System and method for producing aromatic hydrocarbon

Abstract

This aromatic hydrocarbon production system is provided with: a xylene synthesis reactor which is filled with a xylene synthesis catalyst and which synthesizes an aromatic hydrocarbon from methanol by means of a xylene synthesis reaction in the presence of water vapor; a methanol supply line for supplying methanol to the xylene synthesis reactor; and a water vapor supply line that supplies water vapor to the xylene synthesis reactor.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a system and a method for producing aromatic hydrocarbons including xylene from CO2. BACKGROUND

[0002] Xylene is an important basic chemical used as a raw material for high-purity terephthalic acid, which is a raw material for resins for polyester fibers or plastic bottles. In the past, xylene derived from fossil fuels has been produced. In recent years, as one of "carbon cycle technologies" that capture and recover CO2 discharged from factories and the like as resources and seek effective use of the recovered CO2, industrial production of xylene from CO2 has been proposed.

[0003] The process flow of industrial production of xylene from CO2 includes: (1) a methanol synthesis step of synthesizing methanol from CO2 and H2; (2) a xylene synthesis step of synthesizing xylene from methanol; and (3) a terephthalic acid separation step of separating terephthalic acid from xylene. In addition, xylene has three xylene isomers of terephthalic acid, o-xylene, and m-xylene, and in the terephthalic acid separation step, terephthalic acid is selectively separated from aromatic hydrocarbons including xylene.

[0004] In the past, a technology of converting methanol into aromatic hydrocarbons by bringing methanol into contact with a zeolite catalyst has been known. For example, a technology of synthesizing xylene from methanol using a zeolite catalyst is disclosed in Patent Literature 1.

[0005] Prior Art Documents: Patent Literature: Patent Literature 1: Japanese Patent Application Publication No. 2007-137840 SUMMARY

[0006] Problems to be Solved by the Invention: In a reaction of synthesizing xylene from methanol using a catalyst, when the xylene synthesis catalyst is deactivated, the xylene synthesis reaction stops. The longer the reaction time of the xylene synthesis catalyst until deactivation, that is, the longer the life of the catalyst, the lower the frequency and cost of maintenance such as catalyst replacement.

[0007] The present disclosure was made in view of the above circumstances, and an object thereof is to provide a technology that can prolong the reaction time of a xylene synthesis catalyst that promotes synthesis of xylene from methanol until deactivation, that is, the life of the catalyst, in a system and a method for producing aromatic hydrocarbons.

[0008] Means for Solving the Problems: The present inventors have made a new finding that, in a reaction for synthesizing xylene from methanol using a xylene synthesis catalyst, the time until the xylene synthesis catalyst is deactivated, i.e., the life of the catalyst, is lengthened by adding water vapor to the methanol.

[0009] In this disclosure, one form of the aromatic hydrocarbon production system is characterized by comprising: a xylene synthesis reactor filled with a xylene synthesis catalyst, which synthesizes an aromatic hydrocarbon from methanol and water vapor through a xylene synthesis reaction; a methanol supply line that supplies methanol to the xylene synthesis reactor; and a water vapor supply line that supplies water vapor to the xylene synthesis reactor.

[0010] In this disclosure, one form of the aromatic hydrocarbon production method is characterized by comprising: supplying methanol to a xylene synthesis reactor filled with a xylene synthesis catalyst; supplying water vapor to the xylene synthesis reactor; and synthesizing an aromatic hydrocarbon from methanol and water vapor through a xylene synthesis reaction using the xylene synthesis reactor.

[0011] Effects of the Invention According to the present disclosure, it is possible to provide a technology that can lengthen the reaction time until a xylene synthesis catalyst, which promotes the synthesis of xylene from methanol, is deactivated, i.e., the life of the catalyst, in an aromatic hydrocarbon production system and method. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 a graph showing the relationship between the reaction time of the xylene synthesis catalyst and the methanol conversion rate when the water vapor concentration in the raw material is changed in a xylene synthesis reaction using a xylene synthesis catalyst; Figure 2 a block diagram showing the overall structure of the aromatic hydrocarbon production system according to one embodiment of the present disclosure; Figure 3 a block diagram showing the overall structure of the aromatic hydrocarbon production system according to Modification 1. DETAILED DESCRIPTION

[0013] The aromatic hydrocarbon production system according to the present disclosure utilizes a reaction in which methanol is converted into an aromatic hydrocarbon containing xylene (hereinafter referred to as "xylene synthesis reaction") by bringing the methanol into contact with a xylene synthesis catalyst. In the aromatic hydrocarbon production system according to the present disclosure, by bringing the methanol into contact with the xylene synthesis catalyst in the presence of water vapor, an aromatic hydrocarbon is generated while suppressing the rate of deactivation of the catalyst.

[0014] In a xylene synthesis reaction using a xylene synthesis catalyst, an experiment for confirming the relationship between the water vapor concentration in a raw material and the life of the xylene synthesis catalyst was performed. In this experiment, a zeolite catalyst was used as the xylene synthesis catalyst, and a raw material of 400°C mixed with 16 mol% of methanol, a mol% of water vapor, and (84 - a) mol% of nitrogen was continuously supplied to a reaction vessel filled with the xylene synthesis catalyst, and the amount of methanol contained in the exhaust gas from the reaction vessel was measured every one hour. The methanol conversion rate [%] was calculated from the measured value. The conversion rate of methanol is the amount of methanol converted to aromatic hydrocarbons with respect to the total amount of methanol supplied, expressed in percentage. The concentration a of water vapor was varied to be 0, 4, 8, 16.

