JP2018051543A - Manufacturing method of dried water electrolysis gas and device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for safely manufacturing dried water electrolysis gas with excellent energy efficiency, from high humidity water electrolysis gas manufactured by water electrolysis.SOLUTION: A manufacturing method of dried water electrolysis gas includes a water electrolysis gas generating process of providing water electrolysis gas by electrolyzing water, an absorption process of selectively absorbing steam in an absorbent by contacting the water electrolysis gas of including steam derived from raw material water and the absorbent of including an ion liquid and a separation process of gas-liquid-separating dried water electrolysis gas reduced in humidity in the absorption process and a rich absorbent of absorbing the steam.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing dry water electrolysis gas and an apparatus therefor.

  Renewable energies such as solar and wind are valuable energy resources. However, suitable places for sunshine and wind conditions are unevenly distributed, and the obtained place is remote from the consumption place, and the generated power obtained varies depending on the season and time. Therefore, research is underway on how to use renewable energy by converting it to hydrogen in order to adjust the location, amount, and timing. For example, there are methods of producing hydrogen by electrolyzing water, such as alkaline water electrolysis and solid polymer water electrolysis. This water electrolysis can produce oxygen at the same time.

  Patent Document 1 discloses a water electrolysis apparatus using a solid polymer electrolyte membrane. In this water electrolysis apparatus, when water is supplied to the anode side of the solid polymer electrolyte membrane, oxygen gas and hydrogen ions are generated on the anode side. The hydrogen ions move with water to the cathode side through the polymer electrolyte membrane, and react with the cathode side to generate hydrogen gas. From this cathode side, hydrogen gas and water in which hydrogen gas is dissolved are discharged. Hydrogen gas is taken out of the water in which hydrogen gas is dissolved by the gas-liquid separator. From the anode side, oxygen gas and water in which oxygen gas is dissolved are discharged.

  Patent Document 2 discloses a solid polymer type high pressure vessel-accommodated water electrolysis hydrogen generator using a polymer electrolyte membrane. In this hydrogen generator, hydrogen generated from the cathode side of the electrolytic cell is sent to a hydrogen gas-liquid separator via a hydrogen line, where it is separated from water and gas-liquid, and further sent to a hydrogen tank via a hydrogen line. Oxygen generated from the anode side of the water electrolysis tank is sent to an oxygen gas-liquid separator, where it is separated from water and gas-liquid, and supplied to a predetermined location via an oxygen line.

JP 2010-280975 A JP 2006-199995 A

  In the water electrolysis gas obtained by these water electrolysis, hydrogen gas is separately obtained from the anode side and oxygen gas is separately obtained from the cathode side. Further, it does not contain by-products such as carbon dioxide like hydrogen gas obtained by steam reforming of hydrocarbons. On the other hand, the raw material water is accompanied by water vapor. Therefore, depending on the application, it is necessary to remove it and make it highly purified.

  As a general dehumidification process of gas, there is a process of lowering the dew point by cooling a mixed gas containing water vapor with a chiller, and a process of bringing the mixed gas containing water vapor into contact with an adsorbent or absorbent.

  However, when the former dehumidification process is applied to the water electrolysis gas, not only the water to be removed but also the water electrolysis gas itself must be cooled, which requires extra energy. In addition, hydrogen gas of water electrolysis gas is often compressed after dehumidification, stored and transported. However, a decrease in partial pressure of hydrogen gas due to cooling leads to an increase in compression energy in the subsequent compression process, which is disadvantageous in terms of energy. It becomes.

  The latter dehumidification process includes a method using a solid adsorbent and a liquid absorbent. When dehumidification is performed using a solid adsorbent such as zeolite, heat treatment must be performed at a high temperature (up to 200 ° C.) in order to regenerate the solid adsorbent that has absorbed moisture. Therefore, when this dehumidification process is applied to a water electrolysis gas having a large amount of water, a large amount of energy is required. In general, dehumidification with a solid adsorbent is performed by batch processing (two-cylinder or multi-cylinder type). In this batch process, it is necessary to heat the entire batch processing unit and cool it thereafter. And in this process, since heat exchange is difficult, a large amount of energy is required.

  As a liquid absorbent, triethylene glycol (TEG) is known as a gas absorbent or an air conditioner. However, if TEG is used as an absorbent, the absorbent itself has a vapor pressure, which hinders high purity of hydrogen. Further, TEG has flammability and has other problems such as being unsuitable for targeting hydrogen gas and oxygen gas.

  Accordingly, an object of the present invention is to provide a method for producing a dry water electrolysis gas that is energy efficient and safe from a high humidity water electrolysis gas produced by water electrolysis.

  As a result of intensive studies to achieve the above problems, the present inventors have found that an ionic liquid is useful for dehumidification of a high-humidity water electrolysis gas produced by water electrolysis. Based on these findings, the present inventors have completed the present invention.

In order to solve the above problems, the method for producing a dry water electrolysis gas of the present invention comprises:
A water electrolysis gas generation step of electrolyzing water to obtain a water electrolysis gas;
An absorption step in which the water electrolysis gas containing water vapor derived from raw water obtained in the water electrolysis gas generation step is brought into contact with an absorption liquid containing an ionic liquid to selectively absorb water vapor into the absorption liquid; ,
A dry water electrolysis gas having reduced humidity in the absorption step, and a separation step of gas-liquid separation of the rich absorption liquid that has absorbed water vapor.

  It is preferable to further include a heat exchanging step of exchanging heat between the water electrolysis gas before the absorbing step and the rich absorbent.

  It is preferable to further include a regeneration step in which the rich absorbent is heated and / or decompressed to remove moisture and regenerate the absorbent.

  It is preferable to further include a second heat exchange step in which heat exchange is performed between the absorbent regenerated in the regeneration step and the rich absorbent.

  The anion constituting the ionic liquid is preferably an oxoacid ion.

The oxo acid ion is a carboxylate ion represented by formula 1, nitrate ion, sulfate ion, hydrogen sulfate ion, sulfonate ion represented by formula 2, phosphate ester ion or phosphate ion represented by formula 3. Or a phosphonate ester ion or a phosphonate ion represented by Formula 4.

(In Formula 1, R ¹ is a hydrogen atom or a hydrocarbon group which may be unsubstituted or substituted.)
(In Formula 2, R ² is a hydrogen atom or a hydrocarbon group which may be unsubstituted or substituted.)
(In Formula 3, R ³ and R ⁴ are a hydrogen atom or an unsubstituted or substituted hydrocarbon group.)
(In Formula 4, R ⁵ is a hydrogen atom or an unsubstituted or substituted hydrocarbon group.)

