JP2003144924A - Selective oxidation catalyst for hydrogen, selective oxidation method for hydrogen and dehydrogenation method for hydrocarbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively provide a catalyst for selectively oxidizing hydrogen formed by the dehydrogenation reaction of hydrocarbon and hydrogen in gas containing formed hydrocarbon having an olefinic unsaturated bond and raw material hydrocarbon. SOLUTION: The catalyst for catalytically oxidizing hydrogen in gas containing hydrogen and hydrocarbon is obtained by supporting a platinum group element on a carrier which is formed by coating a heat-resistant inorganic compound with niobium oxide and/or tantalum oxide. In the method for oxidizing hydrogen in the gas containing hydrogen and hydrocarbon, this catalyst is brought into contact with gas containing hydrogen, hydrocarbon and oxygen to oxidize hydrogen in the gas. This dehydrogenation method for hydrocarbon includes a first process for forming gas containing dehydrogenated hydrocarbon, unreacted raw material hydrocarbon and hydrogen by bringing a raw material hydrocarbon into contact with a dehydrogenation catalyst, a second process for mixing the gas formed in the first process with oxygen-containing gas and bringing this gaseous mixture into contact with this catalyst to oxidize hydrogen in the gas and a third process for bringing the gas formed in the second process into contact with the dehydrogenation catalyst to dehydrogenate the raw material hydrocarbon in the gas.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a catalyst for selectively catalytically oxidizing hydrogen in a gas containing hydrogen and hydrocarbons with oxygen, a method for oxidizing hydrogen using the catalyst,
And a method for dehydrogenating hydrocarbons using the catalyst.

2. Description of the Related Art One of the methods for producing a hydrocarbon having an olefinically unsaturated bond is a method for dehydrogenating a hydrocarbon.

For example, a method for producing styrene by dehydrogenating ethylbenzene using an iron-based catalyst is known. However, since this dehydrogenation reaction is an equilibrium reaction, the produced hydrogen hinders the progress of the reaction. In addition, since the dehydrogenation reaction is an endothermic reaction, the temperature in the system decreases as the reaction progresses. For these reasons, it was difficult to produce styrene with high yield even when dehydrogenating ethylbenzene by this method. Therefore, various methods for shifting the reaction equilibrium and compensating for the decrease in the reaction temperature by selectively oxidizing hydrogen generated in the step of producing styrene from ethylbenzene have been studied.

Japanese Unexamined Patent Publication (Kokai) No. 49-56930 discloses unreacted ethylbenzene, styrene, and hydrogen obtained by dehydrogenating ethylbenzene using an oxidation catalyst in which platinum is supported on A-type zeolite or alumina. A method for oxidizing hydrogen in a gas containing is described. However, this method cannot oxidize hydrogen selectively, and some of the hydrocarbons were also oxidised.

US Pat. No. 4,565,898 discloses a method of oxidizing hydrogen in a gas obtained by dehydrogenating ethylbenzene using a catalyst in which platinum, tin and lithium are supported on alumina. Have been described. However, even with this method, hydrogen could not be selectively oxidized. Simultaneous oxidation of hydrocarbons during the oxidation of hydrogen is not preferable not only in terms of the loss of hydrocarbons but also in the generation of carbon dioxide. Because carbon dioxide reduces the activity of the dehydrogenation catalyst and the selectivity of the hydrogen oxidation catalyst (Hirano, Catalyst, 29, (8), 641 (198).
7) and the like), the reaction results will be significantly reduced when the dehydrogenation reaction and the selective oxidation reaction of hydrogen are alternately performed in series.

In addition, in the process for producing styrene in which such dehydrogenation and selective oxidation of the produced hydrogen are carried out, when the dehydrogenation catalyst contains a potassium compound, the potassium compound scatters (BD Herzog et. .al., In
d. Eng. Chem. Prod. Res. Dev. Two
3, (2), 187 (1984); Hayasaka et al., Proceedings of the 24th Japan Aromatic Industry Conference, p36 (1990), etc.). When the scattered potassium compounds adhere to the oxidation catalyst, the selectivity of the selective oxidation reaction of hydrogen is lowered,
In addition, it mainly promotes the steam reforming reaction of styrene to increase the amount of carbon dioxide generated.