[0015] Figure 1 A graph showing the relationship between the reaction time of the xylene synthesis catalyst and the methanol conversion rate when the water vapor concentration in the raw material was changed in the xylene synthesis reaction using the xylene synthesis catalyst is shown. In the graph, the horizontal axis represents the reaction time of the xylene synthesis catalyst, and the vertical axis represents the methanol conversion rate. In the graph, the solid line represents the case where the water vapor concentration in the raw material was 0, the dashed line represents the case where the water vapor concentration in the raw material was 4, the chain line represents the case where the water vapor concentration in the raw material was 8, and the one-dot chain line represents the case where the water vapor concentration in the raw material was 16. Figure 1In the graph, the vertical axis represents the methanol conversion rate [%], and the horizontal axis represents the reaction time of the catalyst for xylene synthesis. When the water vapor concentration in the raw material was 0 mol%, the methanol conversion rate from the start of the reaction until 2 hours had passed was 100%, but the methanol conversion rate decreased to about 80% after 2 hours. When the water vapor concentration in the raw material was 4 mol%, the methanol conversion rate from the start of the reaction until 3 hours had passed was 100%, but the methanol conversion rate decreased to about 70% after 4 hours. When the water vapor concentration in the raw material was 8 mol%, the methanol conversion rate from the start of the reaction until 4 hours had passed was 100%, but the methanol conversion rate decreased to about 70% after 5 hours. When the water vapor concentration in the raw material was 16 mol%, the methanol conversion rate from the start of the reaction until 4 hours had passed was 100%, but the methanol conversion rate decreased to about 70% after 5 hours. From these results, it was judged that the catalyst for xylene synthesis was deactivated in 3 hours when the water vapor concentration in the raw material was 0 mol%, in 4 hours when the water vapor concentration in the mixed gas was 4 mol%, and in 5 hours when the water vapor concentration in the mixed gas was 8 mol% and 16 mol%. Thus, it was found that by bringing methanol into contact with the catalyst for xylene synthesis in the presence of water vapor, it was possible to generate aromatic hydrocarbons while suppressing the deactivation rate of the catalyst. By suppressing the deactivation rate of the catalyst, the life of the catalyst was lengthened. Also, it was shown that when the methanol concentration in the raw material brought into contact with the catalyst for xylene synthesis was 16 mol%, if the water vapor concentration in the raw material was 4 mol% or more, that is, the concentration of water vapor was 1 / 4 or more relative to the concentration of methanol, the suppression effect of the deactivation rate of the catalyst was obtained. Furthermore, it was shown that when the methanol concentration in the raw material brought into contact with the catalyst for xylene synthesis was 16 mol%, if the water vapor concentration in the raw material was 8 mol% or more, that is, the concentration of water vapor was 1 / 2 or more relative to the concentration of methanol, the suppression effect of the deactivation rate of the catalyst did not change.

[0016] Structure of the aromatic hydrocarbon manufacturing system 100 Figure 2 A block diagram showing the overall structure of the aromatic hydrocarbon manufacturing system 100 according to the present disclosure. The aromatic hydrocarbon manufacturing system 100 according to the present disclosure is responsible for (1) a methanol synthesis process of synthesizing methanol from CO2 and H2 and (2) a xylene synthesis process of synthesizing xylene from methanol in a process of industrially manufacturing p-xylene using H2 (hydrogen) and CO2 (carbon dioxide) as raw materials, and manufacturing an aromatic hydrocarbon 97 containing xylene.

[0017] The aromatic hydrocarbon manufacturing system 100 includes a methanol synthesis reactor 11 and a xylene synthesis reactor 12.

[0018] The methanol synthesis reactor 11 is a reaction vessel in which a methanol synthesis reaction caused by hydrogenation of CO2 is performed. The methanol synthesis reactor 11 is filled with a methanol synthesis catalyst 110. The methanol synthesis catalyst 110 promotes a methanol synthesis reaction in which methanol and water vapor are generated from CO2 and H2 (CO2 + 3H2→ CH3OH + H2O). The methanol synthesis catalyst 110 is not particularly limited as long as it is a catalyst that promotes a reaction in which methanol is generated from CO2. As such a methanol synthesis catalyst 110, a Cu-based catalyst (reaction temperature: about 250°C, reaction pressure: 3 to 5 MPa), a metal oxide catalyst, and the like are known.

[0019] The methanol synthesis reactor 11 is connected to a raw material gas line 21 and a first product line 22.

[0020] A raw material gas 91 containing H2 and CO2 is supplied to the methanol synthesis reactor 11 through the raw material gas line 21. The H2 in the raw material gas 91 is generated, for example, by electrolysis of water. The CO2 in the raw material gas 91 is supplied from a carbon dioxide supply source 46. The carbon dioxide supply source 46 will be described later in detail.

[0021] A compressor 48 is provided on the raw material gas line 21. The compressor 48 pressurizes the raw material gas 91 to a pressure suitable for the methanol synthesis reaction. Also, a raw material heater 31 is provided on the raw material gas line 21. The raw material heater 31 warms the raw material gas 91 to a temperature suitable for the methanol synthesis reaction. The reaction temperature and the reaction pressure of the methanol synthesis reaction differ depending on the methanol synthesis catalyst 110. For example, when the methanol synthesis catalyst 110 is a Cu-based catalyst, the reaction temperature is about 250°C, and the reaction pressure is 3 to 5 MPa.

[0022] A first fluid 92 discharged from the methanol synthesis reactor 11 flows into the first product line 22. The first fluid 92 flowing into the first product line 22 contains, in addition to methanol and water vapor that are reaction products of the methanol synthesis reaction, unreacted H2 and CO2.

[0023] A first heat recoverer 32 is provided on the first product line 22. The first heat recoverer 32 recovers thermal energy possessed by the first fluid 92. For example, the first heat recoverer 32 has a first heat medium flow path 360 in which a first heat medium 36 that recovers thermal energy of the first fluid 92 by heat exchange with the first fluid 92 flows. In the first heat recoverer 32, the first heat medium 36 and the first fluid 92 are in contact with each other. Figure 2 In the first heat recoverer 32, the movement of the first heat medium 36 is indicated by a dotted line. The flow path of the first heat medium 36 is formed by a pipe or the like. The first heat medium 36 that has recovered thermal energy of the first fluid 92 is heat-exchanged with the raw material gas 91 by the raw material heater 31. That is, the thermal energy recovered from the first fluid 92 in the first heat recoverer 32 is used for heating of the raw material gas 91.

[0024] A first gas-liquid separator 41 is provided downstream of the first heat exchanger 32 in the first product line 22. The first gas-liquid separator 41 separates and removes a gaseous component such as water vapor from the first fluid 92 flowing through the first product line 22. The gaseous component separated from the first fluid 92 in the first gas-liquid separator 41 includes unreacted H2and CO2. A portion of the gaseous component separated from the first fluid 92 is returned to the raw material gas line 21 through a circulation line 28. A compressor 49 is provided on the circulation line 28, and the gaseous component returned from the first gas-liquid separator 41 to the raw material gas 91 is pressurized to a pressure suitable for the methanol synthesis reaction by the compressor 49.

