JP4907210B2 - Hydrogen storage and transport system - Google Patents

Description

  Hydrogen storage system equipped with hydrogenation reaction device for producing hydrogenated aromatic compound (hydrogen supplier) by carrying out hydrogenation reaction of aromatic compound (hydrogen store), and hydrogenated aromatic compound obtained as hydrogen A hydrogen supply system comprising a hydrogenated aromatic compound transport means for transporting to a use site, a dehydrogenation reaction apparatus for producing hydrogen and an aromatic compound by a dehydrogenation reaction of the transported hydrogenated aromatic compound, and a recovered The recovered aromatic transport means transports the recovered aromatic compound to the hydrogen storage system again, hydrogenates the aromatic compound with hydrogen to produce the hydrogenated aromatic compound, and stores and / or transfers hydrogen. And a hydrogen storage and transport system by an organic chemical hydride method for producing and using hydrogen by dehydrogenation of a hydrogenated aromatic compound in a dehydrogenation reactor, The performance of the hydrogenation catalyst utilized in the dehydrogenation catalyst and hydrogenated apparatus utilized in the hydrogen reactor regarding storage transport system hydrogens can be maintained stably for a long period of time.

  In recent years, development and practical application of hydrogen energy utilization technology for stationary fuel cells, hydrogen vehicles, fuel cell vehicles, etc. has progressed, and hydrogen as fuel is supplied to these stationary fuel cells, hydrogen vehicles, fuel cell vehicles, etc. Development of hydrogen storage and transport technology is underway. In addition, the development of a hydrogen station as an infrastructure for supplying hydrogen to fuel cell vehicles is in the demonstration stage. The hydrogen station is an on-site hydrogen station that obtains hydrogen by reforming fossil fuels such as methanol and naphtha in the station. It is roughly classified into an off-site type hydrogen station that compresses or liquefies hydrogen such as electrolytic byproduct hydrogen and transports it to the station.

However, in the former on-site hydrogen station, a large amount of carbon monoxide (CO) is by-produced during reforming, so that a considerable amount of carbon dioxide (CO ₂ ) is inevitably discharged in the end. There is. And the main purpose of converting primary energy to secondary energy hydrogen is not only to suppress the emission of sulfur compounds and nitrogen compounds, but also to suppress the emission of carbon dioxide, which is a warming gas. It is considered that the first purpose is to control the emission of methane. Therefore, reforming fossil fuels at geographically dispersed hydrogen stations is not preferable from the viewpoint of suppressing carbon dioxide emissions.

  In the latter off-site type hydrogen station, hydrogen is transported from the outside. As a method for transporting hydrogen, a compressed hydrogen method or a liquid hydrogen method that has been put into practical use has been studied. ing. As for compressed hydrogen, hydrogen transport using a 700 atm high pressure vessel has recently been studied. However, the use of extremely high pressure is considered to be potentially dangerous, and the volume is also high at 700 atm high pressure. Storage density is not enough. In addition, since liquid hydrogen needs to maintain an ultra-low temperature of −253 ° C., it is considered to have high potential danger as well, and the problem is that hydrogen loss due to boil-off is large. For this reason, research and development aimed at hydrogen storage and transport technology with high storage efficiency and low potential danger has been vigorously conducted.

  In recent years, the organic chemical hydride method has attracted attention among the hydrogen storage and transport technologies that have been researched and developed. The organic chemical hydride method converts aromatics such as toluene into hydrogenated aromatic compounds such as methylcyclohexane (MCH) that have been hydrogenated by chemical reactions with stored hydrogen, resulting in a liquid state of chemical products at room temperature and pressure. This is a method for storing and transporting hydrogen energy in which hydrogen is stored and transported and hydrogen is generated by dehydrogenation at the place of use. Since hydrogen can be stored and transported as a chemical at room temperature and normal pressure, there are many parts where existing infrastructure can be used, and there is less potential danger, compared to the compressed hydrogen method and liquid hydrogen method. Both volume storage density and mass storage density are high. "Hydrogen Energy Cutting Edge Technology" (supervised by Tokio Ota) NTS Publishing Co. (1995) uses this method to produce hydrogen using abundant hydroelectric power from Canada and transport it across Europe to Europe. In the Euro-Québec project, it was introduced that the MTH method was studied, which can be hydrogenated and transported as methylcyclohexane.

  However, in such an MTH system, a hydrogenation reaction of an aromatic compound to hydrogenate an aromatic compound such as toluene to form a hydrogenated aromatic compound and hydrogen from the hydrogenated aromatic compound to store hydrogen. Dehydrogenation of the hydrogenated aromatic compound is required to remove the hydrogen, and the hydrogenation reaction of the former aromatic compound is technically easy with many industrial achievements, but the latter hydrogenated aromatic Since there was no catalyst that stably maintained the performance of the dehydrogenation reaction of the compound, the hydrogen energy storage and transport system based on the MTH method in the Euro-Québec project was not technically established.

  J. Catalysis, 88, 150 (1984), AIChE Journal, 31, (12), 1997 (1985), Ind. Eng. Chem. Fundam., 24, (4), 433 (1985), J. Catalysis, 107 , (2), 490 (1987) describe that the dehydrogenation catalyst at that time had a catalyst life of several hours to several tens of hours due to remarkable deterioration of activity due to carbon deposition. However, the development of a dehydrogenation catalyst that operates stably over a long period of time disclosed in Japanese Patent Application Laid-Open No. 2005-211,845 has a prospect for technical establishment of this method. Vol. 35, No. 12, 16-16 (2005), “Fine Chemical” Vol. 35, No. 1, 5-13 (2006), PETROTECH, Vol. 29, No. 2, 34-41 (2006) It is introduced as the hydride method (OCH method: Organic Chemical Hydride Method).

  Japanese Patent Laid-Open No. 2004-299,924 discloses a reaction in which a heat medium is introduced into a multi-tube heat exchanger type reactor for the purpose of efficiently giving heat necessary for a dehydrogenation reaction which is an endothermic reaction to a catalyst. A vessel is disclosed. In addition, fuel cell vehicles are being developed with a development target of 500 km continuous running with 5 kg of hydrogen. However, it is difficult to run 500 km continuously with hydrogen using the compressed hydrogen method at 700 atm. It is said that it is necessary to review the mounting method.

  Further, JP-A-2005-216,774 discloses a system in which organic hydride is directly mounted on a fuel cell vehicle and hydrogen is generated on-board. According to the OCH method, methylcyclohexane (MCH) required for storing 5 kg of hydrogen is 110 L, and the amount of toluene recovered after dehydrogenation is 90 L. Since it is mounted on the vehicle as a liquid at normal temperature and normal pressure, the shape of the tank can be used freely, and the dehydrogenation catalyst required to generate 1 kg of hydrogen per hour may be 11 L. The dehydrogenation reaction requires heat input at a reaction temperature of 300 to 320 ° C. When this is covered by the power generated by the fuel cell, the required theoretical power is about 10 KWh.

  However, in order to demonstrate excellent catalytic performance practically in hydrogen stations, on-board fuel cell vehicles, etc., when hydrogenated aromatics that store hydrogen on an industrial scale are used as raw materials, It is necessary to grasp the influence of impurities contained in the catalyst on the life of the dehydrogenation catalyst, and to have specific means for efficiently removing impurities that cause catalyst deterioration, and the establishment of such means was desired. .

J. Catalysis, 88, 150 (1984) AIChE Journal, 31 Ind.Eng.Chem.Fundam., 24, (4), 433 (1985) J. Catalysis, 107, (2), 490 (1987) Japanese Unexamined Patent Publication No. 2005-211,845 JP 2004-299,924 JP 2005-216,774

  Therefore, the present inventors have a high storage efficiency of hydrogen, can store hydrogen as a liquid at normal temperature and normal pressure, and without losing the advantages such as less potential danger. In order to make it possible to stably operate a hydrogen storage and transport system using an organic chemical hydride method that can easily store and transport hydrogen without complicating control over a long period of time, As a result of quantitatively examining the effect of impurities in the product on the life of the dehydrogenation catalyst when conducting a hydrogenation reaction, and intensive investigations on an efficient method for removing impurities, hydrogenation for hydrogenating aromatic compounds Reactor, hydrogen storage / transfer device for storing / transporting the obtained hydrogenated aromatic compound, dehydrogenation reaction device for dehydrogenating the hydrogenated aromatic compound, and aroma for storing / transporting the obtained aromatic compound By installing a removal device such as a distillation device for the specific inhibitor which becomes a poison for the catalyst and inhibits the dehydrogenation reaction and hydrogenation reaction in the system consisting of the compound storage and transfer device, it is easy to inhibit the reaction. It is found that the catalyst for the hydrogenation reaction and the catalyst for the dehydrogenation reaction can be stably operated for a long period of time, and the hydrogen storage and transport system can be stably operated for a long period of time. The present invention has been completed.

