Aerosol hydrocarbon production system and method

Abstract

This system for producing an aromatic hydrocarbon is provided with: a xylene synthesis reactor that is filled with a xylene synthesis catalyst and synthesizes an aromatic hydrocarbon from methanol by 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.

Description

Technical Field

[0001] The present disclosure relates to a system and method for producing aromatic hydrocarbons containing xylene using CO2 as a raw material.

Background Art

[0002] Para-xylene is an aromatic hydrocarbon and an important basic chemical used as a raw material for high-purity terephthalic acid, which is a raw material for polyester fibers and resins for PET bottles. Conventionally, para-xylene has been produced from fossil fuels. In recent years, as one of the "carbon recycling technologies" that capture and recover CO2 emitted from factories and the like as resources and aim to effectively utilize the recovered CO2, the industrial production of para-xylene using CO2 as a raw material has been proposed.

[0003] The process for industrially producing para-xylene using CO2 as a raw material 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 para-xylene separation step of separating para-xylene from xylene. Note that xylene has three xylene isomers, namely para-xylene, ortho-xylene, and meta-xylene, and in the para-xylene separation step, para-xylene is selectively separated from aromatic hydrocarbons containing xylene.

[0004] Conventionally, a technique for converting methanol into aromatic hydrocarbons by contacting methanol with a zeolite-based catalyst is known. For example, Patent Document 1 discloses a technique for synthesizing xylene from methanol using a zeolite-based catalyst.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the reaction of synthesizing xylene from methanol using a catalyst, the xylene synthesis reaction stops when the xylene synthesis catalyst becomes inactive. The longer the reaction time until the xylene synthesis catalyst becomes inactive, i.e., the longer the catalyst's lifespan, the lower the frequency and cost of maintenance such as catalyst replacement can be.

[0007] This disclosure has been made in view of the foregoing and aims to provide a technology that can extend the reaction time until deactivation of a xylene synthesis catalyst that promotes the synthesis of xylene from methanol, i.e., the lifespan of the catalyst, in a system and method for producing aromatic hydrocarbons. [Means for solving the problem]

[0008] As a result of diligent research, the inventors of this application have obtained a new finding: in the reaction of synthesizing xylene from methanol using a xylene synthesis catalyst, adding water vapor to methanol extends the time until the xylene synthesis catalyst is deactivated, i.e., the lifespan of the catalyst.

[0009] Therefore, the aromatic hydrocarbon production system according to one aspect of this disclosure is A xylene synthesis reactor is packed with a xylene synthesis catalyst and synthesizes aromatic hydrocarbons from methanol and water vapor through a xylene synthesis reaction. A methanol supply line for supplying methanol to the xylene synthesis reactor, The system is characterized by comprising a steam supply line for supplying steam to the xylene synthesis reactor.

[0010] Furthermore, a method for producing aromatic hydrocarbons according to one aspect of this disclosure is: To supply methanol to a xylene synthesis reactor packed with a xylene synthesis catalyst, To supply steam to the xylene synthesis reactor, and, The method includes synthesizing aromatic hydrocarbons from methanol and water vapor in the xylene synthesis reactor via a xylene synthesis reaction. [Effects of the Invention]

[0011] According to this disclosure, a technology is available that can extend the reaction time until the deactivation of a xylene synthesis catalyst, i.e., the lifespan of the catalyst, in a system and method for producing aromatic hydrocarbons. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a chart 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 materials is changed in a xylene synthesis reaction using a xylene synthesis catalyst. [Figure 2] Figure 2 is a block diagram showing the overall configuration of an aromatic hydrocarbon production system according to one embodiment of the present disclosure. [Figure 3] Figure 3 is a block diagram showing the overall configuration of the aromatic hydrocarbon production system according to Modification 1. [Modes for carrying out the invention]

[0013] The aromatic hydrocarbon production system described herein utilizes a reaction (hereinafter referred to as the "xylene synthesis reaction") in which methanol is converted into an aromatic hydrocarbon containing xylene by contacting methanol with a xylene synthesis catalyst. In the aromatic hydrocarbon production system described herein, aromatic hydrocarbons are produced while suppressing the deactivation rate of the catalyst by contacting methanol with a xylene synthesis catalyst in the presence of water vapor.

[0014] In a xylene synthesis reaction using a xylene synthesis catalyst, a test was conducted to confirm the relationship between the water vapor concentration in the raw materials and the lifespan of the xylene synthesis catalyst. In this test, a zeolite-based catalyst was used as the xylene synthesis catalyst. A mixture of 16 mol% methanol, α mol% water vapor, and (84-α) mol% nitrogen, heated to 400°C, was continuously supplied to a reaction vessel filled with the xylene synthesis catalyst. The amount of methanol contained in the exhaust from the reaction vessel was measured every hour. The methanol conversion rate [%] was determined from the measured values. The methanol conversion rate is expressed as a percentage of the total amount of methanol supplied that was converted to aromatic hydrocarbons. The water vapor concentration α was treated as a variable and varied from 0, 4, 8, and 16.

