U.S. patent application number 13/329953 was filed with the patent office on 2012-12-20 for device and method for reducing carbon dioxide.
This patent application is currently assigned to Panasonic Corporation. Invention is credited to Masahiro DEGUCHI, Reiko TANIGUCHI, Satoshi YOTSUHASHI, Yuji ZENITANI.
Application Number | 20120318680 13/329953 |
Document ID | / |
Family ID | 45496648 |
Filed Date | 2012-12-20 |
United States Patent
Application |
20120318680 |
Kind Code |
A1 |
ZENITANI; Yuji ; et
al. |
December 20, 2012 |
DEVICE AND METHOD FOR REDUCING CARBON DIOXIDE
Abstract
A device for reducing carbon dioxide includes a vessel for
holding an electrolyte solution including carbon dioxide, a working
electrode and a counter electrode. The working electrode contains
boron particles.
Inventors: |
ZENITANI; Yuji; (Nara,
JP) ; TANIGUCHI; Reiko; (Osaka, JP) ;
YOTSUHASHI; Satoshi; (Osaka, JP) ; DEGUCHI;
Masahiro; (Osaka, JP) |
Assignee: |
Panasonic Corporation
Osaka
JP
|
Family ID: |
45496648 |
Appl. No.: |
13/329953 |
Filed: |
December 19, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2011/001521 |
Mar 15, 2011 |
|
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13329953 |
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Current U.S.
Class: |
205/455 ;
205/334; 205/462 |
Current CPC
Class: |
C25B 11/0447 20130101;
C25B 3/04 20130101 |
Class at
Publication: |
205/455 ;
205/334; 205/462 |
International
Class: |
C25B 3/04 20060101
C25B003/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 23, 2010 |
JP |
2010-165649 |
Claims
1. A method for reducing carbon dioxide by using a device for
reducing carbon dioxide, the method comprising: a step (a) of
preparing the device, the device comprising: a vessel; a working
electrode, and a counter electrode, wherein: an electrolytic
solution is held in the vessel, the working electrode is composed
of a conductive base material on which a boron particle is
supported, the counter electrode contains metal, the boron is in
contact with the electrolytic solution, the metal is in contact
with the electrolytic solution, and the electrolytic solution
contains the carbon dioxide; and a step (b) of applying a voltage
between the working electrode and the counter electrode, thereby
reducing the carbon dioxide contained in the electrolytic
solution.
2. The method according to claim 1, wherein: the vessel comprises a
solid electrolyte membrane, and the solid electrolyte membrane is
interposed between the working electrode and the counter
electrode.
3. The method according to claim 1, wherein in the step (b), the
voltage applied between the working electrode and the counter
electrode is not less than 2.0 volts.
4. The method according to claim 1, wherein in the step (b), at
least one of methane, ethylene, ethan, and formic acid is
generated.
5-11. (canceled)
12. The method according to claim 1, wherein the conductive base
material is a carbon paper, a noble-metal substrate, a glassy
carbon substrate, or a conductive silicon substrate.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of PCT Application No.
PCT/JP2011/001521 filed on Mar. 15, 2011, claiming priority of
Japanese Patent Application No. 2010-165649 filed on Jul. 23, 2010,
the entire contents of each of which are incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present disclosure relates to a device and a method for
reducing carbon dioxide.
SUMMARY
[0003] One of the purposes of the present disclosure is to provide
a novel device and method for reducing carbon dioxide.
[0004] One example of the present disclosure is a device for
reducing carbon dioxide. The device includes a vessel for holding
an electrolyte solution including carbon dioxide, a working
electrode and a counter electrode. The working electrode contains
boron.
[0005] In the above device, the counter electrode may contain one
of platinum, gold, silver, copper, nickel and titanium.
[0006] In any of the above devices, the working electrode may
contain boron particles disposed on a substrate. The substrate may
be a carbon paper, a noble metal substrate, a glassy carbon
substrate or a conductive silicon substrate.
[0007] Any of the above devices may optionally include a solid
electrolyte membrane interposed between the working electrode and
the counter electrode. Further, any of the above devices may
optionally include a reference electrode.
