JP2007076982A - Hydrogen production system and power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen production system which can efficiently produce hydrogen capable of being used in a fuel cell with compact equipment. <P>SOLUTION: The hydrogen production system is constituted of (1) a hydrogen production apparatus for generating hydrogen from raw material oil comprising hydrocarbons mainly having cyclohexane rings by dehydrogenating the cyclohexane rings to form aromatic rings and (2) a hydrogen purification apparatus for converting aromatic hydrocarbons remaining in hydrogen into saturated hydrocarbons by the hydrogenation and/or hydrocracking after separating the aromatic hydrocarbons from the hydrogen-containing product produced by the hydrogen production apparatus. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydrogen production system and a power generation system. In particular, the present invention relates to a hydrogen production system suitable for use in a fuel cell.

  Hydrogen is widely used in various industrial fields including the oil refining and chemical industries. In particular, in recent years, hydrogen energy has attracted attention as a future energy, and research is being conducted focusing on fuel cells. However, hydrogen gas has a large volume per calorie, requires a very low temperature for liquefaction, and also requires a large amount of energy for liquefaction, so a system for storing and transporting hydrogen is an important issue. Yes. Therefore, the use of hydrogen storage metals has been proposed, but it is far from practical use. In addition, it is necessary to develop a new infrastructure for supplying hydrogen (see Non-Patent Document 1). Liquid hydrocarbons, on the other hand, have an energy density that is easier to handle than hydrogen gas, and also have the advantage of being able to use existing infrastructure, so they can be stored and transported in the form of hydrocarbons and used as needed. The method of producing hydrogen from hydrocarbons is important.

  When transported in the form of solid or liquid hydrocarbons in this way, the inconvenience of transporting gas or liquid hydrogen can be eliminated. That is, a facility or apparatus for producing hydrogen from hydrocarbons, preferably liquid hydrocarbons, is arranged at a location adjacent to or near a hydrogen consuming facility or device such as a fuel cell, and hydrogen is produced at or near the location, If the produced hydrogen is used in an adjacent or near hydrogen consuming apparatus / equipment, it is preferable because the inconvenience of storing and transporting gaseous hydrogen can be eliminated or reduced because it is transported and stored in the form of hydrocarbon. In particular, when the hydrogen consuming equipment / device is mounted on a mobile equipment / device such as an automobile, it is more preferable if the hydrogen consuming equipment / device is mounted on the mobile equipment / device to move together. Such equipment can be easily installed in a small-scale device.

  Large-scale production of hydrogen is widely performed by known techniques such as steam reforming and partial oxidation of methane and light paraffin. However, these reactions require high temperatures and complicated processes, and are generally inefficient and unsuitable for small scale production. There is a reforming reaction of methanol as a small-scale hydrogen production method, but carbon monoxide is mixed in the hydrogen obtained by this reaction, and then carbon dioxide produced by conversion and conversion of carbon monoxide. In addition, there is a disadvantage that each process of separation and removal of methane is required.

  On the other hand, in the method of producing hydrogen by dehydrogenating liquid hydrocarbons, the reaction is simple, so the number of processes related to the reaction is reduced, and the unsaturated carbonized product is liquid with hydrogen at room temperature. Since it is hydrogen, it has the feature that separation of both is easy. In particular, hydrocarbons with cyclohexane rings are used as feedstock, and the reaction to dehydrogenate the cyclohexane rings to aromatic rings is easily converted in the presence of an appropriate dehydrogenation catalyst. The rate can be almost 100%, and the separation of the product hydrogen and aromatic hydrocarbons is also easier because of the large difference in boiling point, which is suitable for small-scale hydrogen production (Non-Patent Documents) 2).

  However, in a fuel cell, particularly a polymer electrolyte fuel cell using hydrogen as a fuel, it is known that impurities contained in hydrogen affect the fuel cell. In general, when sulfur compounds, carbon monoxide, unsaturated hydrocarbons, aromatic hydrocarbons, etc. are present, it is necessary to severely limit their contents in order to poison the reaction catalyst in the fuel cell and inhibit the reaction. is there. On the other hand, light saturated hydrocarbons that are gases at room temperature under atmospheric pressure, such as methane, ethane, propane, and butane, have a very small effect and allow a considerable amount of mixing.