[0015] Figure 1 is 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 materials is changed in a xylene synthesis reaction using a xylene synthesis catalyst. In the graph of Figure 1, the vertical axis represents the methanol conversion rate [%], and the horizontal axis represents the reaction time of the xylene synthesis catalyst. When the water vapor concentration in the raw materials is 0 mol%, the methanol conversion rate is 100% up to 2 hours after the start of the reaction, but decreases to approximately 80% after 2 hours. When the water vapor concentration in the raw materials is 4 mol%, the methanol conversion rate is 100% up to 3 hours after the start of the reaction, but decreases to approximately 70% after 4 hours. When the water vapor concentration in the raw materials is 8 mol%, the methanol conversion rate is 100% up to 4 hours after the start of the reaction, but decreases to approximately 70% after 5 hours. When the water vapor concentration in the raw materials is 16 mol%, the methanol conversion rate is 100% up to 4 hours after the start of the reaction, but after 5 hours, the methanol conversion rate decreases to approximately 70%. From these results, it can be concluded that when the water vapor concentration in the raw materials is 0 mol%, the xylene synthesis catalyst is deactivated in 3 hours; when the water vapor concentration in the mixed gas is 4 mol%, the xylene synthesis catalyst is deactivated in 4 hours; and when the water vapor concentrations in the mixed gas are 8 and 16 mol%, the xylene synthesis catalyst is deactivated in 5 hours. Thus, it has become clear that by contacting methanol with the xylene synthesis catalyst in the presence of water vapor, aromatic hydrocarbons can be produced while suppressing the deactivation rate of the catalyst. Suppressing the deactivation rate of the catalyst extends the life of the catalyst. Furthermore, it was shown that when the methanol concentration in the raw materials contacted with the xylene synthesis catalyst is 16 mol%, if the water vapor concentration in the raw materials is 4 mol% or higher, i.e., if the water vapor concentration relative to the methanol concentration is 1 / 4 or higher, the effect of suppressing the deactivation rate of the catalyst can be obtained. Furthermore, it was shown that when the methanol concentration in the raw material contacted with the xylene synthesis catalyst is 16 mol%, and the water vapor concentration in the raw material is 8 mol% or higher, i.e., when the water vapor concentration is 1 / 2 or more of the methanol concentration, there is no change in the effect of suppressing the deactivation rate of the catalyst.

[0016] 《Configuration of the Aromatic Hydrocarbon Production System 100》 FIG. 2 is a block diagram showing the overall configuration of the aromatic hydrocarbon production system 100 according to the present disclosure. The aromatic hydrocarbon production system 100 according to the present disclosure is a process for industrially producing paraxylene using H2 (hydrogen) and CO2 (carbon dioxide) as raw materials, and includes (1) a methanol synthesis step of synthesizing methanol from CO2 and H2, and (2) a xylene synthesis step of synthesizing xylene from methanol, and produces aromatic hydrocarbons 97 containing xylene.

[0017] The aromatic hydrocarbon production 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 methanol synthesis by hydrogenation of CO2 is carried out. The methanol synthesis reactor 11 is filled with a methanol synthesis catalyst 110. The methanol synthesis catalyst 110 promotes a methanol synthesis reaction (CO2 + 3H2 → CH3OH + H2O) for generating methanol and steam from CO2 and H2. The methanol synthesis catalyst 110 is not particularly limited as long as it promotes the reaction of generating methanol from CO2. As such a methanol synthesis catalyst 110, a Cu-based catalyst (reaction temperature around 250 ° C., reaction pressure 3-5 MPa), a metal oxide catalyst, etc. are known.

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

[0020] Through the raw material gas line 21, a raw material gas 91 containing H2 and CO2 is supplied to the methanol synthesis reactor 11. The H2 in the raw material gas 91 is, for example, generated 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 in detail later.

[0021] A compressor 48 is provided in the raw material gas line 21. The compressor 48 increases the pressure of the raw material gas 91 to a pressure suitable for the methanol synthesis reaction. A raw material heater 31 is also provided in the raw material gas line 21. The raw material heater 31 raises the temperature of the raw material gas 91 to a temperature suitable for the methanol synthesis reaction. The reaction temperature and reaction pressure of the methanol synthesis reaction vary depending on the methanol synthesis catalyst 110. For example, if the methanol synthesis catalyst 110 is a Cu-based catalyst, the reaction temperature is around 250°C and the reaction pressure is 3-5 MPa.

[0022] The first product line 22 receives the first fluid 92 discharged from the methanol synthesis reactor 11. The first fluid 92 flowing into the first product line 22 contains methanol and water vapor, which are reaction products of the methanol synthesis reaction, as well as unreacted H2 and CO2.

[0023] A first heat recovery unit 32 is provided in the first product line 22. The first heat recovery unit 32 recovers the thermal energy of the first fluid 92. For example, the first heat recovery unit 32 has a first heat medium channel 360 through which a first heat medium 36 flows, recovering the thermal energy of the first fluid 92 by exchanging heat with it. In Figure 2, the movement of the first heat medium 36 is shown by a dashed line. The channel for the first heat medium 36 is formed by piping or the like. The first heat medium 36, which has recovered the thermal energy of the first fluid 92, exchanges heat with the raw material gas 91 in the raw material heater 31. That is, the thermal energy recovered from the first fluid 92 in the first heat recovery unit 32 is used to heat the raw material gas 91.

[0024] A first gas-liquid separator 41 is provided downstream of the first heat recovery unit 32 in the first product line 22. The first gas-liquid separator 41 separates and removes gaseous components such as water vapor from the first fluid 92 flowing through the first product line 22. The gaseous components separated from the first fluid 92 in the first gas-liquid separator 41 include unreacted H2 and CO2. A portion of the gaseous components separated from the first fluid 92 is returned to the raw material gas line 21 through the recycling line 28. The recycling line 28 is equipped with a compressor 49, which increases the pressure of the gaseous components returned from the first gas-liquid separator 41 to the raw material gas 91 to a pressure suitable for the methanol synthesis reaction.

[0025] Downstream of the first gas-liquid separator 41 in the first product line 22, a first fluid 92, which is a liquid containing a large amount of methanol, flows after the gaseous components have been separated. This liquid also contains water that has been liquefied from the water vapor contained in the first fluid 92. Downstream of the first gas-liquid separator 41 in the first product line 22, a pressure reducer 51 is provided. The pressure reducer 51 reduces the pressure of the first fluid 92.

