U.S. patent application number 13/504235 was filed with the patent office on 2012-10-25 for spherical electrode and electrolysis cell including same.
This patent application is currently assigned to ELCHEM TECH CO, LTD.. Invention is credited to Yun-Ki Choi, Eun-Soo Kim, Tae-Lim Lee, Sang Bong Moon.
Application Number | 20120267242 13/504235 |
Document ID | / |
Family ID | 43922259 |
Filed Date | 2012-10-25 |
United States Patent
Application |
20120267242 |
Kind Code |
A1 |
Moon; Sang Bong ; et
al. |
October 25, 2012 |
SPHERICAL ELECTRODE AND ELECTROLYSIS CELL INCLUDING SAME
Abstract
The present invention relates to a spherical electrode and to a
spherical electrode cell, and more particularly, to a method for
forming an electrode on an ion-exchange resin or forming an
electrolysis cell on an ion-exchange resin. The spherical electrode
or spherical electrolysis cell of the present invention can be used
for: electrolysis reactors, for example in hydrolysis for producing
hydrogen and oxygen gas; for the production of oxidants by means of
the electrolysis of electrolytes such as a sodium chloride solution
and sodium chlorite; or fuel cells that generate electricity using
oxygen and hydrogen.
Inventors: |
Moon; Sang Bong; (Seoul,
KR) ; Lee; Tae-Lim; (Seoul, KR) ; Kim;
Eun-Soo; (Seoul, KR) ; Choi; Yun-Ki; (Seoul,
KR) |
Assignee: |
ELCHEM TECH CO, LTD.
Seoul
KR
Moon; Sang Bong
Seoul
KR
|
Family ID: |
43922259 |
Appl. No.: |
13/504235 |
Filed: |
November 26, 2009 |
PCT Filed: |
November 26, 2009 |
PCT NO: |
PCT/KR09/07012 |
371 Date: |
July 11, 2012 |
Current U.S.
Class: |
204/290.03 ;
204/290.01; 204/290.11; 204/291 |
Current CPC
Class: |
H01M 4/921 20130101;
C25B 9/00 20130101; H01M 4/8663 20130101; H01M 4/8657 20130101;
H01M 4/925 20130101; H01M 4/90 20130101; C25B 11/02 20130101; Y02E
60/50 20130101; H01M 4/9075 20130101 |
Class at
Publication: |
204/290.03 ;
204/291; 204/290.01; 204/290.11 |
International
Class: |
C25B 11/08 20060101
C25B011/08; C25B 11/02 20060101 C25B011/02; C25B 11/06 20060101
C25B011/06 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 30, 2009 |
KR |
10-2009-0104524 |
Claims
1. An electrode for an electrochemical cell, comprising an
ion-exchange resin matrix and a first electrode layer coated on a
surface of the ion-exchange resin matrix, characterized in that the
electrode has a shape selected from the group consisting of
spheres, granules, beads, grains and fibers.
2. The electrode for an electrochemical cell according to claim 1,
wherein the first electrode layer is coated on 1-100% of a total
surface area of the electrode for an electrochemical cell.
3. The electrode for an electrochemical cell according to claim 2,
which further comprises a second electrode layer, wherein the
second electrode layer is coated on a surface of the ion-exchange
resin matrix, and the first electrode layer is coated on a surface
of the second electrode layer.
4. The electrode for an electrochemical cell according to claim 3,
which further comprises a third electrode layer coated on a surface
of the first electrode layer.
5. The electrode for an electrochemical cell according to claim 3,
wherein the matrix is selected from the group consisting of:
strongly acidic crosslinked polystyrene-divinylbenzene cationic
resins; weakly acidic crosslinked polystyrene-divinylbenzene
cationic resins; iminodiacetic acid-chelated crosslinked
polystyrene-divinylbenzene cationic resins; strongly basic
polystyrene-divinyl benzene anionic resins; weakly basic
polystyrene-divinylbenzene anionic resins; strongly basic/weakly
basic polystyrene-divinylbenzene anionic resins; strongly
basic/weakly basic acrylic anionic resins; strongly acidic
perfluorosulfonated cationic resins; strongly basic
perfluroroaminated anionic resins; natural anion exchangers;
natural cation exchangers; porous inorganic materials; and
combinations thereof, the first electrode layer is selected from
the group consisting of platinum group metals (platinum, ruthenium,
rhodium, palladium, osmium, iridium), as well as gold, silver,
chrome, iron, lead, titanium, manganese, cobalt, nickel,
molybdenum, tungsten, aluminum, silicon, zinc, tin and alloys or
combinations thereof, the second electrode layer is selected from
the group consisting of titanium, silver, copper, tin and alloys or
combinations thereof, and each of the first electrode layer and the
second electrode layer has a thickness of 0.1-5 .mu.m.