In a method for producing hydrogen by using hydrocarbons having liquid cyclohexane rings as raw material oil and dehydrogenating the cyclohexane rings to aromatic rings, most of the generated hydrogen and aromatic hydrocarbons can be cooled to room temperature. Aromatic hydrocarbons can be liquefied and separated from hydrogen, but an amount of aromatic hydrocarbons depending on the vapor pressure at room temperature is mixed in hydrogen gas. For example, benzene has a vapor pressure of 8 kPa at 15 ° C. and is mixed in the order of%.
As a countermeasure for this, a method of cooling and separating using a refrigerator is conceivable, but it is not preferable in that the energy consumption required for cooling is large and the energy efficiency is low, and the facility becomes large.

  As another separation method, there is an adsorption separation method in which it is adsorbed by an adsorbent and separated. In this method, it is necessary to desorb and recover the aromatic hydrocarbon from the adsorbent after adsorption and to regenerate the adsorbent. Among them, the pressure swing adsorption method (PSA method) in which adsorption and desorption are performed by pressure fluctuation is known, but the recovery rate of hydrogen gas is low, and operations such as pressure increase and decrease are necessary as a system. There is a drawback of increasing the size.

  As a separation method other than the above, there is a membrane separation method. Membrane separation is characterized by good energy efficiency. As the types of separation membranes, there are mainly palladium membranes, polymer membranes, ceramic membranes, and carbon membranes. In the purification of hydrogen, membrane separation using a polymer membrane has been put into practical use for separation from hydrocarbon gases such as carbon monoxide, nitrogen and methane. A palladium thick film has been put to practical use for the purpose of purifying high purity hydrogen. However, excluding high-purity hydrogen purification using a thick palladium membrane, the hydrogen purity purified by the membrane separation method is at most about 99.9%, and impurities of the order of several hundred ppm remain. In the separation of aromatic hydrocarbons, which is the object of the present invention, this amount cannot be used as fuel hydrogen for polymer electrolyte fuel cells. In addition, high purity hydrogen purification using a thick palladium membrane has sufficient purity, but is slow and slow in hydrogen permeation, is not efficient, requires a large amount of palladium, is expensive, and has significant resource limitations. As described above, there is a problem that there is a great demerit as equipment that enables in-vehicle use (see Non-Patent Document 3).

Nori Kobayashi, “Quarterly Energy Comprehensive Engineering”, 2003, Vol. 25, No. 4, p. 73-87 Masaru Ichikawa, “Industrial Materials”, 2003, Vol. 51, No. 4, p. 62-69 Supervised by Masayuki Nakagaki, “Membrane Processing Technology System (Vol. 1)”, Fuji Techno System, 1991, p. 661-662 and p. 922-925

  An object of the present invention is to provide an efficient hydrogen production system by combining a hydrogen production device that produces hydrogen by a small and efficient dehydrogenation reaction and a small hydrogen purification device, and also provide a power generation system. There is.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention mainly generate hydrocarbons having a cyclohexane ring as raw material oil, and dehydrogenate the cyclohexane ring into an aromatic ring to generate hydrogen. Hydrogen separation apparatus and hydrogenated and / or hydrocracked aromatic hydrocarbons remaining in hydrogen after separation of aromatic hydrocarbons produced from hydrogen-containing products produced in the hydrogen production apparatus The present invention has been completed by finding a system capable of producing hydrogen that can be efficiently used in a fuel cell by combining a hydrogen purifier that converts to saturated hydrocarbons by using the waste heat of the dehydrogenation reaction.

That is, the present invention relates to a hydrogen production system including at least the following hydrogen production apparatus and hydrogen purification apparatus.
(1) A hydrogen production apparatus that generates hydrogen by dehydrogenating a cyclohexane ring into an aromatic ring from a raw material oil mainly composed of a hydrocarbon having a cyclohexane ring.
(2) Saturated hydrocarbons are obtained by separating aromatic hydrocarbons from the hydrogen-containing product produced by the hydrogen production apparatus and then hydrogenating and / or hydrocracking the remaining aromatic hydrocarbons in hydrogen. Hydrogen purification device that converts to

The present invention also relates to a power generation system including at least the following hydrogen production apparatus, hydrogen purification apparatus, and fuel cell.
(1) A hydrogen production apparatus that generates hydrogen by dehydrogenating a cyclohexane ring into an aromatic ring from a raw material oil mainly composed of a hydrocarbon having a cyclohexane ring.
(2) Saturated hydrocarbons are obtained by separating aromatic hydrocarbons from the hydrogen-containing product produced by the hydrogen production apparatus and then hydrogenating and / or hydrocracking the remaining aromatic hydrocarbons in hydrogen. Hydrogen purification device that converts to
(3) A fuel cell to which hydrogen obtained from the hydrogen purifier is supplied.

