Method and apparatus for producing useful hydrocarbon

Abstract

To provide a method and apparatus for producing a useful hydrocarbon, which can produce the useful hydrocarbon efficiently over a long period of time using a methane-containing hydrocarbon and carbon dioxide which are easily obtained raw materials.SOLUTION: A method for producing a useful hydrocarbon has: a dry reforming process 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 process of producing a second gas containing a useful hydrocarbon from the carbon monoxide and the hydrogen in the first gas; and a recycling process of separating a carbon dioxide-containing gas from the second gas and feeding it to the dry reforming process.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 Art

[0002] Useful hydrocarbons such as various lower olefins and aromatic hydrocarbons that are basic chemical raw materials, and various liquid fuels (such as gasoline, liquefied petroleum gas (LPG), and aviation fuel) are hydrocarbons having 2 or more carbon atoms and are mainly produced from petroleum resources. However, in the production processes of these hydrocarbons, geopolitical risks are a concern mainly because petroleum resources are used as raw materials. Furthermore, in the production and consumption processes of these hydrocarbons, a large amount of carbon dioxide is emitted, so it is also regarded as a problem from the perspective of global warming. Therefore, the development of a clean process that uses resources with unlimited occurrence areas as raw materials and emits less carbon dioxide is being explored.

[0003]

[0004] ​In addition to this, in recent years, renewable energies such as biogas power generation and solar power generation using organic wastes such as livestock manure and sewage sludge have attracted attention. However, since the energy forms obtained by these technologies are electricity, energy transportation is difficult depending on the power transmission capacity situation. Furthermore, in biogas power generation, only methane gas among methane gas and carbon dioxide obtained from organic wastes is utilized. Therefore, the current situation where carbon dioxide is not utilized is not preferable from the viewpoint of global warming.

[0005] Thus, natural resources do not exist in inexhaustible quantities and can only be produced in specific countries or regions. Furthermore, also in the case of renewable energies, from the viewpoint of energy storage and transportation, energy forms other than electricity are required.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present disclosure is to provide a method for producing useful hydrocarbons and a production apparatus for useful hydrocarbons that can be efficiently produced over a long period using methane-containing hydrocarbons and carbon dioxide, which are easily obtainable raw materials.

Means for Solving the Problems

[0008] [1] A method for producing useful hydrocarbons having a dry reforming step of generating a first gas containing carbon monoxide and hydrogen from a mixed gas containing methane-containing hydrocarbons and carbon dioxide, a useful hydrocarbon generation step of generating a second gas containing useful hydrocarbons 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 it to the dry reforming step. [2] The recycling step adjusts the supply amount of the carbon dioxide-containing gas supplied to the dry reforming step according to the ratio (M<M HC / M CO2 ) of the total carbon molar number M of carbon dioxide in the mixed gas supplied to the dry reforming step and the total carbon molar number M of hydrocarbons supplied to the dry reforming step, where M is the total carbon molar number of carbon dioxide in the carbon dioxide-containing gas, for the useful hydrocarbon production method described in [1] above. CO2 [2] The recycling step adjusts the supply amount of the carbon dioxide-containing gas supplied to the dry reforming step according to the ratio (M<M HC / M CO2 ) of the total carbon molar number M of carbon dioxide in the mixed gas supplied to the dry reforming step and the total carbon molar number M of hydrocarbons supplied to the dry reforming step, where M is the total carbon molar number of carbon dioxide in the carbon dioxide-containing gas, for the useful hydrocarbon production method described in [1] above. HC [2] The recycling step adjusts the supply amount of the carbon dioxide-containing gas supplied to the dry reforming step according to the ratio (M<M HC / M CO2 ) of the total carbon molar number M of carbon dioxide in the mixed gas supplied to the dry reforming step and the total carbon molar number M of hydrocarbons supplied to the dry reforming step, where M is the total carbon molar number of carbon dioxide in the carbon dioxide-containing gas, for the useful hydrocarbon production method described in [1] above. HC [2] The recycling step adjusts the supply amount of the carbon dioxide-containing gas supplied to the dry reforming step according to the ratio (M<M HC / M CO2 ) of the total carbon molar number M of carbon dioxide in the mixed gas supplied to the dry reforming step and the total carbon molar number M of hydrocarbons supplied to the dry reforming step, where M is the total carbon molar number of carbon dioxide in the carbon dioxide-containing gas, for the useful hydrocarbon production method described in [1] above. CO2 ) of the total carbon molar number M of carbon dioxide in the mixed gas supplied to the dry reforming step and the total carbon molar number M of hydrocarbons supplied to the dry reforming step, where M is the total carbon molar number of carbon dioxide in the carbon dioxide-containing gas, for the useful hydrocarbon production method described in [1] above. [3] In the useful hydrocarbon production method described in [1] or [2] above, the CO2 concentration of the carbon dioxide-containing gas is 50% or more. [4] The useful hydrocarbon production method according to any one of [1] to [3] above further includes a hydrogen supply step of separating hydrogen from the second gas and supplying it to the useful hydrocarbon production step. [5] In the hydrogen supply step, the supply amount of hydrogen supplied to the useful hydrocarbon production step is adjusted according to the molar number M H of hydrogen in the useful hydrocarbon production step, for the useful hydrocarbon production method described in [4] above. H [5] In the hydrogen supply step, the supply amount of hydrogen supplied to the useful hydrocarbon production step is adjusted according to the molar number M H of hydrogen in the useful hydrocarbon production step, for the useful hydrocarbon production method described in [4] above. [6] The useful hydrocarbon production method according to any one of [1] to [5] above further includes an adjustment step of adjusting the molar ratio (M H / M CO ) of the molar number M CO of carbon monoxide contained in the first gas obtained in the dry reforming step to the molar number M H of hydrogen. CO [6] The useful hydrocarbon production method according to any one of [1] to [5] above further includes an adjustment step of adjusting the molar ratio (M H / M CO ) of the molar number M CO of carbon monoxide contained in the first gas obtained in the dry reforming step to the molar number M H of hydrogen. H [6] The useful hydrocarbon production method according to any one of [1] to [5] above further includes an adjustment step of adjusting the molar ratio (M H / M CO ) of the molar number M CO of carbon monoxide contained in the first gas obtained in the dry reforming step to the molar number M H of hydrogen. H [6] The useful hydrocarbon production method according to any one of [1] to [5] above further includes an adjustment step of adjusting the molar ratio (M H / M CO ) of the molar number M CO of carbon monoxide contained in the first gas obtained in the dry reforming step to the molar number M H of hydrogen. CO ) of the molar number M CO of carbon monoxide contained in the first gas obtained in the dry reforming step to the molar number M H of hydrogen. [7] The useful hydrocarbon production method according to any one of [1] to [6] above further includes a combustion step of separating a substance containing carbon atoms from the second gas and burning the substance containing carbon atoms to generate carbon dioxide, and the recycling step supplies the carbon dioxide-containing gas and the carbon dioxide generated in the combustion step to the dry reforming step. [8] The useful hydrocarbon is at least one hydrocarbon selected from the group consisting of olefins, aromatic hydrocarbons, gasoline, liquefied petroleum gas, and liquid hydrocarbons, for the useful hydrocarbon production method according to any one of [1] to [7] above. [9] The method for producing a useful hydrocarbon according to any one of [1] to [8] above, wherein the useful hydrocarbon is liquefied petroleum gas.

