Hydrogen station and hydrogen production method

Abstract

[Task] To avoid the use of open flames and suppress CO2 emissions when heating a heat medium used to input heat to a dehydrogenation reaction of a hydrogenated aromatic compound. [Solution] A hydrogen station 1 includes a dehydrogenation reactor 23 that produces hydrogen through a dehydrogenation reaction of a hydrogenated aromatic compound in the presence of a dehydrogenation catalyst; a heat supply device 26 that supplies heat to the dehydrogenation reactor using a heat medium heated by a fuel; and a PSA unit 33 that purifies the reaction product gas in the dehydrogenation reactor by using an adsorbent according to a pressure swing adsorption method, wherein a purge gas containing hydrogen is supplied to the PSA unit for regeneration of the adsorbent, the heat supply device includes a storage tank 27 for storing the heat medium and a catalytic combustion tube 28, the catalytic combustion tube being disposed within the storage tank so as to catalytically combust the fuel in the presence of a combustion catalyst, and the catalytic combustion tube being supplied with purge gas exhausted from the PSA unit together with air as fuel.

Description

Technical Field

[0001] The present invention relates to a hydrogen station and a hydrogen production method for supplying hydrogen to mobile bodies equipped with fuel cells, such as fuel cell vehicles (FCVs), fuel cell forklifts, and the like. Background Art

[0002] According to the basic hydrogen strategy of the Japanese government, hydrogen stations for filling mobile bodies such as fuel cell vehicles equipped with fuel cells with hydrogen are being prepared. Currently, hydrogen stations for FCVs are in operation at about 110 locations, with the goal of deploying hydrogen stations at 900 locations by 2030, which are concentrated in four major metropolitan areas. It is expected that eventually, hydrogen stations will become necessary at about 15,000 locations, similar to current gas stations. After 2030, it will be necessary to promote hydrogen stations not only in the four major metropolitan areas, but also nationwide, including remote islands. Currently, hydrogen stations put into practical use use compressed hydrogen or liquid hydrogen to store and transport hydrogen.

[0003] On the other hand, there is an organic chemical hydride method as a method for storing / transporting hydrogen (see non-patent documents 1 and 2). The organic chemical hydride method (OCH method) is a method in which hydrogen undergoes a hydrogenation reaction with an aromatic compound such as toluene (TOL) and is converted into a saturated cyclic compound (hydrogenated aromatic compound), such as methylcyclohexane (MCH) containing hydrogen in its molecule, thereby achieving "storage" and "transportation" in a liquid state at room temperature and pressure, and taking out the necessary amount of hydrogen by dehydrogenation of the saturated cyclic compound for use at the place of use. That is, the OCH method includes a hydrogenation reaction (hydrogen storage reaction) in which hydrogen and TOL react and a dehydrogenation reaction (hydrogen production reaction) in which hydrogen is generated from MCH and TOL is recovered. For example, the TOL generated after taking out the hydrogen can be recovered and repeatedly used as a container (carrier) for hydrogen.

[0004] The dehydrogenation reaction of producing hydrogen from saturated cyclic compounds after transportation is an endothermic reaction, so it is necessary to input heat from the outside. Thus, in the dehydrogenation reaction, a method is adopted in which a heated liquid heat medium such as hot oil is circulated outside a reaction tube filled with a dehydrogenation catalyst to introduce the necessary heat to maintain a predetermined reaction temperature condition (for example, a reaction temperature of 300 to 400°C). Here, as a method for heating hot oil, it is conceivable to use a flame generated by the combustion of fuel in a heating furnace to heat the pipe in which the hot oil flows by an open flame (see patent document 1). However, for safety reasons, it is preferred to avoid the use of open flames in hydrogen stations where flammable hydrogen is handled as much as possible.

[0005] Furthermore, if fossil fuels such as natural gas or kerosene are used as fuel for heating the hot oil, the carbon content in the fuel will be emitted as CO2, thus reducing the significance of using hydrogen. Furthermore, an ignition source is essential for fuel combustion, so there is a problem that the risk of ignition sources cannot be avoided simply by avoiding the use of the furnace burner.

[0006] Prior art literature

[0007] Patent Literature

[0008] Non-patent document 1: OKADA Yoshimi, Energy / Natural Resources, Vol. 33, No. 3, 168 (2018)

[0009] Non-Patent Document 2: OKADA Yoshimi, Bulletin of The High Pressure Gas Safety Institute of TOKYO, August 2019 and September 2019

[0010] Patent Document 1: JP2015-182919A Summary of the Invention

[0011] The task to be accomplished by the present invention

[0012] Against this background, the present inventors have conducted extensive research on a method for avoiding the use of an open flame and suppressing carbon dioxide emissions when inputting heat using a heated heat medium to a dehydrogenation reaction of a hydrogenated aromatic compound performed in a hydrogen station.

[0013] As a result, the present inventors have discovered that it is possible to heat a heat medium using the heat of combustion without generating a flame by purifying the reaction product gas containing hydrogen obtained by the dehydrogenation reaction using a PSA device using the PSA method (pressure swing adsorption method) and catalytically burning a purge gas (containing a high concentration of hydrogen) used to regenerate the column (adsorption tower) of the PSA device (i.e., to remove impurities adsorbed on the adsorbent contained in the column). Thus, it is possible to suppress carbon dioxide emissions from hydrogen stations while avoiding the use of open flames or the like that could become ignition sources within the hydrogen station. Furthermore, the present inventors have discovered that it is preferable to use a highly active platinum catalyst in combination as a combustion catalyst for catalytic combustion of the purge gas, so that the purge gas can spontaneously ignite even in cold regions.

[0014] Therefore, an object of the present invention is to provide a hydrogen station and a hydrogen production method, which can avoid the use of open flames and suppress CO2 emissions when heating the heat medium when using a heated heat medium to input heat to the dehydrogenation reaction of hydrogenated aromatic compounds.

[0015] Means of completing the task

[0016] One aspect of the present invention is a hydrogen station (1), which includes: a dehydrogenation reactor (23) that produces hydrogen by a dehydrogenation reaction of a hydrogenated aromatic compound in the presence of a dehydrogenation catalyst; a heat supply device (26) that supplies heat to the dehydrogenation reactor via a heat medium heated by a fuel; and a PSA device (33) that purifies the reaction product gas containing hydrogen produced by the dehydrogenation reactor by using an adsorbent according to a pressure swing adsorption method, wherein the PSA device is supplied with a purge gas containing hydrogen for regenerating the adsorbent, the heat supply device includes a storage tank (27) for storing the heat medium and a catalytic combustion tube (28), the catalytic combustion tube being arranged in the storage tank so as to catalytically combust the fuel in the presence of a combustion catalyst, and the catalytic combustion tube being supplied with a purge gas and air discharged from the PSA device as fuel.

[0017] According to this aspect, when a heated heat medium is used to input heat to the dehydrogenation reaction of the hydrogenated aromatic compound, the heat medium is heated by catalytically burning the purge gas used during the regeneration of the adsorbent in the PSA unit, thereby avoiding the use of open flames when heating the heat medium and suppressing CO2 emissions.

[0018] In the above aspect, preferably, the dehydrogenation catalyst comprises a platinum-supported alumina catalyst, and the platinum-supported alumina catalyst comprises: an alumina carrier; and platinum supported on the alumina carrier, wherein the alumina carrier comprises a surface area of ​​200m 2 / g or more, pore volume 0.50m 3 / g or more and an average pore size of 60 to range of gamma-alumina supports, wherein the pore size is the average pore size The pores in the range of 0.5 to 1.0 % by weight account for 60% or more of the total pore volume, 0.1 to 1.5 wt% of the platinum particles are supported on the γ-alumina support in terms of elemental platinum (Pt), and 70% or more of the platinum particles have 8 to 1.5 wt% by weight, as directly observed using a transmission electron microscope. size.

[0019] According to this aspect, a platinum-supported alumina catalyst comprising platinum particles having an appropriately set particle diameter (platinum having an appropriately controlled particle distribution) is used in the dehydrogenation reaction of hydrogenated aromatic compounds, and therefore, due to the improvement in catalyst life, the dehydrogenation reaction of hydrogenated aromatic compounds (i.e., hydrogen production) can be carried out stably.

[0020] In the above aspect, preferably, the combustion catalyst includes a catalyst having the same structure as the dehydrogenation catalyst.

[0021] According to this aspect, by using a relatively highly active catalyst having the same structure as the dehydrogenation catalyst (e.g., a platinum-supported alumina catalyst) as a combustion catalyst, heating of the heat medium can be advantageously performed. In particular, by using a platinum-supported alumina catalyst comprising platinum particles having a suitably set particle diameter (platinum having a suitably controlled particle distribution) in catalytic combustion, heating of the heat medium can be stably performed due to improved catalyst life.

[0022] In the above aspect, preferably, the combustion catalyst is installed in the fuel inlet part (28A) of the catalytic combustion tube for introducing the fuel, and the combustion catalyst includes a first catalyst and a second catalyst, the first catalyst has the same structure as the dehydrogenation catalyst, and the second catalyst has a different structure from the first catalyst and is installed in a part downstream of the fuel inlet part of the catalytic combustion tube.

[0023] According to this aspect, the fuel in the fuel inlet portion of the catalytic combustion tube can be spontaneously ignited by the first catalyst in a favorable manner. Similarly, since a portion downstream of the fuel inlet portion of the catalytic combustion tube is filled with a second catalyst having a structure different from that of the first catalyst, it is possible to reduce catalyst costs by using a catalyst (universal catalyst) that is cheaper than the first catalyst as the second catalyst.

[0024] In the above aspect, preferably, the heat medium is hot oil.

[0025] According to this aspect, it is possible to easily supply heat to the dehydrogenation reactor using a suitable heat medium.

[0026] In the above aspect, preferably, the catalytic combustion tube is supplied with air in a divided manner at a plurality of different locations.

[0027] According to this aspect, the catalytic combustion reaction can be made to proceed uniformly over a wide area of ​​the catalytic combustion tube, thereby suppressing the occurrence of hot spots.

[0028] In the above aspect, preferably, the hydrogen station further includes: a distributor (15) which supplies the hydrogen purified by the PSA device to a mobile body equipped with a fuel cell; a precooler (17) which cools the hydrogen supplied by the distributor by using a coolant; and a gas-liquid separator (31) which separates the reaction product gas into gas and liquid, wherein in the gas-liquid separator, the reaction product gas is cooled by the coolant supplied by the precooler.

[0029] According to this aspect, it is possible to cool the reaction product gas to a temperature lower than the atmospheric temperature by using the coolant of the precooler, and thus, the aromatic compounds (e.g., toluene) and unreacted raw materials (e.g., cyclohexane) contained in the reaction product gas can be advantageously condensed in the gas-liquid separator.

[0030] In the above aspect, preferably, in the dehydrogenation reaction, hydrogen and toluene are produced by dehydrogenating cyclohexane as a hydrogenated aromatic compound, and the hydrogen station further includes: a first tank (4) for storing cyclohexane; and a second tank (6) for storing toluene, and the first tank and the second tank are respectively placed underground.

[0031] According to this aspect, the freedom of using the space above the ground in the hydrogen station is increased, and the hydrogen station can be made compact. In this case, underground tanks used to store gasoline or the like in existing gas stations can be used to (reuse) store cyclohexane and / or toluene.

[0032] In the above aspect, preferably, at least one of the gaseous-phase gas in the first tank and the gaseous-phase gas in the second tank is supplied to the catalytic combustion tube as fuel together with the purge gas exhausted from the PSA device.

[0033] According to this aspect, hydrogen that may be contained in at least one of the gas phase in the first tank and the gas phase in the second tank can be safely removed.

[0034] In the above aspect, preferably, at least one of the gaseous phase gas in the first tank and the gaseous phase gas in the second tank is introduced into the fuel inlet portion (28A) of the catalytic combustion tube for introducing fuel together with air.

[0035] According to this aspect, hydrogen contained in at least one of the gas phase in the first tank and the gas phase in the second tank can be used as fuel for ignition in the catalytic combustion tube.

[0036] In the above aspect, preferably, the catalytic combustion tube is a coil filled with a combustion catalyst.

[0037] According to this aspect, the heat medium can be heated uniformly by catalytic combustion.

[0038] In the above aspect, preferably, the hydrogenated aromatic compound is one member or a mixture of two or more members selected from the following: hydrides of monocyclic aromatic compounds, hydrides of bicyclic aromatic compounds and hydrides of compounds having three or more aromatic rings.

[0039] According to this aspect, the dehydrogenation reaction can be advantageously carried out by using a suitable hydrogenated aromatic compound.

[0040] In the above aspect, preferably, the hydrogenated aromatic compound is one member selected from the group consisting of methylcyclohexane, cyclohexane, trimethylcyclohexane, decalin, and dibenzotriol, or a mixture of two or more members selected from the group consisting of methylcyclohexane, cyclohexane, trimethylcyclohexane, decalin, and dibenzotriol.

[0041] According to this aspect, the dehydrogenation reaction can be advantageously carried out by using a suitable hydrogenated aromatic compound.

[0042] One aspect of the present invention is a method for producing hydrogen in a hydrogen station, comprising: producing hydrogen through a dehydrogenation reaction of a hydrogenated aromatic compound in the presence of a dehydrogenation catalyst; supplying heat to the dehydrogenation reaction via a heat medium heated using a fuel; and purifying a reaction product gas containing hydrogen produced by the dehydrogenation reaction by using an adsorbent according to a pressure swing adsorption method, wherein a purge gas containing hydrogen is used for regeneration of the adsorbent, and the purge gas for adsorbent regeneration is supplied as a fuel together with air in heating the heat medium.

