JP2006143507A - Method for selectively recovering hydrogen from hydrogen-containing mixed gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for selectively separating and recovering hydrogen gas using a chemical reaction by a simple and cheap method from a hydrogen-containing mixed gas. <P>SOLUTION: The method uses a hydrogenation reactor and a dehydrogenation reactor that are connected in series, wherein in the hydrogenation reactor a mixed gas that contains a hydrogen gas containing a heteroatom compound (such as H<SB>2</SB>S, CO, H<SB>2</SB>O, NH<SB>3</SB>, HCN or the like) and naphthalene are reacted in the presence of a catalyst and stored to produce tetralin by selectively reacting hydrogen in the mixed gas with naphthalene, and then in the dehydrogenation reactor in which the tetralin is supplied therefrom a dehydrogenation reaction is conducted to obtain a hydrogen gas. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for selectively separating and recovering hydrogen gas from a mixed gas containing hydrogen gas.

Hydrogen gas has been used for various applications such as raw materials for the chemical industry, but in recent years, the demand for fuel gas for fuel cells for residential use or automobiles has increased.
That is, since _{the CO 2,} NO X generated by the combustion of fossil fuels in motor vehicles and power plants, SO _X, dust or the like, global warming has become a serious problem with respect to environmental _pollution, CO 2, NO Fuel cells, which are clean energy sources that emit almost no _{X 2} , SO _X , and dust, are attracting great expectations as automobile driving sources and residential energy sources, and it is certain that the demand for hydrogen will increase in the future. It is. Therefore, a method for stably supplying hydrogen gas at low cost is desired.

  As industrially obtained gas containing hydrogen gas, there are, for example, coke oven gas (COG), blast furnace gas (BFG), converter gas (LDG), etc. generated in steelworks facilities, and other gases include Naphtha cracked gas, coal gasification gas, woody biomass gasification gas, waste plastic gasification gas, city gas (natural gas) reformed gas, waste (including RDF) gasification gas, etc. generated in petrochemical industry facilities Can be mentioned.

For example, regarding COG, COG includes 50-60% hydrogen (H ₂ ), 20-30% methane (CH ₄ ), 5-10% carbon monoxide (CO), 2-3% Ethylene (C ₂ H ₄ ) is contained and is an extremely excellent raw material as a hydrogen source. Conventionally, these active ingredients are separated and used.

As a method for separating hydrogen from a gas containing hydrogen, a PSA (Pressure Swing Adsorption) method and a cryogenic separation method have been generally used.
In the PSA method, for example, when separating hydrogen from COG, COG is compressed to 10 kg / cm ² and purified to remove impurities such as H ₂ S and CO _2, and then activated carbon, molecular sieve or This is a method in which only hydrogen is separated and recovered by adsorbing and removing hydrocarbons such as CH ₄ and C ₂ H ₄ and CO by introducing them into a tower packed with various adsorbents such as silica gel.

In the cryogenic separation method, as described in Non-Patent Document 1, for example, purified COG is compressed (for example, 10 kg / cm ² ), and the gas is cooled by sufficiently utilizing heat exchange to provide a gas other than hydrogen. Are sequentially separated at the liquefaction point and hydrogen is finally taken out.

On the other hand, Patent Document 1 describes that hydrogen in a hydrogen-containing mixed gas is reacted with benzene and converted into cyclohexane and stored, and in use, cyclohexane is again converted into hydrogen and benzene to extract hydrogen.
However, in the method described in Patent Document 1, in order to adjust the imbalance between the generation amount of the hydrogen-containing gas and the gas demand amount in the process of using the generation gas, the hydrogen gas in the generation gas is in the form of cyclohexane. This is to separate and store, and to extract hydrogen from the stored cyclohexane as necessary, and not to produce hydrogen continuously.

  Further, as in the case of the above-mentioned Patent Document 1, as an aromatic compound, Non-Patent Document 2 discloses a hydrogenation product containing decalin as a main component by reacting naphthalene with hydrogen gas at a hydrogenation site. It is described that hydrogen is generated from the hydrogenated product by a dehydrogenation reaction. This is because the hydrogenated product is used as a hydrogen storage medium, and this is used as a tanker truck for household fuel oil wholesale stores. It is transported to a retail store or a gasoline retailer / stand, and naphthalene and hydrogen are generated from decalin by a decalin dehydrogenation reactor at the transport destination, and this hydrogen is supplied to automobiles, etc., from hydrogen containing gas It is not intended to produce hydrogen gas continuously.

