] The cooking liquid used in the polysulfide cooking method is prepared as follows: in the presence of a catalyst (such as activated carbon), molecular oxygen (such as air) is used to oxidize an alkaline aqueous solution containing sodium sulfide (that is, the so-called white liquor), such as Reaction Formula 1, (JP-A-61-259754 and JP-A-53-92981). By this method, polysulfide cooking liquid can be obtained with a selectivity of about 60% and a conversion rate ...

Claims

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Application Information

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IPC IPC(8): C01B17/34C25B1/00C25B1/22D21C11/00D21C11/04
CPCD21C11/0078D21C11/0057
Inventor安藤达也下平哲司远藤荣治
OwnerKAWASAKI KASEI CHEMICALS LTD