[0008] Another example of the present disclosure is a method for
reducing carbon dioxide by using any of the above devices for
reducing carbon dioxide. The method includes a step (a) of
preparing any one of the aforementioned devices. An electrolytic
solution is held in the vessel, the boron in the working electrode
is in contact with the electrolytic solution, the metal in the
counter electrode is in contact with the electrolytic solution, and
the electrolytic solution contains the carbon dioxide. The method
further includes a step (b) of applying a voltage between the
working electrode and the counter electrode, thereby reducing the
carbon dioxide contained in the electrolytic solution.
[0009] In the above method, in the step (b), the voltage applied
between the working electrode and the counter electrode is not less
than 2.0 volts. In the step (b), at least one of methane, ethylene,
ethan, and formic acid is generated.
[0010] The present disclosure can provide a novel device and method
for reducing carbon dioxide.
BRIEF DESCRIPTION OF DRAWINGS
[0011] FIG. 1 shows an exemplary device for reducing carbon dioxide
according to the embodiment 1.
[0012] FIG. 2 shows a graph of the result of the reaction
current-electric field potential measurement (C-V measurement) in
the example 1.
[0013] FIG. 3 shows a graph of the result of the gas chromatography
in the example
[0014] FIG. 4 shows a graph of the result of the liquid
chromatography in the example 1.
DESCRIPTION OF EMBODIMENTS
[0015] One exemplary embodiment of the present disclosure is
described below.
(Step (a))
[0016] In step (a), a device for reducing carbon dioxide is
prepared. As shown in FIG. 1, the device includes a vessel 21, a
working electrode 11, and a counter electrode 13. An electrolytic
solution 15 is held in the vessel 21. An example of the
electrolytic solution 15 is a potassium hydrogen carbonate aqueous
solution. The electrolytic solution 15 contains carbon dioxide. It
is preferable that the electrolytic solution 15 is mild acidic in
the condition where carbon dioxide is dissolved in the electrolytic
solution 15.
[0017] The working electrode 11 contains boron. The working
electrode 11 may be fabricated as follows. First, boron particles
are dispersed in an organic solvent to form slurry. Next, the
slurry is applied to a porous conductive base material to obtain a
working electrode. This base material preferably has a shape of a
film. An example of the base material includes a carbon paper, a
noble metal substrate, a glassy carbon substrate, and a conductive
silicon substrate.
[0018] The working electrode may be formed by a sputtering
method.
[0019] The working electrode 11 is in contact with the electrolytic
solution 15. To be exact, the boron included in the working
electrode 11 is in contact with the electrolytic solution 15. As
shown in FIG. 1, the working electrode 11 is immersed in the
electrolytic solution 15. As long as the boron is in contact with
the electrolytic solution 15, only a part of the working electrode
11 may be immersed in the electrolytic solution 15.
[0020] The counter electrode contains metal. An example of the
preferred metal includes platinum, gold, silver, copper, nickel,
and titanium. As long as the metal is not electrolyzed, the
material of the metal is not limited.
[0021] The counter electrode 13 is in contact with the electrolytic
solution 15. To be exact, the metal of the counter electrode 13 is
in contact with the electrolytic solution 15. As shown in FIG. 1,
the counter electrode 13 is immersed in the electrolytic solution
15. As long as the metal is in contact with the electrolytic
solution 15, only a part of the counter electrode 13 may be
immersed in the electrolytic solution 15.
[0022] As shown in FIG. 1, it is preferable that the vessel 21
includes a tube 17. Carbon dioxide is supplied through the tube 17
to the electrolytic solution 15. One end of the tube 17 is immersed
in the electrolytic solution 15.
[0023] It is preferred that a solid electrolyte membrane 16 is
provided in the vessel 21. The reason for providing the solid
electrolyte membrane 16 is described later in step (b). The solid
electrolyte membrane 16 is interposed between the working electrode
11 and the counter electrode 13 to divide the electrolytic solution
15 into a first liquid 15L and a second liquid 15R. The counter
electrode 13 is in contact with the first liquid 15L. The working
electrode is in contact with the second liquid 15R.
