Method for producing useful hydrocarbons and apparatus for producing useful hydrocarbons

Abstract

To provide a method for producing a useful hydrocarbon by which the useful hydrocarbon can efficiently be produced over a long period by using a methane-containing hydrocarbon and carbon dioxide which are easily obtained raw materials, and to provide an apparatus for producing the useful hydrocarbon.SOLUTION: A method for producing a useful hydrocarbon includes a dry reforming step of producing a first gas containing carbon monoxide and hydrogen from a mixed gas containing a methane-containing hydrocarbon and carbon dioxide, a useful hydrocarbon producing step of producing a second gas containing a useful hydrocarbon from carbon monoxide and hydrogen in the first gas, and a recycling step of separating a carbon dioxide-containing gas from the second gas and supplying the carbon dioxide-containing gas to the dry reforming step.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing useful hydrocarbons and an apparatus for producing useful hydrocarbons. [Background technology]

[0002] Useful hydrocarbons, such as various lower olefins and aromatic hydrocarbons that serve as basic chemical raw materials, and various liquid fuels (gasoline, liquefied petroleum gas (LPG), aviation fuel, etc.), are hydrocarbons with two or more carbon atoms and are mainly produced from petroleum resources. However, the production process of these hydrocarbons is primarily based on petroleum resources, raising concerns about geopolitical risks. Furthermore, the production and consumption processes of these hydrocarbons emit large amounts of carbon dioxide, which is considered problematic from the perspective of global warming. Therefore, efforts are being made to develop clean processes that use resources that are not limited to specific geographic locations as raw materials and that emit less carbon dioxide.

[0003] For example, liquefied petroleum gas emits less carbon dioxide, one of the causes of global warming, than crude oil or gasoline, and research into curbing global warming is being actively conducted. Patent Document 1 describes a method for producing liquefied petroleum gas, which includes a synthesis gas production process for producing synthesis gas from a carbon-containing raw material and at least one selected from the group consisting of water, oxygen, and carbon dioxide, a light paraffin production process for producing a light paraffin-containing gas containing low-boiling-point components from the synthesis gas, a separation process for separating the low-boiling-point components from the low-paraffin-containing gas, and a recycling process for recycling the low-boiling-point components to the synthesis gas production process. However, Patent Document 1 uses natural resources such as natural gas, naphtha, and coal as the carbon-containing raw material used to produce liquefied petroleum gas.

[0004] In recent years, other renewable energy sources such as biogas power generation, which uses organic waste such as livestock manure and sewage sludge, and solar power generation have been attracting attention. However, these technologies produce electricity as the energy source, which makes energy transportation difficult depending on the current power transmission capacity. Furthermore, biogas power generation utilizes only methane gas, which is one of the two gases obtained from organic waste, carbon dioxide. Therefore, the current situation in which carbon dioxide is not utilized is undesirable from the perspective of global warming.

[0005] As such, natural resources are not inexhaustible and can only be produced in certain countries or regions. Furthermore, even in the case of renewable energy, energy forms other than electricity are required from the perspective of energy storage and transportation. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-143752 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present disclosure is to provide a method and an apparatus for producing useful hydrocarbons that can efficiently produce useful hydrocarbons over a long period of time using methane-containing hydrocarbons and carbon dioxide, which are easily obtained raw materials. [Means for solving the problem]

[0008] [1] A method for producing useful hydrocarbons, comprising: a dry reforming step of producing a first gas containing carbon monoxide and hydrogen from a mixed gas containing methane-containing hydrocarbons and carbon dioxide; a useful hydrocarbon production step of producing a second gas containing useful hydrocarbons from the carbon monoxide and hydrogen in the first gas; and a recycling step of separating a carbon dioxide-containing gas from the second gas and supplying it to the dry reforming step. [2] The recycling step is performed by adjusting the total number of carbon moles M of carbon dioxide in the mixed gas and the carbon dioxide in the carbon dioxide-containing gas supplied to the dry reforming step. CO2 the total number of carbon moles M of hydrocarbons fed to the dry reforming step HC The ratio (M HC / M CO2 The method for producing useful hydrocarbons according to the above-mentioned [1], wherein the amount of the carbon dioxide-containing gas to be supplied to the dry reforming step is adjusted depending on the amount of the carbon dioxide-containing gas. [3] The method for producing useful hydrocarbons according to [1] or [2] above, wherein the carbon dioxide-containing gas has a CO2 concentration of 50% or more. [4] The method for producing useful hydrocarbons according to any one of the above [1] to [3], further comprising a hydrogen supply step of separating hydrogen from the second gas and supplying the hydrogen to the useful hydrocarbon production step. [5] The hydrogen supply step is performed by supplying hydrogen to the useful hydrocarbon production step using a mole number M H The method for producing useful hydrocarbons according to the above [4], wherein the amount of hydrogen supplied to the useful hydrocarbon production step is adjusted depending on the amount of hydrogen. [6] The number of moles M of carbon monoxide contained in the first gas obtained in the dry reforming step CO the number of moles of hydrogen M H Molar ratio (M H / M CO The method for producing useful hydrocarbons according to any one of the above [1] to [5], further comprising an adjusting step of adjusting the hydroxyl group of the hydrocarbons. [7] The method for producing useful hydrocarbons according to any one of the above [1] to [6], further comprising a combustion step of separating a substance containing carbon atoms from the second gas and combusting the substance containing carbon atoms to produce carbon dioxide, wherein the recycling step supplies the carbon dioxide-containing gas and the carbon dioxide produced in the combustion step to the dry reforming step. [8] The method for producing useful hydrocarbons according to any one of [1] to [7] above, wherein the useful hydrocarbons are at least one hydrocarbon selected from the group consisting of olefins, aromatic hydrocarbons, gasoline, liquefied petroleum gas, and liquid hydrocarbons. [9] The method for producing useful hydrocarbons according to any one of the above [1] to [8], wherein the useful hydrocarbons are liquefied petroleum gases.

[10] The method for producing useful hydrocarbons according to any one of [1] to [8] above, wherein the useful hydrocarbons are liquefied petroleum gases, and the carbon dioxide-containing gas contains hydrocarbons other than those with carbon numbers of 3 to 4.

[11] The method for producing useful hydrocarbons according to any one of the above [1] to [8], wherein the useful hydrocarbons are olefins, and the carbon dioxide-containing gas contains at least one of hydrocarbons other than the target olefins and carbon monoxide.

[12] The method for producing useful hydrocarbons according to any one of the above [1] to [8], wherein the useful hydrocarbons are aromatic hydrocarbons, and the carbon dioxide-containing gas contains at least one of hydrocarbons other than the target aromatic hydrocarbons and carbon monoxide.

[13] The method for producing useful hydrocarbons according to any one of [1] to [8] above, wherein the useful hydrocarbons are gasoline, and the carbon dioxide-containing gas contains at least one of hydrocarbons other than gasoline and carbon monoxide.

[14] The method for producing useful hydrocarbons according to any one of the above [1] to [8], wherein the useful hydrocarbons are liquid hydrocarbons, and the carbon dioxide-containing gas contains at least one of hydrocarbons having 4 or less carbon atoms and carbon monoxide.

[15] An apparatus for producing useful hydrocarbons, comprising: a dry reforming section that produces a first gas containing carbon monoxide and hydrogen from a mixed gas containing methane-containing hydrocarbons and carbon dioxide; a useful hydrocarbon production section that receives the first gas produced in the dry reforming section and produces a second gas containing useful hydrocarbons from the carbon monoxide and hydrogen in the first gas; and a recycling section that separates a carbon dioxide-containing gas from the second gas produced in the useful hydrocarbon production section and supplies the carbon dioxide-containing gas to the dry reforming section.

[16] A method for producing useful hydrocarbons, comprising: a dry reforming step of producing a first gas containing carbon monoxide and hydrogen from a gas having a methane / carbon dioxide ratio of 1 to 9 in moles; a useful hydrocarbon production step of producing a second gas containing useful hydrocarbons from the carbon monoxide and hydrogen in the first gas; and a recycling step of separating a carbon dioxide-containing gas from the second gas and supplying it to the dry reforming step. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a method and an apparatus for producing useful hydrocarbons that can efficiently produce useful hydrocarbons over a long period of time using methane-containing hydrocarbons and carbon dioxide, which are easily obtained raw materials. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing an example of a method for producing useful hydrocarbons according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing an example of an apparatus for producing useful hydrocarbons according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, the embodiments will be described in detail with reference to the drawings.

[0012] The present inventors focused on dry reforming, which can produce carbon monoxide and hydrogen from easily obtained methane-containing hydrocarbons and carbon dioxide, as well as from methane-containing hydrocarbons and carbon dioxide. Dry reforming produces carbon monoxide and hydrogen (synthesis gas) from methane-containing hydrocarbons and carbon dioxide in equal ratios (carbon basis). However, dry reforming under conditions where the amount of methane-containing hydrocarbons is greater than a predetermined amount (i.e., conditions where there is a shortage of carbon dioxide) can cause significant deterioration (coking) of the catalyst used in the reaction, requiring catalyst replacement in a short period of time. In the worst case, there are concerns that this can lead to a loss of efficiency and safety, such as blockage of the reactor.

[0013] Furthermore, the present inventors have noticed that when a gas containing useful hydrocarbons (second gas) is produced from carbon monoxide and hydrogen in a useful hydrocarbon production step performed after the dry reforming step, the second gas contains carbon dioxide, which is an unreacted substance or by-product in the dry reforming step and the useful hydrocarbon production step.The present inventors have then found that by supplying carbon dioxide, an impurity contained in the second gas, to the dry reforming step and reusing it, it is possible to suppress catalyst deterioration reactions during the dry reforming step and to efficiently produce useful hydrocarbons over a long period of time.The present disclosure is based on this finding.

[0014] The method for producing useful hydrocarbons of the embodiment includes a dry reforming step of producing a first gas containing carbon monoxide and hydrogen from a mixed gas containing methane-containing hydrocarbons and carbon dioxide, a useful hydrocarbon production step of producing a second gas containing useful hydrocarbons from the carbon monoxide and hydrogen in the first gas, and a recycling step of separating a carbon dioxide-containing gas from the second gas and supplying it to the dry reforming step.

[0015] The apparatus for producing useful hydrocarbons of the embodiment includes a dry reforming section that produces a first gas containing carbon monoxide and hydrogen from a mixed gas containing methane-containing hydrocarbons and carbon dioxide, a useful hydrocarbon production section that receives the first gas produced in the dry reforming section and produces a second gas containing useful hydrocarbons from the carbon monoxide and hydrogen in the first gas, and a recycle section that separates a carbon dioxide-containing gas from the second gas produced in the useful hydrocarbon production section and supplies the carbon dioxide-containing gas to the dry reforming section.

