AU2024201352B2

AU2024201352B2 - Electrochemical reaction device and method of operating electrochemical reaction device

Info

Publication number: AU2024201352B2
Application number: AU2024201352A
Authority: AU
Inventors: Naoya Fujiwara; Ryota Kitagawa; Yusuke Kofuji; Yuki Kudo; Satoshi Mikoshiba
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2023-09-15
Filing date: 2024-02-29
Publication date: 2026-01-08
Anticipated expiration: 2044-02-29
Also published as: EP4524291A3; EP4524291A2; JP2025042780A; CN119640291A; US20250092536A1; AU2024201352A1

Abstract

47 An electrochemical reaction device includes: a structure that includes: a cathode; an anode; a diaphragm, a cathode chamber; and an anode chamber; a first to a fourth flow path through which a first to fourth fluid flows respectively; at least one controller selected from a first and a second flow rate controller, a first and a second pressure controller, a 5 temperature controller and a power supply, the controller including the first flow rate controller; a gas/liquid separator in the middle of the fourth flow path; a first flowmeter that measures a flow rate of the third fluid; a second flowmeter that measures a flow rate of the fourth fluid; and a control device that measures the sum of the flow rates of the first, third and fourth fluids and controls the controller according to the sum to control a pressure 10 difference between the chambers.

Description

TECHNICAL FIELD

[0001] Embodiments relate to an electrochemical reaction device.

BACKGROUND

5 [0002] In recent years, fossil fuels such as petroleum and coal may be depleted, and

alternately sustainable renewable energy has been increasingly expected. Such energy 2024201352

problems and environmental problems motivate to develop a Power to Chemicals (P2C)

technology to electrochemically reduce carbon dioxide using the renewable energy such as

sunlight or the like to generate a storable chemical energy source. Electrolytic devices

10 with the P2C technology are included in the electrochemical reaction devices such as

carbon dioxide reaction devices, the carbon dioxide reaction devices include for example,

an anode to oxidize water (H2O) to produce oxygen (O2) and a cathode to reduce carbon

dioxide (CO2) to produce a carbon compound. The anode and the cathode of the carbon

dioxide reaction device are connected to a power supply using renewable energy such as

15 solar power generation, hydroelectric power generation, wind power generation,

geothermal power generation, or the like.

[0003] The cathode of the carbon dioxide reaction device is arranged, for example, to be

immersed in water containing dissolved carbon dioxide or to be in contact with carbon

dioxide flowing through a flow path. The cathode obtains reduction potential for carbon

20 dioxide from the power supply derived from renewable energy and thereby reduces carbon

dioxide to produce carbon compounds such as carbon monoxide (CO), formic acid

(HCOOH), methanol (CH3OH), methane (CH4), ethanol (C2H5OH), ethane (C2H6),

ethylene (C2H4), formaldehyde (HCHO), ethylene glycol (C2H6O2), acetic acid

(CH3COOH), and propanol (C3H7OH). The anode is arranged to be in contact with an

25 electrolytic solution containing water and produces oxygen and a hydrogen ion (H +). Such

a carbon dioxide reaction device is required to increase the use efficiency of carbon

dioxide, as well as the use efficiency and the utility value of reduction products of carbon

dioxide.

[0004] It is desired to address or alleviate one or more disadvantages or limitations of the

prior art, or to at least provide a useful alternative, such as by increasing the use efficiency

of carbon dioxide.

5 RELEVANT REFERENCES Patent Reference 2024201352

[0005] Reference 1: JP 2019-506165 A

Reference 2: JP 2018-070936 A

Reference 3: JP 2021-46574 A

10

SUMMARY

[0006] One or more embodiments of the present invention comprise an electrochemical

reaction device comprising: an electrochemical reaction structure that includes: a cathode

having a reduction catalyst that promotes a reduction reaction of reducing carbon dioxide

15 to produce a carbon compound; an anode having an oxidation catalyst that promotes an

oxidation reaction of oxidizing water to produce oxygen; a diaphragm between the cathode

and the anode, a cathode chamber facing on the cathode; and an anode chamber facing on

the anode; a first flow path through which a first fluid flows, the first flow path being

connected to an inlet of the cathode chamber, and the first fluid being supplied to the

20 cathode chamber and containing the carbon dioxide; a second flow path through which a

second fluid flows, the second flow path being connected to an inlet of the anode chamber,

the second fluid being supplied to the anode chamber and containing the water; a third

flow path through which a third fluid flows, the third flow path being connected to an

outlet of the cathode chamber, and the third fluid being discharged from the cathode

25 chamber and containing the carbon compound; a fourth flow path through which a fourth

fluid flows, the fourth flow path being connected to an outlet of the anode chamber, and

the fourth fluid being discharged from the anode chamber and containing the water and the

oxygen; at least one controller selected from the group consisting of a first flow rate

controller, a second flow rate controller, a first pressure controller, a second pressure

controller, a temperature controller and a power supply, the first flow rate controller being

configured to measure and control a flow rate of the first fluid flowing through the first

flow path, the second flow rate controller being configured to measure and control a flow

rate of the second fluid flowing through the second flow path, the first pressure controller

5 being configured to control a pressure of the third flow path, the second pressure controller

being configured to control a pressure of the fourth flow path, the temperature controller 2024201352

being configured to control a temperature of the electrochemical reaction structure, and the

power supply being configured to control a current or a voltage to be supplied to the

electrochemical reaction structure, the at least one controller including the first flow rate

10 controller; a gas/liquid separator provided in the middle of the fourth flow path and

configured to process the fourth fluid to separate a liquid containing the water from the

fourth fluid; a first flowmeter configured to measure a flow rate of the third fluid flowing

through the third flow path; a second flowmeter configured to measure a flow rate of the

processed fourth fluid flowing through the fourth flow path; and a control device

15 connected to the at least one controller, the first flowmeter and the second flowmeter, the

control device being configured to measure a sum of the flow rate of the first fluid flowing

through the first flow path, the flow rate of the third fluid flowing through the third flow

path, and the flow rate of the processed fourth fluid flowing through the fourth flow path,

and being configured to control the at least one controller according to the sum to control a

20 pressure difference between the cathode chamber and the anode chamber.

[0006a] Further embodiments of the present invention comprise an electrochemical

reaction device comprising: an electrochemical reaction structure comprising: a cathode

to produce a carbon compound; an anode having an oxidation catalyst that promotes an

25 oxidation reaction of oxidizing water to produce oxygen; a diaphragm between the cathode

cathode chamber and containing the carbon dioxide; a second flow path through which a

5 outlet of the cathode chamber, and the third fluid being discharged from the cathode

chamber and containing the carbon compound; a fourth flow path through which a fourth 2024201352

10 controller, a second flow rate controller, a first pressure controller, a second pressure

configured to control a flow rate of the first fluid flowing through the first flow path, the

second flow rate controller being configured to control a flow rate of the second fluid

flowing through the second flow path, the first pressure controller being configured to

15 control a pressure of the third flow path, the second pressure controller being configured to

control a pressure of the fourth flow path, the temperature controller being configured to

control a temperature of the electrochemical reaction structure, the power supply being

configured to control a current or a voltage to be supplied to the electrochemical reaction

structure, and the at least one controller including the first flow rate controller; a gas/liquid

20 separator provided in the middle of the fourth flow path and configured to process the

fourth fluid to separate a liquid containing the water from the fourth fluid; a first flowmeter

configured to measure a flow rate of the third fluid flowing through the third flow path; a

second flowmeter configured to measure a flow rate of the processed fourth fluid flowing

through the fourth flow path; and a control device connected to the at least one controller,

25 the first flowmeter and the second flowmeter, the control device being configured to

measure a sum of the flow rate of the first fluid flowing through the first flow path, the

flow rate of the third fluid flowing through the third flow path, and the flow rate of the

processed fourth fluid flowing through the fourth flow path, and being configured to

control the at least one controller according to the sum to control a pressure difference

between the cathode chamber and the anode chamber, wherein the at least one controller

includes: the first pressure controller; and the second pressure controller, and the control

device is configured to control the first pressure controller according to the sum to control

5 the pressure of the third flow path, and to control the second pressure controller according

to the sum to control the pressure of the fourth flow path, and thus control the pressure 2024201352

difference.

[0006b] Further embodiments of the present invention comprise an electrochemical

10 having a reduction catalyst that promotes a reduction reaction of reducing carbon dioxide

15 connected to an inlet of the cathode chamber, and the first fluid being supplied to the

20 outlet of the cathode chamber, and the third fluid being discharged from the cathode

chamber and containing the carbon compound; a fourth flow path through which a fourth

25 controller, a second flow rate controller, a first pressure controller, a second pressure

control a pressure of the third flow path, the second pressure controller being configured to

5 configured to control a current or a voltage to be supplied to the electrochemical reaction

structure, and the at least one controller including the first flow rate controller; a gas/liquid 2024201352

separator provided in the middle of the fourth flow path and configured to process the

10 second flowmeter configured to measure a flow rate of the processed fourth fluid flowing

the first flowmeter and the second flowmeter, the control device being configured to

15 processed fourth fluid flowing through the fourth flow path, and being configured to

between the cathode chamber and the anode chamber, wherein the control device is

configured to compare a first data indicating the sum with a second data to be stored in the

control device, and is configured to control the at least one controller according to a

20 comparison result to control the pressure difference.

[0006c] Further embodiments of the present invention comprise an electrochemical

configured to analyze variations in the sum over time, and is configured to control the at

least one controller according to a result of the analyzation to control the pressure

5 difference.