  Accordingly, an object of the present invention is to reduce the advantages such as high hydrogen storage efficiency, hydrogen storage as a liquid at normal temperature and normal pressure, and less potential danger, and the structure of the reactor. It is an object of the present invention to provide a system capable of easily storing and transporting hydrogen energy by an organic chemical hydride method (OCH method) without complicating control and control.

  In addition, another object of the present invention is to identify an inhibitor that becomes a poisoning substance for a catalyst used in a hydrogenation reaction and a catalyst used in a dehydrogenation reaction and inhibits the dehydrogenation reaction and the hydrogenation reaction. By providing the system with a removal device such as a distillation device that removes the catalyst, the life of the catalyst used in the hydrogenation reaction and dehydrogenation reaction is extended, and a hydrogen energy storage and transportation system that can be operated at low cost over a long period of time is provided. There is.

That is, the present invention relates to a hydrogen storage system equipped with a hydrogenation reaction apparatus for producing a hydrogenated aromatic compound (hydrogen supply body) by performing a hydrogenation reaction of an aromatic compound (hydrogen storage body), and the obtained hydrogen Hydrogen equipped with hydrogenated aromatic compound transport means for transporting the hydrogenated aromatic compound to a place where hydrogen is used, and a dehydrogenation reactor for producing hydrogen and the aromatic compound by dehydrogenation of the transported hydrogenated aromatic compound A supply system and a recovered aromatic transport means for transporting the recovered aromatic compound back to the hydrogen storage system are provided. Hydrogenated aromatic compounds are produced by hydrogen to produce hydrogenated aromatic compounds, and hydrogen is stored. Storage of hydrogen by an organic chemical hydride method in which hydrogen is produced by dehydrogenation reaction of a hydrogenated aromatic compound in a dehydrogenation reactor after being transferred and / or used. In the transmission system,
The aromatic compound used as the hydrogen storage is a monocyclic aromatic or a bicyclic aromatic, and the dehydrogenation catalyst has a surface area of 150 m ² / g or more and a pore volume of 0.40 cm ³ / g or more. Further, platinum, palladium, rhodium, iridium and ruthenium are added to a porous γ-alumina support having an average pore diameter of 90 to 300 mm and a ratio of pores having an average pore diameter of ± 30 mm to the total pore volume of 50% or more. A catalyst supporting at least one kind of catalytic metal selected from
Within the system, downstream of the hydrogenation reactor, poisoning of hydrogenation catalyst generated in the system-based is used in the dehydrogenation catalyst and / or hydrogenated apparatus utilized in the dehydrogenation reactor to remove the reaction inhibiting substance inhibiting dehydrogenation and / or hydrogenation reaction I Do with the substance, the reaction inhibiting substance removing device is provided to maintain the reaction inhibiting substance concentration in the system based on 100ppm or less Hydrogen storage and transport system .

Further, in the present invention, at least one catalytically active metal selected from nickel, platinum, palladium, rhodium, iridium, and ruthenium is selected from alumina, silica alumina, and silica as a hydrogenation catalyst used in the hydrogenation apparatus. At least one catalytically active metal selected from nickel, platinum, palladium, rhodium, iridium, and ruthenium as a dehydrogenation catalyst used in a dehydrogenation apparatus. Using a dehydrogenation catalyst that is supported on a catalyst carrier selected from alumina, silica alumina, and silica, and aromatic compounds used as hydrogen storage materials such as monocyclic aromatics such as toluene and benzene, or 2 such as naphthalene This is a hydrogen storage and transport system using ring aromatics.

Furthermore, in the present invention, when the aromatic compound used as a hydrogen storage material is a monocyclic aromatic compound such as toluene or benzene, a polymerization product of a dimer or trimer of a 6-membered ring compound In addition, when a dimer of a 5-membered ring compound or a polymerization product of a trimer or more is a reaction inhibitor and the aromatic compound used as a hydrogen reservoir is a bicyclic aromatic compound such as naphthalene, 6 In addition to a dimer or trimer polymerization product of a membered ring compound and a dimer or trimer or higher polymerization product of a five membered ring compound, a dimer or trimer of a bicyclic aromatic compound The concentration of the reaction inhibitory substance in the system is determined by specifying that the above polymerization products are reaction inhibitory substances and removing these reaction inhibitory substances outside the system using a simple distillation apparatus having 2 to 4 theoretical plates. To 100 ppm or less, preferably 50 ppm or less, more preferably 10 ppm or less Performing dehydrogenation Te, a storage transportation system of hydrogen by an organic chemical hydride method.

Furthermore, in the present invention, the dehydrogenation catalyst used in the dehydrogenation reactor has a surface area of 150 m ² / g or more, a pore volume of 0.40 cm ³ / g or more, an average pore diameter of 90 to 300 kg, and a total pore volume. On the other hand, a porous γ-alumina carrier in which the proportion of pores having an average pore diameter of ± 30 mm is 50% or more is loaded with at least one catalyst metal selected from platinum, palladium, rhodium, iridium and ruthenium. If necessary, this porous γ-alumina support is a system for storing and transporting hydrogen by an organic chemical hydride method using a dehydrogenation catalyst supporting an alkali metal in addition to a catalyst metal.

  In the present invention, the hydrogenation reaction apparatus that performs a hydrogenation reaction of an aromatic compound (hydrogen storage body) to generate a liquid hydrogenated aromatic compound (hydrogen supply body) at room temperature and normal pressure is preferably hydrogen It is often attached to a hydrogen supply engine that can supply hydrogen and supply hydrogen, for example, primary energy such as natural energy such as hydropower, wind power and geothermal, and fossil fuel such as coal, oil and natural gas. Is easy to obtain, hydrogen electrolysis equipment, hydrogen by-product equipment equipped with hydrogen by-product equipment such as steam reformer, and hydrogen provided to supply hydrogen to off-site hydrogen stations It is attached to a hydrogen supply engine equipped with manufacturing facilities.

  In this hydrogenation reactor, the hydrogenated aromatic compound is hydrogenated with hydrogen to form a hydrogenated aromatic compound that is a hydrogen supplier. Store as a family compound. The hydrogenation reaction of this aromatic compound is carried out, for example, with an aromatic compound such as benzene, toluene, xylene, naphthalene, methylnaphthalene, anthracene, etc. at 150 ° C. to 250 ° C., preferably 160 ° C. to 220 ° C., pressure 0.1 MP It is carried out by contacting with a hydrogenation catalyst together with hydrogen under the conditions of 5MP or less, preferably 0.5MP or more and 3MP or less. As the hydrogenation catalyst used here, typically, platinum, nickel, palladium, rhodium, Examples thereof include a catalyst in which an active metal such as iridium or ruthenium is supported on a support such as alumina, silica, or silica alumina.

  In addition, a dehydrogenation reaction apparatus for producing hydrogen and an aromatic compound by dehydrogenation of a hydrogenated aromatic compound is preferably attached to a hydrogen consuming engine that consumes hydrogen, for example, power generation using hydrogen as a fuel. It is attached to a hydrogen consuming engine such as a power generation facility equipped with a fuel cell, a hydrogen station that supplies hydrogen as a fuel to a stationary fuel cell, a hydrogen vehicle, a fuel cell vehicle, and the like.

  In the present invention, the hydrogenated aromatic compound obtained in the hydrogenation reaction apparatus is used to store and transport hydrogen energy prior to the dehydrogenation reaction in the dehydrogenation reaction apparatus. Stored and / or transported. Specifically, the storage and / or transfer means performed by the hydrogen storage / transfer apparatus includes a storage tank at a hydrogen storage place, a storage tank attached to a transfer vehicle or a transfer ship as a transport means, and In addition to the case where the storage tank is configured at the transfer destination, it is also possible to transport by a pipe such as a pipeline connecting the hydrogen storage system in the hydrogen storage place and the hydrogen supply system in the hydrogen supply place. In addition, the hydrogen storage system and the hydrogen supply system need not be installed at different sites. If hydrogen storage and transportation is required on the same site, both systems may be installed on the same site. .

  In the present invention, in the dehydrogenation reaction apparatus, hydrogen and an aromatic compound are produced by a dehydrogenation reaction of a hydrogenated aromatic compound (hydrogen supplier), and the hydrogen is used in a hydrogen consuming engine and an aromatic compound ( Hydrogen storage body) is recovered by the aromatic compound storage / transfer device. This dehydrogenation reaction of the hydrogenated aromatic compound is performed by, for example, a hydrogenated aromatic compound such as cyclohexane, methylcyclohexane, dimethylcyclohexane, tetralin, decalin, methyldecalin, tetradecahydroanthracene, preferably cyclohexane, methylcyclohexane, decalin or It is carried out by bringing methyl decalin into contact with a dehydrogenation catalyst at 200 ° C. or higher and 350 ° C. or lower, preferably 280 ° C. or higher and 330 ° C. or lower.