(Step (b))
[0024] In step (b), a negative voltage and a positive voltage are
applied to the working electrode 11 and the counter electrode 13,
respectively. This causes the carbon dioxide contained in the
electrolytic solution 15 (to be exact, the second liquid 15R) to be
reduced on the working electrode 11. As a result, at lease one
selected from carbon monoxide, formic acid, and methane is
generated on the working electrode 11. On the counter electrode 13,
water is oxidized to form oxygen.
[0025] It is preferred to use a potentiostat 14 to apply a
potential difference is applied between the working electrode 11
and the counter electrode 13.
[0026] The potential difference applied between the working
electrode 11 and the counter electrode 13 is preferably not less
than 2.0 volts. This corresponds to the fact that carbon dioxide
reducing current is measured at not more than -0.7 volts (and not
less than -1.5 volts) in the example 1, which is described
later.
[0027] In the preferable embodiment, the solid electrolyte membrane
16 is provided. Only a proton penetrates the solid electrolyte
membrane 16. An example of the solid electrolyte membrane 16
includes a Nafion (Registered Trade Mark) film, which is available
from Dupont Kabushiki Kaisha.
[0028] The solid electrolyte membrane 16 prevents a reverse
reaction on the counter electrode 13. Namely, when the carbon
monoxide, formic acid, or methane, which is generated on the
working electrode 11, reaches the counter electrode 13, it is
oxidized on the counter electrode 13 and returns to carbon dioxide.
The solid electrolyte membrane 16 prevents this reverse
reaction.
[0029] As shown in FIG. 1, it is preferred that a reference
electrode 12 is provided. The reference electrode 12 is in contact
with the electrolytic solution 15. When the solid electrolyte
membrane 16 is used, the reference electrode 12 is in contact with
the second liquid 15R. The reference electrode 12 is electrically
connected to the working electrode 11. An example of the reference
electrode 12 is a silver/silver chloride electrode.
[0030] The present device and method is described in more detail by
the following example.
Example 1
[0031] Particles of boron (B particle, Mitsuwa Chemicals Co., Ltd,
purity of 96%) having an average particle size of 8 microns are
disposed, with a distribution density of 1.times.10.sup.7
particle/cm.sup.2, on a conductive carbon paper (CP) having a
thickness of 0.5 mm, thereby making an electrode catalyst (working
electrode) according to the present subject matter.
[0032] Using this electrode catalyst, electrochemical reducing
reaction of CO.sub.2 was performed.
[0033] FIG. 1 shows a structural drawing of the electrochemical
cell used for this measurement.
[0034] The electrochemical cell includes three electrodes, i.e.,
the boron particle supported electrode as set forth above as the
working electrode 11, a silver/silver chloride electrode (Ag/AgCl
electrode) as the reference electrode 12, and a platinum electrode
(Pt-electrode) as the counter electrode 13.
[0035] The electric potential applied to the electrode was changed
by using potensiostat 14, and the reducing reaction of CO.sub.2 was
performed and evaluated.
[0036] An electrolyte 15, 0.1M potassium bicarbonate aqueous
solution (KHCO.sub.3 aqueous solution) was used.
[0037] The working electrode 11 and the counter electrode 13 were
partitioned off with a solid electrolyte membrane 16 to prevent the
gases produced by catalytic reaction from being mixed.
[0038] CO.sub.2 gas was introduced into the electrolyte 15 through
the gas introduction tube 17 arranged in the vessel 21 by being
bubbled in a KHCO.sub.3 electrolytic solution 15.
[0039] First of all, (1) nitrogen gas was introduced into and
electrolyte for 30 minutes with a flow rate of 200 ml/min, keeping
a bubbling state to exclude CO.sub.2 from the electrolyte solution.
Under this condition, the electric potential was changed, and a
curve of reaction electric current-electrolysis voltage (C-V curve)
was measured.
[0040] Next, (2) the gas was switched from nitrogen to CO.sub.2 and
the CO.sub.2 gas was introduced into the electrolyte 15 for 30
minutes with the same flow rate of 200 ml/min so that the
electrolyte 15 was saturated with CO.sub.2. Under this condition,
the electric potential was changed, and C-V curve was measured.
