EP1487747A1 - Electrolyte composition for electrolysis of brine, method for electrolysis of brine, and sodium hydroxide prepared therefrom - Google Patents

Electrolyte composition for electrolysis of brine, method for electrolysis of brine, and sodium hydroxide prepared therefrom

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Publication number
EP1487747A1
EP1487747A1 EP02730968A EP02730968A EP1487747A1 EP 1487747 A1 EP1487747 A1 EP 1487747A1 EP 02730968 A EP02730968 A EP 02730968A EP 02730968 A EP02730968 A EP 02730968A EP 1487747 A1 EP1487747 A1 EP 1487747A1
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EP
European Patent Office
Prior art keywords
brine
electrolysis
aqueous solution
platinum compound
chamber
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Application number
EP02730968A
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German (de)
French (fr)
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EP1487747B1 (en
Inventor
Dae-Sik 207 Hanwha Chemical Corp. Sataek KIM
Hyung-Kwan Kim
Hyung-Mog 1301 Hyubseonghyundai apt. KIM
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Hanwha Chemical Corp
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Hanwha Chemical Corp
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/14—Alkali metal compounds
    • C25B1/16—Hydroxides
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/34—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis
    • C25B1/46—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis in diaphragm cells

Definitions

  • the present invention relates to an electrolyte composition for
  • NaOH sodium hydroxide
  • Methods for preparing sodium hydroxide include a Leblanc process that prepares sodium hydroxide by adding sulfuric acid to crude salt to cause
  • thermolysis an ammonia soda process that prepares sodium hydroxide by
  • the electrolysis process is the most widely used, and it includes a diaphragm process, a mercury process, and an ion-exchange membrane process.
  • a diaphragm process prepares sodium hydroxide by installing a
  • diaphragm made of asbestos between a graphite anode and an iron cathode
  • ion-exchange membrane is installed inside an electrolytic cell to divide the
  • electrolytic cell into a cation chamber and an anion chamber with brine as an
  • Fig. 3 is a cross-sectional view of an apparatus for electrolysis of
  • electrolytic cell (1 1 ) is comprised of a cation chamber (12) and an anion
  • anion chamber (13) is installed therebetween.
  • brine is injected through a brine injection
  • the cation chamber (12) and the anion chamber (13) are respectively
  • anode plate (25) and a cathode plate (26).
  • Fig. 1 shows a chemical equation involved in electrolysis of brine by
  • the electrode plate surface is previously coated or plated with
  • the ion-exchange membrane is
  • Electrode plate are removed and compounds such as AuCI 3 , RuCI 3 , lrCI 3 , etc.
  • the present invention is made in order to solve the problems of the prior arts, and it is an object of the present invention to provide an electrolyte composition for electrolysis of brine comprising an aqueous solution of a
  • brine comprising an aqueous solution of a platinum compound into an
  • electrolytic cell to prepare sodium hydroxide. It is another object of the present invention to provide sodium
  • the present invention provides an
  • electrolyte composition for electrolysis of brine comprising an aqueous
  • the present invention also provides a method for electrolysis of brine
  • the present invention also provides sodium hydroxide prepared by
  • the present invention also provides an apparatus for electrolysis of
  • brine comprising a cation chamber and an anion chamber divided by a
  • cathode plate equipped in the cation chamber and the anion chamber; a brine injection tube connected to the cation chamber; a pure water injection
  • Fig. 1 shows a Chemical Equation involved in electrolysis of brine by
  • Fig. 2 shows a Chemical Equation involved in the electrolysis of brine of the present invention.
  • Fig. 3 is a cross-sectional view of an apparatus for electrolysis of brine
  • Fig. 4 is a cross-sectional view of the apparatus for electrolysis of brine of the present invention.