[0006c] Further embodiments of the present invention comprise a method of operating an 2024201352

electrochemical reaction device, the electrochemical reaction device comprising an

electrochemical reaction structure, the electrochemical reaction structure comprising: a

cathode having a reduction catalyst that promotes a reduction reaction of reducing carbon

10 dioxide to produce a carbon compound; an anode having an oxidation catalyst that

promotes an oxidation reaction of oxidizing water to produce oxygen; a diaphragm

between the cathode and the anode, a cathode chamber facing on the cathode; and an anode

chamber facing on the anode; a first flow path through which a first fluid flows, the first

flow path being connected to an inlet of the cathode chamber, and the first fluid being

15 supplied to the cathode chamber and containing the carbon dioxide; a second flow path

through which a second fluid flows, the second flow path being connected to an inlet of the

anode chamber, and the second fluid being supplied to the anode chamber and containing

the water; a third flow path through which a third fluid flows, the third flow path being

connected to an outlet of the cathode chamber, and the third fluid being discharged from

20 the cathode chamber and containing the produced carbon compound; a fourth flow path

through which a fourth fluid flows, the fourth flow path being connected to an outlet of the

anode chamber, and the fourth fluid being discharged from the anode chamber and

containing the water and the produced oxygen; at least one controller selected from the

group consisting of a first flow rate controller, a second flow rate controller, a first pressure

25 controller, a second pressure controller, a temperature controller and a power supply, the

first flow rate controller being configured to measure and control a flow rate of the first

fluid flowing through the first flow path, the second flow rate controller being configured

to measure and control a flow rate of the second fluid flowing through the second flow

path, the first pressure controller being configured to control a pressure of the third flow

path, the second pressure controller being configured to control a pressure of the fourth

flow path, the temperature controller being configured to control a temperature of the

electrochemical reaction structure, the power supply being configured to control a current

5 or a voltage to be supplied to the electrochemical reaction structure, and the at least one

controller including the first flow rate controller; a gas/liquid separator provided in the 2024201352

middle of the fourth flow path and configured to process the fourth fluid to separate a

liquid containing the water from the fourth fluid; a first flowmeter configured to measure a

flow rate of the third fluid flowing through the third flow path; and a second flowmeter

10 configured to measure a flow rate of the processed fourth fluid flowing through the fourth

flow path, the method comprising: supplying the first fluid to the cathode chamber,

supplying the second fluid to the anode chamber, and supplying a current or a voltage to

the electrochemical reaction structure, to reduce the carbon dioxide by the cathode to

produce the carbon compound and to oxidize the water by the anode to produce the

15 oxygen; and measuring the sum of the flow rate of the first fluid flowing through the first

flow path, the flow rate of the third fluid flowing through the third flow path, and the flow

rate of the processed fourth fluid flowing through the fourth flow path and controlling the

at least one controller according to the sum to control a pressure difference between the

cathode chamber and the anode chamber.

20

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] One or more embodiments of the present invention are hereinafter described, by

way of example only, with reference to the accompanying drawings in which:

FIG. 1 is a schematic view illustrating an example configuration of an

25 electrochemical reaction device in an embodiment;

FIG. 2 is a schematic view illustrating another example configuration of the

electrochemical reaction device in the embodiment;

FIG. 3 is a schematic view illustrating another example configuration of the

electrochemical reaction device in the embodiment;

FIG. 4 is a schematic view illustrating another example configuration of the

electrochemical reaction device in the embodiment;

FIG. 5 is a schematic view illustrating another example configuration of the

5 electrochemical reaction device in the embodiment; and

FIG. 6 is a schematic view illustrating another example configuration of the 2024201352

electrochemical reaction device in the embodiment.

DETAILED DESCRIPTION

10 [0008] There will be explained embodiments with reference to the drawings below. In

each of the following embodiments, substantially the same components are denoted by the

same reference numerals and symbols, and explanations thereof may be partly omitted.

The drawings are schematic, and a relation between thickness and planar dimension, a

thickness ratio among parts, and so on may be different from actual ones.

15 [0009] In this specification, "connecting" includes not only directly connecting but also

indirectly connecting in some cases, unless otherwise specified.

[0010] FIG. 1 is a schematic view illustrating an example configuration of an

electrochemical reaction device. FIG. 1 illustrates an example configuration of an

electrochemical reaction device 1. The electrochemical reaction device 1 includes an

20 electrochemical reaction structure 10, a flow path P1, a flow path P2, a flow path P3, a

flow path P4, a flow rate controller 21, a flow rate controller 22, a humidifier 30, a

pressure controller 41, a pressure controller 42, a dehydrator 51, a gas/liquid separator 52,

a flowmeter 61, a flowmeter 62, a power supply 70, and a control device 80.

[0011] The electrochemical reaction structure 10 includes a cathode 11, an anode 12, a

25 diaphragm 13, a flow path plate 14, a flow path plate 15, a current collector 16, and a

current collector 17.

[0012] The cathode 11 is, for example, a reduction electrode for performing a reduction

reaction of at least one reducible material (substance to be reduced). Examples of the at

least one reducible material include carbon dioxide. The cathode 11 can reduce, for

example, carbon dioxide supplied as a gas or carbon dioxide contained in a first

electrolytic solution (cathode solution) to produce a carbon compound. Examples of the

carbon compound include carbon monoxide, formic acid, methanol, methane, ethanol,

5 ethane, ethylene, formaldehyde, ethylene glycol, acetic acid, and propanol. The cathode 11

may perform a side reaction of generating hydrogen through a reduction reaction of water 2024201352

as well as a reduction reaction of carbon dioxide.

[0013] The cathode 11 has a reduction catalyst that promotes a reduction reaction that

reduces carbon dioxide to produce a carbon compound, for example. The reduction

10 catalyst can be formed using a material that reduces the activation energy for reducing

carbon dioxide, for example. In other words, the reduction catalyst can be formed using a

material that lowers the overvoltage when producing a carbon compound by the reduction

reaction of carbon dioxide, for example.

[0014] The cathode 11 can be formed using a metal material or a carbon material, for

15 example. Examples of the metal material include metals such as gold, aluminum, copper,

silver, platinum, palladium, zinc, mercury, indium, nickel, and titanium, alloys containing

these metals, and so on. Examples of the carbon material include graphene, carbon

nanotube (CNT), fullerene, ketjen black, and so on. The cathode 11 is not limited to these

materials, and may be formed using a metal complex such as a Ru complex or a Re

20 complex, or an organic molecule having an imidazole skeleton or a pyridine skeleton, for

example. The cathode 11 may be formed using a mixture of a plurality of materials. The

cathode 11 may have a structure having the reduction catalyst in a thin film shape, a mesh

shape, a particle shape, a wire shape, or the like provided on a conductive substrate, for

example. The type of the carbon compound produced by the reduction reaction also differs

25 depending on the type of reduction catalyst.

[0015] The anode 12 is an oxidation electrode for performing an oxidation reaction of at

least one oxidizable material (substance to be oxidized), for example. Examples of at least

one oxidizable material include water. The anode 12 oxidizes an oxidizable material such

as a substance or ion in a second electrolytic solution (anode solution) to produce oxygen,

for example.

[0016] The anode 12 has an oxidation catalyst that promotes an oxidation reaction that

oxidizes water to produce oxygen, for example. The oxidation catalyst can be formed

5 using a material that reduces the activation energy when oxidizing an oxidizable material,

in other words, a material that lowers the reaction overpotential, for example. Examples of 2024201352

the oxidation reaction at the anode 12 include reactions of oxidizing water to produce

oxygen or hydrogen peroxide water, oxidizing chloride ions (Cl -) to produce chlorine,

oxidizing carbonate ions or hydrogen carbonate ions to produce carbon dioxide, and so on.

10 [0017] Examples of the oxidation catalyst include metal materials. Examples of the

metal material include ruthenium, iridium, platinum, cobalt, nickel, iron, manganese,

tantalum, zirconium, and so on. Further, examples of the metal material include a binary

metal oxide, a ternary metal oxide, a quaternary metal oxide, and so on. Examples of the

binary metal oxide include manganese oxide (Mn-O), iridium oxide (Ir-O), nickel oxide

15 (Ni-O), cobalt oxide (Co-O), iron oxide (Fe-O), tin oxide (Sn-O), indium oxide (In-O),

ruthenium oxide (Ru-O), and so on. Examples of the ternary metal oxide include nickel-

iron oxide (Ni-Fe-O), nickel-cobalt oxide (Ni-Co-O), lanthanum-cobalt oxide (La-Co-O),

nickel-lanthanum oxide (Ni-La-O), strontium-iron oxide (Sr-Fe-O), and so on. Examples

of the quaternary metal oxide include lead-ruthenium-iridium oxide (Pb-Ru-Ir-O),

20 lanthanum-strontium-cobalt oxide (La-Sr-Co-O), and so on. The oxidation catalyst is not

limited to these materials, and may be formed using a metal hydroxide containing a metal

such as cobalt, nickel, iron, or manganese, or a metal complex such as a ruthenium

complex or an iron complex. Further, the oxidation catalyst may be formed by mixing a

plurality of materials.

25 [0018] The anode 12 may be formed using a composite material containing both an

oxidation catalyst and a conductive material. Examples of the conductive material include

carbon materials such as carbon black, activated carbon, fullerene, carbon nanotube,

graphene, ketjen black, and diamond, transparent conductive oxides such as indium tin

oxide (ITO), zinc oxide (ZnO), fluorine-doped tin oxide (FTO), aluminum-doped zinc

oxide (AZO), and antimony-doped tin oxide (ATO), metals such as copper, aluminum,

titanium, nickel, silver, tungsten, cobalt, and gold, alloys each containing at least one of the

metals, and so on. The anode 12 may have a structure having the oxidation catalyst in a

5 thin film shape, a mesh shape, a particle shape, a wire shape, or the like provided on a

conductive substrate, for example. The conductive substrate can be formed using a metal 2024201352

material containing titanium, titanium alloy, or stainless steel, for example.

[0019] The diaphragm 13 is provided between the cathode 11 and the anode 12. The

diaphragm 13 can separate a cathode chamber 140 and an anode chamber 150. The

10 diaphragm 13 can move ions such as hydrogen ions (H+), hydroxide ions (OH-), hydrogen

carbonate ions (HCO3-), and carbonate ions (CO32-). By the diaphragm 13, an

electrochemical reaction cell having a two-chamber structure can be formed. The

diaphragm 13 may be provided in contact with the cathode 11 and the anode 12.

[0020] The diaphragm 13 can be formed using a membrane capable of selectively

15 allowing anions or cations to pass therethrough, for example. This allows the composition

of the second electrolytic solution in contact with the anode 12 to be different from that of

the first electrolytic solution in contact with the cathode 11, and furthermore, differences in

ionic strength, pH, and so on can promote the reduction reaction or the oxidation reaction.

The diaphragm 13 may have a function of permeating part of ions contained in the

20 electrolytic solutions in which the cathode 11 and the anode 12 are immersed therethrough,

namely, a function of blocking one or more kinds of ions contained in the electrolytic

solutions. This can differ the pH or the like between the two electrolytic solutions, for

example. Further, in terms of the blocking of ions, a diaphragm that does not completely

block part of ions but is effective enough to limit the amount of movement by ion species

25 may be used.

