Metal catalyst and method for hydrogenolysis of cyclic compound using the same

Abstract

To perform selective hydrogenolysis of a cyclic compound having a five-membered ring structure, which is contained in a saturated cyclic compound used as a hydrogen carrier.SOLUTION: A metal catalyst is used in the hydrogenolysis of a cyclic compound having a five-membered ring structure, which is contained in a saturated cyclic compound used as a hydrogen carrier. The metal catalyst includes a silica-based carrier as a catalyst carrier, and cobalt as a metal supported on the catalyst carrier.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a metal catalyst for use in the hydrogenolysis of a cyclic compound having a five-membered ring structure, and a method for hydrogenolysis of a cyclic compound using the same. [Background technology]

[0002] Conventionally, the organic chemical hydride method is known as a method for storing and transporting hydrogen (see Non-Patent Documents 1 and 2). The organic chemical hydride method includes a hydrogenation reaction (i.e., hydrogen storage reaction) in which an aromatic compound such as toluene is reacted with hydrogen, and a dehydrogenation reaction (i.e., hydrogen generation reaction) in which hydrogen is generated from a saturated cyclic compound such as methylcyclohexane (i.e., hydrogenated aromatics) to recover an aromatic compound such as toluene. According to the organic chemical hydride method, the saturated cyclic compound that has absorbed hydrogen can be stored and transported in a liquid state at room temperature and pressure, and a required amount of hydrogen can be extracted by a dehydrogenation reaction of the saturated cyclic compound at the site where hydrogen is used. Saturated cyclic compounds such as methylcyclohexane and aromatic compounds such as toluene that are generated after hydrogen is extracted from the saturated cyclic compounds are repeatedly used as hydrogen containers (i.e., hydrogen carriers).

[0003] It is known that the hydrogenation reaction or dehydrogenation reaction in the organic chemical hydride process can produce various by-products (impurities) in addition to the target product (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Non-Patent Document 1] Yoshimi Okada, Energy and Resources, Vol.33, No.3, 168(2018) [Non-Patent Document 2] Yoshimi Okada, Tokyo High Pressure Gas Association Newsletter, August and September 2019 issues [Non-Patent Document 3] Choi, Y., Ishii, M., Nanba, T., Tsujimura, T., Taniguchi, T., 46th Petroleum and Petrochemical Symposium, Abstract, 2A03 (2016) [Patent Document 1] JP 2007-269522 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned organic chemical hydride method, the ratio of impurities mixed in the hydrogen carrier may gradually increase due to repetition of hydrogenation and dehydrogenation reactions. Therefore, it is considered to remove (separate) such impurities from the hydrogen carrier by, for example, distilling the hydrogen carrier containing impurities.

[0006] In particular, impurities that may be mixed into hydrogen carriers include cyclic compounds having a five-membered ring structure, such as cyclopentanes, which are produced in dehydrogenation reactions (hereinafter referred to as five-membered ring compounds) (see Non-Patent Document 3). Because the boiling points of such five-membered ring compounds are relatively close to the boiling point of the hydrogen carrier, it is not easy to separate these five-membered ring compounds from the hydrogen carrier by distillation.

[0007] Therefore, after extensive research, the inventors of the present application developed a metal catalyst that can selectively hydrocrack five-membered ring compounds contaminated in a hydrogen carrier, and as a result, they found that the five-membered ring compounds can be converted into hydrocracked light hydrocarbons from the hydrogen carrier and easily separated.

[0008] In view of the above background, an object of the present invention is to provide a metal catalyst capable of selectively hydrolyzing cyclic compounds having a five-membered ring structure contained in saturated cyclic compounds used as hydrogen carriers, and a method for hydrolyzing cyclic compounds using the same. [Means for solving the problem]

[0009] In order to solve the above problems, one embodiment of the present invention is a metal catalyst used for the hydrolysis of a cyclic compound having a five-membered ring structure contained in a saturated cyclic compound used as a hydrogen carrier, the metal catalyst comprising a silica-based carrier as a catalyst support and cobalt as a metal supported on the catalyst support.

[0010] According to this embodiment, it is possible to selectively hydrolyze a cyclic compound having a five-membered ring structure contained in a saturated cyclic compound used as a hydrogen carrier. In other words, even when a cyclic compound having a five-membered ring structure is hydrolyzed in a state where it is mixed in a hydrogen carrier, it is possible to appropriately hydrolyze the cyclic compound while suppressing loss of the hydrogen carrier (i.e., unintended chemical reaction).

[0011] In the above embodiment, the metal may contain 1 to 50% by weight of cobalt.

[0012] According to this embodiment, an appropriate amount of cobalt is supported on the catalyst support, so that the hydrogenolysis of a cyclic compound having a five-membered ring structure can be stably carried out.

[0013] In the above embodiment, the metal may contain 5% by weight or more of cobalt.

[0014] According to this embodiment, the selectivity to lighter hydrocarbons having fewer carbon numbers (eg, C1-C5 alkanes) can be effectively increased.

[0015] In order to solve the above problems, one aspect of the present invention is a method for hydrogenolysis of a cyclic compound having a five-membered ring structure contained in a saturated cyclic compound used as a hydrogen carrier, using the above metal catalyst, which is configured to produce an aromatic compound and a cyclic compound having a five-membered ring structure as an impurity by a dehydrogenation reaction of the saturated cyclic compound, perform a hydrogenation reaction of the aromatic compound containing the impurity, and perform hydrogenolysis using the metal catalyst on a mixture of the saturated cyclic compound and the impurity produced by the hydrogenation reaction of the aromatic compound.