  • Fig. 5 shows operating voltages of the electrolytic cells of Example 6
  • the platinum compound is preferably selected
  • Fig. 2 shows a chemical equation of electrolysis of brine
  • Saturated brine is injected into a cation chamber, and pure water and a
  • platinum compound aqueous solution are injected into an anion chamber.
  • the liquid mixture of the pure water and the platinum compound aqueous solution is referred to as an electrolytic composition for
  • aqueous solution move to a cathode plate surface.
  • Platinum ions have superior electrical conductivity and corrosion resistance for strong alkali.
  • a cathode plate plated with platinum ions has comparatively low
  • aqueous solution are preferably 0.1 to 10 wt%. If the contents are less than
  • comprising an aqueous solution of the platinum compound is preferably 0.1 to
  • sodium hydroxide will be small, and if the amount is more than 0.2 liter,
  • the method for electrolysis of brine of the present invention which comprises injecting brine and pure water respectively into a cation chamber
  • Fig. 4 is a cross-
  • an electrolytic cell (111) is composed of a cation
  • anion chamber (113), an anode plate (125) and a cathode plate (126) are
  • brine is injected through a brine injection
  • waste brine that remains after reaction and chlorine gas produced during electrolysis are stored in a cation chamber discharge tank (117) after
  • the method for electrolysis of the present invention is characterized by mixing an aqueous solution of a platinum compound with pure water and
  • aqueous solution of the platinum compound is injected through another injection tube of an electrolytic cell or through a platinum compound aqueous solution injection tube connecting with another injection tube, the
  • cathode plate (126) surface is not coated therewith.
  • the platinum compound is preferably selected from a group
  • hexahydroxoplatinate (IV) (H 2 Pt(OH) 6 is most preferable because it is separated into platinum ions, hydrogen ions, and hydroxide ions in an aqueous solution.
  • Fig. 2 shows a chemical equation involved in electrolysis of brine by injecting hydrogen hexahydroxoplatinate (IV) into an electrolytic cell.
  • aqueous solution move to a cathode plate surface by electrodeposition.
  • aqueous solution are preferably 0.1 to 10 wt%. If the contents are less than
  • comprising an aqueous solution of the platinum compound is preferably 0.1 to
  • sodium hydroxide will be small, and if the amount is more than 0.2 liter,
  • the present invention also provides sodium hydroxide prepared by
  • the present invention also provides an apparatus for electrolysis of
  • brine comprising a cation chamber and an anion chamber divided by a
  • electrolytic cell can be reduced, and thus sodium hydroxide can be
  • the total amount of injected pure water was 10 liters, and that of the
  • hexachloroplatinate (IV) aqueous solution was 1 liter.
  • a sodium hydroxide aqueous solution was prepared by the same
  • a sodium hydroxide aqueous solution was prepared by the same
  • a sodium hydroxide aqueous solution was prepared by the same
  • a sodium hydroxide aqueous solution was prepared by the same
  • a sodium hydroxide aqueous solution was prepared by the same method as in Example 1 , except that hydrogen hexahydroxoplatinate (IV) (H 2 Pt(OH) 6 ) was used as a platinum compound.
  • a sodium hydroxide aqueous solution was prepared by the same
  • a sodium hydroxide aqueous solution was prepared by the same
  • a sodium hydroxide aqueous solution was prepared by the same
  • a sodium hydroxide aqueous solution was prepared by the same method as in Example 1 , except that 20 g of lrCI 3 was dissolved in 1 liter of
  • Fig. 5 shows the operating voltages of the electrolytic cells of
  • Example 6 and Comparative Examples 1 to 3 with the lapse of operation time were all set to 6.65 V.
  • brine is electrolyzed using the electrolyte composition for electrolysis of brine comprising a platinum compound aqueous solution and a
  • the electrolysis process is efficient and the cost required for maintenance and repair of an electrolytic cell can be reduced and sodium hydroxide can be