[0021] The diaphragm 13 can be formed using an ion exchange membrane such as, for

example, NEOSEPTA (registered trademark) of ASTOM Corporation, Selemion

(registered trademark), Aciplex (registered trademark) of ASAHI GLASS CO., LTD.,

Fumasep (registered trademark), fumapem (registered trademark) of Fumatech GmbH,

Nafion (registered trademark) being fluorocarbon resin made by sulfonating and

polymerizing tetrafluoroethylene of E.I. du Pont de Nemours and Company, lewabrane

(registered trademark) of LANXESS AG, IONSEP (registered trademark) of IONTECH

5 Inc., Mustang (registered trademark) of PALL Corporation, ralex (registered trademark) of

mega Corporation, Gore-Tex (registered trademark) of Gore-Tex Co., Ltd. Sustainion 2024201352

(registered trademark) of DIOXIDE MATERIALS, or PiperION (registered trademark) of

Versogen, Inc. The ion exchange membrane may be formed using a membrane having

hydrocarbon as a basic skeleton, for example. An anion exchange membrane may be

10 formed using a membrane having an amine group, for example. In the case where there is

a pH difference between the first electrolytic solution and the second electrolytic solution,

by forming the diaphragm 13 using a bipolar membrane made by stacking a cation

exchange membrane and an anion exchange membrane, the electrolytic solutions can be

used while stably keeping the pHs thereof.

15 [0022] The diaphragm 13 may be formed using materials such as porous membranes of a

silicone resin, fluorine-based resins such as perfluoroalkoxyalkane (PFA),

perfluoroethylene propene copolymer (FEP), polytetrafluoroethylene (PTFE),

ethylene∙tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF),

polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer

20 (ECTFE), and polyethersulfone (PES), and ceramics, packing filled with glass filter, agar,

and so on, insulating porous bodies of zeolite, oxide, and so on, for example. In particular,

a hydrophilic porous membrane is preferable as the material for the diaphragm 13 because

it can inhibit clogging due to air bubbles.

[0023] The cathode 11, the anode 12, and the diaphragm 13 are stacked to form an

25 electrochemical reaction cell. The electrochemical reaction structure 10 may include a cell

stack formed by stacking a plurality of electrochemical reaction cells. The presence of the

cell stack increases the amount of carbon dioxide reacted per unit area to increase the

production amount of carbon compounds. The number of stacked electrochemical reaction

cells is preferably 10 or more and 150 or less, for example.

[0024] The flow path plate 14 defines the cathode chamber 140. The cathode chamber

140 is provided on the surface of the flow path plate 14 to face on the cathode 11 and can

define a cathode flow path. The cathode chamber 140 has an inlet for supplying fluid to

5 the cathode chamber 140 and an outlet for discharging the fluid from the cathode chamber

140. The surface shape of the cathode flow path is not limited in particular, but is 2024201352

serpentine, for example.

[0025] The flow path plate 15 defines the anode chamber 150. The anode chamber 150

is provided on the surface of the flow path plate 15 to face on the anode 12, and can define

10 an anode flow path. The anode chamber 150 has an inlet for supplying fluid to the anode

chamber 150 and an outlet for discharging the fluid from the anode chamber 150. The

surface shape of the anode flow path is not limited in particular, but is serpentine, for

example.

[0026] Electrolytic reactions such as an oxidation reaction and a reduction reaction by

15 the electrochemical reaction structure 10 are preferably performed at a temperature of

room temperature (for example, 25°C) or more and 100°C or less, at which the electrolytic

solution does not vaporize. The temperature is preferably 60°C or more and 95°C or less,

and more preferably 60°C or more and 80°C or less. In order to set the temperature to less

than room temperature, a cooling device such as a chiller is required, which may reduce

20 the energy efficiency of an overall system. When the temperature exceeds 100°C, the

water in the electrolytic solution turns into vapor and resistance increases, which may

reduce the electrolysis efficiency.

[0027] The current density of the cathode 11 is not limited in particular, but a higher

current density is preferred in order to increase the amount of reduction products produced

25 per unit area. The current density is preferably 100 mA/cm 2 or more and 1.5 A/cm2 or less,

and further preferably 300 mA/cm2 or more 700 mA/cm2 or less. When the current density

is less than 100 mA/cm2, the amount of reduction products produced per unit area is small,

which requires a large area. When the current density exceeds 1.5 A/cm2, a side reaction of

hydrogen generation increases, leading to a decrease in the concentration of reduction

products.

[0028] In the case where Joule heat also increases by increasing the current density, the

temperature increases above an appropriate temperature, so that a cooling mechanism may

5 be provided in or near the electrochemical reaction structure 10. The cooling mechanism

may be water cooling or air cooling. Even when the temperature of the electrochemical 2024201352

reaction structure 10 is higher than room temperature, the temperature may remain

unchanged as long as it is equal to or less than 100°C.

[0029] The flow path P1 is connected to the inlet of the cathode chamber 140. A cathode

10 supply fluid to be supplied to the cathode chamber 140 can flow through the flow path P1.

The cathode supply fluid contains carbon dioxide. The cathode supply fluid may be a gas

containing gaseous carbon dioxide or the first electrolytic solution containing carbon

dioxide.

[0030] The flow path P1 may be connected to a carbon dioxide supply source. The

15 carbon dioxide supply source may include a carbon dioxide separation and capture device,

and may be connected to the carbon dioxide separation and capture device. A carbon

dioxide gas from the carbon dioxide separation and capture device can be supplied to the

flow path P1, for example, directly or after being stored once. Examples of the carbon

dioxide supply source include facilities having various incinerators or combustion furnaces

20 such as a thermal power plant and a garbage incinerator, facilities having a steel plant and a

blast furnace, and so on. The carbon dioxide supply source is not limited to these facilities,

but may be other factories that generate carbon dioxide.

[0031] The flow path P2 is connected to the inlet of the anode chamber 150. An anode

supply fluid to be supplied to the anode chamber 150 can flow through the flow path P2.

25 The anode supply fluid contains water or the second electrolytic solution. The flow path

P2 may be connected to an anode solution supply source. The anode solution supply

source can supply the second electrolytic solution, which is used for the anode supply

fluid, for example.

[0032] The flow path P3 is connected to the outlet of the cathode chamber 140. A

cathode exhaust fluid to be discharged from the cathode chamber 140 can flow through the

flow path P3. The cathode exhaust fluid contains a carbon compound and hydrogen

produced by the reduction reaction at the cathode 11 and a part of the carbon dioxide gas or

5 a part of the first electrolytic solution contained in the cathode supply fluid.

[0033] The flow path P4 is connected to the outlet of the anode chamber 150. An anode 2024201352

exhaust fluid to be discharged from the anode chamber 150 can flow through the flow path

P4. The anode exhaust fluid contains, for example, gaseous oxygen produced by the

oxidation reaction at the anode 12, carbon dioxide moving from the cathode chamber 140

10 or the electrolytic solution, and water or a part of the second electrolytic solution contained

in the anode supply fluid.

[0034] When a gas containing a reducible material such as carbon dioxide (cathode gas)

is supplied to the cathode chamber 140, the electrochemical reaction structure 10 may

include a second cathode chamber between the cathode 11 and the diaphragm 13 and

15 supply the first electrolytic solution to the second cathode chamber. FIG. 2 is a schematic

view illustrating another example configuration of the electrochemical reaction device in

the embodiment. As illustrated in FIG. 2, the electrochemical reaction device 1 may

further include a flow path plate 18, a cathode chamber 180, a flow path P5, and a flow

path P6.

20 [0035] The flow path plate 18 defines the cathode chamber 180. The cathode chamber

180 is provided on the surface of the flow path plate 18 to face on the cathode 11, and can

define a second cathode flow path. The cathode chamber 180 is arranged across the

cathode 11 from the cathode chamber 140. The cathode chamber 180 has an inlet for

supplying fluid to the cathode chamber 180 and an outlet for discharging the fluid from the

25 cathode chamber 180.

[0036] The flow path P5 is connected to the inlet of the cathode chamber 180. A second

cathode supply fluid to be supplied to the cathode chamber 180 can flow through the flow

path P5. The second cathode supply fluid contains the first electrolytic solution. The first

electrolytic solution may contain carbon dioxide, or does not need to contain carbon

dioxide. The flow path P5 may be connected to a cathode solution supply source. The

cathode solution supply source can supply the first electrolytic solution, which is used for

the second cathode supply fluid, for example. When the first electrolytic solution is the

5 same as the second electrolytic solution, the flow path P5 may be connected to the anode

solution supply source. 2024201352

[0037] The flow path P6 is connected to the outlet of the cathode chamber 180. A second

cathode exhaust fluid to be discharged from the cathode chamber 180 can flow through the

flow path P6. The second cathode exhaust fluid contains a carbon compound and

10 hydrogen produced by the reduction reaction at the cathode 11 and the first electrolytic

solution. The second cathode exhaust fluid may be reused by the gas/liquid separator

separating the second cathode exhaust fluid into a gas component and a liquid component

and then supplying the separated liquid component to the flow path P5 as the first

electrolytic solution. In this case, the electrochemical reaction device 1 may include a flow

15 path and a pump to return the separated liquid component to the flow path P5, the flow

path connecting the flow path P5 and the flow path P6, the pump being provided in the

middle of the flow path.

[0038] The first electrolytic solution preferably has a high absorptance of carbon dioxide.

The carbon dioxide in the first electrolytic solution is not always limited to be dissolved

20 therein, but be in an air bubble state to be mixed in the first electrolytic solution. Examples

of the electrolytic solution containing carbon dioxide include aqueous solutions containing

hydrogencarbonates and carbonates such as lithium hydrogen carbonate (LiHCO 3), sodium

hydrogen carbonate (NaHCO3), potassium hydrogen carbonate (KHCO3), cesium hydrogen

carbonate (CsHCO3), sodium carbonate (Na2CO3), and potassium carbonate (K2CO3),

25 phosphoric acid, boric acid, and so on. The electrolytic solution containing carbon dioxide

may contain alcohols such as methanol or ethanol, or ketones such as acetone, or may be

an alcohol solution or ketone solution. The first electrolytic solution may be an electrolytic

solution containing a carbon dioxide absorbent that lowers the reduction potential for

carbon dioxide, has a high ion conductivity, and absorbs carbon dioxide.

[0039] Examples of the electrolytic solutions such as the first electrolytic solution and

the second electrolytic solution, include a solution containing water, which is, for example,

an aqueous solution containing any electrolyte. The solution is preferred to be an aqueous

5 solution that promotes the oxidation reaction of water. Examples of the aqueous solution

containing the electrolyte include aqueous solutions containing phosphate ion (PO 42‒), 2024201352

borate ion (BO33‒), sodium ion (Na+), potassium ion (K+), calcium ion (Ca2+), lithium ion

(Li+), cesium ion (Cs+), magnesium ion (Mg2+), chloride ion (Cl‒), hydrogen carbonate ion

(HCO3‒), carbonate ion (CO3‒), hydroxide ion (OH‒), and so on.