[0016] According to this embodiment, in a system based on an organic chemical hydride method, it becomes possible to selectively hydrolyze a cyclic compound having a five-membered ring structure contained in a saturated cyclic compound used as a hydrogen carrier.

[0017] In the above aspect, the hydrogenolysis may be carried out by supplying the mixture of the saturated cyclic compound and the impurities together with 50 to 99.8 mol % of hydrogen to the metal catalyst, the catalyst layer of which is maintained at a temperature of 150°C to 300°C.

[0018] According to this embodiment, the mixture of saturated cyclic compounds and impurities is subjected to hydrogenolysis at an appropriate catalytic temperature together with 50 to 99.8 mol % of hydrogen, whereby it is possible to stably hydrogenolyze cyclic compounds having a five-membered ring structure.

[0019] According to the above embodiment, it becomes possible to selectively hydrogenolyze a cyclic compound having a five-membered ring structure contained in a saturated cyclic compound used as a hydrogen carrier. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a hydrogen storage and transportation system according to an embodiment. [Diagram 2] An explanatory diagram showing the relationship between by-products and their boiling points in the dehydrogenation reaction of methylcyclohexane. [Diagram 3] Diagram of hydrogenolysis of methylcyclopentane [Figure 4] Diagram showing the distribution of reaction products during hydrogenolysis of MCP [Diagram 5] Diagram showing the distribution of reaction products during the hydrogenolysis of MCH [Figure 6] Diagram showing the distribution of reaction products during hydrocracking of a mixed feedstock of MCP and MCH DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, a metal catalyst according to an embodiment and a method for hydrogenolysis of a cyclic compound having a five-membered ring structure (hereinafter referred to as a five-membered ring compound) using the same will be described with reference to the drawings. Here, an example in which the metal catalyst and the hydrogenolysis method using the same are applied to a hydrogen storage and transportation system 1 based on an organic chemical hydride method shown in FIG.

[0022] The hydrogen storage and transportation system 1 includes a hydrogenation plant 2 that generates saturated cyclic compounds as organic hydrides by adding hydrogen to aromatic compounds, and a dehydrogenation plant 3 that generates hydrogen and aromatic compounds by dehydrogenating the saturated cyclic compounds. Here, an example is described in which methylcyclohexane (abbreviated as "MCH" as necessary) is used as the saturated cyclic compound, and toluene (abbreviated as "TOL" as necessary) is used as the aromatic compound.

[0023] The hydrogenation plant 2 has a hydrogenation reactor 11 that produces methylcyclohexane by carrying out a hydrogenation reaction of adding hydrogen (H2) to toluene based on a known method. The hydrogenation plant 2 is provided with a storage facility 4. The storage facility 4 has an MCH storage tank 12 that stores the methylcyclohexane produced by the hydrogenation reactor 11. The storage facility 4 also has a TOL storage tank 13 for storing toluene transported from the dehydrogenation plant 3 side (i.e., the storage facility 5).

[0024] The dehydrogenation plant 3 has a dehydrogenation reactor 21 that produces hydrogen and toluene by carrying out a dehydrogenation reaction of methylcyclohexane based on a known method. The dehydrogenation plant 3 is additionally provided with a storage facility 5. The storage facility 5 has a TOL storage tank 22 that stores the toluene produced by the dehydrogenation reactor 21. The storage facility 5 also has an MCH storage tank 23 for storing methylcyclohexane transported from the hydrogenation plant 2 side (storage facility 4).

[0025] In the hydrogen storage and transportation system 1, the methylcyclohexane stored in the MCH storage tank 12 is transported to the dehydrogenation plant 3 using known transportation means (ship, vehicle, pipeline, etc.) and stored in the MCH storage tank 23. The methylcyclohexane stored in the MCH storage tank 23 is used for the dehydrogenation reaction in the dehydrogenation reaction apparatus 21. On the other hand, the toluene stored in the TOL storage tank 22 is transported to the hydrogenation plant 2 using known transportation means and stored in the TOL storage tank 13. The toluene stored in the TOL storage tank 13 is used for the hydrogenation reaction in the hydrogenation reaction apparatus 11. In this way, methylcyclohexane and toluene are repeatedly used as hydrogen containers (hydrogen carriers).

[0026] As shown in FIG. 2(A), the dehydrogenation reaction in the dehydrogenation reactor 21 produces by-products including five-membered ring compounds in addition to hydrogen and toluene. Such five-membered ring compounds include dimethylcyclopentanes (e.g., 1,1-dimethylcyclopentane, 1,3-cis-dimethylcyclopentane, 1,3-trans-dimethylcyclopentane, and 1,2-trans-dimethylcyclopentane) and ethylcyclopentane. On the other hand, the boiling points of the five-membered ring compounds are relatively close to the boiling points of methylcyclohexane and toluene, which serve as hydrogen carriers, as shown in FIG. 2(B), and therefore it is not easy to separate them from the hydrogen carrier by distillation.

[0027] The five-membered ring compound produced in the dehydrogenation reactor 21 is stored in a TOL storage tank 22 mixed with toluene, and then sent to the hydrogenation plant 2 via the TOL storage tank 13. Therefore, the methylcyclohexane produced in the hydrogenation plant 2 may contain the five-membered ring compound derived from the above-mentioned dehydrogenation reaction as an impurity. This five-membered ring compound is sent again to the dehydrogenation plant 3 mixed with methylcyclohexane, and circulates within the hydrogen storage and transportation system 1. The five-membered ring compound may be produced not only by the dehydrogenation reaction in the dehydrogenation reactor 21, but also by the hydrogenation reaction in the hydrogenation reactor 11.