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)

Abstract

The present invention relates to an electrolyte composition for electrolysis of brine, a method for electrolysis of brine, and sodium hydroxide prepared therefrom, and particularly to an electrolyte composition for electrolysis of brine, a method for electrolysis of brine comprising injecting brine and pure water respectively to a cation chamber and an anion chamber divided by a separation membrane installed in an electrolytic cell through a brine injection tube and a pure water injection tube, and applying a power source to an anode plate and a cathode plate installed in the cation chamber and anion chamber to separate produced chloride gas, hydrogen gas, and a sodium hydroxide aqueous solution characterized in that an aqueous solution of a platinum compound is injected into the anion chamber through the pure water injection tube, and sodium hydroxide prepared therefrom.

Description

ELECTROLYTE COMPOSITION FOR ELECTROLYSIS OF BRINE,
METHOD FOR ELECTROLYSIS OF BRINE, AND SODIUM HYDROXIDE
PREPARED THEREFROM
CROSS REFERENCE TO RELATED APPLICATION
This application is based on Korean patent application No. 2002-
0016970 filed in the Korean Intellectual Property Office on March 28, 2002,
and Korean patent application No. 2002-0018673 filed in the Korean
Intellectual Property Office on April 4, 2002, the contents of which are
incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
(a) Field of the Invention ,
The present invention relates to an electrolyte composition for
electrolysis of brine and a method for electrolysis of brine and sodium
hydroxide prepared therefrom, and particularly to an electrolyte composition
for electrolysis of brine and a method for electrolysis of brine which minimize
electric resistance of an electrode plate and thus can reduce power
consumption, do not require separation of an electrolytic cell by interrupting
electrolysis in order to replace an electrode plate and thus makes electrolysis
efficient, and which can reduce the cost required for maintaining and
repairing an electrolytic cell and thus can economically prepare sodium hydroxide, and sodium hydroxide prepared therefrom.
(b) Description of the Related Art
Sodium hydroxide (NaOH) is a pure white solid, and its aqueous
solution shows strong alkalinity. Sodium hydroxide is a widely used material
for preparation of pulp, fiber, dye, rubber, soap, etc., and is widely used for a
desiccant because it has a strong deliquescing property.
Methods for preparing sodium hydroxide include a Leblanc process that prepares sodium hydroxide by adding sulfuric acid to crude salt to cause
thermolysis, an ammonia soda process that prepares sodium hydroxide by
reacting soda lime with Ca(OH)2, and an electrolysis process that prepares sodium hydroxide by electrolyzing brine, etc. Presently, the electrolysis process is the most widely used, and it includes a diaphragm process, a mercury process, and an ion-exchange membrane process.
A diaphragm process prepares sodium hydroxide by installing a
diaphragm made of asbestos between a graphite anode and an iron cathode
so that chlorine coming from the anode may not react with sodium hydroxide coming from the cathode, and a mercury process prepares sodium hydroxide
using mercury as a cathode material. However, the diaphragm process has
a problem of practical use because the concentration of sodium hydroxide
prepared is merely 10 to 13%, and thus the concentration processes must be
repeated several times. The mercury process is not presently used because
of environmental contamination problems of the heavy metal mercury. An ion-exchange membrane process is most widely used, in which an
ion-exchange membrane is installed inside an electrolytic cell to divide the
electrolytic cell into a cation chamber and an anion chamber with brine as an
electrolyte, an anode plate and a cathode plate are respectively installed in
the cation chamber and the anion chamber, and electric power is supplied to
the two electrode plates to obtain chlorine gas from the anode and hydrogen
and sodium hydroxide from the cathode.
Fig. 3 is a cross-sectional view of an apparatus for electrolysis of
brine by an ion-exchange membrane process. As shown in Fig. 3, an
electrolytic cell (1 1 ) is comprised of a cation chamber (12) and an anion
chamber (13), and a membrane (14) dividing the cation chamber (12) and the
anion chamber (13) is installed therebetween.
To the cation chamber (12), brine is injected through a brine injection
tube (15), waste brine that remains after reaction and chlorine gas produced
during electrolysis are stored in an cation chamber discharge tank (17) after
passing through a cation chamber discharge tube (16), chlorine gas is
discharged again through a chlorine gas discharge tube (18), and brine that
remains after reaction and unreacted brine are discharged through a waste
brine discharge tube (19).
Pure water is injected into the anion chamber (13) through a pure
water injection tube (20), and a sodium hydroxide aqueous solution and
hydrogen gas, reactants produced in the anion chamber (13), are stored in an anion chamber discharge tank (22) after passing through an anion
chamber discharge tube (21). Hydrogen gas is discharged again through a
hydrogen gas discharge tube (23), and the sodium hydroxide aqueous
solution is discharged through a sodium hydroxide aqueous solution discharge tube (24).
The cation chamber (12) and the anion chamber (13) are respectively