  According to the hydrogen production system of the present invention, hydrogen that can be efficiently used in a fuel cell can be produced with a small facility.

Hereinafter, preferred embodiments of the present invention will be described.
The hydrogen production system of the present invention comprises at least a hydrogen production apparatus and a hydrogen purification apparatus, and the hydrogen production apparatus dehydrogenates the cyclohexane ring from a raw material oil mainly composed of a hydrocarbon having a cyclohexane ring to form an aromatic ring. Hydrogen is generated by the reaction.

  It is preferable to use a catalyst for this dehydrogenation reaction. Although any catalyst having dehydrogenation activity can be used as the catalyst, it is preferable to carry out the reaction in the form of a fixed bed flow type reaction using a solid catalyst. As this solid catalyst, a catalyst supporting a catalytically active main component using a metal oxide having a stable and large surface area as a carrier can be suitably used. Further, for example, a thermally conductive catalyst disclosed in JP-A No. 2002-11958 can also be preferably used.

The main component of the catalytic activity is a component having dehydrogenation activity, and can be arbitrarily selected, but is preferably Group 8 element, Group 9 element and Group 10 element of the periodic table, specifically , Iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum and the like, preferably nickel, palladium and platinum. Two or more of these elements may be combined. In the present invention, the group numbers in the periodic table are based on the International Pure and Applied Chemistry Union Inorganic Chemical Nomenclature Nomenclature 1990 Edition.
The method for supporting these catalytically active main components on the carrier is arbitrary, but the impregnation method is preferred. Specific examples include the Incipient Wetness method and the evaporation to dryness method. The elemental compound used is preferably a water-soluble salt, and is preferably impregnated as an aqueous solution. As the water-soluble compound, chloride, nitrate and carbonate are preferable.
The support is preferably a metal oxide having high mechanical strength, thermal stability and a large surface area. Specific examples include alumina, silica, titania, silica alumina, and the like, and alumina and silica are more preferable.

  Additives may coexist in the catalyst if necessary. Preferred additives include basic substances. The coexistence of the basic substance suppresses side reactions such as decomposition caused by acidity, and suppresses deterioration of the catalyst due to carbonaceous deposition. The type of basic substance is arbitrary, but compounds of Group 1 elements and Group 2 elements of the periodic table are preferred, and specifically, lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium And compounds such as barium are preferred. More preferably, it is a compound of a Group 1 element, and specifically, compounds such as lithium, sodium, potassium, rubidium, cesium and the like are preferable. As these compounds, water-soluble substances are preferable, and chlorides, sulfates, nitrates, and carbonates are more preferable. The content of the basic substance is preferably in the range of 0.1 to 100 by weight ratio with respect to the catalytically active main component. The preparation method for containing these basic substances in the catalyst is optional, but an impregnation method is preferred. Specific examples include the Incipient Wetness method and the evaporation to dryness method.

  The reactant used in the present invention is a hydrocarbon having a cyclohexane ring. Specific examples include cyclohexane, cyclohexane alkyl-substituted products, decalin, decalin alkyl-substituted products, tetralin, tetralin alkyl-substituted products, and the like. Preferred are methylcyclohexane, dimethylcyclohexane, decalin, and methyldecalin. More preferred are methylcyclohexane and dimethylcyclohexane. These hydrocarbons having a cyclohexane ring may be pure substances, or may be a mixture of a plurality of hydrocarbons. The reactants need not all be hydrocarbons having a cyclohexane ring, and may contain a certain amount of other compounds such as hydrocarbons having no cyclohexane ring.