[10] The method for producing a useful hydrocarbon according to any one of [1] to [8] above, wherein the useful hydrocarbon is liquefied petroleum gas and the carbon dioxide-containing gas contains hydrocarbons other than those having 3 to 4 carbon atoms.

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

[14] The method for producing a useful hydrocarbon according to any one of [1] to [8] above, wherein the useful hydrocarbon is 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 useful hydrocarbon production apparatus comprising: a dry reforming unit that generates a first gas containing carbon monoxide and hydrogen from a mixed gas containing a methane-containing hydrocarbon and carbon dioxide; a useful hydrocarbon generation unit that is supplied with the first gas generated by the dry reforming unit and generates a second gas containing a useful hydrocarbon from carbon monoxide and hydrogen in the first gas; and a recycling unit that separates a carbon dioxide-containing gas from the second gas generated by the useful hydrocarbon generation unit and supplies the separated gas to the dry reforming unit.

[16] A dry reforming step of producing a first gas containing carbon monoxide and hydrogen from a gas in which methane / carbon dioxide is 1 or more and 9 or less in molar conversion, a useful hydrocarbon production step of producing a second gas containing useful hydrocarbons 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 it to the dry reforming step. A method for producing useful hydrocarbons having

Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a method for producing useful hydrocarbons and a device for producing useful hydrocarbons that can be efficiently produced over a long period of time using methane-containing hydrocarbons and carbon dioxide, which are easily obtainable raw materials.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Mode for Carrying Out the Invention

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

[0012] The present inventors focused on dry reforming that can easily obtain methane-containing hydrocarbons and carbon dioxide, and can generate carbon monoxide and hydrogen from methane-containing hydrocarbons and carbon dioxide. Dry reforming produces carbon monoxide and hydrogen (synthesis gas) from methane-containing hydrocarbons and carbon dioxide in the same ratio (carbon basis). However, in dry reforming under conditions where the methane-containing hydrocarbon is more than a predetermined amount (under conditions where carbon dioxide is insufficient), the deterioration reaction (coking) of the catalyst used in the reaction is remarkable, and the catalyst needs to be replaced in a short period of time. In the worst case, concerns such as blockage of the reaction apparatus may occur, and the efficiency and safety may be impaired.

[0013] Further, the present inventors have found that when a gas (second gas) containing useful hydrocarbons is produced from carbon monoxide and hydrogen by a useful hydrocarbon production step performed after the dry reforming step, carbon dioxide, which is an unreacted substance or by-product in the dry reforming step and the useful hydrocarbon production step, is contained in the second gas. Then, the present inventors have found that by supplying carbon dioxide, which is an impurity contained in the second gas, to the dry reforming step for reuse, the deterioration reaction of the catalyst during the dry reforming step can be suppressed, and useful hydrocarbons can be efficiently produced over a long period of time. The present disclosure is based on such findings.

[0014] The method for producing useful hydrocarbons according to 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 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 according to the embodiment includes a dry reforming unit 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 unit that is supplied with the first gas produced by the dry reforming unit and produces a second gas containing useful hydrocarbons from carbon monoxide and hydrogen in the first gas, and a recycling unit that separates a carbon dioxide-containing gas from the second gas produced by the useful hydrocarbon production unit and supplies it to the dry reforming unit.

[0016] [Method for Producing Useful Hydrocarbons] First, the method for producing useful hydrocarbons according to the embodiment will be described. FIG. 1 is a block diagram showing an example of the method for producing useful hydrocarbons according to the 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 generated from a mixed gas containing methane-containing hydrocarbon and carbon dioxide. The methane-containing hydrocarbon supplied to the dry reforming step S10 is composed of methane and hydrocarbons other than methane. The hydrocarbons other than methane contained in the methane-containing hydrocarbon are not particularly limited, and are, for example, pure substances of hydrocarbons having 2 to 10 carbon atoms or mixtures thereof, preferably hydrocarbons having 2 to 6 carbon atoms, and preferably ethane. At this time, 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 methane-containing hydrocarbon as described above is supplied to the dry reforming step S10, the yield of useful hydrocarbons is improved.

[0019] Further, the hydrocarbons contained in the methane-containing hydrocarbon may contain a small amount of the target useful hydrocarbons, and the amount thereof may be less than the amount of the target useful hydrocarbons produced contained in the second gas.

[0020] In the dry reforming step S10, for example, as shown in the following formula (1), carbon monoxide and hydrogen are synthesized from methane and carbon dioxide contained in the mixed gas by dry reforming. Further, since the hydrocarbon used as the raw material for dry reforming is not limited to methane, when the formula (1) is generalized for saturated hydrocarbons, for example, the following formula (2) is obtained. At this time, the carbon and carbon dioxide contained in the raw material hydrocarbon react in the same amount.

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

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

[0023] The dry reforming catalyst is not particularly limited. For example, from the viewpoint of showing catalytic activity over a long period of time and generating carbon monoxide and hydrogen, the dry reforming catalyst includes a porous structure carrier composed of a zeolite-type compound and at least one catalyst substance inherent in the carrier. The carrier has passages communicating with each other, and the ratio of the long side dimension L to the thickness dimension d in the carrier (L / d ratio) is 5.0 or more, and it is preferable that the catalyst substance is a catalyst structure present in at least the passages of the carrier.

[0024] For 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. Also, when the L / d ratio is 35.0 or less, the production yield of the catalyst structure can be improved.

[0025] Further, 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 increases sufficiently, and as the average particle size becomes smaller, the catalytic activity can be improved. Also, from the viewpoint of achieving both high catalytic activity and anti-coking property, the average particle size of the catalyst substance is preferably 9.00 nm or less, and more preferably 4.50 nm or less.

[0026] In addition, for the dry reforming catalyst, any catalyst known as a dry reforming catalyst 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., it contains at least one selected from Ir, Ru, Rh, Pt, Pd, Ni, Co, Fe, which are metal species active in dry reforming, and the carrier can also use a carrier containing at least one selected from MgO, Al2O3, SiO2, CeO2, CaO, ZrO2, TiO2, La2O3, ZnO, silicalite-1, MCM-41, SBA-15. However, the dry reforming catalyst is not particularly limited to these.

[0027] The heating temperature of the dry reforming catalyst is appropriately set according to the type of the 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, regarding the heating temperature of the dry reforming catalyst, the lower limit value is preferably 400 °C or higher, more preferably 600 °C or higher, and the upper limit value 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. The first gas contains, in addition to carbon monoxide and hydrogen (synthesis gas), hydrocarbons and carbon dioxide that are unreacted substances, water that is a by-product, and the like.