equipped with an anode plate (25) and a cathode plate (26).
Fig. 1 shows a chemical equation involved in electrolysis of brine by
the existing ion-exchange membrane process. As shown in Fig. 1 , as electrolysis proceeds, hydrogen ions remaining in an anion chamber are
attached to a cathode plate surface to increase electric resistance of a cathode plate, thereby increasing power consumption during electrolysis.
Generally, in order to restrain the increase in resistance of an
electrode plate, the electrode plate surface is previously coated or plated with
compounds such as AuCI3, RuCI3, lrCI3, etc., or it is fired at 400 to 500 °C
and inserted into an electrolytic cell. If electrolyzing brine by the above
method, compounds such as AuCI3, RuCI3, lrCI3, etc. coated or plated on the
electrode plate surface will be continuously oxidized to continuously increase
electric resistance of the electrode plate surface. Therefore, there is a
problem that in proportion to the increased electric resistance, more power is
consumed in electrolysis and the production cost of sodium hydroxide
increases. In order to overcome these problems, the ion-exchange membrane is
replaced every 2 years, the cathode plate every four years, and the anode
plate every 6 years, or compounds such as Au, Ru, Ir, etc. attached to the
electrode plate are removed and compounds such as AuCI3, RuCI3, lrCI3, etc.
are coated or plated again on the electrode plate to renew it. However, the
renewal of an electrode plate requires much time and human and material
resources, and the electrolytic cell cannot be operated during the time
required for renewal, and thus productivity is reduced.
SUMMARY OF THE INVENTION
The present invention is made in order to solve the problems of the prior arts, and it is an object of the present invention to provide an electrolyte composition for electrolysis of brine comprising an aqueous solution of a
platinum compound that minimizes electric resistance of an electrode plate and thus can reduce power consumption, that needs no interruption of
electrolysis to separate an electrolytic cell in order to replace an electrode
plate and thus makes an electrolysis process efficient, and that can reduce the cost required for maintenance and repair of an electrolytic cell to thus
economically prepare sodium hydroxide.
It is another object of the present invention to provide a method for
electrolysis of brine that injects the electrolysis composition for electrolysis of
brine comprising an aqueous solution of a platinum compound into an
electrolytic cell to prepare sodium hydroxide. It is another object of the present invention to provide sodium
hydroxide prepared by the above method.
It is another object of the present invention to provide an apparatus
for electrolysis of brine.
In order to achieve these objects, the present invention provides an
electrolyte composition for electrolysis of brine comprising an aqueous
solution of a platinum compound.
The present invention also provides a method for electrolysis of brine
comprising injecting brine and pure water respectively into a cation chamber and an anion chamber divided by a separation membrane installed inside an
electrolytic cell through a brine injection tube and a pure water injection tube and applying a power source to an anode plate and a cathode plate installed in the cation chamber and the anion chamber to separate produced chlorine gas, hydrogen gas, and sodium hydroxide aqueous solution, characterized in
that an aqueous solution of a platinum compound is injected into the anion
chamber through the pure water injection tube.
The present invention also provides sodium hydroxide prepared by
the above method.
The present invention also provides an apparatus for electrolysis of
brine comprising a cation chamber and an anion chamber divided by a
separation membrane installed in an electrolytic cell; an anode plate and a
cathode plate equipped in the cation chamber and the anion chamber; a brine injection tube connected to the cation chamber; a pure water injection
tube connected to the anion chamber; and a platinum compound aqueous
solution injection tube connected to the pure water injection tube.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows a Chemical Equation involved in electrolysis of brine by
an ion-exchange membrane process.
Fig. 2 shows a Chemical Equation involved in the electrolysis of brine of the present invention.
Fig. 3 is a cross-sectional view of an apparatus for electrolysis of brine
by an ion-exchange membrane process of the prior art.
Fig. 4 is a cross-sectional view of the apparatus for electrolysis of brine of the present invention.
Fig. 5 shows operating voltages of the electrolytic cells of Example 6
and Comparative Examples 1 to 3 with the lapse of operation time.
Explanation of reference numerals in Figures.
11 , 111 : Electrolytic cell
12, 112: Cation chamber
13, 113: Anion chamber
14, 114: Separation membrane
15, 115: Brine injection tube
16, 116: Cation chamber discharge tube 17, 117: Cation chamber discharge tank
18, 118: Chlorine gas discharge tube
19, 119: Waste brine discharge tube
20, 120: Pure water injection tube
21 , 121 : Anion chamber discharge tube
22, 122: Anion chamber discharge tank
23, 123: Hydrogen gas discharge tube
24, 124: Sodium hydroxide aqueous solution discharge tube
25, 125: Anode plate
26, 126: Cathode plate
127: Platinum compound aqueous solution injection tube
DETAILED DESCRIPTION AND THE PREFERRED EMBODIMENTS