  The products obtained by the dehydrogenation reaction are mainly hydrogen and aromatic hydrocarbons. Aromatic hydrocarbons can be recovered and hydrogenated again to return them to hydrocarbons having a cyclohexane ring as a raw material and reuse them. Alternatively, it can be used as a fuel necessary for the dehydrogenation reaction as necessary. In addition, since aromatic hydrocarbons generally have a high octane number, substances having a suitable boiling point can also be used as a gasoline base material. Alternatively, it can be used as a chemical product.

  The reaction conditions for dehydrogenation can be appropriately selected according to the type of raw material and the type of reaction. The dehydrogenation reaction from the cyclohexane ring to the aromatic ring is a reversible reaction, and conditions of high temperature and low pressure are preferable in terms of chemical equilibrium. The lower limit of the reaction pressure is preferably 0.05 MPa or more, more preferably 0.1 MPa or more, and the upper limit is preferably 1 MPa or less, more preferably 0.5 MPa or less. In the present invention, the pressure is expressed as an absolute pressure unless otherwise specified. The reaction temperature is preferably a high temperature in terms of chemical equilibrium, but a low temperature is preferable in terms of energy efficiency. The lower limit of the reaction temperature is preferably 200 ° C. or higher, more preferably 300 ° C. or higher, and the upper limit is preferably 450 ° C. or lower, more preferably 400 ° C. or lower. Although it is disadvantageous in terms of chemical equilibrium, hydrogen may be added to the raw material for the purpose of preventing the deactivation of the catalyst or for operating the apparatus. The molar ratio of hydrogen to the raw material is preferably 0.01 or more and 1 or less. The preferable range of LHSV (liquid hourly space velocity) depends on the activity of the catalyst, but is preferably 1 v / v / hr or more and 100 v / v / hr or less.

The hydrogen purifying apparatus in the present invention separates hydrocarbons from the hydrogen-containing product obtained from the hydrogen production apparatus (dehydrogenation reactor), and then hydrogenates and / or hydrogenates hydrocarbons remaining in the hydrogen. It is converted into saturated hydrocarbons by chemical decomposition. These hydrocarbons are mainly aromatic hydrocarbons, but also include unreacted feedstock.
The method for separating hydrocarbons is arbitrary, and known methods such as cooling, adsorption, and membrane separation can be adopted. However, from the viewpoint of simplicity of the apparatus, a method of liquefying hydrocarbons by cooling at about room temperature and performing gas-liquid separation is preferable. The lower limit of the pressure for separation is preferably 0.1 MPa or more, more preferably 0.2 MPa or more, and the upper limit is preferably 2 MPa or less, more preferably 1 MPa or less. The lower limit of the temperature during separation is preferably room temperature or higher, more preferably 40 ° C. or higher, and the upper limit is preferably 100 ° C. or lower, more preferably 70 ° C. or lower.

  In the present invention, separation by a hydrogen separation membrane is also preferable. The hydrogen separation membrane is preferably a ceramic membrane or a metal membrane such as a palladium membrane in terms of resistance to aromatic hydrocarbons and heat resistance. In the present invention, the ceramic membrane is preferably separated by molecular sieving. The pore size of the portion of the membrane where selective separation is performed is preferably 0.3 nm or more and 0.7 nm or less, and more preferably 0.3 nm or more and 0.5 nm or less. A known ceramic material can be used as the material of the ceramic film, but silica, alumina, titania, glass, silicon carbide, and silicon nitride are preferable. This ceramic film is usually formed on a support that mechanically holds the film. The support is preferably a porous ceramic, more preferably porous alumina, silica, or silicon nitride.

  In the case of a metal membrane, a hydrogen separation membrane in which a metal thin film is formed on the inner surface or outer surface of a tubular porous metal support having pores or a porous ceramic support having tubular pores is preferable. A metal film containing 100 to 1 mass% of palladium, or a metal film containing 80 to 10 mass% of at least one metal selected from silver, copper, vanadium, niobium, and tantalum is preferable. Although any method can be selected as the method for forming the metal thin film, specific examples include electroless plating, vapor deposition, and rolling.