6. An electrochemical cell comprising an ion-exchange resin matrix,
a first electrode layer coated on a surface of the ion-exchange
resin matrix, and a second electrode layer coated on the surface of
the ion-exchange resin matrix, characterized in that the electrode
has a shape selected from the group consisting of spheres,
granules, beads, grains and fibers, and the first electrode layer
and the second electrode layer correspond to an anode and a
cathode, respectively, or to a cathode and an anode,
respectively.
7. The electrochemical cell according to claim 6, wherein the first
electrode layer and the second electrode layer have a combined
surface area corresponding to 1-99% of the total surface area of
the electrode chemical cell, and each of the first electrode layer
and the second electrode layer is coated on 0.5-60% of the total
surface area of the electrochemical cell.
8. The electrochemical cell according to claim 7, wherein the
matrix is selected from the group consisting of: strongly acidic
crosslinked polystyrene-divinylbenzene cationic resins; weakly
acidic crosslinked polystyrene-divinylbenzene cationic resins;
iminodiacetic acid-chelated crosslinked polystyrene-divinylbenzene
cationic resins; strongly basic polystyrene-divinylbenzene anionic
resins; weakly basic polystyrene-divinylbenzene anionic resins;
strongly basic/weakly basic polystyrene-divinylbenzene anionic
resins; strongly basic/weakly basic acrylic anionic resins;
strongly acidic perfluorosulfonated cationic resins; strongly basic
perfluroroaminated anionic resins; natural anion exchangers;
natural cation exchangers; porous inorganic materials; and
combinations thereof, the first electrode layer is selected from
the group consisting of platinum group metals (platinum, ruthenium,
rhodium, palladium, osmium, iridium), as well as gold, silver,
chrome, iron, lead, titanium, manganese, cobalt, nickel,
molybdenum, tungsten, aluminum, silicon, zinc, tin and alloys or
combinations thereof, and the first electrode layer has a thickness
of 0.1-5 .mu.m.
Description
TECHNICAL FIELD
[0001] The present invention relates to a spherical cell suitable
for electrolysis of water or an aqueous solution of electrolyte
(e.g. sodium chloride or sodium chlorite) or the like, and to an
electrolysis cell including the same.
BACKGROUND ART
[0002] An electrochemical cell is a kind of energy conversion
system. For example, such electrochemical cells may be classified
into electrolysis cells producing oxygen or hydrogen gas by using
reactants, such as water, or decomposing a solution containing
sodium chloride or sodium chlorite electrolyte, and fuel cells
generating electricity by using oxygen and hydrogen fuel.
[0003] Fundamental constitutional unit elements of an
electrochemical cell include an anode, a cathode and an
electrolyte. FIG. 1 shows a typical electrolysis cell, including an
anode chamber 20 having an anode 10, a cathode chamber 40 having a
cathode 30, and an ion-exchange membrane 50 serving as an
electrolyte transfer medium between the anode and the cathode. The
operation mechanism of such an electrolysis cell will be described
by taking, as an example, an electrolysis cell in which NaClO.sub.2
is supplied to the anode chamber as an electrolyte to produce
chlorine dioxide. The electrolyte, NaClO.sub.2, is supplied to the
anode in the anode chamber, and then is decomposed into chlorine
dioxide (ClO.sub.2) gas, electron (e.sup.-) and sodium ion
(Na.sup.+), while a non-reacted portion is discharged out of the
anode chamber of the electrolysis cell together with chlorine
dioxide (ClO.sub.2) gas. After the decomposition, sodium ion
(Na.sup.+) passes through the ion-exchange membrane 50 and moves
toward the cathode 30 (hydrogen electrode), while electron moves
along an outer path 60 by which the anode 10 and the cathode 30 are
connected with each other. Pure water is supplied to the cathode
chamber 40, and then decomposed at the cathode 30 by the electron
(e'') transferred from the anode 10 (reduction). As a result, pure
water is decomposed into hydrogen (H.sub.2) gas and hydroxide ion.