[0016] [Method of producing useful hydrocarbons] First, a method for producing useful hydrocarbons according to an embodiment will be described. Fig. 1 is a block diagram showing an example of a method for producing useful hydrocarbons according to an embodiment.

[0017] As shown in FIG. 1, the method for producing useful hydrocarbons includes a dry reforming step S10, a useful hydrocarbon production step S20, and a recycling step S30.

[0018] In the dry reforming step S10, a first gas containing carbon monoxide and hydrogen is produced from a mixed gas containing methane-containing hydrocarbons and carbon dioxide. The methane-containing hydrocarbons supplied to the dry reforming step S10 are composed of methane and hydrocarbons other than methane. The hydrocarbons other than methane contained in the methane-containing hydrocarbons are not particularly limited, and may be, for example, pure substances of hydrocarbons having 2 to 10 carbon atoms or mixtures thereof, preferably hydrocarbons having 2 to 6 carbon atoms, and more preferably ethane. In this case, the ratio of the number of moles of methane to the number of moles of hydrocarbons having 2 to 6 carbon atoms (methane / hydrocarbons having 2 to 6 carbon atoms) is preferably 1 or more. When the mixed gas containing the methane-containing hydrocarbons described above is supplied to the dry reforming step S10, the yield of useful hydrocarbons is improved.

[0019] Furthermore, the hydrocarbons contained in the methane-containing hydrocarbons may contain a small amount of the target useful hydrocarbons, as long as the amount is less than the amount of the target useful hydrocarbons produced in the second gas.

[0020] In the dry reforming step S10, carbon monoxide and hydrogen are synthesized from methane and carbon dioxide contained in the mixed gas by dry reforming, for example, as shown in the following formula (1). Furthermore, since the hydrocarbons used as the raw material for dry reforming are not limited to methane, formula (1) can be generalized to, for example, saturated hydrocarbons, resulting in the following formula (2). At this time, equal amounts of carbon and carbon dioxide contained in the raw hydrocarbon react.

[0021] CH4+CO2→2CO+2H2...Equation (1) C n H 2n+2 +nCO2→2nCO+(n+1) H2(n≧1)...Equation (2)

[0022] The dry reforming step S10 uses a catalyst (hereinafter simply referred to as a dry reforming catalyst) for synthesizing carbon monoxide and hydrogen from methane-containing hydrocarbons and carbon dioxide contained in the mixed gas by dry reforming. In the dry reforming step S10, the mixed gas is supplied to the dry reforming catalyst while the dry reforming catalyst is heated, whereby the methane-containing hydrocarbons and carbon dioxide in the supplied mixed gas react with each other on the dry reforming catalyst to generate a first gas containing carbon monoxide and hydrogen.

[0023] The dry reforming catalyst is not particularly limited, but from the viewpoint of exhibiting catalytic activity over a long period of time to produce carbon monoxide and hydrogen, the dry reforming catalyst is preferably a catalyst structure comprising a porous carrier made of a zeolite-type compound and at least one catalytic substance present in the carrier, the carrier having passages that communicate with each other, the ratio of the long side dimension L to the thickness dimension d of the carrier (L / d ratio) being 5.0 or more, and the catalytic substance being present in at least the passages of the carrier.

[0024] In such a catalyst structure, the L / d ratio of the carrier is 5.0 or more, preferably 5.0 or more and 35.0 or less, and more preferably 7.0 or more and 25.0 or less. When the L / d ratio of the carrier is 5.0 or more, the catalytic activity can be improved. Furthermore, when the L / d ratio is 35.0 or less, the production yield of the catalyst structure can be improved.

[0025] Furthermore, for such a catalyst structure, the average particle size of the catalyst substance is preferably 1.00 nm or more and 13.00 nm or less. When the average particle size of the catalyst substance is within the above range, the catalytic activity is sufficiently increased, and as the average particle size becomes smaller, the catalytic activity can be improved. Furthermore, from the viewpoint of achieving both high catalytic activity and coking resistance, the average particle size of the catalyst substance is preferably 9.00 nm or less, more preferably 4.50 nm or less.

[0026] Furthermore, any known catalyst for dry reforming can be used. For example, as described in Yuche Gao et al., "A review of recent developments in hydrogen production via biogas dry reforming," Energy Conversion and Management, 171 (2018) 133-155, the catalyst contains at least one metal active in dry reforming selected from Ir, Ru, Rh, Pt, Pd, Ni, Co, and Fe, and the support contains at least one selected from MgO, Al2O3, SiO2, CeO2, CaO, ZrO2, TiO2, La2O3, ZnO, silicalite-1, MCM-41, and SBA-15. However, the dry reforming catalyst is not limited to these.

[0027] The heating temperature of the dry reforming catalyst is appropriately set depending on the type of dry reforming catalyst, the supply amount of the mixed gas, the content ratio of methane-containing hydrocarbons and carbon dioxide contained in the mixed gas, etc. For example, the lower limit of the heating temperature of the dry reforming catalyst is preferably 400°C or higher, more preferably 600°C or higher, and the upper limit is preferably 1000°C or lower, more preferably 900°C or lower.

[0028] The first gas generated in the dry reforming step S10 contains a synthesis gas containing at least carbon monoxide and hydrogen. In addition to carbon monoxide and hydrogen (synthesis gas), the first gas also contains unreacted substances such as hydrocarbons and carbon dioxide, and by-products such as water.

[0029] The carbon monoxide and hydrogen contents in the first gas can be adjusted as appropriate depending on the dry reforming conditions, such as the heating temperature of the dry reforming catalyst, the amount of mixed gas supplied, and the methane-containing hydrocarbon and carbon dioxide contents in the mixed gas.

[0030] In the useful hydrocarbon production step S20 performed after the dry reforming step S10, a second gas containing useful hydrocarbons is produced from carbon monoxide and hydrogen in the first gas produced in the dry reforming step S10, as shown in the following formula (3).

[0031] CO + 2H2 → hydrocarbons Equation (3)

[0032] The second gas produced in the useful hydrocarbon production step S20 contains at least useful hydrocarbons. In addition to useful hydrocarbons, the second gas also contains hydrocarbons that are unreacted substances in the dry reforming step S10 and the useful hydrocarbon production step S20, carbon dioxide, carbon monoxide, hydrogen, water that are by-products of these steps, and hydrocarbons other than useful hydrocarbons.

[0033] In the recycling step S30 performed after the useful hydrocarbon production step S20, a carbon dioxide-containing gas is separated from the second gas produced in the useful hydrocarbon production step S20, and the carbon dioxide-containing gas is supplied to the dry reforming step S10.

[0034] As shown in the above formulas (1) and (2), in the dry reforming step S10, carbon monoxide and hydrogen are produced from methane-containing hydrocarbons and carbon dioxide in the same ratio (carbon basis) (carbon molar ratio of 1:1). On the other hand, as the ratio of carbon dioxide to methane-containing hydrocarbons in the mixed gas decreases, coking of the dry reforming catalyst becomes more likely to occur, resulting in a decrease in the activity of the dry reforming catalyst and a decrease in the amount of useful hydrocarbons produced.

[0035] Therefore, in the recycling step S30, a carbon dioxide-containing gas (so-called off-gas) containing carbon dioxide, an impurity in the second gas produced in the useful hydrocarbon production step S20, is supplied to the dry reforming step S10. This suppresses coking of the dry reforming catalyst due to a decrease in the ratio of carbon dioxide to methane-containing hydrocarbons, thereby suppressing a decrease in the activity of the dry reforming catalyst. This makes it possible to efficiently produce useful hydrocarbons over a long period of time. Furthermore, since the carbon dioxide discharged from the useful hydrocarbon production step S20 is reused as a raw material for the dry reforming step S10, global warming can be suppressed. If the carbon dioxide-containing gas contains hydrocarbons other than useful hydrocarbons, the yield of useful hydrocarbons is further improved.

[0036] The mixed gas supplied to the dry reforming step S10 may also be biogas. Biogas contains methane and other hydrocarbons (methane-containing hydrocarbons) as its main components, and carbon dioxide. Biogas is a renewable energy resource produced from organic waste such as livestock manure, food waste, and wood waste, and is environmentally friendly. As such, biogas can be produced or obtained relatively easily compared to natural resources such as natural gas, which can only be produced in specific regions.

[0037] In this way, biogas is not only a renewable energy resource, but is also easier to obtain than natural resources such as natural gas. Therefore, if biogas is used as a raw material in a production process for useful hydrocarbons, there will be no shortage of raw material and the raw material can be obtained stably.

[0038] On the other hand, the ratio of carbon dioxide to the total of methane-containing hydrocarbons and carbon dioxide contained in biogas is often around 40%, meaning that biogas contains more methane-containing hydrocarbons than carbon dioxide. Thus, biogas contains more methane-containing hydrocarbons than carbon dioxide. Therefore, when biogas is supplied to the dry reforming step S10, there is a shortage of carbon dioxide, and some of the methane-containing hydrocarbons are not utilized, resulting in a decrease in the amount of synthesis gas produced in the dry reforming step S10. Furthermore, because biogas contains more methane-containing hydrocarbons than carbon dioxide, coking of the dry reforming catalyst is likely to occur, as described above, resulting in a decrease in the activity of the dry reforming catalyst and a decrease in the amount of useful hydrocarbons produced.

[0039] To address such concerns, in the recycle step S30, the carbon dioxide-containing gas that is the off-gas is supplied to the dry reforming step S10, making it possible to compensate for the deficiency of carbon dioxide in the biogas. In this way, even when biogas is used as a raw material, the recycle step S30 can prevent a shortage of carbon dioxide derived from the biogas in the dry reforming step S10, making it possible to stably carry out the dry reforming step S10 over a long period of time. Furthermore, coking of the dry reforming catalyst caused by a decrease in the ratio of carbon dioxide to methane-containing hydrocarbons can be suppressed, making it possible to suppress a decrease in the activity of the dry reforming catalyst. As a result, useful hydrocarbons can be produced efficiently over a long period of time.

[0040] In addition, the recycling step S30 is carried out by adjusting the total number of carbon moles M of carbon dioxide in the mixed gas and the carbon dioxide in the carbon dioxide-containing gas supplied to the dry reforming step S10. CO2 The total number of carbon moles M of hydrocarbons supplied to the dry reforming step S10 HC The ratio (M HC / M CO2It is preferable to adjust the supply amount of the carbon dioxide-containing gas to be supplied to the dry reforming step S10 depending on the methane-containing hydrocarbons in the mixed gas and the carbon dioxide-containing gas.