Japanese Unexamined Patent Publication (Kokai) No. 9-29095 discloses a method of oxidizing hydrogen in a gas obtained by dehydrogenating ethylbenzene using a catalyst in which platinum is supported on niobium oxide or the like. However, although this method can selectively oxidize hydrogen as compared with the above-mentioned method, it is not economically advantageous because it uses relatively expensive niobium.

Japanese Unexamined Patent Publication (Kokai) No. 11-80045 describes a method of selectively oxidizing hydrogen by bringing a gas from which a potassium compound has been removed in advance into contact with an oxidation catalyst. However, this method requires a potassium adsorption step between the dehydrogenation step and the hydrogen oxidation step, which complicates the apparatus. In addition, JP-A-11-32
No. 2303 describes a method of oxidizing hydrogen in a gas obtained by dehydrogenating ethylbenzene using a catalyst obtained by supporting niobium oxide or tantalum oxide and a platinum group metal on a heat-resistant inorganic carrier. Has been done. This catalyst has a higher strength than the catalyst described in JP-A-9-29095, but again a small amount of hydrocarbons burned.

[0008]

DISCLOSURE OF THE INVENTION The present invention selectively oxidizes hydrogen produced in a hydrocarbon dehydrogenation reaction, a hydrocarbon having an olefinic unsaturated bond, and hydrogen in a gas containing a raw material hydrocarbon. An object is to provide a catalyst at low cost.

[0009]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that a carrier having a heat-resistant inorganic compound as a core and a surrounding area coated with niobium oxide and / or tantalum oxide is used. The inventors have found that a catalyst supporting a platinum group element oxidizes hydrogen extremely selectively, and completed the present invention.

That is, the gist of the present invention is to provide hydrogen and hydrocarbons characterized in that a platinum group element is carried on a carrier obtained by coating a heat-resistant inorganic compound with niobium oxide and / or tantalum oxide. A catalyst for catalytically oxidizing hydrogen in a contained gas with oxygen; hydrogen and carbonization characterized by contacting the catalyst with a gas containing hydrogen, hydrocarbon and oxygen to oxidize hydrogen in the gas Method for oxidizing hydrogen in gas containing hydrogen; contacting raw hydrocarbon with dehydrogenation catalyst to produce dehydrogenated hydrocarbon, unreacted raw hydrocarbon, and gas containing hydrogen Step, the second step of oxidizing the hydrogen in the gas by mixing the gas generated in the first step with the oxygen-containing gas and then contacting this catalyst, and the gas generated in the second step as a dehydrogenation catalyst. contact The third step, the dehydrogenation process of hydrocarbons comprising a dehydrogenating a hydrocarbon feedstock in the gas by causing a.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The catalyst according to the present invention comprises granulating a heat-resistant inorganic compound into a desired size, coating the granule with niobium oxide and / or tantalum oxide to form a carrier, and then applying platinum to the carrier. It can be manufactured by supporting an element of the group and drying and firing. Examples of the heat-resistant inorganic compound include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide and the like. Of these, aluminum oxide or silicon oxide is preferable. If desired, they can be used together.

The heat-resistant inorganic compound preferably has a finer particle size in terms of moldability and catalyst strength at the time of granulation, so 50% or more thereof is 74 μm or less (200 mesh or less),
It is particularly preferably 43 μm or less (325 mesh or less). Granulation is performed by mixing a heat-resistant inorganic compound and an appropriate amount of water, and rolling using a tilting plate granulator, a drum granulator, a truncated cone granulator, a vibrating rotary granulator, etc. It is preferable to granulate into spheres by a formula granulation method or the like. At this time, a molding aid can be used to enhance the binding force of the particles. As a molding aid, cellulose, corn starch, polyvinyl alcohol, flour, diatomaceous earth, glucose, rice paste,
Examples include polyethylene glycol, gum arabic,
If desired, these can be used in combination.