In the present invention, the dehydrogenation catalyst used for the dehydrogenation reaction of this hydrogenated aromatic compound is a surface area of 150 m ² / g or more, a pore volume of 0.40 cm ³ / g or more, an average pore diameter of 90 to 300 mm, At least one catalyst metal selected from platinum, palladium, rhodium, iridium and ruthenium is added to a porous γ-alumina support in which the proportion of pores having an average pore diameter of ± 30 mm with respect to the pore volume is 50% or more. A supported catalyst is used.

In the dehydrogenation catalyst used in the present invention, the porous γ-alumina support used as the catalyst support has a surface area of 150 m ² / g or more, preferably 200 m ² / g or more, and a pore volume of 0.40 cm ³ / g or more. , Preferably 0.65 cm ³ / g or more, an average pore diameter of 90 to 300 mm, preferably 90 to 200 mm, and an occupation ratio of pores having an average pore diameter of ± 30 mm is 50% or more, preferably 80 When the surface area is less than 150 m ² / g, the activity after the catalyst is not sufficient, and when the pore volume is less than 0.40 cm ³ / g, the active metal component is uniformly supported. When the average pore diameter is smaller than 90 mm, the surface area becomes large, but the pore volume becomes extremely small. On the contrary, when the average pore diameter is larger than 300 mm, the surface area becomes extremely small, and the pore volume becomes extremely small. These will grow As a result of comprehensively considering the above correlation, an average pore diameter of 90 to 300 mm is appropriate. Further, when the occupation ratio of pores having an average pore diameter of ± 30 mm is less than 50%, the effect of the present invention is reduced in catalyst performance.

  The reason for using such an alumina carrier having specific physical properties is that the pore distribution is uniformly controlled and the pore size is concentrated in the range of 90 to 300 mm throughout the carrier. This is because impregnation with platinum or potassium is performed uniformly and the dispersion state is improved. The pore distribution control of the alumina support is originally performed on the catalyst support of the process mainly for heavy oils with a large molecular size for the purpose of improving the diffusion of reaction substrates and products. It was. However, recently, it has been found that by uniformly controlling the pore distribution of the alumina support, the surface can be coated with a supported metal and the impregnation of the supported metal can be carried out satisfactorily (Yoshiaki Okada, Kenichi Imagawa, Sachio Asaoka) , Journal of Petroleum Society, Vol.44, No.5, 277-285 (2001)).

  In completing the dehydrogenation catalyst of the present invention, a catalyst was prepared using an alumina support in which the pore distribution was not uniformly controlled and an alumina support in which the pore distribution was uniformly controlled by pH swing operation. As a result of examining the degree of reaction and the reaction results, it was found that the catalyst with controlled pore distribution of the alumina support was superior in both the degree of dispersion and the reaction result, and the alumina support having specific physical properties was adopted.

  Such a porous γ-alumina carrier having specific physical properties is obtained by filtering and washing a slurry of aluminum hydroxide produced by neutralization of an aluminum salt, as disclosed in, for example, Japanese Patent Publication No. 6-72,005. The obtained alumina hydrogel is dehydrated and dried and then calcined at 400 to 800 ° C. for about 1 to 6 hours. Preferably, the pH value of the alumina hydrogel is adjusted to the alumina hydrogel dissolution pH region and the boehmite gel precipitation. It is obtained through a pH swing process in which an alumina hydrogel-forming substance is added to grow an alumina hydrogel crystal when the pH is changed between at least one of the pH ranges and from one pH range to the other. It is good to be. The porous γ-alumina support obtained through this pH swing process is excellent in the uniformity of pore distribution, there is little variation in physical properties even in the alumina support pellets after molding, and the physical properties of each pellet are stable. It is excellent in that it is.

  The catalyst metal supported on the porous γ-alumina carrier having such specific physical properties is preferably one or more metals selected from platinum, palladium, rhodium, iridium and ruthenium, Is platinum, and for example, when the catalyst metal is platinum, it is 0.3 wt% or more and 2.0 wt% or less, preferably 0.5 wt% or more and 1.0 wt% or less. If the supported amount of platinum is less than 0.3% by weight, there is a problem that the activity is low. On the other hand, if it is more than 2.0% by weight, the particle size of platinum becomes large, the selectivity is lowered and sintering is performed. There is a problem that it is easy to deteriorate.

  In addition, when the noble metal such as platinum or palladium is impregnated and supported on the alumina support, the degree of dispersion of the noble metal after the firing and supporting varies depending on the pH of the impregnating aqueous solution. In the present catalyst system using an alumina support having specific physical properties, the optimum pH range is in the range of 1.8 to 3.0. When the pH value of the impregnation solution is lower than 1.8, the degree of dispersion of the noble metals after loading is low, and when the pH value is higher than 3.0, the degree of dispersion also decreases. This is presumed that the adsorption force of the metal compound molecules on the alumina support differs depending on the pH value at the time of impregnation, and has a great influence on sintering during particle growth.

  Further, the degree of dispersion of the noble metal tends to decrease due to the subsequent supporting of the alkali metal, but the alkali metal is adjusted by adjusting the pH value at the time of impregnation with the noble metal to the range of 1.8 to 3.0. It is possible to minimize the decrease in the degree of dispersion of the noble metal due to the loading of. As a result, the degree of dispersion of the noble metal after the catalyst can be highly dispersed to 70% or more, more preferably 80% or more.

  As described above, the size of the noble metal particles having a high degree of dispersion is 10 mm or less, and when the degree of dispersion is 70%, the size is 7 mm or less. In such a cluster of small noble metal particles, the number of platinum atoms forming the plane is small, and considering the molecular size of hydrogenated aromatics, the surface of the noble metal on which these aromatic molecules adsorb in a plane The plane is considered to be extremely few. Therefore, it is presumed that these decomposition reactions can be suppressed because the adsorption of a plurality of aromatic carbon atoms is extremely small.

  In general, in reforming catalysts and dehydrogenation catalysts, noble metal particles such as platinum are bimetalized with a second metal component such as rhenium or tin to cut off the continuous arrangement of atoms having decomposition activity such as platinum, Although the planar adsorption of carbon atoms of raw materials and products is inhibited to suppress the decomposition reaction, the catalyst system according to the present invention is a bimetal because noble metal particles are highly dispersed and the particle diameter is sufficiently small. It is considered possible to suppress the decomposition reaction without performing the conversion.

  The reason for supporting the alkali metal in the dehydrogenation catalyst of the present invention is to mask the acid sites on the alumina to suppress the decomposition reaction on the alumina surface. The residual acid point on alumina is considered to vary depending on the amount of noble metal supported, and the amount of alkali metal necessary for masking decreases as the amount of noble metal supported increases. Therefore, if a highly dispersed state of platinum is realized, a certain level of performance is ensured even when masking with an alkali metal is not performed. However, since hydrogenated aromatics are recovered after dehydrogenation and used again as a hydrogenation raw material, it is necessary to reduce the loss due to decomposition as much as possible. From this viewpoint, it is more desirable to support an alkali metal.

  Further, the alkaline metal supported on the porous γ-alumina support specifically includes Group 1A and Group 1 of the periodic table including lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, and barium. Group 2A metal element, preferably potassium, and the supported amount is, for example, 0.001 wt% or more and 1.0 wt% or less, preferably 0.005 wt% when the alkaline metal is potassium. The content is 0.5% by weight or less. When the amount of the alkaline metal supported is less than 0.001% by weight, there is a problem that the effect is not substantially obtained. On the other hand, when the amount is more than 1.0% by weight, there is a problem that the activity is reduced due to excess. is there.

  The dehydrogenation catalyst of the present invention is obtained by impregnating the above porous γ-alumina carrier with the above catalyst metal solution, drying and calcining to obtain a catalyst metal-supported calcined product, in a state where the catalyst metal-supported calcined product is not reduced. The alkaline metal solution is impregnated and dried, and then the obtained dried alkali metal-supported product is directly subjected to final hydrogen reduction without firing.

  Here, the catalyst metal compound solution impregnated in the porous γ-alumina support includes various complex compounds such as chloride, bromide, ammonium salt, carbonyl compound, amine, ammine complex and acetylacetonato complex of the catalyst metal. For example, when the catalyst metal is platinum, chloroplatinic acid, acetylacetonatoplatinum, platinum platinum ammonium salt, bromoplatinic acid, platinum dichloride, platinum tetrachloride hydrate, carbonyl platinum dichloride Examples thereof include platinum compounds such as dichloride and dinitrodiamine platinate. When the catalyst metal is supported, the porous γ-alumina carrier is impregnated with the solution of the above-mentioned catalyst metal compound, and is preferably 50 ° C. or more and 200 ° C. or less, preferably 0.5 hours or more and 48 hours or less. And then baking is preferably performed at a temperature of 350 ° C. to 600 ° C., 0.5 hour to 48 hours, more preferably 350 ° C. to 450 ° C. for 0.5 hour to 5 hours. It is good.

