WO2019212071A1

WO2019212071A1 - Electrochemical dehydration reactor and method for manufacturing hydrogen by using same

Info

Publication number: WO2019212071A1
Application number: PCT/KR2018/005040
Authority: WO
Inventors: 문상봉; 최윤기; 윤대진; 문창환; 정혜영
Original assignee: (주)엘켐텍
Priority date: 2018-04-30
Filing date: 2018-04-30
Publication date: 2019-11-07
Also published as: KR20190125885A

Abstract

The electrochemical dehydration reactor of the present invention has a positive electrode room and a negative electrode room on both sides of a solid polymer electrolyte membrane, respectively. A hydrogenated organic matter supplied into the positive electrode room is degraded into an organic compound, protons, and electrons, which are then moved into the negative electrode room to generate hydrogen.

Description

Electrochemical Dehydrogenation Reactor and Process for Producing Hydrogen Using the Same

The present invention relates to an electrochemical dehydrogenation reactor, and more particularly, to an electrochemical dehydrogenation reactor in which hydrogenated hydrogenated organics are oxidized in an anode chamber and hydrogen is generated by a reduction reaction in a cathode chamber. In addition, the present invention also relates to a method for producing hydrogen using the electrochemical dehydrogenation reactor as described above.

Renewable energy is actively introduced at home and abroad for the purpose of reducing CO ₂ . However, renewable energy such as wind power generation and solar power generation has a problem in that the power generation is irregular and the inconsistency between the power demand and the power generation is very large. As an alternative to this, a device such as a battery can be used for instantaneous energy storage and output control, but it is difficult to apply due to the high cost due to seasonal factors (summer and winter) and long distance energy transmission.

Accordingly, energy carriers capable of storing power obtained from these renewable energies for a long time or transporting them to remote locations are being considered. Energy carriers include liquid hydrogen (or compressed hydrogen), ammonia, organic hydride (Liquid Organic Hydrogen Carrier, hereinafter referred to as "LOHC"), and the like. At present, since hydrogen carriers are gas at room temperature and atmospheric pressure (low weight and volume energy density), a special tank is required for transportation and storage. In contrast, LOHC is a hydrogen carrier that is liquid at room temperature and atmospheric pressure, has similar properties to petroleum, and is easy to transport using existing infrastructure. Representative LOHCs include benzene, naphthalene, toluene, N-ethylcarbazole, pyridine, and the like, which are hydrogenated organic compounds by hydrogenation.

Hydrogenation of toluene (TL), one of LOHCs, to methylcyclohexane, a hydrogenated organic compound, has been proposed by chemical reaction and electrochemical synthesis. The most common method is a chemical reaction using a catalyst.

As for the method of obtaining hydrogen from methylcyclohexane, which is a hydrogenated organic substance (dehydrogenation method), all processes are known to use a chemical reaction method. The chemical reaction method uses a catalyst and uses high temperature heat.

However, the process by the chemical reaction method has a problem in practical use for the following reasons. First, there are limitations in application where high temperature heat cannot be obtained. Second, it has low reaction selectivity in reactions using high temperature heat.

[Prior art document]

Hydrogen-stored as an oil (April 2018, HYDROGENIOUS TECHNOLOGIES GmbH

Therefore, the present invention was developed to solve the problems of the prior art as described above, an electrochemical dehydrogenation reactor for supplying a hydrogenated hydrogenated organic material to the anode chamber to oxidize it at the anode, and to produce hydrogen at the cathode and this Its purpose is to provide a method for producing used hydrogen.

The electrochemical dehydrogenation reactor of the present invention for achieving the above object is provided with a cathode chamber and a cathode chamber on each side of the solid polymer electrolyte membrane, the hydrogenated organic material supplied to the anode chamber is an organic compound, protons and electrons After decomposition to move to the cathode chamber is characterized in that for producing hydrogen.

In addition, according to the present invention, the hydrogenated organic material is methylcyclohexane, and the organic compound is characterized in that toluene (toluene).

In addition, according to the present invention, a reaction layer and a diffusion layer in which electrochemical oxidation and reduction occur on both sides of the solid polymer electrolyte membrane are further sequentially formed to form a membrane electrode assembly.