  Patent Document 2 discloses a hydrogen storage / supply system that uses an aromatic compound as a hydrogen gas storage / transport medium, and hydrogenation and dehydrogenation of a hydrogen storage body can be performed in a single container. However, this is not intended to continuously produce hydrogen gas from hydrogen-containing gas.

  In Patent Document 3, a raw material naphthalene containing naphthalene having a sulfur content of 50 ppm or less is hydrogenated using a feed gas containing hydrogen to produce a product containing decalin, and the product is dehydrogenated to obtain high purity. A method for producing hydrogen is described which is characterized by obtaining hydrogen. In this method, if the supply gas containing hydrogen contains a sulfur content, the sulfur content becomes a catalyst poison of the hydrogenation catalyst, so that the sulfur content in the supply gas containing hydrogen is reduced to 50 ppm or less. Is required.

JP-A-61-201601 JP 2002-134141 A JP 2003-277003 A Fuji Steel Technical Report: Vol. 11, no. 4, pp. 21-29 ECOIndustryVol.7 No.8 (2002) P.29-35

The present invention relates to a method of hydrogenating an aromatic compound to form a hydrogenated aromatic compound, and dehydrogenating the hydrogenated aromatic compound to selectively recover hydrogen, in a mixed gas containing hydrogen gas as a raw material. It is an object of the present invention to provide a method capable of separating and recovering hydrogen by sufficiently proceeding a hydrogenation-dehydrogenation reaction even when a heteroatom compound is present. In addition, the hetero atom as used in this invention means S, O, and N.

  The present inventors have obtained the knowledge that a naphthalene-tetralin-based hydrogenation-dehydrogenation reaction proceeds sufficiently even when a heteroatom compound is contained in a supply gas containing hydrogen, and completed the present invention. . That is, the present invention capable of solving the above problems is as follows.

(1) Using a hydrogenation reaction apparatus and a dehydrogenation reaction apparatus connected in series, reacting a mixed gas containing a hydrogen gas containing a heteroatom compound with an aromatic compound in the presence of a catalyst in the hydrogenation reaction apparatus Hydrogen in the mixed gas is selectively stored in an aromatic compound to produce a hydrogenated aromatic compound, and then the hydrogenated aromatic compound is supplied to the dehydrogenation reactor, A method for selectively recovering hydrogen from a mixed gas containing hydrogen gas, characterized in that hydrogen gas is obtained by performing a reaction, wherein the aromatic compound is naphthalene, and the hydrogenated aromatic compound is tetralin A method for selectively recovering hydrogen from a mixed gas containing hydrogen gas.
(2) The type of the heteroatom compound and the concentration in the mixed gas containing hydrogen gas satisfy at least one condition selected from the following (1) to (5): A method for selectively recovering hydrogen from a mixed gas containing hydrogen gas.
(1) H ₂ S having a concentration of 100 ppm or more
(2) CO with a concentration of 0.1% or more
(3) H ₂ O having a concentration of 1000 ppm or more
(4) NH ₃ having a concentration of 100 ppm or more
(5) HCN with a concentration of 100 ppm or more
(3) The method for selectively recovering hydrogen from a mixed gas containing hydrogen gas as described in (1) or (2) above, wherein the catalyst is a Co—Mo or Ni—Mo system (4) The mixed gas containing hydrogen gas is a mixed gas containing hydrogen gas and methane gas, and the mixed gas after hydrogen is separated by the hydrogenation reactor is recovered as a high-calorie mixed gas The method for selectively recovering hydrogen from a mixed gas containing hydrogen gas as described in (1) to (3) above.