[0028] Therefore, the hydrogen storage and transportation system 1 is equipped with a hydrogen cracking device 6 that performs a hydrogen cracking reaction of the five-membered ring compounds mixed in the hydrogen carrier. The hydrogen cracking device 6 uses a metal catalyst (hereinafter referred to as the "hydrogen cracking catalyst") to selectively hydrogen-crack the five-membered ring compounds mixed in as impurities in methylcyclohexane, converting them into light linear hydrocarbons.

[0029] The hydrocracker 6 can, for example, extract at least a portion of the product of the hydrogenation reaction (mainly methylcyclohexane, for example, 98 wt% or more) produced by the hydrogenation plant 2 as a processing target before being stored in the storage facility 4, and perform a hydrocracking reaction. In the hydrocracker 6, the five-membered ring compounds in the product of the hydrogenation reaction are decomposed into lighter hydrocarbons (for example, pentane, hexane, heptane, etc.). In particular, the five-membered ring compounds can be decomposed into lighter hydrocarbons with fewer carbon numbers (for example, C1-C5 alkanes) by appropriately selecting a metal used in the hydrocracking catalyst. These hydrocarbons can be removed (i.e., separated) from the methylcyclohexane by distillation or other known processes. The methylcyclohexane from which the five-membered ring compounds have been removed (or reduced) is mixed again with the product of the hydrogenation plant 2.

[0030] The target of treatment by the hydrocracker 6 may be methylcyclohexane (containing five-membered ring compounds as impurities) extracted from the MCH storage tank 12 of the storage facility 4. In this case, the methylcyclohexane from which the five-membered ring compounds have been removed by the hydrocracker 6 is returned to the MCH storage tank 12. The hydrocracker 6 may be connected to a supply line (not shown) for the raw material to the dehydrogenation reactor 21 and may constitute a part of the dehydrogenation plant 3.

[0031] Alternatively, the subject of treatment by the hydrocracker 6 may be methylcyclohexane (containing five-membered ring compounds as impurities) extracted from the MCH storage tank 23 of the storage facility 5. In this case, the methylcyclohexane from which the five-membered ring compounds have been removed by the hydrocracker 6 is returned to the MCH storage tank 23. In addition, the hydrocracker 6 may be connected to a discharge line (not shown) for the product of the hydrogenation reaction apparatus 11 and form part of the hydrogenation plant 2.

[0032] As the hydrogenolysis apparatus 6, for example, a fixed-bed flow-type reactor is used. The hydrogenolysis apparatus 6 is equipped with a temperature regulator (for example, an electric heater or a heat exchanger using a heat medium). In the hydrogenolysis reaction in the hydrogenolysis apparatus 6, the temperature regulator preferably maintains the temperature of the catalyst layer made of the hydrogenolysis catalyst within a range of, for example, 150°C to 300°C. The metal catalyst according to this embodiment exhibits good catalytic performance even when the temperature of the catalyst layer is 200°C or lower. In addition, the reaction raw material used in the hydrogenolysis reaction may contain, for example, 50 to 99.8 mol% hydrogen together with a mixture of methylcyclohexane and a five-membered ring compound.

[0033] The hydrogenolysis catalyst used in the hydrogenolysis device 6 may be, for example, a hydrogenolysis catalyst containing silica as a catalyst support and cobalt as a metal supported on the catalyst support. The hydrogenolysis catalyst may contain 1 to 50 wt% (weight %) of cobalt. More preferably, the hydrogenolysis catalyst may contain 5 wt% or more of cobalt. As the silica-based support as the catalyst support, amorphous silica may be used. However, the silica-based support is not limited to amorphous silica, and may be, for example, pure silica zeolites including silicalite-1, zeolite beta, and high silica USY (ultra-stable Y), or regular mesoporous silica including FSM-16, MCM-41, MCM-48, and SBA-15.

[0034] The organic hydride used in the hydrogen storage and transportation system 1 is not limited to the above-mentioned methylcyclohexane, as long as it is an organic compound that reversibly releases hydrogen at least by a catalytic reaction. In the hydrogen storage and transportation system 1, as the organic hydride, monocyclic hydrogenated aromatic compounds such as methylcyclohexane and cyclohexane, bicyclic hydrogenated aromatic compounds such as tetralin, decalin, and methyldecalin, and tricyclic hydrogenated aromatic compounds such as tetradecahydroanthracene, etc., can be used alone or as a mixture of two or more kinds. When the organic hydride is changed to toluene obtained by the dehydrogenation reaction of methylcyclohexane, other aromatic compounds corresponding to it are used.

[0035] Hereinafter, based on Examples 1 to 4 and Comparative Example 1, preferred embodiments of the hydrogenolysis catalyst and the method for hydrogenolysis of five-membered ring compounds using the same according to the present invention will be specifically described.

[0036] The above-mentioned hydrogen cracking unit 6 is premised on hydrogen cracking five-membered ring compounds mixed as impurities in the product of the hydrogenation reaction in the hydrogenation plant 2 (or generated as a by-product of the reaction) using a hydrogen cracking catalyst. The reaction raw material in the hydrogen cracking unit 6 (i.e., the target of the hydrogen cracking reaction) is a mixture of methylcyclohexane generated by the hydrogenation reaction of toluene and five-membered ring compounds. In Examples 1-3 and Comparative Example 1, methylcyclopentane (abbreviated as "MCP" as necessary) was used as a model compound for the five-membered ring compounds contained in (i.e., mixed into) the reaction raw material. In Example 4, a mixed raw material of MCP and MCH (hereinafter, sometimes referred to as "MCP+MCH") was used to more closely resemble reality.