[0029] The content ratio of carbon monoxide and hydrogen contained in the first gas can be appropriately adjusted according to the conditions of dry reforming, such as the heating temperature of the dry reforming catalyst, the supply amount of the mixed gas, and the content ratio of methane-containing hydrocarbons and carbon dioxide contained in the mixed gas.

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

[0031] CO + 2H2 → hydrocarbon ··· Formula (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 contains hydrocarbons, carbon dioxide, carbon monoxide, hydrogen, which are unreacted substances in the dry reforming step S10 and the useful hydrocarbon production step S20, water which is a by-product 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) to (2), in the dry reforming step S10, carbon monoxide and hydrogen are produced from methane-containing hydrocarbons and carbon dioxide at the same ratio (carbon basis) (1:1 in terms of carbon molar ratio). 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 tends to occur. As a result, the activity of the dry reforming catalyst decreases, and the production amount of useful hydrocarbons decreases.

[0035] Therefore, in the recycling step S30, by supplying a carbon dioxide-containing gas (so-called off-gas) containing carbon dioxide, which is an impurity in the second gas generated in the useful hydrocarbon production step S20, to the dry reforming step S10, it is possible to suppress coking of the dry reforming catalyst due to a decrease in the ratio of carbon dioxide to methane-containing hydrocarbons, and thus suppress a decrease in the activity of the dry reforming catalyst. Therefore, useful hydrocarbons can be efficiently produced over a long period of time. In addition, 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. When the carbon dioxide-containing gas contains hydrocarbons other than useful hydrocarbons, the yield of useful hydrocarbons is further improved.

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

[0037] As described above, in addition to being a renewable energy resource, biogas is easily available compared with natural resources such as natural gas. Therefore, when biogas is used as a raw material for the method for producing useful hydrocarbons, the raw materials can be stably obtained without a shortage of raw materials.

[0038] On the one hand, the proportion of carbon dioxide in the total of methane-containing hydrocarbons and carbon dioxide contained in biogas is often about 40%, and methane-containing hydrocarbons are contained more than carbon dioxide. Thus, biogas contains more methane-containing hydrocarbons than carbon dioxide. Therefore, when biogas is supplied to the dry reforming step S10, carbon dioxide is insufficient, and a part of the methane-containing hydrocarbons is not utilized. As a result, the production amount of the synthesis gas obtained in the dry reforming step S10 decreases. Further, since biogas contains more methane-containing hydrocarbons than carbon dioxide, as described above, coking of the dry reforming catalyst is likely to occur, and as a result, the activity of the dry reforming catalyst decreases, and the production amount of useful hydrocarbons decreases.

[0039] In response to such concerns, in the recycling step S30, since the carbon dioxide-containing gas which is off-gas is supplied to the dry reforming step S10, it is possible to compensate for the excessive shortage of carbon dioxide in biogas. Thus, even when biogas is used as a raw material, the recycling step S30 can suppress the shortage of carbon dioxide derived from biogas in the dry reforming step S10, so that the dry reforming step S10 can be stably performed over a long period. Further, since coking of the dry reforming catalyst due to a decrease in the ratio of carbon dioxide to methane-containing hydrocarbons can be suppressed, a decrease in the activity of the dry reforming catalyst can be suppressed. Therefore, useful hydrocarbons can be efficiently produced over a long period.

[0040] Further, the recycling step S30 is the ratio (M CO2 of the total carbon molar number M of carbon dioxide in the mixed gas supplied to the dry reforming step S10 and carbon dioxide in the carbon dioxide-containing gas to the total carbon molar number M HC of the hydrocarbons supplied to the dry reforming step S10 (M HC / M CO2Preferably, the supply amount of the carbon dioxide-containing gas supplied to the dry reforming step S10 is adjusted according to []. The hydrocarbon supplied to the dry reforming step S10 is the hydrocarbon contained in the methane-containing hydrocarbon in the mixed gas and the carbon dioxide-containing gas.

[0041] In the dry reforming step S10, under the condition that the methane-containing hydrocarbon is more than a predetermined amount, coking of the dry reforming catalyst and carbon dioxide deficiency may occur. Therefore, in the recycling step S30, when the above ratio (M HC / M CO2 ) is very large, increasing the supply amount of the carbon dioxide-containing gas supplied to the dry reforming step S10 can suppress coking generation and carbon dioxide deficiency in the dry reforming step S10. Thus, by adjusting the supply amount of the carbon dioxide-containing gas supplied to the dry reforming step S10 according to the above ratio (M HC / M CO2 ) in the dry reforming step S10, coking generation and carbon dioxide deficiency in the dry reforming step S10 can be further suppressed.

[0042] In addition, biogas is generated from various types of organic waste. Therefore, the ratio of methane-containing hydrocarbon to carbon dioxide contained in biogas varies depending on the type of organic waste. Even when biogas is supplied to the dry reforming step S10, the supply amount of the carbon dioxide-containing gas supplied to the dry reforming step S10 is adjusted according to the above ratio (M HC / M CO2 ) in the dry reforming step S10 by the recycling step S30. Therefore, even if the content ratio of methane-containing hydrocarbon to carbon dioxide in biogas is different, coking generation and carbon dioxide deficiency in the dry reforming step S10 can be further suppressed.

[0043] Adjust the supply amount of the carbon dioxide-containing gas supplied to the dry reforming step S10 so that the above ratio (M HC / M CO2 ) in the dry reforming step S10 is preferably controlled to 1.30 or less, more preferably 1.00 or less, and the above effect can be further improved.

[0044] In addition, the CO2 concentration of the carbon dioxide-containing gas supplied to the dry reforming step S10 by the recycling 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, by adjusting the supply amount of the recycled gas in the recycling step S30, the occurrence of coking and carbon dioxide shortage in the dry reforming step S10 can be sufficiently suppressed.

[0045] In addition, the method for producing useful hydrocarbons according to the embodiment may further include a mixed gas generation step (not shown). The mixed gas generation step generates a mixed gas containing methane-containing hydrocarbons and carbon dioxide and supplies it to the dry reforming step S10. The mixed gas generation step preferably performs a thermal decomposition treatment using biomass resources such as lignocellulosic biomass and waste plastics as raw materials, or a gasification treatment in which these raw materials are oxidatively decomposed by adding an oxidizing agent (H2O, oxygen, carbon dioxide).

[0046] In the thermal decomposition treatment and gasification treatment, a gas containing at least carbon monoxide and hydrogen is generated, but hydrocarbons and carbon dioxide are also generated as impurities. These hydrocarbons and carbon dioxide can be supplied from the mixed gas generation step to the dry reforming step S10.

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

[0048] Depending on the types of raw materials for pyrolysis treatment or gasification treatment, their mixing ratios, reaction temperature, and other conditions, the carbon ratio of hydrocarbons and carbon dioxide changes.