[0041] A reaction electric current by CO.sub.2 reducing reaction
was evaluated by taking a difference between the C-V curve in the
state (2) (the state saturated with CO.sub.2) and the C-V curve in
the state (1) (the state that CO.sub.2 was excluded).
[0042] FIG. 2 shows the result of the difference between the two
curves.
[0043] In this figure, the state that the current value (vertical
axis) is negative shows that CO.sub.2 reducing reaction has
occurred.
[0044] As shown in FIG. 2, at the applied voltage is around -0.7V,
a reaction electric current changes from zero to negatively in the
experimental result of this example.
[0045] In other words, when the electrode catalyst including B
particles is use, the reducing electric current of CO.sub.2 was
observed at the voltage of approximately -0.7V with respect to the
silver/silver chloride electrode (Ag/AgCl electrode) as the
reference electrode.
[0046] This result means that reducing reaction has started at
about -0.5V in a case using the standard hydrogen-electrode.
[0047] On the other hand, when a CO.sub.2 reducing experiment was
conducted with an electrode catalyst of Cu in the same measurement
system, the voltage smaller than -1.1 V (i.e., larger in the
absolute value) was necessary to cause the reducing reaction of
CO.sub.2. This comparison shows that that electrode catalyst which
includes boron is effective in reduction of voltage for reducing
reaction of CO.sub.2.
[0048] Next, the product of reducing reaction of CO.sub.2 using the
electrode on which the B particle was supported gave was
analyzed.
[0049] For the analysis of the gas components, gas chromatograph of
the hydrogen flame ion detector (FID) method was employed, and for
the analysis of liquid components, a liquid chromatograph of the UV
detection method was employed.
[0050] FIG. 3 shows the measurement result of detected methane
(CH.sub.4), ethylene (C.sub.2H.sub.4) and ethan (C.sub.2H.sub.6)
with a gas chromatograph of FID.
[0051] By using a separate column of PrapakQ and controlling a
valve with a predetermined time-sequence, the FID gas chromatograph
is programmed so that CH.sub.4 is detected at around 1.5 minutes
after the start of the measurement, C.sub.2H.sub.4 is detected at
around 4.5 minutes, and C.sub.2H.sub.6 is detected at around 6.5
minutes, respectively.
[0052] As a result, the peaks of voltage were observed by time
domain which corresponds to those as shown in FIG. 3, and it was
confirmed that CH.sub.4, C.sub.2H.sub.4 and C.sub.2H.sub.6 were
generated.
[0053] The measurement result of formic acid (HCOOH) by the liquid
chromatograph is shown in FIG. 4.
[0054] By using a column of TSKgel SCX-H+, the liquid chromatograph
was set so that a peak in HCOOH might be detected around 11.5
minutes after start of the measurement.
[0055] As a result, as shown in FIG. 4, a peak of the voltage was
observed in the range corresponding to this time.
[0056] As a result, it was confirmed that HCOOH was generated by
the reducing reaction of CO.sub.2 by using the electrode catalyst
that includes B particle. As set forth above, the generation of
methane (CH.sub.4), ethylene (C.sub.2H.sub.4), Ethan
(C.sub.2H.sub.6) and formic acid (HCOOH) were confirmed finally by
the results of analysis of the product produced by catalytic
reaction.
Comparative Example 1
[0057] For a comparison, electrolytic reaction was measured with
only the carbon paper (CP) which was used to support a boron
particle. As a result, electric current by reducing reaction of
CO.sub.2 was not observed and it was confirmed that CP was inactive
for reducing of CO.sub.2. The product by electrolytic reaction was
only hydrogen (H.sub.2).
Comparative Example 2
[0058] For another comparison, electrolytic reaction was measured
with Silicon (Si) substrate. As a result, hydrogen (H.sub.2) was a
main product as for the product by the electrolysis reaction, and
hydrocarbon or formic acid (HCOOH) was not generated.
INDUSTRIAL APPLICABILITY
[0059] The present device and method provide a novel method for
reducing carbon dioxide.
* * * * *