[0025] The first fluid 92 from which the gaseous component has been separated, i.e., a liquid containing a large amount of methanol, flows downstream of the first gas-liquid separator 41 in the first product line 22. The liquid also contains water resulting from the liquefaction of water vapor contained in the first fluid 92. A pressure reducer 51 is provided downstream of the first gas-liquid separator 41 in the first product line 22. The first fluid 92 is depressurized by the pressure reducer 51.

[0026] A second gas-liquid separator 42 is provided downstream of the pressure reducer 51 in the first product line 22. A portion of the first fluid 92 vaporized by the depressurization by the pressure reducer 51 is separated from the first fluid 92 by the second gas-liquid separator 42. Thus, the gaseous component and the liquid component of the first fluid 92 are separated by the two-stage gas-liquid separators, the first gas-liquid separator 41 and the second gas-liquid separator 42, and methanol 94 is separated from the first fluid 92. The methanol 94 contains water resulting from the liquefaction of water vapor. The second gas-liquid separator 42 is connected to a methanol supply line 23. The methanol 94 is supplied to the xylene synthesis reactor 12 through the methanol supply line 23. In addition, the fluid flowing through the methanol supply line 23 can contain water 99 (or water vapor 99a) in addition to the methanol 94.

[0027] The xylene synthesis reactor 12 is connected to the methanol supply line 23, the water vapor supply line 24, and the second product line 26.

[0028] The xylene synthesis reactor 12 is a reaction vessel in which a xylene synthesis reaction is performed. The xylene synthesis reactor 12 is filled with a xylene synthesis catalyst 120. The xylene synthesis catalyst 120 promotes a synthesis reaction from methanol to aromatic hydrocarbons in the presence of water vapor. The type of the xylene synthesis catalyst 120 is not particularly limited. As the xylene synthesis catalyst 120, for example, a zeolite catalyst is known, and the reaction temperature is about 400 to 600°C.

[0029] Methanol 94 is supplied to the xylene synthesis reactor 12 through a methanol supply line 23. The methanol supply line 23 is provided with a methanol heater 33. The methanol heater 33 warms the methanol 94 to a temperature suitable for the xylene synthesis reaction. Here, it is also possible that the vaporized methanol 94 and water 99 are supplied to the xylene synthesis reactor 12 through the methanol supply line 23. In this case, the methanol supply line 23 functions as a water vapor supply line as well. The water 99 and methanol 94 flowing out of the second gas-liquid separator 42 to the methanol supply line 23 are warmed by the methanol heater 33 provided to the methanol supply line 23, and become water vapor 99a and gaseous methanol 94, which flow into the xylene synthesis reactor 12.

[0030] Water vapor 95 is supplied to the xylene synthesis reactor 12 through a water vapor supply line 24. In order to adjust the water vapor concentration in the xylene synthesis reactor 12, it is also possible to dilute the water vapor 95 with nitrogen gas. The water vapor supply line 24 is provided with a pump 50. The pump 50 pressurizes the water vapor 95 to a pressure suitable for the xylene synthesis reaction and sends it out to the xylene synthesis reactor 12. Further, a water vapor heater 35 is provided to the water vapor supply line 24 downstream of the pump 50. The water vapor heater 35 warms the water vapor 95 to a temperature suitable for the xylene synthesis reaction. As described above, when the methanol supply line 23 functions as a water vapor supply line as well, the water vapor supply line 24 can be omitted.

[0031] When the methanol 94 and water vapor 95, 99a are supplied to the xylene synthesis reactor 12, a synthesis reaction of xylene is generated by the action of the xylene synthesis catalyst 120. In the reaction product of the xylene synthesis reactor 12, in addition to aromatic hydrocarbons, lower hydrocarbons are also contained. In the aromatic hydrocarbons in the reaction product, benzene, toluene, and the three xylene isomers can be contained. In the lower hydrocarbons in the reaction product, C2-C4 olefins such as ethylene and propylene, and C1-C5 alkanes such as methane, ethane, propane, and butane can be contained. However, depending on the kind of the xylene synthesis catalyst 120, the composition and the ratio of the aromatic hydrocarbons and the lower hydrocarbons contained in the reaction product are different.

[0032] The second fluid 96 discharged from the xylene synthesis reactor 12 flows into the second product line 26. In the second fluid 96 flowing into the second product line 26, in addition to the aromatic hydrocarbons which are the reaction product of the xylene synthesis reaction, lower hydrocarbons and water vapor are also contained.

[0033] The second product line 26 is provided with a second heat exchanger 34. The second heat exchanger 34 recovers the thermal energy possessed by the second fluid 96. For example, the second heat exchanger 34 has a second heat medium flow path 370 in which a second heat medium 37 flows, and the second heat medium 37 recovers the thermal energy possessed by the second fluid 96 by heat exchange with the second fluid 96. In the second heat exchanger 34, the second heat medium 37 is warmed by the thermal energy possessed by the second fluid 96, and the second heat medium 37 is sent out to the second heat medium line 36. Figure 2In the second heat medium 37, the movement of the second heat medium 37 is indicated by a double dotted line. In addition, the flow path of the second heat medium 37 is formed by a pipe or the like. The second heat medium 37, from which the heat energy of the second fluid 96 is recovered, exchanges heat with the methanol 94 by the methanol heater 33. That is, the heat energy recovered from the second fluid 96 in the second heat recovery device 34 is used for heating the methanol 94. Also, the second heat medium 37, from which the heat energy of the second fluid 96 is recovered, exchanges heat with the water vapor 95 by the water vapor heater 35. That is, the heat energy recovered from the second fluid 96 in the second heat recovery device 34 is used for heating the water vapor 95.

[0034] A third gas-liquid separator 45 is provided at a position downstream of the second heat recovery device 34 in the second product line 26. The third gas-liquid separator 45 separates the second fluid 96 into a gas component and a liquid component. The liquid component of the second fluid 96 contains water, which is liquefied water vapor, and aromatic hydrocarbons 97, which include xylene. The water and the aromatic hydrocarbons 97 are separated by specific gravity. The gas component of the second fluid 96 contains aliphatic hydrocarbons 98, which include ethylene or propylene, or the like, as olefinic lower hydrocarbons.