[0041] In the dry reforming step S10, under conditions where the amount of methane-containing hydrocarbons is greater than a predetermined amount, coking of the dry reforming catalyst and a shortage of carbon dioxide may occur. Therefore, the recycle step S30 is performed to reduce the ratio (M HC / M CO2 When the ratio (M HC / M CO2 By adjusting the supply amount of the carbon dioxide-containing gas supplied to the dry reforming step S10 in accordance with the above, it is possible to further suppress the occurrence of coking and the shortage of carbon dioxide in the dry reforming step S10.

[0042] Furthermore, biogas is produced from various types of organic waste. Therefore, the ratio of methane-containing hydrocarbons to carbon dioxide contained in the biogas varies depending on the type of organic waste. Even when the biogas is supplied to the dry reforming step S10, the recycle step S30 can be used to reduce the ratio (M HC / M CO2 ) and adjusts the amount of carbon dioxide-containing gas supplied to the dry reforming step S10 according to the amount of carbon dioxide-containing gas supplied to the dry reforming step S10. Therefore, even if the content ratio of methane-containing hydrocarbons and carbon dioxide in the biogas varies, the occurrence of coking and carbon dioxide shortage in the dry reforming step S10 can be further suppressed.

[0043] The amount of carbon dioxide-containing gas supplied to the dry reforming step S10 is adjusted to satisfy the above ratio (M HC / M CO2 ) is preferably controlled to 1.30 or less, more preferably 1.00 or less, the above effects can be further improved.

[0044] Furthermore, the CO2 concentration of the carbon dioxide-containing gas supplied to the dry reforming step S10 by the recycle step S30 is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. When the CO2 concentration of the carbon dioxide-containing gas is 50% or more, the occurrence of coking and a shortage of carbon dioxide in the dry reforming step S10 can be sufficiently suppressed by adjusting the supply amount of the recycle gas in the recycle step S30.

[0045] Furthermore, the method for producing useful hydrocarbons according to the embodiment may further include a mixed gas generation step (not shown). In the mixed gas generation step, a mixed gas containing methane-containing hydrocarbons and carbon dioxide is generated and supplied to the dry reforming step S10. The mixed gas generation step is preferably a pyrolysis process using biomass resources such as woody biomass or waste plastics as raw materials, or a gasification process in which these raw materials are oxidatively decomposed by adding an oxidizing agent (HO, oxygen, or carbon dioxide).

[0046] In the pyrolysis process and gasification process, gas containing at least carbon monoxide and hydrogen is produced, but hydrocarbons and carbon dioxide are also produced as impurities. These hydrocarbons and carbon dioxide can be supplied from the mixed gas production process to the dry reforming process S10.

[0047] In this case, the method for producing useful hydrocarbons according to the embodiment may include a separation step of separating carbon monoxide and hydrogen from the gas containing hydrocarbons and carbon dioxide between the mixed gas production step and the dry reforming step S10.

[0048] The carbon ratio of hydrocarbons to carbon dioxide varies depending on conditions such as the type of raw materials used in pyrolysis and gasification, their mixing ratio, and reaction temperature.

[0049] If the amount of hydrocarbons in the dry reforming step S10 is greater than the specified amount (carbon dioxide is insufficient), in the recycling step S30, a carbon dioxide-containing gas containing carbon dioxide, an impurity in the second gas produced in the useful hydrocarbon production step S20, is supplied to the dry reforming step S10. This suppresses coking of the dry reforming catalyst due to a decrease in the ratio of carbon dioxide to hydrocarbons, and therefore suppresses a decrease in the activity of the dry reforming catalyst. As a result, the desired useful hydrocarbons can be produced efficiently over a long period of time. Furthermore, since the carbon dioxide discharged from the useful hydrocarbon production step S20 is reused as a raw material for the dry reforming step S10, global warming can be suppressed.

[0050] Furthermore, trace amounts of sulfur and halogens may be mixed in as impurities in the gas produced by the pyrolysis and gasification processes. These can poison the dry reforming catalyst used in the dry reforming step S10 and the useful hydrocarbon production catalyst used in the useful hydrocarbon production step S20, potentially impairing the catalytic performance and causing damage to the equipment. Therefore, a desulfurization step, dehalogenation step, or the like can be appropriately provided as a pretreatment step for the produced gas between the mixed gas production step and the dry reforming step S10.

[0051] Preferably, the method for producing useful hydrocarbons according to the embodiment further includes a hydrogen supply step S40 in which hydrogen is separated from the second gas produced in the useful hydrocarbon production step S20 and supplied to the useful hydrocarbon production step S20.

[0052] As shown in the above formula (3), the useful hydrocarbon production step S20 requires twice the amount of hydrogen relative to carbon monoxide. On the other hand, the ratio of carbon monoxide to hydrogen in the first gas produced in the dry reforming step S10 is the same as shown in the above formulas (1) and (2). As such, since the same ratios of carbon monoxide and hydrogen are produced in the dry reforming step S10 and the useful hydrocarbon production step S20 requires twice the amount of hydrogen as carbon monoxide, performing the useful hydrocarbon production step S20 for a long period of time will lead to a shortage of hydrogen. As a result, carbon monoxide will be surplus, and the amount of useful hydrocarbons produced in the useful hydrocarbon production step S20 will decrease.

[0053] Therefore, in the hydrogen supply step S40, hydrogen (so-called off-gas), which is an impurity in the second gas produced in the useful hydrocarbon production step S20, is supplied to the useful hydrocarbon production step S20, thereby compensating for the deficiency of hydrogen, which is the raw material for the useful hydrocarbon production step S20. In this way, the hydrogen supply step S40 can suppress a hydrogen shortage due to the long-term useful hydrocarbon production step S20, so the useful hydrocarbon production step S20 can be carried out stably over a long period of time. Therefore, useful hydrocarbons that are easy to store and transport can be efficiently produced over a long period of time. Furthermore, since the hydrogen discharged from the useful hydrocarbon production step S20 is reused as a raw material for the useful hydrocarbon production step S20, the environmental impact can be reduced.

[0054] In addition, the hydrogen supply step S40 is performed by increasing the number of moles M of hydrogen in the useful hydrocarbon production step S20. H It is preferable to adjust the amount of hydrogen supplied to the useful hydrocarbon production step S20 depending on the number of moles M H It is also more preferable to adjust the amount of hydrogen supplied to the useful hydrocarbon production step S20 depending on the type and reaction of useful hydrocarbons to be produced.

[0055] For example, when liquefied petroleum gas is produced as useful hydrocarbons, the number of moles of hydrogen M in the useful hydrocarbon production step S20 is HOn the other hand, when the number of moles of hydrogen in the useful hydrocarbon production step S20 is large, the useful hydrocarbon synthesis reaction proceeds smoothly. H If the number of moles of hydrogen in the useful hydrocarbon synthesis reaction is small, there is a possibility that hydrogen shortage will occur in the useful hydrocarbon synthesis reaction. H When the amount of hydrogen supplied to the useful hydrocarbon production step S20 is small, the shortage of hydrogen in the useful hydrocarbon production step S20 can be suppressed by increasing the amount of hydrogen supplied to the useful hydrocarbon production step S20.

[0056] In this way, in the hydrogen supply step S40, the number of moles M of hydrogen in the useful hydrocarbon production step S20 is H When the number of moles M of hydrogen in the useful hydrocarbon production step S20 is small, the amount of hydrogen supplied to the useful hydrocarbon production step S20 is increased. H By adjusting the amount of hydrogen supplied to the useful hydrocarbon production step S20 depending on the amount of hydrogen, the desired useful hydrocarbons can be produced more efficiently.

[0057] In addition, the hydrogen supply step S40 is carried out in a manner similar to that of the useful hydrocarbon production step S20. CO the number of moles of hydrogen M H Molar ratio (M H / M CO It is preferable to adjust the amount of hydrogen supplied to the useful hydrocarbon production step S20 depending on the amount of hydrogen supplied to the useful hydrocarbon production step S20.

[0058] The molar ratio (M H / M CO ), if the ratio of hydrogen to carbon monoxide is very low, there is a possibility of hydrogen shortage. Therefore, in the hydrogen supply step S40, the molar ratio (M H / M CO When the molar ratio (M H / M COBy adjusting the amount of hydrogen supplied to the useful hydrocarbon production step S20 in accordance with the above, it is possible to more reliably prevent a shortage of hydrogen in the useful hydrocarbon production step S20.

[0059] In addition, in the method for producing useful hydrocarbons according to the embodiment, the number of moles M of carbon monoxide contained in the first gas obtained in the dry reforming step S10 is CO the number of moles of hydrogen M H Molar ratio (M H / M CO The adjustment step may further include an adjustment step (not shown) for adjusting the temperature of the sintered body (S10). The adjustment step is performed before the dry reforming step S10.

[0060] The adjustment step is performed by adjusting the molar ratio (M H / M CO The adjustment step is performed before the dry reforming step S10, and adjusts the molar ratio (M H / M CO In the adjustment step, it is preferable to adjust the molar ratio (M H / M CO ) is adjusted.

[0061] The molar ratio (M H / M CO ) is supplied to the useful hydrocarbon production step S20, hydrogen shortage due to the long-term useful hydrocarbon production step S20 can be suppressed, and the useful hydrocarbon production step S20 can be stably carried out for a long period of time. Therefore, the desired useful hydrocarbons can be efficiently produced for a long period of time.

[0062] The method for producing useful hydrocarbons according to the embodiment may further include a combustion step (not shown) in which substances containing carbon atoms are separated from the second gas and combusted to produce carbon dioxide. In this case, the recycle step S30 supplies the carbon dioxide-containing gas and the carbon dioxide produced in the combustion step to the dry reforming step S10.

[0063] For example, when liquefied petroleum gas is produced as useful hydrocarbons, the second gas discharged from the useful hydrocarbon production step S20 contains, in addition to liquefied petroleum gas, impurities such as methane, carbon dioxide, carbon monoxide, methanol, dimethyl ether, hydrocarbons with 1 to 2 carbon atoms, and hydrocarbons with 5 or more carbon atoms. In the combustion step, the carbon atom-containing substances in the second gas discharged from the useful hydrocarbon production step S20 are separated from the second gas, and the separated carbon atom-containing substances are combusted to produce carbon dioxide.

[0064] The carbon atom-containing substance combusted in the combustion step includes at least one substance selected from the group consisting of methane, carbon monoxide, methanol, dimethyl ether, and hydrocarbons other than the target useful hydrocarbons. Note that the carbon atom-containing substance combusted in the combustion step may or may not include carbon dioxide.