[0043] According to this aspect, when a heated heat medium is used to input heat to the dehydrogenation reaction of the hydrogenated aromatic compound, the heat medium is heated by catalytic combustion of a purge gas that has been used for regeneration of the adsorbent according to the pressure swing adsorption method, thereby avoiding the use of an open flame in the heating of the heat medium and suppressing CO2 emissions.

[0044] Hydrogen has been attracting attention as a clean secondary energy source since the 1970s. In Japan, the Sunshine Project (1974-1992), the Moonlight Project (1978-1992), and the New Sunshine Project (1993-2001) all promoted research and development of hydrogen production technologies and fuel cells. Regarding large-scale hydrogen storage and transportation, the WE-NET project (1992-2002) initiated the development of liquefied hydrogen methods. Meanwhile, the organic chemical hydride (OCH) process has a long history, dating back to the EuroQuebec Project, an international research and development project conducted in the 1980s by the Quebec government of Canada and 12 European countries. This project proposed producing hydrogen through water electrolysis using abundant excess hydropower in Quebec and transporting it across the Atlantic for use in Europe. Liquid hydrogen was discussed as the first candidate for hydrogen transportation, followed by liquid ammonia and the OCH process. At the time, the organic chemical hydride process was known as the MCH process. The European Quebec project lasted about 10 years, until 1992, but ended without any of the methods being implemented, and since then, the technology for storing and transporting hydrogen on a large scale has not been implemented.

[0045] In Japan, the development of the liquid hydrogen method was promoted by the WE-NET project, which ran from 1992 to 2002, while research on the OCH method was primarily driven by Japanese universities. The applicant began developing a dehydrogenation catalyst in 2002 and presented its first academic presentation at the 2004 World Hydrogen Conference in Yokohama. Around this time, examples of corporate R&D began to be published. Currently, the only large-scale hydrogen storage and transportation technologies that have achieved demonstration-level R&D are the liquid hydrogen method and the applicant's proposed OCH method.

[0046] The OCH method involves hydrogenating aromatic compounds such as toluene (TOL) to form saturated cyclic compounds containing hydrogen, such as methylcyclohexane (MCH). This allows for storage and transportation of hydrogen in a liquid state at room temperature and pressure. The necessary amount of hydrogen is then removed through a dehydrogenation reaction and used at the point of use. This method involves a hydrogenation reaction (hydrogen storage reaction) in which hydrogen reacts with TOL, and a dehydrogenation reaction (hydrogen production reaction) in which hydrogen is generated from MCH and recovered. The TOL generated after hydrogen extraction is recovered and reused as a hydrogen container (carrier).

[0047] Because hydrogen is an explosive gas, its large-scale storage and transportation present a potentially high risk. The OCH method utilizes hydrogen stored and transported within the molecules of MCH, a component of gasoline and diesel fuel that is liquid at room temperature and pressure. Therefore, this method is theoretically highly safe. Specifically, even if a fire occurs in the tanks and reactors of an OCH system, it would be similar to a conventional refinery fire, and the likelihood of significant damage to surrounding areas is considered extremely low. The understanding that "accidents will eventually occur" is crucial to safety measures, which is why safety is fundamentally required.

[0048] Using the OCH method, approximately 530L of hydrogen can be stored in 1L of liquid MCH. In order to actually reduce the volume of hydrogen to 1 / 500 or less, it is necessary to compress the hydrogen to 500 standard atmospheres or more, or to cool the hydrogen to -253°C or below to make it 1 / 800 of the volume of liquid hydrogen, but according to the OCH method, by using chemical reactions, the volume can be reduced to 1 / 500 at room temperature and pressure. In addition, since TOL and MCH are liquid in a wide temperature range of -95°C to 101°C, they can be handled as liquids (such as water) in any environment on Earth. In order to establish a large-scale supply chain, it is necessary to purchase hundreds of thousands of tons of TOL, but TOL is a fuel base material that is contained in high-octane gasoline at a ratio of 10% by weight or more, and is also a common chemical product with 20 million tons produced worldwide each year. In addition, it is also widely used as an industrial solvent. Therefore, TOL can be easily purchased in large quantities.

[0049] In summary, the main feature of this method is that it can reduce the potential risks associated with large-scale storage and transportation of hydrogen to the risk level associated with conventional gasoline storage and transportation (i.e., it is a highly safe method), which is the first reason why applicants are interested in the OCH method. In addition, the storage of TOL and MCH in large tanks and their transportation by chemical tankers and chemical trucks are both long-standing practices as chemical products. With the current trend of vehicle electrification, the demand for gasoline, diesel, etc. as automotive fuels is expected to decrease, so the fact that existing infrastructure (such as storage tanks) can be converted to use in the OCH method is a significant advantage.

[0050] Furthermore, if hydrogen is used as a power generation fuel on a large scale in the future, hydrogen fuel reserves will become as essential as current oil reserves. Since TOL and MCH undergo no chemical changes even when stored in large quantities for long periods of time, and since there is no additional energy consumption or loss associated with long-term storage, storing MCH in tanks at existing oil reserves can convert these reserves into hydrogen energy reserves.

[0051] The applicant focused on the OCH process, which offers superior safety and cost advantages due to its ability to leverage existing infrastructure. In 2002, the applicant began developing a novel dehydrogenation catalyst, a key to its practical implementation, and successfully developed the world's first novel dehydrogenation catalyst suitable for industrial application in the OCH process. Subsequently, in 2013, to establish the technology for the entire system, the applicant used the developed dehydrogenation catalyst in the dehydrogenation process and combined it with the TOL hydrogenation process for hydrogen storage. This resulted in a demonstration facility that continuously and repeatedly stored and produced hydrogen at the same site. From April 2013 to November 2014, the demonstration ran for approximately 10,000 hours, confirming the ability to stably maintain the designed high performance, thus completing the technology establishment.

[0052] Subsequently, as the final stage of development, as a project of NEDO (New Energy and Industrial Technology Development Organization), the world's first international hydrogen supply chain demonstration was carried out in 2020, in which approximately 200 tons of hydrogen were actually transported from Brunei in Southeast Asia to Kawasaki Kaihin in Japan using this system in accordance with the OCH method, and a demonstration of hydrogen transportation of 100 tons or more per year using this system was completed.

[0053] JP4652695B2 (hereinafter referred to as Patent Document 3) and JP4142733B2 (hereinafter referred to as Patent Document 4) disclose dehydrogenation catalysts used in the dehydrogenation reaction of the OCH process described above. Several specific methods for dehydrogenation in this method have been proposed worldwide, but in order to put facilities that provide fuel for power generation into practical use on a large scale, not only high production yields but also sufficient catalyst life are required. Therefore, in hydrogen stations and hydrogen production methods using the OCH process of the present invention, it is also preferred to use such dehydrogenation catalysts with long lifespans and excellent economic performance.

[0054] Patent document 3 discloses a platinum-supported alumina catalyst, wherein platinum is supported on a porous γ-alumina carrier having a surface area of ​​150 m 2 / g or higher, pore volume 0.55cm 3 / g or more, and an average pore size of 90 to Aperture between 90 and The pores account for 60% of the total pore volume. Similarly, Patent Document 4 discloses a uniform platinum-supported alumina catalyst in which sulfur is contained in the alumina carrier, thereby making the dispersion pattern of the supported platinum uniform and suppressing the decomposition reaction, thereby improving the catalyst life. Please note that all documents mentioned in this specification, including Patent Document 3 and Patent Document 4, constitute part of this specification, and their detailed descriptions are omitted.

[0055] Here, the dehydrogenation catalysts disclosed in Patent Documents 3 and 4 are characterized in that the particle size of the platinum particles supported on the alumina carrier is significantly smaller than that of conventional platinum catalysts. The average particle size of the platinum particles of a general platinum-supported alumina catalyst is In the past, the OCH process could not be put into practice because the dehydrogenation catalyst had not yet been developed, but the applicant found that by highly dispersing the platinum particles into about The catalytic activity of the platinum-loaded alumina catalyst was significantly improved by the small particles. Based on this, the applicant established the technology of this method and completed the world's first demonstration of an international hydrogen supply chain based on this method before the end of 2020.

[0056] The platinum particle size of the dehydrogenation catalyst disclosed in Patent Documents 3 and 4 is or smaller, and most platinum particles are As mentioned above, the minimum platinum particle size of the existing platinum-supported alumina catalyst is about And the average particle size is In the hydrogen station based on the OCH method according to the present invention, it is preferred to use platinum particles with an average particle size of or smaller dehydrogenation catalysts, including the dehydrogenation catalysts disclosed in Patent Document 3 and Patent Document 4.

[0057] Regarding the catalysts that can be used as dehydrogenation catalysts in the present invention, homogeneous catalysts are effective when the feedstock diffuses sufficiently into the catalyst; eggshell catalysts are effective when diffusion into the catalyst is limited and inadequate. Therefore, both types of catalysts can be used appropriately depending on the diffusion state within the reaction area. Furthermore, even for the same reaction, the diffusion state of the feedstock into the catalyst varies depending on the location within the dehydrogenation reactor. Near the outlet, where the reaction is already underway, the feedstock concentration is low, potentially limiting diffusion into the catalyst. In such cases, both homogeneous and eggshell catalysts can be used in the reactor.

[0058] Generally speaking, the degree of diffusion of feedstock into the catalyst is expressed by the catalyst efficiency factor, which can be controlled by varying the size and shape of the catalyst particles. Therefore, for both uniform and eggshell catalysts, platinum-alumina catalysts with varying catalyst efficiency factors can be produced by varying the size and shape of the catalyst particles.

[0059] In the platinum-supported alumina catalyst that can be used as the dehydrogenation catalyst of the present invention, it is preferred that the pore size of the platinum-supported alumina carrier be controlled as uniformly as possible so that the pore distribution thereof is sharp. Specifically, a γ-alumina carrier having a surface area of ​​200 m 2 / g or more, with a pore volume of 0.5m 3 / g or more, and an average pore size of 60 to The average pore size Pores within this range account for 60% or more of the total pore volume. If the surface area is less than 200m 2 / g, the activity of the catalyst after formation is insufficient; if the pore volume is less than 0.5m 3 / g, it is difficult to uniformly load the active metal components; if the average pore size is smaller than The pore volume becomes smaller and the surface area becomes larger. Conversely, if the average pore diameter is larger than The surface area becomes smaller and the pore volume becomes larger. When all these relationships are taken into account, the average pore size is 60 to is appropriate. Similarly, if the pore size is within the average pore size If the proportion of pores within the range is less than 60%, the effectiveness of the present invention on catalyst performance is reduced. By making the pore size uniform, the alumina support has a uniform pore size throughout the entire powder and its molded body. As a result, the process of dispersing and supporting platinum on the alumina support, as well as the process of dispersing and supporting platinum across the entire alumina support in accordance with the distribution of sulfur, can be appropriately performed.

[0060] The hydrogen station according to the present invention includes a dehydrogenation reactor that generates hydrogen through a dehydrogenation reaction of a hydrogenated aromatic compound (e.g., methylcyclohexane) serving as a hydrogen carrier, and a PSA (pressure swing adsorption) unit for purifying the generated hydrogen to a purity that can be supplied to fuel cell vehicles (FCVs), etc. Similarly, a system for recovering TOL generated by the dehydrogenation reaction and unreacted MCH can be installed in the hydrogen station.

[0061] As the dehydrogenation reactor of the present invention, a multi-tubular fixed-bed reactor having a structure similar to a heat exchanger is suitable. Specifically, in the dehydrogenation reactor, catalytic reactor tubes filled with a dehydrogenation catalyst are arranged in parallel within the reactor, and MCH gas heated to the reaction temperature is supplied to the catalytic reactor tubes, while liquid heat medium is supplied to the outside of the catalytic reactor tubes, thereby supplying the heat required for the endothermic dehydrogenation reaction and maintaining the reaction temperature.

[0062] In the present invention, as a heat medium for supplying heat to the catalytic reactor tubes, a liquid with a large heat capacity is preferred. When gas is used as a heat medium, there is a disadvantage that, due to the small heat capacity, a large heat transfer area is required, and this requires an increase in the surface area of ​​the catalytic reactor tubes, thereby making the reactor larger than required. As a liquid heat medium, existing molten salts or hot oils can be used. However, please note that molten salts generally contain oxygen atoms in their molecules, and if, in unlikely circumstances such as an unexpected earthquake, the MCH gas in the reaction tubes comes into contact with the molten salts, it is possible to catch fire even in the reaction temperature range of 300 to 400°C. Therefore, it is highly safe and preferred to use hot oil that never ignites as a heat medium because it will not cause a fire in principle.

[0063] In the present invention, commercially available ordinary oil for heat medium can be used as the hot oil. Since the hot oil is a hydrocarbon with a large molecular weight, it may be thermally decomposed at approximately 400°C and lose its heat. Therefore, it is preferable to use a hot oil that can minimize thermal decomposition losses as the hot oil for supplying heat to the catalytic reactor tubes.

[0064] In the present invention, hot oil can be stored in a tank equipped with catalytic combustion tubes (catalytic combustion coils) filled with a combustion catalyst, thereby heating the hot oil by transferring heat generated by catalytic combustion from the catalytic combustion tubes to the hot oil. Because hot oil is not corrosive, inexpensive steel can be used as the metal material forming the catalytic combustion tubes.