The present invention will now be explained in detail.
The present invention is characterized by adding a platinum
compound to an electrolyte composition for electrolysis of brine, particularly in
an aqueous solution phase. The platinum compound is preferably selected
from hexachloroplatinate (IV) (H2PtCI6 • 6H20), potassium
tetrachloroplatinate (II) (K2PtCI4), diaminodinitroplatinum (II) (Pt(NH3)2(NO)2),
hexaaminoplatinum (IV) chloride (Pt(NH3)6CI4), tetraamine platinum (II)
chloride (Pt(NH3)4CI2), hydrogen hexahydroxoplatinate (IV) (H2Pt(OH)6) and
sodium tetrachloroplatinate (II) (Na2PtCI4 • 6H20). Hydrogen hexahydroxoplatinate (IV) (H2Pt(OH)6), separated into platinum ions,
hydrogen ions, and hydroxide ions in an aqueous solution, is most preferable.
Fig. 2 shows a chemical equation of electrolysis of brine when
hydrogen hexahydroxoplatinate (IV) is introduced into an electrolytic cell.
Saturated brine is injected into a cation chamber, and pure water and a
platinum compound aqueous solution are injected into an anion chamber. In
the present invention, the liquid mixture of the pure water and the platinum compound aqueous solution is referred to as an electrolytic composition for
electrolysis of brine.
As shown in Fig. 2, Pt4+ platinum ions in the platinum compound
aqueous solution move to a cathode plate surface. Platinum ions have superior electrical conductivity and corrosion resistance for strong alkali. In addition, a cathode plate plated with platinum ions has comparatively low
electric resistance compared to a cathode plate plated with a material other than platinum ions or an unplated cathode plate, and it also has strong
corrosion resistance to a strong alkali sodium hydroxide aqueous solution
produced in an anion chamber and thus can prevent corrosion of a cathode.
The contents of platinum compounds in the platinum compound
aqueous solution are preferably 0.1 to 10 wt%. If the contents are less than
0.1 wt%, an increase in electric resistance of a cathode plate surface cannot
be prevented, and if the contents are more than 10 wt%, power consumption
will not be simply proportional to the contents of the expensive platinum compounds, thus making it uneconomical.
In addition, the amount of the platinum compound aqueous solution
in the electrolyte composition for electrolysis of brine of the present invention
comprising an aqueous solution of the platinum compound is preferably 0.1 to
0.2 liter per 1 liter of pure water injected into an anion chamber. If the
amount is less than 0.1 liter per 1 liter of pure water, the amount of prepared
sodium hydroxide will be small, and if the amount is more than 0.2 liter,
electric resistance of an electrode plate will not decrease in proportion to the amount of expensive platinum compounds, thus making it uneconomical.
The method for electrolysis of brine of the present invention, which comprises injecting brine and pure water respectively into a cation chamber
and an anion chamber divided by a separation membrane installed in an electrolytic cell through a brine injection tube and a pure water injection tube and applying a power source to an anode plate and a cathode plate installed
in the cation chamber and the anion chamber to separate produced chlorine gas, hydrogen gas, and sodium hydroxide aqueous solution, is characterized
in that an aqueous solution of the platinum compound is injected into the
anion chamber through the pure water injection tube.
An apparatus for electrolysis used in the electrolysis method of the
present invention will be explained referring to Fig. 4. Fig. 4 is a cross-
sectional view of the apparatus for electrolysis of brine of the present
invention. As shown in Fig. 4, an electrolytic cell (111) is composed of a cation
chamber (112) and an anion chamber (113), and a separation membrane
(114) dividing the cation chamber (112) and the anion chamber (113) is
installed therebetween. In addition, inside the cation chamber (112) and the
anion chamber (113), an anode plate (125) and a cathode plate (126) are
respectively installed.
In the cation chamber (112), brine is injected through a brine injection
tube (115), waste brine that remains after reaction and chlorine gas produced during electrolysis are stored in a cation chamber discharge tank (117) after
passing through a cation chamber discharge tube (116), chlorine gas is discharged again through a chlorine gas discharge tube (118), and brine that
remains after reaction and unreacted brine are discharged through a waste brine discharge tube (119).
In the anion chamber (113), pure water is injected through a pure
water injection tube (120), and hydrogen gas and sodium hydroxide aqueous solution, reactants produced in the anion chamber (113), are stored in an
anion chamber discharge tank (122) after passing through an anion chamber
discharge tube (121). Hydrogen gas is discharged again through a
hydrogen gas discharge tube (123), and a sodium hydroxide aqueous
solution is discharged through a sodium hydroxide aqueous solution
discharge tube (124).
The method for electrolysis of the present invention is characterized by mixing an aqueous solution of a platinum compound with pure water and
injecting the mixture in the anion chamber (113). In order to mix the
aqueous solution of the platinum compound with pure water and inject it into
the anion chamber (113), the aqueous solution of the platinum compound is
initially mixed with pure water and the mixture is injected into the pure water