[0065] In the recycle step S30, in addition to the carbon dioxide-containing gas separated from the second gas produced in the useful hydrocarbon production step S20, the carbon dioxide produced in the combustion step is also supplied to the dry reforming step S10. The amount of carbon dioxide supplied to the dry reforming step S10 can be increased by the combustion step. Therefore, the occurrence of coking and carbon dioxide shortage due to the dry reforming step S10 can be further suppressed, and the desired useful hydrocarbons can be produced efficiently over a long period of time. In addition, the heat generated in the combustion step can be recovered and used in the dry reforming step S10 and the useful hydrocarbon production step S20.

[0066] It is also preferable to adjust the combustion rate of the combustion step according to the ratio of lower hydrocarbons to carbon dioxide in the hydrocarbons supplied to the dry reforming step S10. The combustion rate of the combustion step is the rate at which hydrocarbons excluding the target useful hydrocarbon components in the second gas are combusted and converted to carbon dioxide, as shown in the following formula (4), and can be calculated from the following formula: For example, when the combustion rate of the combustion step is 100%, the combustion step burns all hydrocarbons excluding the target useful hydrocarbon components in the second gas to produce carbon dioxide.

[0067] 2C n H 2n+2 +(3n+1)O2→(2n+2)H2O+2nCO2...Equation (4)

[0068] Combustion rate (%) = 100 - (total amount of hydrocarbons (C-mol) excluding the target useful hydrocarbon components combusted in the combustion process) x 100 / total amount of hydrocarbons (C-mol) excluding the target useful hydrocarbon components in the second gas)

[0069] In this way, the amount of carbon dioxide produced in the combustion step can be adjusted by changing the combustion rate in the combustion step. Therefore, the amount of carbon dioxide produced can be adjusted by adjusting the combustion rate in the combustion step according to the ratio of lower hydrocarbons and carbon dioxide supplied to the dry reforming step S10, and the amount of carbon dioxide supplied to the dry reforming step S10 in the recycle step S30 can be adjusted, thereby increasing the amount of useful hydrocarbons produced.

[0070] For example, when liquefied petroleum gas is produced in the useful hydrocarbon production step S20, a combustion rate of 3% or higher in the combustion step can sufficiently suppress a shortage of carbon dioxide in the dry reforming step S10. Furthermore, a combustion rate of 50% or lower in the combustion step provides a favorable ratio of lower hydrocarbons to carbon dioxide supplied to the dry reforming step S10. Therefore, a combustion rate of 3% or higher and 50% or lower in the combustion step can efficiently produce useful hydrocarbons over a long period of time.

[0071] Furthermore, when the method for producing useful hydrocarbons according to the embodiment supplies biogas to the dry reforming step S10, it may include a desulfurization step (not shown) for desulfurizing the biogas. The desulfurization step is performed before the dry reforming step S10. Biogas contains sulfur components, such as sulfur compounds like hydrogen sulfide. The sulfur components in the biogas reduce the catalytic performance of the dry reforming catalyst used in the dry reforming step S10 and the useful hydrocarbon production catalyst used in the useful hydrocarbon production step S20. Desulfurizing the biogas in the desulfurization step can suppress the reduction in the catalytic performance of the dry reforming catalyst and the useful hydrocarbon production catalyst. This allows for stable production of the desired useful hydrocarbons over a long period of time.

[0072] Furthermore, the method for producing useful hydrocarbons according to the embodiment may include a dehydration step (not shown) for dehydrating the first gas produced in the dry reforming step S10. The dehydration step is carried out after the dry reforming step S10 and before the useful hydrocarbon production step S20. The first gas supplied to the useful hydrocarbon production step S20 may contain water. By dehydrating the first gas in the dehydration step, the efficiency of the synthesis reaction of useful hydrocarbons carried out in the useful hydrocarbon production step S20 can be improved, and further, a decrease in the catalytic performance of the catalyst for producing useful hydrocarbons due to moisture can be suppressed.

[0073] Furthermore, the method for producing useful hydrocarbons according to the embodiment may include a compression step (not shown) for compressing the first gas produced in the dry reforming step S10. The compression step is carried out after the dry reforming step S10 and before the useful hydrocarbon production step S20. By compressing the first gas in the compression step, the compressed first gas is supplied to the production step S20, thereby improving the efficiency of the synthesis reaction of useful hydrocarbons carried out in the useful hydrocarbon production step S20.

[0074] Furthermore, the useful hydrocarbons produced by the method for producing useful hydrocarbons are preferably at least one hydrocarbon selected from the group consisting of olefins, aromatic hydrocarbons, gasoline, liquefied petroleum gas, and liquid hydrocarbons, and more preferably liquefied petroleum gas.

[0075] The olefins are preferably ethylene and propylene. The aromatic hydrocarbons are preferably benzene, toluene, and xylene. The gasoline is preferably a hydrocarbon having 5 to 12 carbon atoms. The liquefied petroleum gas is preferably a hydrocarbon having 3 to 4 carbon atoms. The liquid hydrocarbons are preferably naphtha, kerosene, jet fuel, light oil, and heavy oil, which are hydrocarbons having 5 or more carbon atoms.

[0076] In the method for producing useful hydrocarbons, a hydrocarbon mixture containing various target useful hydrocarbons as main components can be synthesized from carbon monoxide and hydrogen by various useful hydrocarbon synthesis reactions using appropriate catalysts and under appropriate reaction conditions in the useful hydrocarbon production step S20, depending on the type of useful hydrocarbon to be produced.

[0077] For example, when olefins are produced as useful hydrocarbons, an olefin synthesis reaction is carried out in the useful hydrocarbon production step S20 using a useful hydrocarbon production catalyst (olefin production catalyst) for synthesizing olefins from carbon monoxide and hydrogen contained in the first gas. In the useful hydrocarbon production step S20, the olefin production catalyst is heated while the first gas is supplied to the olefin production catalyst, whereby the carbon monoxide and hydrogen in the supplied first gas react with each other in the olefin production catalyst to produce a second gas containing olefins.

[0078] From the viewpoint of increasing the amount of olefins produced, the catalyst for producing olefins is preferably a catalyst containing a catalyst material for methanol synthesis and a ZSM-5 type zeolite catalyst material.

[0079] In such a catalyst, the ZSM-5 type zeolite catalytic material preferably contains phosphorus (P). When the ZSM-5 type zeolite catalytic material contains P, the acid strength of the ZSM-5 type zeolite catalytic material can be appropriately controlled, thereby suppressing excessive hydrocarbon chain growth and increasing the production of olefins such as ethylene and propylene.

[0080] Furthermore, for such catalysts, the ratio of the number of moles of SiO to the number of moles of AlO contained in the ZSM-5 zeolite catalyst material (number of moles of SiO / number of moles of AlO) is preferably 20 or more and 60 or less. By substituting some of the silicon atoms in the silicate constituting the zeolite framework of the ZSM-5 zeolite catalyst material with aluminum atoms, the aluminum atoms become acid sites, and the zeolite catalyst material exhibits the function of a solid acid. When this ratio is 60 or less, the number of acid sites in the ZSM-5 zeolite catalyst material increases, thereby increasing the amount of olefins produced. When this ratio is 20 or more, catalyst degradation such as coking caused by an excessive number of acid sites can be suppressed.

[0081] The heating temperature of the olefin production catalyst is appropriately set depending on the type of the olefin production catalyst, the supply amount of the first gas, etc. For example, the heating temperature of the olefin production catalyst is 240°C or higher and 350°C or lower.

[0082] Regarding the pressure of the olefin synthesis reaction, the lower limit is preferably 2.0 MPa or more, more preferably 3.0 MPa or more, and even more preferably 3.5 MPa or more, and the upper limit is preferably 6.0 MPa or less, more preferably 5.5 MPa or less, and even more preferably 5.0 MPa or less.

[0083] At this time, the second gas produced in the useful hydrocarbon production step S20 contains at least olefins, which are useful hydrocarbons. In addition to olefins, the second gas also contains hydrocarbons, carbon dioxide, carbon monoxide, hydrogen, and by-products of the dry reforming step S10 and the useful hydrocarbon production step S20, such as unreacted substances in these steps, such as methanol, dimethyl ether, and hydrocarbons with 10 or less carbon atoms.

[0084] The content of olefins in the second gas can be adjusted appropriately depending on the conditions of the olefin synthesis reaction, such as the heating temperature of the olefin production catalyst and the supply amount of the first gas.

[0085] When the useful hydrocarbons are olefins, the carbon dioxide-containing gas preferably contains at least one of hydrocarbons other than the target olefins and carbon monoxide. When the carbon dioxide-containing gas contains the above-mentioned substances, the yield of olefins is significantly improved.

[0086] Furthermore, for example, when aromatic hydrocarbons are produced as useful hydrocarbons, an aromatic hydrocarbon synthesis reaction is carried out in the useful hydrocarbon production step S20 using a useful hydrocarbon production catalyst (aromatic hydrocarbon production catalyst) for synthesizing aromatic hydrocarbons from carbon monoxide and hydrogen contained in the first gas. In the useful hydrocarbon production step S20, the aromatic hydrocarbon production catalyst is heated while the first gas is supplied to the aromatic hydrocarbon production catalyst, whereby the carbon monoxide and hydrogen in the supplied first gas react with each other in the aromatic hydrocarbon production catalyst to produce a second gas containing aromatic hydrocarbons.

[0087] From the viewpoint of increasing the amount of aromatic hydrocarbons produced, the aromatic hydrocarbon production catalyst is preferably a catalyst containing a methanol synthesis catalyst material and a ZSM-5 type zeolite catalyst material.

[0088] In such catalysts, the ZSM-5 zeolite catalytic material preferably supports one or more of MnO, MnCr2O4, MnAl2O4, MnZrO4, ZnO, ZnCr2O4, and ZnAl2O4 as active metal oxides, and more preferably supports one or more of MnO, MnCr2O4, MnAl2O4, and MnZrO4. When the ZSM-5 zeolite catalytic material supports the above metal oxides, the production amount of aromatic hydrocarbons can be increased.

[0089] Furthermore, for such catalysts, the ratio of the number of moles of SiO2 to the number of moles of Al2O3 (number of moles of SiO2 / number of moles of Al2O3) contained in the ZSM-5 zeolite catalyst material is preferably 20 or more and 60 or less. By substituting some of the silicon atoms in the silicate constituting the zeolite framework of the ZSM-5 zeolite catalyst material with aluminum atoms, the aluminum atoms become acid sites, and the zeolite catalyst material exhibits the function of a solid acid. When this ratio is 60 or less, the number of acid sites in the ZSM-5 zeolite catalyst material increases, thereby increasing the amount of aromatic hydrocarbons produced. When this ratio is 20 or more, catalyst degradation such as coking caused by an excessive number of acid sites can be suppressed.