10 [0040] Examples of the electrolytic solutions include an ionic liquid that is made of salts

of cations such as imidazolium ions or pyridinium ions and anions such as BF 4‒ or PF6‒

and is in a liquid state in a wide temperature range, or an aqueous solution thereof.

Further, examples of other electrolytic solutions include amine solutions such as

ethanolamine, imidazole, and pyridine, and aqueous solutions thereof. Examples of amine

15 include primary amine, secondary amine, tertiary amine, and so on. The electrolytic

solutions may be high in ion conductivity and have properties of absorbing carbon dioxide

and characteristics of reducing the reduction energy.

[0041] Examples of the primary amine include methylamine, ethylamine, propylamine,

butylamine, pentylamine, hexylamine, and so on. Hydrocarbons of the amine may be

20 substituted by alcohol, halogen, and the like. Examples of amine whose hydrocarbons are

substituted include methanolamine, ethanolamine, chloromethylamine, and so on. Further,

an unsaturated bond may exist. These hydrocarbons are also the same in the secondary

amine and the tertiary amine.

[0042] Examples of the secondary amine include dimethylamine, diethylamine,

25 dipropylamine, dibutylamine, dipentylamine, dihexylamine, dimethanolamine,

diethanolamine, dipropanolamine, and so on. The substituted hydrocarbons may be

different. This also applies to the tertiary amine. Examples with different hydrocarbons

include methylethylamine, methylpropylamine, and so on.

[0043] Examples of the tertiary amine include trimethylamine, triethylamine,

tripropylamine, tributylamine, trihexylamine, trimethanolamine, triethanolamine,

tripropanolamine, tributanolamine, trihexanolamine, methyldiethylamine,

methyldipropylamine, and so on.

5 [0044] Examples of the cation of the ionic liquid include 1-ethyl-3-methylimidazolium

ion, 1-methyl-3-propylimidazolium ion, 1-butyl-3-methylimidazole ion, 1-methyl-3- 2024201352

pentylimidazolium ion, 1-hexyl-3-methylimidazolium ion, and so on.

[0045] A second place of the imidazolium ion may be substituted. Examples of the

cation of the imidazolium ion whose second place is substituted include 1-ethyl-2,3-

10 dimethylimidazolium ion, 1,2-dimethyl-3-propylimidazolium ion, 1-butyl-2,3-

dimethylimidazolium ion, 1,2-dimethyl-3-pentylimidazolium ion, 1-hexyl-2,3-

dimethylimidazolium ion, and so on.

[0046] Examples of the pyridinium ion include methylpyridinium, ethylpyridinium,

propylpyridinium, butylpyridinium, pentylpyridinium, hexylpyridinium, and so on. In both

15 of the imidazolium ion and the pyridinium ion, an alkyl group may be substituted, or an

unsaturated bond may exist.

[0047] Examples of the anion include fluoride ion (F‒), chloride ion (Cl‒), bromide ion

(Br‒), iodide ion (I‒), BF4‒, PF6‒, CF3COO‒, CF3SO3‒, NO3‒, SCN‒, (CF3SO2)3C‒,

bis(trifluoromethoxysulfonyl)imide, bis(perfluoroethylsulfonyl)imide, and so on. Dipolar

20 ions in which the cations and the anions of the ionic liquid are coupled by hydrocarbons

may be used. A buffer solution such as a potassium phosphate solution may be supplied to

the anode chamber 150 and the cathode chamber 180.

[0048] The second electrolytic solution contains water as the oxidizable material. It is

possible to change the amount of water or the electrolytic solution components contained

25 in the first and second electrolytic solutions to change the reactivity and then change the

selectivity of a reduced substance or the ratio of produced substances. The first and second

electrolytic solutions may contain redox couples as needed. Examples of the redox couple

include Fe3+/Fe2+, IO3‒/I‒, and so on.

[0049] The flow rate controller 21 is provided in the middle of the flow path P1. The

flow rate controller 21 can control the flow rate of the cathode supply fluid flowing

through the flow path P1, for example. The flow rate controller 21 may include a mass

flow controller, for example. The flow rate controller 21 can control the flow rate of

5 carbon dioxide to be introduced into the cathode chamber 140. The flow rate controller 21

may have a function of controlling the flow rate of the cathode supply fluid based on a 2024201352

control signal from the control device 80. The flow rate controller 21 may, for example,

measure the flow rate of the cathode supply fluid flowing through the flow path P1 and

supply a data signal including data indicating the measured flow rate to the control device

10 80.

[0050] The flow rate controller 22 is provided in the middle of the flow path P2. The

flow rate controller 22 can control the flow rate of the anode supply fluid flowing through

the flow path P2, for example. The flow rate controller 22 may include a mass flow

controller, for example. The flow rate controller 22 can also control the temperature of the

15 electrochemical reaction structure 10 or move the gas generated in the anode chamber 150

to the flow path P4. The flow rate controller 22 may, for example, measure the flow rate of

the anode supply fluid flowing through flow path P2 and supply a data signal including

data indicating the measured flow rate to the control device 80.

[0051] The humidifier 30 is provided so as to precede or follow the flow rate controller

20 21 in the middle of the flow path P1. The humidifier 30 can humidify the carbon dioxide

gas in the cathode supply fluid. Examples of the humidifier 30 include humidifiers such as

a bubbling type humidifier and a hollow fiber membrane type humidifier. As illustrated in

FIG. 1, arranging the humidifier 30 between the flow rate controller 21 and the cathode

chamber 140 makes it possible to supply the cathode supply fluid containing a carbon

25 dioxide gas to the cathode chamber 140 with an accurate supply amount even after

humidification. The electrochemical reaction device in the embodiment does not need to

include the humidifier 30.

[0052] The cathode supply fluid containing the humidified carbon dioxide gas may

contain liquid in the form of mist or fumes. A part of the cathode supply fluid containing

the humidified carbon dioxide gas may consist of liquid water. Further, the water may

contain something that functions as a cathode solution, or may contain carbon dioxide as

the reducible substance.

5 [0053] The pressure controller 41 is provided in the middle of the flow path P3. The

pressure controller 41 can control the pressure in the cathode chamber 140 by controlling 2024201352

the pressure of the flow path P3. The pressure controller 41 may have a function of

controlling the pressure in the cathode chamber 140 based on a control signal from the

control device 80. The pressure controller 41 may have a function of indirectly measuring

10 the pressure in the cathode chamber 140 by measuring the pressure of the flow path P3.

[0054] The pressure controller 42 is provided in the middle of the flow path P4. The

pressure controller 42 can control the pressure in the anode chamber 150 by controlling the

pressure of the flow path P4, for example. The pressure controller 42 may have a function

of controlling the pressure in the anode chamber 150 based on a control signal from the

15 control device 80. The pressure controller 42 may have a function of indirectly measuring

the pressure in the anode chamber 150 by measuring the pressure of the flow path P4.

[0055] The dehydrator 51 is provided so as to follow the pressure controller 41, for

example, in the middle of the flow path P3. The dehydrator 51 can, for example, process

the cathode exhaust fluid to separate water and the first electrolytic solution from the

20 cathode exhaust fluid. The dehydrator 51 may have a function of removing water from

exhaust gas by cooling or the like. The arrangement of the dehydrator 51 preceding the

flowmeter 61 makes it possible to more accurately measure the flow rate of gas containing

carbon compounds in the cathode exhaust fluid discharged from the cathode chamber 140.

[0056] The gas/liquid separator 52 is provided so as to follow the pressure controller 42,

25 for example, in the middle of the flow path P4. The gas/liquid separator 52 can, for

example, process the anode exhaust fluid to separate liquid such as water and the

electrolytic solution from the anode exhaust fluid. The processed anode exhaust fluid

contains, for example, oxygen produced by the oxidation reaction at the anode 12 and

carbon dioxide that has moved from the cathode chamber 140. The arrangement of the

gas/liquid separator 52 preceding the flowmeter 62 makes it possible to more accurately

measure the flow rate of gas such as oxygen or carbon dioxide in the anode exhaust fluid

discharged from the anode chamber 150.

5 [0057] The flowmeter 61 is provided so as to follow the dehydrator 51, for example, in

the middle of the flow path P3. The flowmeter 61 can measure the flow rate of the 2024201352

processed cathode exhaust fluid flowing through the flow path P3, for example. The

flowmeter 61 can measure the total flow rate of gases such as carbon compounds,

hydrogen, and unreacted carbon dioxide in the cathode exhaust fluid.

10 [0058] The flowmeter 62 is provided so as to follow the gas/liquid separator 52, for

example, in the middle of the flow path P4. The flowmeter 62 can measure the flow rate of

the processed anode exhaust fluid flowing through the flow path P4, for example. The

flowmeter 62 can measure the total flow rate of gases such as oxygen and carbon dioxide

in the anode exhaust fluid.

15 [0059] The power supply 70 can supply power to the electrochemical reaction structure

10, for example. The power supply 70 is connected to the current collector 16 and the

current collector 17, for example. The power supply 70 can apply power to the

electrochemical reaction structure 10 to cause an electrolytic reaction such as an oxidation

reaction or a reduction reaction, and is electrically connected to the cathode 11 and the

20 anode 12. The electric energy supplied by the power supply 70 is used to cause a reduction

reaction at the cathode 11 and an oxidation reaction at the anode 12. The power supply 70

and the current collector 16 are connected by wiring and the power supply 70 and the

current collector 17 are connected by wiring, for example. Between the electrochemical

reaction structure 10 and the power supply 70, electric devices such as inverters,

25 converters, and batteries may be installed as needed. The electrochemical reaction

structure 10 may be driven by a constant-voltage system or a constant-current system.

[0060] The power supply 70 may be an ordinary commercial power supply, a battery, or

the like, or may be a power supply that converts renewable energy to electric energy and

supplies it. Examples of such a power supply include a power supply that converts kinetic

energy or potential energy such as wind power, water power, geothermal power, or tidal

power to electric energy, a power supply such as a solar cell including a photoelectric

conversion element that converts light energy to electric energy, a power supply such as a

5 fuel cell or a storage battery that converts chemical energy to electric energy, and a power

supply such as an apparatus that converts vibrational energy such as sound to electric 2024201352

energy. The photoelectric conversion element has a function of performing charge

separation by emitted light energy of sunlight or the like. Examples of the photoelectric

conversion element include a pin-junction solar cell, a pn-junction solar cell, an amorphous

10 silicon solar cell, a multijunction solar cell, a single crystal silicon solar cell, a

polycrystalline silicon solar cell, a dye-sensitized solar cell, an organic thin-film solar cell,

and so on. Further, the photoelectric conversion element may be stacked on at least one of

the cathode 11 and the anode 12 inside the electrochemical reaction structure 10.