Hydroxide ion reacts with sodium ion transferred from the anode
chamber 20 through the ion-exchange membrane 50, thereby forming
NaOH. Herein, the electrochemical reactions occurring at the anode
10 and the cathode 30 separately may be represented by the
following Reaction Formulae 1 to 4.
NaClO.sub.2.fwdarw.Na.sup.++ClO.sub.2.sup.- (dissociation of
electrolyte at anode) [Reaction Formula 1]
ClO.sub.2.sup.-.fwdarw.ClO.sub.2 (gas)+e.sup.- (oxidation at anode)
[Reaction Formula 2]
H.sub.2O+e.sup.-.fwdarw.1/2H.sub.2+OH.sup.- (reduction at cathode)
[Reaction Formula 3]
Na.sup.++OH.sup.-.fwdarw.NaOH (production of sodium hydroxide at
cathode) [Reaction Formula 4]
[0004] In addition, the system of FIG. 1 may be applied to
electrochemical decomposition of water to produce hydrogen gas and
oxygen gas. In the system of FIG. 1, water (H.sub.2O) is supplied
to the anode catalyst, and then decomposed into oxygen gas
(O.sub.2), electron (e.sup.-) and proton (H.sup.+) by an
electrochemical reaction. Herein, a portion of water is discharged
out through the product outlet of the electrolysis cell together
with oxygen (O.sub.2) gas. Then, thus decomposed proton (H.sup.+)
passes through the ion-exchange membrane and moves toward the
cathode catalyst (hydrogen electrode), so that it may react with
the electron (e) transferred along an external path (not shown)
connected between the anode catalyst and the cathode catalyst to
produce hydrogen (H.sub.2) gas. Herein, the electrochemical
reactions occurring at the anode catalyst and the cathode catalyst
separately are represented by the following Reaction Formulae 5 and
6.
2H.sub.2O.fwdarw.4H.sup.++4e.sup.-+O.sub.2 (oxidation at anode)
[Reaction Formula 5]
4H.sup.++4e.sup.-.fwdarw.2H.sub.2 (reduction at cathode) [Reaction
Formula 6]
[0005] Meanwhile, in a fuel cell, reactions occur through a
mechanism opposite to the reaction mechanism of the above-described
electrolysis of water. In other words, in a fuel cell, hydrogen,
methanol or other hydrogen fuel sources react with oxygen to
generate electricity. Herein, general reactions occurring in a fuel
cell are represented by the following Reaction Formulae 7 and 8
2H.sub.2.fwdarw.4H.sup.++4e.sup.- (oxidation at anode) [Reaction
Formula 7]
4H.sup.++4e.sup.-+O.sub.2.fwdarw.2H.sub.2O (reduction at cathode)
[Reaction Formula 8]
[0006] In the above-mentioned electrochemical reactions (Reaction
Formulae 2 & 3, Reaction Formulae 5 & 6, and Reaction
Formulae 7 & 8), reactions occur at the interface of an
electrode. At the interface of an electrode, a solid-liquid-gas
three-phase reaction is involved. Particular phenomena involved
herein include provision of an electron transfer path in a solid
portion, transfer of ions to an electrode in a liquid as an
electrolyte, transfer of a product (in the case of a liquid) to a
bulk solution, and transfer of a gas product to a bulk solution in
a gaseous portion. Therefore, to maximize the efficiency of an
electrochemical reaction, it is required to maximize electrolyte
transferability (conductivity), to maximize an electron transfer
path (electrode area), and to maximize gas product transfer
(electrode shape). As a result, a general electrochemical reactor,
in which an electrode having a predetermined space takes a
structure of a plate-like electrode or a mesh-like electrode,
requires stacking of a plurality of electrodes, thereby limiting
significant improvement in its performance.
[0007] FIG. 2 shows another embodiment of a typical electrolysis
cell. In FIG. 2, a spherical electrode 26 is disposed between an
anode 22 and a membrane 28, and between a membrane 28 and a cathode
24. Thus, the area of an electrode in the electrolysis cell is
maximized as compared to the electrolysis cell shown in FIG. 1.
[0008] A particular example of patents related to a spherical
electrode is U.S. Pat. No. 6,024,850 (Title: Modified Ion Exchange
Materials, Applicant: Assignee: Halox technologies Corporation).