[0026] A second gas-liquid separator 42 is provided downstream of the vacuum regulator 51 in the first product line 22. A portion of the first fluid 92, vaporized by the vacuum regulator 51, is separated from the first fluid 92 by the second gas-liquid separator 42. In this way, methanol 94 is separated from the first fluid 92 by the two-stage gas-liquid separators, the first gas-liquid separator 41 and the second gas-liquid separator 42, separating the gaseous and liquid components of the first fluid 92. This methanol 94 contains water that has been liquefied from water vapor. A methanol supply line 23 is connected to the second gas-liquid separator 42. The methanol 94 is supplied to the xylene synthesis reactor 12 through the methanol supply line 23. Note that the fluid flowing through the methanol supply line 23 may also contain water 99 (or water vapor 99a) in addition to methanol 94.

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

[0028] The xylene synthesis reactor 12 is a reaction vessel in which the xylene synthesis reaction takes place. The xylene synthesis reactor 12 is filled with a xylene synthesis catalyst 120. The xylene synthesis catalyst 120 promotes the synthesis reaction from methanol to aromatic hydrocarbons in the presence of water vapor. The type of xylene synthesis catalyst 120 is not particularly limited. For example, zeolite-based catalysts are known as xylene synthesis catalysts 120, and the reaction temperature is around 400-600°C.

[0029] Methanol 94 is supplied to the xylene synthesis reactor 12 through the methanol supply line 23. A methanol heater 33 is provided in the methanol supply line 23. The methanol heater 33 raises the methanol 94 to a temperature suitable for the xylene synthesis reaction. Alternatively, vaporized methanol 94 and water 99 may be supplied to the xylene synthesis reactor 12 through the methanol supply line 23. In this case, the methanol supply line 23 also functions as a water vapor supply line. The water 99 and methanol 94 that flow from the second gas-liquid separator 42 to the methanol supply line 23 are heated in the methanol heater 33 provided in the methanol supply line 23, and flow into the xylene synthesis reactor 12 as water vapor 99a and gaseous methanol 94.

[0030] Steam 95 is supplied to the xylene synthesis reactor 12 through the steam supply line 24. The steam 95 may be diluted with nitrogen to adjust the steam concentration in the xylene synthesis reactor 12. A pump 50 is provided in the steam supply line 24. The pump 50 increases the steam 95 to a pressure suitable for the xylene synthesis reaction and sends it to the xylene synthesis reactor 12. A steam heater 35 is also provided downstream of the pump 50 in the steam supply line 24. The steam heater 35 raises the steam 95 to a temperature suitable for the xylene synthesis reaction. If the methanol supply line 23 also functions as a steam supply line, as described above, the steam supply line 24 may be omitted.

[0031] When methanol 94 and water vapor 95,99a are supplied to the xylene synthesis reactor 12, the xylene synthesis reaction occurs through the action of the xylene synthesis catalyst 120. The reaction products of the xylene synthesis reactor 12 include lower hydrocarbons in addition to aromatic hydrocarbons. The aromatic hydrocarbons in the reaction products may include benzene, toluene, and three xylene isomers. The lower hydrocarbons in the reaction products may include C2-C4 alkenes such as ethylene and propylene, and C1-C5 alkanes such as methane, ethane, propane, and butane. However, the composition and proportion of aromatic hydrocarbons and lower hydrocarbons in the reaction products differ depending on the type of xylene synthesis catalyst 120.

[0032] The second fluid 96 discharged from the xylene synthesis reactor 12 flows into the second product line 26. The second fluid 96 flowing into the second product line 26 contains aromatic hydrocarbons, which are the reactive substances in the xylene synthesis reaction, as well as lower hydrocarbons and water vapor.

[0033] A second heat recovery unit 34 is provided in the second product line 26. The second heat recovery unit 34 recovers the thermal energy of the second fluid 96. For example, the second heat recovery unit 34 has a second heat medium channel 370 through which the second heat medium 37 flows, and the second heat medium 37 recovers the thermal energy of the second fluid 96 by exchanging heat with the second fluid 96. In Figure 2, the movement of the second heat medium 37 is shown by a dashed line. The channel for the second heat medium 37 is formed by piping, etc. The second heat medium 37, which has recovered the thermal energy of the second fluid 96, exchanges heat with methanol 94 in the methanol heater 33. That is, the thermal energy recovered from the second fluid 96 in the second heat recovery unit 34 is used to heat methanol 94. In addition, the second heat medium 37, which has recovered the thermal energy of the second fluid 96, exchanges heat with steam 95 in the steam heater 35. In other words, the thermal energy recovered from the second fluid 96 in the second heat recovery unit 34 is used to heat the steam 95.

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

[0035] The third gas-liquid separator 45 is connected to the product line 27. Aromatic hydrocarbons 97 separated from the second fluid 96 in the third gas-liquid separator 45 flow into the product line 27. The aromatic hydrocarbons 97 are sent through the product line 27 to the next paraxylene separation process. In the paraxylene separation process, paraxylene is separated from the aromatic hydrocarbons 97, and the paraxylene is used as a material for chemical products.

[0036] Composition of 46 carbon dioxide sources The carbon dioxide supply source 46 of the aromatic hydrocarbon production system 100 according to this disclosure comprises 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, releasing the CO2 absorbed by the carbon dioxide absorbent 43. The released CO2 is sent to the raw material gas line 21 and used as raw material gas 91. The carbon dioxide absorbent 43 that has released CO2 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 absorbent solution) is used. However, a solid carbon dioxide absorbent 43 (i.e., a carbon dioxide chemical absorbent material) may also be used. The solid carbon dioxide absorbent 43 is a porous support such as zeolite on which an amine compound that reversibly absorbs CO2 is supported. Typical amines used in carbon dioxide absorbents 43 include alkanolamines such as monoethanolamine and methyldiethanolamine, sterically hindered amines such as 2-amino-2-methyl-1-propanol, and cyclic amines such as piperazine. The CO2 absorption and release temperatures of the carbon dioxide absorbent 43 vary depending on the properties of the carbon dioxide absorbent 43 and the type of amine. For example, a carbon dioxide absorbent 43 that utilizes the neutralization reaction between an aqueous alkanolamine solution and CO2 absorbs CO2 at 40-50°C and releases CO2 at 110-130°C. The method for releasing CO2 from the carbon dioxide absorbent 43 is appropriate to the type of carbon dioxide absorbent 43. For example, CO2 can be released by indirectly heating a liquid carbon dioxide absorbent 43. Alternatively, CO2 can be released by indirectly heating a solid carbon dioxide absorbent 43 or by bringing the carbon dioxide absorbent 43 into contact with water vapor.