The granulated product having a desired particle size is obtained by sieving. The particle size depends on the equipment that uses this catalyst.
It may be determined as appropriate. The granular heat-resistant inorganic compound thus obtained and niobium oxide and / or tantalum oxide are mixed with an appropriate amount of water and granulated by the rolling granulation method or the like to obtain carrier particles. . By this operation, niobium oxide and / or tantalum oxide can be coated around the heat-resistant inorganic compound as a nucleus. At this time also, the molding aid may be used. By covering the heat-resistant inorganic compound with niobium oxide and / or tantalum oxide to prevent the heat-resistant inorganic compound from being exposed to the outside, the adverse effect of the potassium compound scattered from the dehydrogenation catalyst can be avoided. That is, according to the knowledge of the present inventors, when the scattered potassium compound adheres to the heat-resistant inorganic compound, the selectivity of the catalyst decreases, but when it adheres to niobium oxide or tantalum oxide, potassium niobate or tantalum. It is fixed as potassium acid and does not affect the catalytic activity.

The content of niobium oxide and / or tantalum oxide in the carrier particles is preferably 20 to 80% by weight. If it is less than 20% by weight, the heat-resistant inorganic compound may not be completely covered with niobium oxide and / or tantalum oxide, or the niobium oxide and / or tantalum oxide may be thin and lack durability. For this reason, the influence of the potassium compound cannot be sufficiently avoided, and the selectivity of hydrogen oxidation is reduced. 8
If it exceeds 0% by weight, it does not affect the catalytic activity or the selectivity of hydrogen oxidation, but it is not preferable because the catalyst strength is lowered and the catalyst becomes expensive.

Further, it is preferable that the carrier particles have a heat-resistant inorganic compound as a core, and the periphery thereof is substantially uniformly covered with a layer of 20 to 80% by volume of niobium oxide and / or tantalum oxide. As niobium oxide or tantalum oxide used for coating, a commercially available product may be crushed to a desired size before use. Since finer particles are more suitable in terms of moldability and catalyst strength, it is preferable to use crushed particles of 10 μm or less, especially 5 μm or less.

It is preferable to coat with niobium oxide, especially niobium pentoxide. The carrier granules obtained above are 100-
After drying at 150 ° C for 2 to 24 hours, it is calcined at 300 to 1500 ° C for 3 to 12 hours to obtain a catalyst carrier. After impregnating the catalyst carrier with an aqueous solution of a salt of a platinum group element, the platinum group element is supported by drying and firing at a temperature of 50 to 1000 ° C.
A selective hydrogen oxidation catalyst is obtained.

The proportion of niobium oxide and / or tantalum oxide in the obtained selective hydrogenation catalyst is preferably 20 to 80% by weight. The ratio of platinum group elements is 0.0
It is preferably from 01 to 10% by weight, particularly from 0.05 to 5% by weight. When this ratio is low, the activity of the oxidation reaction is reduced. On the other hand, if this ratio exceeds 10% by weight, the catalytic activity and the selectivity of hydrogen oxidation are not affected, but the catalyst becomes expensive, which is not preferable.

Examples of the platinum group element include platinum and palladium. These may be used in combination if desired. Any of these salts may be used, and examples thereof include halides, hydroxides and sulfates.
Alternatively, an organic compound such as bisacetylacetonatoplatinum or platinous cyanide can be used. A gas containing hydrogen, hydrocarbons and oxygen is brought into contact with the catalyst according to the present invention to selectively oxidize hydrogen in the gas. This oxidation reaction is usually carried out at 300 to 800 ° C., preferably 400 to 700 ° C. If the temperature is higher than this, the selectivity is lowered and the combustion rate of hydrocarbons is increased. On the other hand, when the temperature is low, the selectivity is not affected, but the catalytic activity is reduced.

The reaction pressure is preferably 0.05 to 10 atm. As the gas to be subjected to the reaction, a gas containing hydrogen and dehydrogenated hydrocarbon produced by contacting the raw material hydrocarbon with a dehydrogenation catalyst, and a gas containing an unreacted raw material hydrocarbon, and an oxygen-containing gas were mixed. Gas is preferred. As the oxygen-containing gas, oxygen gas, air, oxygen-enriched air,
Air diluted with an inert gas may be used. Further, the oxygen-containing gas may contain water vapor.