In addition, according to the present invention, the solid polymer electrolyte membrane is a fluorine-based polymer membrane-based or hydrocarbon-based polymer membrane-based material, characterized in that having a thickness of 5 ~ 300㎛.

In addition, according to the present invention, the reaction layer includes a catalyst and a carrier supporting the catalyst to enlarge the reaction surface area of the catalyst, the particle size of the catalyst is 0.001 ~ 0.1㎛, the particle size of the carrier is 10 It is characterized by a ~ 1000nm.

According to this invention, the diffusion layer is made of carbon or metal, and has a thickness of 0.1 to 2 mm and an opening ratio of 30 to 70%.

Hydrogen production method of the present invention for achieving the above object is characterized in that for producing hydrogen using the electrochemical dehydrogenation reactor configured as described above.

In addition, according to the present invention, the supplied current is 0.01A / cm ² ~ 2.0A / cm ² per unit area, characterized in that the operating temperature is 10 ℃ ~ 100 ℃.

In addition, according to this invention, the pressure of the hydrogen supplied is characterized in that 0.1bar ~ 350bar.

The present invention is to supply the hydrogenated hydrogenated organic material to the anode chamber to oxidize it at the anode, and to produce hydrogen at the cathode, because it uses an electrochemical method that can be operated at room temperature and atmospheric pressure, not the reaction of high temperature and high pressure during the dehydrogenation reaction. In addition, there is an advantage in that the operation at the start and stop operation is excellent.

In addition, the present invention is a method of using an electrolysis cell in which the anode and the cathode are integrated into the membrane, and thus it is possible to operate at low power, thereby reducing the operating cost significantly.

1 is a conceptual diagram of an electrochemical dehydrogenation reactor according to the present invention,

2 is a structural diagram of a membrane electrode assembly applied to the electrochemical dehydrogenation reactor of the present invention,

3 is a structural diagram of an electrochemical cell used as an electrochemical dehydrogenation reactor of the present invention,

4 is a structural diagram of an electrochemical stack used as an electrochemical dehydrogenation reactor of the present invention,

5 and 6 are graphs of the voltage-current density and the hydrogenation amount for the embodiments tested by applying the electrochemical dehydrogenation reactor according to the present invention.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of an electrochemical dehydrogenation reactor and a method for producing hydrogen using the same according to the present invention will be described in detail.

Hereinafter, in this embodiment, a method of obtaining hydrogen from MCH using toluene (TL) as an organic compound and methylcyclohexane (MCH) as a hydrogenated organic material will be described as an example.

1 is a conceptual diagram of an electrochemical dehydrogenation reactor according to this invention. As shown in FIG. 1, the electrochemical dehydrogenation reactor of the present invention is composed of a positive electrode 110, a solid polymer electrolyte membrane 120, and a negative electrode 130.

That is, when the MCH is supplied to the anode 110, the MCH is decomposed into toluene (TL), protons, and electrons at the anode, and the proton passes through the solid polymer electrolyte membrane 120 to the cathode 130. It is configured to move and cause a hydrogen reaction. At this time, the theoretical electrode reaction is 1.20V, the actual operation is about 2.0V in consideration of the overvoltage, etc., it is possible to significantly reduce the operating energy compared to the operation method of the conventional catalytic decomposition process.

2 is a structural diagram of a membrane electrode assembly 200 applied to the electrochemical dehydrogenation reactor of the present invention. As shown in FIG. 2, the most important part of the components of the electrochemical cell is a membrane electrode assembly (hereinafter referred to as "MEA"). The MEA 200 integrates the

reaction layers

204 and 208 where the electrochemical oxidation reaction and the reduction reaction take place and the solid polymer electrolyte membrane (hereinafter referred to as Proton exchange membrane, hereinafter referred to as "PEM"), or This means that the

diffusion layers

202 and 210 are integrated in addition to the

reaction layers

204 and 208 and the PEM 206 of the same oxidation and reduction reaction.

In the following, the place where the oxidation reaction occurs is described as the first electrochemical reaction layer 204 and the place where the reduction reaction occurs as the second electrochemical reaction layer 208, where the current is applied to the oxidation reaction and Reduction reactions occur simultaneously.