[0038] The composition of the carbon dioxide supply source 46 is not particularly limited, but can be exemplified as follows: (i) When a liquid carbon dioxide absorbent 43 is used, the carbon dioxide supply source 46 is provided with an absorption container and a release container containing the carbon dioxide absorbent 43, and an absorbent heater 53 that indirectly heats the carbon dioxide absorbent 43 in the release container. The absorption container and the release container are in communication with each other. A gas containing CO2 is supplied to the absorption container, and the CO2 is absorbed by the carbon dioxide absorbent 43. The carbon dioxide absorbent 43 that has absorbed CO2 moves to the release container. In the release container, the carbon dioxide absorbent 43 is heated, causing the carbon dioxide absorbent 43 to release CO2. The carbon dioxide absorbent 43 that has released CO2 moves to the absorption container. (ii) When a solid carbon dioxide absorbent 43 is used, the carbon dioxide supply source 46 has a series of reaction vessels through which the carbon dioxide absorbent 43 flows, and while some of the carbon dioxide absorbent 43 is used to absorb CO2, some of the remaining carbon dioxide absorbent 43 is heated by an absorbent heater 53 to release CO2. (iii) When a solid carbon dioxide absorbent 43 is used, the carbon dioxide source 46 has multiple reaction vessels filled with the carbon dioxide absorbent 43, and while some of the reaction vessels are used to absorb CO2, the remaining reaction vessels release CO2 by heating with an absorbent heater 53.

[0039] For the release of CO2 from the carbon dioxide absorbent 43, the thermal energy recovered from the first fluid 92, i.e., a portion of the heat generated during methanol synthesis, may be used. In this case, the first heat transfer medium 36, which has recovered the thermal energy of the first fluid 92 in the first heat recovery unit 32, exchanges heat with the raw material gas 91 via the raw material heater 31 to heat the raw material gas 91, and is then supplied to the absorbent heater 53 of the carbon dioxide supply source 46 to be used to heat the carbon dioxide absorbent 43.

[0040] Furthermore, the thermal energy recovered from the second fluid 96, i.e., a portion of the heat generated in the xylene synthesis reaction, may be used to release CO2 from the carbon dioxide absorbent 43. In this case, the second heat transfer medium 37, which has recovered the thermal energy of the second fluid 96 in the second heat recovery unit 34, exchanges heat with methanol 94 via the methanol heater 33 to heat the methanol 94, and is then supplied to the absorbent heater 53 of the carbon dioxide supply source 46 for heating the carbon dioxide absorbent 43. Alternatively, the second heat transfer medium 37, which has recovered the thermal energy of the second fluid 96 in the second heat recovery unit 34, exchanges heat with steam 95 via the steam heater 35 to heat the steam 95, and is then supplied to the absorbent heater 53 of the carbon dioxide supply source 46 for heating the carbon dioxide absorbent 43.

[0041] In the carbon dioxide supply source 46, at least one of the thermal energy recovered from the first fluid 92 and the thermal energy recovered from the second fluid 96 may be used to release CO2 from the carbon dioxide absorbent 43. However, in order to make more effective use of the thermal energy in the system, it is preferable that both the thermal energy recovered from the first fluid 92 and the thermal energy recovered from the second fluid 96 be used to release CO2 from the carbon dioxide absorbent 43.

[0042] The CO2 emission temperature of the carbon dioxide absorbent 43 is lower than the methanol synthesis reaction temperature, and the methanol synthesis reaction temperature is lower than the xylene synthesis reaction temperature. Furthermore, 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. Given these temperature relationships within the system, in order to make more effective use of the thermal energy within the system, the thermal energy of the second fluid 96 recovered in the second heat recovery unit 34 may be used to heat the raw material gas 91 and methanol 94 before being used to heat the carbon dioxide absorbent 43. Similarly, the thermal energy of the second fluid 96 recovered in the second heat recovery unit 34 may be used to heat the raw material gas 91 and steam 95 before being used to heat the carbon dioxide absorbent 43.

[0043] In the aromatic hydrocarbon production system 100 (100A) according to the modified example 1 shown in Figure 3, the raw material gas line 21 is provided with a first raw material heater 31 that exchanges heat between a first heat medium 36 and a raw material gas 91, and a second raw material heater 31 that exchanges heat between a second heat medium 37 and a raw material gas 91. The first heat medium 36, from which the thermal energy of the first fluid 92 has been recovered in the first heat recovery unit 32, exchanges heat with the raw material gas 91 via the first raw material heater 31 to heat the raw material gas 91, and is then supplied to the absorbent heater 53 and used to heat the carbon dioxide absorbent 43. The second heat transfer medium 37, which has recovered the thermal energy of the second fluid 96 in the second heat recovery unit 34, first heats the methanol 94 by exchanging heat with methanol 94 via the methanol heater 33, then heats the raw material gas 91 by exchanging heat with raw material gas 91 via the second raw material heater 31, and finally is supplied to the absorbent heater 53 of the carbon dioxide supply source 46 and used to heat the carbon dioxide absorbent 43. In addition, the aromatic hydrocarbon production system 100A according to Modification 1 differs from the aromatic hydrocarbon production system 100 according to the above embodiment in that the flow of the second heat transfer medium 37 is different, but the other components are substantially the same.