  The water electrolysis gas is preferably hydrogen gas.

In addition, the dry water electrolysis gas production apparatus of the present invention comprises:
Water electrolysis gas generating means for electrolyzing water to obtain water electrolysis gas;
Absorbing means for selectively absorbing water vapor in the absorbing liquid by bringing the water electrolyzed gas containing water vapor derived from raw water obtained by the water electrolyzing gas generating means into contact with an absorbing liquid containing an ionic liquid. When,
A dry water electrolysis gas whose humidity has been reduced by the absorption means; and a separation means for separating the rich absorption liquid that has absorbed water vapor into a gas-liquid separation.

  Preferably, the dry water electrolysis gas production apparatus further includes a regeneration means for heating and / or depressurizing the rich absorbent that has absorbed water vapor to remove moisture and regenerate the absorbent.

  INDUSTRIAL APPLICABILITY According to the present invention, there is provided a method for producing a dry water electrolysis gas that is energy efficient and safe from a high humidity water electrolysis gas produced by water electrolysis.

The figure which shows the one aspect | mode of the manufacturing apparatus of the dry water electrolysis gas of this invention. Relative humidity dependence of water vapor absorption at 25 ° C. for calcium chloride and various ionic liquids. Relative humidity dependence of water vapor absorption at 80 ° C. for calcium chloride and various ionic liquids.

  The method for producing a dry water electrolysis gas of the present invention includes a water electrolysis gas generation step of electrolyzing water to obtain hydrogen and oxygen, and water electrolysis containing water vapor derived from raw water obtained in the hydrogen and oxygen generation step. An absorption step in which a gas and an absorption liquid containing an ionic liquid are brought into contact with each other to selectively absorb water vapor into the absorption liquid; a dry water electrolysis gas with reduced humidity in the absorption step; and a rich absorption in which water vapor is absorbed A separation step of gas-liquid separation of the liquid.

(Water electrolysis gas generation process)
The hydrogen and oxygen production step according to the present invention is not particularly limited as long as it is a method for electrolyzing water to obtain a water electrolysis gas, and examples thereof include alkaline water electrolysis, solid polymer water electrolysis, and high-temperature steam electrolysis.

  In alkaline water electrolysis, an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution is usually used as the electrolyte. In alkaline water electrolysis, since hydrogen and hydroxide ions are obtained from water on the cathode side, the obtained hydrogen gas contains water at a high humidity corresponding to the vapor pressure. And since water and oxygen are obtained from hydroxide ions on the anode side, the obtained oxygen contains water at a high humidity corresponding to the vapor pressure. In this way, oxygen is obtained on the anode side (anode side) and hydrogen is obtained on the cathode side (cathode side), so that hydrogen and oxygen can be obtained separately, but each with high humidity corresponding to the vapor pressure. Contains water. The electrolysis temperature of alkaline water electrolysis is usually room temperature to 200 ° C, preferably 70 ° C to 90 ° C. When the temperature is high, the electrode reaction rate tends to be improved.

  In solid polymer type water electrolysis, a proton type cation membrane such as a fluororesin cation membrane is usually used as an electrolyte membrane. In polymer electrolyte water electrolysis, oxygen and hydrogen ions are generated when water is supplied to the anode side. The hydrogen ions move through the film to the cathode side, obtain electrons, and become hydrogen. As the hydrogen ions move in the membrane, water also moves to the cathode side as affinity water. On the cathode side, the generated gas and the moved water are gas-liquid separated to obtain hydrogen gas. The obtained hydrogen gas contains water at a high humidity corresponding to the vapor pressure. Thus, hydrogen and oxygen can be obtained separately, but each contains water at a high humidity corresponding to the vapor pressure. The electrolysis temperature of solid polymer water electrolysis is usually 60 ° C to 100 ° C.

  High temperature steam electrolysis is an improvement of alkaline water electrolysis and uses zirconium oxide or the like as an electrolyte. In high-temperature steam electrolysis, part of the water vapor supplied to the cathode side becomes hydrogen and oxide ions, and a mixture of hydrogen and water vapor is obtained. The oxide ions move through the electrolyte membrane and become oxygen on the anode side. Therefore, hydrogen and oxygen can be obtained separately. On the cathode side, hydrogen gas is obtained as a mixed gas of the generated gas and unreacted water vapor. Therefore, the obtained hydrogen gas contains water at a high humidity corresponding to the vapor pressure. The electrolysis temperature of high-temperature steam electrolysis is, for example, 500 ° C. or higher, 700 ° C. or higher, and 1000 ° C. or lower.

(Absorption process)
In the absorption step according to the present invention, the water electrolysis gas containing water vapor derived from the raw water obtained in the water electrolysis gas generation step is brought into contact with the absorption liquid containing ionic liquid to selectively use the water vapor. To absorb in the absorbent.
As described above, hydrogen or oxygen obtained in the water electrolysis gas generation step is accompanied by gas or liquid water. When liquid water is present, it can be removed by gas-liquid separation before the absorption step. The gas obtained by gas-liquid separation, if necessary, becomes a mixed gas of hydrogen or oxygen and water vapor, but contains a large amount of water and usually contains water vapor with a saturated water vapor amount. For example, at 25 ° C. and normal pressure, 23 g of saturated water vapor per 1 m ³ is contained.

  In the absorption step, the water electrolysis gas is brought into contact with the absorption liquid. This absorption liquid contains an ionic liquid. The ionic liquid absorbs water with little absorption of hydrogen and oxygen. Therefore, by bringing the absorption liquid into contact with the water electrolysis gas, the water vapor on the gas phase side can be moved to the absorption liquid side of the liquid phase, and the moisture content in the gas phase can be reduced.

(Ionic liquid)
The ionic liquid used in the present invention comprises a cation and an anion, and is a liquid salt at 100 ° C. and atmospheric pressure. The ionic liquid according to the present invention is preferably liquid at room temperature (25 ° C.). That is, the melting point of the ionic liquid according to the present invention is not particularly limited as long as it is 100 ° C. or less, but is preferably less than 50 ° C., more preferably less than 25 ° C., and particularly preferably less than 10 ° C. This ionic liquid includes one having a melting point of 100 ° C. or less by containing a trace amount of water. Moreover, the minimum of melting | fusing point of the ionic liquid which concerns on this invention is not specifically limited. Note that the ionic liquid is often supercooled and takes a liquid state even below the melting point, and the ionic liquid is not limited even if the melting point is high as long as such a liquid state can be maintained.