injection tube (120), or a platinum compound aqueous solution injection tube
(127) connecting with the pure water injection tube (120) is separately
installed to inject the aqueous solution of the platinum compound into the anion chamber through the platinum compound aqueous solution injection tube (127).
If the aqueous solution of the platinum compound is injected through another injection tube of an electrolytic cell or through a platinum compound aqueous solution injection tube connecting with another injection tube, the
objects of the present invention cannot be sufficiently achieved. For example, if the platinum compound aqueous solution injection tube is
connected with the anion chamber discharge tube (121) and the aqueous solution of a platinum compound is injected through it, most of the platinum in
the platinum compound aqueous solution is discharged to the anion chamber
discharge tank (1 2) by discharge pressure of the sodium hydroxide aqueous
solution and hydrogen gas discharged from the anion chamber, and thus the
cathode plate (126) surface is not coated therewith.
However, the platinum compound aqueous solution is injected into
the anion chamber (113) through the pure water injection tube (120), the platinum cation ingredient of the platinum compound aqueous solution moves
to the cathode plate (126) by electrodeposition and is coated on the cathode
plate (126), and thus an electric resistance of the cathode plate surface
decreases to reduce power consumption for electrolysis.
The platinum compound is preferably selected from a group
consisting of hexachloroplatinate (IV) (H2PtCI6 • H20), potassium
tetrachloroplatinate (II) (K2PtCI4), diaminodinitroplatinum (II) (Pt(NH3)2(N02),
hexaaminoplatinum (IV) chloride (Pt(NH3)6CI4), tetraamine platinum (II)
chloride (Pt(NH3)4CI2), hydrogen hexahydroxoplatinate (IV) (H2Pt(OH)6), and
sodium tetrachloroplatinate (II) (Na2PtCI4 • 6H20). Hydrogen
hexahydroxoplatinate (IV) (H2Pt(OH)6 is most preferable because it is separated into platinum ions, hydrogen ions, and hydroxide ions in an aqueous solution.
Fig. 2 shows a chemical equation involved in electrolysis of brine by injecting hydrogen hexahydroxoplatinate (IV) into an electrolytic cell. Brine
is injected into a cation chamber, and pure water and a platinum compound aqueous solution are injected into an anion chamber.
As shown in Fig. 2, Pt4+ platinum ions of the platinum compound
aqueous solution move to a cathode plate surface by electrodeposition.
Platinum ions have superior electrical conductivity and corrosion resistance
for strong alkali. In addition, a cathode plate plated with platinum ions has
comparatively low electric resistance compared to a cathode plate plated with a material other than platinum ions or an unplated cathode plate, and it also
has strong corrosion resistance for a strong alkali sodium hydroxide aqueous
solution and thus can prevent corrosion of the cathode plate.
The contents of platinum compounds in the platinum compound
aqueous solution are preferably 0.1 to 10 wt%. If the contents are less than
0.1 wt%, an increase in electric resistance of a cathode plate surface cannot
be prevented, and if the contents are more than 10 wt%, power consumption
will not be simply proportional to the contents of the expensive platinum
compounds, thus making it uneconomical.
In addition, the amount of the platinum compound aqueous solution,
in the electrolyte composition for electrolysis of brine of the present invention
comprising an aqueous solution of the platinum compound is preferably 0.1 to
0.2 liter per 1 liter of pure water injected into an anion chamber. If the
amount is less than 0.1 liter per 1 liter of pure water, the amount of prepared
sodium hydroxide will be small, and if the amount is more than 0.2 liter,
electrical resistance of an electrode plate will not decrease in proportion to
the amount of expensive platinum compounds, thus making it uneconomical.
The present invention also provides sodium hydroxide prepared by
the electrolysis method.
As shown in Fig. 4, if the platinum compound aqueous solution is
injected into the pure water injection tube to electrolyze brine, an aqueous
solution of sodium hydroxide is produced in the anion chamber of the electrolytic cell. As a method for separating sodium hydroxide from the
aqueous solution of sodium hydroxide, any method generally used in the art
can be employed.
The present invention also provides an apparatus for electrolysis of
brine comprising a cation chamber and an anion chamber divided by a
separation membrane in an electrolytic cell; an anode plate and a cathode
plate respectively installed in the cation chamber and the anion chamber; a
brine injection tube connected with the cation chamber; a pure water injection tube connected with the anion chamber; and a platinum compound aqueous
solution injection tube connected with the pure water injection tube.
As explained, if brine is electrolyzed using the electrolyte composition for electrolysis of brine comprising an aqueous solution of a platinum
compound and the method for electrolysis of brine of the present invention, electric resistance of an electrode plate can be minimized to reduce power
consumption, and there is no need to interrupt electrolysis to separate an
electrolytic cell in order to change an electrode plate and thus the electrolysis process is efficient, the cost required for maintenance and repair of an
electrolytic cell can be reduced, and thus sodium hydroxide can be