  In addition, as an alkaline metal compound used when an alkali metal is supported on a catalyst metal-supported fired product obtained by supporting a catalyst metal on a porous γ-alumina carrier, an alkali metal chloride, bromide, iodide, Examples thereof include nitrates, sulfates, acetates, propionates and the like, preferably those which are soluble in water and / or soluble in organic solvents such as acetone, such as potassium chloride, potassium bromide, potassium iodide. , Potassium nitrate, potassium sulfate, potassium acetate, potassium propionate, rubidium chloride, rubidium bromide, rubidium iodide, rubidium nitrate, rubidium sulfate, rubidium acetate, rubidium propionate, lithium chloride, lithium bromide, lithium iodide, lithium nitrate , Lithium sulfate, lithium acetate, lithium propionate, cesium chloride , Cesium bromide, cesium iodide, cesium nitrate, cesium sulfate, cesium acetate, cesium propionate, magnesium chloride, magnesium bromide, magnesium iodide, magnesium nitrate, magnesium sulfate, magnesium acetate, magnesium propionate, calcium chloride, odor Calcium iodide, calcium iodide, calcium nitrate, calcium sulfate, calcium acetate, calcium propionate and the like can be mentioned.

  Further, when the alkaline metal is supported on the catalyst metal-supported fired product, after impregnating the alkaline metal compound solution, the temperature is from room temperature to 200 ° C. and from 0.5 hour to 48 hours, preferably from 50 ° C. to 150 ° C. It is preferable to dry under the drying conditions of not more than 0 ° C. and not less than 0.5 hours and not more than 24 hours, more preferably not less than 80 ° C. and not more than 120 ° C. and not less than 0.5 hours and not more than 5 hours.

  The alkaline metal-supported dried product obtained by impregnating the catalyst metal-supported fired product with an alkaline metal and drying is directly subjected to final hydrogen reduction without firing, and the reduction conditions for this hydrogen reduction are as follows. In an atmosphere of hydrogen gas, it is preferably performed at 350 ° C. to 600 ° C. and 0.5 hours to 48 hours, preferably 350 ° C. to 550 ° C. and 3 hours to 24 hours. Firing prior to the hydrogen reduction of the alkaline metal-supported dry matter causes a problem that the catalytic performance of activity, selectivity and life is lowered, and it is sufficient that the temperature during the hydrogen reduction is less than 350 ° C. On the other hand, there is a problem that platinum is not reduced. On the other hand, when the temperature exceeds 600 ° C., platinum particles are sintered at the time of reduction, and the metal dispersibility is lowered.

  After impregnating with noble metals such as platinum, perform calcination only, impregnate and dry with alkali metal without reduction, perform direct hydrogen reduction without calcination, reduce platinum and decompose alkali metal compounds The reason why a catalyst with high performance can be prepared is not clearly clarified at this time, but is presumed as follows.

  Firing after impregnation with a noble metal such as platinum means that the noble metal compound is decomposed and at the same time the noble metal species is immobilized on the support. After this, since the alkali metal compound is generally impregnated in the state of an aqueous solution, it is not preferable to contact the reduced platinum with water at this time. The metallic platinum is oxidized by the water, and the passive film is formed. What happens is considered obvious. Therefore, it is preferable to impregnate the alkali metal compound in a state in which platinum is not reduced but is fixed as an oxide by air baking.

  Subsequently, a step of decomposing and fixing the alkali metal compound is necessary. In this case, it is better to carry out the hydrogen reduction directly by drying only than the method of hydrogen reduction after air baking and fixing. High catalytic performance can be expressed. The reason for this is considered to be that when the decomposition is performed in a reducing atmosphere, the acid sites of alumina can be masked well despite the amount of alkali metal species being 1% or less. The role of the alkali metal is to suppress the decomposition of hydrogenated aromatics by masking the acid sites on the surface of the alumina support remaining after platinum is supported. Comparing the performance of the catalysts prepared in the same way with both preparation methods, the latter is highly selective and supports the fact that the acid sites are well masked.

  In the present invention, the aromatics used as the hydrogen reservoir are monocyclic aromatics such as toluene and benzene and / or bicyclic aromatics such as naphthalene. Hydrogenation processes of these aromatics are already several dozens such as production of decalin from naphthalene as a fuel for aviation and hydrogenation of benzene and toluene as chemicals and industrial solvents. It has been industrialized for many years and has reached the present day. The catalyst used for these hydrogenation reactions is mainly carried out in a slurry bed or fixed bed reaction system using nickel, platinum as active metals and palladium, rhodium, iridium, etc. as other metals. The lifetime is usually 1 to 3 years.

  On the other hand, the dehydrogenation reaction of hydrogenated aromatic compounds such as methylcyclohexane, in which hydrogen is stored by hydrogenation reaction, has not been industrialized so far, and it is necessary to establish a hydrogen storage and transport system by the organic chemical hydride method. Therefore, a dehydrogenation catalyst that operates stably over a long period of time has been required. The dehydrogenation catalyst disclosed in the aforementioned JP-A-2005-211,845 is a catalyst that operates stably in a simple fixed bed. By using platinum, palladium, rhodium, iridium, etc. as the active metal, and more preferably using platinum, by controlling the pH value when impregnating an aqueous solution of a platinum compound onto a γ-alumina carrier having specific physical properties. It is a catalyst for highly dispersing platinum. Further, for the purpose of suppressing the decomposition reaction occurring at the acid sites on the alumina, the catalyst is designed to suppress the decomposition reaction by masking the acid sites by adding an alkali metal, preferably potassium.

When methylcyclohexane (MCH) is supplied to the above catalyst at 320 ° C. and atmospheric pressure, the dehydrogenation reaction proceeds rapidly, and the MCH conversion rate is 95% or more even at the supply rate of LHSV = 2.0 h ^−1. In addition, it is possible to maintain the performance of a toluene selectivity of 99.9% or more and a hydrogen generation rate of 1000 Ncc-H ₂ / h / cc-cat over a long period of time. However, MCH, which is a raw material for dehydrogenation in practical use, contains various impurities. Means for grasping the influence of these impurities on the life of the dehydrogenation catalyst and removing impurities that affect the life It is necessary to have Further, the life of a catalyst used in an existing hydrogenation plant is usually 1 to 3 years and has an industrially sufficient life. In this hydrogen storage and transport system, the aroma used for a hydrogen storage body is used. Since the group is repeatedly used, it is considered that not only the dehydrogenation reaction but also the life of the catalyst used for the hydrogenation reaction is affected.

  When comparing hydrogenation reaction and dehydrogenation reaction, hydrogen partial pressure is very high in hydrogenation reaction, and it is carried out under conditions where the reaction proceeds thermodynamically to the hydrogenation reaction side, so the impurities are about the same. Even if it exists, since it does not remain on the catalyst, the influence on the catalyst life is small compared to the dehydrogenation reaction. However, in the hydrogen storage and transport system of the present method, in which the same aromatic raw material is repeatedly used compared to a process in which the raw material passes through the reactor only once as in an existing hydrogenation plant, impurities accumulate in the system. Therefore, it can be considered that the life of the hydrogenation catalyst is also affected. In the case of a dehydrogenation reaction, the reaction is carried out under conditions where the reaction proceeds thermodynamically toward the dehydrogenation reaction side. Therefore, when impurities are dehydrogenated, they tend to remain on the catalyst, and the remaining impurities are polymerized and decomposed. Since the dehydrogenation reaction is repeated in a complicated manner, the carbon is finally stripped of hydrogen and is likely to cause a coking reaction that deposits on the catalyst and degrades the catalytic activity. It is easily affected. Therefore, firstly, in order to extend the life of the dehydrogenation catalyst, and secondly, in order to extend the life of the hydrogenation catalyst, it is necessary to prevent accumulation of impurities that affect these deteriorations in the system. is there.

  Impurities contained in products of industrial hydrogenation processes include impurities originally contained in aromatics as raw materials and impurities newly generated by hydrogenation reactions. It is defined as an impurity generated by the reaction.

  The impurities produced by these industrial hydrogenation processes and their production paths will be described with reference to FIG. FIG. 1 shows impurities in a product and a production route thereof in the case of methylcyclohexane (MCH) produced by hydrogenating an aromatic as a hydrogen reservoir using toluene.

  The side reactions that occur as the first step at the acid sites of the alumina and silica alumina used on the active metal of the hydrogenation catalyst or as a support are the decomposition reaction in which the methyl group of the side chain is eliminated and the decomposition reaction in which the aromatic ring is cleaved. is there. In the route where the methyl group is eliminated, first, the methyl group is hydrogenated to methane, and the benzene ring from which the methyl group is eliminated is similarly hydrogenated to cyclohexane. However, the reaction in which the eliminated methyl group is added to the raw material MCH also proceeds to produce dimethylcyclohexanes and trimesylcyclohexanes. Furthermore, they undergo decomposition polymerization to produce bicyclohexyls, which are bicyclic products.

On the other hand, when the first stage decomposition reaction of the raw material MCH is cleavage of an aromatic ring, it becomes C ₇ chain hydrocarbons, which are hydrogenated to produce corresponding chain paraffins. These reactions are roughly divided into two cases, one being recyclized to form a 5-membered ring and the other being near-decomposed. The 5-membered ring compound is considered to have a methyl group added as in the above-mentioned raw material MCH or polymerize to form a 5-membered bicyclic compound. In addition, chain hydrocarbons are repeatedly decomposed, isomerized, polymerized, etc., and finally chain hydrocarbon paraffins up to C ₉ are present as impurities.