The spherical electrode disclosed therein is characterized in that
an ion-exchange resin is used as a matrix and an electrode catalyst
is present in the ion-exchange resin.
[0009] However, such a spherical electrode having an electrode
catalyst in an ion-exchange resin is functionally problematic, as
described hereinafter with reference to FIG. 3 on the basis of the
above-described reaction phenomena occurring at an electrode
surface.
[0010] First, an electrolyte is transferred into an ion-exchange
membrane to cause an electrochemical reaction, thereby causing
degradation of reaction efficiency (this is because diffusion
resistance is too high to transfer ions into the ion-exchange
resin, and it is more difficult to transfer thus generated gas to
the exterior of the ion-exchange resin).
[0011] Second, there is no electron transfer path (specifically,
metal) for the electron formed by the electrochemical reaction in
the ion-exchange resin, thereby increasing electron resistance and
reducing reaction efficiency.
[0012] Moreover, in the case of an electrochemical reaction dealing
with a high-concentration electrolyte, an electrode catalyst may be
discharged, resulting in rapid degradation of durability. The
electrode of the related art includes a structure having an
electrode catalyst containing a counterion at the active site in
the ion-exchange resin. Thus, when electrolyzing a
high-concentration electrolyte, such as saturated brine, the
catalyst ion may be discharged easily. This may be predicted easily
from a regeneration process using brine in a general ion-exchange
resin.
DISCLOSURE
Technical Problem
[0013] The present invention is directed to providing a spherical
electrode structure capable of being filled in an electrolysis cell
and applicable to various conditions including electrolytes or
concentration.
Technical Solution
[0014] In one general aspect, the present invention provides an
electrode for an electrochemical cell including an ion-exchange
resin matrix and a first electrode layer coated on a surface of the
ion-exchange resin matrix, characterized in that the electrode has
a shape selected from the group consisting of spheres, granules,
beads, grains and fibers.
[0015] According to an embodiment, the first electrode layer may be
coated on 1-100% of the total surface area of the electrode for an
electrochemical cell. Particularly, a coating ratio of at least 70%
is preferable in view of overall electrochemical performance or
efficiency.
[0016] According to another embodiment, the electrode for an
electrochemical cell further includes a second electrode layer,
wherein the second electrode layer is coated on a surface of the
ion-exchange resin matrix, and may be provided as a multilayer type
electrode in which the first electrode layer is coated on a surface
of the second electrode layer. In addition, the electrode for an
electrochemical cell may further include a third electrode layer
coated on a surface of the first electrode layer. Such a multilayer
type electrode may exhibit electrode quality equal to or better
than an electrode using a noble metal catalyst, while reducing the
amount of an expensive noble metal catalyst significantly.
[0017] In another general aspect, the present invention provides an
electrochemical cell including an ion-exchange resin matrix, a
first electrode layer coated on a surface of the ion-exchange resin
matrix, and a second electrode layer coated on the surface of the
ion-exchange resin matrix, characterized in that the electrode has
a shape selected from the group consisting of spheres, granules,
beads, grains and fibers, and the first electrode layer and the
second electrode layer correspond to an anode and a cathode,
respectively, or to a cathode and an anode, respectively.
[0018] According to an embodiment, the first electrode layer and
the second electrode layer have a combined surface area
corresponding to 1-99%, particularly 30-90% of the total surface
area of the electrode chemical cell. According to another
embodiment, to provide the above-defined range of combined surface
area, each of the first electrode layer and the second electrode
layer may be coated on 0.5-60% of the total surface area of the
electrochemical cell.
[0019] Particularly, when the first electrode layer and the second
electrode layer have a combined surface area corresponding to
50-70% of the total surface area of the electrochemical cell, and
each of the anode and the cathode is coated in such a manner that
each surface area is 30-35% of the total surface area of the
electrochemical cell, the resultant electrochemical cell is capable
of normal operation even without a short-preventing medium, such as
a non-woven web, between the anode and the cathode.
[0020] Controlling the surface coating degree of the electrode may
be performed easily by those skilled in the art as long as it is
based on the present disclosure.