[0061] The power supply 70 can control the current or voltage to be supplied to the

15 electrochemical reaction structure 10, for example. The power supply 70 may include a

power controller that controls the current or voltage to be supplied to the electrochemical

reaction structure 10, for example. The power supply 70 may have a function of

controlling the pressure in the cathode chamber 140 or the pressure in the anode chamber

150 by controlling the current or voltage to be supplied to the electrochemical reaction

20 structure 10 based on a control signal from the control device 80.

[0062] FIG. 3 is a schematic view illustrating another example configuration of the

electrochemical reaction device in the embodiment. As illustrated in FIG. 3, the

electrochemical reaction device 1 may further include a flow path P7 and a pump 90. The

flow path P7 connects the gas/liquid separator 52 and the flow path P2 or the anode

25 solution supply source, for example. The pump 90 is provided in the middle of the flow

path P7. The gas/liquid separator 52 separates the anode exhaust fluid into a liquid

component such as the second electrolytic solution and a gas component such as oxygen,

hydrogen, and carbon dioxide and the pump 90 returns the liquid component to the flow

path P2 through the flow path P7, thereby enabling circulation of the anode solution. The

flow paths P1, P2, P3, P4, P5, P6, and P7 can be formed using pipes, for example.

[0063] FIG. 4 is a schematic view illustrating another example configuration of the

electrochemical reaction device in the embodiment. As illustrated in FIG. 4, the

5 electrochemical reaction device 1 may further include a temperature controller 71. The

temperature controller 71 is directly or indirectly connected to the electrochemical reaction 2024201352

structure 10. The temperature controller 71 can measure and control, for example, the

temperature (for example, external temperature) of the electrochemical reaction structure

10. The temperature controller 71 may include a heater capable of heating the

10 electrochemical reaction structure 10 or a cooler capable of cooling the electrochemical

reaction structure 10. The temperature controller 71 may measure at least one of the

temperatures of the cathode chamber 140 and the anode chamber 150 and control these

temperatures. The temperature controller 71 may have a function of controlling the

pressure in the cathode chamber 140 and the pressure in the anode chamber 150 by

15 controlling at least one of the temperature of the electrochemical reaction structure 10, the

temperature of the cathode chamber 140, and the temperature of the anode chamber 150

based on a control signal from the control device 80.

[0064] The control device 80 is connected to at least one of the controllers of the flow

rate controller 21, the flow rate controller 22, the pressure controller 41, the pressure

20 controller 42, the temperature controller 71, and the power supply 70, for example, by a

wired connection or a wireless connection. For example, as illustrated in FIG. 1, the

control device 80 is connected to each of the flow rate controller 21, the flowmeter 61, and

the flowmeter 62 by a wired connection or a wireless connection. The control device 80

can, for example, measure the sum of the flow rate of the cathode supply fluid flowing

25 through the flow path P1, the flow rate of the processed cathode exhaust fluid flowing

through the flow path P3, and the flow rate of the processed anode exhaust fluid flowing

through the flow path P4, and control the operating conditions of the electrochemical

reaction structure 10 according to the measured sum value. The control device 80 may

control a pressure difference (differential pressure) between the cathode chamber 140 and

the anode chamber 150, for example, by controlling at least one of the controllers of the

flow rate controller 21, the flow rate controller 22, the pressure controller 41, the pressure

controller 42, the temperature controller 71, and the power supply 70 according to the

5 measured sum value, for example.

[0065] The control device 80 includes hardware including an arithmetic device such as a 2024201352

processor, for example. Each operation may be stored as an operation program in a

computer-readable recording medium such as a memory, and each operation may be

executed by appropriately reading the operation program stored in the recording medium

10 by hardware.

[0066] FIG. 5 is a schematic view illustrating another example configuration of the

electrochemical reaction device in the embodiment. As illustrated in FIG. 5, the control

device 80 may be further connected to at least one of the pressure controller 41 and the

pressure controller 42 by a wired connection or a wireless connection. The control device

15 80 can, for example, measure the sum of the flow rate of the cathode supply fluid flowing

through the flow path P1, the flow rate of the processed cathode exhaust fluid flowing

through the flow path P4 and control at least one of the pressure controller 41 and the

pressure controller 42 according to the measured sum value to control the operating

20 conditions of the electrochemical reaction structure 10.

[0067] FIG. 6 is a schematic view illustrating another example configuration of the

electrochemical reaction device in the embodiment. As illustrated in FIG. 6, the control

device 80 may be connected to at least one of the pressure controller 41 and the pressure

controller 42 by a wired connection or a wireless connection, and does not need to be

25 connected to the flow rate controller 22. The control device 80 can, for example, measure

the sum of the flow rate of the cathode supply fluid flowing through the flow path P1, the

flow rate of the processed cathode exhaust fluid flowing through the flow path P3, and the

flow rate of the processed anode exhaust fluid flowing through the flow path P4 and

control at least one of the pressure controller 41 and the pressure controller 42 according to

the measured sum value to control the operating conditions of the electrochemical reaction

structure 10. The configurations illustrated in FIGs. 1, 2, 3, 4, 5, and 6 may be combined

as appropriate.

5 [0068] Next, there is explained an example method of operating the electrochemical

reaction device 1. Here, there is explained the case where carbon dioxide is reduced to 2024201352

produce carbon monoxide mainly and water is oxidized to produce oxygen. When the

cathode supply fluid containing carbon dioxide is supplied to the cathode chamber 140, the

anode supply fluid containing the second electrolytic solution is supplied to the anode

10 chamber 150, and a voltage that is equal to or more than the electrolysis voltage is applied

between the cathode 11 and the anode 12 by supplying power by the power supply 70, the

oxidation reaction of water occurs near the anode 12 in contact with the second electrolytic

solution. As expressed in the following expression (1), an oxidation reaction of water

contained in the second electrolytic solution occurs, electrons are lost, and oxygen and

15 hydrogen ions are produced. Some of the produced hydrogen ions move to the cathode

chamber 140 through the diaphragm 13.

2H2O → 4H+ + O2 + 4e‒ ...(1)

[0069] When the hydrogen ions (H+) produced on the anode 12 side reach the vicinity of

the cathode 11 and at the same time, electrons (e‒) are supplied to the cathode 11 from the

20 power supply 70, the reduction reaction of carbon dioxide occurs. As expressed in the

following expression (2), carbon dioxide is reduced by the hydrogen ions (H +) that have

moved to the vicinity of the cathode 11 and the electrons (e‒) supplied from the power

supply 70 to produce carbon monoxide.

2CO2 + 4H+ + 4e‒ → 2CO + 2H2O ...(2)

25 [0070] The gas component contained in the anode exhaust fluid from the anode chamber

150 is mainly an oxygen gas, as expressed in The expression (1). In the reactions at the

cathode 11 and the anode 12, most of the carbon dioxide contained in the cathode supply

fluid supplied to the cathode chamber 140 is reduced at the cathode 11, but some flows to

the anode 12 side as carbon dioxide or as ions such as carbonate ions (CO32‒) or hydrogen

carbonate ions (HCO3‒). The carbonate ions or the hydrogen carbonate ions that have

moved to the anode 12 side become present as carbon dioxide by a chemical equilibrium

reaction when the pH of the anode solution (second electrolytic solution) becomes, for

5 example, six or less, and some of the carbon dioxide is dissolved in the anode solution.

Such a carbon dioxide gas, which is not fully dissolved in the anode solution, is contained 2024201352

with the oxygen gas in the anode exhaust fluid discharged from the anode chamber 150.

Under general operating conditions of the electrochemical reaction structure 10, the

abundance ratio of the carbon dioxide gas to the oxygen gas in the anode exhaust fluid

10 increases up to, for example, 2: 1 in some cases.

[0071] The electrochemical reaction device in the embodiment can predict the state of

the electrochemical reaction of the electrochemical reaction structure 10 by understanding

the flow rate of the cathode supply fluid flowing through the flow path P1, the flow rate of

the cathode exhaust fluid flowing through the flow path P3 (cathode exhaust fluid

15 processed by the dehydrator 51), and the flow rate of the anode exhaust fluid flowing

through the flow path P4 (anode exhaust fluid processed by the gas/liquid separator 52).

Through the reaction represented by the expression (2), carbon dioxide is consumed at the

cathode 11, but an equal amount of carbon compound (carbon monoxide, here) is

produced. Furthermore, the same amount of carbon dioxide as the amount of carbon

20 compound produced moves toward the anode 12. When the flow rate of the carbon

dioxide gas in the cathode supply fluid flowing through the flow path P1 is assumed to 100

and the current having a theoretical amount necessary to reduce the carbon dioxide gas

whose flow rate is assumed to 50 is supplied from the power supply 70 to the

electrochemical reaction structure 10, the ratios of carbon dioxide, carbon monoxide, and

25 hydrogen in the case of the Faraday efficiency (FE) being 100%, 90%, 70%, and 50% are

as illustrated in Table 1, for example. Data indicating such a relationship are registered

(recorded) in the control device 80 in advance, and the difference between the registered

data and the actual measured data and changes in the operating situation over time are

checked, thereby making it possible to understand the operating status.

[0072] [Table 1]

FE 100% 90% 70% 50% CO2 0 10 30 50 Cathode CO 50 45 35 25 exhaust fluid H2 0 5 15 25 2024201352

Subtotal 50 60 80 100 Anode CO2 50 45 35 25 exhaust O2 25 25 25 25 fluid Subtotal 75 70 60 50 Total 125 130 140 150

[0073] When a hydrogen production reaction, which is a side reaction, proceeds due to

5 catalyst deterioration or a phenomenon such as flooding in which the cathode catalyst is

covered with water or an electrolytic solution, a change in the cathode exhaust fluid occurs

such that the Faraday efficiency illustrated in Table 1 decreases from 100% to 90% or 70%.