[0090] The heating temperature of the aromatic hydrocarbon production catalyst is set appropriately depending on the type of aromatic hydrocarbon production catalyst, the supply amount of the first gas, etc. For example, the heating temperature of the aromatic hydrocarbon production catalyst is 300°C or higher and 600°C or lower.

[0091] The pressure in the aromatic hydrocarbon synthesis reaction is preferably 0.1 MPa or more and 6.0 MPa or less.

[0092] At this time, the second gas produced in the useful hydrocarbon production step S20 contains at least aromatic hydrocarbons, which are useful hydrocarbons. In addition to aromatic hydrocarbons, the second gas also contains hydrocarbons that are unreacted substances in the dry reforming step S10 and the useful hydrocarbon production step S20, carbon dioxide, carbon monoxide, hydrogen, by-products of these steps such as methanol and dimethyl ether, and hydrocarbons other than aromatic hydrocarbons, which are useful hydrocarbons.

[0093] The content of aromatic hydrocarbons in the second gas can be adjusted appropriately depending on the conditions of the aromatic hydrocarbon synthesis reaction, such as the heating temperature of the aromatic hydrocarbon production catalyst and the supply amount of the first gas.

[0094] When the useful hydrocarbons are aromatic hydrocarbons, the carbon dioxide-containing gas preferably contains at least one of hydrocarbons other than the target aromatic hydrocarbons and carbon monoxide. When the carbon dioxide-containing gas contains the above-mentioned substances, the yield of aromatic hydrocarbons is significantly improved.

[0095] Furthermore, for example, when producing gasoline as useful hydrocarbons, a gasoline synthesis reaction is carried out in the useful hydrocarbon production step S20 using a useful hydrocarbon production catalyst (gasoline production catalyst) for synthesizing gasoline from the carbon monoxide and hydrogen contained in the first gas. In the useful hydrocarbon production step S20, the first gas is supplied to the gasoline production catalyst while the gasoline production catalyst is heated, whereby the carbon monoxide and hydrogen in the supplied first gas react in the gasoline production catalyst to produce a second gas containing gasoline.

[0096] From the viewpoint of increasing the amount of gasoline produced, the gasoline production catalyst is preferably a catalyst containing a methanol synthesis catalytic material and a ZSM-5 type zeolite catalytic material.

[0097] Furthermore, for such catalysts, the ratio of the number of moles of SiO to the number of moles of AlO contained in the ZSM-5 type zeolite catalyst material (number of moles of SiO / number of moles of AlO) is preferably at least 12. Furthermore, the ZSM-5 type zeolite catalyst material preferably has pores formed by up to 12-membered rings, more preferably up to 10-membered rings. By substituting aluminum atoms for some of the silicon atoms in the silicate constituting the zeolite framework of the ZSM-5 type zeolite catalyst material, the aluminum atoms become acid sites, allowing the zeolite catalyst material to function as a solid acid. Such ZSM-5 type zeolite catalyst materials can increase the amount of gasoline produced. Examples of such ZSM-5 type zeolite catalyst materials include ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, and ZSM-38.

[0098] The heating temperature of the gasoline producing catalyst is appropriately set depending on the type of the gasoline producing catalyst, the supply amount of the first gas, etc. For example, the heating temperature of the gasoline producing catalyst is 250°C or higher and 500°C or lower, preferably 300°C or higher and 450°C or lower.

[0099] The pressure of the gasoline synthesis reaction is preferably 25 bar or more and 150 bar or less.

[0100] At this time, the second gas produced in the useful hydrocarbon production step S20 contains at least gasoline, which is a useful hydrocarbon. In addition to gasoline, the second gas also contains hydrocarbons that are unreacted substances in the dry reforming step S10 and the useful hydrocarbon production step S20, carbon dioxide, carbon monoxide, hydrogen, and by-products of these steps, such as methanol, dimethyl ether, and hydrocarbons other than gasoline.

[0101] The content of gasoline in the second gas can be adjusted as appropriate depending on the conditions of the gasoline synthesis reaction, such as the heating temperature of the gasoline production catalyst and the supply amount of the first gas.

[0102] When the useful hydrocarbon is gasoline, it is more preferable that the carbon dioxide-containing gas contains at least one of hydrocarbons other than the target gasoline and carbon monoxide. When the carbon dioxide-containing gas contains the above-mentioned substances, the yield of gasoline is significantly improved.

[0103] Furthermore, for example, when liquefied petroleum gas is produced as useful hydrocarbons, a useful hydrocarbon production catalyst (LPG production catalyst) for synthesizing liquefied petroleum gas from carbon monoxide and hydrogen contained in the first gas is used to carry out a liquefied petroleum gas synthesis reaction in the useful hydrocarbon production step S20. In the useful hydrocarbon production step S20, the first gas is supplied to the LPG production catalyst while the LPG production catalyst is heated, whereby the carbon monoxide and hydrogen in the supplied first gas react on the LPG production catalyst to produce a second gas containing liquefied petroleum gas.

[0104] From the viewpoint of increasing the amount of liquefied petroleum gas produced and increasing the proportion of propane contained in the liquefied petroleum gas, it is preferable that the LPG production catalyst is a catalyst containing a methanol synthesis catalytic material and a ZSM-5 type zeolite catalytic material.

[0105] For such catalysts, it is preferable that the ZSM-5 type zeolite catalytic material supports Pt (platinum) or Pt and Pd (palladium). When the ZSM-5 type zeolite catalytic material supports Pt or Pt and Pd, the amount of liquefied petroleum gas produced and the propane content can be increased. Regarding the state of Pt and Pd supported on the ZSM-5 type zeolite catalytic material, a mixture of elemental Pt and elemental Pd may be present, or Pt and Pd may be alloyed, or at least one elemental metal of Pt or Pd may be present mixed with an alloy of Pt and Pd.

[0106] In addition, for such a catalyst, the ZSM-5 type zeolite catalytic material preferably contains P. When the ZSM-5 type zeolite catalytic material contains P, the acid strength of the ZSM-5 type zeolite catalytic material can be appropriately controlled, thereby increasing the amount of liquefied petroleum gas produced and the propane content.

[0107] Furthermore, for such catalysts, the ratio of the number of moles of SiO2 to the number of moles of Al2O3 (number of moles of SiO2 / number of moles of Al2O3) contained in the ZSM-5 zeolite catalyst material is preferably 20 or more and 60 or less. By substituting some of the silicon atoms in the silicate constituting the zeolite framework of the ZSM-5 zeolite catalyst material with aluminum atoms, the aluminum atoms become acid sites, and the zeolite catalyst material exhibits the function of a solid acid. When this ratio is 60 or less, the number of acid sites in the ZSM-5 zeolite catalyst material increases, thereby enabling an increase in the amount of liquefied petroleum gas produced and the propane content. Furthermore, when this ratio is 20 or more, catalyst degradation such as coking caused by an excessive number of acid sites can be suppressed.

[0108] The heating temperature of the LPG generating catalyst is set appropriately depending on the type of LPG generating catalyst, the supply amount of the first gas, etc. For example, the heating temperature of the LPG generating catalyst is 240°C or higher and 350°C or lower.

[0109] Regarding the pressure of the liquefied petroleum gas synthesis reaction, the lower limit is preferably 2.0 MPa or more, more preferably 3.0 MPa or more, and even more preferably 3.5 MPa or more, and the upper limit is preferably 6.0 MPa or less, more preferably 5.5 MPa or less, and even more preferably 5.0 MPa or less.

[0110] At this time, the second gas produced in the useful hydrocarbon production step S20 contains at least liquefied petroleum gas, which is a useful hydrocarbon. In addition to liquefied petroleum gas, the second gas also contains hydrocarbons, carbon dioxide, carbon monoxide, hydrogen, which are unreacted substances in the dry reforming step S10 and the useful hydrocarbon production step S20, as well as by-products of these steps such as methanol, dimethyl ether, hydrocarbons with a carbon number of 1 to 2, and hydrocarbons with a carbon number of 5 or more.

[0111] The content ratio of liquefied petroleum gas in the second gas can be adjusted as appropriate depending on the conditions of the liquefied petroleum gas synthesis reaction, such as the heating temperature of the LPG production catalyst and the supply amount of the first gas.

[0112] When the useful hydrocarbon is liquefied petroleum gas, the carbon dioxide-containing gas preferably contains hydrocarbons other than those with a carbon number of 3 or 4, more preferably contains at least one of hydrocarbons with a carbon number of 1 to 2 and carbon monoxide, and even more preferably contains ethane. When the carbon dioxide-containing gas contains the above-mentioned substances, the yield of liquefied petroleum gas is significantly improved.

[0113] Furthermore, for example, when liquid hydrocarbons are produced as useful hydrocarbons, a liquid hydrocarbon synthesis reaction is carried out in the useful hydrocarbon production step S20 using a useful hydrocarbon production catalyst (liquid hydrocarbon production catalyst) for synthesizing liquid hydrocarbons from carbon monoxide and hydrogen contained in the first gas. In the useful hydrocarbon production step S20, the liquid hydrocarbon production catalyst is heated while the first gas is supplied to the liquid hydrocarbon production catalyst, whereby the carbon monoxide and hydrogen in the supplied first gas react in the liquid hydrocarbon production catalyst to produce a second gas containing liquid hydrocarbons.

[0114] From the viewpoint of increasing the amount of liquid hydrocarbons produced, the catalyst for producing liquid hydrocarbons is preferably a Fischer-Tropsch synthesis catalyst.

[0115] The FT synthesis catalyst preferably has at least one metal active in the FT reaction supported on a support. The support is preferably Al2O3 or SiO2. The metal active in the FT reaction is preferably Ru, Co, Fe, or Ni, and more preferably Ru or Co. When the metal is Ru, the FT synthesis catalyst preferably contains Ru in an amount of 0.5% by mass or more and 5.0% by mass or less in terms of metal. When the metal is Co, the FT synthesis catalyst preferably contains Co in an amount of 5.0% by mass or more and 40.0% by mass or less in terms of metal.

[0116] The FT synthesis catalyst may be a catalyst structure listed as a suitable example of the dry reforming catalyst above, which includes Co inside.

[0117] The heating temperature of the catalyst for producing liquid hydrocarbons is set appropriately depending on the type of catalyst for producing liquid hydrocarbons, the supply amount of the first gas, etc. For example, the heating temperature of the catalyst for producing liquid hydrocarbons is 200°C or higher and 350°C or lower, preferably 210°C or higher and 310°C or lower, and more preferably 220°C or higher and 290°C or lower.