When all oxygen is consumed, coking may occur on the catalyst, but this does not affect the ability to selectively oxidize hydrogen. A hydrocarbon dehydrogenation method including a selective hydrogen oxidation reaction using a catalyst according to the present invention includes the following three steps. In the first step, the dehydrogenation reaction is performed by bringing the raw material hydrocarbon into contact with the dehydrogenation catalyst in the first stage reactor filled with the dehydrogenation catalyst. In the second step, the gas produced in the first-stage reactor and the oxygen-containing gas are mixed and supplied to the second-stage reactor filled with the catalyst according to the present invention to selectively oxidize hydrogen. At this time, the gas temperature rises due to the oxidation reaction. In the third step, the second
The gas produced in the three-stage reactor is charged with a third hydrogen gas filled with a dehydrogenation catalyst
The raw material hydrocarbons remaining in the stage reactor are dehydrogenated. In addition, the reaction rate of the raw material hydrocarbon can be improved by passing the gas generated in the third-stage reactor through the second step and the third step again. Further, steam is usually allowed to coexist in the dehydrogenation reaction, but steam can also be allowed to coexist in this process.

As the raw material hydrocarbon to be subjected to the dehydrogenation reaction, any hydrocarbon which can form an olefinically unsaturated bond by dehydrogenation can be used. Among them, ethylbenzene,
Aromatic hydrocarbons having a dehydrogenatable hydrocarbon group such as diethylbenzene, ethylnaphthalene, and diethylnaphthalene are preferable, and ethylbenzene is particularly preferable. The dehydrogenation method according to the present invention will be specifically described with reference to a process for producing styrene from ethylbenzene. In a first-stage reactor filled with an iron-based catalyst containing iron and an alkali metal as main active components, a mixed gas of ethylbenzene and steam is brought into contact with the iron-based catalyst, and the temperature is 500 ° C to 800 ° C and 0.05 to 10 atm. The dehydrogenation reaction is performed at the pressure of. Then, the gas flowing out from the first-stage reactor and the oxygen-containing gas are mixed and supplied to the second-stage reactor filled with the catalyst according to the present invention,
Selectively oxidize hydrogen in gas. Finally, the gas flowing out from the second-stage reactor is supplied to the third-stage reactor filled with the iron-based catalyst to dehydrogenate the residual ethylbenzene to obtain styrene. According to this method, hydrogen, which hinders the progress of the dehydrogenation reaction in the second-stage reactor, can be selectively oxidized, and a gas whose temperature has risen due to hydrogen oxidation is supplied to the third-stage reactor. Because you can
Styrene can be obtained in a much higher yield than the conventional dehydrogenation reaction.

[0022]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The structure of the obtained hydrogen-selective oxidation catalyst was determined by electron probe microanalyzer (EPMA;
It was confirmed using Shimadzu EPMA-1600).
That is, after embedding the catalyst in epoxy resin and polishing it to obtain a cross section that passes through the center of the catalyst sphere, electron beam energy of 15 K with niobium and aluminum as the target elements.
V, 100 nA, beam size: 2 μm, step size: 2 μm, line analysis in two directions in the X and Y directions,
The cross-sectional areas of the layer made of alumina and the layer made of niobium pentoxide were determined, and the volume occupied by each of them was calculated.

The contents of aluminum and niobium in the hydrogen selective oxidation catalyst were determined by fluorescent X-ray (XRF) analysis. That is, 0.5 g of the sample, 5 g of the flux, and 0.05 g of the release agent were mixed and heated to produce a glass bead. The XRF intensity was measured by ZSX100e manufactured by Rigaku Denki Kogyo, and the content of each element was determined by the calibration curve method. Example 1 (Catalyst preparation) 100 parts by weight of γ-alumina powder, 5 parts by weight of cellulose (Avicel, manufactured by Asahi Kasei Corporation), and a small amount of water were kneaded. This is put into a tilting plate type rolling granulator, granulated while sprinkling water in a spray form, and a diameter of 3 m is obtained using a sieve.
The size was adjusted to about m. The obtained granules were put into the above granulator, and while sprinkling water in a spray form, 400 parts by weight of niobium pentoxide powder having an average particle diameter of 2 μm was added little by little, and granulated, and a diameter of 4 was obtained using a sieve. The size was adjusted to 0.5 mm.