[0035] A product line 27 is provided to the third gas-liquid separator 45. The aromatic hydrocarbons 97 separated from the second fluid 96 by the third gas-liquid separator 45 flow into the product line 27. The aromatic hydrocarbons 97 are sent to a subsequent xylene separation process by the product line 27. In the xylene separation process, xylene is separated from the aromatic hydrocarbons 97, and the xylene is used as a material for a chemical product.

[0036] Structure of the carbon dioxide supply source 46 The carbon dioxide supply source 46 of the aromatic hydrocarbon manufacturing system 100 according to the present disclosure includes a carbon dioxide absorbent 43 that reversibly absorbs CO2 by a chemical absorption method, and an absorbent heater 53 that heats the carbon dioxide absorbent 43. In the carbon dioxide supply source 46, the carbon dioxide absorbent 43 is heated by the absorbent heater 53, and thereby releases CO2 adsorbed to the carbon dioxide absorbent 43. The released CO2 is sent to the raw material gas line 21 and used as the raw material gas 91. The carbon dioxide absorbent 43 from which the CO2 is released is used again to absorb CO2.

[0037] As the carbon dioxide absorbent 43, a liquid amine-based carbon dioxide absorbent 43 (i.e., a carbon dioxide chemical absorption liquid) is used. However, as the carbon dioxide absorbent 43, a solid carbon dioxide absorbent 43 (i.e., a carbon dioxide chemical absorption material) can also be used. The solid carbon dioxide absorbent 43 is a substance in which a porous carrier such as zeolite holds an amine compound that reversibly absorbs CO2 by adsorption. As the amine typically used in the carbon dioxide absorbent 43, alkanolamines such as monoethanolamine and methyldiethanolamine, sterically hindered amines such as 2-amino-2-methyl-l-propanol, and cyclic amines such as piperazine can be listed. The absorption temperature and the release temperature of CO2 by the carbon dioxide absorbent 43 differ depending on the properties of the carbon dioxide absorbent 43 or the kind of the amine, etc. For example, the carbon dioxide absorbent 43 that utilizes the neutralization reaction of an aqueous alkanolamine solution with CO2 absorbs CO2 at 40 to 50°C and releases CO2 at 110 to 130°C. The method of releasing CO2 from the carbon dioxide absorbent 43 employs an appropriate method corresponding to the kind of the carbon dioxide absorbent 43. For example, CO2 can be released by indirectly heating the liquid carbon dioxide absorbent 43. Also, for example, CO2 can be released by indirectly heating the solid carbon dioxide absorbent 43 or by bringing the carbon dioxide absorbent 43 into contact with water vapor.

[0038] The structure of the carbon dioxide supply source 46 is not particularly limited and can be exemplified as follows: (i) In the case of using a liquid carbon dioxide absorbent 43, the carbon dioxide supply source 46 is provided with an absorption vessel and a release vessel that contain the carbon dioxide absorbent 43, and an absorbent heater 53 that indirectly heats the carbon dioxide absorbent 43 in the release vessel. The absorption vessel and the release vessel are in communication. A gas containing CO2 is supplied to the absorption vessel, and CO2 is absorbed by the carbon dioxide absorbent 43. The carbon dioxide absorbent 43 that has absorbed CO2 moves to the release vessel. In the release vessel, CO2 is released from the carbon dioxide absorbent 43 by heating the carbon dioxide absorbent 43. The carbon dioxide absorbent 43 from which CO2 has been released moves to the absorption vessel; (ii) In the case of using a solid carbon dioxide absorbent 43, the carbon dioxide supply source 46 has a series of reaction vessels in which the carbon dioxide absorbent 43 flows, and during the period in which a part of the carbon dioxide absorbent 43 is used for the absorption of CO2, a part of the remaining carbon dioxide absorbent 43 is released of CO2 by heating by the absorbent heater 53; (iii) In the case of using the solid carbon dioxide absorbent 43, the carbon dioxide supply source 46 has a plurality of reaction vessels filled with the carbon dioxide absorbent 43, and during the period in which a part of the reaction vessels is used for the absorption of CO2, the remaining part of the reaction vessels is used for the release of CO2 by heating by the absorbent heater 53.

[0039] In order to release CO2from the carbon dioxide absorbent 43, the heat energy recovered from the first fluid 92, i.e., a part of the heat generated by the methanol synthesis, can be used. At this time, the first heat medium 36, which has recovered the heat energy of the first fluid 92 by the first heat exchanger 32, is supplied to the absorbent heater 53 of the carbon dioxide supply source 46 after heating the raw material gas 91 by heat exchange with the raw material gas 91 via the raw material heater 31, and is used for the heating of the carbon dioxide absorbent 43.

[0040] In addition, in order to release CO2from the carbon dioxide absorbent 43, the heat energy recovered from the second fluid 96, i.e., a part of the heat generated by the xylene synthesis reaction, can also be used. At this time, the second heat medium 37, which has recovered the heat energy of the second fluid 96 by the second heat exchanger 34, is supplied to the absorbent heater 53 of the carbon dioxide supply source 46 after heating the methanol 94 by heat exchange with the methanol 94 via the methanol heater 33, and is used for the heating of the carbon dioxide absorbent 43. Also, the second heat medium 37, which has recovered the heat energy of the second fluid 96 by the second heat exchanger 34, is supplied to the absorbent heater 53 of the carbon dioxide supply source 46 after heating the water vapor 95 by heat exchange with the water vapor 95 via the water vapor heater 35, and is used for the heating of the carbon dioxide absorbent 43.

[0041] In the carbon dioxide supply source 46, in order to release CO2from the carbon dioxide absorbent 43, at least one of the heat energy recovered from the first fluid 92 and the heat energy recovered from the second fluid 96 can be used. However, in order to more effectively utilize the heat energy within the system, it is preferable that both the heat energy recovered from the first fluid 92 and the heat energy recovered from the second fluid 96 be used for the release of CO2from the carbon dioxide absorbent 43.