[0065] In the present invention, an existing combustion catalyst known to be used in catalytic combustion can be used as the combustion catalyst installed in the catalytic combustion tube. However, please note that since the combustion catalyst needs to be able to reliably cause the fuel to spontaneously ignite, and hydrogenation stations in cold regions require spontaneous ignition below the freezing point of water, it is preferred to use a highly active platinum catalyst as the combustion catalyst. On the other hand, in the present invention, the dehydrogenation catalyst that can be used in the dehydrogenation reactor has a very high activity, which can reduce the dehydrogenation temperature required by the existing dehydrogenation catalyst by 100°C or more. Therefore, in the present invention, in addition to the existing combustion catalyst, a catalyst that can be used as a dehydrogenation catalyst can also be used as a high-performance combustion catalyst, so that the fuel can be spontaneously ignited in a reliable manner. Similarly, considering that if the catalyst used as a dehydrogenation catalyst is used as the entire combustion catalyst, it is possible to make the fuel spontaneously ignite in any cold region on the earth.

[0066] In the present invention, in addition to the platinum-loaded alumina catalysts disclosed in the above-mentioned Patent Documents 3 and 4, the catalysts that can be used as dehydrogenation catalysts and combustion catalysts include new platinum-loaded alumina catalysts, in which the particle size of the platinum particles supported on the carrier is set more appropriately (the distribution of the platinum particles is appropriately controlled) by direct observation using a transmission electron microscope, as described below.

[0067] In the present invention, existing combustion catalysts that can be used as the combustion catalyst (the second catalyst described later) include those having at least one noble metal such as platinum, palladium, or iridium supported on a carrier, and metal-supported catalysts having at least one metal such as nickel, cobalt, molybdenum, chromium, vanadium, or molybdenum supported on a carrier. Noble metals are expensive but have high ignitability, while non-noble metals have low ignitability but are low-cost.

[0068] In the present invention, the PSA device has a plurality of columns (adsorption tanks) filled with adsorbents, and the reaction product gas is supplied to these columns so that impurities are adsorbed and removed. In the PSA device, for example, the reaction product gas is supplied to one of the two columns so that the impurities are adsorbed by the adsorbent and hydrogen is taken out. The adsorption capacity of the adsorbent decreases over time, so the supply end point of the reaction product gas is switched to another column at an appropriate time. The adsorbent is regenerated by desorbing the adsorbed impurities by reducing the pressure in the column, and product hydrogen that does not include impurities is supplied to purge the impurities. The PSA method changes the pressure to desorb impurities and is therefore called a pressure swing adsorption method. The purge gas used in the regeneration operation of the PSA device uses product hydrogen, so the purge gas contains a high concentration of hydrogen after removing the impurities.

[0069] In the present invention, the purge gas discharged from the PSA device (i.e., after purging impurities) can be used as fuel supplied to the catalytic combustion coil. The purge gas for the PSA device is supplied by a column in a regeneration mode (the adsorbent is being regenerated) of a plurality of columns. Here, it is preferred that the columns to be regenerated in the PSA device are switched in sequence so that the purge gas as fuel is continuously supplied (exhausted) without interruption, and thus the regeneration process is performed without interruption. However, please note that a hydrogen container (hydrogen holder) for storing pressurized purge gas can be provided as needed. For example, by supplying all the purge gas discharged by the PSA device to a hydrogen container so that the purge gas is temporarily stored therein, the purge gas can be stably supplied to the catalytic combustion coil by the hydrogen container, and in addition, the entire amount of purge gas discharged by the PSA device can be used without waste.

[0070] In the present invention, a gas-liquid separator can be installed between the dehydrogenation reactor and the PSA unit as a system for recovering the TOL and unreacted MCH produced by the dehydrogenation reaction. In the gas-liquid separator, the reaction product gas removed from the dehydrogenation reactor is cooled to 100°C or lower, allowing the liquid components (including TOL and MCH condensed into liquid) to be recovered. Furthermore, in the gas-liquid separator according to the present invention, the reaction product gas is preferably cooled to 10°C or lower to improve the recovery rate of TOL, MCH, etc.

[0071] Recovering TOL, MCH, and the like from the reaction product gas as much as possible before introducing it to the PSA unit as described above not only reduces toluene losses resulting from conversion to unrecovered amounts but also helps reduce the processing load of the PSA unit. Similarly, since an increase in the amount of impurities removed by adsorption in the PSA unit can lead to an increase in CO emissions generated during catalytic combustion, recovering TOL, MCH, and the like helps reduce this.

[0072] When cooling the reaction product gas containing TOL and MCH, it can generally be naturally cooled to about 50°C without requiring special energy consumption, and when it is further cooled to approximately atmospheric temperature, cooling water can be used. However, cooling the reaction product gas to 10°C or lower is difficult, especially in summer or when the temperature is high, so it is necessary to re-cool it. In a hydrogen station, 5 kg of hydrogen can be pumped into the hydrogen tank of the FCV in 3 minutes, but in order to prevent the temperature of the FCV hydrogen tank from rising to 80°C or higher due to the frictional heat generated at this time, the hydrogen is pre-cooled to about -40°C by a pre-cooler. Therefore, in the present invention, the reaction product gas containing TOL and MCH can be cooled by using the cold capacity of the pre-cooler.

[0073] Hydrogen stations that perform dehydrogenation reactions require tanks for storing MCH, the raw material for the dehydrogenation reaction, and TOL, which is produced during the dehydrogenation reaction. Existing gas stations are equipped with underground tanks for gasoline, kerosene, fuel oil, and the like. MCH and TOL are classified as Class 4 hazardous materials and Class 1 petroleum, and are therefore classified as hazardous materials like gasoline and kerosene. Similarly, MCH and TOL are compounds with 7 carbon atoms and have lower vapor pressure and less volatility than gasoline, which contains hydrocarbon components with 4 or more carbon atoms.

[0074] On the other hand, MCH and TOL stored in hydrogen stations contain hydrogen due to solubility, but the amount is very small, and it is generally unlikely that the gaseous components in the underground tanks will reach a concentration equal to or higher than the explosion limit. However, it is preferable to provide a system for removing dissolved hydrogen from the underground tanks.

[0075] To remove dissolved hydrogen, the present invention utilizes catalytic combustion to remove the gaseous components from the tank storing MCH (MCH tank) and the tank storing TOL (TOL tank). The gas (tank gas) obtained by discharging the gaseous components from the tank storing MCH (MCH tank) and the tank storing TOL (TOL tank) is subjected to catalytic combustion. In this case, since the tank gas contains not only hydrogen but also MCH and TOL in amounts corresponding to their vapor pressures, releasing them into the atmosphere is undesirable, and thus offers the advantage of being able to process them through catalytic combustion. Note that, if the increased cost is acceptable, it is conceivable to introduce an inert gas such as nitrogen into the liquid in these tanks to remove the gaseous components.

[0076] Air can be used as the oxygen required for catalytic combustion of the tank gas. Similarly, catalytic combustion of the tank gas can be performed separately from the purge gas exhausted from the PSA unit using a similar catalytic combustion coil. However, please note that if the tank gas is mixed with the purge gas and catalytically combusted, there is an advantage in that the hydrogen in the tank can be handled with a simple configuration. The tank gas, along with air, is introduced to the inlet portion of the catalytic combustion coil filled with a platinum-supported alumina catalyst, allowing for catalytic combustion of the tank gas through spontaneous ignition.

[0077] The hydrogenated aromatic compound that can be used in the dehydrogenation reaction according to the present invention is not limited to MCH, and is preferably one member or a mixture of two or more members selected from the following: hydrides of monocyclic aromatic compounds, such as cyclohexane, dimethylmethylcyclohexane, trimethylcyclohexane, etc.; hydrides of bicyclic aromatic compounds, such as tetralin, decalin, methyldecalin, biphenyl, diphenylmethyl, etc.; and hydrides of compounds having 3 or more aromatic rings, such as dibenzotriol, tetradecahydroanthracene, etc.

[0078] Effects of the present invention

[0079] According to the aforementioned configuration, in the hydrogen station and hydrogen production method, when heat is input to the dehydrogenation reaction of the hydrogenated aromatic compound using a heated heat medium, it is possible to avoid using an open flame and suppress CO2 emissions when heating the heat medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 This is a diagram of the configuration of a conventional hydrogen station;

[0081] Figure 2 is a configuration diagram of a hydrogen station according to a first embodiment;

[0082] Figure 3 is a diagram showing a detailed configuration of a dehydrogenation unit according to a first embodiment;

[0083] Figure 4 is a configuration diagram of a hydrogen station according to a second embodiment;

[0084] Figure 5 are explanatory diagrams showing (A) a transmission electron micrograph of the catalyst in the 2000s and (B) a transmission electron micrograph of the catalyst in recent years; and

[0085] Figure 6 This figure is an explanatory diagram regarding the measurement of the particle size of platinum particles based on transmission electron micrographs. DETAILED DESCRIPTION

[0086] Hereinafter, a hydrogen station and a method of producing hydrogen according to embodiments will be described with reference to the accompanying drawings.

[0087] Existing hydrogen stations are roughly divided into on-site and off-site types. On-site type is a general term for hydrogen stations that produce hydrogen in the hydrogen station. Off-site type is a general term for hydrogen stations that directly transport high-purity hydrogen as compressed hydrogen or liquid hydrogen to the hydrogen station and use the hydrogen stored therein after pressurization. The hydrogen station according to the present invention, which will be described in detail later, produces hydrogen through an on-site dehydrogenation reaction, which is similar to an on-site reforming hydrogen station, and therefore, it is considered to be classified as an on-site type. However, at the current point in time, the hydrogen station according to the present invention is still in the research and development stage, and there is no actual hydrogen station, so it is not yet certain which type it will ultimately be classified into.

[0088] (Conventional Technology)

[0089] like Figure 1 As shown in , a conventional on-site hydrogen station 101 includes a hydrogen production device 103 required for hydrogen production. As the hydrogen production device 103, a water electrolysis device or a reforming type hydrogen production device is used. In the reforming type hydrogen production device, fossil fuels such as city gas are steam reformed and thereafter converted into hydrogen and carbon dioxide through a shift reaction. The water electrolysis device uses electrical energy to electrolyze water, so there is a cost issue; and the reforming type hydrogen production device produces carbon dioxide, so they are not mainstream hydrogen stations that are actually operated as commercial stations. The current situation is that off-site hydrogen stations based on the compressed hydrogen method or the liquid hydrogen method are used as commercial stations, and there are about 50 locations in operation for each method.

[0090] The hydrogen produced by the hydrogen production device 103 is sent to the hydrogen storage tank 105 and temporarily stored there. Thereafter, the hydrogen stored in the hydrogen storage tank 105 is sent to the compressor 109, and after the pressure therein is increased to about 800 standard atmospheres, the hydrogen is sent to the accumulator 111 and stored there as product hydrogen.

[0091] The product hydrogen stored in the accumulator 111 is supplied to a fuel cell vehicle (FCV) 113 using the hydrogen station 101 via a dispenser 115 .

[0092] For example, pumping hydrogen into the onboard tank of the FCV 113 requires pumping 5 kg of hydrogen in 3 minutes, and due to the frictional heat generated when pumping hydrogen at this rate, the temperature in the onboard tank of the FCV 113 rises. Therefore, in order to maintain the temperature in the onboard tank at 80°C or lower, the hydrogen supplied from the dispenser 115 is supplied to the FCV 113 in a state cooled to approximately -40°C by the coolant supplied by the precooler 117.

[0093] (First embodiment)

[0094] Next, we will refer to Figure 2 and Figure 3 A hydrogen station 1 and a method for producing hydrogen therefrom according to a first embodiment of the present invention will be described.

[0095] like Figure 2 As shown in FIG, the hydrogen station 1 according to the first embodiment includes a dehydrogenation unit 3 that generates hydrogen through a dehydrogenation reaction of a hydroaromatic compound. As described in detail later, in the dehydrogenation unit 3, methylcyclohexane (MCH) is used as the hydroaromatic compound as a raw material, and due to the dehydrogenation reaction of MCH in the presence of a dehydrogenation catalyst, a reaction product gas (reaction product) containing hydrogen, toluene (TOL), etc. is generated. This reaction product gas contains unreacted MCH, etc.

[0096] MCH is stored in an MCH tank 4 and supplied to the dehydrogenation unit 3 via a raw material supply line L1. TOL is sent from the dehydrogenation unit 3 to a toluene tank 6 via a toluene discharge line L3 and stored therein. The supply of MCH to the MCH tank 4 and the recovery of TOL from the toluene tank 6 are both carried out by a chemical truck (not shown).

[0097] The MCH tank 4 and the toluene tank 6 are each placed at an appropriate location within the hydrogen station 1, preferably underground within the station 1. This increases the flexibility of the above-ground space within the hydrogen station 1 and allows the station 1 to be made more compact. In this case, the underground tanks used to store gasoline and the like at existing gas stations can be used to store MCH and TOL (i.e., reused as the MCH tank 4 and the toluene tank 6).

[0098] The hydrogen generated by the dehydrogenation unit 3 is sent to the compressor 9 via the hydrogen transport line L5. The hydrogen sent to the compressor 9 is purified in the dehydrogenation unit 3 to an extent that it can be used as product hydrogen.

[0099] and Figure 1, after the pressure in the compressor 9 is increased to about 800 standard atmospheres, the hydrogen is sent to the accumulator 11 via the hydrogen transport line L6. The hydrogen sent to the accumulator 11 is stored there as product hydrogen. The product hydrogen stored in the accumulator 11 is sent to the dispenser 15 via the hydrogen transport line L7, and from there is supplied to the fuel cell vehicle (FCV) 13 via the gas filling pipe L11. The hydrogen supplied by the dispenser 15 is sent to the FCV 13 in a state where it is cooled to about -40°C by the coolant supplied by the precooler 17. Note that the hydrogen station 1 can be used not only by the FCV 13, but also by any mobile body equipped with a fuel cell.