  When benzene having no side chain is used as the hydrogen storage body, impurities when the methyl group as the side chain in FIG. 1 is removed and when bicyclic aromatics such as naphthalene compounds are used as the hydrogen storage body are as follows: If the aromatic ring portion is considered as two rings, it is possible to assume impurities in each system in almost the same route.

  When the aromatic used as a hydrogen storage body shown in FIG. 1 is toluene, the product MCH of the industrial process may contain up to about 40 kinds of impurities. The number of these impurities depends on the purity of the raw material toluene and the hydrogenation reaction conditions, and depending on the process, hydrogenation processes that can be suppressed to less than half of the impurities are also operating industrially.

  Next, using Table 1, about 40 types of impurities are classified by type, and whether these compounds affect the catalyst life of the dehydrogenation reaction will be described. About 40 types of impurities can be classified by type into chain hydrocarbons, cyclic compounds with 5-membered rings, cyclic compounds with 6-membered rings, and bicyclic polymerization products in which cyclic compounds are polymerized. Separated.

The chain hydrocarbons are paraffins hydrogenated in the hydrogenation reaction process, the impurities contained as liquid products at room temperature are C _{5 to} C ₉ hydrocarbons, and C _{2 to} C as gas products. There are ₄ hydrocarbons. The precursors in which chain hydrocarbons are linked to coking are dienes having two double bonds, and butadiene is known as the compound most likely to be linked to coking. However, it is known that chain hydrocarbons are more difficult to proceed with dehydrogenation than aromatics, and the greater the number of carbons, the easier the dehydrogenation reaction proceeds. Here, since the even dehydrogenation reaction in chain hydrocarbon of C ₉ is the most number of carbon atoms is larger chain hydrocarbons in the impurity proceeds is not less than about 400 ° C., these C ₂ ~ The chain hydrocarbons of C ₉ are inactive because the dehydrogenation reaction does not proceed on the dehydrogenation catalyst under reaction conditions of 350 ° C. or lower, and do not affect the life of the dehydrogenation catalyst.

  Cyclic compounds having a 5-membered ring are also present in the impurities as hydrogenated compounds. These cyclopentane compounds become cyclopentadiene as the dehydrogenation proceeds, and become prominent compounds as precursors for coking. However, since cyclopentanes are also 5-membered ring compounds, the dehydrogenation reaction is difficult to proceed as compared with MCHs that are 6-membered ring compounds, and the dehydrogenation reaction does not proceed at a reaction temperature of 350 ° C. or lower. It is inert and does not affect the life of the dehydrogenation catalyst. However, bicyclic compounds in which 5-membered ring compounds are polymerized are easier to decompose and polymerize than a single ring, and the dehydrogenation reaction also proceeds more easily. It is assumed that Therefore, when selecting a hydrogenation process, it is preferable to employ a process with few impurities of a 5-membered ring compound.

  Six-membered cyclic compounds are basically compounds of the same family as MCH, which is a raw material for dehydrogenation, and these become a hydrogen storage body like MCH. Since the six-membered ring compound is more easily dehydrogenated as the number of side chains is larger, almost all of these impurities are used as a hydrogen reservoir because the dehydrogenation reaction proceeds with priority over MCH. However, the more the side chain, the easier the decomposition polymerization reaction proceeds, and the bicyclic compound decomposed and polymerized in the same manner as the five-membered ring compound easily decomposes and dehydrogenation easily proceeds. Therefore, it is assumed that the dehydrogenation catalyst is deteriorated. Therefore, when selecting a hydrogenation process, it is preferable to employ a process with few impurities of a 6-membered ring compound.

  Since the bicyclic polymerization product easily proceeds with a decomposition polymerization reaction and also with a dehydrogenation reaction, it directly affects the catalyst life of the dehydrogenation catalyst. It is considered that the bicyclic polymerization product is further decomposed and polymerized on the dehydrogenation catalyst to form a tetracyclic compound and the like. Since these compounds are heavy, they are difficult to desorb from the catalyst after the dehydrogenation reaction. In addition, dehydrogenation reaction and decomposition reaction proceed to convert to carbonaceous matter and coking proceeds.

  The same applies to the case where bicyclic naphthalene compounds are used as the hydrogen storage body. Since the 4-ring polymerization product obtained by polymerizing naphthalene is also heavy, it desorbs from the catalyst after the dehydrogenation reaction. It is difficult to remain on the catalyst, and further, dehydrogenation reaction and decomposition reaction proceed to be converted into carbonaceous matter and coking proceeds.

  From the above, compounds that directly affect the lifetime of the dehydrogenation catalyst are identified as polymerized polycyclic compounds. When toluene is used as the hydrogen storage body, the bicyclic polymerization products contained as impurities in the product of the industrial hydrogenation process are bicyclohexyl and alkylbicyclohexyls having a methyl group added thereto. Bicyclic compounds obtained by polymerizing 5-membered cyclic compounds and compounds obtained by polymerizing 6-membered cyclic compounds and 5-membered cyclic compounds are not detected in the quantitative analysis of the gas chromatograph. This is thought to be because the amount of impurities of cyclopentanes, which are precursors to be polymerized, is very small, and the products obtained by polymerization of these are not detected because the amount is even smaller. However, it is considered that not only the polymerization products of 6-membered ring compounds, but also the polymerization products of 5-membered ring compounds, which are contained in products in relatively large amounts as impurities, directly affect the life of the dehydrogenation catalyst. Therefore, it is preferable that these polymerization products are also removed from the system.

  In addition, a bicyclic polymerization product that directly affects the life of the dehydrogenation catalyst is slightly generated even during the dehydrogenation reaction. For example, when a dehydrogenation reaction is continuously performed for about 6000 hours or more continuously using a single component of methylcyclohexane as a hydrogen reservoir, the dehydrogenation reaction at this time is carried out with a selectivity of 99% by weight or more. However, dehydrogenation by-products are generated on the order of several tens to several hundred ppm, and carbon deposition proceeds due to the dehydrogenation by-products, thereby reducing the life of the dehydrogenation catalyst. Therefore, in the hydrogen storage and transport system of the present method that repeatedly uses a hydrogen storage body, reaction inhibitors that are considered to directly affect the life of these dehydrogenation catalysts in the system and also to the life of the hydrogenation reaction catalyst. It is necessary to prevent these polymerization products from accumulating in the system by removing the bicyclic polymerization products.

  The above-mentioned reaction inhibitor removal device is a transfer route of hydrogenated aromatic compounds from a hydrogenation reactor to a dehydrogenation reactor via a hydrogen storage / transfer device and / or an aromatic compound from the dehydrogenation reactor. The transfer route of the aromatic compound from the storage / transfer device to the hydrogenation reaction device, preferably the transfer route of the hydrogenated aromatic compound from the hydrogen storage / transfer device to the dehydrogenation reaction device, more preferably hydrogenation. Immediately after the reaction apparatus, an inhibitor removal apparatus for removing the reaction inhibition substance by-produced by the hydrogenation reaction can be provided.

  Here, the inhibitor removal device may be any device that can separate and remove the polymerization product as a reaction inhibitor, and examples thereof include a distillation device and an adsorption device. When toluene is used as the hydrogen storage body, the boiling point of MCH, which is the hydrogenated compound, is 101 ° C. At this time, the boiling point of the bicyclic compound of bicyclohexyls to be removed as a reaction inhibitor is 235 ° C. for bicyclohexyl having no alkyl group, and the boiling point of bicyclohexyls having an alkyl group is 240 ° C. or more. In addition, the boiling points of 5-membered polymerized bicyclopentanes which are considered to be undetectable because the amount actually contained are both 190 ° C. or higher, and the bicyclic compounds in which 5-membered and 6-membered rings are polymerized. It is.

  Thus, the reaction inhibiting substance to be removed is a polymerization product, the boiling point difference from MCH used as a dehydrogenation raw material is about 90 ° C., and the hydrogenation reaction is a large exothermic reaction. Therefore, excess reaction heat can be recovered from the hydrogenation process, and this thermal energy can be directly used as heat energy when removing reaction inhibitors. The method is preferably a distillation operation.

  Distillation calculations were conducted to examine the distillation operation to remove reaction inhibitors contained in products of industrial hydrogenation processes. When the product of polymerization was 100 ppm or less, reaction inhibition was achieved by distillation operation with two theoretical plates. The concentration of the substance can be reduced to 1 ppm or less, and even when the concentration of the reaction inhibitory substance is 1000 ppm or less, the concentration of the reaction inhibitory substance can be reduced to 1 ppm or less by a distillation operation with four theoretical plates. .