[0042] The CO2 release temperature of the CO2 absorbent 43 is lower than the methanol synthesis reaction temperature, and the methanol synthesis reaction temperature is lower than the xylene synthesis reaction temperature. Also, both the methanol synthesis reaction and the xylene synthesis reaction are exothermic reactions, and the temperature of the second fluid 96 discharged from the xylene synthesis reactor 12 is higher than the temperature of the first fluid 92 discharged from the methanol synthesis reactor 11. According to the temperature relationship within the system, in order to more effectively utilize the heat energy within the system, the heat energy of the second fluid 96 recovered by the second heat exchanger 34 can also be used for heating the raw material gas 91 and the methanol 94, and then used for heating the CO2 absorbent 43. Similarly, the heat energy of the second fluid 96 recovered by the second heat exchanger 34 can also be used for heating the raw material gas 91 and the water vapor 95, and then used for heating the CO2 absorbent 43.

[0043] In Figure 3 In the aromatic hydrocarbon manufacturing system 100 (100A) according to the modification example 1, the raw material gas line 21 is provided with the first raw material heater 31 that exchanges heat between the first heat medium 36 and the raw material gas 91, and the second raw material heater 31 that exchanges heat between the second heat medium 37 and the raw material gas 91. The first heat medium 36 that has recovered the heat energy of the first fluid 92 by the first heat exchanger 32 exchanges heat with the raw material gas 91 by the first raw material heater 31 to heat the raw material gas 91, and then is supplied to the absorbent heater 53 to be used for heating the CO2 absorbent 43. The second heat medium 37 that has recovered the heat energy of the second fluid 96 by the second heat exchanger 34 first exchanges heat with the methanol 94 by the methanol heater 33 to heat the methanol 94, then exchanges heat with the raw material gas 91 by the second raw material heater 31 to heat the raw material gas 91, and finally is supplied to the absorbent heater 53 of the CO2 supply source 46 to be used for heating the CO2 absorbent 43. Also, the second heat medium 37 that has recovered the heat energy of the second fluid 96 by the second heat exchanger 34 first exchanges heat with the water vapor 95 by the water vapor heater 35 to heat the water vapor 95, then exchanges heat with the raw material gas 91 by the second raw material heater 31 to heat the raw material gas 91, and finally is supplied to the absorbent heater 53 of the CO2 supply source 46 to be used for heating the CO2 absorbent 43. In addition, the aromatic hydrocarbon manufacturing system 100A according to the modification example 1 is substantially the same as the aromatic hydrocarbon manufacturing system 100 according to the above-described embodiment except for the flow of the second heat medium 37.

[0044] 〔Summary〕 The aromatic hydrocarbon manufacturing system 100 according to the first item of the present disclosure includes: a xylene synthesis reactor 12 filled with a xylene synthesis catalyst 120 that synthesizes an aromatic hydrocarbon 97 from methanol 94 by a xylene synthesis reaction in the presence of water vapor 95, 99a; a methanol supply line 23 that supplies the methanol 94 to the xylene synthesis reactor 12; a water vapor supply line 23, 24 that supplies the water vapor 99a, 95 to the xylene synthesis reactor 12, Here, the concentration of the water vapor 99a, 95 in the gas that contacts the xylene synthesis catalyst 120 in the xylene synthesis reactor 12 is preferably 1 / 4 or more of the concentration of the methanol 94. The concentration ratio of the methanol 94 to the water vapor 99a, 95 in the gas that contacts the xylene synthesis catalyst 120 can also be about 1:1. Furthermore, water can also be added as a diluent for suppressing the heat release at the time of the reaction, in which case the concentration of the water vapor 99a, 95 in the gas that contacts the xylene synthesis catalyst 120 is preferably higher than the concentration of the methanol 94, and for example, the volume ratio of the water vapor 99a, 95 to the methanol 94 in the gas that contacts the xylene synthesis catalyst 120 can also be about 9:1. In an extreme example, the volume ratio of the water vapor 99a, 95 to the methanol 94 in the gas that contacts the xylene synthesis catalyst 120 can also be about 99:1.

[0045] In the xylene synthesis reactor 12 of the manufacturing system 100 of the above structure, the methanol 94 is converted into the aromatic hydrocarbon 97 by the xylene synthesis catalyst 120 in the presence of the water vapor 99a, 95. It is known that by contacting the methanol 94 with the xylene synthesis catalyst 120 in the presence of the water vapor 99a, 95, it is possible to generate the aromatic hydrocarbon 97 while suppressing the deactivation rate of the catalyst 120. Thus, in the aromatic hydrocarbon manufacturing system 100, by the suppression of the deactivation rate of the xylene synthesis catalyst 120, it is possible to extend the life of the xylene synthesis catalyst 120, and it is possible to reduce the frequency of replacement of the xylene synthesis catalyst 120.

[0046] The manufacturing system 100 of the aromatic hydrocarbon 97 according to the second item of the present disclosure is a manufacturing system 100 of the aromatic hydrocarbon 97 according to the first item of the present disclosure, and is provided with: a methanol synthesis reactor 11 that synthesizes the methanol 94 by a methanol synthesis reaction accompanied by the generation of water vapor from a raw material gas 91 that includes hydrogen and carbon dioxide; a raw material gas line 21 that supplies the raw material gas 91 to the methanol synthesis reactor 11; and a gas-liquid separator 41, 42 that separates the methanol 94 and the water 99 from the first fluid 92 that is discharged from the methanol synthesis reactor 11 that includes the reaction product of the methanol synthesis reaction, a methanol supply line 23 that supplies the methanol 94 and the water 99 that are separated from the first fluid 92 by the gas-liquid separator 44 as the methanol 94 and the water vapor 99a to the xylene synthesis reactor 12, the methanol supply line 23 serving also as a water vapor supply line.

[0047] In the manufacturing system 100 of the above structure, water generated by the methanol synthesis reaction can be effectively utilized for the xylene synthesis reaction.

[0048] The manufacturing system 100 of the aromatic hydrocarbon 97 according to the third aspect of the present disclosure is the manufacturing system 100 of the aromatic hydrocarbon 97 according to the first aspect, further comprising: a methanol synthesis reactor 11 that synthesizes methanol 94 by a methanol synthesis reaction from a raw material gas 91 containing hydrogen and carbon dioxide; a gas-liquid separator 41, 42 that separates the methanol 94 from a first fluid 92 discharged from the methanol synthesis reactor 11 including a reaction product of the methanol synthesis reaction; and a methanol supply line 23 that supplies the methanol 94 separated from the first fluid 92 with the gas-liquid separator 41, 42 to the xylene synthesis reactor 12.