[0100] The coolant for cooling the hydrogen circulates in a first coolant circulation line L13 provided between the distributor 15 and the precooler 17, and exchanges heat with the hydrogen in a heat exchanger for cooling the hydrogen provided in the distributor 15. Alternatively, a configuration may be made such that the hydrogen from the distributor 15 is sent to the FCV 13 after passing through the heat exchanger for cooling the hydrogen provided in the precooler 17 (i.e., after exchanging heat with the coolant).

[0101] Next, we will refer to Figure 3 The detailed configuration of the dehydrogenation unit 3 is described.

[0102] In the dehydrogenation unit 3, MCH stored in the MCH tank 4 is supplied as a raw material to the dehydrogenation reactor 23 via a liquid pump 21 (a pump for transporting MCH) provided in the raw material supply line L1. A heat exchanger 25 is provided in the raw material supply line L1 for exchanging heat between the MCH supplied to the dehydrogenation unit 3 and the reaction product gas withdrawn from the dehydrogenation reactor 23. More specifically, the MCH flowing in the raw material supply line L1 is heated to a temperature close to the reaction temperature of the dehydrogenation reaction by exchanging heat with the reaction product gas flowing in the reaction product gas line L21 at the heat exchanger 25, and is then introduced into the upper portion of the dehydrogenation reactor 23 in a gaseous state.

[0103] The hydrogen station 1 is provided with a heat supply device 26, which supplies heat to the dehydrogenation reactor 23 via a heat medium heated by using fuel. The heat supply device 26 includes a storage tank 27 for storing the heat medium and a catalytic combustion coil 28 (catalytic combustion tube) arranged in the storage tank 27 and filled with a combustion catalyst. In the catalytic combustion coil 28, the fuel is catalytically combusted in the presence of the combustion catalyst, and the heat generated thereby is transferred from the catalytic combustion coil 28 to the heat medium in the storage tank 27, thereby heating the heat medium. The heated heat medium circulates in the heat medium circulation line L23 provided between the dehydrogenation reactor 23 and the heat supply device 26. Therefore, heat is supplied from the heat supply device 26 to the dehydrogenation reactor 23. As described in detail later, in the heat supply device 26, the purge gas discharged by the PSA device 33 (hereinafter referred to as the exhaust purge gas) is used as fuel.

[0104] The reaction product gas withdrawn from the dehydrogenation reactor 23 flows through the reaction product gas line L21 , and is introduced into the gas-liquid separator 31 after heat exchange with the MCH in the heat exchanger 25 .

[0105] The gas-liquid separator 31 has a known structure and cools the reaction product gas to separate it into a gaseous phase component and a liquid phase component. In this embodiment, the reaction product gas introduced into the gas-liquid separator 31 is naturally cooled to a temperature of 100°C or lower. In the gas-liquid separator 31, the TOL and MCH contained in the reaction product gas are condensed into a liquid, thereby forming the liquid phase component. The liquid phase component is extracted from the lower portion of the gas-liquid separator 31 and introduced into the toluene tank 6 via the toluene discharge line L3, where it is stored.

[0106] On the other hand, the hydrogen that constitutes the gas phase component in the gas-liquid separator 31 is crude hydrogen, which contains TOL and MCH in amounts corresponding to the vapor pressure that depends on the temperature. This crude hydrogen is extracted from the upper portion of the gas-liquid separator 31 and sent to the PSA unit 33 via the crude hydrogen transport line L25.

[0107] The PSA unit 33 is a device for purifying the crude hydrogen gas (the gaseous component of the reaction product gas) supplied from the gas-liquid separator 31. PSA unit 33 removes impurities contained in the crude hydrogen gas by supplying the crude hydrogen gas to a column (adsorption tank) filled with an adsorbent, thereby adsorbing the impurities. PSA unit 33 includes a plurality of columns arranged in parallel, and continuously performs purification by alternately switching between the columns used for the regeneration process and the columns used for the purification process.

[0108] In the column used for the purification process, which is supplied with the reaction product gas, impurities are adsorbed on the adsorbent under high pressure, thereby removing the impurities. On the other hand, in the column used for the regeneration process, the pressure in the column is reduced to desorb the adsorbed impurities, and high-purity hydrogen is supplied as a purge gas to purge the desorbed impurities. The product hydrogen is used as the purge gas used in the regeneration operation of the column used for the regeneration process. The purge gas discharged from the PSA unit 33 after the impurities are removed (hereinafter referred to as the exhaust purge gas) contains impurities desorbed from the adsorbent, but the hydrogen concentration is relatively high compared to the impurity concentration. For example, the hydrogen concentration of the exhaust purge gas is 80% or greater.

[0109] However, please note that the hydrogen concentration of the exhaust purge gas can be adjusted by changing the design of the columns of the PSA unit 33. That is, if the column size (i.e., the amount of adsorbent) is increased and the purification process time is increased, the amount of impurities removed by adsorption increases, and therefore the hydrogen concentration in the purge gas decreases. On the other hand, if the column size is designed to be small and the switching time (purification process time) is shortened, the hydrogen concentration in the purge gas becomes higher because the amount of impurities removed by adsorption is smaller.

[0110] Here, the calorific value of hydrogen per unit weight is 120MJ / kg, which is very high. However, hydrogen has a small molecular weight and is light in weight. Therefore, when converted to unit volume, hydrogen is a substance with a low calorific value of 12MJ / Nm 3 On the other hand, hydrocarbons such as gasoline and kerosene contain the heat of combustion of carbon, so their calorific value per unit weight is approximately 40 MJ / kg, which is about one-third that of hydrogen. Regarding TOL, the ratio of hydrogen atoms to carbon atoms is not significantly different, so their heat of combustion (39.5 MJ / kg) is basically the same as that of gasoline, kerosene, etc.

[0111] Since the impurities in the exhaust purge gas are mainly TOL, assuming that the hydrogen concentration in the exhaust purge gas is 80% and the remaining 20% ​​is TOL, then 1Nm 3 The exhaust purge gas has a heat content of about 10 MJ for hydrogen and about 80 MJ for TOL. Therefore, the exhaust purge gas has a total heat content of 90 MJ / Nm 3 Similarly, assuming that the TOL concentration in the exhaust purge gas is 10%, the heat corresponding to TOL is approximately 40 MJ. Therefore, the heat of the exhaust purge gas including the heat corresponding to hydrogen is 50 MJ / Nm 3 .

[0112] The hydrogen contained in the exhaust purge gas is product hydrogen and therefore valuable. For example, 800 L of hydrogen has a heat value of 8.6 MJ, and 200 L of TOL gas has a heat value of 34.6 MJ. Therefore, 1000 L of exhaust purge gas with an 80% hydrogen concentration has a heat value of 43.2 MJ. On the other hand, the heat required to produce 800 L of hydrogen through the dehydrogenation reaction is 2.6 MJ. Therefore, if the hydrogen used in the exhaust purge gas is produced through the dehydrogenation reaction, the exhaust purge gas can be a heat source that produces hydrogen with a volume approximately 17 times the volume of the hydrogen contained therein.

[0113] On the other hand, in the case where the generated exhaust purge gas has a hydrogen concentration of 90% and a TOL gas concentration of 10%, the total of 17.3 MJ of heat corresponding to the TOL gas and 9.6 MJ of heat corresponding to the hydrogen is 26.9 MJ, so the heat amount of the exhaust purge gas is reduced.

[0114] Similarly, if the TOL concentration in the exhaust purge gas increases to provide the required heat, the amount of carbon dioxide emitted increases, and the LCACO2 value becomes larger, thereby weakening the significance of the hydrogen station. Therefore, in the hydrogen station 1, it is important to design an optimal system from the perspectives of the heat of the exhaust purge gas, the economic benefits based on the hydrogen concentration, and the environmental impact based on LCACO2.

[0115] The exhaust purge gas from the PSA unit 33 is sent to a purge gas tank 39 via a purge gas pump 37 provided in an exhaust purge gas line L31 and stored there. Regarding the storage pressure in the purge gas tank 39, if the pressure is relatively low, the following problem arises: the exhaust purge gas cannot be properly supplied to the catalytic combustion coil 28 due to pressure loss when supplying it to the catalytic combustion coil 28. On the other hand, if the storage pressure in the purge gas tank 39 is relatively high, even if there is an advantage in that the size of the purge gas tank 39 can be reduced, the power required by the purge gas pump 37 increases, resulting in a decrease in the energy efficiency of the hydrogen station 1 due to increased energy loss. Therefore, the storage pressure in the purge gas tank 39 is determined by taking into account economic and energy benefits, as well as pressure loss and required power. The storage pressure is preferably set within the range of 1 to 20 standard atmospheres, and more preferably within the range of 3 to 9 standard atmospheres.

[0116] The exhaust purge gas is introduced as fuel from the purge gas tank 39 via the purge gas supply line L33 to the catalytic combustion coil 28 of the heating device 26. Preferably, a highly active platinum-supported alumina catalyst (hereinafter referred to as the first catalyst), which is also used as a dehydrogenation catalyst, is installed in the catalytic combustion coil 28 together with an existing combustion catalyst (hereinafter referred to as the second catalyst) for ignition. The first catalyst is installed in the fuel inlet portion 28A of the catalytic combustion coil 28, and its filling amount is smaller than that of the second catalyst. Depending on the surrounding environment of the hydrogen station 1 (especially the atmospheric temperature), etc., the fuel inlet portion 28A (i.e., the filling area of ​​the first catalyst in the catalytic combustion coil 28) can be set to an appropriate range (length) at the upstream end of the catalytic combustion coil 28. Thus, it is possible for the exhaust purge gas to be spontaneously ignited by the first catalyst in the fuel inlet portion 28A of the catalytic combustion coil 28 in an advantageous manner. Likewise, a portion downstream of the fuel inlet portion 28A of the catalytic combustion coil 28 (i.e., a portion other than the fuel inlet portion 28A) is filled with a second catalyst having a structure different from that of the first catalyst, and therefore, by using a catalyst (universal catalyst) that is cheaper than the first catalyst as the second catalyst, it is possible to reduce catalyst costs. However, please note that in the hydrogen station 1, it is not prohibited to use only the first catalyst as the combustion catalyst.

[0117] Ignition of the fuel in the catalytic combustion coil 28 is possible by providing an ignition source of approximately 700° C. achieved by heating the nickel-chromium alloy wire in the fuel inlet portion 28A, but in the hydrogen station 1, it is not preferred to use an open flame or provide a high-temperature portion of the nickel-chromium alloy wire in consideration of safety measures.

[0118] On the other hand, the first catalyst is characterized in that it has excellent ignitability, and it can ignite the exhaust purge gas even at room temperature. In cold areas, there is a problem that the moisture generated in the combustion adheres to the combustion catalyst and freezes on it, so the combustibility below the freezing point of water is not good. It is estimated that the platinum-supported alumina catalyst used in the dehydrogenation reaction of the present invention has high activity, which is 400 times or more higher than that of ordinary platinum catalysts, and has very high ignitability. Even if an ignition source such as an open flame or an electric heating wire is not provided, it is possible to make the exhaust purge gas quickly spontaneously ignite in the catalytic combustion coil 28 by using the platinum-supported alumina catalyst as a combustion catalyst. In particular, by increasing the particle size of the platinum particles supported on the carrier to to The ratio of particles enhances the dispersion of the reaction in the first catalyst, preventing the surface of the platinum from being completely covered with ice even if moisture on the combustion catalyst is frozen below the freezing point of water, thereby making it possible for the exhaust purge gas to spontaneously ignite quickly.

[0119] When the exhaust purge gas is catalytically combusted, a supply of oxygen is necessary. Air containing the oxygen required for catalytic combustion is supplied to the catalytic combustion coil 28 via an air pump 41 provided in an air supply line L37. Air supply line L37 is connected to a connection portion 43 of a purge gas supply line L33. Thus, the exhaust purge gas flowing through line L33 mixes with air in connection portion 43 and is then directed to the fuel inlet portion 28A of the catalytic combustion coil 28. In this manner, when the exhaust purge gas comes into contact with the first catalyst for spontaneous ignition, which is installed in the fuel inlet portion 28A, the mixture of the exhaust purge gas and the required amount of air spontaneously ignites.

[0120] The amount of air supplied to the line L33 is only required to be greater than the theoretical amount required for burning the exhaust purge gas. However, please note that if the amount of air supplied is too much, it will hinder the catalytic combustion reaction, while if the amount of air supplied is too little, there may be a problem that the gas diffusion in the combustion catalyst layer may stagnate and it may be difficult to maintain a good combustion reaction.

[0121] Likewise, the air required for the catalytic combustion in the catalytic combustion coil 28 does not necessarily have to be completely mixed with the exhaust purge gas introduced to the fuel inlet portion 28A (i.e., introduced to the connection portion 43 of the pipe L33). For example, at least a portion of the air introduced to the connection portion 43 as described above may be supplied via the split air supply pipe L37A (see Figure 3 The air is introduced to the middle portion of the catalytic combustion coil 28 (ie, the downstream side of the fuel inlet portion 28A) by the dotted line in FIG. This introduction of air to the middle portion of the catalytic combustion coil 28 can be performed for at least one or more middle portions.

[0122] Since air is supplied separately to the catalytic combustion coil 28 in this way, the following problems are avoided, for example, the formation of a hot spot due to the rapid progress of the catalytic combustion reaction near the fuel inlet portion 28A, thereby preventing uniform heating of the heat medium in the storage tank 27, or the occurrence of sintering of metal particles (aggregation of active metal of the combustion catalyst) due to the formation of the hot spot, thereby reducing the surface area of ​​the active metal and deteriorating the performance of the combustion catalyst.