[0037] For example, as shown in FIG. 3, in the hydrogenolysis of methylcyclopentane (MCP), the ring of MCP is cleaved at positions (1)-(3), and chain compounds (hexane, 2-methylpentane, 3-methylpentane, etc.) can be produced according to the position of the cleavage. Furthermore, these chain compounds can be further decomposed to produce C1-C5 alkanes. Unlike five-membered ring compounds, the products of these hydrogenolysis reactions can be easily separated from methylcyclohexane by distillation or other known processes. Similarly, the products of the hydrogenolysis reaction of ethylcyclopentane and other five-membered ring compounds can also be easily separated from methylcyclohexane.

[0038] Table 1 shows a list of the catalyst samples used in Examples 1-4 and Comparative Example 1. As will be described later in detail, in Examples 1-4, catalysts in which different amounts of cobalt (Co) are supported on amorphous silica as a catalyst support are used. In addition, as Comparative Example 1, a catalyst sample in which platinum (Pt) is supported on a commercially available support described later is used.

[0039] [Table 1]

[0040] Table 2 shows the reaction materials used in Examples 1-4 and Comparative Example 1.

[0041] [Table 2]

[0042] In Examples 1-3 and Comparative Example 1, the performance of each catalyst sample was evaluated when methylcyclopentane (MCP) as a five-membered ring compound and methylcyclohexane (MCH) as a hydrogen carrier were supplied to a reactor together with hydrogen as reaction raw materials. As shown in Table 2, in Examples 1-3 and Comparative Example 1, when MCP is used as the reaction raw material, the hydrogen / MCP ratio (mol / mol) in the reaction raw material is 28. When MCH is used as the reaction raw material, the hydrogen / MCH ratio (mol / mol) in the reaction raw material is 28.

[0043] In Example 4, assuming the actual raw material in the hydrocracking unit 6, a mixed raw material of 10 mol % methylcyclopentane as a five-membered ring compound and 90 mol % methylcyclohexane as a hydrogen carrier was prepared and fed to the reactor together with hydrogen to evaluate the performance of each catalyst sample. As shown in Table 2, in Example 4, the hydrogen / (MCP+MCH) ratio (mol / mol) in the reaction raw material was 28.

[0044] In Examples 1-4, cobalt (Co) was used as the active species, which selectively promotes the hydrogenolysis reaction that cleaves the carbon-carbon bond of a five-membered ring compound in the presence of hydrogen, on the assumption that the hydrogenolysis reaction is carried out in a mild temperature range where the temperature of the catalyst layer is about 200° C. In addition, a silica-based material that does not exhibit solid acidity that can cause side reactions such as isomerization reactions was used as the catalyst support.

[0045] Example 1 3. Preparation method of 0 wt%-Co / SiO2 catalyst In a 300 mL eggplant flask, 0.2294 g of cobalt nitrate hexahydrate (Co(NO3)2 6H2O) and 75 mL of pure water were added and thoroughly dissolved by ultrasonic irradiation. Then, amorphous silica powder (AEROSIL® 380, Nippon Aerosil Co., Ltd., BET specific surface area 380 m) was added as a carrier. 21.5356 g of Co / g was added and stirred at room temperature for 1 hour, and the silica was impregnated and supported so that the loading rate as Co metal was 3.0 wt%. After evaporating to dryness at 40°C using an evaporator, the collected product was transferred to an oven and dried overnight at 80°C to collect powder. The powder was pressurized and then crushed appropriately and sieved to 500-600 μm. In the reduction treatment of the catalyst, 1.2001 g of the sized catalyst was filled into a fixed bed flow device and heated to 400°C over 30 minutes under nitrogen flow (30 mL / min), then switched to hydrogen flow (30 mL / min) and reduction treatment was performed for 1 hour, and then cooled to room temperature while maintaining the hydrogen flow atmosphere to obtain a 3.0 wt%-Co / SiO2 catalyst.

[0046] 3.0 wt%-Co / SiO2 catalyst performance evaluation test method [Hydrogenolysis reaction of methylcyclopentane (MCP) (see Table 2)] The performance evaluation test of the 3.0 wt%-Co / SiO2 catalyst prepared by the above procedure was carried out according to the following procedure. The catalyst was pretreated by filling 206.0 mg of the 3.0 wt%-Co / SiO2 catalyst into a fixed-bed flow reactor, heating it to 400 °C over 30 minutes under nitrogen flow (30 mL / min), and then switching to hydrogen flow (40 mL / min) for 1 hour to carry out reduction treatment. After reduction treatment, the hydrogenolysis reaction of methylcyclopentane (MCP) was carried out for a specified time under the conditions of hydrogen flow rate 40 mL / min, H2 / MCP = 28 mol / mol, W / F (ratio of catalyst amount to MCP flow rate) = 58.81 g-cat. h / mol, reaction temperature 200 °C, and total pressure 0.1 MPa. The product was sampled 5 minutes after the start of the hydrogenolysis reaction, and the conversion rate (%) of MCP and the selectivity (C-%) of the reaction product were determined by FID-GC (flame ionization detector-type gas chromatograph) analysis, which were used as indicators of catalyst performance (see Table 3 and Figure 4 below for the results of the performance evaluation test).