  Separation conditions for membrane separation vary depending on the type of hydrocarbon used as a raw material, the performance of the separation membrane, and the required purity of hydrogen, but the pressure is preferably 0.1 MPa or more and 2 MPa or less, more preferably 0.1 MPa or more and 1 MPa or less. preferable. The differential pressure of the separation membrane is preferably from 0.01 MPa to 2 MPa, more preferably from 0.1 MPa to 1 MPa. The temperature is preferably higher than the boiling point of the hydrocarbon separated from hydrogen, that is, higher than normal temperature. Preferably they are 100 degreeC or more and 450 degrees C or less, More preferably, they are 120 degreeC or more and 400 degrees C or less. This heat source can be efficiently performed by using the heat of the reaction product of the dehydrogenation reaction. Depending on the temperature required for membrane separation, the product gas coming out of the dehydrogenation reactor may be introduced into the membrane separator at the same temperature, or after cooling to an appropriate temperature through a heat exchanger. Also good. When cooling, energy efficiency can be increased by using heat to preheat the feedstock.

  Thus, hydrocarbons mainly composed of a small amount of aromatic hydrocarbons remain in the hydrogen after separation of the aromatic hydrocarbons. The hydrogen purifier of the present invention is characterized in that this aromatic hydrocarbon is hydrogenated and converted to saturated hydrocarbon, or hydrocracked and converted to light saturated hydrocarbon.

  A catalyst is preferably used for the hydrogenation and / or hydrocracking reaction. Although any catalyst having hydrogenation activity can be used as this catalyst, it is preferable to carry out the reaction in the form of a fixed bed flow type reaction using a solid catalyst. As this solid catalyst, a catalyst supporting a catalytically active main component using a metal oxide having a stable and large surface area as a carrier can be suitably used.

  This catalytically active main component is a component having hydrogenation activity and can be arbitrarily selected, but is preferably a group 8 element, a group 9 element, or a group 10 element in the periodic table. Specific examples include iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, and the like, preferably nickel, palladium, and platinum. Two or more of these elements may be combined. The preparation method for supporting these catalytically active main components on a carrier is arbitrary, but an impregnation method is preferred. Specific examples include the Incipient Wetness method and the evaporation to dryness method. The elemental compound used is preferably a water-soluble salt, and is preferably impregnated as an aqueous solution. As the water-soluble compound, chloride, nitrate and carbonate are preferable.

  The support is preferably a metal oxide having a high mechanical strength, a thermally stable and large surface area, or a composite metal oxide, specifically, alumina, silica, titania, silica alumina, silica zirconia alumina, and the like. Alumina and silica are more preferable. Further, when hydrocracking hydrocarbons, acidic metal oxides and composite metal oxides are preferable, and specific examples include silica alumina and silica zirconia alumina.

  Additives may coexist in the catalyst if necessary. Preferable additives include acidic substances. The coexistence of the acidic substance promotes the hydrocracking reaction resulting from the acidity. The kind of the acid substance is arbitrary, but acid type zeolite and clay mineral are preferable. Preferred examples of zeolite and clay mineral include faujasite, Y zeolite, ultrastable Y zeolite (USY), mordenite, MFI zeolite, β zeolite, ferrierite, A zeolite, smectite, montmorillonite, and activated clay. More preferred are acid-type zeolites, and Y zeolite, ultrastable Y zeolite (USY), mordenite, MFI zeolite, β zeolite, and ferrierite are preferred. The content of the acidic substance is preferably in the range of 0.1 to 80% by weight with respect to the carrier.

  Aromatic hydrocarbons remaining in hydrogen are hydrogenated to become saturated hydrocarbons having a cyclohexane ring, and further hydrocracked to increase hydrogen consumption, but become lighter saturated hydrocarbons. Since these saturated hydrocarbons have little influence on the fuel cell, there is no problem even if a considerable amount is mixed.

  The reaction conditions can be appropriately selected according to the type of aromatic hydrocarbon. The hydrogenation reaction from an aromatic ring to a cyclohexane ring is a reversible reaction, and conditions of low temperature and high pressure are preferable in terms of chemical equilibrium. The hydrocracking reaction is virtually irreversible, and high temperature conditions are preferred. The lower limit of the reaction pressure is preferably 0.1 MPa, and the upper limit is preferably 1 MPa, more preferably 0.5 MPa. The reaction temperature is preferably a high temperature in terms of the reaction rate, but a low temperature is preferable from the viewpoint of increasing the energy efficiency by utilizing the heat of the reaction product after separation of the aromatic hydrocarbon. The lower limit of the reaction temperature is preferably 100 ° C, more preferably 200 ° C, and the upper limit is preferably 400 ° C, more preferably 350 ° C. The preferable range of LHSV (liquid hourly space velocity) depends on the activity of the catalyst, but is preferably 1 v / v / hr or more and 100 v / v / hr or less.