[0021] The matrix may be selected from the group consisting of:
strongly acidic crosslinked polystyrene-divinylbenzene cationic
resins; weakly acidic crosslinked polystyrene-divinylbenzene
cationic resins; iminodiacetic acid-chelated crosslinked
polystyrene-divinylbenzene cationic resins; strongly basic
polystyrene-divinylbenzene anionic resins; weakly basic
polystyrene-divinylbenzene anionic resins; strongly basic/weakly
basic polystyrene-divinylbenzene anionic resins; strongly
basic/weakly basic acrylic anionic resins; strongly acidic
perfluorosulfonated cationic resins; strongly basic
perfluroroaminated anionic resins; natural anion exchangers;
natural cation exchangers; porous inorganic materials; and
combinations thereof.
[0022] The first electrode layer may be selected from the group
consisting of platinum group metals (platinum, ruthenium, rhodium,
palladium, osmium, iridium), as well as gold, silver, chrome, iron,
lead, titanium, manganese, cobalt, nickel, molybdenum, tungsten,
aluminum, silicon, zinc, tin and alloys or combinations thereof.
The second electrode layer may be selected from the group
consisting of titanium, silver, copper, tin and alloys or
combinations thereof. In addition, the first electrode layer may
have a thickness of 0.1-5 .mu.m.
[0023] In still another general aspect, the present invention
provides a hollow sphere electrode capable of being filled between
an anode and a cathode, between an anode and a membrane, between a
cathode and a membrane, between a membrane and a membrane, or the
like, in an electrolysis cell for an aqueous solution containing an
electrolyte, characterized in that the electrode is filled in such
a manner that the electrode has an area of 1,000-1,000,000 cm.sup.2
per m.sup.3 of volume of the electrolysis cell.
[0024] According to an embodiment, the hollow sphere electrode has
a structure in which a metal is precipitated as an electrochemical
catalyst on a surface of a medium capable of ion exchange in an
amount of 1-100%.
[0025] The electrolysis cell includes a medium capable of ion
exchange, and at least one metal precipitated as an electrochemical
catalyst on a surface of the medium at a ratio of 1-99%.
Advantageous Effects
[0026] The electrode according to an embodiment has an electrode
surface area up to 100 m.sup.2 per m.sup.3 of an electrolysis cell,
and thus maximizes the performance of an electrolysis system, makes
an electrolysis system compact, and reduces manufacturing cost.
DESCRIPTION OF DRAWINGS
[0027] FIG. 1 is a schematic view of a typical electrolysis
cell;
[0028] FIG. 2 is a schematic view showing another typical
electrolysis cell (U.S. Pat. No. 6,024,850 (Title: Modified Ion
Exchange Materials, Applicant: Assignee: Halox Technologies
Corporation);
[0029] FIG. 3 is a schematic view illustrating a problem of the
electrolysis cell as shown in FIG. 2;
[0030] FIG. 4 is a schematic view showing a spherical electrode 400
according to an embodiment of the present invention;
[0031] FIG. 5 is a schematic view showing a spherical electrode 500
having a multilayer type metal layer according to another
embodiment of the present invention;
[0032] FIG. 6 is a schematic view showing a spherical electrode
according to still another embodiment of the present invention;
[0033] FIG. 7 shows a spherical electrochemical cell 700 according
to an embodiment of the present invention;
[0034] FIG. 8 is a scanning electron microscope (SEM) image of a
first Ti coating layer obtained from Example 9;
[0035] FIG. 9 is an SEM image of a second Pt coating layer obtained
from Example 9;
[0036] FIG. 10 is an X-ray diffraction (XRD) image of the sample
obtained from Example 9;
[0037] FIG. 11 is a schematic view showing the electrolysis cell
according to an embodiment of the present invention;
[0038] FIG. 12 is a graph showing the results of comparison of the
electrode of the present invention with the electrode according to
a comparative example in terms of electrolysis voltage;
[0039] FIG. 13 is a graph showing the results of comparison of the
electrode of the present invention with the electrode according to
a comparative example in terms of chlorine concentration;
[0040] FIG. 14 is a graph showing the results of comparison of the
electrode of the present invention with the electrode according to
a comparative example in terms of current efficiency;
[0041] FIG. 15 is a photo showing the spherical electrolysis cell
of FIG. 7; and
[0042] FIG. 16 is a photo showing a magnified view of the interface
of the spherical electrolysis cell of FIG. 10.
BEST MODE
[0043] Hereinafter, the embodiments of the present disclosure will
be described in detail with reference to accompanying drawings.