[0049] When the amount of hydrocarbon is more than the specified amount (carbon dioxide is insufficient) in the dry reforming step S10, in the recycling step S30, by supplying a carbon dioxide-containing gas containing carbon dioxide, which is an impurity in the second gas generated in the useful hydrocarbon generation step S20, to the dry reforming step S10, coking of the dry reforming catalyst caused by a decrease in the ratio of carbon dioxide to hydrocarbon can be suppressed. Therefore, a decrease in the activity of the dry reforming catalyst can be suppressed. As a result, the target useful hydrocarbon can be efficiently produced over a long period. Also, since the carbon dioxide discharged from the useful hydrocarbon generation step S20 is reused as a raw material for the dry reforming step S10, global warming can be suppressed.

[0050] In addition, trace amounts of sulfur and halogen may be mixed as impurities in the gas generated by pyrolysis treatment or gasification treatment. Since these become poisoning substances for 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, they may impair the catalyst performance and at the same time cause damage to the apparatus. Therefore, a desulfurization step, a dehalogenation step, etc. can be appropriately provided as a pretreatment step for the above-mentioned generated gas between the mixed gas generation step and the dry reforming step S10.

[0051] Moreover, the method for producing useful hydrocarbons according to the embodiment preferably further includes a hydrogen supply step S40 that separates hydrogen from the second gas generated in the useful hydrocarbon generation step S20 and supplies it to the useful hydrocarbon generation step S20.

[0052] As shown in the above formula (3), in the useful hydrocarbon production step S20, hydrogen in an amount twice that of carbon monoxide is required. On the other hand, the ratio of carbon monoxide to hydrogen in the first gas generated in the dry reforming step S10 is the same as shown in the above formulas (1) and (2). Thus, in the dry reforming step S10, carbon monoxide and hydrogen are generated in the same ratio, and in the useful hydrocarbon production step S20, hydrogen in an amount twice that of carbon monoxide is required. Therefore, if the useful hydrocarbon production step S20 is carried out for a long period, a shortage of hydrogen will occur. As a result, excess carbon monoxide will remain, and the production amount of useful hydrocarbons obtained in the useful hydrocarbon production step S20 will decrease.

[0053] Therefore, in the hydrogen supply step S40, by supplying hydrogen (so-called off-gas), which is an impurity in the second gas generated in the useful hydrocarbon production step S20, to the useful hydrocarbon production step S20, it is possible to compensate for the insufficient amount of hydrogen, which is a raw material for the useful hydrocarbon production step S20. Thus, since the hydrogen supply step S40 can suppress the shortage of hydrogen caused by the long-term useful hydrocarbon production step S20, the useful hydrocarbon production step S20 can be stably carried out over a long period. Therefore, useful hydrocarbons that are easy to store and transport can be efficiently produced over a long period. In addition, 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 load can be reduced.

[0054] Further, the hydrogen supply step S40 preferably adjusts the supply amount of hydrogen supplied to the useful hydrocarbon production step S20 according to the number of moles M of hydrogen in the useful hydrocarbon production step S20 H and more preferably adjusts the supply amount of hydrogen supplied to the useful hydrocarbon production step S20 according to the above number of moles M H and the type and reaction of the useful hydrocarbon to be produced.

[0055] For example, when producing liquefied petroleum gas as the useful hydrocarbon, the number of moles M of hydrogen in the useful hydrocarbon production step S20 HWhen there is a large amount, the useful hydrocarbon synthesis reaction proceeds well. On the other hand, the number of moles M of hydrogen in the useful hydrocarbon production step S20 H When there is a small amount, there is a possibility of hydrogen shortage in the useful hydrocarbon synthesis reaction. Therefore, in the hydrogen supply step S40, when the number of moles M of hydrogen in the useful hydrocarbon production step S20 H is small, increasing the supply amount of hydrogen supplied to the useful hydrocarbon production step S20 can suppress the hydrogen shortage in the useful hydrocarbon production step S20.

[0056] Thus, in the hydrogen supply step S40, when the number of moles M of hydrogen in the useful hydrocarbon production step S20 H is small, increasing the supply amount of hydrogen supplied to the useful hydrocarbon production step S20, that is, according to the number of moles M of hydrogen in the useful hydrocarbon production step S20 H By adjusting the supply amount of hydrogen supplied to the useful hydrocarbon production step S20 accordingly, the target useful hydrocarbon can be produced more efficiently.

[0057] Also, the hydrogen supply step S40 preferably adjusts the supply amount of hydrogen supplied to the useful hydrocarbon production step S20 according to the molar ratio (M CO of hydrogen to carbon monoxide in the useful hydrocarbon production step S20 H / M H / M CO ).

[0058] Regarding the molar ratio (M H / M CO ) in the useful hydrocarbon production step S20, if the ratio of hydrogen to carbon monoxide is very small, there is a possibility of hydrogen shortage. Therefore, in the hydrogen supply step S40, when the molar ratio (M H / M CO ) in the useful hydrocarbon production step S20 is very small, increasing the supply amount of hydrogen supplied to the useful hydrocarbon production step S20 can suppress the hydrogen shortage in the useful hydrocarbon production step S20. Thus, regarding the molar ratio (M H / M COBy adjusting the supply amount of hydrogen supplied to the useful hydrocarbon production step S20 according to (0), it is possible to more reliably suppress hydrogen shortage in the useful hydrocarbon production step S20.

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

[0060] The adjustment step adjusts the molar ratio (M H / M CO ) in the first gas obtained in the dry reforming step S10. The adjustment step is performed before the dry reforming step S10 and preferably adjusts the molar ratio (M H / M CO ) in the first gas. In the adjustment step, the molar ratio (M H / M CO ) in the first gas is adjusted according to the conditions of the reaction for producing useful hydrocarbons carried out in the useful hydrocarbon production step S20.

[0061] When the first gas in which the molar ratio (M H / M CO ) is adjusted by the adjustment step is supplied to the useful hydrocarbon production step S20, hydrogen shortage due to the long-term useful hydrocarbon production step S20 can be suppressed, so that the useful hydrocarbon production step S20 can be stably performed over a long period. Therefore, the target useful hydrocarbons can be efficiently produced over a long period.

[0062] Further, the method for producing useful hydrocarbons according to the embodiment may further include a combustion step (not shown) for separating a substance containing carbon atoms from the second gas and burning the substance containing carbon atoms to generate carbon dioxide. In this case, the recycling step S30 supplies the carbon dioxide-containing gas and the carbon dioxide generated in the combustion step to the dry reforming step S10.

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

[0064] The substance containing carbon atoms to be combusted in the combustion step contains at least one substance selected from the group consisting of methane, carbon monoxide, methanol, dimethyl ether, and hydrocarbons other than the target useful hydrocarbon. Note that the substance containing carbon atoms to be combusted in the combustion step may or may not contain carbon dioxide.

[0065] The recycling step S30 supplies the carbon dioxide generated in the combustion step, in addition to the carbon dioxide-containing gas separated from the second gas generated in the useful hydrocarbon production step S20, 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, since coking generation and carbon dioxide shortage due to the dry reforming step S10 can be further suppressed, the target useful hydrocarbon can be efficiently produced over a long period. 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] Further, it is preferable to adjust the combustion rate of the combustion step according to the ratio of the lower hydrocarbon to carbon dioxide in the hydrocarbon supplied to the dry reforming step S10. The combustion rate of the combustion step is the ratio of converting the hydrocarbon excluding the target useful hydrocarbon component in the second gas into carbon dioxide by combustion, 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 the hydrocarbons excluding the target useful hydrocarbon component in the second gas to generate carbon dioxide.