economically prepared. In addition, the method is environmentally
acceptable because it does not include the heavy metal mercury, as does the
mercury process.
The present invention will be explained in more detail with reference to the following Examples and Comparative Examples. However, these are
to illustrate the present invention and the present invention is not limited to
them.
Example 1
To 1 liter of pure water, 10 g of hexachloroplatinate (IV) (H2PtCI6
• 6H20) were added to prepare an aqueous solution of hexachloroplatinate
(IV). The aqueous solution and pure water were respectively injected into a
platinum compound aqueous solution injection tube and a pure water
injection tube in an electrolytic cell. Brine was injected into the electrolytic
cell and an electrolyte composition comprising the prepared platinum
compound aqueous solution was injected into a cathode circulation tube for 3
minutes to electrolyze brine to prepare a sodium hydroxide aqueous solution.
The total amount of injected pure water was 10 liters, and that of the
hexachloroplatinate (IV) aqueous solution was 1 liter.
Example 2
A sodium hydroxide aqueous solution was prepared by the same
method as in Example 1 , except that potassium tetrachloroplatinate (II)
(K2PtCI4) was used as a platinum compound.
Example 3
A sodium hydroxide aqueous solution was prepared by the same
method as in Example 1 , except that diaminodinitroplatinum (II)
(Pt(NH3)2(NO)2) was used as a platinum compound. Example 4
A sodium hydroxide aqueous solution was prepared by the same
method as in Example 1 , except that hexaaminoplatinum (IV) chloride
(Pt(NH3)6CI4) was used as a platinum compound.
Example 5
A sodium hydroxide aqueous solution was prepared by the same
method as in Example 1 , except that tetraamine platinum (II) chloride (Pt(NH3)4CI2) was used as a platinum compound.
Example 6
A sodium hydroxide aqueous solution was prepared by the same method as in Example 1 , except that hydrogen hexahydroxoplatinate (IV) (H2Pt(OH)6) was used as a platinum compound.
Example 7
A sodium hydroxide aqueous solution was prepared by the same
method as in Example 1 , except that sodium tetrachloroplatinate (II) (Na2PtCI4 6H20) was used as a platinum compound.
Comparative Example 1
A sodium hydroxide aqueous solution was prepared by the same
method as in Example 1 , except that 20 g of AuCI3 were dissolved in 1 liter of
pure water instead of the platinum compound and the aqueous solution
thereof used, and the product AZEC MD66.69, manufactured by Japan Asahi Glass Co., Ltd was used as an electrolytic cell.
Comparative Example 2
A sodium hydroxide aqueous solution was prepared by the same
method as in Example 1 , except that 20 g of RuCI3 was dissolved in 1 liter of
pure water instead of the platinum compound, and the aqueous solution
thereof was used.
Comparative Example 3
A sodium hydroxide aqueous solution was prepared by the same method as in Example 1 , except that 20 g of lrCI3 was dissolved in 1 liter of
pure water instead of the platinum compound, and the aqueous solution thereof was used.
Comparison of operating voltage
Fig. 5 shows the operating voltages of the electrolytic cells of
Example 6 and Comparative Examples 1 to 3 with the lapse of operation time. The initial operating voltages were all set to 6.65 V.
As shown in Fig. 5, when RuCI3 and lrCI3 aqueous solutions of
Comparative Examples 2 and 3 were injected to electrolyze, the operating
voltages of the electrolytic cells gradually increased with the lapse of time.
In addition, when adding the AuCI3 aqueous solution of Comparative Example
1 to electrolyze, the operating voltage increased more than in Comparative
Examples 2 and 3. It is considered that electric resistance of the cathode
plate increased due to Au, Ru, and Ir of the AuCI3, RuCI3, and lrCI3 aqueous solutions injected into the anion chamber with the lapse of the operation time.
However, when the platinum compound aqueous solution of Example
6 was injected into an electrolytic cell to operate the electrolytic cell, the
operating voltage decreased with the lapse of operation time. Particularly,
after 15 minutes of operation, the operating voltage decreased to 6.5 V, and
then stabilized at 6.42 V. This is because platinum cations of the hydrogen
hexahydroxoplatinate (IV) (H2Pt(OH)6) aqueous solution were
electrodeposited on a cathode plate surface by electrodeposition to decrease
electric resistance of the electrode plate surface.
As explained, if the platinum compound aqueous solution of the present invention is injected into a platinum compound aqueous solution
injection tube connected with a pure water injection tube to electrolyze brine, electric resistance of an electrode plate decreases and thus operating voltage decreases, and therefore power consumption for electrolysis can be reduced
and sodium hydroxide can be economically prepared.
If brine is electrolyzed using the electrolyte composition for electrolysis of brine comprising a platinum compound aqueous solution and a
method for electrolysis of brine using the same of the present invention,
electric resistance of an electrode plate is minimized to reduce power
consumption, there is no need to interrupt the electrolysis process to
separate an electrolytic cell in order to replace an electrode plate, and thus
the electrolysis process is efficient and the cost required for maintenance and repair of an electrolytic cell can be reduced and sodium hydroxide can be
economically prepared.