When MCH is supplied to the first electrochemical reaction layer 204 via the first diffusion layer 202, MCH is toluene (TL), electrons (e) in the first electrochemical catalyst 212 (oxidation catalyst, positive electrode active material electrode) ^-) and it is decomposed into hydrogen ions (H ⁺⁾ (proton) (see scheme 1). At this time, the hydrogen ion (H ⁺ ) is passed through the PEM 206 by the electric field to the second electrochemical catalyst 216 (reduction catalyst, negative electrode active material, or hydrogen gas generating electrode), electron (e ⁻ ) is The first electrochemical catalyst 212 moves to the second electrochemical catalyst 216 through the first diffusion layer 202, an external circuit (not shown), and the second diffusion layer 210.

In the second electrochemical catalyst 216, hydrogen ions (H ⁺ ) moved from the first electrochemical catalyst 212 and electrons (e ⁻ ) react to generate hydrogen (see Scheme 2).

The electrochemical reactions occurring in the first electrochemical catalyst 112 and the second electrochemical catalyst 116, respectively, are represented by the following

Reaction Schemes

1, 2, and 3.

Scheme 1

MCH (methyl cyclohexane) → TL (toluene) ⁺ 6H + + 6e ^- (anode reaction, an oxidation reaction)

Scheme 2

^{^{_{6H + + 6e - → 3H 2}}} ( cathode reaction, reduction reaction)

Scheme 3

MCH (methylcyclohexane) → TL (toluene) + 3H ₂ (total reaction)

Hereinafter, the components applied to the electrochemical cell of the present invention will be described.

The PEM 206 has a sulfonic acid ion exchange group that is excellent in oxidation reaction or long-term stability against organic compounds (TL and MCH), and has excellent hydrogen ion (proton or H ⁺ ) conductivity, and an anode chamber material (TL, MCH). It should be possible to prevent the mixing and diffusion of the cathode chamber material (hydrogen). As an example, Nafion (Nafion, registered trademark) of DuPont, Flemion (Flemion, registered trademark) of Asahi Glass Co., Ltd., Aciplex (Asiplex, registered trademark) of Asahi Glass Co., Ltd. Gore Select (registered trademark) and the like can be used, and hydrocarbon-based polymer membranes include sulfonated polyether ketones, sulfonated polyether sulfones, sulfonated polyether ether sulfones, sulfonated polysulfides and sulfonated polyphenylenes. Etc. can be used.

5-300 micrometers is preferable and, as for the thickness of a PEM, 20-170 micrometers is especially preferable. If the thickness of the PEM is less than 5 µm, cross leakage (product leakage from the cathode chamber to the anode chamber) is likely to occur, and if the thickness of the PEM becomes thicker than 300 µm, the proton resistance becomes large, which consumes a lot of electrical energy, which is undesirable. not.

The first and second

electrochemical catalysts

212 and 216 are platinum, palladium, ruthenium, iridium, rhodium, osmium, platinum group elements, iron, lead, copper, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, Metals such as aluminum, alloys thereof, oxides, and complex oxides may be used. Platinum, palladium, rhodium, ruthenium, and iridium may be used for excellent electrode reactivity and to efficiently and stably use the electrode reaction for a long time. Preference is given to using one or two or more metals or oxides selected from.

The particle size of the first and second

electrochemical catalysts

212 and 216 is too low, so that the activity of the catalyst is lowered. If the particle size is too small, the stability of the catalyst is lowered. Preferably it is 1-50 nm.

In order to increase the reaction surface area of the catalyst, carriers (or carriers) 214 and 218 supporting the catalyst are preferably in the form of electron conductive particles, and include metal oxides including titanium, carbon black, graphite, graphite, activated carbon, and carbon. Preference is given to using fibers, carbon nanotubes, fullerenes. In addition, the

carriers

214 and 218 are difficult to form an electron conductive pathway generated when the particle size is too small. When the particle size is too large, the gas diffusion into the electrode catalyst layer formed on the carrier is reduced, Since the utilization rate decreases, the particle diameter is preferably 10 to 1,000 nm, more preferably 10 to 100 nm.