[0044] [Summary] The production system 100 for aromatic hydrocarbons 97 relating to the first item of this disclosure is A xylene synthesis reactor 12 is filled with a xylene synthesis catalyst 120 and synthesizes aromatic hydrocarbons 97 from methanol 94 by a xylene synthesis reaction in the presence of water vapor 95,99a, A methanol supply line 23 supplies methanol 94 to the xylene synthesis reactor 12, The system includes steam supply lines 23 and 24 that supply steam 99a and 95 to the xylene synthesis reactor 12. Here, in the xylene synthesis reactor 12, the concentration of water vapor 99a,95 in the gas in contact with the xylene synthesis catalyst 120 is preferably 1 / 4 or more of the concentration of methanol 94. The concentration ratio of methanol 94 to water vapor 99a,95 in the gas in contact with the xylene synthesis catalyst 120 may be about 1:1. Furthermore, water can be added as a diluent to suppress the exothermic reaction. In this case, the concentration of water vapor 99a,95 in the gas in contact with the xylene synthesis catalyst 120 is preferably higher than the concentration of methanol 94. For example, the volume ratio of water vapor 99a,95 to methanol 94 in the gas in contact with the xylene synthesis catalyst 120 may be about 9:1. In an extreme example, the volume ratio of water vapor 99a,95 to methanol 94 in the gas in contact with the xylene synthesis catalyst 120 may be about 99:1.

[0045] In the xylene synthesis reactor 12 of the manufacturing system 100 with the above configuration, methanol 94 is converted to aromatic hydrocarbons 97 by the xylene synthesis catalyst 120 in the presence of water vapor 99a and 95. It has been found that by contacting methanol 94 with the xylene synthesis catalyst 120 in the presence of water vapor 99a and 95, aromatic hydrocarbons 97 can be produced while suppressing the deactivation rate of the catalyst 120. Thus, in the aromatic hydrocarbon manufacturing system 100, the lifespan of the xylene synthesis catalyst 120 can be extended by suppressing the deactivation rate of the xylene synthesis catalyst 120, and the frequency of replacement of the xylene synthesis catalyst 120 can be reduced.

[0046] The production system 100 for aromatic hydrocarbons 97 relating to item 2 of this disclosure is, in the production system 100 for aromatic hydrocarbons 97 relating to item 1, A methanol synthesis reactor 11 synthesizes methanol 94 from a raw material gas 91 containing hydrogen and carbon dioxide through a methanol synthesis reaction, accompanied by the generation of water vapor. A raw material gas line 21 that supplies raw material gas 91 to the methanol synthesis reactor 11, The system includes gas-liquid separators 41 and 42 for separating methanol 94 and water 99 from the first fluid 92 discharged from the methanol synthesis reactor 11 containing the reaction products of the methanol synthesis reaction. The methanol supply line 23 supplies methanol 94 and water 99, separated from the first fluid 92 in the gas-liquid separator 44, to the xylene synthesis reactor 12 as methanol 94 and water vapor 99a, and the methanol supply line 23 also serves as a water vapor supply line.

[0047] In the manufacturing system 100 with the above configuration, the water produced in the methanol synthesis reaction can be effectively utilized in the xylene synthesis reaction.

[0048] The production system 100 for aromatic hydrocarbons 97 relating to item 3 of this disclosure is, in the production system 100 for aromatic hydrocarbons 97 relating to item 1, A methanol synthesis reactor 11 that synthesizes methanol 94 from a raw material gas 91 containing hydrogen and carbon dioxide by a methanol synthesis reaction, A raw material gas line 21 that supplies raw material gas 91 to the methanol synthesis reactor 11, Gas-liquid separators 41 and 42 separate methanol 94 from the first fluid 92 discharged from the methanol synthesis reactor 11 containing the reaction products of the methanol synthesis reaction, The system includes a methanol supply line 23 that supplies methanol 94, separated from the first fluid 92 by gas-liquid separators 41 and 42, to the xylene synthesis reactor 12.

[0049] In the aromatic hydrocarbon 97 production system 100 relating to the second and third items, the reaction to produce aromatic hydrocarbon 97 from CO2 and H2 is carried out in two stages: a methanol synthesis reaction carried out in the methanol synthesis reactor 11 and a xylene synthesis reaction carried out in the xylene synthesis reactor 12. This makes it possible to provide optimal reaction conditions for each of the methanol synthesis and xylene synthesis reactions. In addition, unreacted CO2 and H2 can be separated at a stage before by-products such as aliphatic hydrocarbons 98 are mixed in during the xylene synthesis reaction and returned to the methanol synthesis reactor 11, and the aliphatic hydrocarbons 98 can be recovered as a valuable material in a later stage.

[0050] The production system 100 for aromatic hydrocarbons 97 relating to item 4 of this disclosure is, in the production system 100 for aromatic hydrocarbons 97 relating to item 2 or 3, A first heat recovery unit 32 recovers thermal energy from the first fluid 92, A second heat recovery unit 34 recovers thermal energy from a second fluid 96 discharged from a xylene synthesis reactor 12 containing the reaction products of the xylene synthesis reaction, The system comprises a carbon dioxide absorbent 43 that reversibly absorbs carbon dioxide, an absorbent heater 53 that heats the carbon dioxide absorbent 43 with at least one of the thermal energy recovered from the first fluid 92 and the thermal energy recovered from the second fluid 96, and a carbon dioxide supply source 46 that supplies the carbon dioxide released from the carbon dioxide absorbent 43 by heating to the raw gas line 21.