  Although the anion which comprises the ionic liquid used for this invention is not specifically limited, It is preferable in it being an oxo acid ion. In the present specification, the oxo acid is an inorganic or organic acid containing oxygen.

  Examples of the oxo acid include carboxylic acid, nitric acid, sulfuric acid, sulfonic acid, phosphoric acid ester, phosphoric acid, phosphonic acid ester, and phosphonic acid.

The carboxylate ion is an anion represented by Formula 1.
Here, R ¹ in Formula 1 is a hydrogen atom or an unsubstituted or substituted hydrocarbon group. The hydrocarbon group is not particularly limited, and examples thereof include an alkyl group, an alkenyl group, an alkynyl group, and an aromatic hydrocarbon group, which may be cyclic or acyclic, and have a hetero atom in the skeleton. It may be. Specifically, alkyl groups such as methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group; these alkenyl groups, Alkynyl group; alkoxy group such as methoxy group and ethoxy group, allyl group, aryl group and the like. As the hydrocarbon group, an aliphatic hydrocarbon group is preferable, and an alkyl group is more preferable. Examples of the substituent include halogen groups such as fluorine, chlorine bromine and iodine; hydroxyl groups; cyano groups.

  More specific examples of the carboxylic acid include formic acid, acetic acid, propionic acid, butyric acid, oleic acid, benzoic acid, lactic acid, trifluoroacetic acid, and heptafluorobutyric acid. Of these, acetic acid and trifluoroacetic acid are preferable.

The sulfonate ion is an anion represented by Formula 2.
Here, R ² in Formula 2 is a hydrogen atom or an unsubstituted or substituted hydrocarbon group. Examples of the substituent and the hydrocarbon group include those mentioned as the substituent and the hydrocarbon group of the carboxylate ion. Specific examples of the sulfonic acid include alkyl sulfonic acids such as methyl sulfonic acid and ethane sulfonic acid; perfluoroalkyl sulfonic acids such as trifluoromethane sulfonic acid and nonafluorobutane sulfonic acid; alkyl such as lauryl sulfuric acid and polyoxyethylene alkyl sulfuric acid. A sulfuric acid is mentioned. Of these, methylsulfonic acid is preferred.

Phosphate ion and phosphate ion are anions represented by Formula 3.
Here, in Formula 3, R ³ and R ⁴ are a hydrogen atom or a hydrocarbon group which may be unsubstituted or substituted. Examples of the substituent and the hydrocarbon group include those mentioned as the substituent and the hydrocarbon group of the carboxylate ion. The anion represented by Formula 3 is a phosphate ion when R ³ and R ⁴ are hydrogen atoms, and a phosphate monoester ion when one is a hydrogen atom and the other is a hydrocarbon group, The case where is a hydrocarbon group is a phosphate diester ion. Specific examples of the phosphate ester include phosphate esters such as butyl phosphate and phenyl phosphate, and phosphate diesters such as dibutyl phosphate and bis (2-ethylhexyl) phosphate.

The phosphonate ester ion and the phosphonate ion are anions represented by Formula 4.
Here, R ⁵ in Formula 4 is a hydrogen atom or a hydrocarbon group which may be unsubstituted or substituted. Examples of the substituent and the hydrocarbon group include those mentioned as the substituent and the hydrocarbon group of the carboxylate ion. The anion represented by Formula 4 is a phosphonate ion when R ⁵ is a hydrogen atom, and a phosphonate ion when R ⁵ is a hydrocarbon group. Among the hydrocarbon groups, an aliphatic hydrocarbon group is preferable, an alkyl group is more preferable, an alkyl group having 2 or less carbon atoms is particularly preferable, and a methyl group is most preferable. Specific examples of the phosphonic acid ester include methyl phosphite ((MeO) HPOO ⁻ ).

  The cation constituting the ionic liquid according to the present invention is not particularly limited, and examples thereof include imidazoliums, pyrrolidiniums, piperidiniums, pyridiniums, morpholiniums, ammoniums, phosphoniums, and sulfoniums. Of these, imidazoliums are preferable.

  The imidazolium is a cation of a compound in which a hydrogen atom of imidazole (1,3-diaza-2,4-cyclopentadiene) is substituted with a hydrocarbon group, and is represented by, for example, Formula 5.

Here, in Formula 5, R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are a hydrogen atom or an unsubstituted or substituted hydrocarbon group.

  The hydrocarbon group of the imidazoliums is not particularly limited, and examples thereof include those listed as the substituent of the carboxylate ion and the hydrocarbon group. There may be one hydrocarbon group or two or more hydrocarbon groups, but it is preferable to have a hydrocarbon group at two nitrogen atoms at the 1- and 3-positions. Moreover, when a hydrocarbon group has two or more hydrocarbon groups, they may be the same or different.

Examples of imidazoliums include asymmetric imidazoliums substituted with one saturated or unsaturated hydrocarbon group such as 1-methylimidazolium, 1-ethylimidazolium, 1-propylimidazolium, 1-butylimidazolium and the like. Symmetrically substituted with two saturated or unsaturated hydrocarbon groups such as 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1,3-dipropylimidazolium, 1,3-dibutylimidazolium; Types of imidazolium; 1-ethyl-3-methylimidazolium, 1-methyl-3-propylimidazolium, 1-butyl-3-methylimidazolium, 1-ethyl-3-propylimidazolium, 1-butyl-3 -Two saturated or unsaturated carbonizations such as ethyl imidazolium, 1-butyl-3-propyl imidazolium, etc. And asymmetric imidazolium substituted with a hydrogen group; imidazolium substituted with two or more saturated or unsaturated hydrocarbon groups, and the like. Among these, 1-ethyl-3-methylimidazolium ([emim] ⁺ ) is preferable.

  In the ionic liquid according to the present invention, the combination of the cation and the anion is not particularly limited as long as the salt becomes an ionic liquid, but more specifically, as the ionic liquid, 1-ethyl-3-methylimidazo Lithium acetate, 1-ethyl-3-methylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium benzoate, 1-ethyl-3-methylimidazolium methylsulfonate, 1-ethyl-3-methylimidazolium methyl sulfate , 1-ethyl-3-methylimidazolium hydrogen sulfate, 1-ethyl-3-methylimidazolium methyl phosphite is preferable because the dehumidifying amount is twice or more as compared with the case where triethylene glycol is used as an absorbing solution. .