The first and second diffusion layers 202 and 210 may be made of carbon or metal. In addition, the first and second diffusion layers 202 and 210 may use cloth, paper, sintered fiber, or the like. The first diffusion layer 202 is coated with a hydrophobic material such as polytetrafluoroethylene (PTFE) on the surface to facilitate gas fluid flow, and a carbon-based material having excellent corrosion resistance against hydrogen is particularly preferable. The second diffusion layer 210 is not limited to the material. In addition, the first and second diffusion layers 202 and 210 preferably have a thickness of 0.1 to 2 mm and an opening ratio of about 30 to 70% to promote diffusion of gas.

The manufacturing process of the MEA 200 is composed of a catalyst synthesis process, a catalyst ink production process, a catalyst ink transfer process, and a thermocompression process (a process of forming the transferred catalyst ink in a PEM or diffusion layer).

In the catalyst synthesis step, catalysts and carriers may use commercially available particles, but may be synthesized according to a known method and used. For example, the synthesis | combination may employ | adopt the wet method which mixes and synthesize | combines a reducing agent in the aqueous solution which melt | dissolves a catalyst metal ion, or may employ | adopt dry methods, such as vapor deposition sputtering.

The catalyst ink manufacturing process includes the

catalysts

212 and 216 obtained in the catalyst synthesis process and the

carriers

214 and 218 having the same, hydrophobic resins, solvents, and the like so that catalysts are easily formed in the PEM 206 or the diffusion layers 202 and 210. It is a process of mixing Nafion (trademark) dispersion liquid which is an ionomer.

The catalyst ink for the first electrochemical reaction layer 204 includes a first electrochemical catalyst 212, a carrier 214, a polymer electrolyte ionomer, a solvent and a hydrophobic resin, and the second electrochemical reaction layer 208. Catalyst inks include a second electrochemical catalyst 216, a carrier 218, a polymer electrolyte ionomer, a solvent and a hydrophobic resin. Hydrophobic resin (fluorine-type high molecular component) is a gas permeable material, It is preferable that the particle diameter of the powder is 0.005-10 micrometers. In the case of the anode catalyst (first electrochemical catalyst 212) or the reduction catalyst (second electrochemical catalyst 216) used in the first electrochemical reaction layer 204, the amount of catalyst in each layer is 0.01 mg / cm ² is preferably such that more than, 10mg / cm ² or less. This is because the reaction efficiency is lowered at less than 0.01 mg / cm ² , and the installation cost of the electrochemical reaction cell is increased at more than 10 mg / cm ² .

The catalyst ink transfer process is a process of transferring the catalyst ink prepared under the above conditions to a transfer paper (eg, Teflon sheet, polyimide sheet), leaving the main catalyst component and removing the solvent component. This transfer step may be omitted in the case where the catalyst ink is directly sprayed onto the PEM or the diffusion layer.

The thermocompression process is a process of transferring the catalyst layer formed on the transfer paper to the film or the diffusion layer through thermal and compression. As a processing apparatus, well-known apparatuses, such as a hot press and a hot roller, can be used. As for press conditions, room temperature-360 degreeC, and the pressure of 0.1-5 Mpa are preferable.

Figure 3 is an electrochemical cell used as the electrochemical dehydrogenation reactor of the present invention, a structural diagram of an electrochemical cell 300 having a membrane electrode assembly shown in Figure 2, Figure 4 is an electrochemical dehydrogenation reactor of the present invention As an electrochemical stack used as a structure, it is a structural diagram of an electrochemical stack 400 formed by stacking a plurality of unit electrochemical cells shown in FIG. 3.

As shown in FIG. 3, the electrochemical cell 300 includes a first end plate 302, a first insulating plate 304, a first current supply plate 306, and a first electrochemical reaction chamber frame 308), the first electrochemical reaction chamber 310, the MEA (200 in FIG. 2), the second electrochemical reaction chamber 312, the second electrochemical reaction chamber frame 314, and the second current supply plate 316. In addition to the second insulating plate 318 and the second end plate 320, a power converter 324 for supplying a current to the electrochemical cell is provided with a DC power supply.