Claims

WHAT IS CLAIMED IS:
1. An electrolyte composition for electrolysis of brine comprising an aqueous
solution of a platinum compound.
2. The electrolyte composition for electrolysis of brine according to Claim 1 ,
wherein the platinum compound is selected from a group consisting of
hexachloroplatinate (IV) (H2PtCI6- 6H20), potassium tetrachloroplatinate (II)
(K2PtCI4), diaminodinitroplatinum (II) (Pt(NH3)2(NO)2), hexaaminoplatinum (IV)
chloride (Pt(NH3)6CI4), tetraamine platinum (II) chloride (Pt(NH3)4CI2), hydrogen hexahydroxoplatinate (IV) (H2Pt(OH)6), and sodium
tetrachloroplatinate (II) (Na2PtCI4- 6H20).
3. The electrolyte composition for electrolysis of brine according to Claim 1 , wherein the contents of the platinum compound in the aqueous solution of the platinum compound are 0.1 to 10 wt%.
4. The electrolyte composition for electrolysis of brine according to Claim 1 , wherein the aqueous solution of the platinum compound is used in the
amount of 0.1 to 2 liters per 1 liter of pure water.
5. A method for electrolysis of brine, comprising injecting brine and pure
water respectively to a cation chamber and an anion chamber divided by a
separation membrane installed in an electrolytic cell through a brine injection
tube and a pure water injection tube, and applying a power source to an
anode plate and a cathode plate installed in the cation chamber and anion
chamber to separate produced chloride gas, hydrogen gas, and sodium hydroxide aqueous solution, characterized in that an aqueous solution of a
platinum compound is injected into the anion chamber through the pure water
injection tube.
6. The method for electrolysis of brine according to Claim 5, wherein the
aqueous solution of the platinum compound is injected through a separate
platinum compound aqueous solution injection tube connected with the pure water injection tube.
7. The method for electrolysis of brine according to Claim 5, wherein the platinum compound is selected from a group consisting of
hexachloroplatinate (IV) (H2PtCI6- 6H20), potassium tetrachloroplatinate (II)
(K2PtCI4), diaminodinitroplatinum (II) (Pt(NH3)2(NO)2), hexaaminoplatinum (IV) chloride (Pt(NH3)6CI4), tetraamine platinum (II) chloride (Pt(NH3)4CI2), hydrogen hexahydroxoplatinate (IV) (H2Pt(OH)6), and sodium
tetrachloroplatinate (II) (Na2PtCI4 • 6H20).
8. The method for electrolysis of brine according to Claim 5, wherein the
contents of the platinum compound in the aqueous solution of the platinum compound are 0.1 to 10 wt%.
9. The method for electrolysis of brine according to Claim 5, wherein the
aqueous solution of the platinum compound is used in an amount of 0.1 to 2
liters per 1 liter of pure water.
10. Sodium hydroxide prepared by the method of any one of Claims 5 to 9.
11. An apparatus for electrolysis of brine, comprising: a cation chamber and an anion chamber divided by a separation
membrane installed in an electrolytic cell;
an anode plate and a cathode plate respectively equipped in the cation
chamber and the anion chamber;
a brine injection tube connected with the cation chamber;
a pure water injection tube connected with the anion chamber; and
a platinum compound aqueous solution injection tube connected with
the pure water injection tube.
EP02730968A 2002-03-28 2002-05-28 Use of an electrolyte composition for electrolysis of brine, method for electrolysis of brine, and for preparation of sodium hydroxide Revoked EP1487747B1 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
KR1020020016970A KR100363011B1 (en) 2002-03-28 2002-03-28 Electrolyte composition for electrolysis of brine and electrolysis method of brine using the same
KR2002016970 2002-03-28
KR1020020018673A KR100363012B1 (en) 2002-03-28 2002-04-04 Electrolysis method of brine and caustic soda prepared therefrom
KR2002018673 2002-04-04
PCT/KR2002/001004 WO2003082749A1 (en) 2002-03-28 2002-05-28 Electrolyte composition for electrolysis of brine, method for electrolysis of brine, and sodium hydroxide prepared therefrom

Publications (2)

Publication Number Publication Date
EP1487747A1 true EP1487747A1 (en) 2004-12-22
EP1487747B1 EP1487747B1 (en) 2006-08-02

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US (1) US20040238373A1 (en)
EP (1) EP1487747B1 (en)
JP (1) JP2005520049A (en)
KR (2) KR100363011B1 (en)
CN (1) CN1309871C (en)
AT (1) ATE334944T1 (en)
AU (1) AU2002303008A1 (en)
DE (1) DE60213671T2 (en)
WO (1) WO2003082749A1 (en)

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EP3597791A1 (en) 2018-07-20 2020-01-22 Covestro Deutschland AG Method for improving the performance of nickel electrodes

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EP1953270A1 (en) 2007-01-24 2008-08-06 Bayer MaterialScience AG Method for improving the performance of nickel electrodes
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ATE334944T1 (en) 2006-08-15
WO2003082749A1 (en) 2003-10-09
JP2005520049A (en) 2005-07-07
KR100363012B1 (en) 2002-11-30
EP1487747B1 (en) 2006-08-02
US20040238373A1 (en) 2004-12-02
DE60213671D1 (en) 2006-09-14
DE60213671T2 (en) 2007-10-04
KR100363011B1 (en) 2002-11-30
CN1309871C (en) 2007-04-11
CN1547557A (en) 2004-11-17
AU2002303008A1 (en) 2003-10-13

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