(5) Means capable of transporting heat between the two reactors so as to mutually compensate heat absorption for suppressing heat generation of the hydrogenation reaction and heat supply for suppressing heat absorption of the dehydrogenation reaction. The method for selectively recovering hydrogen from a mixed gas containing hydrogen gas according to any one of (1) to (4), wherein the method is used.
(6) The selective recovery of hydrogen from the mixed gas containing hydrogen gas as described in (1) to (5) above, wherein the mixed gas containing hydrogen gas is a by-product gas generated at a steel works Method.
(7) The method for selectively recovering hydrogen from a mixed gas containing hydrogen gas as described in (6) above, wherein the mixed gas containing hydrogen gas is coke oven gas.
(8) Selection of hydrogen from the mixed gas containing hydrogen gas as described in (1) to (5) above, wherein the mixed gas containing hydrogen gas is naphtha, methane decomposition gas or coal gasification gas (9) The hydrogen gas described in (1) to (8) above, wherein the dehydrogenation reaction of naphthalene is carried out at a reaction temperature of 150 to 450 ° C. and a reaction pressure exceeding normal pressure. A method for selectively recovering hydrogen from a gas mixture.
(10) The method for selectively recovering hydrogen from a mixed gas containing hydrogen gas as described in (9) above, wherein the reaction pressure is 10 atm to 50 atm.
(11) A method for producing decalin by hydrogenating naphthalene using high-pressure hydrogen recovered by a method for selectively recovering hydrogen from a mixed gas containing hydrogen gas as described in (1) to (10) above.

  According to the present invention, even if a mixed gas containing hydrogen as a raw material contains a heteroatom (S, O, N) compound, hydrogen gas can be separated and recovered from the mixed gas by a simple method. Therefore, it becomes possible to supply hydrogen gas at low cost.

  The present inventors conducted a test on the hydrogenation-dehydrogenation reaction of naphthalene-decalin. In the reaction of naphthalene-decalin, the reaction catalyst is poisoned by impurities in the mixed gas containing hydrogen gas. It was found that the reaction does not proceed sufficiently, and that when the catalyst is Ni, Pt, Pd, Ru, Rh, etc., the heteroatom compound in the mixed gas has a catalyst poisoning action.

Examples of the heteroatom compound having such a catalyst poisoning action include H ₂ S, CO, H ₂ O, HCN, and NH ₃ . And when they are present at the concentrations shown in Table 1 below, the catalyst poisoning action is particularly remarkable, and the influence is large when the heteroatom is S. In particular, the catalyst is a noble metal type such as Pt, Pd, etc. It turned out that the influence is large in the thing.

As described above, when 1 ppm or more of H ₂ S is contained in the reaction hydrogen gas, the catalyst is poisoned and the reaction hardly proceeds. Further, in a gas such as COG that is normally produced, H ₂ S is present in several thousand ppm. Therefore, when this gas is used as a hydrogen source gas, the hydrogenation reaction process does not proceed in the naphthalene-decalin system. This poisoning of the catalyst is probably caused by a heteroatom in the heteroatom (S, O, N) compound adhering to the active site of the catalyst and losing the activity of the catalyst.
The aromatic compound → hydrogenated aromatic compound system includes a benzene-cyclohexane system and a toluene-methylcyclohexane system, and these systems have a large catalytic poisoning effect by a heteroatom compound as in the naphthalene-decalin system.

On the other hand, when the reaction system is a naphthalene-tetralin system, it has been found that the reaction proceeds sufficiently even if a considerable amount of a heteroatom compound is present in the hydrogen mixed gas. In the case of a Ni—Mo catalyst, it was confirmed that the reaction proceeds without poisoning the catalyst even when several thousand ppm of S is present in the raw material.

In the present invention, a catalyst for promoting the hydrogenation reaction from naphthalene to tetralin is used. Examples of the catalyst for the hydrogenation reaction from naphthalene to tetralin include a Co—Mo or Ni—Mo based catalyst.
As such a catalyst, a catalyst as disclosed in Japanese Patent No. 3,139,115, Japanese Patent Publication No. 56-1293 and Mitsui Engineering & Shipbuilding No. 156, pages 1 to 7 can be used.

The catalyst described in Japanese Patent No. 3,139,115 has a specific surface area of 200 to 400 m ² / g, a pore volume of 0.37 to 0.57 ml / g, an average pore diameter of 55 to 90 kg, 50% or more of the pores are distributed in the range of 55 to 90 mm in pore diameter, and the pore diameter exceeding 90 mm has a sharp pore distribution of 15% or less of the total pores, and cobalt and molybdenum are oxidized. This is a cobalt-molybdenum-alumina catalyst containing 11 to 25% by weight in total.
In addition, the catalyst described in Japanese Patent Publication No. 56-1293 is supported on silica, alumina, silica-alumina, diatomaceous earth, pumice, etc., by supporting one or more of cobalt, nickel, molybdenum and tungsten oxides. This is a catalyst that has been sulfurized.