In the first electrochemical reaction chamber 310 (anode chamber) and the second electrochemical reaction chamber 312 (cathode chamber), flow paths (see (a) of FIG. 3) for supplying and discharging respective reactants or products are formed. It is configured to perform a function of mechanically supporting the MEA 200 and an electrical connection function with an adjacent unit cell.

The first end plate 302 and the second end plate 320 provide a bolt / nut fastening hole (not shown) for the unit electrochemical cell assembly, and a passage (not shown) for reactants and products, and a first insulating plate. 304 and the second insulating plate 318 are electrically connected between the first end plate 302 and the first current supply plate 306 and between the second end plate 320 and the second current supply plate 316, respectively. Insulating function, the first current supply plate 306 and the second current supply plate 316 is connected to the power converter 324 serves to supply the current required for the electrochemical cell 300.

On the other hand, when the first electrochemical catalyst 212 is located in the first electrochemical reaction chamber 310 and the oxidation reaction occurs, it becomes a space for the movement of the reactant MCH, the product TL (toluene), PEM (206) In the second electrochemical reaction chamber 312 which is located opposite to the first electrochemical reaction chamber 310 with respect to), space for external discharge of hydrogen by a reduction reaction is provided.

The first electrochemical reaction chamber 310 is isolated from the outside by the first electrochemical reaction chamber frame 308, and the second electrochemical reaction chamber 312 is external by the second electrochemical reaction chamber frame 314. Is blocked. In addition, a gasket (or packing) 322 is installed between the MEA 200, the first electrochemical reaction chamber frame 308, and the second electrochemical reaction chamber frame 314 to prevent external leakage of reactants and products. .

Among the components constituting the electrochemical cell 300, the first electrochemical reaction chamber frame 308, the second electrochemical reaction chamber frame 314, and the gasket 322 are introduced into a reactant or a product through the electrochemical cell. And an appropriate hole to facilitate outflow, and a flow path (indicated by a dotted line in FIG. 3A) is formed in the first electrochemical reaction chamber frame 308 and the second electrochemical reaction chamber frame 314.

In order to obtain a desired amount of the product, a plurality of unit electrochemical cells are required, and at this time, a collection of two or more stacked electrochemical cells may be formed as an electrochemical stack 400 and operated (see FIG. 4).

The following describes the operation method of the electrochemical cell.

As in the example of FIG. 3, reactant 1 (MCH, methylcyclohexane) is supplied to the lower portion of the first electrochemical reaction chamber 310 of the electrochemical cell 300. Then, hydrogen is generated in the second electrochemical reaction chamber 312 by the reaction scheme as described above, wherein the purity of the hydrogen becomes 90% or more.

Here, the current supplied to the first electrochemical reaction layer 204 and the second electrochemical reaction layer 208 is preferably 0.01 A / cm ² to 2.0 A / cm ² per unit area. This is because, in the case of 0.01A / cm ² or less, the electrolytic reaction area is increased, which increases the investment cost, and in 2.0A / cm ² or more, there is a problem in that durability of the components of the electrolysis cell due to overvoltage is deteriorated. .

Although the operating temperature of an electrolysis cell is 10 degreeC-100 degreeC, 50 degreeC-80 degreeC is more preferable. This is because the proton transfer resistance increases at 10 ° C. or lower, and deterioration in durability of the electrolysis cell component is a problem at 100 ° C. or higher.

The hydrogen pressure supplied to the electrolysis cell is appropriately 0.1 bar to 350 bar. This is because, at 0.1 bar or less, electrolysis efficiency is reduced due to despreading of the cathode chamber, and at least 350 bar, the durability deterioration of components of the electrolysis cell becomes a problem.

Examples of the present invention will be described in detail below, but these examples are merely illustrative for describing the present invention preferably, and do not limit the present invention at all.

Example 1 Dehydrogenation of MCH (Methylcyclohexane) (Product TL (Toluene))

MEF 200, Nafion 117 perfluorocarbonsulfonic acid film (thickness 170), first electrochemical reaction layer 204 (anode catalyst, Pt / C carrier (Tanaka Precious Metal Industry)) 0.5 mg / cm ² and agent 2 electrochemical reaction layer 208 (cathode catalyst, Pt-Ru / C carrier (Tanaka Precious Metal Industry)) 0.5 mg / cm ² , first diffusion layer 202 (carbon paper) and second diffusion layer 210, titanium sintered fiber aperture ratio 80%, thickness 0.2mm, Descartes, Germany). The area (electrochemical reaction area) of the MEA 200 was 25 cm ² .