[0044] FIG. 4 is a schematic view showing a spherical electrode 400
according to an embodiment. As shown in FIG. 4, the spherical
electrode 400 uses an ion exchanger as a matrix 410 and includes an
electrode catalyst 420 on the surface of the matrix. However, the
shape of the matrix is not limited to a particular shape, such as a
spherical shape.
[0045] The matrix 410 may be any medium capable of ion exchange.
Particular examples of the matrix material include: strongly acidic
crosslinked polystyrene-divinylbenzene cationic resins; weakly
acidic crosslinked polystyrene-divinylbenzene cationic resins;
iminodiacetic acid-chelated crosslinked polystyrene-divinylbenzene
cationic resins; strongly basic polystyrene-divinylbenzene anionic
resins; weakly basic polystyrene-divinylbenzene anionic resins;
strongly basic/weakly basic polystyrene-divinylbenzene anionic
resins; strongly basic/weakly basic acrylic anionic resins;
strongly acidic perfluorosulfonated cationic resins; strongly basic
perfluroroaminated anionic resins; natural anion exchangers, such
as clay; natural cation exchangers, such as manganese greensand;
porous inorganic materials, such as zeolite, capable of absorbing
ions; and combinations thereof. Such matrix materials are
commercially available.
[0046] The catalyst 420 coated on the matrix may be selected from
the group consisting of platinum group metals (platinum, ruthenium,
rhodium, palladium, osmium, iridium), as well as gold, silver,
chrome, iron, lead, titanium, manganese, cobalt, nickel,
molybdenum, tungsten, aluminum, silicon, zinc, tin and alloys or
oxides thereof.
[0047] Although there is no limitation in thickness of the
electrode catalyst layer 420, the electrode catalyst layer may have
a thickness of 0.1-5 .mu.m, more particularly 0.1-2 .mu.m. In the
case of a thickness greater than 2 .mu.m, a non-active reaction
layer that does not participate in a reaction becomes too thick,
thereby causing catalyst loss and poor cost efficiency.
[0048] The electrode catalyst layer 420 may have a surface area
covering 1-100% of the surface of the matrix depending on the
particular purpose of electrochemical reaction.
[0049] Methods for forming the electrode catalyst layer on the ion
exchange resin body include chemical methods, such as
adsorption-reduction and electroplating, physical methods, such as
vacuum deposition, etc. However, considering coating on a large
amount of spherical ion exchanger particles, chemical
adsorption-reduction methods may be used. Chemical
adsorption-reduction methods are carried out by allowing an
electrode catalyst material to be adsorbed on an ion exchange resin
and reducing the electrode catalyst material on the surface of the
ion exchange resin. Such methods may be applied and performed
easily by those skilled in the art.
[0050] FIG. 5 shows a spherical electrode 500 having a multilayer
type metal layer according to another embodiment of the present
invention. After forming a first metal layer 520 on the ion
exchange resin matrix 510 as shown in FIG. 4 by an
adsorption-reduction method, or the like, the same or different
metal catalyst layer 530 is further formed on the first metal layer
to provide an electrode having a bilayer structure. The first layer
520 may include a metal, such as titanium, silver, copper or tin,
having excellent electron conductivity. The second layer 530 may
include the electrode catalyst layer as mentioned with reference to
FIG. 4.
[0051] FIG. 6 is a schematic view showing a spherical electrode
according to still another embodiment. The spherical electrode is a
hollow spherical electrode structure obtained by firing the
spherical electrode as shown in FIG. 4 or FIG. 5 at about
800.degree. C. so that the inner ion exchange layer is
pyrolyzed.
[0052] FIG. 7 shows a spherical electrochemical cell 700 according
to an embodiment. As shown in FIG. 7, the sphere functions as a
unit electrolysis cell 700. The spherical electrochemical cell 700
includes fundamental elements of an electrochemical cell, such as
an anode, cathode, electrolyte, or the like. The spherical
electrochemical cell includes an ion conductor matrix 710 as an
electrolyte, a metal 720 having an anodic function (oxidation) as
an anode catalyst, and a metal 730 having a cathodic function
(reduction) as a cathode catalyst. Particular types of the anode
catalyst 720 or cathode catalyst 730 coated on the matrix are the
same as described with reference to FIG. 4. In practice, the metal
forming the anode catalyst 720 may be different from the metal
forming the cathode catalyst 730.