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

[0068] Combustion rate (%) = 100 - (total amount of hydrocarbons excluding the target useful hydrocarbon component burned in the combustion step (C-mol) × 100 / total amount of hydrocarbons excluding the target useful hydrocarbon component in the second gas (C-mol))

[0069] Thus, by changing the combustion rate of the combustion step, the amount of carbon dioxide generated in the combustion step can be adjusted. Therefore, according to the ratio of the lower hydrocarbon to carbon dioxide supplied to the dry reforming step S10, the combustion rate of the combustion step is adjusted to adjust the amount of carbon dioxide generated, and the amount of carbon dioxide supplied to the dry reforming step S10 in the recycling step S30 can be adjusted, so that the production amount of the target useful hydrocarbon can be increased.

[0070] For example, when manufacturing liquefied petroleum gas in the useful hydrocarbon production step S20, if the combustion rate of the combustion step is 3% or more, the carbon dioxide shortage in the dry reforming step S10 can be sufficiently suppressed. Also, if the combustion rate of the combustion step is 50% or less, the ratio of the lower hydrocarbon to carbon dioxide supplied to the dry reforming step S10 is good. Therefore, when the combustion rate of the combustion step is 3% or more and 50% or less, useful hydrocarbons can be efficiently produced over a long period.

[0071] In addition, when the method for producing useful hydrocarbons according to the embodiment supplies biogas to the dry reforming step S10, it may have 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. By desulfurizing the biogas in the desulfurization step, it is possible to suppress the reduction in the catalytic performance of the dry reforming catalyst and the useful hydrocarbon production catalyst. Therefore, the target useful hydrocarbons can be stably produced over a long period of time.

[0072] In addition, the method for producing useful hydrocarbons according to the embodiment may have a dehydration step (not shown) for dehydrating the first gas generated in the dry reforming step S10. The dehydration step is performed 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 performed in the useful hydrocarbon production step S20 can be improved, and furthermore, the reduction in the catalytic performance of the useful hydrocarbon production catalyst due to moisture can be suppressed.

[0073] In addition, the method for producing useful hydrocarbons according to the embodiment may have a compression step (not shown) for compressing the first gas generated in the dry reforming step S10. The compression step is performed 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, so the efficiency of the synthesis reaction of useful hydrocarbons performed in the useful hydrocarbon production step S20 can be improved.

[0074] In addition, 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] As the olefins, ethylene and propylene are preferable. As the aromatic hydrocarbons, benzene, toluene, and xylene are preferable. As the gasoline, hydrocarbons having 5 to 12 carbon atoms are preferable. As the liquefied petroleum gas, hydrocarbons having 3 to 4 carbon atoms are preferable. As the liquid hydrocarbons, naphtha, kerosene, jet fuel, light oil, and heavy oil, which are hydrocarbons having 5 or more carbon atoms, are preferable.

[0076] In the method for producing useful hydrocarbons, depending on the type of useful hydrocarbons to be produced, under appropriate catalysts and reaction conditions in the useful hydrocarbon production step S20, various useful hydrocarbon synthesis reactions can be used to synthesize a hydrocarbon mixture mainly composed of the target various useful hydrocarbons from carbon monoxide and hydrogen.

[0077] For example, when producing olefins as useful hydrocarbons, in the useful hydrocarbon production step S20, a useful hydrocarbon production catalyst (olefin production catalyst) for synthesizing olefins from carbon monoxide and hydrogen contained in the first gas is used to perform an olefin synthesis reaction. In the useful hydrocarbon production step S20, while supplying the first gas to the olefin production catalyst, by heating the olefin production catalyst, carbon monoxide and hydrogen in the supplied first gas react with the olefin production catalyst to generate a second gas containing olefins.

[0078] From the viewpoint of increasing the production amount of olefins, the olefin production catalyst is preferably a catalyst containing a methanol synthesis catalyst substance and a ZSM-5 type zeolite catalyst substance.

[0079] For such a catalyst, the ZSM-5 type zeolite catalyst material preferably contains P (phosphorus). When the ZSM-5 type zeolite catalyst material contains P, the acid strength of the ZSM-5 type zeolite catalyst material can be appropriately controlled, so that excessive growth of hydrocarbon chains can be suppressed and the production amount of olefins such as ethylene and propylene can be increased.

[0080] Also, for such a catalyst, 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 type zeolite catalyst material is preferably 20 or more and 60 or less. By replacing a part of the silicon atoms in the silicate constituting the zeolite framework of the ZSM-5 type zeolite catalyst material with aluminum atoms, the aluminum atoms become acid sites, so that the zeolite catalyst material exhibits the function as a solid acid. When the above ratio is 60 or less, the acid sites of the ZSM-5 type zeolite catalyst material increase, so that the production amount of olefins can be increased. Also, when the above ratio is 20 or more, catalyst deterioration such as coking caused by excessive acid sites can be suppressed.

[0081] The heating temperature of the catalyst for olefin production is appropriately set according to the type of the catalyst for olefin production, the supply amount of the first gas, etc. For example, the heating temperature of the catalyst for olefin production is 240°C or more and 350°C or less.

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

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

[0084] The content ratio of olefins contained in the second gas can be appropriately adjusted according to the conditions of the olefin synthesis reaction such as the heating temperature of the catalyst for olefin production and the supply amount of the first gas.

[0085] When the useful hydrocarbon is an olefin, it is preferable that the carbon dioxide-containing gas contains at least one of hydrocarbons other than the target olefins and carbon monoxide. When the carbon dioxide-containing gas contains the above substances, the yield of olefins is significantly improved.

[0086] Further, for example, when producing aromatic hydrocarbons as useful hydrocarbons, in the useful hydrocarbon production step S20, a useful hydrocarbon production catalyst (aromatic hydrocarbon production catalyst) for synthesizing aromatic hydrocarbons from carbon monoxide and hydrogen contained in the first gas is used to carry out an aromatic hydrocarbon synthesis reaction. In the useful hydrocarbon production step S20, while supplying the first gas to the aromatic hydrocarbon production catalyst, the aromatic hydrocarbon production catalyst is heated, so that carbon monoxide and hydrogen in the supplied first gas react with the aromatic hydrocarbon production catalyst to generate a second gas containing aromatic hydrocarbons.

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

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

[0089] Also, for such a catalyst, 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 type zeolite catalyst material is preferably 20 or more and 60 or less. By replacing a part of the silicon atoms in the silicate constituting the zeolite framework of the ZSM-5 type zeolite catalyst material with aluminum atoms, the aluminum atoms become acid sites, so the zeolite catalyst material exhibits the function as a solid acid. When the above ratio is 60 or less, the acid sites of the ZSM-5 type zeolite catalyst material increase, so the production amount of aromatic hydrocarbons can be increased. Also, when the above ratio is 20 or more, catalyst deterioration such as coking caused by too many acid sites can be suppressed.