When carbon dioxide whose flow rate is assumed to 100 flows through the flow path P3

and the Faraday efficiency decreases, the sum of the flow rate of the processed cathode

10 exhaust fluid flowing through the flow path P3 and the flow rate of the processed anode

exhaust fluid flowing through the flow path P4 increases to 125 when the Faraday

efficiency is 100%, increases to 130 when the Faraday efficiency is 90%, and increases to

140 when the Faraday efficiency is 100%. Thus, for example, by measuring the sum of the

flow rate of the cathode supply fluid flowing through the flow path P1, the flow rate of the

15 processed cathode exhaust fluid flowing through the flow path P3, and the flow rate of the

processed anode exhaust fluid flowing through the flow path P4, the decrease in Faraday

efficiency can be checked. Further, by comparing the actual measured data of the sum

with the registered data in the control device 80, the deterioration over a long-term

operation can be understood.

20 [0074] The decrease in Faraday efficiency due to deterioration over a long-term

operation causes, for example, a failure mode called cross leak in which a gaseous

substance moves to one of the cathode 11 side and the anode 12 side, or to each other.

When a reduction product moves from the cathode 11 side to the anode 12 side, a carbon

compound or hydrogen produced at the cathode 11 is oxidized at the anode 12 and

converted into carbon dioxide or water. When hydrogen is produced, the sum of the flow

5 rate of the processed cathode exhaust fluid flowing through the flow path P3 and the flow

rate of the processed anode exhaust fluid flowing through the flow path P4 decreases 2024201352

because hydrogen molecules are small, the cross leak of hydrogen moving through the

diaphragm 13 increases, and the product is converted from gas into liquid due to

conversion of hydrogen into water at the anode 12. The respective variations in the flow

10 rates of the processed cathode exhaust fluid and the processed anode exhaust fluid when

hydrogen is converted into water are illustrated in Table 2. When the Faraday efficiency

decreases to 90% due to the cross leak, the sum of the flow rate of the processed cathode

exhaust fluid flowing through the flow path P3 and the flow rate of the processed anode

exhaust fluid flowing through the flow path P4 decreases from 130 to 125. This variation

15 can be used to detect the increase or decrease in cross leak during a long-term operation

and control operation.

[0075] [Table 2]

FE 90% 70% 50% CO2 10 30 50 Cathode CO 45 35 25 exhaust fluid H2 0 0 0 Subtotal 55 65 75 Anode CO2 45 35 25 exhaust O2 25 25 25 fluid Subtotal 70 60 50 Total 125 125 125

[0076] For example, when operation is performed with the Faraday efficiency being

20 90%, the flow rate of the processed cathode exhaust fluid flowing through the flow path P3

varies from 60 in Table 1 to 55 in Table 2 over a long-term operation, and when the flow

rate of the processed anode exhaust fluid flowing through the flow path P4 does not vary

from 70 in Table 1 and remains 70 in Table 2, such a variation in the cathode exhaust fluid

as illustrated in Table 2 caused by the occurrence of the cross leak can be detected and the

operating conditions of each component can be controlled based on a control signal from

5 the control device 80.

[0077] A known example of a conventional electrochemical reaction device, detects the 2024201352

total flow rate of fluid discharged from a cathode chamber or an anode chamber and to

control the flow rate of a carbon dioxide gas in fluid supplied to the cathode chamber for

controlling carbon dioxide contained in the fluid discharged from the cathode chamber

10 according to a detection result. However, in order to detect changes in electrolysis

performance such as a cross leak or deterioration caused by a long-term operation of the

electrochemical reaction device, it is necessary to detect variations in the sum of the flow

rate of the cathode supply fluid flowing through the flow path P1, the flow rate of the

processed cathode exhaust fluid flowing through the flow path P3, and the flow rate of the

15 processed anode exhaust fluid flowing through the flow path P4, as in the electrochemical

reaction device in the embodiment.

[0078] The cathode chamber 140 and the anode chamber 150 has an appropriate

balanced pressure therebetween, the appropriate balanced pressure can be set by

controlling the pressures of cathode chamber 140 and the anode chamber 150 using, for

20 example, the pressure controller 41 and the pressure controller 42. When the pressure in

the cathode chamber 140 is low, water or an electrolytic solution may flow into the cathode

11 from the flow path P2. When too much water or electrolytic solution flows into the

cathode 11, flooding occurs and the hydrogen production reaction, which is a side reaction,

proceeds. When the pressure in the cathode chamber 140 is high, water or an electrolytic

25 solution is not sufficiently supplied to the cathode 11, resulting in a problem that ion

diffusion is inhibited. The pressure in the cathode chamber 140 is preferably controlled to

a range of 0 PaG or more and 300 KPaG or less in gauge pressure. The pressure in the

cathode chamber 140 can be controlled by the pressure controller 41, for example. The

pressure in the cathode chamber 140 is more preferably controlled to 50 KPaG or more and

200 KPaG or less in gauge pressure. The pressure in the anode chamber 150 is preferably

controlled to 0 PaG or more and 300 KPaG or less in gauge pressure. The pressure in the

anode chamber 150 can be controlled by the pressure controller 42, for example. The

5 pressure in the anode chamber 150 is more preferably controlled to 0 PaG or more and 200

KPaG or less in gauge pressure. The pressure difference (differential pressure) between 2024201352

the cathode chamber 140 and the anode chamber 150 is preferably controlled to 0 PaG or

more and 150 KPaG or less in gauge pressure. The pressure in the cathode chamber 140 is

preferably higher than that in the anode chamber 150. The control of the pressure

10 difference between the cathode chamber 140 and the anode chamber 150 to the range, can

reduce the hydrogen production reaction, which is a side reaction, for example.

[0079] When the control device 80 detects the occurrence of the cross leak from the

cathode chamber 140 to the anode chamber 150, based on a control signal from the control

device 80, at least one of the controllers of the flow rate controller 21, the flow rate

15 controller 22, the pressure controller 41, the pressure controller 42, the power supply 70,

and the temperature controller 71 is controlled, to thereby control the operating conditions

of the electrochemical reaction structure 10. Further, the control device 80 may compare

first data indicating the measured sum with second data registered in the control device 80

and control at least one of the controllers according to a comparison result, to thereby

20 control the pressure difference. The control device 80 may analyze the variation in the

measured sum over time and control at least one of the controllers according to an analysis

result, to thereby control the pressure difference.

[0080] When the cross leak occurs, for example, the control device 80 controls the flow

rate controller 21 to increase the flow rate of the cathode supply fluid flowing through the

25 flow path P1, thereby making it possible to reduce the hydrogen production reaction.

[0081] When the hydrogen production reaction increases due to temperature rise and the

cross leak occurs, the control device 80 controls the flow rate controller 22 to increase the

flow rate of the anode supply fluid flowing through the flow path P2, thereby making it

possible to reduce increasing the temperature of the electrochemical reaction structure 10

to reduce the hydrogen production reaction.

[0082] When the variation in the pressure of the cathode chamber 140 or the pressure in

the anode chamber 150 causes an increase in water inflow from the anode 12 side to the

5 cathode 11 and the cross leak occurs, the control device 80 controls the pressure controller

41 to control the pressure in the cathode chamber 140 and controls the pressure controller 2024201352

42 to control the pressure in the anode chamber 150, thereby making it possible to reduce

electrolyzing water. Further, the control device 80 controls the power supply 70 to reduce

the value of current or voltage to be supplied to the electrochemical reaction structure 10,

10 thereby making it possible to prevent increasing the temperature of the electrochemical

reaction structure 10 to reduce the hydrogen production reaction.

[0083] When the cross leak occurs, the control device 80 controls the heater of the

temperature controller 71 to reduce the temperature of the electrochemical reaction

structure 10, thereby making it possible to reduce the hydrogen production reaction.

15 [0084] The flow path P3 may be connected to a valuable material production device.

Examples of the valuable material production device include a chemical synthesis device

that produces valuable materials through chemical synthesis using raw materials such as

carbon monoxide, and so on. Examples of the valuable material include methanol

produced by a methanol production device, hydrocarbons produced by a Fischer-Tropsch

20 reactor, synthetic gasoline, light oil, jet fuel, olefin compounds produced by an olefin

production device, and so on. The valuable material production device provided so as to

follow the electrochemical reaction structure 10, can produce valuable materials having a

high added value from the product of the electrochemical reaction structure 10.

[0085] The type of the chemical synthesis device is not particularly limited as long as it

25 is capable of causing a reaction to synthesize another substance from the reduction product

produced at the cathode 11. Examples of the reaction using the reduction product by the

chemical synthesis device, include a chemical reaction, an electrochemical reaction,

biological conversion reactions using products such as algae, enzyme, yeast, and bacteria,

and so on.

[0086] The flow path P3 may be connected to a product separator instead of to the

valuable material production device. The product separator can separate a carbon

compound such as carbon monoxide, which is a product, by separating excess carbon

5 dioxide from the cathode exhaust fluid or removing water from the cathode exhaust fluid.

For example, when the carbon monoxide gas is produced in the electrochemical reaction 2024201352

structure 10 by the expression (2), by using, as a raw material, a mixed gas containing the

produced carbon monoxide gas and a hydrogen gas as a byproduct of the reduction

reaction, methanol can be produced through methanol synthesis, or jet fuel, light oil, or the

10 like can be produced through Fischer-Tropsch synthesis. The present invention is not

limited to this, and the flow path P3 may be connected to a tank that stores gas containing

carbon compounds such as carbon monoxide instead of to the valuable material production

device.

[0087] The reduction product may contain hydrogen obtained by electrolysis of carbon

15 dioxide, carbon monoxide, and water. The concentration of hydrogen can be arbitrarily

controlled depending on uses. In the case where hydrogen is used in the chemical

synthesis device, carbon dioxide may be separated from the cathode exhaust fluid to be

used, in order to use the mixture of carbon monoxide and hydrogen. In the case where

hydrogen is not used, carbon monoxide is only separated from the cathode exhaust fluid.

20 In the case where methanol is produced, by controlling the number of moles of hydrogen to

about twice the number of moles of carbon monoxide, the hydrogen produced at the

cathode 11 can be used as a valuable material. In the meantime, at the cathode 11, the side

reaction of hydrogen can be inhibited depending on the reaction conditions to control the

concentration of hydrogen in the reduction product to a range of 0.1% or more and 5% or

25 less in volume percent. This makes it possible to use the electrochemical reaction device

as a carbon monoxide production device that produces high-concentration carbon

monoxide.

[0088] The configurations in the embodiments are applicable in combination, and parts

thereof are also replaceable. While certain embodiments have been described, these

embodiments have been presented by way of example only, and are not intended to limit

the scope of the inventions. Indeed, the novel embodiments described herein may be

embodied in a variety of other forms; furthermore, various omissions, substitutions and

5 changes in the form of the embodiments described herein may be made without departing

from the scope of the inventions. The accompanying claims and their equivalents are 2024201352

intended to cover such forms or modifications as would fall within the scope of the

inventions.