[0051] In conventional aromatic hydrocarbon production systems, when CO2 absorbed by a carbon dioxide absorbent is used as a raw material, a major challenge is the high cost due to the need to procure the raw material gas, particularly the significant energy supply required from outside the system to release the CO2 from the carbon dioxide absorbent. In contrast, in the aromatic hydrocarbon 97 production system 100 according to this disclosure, the heat generated in the aromatic hydrocarbon 97 production process is effectively utilized to supply CO2 contained in the raw material gas 91, that is, for the procurement of the raw material gas 91. Therefore, the energy supplied from outside the system for the procurement of the raw material gas 91 can be reduced, and the cost of procuring the raw material gas 91 can be reduced. In addition, energy is recycled within the system, resulting in less energy loss and consequently suppressing CO2 emissions.

[0052] The production system 100 for aromatic hydrocarbons 97 relating to item 5 of this disclosure is, in the production system 100 for aromatic hydrocarbons 97 relating to item 4, The first heat recovery unit 32 has a first heat medium channel 360 through which a first heat medium 36 flows, which recovers the thermal energy of the first fluid 92 by exchanging heat with the first fluid 92. The system includes a raw material heater 31 that heats the raw material gas 91 by exchanging heat with a first heat transfer medium 36, and the first heat transfer medium 36 is supplied to the absorbent heater 53 via the first raw material heater 31.

[0053] In the manufacturing system 100 with the above configuration, the thermal energy recovered from the first fluid 92 is used to heat the raw material gas 91, and then used to heat the carbon dioxide absorbent 43. The CO2 release temperature from the carbon dioxide absorbent 43 is sufficiently lower than the temperature of the raw material gas 91, which is suitable for the methanol synthesis reaction. Therefore, even the thermal energy remaining after being used to heat the raw material gas 91 can be used for CO2 release, and the thermal energy of the first fluid 92 can be effectively utilized.

[0054] The production system 100 for aromatic hydrocarbons 97 relating to item 6 of this disclosure is, in the production system 100 for aromatic hydrocarbons 97 relating to item 4 or 5, The second heat recovery unit 34 has a second heat medium channel 370 through which a second heat medium 37 flows, which recovers the thermal energy of the second fluid 96 by exchanging heat with the second fluid 96. The methanol supply line 23 is equipped with a methanol heater 33 that heats methanol 94 by exchanging heat with a second heat transfer medium 37. The second heat transfer medium 37 is supplied to the absorbent heater 53 via the methanol heater 33.

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

[0056] The production system 100 for aromatic hydrocarbons 97 relating to item 7 of this disclosure is, in the production system 100 for aromatic hydrocarbons 97 relating to item 6, The system includes a second raw material heater 31 located in the raw material gas line 21, which heats the raw material gas 91 by exchanging heat with a second heat transfer medium 37. The second heat transfer medium 37 is supplied to the absorbent heater 53 via the methanol heater 33 and the raw material heater 31.

[0057] In the manufacturing system 100 with the above configuration, the thermal energy recovered from the second fluid 96 is used to heat the methanol 94 and the raw material gas 91, and then used to heat the carbon dioxide absorbent 43. The CO2 release temperature from the carbon dioxide absorbent 43 is sufficiently lower than the temperature of the raw material gas 91, which is suitable for the methanol synthesis reaction. Therefore, even the thermal energy remaining after being used to heat the methanol 94 and the raw material gas 91 can be used for CO2 release, and the thermal energy of the second fluid 96 can be effectively utilized.

[0058] The production system 100 for aromatic hydrocarbons 97 relating to item 8 of this disclosure is, in the production system 100 for aromatic hydrocarbons 97 relating to any of items 4 to 7, The second heat recovery unit 34 has a second heat medium channel 370 through which a second heat medium 37 flows, which recovers the thermal energy of the second fluid 96 by exchanging heat with the second fluid 96. The steam supply line 24 is equipped with a steam heater 35 that heats the steam 95 by exchanging heat with a second heat transfer medium 37. The second heat transfer medium 37 is supplied to the absorbent heater 53 via the steam heater 35.

[0059] In the manufacturing system 100 described above, the energy recovered from the second fluid 96 is used to heat the steam 95, and then to heat the carbon dioxide absorbent 43. The CO2 release temperature from the carbon dioxide absorbent 43 is sufficiently lower than the temperature of the steam 95, which is suitable for the xylene synthesis reaction. Therefore, even the thermal energy remaining after being used to heat the steam 95 can be used for CO2 release, and the thermal energy of the second fluid 96 can be effectively utilized.

[0060] The production system 100 for aromatic hydrocarbons 97 relating to item 9 of this disclosure is, in the production system 100 for aromatic hydrocarbons 97 relating to item 8, The system includes a second raw material heater 31 located in the raw material gas line 21, which heats the raw material gas 91 by exchanging heat with a second heat transfer medium 37. The second heat transfer medium 37 is supplied to the absorbent heater 53 via the steam 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 to heat the steam 95 and the raw material gas 91, and then used to heat the carbon dioxide absorbent 43. The CO2 release temperature from the carbon dioxide absorbent 43 is sufficiently lower than the temperature of the raw material gas 91, which is suitable for the methanol synthesis reaction. Therefore, even the thermal energy remaining after being used to heat the steam 95 and the raw material gas 91 can be used for CO2 release, and the thermal energy of the second fluid 96 can be effectively utilized.

[0062] The method for producing aromatic hydrocarbons 97 relating to item 10 of this disclosure is: To supply methanol 94 to a xylene synthesis reactor 12 filled with xylene synthesis catalyst 120, To supply steam 95,99a to the xylene synthesis reactor 12, and, The method includes synthesizing aromatic hydrocarbons 97 from methanol 94 in the presence of water vapor 95 and 99a in a xylene synthesis reactor 12 via a xylene synthesis reaction.