[0049] In the manufacturing system 100 of the aromatic hydrocarbon 97 according to the second and third aspects, the reaction of generating the aromatic hydrocarbon 97 from CO2 and H2 is divided into two stages of the methanol synthesis reaction with the methanol synthesis reactor 11 and the xylene synthesis reaction with the xylene synthesis reactor 12. Thus, the methanol synthesis reaction and the xylene synthesis reaction can be given appropriate reaction conditions, respectively. Also, unreacted CO2 and H2 can be separated at a stage before being mixed with by-products such as the aliphatic hydrocarbon 98 in the xylene synthesis reaction and returned to the methanol synthesis reactor 11, and the aliphatic hydrocarbon 98 can be recovered as a valuable substance in a subsequent stage.

[0050] The manufacturing system 100 of the aromatic hydrocarbon 97 according to the fourth aspect of the present disclosure is the manufacturing system 100 of the aromatic hydrocarbon 97 according to the second or third aspect, further comprising: a first heat recovery device 32 that recovers heat energy from the first fluid 92; a second heat recovery device 34 that recovers heat energy from a second fluid 96 discharged from the xylene synthesis reactor 12 including a reaction product of the xylene synthesis reaction; and a carbon dioxide supply source 46 having: a carbon dioxide absorbent 43 that reversibly absorbs carbon dioxide; and an absorbent heater 53 that heats the carbon dioxide absorbent 43 with at least one of heat energy recovered from the first fluid 92 and heat energy recovered from the second fluid 96, and supplies carbon dioxide released from the carbon dioxide absorbent 43 by the heating to the raw material gas line 21.

[0051] In the conventional aromatic hydrocarbon manufacturing system, when CO2 adsorbed to the carbon dioxide absorbent is used as a raw material, in order to supply the raw material gas, particularly in order to cause CO2 to desorb from the carbon dioxide absorbent, a large amount of energy is supplied from the outside of the system, and thus there is a problem that the cost becomes high. In contrast, in the aromatic hydrocarbon 97 manufacturing system 100 according to the present disclosure, the heat generated in the process of manufacturing the aromatic hydrocarbon 97 is effectively utilized for the supply of CO2 included in the raw material gas 91, that is, for the supply of the raw material gas 91. Thus, it is possible to reduce the energy supplied from the outside of the system for the supply of the raw material gas 91, and it is possible to reduce the cost involved in the supply of the raw material gas 91. Also, the energy is recycled within the system, and the loss of energy is small, and thus the emission of CO2 is suppressed.

[0052] The aromatic hydrocarbon 97 manufacturing system 100 according to the fifth aspect of the present disclosure is the aromatic hydrocarbon 97 manufacturing system 100 according to the fourth aspect of the present disclosure, The first heat exchanger 32 has a first heat medium flow path 360 in which a first heat medium 36 that recovers the heat energy of the first fluid 92 by heat exchange with the first fluid 92 flows, and has a raw material heater 31 that heats the raw material gas 91 by heat exchange with the first heat medium 36, and the first heat medium 36 is supplied to the absorbent heater 53 via the first raw material heater 31.

[0053] In the manufacturing system 100 having the above-described structure, the heat energy recovered from the first fluid 92 is used for the heating of the raw material gas 91, and then used for the heating of the carbon dioxide absorbent 43. The temperature at which CO2 is released from the carbon dioxide absorbent 43 is sufficiently low compared to the temperature of the raw material gas 91 suitable for the methanol synthesis reaction. Thus, even the heat energy after the heating of the raw material gas 91 can be used for the desorption of CO2, and the heat energy of the first fluid 92 can be effectively utilized.

[0054] The aromatic hydrocarbon 97 manufacturing system 100 according to the sixth aspect of the present disclosure is the aromatic hydrocarbon 97 manufacturing system 100 according to the fourth or fifth aspect of the present disclosure, The second heat exchanger 34 has a second heat medium flow path 370 in which a second heat medium 37 that recovers the heat energy of the second fluid 96 by heat exchange with the second fluid 96 flows, and has a methanol heater 33 that is disposed in the methanol supply line 23 and heats the methanol 94 by heat exchange with the second heat medium 37, and the second heat medium 37 is supplied to the absorbent heater 53 via the methanol heater 33.

[0055] In the production system 100 described above, the heat energy recovered from the second fluid 96 is used for heating of the carbon dioxide absorbent 43 after being used for heating of the methanol 94. The temperature at which CO2is released from the carbon dioxide absorbent 43 is sufficiently low compared to the temperature of the methanol 94 suitable for the xylene synthesis reaction. Therefore, even the heat energy after being used for heating of the raw material gas 91 can be used for release of CO2, and the heat energy of the second fluid 96 can be effectively utilized.

[0056] The production system 100 of the aromatic hydrocarbon 97 according to the seventh aspect of the present disclosure is the production system 100 of the aromatic hydrocarbon 97 according to any one of the fourth to sixth aspects of the present disclosure, wherein The second heat medium 37 is supplied to the absorbent heater 53 via the methanol heater 33 and the raw material heater 31.

[0057] In the production system 100 described above, the heat energy recovered from the second fluid 96 is used for heating of the carbon dioxide absorbent 43 after being used for heating of the methanol 94 and the raw material gas 91. The temperature at which CO2is released from the carbon dioxide absorbent 43 is sufficiently low compared to the temperature of the raw material gas 91 suitable for the methanol synthesis reaction. Therefore, even the heat energy after being used for heating of the methanol 94 and the raw material gas 91 can be used for release of CO2, and the heat energy of the second fluid 96 can be effectively utilized.

[0058] The production system 100 of the aromatic hydrocarbon 97 according to the eighth aspect of the present disclosure is the production system 100 of the aromatic hydrocarbon 97 according to any one of the fourth to seventh aspects of the present disclosure, wherein The second heat medium 37 is supplied to the absorbent heater 53 via the water vapor heater 35. The second heat medium 37 is supplied to the absorbent heater 53 via the water vapor heater 35.

[0059] In the production system 100 described above, the energy recovered from the second fluid 96 is used for heating of the carbon dioxide absorbent 43 after being used for heating of the water vapor 95. The temperature at which CO2is released from the carbon dioxide absorbent 43 is sufficiently low compared to the temperature of the water vapor 95 suitable for the xylene synthesis reaction. Therefore, even the heat energy after being used for heating of the water vapor 95 can be used for release of CO2, and the heat energy of the second fluid 96 can be effectively utilized.