[0090] The heating temperature of the catalyst for producing aromatic hydrocarbons is appropriately set according to the type of the catalyst for producing aromatic hydrocarbons, the supply amount of the first gas, etc. For example, the heating temperature of the catalyst for producing aromatic hydrocarbons is 300°C or more and 600°C or less.

[0091] The pressure of 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 generated in the useful hydrocarbon production step S20 contains at least aromatic hydrocarbons which are useful hydrocarbons. In addition to aromatic hydrocarbons, the second gas contains hydrocarbons, carbon dioxide, carbon monoxide, hydrogen which are unreacted substances in the dry reforming step S10 and the useful hydrocarbon production step S20, methanol and dimethyl ether which are by-products of these steps, and hydrocarbons other than aromatic hydrocarbons which are useful hydrocarbons.

[0093] The content ratio of the aromatic hydrocarbons contained in the second gas can be appropriately adjusted according to the conditions of the aromatic hydrocarbon synthesis reaction such as the heating temperature of the catalyst for aromatic hydrocarbon production and the supply amount of the first gas.

[0094] When the useful hydrocarbon is an aromatic hydrocarbon, it is preferable that the carbon dioxide-containing gas contains at least one of hydrocarbons other than the target aromatic hydrocarbon and carbon monoxide. When the carbon dioxide-containing gas contains the above substances, the yield of the aromatic hydrocarbon is significantly improved.

[0095] Also, for example, when producing gasoline as the useful hydrocarbon, in the useful hydrocarbon production step S20, a useful hydrocarbon production catalyst (gasoline production catalyst) for synthesizing gasoline from carbon monoxide and hydrogen contained in the first gas is used to perform a gasoline synthesis reaction. In the useful hydrocarbon production step S20, while supplying the first gas to the gasoline production catalyst, by heating the gasoline production catalyst, carbon monoxide and hydrogen in the supplied first gas react with the gasoline production catalyst to generate a second gas containing gasoline.

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

[0097] In addition, for such a catalyst, 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 type zeolite catalyst substance is preferably at least 12. Further, the ZSM-5 type zeolite catalyst substance preferably has a pore diameter formed by up to 12-membered rings, more preferably up to 10-membered rings. By replacing a part of the silicon atoms in the silicate constituting the zeolite framework of the ZSM-5 type zeolite catalyst substance with aluminum atoms, the aluminum atoms become acid sites, so that the zeolite catalyst substance exhibits the function as a solid acid. When it is the ZSM-5 type zeolite catalyst substance as described above, the production amount of gasoline can be increased. Such ZSM-5 type zeolite catalyst substances are, for example, ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35 and ZSM-38.

[0098] The heating temperature of the gasoline production catalyst is appropriately set according to the type of the gasoline production catalyst, the supply amount of the first gas, etc. For example, the heating temperature of the gasoline production 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 higher and 150 bar or lower.

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

[0101] The content ratio of gasoline contained in the second gas can be appropriately adjusted according to 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 substances, the yield of gasoline is significantly improved.

[0103] Also, for example, when producing liquefied petroleum gas as the useful hydrocarbon, in the useful hydrocarbon production step S20, 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 the liquefied petroleum gas synthesis reaction. In the useful hydrocarbon production step S20, while supplying the first gas to the LPG production catalyst, by heating the LPG production catalyst, carbon monoxide and hydrogen in the supplied first gas react with the LPG production catalyst to generate a second gas containing liquefied petroleum gas.

[0104] From the viewpoint of increasing the production amount of liquefied petroleum gas and increasing the content ratio of propane contained in the liquefied petroleum gas, the LPG production catalyst is preferably a catalyst containing a methanol synthesis catalyst substance and a ZSM-5 type zeolite catalyst substance.

[0105] Regarding such a catalyst, it is preferable to support Pt (platinum), or Pt and Pd (palladium) on the ZSM-5 type zeolite catalyst substance. When the ZSM-5 type zeolite catalyst substance supports Pt, or Pt and Pd, the production amount of liquefied petroleum gas and the content ratio of propane can be increased. Regarding the states of Pt and Pd supported on the ZSM-5 type zeolite catalyst substance, metallic Pt and metallic Pd may be mixed, Pt and Pd may be alloyed, or at least one of metallic Pt and Pd and an alloy of Pt and Pd may be mixed.

[0106] Also, regarding such a catalyst, it is preferable that the ZSM-5 type zeolite catalyst substance contains P. When the ZSM-5 type zeolite catalyst substance contains P, the acid strength of the ZSM-5 type zeolite catalyst substance can be appropriately controlled, so that the production amount of liquefied petroleum gas and the content ratio of propane can be increased.

[0107] Also, for such a catalyst, 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 type zeolite catalyst substance is preferably 20 or more and 60 or less. By replacing a part of the silicon atoms in the silicate constituting the zeolite framework of the ZSM-5 type zeolite catalyst substance with aluminum atoms, the aluminum atoms become acid sites, so that the zeolite catalyst substance exhibits the function as a solid acid. When the above ratio is 60 or less, the acid sites of the ZSM-5 type zeolite catalyst substance increase, so that the production amount of liquefied petroleum gas and the content ratio of propane can be increased. Also, when the above ratio is 20 or more, catalyst deterioration such as coking caused by too many acid sites can be suppressed.

[0108] The heating temperature of the catalyst for LPG production is appropriately set according to the type of the catalyst for LPG production, the supply amount of the first gas, etc. For example, the heating temperature of the catalyst for LPG production is 240 °C or more and 350 °C or less.

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

[0110] At this time, the second gas generated 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 contains hydrocarbons, carbon dioxide, carbon monoxide, hydrogen which are unreacted substances in the dry reforming step S10 and the useful hydrocarbon production step S20, methanol, dimethyl ether which are by-products of these steps, hydrocarbons having 1 or more and 2 or less carbon atoms, hydrocarbons having 5 or more carbon atoms, etc.

[0111] The content ratio of the liquefied petroleum gas contained in the second gas can be appropriately adjusted according to the conditions of the liquefied petroleum gas synthesis reaction such as the heating temperature of the catalyst for LPG production 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 having 3 to 4 carbon atoms, more preferably contains at least one of hydrocarbons having 1 to 2 carbon atoms and carbon monoxide, and even more preferably contains ethane. When the carbon dioxide-containing gas contains the above substances, the yield of liquefied petroleum gas is significantly improved.

[0113] Also, for example, when producing a liquid hydrocarbon as the useful hydrocarbon, in the useful hydrocarbon production step S20, a useful hydrocarbon production catalyst (liquid hydrocarbon production catalyst) for synthesizing a liquid hydrocarbon from carbon monoxide and hydrogen contained in the first gas is used to perform a liquid hydrocarbon synthesis reaction. In the useful hydrocarbon production step S20, while supplying the first gas to the liquid hydrocarbon production catalyst, by heating the liquid hydrocarbon production catalyst, carbon monoxide and hydrogen in the supplied first gas react with the liquid hydrocarbon production catalyst to generate a second gas containing a liquid hydrocarbon.