[0123] Furthermore, it is also possible to supply at least one of the gas constituting the gas phase component in the MCH tank 4 (hereinafter referred to as MCH tank gas) and the gas constituting the gas phase component in the toluene tank 6 (hereinafter referred to as toluene tank gas) as fuel to the catalytic combustion coil 28 together with the exhaust purge gas. More specifically, as Figure 3As shown by the dotted line in , the MCH tank gas discharged from the MCH tank 4 is sent to the connecting portion 43 of the purge gas supply pipeline L33 by the gas discharge pump 44 provided in the tank gas discharge pipeline L38. Thus, at the downstream end of the tank gas discharge pipeline L38, the MCH tank gas is mixed with the discharged purge gas in the connecting portion 43. Similarly, the toluene tank gas discharged from the toluene tank 6 is sent to the connecting portion 43 of the pipeline L33 via the branch pipeline L38A connected to the middle part of the tank gas discharge pipeline L38. Thus, at the downstream end of the tank gas discharge pipeline L38, the toluene tank gas is mixed with the discharged purge gas in the connecting portion 43. Please note that the toluene tank gas can be led to the pipeline L33 via a pipeline (pipeline) different from the pipeline (pipeline) of the MCH tank gas. Similarly, the position where the MCH tank gas and the toluene tank gas are led to the pipeline L33 is not limited to the connecting portion 43 and can be changed appropriately.

[0124] The fuel (including the exhaust purge gas) catalytically combusted in the catalytic combustion coil 28 is discharged from its downstream end as exhaust gas. The exhaust gas passes through an exhaust gas line L39 equipped with an exhaust gas regulating valve 45, while maintaining a temperature of 100°C or higher to prevent moisture condensation, and is released into the atmosphere. Because the exhaust gas is completely burned, it has been converted into a gas containing water vapor and nitrogen as its main components, with low concentrations of CO2 and unreacted oxygen. Therefore, it is harmless and can be released into the atmosphere.

[0125] The product hydrogen obtained by purifying the crude hydrogen in the PSA unit 33 has a purity of, for example, 99.7% or higher and a carbon content of 2 ppm or less. The product hydrogen is sent from the PSA unit 33 to the compressor 9 via a hydrogen transport line L5.

[0126] (Second embodiment)

[0127] Next, we will refer to Figure 4 A hydrogen station 1 and a method for producing hydrogen therefrom according to a second embodiment of the present invention will be described. Figure 4 Components similar to those in the first embodiment are denoted by the same reference numerals. Similarly, regarding the hydrogen station 1 according to the second embodiment, features not specifically mentioned below are the same as those of the first embodiment. The hydrogen station 1 and hydrogen production method thereof according to the second embodiment are particularly suitable for improving the recovery rate of TOL contained in the reaction product gas.

[0128] As in the first embodiment, impurities other than hydrogen contained in the reaction product gas of the dehydrogenation reaction performed by the dehydrogenation reactor 23 include TOL as a main component and also include unreacted MCH and methane gas generated by decomposition side reactions. Among these impurities, TOL and MCH can be repeatedly used as hydrogen carriers in the OCH process, and therefore, it is preferable to recover them as much as possible within the range that can ensure economic efficiency.

[0129] As in the first embodiment, the reaction product gas flowing in the reaction product gas line L21 passes through the heat exchanger 25, where it is cooled by transferring heat to the raw material gas in the raw material supply line L1, and thereafter is cooled to a temperature of 100° C. or lower (e.g., approximately 50° C.) by natural cooling in the gas-liquid separator 31. However, it should be noted that in hot seasons, such as summer, the temperature in the gas-liquid separator 31 may exceed 60° C. The crude hydrogen gas constituting the gas phase component of the gas-liquid separator 31 contains TOL and MCH in amounts corresponding to the vapor pressure depending on the temperature. Therefore, further cooling the gas-liquid separator 31 to lower the temperature of the crude hydrogen effectively reduces the concentrations of TOL and MCH in the crude hydrogen gas fed to the PSA unit 33.

[0130] Therefore, in the hydrogen station 1 according to the second embodiment, as Figure 4 As shown in FIG, the cooling capacity of the coolant of the precooler 17 is used to cool the crude hydrogen. More specifically, the coolant is circulated in the second coolant circulation line L41 provided between the precooler 17 and the gas-liquid separator 31, thereby cooling the interior of the gas-liquid separator 31. In this way, the coolant supplied to the distributor 15 (see FIG. Figure 2 ) and the cooling capacity supplied to the gas-liquid separator 31 are both provided by the precooler 17, so the crude hydrogen can be cooled with a simple configuration. Because the coolant supplied to the gas-liquid separator 31 has a relatively low temperature (for example, -40°C), its supply amount can be small, and the pipe size of the second coolant circulation line L41 can also be small, so that thermal insulation can be easily achieved. Due to the cooling of the coolant, the crude hydrogen in the gas-liquid separator 31 can be cooled to approximately -10°C to 0°C. Therefore, the concentrations of TOL and MCH contained in the crude hydrogen in an amount corresponding to the vapor pressure can be significantly reduced, the processing load of the PSA device 33 can be reduced, and the loss of TOL and MCH used as hydrogen carriers can also be reduced.

[0131] Note that the second coolant circulation line L41 may be provided separately from the first coolant circulation line L13. Alternatively, the first coolant circulation line L13 and the second coolant circulation line L41 may be provided in series. In this case, the coolant may be used for cooling the gas-liquid separator 31 after cooling the hydrogen in the distributor 15.

[0132] (Dehydrogenation Catalyst)

[0133] Next, a novel dehydrogenation catalyst (platinum-supported alumina catalyst) will be described that can be used in the hydrogen station 1 and hydrogen production method according to the first and second embodiments of the present invention. As described above, this dehydrogenation catalyst can also be used as a combustion catalyst.

[0134] Figure 5 Shown are photos of catalysts taken by transmission electron microscopy (A) in the 2000s and (B) in recent years. Figure 5 (A) is a photograph of an eggshell-type catalyst disclosed in Patent Document 13 (JP4652695B2). Figure 5 The photo (A) was taken in 2006 using a Hitachi HD-200 transmission electron microscope, the latest model at the time, at a magnification of 1.8 million times. Figure 5 (B) is a photograph of a uniform platinum-supported alumina catalyst disclosed in Patent Document 4 (JP4142733B2). Figure 5 The image (B) was taken using a JEOL JEM-ARM200 electron microscope in 2018 at a magnification of 2 million times.

[0135] The resolution of general transmission electron microscopes in the 2000s was not enough to measure the platinum particle size of a few nanometers by direct observation, so the particle size was usually estimated by the CO pulse method (CO pulse adsorption method). Particles and molecules such as benzene rings with a resolution of about

[0136] exist Figure 5 In the transmission electron microscope photograph from the 2000s shown in (A), it can be seen that a plurality of platinum particles are independently supported, but the outlines of the white spots (ie, platinum particles) are unclear, so the particles appear larger than they actually are.

[0137] exist Figure 5 In the recent transmission electron microscope photograph shown in (B), it can be seen that the outline of the white spots (platinum particles) can be observed more clearly. Therefore, by direct observation with a recent transmission electron microscope, the particle size of platinum supported on the alumina carrier can be measured with higher accuracy. The average particle size of the platinum particles in the platinum-supported alumina catalyst of the present invention can be measured by measuring the average particle size of the platinum particles in the platinum-supported alumina catalyst of the present invention. Figure 5(B) is obtained by measuring the particle size of a predetermined number (typically, about 50) of platinum particles in a photograph taken with a transmission electron microscope and calculating its average value. In a transmission electron microscope, it is preferred to set the magnification so that the particle size of a predetermined number of platinum particles fits the photograph (for example, using the platinum-supported alumina catalyst of the present invention, 40 to 50 platinum particles can be observed in a field of view of 2 million times magnification). The size of each platinum particle can be measured by aligning the measuring line with the outline of the particle on a computer screen equipped with an electron microscope system. At this time, in the case where the shape of the platinum particles has a major axis diameter and a minor axis diameter, the major axis diameter can be measured by aligning the measuring line with the outline of the major axis diameter, and the minor axis diameter can be measured in a similar manner. In the platinum-supported alumina catalyst of the present invention, there is basically no difference between the major axis diameter and the minor axis diameter of the platinum particles, so the major axis diameter can be used as a representative value. In addition, the size of the particle diameter can also be measured by printing an image and measuring the particle diameter with a ruler to compare with the scale on the image.

[0138] In contrast, the platinum particle sizes disclosed in the above-mentioned Patent Documents 3 and 4 are estimates by the CO pulse method. It is considered that there is an error between the particle size estimated by the CO pulse method and the particle size measured by direct observation using a transmission electron microscope. This is because in the CO pulse method, the particle size may be estimated to be smaller than the particle size measured by direct observation. In the CO pulse method, since 1 molecule of CO is adsorbed on 1 atom of platinum on the surface of the platinum particle, the total CO adsorption amount is measured, and assuming that the shape of the platinum particle is a cube, the particle size is estimated to be the length of one side thereof. At this time, the estimation is made under the assumption that CO is not adsorbed on the carrier. In the case of a platinum-supported alumina catalyst, CO is preferentially adsorbed on platinum, and the injection of CO is stopped immediately when the amount of discharged CO is equal to the amount of injected CO, but in the alumina carrier, the surface area is large and a certain amount of CO is adsorbed on the carrier, and therefore, it is estimated that the CO is adsorbed on the platinum surface.

[0139] Here, the CO pulse method will be described. When CO is pulsed into the sample, CO is adsorbed on the surface of the supported metal, and the amount of CO emitted is small in the initial stage of injection. Soon, CO is adsorbed on almost the entire surface of the supported metal, and when a steady state is reached, almost all of the injected CO is discharged. At this time, the amount of CO discharged in the steady state is subtracted from the amount of CO discharged during the adsorption period, and the sum of the differences is calculated as the amount of CO adsorbed. The CO pulse method is a method of calculating the metal surface area, dispersion rate, and particle size based on the adsorption amount and the supported metal content. The specific calculation method is described below.

[0140] From the amount Vt of CO gas adsorbed by a sample amount of the catalyst W (g) at the measurement temperature, the amount V of adsorbed gas per gram of the catalyst at 0°C is obtained by the following formula (1).

[0141] V = (Vt / W)×{273 / (273 + t)} (ml / g-cat) ... (1)

[0142] Here, when the percentage of the metal content of the sample is defined as C (%) and the atomic weight of the supported metal is defined as M, the number of moles R of the supported metal per gram of the sample is calculated from formula (2).

[0143] R = (C / 100)×(1 / M) (mol / g-cat) ... (2)

[0144] The number of moles K of adsorbed gas per gram of sample is obtained from formula (3).

[0145] K = V / (22.4 × 10 -3 ×10 6 ) (mol / g-cat) ... (3)

[0146] From these, the dispersion degree B (the ratio of the effective surface metal in the supported metal) is obtained by formula (4).

[0147] B = (K / R) ×100 (%) ... (4)

[0148] When the lattice constant of the supported metal catalyst is defined as And assume that an adsorbed gas molecule is adsorbed on the lattice constant area a 2 When , the specific surface area S of the metal is obtained by formula (5).

[0149] S = number of gas molecules adsorbed by 1g sample × a 2

[0150] = K × 6.02 × 10 23 ×(a ×10 -10 ) 2 ... (5)

[0151] Furthermore, when the supported metal particles are assumed to be a cube having a side length of D(m), five of the six surfaces of the particles are effective, and thus, the following equation is established.

[0152] The effective area of ​​a particle S = 5D 2 (m 2 ) ... (6)

[0153] The volume of a particle v = D 3 (m 3 ) ... (7)

[0154] When the number of metal-supported particles per gram of sample is defined as n, the following equation is established.

[0155] The specific surface area of ​​the supported metal S = ns = n5D 2 (m 2 )...(8)

[0156] Volume of supported metal Vc=nv=Nd 3 (m 3 )...(9)

[0157] From equations (6) to (9), the length of one side D (m) is expressed by equation (10).

[0158] S / Vc = 5 / D, therefore, D = 5Vc / S (m) ... (10)

[0159] Here, when the percentage of supported metal content is defined as C (%) and the specific gravity is defined as d (g / cm 3 ), the supported metal volume Vc per gram of sample is expressed by formula (11).

[0160] Vc = weight of supported metal per gram of sample (g / g) / specific gravity of supported metal (g / cm 3 )

[0161] = C / 100 / d (g / cm 3 ) ... (11)

[0162] Therefore, the particle size is calculated by formula (12).

[0163]

[0164] As described above, in conventional platinum-supported alumina catalysts, the CO-pulse method or transmission electron microscopy (see Figure 5 (A)) The particle size of platinum supported on an alumina carrier is measured (calculated), with relatively large errors. Therefore, in conventional platinum-supported alumina catalysts, the preferred range of platinum particle size is set to a relatively wide range because it is difficult to control the platinum particle size with high precision.

[0165] In contrast, in the present invention, based on recent transmission electron micrographs (see Figure 5 The value of the platinum particle size measured with high precision in (B)) sets the range of platinum particle size (platinum particle size distribution) that can significantly improve the catalyst life compared with conventional platinum-supported alumina catalysts. In the platinum-supported alumina catalyst of the present invention, it is preferred that 70% or more of the platinum particles supported on the γ-alumina carrier have a particle size distribution when directly observed using a transmission electron microscope. More preferably, 80% or more of the platinum particles supported on the γ-alumina support have a size of Further preferably, 90% or more of the platinum particles supported on the γ-alumina carrier have 8 to size.