The reaction of hydrogenating naphthalene to produce tetralin can be represented by the following reaction formula.
C ₁₀ H ₈ (naphthalene) + 2H ₂ → C ₁₀ H ₁₂ (tetralin)
The reaction to the right side in the above reaction formula is a reaction accompanied by exotherm, and the reaction to the left side is the opposite endothermic reaction. The reaction rate of the naphthalene-tetralin system is about 10 times faster than that of the naphthalene-decalin system.

  In addition, the method of the present invention includes a step of dehydrogenating tetralin produced by the hydrogenation reaction to produce naphthalene. In the dehydrogenation reaction for producing naphthalene and hydrogen gas from tetralin, a catalytic reaction by a dehydrogenation catalyst is used. As the dehydrogenation catalyst, a known catalyst can be used in addition to the above-described hydrogenation catalyst. For example, palladium, platinum, rhodium, iridium, ruthenium, osmium, molybdenum, rhenium, tungsten, vanadium, nickel, chromium, cobalt, and the like. A catalyst containing at least one metal selected from the group consisting of iron can be used. As the catalyst carrier, alumina, silica, zirconia, zeolite, titania, activated carbon and the like can be used.

The conditions for the hydrogenation reaction are preferably a temperature of 200 to 250 ° C. and a pressure of 10 to 30 atm.
The dehydrogenation reaction is carried out by continuous dehydrogenation reaction under heating and pressure such that tetralin is in a liquid state in the presence of a catalyst. Conditions such as temperature and pressure in the dehydrogenation reaction vessel can be set as appropriate, but the reaction temperature is 150 to 450 ° C., preferably 250 to 350 ° C., and the reaction pressure is a pressure exceeding normal pressure. , Preferably 10 to 50 atm.

FIG. 1 shows an example in which COG is used as a mixed gas containing hydrogen gas.
The hydrogen selective recovery method of the present invention will be described with reference to FIG.
COG and naphthalene returned from the dehydrogenation reactor 2 are respectively introduced into the hydrogenation reactor 1. Hydrogen and naphthalene in the mixed gas react with each other by a hydrogenation catalyst to produce tetralin, and waste COG after the reaction removes liquid components such as tetralin and is discharged from the hydrogenation reactor 1. The tetralin content produced by the reaction is led from the hydrogenation reactor 2 to the dehydrogenation reactor 2 by piping, where the tetralin is converted into hydrogen gas and naphthalene by the dehydrogenation catalyst, and the produced naphthalene is hydrogenated. On the other hand, the generated hydrogen is recovered as a product after removing naphthalene and the like.

  As described above, the hydrogenation reaction of naphthalene is an exothermic reaction, and the dehydrogenation reaction of tetralin is an endothermic reaction. In the present invention, in order to effectively use the heat generated by the exothermic reaction, each reaction apparatus is provided with a heat exchange pipe as shown in FIG. 1, and water (steam), heat transfer oil, etc. are provided in the pipe. It is preferable to circulate the heat medium.

This heat medium recovers the heat generated by the hydrogenation reaction through the heat exchange pipe 5 provided in the hydrogenation reaction apparatus, passes through the heat medium storage facility 4, and is accommodated in the heat medium storage facility 4. After being reheated as necessary until the amount of heat required by the dehydrogenation reactor 2 is obtained by indirect heat exchange with the heat medium being heated, the heat exchange pipe 5 'of the dehydrogenation reactor 2 is circulated. As a result, the heat absorbed by the dehydrogenation reaction is applied to the reaction system and cooled, and after passing through the heat medium storage facility 3 again, the heat is returned to the hydrogenation reaction apparatus 1.
As described above, heat generated by the hydrogenation reaction can be effectively utilized by enabling the transport of heat between the two reactors.

In the present invention, it is desirable to arrange the hydrogenation reaction apparatus and the dehydrogenation reaction apparatus in close proximity to each other. Such close arrangement makes it possible to effectively use heat generated by hydrogenation (exothermic reaction) on the dehydrogenation (endothermic reaction) side.
Moreover, when performing hydrogenation and dehydrogenation by a naphthalene-tetralin type | system | group, the naphthalene after dehydrogenating in a high temperature state (about 330 degreeC) can be immediately returned to the adjacent hydrogenation apparatus with high temperature. Since naphthalene is solidified at about 80 ° C., naphthalene can be handled in a liquid state in the vicinity.