[0114] From the viewpoint of increasing the production amount of the liquid hydrocarbon, the liquid hydrocarbon production catalyst is preferably a Fischer-Tropsch (FT) synthesis catalyst.

[0115] As the FT synthesis catalyst, it is preferable to support at least one or more metals having activity for the FT reaction on a carrier. The carrier is preferably Al2O3 or SiO2. Also, the metal having activity for the FT reaction is preferably Ru, Co, Fe, or Ni, and more preferably Ru or Co. When the above 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 above 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] Also, the FT synthesis catalyst may be a catalyst structure exemplified as a preferred example of the dry reforming catalyst, and may be one in which Co is included inside.

[0117] The heating temperature of the catalyst for liquid hydrocarbon production is appropriately set according to the type of the catalyst for liquid hydrocarbon production, the supply amount of the first gas, and the like. For example, the heating temperature of the catalyst for liquid hydrocarbon production 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] Regarding the pressure of the liquid hydrocarbon synthesis reaction, it is preferably 0.5 MPa or higher and 10.0 MPa or lower, more preferably 0.7 MPa or higher and 7.0 MPa or lower, and still more preferably 0.8 MPa or lower and 5.0 MPa or lower.

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

[0120] The content ratio of the liquid hydrocarbon contained in the second gas can be appropriately adjusted according to the conditions of the liquid hydrocarbon synthesis reaction such as the heating temperature of the catalyst for liquid hydrocarbon production and the supply amount of the first gas.

[0121] When the useful hydrocarbon is a liquid hydrocarbon, it is preferable that the carbon dioxide-containing gas contains at least one of hydrocarbons having 4 or less carbon atoms and carbon monoxide. When the carbon dioxide-containing gas contains the above substances, the yield of the liquid hydrocarbon is significantly improved.

[0122] [Apparatus for producing useful hydrocarbon] Next, the apparatus for producing useful hydrocarbon according to the embodiment will be described. FIG. 2 is a schematic diagram showing an example of the apparatus for producing useful hydrocarbon according to the embodiment. The apparatus 1 for producing useful hydrocarbon according to the embodiment is an apparatus for performing the method for producing useful hydrocarbon according to the above embodiment.

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

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

[0125] When the mixed gas is supplied to the dry reforming unit 2 equipped with the dry reforming catalyst in a heated state, the dry reforming unit 2 causes the methane-containing hydrocarbon and carbon dioxide in the mixed gas to react by the dry reforming catalyst to generate a first gas containing carbon monoxide and hydrogen. In this way, dry reforming is performed on the mixed gas in the dry reforming unit 2.

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

[0127] When the first gas is supplied to the useful hydrocarbon generation unit 3 equipped with the useful hydrocarbon generation catalyst in a heated state, the useful hydrocarbon generation unit 3 causes the carbon monoxide and hydrogen in the first gas to react by the useful hydrocarbon generation catalyst to generate a second gas containing the target useful hydrocarbon. In this way, a useful hydrocarbon synthesis reaction is performed on the first gas in the useful hydrocarbon generation unit 3.

[0128] The recycling unit 4 that constitutes the useful hydrocarbon production apparatus 1 separates a carbon dioxide-containing gas from the second gas generated by the useful hydrocarbon generation unit 3 and supplies the carbon dioxide-containing gas to the dry reforming unit 2. When the carbon dioxide-containing gas separated from the second gas discharged from the useful hydrocarbon generation unit 3 is supplied to the dry reforming unit 2 by the recycling unit 4, the occurrence of coking and carbon dioxide deficiency in the dry reforming unit 2 can be suppressed. Therefore, the target useful hydrocarbon can be efficiently produced over a long period of time.

[0129] Further, the recycling unit 4 is the total carbon molar number M of carbon dioxide in the mixed gas supplied to the dry reforming unit 2 and carbon dioxide in the carbon dioxide-containing gas CO2 with respect to the total carbon molar number M of hydrocarbons supplied to the dry reforming unit 2 HC of the ratio (M HC / M CO2 ), it is preferable to adjust the supply amount of the carbon dioxide-containing gas supplied to the dry reforming unit 2. The hydrocarbons supplied to the dry reforming unit 2 are methane-containing hydrocarbons in the mixed gas and hydrocarbons contained in the carbon dioxide-containing gas.

[0130] When the carbon molar ratio (M HC / M CO2 ) in the dry reforming unit 2 is large, there is a possibility of coking and carbon dioxide deficiency occurring in the dry reforming unit 2. Therefore, when the carbon molar ratio (M HC / M CO2 ) in the dry reforming unit 2 is large, if the recycling unit 4 increases the supply amount of the carbon dioxide-containing gas supplied to the dry reforming unit 2, the occurrence of coking and carbon dioxide deficiency in the dry reforming unit 2 can be suppressed.

[0131] Thus, the carbon molar ratio (M HC / M CO2When it is large, the supply amount of the carbon dioxide-containing gas supplied from the recycling unit 4 to the dry reforming unit 2 is increased. For example, according to the carbon molar ratio (M HC / M CO2 ) in the dry reforming unit 2, by adjusting the supply amount of the carbon dioxide-containing gas supplied from the recycling unit 4 to the dry reforming unit 2, the target useful hydrocarbon can be produced more efficiently. By adjusting the supply amount of the carbon dioxide-containing gas supplied to the dry reforming unit 2 to control the above ratio (M HC / M CO2 ) in the dry reforming unit 2 to preferably 1.30 or less, more preferably 1.00 or less, the above effect can be further improved.

[0132] Also, the CO2 concentration of the carbon dioxide-containing gas supplied from the recycling unit 4 to the dry reforming unit 2 is preferably 50% or more, more preferably 60% or more, and still more preferably 70% or more. When the CO2 concentration of the carbon dioxide-containing gas is 50% or more, by adjusting the supply amount of the recycled gas in the recycling unit 4, coking generation and carbon dioxide shortage in the dry reforming unit 2 can be sufficiently suppressed.

[0133] Moreover, 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 hydrocarbon and carbon dioxide and supplies it to the dry reforming unit 2. The mixed gas generation unit preferably performs pyrolysis treatment using biomass resources such as woody biomass and waste plastics as raw materials, or gasification treatment in which these raw materials are oxidatively decomposed by adding an oxidant (H2O, oxygen, carbon dioxide).

[0134] In the pyrolysis treatment and gasification treatment, a gas containing at least carbon monoxide and hydrogen is generated, but hydrocarbons and carbon dioxide are also generated as impurities. These hydrocarbons and carbon dioxide can be supplied from the mixed gas generation unit to the dry reforming unit 2.

[0135] At this time, the production apparatus 1 for useful hydrocarbons according to the embodiment may include a separation unit that separates carbon monoxide and hydrogen from a gas containing hydrocarbons and carbon dioxide between the mixed gas generation unit and the dry reforming unit 2.