[0166] Below, refer to Figure 2 The eggshell-type metal-supported catalyst and the uniform metal-supported catalyst of the present invention will be described. The eggshell-type metal-supported catalyst refers to a state in which the metal component to be supported is dispersed and supported only on the outer shell portion of the cross-section of the shaped catalyst. That is, the metal support portion 2 on which the metal component is supported is formed in the outer shell portion of the porous support 1. The uniform metal-supported catalyst refers to a state in which the metal component is dispersed throughout the cross-section of the catalyst, and the metal support portion 2 on which the metal component is supported is formed throughout the interior of the shaped body of the porous support 1.

[0167] The platinum-supported alumina catalyst of the present invention comprises an alumina carrier and platinum supported on the alumina carrier.

[0168] Next, the alumina support used in the platinum-supported alumina catalyst of the present invention will be described.

[0169] The alumina support is preferably a porous γ-alumina support. For example, as disclosed in JPH6-72005B2, the alumina support is preferably a porous γ-alumina support obtained by filtering and washing an aluminum hydroxide slurry produced by neutralizing an aluminum salt, dehydrating and drying the resulting alumina hydrogel, and then calcining the product at 400-800°C for approximately 1-6 hours. More preferably, the alumina support is a porous γ-alumina support obtained by a pH swing method, in which the pH of the alumina hydrogel alternately fluctuates between a pH range in which the alumina hydrogel dissolves and a pH range in which the boehmite gel precipitates, while an alumina hydrogel-forming substance is added to form alumina hydrogel crystals as the pH fluctuates from at least one pH range to another. The porous γ-alumina support obtained by the pH swing method has excellent uniformity in pore distribution and, since the physical properties of the alumina support particles after support formation also vary slightly, is also excellent in the stability of the physical properties of each particle.

[0170] The inventors of the present application have further studied the relationship between the drying and calcining conditions of alumina hydrogel (boehmite) and the particle size of the supported platinum. As a result, they found that in order to stably support many platinum particles on a γ-alumina carrier with a diameter of 8 to 100 nm, the following parameters should be considered: It is particularly preferred that the drying temperature is 200°C or lower, the subsequent calcination temperature is 250 to 400°C, and the calcination time is 1 to 12 hours.

[0171] When preparing the uniform platinum-supported alumina catalyst of the present invention, there are no restrictions on the sulfur or sulfur compound that must be pre-dispersed in the alumina support, as long as the sulfur or sulfur compound contains elemental sulfur and can be uniformly dispersed in the catalyst support during or after the catalyst support is prepared. Examples of the sulfur or sulfur compound include sulfur crystalline powder, sulfur-containing compounds such as sulfuric acid, and sulfates including ammonium sulfate. To facilitate the dispersion of sulfur on the support, sulfur compounds that are soluble in water or an organic solvent are preferred. Examples of such sulfur compounds include sulfuric acid and ammonium sulfate.

[0172] The amount of sulfur contained in the support, calculated as elemental sulfur (S), is preferably 0.15-5.0% by weight, more preferably 0.15-3.0% by weight. When the sulfur content is less than 0.15% by weight, the degree of uniform metal loading at the center of the catalyst is low, while when the sulfur content exceeds 5% by weight, there is a problem that sulfur may locally aggregate and the metal may not be dispersed and loaded in this area. In view of the above, considering the effect of uniform metal dispersion and loading, the most suitable sulfur content range is 0.15-5.0% by weight.

[0173] The inventors of the present application have further studied the relationship between sulfur concentration and the particle size of supported platinum and found that in order to stably support a large number of platinum particles on a γ-alumina carrier with a The size of the composite material is particularly preferably such that the content of sulfur or sulfur compounds is 0.5-1.2% by weight, calculated as elemental sulfur (S), relative to the sulfur content range.

[0174] In the present invention, regarding the method for preparing a sulfur-containing catalyst carrier containing the above-mentioned sulfur or sulfur compound, a method capable of introducing sulfur or sulfur compound in a state where the sulfur or sulfur compound is uniformly dispersed over the entire cross-section of the carrier can be used. For example, the following methods are mentioned: Method A, which comprises kneading sulfur powder into the obtained metal hydroxide gel as a metal oxide precursor when preparing the catalyst carrier, molding the resultant into a predetermined shape, and drying and calcining the resultant; Method B, which comprises preparing a sulfur-containing metal hydroxide gel as a metal oxide precursor using a metal sulfate and / or sulfuric acid when preparing the catalyst carrier, molding the resultant into a predetermined shape, and drying and calcining the resultant; Method C, which comprises molding the metal hydroxide gel as a metal oxide precursor into a predetermined shape when preparing the catalyst carrier, drying the resultant to form a dried metal hydroxide gel, and impregnating the dried metal hydroxide gel with a sulfur compound solution. a metal oxide, and calcining the metal oxide; a method D comprising, when preparing a catalyst support, shaping a metal hydroxide gel as a metal oxide precursor into a predetermined shape, drying the resultant to form a dried metal hydroxide, impregnating the dried metal hydroxide with a sulfur compound solution, and calcining the metal hydroxide; and a method E comprising shaping a metal hydroxide gel as a metal oxide precursor into a predetermined shape, drying the resultant to form a dried metal hydroxide gel, calcining the dried metal hydroxide gel to form a calcined metal oxide, impregnating the calcined metal oxide with a sulfur compound solution such as an aqueous sulfuric acid solution and an ammonium sulfate solution, and further calcining the resultant.

[0175] The inventors of this application have conducted further research on the method of preparing sulfur-containing catalyst supports and found that in order to stably support a large number of platinum particles on the γ-alumina support, the size of the particles should be It is particularly preferred to disperse and support sulfur on the surface of the γ-alumina support according to the above-mentioned method E.

[0176] Regarding the calcination conditions for preparing the sulfur-containing catalyst support, the calcination temperature is generally 100 to 1000°C, preferably 350 to 800°C, and the calcination time is 0.5 to 48 hours, preferably 1 to 24 hours. When the calcination temperature is lower than 350°C, the conversion from hydroxide to oxide may not be complete, while when the calcination temperature is higher than 800°C, the surface area after calcination may be significantly reduced.

[0177] The inventors of the present application have further studied the drying and calcining conditions when preparing the sulfur-containing γ-alumina carrier. As a result, it was found that in order to stably support a large number of platinum particles on the γ-alumina carrier to have It is particularly preferred that, for the drying conditions, the drying temperature is 100-200° C. and the drying time is 3-12 hours, and for the calcining conditions, the calcining temperature is 250-400° C. and the calcining time is 1-12 hours.

[0178] In the present invention, the amount of platinum supported on the sulfur-containing catalyst support is 0.05-5.0 wt%, preferably 0.1-3.0 wt%, calculated as elemental platinum. When the platinum loading (loaded amount) is less than 0.05 wt%, activity is low, while when the platinum loading exceeds 5.0 wt%, the platinum particle size increases, selectivity decreases, and sintering may occur, leading to the possibility of deactivation.

[0179] The inventors of the present application have further studied the preferred loading amount of platinum and found that in order to stably load a large number of platinum particles on the γ-alumina carrier to have The size range is such that the amount of platinum supported is preferably 0.1 to 1.5 wt % calculated as the content of elemental platinum, and more preferably 0.5 to 1.5 wt % from the viewpoint of improving the life of the prepared platinum-supported alumina catalyst.

[0180] In the present invention, when platinum metal is supported on a γ-alumina carrier, the γ-alumina carrier may be impregnated with a solution of a platinum compound, dried, and then calcined at a predetermined temperature. Examples of platinum compounds include chlorides, bromides, ammonium salts, carbonyl compounds, and various complexes of platinum, such as amine complexes, ammonia complexes, and acetylacetonate complexes. Examples of platinum compounds include chloroplatinic acid, platinum acetylacetonate, ammonium platinate, bromoplatinate, platinum dichloride, platinum tetrachloride hydrate, carbonyldichloroplatinum, and dinitrodiamineplatinate.

[0181] The inventors of the present application conducted further research on the platinum compounds used for impregnation and found that, from the perspective of improving the life of the prepared platinum-loaded alumina catalyst, it is particularly preferred to use an aqueous solution of chloroplatinic acid as the platinum reagent aqueous solution to impregnate the calcined γ-alumina carrier with platinum.

[0182] After the alumina support is impregnated with the above platinum compound solution, the alumina support to which the platinum compound is attached is dried at 50-200°C for 0.5-48 hours and then calcined at 350-600°C for 0.5-48 hours, more preferably at 350-450°C for 0.5-5 hours.

[0183] The inventors of the present application have further studied the drying and calcining conditions after platinum is appropriately impregnated on an alumina support (for example, the content calculated as elemental platinum is in the range of 0.5 to 1.5 wt %), and found that in order to stably support a large number of platinum particles on a γ-alumina support to have a thickness of 8 to 1.5 wt %, the conditions for the platinum to be calcined should be kept constant. It is particularly preferred that, with respect to the drying conditions, the drying temperature is 100 to 200° C. and the drying time is 3 to 12 hours, and with respect to the calcination conditions, the calcination temperature is 250 to 450° C. and the calcination time is 1 to 8 hours.

[0184] Then, as the final step of the platinum loading process, the alumina support to which the platinum compound is attached is placed in a hydrogen atmosphere and subjected to a hydrogen reduction process under reducing conditions of 350 to 600° C. for 0.5 to 48 hours, preferably 350 to 550° C. for 3 to 24 hours. If the temperature during the hydrogen reduction is lower than 350° C., there arises a problem in that platinum is not sufficiently reduced, while if the temperature exceeds 600° C., there arises a problem in that platinum particles sinter during reduction and metal dispersion is reduced.

[0185] The inventors of the present application have further studied the temperature conditions for hydrogen reduction after appropriate platinum impregnation and calcination, and found that in order to stably support a large number of platinum particles on the γ-alumina carrier to have It is particularly preferred that the hydrogen reduction temperature is 300-450° C. and is lower than or equal to the calcination temperature after platinum impregnation, and the hydrogen reduction time is 1-15 hours.

[0186] The amount of alkali added to the eggshell-type platinum-supported alumina catalyst and the uniform platinum-supported alumina catalyst prepared by incorporating sulfur into a γ-alumina carrier is 0.1 to 5% by weight, preferably 0.3 to 3.0% by weight, and more preferably 0.5 to 1.5% by weight. When the alkali metal loading is less than 0.1% by weight, there are problems of a short catalyst life and a small effect, while when the loading exceeds 5.0% by weight, there are problems of reduced activity and a shortened catalyst life.

[0187] The inventors of this application have conducted a study on the process of supporting a plurality of platinum particles on a γ-alumina carrier to have a diameter of 8 to 100 nm. The preferred amount of base added when the size range is further studied, and it was found that as long as the amount of base added is 0.5 to 1.5 weight%, it has no significant effect on the size of the prepared platinum particles.

[0188] Alkali metal compounds used when supporting an alkali metal on an eggshell-type platinum-supported alumina catalyst or a uniform platinum-supported alumina catalyst prepared by incorporating sulfur into a γ-alumina carrier include, for example, chlorides, bromides, iodides, nitrates, sulfates, acetates, and propionates of the alkali metal, preferably water-soluble and / or soluble in an organic solvent such as acetone. Examples of such compounds include sodium chloride, sodium bromide, sodium iodide, sodium nitrate, sodium sulfate, sodium acetate, sodium propionate, potassium chloride, potassium bromide, potassium iodide, potassium nitrate, potassium sulfate, potassium acetate, potassium propionate, calcium chloride, calcium bromide, calcium iodide, calcium nitrate, calcium sulfate, calcium acetate, and calcium propionate.

[0189] In addition, when alkali metal is supported on an eggshell-type platinum-supported alumina catalyst and a uniform platinum-supported alumina catalyst prepared by containing sulfur in a γ-alumina carrier, they are impregnated with a solution of an alkali metal compound and then dried under dry conditions at room temperature to 200°C for 0.5 to 48 hours, preferably at 50 to 150°C for 0.5 to 24 hours, more preferably at 80 to 120°C for 0.5 to 5 hours, and then calcined at 350 to 600°C for 0.5 to 48 hours, preferably at 350 to 450°C for 0.5 to 5 hours.

[0190] The inventors of the present application have conducted a study on the effect of impregnating a γ-alumina carrier (where a plurality of platinum particles are supported on a γ-alumina carrier to have a thickness of 8 to 100 nm) with a solution of a preferred basic compound. The drying conditions after the drying were further studied and it was found that as long as the temperature was between room temperature and 200°C, it had no effect on the size of the supported platinum particles, regardless of the drying time.

[0191] The alkali metal-supported dry material obtained by impregnating an eggshell-type platinum-supported alumina catalyst and a uniform platinum-supported alumina catalyst prepared by including sulfur in a γ-alumina carrier and drying the impregnated catalyst is not calcined and is directly subjected to the final hydrogen reduction. The reduction conditions of the hydrogen reduction are preferably carried out at 350-600°C in a hydrogen atmosphere for 0.5-48 hours, more preferably at 350-550°C for 3-24 hours. If calcination is performed before the hydrogen reduction of the alkali metal-supported dry material, the problem of reduced catalyst performance related to activity, selectivity and life arises. In addition, if the temperature during hydrogen reduction is lower than 350°C, there is a problem that platinum is not completely reduced. If the temperature during hydrogen reduction exceeds 600°C, there is a problem that platinum particles sinter during reduction and metal dispersion is reduced.