  In particular, when the place where the hydrogen (containing) gas is generated and the place where the recovered hydrogen gas is consumed are close to each other, as described above, the heat can be effectively used by arranging them side by side. This is advantageous because it can be used as it is without having to store hydrogen gas in a storage container or the like.

  Further, the present invention can also be applied to a case where the place where the hydrogen (containing) gas is generated and the place where the recovered hydrogen gas is consumed, but in that case, hydrogenation with a naphthalene-tetralin system, When dehydrogenation is performed, naphthalene after dehydrogenation at a high temperature cannot be immediately returned to the hydrogenation reactor while maintaining a high temperature. Therefore, the naphthalene is heated and handled in a liquid state. .

As the mixed gas, any mixed gas containing hydrogen can be used without any particular limitation.
Such gases include COG (coke oven gas), BFG (blast furnace gas), LDG (by-product gas of steelworks such as converter gas), especially hydrogen gas is 50-60% in COG. Since it is contained, it is suitable as a mixed gas used in the present invention.
In addition, since COG contains methane, when COG is used as a mixed gas containing hydrogen in the present invention, as a result of separation of hydrogen gas from COG gas in the hydrogenation reaction apparatus, residual COG gas is Since the methane concentration increases and becomes high calorie, it is suitable as a fuel gas.

In addition, blast furnace gas and converter gas are inferior in efficiency because the hydrogen concentration is low, but in the case of converter gas, CO in the gas is shift-converted to convert it into hydrogen and carbon dioxide, and the hydrogen concentration is reduced. By making it high, it becomes suitable for the mixed gas used in the present invention.
Other mixed gas containing hydrogen gas includes naphtha or methane decomposition gas or coal gasification gas, woody biomass gasification gas, waste plastic gasification gas, city gas (natural gas) reformed gas, waste (including RDF) A gasification gas can be mentioned.

  Hereinafter, the present invention will be described based on examples.

In the present embodiment, the apparatus shown in FIG. 1 is used.
Purified naphthalene 67.5 kg / Hr and COG 74.76 Nm ³ / Hr were charged into the hydrogenation reactor of FIG. 1 at a pressure of 20 kg / cm ² . The composition of COG was H ₂ 56%, CH ₄ 28%, C ₂ H ₄ 3%, CO 7%, N ₂ 3%, CO ₂ 3%, and H ₂ S was present at 3000 ppm.
The temperature of the hydrogenation reactor was 250 ° C., and a Ni—Mo catalyst using alumina as a support was used.
The product is tetralin 69.61 kg / Hr, and the unreacted COG is 53.83 Nm ³ / Hr (composition: H ₂ 38.9%, CH ₄ 38.9%, C ₂ H ₄ 4.2%, N ₂ 4. 2%, CO ₂ 4.2%, H ₂ S 4200 ppm).
The total amount of tetralin produced was sent to the dehydrogenation tower and dehydrogenated. Conditions were increased to 20 kg / cm ² at 440 ° C., and the catalyst was the same Ni—Mo system as hydrogenation.
Recovery exhaust gas: Hydrogen 20.9Nm ³ / Hr
Discharged liquid; naphthalene 67.5 kg / Hr,
By this reaction, 20 kg / cm ² of hydrogen gas could be obtained. This naphthalene was returned to the hydrogenation tower.

The hydrogenation reactor shown in FIG. 1 was charged with 67.5 kg / Hr of naphthalene, 7.5 t / Hr of tetralin and 46.89 Nm ³ / Hr of COG at a pressure of 10 kg / cm ² . S-1000 ppm was present in naphthalene-tetralin and 3000 ppm of H ₂ S was present in COG. The composition of COG was the same as in Example 1.
The temperature of the hydrogenation reactor was 250 ° C., and a Ni—Mo catalyst using alumina as a support was used. The product was tetralin 69.40 kg / Hr, naphthalene 7.48 kg / Hr and unreacted COG 25.89 Nm ³ / Hr (H ₂ 29.8%, CH ₄ 44.7, C ₂ H ₄ 4.8%, CO 11.2%, CO ₂ 4.8%, N ₂ 4.7%, H ₂ S 4500 ppm).
The total amount of tetralin and naphthalene produced was sent to a dehydrogenation reactor and dehydrogenated. Conditions were pressurized at 440 ° C. to 30 kg / cm ² and the catalyst was a Ni—Mo based catalyst.
The recovered hydrogen gas was 21.0 Nm ³ / Hr, and naphthalene 67.5 kg / Hr and tetralin 7.5 kg / Hr were obtained. Naphthalene and tetralin were all returned to the hydrogenation reactor.