  The ionic liquid which concerns on this invention can be manufactured by a well-known method, and can employ | adopt optimal conditions according to a raw material.

(Absorbing liquid)
The absorbing liquid according to the present invention contains the ionic liquid described above. The absorption liquid according to the present invention can use a single type or a plurality of types of ionic liquids, and can contain components other than the ionic liquid within a range not impairing the effects of the present invention.

  The contact method between the water electrolysis gas and the absorption liquid is not particularly limited as long as the water vapor in the water electrolysis gas is absorbed by the absorption liquid. For example, a method of spraying the absorbing liquid onto the water electrolysis gas, a method of allowing the absorbing liquid to flow down on the wall of the tower from above, and a flow of the water electrolysis gas, allowing the absorbing liquid to flow down from above the packed tower filled with packing, Examples thereof include a method of circulating an electrolytic gas and a method of bubbling a water electrolytic gas in an absorbing solution.

(Separation process)
The separation step according to the present invention gas-liquid separates the dry water electrolysis gas whose humidity has been reduced in the absorption step and the rich absorbent that has absorbed water vapor. In this specification, the rich absorbent that has absorbed water vapor may be referred to as a “rich absorbent” to distinguish it from the absorbent before absorption. Since the ionic liquid contained in the absorption liquid absorbs water vapor and has a low vapor pressure, dry water electrolysis gas can be obtained simply by gas-liquid separation and removing the rich absorption liquid.

  The separation step according to the present invention is not particularly limited as long as it is a method capable of gas-liquid separation of the dry water electrolysis gas whose humidity has been reduced in the absorption step and the rich absorption liquid that has absorbed water vapor, but may be performed simultaneously with the absorption step. preferable. For example, in the absorption process, when a method of spraying an absorption liquid onto the water electrolysis gas is used, the water electrolysis gas is circulated from one side of the tube to the other, and the water electrolysis gas is sprayed onto the water electrolysis gas to absorb water vapor. And a method of extracting the rich absorbent from the lower side. Water vapor in the water electrolysis gas is absorbed and extracted by the absorbing liquid, and the dry water electrolysis gas is discharged from the other side of the tube.

  In addition, as the absorption step, a method of flowing the absorption liquid from the top to the wall surface of the tower and circulating the water electrolysis gas, or a method of flowing the absorption liquid from the top of the packed tower filled with the packing and circulating the water electrolysis gas When water is used, water electrolysis gas can be blown from below, dry water electrolysis gas can be extracted from above, and rich absorption liquid that has absorbed water vapor can be extracted from below.

  The water electrolysis gas generation step has high energy efficiency when the temperature is high. On the other hand, the ionic liquid used for the absorption liquid in the absorption process has a larger amount of water absorption as the temperature is lower. Therefore, it is preferable to cool the high-humidity electrolytic gas before the absorption step. Therefore, it is preferable in terms of energy efficiency to perform a heat exchange step in which heat exchange is performed between the water electrolysis gas and the rich absorbent before the absorption step.

(Regeneration process)
The method for producing a dry water electrolysis gas of the present invention can include a regeneration step of regenerating the rich absorbent obtained in the above-described separation step.

  The method for regenerating the rich absorbent into the absorbent is not particularly limited. The amount of water absorbed in the ionic liquid used in the absorbent of the present invention tends to decrease as the temperature increases. Therefore, by making the rich absorbent liquid at a temperature higher than the temperature at which the water electrolysis gas and the absorbent liquid are brought into contact with each other, it is possible to release water vapor and regenerate the absorbent liquid. In addition, by utilizing the difference between the low vapor pressure of ionic liquid and the vapor pressure of water and the fact that the water absorbability of ionic liquid decreases as the water vapor partial pressure decreases, the rich absorbent liquid is physically reduced by reducing the pressure. Examples include a method of releasing water vapor and a method of simultaneously performing heating and decompression. A combination of heating and reduced pressure is preferred. The released water vapor can be reused as a raw material for water electrolysis.

  When heating the rich absorbent in the regeneration step, it is preferable in terms of energy efficiency that the rich absorbent is heated by heat exchange with the water electrolysis gas before the absorbent step.

  On the other hand, when the absorbent regenerated in the regeneration step is used in the absorption step, it is preferable to lower the temperature in order to increase the amount of water absorbed. For cooling the regenerated absorbent, the rich absorbent before the regeneration process can be used. That is, it is preferable in terms of energy efficiency to perform the second heat exchange step in which heat is exchanged between the absorbent regenerated in the regeneration step and the rich absorbent.

  The absorption process using the absorption liquid containing the ionic liquid described above can continuously reduce the water electrolysis gas having a very high water vapor amount to a moderate humidity at a low cost. Therefore, the amount of solid desiccant used is reduced even when the water content of the dried water electrolysis gas obtained in the subsequent separation step is further reduced with a solid desiccant such as calcium chloride or zeolite. Can extend the period of use.

(Dry water electrolysis gas production equipment)
The apparatus for producing a dry water electrolysis gas of the present invention includes a water electrolysis gas generating means for electrolyzing water to obtain a water electrolysis gas, and a water electrolysis containing water vapor derived from the raw water obtained by the water electrolysis gas generation means. An absorbing means for bringing the gas into contact with an absorbing liquid containing an ionic liquid to selectively absorb water vapor into the absorbing liquid, a dry water electrolytic gas whose humidity has been reduced by the absorbing means, and an abundance that has absorbed water vapor. Separating means for gas-liquid separation of the absorption liquid. Hereinafter, a description will be given with reference to FIG.

FIG. 1 shows an embodiment of an apparatus used in the method for producing dry water electrolysis gas of the present invention.
The electrolytic cell 1 (water electrolysis gas generating means) includes an anode 2 and a cathode 3. The electrolytic cell 1 contains an electrolytic solution 4 such as an aqueous sodium hydroxide solution. Although not shown in the figure, the electrolytic layer is provided with a film so as to be divided into an anode side and a cathode side. The electrolytic cell 1 may be provided with a temperature control device 5 such as a heater or a chiller as necessary. Raw water 6 is supplied to the electrolytic cell 1. In the electrolytic cell 1, the water 6 is electrolyzed. A mixed gas of hydrogen and water vapor is obtained from the cathode side, and a mixed gas of oxygen and water vapor is obtained from the anode 2 side. In FIG. 1, one of these mixed gases is shown as the water electrolysis gas 7. If necessary, the temperature of the water electrolysis gas 7 is lowered by the heat exchanger 8.