[0192] The inventors of this application have made it possible to load a large number of platinum particles on a γ-alumina carrier with a diameter of 8 to 100 mm. In order to obtain a size within a certain range, the hydrogen reduction conditions after impregnation with a preferred alkaline compound solution and drying were further studied. It was found that if the temperature and reduction time were less than or equal to the temperature and reduction time of the hydrogen reduction performed as the last step of the platinum loading process before the addition of the alkali metal, there was no effect on the size of the supported platinum particles.

[0193] Hereinafter, preferred embodiments of the dehydrogenation catalyst of the present invention will be described in detail based on Examples and Comparative Examples.

[0194] [Comparative Example 1] (Comparison of the particle size measurement results of the eggshell catalyst described in Patent Document 3 and the uniform platinum-supported alumina catalyst described in Patent Document 4 between direct observation using a transmission electron microscope and the CO pulse method)

[0195] The platinum particle size of the eggshell catalyst described in Patent Document 3 is estimated based on the dispersion estimated from the CO adsorption amount measured by the CO pulse method, assuming that the shape of the platinum particles is a cube. As shown in Table 2 (Experimental Example 1) and Table 3 (Experimental Example 2) of Patent Document 3, the particle size is estimated to be Particle size within the range.

[0196] On the other hand, as shown in Table 1 (Implementation 4) of Patent Document 4, the particle size of the uniform platinum-supported alumina catalyst described in Patent Document 4 is estimated to be particle size.

[0197] like Figure 6 As shown, the 42 platinum particles in the uniform platinum-supported alumina catalyst described in Patent Document 4 (see Figure 6 The particle size is the number 1-42 in the figure. Figure 6 The catalyst images shown correspond to Figure 5 (B) is a transmission electron microscope photograph. This catalyst is also equivalent to the catalyst No. 6 (particle size) described in Patent Document 4 (Table 1). ).

[0198] The measurement of platinum particle size can be performed by using the particle size measurement function on the electron microscope screen. However, by comparing the length of the largest diameter portion of the particle size with the scale shown in the electron microscope photograph, approximately the same measurement results can be obtained. Table 1 shows the results of the particle size measurement. The average particle size of the 42 platinum particles shown in Table 1 is (1.68nm).

[0199] Table 1

[0200]

[0201] According to the measurement results of platinum particle size shown in Table 1, it can be seen that among the 42 measured platinum particles, 19 (about 45%) platinum particles have a size of 8 to (0.8 to 1.5 nm), 23 platinum particles larger than (1.5nm) and the size is (1.6nm) or larger.

[0202] Therefore, when the direct observation image of the uniform platinum-supported alumina catalyst described in Patent Document 4 (Catalyst No. 6 in Table 1 of Patent Document 4) was measured by electron microscope, the average particle size of platinum was 1.68 nm. It can be seen from this that the estimated value of the platinum particle size by the CO pulse method described in Patent Document 4 is This is a very small value compared to the value measured by direct observation of electron microscope images.

[0203] As described above, for the eggshell-type catalyst described in Patent Document 3 and the uniform-type platinum-supported alumina catalyst described in Patent Document 2, the dispersion estimated based on the CO adsorption amount measured by the CO-pulse method and the particle size estimated assuming that the shape of the platinum particles is a cube was estimated to be However, these particle sizes are also considered to be quite small values ​​based on direct observation using an electron microscope.

[0204] The large error in the estimated particle size obtained by such a CO pulse method is believed to be due to the fact that in the CO pulse method, the estimation is based on the following assumption: it is assumed that the introduced CO is adsorbed on the platinum atoms exposed on the surface of the platinum particles, but in fact, many CO molecules are adsorbed on the alumina support, so the observed CO adsorption amount is large. The particle size is estimated as the length of one side assuming that the shape of the platinum particles is cubic.

[0205] [Comparative Example 2] (Production method described in the embodiment of Patent Document 3)

[0206] The method for producing the eggshell-type platinum-supported γ-alumina catalyst described in the embodiment of Patent Document 3 will be described.

[0207] Similar to the embodiment of Patent Document 3, a porous γ-alumina support was prepared according to the conventional technology described in Embodiment 1 of JPH6-72005B2. The outline of the method is as follows. While vigorously stirring, an aqueous sodium aluminate solution was instantly added to hot dilute sulfuric acid to obtain an aluminum hydroxide slurry suspension (pH 10). This suspension was used as an aluminum hydroxide seed crystal, and while continuing to stir, the operation of alternating addition of hot dilute sulfuric acid and sodium aluminate solution at regular intervals was repeated to obtain a filter cake after filtration and washing. The filter cake was extruded and dried, and then calcined at 500°C for 3 hours.

[0208] The physical properties of the γ-alumina carrier thus prepared are: surface area of ​​240 m2 / g, pore volume of 0.713 cm3 / g, average pore diameter of Aperture The pore occupancy is 90%. 79 g of a 0.4 wt% aqueous solution of chloroplatinic acid (the aqueous solution was prepared so that the pH value was 2.0) was added to 20 g of the porous γ-alumina support and allowed to stand for 3 hours for impregnation before removing water by decantation. Subsequently, the resultant was dried at 120°C for 3 hours and then calcined at 400°C in an air flow in a muffle furnace for 3 hours. After the obtained calcined product was cooled to room temperature in a dryer, it was reduced at 400°C under a hydrogen flow for 15 hours to prepare a dehydrogenation catalyst (equivalent to Catalyst No. 2 in Table 2 of the embodiment of Patent Document 3). According to the CO-pulse method, the platinum particle size of the catalyst was estimated to be

[0209] [Comparative Example 3] (Production method described in the embodiment of Patent Document 4)

[0210] A method for producing a uniform platinum-supported γ-alumina catalyst described in an embodiment of Patent Document 4 will be described.

[0211] 3900cc of a 2.67mol / L aluminum nitrate aqueous solution was prepared, along with 3900cc of a 14% ammonia solution. 20L of pure water was added to a 30L enameled container, and the container was heated to 70°C while stirring. While stirring, the pH was adjusted four times: 1300cc of the aluminum nitrate aqueous solution was added, stirred for 5 minutes (pH = 2.0), and then 1300cc of the ammonia solution was added, stirred for 5 minutes (pH = 7.4). The resulting aqueous slurry of aluminum hydroxide was filtered to recover a filter cake, which was then washed three times by redispersing the filter cake in 20L of pure water and filtering it again to obtain a washed gel.

[0212] The washed filter cake was air-dried, its moisture content adjusted, and then formed into rods with a diameter of 1.6 mm using an extruder. The resulting product was dried (120°C, 3 hours), crushed to approximately 1 cm in length, and calcined in a muffle furnace (500°C, 3 hours) to obtain a sulfur-free alumina support A. The resulting alumina support A had a BET surface area of ​​275 m2 / g and a pore volume of 0.65 cm3 / g as measured by mercury porosimetry. Furthermore, the resulting alumina support A had an average pore diameter of 8.9 nm and a sharp pore distribution, with nearly all pores concentrated near the average pore diameter. Furthermore, the volume occupied by pores with a diameter of 7 to 10 nm accounted for 80% or more of the total pore volume.

[0213] Alumina Support A was impregnated with an aqueous solution of ammonium sulfate at a concentration of 0.38 mol / L to achieve a sulfur content of 0.5 wt% after calcination, and the solvent was removed by an evaporator. Alumina Support A was then dried (120°C, 3 hours) and calcined (500°C, 3 hours) to obtain an alumina support containing 0.5 wt% sulfur.

[0214] The alumina support thus prepared was impregnated with an aqueous solution of chloroplatinic acid (the pH of the solution was adjusted to 2.0) so that the platinum loading after calcination was 0.6 wt%. Then, water was removed by an evaporator, and the resultant was dried (120° C., 3 hours) and calcined (400° C., 3 hours). Then, the resultant was charged into a flow-type hydrogen reduction apparatus and subjected to hydrogen reduction at 450° C. for 15 hours in a hydrogen flow, thereby obtaining a 0.6 wt% platinum-supported alumina catalyst. The estimated platinum particle size of the platinum-supported alumina catalyst measured by the CO pulse method was

[0215] [Comparative Example 4] (Reaction Test Method of the Eggshell Catalyst Described in Patent Document 3 and the Uniform Catalyst Described in Patent Document 4)

[0216] A comparison of the dehydrogenation reaction test method (reaction test method) and reaction test results related to the eggshell-type catalyst described in Patent Document 3 and the uniform catalyst described in Patent Document 4 is shown. Here, the dehydrogenation reaction test described in Patent Document 3 and the dehydrogenation reaction test described in Patent Document 4 differ in the conditions of reaction temperature and hydrogen concentration supplied to the raw material MCH. This is because the dehydrogenation catalyst described in Patent Document 3 and the dehydrogenation catalyst described in Patent Document 4 have different deterioration rates, and the reaction test conditions for the deterioration rate during the development of the dehydrogenation catalyst described in Patent Document 3 are conditions under which degradation is relatively difficult to proceed. Specifically, the reaction test conditions described in Patent Document 3 are as follows: reaction temperature of 300°C and hydrogen supply concentration of 20%, and the reaction conditions described in Patent Document 4 are as follows: reaction temperature of 320°C and hydrogen supply concentration of 5%. The reason is that the dehydrogenation catalyst described in Patent Document 4 is a catalyst that deteriorates slowly and is difficult to deteriorate, so the reaction test is performed under accelerated conditions that are easy to deteriorate.

[0217] In this comparative example concerning a dehydrogenation reaction test of methylcyclohexane (MCH), results of dehydrogenation reaction tests using the dehydrogenation catalyst described in Patent Document 3 as Catalyst No. 1 and using the dehydrogenation catalyst described in Patent Document 4 as Catalyst No. 2 are shown.

[0218] 10cc of each of the above catalysts was placed in a stainless steel reaction tube having an inner diameter of 12.6mm and a length of 300mm. A thermocouple protection tube with an outer diameter of 1 / 8 inch was installed at the center of the cross section of the reaction tube so that the center of the catalyst layer was located at the longitudinal center of the reaction tube. 10cc of spherical α-alumina beads with a diameter of 1mm were placed on the upper side of the catalyst as a preheating layer. Under a hydrogen flow (LHSV = 5.0; 50cc / hr), the temperature was increased until the center temperature of the catalyst layer reached 320°C. Subsequently, methylcyclohexane (MCH) was supplied to the reactor in an amount corresponding to LHSV = 2.0 (20cc / hr) using a high-speed liquid chromatography (HPLC) liquid supply pump (HPLC pump), and the hydrogen flow rate was immediately adjusted so that the hydrogen amount was 5mol% relative to the total amount of MCH and hydrogen. During the reaction, the reaction test was carried out while adjusting the output of the electric furnace so that the center temperature of the catalyst layer was 320°C.

[0219] A gas-liquid separator is provided at the outlet of the reaction tube to separate the resultant into a liquid product such as toluene and a gas such as hydrogen produced by the dehydrogenation reaction, and the collected liquid product and gas are analyzed by gas chromatography, respectively.

[0220] The MCH conversion (%), toluene selectivity (%), toluene yield (%), and generated methane concentration (ppm) were obtained 24 hours and 300 hours after the start of the reaction. The results are shown in Table 2.

[0221] Table 2

[0222]

[0223] [Example 1] (Preparation method of eggshell catalyst of the present invention and particle size measurement results)

[0224] 3900cc of a 2.67mol / L aluminum nitrate aqueous solution was prepared, along with 3900cc of a 14% ammonia solution. 20L of pure water was added to a 30L enameled container, and the container was heated to 70°C while stirring. While continuing to stir, a pH swing operation was performed four times: 1300cc of the aluminum nitrate aqueous solution was added, stirred for 5 minutes (pH = 2.0), and then 1300cc of the ammonia solution was added, stirred for 5 minutes (pH = 7.4). The resulting aqueous slurry of aluminum hydroxide was filtered to recover a filter cake, which was then washed three times in which the filter cake was redispersed in 20L of pure water and filtered again, yielding a washed gel.

[0225] The washed filter cake was air-dried, the moisture content was adjusted, and the mixture was formed into a rod with a diameter of 1.6 mm using an extruder. The resulting mixture was dried (120°C, 3 hours), crushed to a length of about 1 cm, and calcined in a muffle furnace (350°C, 3 hours) to obtain a sulfur-free alumina support A. The BET surface area of ​​the obtained alumina support A was 290 m2 / g, and the pore volume measured by mercury porosimetry was 0.61 cm3 / g. In addition, the average pore diameter of the obtained alumina support A was 9.5 nm. It has a sharp pore distribution, in which almost all pores are concentrated near the average pore diameter. In addition, the diameter is 7-11nm The volume occupied by the pores is 80% or more of the total pore volume.

[0226] The alumina support thus prepared was impregnated with an aqueous solution of chloroplatinic acid, and the pH of the solution was adjusted to 2.0 so that the platinum loading was 0.6 wt % after calcination. The water was then removed by an evaporator, and the resultant was dried (120° C., 3 hours) and calcined (350° C., 3 hours). The alumina support was then placed in a flow-type hydrogen reduction apparatus and reduced in a 400° C. hydrogen stream for 15 hours to obtain a 0.6 wt % platinum-loaded alumina catalyst (hereinafter referred to as catalyst NO.3). In the catalyst NO.3 thus obtained, the average particle size of the platinum particles measured by direct observation using an electron microscope was Table 3 shows the measurement results of the platinum particle size.

[0227] Table 3

[0228]

[0229] In Table 3, it can be seen that the smallest platinum particle is (0.8nm) in size, the largest platinum particle is (2.1nm) in size. In addition, among the 45 platinum particles measured, 40 (about 89%) of the platinum particles were between 8 and (0.8 to 1.5 nm), only 5 platinum particles are larger than (1.5nm) and the size is (1.6nm) or larger.