The obtained spheres were dried at 120 ° C. for 3 hours, placed in a muffle furnace and baked at 900 ° C. for 3 hours. 100 g of this baked product was taken and impregnated with 30 mL of a chloroplatinic acid aqueous solution containing 0.2 g of platinum. This was dried by a rotary evaporator under reduced pressure at 60 ° C. for 1 hour, then in a dryer at 120 ° C. for 3 hours, and then in the air at 65 ° C.
By calcination at 0 ° C. for 3 hours, a selective hydrogen oxidation catalyst containing 0.2% by weight of platinum was obtained. The obtained catalyst is EPM
When analyzed by A, a layer of niobium pentoxide having a thickness of 0.75 mm was formed around an alumina nucleus having a diameter of 3 mm. The weight composition of the obtained catalyst was 7% niobium pentoxide.
2.0% by weight, aluminum oxide 27.8% by weight, platinum 0.2% by weight, and the volume composition is niobium pentoxide 70.4.
% By volume and 29.6% by volume of aluminum oxide. (Reaction) A quartz reaction tube having an inner diameter of 15.75 mm was filled with 44 mL of quartz chips having almost the same particle size as that of the catalyst, 8 mL of the selective hydrogen oxidation catalyst obtained above was filled therein, and further on that. After filling 42 mL of the above quartz chip, 1
A hydrogen-nitrogen mixed gas containing 0% hydrogen was introduced at 600 ° C. for 1 hour to reduce the catalyst. Then, the reaction tube was charged with ethylbenzene, styrene, water, hydrogen, oxygen and nitrogen 1: 0.4: 11.5: 0.43: 0.18:
Gas containing 0.69 (molar ratio) at 630 ° C., SV =
It was introduced at a space velocity of 6550 hr ⁻¹ (0 ° C., 1 atm conversion) and LHSV (ethylbenzene + styrene) = 3.5 hr ⁻¹ to selectively oxidize hydrogen.

The gas flowing out from the reaction tube and the condensate obtained by cooling the gas were analyzed by gas chromatography. Reaction start 8
After the lapse of time, the analysis results were as follows: oxygen conversion rate 100%, hydrogen conversion rate 74.4%, styrene and ethylbenzene combustion rate 0.8.
It was 6%. The styrene and ethylbenzene burning rate is the percentage of the total number of moles of styrene and ethylbenzene lost in the reaction with respect to the total number of moles of styrene and ethylbenzene supplied to the reaction tube.

Comparative Example 1 Japanese Unexamined Patent Publication No. 11-322303 DISCLOSURE OF THE INVENTION According to the method described in Example 1, a catalyst having a catalyst composition of 0.2% by weight of platinum, 5% by weight of niobium pentoxide and 94.8% by weight of aluminum oxide. Was prepared. An oxidation reaction of hydrogen was carried out in the same manner as in Example 1 except that this catalyst was used. Eight hours after the start of the reaction, the reaction tube outlet gas and the condensate of the receiver were analyzed by gas chromatography. As a result, the oxygen conversion rate was 100%, the hydrogen conversion rate was 68.8%, and the styrene and ethylbenzene combustion rate was 1.07%.

Example 2 An iron oxide-oxidation prepared by the method described in Example 6 of JP-A-4-277030 by mounting a thermocouple insertion tube having an outer diameter of 4 mm on a reaction tube made of SUS316 having an inner diameter of 21 mm. 23.3 mL of the potassium-based dehydrogenation catalyst and 20 mL of the selective hydrogen oxidation catalyst of Example 1 were sequentially charged to form a packed bed composed of the dehydrogenation catalyst layer and the oxidation catalyst layer from the upstream side. A space was provided between both catalyst layers, and an air supply pipe was opened here. This reaction tube was placed in an electric furnace and heated while circulating nitrogen gas so that the inlet temperature of the dehydrogenation catalyst layer was 550.
When the temperature reached ℃, the nitrogen gas was replaced with a mixed gas of nitrogen gas and water vapor, ethylbenzene was supplied, and air was supplied from an air supply pipe. The temperature of the oxidation catalyst layer is 630
C., the supply gas to the oxidation catalyst layer is ethylbenzene, styrene, water, hydrogen, oxygen, and nitrogen 1: 0.4: 11.
5: 0.43: 0.18: 0.69 (molar ratio) composition,
SV = 6550hr ^-1 (0 ° C, 1 atm conversion), LHSV
The temperature of the dehydrogenation catalyst layer and the supply gas were adjusted so that the space velocity of (ethylbenzene + styrene) = 3.5 hr ⁻¹ was obtained.