  The water electrolysis gas 7 is brought into contact with the absorbing liquid 10 in the absorption tower 9 (absorption means / separation means). The absorption liquid selectively absorbs water vapor and becomes the rich absorption liquid 11. The water electrolysis gas 7 becomes the dry water electrolysis gas 12.

  If necessary, the temperature of the rich absorbent 11 is raised by the heat exchanger 8 and the heat exchanger 13. The rich absorbent 11 is regenerated by removing moisture with the regenerator 14 and becomes the absorbent 10. The regenerator 14 (regeneration means) includes a heater 15 and a decompression pump 16, and heats and depressurizes the rich absorbent 11 to remove moisture. The regenerated absorbent 10 is cooled by the liquid feed pump 17 by the heat exchanger 13 and the precooler 18 as necessary, and then returned to the absorption tower 9.

(Example)
EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to these Examples. The pressure is an absolute pressure unless otherwise specified.

(Measurement of water vapor absorption)
The amount of water vapor absorbed was measured using calcium chloride and various ionic liquids as the absorbing solution. The measurement is performed by placing an absorption liquid of a predetermined mass in a high-temperature humidity chamber (but calcium chloride is an anhydrous solid), contacting air of a predetermined humidity at a predetermined temperature, and measuring the absorption amount at a predetermined time interval. Mass change was measured. The time when the mass change of the absorbing liquid disappeared was regarded as a saturated state, and the water vapor absorption amount w _H2O (g / g-ionic liquid) and the water vapor mole fraction x _H2O were determined.

  Temperature and relative humidity conditions are about 25 ° C. (relative humidity about 50%, about 70%, about 90%) and about 80 ° C. (relative humidity about 30%, about 50%, about 70%, 90%). It was. The results are shown in Tables 1 and 2. Moreover, the dependence with respect to relative humidity of the water vapor absorption amount of calcium chloride and each absorption liquid is shown in FIG. 2 (25 degreeC) and FIG. 3 (80 degreeC).

Abbreviations of anions and cations constituting the ionic liquids in Tables 1 and 2 are as follows. [Emim] ⁺ is an abbreviation for 1-ethyl-3-methylimidazolium. [AcO] ⁻ is an acetate anion (acetate; CH ₃ C (═O) O ⁻ ), [TFA] ⁻ is a trifluoroacetate anion (trifluoroacetate; CF ₃ C (═O) O ⁻ ), [BZA ] ^- benzoic acid anion ^{(benzoate; PhC (= O) O -} ) of, [MeSO _3] ^- methyl sulfonate _{(MeS (= O) 2 O} -) of, [MeSO _4] ^- methylsulfinyl Fate (Meos [= O) ₂ O ⁻ , [HSO ₄ ] ⁻ is a hydrogen sulfate anion ((HO) S (═O) ₂ O ⁻ ), [MeHPO ₃ ] ⁻ is methyl phosphite ((MeO) HP (═O ) O ^-) of, [TCB] ^- is tetracyanoborate (B _{(CN) 4} ^- is an abbreviation of).

Based on the measurement results of the water vapor absorption amount of the various absorption liquids described above, the amount of the absorption liquid necessary for drying the water electrolysis gas 1 m ³ / h was calculated. The calculation condition is that the water electrolysis gas containing water vapor derived from the raw water obtained in the water electrolysis gas generation step is atmospheric pressure, 25 ° C., 90 RH% (water vapor pressure 2.84 kPa), and the temperature of the regeneration step is 80. The water vapor pressure of the absorbent regenerated at 0 ° C. is 0 RH% (water vapor pressure 0 kPa), 30 RH% (water vapor pressure 142.3 kPa), 50 RH% (water vapor pressure 237.08 kPa), 70 RH% (water vapor pressure 33.3%). 564 kPa) or 90 RH% (water vapor pressure 424.54 kPa). Moreover, the water electrolysis gas (H ₂ or O ₂ ) of water electrolysis gas (absorption tower inlet / atmospheric pressure) and water partial pressure are set to 98.40 kPa (80.04 kg / m ³ ) · H ₂ O. 2.84 kPa (20.60 kg / m ³ ), and the absorption efficiency and the regeneration efficiency are 100% (that is, all the water vapor in the water electrolysis gas is transferred to the ionic liquid in the absorption process, and the recovery process is performed in the ionic liquid); All excess water will evaporate).

  For comparison, calculations were also made for calcium chloride and triethylene glycol (TEG). The amount of water vapor absorbed by TEG was estimated from the data described in “Triethylene Glycol” issued by Dow Chemical Company, 2007. Here, it is conceivable to extrapolate the water vapor absorption amount of the absorbing liquid at 25 ° C. and 100 RH%, but since the error may be too large, it is set to 90 RH%. Moreover, although the absorption result of the water vapor pressure in the air is used in the trial calculation, the water vapor absorption amount of the ionic liquid is considered to be almost the same in the case of air and hydrogen or oxygen.

  Table 3 shows the calculation results of the amount of necessary ionic liquid when the relative humidity in the regeneration process is 90 RH%. Table 4 shows the case where the relative humidity is 70 RH%, Table 5 shows the case where the relative humidity is 50 RH%, Table 6 shows the case where the relative humidity is 30 RH%, and Table 7 shows the case where the relative humidity is 0 RH%. In Tables 3 and 4, when the recovered amount is a negative value, it means that the absorbed amount of water vapor is larger at 80 ° C. and 90 RH% than at 25 ° C. and 90 RH%. Each table shows the difference from triethylene glycol. The larger this value, the smaller the amount of absorption liquid required.

  Hereinafter, the amount of energy required for dehumidification is calculated.

(Comparative Example 1: Dehumidification by cooling)
The amount of energy required to dehumidify the water electrolysis gas 1 m ³ / h by cooling to atmospheric pressure / dew point −20 ° C. according to the conventional method is calculated. Water electrolysis gas shall be atmospheric pressure, 25 degreeC, and 90RH%. This water electrolysis gas condition corresponds to the case where the water electrolysis gas generation step is performed by alkaline water electrolysis.

(1) Calculate the mass of water to be removed.
When the water electrolysis gas at atmospheric pressure / 25 ° C./90 RH% is dehumidified by cooling to atmospheric pressure / −20 ° C., the water content of the water electrolysis gas at 25 ° C./90 RH% (pH _{2 O} = 28.5 kPa) is 1 m. ^Since the water content of the dry water electrolysis gas at −20 ° C. and 100 RH% (pH _{2 O} = 0.125 kPa) is 1.07 g per 1 m ³ , the mass of water to be removed is 19.60 g per ³ . 53 g.