[0060] The manufacturing system 100 of the aromatic hydrocarbon 97 according to the ninth aspect of the present disclosure is the manufacturing system 100 of the aromatic hydrocarbon 97 according to the eighth aspect of the present disclosure, further comprising a second raw material heater 31 disposed in the raw material gas line 21 and configured to heat the raw material gas 91 by heat exchange with the second heat medium 37. The second heat medium 37 is supplied to the absorbent heater 53 via the water vapor heater 35 and the raw material heater 31.

[0061] In the manufacturing system 100 described above, the thermal energy recovered from the second fluid 96 is used for heating of the water vapor 95 and the raw material gas 91, and then for heating of the carbon dioxide absorbent 43. The temperature at which CO2 is released from the carbon dioxide absorbent 43 is sufficiently low compared to the temperature of the raw material gas 91 suitable for the methanol synthesis reaction. Therefore, even the thermal energy after the heating of the water vapor 95 and the raw material gas 91 can be used for the release of CO2, and the thermal energy of the second fluid 96 can be effectively utilized.

[0062] The manufacturing method of the aromatic hydrocarbon 97 according to the tenth aspect of the present disclosure includes: supplying the methanol 94 to the xylene synthesis reactor 12 filled with the xylene synthesis catalyst 120; supplying the water vapor 95, 99a to the xylene synthesis reactor 12, and synthesizing the aromatic hydrocarbon 97 from the methanol 94 by the xylene synthesis reaction in the presence of the water vapor 95, 99a using the xylene synthesis reactor 12.

[0063] In the manufacturing method of the aromatic hydrocarbon 97 described above, the methanol 94 is converted to the aromatic hydrocarbon 97 in the presence of the water vapor 99a, 95 by the xylene synthesis catalyst 120. It is known that by contacting the methanol 94 with the xylene synthesis catalyst 120 in the presence of the water vapor 99a, 95, the aromatic hydrocarbon 97 can be generated while suppressing the deactivation rate of the catalyst 120. By suppressing the deactivation rate of the xylene synthesis catalyst 120, the life of the xylene synthesis catalyst 120 can be extended, and the frequency of replacement of the xylene synthesis catalyst 120 can be reduced.

[0064] The manufacturing method of the aromatic hydrocarbon 97 according to the eleventh aspect of the present disclosure is the manufacturing method of the aromatic hydrocarbon 97 according to the tenth aspect of the present disclosure, further comprising: supplying the raw material gas 91 containing hydrogen and carbon dioxide to the methanol synthesis reactor 11; generating the first fluid 92 containing the methanol 94 and the water 99 from the raw material gas 91 by the methanol synthesis reaction using the methanol synthesis reactor 11; and separating the methanol 94 and the water 99 from the first fluid 92; supplying the methanol 94 and the water 99 separated from the first fluid 92 as the methanol 94 and the water vapor 99a to the xylene synthesis reactor 12.

[0065] The production method described above can effectively use water produced by the methanol synthesis reaction for the xylene synthesis reaction.

[0066] The production method of the aromatic hydrocarbon 97 according to the twelfth aspect of the present disclosure is the production method of the aromatic hydrocarbon 97 according to the tenth aspect of the present disclosure, including: supplying a raw material gas 91 containing hydrogen and carbon dioxide to the methanol synthesis reactor 11; generating a first fluid 92 containing methanol 94 from the raw material gas 91 by the methanol synthesis reaction with the methanol synthesis reactor 11; separating the methanol 94 from the first fluid 92; and supplying the methanol 94 separated from the first fluid 92 to the xylene synthesis reactor 12.

[0067] In the production method of the aromatic hydrocarbon 97 according to the eleventh and twelfth aspects of the present disclosure, the reaction of generating the aromatic hydrocarbon 97 from CO2 and H2 is divided into two stages of the methanol synthesis reaction with the methanol synthesis reactor 11 and the xylene synthesis reaction with the xylene synthesis reactor 12. Thereby, the methanol synthesis reaction and the xylene synthesis reaction can be given suitable reaction conditions, respectively. Also, unreacted CO2 and H2 can be separated at a stage before being mixed with by-products such as the aliphatic hydrocarbon 98 in the xylene synthesis reaction, and returned to the methanol synthesis reactor 11, and the aliphatic hydrocarbon 98 can be recovered as a valuable substance in a subsequent stage.

[0068] The production method of the aromatic hydrocarbon 97 according to the thirteenth aspect of the present disclosure is the production method of the aromatic hydrocarbon 97 according to the eleventh or twelfth aspect of the present disclosure, including: recovering heat energy from the first fluid 92; recovering heat energy from a second fluid 96 containing the aromatic hydrocarbon 97 generated by the xylene synthesis reaction with the xylene synthesis reactor 12; separating the aromatic hydrocarbon 97 from the second fluid 96; and causing carbon dioxide to desorb from a carbon dioxide absorbent 43 by heating the carbon dioxide absorbent 43 with at least one of the heat energy recovered from the first fluid 92 and the heat energy recovered from the second fluid 96, and using the desorbed carbon dioxide as a material of the raw material gas 91.

[0069] In the production method of the aromatic hydrocarbon 97 described above, heat generated in the production process of the aromatic hydrocarbon 97 is effectively used for the supply of CO2 contained in the raw material gas 91, that is, for the supply of the raw material gas 91. Therefore, energy supplied from the outside of the system for the supply of the raw material gas 91 can be reduced, and the cost involved in the supply of the raw material gas 91 can be reduced. Also, energy is recycled within the system, and the loss of energy is small, so that the emission of CO2 is suppressed.

[0070] The above discussion of the present disclosure is intended to be illustrative only and not limiting of the disclosure to the ways in which it is disclosed in the specification. For example, in the above detailed description, various features of the present disclosure were grouped together in a number of implementations for the purpose of streamlining the disclosure, but several of the features can be combined in other ways. In addition, several of the features of the present disclosure can be combined with alternative implementations, structures, or forms of the disclosure other than those discussed above.