[0118] The pressure of the liquid hydrocarbon synthesis reaction is preferably 0.5 MPa or more and 10.0 MPa or less, more preferably 0.7 MPa or more and 7.0 MPa or less, and even more preferably 0.8 MPa or less and 5.0 MPa or less.

[0119] At this time, the second gas produced in the useful hydrocarbon production step S20 contains at least liquid hydrocarbons, which are useful hydrocarbons. In addition to liquid hydrocarbons, the second gas also contains hydrocarbons that are unreacted substances in the dry reforming step S10 and the useful hydrocarbon production step S20, carbon dioxide, carbon monoxide, hydrogen, and by-products of these steps, such as methanol, dimethyl ether, and hydrocarbons with a carbon number of 4 or less.

[0120] The content of liquid hydrocarbons in the second gas can be adjusted appropriately depending on the conditions of the liquid hydrocarbon synthesis reaction, such as the heating temperature of the catalyst for producing liquid hydrocarbons and the supply amount of the first gas.

[0121] When the useful hydrocarbons are liquid hydrocarbons, the carbon dioxide-containing gas preferably contains at least one of hydrocarbons having a carbon number of 4 or less and carbon monoxide. When the carbon dioxide-containing gas contains the above-mentioned substances, the yield of liquid hydrocarbons is significantly improved.

[0122] [Useful hydrocarbon production equipment] Next, an apparatus for producing useful hydrocarbons according to an embodiment will be described. Fig. 2 is a schematic diagram showing an example of an apparatus for producing useful hydrocarbons according to an embodiment. The apparatus for producing useful hydrocarbons 1 according to an embodiment is an apparatus for carrying out the method for producing useful hydrocarbons according to the embodiment.

[0123] As shown in FIG. 2, the useful hydrocarbon production apparatus 1 includes a dry reforming section 2, a useful hydrocarbon production section 3, and a recycling section 4.

[0124] A mixed gas containing methane-containing hydrocarbons and carbon dioxide is supplied to the dry reforming section 2 constituting the useful hydrocarbon production apparatus 1. The dry reforming section 2 includes a dry reforming catalyst (not shown) and a heating section (not shown) that heats the dry reforming catalyst. For example, the heating section is a heating furnace. The dry reforming catalyst is heated to a predetermined temperature by the heating section.

[0125] When the mixed gas is supplied to the dry reforming section 2 equipped with a heated dry reforming catalyst, the dry reforming section 2 reacts the methane-containing hydrocarbons and carbon dioxide in the mixed gas with the dry reforming catalyst to generate a first gas containing carbon monoxide and hydrogen. In this way, the dry reforming section 2 performs dry reforming on the mixed gas.

[0126] The useful hydrocarbon production section 3 constituting the useful hydrocarbon production apparatus 1 is supplied with the first gas produced in the dry reforming section 2. The useful hydrocarbon production section 3 includes a useful hydrocarbon production catalyst (not shown) and a heating section (not shown) that heats the useful hydrocarbon production catalyst. For example, the heating section is a heating furnace. The useful hydrocarbon production catalyst is heated to a predetermined temperature by the heating section.

[0127] When the first gas is supplied to the useful hydrocarbon production section 3 equipped with a heated catalyst for producing useful hydrocarbons, the useful hydrocarbon production section 3 reacts carbon monoxide and hydrogen in the first gas with the catalyst for producing useful hydrocarbons to produce a second gas containing the target useful hydrocarbons. In this way, the useful hydrocarbon production section 3 performs a useful hydrocarbon synthesis reaction on the first gas.

[0128] The recycle section 4 constituting the useful hydrocarbon production apparatus 1 separates a carbon dioxide-containing gas from the second gas produced in the useful hydrocarbon production section 3 and supplies the carbon dioxide-containing gas to the dry reforming section 2. When the carbon dioxide-containing gas separated from the second gas discharged from the useful hydrocarbon production section 3 is supplied to the dry reforming section 2 by the recycle section 4, it is possible to suppress the occurrence of coking and a shortage of carbon dioxide in the dry reforming section 2. Therefore, the desired useful hydrocarbons can be produced efficiently over a long period of time.

[0129] The recycle section 4 also determines the total number of carbon moles M of carbon dioxide in the mixed gas and the carbon dioxide in the carbon dioxide-containing gas to be supplied to the dry reforming section 2. CO2 The total number of carbon moles M of hydrocarbons supplied to the dry reforming section 2 HC The ratio (M HC / M CO2 ), it is preferable to adjust the supply amount of the carbon dioxide-containing gas to be supplied to the dry reforming section 2. The hydrocarbons to be supplied to the dry reforming section 2 are methane-containing hydrocarbons in the mixed gas and hydrocarbons contained in the carbon dioxide-containing gas.

[0130] The carbon molar ratio (M HC / M CO2 If the carbon molar ratio (M HC / M CO2 ) is large, by increasing the amount of carbon dioxide-containing gas supplied from the recycle section 4 to the dry reforming section 2, the occurrence of coking and a shortage of carbon dioxide in the dry reforming section 2 can be suppressed.

[0131] In this way, the carbon molar ratio (M HC / M CO2) is large, the carbon molar ratio (M HC / M CO2 ), the amount of carbon dioxide-containing gas supplied from the recycle section 4 to the dry reforming section 2 is adjusted in accordance with the ratio (M HC / M CO2 ) is preferably controlled to 1.30 or less, more preferably 1.00 or less, the above effects can be further improved.

[0132] Furthermore, the CO2 concentration of the carbon dioxide-containing gas supplied to the dry reforming section 2 by the recycle section 4 is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. When the CO2 concentration of the carbon dioxide-containing gas is 50% or more, the occurrence of coking and carbon dioxide shortage in the dry reforming section 2 can be sufficiently suppressed by adjusting the supply amount of recycle gas in the recycle section 4.

[0133] Furthermore, the useful hydrocarbon production apparatus 1 of the embodiment may further include a mixed gas generation unit (not shown). The mixed gas generation unit generates a mixed gas containing methane-containing hydrocarbons and carbon dioxide and supplies it to the dry reforming unit 2. The mixed gas generation unit preferably performs a pyrolysis process using biomass resources such as woody biomass or waste plastics as raw materials, or a gasification process in which these raw materials are oxidatively decomposed by adding an oxidizing agent (HO, oxygen, or carbon dioxide).

[0134] In the pyrolysis process and gasification process, gas containing at least carbon monoxide and hydrogen is produced, but hydrocarbons and carbon dioxide are also produced as impurities. These hydrocarbons and carbon dioxide can be supplied from the mixed gas production section to the dry reforming section 2.

[0135] In this case, the useful hydrocarbon production apparatus 1 of the embodiment may include a separation section between the mixed gas production section and the dry reforming section 2, which separates carbon monoxide and hydrogen from the gas containing hydrocarbons and carbon dioxide.

[0136] Furthermore, trace amounts of sulfur and halogens may be mixed in as impurities in the gas produced by the pyrolysis and gasification processes. These can poison the dry reforming catalyst used in the dry reforming section 2 and the useful hydrocarbon production catalyst used in the useful hydrocarbon production section 3, potentially impairing the catalytic performance and causing damage to the equipment. Therefore, a desulfurization process or dehalogenation process can be provided as appropriate between the mixed gas production section and the dry reforming section 2 as a pretreatment process for the produced gas.

[0137] Furthermore, the useful hydrocarbon production apparatus 1 of the embodiment preferably further includes a hydrogen supply unit 5 that separates hydrogen from the second gas produced in the useful hydrocarbon production unit 3 and supplies the hydrogen to the useful hydrocarbon production unit 3. When hydrogen, which is an impurity in the second gas discharged from the useful hydrocarbon production unit 3, is supplied to the useful hydrocarbon production unit 3 by the hydrogen supply unit 5, a shortage of hydrogen in the useful hydrocarbon production unit 3 can be suppressed. Therefore, the desired useful hydrocarbons can be efficiently produced over a long period of time. Furthermore, the hydrogen discharged from the useful hydrocarbon production unit 3 is reused as a raw material for the useful hydrocarbon production unit 3, thereby reducing the environmental burden.

[0138] The hydrogen supply unit 5 also determines the number of moles of hydrogen M in the useful hydrocarbon production unit 3. H It is preferable to adjust the amount of hydrogen supplied to the useful hydrocarbon production section 3 according to the number of moles M H It is also more preferable to adjust the amount of hydrogen supplied to the useful hydrocarbon production section 3 depending on the type and reaction of useful hydrocarbons to be produced.

[0139] For example, when liquefied petroleum gas is produced as useful hydrocarbons, the number of moles of hydrogen in the useful hydrocarbon production section 3, M HIf the number of moles of hydrogen in the useful hydrocarbon production section 3 is small, there is a possibility that hydrogen shortage will occur in the useful hydrocarbon production section 3. H When the amount of hydrogen supplied to the useful hydrocarbon production section 3 by the hydrogen supply section 5 is small, the shortage of hydrogen in the useful hydrocarbon production section 3 can be suppressed.

[0140] In this way, the number of moles of hydrogen in the useful hydrocarbon production section 3, M H When the number of moles M of hydrogen in the useful hydrocarbon production section 3 is small, the hydrogen supply section 5 increases the amount of hydrogen supplied to the useful hydrocarbon production section 3. H By adjusting the amount of hydrogen supplied from the hydrogen supply unit 5 to the useful hydrocarbon production unit 3 according to the amount of hydrogen supplied, the desired useful hydrocarbons can be produced more efficiently.

[0141] The hydrogen supply unit 5 also supplies the useful hydrocarbons to the useful hydrocarbon production unit 3. CO the number of moles of hydrogen M H Molar ratio (M H / M CO It is preferable to adjust the amount of hydrogen supplied to the useful hydrocarbon production section 3 depending on the amount of hydrogen supplied to the useful hydrocarbon production section 3.

[0142] Molar ratio of useful hydrocarbon production section 3 (M H / M CO Regarding the molar ratio (M H / M CO When the molar ratio (M H / M CO By adjusting the amount of hydrogen supplied from the hydrogen supply section 5 to the useful hydrocarbon production section 3 in accordance with the above-mentioned condition, it is possible to more reliably prevent hydrogen shortage in the useful hydrocarbon production section 3.

[0143] In addition, the apparatus 1 for producing useful hydrocarbons according to the embodiment has a number of moles M of carbon monoxide contained in the first gas obtained in the dry reforming section 2. CO the number of moles of hydrogen M H Molar ratio (M H / M CO The adjusting unit may further include an adjusting unit (not shown) that adjusts the temperature of the dry reforming unit 2. The adjusting unit is provided before the dry reforming unit 2.