(2) Next, the energy required for gas cooling is calculated.
The density of the water electrolysis gas at −20 ° C. · pH _{2 O} = 0.125 kPa is 20.79 L / mol, and the enthalpy is 6.684 kJ / mol.
The density of the water electrolysis gas of 25 ° C. · p _H2O = 0.125 kPa is 24.49 L / mol, and the enthalpy is 7.973 kJ / mol.
Therefore, since the water electrolysis gas is treated at 1 m ³ / h, the energy required for gas cooling is
7.973 kJmol ⁻¹ × (1000 Lh ⁻¹ /24.49 Lmol ⁻¹ )
−6.684 kJmol ⁻¹ × (1000 Lh ⁻¹ /20.79 Lmol ⁻¹ )
= 4.061 kJ / h.

(3) Next, the energy required to liquefy or solidify and separate the water vapor is calculated in three cases. In the calculation, the following values were used for the physical constants of water.
Specific heat of water (kJ / kg · K): 4.186
Specific heat of ice (kJ / kg · K): 2.1
Condensation heat of water vapor (kJ / mol): 40.8
Heat of solidification of water (kJ / mol): 6.003335
Specific heat of water vapor (kJ / kg · K): 2

(A) Case 1
When all water vapor is condensed at 25 ° C in 1 hour, water is cooled to 0 ° C, solidified at 0 ° C, and ice is cooled to -20 ° C;
The energy required for water separation is
{40.8 kJ · mol ⁻¹ × (19.53 g / 18.01 g · mol ⁻¹ ) +4.186 kJ · kg ⁻¹ · K ⁻¹ × (0.01953 kg) × (298 K-273 K) +6.03 kJ mol ⁻¹ × (19.53 g / 18.01 g · mol ⁻¹ ) +2.1 kJ · kg ⁻¹ · K ⁻¹ × (0.01953 kg) × (273K-253K)} / 1h
= 53.65 kJ / h.

(B) Case 2
In one hour, when steam is cooled from 25 ° C to 0 ° C, condensed and solidified at 0 ° C, and ice is cooled to -20 ° C;
The energy required for water separation is
{2.0 kJ · kg ⁻¹ · K ⁻¹ × (0.01953 kg) × (298K-273K) +40.8 kJ · mol ⁻¹ × (19.53 g / 18.01 g · mol ⁻¹ ) +6.03 kJ · mol ⁻¹ × (19.53 g / 18.01 g · mol ⁻¹ ) +2.1 kJ · kg ⁻¹ · K ⁻¹ × (0.01953 kg) × (273K-253K)} / 1h
= 52.58 kJ / h.

(C) Case 3
In one hour, when water vapor is cooled from 25 ° C. to −20 ° C. and all condensed at −20 ° C. to solidify;
The energy required for water separation is
{2.0 kJ · kg ⁻¹ · K ⁻¹ × (0.01953 kg) × (298K-253K) +40.8 kJ · mol ⁻¹ × (19.53 g / 18.01 g · mol ⁻¹ ) +6.03 kJ · mol ⁻¹ × (19.53 g / 18.01 g · mol ⁻¹ )} / 1 h
= 52.54 kJ / h.

(4) Therefore, even in the trial calculation of Case 3 with the lowest energy, the amount of energy required for dehumidification is
4.01 kJ / h + 52.54 kJ / h
= 56.60 kJ / h.

(Example 1: Dehumidification with absorption liquid (ionic liquid; [emim] [AcO]))
The amount of energy when dehumidification equivalent to that of Comparative Example 1 is performed using the ionic liquid as the absorbing liquid is calculated. That is, a water electrolysis gas at atmospheric pressure / 25 ° C./90 RH% (pH _{2 O} = 28.5 kPa) is used as an absorbing liquid (ionic liquid) at atmospheric pressure / 25 ° C./0.4 RH% (pH _{2 O} = 0.125 kPa · Dehumidify to -20 ° C saturated vapor pressure). Therefore, in the recovery step, the amount of water in the rich absorbent must be reduced to almost zero. Therefore, it is calculated that all the water in the rich absorbent is recovered in the regeneration step (80 ° C.). As the absorbing liquid, ionic liquid [emim] [AcO] is used.

(1) The mass of water to be removed is 19.53 g per m ^{3 of} water electrolysis gas, as in the comparative calculation example. The ionic liquid [emim] [AcO] necessary to absorb this 19.53 g of water is shown in Table 1.
(19.53 g / h) /2.471 g
= 7.903 g / h.

(2) The ionic liquid aqueous solution is heated to 80 ° C., and the amount of heat necessary for evaporating the water is obtained. The following physical properties were used.
Specific heat of [emim] [AcO] (kJ / kg · K): 1.95
Heat of evaporation of water (kJ / mol): 40.8
Specific heat of water (kJ / kg · K): 4.186

(2-1) The amount of heat required to raise the temperature of the aqueous solution of the ionic liquid [emim] [AcO] from 25 ° C. to 80 ° C. in 1 hour is as follows:
{1.95 kJ · kg ⁻¹ · K ⁻¹ × (0.007903 kg) × (353K-298K) +4.186 kJ · kg ⁻¹ · K ⁻¹ × (0.01953 kg) × (353K-298K)} / 1h
= 5.34 kJ / h.

(2-2) The amount of heat required for water evaporation (assuming that it is the same as the heat of evaporation of pure water) is:
{40.8 kJmol ⁻¹ × (19.53 g / 18.01 gmol ⁻¹ )} / 1h
= 44.24 kJ / h. Therefore, the amount of heat necessary to heat the ionic liquid aqueous solution to 80 ° C. and evaporate the water is
5.34 kJ / h + 44.24 kJ / h
= 49.58 kJ / h.
If the ionic liquid is used 5 times,
8.73 kJ / h + 44.24 kJ / h
= 52.97 kJ / h is required.