  This heat source can be efficiently performed by using the heat of the reaction product after separating the aromatic hydrocarbon. Depending on the temperature required for the hydrogenation and / or hydrocracking reaction, the product gas after separation of the aromatic hydrocarbons may be introduced into the hydrogenation and / or hydrocracking reactor at the same temperature, It may be introduced after cooling to an appropriate temperature through a heat exchanger. When cooling, energy efficiency can be increased by using heat to preheat the feedstock. Conversely, the cooled product may be reacted by heating.

  FIG. 1 shows a preferred example of a hydrogen production system using a hydrogen separation membrane. In this example, it is assumed that methylcyclohexane (MCH) is used as the feedstock, but it is also useful when other hydrocarbons having a cyclohexane ring are used as the feedstock. The raw material oil is preheated from the raw material oil tank 1 via the pump 2 in the heat exchanger 27 by the non-permeating gas of the membrane separator. Further, after being preheated by the permeation gas of the membrane separator in the heat exchanger 28, it is heated by the heater 12 and the reaction occurs in the dehydrogenation reactor 13. The produced hydrogen and aromatic hydrocarbons are mixed with recycled hydrogen gas and separated by the membrane separator 14. The non-permeate gas containing a small amount of hydrogen (containing a large amount of aromatic hydrocarbons) is heated by the heat exchanger 27 and then cooled by the cooler 23 and is separated into the gas and liquid by the separator 24. The separated aromatic hydrocarbon is recovered in the aromatic hydrocarbon tank 3. The gas separated by the separator 24 is pressurized by the compressor 25, mixed with the product gas before the membrane separator 14, and recycled. If necessary, a part thereof is recycled to the heater 12 via a broken line. On the other hand, the permeate gas (product gas) obtained in the membrane separator 22 is converted into raw material oil in the heat exchanger 28 after hydrogen and / or hydrocracked in a small amount of toluene contained in the hydrogenation (cracking) device 15. Heat is applied to product hydrogen. If necessary, it may be further cooled.

  FIG. 2 shows a preferred example of a hydrogen production system that separates hydrogen by cooling. The raw material oil is preheated from the raw material oil tank 1 via the pump 2 by the product in the heat exchanger 27. Further, after being preheated with product hydrogen in the heat exchanger 28, it is heated by the heater 12, and the reaction occurs in the dehydrogenation reactor 13. The produced hydrogen and aromatic hydrocarbons are cooled by the heat exchangers 29 and 27, cooled by the cooler 23, and separated into gas and liquid by the separator 24. The separated aromatic hydrocarbon is recovered in the aromatic hydrocarbon tank 3. The gas separated by the separator 24 is heated by a heat exchanger 29, and then a small amount of toluene contained in the hydrogenation (cracking) apparatus 15 is hydrogenated and / or hydrocracked. To give product hydrogen.

  FIG. 3 shows a preferred example of a power generation system using a hydrogen separation membrane. Although it is substantially the same as FIG. 1, power is generated by sending product hydrogen to the fuel electrode of the fuel cell. Light saturated aliphatic hydrocarbons contained in a small amount in the product hydrogen pass through the fuel electrode of the fuel cell to become bleed hydrogen, which is burned together with the hydrogen gas obtained from the gas-liquid separator 24 and used for heating the reactor. In this way, the compressor 25 required in FIG. 1 is not necessary and the structure can be simplified.

  FIG. 4 shows a preferred example of a power generation system that separates hydrogen by cooling. Although it is generally the same as FIG. 2, power is generated by sending product hydrogen to the fuel electrode of the fuel cell. Light saturated aliphatic hydrocarbons contained in a small amount of product hydrogen pass through the anode of the fuel cell to become bleed hydrogen, which is burned and used to heat the reactor. In this way, the structure can be simplified. In addition, when only the bleed hydrogen gas is insufficient for heating the heater 12 and the dehydrogenation reactor 13, raw material oil or recovered aromatic hydrocarbon can be used as fuel.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example and a comparative example, this invention is not limited to the range of an Example.