[0047] [Hydrogenolysis reaction of methylcyclohexane (MCH) (see Table 2)] The performance evaluation test of the 3.0 wt%-Co / SiO2 catalyst prepared by the above procedure was carried out according to the following procedure. The catalyst was pretreated by filling 206.0 mg of the 3.0 wt%-Co / SiO2 catalyst into a fixed-bed flow reactor, heating it to 400 °C over 30 minutes under nitrogen flow (30 mL / min), and then switching to hydrogen flow (30 mL / min) for 1 hour to carry out reduction treatment. After reduction treatment, the hydrogenolysis reaction of methylcyclohexane (MCH) was carried out for a specified time under the conditions of hydrogen flow rate 40 mL / min, H2 / MCH = 28 mol / mol, W / F (ratio of catalyst amount to MCH flow rate) = 58.77 g-cat. h / mol, reaction temperature 200 °C, and total pressure 0.1 MPa. The product was sampled 5 minutes after the start of the hydrogenolysis reaction, and the MCH conversion (%) and the selectivity (C-%) of the reaction product were determined by FID-GC analysis, which were used as indicators of catalyst performance (see Table 3 and Figure 5 below for the results of the performance evaluation test).

[0048] Example 2 Preparation method of 5.0 wt%-Co / SiO2 catalyst In a 300 mL eggplant flask, 0.3796 g of cobalt nitrate hexahydrate (Co(NO3)2 6H2O) and 75 mL of pure water were added and thoroughly dissolved by ultrasonic irradiation. Then, amorphous silica powder (AEROSIL® 380, Nippon Aerosil Co., Ltd., BET specific surface area 380 m) was added as a carrier. 2 1.5220 g of Co / g was added and stirred at room temperature for 1 hour, and the silica was impregnated and supported so that the Co metal loading rate was 5.0 wt%. After evaporating to dryness at 40°C using an evaporator, the collected product was transferred to an oven and dried overnight at 80°C to collect the powder. The powder was pressurized and then crushed appropriately, and sieved to 500-600 μm. In the reduction treatment of the catalyst, 1.2026 g of the sized catalyst was filled into a fixed bed flow device and heated to 400°C over 30 minutes under nitrogen flow (30 mL / min), and then switched to hydrogen flow (30 mL / min) and reduction treatment was performed for 5 hours, and then cooled to room temperature while maintaining the hydrogen flow atmosphere to obtain a 5.0 wt%-Co / SiO2 catalyst.

[0049] Test method for evaluating the performance of 5.0 wt%-Co / SiO2 catalyst [Hydrogenolysis reaction of methylcyclopentane (MCP) (see Table 2)] The performance evaluation test of the 5.0 wt%-Co / SiO2 catalyst prepared by the above procedure was carried out according to the following procedure. The catalyst was pretreated by filling 210.0 mg of the 5.0 wt%-Co / SiO2 catalyst into a fixed-bed flow reactor, heating it to 400 °C over 30 minutes under nitrogen flow (30 mL / min), and then switching to hydrogen flow (40 mL / min) for 1 hour to carry out reduction treatment. After reduction treatment, the hydrogenolysis reaction of methylcyclopentane (MCP) was carried out for a specified time under the conditions of hydrogen flow rate 40 mL / min, H2 / MCP = 28 mol / mol, W / F (ratio of catalyst amount to MCP flow rate) = 59.95 g-cat. h / mol, reaction temperature 200 °C, and total pressure 0.1 MPa. The product was sampled 5 minutes after the start of the hydrogenolysis reaction, and the MCP conversion rate (%) and the selectivity (C-%) of the reaction product were determined by FID-GC analysis, which were used as indicators of catalyst performance (see Table 3 and Figure 4 below for the results of the performance evaluation test).

[0050] [Hydrogenolysis reaction of methylcyclohexane (MCH) (see Table 2)] The performance evaluation test of the 5.0 wt%-Co / SiO2 catalyst prepared by the above procedure was carried out according to the following procedure. The catalyst was pretreated by filling 210.0 mg of the 5.0 wt%-Co / SiO2 catalyst into a fixed-bed flow reactor, heating it to 400 °C over 30 minutes under nitrogen flow (30 mL / min), and then switching to hydrogen flow (40 mL / min) for 1 hour to carry out reduction treatment. After reduction treatment, the hydrogenolysis reaction of methylcyclohexane (MCH) was carried out for a specified time under the conditions of hydrogen flow rate 40 mL / min, H2 / MCH = 28 mol / mol, W / F (ratio of catalyst amount to MCH flow rate) = 59.91 g-cat. h / mol, reaction temperature 200 °C, and total pressure 0.1 MPa. The product was sampled 5 minutes after the start of the hydrogenolysis reaction, and the MCH conversion (%) and the selectivity (C-%) of the reaction product were determined by FID-GC analysis, which were used as indicators of catalyst performance (see Table 3 and Figure 5 below for the results of the performance evaluation test).