(3) Calculate the power required to send the ionic liquid [emim] [AcO].
It is assumed that the shaft power of the pump is given by the following equation.
P = ρgQH / η
(Where ρ is density (kgm ⁻³ ), g is gravitational acceleration (9.80665 ms ⁻² ), Q is the total head (m), H is the discharge amount (m ³ s ⁻¹ ), and η is the pump efficiency (0.8).)
The following physical properties were used.
Mass flow rate (kg / h): 0.00790274
[Emim] Density of [AcO] (kg / m ³ ) @ 80 ° C .: 1066.01
Volume flow rate (m ³ / h): 7.41338E-06
Total head (m): 10

The power required to send the ionic liquid [emim] [AcO] is
1066.01 kgm ⁻³ × 9.80665 ms ⁻² × 10 m × (7.41338E-6m ³ h ⁻¹ ) /0.8
= 0.9687 kgm ² s ^-2 h ^-1
= 0.0009687 kJ / h.
If the ionic liquid is used 5 times, 0.004844 kJ / h is required.

(4) The total amount of regeneration heat and liquid feeding power is 49.58 kJ / h. This value is 7.08 kJ / h less than the cooling and dehumidification of Comparative Example 1. Even if the ionic liquid is used 5 times, it is 52.98 kJ / h, and the required energy is 3.62 kJ / h less than in the case of cooling dehumidification. Note that the dehumidification with the above ionic liquid does not take into account the efficiency improvement due to heat exchange, and therefore further energy saving can be achieved.

(Comparative Example 2: Dehumidification by cooling)
The water electrolysis gas is 1 MPa · 25 ° C. · 90 RH%, and the amount of energy required for dehumidifying this water electrolysis gas 1 m ³ / h to atmospheric pressure / dew point −20 ° C. is calculated. This condition corresponds to the case where the water electrolysis gas generation step is performed by solid polymer water electrolysis.

(1) Calculate the mass of water to be removed.
When the water electrolysis gas of 1 MPa · 25 ° C./90 RH% is cooled to 1 MPa · −20 ° C. and dehumidified, the water content of the water electrolysis gas of 25 ° C. · 90 RH% (pH _{2 O} = 28.5 kPa) is 20 per m ^3. Since the water content of the dry water electrolysis gas at −20 ° C. and 100 RH% (pH _{2 O} = 0.125 kPa) is 1.06 g per m ³ , the mass of water to be removed is 1 m ³ of water electrolysis gas. It is 19.54g per unit.

(2) Next, the energy required for gas cooling is calculated.
The density of the hydrous hydrogen gas at −20 ° C. and pH _{2 O} = 0.125 kPa is 2.118 L / mol, and the enthalpy is 6.647 kJ / mol.
The density of the hydrous hydrogen gas at 25 ° C. and pH _{2 O} = 0.125 kPa is 2.494 L / mol, and the enthalpy is 7.939 kJ / mol.
Therefore, since the water electrolysis gas is treated at 1 m ³ / h, the energy required for gas cooling is
7.939 kJmol ⁻¹ × (1000 Lh ⁻¹ /2.494 Lmol ⁻¹ ) −6.647 kJmol ⁻¹ × (1000 Lh ⁻¹ /2.118 Lmol ⁻¹ )
= 44.90 kJ / h.

(3) Next, the energy required to liquefy or solidify and separate the water vapor is calculated in three cases. In the calculation, the same water constant as in Comparative Example 1 was used as the physical constant of water.

a) Case 1
When all water vapor is condensed at 25 ° C in 1 hour, water is cooled to 0 ° C, solidified at 0 ° C, and ice is cooled to -20 ° C;
The energy required for water separation is
{40.8 kJmol ⁻¹ × (19.54 g / 18.01 gmol ⁻¹ ) +4.186 kJkg ⁻¹ K ⁻¹ × (0.01954 kg) × (298K-273K) +6.03 kJmol ⁻¹ × (19.54 g / 18 .01 gmol ⁻¹ ) +2.1 kJkg ⁻¹ K ⁻¹ × (0.01954 kg) × (273K-253K)} / 1h
= 53.67 kJ / h.

b) Case 2
In one hour, when steam is cooled from 25 ° C to 0 ° C, condensed and solidified at 0 ° C, and ice is cooled to -20 ° C;
The energy required for water separation is
{2.0 kJkg ⁻¹ K ⁻¹ × (0.01954 kg) × (298K-273K) +40.8 kJmol ⁻¹ × (19.54 g / 18.01 gmol ⁻¹ ) +6.03 kJmol ⁻¹ × (19.54 g / 18 .01 gmol ⁻¹ ) +2.1 kJkg ⁻¹ K ⁻¹ × (0.01954) × (273K-253K)} / 1h
= 52.61 kJ / h.

c) Case 3
When the water vapor is cooled from 25 ° C. to −20 ° C., and all is condensed and solidified at −20 ° C .;
The energy required for water separation is
{2.0 kJkg ⁻¹ K ⁻¹ × (0.01954 kg) × (298K-253K) +40.8 kJmol ⁻¹ × (19.54 g / 18.01 gmol ⁻¹ ) +6.03 kJmol ⁻¹ × (19.53 g / 18 .01 gmol ⁻¹ )} / 1h
= 52.57 kJ / h.

(4) Therefore, the amount of energy required for dehumidification in the calculation of Case 3 with the lowest energy is
44.90 kJ / h + 52.57 kJ / h
= 97.47 kJ / h.

(Example 2: Dehumidification with absorption liquid (ionic liquid; [emim] [AcO]))
The amount of energy required when dehumidification equivalent to that of Comparative Example 2 is performed using the ionic liquid as the absorbing liquid is calculated. That is, 1 MPa · 25 ° C. · 90 RH% (pH _{2 O} = 28.5 kPa) of water electrolysis gas is 1 MPa · 25 ° C. · 0.4 RH% (pH _{2 O} = 0.125 kPa · −20) as an absorbing liquid (ionic liquid). Dehumidify to saturated vapor pressure at ℃. Therefore, in the recovery step, the amount of water in the rich absorbent must be reduced to almost zero. Therefore, it is calculated that all the water in the rich absorbent is recovered in the regeneration step (80 ° C.). As the absorbing liquid, ionic liquid [emim] [AcO] is used.

(1) The mass of water to be removed is 19.54 g per 1 m ³ of water electrolysis gas as in Comparative Example 2. The ionic liquid [emim] [AcO] necessary to absorb this 19.54 g of water is 7.907 g / h.

(2) The ionic liquid aqueous solution is heated to 80 ° C., and the amount of heat necessary for evaporating the water is obtained. The same physical property values as in Comparative Example 1 were used.