[0144] The adjustment section adjusts the molar ratio (M H / M CO The adjusting section is preferably a steam drum. The steam drum supplies steam to the dry reforming section 2 to adjust the molar ratio (M H / M CO In the adjusting section, the molar ratio (M H / M CO ) is adjusted.

[0145] The molar ratio (M H / M CO ) is supplied to the useful hydrocarbon production section 3, it is possible to suppress hydrogen shortage in the useful hydrocarbon production section 3. Therefore, it is possible to efficiently produce the desired useful hydrocarbons over a long period of time.

[0146] The apparatus 1 for producing useful hydrocarbons according to the embodiment may further include a combustion unit (not shown) that separates substances containing carbon atoms from the second gas and burns the substances containing carbon atoms to produce carbon dioxide. In this case, the recycle unit 4 supplies the carbon dioxide-containing gas and the carbon dioxide produced in the combustion unit to the dry reforming unit 2.

[0147] In the combustion section, substances containing carbon atoms in the second gas discharged from the useful hydrocarbon production section 3 are separated from the second gas, and the separated substances containing carbon atoms are combusted to produce carbon dioxide. The substances containing carbon atoms combusted in the combustion section include at least one substance selected from the group consisting of methane, carbon monoxide, methanol, dimethyl ether, and hydrocarbons other than the target useful hydrocarbons. Note that the substances containing carbon atoms combusted in the combustion section may or may not include carbon dioxide.

[0148] The recycle section 4 supplies to the dry reforming section 2 not only the carbon dioxide-containing gas separated from the second gas produced in the useful hydrocarbon production section 3, but also the carbon dioxide produced in the combustion section. The amount of carbon dioxide supplied to the dry reforming section 2 can be increased by the combustion section. This further suppresses the occurrence of coking and carbon dioxide shortages in the dry reforming section 2, allowing the desired useful hydrocarbons to be produced efficiently over a long period of time. In addition, the heat generated in the combustion section can be recovered and used in the dry reforming section 2 and the useful hydrocarbon production section 3.

[0149] It is also preferable to adjust the combustion rate of the combustion section according to the ratio of hydrocarbons and carbon dioxide supplied to the dry reforming section 2. By changing the combustion rate of the combustion section, the amount of carbon dioxide produced in the combustion section can be adjusted. Therefore, the combustion rate of the combustion section can be adjusted according to the ratio of hydrocarbons and carbon dioxide supplied to the dry reforming section 2 to adjust the amount of carbon dioxide produced, and the amount of carbon dioxide supplied to the dry reforming section 2 by the recycle section 4 can be adjusted, thereby increasing the amount of useful hydrocarbons produced.

[0150] When the combustion rate of the combustion section is 3% or more, it is possible to sufficiently suppress a shortage of carbon dioxide in the dry reforming section 2. Furthermore, when the combustion rate of the combustion section is 50% or less, the ratio of hydrocarbons to carbon dioxide supplied to the dry reforming section 2 is favorable. Therefore, when the combustion rate of the combustion section is 3% or more and 50% or less, it is possible to efficiently produce the target useful hydrocarbons over a long period of time.

[0151] Furthermore, when the apparatus 1 for producing useful hydrocarbons according to the embodiment supplies biogas to the dry reforming section 2, it may include a desulfurization section (not shown) that desulfurizes the biogas. The desulfurization section is connected upstream of the dry reforming section 2. Sulfur components in the biogas reduce the catalytic performance of the dry reforming catalyst installed in the dry reforming section 2 and the useful hydrocarbon production catalyst installed in the useful hydrocarbon production section 3. By desulfurizing the biogas using the desulfurization section, it is possible to suppress the reduction in the catalytic performance of the dry reforming catalyst and the useful hydrocarbon production catalyst. As a result, the desired useful hydrocarbons can be produced stably over a long period of time.

[0152] Furthermore, the useful hydrocarbon production apparatus 1 of the embodiment may include a dehydration section (not shown) that dehydrates the first gas produced in the dry reforming section 2. The dehydration section is provided between the dry reforming section 2 and the useful hydrocarbon production section 3. By dehydrating the first gas in the dehydration section, it is possible to improve the efficiency of the useful hydrocarbon synthesis reaction carried out in the useful hydrocarbon production section 3, and further to suppress a decrease in the catalytic performance of the useful hydrocarbon production catalyst due to moisture.

[0153] Furthermore, the useful hydrocarbon production apparatus 1 of the embodiment may include a compression section (not shown) that compresses the first gas produced in the dry reforming section 2. The compression section is provided between the dry reforming section 2 and the useful hydrocarbon production section 3. By compressing the first gas in the compression section, the compressed first gas is supplied to the useful hydrocarbon production section 3, and therefore the efficiency of the synthesis reaction of the desired useful hydrocarbons carried out in the useful hydrocarbon production section 3 can be improved.

[0154] Furthermore, the useful hydrocarbons produced by the useful hydrocarbon production apparatus 1 are similar to the useful hydrocarbons produced by the above-mentioned useful hydrocarbon production method, and are preferably at least one type of hydrocarbon selected from the group consisting of olefins, aromatic hydrocarbons, gasoline, liquefied petroleum gas, and liquid hydrocarbons, and more preferably liquefied petroleum gas.

[0155] In the useful hydrocarbon production apparatus 1, a hydrocarbon mixture containing various target useful hydrocarbons as main components can be synthesized from carbon monoxide and hydrogen through various useful hydrocarbon synthesis reactions using appropriate catalysts and under appropriate reaction conditions in the useful hydrocarbon production section 3, depending on the type of useful hydrocarbon to be produced. The various useful hydrocarbon synthesis reactions performed in the useful hydrocarbon production section 3 are under the same conditions as those in the useful hydrocarbon production step S20 in the useful hydrocarbon production method described above.

[0156] According to the embodiment described above, by focusing on methane-containing hydrocarbons and carbon dioxide that can be obtained relatively easily, dry reforming that can produce carbon monoxide and hydrogen from the methane-containing hydrocarbons and carbon dioxide, and the fact that the second gas obtained in the useful hydrocarbon production step contains carbon dioxide as an impurity, the carbon dioxide in the second gas is supplied to the dry reforming step and reused, it is possible to produce the desired useful hydrocarbons efficiently over a long period of time using easily obtainable raw materials.

[0157] Furthermore, the technology of the present disclosure can be suitably applied to natural gas containing a large amount of carbon dioxide as an impurity, which is produced from gas fields in countries with abundant natural gas reserves, such as Indonesia and Malaysia, where the cost of treating impurities has become an issue in recent years. If a gas having a methane / carbon dioxide ratio of 1 to 9 in molar terms is used as a raw material instead of the above-mentioned mixed gas and a dry reforming step is performed to produce a first gas containing carbon monoxide and hydrogen from the raw material, a large amount of carbon dioxide can be efficiently supplied to the dry reforming step, which makes it possible to efficiently produce the desired useful hydrocarbons over a long period of time and eliminates the problem of the cost of treating gas containing a large amount of carbon dioxide as an impurity.

[0158] Although the embodiments have been described above, the present invention is not limited to the above embodiments, but includes all aspects encompassed by the concept and scope of the claims of the present disclosure, and can be modified in various ways within the scope of the present disclosure. [Example]

[0159] Next, examples and comparative examples will be described, but the present invention is not limited to these examples.

[0160] (Examples 1-1 to 1-5, Reference Example 1-1) Using the apparatus shown in Figure 2, liquefied petroleum gas, a useful hydrocarbon, was produced by the production method shown in Figure 1. Specifically, the process is as follows.

[0161] A fixed-bed flow reactor was used for the dry reforming section 2. A quartz glass reaction tube was used. As mentioned above, biogas contains more methane than carbon dioxide. Therefore, assuming that carbon dioxide was supplied from the recycle section 4, raw materials with the same methane to carbon dioxide ratio (carbon basis) were supplied to the dry reforming section 2. The total flow rate of methane and carbon dioxide for the raw materials supplied to the dry reforming section 2 was set to 10 ml / min. A dry reforming catalyst was packed to achieve a GHSV of 2170 (1 / h), and quartz wool was packed above and below it to fix the dry reforming catalyst. The dry reforming catalyst used was the above-mentioned dry reforming catalyst containing 1% by mass of Ni. The heating temperature of the dry reforming catalyst was set to 700°C. The first gas generated in the dry reforming section 2 was collected in a gas pack and analyzed by GC-TCD. As a pretreatment, the dry reforming catalyst was subjected to reduction treatment in a hydrogen stream at 700° C. for 1.5 hours.

[0162] A fixed-bed flow reactor was used for the useful hydrocarbon production section 3. A stainless steel reaction tube was used. As described above, the dry reforming section 2 produces carbon monoxide and hydrogen in equal proportions. Therefore, assuming that hydrogen was not supplied from the hydrogen supply section 5, a first gas with the same molar ratio of carbon monoxide to hydrogen was supplied to the useful hydrocarbon production section 3. The flow rate of the first gas supplied to the useful hydrocarbon production section 3 was set to 37.2 ml / min. A useful hydrocarbon production catalyst (LPG production catalyst) was packed to achieve a GHSV of 2000 (1 / h), and the LPG production catalyst was fixed by packing quartz wool above and below it. The LPG production catalyst was a physical mixture of a methanol synthesis catalyst material and a ZSM-5 zeolite catalyst material supporting platinum and palladium in a weight ratio of 1:1. The heating temperature of the LPG production catalyst was set to 280 °C. The pressure inside the useful hydrocarbon production section 3 was set to 5.0 MPa. The second gas produced in the useful hydrocarbon production section 3 was collected in a gas pack and analyzed by GC-TCD and FID. As a pretreatment, the LPG production catalyst was subjected to reduction treatment at 380°C for 2 hours under a hydrogen flow.

[0163] (Comparative Examples 1-1 to 1-3) The same procedures as in the above-described Examples were carried out except for the changes shown in Table 1. In Comparative Examples 1-1 to 1-3, it was assumed that carbon dioxide was not supplied from the recycle section 4.

[0164] Regarding the ranking of syngas yields in Table 1, the syngas yield is 1.20 kg / Nm 3 Above is "good", synthesis gas yield is 1.20kg / Nm 3 In addition, in the ranking of the overall evaluation, when the ranks of both the initial synthesis gas yield and the synthesis gas yield after 7 days were good, it was marked as "◯", when the rank of either the initial synthesis gas yield or the synthesis gas yield after 7 days was good, it was marked as "△", and when the ranks of both the initial synthesis gas yield and the synthesis gas yield after 7 days were poor, it was marked as "×".