The distillation apparatus may be a normal distillation apparatus, and it may be designed to have a column efficiency of 50% or more in a distillation operation with 2 to 4 theoretical plates, and the specific number of shelves is about 3 to 8 plates. The configuration of the shelf is not particularly limited, and may be a commonly used bubble bell tray, perforated plate tray, bubble tray, etc., and may be selected from the cost, etc., using a packing such as Raschig ring as necessary. Also good. For example, when hydrogen is used as a hydrogen station, the scale of hydrogenation equipment for storing hydrogen for 30 to 40 hydrogen stations is assumed to be 70,000 tons / year. The total equipment cost and service cost of the distillation unit that removes reaction inhibitors in the product by the hydrogenation reactor of 100,000 tons / year using these distillation units is 1-2 yen per 1Nm ³ of supplied hydrogen Since it is estimated to be / Nm ³ -H ₂ , it is possible to operate cheaper and more economically than when the catalyst is replaced and operated in a short period of time.

  In addition, when the distillation operation is simple distillation, the equipment cost and utility cost are reduced, but the removal rate of the reaction inhibitor is relatively low, and the catalyst life is distilled with 2 to 4 theoretical plates. Therefore, the frequency of catalyst exchange is increased, which is not economical. However, if the catalyst production method is improved and the cost of the catalyst is improved at a low cost, the removal of the reaction inhibiting substance by single-stage distillation may be economical.

  Furthermore, adsorption removal can be considered as a method for removing a reaction inhibitor other than the distillation operation. As the adsorbent, use of general adsorbents such as zeolite, alumina, silica alumina, etc. can be considered, but a considerable amount of adsorbent is necessary to sufficiently remove the reaction inhibitor by these adsorbents. In addition to the large adsorption column, it is necessary to install a plurality of columns for regeneration of the adsorbent. Further, an operation for continuously switching between the adsorption operation and the regeneration operation is necessary, and the operation is complicated. In addition, the distillation operation is considered preferable in consideration of the equipment cost and the like.

  In this inhibitor removal apparatus, the dehydrogenation inhibitor is separated and removed, and the dehydrogenation inhibitor is preferably reduced to 100 ppm or less, more preferably 50 ppm or less, and even more preferably 10 ppm or less. This makes it possible for the dehydrogenation catalyst to perform a continuous dehydrogenation reaction over 8000 hours.

  According to the hydrogen storage and transport system of the present invention, in a dehydrogenation reaction of a hydrogenated aromatic compound in the dehydrogenation reactor, a high hydrogenated aromatic compound of 90% or more at a relatively low reaction temperature of 290 to 350 ° C. In addition, it has a high reaction selectivity of 98% or more, and can stably carry out the dehydrogenation reaction of this hydrogenated aromatic compound over a long period of time. It is possible to provide a system capable of storing and transporting hydrogen energy easily and efficiently by the OCH method without complicating the structure and control of the reactor with high hydrogen storage efficiency and less potential danger. .

  In the hydrogen storage and transport system of the present invention, among the impurities generated by the hydrogenation reaction, the reaction of the polymerization product that directly affects the life of the hydrogenation catalyst when the dehydrogenation catalyst and the hydrogen storage body are repeatedly used. By providing an apparatus for removing the inhibitory substance, accumulation of reaction inhibitory substance in the hydrogen transfer medium circulation path is prevented, and the life of the dehydrogenation catalyst and the hydrogenation catalyst is extended. An operable hydrogen storage and transport system can be constructed.

  Hereinafter, examples of the present invention shown in the attached drawings, examples of production of dehydrogenation catalysts used in the dehydrogenation reactors of these examples and performance test examples, and representative compounds among impurities produced by industrial hydrogenation reaction processes Based on the reaction test example in which the effect on the life of the dehydrogenation catalyst by adding a large amount is added, and the distillation calculation example in the case where the inhibitor is removed by distillation operation, the preferred embodiment of the present invention The embodiment will be specifically described.

[Configuration example 1]
FIG. 2 shows a configuration example 1 for explaining a basic configuration of a hydrogen storage and transport system by the organic chemical hydride method in the present invention. The hydrogen storage and transport system S ¹ of Configuration Example 1 includes a hydrogen storage system S ² installed at a hydrogen production site and a hydrogen supply system S ³ installed at a hydrogen utilization site.

The hydrogen storage system S ² performs a hydrogenation reaction of an aromatic compound using hydrogen produced by the hydrogen production apparatus S ⁴ , and stores hydrogen as a hydrogenated aromatic compound in a liquid state at normal temperature and pressure. A hydrogenation reaction apparatus (hydrogenation reactor) 1, a removal apparatus 1 a for removing a reaction inhibitor produced in the obtained hydrogenated aromatic compound, and a hydrogenated aromatic compound from which the reaction inhibition substance has been removed. composed of recovered aromatic tank 1c for storing aromatics recovered from hydrogenated aromatic tank 1b and the hydrogen supply system S ³ for storage. Hydrogenated aromatics from which hydrogen has been stored in the hydrogen storage system S ² and from which reaction-inhibiting substances have been removed are supplied as hydrogen chemicals at room temperature and atmospheric pressure by the hydrogenated aromatic transport means 3 as a hydrogen chemical supply site. It is transported to the system S ^3. The transportation means 3 may be a means for transportation through a ship such as a chemical tanker in the case of sea transportation, a vehicle such as a chemical lorry in the case of land transportation, or a pipe attached to the sea floor such as a pipeline and / or underground.

Hydrogen supply system S ³ is hydrogenated aromatic tank 2a, the dehydrogenation reactor (dehydrogenation reactor) 2, the hydrogen separator 2b, and a from the recovery aromatic tank 2c. Hydrogenated aromatic which have been transported to the hydrogen utilization location is stored in the hydrogenated aromatic tank 2a constituting the hydrogen supply system S ^3, the required amount of the dehydrogenation reactor (dehydrogenation reactor) 2 by dehydrogenation To generate the required amount of hydrogen. In the dehydrogenation reactor in this dehydrogenation apparatus 2, the reaction tube has a surface area of 150 m ² / g or more, a pore volume of 0.40 cm ³ / g or more, an average pore diameter of 90 to 300 mm, and a total pore volume. Dehydrogenation in which at least one catalyst metal selected from platinum, palladium, rhodium, iridium and ruthenium is supported on a porous γ-alumina carrier in which the proportion of pores with an average pore diameter of ± 30 mm is 50% or more Packed with catalyst. The reaction product dehydrogenated by the dehydrogenation reactor 2 is mainly generated hydrogen and an aromatic compound, and these are separated by the hydrogen separator 2b, and the hydrogen is purified to the required purity. Since the dehydrogenation reactor 2 in this system has a very high selectivity of the charged dehydrogenation catalyst and is 98% or more, the hydrogen separation device 2b uses aromatic and unreacted hydrogen contained in the gas after gas-liquid separation. It is possible to obtain high-purity hydrogen by a simple operation of removing vapor components such as fluorinated aromatics with an adsorption device or the like. When the supplied hydrogen needs to be at a high pressure, a booster and a high-pressure tank are installed at the subsequent stage of the hydrogen separator 2b, and hydrogen is supplied after the pressure is increased.

Aromatic after dehydrogenation separated by the hydrogen separator 2b is recovered, after being stored in the recovery aromatic tank 2c, recovered aromatic tank constituting the hydrogen storage system S ² by recovering aromatic transporting means 4 Stored in 1c. The aromatic thus recovered is reused again as a hydrogen storage by the hydrogenation reaction apparatus 1, but a trace amount of reaction inhibitor generated in the dehydrogenation reaction and reaction inhibition generated again by the hydrogenation reaction. Since the substances are removed again by the reaction inhibitor removing apparatus 1a, the aromatic as a hydrogen storage body can be repeatedly used without accumulating in the system.

[Dehydrogenation catalyst used in dehydrogenation reactor]
Next, a production example of the dehydrogenation catalyst used in the dehydrogenation reactor 2 constituting the hydrogen storage and transport system will be specifically described.

(Production example)
A γ-alumina support was produced as described in Example 1 of JP-B-6-72,005. The outline of this method is as follows. Aqueous sodium aluminate aqueous solution is added instantaneously with vigorous stirring in hot dilute sulfuric acid to obtain an aluminum hydroxide slurry suspension (pH 10), which is used as seed aluminum hydroxide and stirred. The operation of adding hot dilute sulfuric acid and sodium aluminate aqueous solution alternately for a certain time while repeating the above is repeated to obtain a filter washed cake, which is extruded and dried, and then baked at 500 ° C. for 3 hours. .

  The properties of γ-alumina (support A) obtained by such pH swing operation (pH swing method) are typically as shown in Table 1 below. Further, as an example of an alumina carrier whose pore distribution is not controlled, the properties of a commercially available γ-alumina carrier (carrier B) generally used are also shown in Table 2. FIG. 3 shows the results of measuring the pore distribution of these alumina carriers by the mercury intrusion method.