(2-1) The amount of heat required to raise the temperature of the aqueous solution of the ionic liquid [emim] [AcO] from 25 ° C. to 80 ° C. in 1 hour is as follows:
{1.95 kJkg ⁻¹ K ⁻¹ × (0.007907 kg) × (353K-298K) +4.186 kJkg ⁻¹ K ⁻¹ × (0.01954 kg) × (353K-298K)} / 1h
= 5.35 kJ / h.

(2-2) The amount of heat required for water evaporation is:
{40.8 kJmol ⁻¹ × (19.54 g / 18.01 gmol ⁻¹ )} / 1h
= 44.26 kJ / h. Therefore, the amount of heat necessary to heat the ionic liquid aqueous solution to 80 ° C. and evaporate the water is
5.35 kJ / h + 44.26 kJ / h
= 49.61 kJ / h is required.
If the ionic liquid is used 5 times,
8.74 kJ / h + 44.24 kJ / h
= 52.98 kJ / h is required.

(3) Calculate the power required to send the ionic liquid [emim] [AcO].
It is assumed that the shaft power of the pump is given by the following equation.
P = ρgQH / η
(Where ρ is density (kgm ⁻³ ), g is gravitational acceleration (9.80665 ms ⁻² ), Q is the total head (m), H is the discharge amount (m ³ s ⁻¹ ), and η is the pump efficiency (0.8).)
The following physical properties were used.
Mass flow rate (kg / h): 0.00790274
[Emim] Density of [AcO] (kg / m ³ ) @ 80 ° C .: 1066.01
Volume flow rate (m ^{3 /} h): 7.41338E-06
Total head (m): 100

The power required to send the ionic liquid [emim] [AcO] is
1066.01 kgm ⁻³ × 9.80665 ms ⁻² × 100 m × (7.41338E-6m ³ h ⁻¹ ) /0.8
= 9.687 kgm ² s ^-2 h ^-1
= 0.009687 kJ / h.
If the ionic liquid is used 5 times, 0.04844 kJ / h is required.

(4) The total amount of regeneration heat and liquid feeding power is 49.62 kJ / h. This value is 47.85 kJ / h less than the cooling and dehumidification of Comparative Example 1. Even if the ionic liquid is used 5 times, it is 53.03 kJ / h, and the required energy is 44.44 kJ / h less than in the case of cooling dehumidification. Thus, the effect of the present invention is particularly excellent when the water electrolysis gas generation step is performed by solid polymer water electrolysis. Note that the dehumidification with the above ionic liquid does not take into account the efficiency improvement due to heat exchange, and therefore further energy saving can be achieved.

  According to the method for producing dry water electrolysis gas of the present invention, (1) energy saving can be achieved as compared with the cooling method by chiller, and (2) only the water vapor component can be removed from the hydrogen or oxygen gas source at room temperature. There is no decrease in hydrogen or oxygen partial pressure, (3) the absorption liquid can be regenerated with a low-grade heat source of 100 ° C or lower, and (4) a continuous dehumidification / regeneration process is achieved through circulation of the absorption liquid. Easy to replace, can save sensible heat, and can use various exhaust heat sources. (5) Dehumidification and regeneration are more efficient and energy-saving than conventional absorbents. (6) Problems with conventional absorbents. There is also an effect that the water electrolysis gas is not accompanied by the absorption liquid and does not hinder high purity.

DESCRIPTION OF SYMBOLS 1 ... Electrolytic cell 2 ... Anode 3 ... Cathode 4 ... Electrolyte solution 5 ... Temperature control device 6 ... Water 7 ... Water electrolysis gas 8 ... Heat exchanger 9- .. Absorption tower 10... Absorbing liquid 11. ... Liquid feed pump 18 ... Precooler

Claims (9)

A water electrolysis gas generation step of electrolyzing water to obtain a water electrolysis gas;
The absorption step of selectively absorbing water vapor in the absorption liquid by bringing the water electrolysis gas containing water vapor derived from the raw material water obtained in the water electrolysis gas generation step into contact with the absorption liquid containing the ionic liquid. When,
A separation step of gas-liquid separation of the dry water electrolysis gas having reduced humidity in the absorption step, and the rich absorption liquid that has absorbed water vapor;
The manufacturing method of the dry water electrolysis gas containing this.   The manufacturing method of the dry water electrolysis gas of Claim 1 which further includes the heat exchange process which heat-exchanges with the said water electrolysis gas before the said absorption process, and the said rich absorption liquid.   The method for producing a dry water electrolysis gas according to claim 1 or 2, further comprising a regeneration step of heating and / or depressurizing the rich absorbent to remove moisture to regenerate the absorbent.   The method for producing a dry water electrolysis gas according to claim 3, further comprising a second heat exchange step in which heat exchange is performed between the absorbent regenerated in the regeneration step and the rich absorbent.   The method for producing a dry water electrolysis gas according to any one of claims 1 to 4, wherein the anion constituting the ionic liquid is an oxoacid ion. The oxo acid ion is a carboxylate ion represented by formula 1, nitrate ion, sulfate ion, hydrogen sulfate ion, sulfonate ion represented by formula 2, phosphate ester ion or phosphate ion represented by formula 3. Or the manufacturing method of the dry water electrolysis gas of Claim 5 which is the phosphonate ester ion or phosphonate ion represented by Formula 4.
(In Formula 1, R ¹ is a hydrogen atom or a hydrocarbon group which may be unsubstituted or substituted.)
(In Formula 2, R ² is a hydrogen atom or a hydrocarbon group which may be unsubstituted or substituted.)
(In Formula 3, R ³ and R ⁴ are a hydrogen atom or an unsubstituted or substituted hydrocarbon group.)
(In Formula 4, R ⁵ is a hydrogen atom or an unsubstituted or substituted hydrocarbon group.)   The method for producing a dry water electrolysis gas according to claim 1, wherein the water electrolysis gas is hydrogen gas. Water electrolysis gas generating means for electrolyzing water to obtain water electrolysis gas;
Absorbing means for selectively absorbing water vapor in the absorbing liquid by bringing the water electrolyzed gas containing water vapor derived from raw water obtained by the water electrolyzing gas generating means into contact with an absorbing liquid containing an ionic liquid. When,
Dry water electrolysis gas whose humidity has been reduced by the absorption means, and separation means for gas-liquid separation of the rich absorption liquid that has absorbed water vapor;
An apparatus for producing dry water electrolysis gas.   The apparatus for producing dry water electrolysis gas according to claim 8, further comprising regeneration means for heating and / or depressurizing the rich absorbent that has absorbed the water vapor to remove moisture and regenerate the absorbent.