After the reaction was continued for 770 hours, the supply of ethylbenzene was stopped and the system was cooled while purging with nitrogen.
Then, the oxidation catalyst layer was divided into 10 layers, and 40% by volume of the catalyst was extracted from each layer. A quartz reaction tube having an inner diameter of 15.75 mm was filled with 44 mL of a quartz chip having almost the same particle size as that of the catalyst, 8 mL of the extracted selective hydrogen oxidation catalyst was filled thereon, and 42 mL of the above quartz chip was further placed thereon. After filling, the selective hydrogen oxidation reaction was carried out in the same manner as in Example 1.

Eight hours after the start of the reaction, the gas flowing out from the reaction tube and the condensate obtained by cooling the gas were analyzed by gas chromatography. As a result, the oxygen conversion rate was 100% and the hydrogen conversion rate was 7%.
5.3%, styrene and ethylbenzene burning rate 0.89
%Met. Comparative Example 2 Example 2 was repeated except that the catalyst prepared in Comparative Example 1 was used in place of the selective hydrogen oxidation catalyst of Example 1.
The hydrogen oxidation reaction was carried out in the same manner as in.

Eight hours after the start of the reaction, the gas flowing out from the reaction tube and the condensate obtained by cooling the gas were analyzed by gas chromatography. As a result, the oxygen conversion rate was 100% and the hydrogen conversion rate was 3%.
8.4%, styrene and ethylbenzene combustion rate 0.78
%Met.

Continued front page    (72) Inventor Totsuru Iwakura             1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Chemical Corporation             Inside the company F-term (reference) 4G069 AA03 BA01A BA01B BA02A                       BA04A BA05A BB02A BB02B                       BB04A BB04B BC55A BC55B                       BC56A BC69A BC72A BC75A                       BC75B CB07 CD10 FC08                 4H006 AA02 AC12 BA25 BA26 BA55                       BC10 BD60 BE20 BE30                 4H039 CA21 CC10

Claims (10)

[Claims] 1. A hydrogen in a gas containing hydrogen and hydrocarbon, characterized in that a platinum group element is supported on a carrier obtained by coating a heat-resistant inorganic compound with niobium oxide and / or tantalum oxide. A catalyst for catalytic oxidation of oxygen with oxygen. 2. The catalyst according to claim 1, wherein the heat-resistant inorganic compound is selected from the group consisting of aluminum oxide, silicon oxide, titanium oxide, and zirconium oxide. 3. The catalyst according to claim 1, wherein the proportion of niobium oxide and / or tantalum oxide in the whole catalyst is 20 to 80% by weight. 4. The catalyst according to claim 1, wherein the support is coated with 20 to 80% by volume of niobium oxide and / or tantalum oxide. 5. The catalyst according to claim 1, wherein the proportion of the platinum group element in the whole catalyst is 0.001 to 10% by weight. 6. The catalyst according to claim 1, wherein the platinum group element is platinum or palladium. 7. A hydrogen and a hydrocarbon, wherein the catalyst according to claim 1 is contacted with a gas containing hydrogen, a hydrocarbon and oxygen to oxidize hydrogen in the gas. Method for oxidizing hydrogen in a gas containing. 8. The oxidation method according to claim 7, wherein a gas containing hydrocarbon, hydrogen and oxygen is contacted at 300 to 800 ° C. 9. A first step of producing a gas containing dehydrogenated hydrocarbon, unreacted raw material hydrocarbon, and hydrogen by contacting the raw material hydrocarbon with a dehydrogenation catalyst,
After mixing the gas generated in the first step with the oxygen-containing gas,
A second step of oxidizing hydrogen in a gas by bringing it into contact with the catalyst according to any one of claims 1 to 6, and a carbonization of raw material in the gas by bringing a gas produced in the second step into contact with a dehydrogenation catalyst. And a third step of dehydrogenating hydrogen, the method for dehydrogenating a hydrocarbon. 10. A first step of producing a gas containing styrene, ethylbenzene, and hydrogen by contacting ethylbenzene with a dehydrogenation catalyst; mixing the gas produced in the first step with an oxygen-containing gas; Items 1 to 6
A second step of oxidizing hydrogen in a gas by contacting it with the catalyst according to any one of 1 to 3, and dehydrogenating ethylbenzene in the gas to styrene by contacting the gas produced in the second step with a dehydrogenation catalyst. A method for dehydrogenating ethylbenzene, which comprises a third step.