[0063] In the above method for producing aromatic hydrocarbons 97, methanol 94 is converted to aromatic hydrocarbons 97 by the xylene synthesis catalyst 120 in the presence of water vapor 99a and 95. It has been found that by contacting methanol 94 with the xylene synthesis catalyst 120 in the presence of water vapor 99a and 95, aromatic hydrocarbons 97 can be produced while suppressing the deactivation rate of the catalyst 120. By suppressing the deactivation rate of the xylene synthesis catalyst 120, the lifespan 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 method for producing aromatic hydrocarbons 97 relating to item 11 of this disclosure is the method for producing aromatic hydrocarbons 97 relating to item 10, The raw material gas 91 containing hydrogen and carbon dioxide is supplied to the methanol synthesis reactor 11. In the methanol synthesis reactor 11, a methanol synthesis reaction is carried out to produce a first fluid 92 containing methanol 94 and water 99 from the raw material gas 91. To separate methanol 94 and water 99 from the first fluid 92, The method includes supplying methanol 94 and water 99 separated from the first fluid 92 to the xylene synthesis reactor 12 as methanol 94 and water vapor 99a.

[0065] The above manufacturing method allows for the effective use of water produced in the methanol synthesis reaction in the xylene synthesis reaction.

[0066] The method for producing aromatic hydrocarbons 97 relating to item 12 of this disclosure is the method for producing aromatic hydrocarbons 97 relating to item 10, The raw material gas 91 containing hydrogen and carbon dioxide is supplied to the methanol synthesis reactor 11. In the methanol synthesis reactor 11, a first fluid 92 containing methanol 94 is produced from the raw material gas 91 by a methanol synthesis reaction. To separate methanol 94 from the first fluid 92, This includes supplying methanol 94 separated from the first fluid 92 to the xylene synthesis reactor 12.

[0067] In the method for producing aromatic hydrocarbons 97 related to items 11 and 12, the reaction to produce aromatic hydrocarbons 97 from CO2 and H2 is carried out in two stages: a methanol synthesis reaction carried out in a methanol synthesis reactor 11 and a xylene synthesis reaction carried out in a xylene synthesis reactor 12. This makes it possible to provide suitable reaction conditions for each of the methanol synthesis and xylene synthesis reactions. In addition, unreacted CO2 and H2 can be separated at a stage before by-products such as aliphatic hydrocarbons 98 are mixed in during the xylene synthesis reaction and returned to the methanol synthesis reactor 11, and the aliphatic hydrocarbons 98 can be recovered as a valuable material in a later stage.

[0068] The method for producing aromatic hydrocarbons 97 relating to item 13 of this disclosure is, in the method for producing aromatic hydrocarbons 97 relating to item 11 or 12, To recover thermal energy from the first fluid 92, To recover thermal energy from the second fluid 96 containing aromatic hydrocarbons 97 produced by the xylene synthesis reaction in the xylene synthesis reactor 12. To separate aromatic hydrocarbons 97 from the second fluid 96, and The method includes heating the carbon dioxide absorbent 43 with thermal energy recovered from the first fluid 92 and thermal energy recovered from the second fluid 96 to release carbon dioxide from the carbon dioxide absorbent 43, and using the released carbon dioxide as a material for the raw material gas 91.

[0069] In the above method for producing aromatic hydrocarbons 97, the heat generated during the production process of aromatic hydrocarbons 97 is effectively utilized to supply CO2 contained in the raw material gas 91, that is, for the procurement of the raw material gas 91. Therefore, the energy supplied from outside the system for the procurement of the raw material gas 91 can be reduced, and the cost associated with procuring the raw material gas 91 can be reduced. In addition, energy is recycled within the system, resulting in less energy loss and consequently suppressing CO2 emissions.

[0070] The discussions of this disclosure described above are presented for illustrative and explanatory purposes only and are not intended to limit the disclosure to the forms disclosed herein. For example, in the detailed description above, various features of the disclosure are grouped into several embodiments for the purpose of streamlining the disclosure, but some of the features may be combined. Furthermore, some of the features included in this disclosure may be combined into alternative embodiments, configurations, or aspects other than those discussed above. [Explanation of Symbols]

[0071] 11: Methanol synthesis reactor 12: Xylene synthesis reactor 21: Raw material gas line 23: Methanol supply line 24: Steam supply line 31: Raw material heater 32: First heat recovery unit 33: Methanol heater 34: Second heat recovery unit 35: Steam heater 36: 1st heat medium 37:Second heat medium 41: 1st gas-liquid separator 42:Second gas-liquid separator 43: Carbon dioxide absorbent 46: Sources of carbon dioxide 53: Absorbent Heater 91: Raw material gas 92: 1st fluid 94: Methanol 95: Water vapor 96:Second fluid 97: Aromatic hydrocarbons 360: First heat transfer fluid channel 370: Second heat transfer fluid channel 100: Aromatic hydrocarbon production system 120: Catalyst for xylene synthesis

Claims

1. A methanol synthesis reactor that synthesizes methanol from a raw material gas containing hydrogen and carbon dioxide by a methanol synthesis reaction, accompanied by the generation of water vapor, A raw material gas line that supplies the raw material gas to the methanol synthesis reactor, A gas-liquid separator for separating methanol and water from a first fluid discharged from the methanol synthesis reactor containing the reaction products of the methanol synthesis reaction, A xylene synthesis reactor, filled with a xylene synthesis catalyst, synthesizes aromatic hydrocarbons from methanol via a xylene synthesis reaction in the presence of water vapor, A methanol supply line for supplying methanol separated from the first fluid in the gas-liquid separator to the xylene synthesis reactor, A steam supply line for supplying steam separated from the first fluid in the gas-liquid separator to the xylene synthesis reactor, wherein the steam supply line is also used as the methanol supply line, A first heat recovery unit for recovering thermal energy from the first fluid, A second heat recovery unit recovers thermal energy from a second fluid discharged from the xylene synthesis reactor containing the reaction products of the xylene synthesis reaction, The system comprises a carbon dioxide absorbent that reversibly absorbs carbon dioxide, and an absorbent heater that heats the carbon dioxide absorbent using at least one of the thermal energy recovered from the first fluid and the thermal energy recovered from the second fluid, and a carbon dioxide supply source that supplies the carbon dioxide released from the carbon dioxide absorbent by heating to the raw material gas line. A system for producing aromatic hydrocarbons.