Porous γ-alumina having a physical property of 90% occupancy with a surface area of 240 m ² / g, a pore volume of 0.713 cm ³ / g, an average pore diameter of 119 mm, and an average pore diameter of ± 30 mm prepared as described above. To 20 g of support, 79 g of 0.4 wt% -chloroplatinic acid aqueous solution prepared so as to have a pH value of 2.0 was added, left to stand for 3 hours to impregnate, water was removed by decantation, and then 120 ° C. And then baked at 400 ° C. for 3 hours in an air stream in a muffle furnace.

  The obtained fired product was cooled to room temperature in a desiccator, then added with 10 g of a 0.52 wt% -potassium nitrate aqueous solution, allowed to stand for 3 hours and then impregnated, and then water was removed by an evaporator, and then at 120 ° C. for 3 hours. The mixture was dried and reduced at 400 ° C. for 15 hours under a hydrogen flow to prepare a dehydrogenation catalyst. The supported amount of platinum in this dehydrogenation catalyst is 0.6% by weight, and the supported amount of potassium is 0.1% by weight.

  In addition, using the above-mentioned carrier A with controlled pores, the catalyst No. 1 catalyzed by supporting platinum and potassium in the above procedure, and hydrogen reduction without supporting potassium after supporting only platinum. The catalyst No. 2 carrying only platinum was prepared and the dispersion degree of platinum was measured.

  Furthermore, using a commercially available alumina support B having a broad pore distribution, the dispersity of catalyst No. 3 (0.6 wt% platinum, 0.1 wt% potassium) prepared by the same procedure for supporting platinum and potassium was the same. It was measured.

The degree of dispersion was measured by the CO pulse adsorption method. That is, the metal surface area was calculated on the assumption that one molecule of CO adsorbs to the lattice constant area a ^{2 of} platinum. Further, the metal dispersity and the particle diameter were determined with the amount of platinum supported being 0.6% by weight. The measurement was performed using a fully automatic catalyst gas adsorption amount measuring device (Okura Riken Co., Ltd .: R6015). The results are shown in Table 3.

  As is apparent from Table 3, the catalyst prepared using the carrier A has a significantly higher degree of platinum dispersion and a smaller particle size than the case where the carrier B is used. Further, in the catalyst using the carrier A, the degree of dispersion of platinum tends to be lower in a catalyst supporting potassium as compared with a catalyst supporting platinum alone.

(Performance Test Example 1)
The center of the catalyst layer is positioned in the center of the length direction of a stainless steel reaction tube with an inner diameter of 12.6 mmφ × 300 mm and a 1/8 inch thermocouple protection tube at the center of the reaction tube cross section. No. 1 or No. 3 dehydrogenation catalyst 10 cc obtained above was filled, and 1 mmφ spherical α-alumina beads 10 cc were filled as a preheating layer on the upper side of the catalyst layer. The fixed bed dehydrogenation reactors (No. 1 reactor and No. 3 reactor) filled with the above dehydrogenation catalyst were prepared.

Using these No. 1 and No. 3 fixed-bed dehydrogenation reactors, the catalyst performance in the dehydrogenation reaction of methylcyclohexane (MCH) was examined as follows.
That is, the temperature of the reactor was raised until the center temperature of the catalyst layer reached 320 ° C. under the flow of hydrogen, and then the flow rate of hydrogen was adjusted to LHSV = 5.0 (50 cc / hr), and then high-performance liquid chromatography was performed in the reactor. (HPLC) Using a liquid feed pump (HPLC pump), methylcyclohexane (MCH) is supplied at LHSV = 2.0 (20 cc / hr) so that the hydrogen concentration in the supply gas of MCH and hydrogen is 20 mol%. The supply amount of hydrogen was adjusted. In addition, in supplying MCH, it was supplied after being heated to 300 ° C. by a preheater in advance.

The dehydrogenation reaction in the reactor was carried out continuously, and the hydrogen supply amount was adjusted so that the hydrogen concentration in the supply gas became 5 mol% after 1300 hours had elapsed, and the dehydrogenation reaction was continued thereafter.
A gas-liquid separator is provided at the outlet of the reaction tube to separate the liquid product such as toluene and gas such as hydrogen gas generated by this dehydrogenation reaction, and the recovered liquid product and gas are each subjected to gas chromatography. Analyzed with

  MCH conversion (%), toluene selectivity (%), and hydrogen generation amount (Ncc / h / cc-cat) after 100 hours and 6000 hours from the start of the reaction were determined. The results are shown in Table 4.

  As is apparent from the results shown in Table 4, in the case of the No. 1 reactor using the dehydrogenation catalyst according to the example of the present invention, the No. 3 reactor using the conventional catalyst No. 3 is used. Compared to the case, hydrogen can be produced stably over 6000 hours with good selectivity, and if methylcyclohexane having a high purity without containing a reaction inhibitor is used, an organic chemical hydride method (OCH method) It can be seen that a hydrogen energy storage and transport system can be easily constructed without impairing the advantages of

(Performance Test Examples 2 to 4)
Reaction test example 2 in which a large amount of chain hydrocarbons, five-membered cyclic compounds, and two-ring polymerization products, which are representative compounds among impurities, were independently added to study the effect on the dehydrogenation catalyst life ~ 4 are shown below.

(Performance test example 2)
Using the No. 1 catalyst in the catalyst production example, dehydrogenation No. 1 was prepared again in the same manner as in the performance test example 1, and 1.0% (10,000 ppm) of n-heptane was added to the raw material methylcyclohexane (MCH). A reaction test was carried out in the same manner as in Performance Test Example 1 except that the mixed solution added with was used as a raw material, and the influence of n-heptane on the deterioration of the dehydrogenation catalyst was confirmed. Here, the reason for using n-heptane is the largest among the chain hydrocarbons contained in the impurities in the product MCH by the industrial hydrogenation process, in which the straight chain portion has 7 carbon atoms, and C _This is because chain hydrocarbons having a straight chain of ₈ and C ₉ are hardly contained. The results are shown in Table 5.

  As is apparent from the results in Table 5, the catalyst performance did not show any particular deterioration tendency during the 200-hour test, and showed almost the same tendency as the initial deterioration tendency when n-heptane was not added. Further, since the disproportionation decomposition product and the dehydrogenation product are not detected in the result of analyzing the reaction product by gas chromatography, n-heptane is inactive at the reaction temperature of 320 ° C. and does not react. This shows that it does not participate in the deterioration of the dehydrogenation catalyst.

(Performance Test Example 3)
Using the No. 1 catalyst in the catalyst production example, dehydrogenation No. 1 was prepared in the same manner as in the performance test example 1, and 1.0% (10,000 ppm) of cyclopentane was added to the raw material methylcyclohexane (MCH). A reaction test was performed in the same manner as in Performance Test Example 1 except that the added mixed solution was used as a raw material, and the influence of cyclopentane on the deterioration of the dehydrogenation catalyst was confirmed. The results are shown in Table 6.

  As is clear from the results in Table 6, the catalyst performance did not show any particular deterioration tendency during the 250-hour test, and was almost the same tendency as the initial deterioration when no cyclopentane was added. Moreover, since the decomposition product and the dehydrogenation product are not detected in the result of analyzing the reaction product by gas chromatography, cyclopentane is inactive at the reaction temperature of 320 ° C. and does not react. It turns out that it does not participate in deterioration of a catalyst.

(Performance Test Example 3)
Using the No. 1 catalyst in the catalyst production example, dehydrogenation No. 1 was prepared in the same manner as in the performance test example 1, and 1.0% (10,000 ppm) of bicyclohexyl was added to the raw material methylcyclohexane (MCH). A reaction test was performed in the same manner as in Performance Test Example 1 except that the added mixed solution was used as a raw material, and the influence of bicyclohexyl, which is a bicyclic polymerization product, on the deterioration of the dehydrogenation catalyst was confirmed. The results are shown in Table 7.

  As is apparent from the results in Table 7, the catalyst performance when bicyclohexyl is added is lower than that when bicyclohexyl is not added and is 96% or less. This is because the dehydrogenation of MCH is hindered because bicyclohexyl is adsorbed on the active site of the catalyst and dehydrogenated. Further, the MCH conversion rate significantly deteriorated from 95.9% to 90.9% in the 450-hour test. In addition, as a result of analyzing the reaction product by gas chromatography, a large amount of biphenyl, which is a dehydrogenation product of bicyclohexyl, was detected, and a heavy component not included in the raw material considered to be a decomposition polymerization product of bicyclohexyl was detected. Trace amounts of several quality components were detected. At a reaction temperature of 320 ° C., bicyclohexyl undergoes a dehydrogenation reaction, and a plurality of heavy components are produced by a reaction such as decomposition polymerization on the dehydrogenation catalyst, which causes poisoning of the dehydrogenation catalyst and greatly deteriorates. You can see that it affects.

(Calculation example)
Two types of commercial products of product MCH obtained by a typical industrial hydrogenation process were obtained, the impurities were identified, and distillation calculation was performed on 36 of these components.
Since the impurities in the industrial product MCH are considered to have a large influence on the hydrogenation process and conditions to be produced, the MCH of Company A, which has a relatively large amount of impurities, and the MCH of Company B, which has the least amount of impurities, are used in the distillation calculation Two types were carried out.