[0053] In the spherical electrochemical cell, the electrode
catalyst layer may have a thickness of 1-5 .mu.m. In the case of a
thickness greater than 5 .mu.m, a non-active reaction layer that
does not participate in a reaction becomes too thick, thereby
causing catalyst loss.
[0054] The surface area (combined surface area of the anode layer
surface with the cathode layer surface) may be within a range of
1-99% depending on the particular purpose of electrochemical
reaction. More particularly, the surface area (combined surface
area of the anode catalyst surface with the cathode catalyst
surface) may be within a range of 30-90%. The surface area that
equals to 100% means a contact between the anode and the cathode,
suggesting a short between the anode and the cathode as a physical
meaning. Thus, in this case, no electrochemical reaction
occurs.
[0055] Methods for forming the anode catalyst metal 720 and the
cathode catalyst metal 730 are the same as described above with
reference to FIG. 4. For example, a metal catalyst as the anode
catalyst metal 720 is formed first partially on the total surface
by an adsorption-reduction method, and then the cathode catalyst
metal 730 is further formed partially on the total surface by an
adsorption-reduction method. Since an adsorption-reduction method
is used, it is possible to form the anode catalyst metal 720 and
the cathode catalyst metal 730 at different positions.
[0056] FIG. 15 is a photo showing the spherical electrolysis cell
of FIG. 7, wherein Pt is used as an anode catalyst metal and Sn is
used as a cathode catalyst metal. FIG. 16 is a photo showing a
magnified view of the interface of the spherical electrolysis cell
of FIG. 10.
MODE FOR INVENTION
[0057] The examples and experiments will now be described. The
following examples and experiments are for illustrative purposes
only and not intended to limit the scope of the present
disclosure.
Examples 1-10
Manufacture of Spherical Electrodes
TABLE-US-00001 [0058] TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Catalyst type
Pt Ru Ni Pd Precursor type Pt(NH.sub.3).sub.6]Cl.sub.4 RuCl.sub.4
NiCl.sub.2 PdCl.sub.2 Precursor 1 mM 1 mM 1 mM 1 mM concentration
Adsorption time 1 hr 1 hr 1 hr 1 hr Reducing agent NaBH.sub.4
NaBH.sub.4 NaBH.sub.4 NaBH.sub.4 type Reducing agent 5% 5% 5% 5%
concentration Reduction time 1 hr 1 hr 1 hr 1 hr Reduction pH 8 8 8
8 Determination of SEM SEM SEM SEM precipitation Result Surface
Surface Surface Surface coating coating coating coating
TABLE-US-00002 TABLE 2 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Catalyst type Ir Pb
Sn Cu Precursor type IrCl.sub.4 Pb(SO.sub.4) SnCl.sub.4 CuSO.sub.4
Precursor 1 mM 1 mM 1 mM 1 mM concentration Adsorption time 1 hr 1
hr 1 hr 1 hr Reducing agent NaBH.sub.4 NaBH.sub.4 NaBH.sub.4
NaBH.sub.4 type Reducing agent 5% 5% 5% 5% concentration Reduction
time 1 hr 1 hr 1 hr 1 hr Reduction pH 8 8 8 8 Determination of SEM
SEM SEM SEM precipitation Result Surface Surface Surface coating
Surface coating coating coating
TABLE-US-00003 TABLE 3 Ex. 9 Ex. 10 Catalyst type Pt/TiO.sub.2 Pt
(Anode), Ni (Cathode) Precursor type TiCl.sub.4(1st)
Pt(NH.sub.3).sub.6]Cl.sub.4NiCl.sub.2 H.sub.2PtCl.sub.6(2nd)
Precursor 1 mM 1 mM/1 mM concentration Adsorption time 1 hr 1 hr
Reducing agent NaBH.sub.4 NaBH.sub.4 type Reducing agent 5% 5%
concentration Reduction time 1 hr 1 hr Reduction pH 8 8
Determination of SEM SEM precipitation Result Surface coating
Surface coating
[0059] FIG. 8 is an SEM image showing the first Ti coating layer
obtained from Example 9. It is shown that Ti is developed well with
a uniform shape.
[0060] FIG. 9 is an SEM image showing the second Pt coating layer
obtained from Example 9. It is shown that Pt is not concentrated
locally but is dispersed uniformly.
[0061] FIG. 10 is an image of the sample obtained from Example 9
taken by XRD analysis. It is shown that Pt, TiO.sub.2 and the like
are formed desirably. It is thought that Ti present in the form of
TiO.sub.2 results from oxide formation with oxygen in water.