[0089] It is to be understood that, if any prior art publication is referred to herein, such

10 reference does not constitute an admission that the publication forms a part of the common

general knowledge in the art, in Australia or any other country.

[0090] In the claims which follow and in the preceding description of the invention,

except where the context requires otherwise due to express language or necessary

implication, the word “comprise” or variations such as “comprises” or “comprising” is

15 used in an inclusive sense, i.e. to specify the presence of the stated features but not to

preclude the presence or addition of further features in various embodiments of the

invention.

[0091] The embodiments can be summarized into the following clauses.

(Clause 1)

20 An electrochemical reaction device comprising:

an electrochemical reaction structure comprising:

a cathode having a reduction catalyst that promotes a reduction reaction

of reducing carbon dioxide to produce a carbon compound;

an anode having an oxidation catalyst that promotes an oxidation reaction

25 of oxidizing water to produce oxygen;

a diaphragm between the cathode and the anode,

a cathode chamber facing on the cathode; and

an anode chamber facing on the anode;

a first flow path through which a first fluid flows, the first flow path being

cathode chamber and containing the carbon dioxide;

a second flow path through which a second fluid flows, the second flow path

5 being connected to an inlet of the anode chamber, the second fluid being supplied to the

anode chamber and containing the water; 2024201352

a third flow path through which a third fluid flows, the third flow path being

the cathode chamber and containing the carbon compound;

10 a fourth flow path through which a fourth fluid flows, the fourth flow path being

connected to an outlet of the anode chamber, and the fourth fluid being discharged from the

anode chamber and containing the water and the oxygen;

at least one controller selected from the group consisting of a first flow rate

15 controller, a temperature controller and a power supply, the first flow rate controller being

20 control a pressure of the fourth flow path, the temperature controller being configured to

structure, and the at least one controller including the first flow rate controller;

a gas/liquid separator provided in the middle of the fourth flow path and

25 configured to process the fourth fluid to separate a liquid containing the water from the

fourth fluid;

a first flowmeter configured to measure a flow rate of the third fluid flowing

through the third flow path;

a second flowmeter configured to measure a flow rate of the processed fourth

fluid flowing through the fourth flow path; and

a control device connected to the at least one controller, the first flowmeter and

the second flowmeter, the control device being configured to measure a sum of the flow

5 rate of the first fluid flowing through the first flow path, the flow rate of the third fluid

flowing through the third flow path, and the flow rate of the processed fourth fluid flowing 2024201352

through the fourth flow path, and being configured to control the at least one controller

according to the sum to control a pressure difference between the cathode chamber and the

anode chamber.

10 (Clause 2)

The electrochemical reaction device according to clause 1, further comprising:

a humidifier provided in the middle of the first flow path and configured to

humidify carbon dioxide in the first fluid.

(Clause 3)

15 The electrochemical reaction device according to claim 1 or claim 2, further

comprising:

a dehydrator provided in the middle of the third flow path so as to precede the first

flowmeter, and configured to process the third fluid to separate the water from the third

fluid.

20 (Clause 4)

The electrochemical reaction device according to any one of the clause 1 to the

clause 3, wherein

the control device is configured to control the first flow rate controller according

to the sum, and is configured to control the flow rate of the first fluid flowing through the

25 first flow path to control the pressure difference.

(Clause 5)

The electrochemical reaction device according to any one of the clause 1 to the

clause 4, wherein

the at least one controller includes:

the first pressure controller; and

the second pressure controller, and

the control device is configured to control the first pressure controller according to

5 the sum to control the pressure of the third flow path, and to control the second pressure

controller according to the sum to control the pressure of the fourth flow path, and thus 2024201352

control the pressure difference.

(Clause 6)

The electrochemical reaction device according to any one of the clause 1 to the

10 clause 5, wherein

the at least one controller includes the second flow rate controller, and

the control device is configured to control the second flow rate controller

according to the sum, and is configured to control the flow rate of the second fluid flowing

through the second flow path to control the pressure difference.

15 (Clause 7)

The electrochemical reaction device according to any one of the clause 1 to the

clause 6, wherein

the at least one controller includes the temperature controller, and

the control device is configured to control the temperature controller according to

20 the sum, and is configured to control the temperature of the electrochemical reaction

structure to control the pressure difference.

(Clause 8)

The electrochemical reaction device according to the clause 7, wherein

the temperature controller includes a heater configured to heat the electrochemical

25 reaction structure.

(Clause 9)

The electrochemical reaction device according to any one of the clause 1 to the

clause 8, wherein

the at least one controller includes the power supply, and

the control device is configured to control the power supply according to the sum,

and is configured to control the current or the voltage to be supplied to the electrochemical

reaction structure to control the pressure difference.

5 (Clause 10)

The electrochemical reaction device according to any one of the clause 1 to the 2024201352

clause 9, wherein

the control device is configured to compare a first data indicating the sum with a

second data to be stored in the control device, and is configured to control the at least one

10 controller according to a comparison result to control the pressure difference.

(Clause 11)

The electrochemical reaction device according to any one of the clause 1 to the

clause 10, wherein

the control device is configured to analyze variations in the sum over time, and is

15 configured to control the at least one controller according to a result of the analyzation to

control the pressure difference.

(Clause 12)

A method of operating an electrochemical reaction device,

the electrochemical reaction device comprising an electrochemical reaction

20 structure,

the electrochemical reaction structure comprising:

a cathode having a reduction catalyst that promotes a reduction reaction

of reducing carbon dioxide to produce a carbon compound;

an anode having an oxidation catalyst that promotes an oxidation reaction

25 of oxidizing water to produce oxygen;

a diaphragm between the cathode and the anode,

a cathode chamber facing on the cathode; and

an anode chamber facing on the anode;

a first flow path through which a first fluid flows, the first flow path being

cathode chamber and containing the carbon dioxide;

a second flow path through which a second fluid flows, the second flow path

5 being connected to an inlet of the anode chamber, and the second fluid being supplied to

the anode chamber and containing the water; 2024201352

a third flow path through which a third fluid flows, the third flow path being

the cathode chamber and containing the produced carbon compound;

anode chamber and containing the water and the produced oxygen;

at least one controller selected from the group consisting of a first flow rate

a gas/liquid separator provided in the middle of the fourth flow path and

fourth fluid;

a first flowmeter configured to measure a flow rate of the third fluid flowing

through the third flow path; and

a second flowmeter configured to measure a flow rate of the processed fourth

fluid flowing through the fourth flow path,

the method comprising:

supplying the first fluid to the cathode chamber, supplying the second fluid to the

5 anode chamber, and supplying a current or a voltage to the electrochemical reaction

structure, to reduce the carbon dioxide by the cathode to produce the carbon compound and 2024201352

to reduce the water by the anode to produce the oxygen; and

measuring the sum of the flow rate of the first fluid flowing through the first flow

path, the flow rate of the third fluid flowing through the third flow path, and the flow rate

10 of the processed fourth fluid flowing through the fourth flow path and controlling the at

least one controller according to the sum to control a pressure difference between the

cathode chamber and the anode chamber.

(Clause 13)

The method according to the clause 12, wherein

15 a pressure in the cathode chamber is controlled to a range of 0 PaG or more and

300 KPaG or less,

a pressure in the anode chamber is controlled to 0 PaG or more and 300 KPaG or

less,

the pressure difference is controlled to 0 PaG or more and 150 KPaG or less, and

20 the pressure in the cathode chamber is higher than the pressure in the anode

chamber.

(Clause 14)

The method according to clause 12, wherein

the electrochemical reaction device further comprises at least one selected from

25 the group consisting of a humidifier and a dehydrator,

the humidifier is provided in the middle of the flow path and is configured to

humidify carbon dioxide in the first fluid, and

the dehydrator is provided in the middle of the third flow path so as to precede the

first flowmeter and is configured to process the third fluid to separate the water from the

third fluid.

(Clause 15)

The method according to clause 12, wherein

5 the electrochemical reaction device further comprises a control device, and

the control device is configured to control the first flow rate controller according 2024201352

to the sum and is configured to control the flow rate of the first fluid flowing through the

first flow path to control the pressure difference.

(Clause 16)

10 The method according to clause 12, wherein

the electrochemical reaction device further comprises a control device,

the at least one controller includes:

the first pressure controller; and

the second pressure controller, and

15 the control device is configured to control the first pressure controller according to

the sum to control the pressure of the third flow path and controls the second pressure

controller according to the sum to control the pressure of the fourth flow path, and thereby

controls the pressure difference.

(Clause 17)

20 The method according to clause12, wherein

the electrochemical reaction device further comprises a control device,

the at least one controller includes the second flow rate controller, and

the control device is configured to control the second flow rate controller

25 through the second flow path to control the pressure difference.

(Clause 18)

The method according to any one of clause 12 to clause 17, wherein

the electrochemical reaction device further comprises a control device,

the at least one controller includes the temperature controller, and

the sum, and is configured to control the temperature of the electrochemical reaction

structure to control the pressure difference.

5 (Clause 19)

The electrochemical reaction device according to any one of clause 12 to clause 2024201352

17, wherein

the electrochemical reaction device further comprises a control device,

the at least one controller includes the power supply, and

10 the control device is configured to control the power supply according to the sum,

reaction structure to control the pressure difference.

(Clause 20)

The method according to clause 12, wherein

15 the electrochemical reaction device further includes a control device, and

controller according to a comparison result to control the pressure difference, or

20 configured to control the at least one controller according to a result of the analyzation to

control the pressure difference.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. An electrochemical reaction device comprising:

an electrochemical reaction structure comprising:

5 a cathode having a reduction catalyst that promotes a reduction reaction

of reducing carbon dioxide to produce a carbon compound; 2024201352

an anode having an oxidation catalyst that promotes an oxidation reaction

of oxidizing water to produce oxygen;

a diaphragm between the cathode and the anode,

10 a cathode chamber facing on the cathode; and

an anode chamber facing on the anode;

a first flow path through which a first fluid flows, the first flow path being

cathode chamber and containing the carbon dioxide;

15 a second flow path through which a second fluid flows, the second flow path

being connected to an inlet of the anode chamber, the second fluid being supplied to the

anode chamber and containing the water;

a third flow path through which a third fluid flows, the third flow path being

20 the cathode chamber and containing the carbon compound;

a fourth flow path through which a fourth fluid flows, the fourth flow path being

anode chamber and containing the water and the oxygen;

at least one controller selected from the group consisting of a first flow rate

being configured to control a pressure of the third flow path, the second pressure controller

being configured to control a pressure of the fourth flow path, the temperature controller

being configured to control a temperature of the electrochemical reaction structure, the

5 power supply being configured to control a current or a voltage to be supplied to the

electrochemical reaction structure, and the at least one controller including the first flow 2024201352

rate controller;

a gas/liquid separator provided in the middle of the fourth flow path and

10 fourth fluid;

a first flowmeter configured to measure a flow rate of the third fluid flowing

through the third flow path;

a second flowmeter configured to measure a flow rate of the processed fourth

fluid flowing through the fourth flow path; and

15 a control device connected to the at least one controller, the first flowmeter and

rate of the first fluid flowing through the first flow path, the flow rate of the third fluid

flowing through the third flow path, and the flow rate of the processed fourth fluid flowing

20 according to the sum to control a pressure difference between the cathode chamber and the

anode chamber.