MCH was supplied to the lower part of the first electrochemical reaction chamber 310 (anode chamber) of the electrochemical cell 300 to obtain hydrogen in the second electrochemical reaction chamber 312 (cathode chamber). At this time, the current supplied to the electrochemical cell 300 was 1A / cm ² , the temperature was 80 ° C., and the hydrogen supply pressure was 5 bar.

The performance was evaluated for the voltage-current performance of the electrochemical cell (Example 1 of FIG. 5), and the degree of dehydrogenation (amount of hydrogenation) was measured by measuring the weight change rate (Example 1 of FIG. 6) of the product TL.

Example 2 Dehydrogenation of C ₁₄ H ₂₅ N (3-butyladamantan-1-amine) (Product N-ethylcarbazole)

The MEA was configured in the same manner as the MEA 200 of the first embodiment.

By supplying C ₁₄ H ₂₅ N (3-butyladamantan-1-amine) to the lower part of the first electrochemical reaction chamber 310 (anode chamber) of the electrochemical cell 300, the second electrochemical reaction chamber 312, the negative electrode Hydrogen). At this time, the current, temperature, and hydrogen supply pressure supplied to the electrochemical cell 300 were the same as in Example 1.

Performance is dehydrogenated by evaluating the voltage-current performance of the electrochemical cell (Example 2 of FIG. 5) and measuring the weight change rate (Example 2 of FIG. 6) of the product N-ethylcarbazole. Degree (hydrogenation amount) was measured.

Hydrogen generation and electricity consumption from the electrochemical dehydrogenation reactor according to the present invention was confirmed to be significantly improved. In addition, it was confirmed that the electrochemical dehydrogenation reactor according to the present invention can be effectively used for the dehydrogenation reaction without a heat source.

This invention is not limited to the above-mentioned embodiment, It is also possible to add a deformation | transformation, such as various design changes, based on the knowledge of a person skilled in the art, The embodiment to which such a modification was added is also included in the scope of this invention.

Claims

A cathode chamber and a cathode chamber are respectively provided on both sides of the solid polymer electrolyte membrane.

Electrochemical dehydrogenation reactor, characterized in that the hydrogenated organic material supplied to the anode chamber is decomposed into organic compounds, protons and electrons to move to the cathode chamber to produce hydrogen.
The method according to claim 1,

The hydrogenated organic material is methylcyclohexane, the organic compound is toluene (toluene) characterized in that the electrochemical dehydrogenation reactor.
The method according to claim 1,

An electrochemical dehydrogenation reactor, characterized in that a reaction layer and a diffusion layer in which electrochemical oxidation and reduction occur on both sides of the solid polymer electrolyte membrane are sequentially formed to form a membrane electrode assembly.
The method according to claim 3,

The solid polymer electrolyte membrane is a fluorine-based polymer membrane-based or hydrocarbon-based polymer membrane-based material, the electrochemical dehydrogenation reactor, characterized in that having a thickness of 5 ~ 300㎛.
The method according to claim 3,

The reaction layer includes a catalyst and a carrier supporting the catalyst to enlarge the reaction surface area of the catalyst,

Particle diameter of the catalyst is 0.001 ~ 0.1㎛, electrochemical dehydrogenation reactor, characterized in that the particle size of 10 ~ 1,000nm.
The method according to claim 3,

The diffusion layer is made of carbon or metal, the thickness of 0.1 ~ 2mm, the opening ratio of 30 to 70%, characterized in that the electrochemical dehydrogenation reactor.
Hydrogen is produced using the electrochemical dehydrogenation reactor according to any one of claims 1 to 6.
The method according to claim 7,

Supply current is 0.01A / cm 2 ~ 2.0A / cm 2 per unit area, the operating temperature is a method for producing hydrogen, characterized in that 10 ℃ ~ 100 ℃.
The method according to claim 7,

The pressure of the hydrogen supplied is a method for producing hydrogen, characterized in that 0.1bar ~ 350bar.