[0165] [Table 1]

[0166] As shown in Table 1, in the example in which carbon dioxide is supplied from the recycle section 4 to the dry reforming section 2, the hydrocarbon / carbon dioxide carbon molar ratio in the inlet gas of the dry reforming step is better than in the comparative example, and therefore the synthesis gas yield can be increased. In this case, a hydrocarbon / carbon dioxide carbon molar ratio of 1.30 or less results in a good synthesis gas yield. It is even more preferable to set the ratio to 1.00 or less, as catalyst degradation can be effectively suppressed, suggesting that synthesis gas can be produced efficiently over a long period of time and the yield of useful hydrocarbons can be increased.

[0167] Furthermore, from Examples 1-5, in order to appropriately adjust the carbon molar ratio of the hydrocarbon / carbon dioxide, if the concentration of carbon dioxide in the recycled gas is 50% or more, the amount of recycled gas in the recycling step can be adjusted to ensure the amount of carbon dioxide necessary to properly adjust the carbon molar ratio of the hydrocarbon / carbon dioxide.

[0168] As described above, it was suggested that by maintaining both the CO2 concentration in the recycle gas and the hydrocarbon / carbon dioxide carbon molar ratio in the inlet gas of the dry reforming process at a favorable level, synthesis gas can be produced efficiently over the long term and the yield of useful hydrocarbons can be increased.

[0169] (Examples 2 and 3) The same procedures as in Example 1-1 were carried out except that the first gas was changed to one having the molar ratio of carbon monoxide and hydrogen shown in Table 2. That is, in Examples 2 and 3, hydrogen was supplied from the hydrogen supply unit 5.

[0170] [Table 2]

[0171] As shown in Table 2, by supplying hydrogen from the hydrogen supply unit 5 and doubling the molar ratio of hydrogen to carbon dioxide, the yield of liquefied petroleum gas could be increased.

[0172] (Examples 3-1 to 3-3) Next, in Example 3, the combustion section was operated at the combustion rate shown in Table 3, and the amount of carbon dioxide supplied from the recycle section 4 to the dry reforming section 2 was adjusted. Then, the amount of total hydrocarbons excluding liquefied petroleum gas components in the second gas and the amount of carbon dioxide in the second gas were measured, and the ratio of carbon dioxide to total hydrocarbons excluding liquefied petroleum gas components in the second gas was calculated. Note that in Example 3-1, the combustion section was not operated.

[0173] [Table 3]

[0174] As shown in Table 3, it was suggested that by changing the combustion rate of the combustion section, the amount of carbon dioxide can be adjusted, thereby increasing the amount of liquefied petroleum gas produced.

[0175] From the above, it was suggested that the above examples make it possible to efficiently produce liquefied petroleum gas over a long period of time using easily obtainable raw materials.

[0176] Example 4 The useful hydrocarbon production catalyst (olefin production catalyst) packed in the useful hydrocarbon production section 3 is a physical mixture of a methanol synthesis catalyst and a P-supported ZSM-5 type zeolite catalyst material in a weight ratio of 1:1. The reaction temperature is 320°C, GHSV = 2000h -1 Olefins were produced in the same manner as in the above example, except that the pressure was 5.0 MPa and the H2 / CO ratio was 2.0.

[0177] Example 5 The useful hydrocarbon production catalyst (aromatic hydrocarbon production catalyst) packed in the useful hydrocarbon production section 3 is a physical mixture of a methanol synthesis catalyst and ZSM-5 type zeolite (ZnCr2O4 / ZSM-5) physically mixed with 1 wt% ZnCr2O4 in a weight ratio of 1:1. The reaction temperature is 350°C, GHSV = 500 h-1 Aromatic hydrocarbons were produced in the same manner as in the above example, except that the pressure was 5.0 MPa and the H2 / CO ratio was 2.5.

[0178] Example 6 The useful hydrocarbon production catalyst (gasoline production catalyst) packed in the useful hydrocarbon production section 3 is a physical mixture of a methanol synthesis catalyst and ZSM-5 type zeolite in a weight ratio of 1:1. The reaction temperature is 370°C, GHSV = 3700 h-1 Gasoline was produced in the same manner as in the above example, except that the pressure was 5.0 MPa and the H2 / CO ratio was 2.0.

[0179] Example 7 The useful hydrocarbon production catalyst (liquid hydrocarbon production catalyst) packed in the useful hydrocarbon production section 3 is 0.5 wt% Co-supported SiO2, and the reaction temperature is 230°C, GHSV = 3000. h-1 Liquid hydrocarbons were produced in the same manner as in the above example, except that the pressure was 2.0 MPa and the H2 / CO ratio was 2.0.

[0180] [Table 4]

[0181] As shown in Table 4, by appropriately changing the catalyst and reaction conditions, it was possible to produce olefins, aromatic hydrocarbons, gasoline fractions, and liquid hydrocarbons in the useful hydrocarbon production process.

[0182] Kumagai et al., "Conversion of woody biomass / waste plastic mixtures into chemical raw materials and fuels by co-pyrolysis," Journal of the Waste Management Society, Vol. 28, No. 1, pp. 4-12, 2017, reports that the gas composition obtained by pyrolysis of woody biomass is shown in Table 5 (1) (all C2 to C4 components are converted to C2). Assuming that only methane and ethane are produced as hydrocarbons, adding recycled gas (2) to gas component (1) after pyrolysis in the recycling process can adjust the concentration to the composition shown in Table 5 (3), and it can be seen that the carbon molar ratio of hydrocarbons to carbon dioxide can be adjusted to a suitable value equivalent to that of the above example in Table 1.

[0183] As described above, the above-described embodiments and examples can be applied to various raw materials, such as biogas obtained by methane fermentation of organic waste such as livestock manure, woody biomass, and gas obtained by pyrolysis and gasification of waste plastic.

[0184] [Table 5] [Explanation of symbols]

[0185] 1. Useful hydrocarbon production equipment 2 Dry reforming section 3. Useful hydrocarbon production section 4. Recycling Department 5 Hydrogen supply unit

Claims

1. a dry reforming step of producing a first gas containing carbon monoxide and hydrogen from a mixed gas containing methane-containing hydrocarbons and carbon dioxide; a useful hydrocarbon production step of producing a second gas containing useful hydrocarbons from carbon monoxide and hydrogen in the first gas; a recycling step of separating a carbon dioxide-containing gas from the second gas and supplying the gas to the dry reforming step; A method for producing useful hydrocarbons comprising the steps of:

2. The recycling step is performed by adjusting the total number of carbon moles M of carbon dioxide in the mixed gas and the carbon dioxide in the carbon dioxide-containing gas to be supplied to the dry reforming step. ＣＯ２ The total number of carbon moles M of hydrocarbons supplied to the dry reforming step ＨＣ The ratio (M ＨＣ / M ＣＯ２ 2. The method for producing useful hydrocarbons according to claim 1, wherein the amount of the carbon dioxide-containing gas supplied to the dry reforming step is adjusted depending on the amount of the carbon dioxide-containing gas.

3. The carbon dioxide-containing gas ２ 3. The method for producing useful hydrocarbons according to claim 1, wherein the concentration is 50% or more.

4. 4. The method for producing useful hydrocarbons according to claim 1, further comprising a hydrogen supply step of separating hydrogen from the second gas and supplying the hydrogen to the useful hydrocarbon production step.

5. The hydrogen supply step is performed by supplying hydrogen to the useful hydrocarbon production step using a number of moles M Ｈ The method for producing useful hydrocarbons according to claim 4, wherein the amount of hydrogen supplied to the useful hydrocarbon production step is adjusted depending on the amount of hydrogen.

6. The number of moles M of carbon monoxide contained in the first gas obtained in the dry reforming step ＣＯ The number of moles of hydrogen M Ｈ The molar ratio (M Ｈ / M ＣＯ The method for producing useful hydrocarbons according to any one of claims 1 to 5, further comprising a step of adjusting the sulphur dioxide.

7. a combustion step of separating a substance containing carbon atoms from the second gas and combusting the substance containing carbon atoms to produce carbon dioxide; 7. The method for producing useful hydrocarbons according to claim 1, wherein the recycling step supplies the carbon dioxide-containing gas and the carbon dioxide produced in the combustion step to the dry reforming step.

8. The method for producing useful hydrocarbons according to any one of claims 1 to 7, wherein the useful hydrocarbons are at least one hydrocarbon selected from the group consisting of olefins, aromatic hydrocarbons, gasoline, liquefied petroleum gas, and liquid hydrocarbons.

9. The method for producing useful hydrocarbons according to any one of claims 1 to 8, wherein the useful hydrocarbons are liquefied petroleum gases.

10. The method for producing useful hydrocarbons according to any one of claims 1 to 8, wherein the useful hydrocarbons are liquefied petroleum gases, and the carbon dioxide-containing gas contains hydrocarbons other than those with carbon numbers of 3 or 4.

11. The method for producing useful hydrocarbons according to any one of claims 1 to 8, wherein the useful hydrocarbons are olefins, and the carbon dioxide-containing gas contains at least one of hydrocarbons other than the target olefins and carbon monoxide.

12. The method for producing useful hydrocarbons according to any one of claims 1 to 8, wherein the useful hydrocarbons are aromatic hydrocarbons, and the carbon dioxide-containing gas contains at least one of hydrocarbons other than the target aromatic hydrocarbons and carbon monoxide.

13. The method for producing useful hydrocarbons according to any one of claims 1 to 8, wherein the useful hydrocarbons are gasoline, and the carbon dioxide-containing gas contains at least one of hydrocarbons other than gasoline and carbon monoxide.

14. The method for producing useful hydrocarbons according to any one of claims 1 to 8, wherein the useful hydrocarbons are liquid hydrocarbons, and the carbon dioxide-containing gas contains at least one of hydrocarbons having 4 or less carbon atoms and carbon monoxide.

15. a dry reforming section that generates a first gas containing carbon monoxide and hydrogen from a mixed gas containing methane-containing hydrocarbons and carbon dioxide; a useful hydrocarbon production section to which the first gas produced in the dry reforming section is supplied and which produces a second gas containing useful hydrocarbons from carbon monoxide and hydrogen in the first gas; a recycle section that separates a carbon dioxide-containing gas from the second gas produced in the useful hydrocarbon production section and supplies the gas to the dry reforming section; A useful hydrocarbon production apparatus comprising:

16. a dry reforming step of producing a first gas containing carbon monoxide and hydrogen from a gas having a methane / carbon dioxide ratio of 1 to 9 in terms of moles; a useful hydrocarbon production step of producing a second gas containing useful hydrocarbons from carbon monoxide and hydrogen in the first gas; a recycling step of separating a carbon dioxide-containing gas from the second gas and supplying the gas to the dry reforming step; A method for producing useful hydrocarbons comprising the steps of:

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