2. The electrochemical reaction device according to claim 1, further comprising:

a humidifier provided in the middle of the first flow path and configured to

25 humidify carbon dioxide in the first fluid.

3. The electrochemical reaction device according to claim 1 or claim 2, further

comprising:

fluid.

5

4. The electrochemical reaction device according to any one of claim 1 to claim

3, wherein 2024201352

first flow path to control the pressure difference.

10

5. An electrochemical reaction device comprising:

an electrochemical reaction structure comprising:

a cathode having a reduction catalyst that promotes a reduction reaction

of reducing carbon dioxide to produce a carbon compound;

15 an anode having an oxidation catalyst that promotes an oxidation reaction

of oxidizing water to produce oxygen;

a diaphragm between the cathode and the anode,

a cathode chamber facing on the cathode; and

an anode chamber facing on the anode;

20 a first flow path through which a first fluid flows, the first flow path being

cathode chamber and containing the carbon dioxide;

a second flow path through which a second fluid flows, the second flow path

25 anode chamber and containing the water;

a third flow path through which a third fluid flows, the third flow path being

the cathode chamber and containing the carbon compound;

anode chamber and containing the water and the oxygen;

at least one controller selected from the group consisting of a first flow rate

5 controller, a second flow rate controller, a first pressure controller, a second pressure

controller, a temperature controller and a power supply, the first flow rate controller being 2024201352

10 control a pressure of the third flow path, the second pressure controller being configured to

15 a gas/liquid separator provided in the middle of the fourth flow path and

fourth fluid;

a first flowmeter configured to measure a flow rate of the third fluid flowing

through the third flow path;

20 a second flowmeter configured to measure a flow rate of the processed fourth

fluid flowing through the fourth flow path; and

25 flowing through the third flow path, and the flow rate of the processed fourth fluid flowing

anode chamber, wherein the at least one controller includes:

the first pressure controller; and

the second pressure controller, and

the control device is configured to control the first pressure controller

according to the sum to control the pressure of the third flow path, and to control the

5 second pressure controller according to the sum to control the pressure of the fourth flow

path, and thus control the pressure difference. 2024201352

6. The electrochemical reaction device according to any one of claim 1 to claim

5, wherein

10 the at least one controller includes the second flow rate controller, and

the control device is configured to control the second flow rate controller

through the second flow path to control the pressure difference.

15

7. The electrochemical reaction device according to any one of claim 1 to claim

6, wherein

the at least one controller includes the temperature controller, and

20 structure to control the pressure difference.

8. The electrochemical reaction device according to claim 7, wherein

reaction structure.

25

9. The electrochemical reaction device according to any one of claim 1 to claim

8, wherein

the at least one controller includes the power supply, and

reaction structure to control the pressure difference.

5 10. An electrochemical reaction device comprising:

an electrochemical reaction structure comprising: 2024201352

a cathode having a reduction catalyst that promotes a reduction reaction

of reducing carbon dioxide to produce a carbon compound;

an anode having an oxidation catalyst that promotes an oxidation reaction

10 of oxidizing water to produce oxygen;

a diaphragm between the cathode and the anode,

a cathode chamber facing on the cathode; and

an anode chamber facing on the anode;

a first flow path through which a first fluid flows, the first flow path being

cathode chamber and containing the carbon dioxide;

a second flow path through which a second fluid flows, the second flow path

anode chamber and containing the water;

20 a third flow path through which a third fluid flows, the third flow path being

the cathode chamber and containing the carbon compound;

25 anode chamber and containing the water and the oxygen;

at least one controller selected from the group consisting of a first flow rate

5 control a pressure of the fourth flow path, the temperature controller being configured to

control a temperature of the electrochemical reaction structure, the power supply being 2024201352

a gas/liquid separator provided in the middle of the fourth flow path and

10 configured to process the fourth fluid to separate a liquid containing the water from the

fourth fluid;

a first flowmeter configured to measure a flow rate of the third fluid flowing

through the third flow path;

a second flowmeter configured to measure a flow rate of the processed fourth

15 fluid flowing through the fourth flow path; and

20 through the fourth flow path, and being configured to control the at least one controller

anode chamber, wherein

the control device is configured to compare a first data indicating the sum

with a second data to be stored in the control device, and is configured to control the at

25 least one controller according to a comparison result to control the pressure difference.

11. An electrochemical reaction device comprising:

an electrochemical reaction structure comprising:

a cathode having a reduction catalyst that promotes a reduction reaction

of reducing carbon dioxide to produce a carbon compound;

an anode having an oxidation catalyst that promotes an oxidation reaction

of oxidizing water to produce oxygen;

5 a diaphragm between the cathode and the anode,

a cathode chamber facing on the cathode; and 2024201352

an anode chamber facing on the anode;

a first flow path through which a first fluid flows, the first flow path being

10 cathode chamber and containing the carbon dioxide;

a second flow path through which a second fluid flows, the second flow path

anode chamber and containing the water;

a third flow path through which a third fluid flows, the third flow path being

15 connected to an outlet of the cathode chamber, and the third fluid being discharged from

the cathode chamber and containing the carbon compound;

anode chamber and containing the water and the oxygen;

20 at least one controller selected from the group consisting of a first flow rate

25 flowing through the second flow path, the first pressure controller being configured to

a gas/liquid separator provided in the middle of the fourth flow path and

5 fourth fluid;

a first flowmeter configured to measure a flow rate of the third fluid flowing 2024201352

through the third flow path;

a second flowmeter configured to measure a flow rate of the processed fourth

fluid flowing through the fourth flow path; and

10 a control device connected to the at least one controller, the first flowmeter and

15 according to the sum to control a pressure difference between the cathode chamber and the

anode chamber, wherein

the control device is configured to analyze variations in the sum over

time, and is configured to control the at least one controller according to a result of the

analyzation to control the pressure difference.

20

12. A method of operating an electrochemical reaction device,

the electrochemical reaction device comprising an electrochemical reaction

structure,

the electrochemical reaction structure comprising:

25 a cathode having a reduction catalyst that promotes a reduction reaction

of reducing carbon dioxide to produce a carbon compound;

an anode having an oxidation catalyst that promotes an oxidation reaction

of oxidizing water to produce oxygen;

a diaphragm between the cathode and the anode,

a cathode chamber facing on the cathode; and

an anode chamber facing on the anode;

a first flow path through which a first fluid flows, the first flow path being

5 connected to an inlet of the cathode chamber, and the first fluid being supplied to the

cathode chamber and containing the carbon dioxide; 2024201352

a second flow path through which a second fluid flows, the second flow path

being connected to an inlet of the anode chamber, and the second fluid being supplied to

the anode chamber and containing the water;

10 a third flow path through which a third fluid flows, the third flow path being

the cathode chamber and containing the produced carbon compound;

15 anode chamber and containing the water and the produced oxygen;

at least one controller selected from the group consisting of a first flow rate

20 flow path, the second flow rate controller being configured to measure and control a flow

25 power supply being configured to control a current or a voltage to be supplied to the

electrochemical reaction structure, and the at least one controller including the first flow

rate controller;

a gas/liquid separator provided in the middle of the fourth flow path and

fourth fluid;

a first flowmeter configured to measure a flow rate of the third fluid flowing

through the third flow path; and

5 a second flowmeter configured to measure a flow rate of the processed fourth

fluid flowing through the fourth flow path, 2024201352

the method comprising:

anode chamber, and supplying a current or a voltage to the electrochemical reaction

10 structure, to reduce the carbon dioxide by the cathode to produce the carbon compound and

to oxidize the water by the anode to produce the oxygen; and

of the processed fourth fluid flowing through the fourth flow path and controlling the at

15 least one controller according to the sum to control a pressure difference between the

cathode chamber and the anode chamber.

13. The method according to claim 12, wherein

a pressure in the cathode chamber is controlled to a range of 0 PaG or more and

20 300 KPaG or less,

a pressure in the anode chamber is controlled to 0 PaG or more and 300 KPaG or

less,

the pressure in the cathode chamber is higher than the pressure in the anode

25 chamber.

14. The method according to claim 12, wherein

the group consisting of a humidifier and a dehydrator,

the humidifier is provided in the middle of the flow path and is configured to

humidify carbon dioxide in the first fluid, and

5 first flowmeter and is configured to process the third fluid to separate the water from the

third fluid. 2024201352

15. The method according to claim 12, wherein

the electrochemical reaction device further comprises a control device, and

10 the control device is configured to control the first flow rate controller according

first flow path to control the pressure difference.

16. The method according to claim 12, wherein

15 the electrochemical reaction device further comprises a control device,

the at least one controller includes:

the first pressure controller; and

the second pressure controller, and

20 the sum to control the pressure of the third flow path and controls the second pressure

controls the pressure difference.

17. The method according to claim 12, wherein

25 the electrochemical reaction device further comprises a control device,

the at least one controller includes the second flow rate controller, and

the control device is configured to control the second flow rate controller

through the second flow path to control the pressure difference.

18. The method according to any one of claim 12 to claim 17, wherein

the electrochemical reaction device further comprises a control device,

5 the at least one controller includes the temperature controller, and

the control device is configured to control the temperature controller according to 2024201352

structure to control the pressure difference.

10

19. The electrochemical reaction device according to any one of claim 12 to

claim 17, wherein

the electrochemical reaction device further comprises a control device,

the at least one controller includes the power supply, and

15 and is configured to control the current or the voltage to be supplied to the electrochemical

reaction structure to control the pressure difference.

20. The method according to claim 12, wherein

the electrochemical reaction device further includes a control device, and

20 the control device is configured to compare a first data indicating the sum with a

configured to control the at least one controller according to a result of the analyzation to

25 control the pressure difference.