[0051] Example 3 Preparation method of 10 wt%-Co / SiO2 catalyst In a 500 mL eggplant flask, 1.4944 g of cobalt nitrate hexahydrate (Co(NO3)2 6H2O) and 150 mL of pure water were added and thoroughly dissolved by ultrasonic irradiation. Then, amorphous silica powder (AEROSIL® 380, Nippon Aerosil Co., Ltd., BET specific surface area 380 m) was added as a carrier. 2 3.0182 g of Co / g was added and stirred at room temperature for 1 hour, and the silica was impregnated and supported so that the Co metal loading rate was 10 wt%. After evaporating to dryness at 40°C using an evaporator, the collected product was transferred to an oven and dried overnight at 80°C to collect the powder. The powder was pressurized and then crushed appropriately and sieved to 500-600 μm. In the reduction treatment of the catalyst, 1.2753 g of the sized catalyst was filled into a fixed bed flow device and heated to 400°C over 30 minutes under nitrogen flow (30 mL / min), then switched to hydrogen flow (40 mL / min) and reduction treatment was performed for 5 hours, and then cooled to room temperature while maintaining the hydrogen flow atmosphere to obtain a 10 wt%-Co / SiO2 catalyst.

[0052] Test method for evaluating the performance of 10 wt%-Co / SiO2 catalyst [Hydrogenolysis reaction of methylcyclopentane (MCP) (see Table 2)] The performance evaluation test of the 10 wt%-Co / SiO2 catalyst prepared by the above procedure was carried out according to the following procedure. The catalyst was pretreated by filling 220.0 mg of the 10 wt%-Co / SiO2 catalyst into a fixed-bed flow reactor, heating it to 400 °C over 30 minutes under nitrogen flow (30 mL / min), and then switching to hydrogen flow (30 mL / min) for 1 hour to carry out reduction treatment. After reduction treatment, the hydrogenolysis reaction of methylcyclopentane (MCP) was carried out for a specified time under the conditions of hydrogen flow rate 40 mL / min, H2 / MCP = 28 mol / mol, W / F (ratio of catalyst amount to MCP flow rate) = 62.80 g-cat. h / mol, reaction temperature 200 °C, and total pressure 0.1 MPa. The product was sampled 5 minutes after the start of the hydrogenolysis reaction, and the MCP conversion rate (%) and the selectivity (C-%) of the reaction product were determined by FID-GC analysis, which were used as indicators of catalyst performance (see Table 3 and Figure 4 below for the results of the performance evaluation test).

[0053] [Hydrogenolysis reaction of methylcyclohexane (MCH) (see Table 2)] The performance evaluation test of the 10 wt%-Co / SiO2 catalyst prepared by the above procedure was carried out according to the following procedure. The catalyst was pretreated by filling 220.0 mg of the 10 wt%-Co / SiO2 catalyst into a fixed-bed flow reactor, heating it to 400 °C over 30 minutes under nitrogen flow (30 mL / min), and then switching to hydrogen flow (40 mL / min) for 1 hour to carry out reduction treatment. After reduction treatment, the hydrogenolysis reaction of methylcyclohexane (MCH) was carried out for a specified time under the conditions of hydrogen flow rate 40 mL / min, H2 / MCH = 28 mol / mol, W / F (ratio of catalyst amount to MCH flow rate) = 62.76 g-cat. h / mol, reaction temperature 200 °C, and total pressure 0.1 MPa. The product was sampled 5 minutes after the start of the hydrogenolysis reaction, and the MCH conversion (%) and the selectivity (C-%) of the reaction product were determined by FID-GC analysis, which were used as indicators of catalyst performance (see Table 3 and Figure 5 below for the results of the performance evaluation test).

[0054] Example 4 Preparation method of 10 wt%-Co / SiO2 catalyst A 10 wt%-Co / SiO2 catalyst was obtained in the same manner as in Example 3.

[0055] Test method for evaluating the performance of 10 wt%-Co / SiO2 catalyst [Hydrogenolysis reaction of a mixed feedstock of methylcyclopentane (MCP) and methylcyclohexane (MCH) (see Table 2)] The performance evaluation test of the 10 wt%-Co / SiO2 catalyst prepared by the above procedure was carried out according to the following procedure. The catalyst was pretreated by filling 220.0 mg of the 10 wt%-Co / SiO2 catalyst into a fixed-bed flow reactor, heating it to 400 °C over 30 minutes under nitrogen flow (30 mL / min), and then switching to hydrogen flow (40 mL / min) for 1 hour to carry out reduction treatment. After reduction treatment, the hydrogenolysis reaction of a mixture of methylcyclopentane (MCP) and methylcyclohexane (MCH) was carried out for a specified time under the conditions of hydrogen flow rate of 40 mL / min, H2 / (MCP + MCH) = 28 mol / mol (H2: MCP : MCH = 28 : 0.1 : 0.9), W / F (ratio of catalyst amount to (MCP + MCH) flow rate) = 67.95 g-cat. h / mol, reaction temperature of 200 °C, and total pressure of 0.1 MPa. The products were sampled 5 minutes after the start of the hydrogenolysis reaction, and the conversion rates of MCP and MCH (%) and the selectivity of the reaction products (C-%) were determined by FID-GC analysis, and used as indicators of catalyst performance (see Table 4 and FIG. 6 below for the results of the performance evaluation test).

[0056] Comparative Example 1 Preparation method of 1.0 wt%-Pt / SiO2 catalyst A commercially available (Sigma-Aldrich, 520691-25G) silica-supported platinum catalyst (1.0 wt%-Pt / SiO2) was used as the catalyst sample (see Table 1).