Example 11
Preparation of Chlorate Ion Using Spherical Pt/TiO.sub.2 Ion
Exchange Resin (Matrix)
[0062] 1. Manufacture of Spherical Electrode (see Example 9)
[0063] 2. Structure of Electrolysis Cell
[0064] (1) Schematic View of Electrolysis Cell: FIG. 11
[0065] (2) Structural Parameters of Electrolysis Cell
TABLE-US-00004 TABLE 4 Parameter Value Presence of diaphragm No
Distance between anode and 4 mm cathode Type and size of anode
IrO.sub.2--RuO.sub.2 pyrolyzed electrode current collector on Ti, 4
cm .times. 4 cm Type and size of cathode Pt electroplated electrode
on current collector Ti, 4 cm .times. 4 cm Short-preventing member
on Nylon polymer-based nonwoven web with cathode current collector
a porosity of 80% Position of filled electrode Filled in a 4 mm
space between an anode and a cathode
[0066] 3. Operation Condition of Electrolysis Cell
TABLE-US-00005 TABLE 5 Parameter Value Current density 0.1
A/cm.sup.2 Electrolyte 3% aqueous NaCl solution Electrolyte
retention time (min) 10
[0067] 4. Analysis of Performance
[0068] (1) Method of Calculating Current Efficiency
[0069] Current efficiency is obtained by dividing a measured value
of hypochlorous acid generated under an applied current (I) by a
theoretical value according to the following formula:
Current efficiency (%)={(F.times..rho..times.V)/(35500
(mg).times.l.times.t)}.times.100,
[0070] wherein F is the Faraday constant (96500 (C)), .rho. is an
actual residual chlorine concentration (ppm, mg/L), V is a volume
(L) of water supplied to an electrolysis cell, I is an applied
current (A), and t is a time (s) of electrolysis.
[0071] (2) Performance parameters and Determination Methods
TABLE-US-00006 TABLE 6 Analysis Parameter Analysis method interval
(hr) Results Voltage Determined by a 1 hr Expressed as Ex.
multimeter 11 in FIG. 11 Chlorine Iodometry 1 hr Expressed as Ex.
concentration 11 in FIG. 12 Current efficiency Calculated 1 hr
Expressed as Ex. according to 11 in FIG. 13 Formula 1
Comparative Example 1
Preparation of Chlorate Ion Using Known Electrolyte Cell
[0072] 1. Structure of Electrolysis Cell
TABLE-US-00007 TABLE 7 Parameter Value Presence of diaphragm No
Distance between anode and 4 mm cathode Type and size of anode
current IrO.sub.2--RuO.sub.2 pyrolyzed electrode on Ti, collector 4
cm .times. 4 cm Type and size of cathode current Pt electroplated
electrode on Ti, collector 4 cm .times. 4 cm Short-preventing
member on None cathode current collector Position of filled
electrode None
[0073] 2. Operation Condition of Electrolysis Cell
TABLE-US-00008 TABLE 8 Parameter Value Current density 0.1
A/cm.sup.2 Electrolyte 3% aqueous NaCl solution Electrolyte
retention time (min) 10
[0074] 3. Performance Analysis
TABLE-US-00009 TABLE 9 Analysis Parameter Analysis method interval
(hr) Results Voltage Determined by 1 hr Expressed as multimeter
Comp. Ex. 1 in FIG. 11 Chlorine Iodometry 1 hr Expressed as
concentration Comp. Ex. 1 in FIG. 12 Current efficiency Calculated
1 hr Expressed as according to Comp. Ex. 1 in FIG. Formula 1 13
[0075] As shown in FIG. 11, the electrode according to the present
invention has the same electrolysis voltage as the electrode
according to Comparative Example. Referring to FIG. 12, the
electrode according to the present invention has a chlorine
concentration two times higher than a chlorine concentration of the
electrode according to Comparative Example. It is thought that such
a higher current density is derived from a larger electrode area in
the same space and a lower current density at a filled electrode.
FIG. 13 illustrates comparison of the current efficiencies between
the electrode according to the present invention and the electrode
according to Comparative Example. The current density values are
obtained from the results of FIG. 10 and FIG. 11 and the formula of
current density as mentioned in Comparative Example 1.
* * * * *