<Comparative Example 1>
(Dehydrogenation reaction and cooling separation)
A reaction tube having an inner diameter of 9.5 mm was charged with 2 g of a commercially available catalyst in which 0.3 mass% of platinum was supported on a spherical γ-alumina carrier having an average diameter of 1.5 mm. At the center of the reaction tube, an inner tube with a diameter of 1.6 mm is inserted for temperature measurement, and a thermocouple with a thickness of 0.8 mm is inserted into the inner tube and fixed at the center height of the catalyst layer. Then, the temperature of the catalyst layer was measured. A vaporizer was provided at the inlet of the reaction tube so that methylcyclohexane as a raw material oil could be vaporized and supplied to the reaction tube. A receiver was provided at the outlet of the reaction tube, and a 5 ° C refrigerant was circulated and cooled to collect the liquid product. The generated gas was also collected and analyzed by measuring the flow rate using a gas meter.

  After reducing the catalyst with hydrogen at 300 ° C. for 1 hour, methylcyclohexane was passed through the vaporizer at a rate of 0.22 ml / min to initiate the reaction. The reaction temperature was set to 370 ° C., and the pressure was set to 0.4 MPa. After the reaction started, the supply of hydrogen was stopped. One hour after the start of the reaction, the liquid product once collected in the receiver was extracted, and the liquid product in a steady state was collected again from that point. A gas was sampled and the amounts of hydrogen, methylcyclohexane, toluene and decomposition products in the gas were measured by gas chromatography. The liquid product in the receiver was also analyzed using a gas chromatograph. The reaction results are shown in Table 1. The conversion was 100%, the product was toluene, and a very small amount of methane by-product was observed. The amount of toluene in the gas in hydrogen was 1.7 vol%, and the hydrogen purity was 98.3 vol% in the separation by cooling (refrigerant temperature 5 ° C.).

(Fuel cell power generation evaluation)
An evaluation test was performed using an evaluation apparatus for a single cell of a polymer electrolyte fuel cell. The cell temperature is set to 80 ° C. First, pure hydrogen is supplied to the fuel electrode side, air is supplied to the air electrode side, and the hydrogen utilization rate is 60%, the oxygen utilization rate is 40%, and the current density is 0.5 A / cm ^2. It was in a state. The electromotive force at this time was measured. Thereafter, the experiment was performed by switching pure hydrogen to a gas in which 1.7 vol% toluene was mixed in hydrogen. After 10 minutes, the electromotive force dropped to 72% compared to pure hydrogen.

<Comparative example 2>
(Dehydrogenation and membrane separation)
Using the dehydrogenation reaction apparatus used in Comparative Example 1, a membrane separation experiment apparatus was combined with a membrane separation experiment apparatus instead of the receiver. The ceramic membrane used for membrane separation has a structure in which the outer surface of a tubular support made of porous alumina is coated with a silica membrane, and the silica membrane has fine pores of 0.4 nm. Separation was performed in such a manner that hydrogen permeated from the outside to the inside of the tube.
The dehydrogenation reaction was performed under the same conditions as in Comparative Example 1, and the obtained product was fed to a membrane separation experimental apparatus. The pressure on the inlet side is 0.4 MPa (absolute pressure), the pressure on the permeate outlet side is atmospheric pressure, the differential pressure is 0.3 MPa, 300 ° C., the product gas of the dehydrogenation reaction of Comparative Example 1 is flowed and separated. The experiment was conducted. The results are shown in Table 1. The toluene concentration in the permeated hydrogen gas was 0.5 vol%, and the hydrogen purity was 99.5 vol%.
(Fuel cell power generation evaluation)
An evaluation experiment was conducted in the same manner as in Comparative Example 1 except that a gas in which 0.5 vol% toluene was mixed in hydrogen was used instead of a gas in which 1.7 vol% toluene was mixed in hydrogen. After 10 minutes from gas switching, the electromotive force dropped to 78% compared to pure hydrogen.