A company impurity composition has a high impurity concentration as compared with Company B, an impurity is 3,223ppm of C ₅ impurity concentration -C ₇ is a 4,385ppm C ₈ ~C _9, also, reaction inhibition the concentration of C ₁₂ -C ₁₄ is a substance is 70 ppm. B's MCH, the impurity concentration of C ₅ -C ₇ is impurity 85ppm of C ₈ -C ₉ a 95 ppm, The concentration of C ₁₂ -C ₁₄ which is a reaction inhibitor is 850 ppm. For these two types of MCH, the number of theoretical plates when C _{12 to} C _{14 as} reaction inhibitors are completely removed by distillation operation was determined. Four stages of results were obtained for each MCH composition. The composition when the MCH of Company A is distilled in two theoretical plates and the composition after the distillation operation when the MCH of Company B is distilled in four theoretical plates are the raw materials before distillation. It shows to Table 10 with Table 10 with a composition.

As is apparent from Tables 8 to 10, in the case of MCH of Company A having a polymerization product concentration of C _{12 to} C ₁₄ that is a reaction inhibitor of 70 ppm, C _{12 to} C _{14 is obtained by} distillation with two theoretical plates. It is possible to remove the components almost completely. Further, even in the case of BCH MCH having a C _{12 to} C ₁₄ polymerization product concentration of 800 ppm or more, it can be almost completely removed by a distillation operation with 4 theoretical plates. Furthermore, in the case of MCH containing a large amount of C _{12 to} C ₁₄ components, it is necessary to increase the number of theoretical stages, but this is not preferable from the viewpoints of equipment cost, utility cost, etc., so a process capable of obtaining a hydrogenated product with less impurities is selected. It is preferable.

  The leveling system using hydrogen according to the present invention is a stable operation of an organic chemical hydride method (OCH method) using a hydrogenation reaction of an aromatic compound or the like and a dehydrogenation reaction of a hydrogenated aromatic compound or the like. OCH which has a high storage efficiency of hydrogen, can store hydrogen as a liquid at normal temperature and normal pressure, and has low potential danger. It provides a system that can easily store and transport hydrogen energy using the OCH method without compromising the advantages of the method and without complicating the structure and control of the reactor. It is extremely useful in planning.

  In addition, in such a hydrogen energy storage and transport system, an inhibitor removal device for separating and removing reaction inhibitors such as a distillation apparatus is provided in the hydrogen transfer medium circulation path so that the reaction inhibitor can be easily removed. As a result, hydrogen storage efficiency is high, hydrogen storage is possible as a liquid at normal temperature and pressure, and there is less potential danger. The structure and control of the reactor are not impaired. The hydrogen energy can be easily stored and transported by the OCH method without complicating the process, and the life of the dehydrogenation catalyst and the hydrogenation catalyst can be extended and the hydrogen energy can be operated at low cost over a long period of time. A storage and transportation system can be constructed, and its practical value is high.

FIG. 1 is a diagram showing impurities in methylcyclohexane produced by an industrial hydrogenation process to be examined for reaction inhibitors and their production paths.

FIG. 2 is a block diagram of a configuration example for explaining the configuration of the organic chemical hydride method hydrogen storage and transport system of the present invention.

FIG. 3 is a pore distribution diagram by mercury porosimetry measured for an alumina carrier having specific physical properties prepared by the pH swing method and a commercially available alumina carrier whose pore distribution is not controlled.

Explanation of symbols

S ¹ ... hydrogen storage transportation systems, S ² ... hydrogen storage systems, S ³ ... hydrogen supply system, S ⁴ ... hydrogen production device, 1 ... hydrogenation reactor (hydrogenation reactor), 1a ... reaction inhibiting substance removing device 1b ... hydrogenated aromatic tank A, 1c ... recovered aromatic tank A, 2 ... dehydrogenation reactor (dehydrogenation reactor), 2a ... hydrogenated aromatic tank B, 2b ... hydrogen separator, 2c ... recovered aroma Group tank B, 3... Hydrogenated aromatic transportation means, 4... Recovery aromatic transportation means.

Claims (13)

Hydrogen storage system equipped with hydrogenation reaction device for producing hydrogenated aromatic compound (hydrogen supplier) by carrying out hydrogenation reaction of aromatic compound (hydrogen store), and hydrogenated aromatic compound obtained as hydrogen A hydrogen supply system comprising a hydrogenated aromatic compound transport means for transporting to a use site, a dehydrogenation reaction apparatus for producing hydrogen and an aromatic compound by a dehydrogenation reaction of the transported hydrogenated aromatic compound, and a recovered The recovered aromatic transport means transports the recovered aromatic compound to the hydrogen storage system again, hydrogenates the aromatic compound with hydrogen to produce the hydrogenated aromatic compound, and stores and / or transfers hydrogen. after the, in the hydrogenation aromatics storage transport system of hydrogen by an organic chemical hydride method provided for use by producing hydrogen by dehydrogenation of the dehydrogenation reactor
The aromatic compound used as the hydrogen storage is a monocyclic aromatic or a bicyclic aromatic, and the dehydrogenation catalyst has a surface area of 150 m ² / g or more and a pore volume of 0.40 cm ³ / g or more. Further, platinum, palladium, rhodium, iridium and ruthenium are added to a porous γ-alumina support having an average pore diameter of 90 to 300 mm and a ratio of pores having an average pore diameter of ± 30 mm to the total pore volume of 50% or more. A catalyst supporting at least one kind of catalytic metal selected from
Within the system, downstream of the hydrogenation reactor, poisoning of hydrogenation catalyst generated in the system-based is used in the dehydrogenation catalyst and / or hydrogenated apparatus utilized in the dehydrogenation reactor to remove the reaction inhibiting substance inhibiting dehydrogenation and / or hydrogenation reaction I Do with the substance, the reaction inhibiting substance removing device is provided to maintain the reaction inhibiting substance concentration in the system based on 100ppm or less A hydrogen storage and transport system.   The hydrogenation catalyst is a hydrogenation catalyst in which at least one catalytically active metal selected from nickel, platinum, palladium, rhodium, iridium, and ruthenium is supported on a catalyst carrier selected from alumina, silica alumina, and silica. The hydrogen storage and transport system according to claim 1.   The dehydrogenation catalyst is a dehydrogenation catalyst in which at least one catalytically active metal selected from nickel, platinum, palladium, rhodium, iridium, and ruthenium is supported on a catalyst carrier selected from alumina, silica alumina, and silica. The hydrogen storage and transport system according to claim 1 or 2. The hydrogen storage and transport system according to any one of claims 1 to 3 , wherein the reaction inhibitor removing device is a distillation device. The hydrogen storage and transport system according to claim 4 , wherein the distillation apparatus has a function of 2 to 4 theoretical plates. When the aromatic compound used as a hydrogen reservoir is a monocyclic aromatic, the reaction inhibitor is a dimer of a 6-membered ring compound or a polymerization product of a trimer or more and a 5-membered ring compound. A dimer or a trimer or higher polymerization product, and when the aromatic compound used as a hydrogen reservoir is a bicyclic aromatic compound, a dimer or trimer of a 6-membered ring compound In addition to the above-mentioned polymerization product and a dimer of a 5-membered ring compound or a polymerization product of a trimer or more, it is a bicyclic aromatic dimer or a polymerization product of a trimer or more . The hydrogen storage and transport system according to any one of 5 . Dehydrogenation catalyst is a porous γ- alumina support, storage transport system of hydrogen according to claim 1, the catalytic metals and alkaline metals is a catalyst supported. When the dehydrogenation catalyst impregnates a porous γ-alumina support with a solution of at least one catalytic metal compound selected from platinum, palladium, rhodium, iridium and ruthenium, the pH value of the impregnation solution is 1.8 to The hydrogen storage and transport system according to any one of claims 1 to 7 , wherein the hydrogen dispersibility of the noble metal after catalysis is 60% or more, adjusted to 3.0. The porous γ-alumina support alternately changes the pH value of the aqueous slurry during synthesis of the alumina hydrogel between the alumina hydrogel dissolution pH region and the boehmite gel precipitation pH region, and from at least one of the pH regions to the other. The hydrogen storage and transport system according to any one of claims 1 to 8 , wherein the hydrogen storage and transport system is obtained through a pH swing step in which an alumina hydrogel raw material is added to grow a crystal of alumina hydrogel upon pH change to a pH range. Storage transportation system of hydrogen according to claim 1 the catalyst metal is platinum. 11. The hydrogen storage and transport system according to claim 7 , wherein the alkaline metal is potassium. The hydrogen storage and transport system according to claim 10 or 11 , wherein the supported amount of platinum is 0.3 to 2.0% by weight. The hydrogen storage and transport system according to claim 11 or 12 , wherein the amount of potassium supported is 0.001 to 1.0% by weight.

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