[0057] Test method for evaluating the performance of 1.0 wt%-Pt / SiO2 catalyst [Hydrogenolysis reaction of methylcyclopentane (MCP) (see Table 2)] The performance evaluation test of the above-mentioned commercial product (1.0 wt%-Pt / SiO2 catalyst) was carried out according to the following procedure. The catalyst was pretreated by filling 101.0 mg of 1.0 wt%-Pt / SiO2 catalyst into a fixed-bed flow-type reactor, heating it to 400 °C over 30 minutes under nitrogen flow (30 mL / min), and then switching to hydrogen flow (40 mL / min) for 1 hour to carry out reduction treatment. After reduction treatment, the hydrogenolysis reaction of methylcyclopentane (MCP) was carried out for a specified time under the conditions of hydrogen flow rate 40 mL / min, H2 / MCP = 28 mol / mol, W / F (ratio of catalyst amount to MCP flow rate) = 28.83 g-cat. h / mol, reaction temperature 200 °C, and total pressure 0.1 MPa. The product was sampled 5 minutes after the start of the hydrogenolysis reaction, and the MCP conversion rate (%) and the selectivity (C-%) of the reaction product were determined by FID-GC analysis, which were used as indicators of catalyst performance (see Table 3 and Figure 4 below for the results of the performance evaluation test).

[0058] [Hydrogenolysis reaction of methylcyclohexane (MCH) (see Table 2)] The performance evaluation test of the above-mentioned commercial product (1.0 wt%-Pt / SiO2 catalyst) was carried out according to the following procedure. The catalyst was pretreated by filling 101.0 mg of 1.0 wt%-Pt / SiO2 catalyst into a fixed-bed flow-type reactor, heating it to 400 °C over 30 minutes under nitrogen flow (30 mL / min), and then switching to hydrogen flow (40 mL / min) for 1 hour to carry out reduction treatment. After reduction treatment, the hydrogenolysis reaction of methylcyclohexane (MCH) was carried out for a specified time under the conditions of hydrogen flow rate 40 mL / min, H2 / MCH = 28 mol / mol, W / F (ratio of catalyst amount to MCH flow rate) = 28.81 g-cat. h / mol, reaction temperature 200 °C, and total pressure 0.1 MPa. The product was sampled 5 minutes after the start of the hydrogenolysis reaction, and the MCH conversion (%) and the selectivity (C-%) of the reaction product were determined by FID-GC analysis, which were used as indicators of catalyst performance (see Table 3 and Figure 5 below for the results of the performance evaluation test).

[0059] Table 3 shows the results of the performance evaluation test of each catalyst in Examples 1-3 and Comparative Example 1. Fig. 4 shows the distribution of reaction products in the hydrogenolysis of MCP in the performance evaluation test of each catalyst in Examples 1-3 and Comparative Example 1. Fig. 5 shows the distribution of reaction products in the hydrogenolysis of MCH in the performance evaluation test of each catalyst, similar to Fig. 4. In the performance evaluation test of each catalyst, the hydrogenolysis reaction was carried out under the same conditions using methylcyclopentane (MCP) and methylcyclohexane (MCH) as the sole reaction raw materials.

[0060] [Table 3]

[0061] As shown in Table 3, in Comparative Example 1 (1.0 wt%-Pt / SiO2 catalyst), when MCP was used as the raw material, the hydrogenolysis reaction hardly occurred, and the conversion rate of MCP was less than 1%. When MCP was used as the raw material, the reaction products were the direct ring-opening products n-hexane, 2-methylpentane, and 3-methylpentane, as shown in Figure 4. Also, as shown in Table 3, when MCH was used as the raw material, the conversion rate of MCH was less than 3%. When MCH was used as the raw material, the reaction products were all toluene (TOL), as shown in Figure 5.

[0062] According to the results of Comparative Example 1, when platinum was used as the active species supported on silica, activity was shown in the dehydrogenation aromatization reaction of cyclohexanes (here, the reaction of producing TOL by dehydrogenation of MCH), but almost no activity was shown in the hydrogenolysis reaction of cyclopentanes (here, MCP).

[0063] In contrast, in Example 1 (3.0 wt%-Co / SiO2 catalyst), activity was observed in the hydrogenolysis reaction of MCP, and the conversion rate of MCP was about 2% (see Table 3). When MCP was used as the raw material, the reaction products were about 20% C1-C5 alkanes (i.e., light alkanes with 1-5 carbon atoms), which are easily separated in the subsequent process, and the remainder were direct ring-opening products such as n-hexane, 3-methylpentane, and 2-methylpentane, as well as naphthenes such as cyclopentane and cyclohexane (see Figure 4). When MCH was used as the raw material, the hydrogenolysis reaction hardly occurred, the conversion rate of MCH was less than 1% (see Table 3), and the reaction product was all toluene (TOL) (see Figure 5).

[0064] In Example 2 (5.0 wt%-Co / SiO2 catalyst), the activity of the hydrogenolysis reaction of MCP was further improved compared to Example 1, and the conversion rate of MCP was 20.5% (see Table 3). When MCP was used as the raw material, the reaction products were 73.6% C1-C5 alkanes, and the rest were direct ring-opening products (i.e., n-hexane, 2-methylpentane, and 3-methylpentane) and naphthenes (i.e., cyclopentane and cyclohexane) (see Figure 4). When MCH was used as the raw material, the hydrogenolysis reaction hardly occurred, as in Example 1, and the conversion rate of MCH was less than 1% (see Table 3). When MCH was used as the raw material, the reaction products were 39% C1-C5 alkanes (see Figure 5).