<Example 1>
(Dehydrogenation reaction and cooling separation)
The dehydrogenation reaction was performed under the same conditions as in Comparative Example 1. The conversion was 100%, the amount of toluene in the hydrogen gas was 1.7 vol%, and the hydrogen purity was 98.3 vol%.
(Hydrogenation reaction)
A gas in which 1.7 vol% of toluene was mixed with hydrogen was passed through the hydrogenation reaction apparatus to carry out the reaction. 2 g of a catalyst in which 1 mass% of platinum was supported on a spherical silica support having an average diameter of 1.5 mm was used. The temperature was 250 ° C. Toluene was not detected in the resulting product gas, and the product was only methylcyclohexane, 1.8% by volume of methylcyclohexane and 98.2% by volume of hydrogen.
(Fuel cell power generation evaluation)
An evaluation experiment was conducted in the same manner as in Comparative Example 1 except that a gas in which 1.8 vol% methylcyclohexane was mixed in hydrogen instead of a gas in which 1.7 vol% toluene was mixed in hydrogen. Ten minutes after gas switching, the electromotive force was 98% compared to pure hydrogen.

<Example 2>
(Dehydrogenation and membrane separation)
The dehydrogenation reaction and membrane separation were performed under the same conditions as in Comparative Example 2. The toluene concentration in the permeated hydrogen gas was 0.5 vol%, and the hydrogen purity was 99.5 vol%.
(Hydrolysis reaction)
A gas in which 0.5 vol% of toluene was mixed with hydrogen was passed through the hydrocracking reaction apparatus to carry out the reaction. As the catalyst, 2 g of a catalyst having a composition of 39 mass% of γ-alumina, 39 mass% of USY zeolite (SiO ₂ / Al ₂ O ₃ ratio 6), and ₂ mass% of platinum was used. The temperature was 300 ° C. Toluene was not detected in the obtained product gas, and the product contained methane, a very small amount of ethane, and propane, which were 3.6% by volume of methane and 96.4% by volume of hydrogen.
(Fuel cell power generation evaluation)
An evaluation experiment was conducted in the same manner as in Comparative Example 1 except that a gas in which 3.6 vol% of methane was mixed in hydrogen was used instead of a gas in which 1.7 vol% of toluene was mixed in hydrogen. Ten minutes after gas switching, the electromotive force was 99% compared to pure hydrogen.

  As shown in Table 1, in Example 1 and Example 2 in which toluene remaining in the dehydrogenation reaction was converted to methylcyclohexane and methane by hydrogenation reaction or hydrogenolysis reaction, compared to Comparative Example 1 and Comparative Example 2, The decrease in fuel cell power generation evaluation is small.

An example of a hydrogen production system using a hydrogen separation membrane will be shown. The example of the hydrogen production system which isolate | separates hydrogen by cooling is shown. An example of a power generation system using a hydrogen separation membrane is shown. The example of the electric power generation system which isolate | separates hydrogen by cooling is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw material oil tank 2 Pump 3 Aromatic hydrocarbon tank 12 Heater 13 Dehydrogenation reactor 14 Membrane separator 15 Hydrogenation (decomposition) device 23 Cooler 24 Separator 25 Compressor 27 Heat exchanger 28 Heat exchanger 29 Heat exchanger

Claims (2)

A hydrogen production system comprising at least the following hydrogen production apparatus and hydrogen purification apparatus.
(1) A hydrogen production apparatus that generates hydrogen by dehydrogenating a cyclohexane ring into an aromatic ring from a raw material oil mainly composed of a hydrocarbon having a cyclohexane ring.
(2) Saturated hydrocarbons are obtained by separating aromatic hydrocarbons from the hydrogen-containing product produced by the hydrogen production apparatus and then hydrogenating and / or hydrocracking the remaining aromatic hydrocarbons in hydrogen. Hydrogen purification device that converts to A power generation system comprising at least the following hydrogen production apparatus, hydrogen purification apparatus, and fuel cell.
(1) A hydrogen production apparatus that generates hydrogen by dehydrogenating a cyclohexane ring into an aromatic ring from a raw material oil mainly composed of a hydrocarbon having a cyclohexane ring.
(2) Saturated hydrocarbons are obtained by separating aromatic hydrocarbons from the hydrogen-containing product produced by the hydrogen production apparatus and then hydrogenating and / or hydrocracking the remaining aromatic hydrocarbons in hydrogen. Hydrogen purification device that converts to
(3) A fuel cell to which hydrogen obtained from the hydrogen purifier is supplied.

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