[0230] [Example 2] (Preparation method of uniform catalyst of the present invention and particle size measurement results)

[0231] 3900cc of a 2.67mol / L aluminum nitrate aqueous solution and 3900cc of a 14% ammonia aqueous solution were prepared. 20L of pure water was added to a 30L enameled container, and the container was heated to 70°C while stirring. While stirring, the pH was shifted four times by adding 1300cc of the aluminum nitrate aqueous solution, stirring for 5 minutes (pH = 2.0), then adding 1300cc of the ammonia aqueous solution, and stirring for 5 minutes (pH = 7.4). The resulting aqueous slurry of aluminum hydroxide was filtered to recover a filter cake, followed by three washing operations in which the filter cake was redispersed in 20L of pure water and filtered again to obtain a washed gel.

[0232] The washed filter cake was air-dried, the moisture content was adjusted, and the mixture was formed into a rod with a diameter of 1.6 mm using an extruder. The resulting mixture was dried (120°C, 3 hours), crushed to a length of about 1 cm, and calcined in a muffle furnace (350°C, 3 hours) to obtain a sulfur-free alumina support A. The BET surface area of ​​the obtained alumina support A was 290 m2 / g, and the pore volume measured by mercury porosimetry was 0.61 cm3 / g. In addition, the average pore diameter of the obtained alumina support A was 9.5 nm. It has a sharp pore distribution, in which almost all pores are concentrated near the average pore diameter. In addition, the diameter is 7-11nm The volume occupied by the pores is 80% or more of the total pore volume.

[0233] The γ-alumina support thus prepared was impregnated with an aqueous ammonium sulfate solution having a concentration of 0.38 mol / L so that the sulfur content after calcination was 0.5 wt%, and after removing the solvent with an evaporator, the resultant was dried (120° C., 3 hours) and calcined (350° C., 3 hours) to produce a sulfur-containing alumina support.

[0234] The obtained alumina support was impregnated with an aqueous solution of chloroplatinic acid (its pH was adjusted to 2.0) so that the platinum loading was 0.6 wt % after calcination. Then, water was removed by an evaporator, and the resultant was dried (120° C., 3 hours) and calcined (350° C., 3 hours). Then, the alumina support was placed in a flow-type hydrogen reduction device and reduced in a 400° C. hydrogen stream for 15 hours to obtain a 0.6 wt % platinum-loaded alumina catalyst (hereinafter referred to as catalyst No. 4). In the catalyst No. 4 thus obtained, the average particle size of the platinum particles measured by direct observation using an electron microscope was Table 4 shows the measurement results of the platinum particle size.

[0235] Table 4

[0236]

[0237]

[0238] In Table 4, the smallest platinum particle is (0.8nm) in size, the largest platinum particle is (2.2nm) in size. In addition, among the 47 platinum particles measured, 41 (about 87%) of the platinum particles were between 8 and (0.8 to 1.5 nm), only 6 platinum particles are larger than (1.5nm) and the size is (1.6nm) or larger.

[0239] [Example 3] (Results of reaction tests of the eggshell-type catalyst and the uniform catalyst of the present invention)

[0240] For the eggshell-type platinum-supported γ-alumina catalyst (catalyst No. 3) prepared under the preparation conditions of the present invention shown in Example 1 and the uniform platinum-supported γ-alumina catalyst (catalyst No. 4) prepared under the preparation conditions of the present invention shown in Example 2, a dehydrogenation reaction test of methylcyclohexane was conducted according to a method and reaction conditions similar to the method shown in Comparative Example 4. Table 5 shows the results of the dehydrogenation reaction test and the average particle size of the platinum particles measured based on direct observation of images taken with an electron microscope and the number of platinum particles with a size of The calculation results of the ratio of the number of platinum particles.

[0241] Table 5

[0242]

[0243]

[0244] As can be known from the reaction test results of Table 5, by optimizing the catalyst preparation conditions of the present invention, the platinum-loaded alumina catalyst of excellent performance (particularly catalyst life) can be obtained. Compared with the eggshell type platinum-loaded gamma-alumina catalyst (catalyst NO.1) prepared under conventional preparation conditions, the reduction of the toluene yield of the eggshell type platinum-loaded gamma-alumina catalyst (catalyst NO.3) prepared under the preparation conditions of the present invention is less, and has a long life. In addition, compared with the uniform type platinum-loaded gamma-alumina catalyst (catalyst NO.2) prepared under conventional preparation conditions, the reduction of the toluene yield of the uniform type platinum-loaded gamma-alumina catalyst (catalyst NO.4) prepared under the preparation conditions of the present invention is less, and has a long life.

[0245] Because the reaction tests in Table 5 were conducted under accelerated test conditions, the deterioration in toluene yield after approximately 300 hours was minimal. However, the deterioration under accelerated test conditions was significantly greater than that under actual commercial reaction conditions. Roughly speaking, while the lifespan of Catalyst No. 1 in Table 5 is approximately one year and that of Catalyst No. 2 is approximately two years, Catalyst No. 3 can be expected to have a lifespan of approximately three years, and Catalyst No. 4 can be expected to have a lifespan of approximately four years.

[0246] In addition, in the catalysts according to the present invention (Catalyst No. 3, Catalyst No. 4), in which the catalyst life was improved by the preparation methods shown in Examples 1 and 2, 80% or more of all the platinum particles whose particle sizes were measured by directly observing the observation images taken with an electron microscope had With catalyst NO.2 (where the particle size is within The ratio of the number of particles in the range of about 45% is compared with that in the catalyst of the present invention. The number ratio of platinum particles in the range is significantly high, and the size is The number ratio of platinum particles with a diameter of 0.04 mm or larger was significantly reduced.

[0247] It is believed that the reason why the catalyst life of the catalysts (Catalyst No. 3, Catalyst No. 4) prepared by the preparation method shown in Examples 1 and 2 of the present invention is significantly improved as described above is that the calcination conditions when preparing the γ-alumina support, the calcination conditions after impregnation with platinum (and sulfur, if necessary) and drying, and the conditions during the final hydrogen reduction are optimized.

[0248] The reason why the lifespan of conventional catalysts (i.e., the dehydrogenation catalysts described in Patent Documents 3 and 4) is impaired is believed to be that, in conventional production methods, the calcination conditions when preparing the γ-alumina support exceed 400°C, the calcination conditions after impregnation with platinum (and sulfur, if necessary) and drying are similar to those at high temperatures, and the final hydrogen reduction temperature is high, similar to the calcination conditions when preparing the support and after impregnation with platinum (and sulfur, if necessary) and drying. In particular, it has been found that in the production of the catalyst, it is more preferable to set the final hydrogen reduction temperature to 400°C or lower and to perform calcination at a temperature lower than the final hydrogen reduction condition before hydrogen reduction, thereby causing a thermal history.

[0249] In addition, the catalyst of the present invention could not be realized using electron microscopy technology that was applicable to conventional catalysts (i.e., at the time of filing the patent applications related to the dehydrogenation catalysts described in Patent Documents 3 and 4), but was realized due to the subsequent development of electron microscopy technology, wherein the development of electron microscopy technology made it possible to accurately measure the size of platinum particles of catalysts prepared under various catalyst preparation conditions by direct observation.

[0250] Industrial Applicability

[0251] The hydrogen station of the present invention using the OCH method is highly safe and can be advantageously used as a hydrogen station for filling hydrogen into a mobile body equipped with a fuel cell, such as a mobile body equipped with a fuel cell, such as an FCV, a fuel cell forklift, a fuel cell ship, etc. The OCH method is a highly safe method in which hydrogen is stored and transported in the form of MCH, which is a liquid at room temperature and pressure, and considering that it is very likely to build a large-scale hydrogen supply chain for hydrogen thermal power generation, low-cost MCH is likely to be used on a large scale for hydrogen stations. Hydrogen carriers can be transported to areas including rural areas and remote islands using railway transportation, truck transportation, and ship transportation as existing infrastructure for gasoline and kerosene transportation. Therefore, the hydrogen station using the OCH method is suitable for nationwide deployment of hydrogen stations from 2030 and beyond, and its hydrogen production method is a method suitable for future national reserves. Therefore, the method is likely to be widely used to expand the popularity of hydrogen. Therefore, the present invention has very high industrial applicability.

[0252] Reference Signs List

[0253] 1: Hydrogen Station

[0254] 3: Dehydrogenation unit

[0255] 4:MCH tank

[0256] 6: Toluene tank

[0257] 9: Compressor

[0258] 11: Accumulator

[0259] 15: Allocator

[0260] 17: Precooler

[0261] 23: Dehydrogenation reactor

[0262] 25:Heat exchanger

[0263] 26: Heating device

[0264] 27: Storage Tank

[0265] 28: Catalytic combustion coil

[0266] 28A: Fuel inlet section

[0267] 31: Gas-liquid separator

[0268] 33:PSA device

[0269] 37:Purge gas pump

[0270] 39:Purge gas tank

[0271] 41: Air supply pump

[0272] 43:Connection part

[0273] 45: Exhaust gas regulating valve

[0274] L1: Raw material supply pipeline

[0275] L3: Toluene discharge pipeline

[0276] L5-L7: Hydrogen transport pipeline

[0277] L11: Gas pipe

[0278] L13: First coolant circulation pipeline

[0279] L21: Reaction product gas pipeline

[0280] L23: Heat medium circulation pipeline

[0281] L25: Crude hydrogen transport pipeline

[0282] L31: Exhaust purge gas pipeline

[0283] L33: Purge gas supply line

[0284] L37: Air supply line

[0285] L37A: Split air supply line

[0286] L38: Tank gas discharge line

[0287] L38A: branch line

[0288] L39: Exhaust pipe

[0289] L41: Second coolant circulation line.

Claims

1. A hydrogen station comprising: a dehydrogenation reactor that generates hydrogen by dehydrogenating aromatic compounds in the presence of a dehydrogenation catalyst; a heat supply device for supplying heat to the dehydrogenation reactor via a heat medium heated by fuel; as well as a PSA unit that purifies the reaction product gas containing hydrogen generated from the dehydrogenation reactor by using an adsorbent according to a pressure swing adsorption method, The PSA unit is supplied with a purge gas containing hydrogen for regeneration of the adsorbent. The heat supply device includes a storage tank for storing the heat medium and a catalytic combustion tube, wherein the catalytic combustion tube is arranged in the storage tank so as to catalytically burn the fuel in the presence of a combustion catalyst. The catalytic combustion tube is supplied with the purge gas and air exhausted from the PSA unit as fuel, and The combustion catalyst is installed in the fuel inlet portion of the catalytic combustion tube for introducing the fuel, and the combustion catalyst includes a first catalyst and a second catalyst, the first catalyst is a platinum-supported alumina catalyst for spontaneously igniting the discharged purge gas, the platinum-supported alumina catalyst has the same structure as the dehydrogenation catalyst, and the second catalyst has a different structure from the platinum-supported alumina catalyst and is installed in a portion of the catalytic combustion tube downstream of the fuel inlet portion, The platinum-supported alumina catalyst comprises: an alumina support; and Platinum supported on the alumina carrier, Wherein, the alumina carrier comprises a surface area of ​​200m 2 / g or more, pore volume 0.50m 3 / g or more and an average pore diameter in the range of 60 to 150 Å, wherein pores with a pore diameter within the range of ±30 Å of the average pore diameter account for 60% or more of the total pore volume, 0.1 to 1.5 wt% of platinum particles, calculated as elemental platinum, are supported on the γ-alumina support, and Direct observation using transmission electron microscopy revealed that 70% or more of the platinum particles had a size between 8 and 15 Å.

2. The hydrogen station according to claim 1, wherein: The heat medium is hot oil. 3 . The hydrogen station according to claim 1 , wherein the catalytic combustion tube is supplied with air in a divided manner at a plurality of different locations.

4. The hydrogen station according to claim 1, further comprising: a distributor that supplies the hydrogen gas purified by the PSA device to a mobile body equipped with a fuel cell; a precooler that cools the hydrogen gas supplied from the distributor by using a coolant; and a gas-liquid separator, which separates the reaction product gas into gas and liquid, Wherein, in the gas-liquid separator, the reaction product gas is cooled by the coolant supplied by the precooler.

5. The hydrogen station according to claim 1, wherein: In the dehydrogenation reaction, methylcyclohexane as the hydrogenated aromatic compound is dehydrogenated to generate hydrogen and toluene. The hydrogen station also includes: a first tank for storing the methylcyclohexane; and a second tank storing the toluene, and The first tank and the second tank are both placed underground.

6. The hydrogen station according to claim 5, wherein: At least one of the gas-phase gas in the first tank and the gas-phase gas in the second tank is supplied to the catalytic combustion tube as fuel together with the purge gas exhausted from the PSA device.

7. The hydrogen station according to claim 5, wherein: At least one of the gas-phase gas in the first tank and the gas-phase gas in the second tank is introduced into a fuel inlet portion of the catalytic combustion tube into which the fuel is introduced, together with air.

8. The hydrogen station according to claim 1, wherein: The catalytic combustion tube is a coil filled with the combustion catalyst.

9. The hydrogen station according to claim 1, wherein: The hydrogenated aromatic compound is one member or a mixture of a plurality of members selected from the following: hydrides of monocyclic aromatic compounds, hydrides of bicyclic aromatic compounds, and hydrides of compounds having three or more aromatic rings.

10. The hydrogen station according to claim 1, wherein: The hydrogenated aromatic compound is one member selected from the group consisting of methylcyclohexane, cyclohexane, trimethylcyclohexane and decalin, or a mixture of a plurality of members selected from the group consisting of methylcyclohexane, cyclohexane, trimethylcyclohexane and decalin.

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