[0065] In Example 3 (10 wt%-Co / SiO2 catalyst), the activity of the hydrogenolysis reaction of MCP was further improved compared to Examples 1 and 2, and the conversion rate of MCP reached 32.7% (see Table 3). When MCP was used as the raw material, the reaction products were 76.8% C1-C5 alkanes, and the rest were direct ring-opening products (i.e., n-hexane, 2-methylpentane, and 3-methylpentane) and naphthenes (i.e., cyclopentane and cyclohexane) (see Figure 4). When MCH was used as the raw material, the hydrogenolysis reaction hardly occurred, as in Examples 1 and 2, and the conversion rate of MCH was less than 1% (see Table 3). When MCH was used as the raw material, the reaction products were 39% C1-C5 alkanes (see Figure 5).

[0066] The results of Examples 1-3 show that cobalt as an active species supported on amorphous silica exhibits high cracking activity and high selectivity to C1-C5 alkanes in the hydrogenolysis of cyclopentanes, while its activity in the hydrogenolysis of cyclohexanes is low.

[0067] In Examples 1-3, the metal catalyst (i.e., hydrogenolysis catalyst) used in the hydrogenolysis reaction of cyclopentanes contains 3.0 wt%, 5.0 wt%, and 10 wt%, respectively, but the same effect can be expected with a cobalt content in the range of 1.0 wt% to 50 wt%. In particular, in order to effectively increase the selectivity to C1-C5 alkanes, it is preferable that the hydrogenolysis catalyst contains at least 5 wt% cobalt as an active species.

[0068] In Example 4, the 10 wt%-Co / SiO2 catalyst (Example 3), which showed the best performance in Examples 1-3, was used to carry out the hydrogenolysis reaction of a mixed feedstock of MCP and MCH in order to more closely approximate reality. Table 4 shows the performance evaluation test results of each catalyst in Example 4. Figure 6 shows the distribution of reaction products in the hydrogenolysis of MCP+MCH in relation to the performance evaluation test of each catalyst in Example 4.

[0069] [Table 4]

[0070] As shown in Table 4, in Example 4, the overall conversion rate of the MCP+MCH mixed raw material was 16.6%, of which the conversion rate of MCP was 13.2%, and the conversion rate of MCH was 3.4%.

[0071] From these results, it was confirmed that the 10 wt%-Co / SiO2 catalyst highly selectively hydrolyzed MCP while suppressing the hydrolysis of MCH, even in the performance evaluation test using MCP+MCH assuming practical application to the hydrogen storage and transportation system 1 shown in Figure 1.

[0072] In addition, as shown in Figure 6, the reaction product contained 58.2% C1-C5 alkanes even when MCP+MCH was used as the raw material, confirming that cracking to light alkanes proceeded with high selectivity.

[0073] Thus, from the results of Examples 1 to 4 (see Tables 3 and 4 and Figures 4 to 6), it was found that by applying a metal catalyst in which cobalt is supported on a silica-based carrier such as amorphous silica, cyclopentanes contained in methylcyclohexane can be hydrocracked to light alkanes with high selectivity.

[0074] Although the description of the specific embodiment has been completed above, the present invention is not limited to the above embodiment and modified examples, and can be widely modified and implemented. The metal catalysts and the components of the method for hydrocracking a cyclic compound using the same shown in the above embodiment are not necessarily all essential, and at least those skilled in the art can select them appropriately without departing from the scope of the present invention.

[0075] For example, the application of the metal catalyst and the method for hydrocracking a cyclic compound using the same according to the present invention is not limited to the hydrocracking device 6 provided in the above-mentioned hydrogen storage and transportation system 1. They can be widely applied to the hydrocracking of cyclic compounds having a five-membered ring structure contained in saturated cyclic compounds. [Explanation of symbols]

[0076] 1: Transportation system 2: Hydrogenation plant 3: Dehydrogenation plant 4: Storage facilities 5: Storage facilities 6: Hydrogenolysis device 11: Hydrogenation reactor 12:MCH storage tank 13:TOL storage tank 21: Dehydrogenation reactor 22:TOL storage tank 23:MCH storage tank

Claims

1. A metal catalyst for use in the hydrogenolysis of a cyclic compound having a five-membered ring structure contained in a saturated cyclic compound used as a hydrogen carrier, comprising: A silica-based carrier as a catalyst carrier; Cobalt as a metal supported on the catalyst support; A metal catalyst comprising:

2. 2. The metal catalyst according to claim 1, comprising 1 to 50% by weight of cobalt as said metal.

3. 3. The metal catalyst according to claim 2, comprising at least 5% by weight of cobalt as said metal.

4. The metal catalyst according to claim 1 or 2, wherein the silica-based support comprises amorphous silica.

5. A method for hydrogenolysis of a cyclic compound having a five-membered ring structure contained in the saturated cyclic compound used as a hydrogen carrier, using the metal catalyst according to any one of claims 1 to 3, comprising the steps of: a dehydrogenation reaction of the saturated cyclic compound to produce an aromatic compound and a cyclic compound having a five-membered ring structure as an impurity thereof; carrying out a hydrogenation reaction of the aromatic compound contaminated with the impurities; a hydrogenolysis method, comprising carrying out hydrogenolysis on a mixture of the saturated cyclic compounds and the impurities produced by the hydrogenation reaction of the aromatic compound, using the metal catalyst.

6. The hydrolysis method according to claim 5, wherein the hydrolysis is carried out by supplying the mixture of the saturated cyclic compounds and the impurities together with 50 to 99.8 mol % of hydrogen to the metal catalyst, the catalyst layer of which is maintained at a temperature of 150° C. to 300° C.

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