2. A methanol synthesis reactor that synthesizes methanol from a raw material gas containing hydrogen and carbon dioxide by a methanol synthesis reaction, accompanied by the generation of water vapor, A raw material gas line that supplies the raw material gas to the methanol synthesis reactor, A gas-liquid separator for separating methanol and water from a first fluid discharged from the methanol synthesis reactor containing the reaction products of the methanol synthesis reaction, A xylene synthesis reactor, filled with a xylene synthesis catalyst, synthesizes aromatic hydrocarbons from methanol via a xylene synthesis reaction in the presence of water vapor, A methanol supply line for supplying methanol separated from the first fluid in the gas-liquid separator to the xylene synthesis reactor, A steam supply line for supplying steam to the xylene synthesis reactor, A first heat recovery unit for recovering thermal energy from the first fluid, A second heat recovery unit recovers thermal energy from a second fluid discharged from the xylene synthesis reactor containing the reaction products of the xylene synthesis reaction, The system comprises a carbon dioxide absorbent that reversibly absorbs carbon dioxide, and an absorbent heater that heats the carbon dioxide absorbent using at least one of the thermal energy recovered from the first fluid and the thermal energy recovered from the second fluid, and a carbon dioxide supply source that supplies the carbon dioxide released from the carbon dioxide absorbent by heating to the raw material gas line. A system for producing aromatic hydrocarbons.

3. The first heat recovery unit has a first heat medium channel through which a first heat medium flows, which recovers the thermal energy of the first fluid by exchanging heat with the first fluid. The system includes a first raw material heater that heats the raw material gas by exchanging heat with the first heat transfer medium, The first heat transfer medium is supplied to the absorbent heater via the first raw material heater. A system for producing aromatic hydrocarbons according to claim 1 or 2.

4. The second heat recovery unit has a second heat medium channel through which a second heat medium flows, which recovers the thermal energy of the second fluid by exchanging heat with the second fluid. The methanol supply line is equipped with a methanol heater that heats methanol by exchanging heat with the second heat transfer medium, The second heat transfer medium is supplied to the absorbent heater via the methanol heater. A system for producing aromatic hydrocarbons according to claim 1 or 2.

5. The raw material gas line is equipped with a second raw material heater that heats the raw material gas by exchanging heat with the second heat transfer medium, The second heat transfer medium is supplied to the absorbent heater via the methanol heater and the second raw material heater. A system for producing aromatic hydrocarbons according to claim 4.

6. The second heat recovery unit has a second heat medium channel through which a second heat medium flows, which recovers the thermal energy of the second fluid by exchanging heat with the second fluid. The steam supply line is equipped with a steam heater that heats the steam by exchanging heat with the second heat transfer medium, The second heat transfer medium is supplied to the absorbent heater via the steam heater. A system for producing aromatic hydrocarbons according to claim 1 or 2.

7. The raw material gas line is equipped with a second raw material heater that heats the raw material gas by exchanging heat with the second heat transfer medium, The second heat transfer medium is supplied to the absorbent heater via the steam heater and the second raw material heater. A system for producing aromatic hydrocarbons according to claim 6.

8. A raw material gas containing hydrogen and carbon dioxide is supplied to a methanol synthesis reactor. In the methanol synthesis reactor, a first fluid containing methanol and water is produced from the raw material gas by a methanol synthesis reaction. To separate methanol and water from the first fluid, The methanol and water separated from the first fluid are supplied as methanol and water vapor to a xylene synthesis reactor filled with a xylene synthesis catalyst. To supply steam to the xylene synthesis reactor, The aforementioned xylene synthesis reactor is used to synthesize aromatic hydrocarbons from methanol in the presence of water vapor via a xylene synthesis reaction. To recover thermal energy from the first fluid, To recover thermal energy from a second fluid containing aromatic hydrocarbons produced by the xylene synthesis reaction in the xylene synthesis reactor, Separating aromatic hydrocarbons from the second fluid, and This includes heating the carbon dioxide absorbent with thermal energy recovered from the first fluid and thermal energy recovered from the second fluid to release carbon dioxide from the carbon dioxide absorbent, and using the released carbon dioxide as a material for the raw material gas. A method for producing aromatic hydrocarbons.

9. A raw material gas containing hydrogen and carbon dioxide is supplied to a methanol synthesis reactor. In the methanol synthesis reactor, a first fluid containing methanol is produced from the raw material gas by a methanol synthesis reaction. To separate methanol from the first fluid, The methanol separated from the first fluid is supplied to a xylene synthesis reactor packed with a xylene synthesis catalyst. To supply steam to the xylene synthesis reactor, and, The aforementioned xylene synthesis reactor is used to synthesize aromatic hydrocarbons from methanol in the presence of water vapor via a xylene synthesis reaction. To recover thermal energy from the first fluid, To recover thermal energy from a second fluid containing aromatic hydrocarbons produced by the xylene synthesis reaction in the xylene synthesis reactor, Separating aromatic hydrocarbons from the second fluid, and This includes heating the carbon dioxide absorbent with thermal energy recovered from the first fluid and thermal energy recovered from the second fluid to release carbon dioxide from the carbon dioxide absorbent, and using the released carbon dioxide as a material for the raw material gas. A method for producing aromatic hydrocarbons.

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