[0071] Symbol explanation 11: methanol synthesis reactor 12: xylene synthesis reactor 21: raw material gas line 23: methanol supply line 24: water vapor supply line 31: raw material heater 32: first heat recovery device 33: methanol heater 34: second heat recovery device 35: water vapor heater 36: first heat medium 37: second heat medium 41: first gas-liquid separator 42: second gas-liquid separator 43: carbon dioxide absorbent 46: carbon dioxide supply source 53: absorbent heater 91: raw material gas 92: first fluid 94: methanol 95: water vapor 96: second fluid 97: aromatic hydrocarbon 360: first heat medium flow path 370: second heat medium flow path 100: aromatic hydrocarbon manufacturing system 120: xylene synthesis catalyst

Claims

1. A system for manufacturing aromatic hydrocarbons, characterized in that, Possessing: a xylene synthesis reactor filled with a catalyst for xylene synthesis, which synthesizes an aromatic hydrocarbon from methanol through a xylene synthesis reaction in the presence of water vapor; a methanol supply line that supplies methanol to the xylene synthesis reactor; and a water vapor supply line that supplies water vapor to the xylene synthesis reactor.

2. The aromatic hydrocarbon production system according to claim 1, characterized by: Possessing: a methanol synthesis reactor that synthesizes methanol from a raw material gas containing hydrogen and carbon dioxide through a methanol synthesis reaction with generation of water vapor; a raw material gas line that supplies the raw material gas to the methanol synthesis reactor; and a gas-liquid separator that separates methanol and water from a first fluid discharged from the methanol synthesis reactor containing a reaction product of the methanol synthesis reaction, the methanol supply line supplies, as methanol and water vapor, methanol and water separated from the first fluid by the gas-liquid separator to the xylene synthesis reactor, and the methanol supply line functions as the water vapor supply line.

3. The aromatic hydrocarbon production system according to claim 1, characterized by: Possessing: a methanol synthesis reactor that synthesizes methanol from a raw material gas containing hydrogen and carbon dioxide through a methanol synthesis reaction; a raw material gas line that supplies the raw material gas to the methanol synthesis reactor; a gas-liquid separator that separates methanol from a first fluid discharged from the methanol synthesis reactor containing a reaction product of the methanol synthesis reaction; and the methanol supply line that supplies methanol separated from the first fluid by the gas-liquid separator to the xylene synthesis reactor.

4. The aromatic hydrocarbon production system according to claim 2 or 3, characterized by: Possessing: a first heat recovery device that recovers heat energy from the first fluid; a second heat recovery device that recovers heat energy from a second fluid discharged from the xylene synthesis reactor containing a reaction product of the xylene synthesis reaction; and a carbon dioxide supply source that has a carbon dioxide absorbent that reversibly absorbs carbon dioxide, and an absorbent heater that heats the carbon dioxide absorbent with at least one of heat energy recovered from the first fluid and heat energy recovered from the second fluid, and supplies carbon dioxide that is desorbed from the carbon dioxide absorbent by heating to the raw material gas line.

5. The aromatic hydrocarbon production system according to claim 4, characterized in that: the first heat recovery device has a first heat medium flow path through which a first heat medium that recovers heat energy of the first fluid by heat exchange with the first fluid flows, a first raw material heater that heats the raw material gas by heat exchange with the first heat medium is provided, and the first heat medium is supplied to the absorbent heater via the first raw material heater.

6. The aromatic hydrocarbon production system according to claim 4, characterized in that: the second heat recovery device has a second heat medium flow path through which a second heat medium that recovers heat energy of the second fluid by heat exchange with the second fluid flows, a methanol heater that heats methanol by heat exchange with the second heat medium is provided in the methanol supply line, and the second heat medium is supplied to the absorbent heater via the methanol heater. ​ The second heat medium is supplied to the absorbent heater via the methanol heater.

7. The aromatic hydrocarbon production system according to claim 6, wherein a second raw material heater configured in the raw material gas line to heat the raw material gas by heat exchange with the second heat medium is provided, the second heat medium is supplied to the absorbent heater via the methanol heater and the second raw material heater.

8. The aromatic hydrocarbon production system according to claim 4, wherein the second heat recovery device has a second heat medium flow path through which a second heat medium that recovers heat energy of the second fluid by heat exchange with the second fluid flows, a water vapor heater configured in the water vapor supply line to heat water vapor by heat exchange with the second heat medium is provided, the second heat medium is supplied to the absorbent heater via the water vapor heater.

9. The aromatic hydrocarbon production system according to claim 8, wherein a second raw material heater configured in the raw material gas line to heat the raw material gas by heat exchange with the second heat medium is provided, the second heat medium is supplied to the absorbent heater via the water vapor heater and the second raw material heater.

10. A method for producing an aromatic hydrocarbon, comprising: supplying methanol to a xylene synthesis reactor filled with a catalyst for xylene synthesis; supplying water vapor to the xylene synthesis reactor; and synthesizing an aromatic hydrocarbon from methanol by a xylene synthesis reaction in the presence of water vapor with the xylene synthesis reactor.

11. The method for producing an aromatic hydrocarbon according to claim 10, comprising: supplying a raw material gas containing hydrogen and carbon dioxide to a methanol synthesis reactor; generating a first fluid containing methanol and water from the raw material gas by a methanol synthesis reaction with the methanol synthesis reactor; separating methanol and water from the first fluid; and supplying the methanol and water separated from the first fluid as methanol and water vapor to the xylene synthesis reactor.

12. The method for producing an aromatic hydrocarbon according to claim 10, comprising: supplying a raw material gas containing hydrogen and carbon dioxide to a methanol synthesis reactor; generating a first fluid containing methanol from the raw material gas by a methanol synthesis reaction with the methanol synthesis reactor; separating methanol from the first fluid; and supplying the methanol separated from the first fluid to the xylene synthesis reactor.

13. The method for producing an aromatic hydrocarbon according to claim 11 or 12, comprising: recovering heat energy from the first fluid; recovering heat energy from a second fluid containing an aromatic hydrocarbon generated by the xylene synthesis reaction with the xylene synthesis reactor; separating the aromatic hydrocarbon from the second fluid; and causing carbon dioxide to desorb from a carbon dioxide absorbent by heating the carbon dioxide absorbent with at least one of the heat energy recovered from the first fluid and the heat energy recovered from the second fluid, and using the desorbed carbon dioxide as a material of the raw material gas. ​ ​ ​ ​

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