  The method of the present invention can be applied as a method for supplying hydrogen gas in the fuel cell and chemical industry fields that require hydrogen gas.

It is a figure which shows an example of the apparatus for implementing the selective collection | recovery method of the hydrogen gas from the mixed gas containing the hydrogen gas of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydrogenation reactor 2 Dehydrogenation reactor 3 High pressure pump 4 Heat medium storage equipment 5,5 'Heat exchange piping 6 Heat medium pump 7 Pressure reducing valve

Claims (11)

  Using a hydrogenation reaction apparatus and a dehydrogenation reaction apparatus connected in series, a mixed gas containing a hydrogen gas containing a heteroatom compound and an aromatic compound are reacted in the presence of a catalyst in the hydrogenation reaction apparatus. Hydrogen in the mixed gas is selectively stored in an aromatic compound to produce a hydrogenated aromatic compound, and then the hydrogenated aromatic compound is supplied to the dehydrogenation reactor to perform a dehydrogenation reaction. A method for selectively recovering hydrogen from a mixed gas containing hydrogen gas, wherein the aromatic compound is naphthalene and the hydrogenated aromatic compound is tetralin A method for selectively recovering hydrogen from a mixed gas containing hydrogen gas. The hydrogen gas according to claim 1, wherein the kind of the heteroatom compound and the concentration in the mixed gas containing hydrogen gas satisfy at least one condition selected from the following (1) to (5): A method for selective recovery of hydrogen from a mixed gas.
(1) H ₂ S having a concentration of 100 ppm or more
(2) CO with a concentration of 0.1% or more
(3) H ₂ O having a concentration of 1000 ppm or more
(4) NH ₃ having a concentration of 100 ppm or more
(5) HCN with a concentration of 100 ppm or more   3. The method for selectively recovering hydrogen from a mixed gas containing hydrogen gas according to claim 1 or 2, wherein the catalyst is a Co-Mo or Ni-Mo system.   The mixed gas containing hydrogen gas is a mixed gas containing hydrogen gas and methane gas, and the mixed gas after hydrogen is separated by the hydrogenation reactor is recovered as a high-calorie mixed gas A method for selectively recovering hydrogen from a mixed gas containing hydrogen gas according to any one of claims 1 to 3.   Using a means that enables heat transfer between the two reactors such that the heat absorption for suppressing the exothermic heat of the hydrogenation reaction and the heat supply for suppressing the heat absorption of the dehydrogenation reaction are mutually compensated. The method for selectively recovering hydrogen from a mixed gas containing hydrogen gas according to any one of claims 1 to 4.   The method for selectively recovering hydrogen from a mixed gas containing hydrogen gas according to any one of claims 1 to 5, wherein the mixed gas containing hydrogen gas is a by-product gas generated at a steel mill.   The method for selectively recovering hydrogen from a mixed gas containing hydrogen gas according to claim 6, wherein the mixed gas containing hydrogen gas is coke oven gas.   The method for selectively recovering hydrogen from a mixed gas containing hydrogen gas according to any one of claims 1 to 5, wherein the mixed gas containing hydrogen gas is naphtha, methane decomposition gas, or coal gasification gas.   The hydrogen from the mixed gas containing hydrogen gas according to any one of claims 1 to 8, wherein the dehydrogenation reaction of the naphthalene is performed at a reaction temperature of 150 to 450 ° C and a reaction pressure exceeding normal pressure. Selective collection method.   The method for selectively recovering hydrogen from a mixed gas containing hydrogen gas according to claim 9, wherein the reaction pressure is 10 atm to 50 atm.   A method for producing decalin by hydrogenating naphthalene using high-pressure hydrogen recovered by a method for selectively recovering hydrogen from a mixed gas containing hydrogen gas according to any one of claims 1 to 10.

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