[0136] In addition, trace amounts of sulfur and halogen may be mixed as impurities in the gas generated by the pyrolysis treatment or gasification treatment. Since these become poisoning substances for the dry reforming catalyst used in the dry reforming unit 2 and the useful hydrocarbon production catalyst used in the useful hydrocarbon production unit 3, they may impair the catalyst performance and at the same time cause damage to the apparatus. Therefore, a desulfurization step, a dehalogenation step, or the like can be appropriately provided as a pretreatment step for the above-mentioned generated gas between the mixed gas generation unit and the dry reforming unit 2.

[0137] Further, the production apparatus 1 for useful hydrocarbons according to the embodiment preferably further includes a hydrogen supply unit 5 that separates hydrogen from the second gas generated in the useful hydrocarbon production unit 3 and supplies it 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 hydrogen shortage in the useful hydrocarbon production unit 3 can be suppressed. Therefore, the target useful hydrocarbons can be efficiently produced over a long period of time. In addition, since the hydrogen discharged from the useful hydrocarbon production unit 3 is reused as a raw material for the useful hydrocarbon production unit 3, the environmental load can be reduced.

[0138] Further, the hydrogen supply unit 5 preferably adjusts the supply amount of hydrogen supplied to the useful hydrocarbon production unit 3 according to the number of moles M of hydrogen in the useful hydrocarbon production unit 3 H and it is more preferable to adjust the supply amount of hydrogen supplied to the useful hydrocarbon production unit 3 according to the number of moles M H and the type and reaction of the useful hydrocarbons to be produced.

[0139] For example, when producing liquefied petroleum gas as the useful hydrocarbon, the number of moles M of hydrogen in the useful hydrocarbon production unit 3 HIf there is a shortage, there is a possibility of hydrogen deficiency in the useful hydrocarbon production unit 3. Therefore, the number of moles of hydrogen M in the useful hydrocarbon production unit 3 H When there is a shortage, if the supply amount of hydrogen supplied by the hydrogen supply unit 5 to the useful hydrocarbon production unit 3 is increased, the hydrogen deficiency in the useful hydrocarbon production unit 3 can be suppressed.

[0140] In this way, when the number of moles of hydrogen M in the useful hydrocarbon production unit 3 H is small, by increasing the supply amount of hydrogen supplied by the hydrogen supply unit 5 to the useful hydrocarbon production unit 3, that is, according to the number of moles of hydrogen M H in the useful hydrocarbon production unit 3, by adjusting the supply amount of hydrogen supplied by the hydrogen supply unit 5 to the useful hydrocarbon production unit 3, the target useful hydrocarbon can be produced more efficiently.

[0141] Further, the hydrogen supply unit 5 adjusts the supply amount of hydrogen supplied to the useful hydrocarbon production unit 3 according to the molar ratio (M CO of hydrogen to carbon monoxide in the useful hydrocarbon production unit 3 H is preferably adjusted. H / M CO )

[0142] Regarding the molar ratio (M H / M CO ) in the useful hydrocarbon production unit 3, if the ratio of hydrogen to carbon monoxide is very small, there is a possibility of hydrogen deficiency. Therefore, when the molar ratio (M H / M CO ) in the useful hydrocarbon production unit 3 is very small, if the supply amount of hydrogen supplied by the hydrogen supply unit 5 to the useful hydrocarbon production unit 3 is increased, the hydrogen deficiency in the useful hydrocarbon production unit 3 can be suppressed. In this way, according to the molar ratio (M H / M CO ) in the useful hydrocarbon production unit 3, by adjusting the supply amount of hydrogen supplied by the hydrogen supply unit 5 to the useful hydrocarbon production unit 3, the hydrogen deficiency in the useful hydrocarbon production unit 3 can be more reliably suppressed.

[0143] Further, the apparatus 1 for producing useful hydrocarbons according to the embodiment may further include an adjustment unit (not shown) that adjusts the molar ratio (M CO / M H ) of the number of moles M of hydrogen to the number of moles M of carbon monoxide contained in the first gas obtained in the dry reforming unit 2. The adjustment unit is provided in front of the dry reforming unit 2. CO to the number of moles M of hydrogen H in the first gas discharged from the dry reforming unit 2. The adjustment unit preferably is a steam drum. The steam drum supplies steam to the dry reforming unit 2 to adjust the molar ratio (M H / M CO ) in the first gas. In the adjustment unit, the molar ratio (M H / M CO ) in the first gas is adjusted according to the conditions of the useful hydrocarbon synthesis reaction carried out in the useful hydrocarbon production unit 3. H / M CO )

[0144] The adjustment unit adjusts the molar ratio (M H / M CO ) in the first gas discharged from the dry reforming unit 2. The adjustment unit preferably is a steam drum. The steam drum supplies steam to the dry reforming unit 2 to adjust the molar ratio (M H / M CO ) in the first gas. In the adjustment unit, the molar ratio (M H / M CO ) in the first gas is adjusted according to the conditions of the useful hydrocarbon synthesis reaction carried out in the useful hydrocarbon production unit 3. H / M CO ) H / M CO ) H / M CO )

[0145] When the first gas whose molar ratio (M H / M CO ) has been adjusted by the adjustment unit is supplied to the useful hydrocarbon production unit 3, hydrogen deficiency in the useful hydrocarbon production unit 3 can be suppressed. Therefore, the target useful hydrocarbons can be efficiently produced over a long period of time. H / M CO )

[0146] Further, the apparatus 1 for producing useful hydrocarbons according to the embodiment may further include a combustion unit (not shown) that separates a substance containing carbon atoms from the second gas and burns the substance containing carbon atoms to generate carbon dioxide. In this case, the recycling unit 4 supplies the carbon dioxide-containing gas and the carbon dioxide generated 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 burned to produce carbon dioxide. The substances containing carbon atoms burned 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 burned in the combustion section may or may not contain carbon dioxide.

[0148] The recycling section 4 supplies the carbon dioxide-containing gas separated from the second gas generated in the useful hydrocarbon production section 3, as well as the carbon dioxide generated in the combustion section, to the dry reforming section 2. The amount of carbon dioxide supplied to the dry reforming section 2 can be increased by the combustion section. Therefore, since coking generation and carbon dioxide shortage in the dry reforming section 2 can be further suppressed, the target useful hydrocarbons can be efficiently produced over a long period. Also, the heat generated in the combustion section can be recovered and utilized in the dry reforming section 2 and the useful hydrocarbon production section 3.

[0149] Further, it is preferable to adjust the combustion rate of the combustion section according to the ratio of the hydrocarbon and carbon dioxide supplied to the dry reforming section 2. By changing the combustion rate of the combustion section, the amount of carbon dioxide generated in the combustion section can be adjusted. Therefore, according to the ratio of the hydrocarbon and carbon dioxide supplied to the dry reforming section 2, the combustion rate of the combustion section is adjusted to adjust the amount of carbon dioxide generated, and the amount of carbon dioxide supplied to the dry reforming section 2 in the recycling section 4 can be adjusted, so that the production amount of the target useful hydrocarbons can be increased.

[0150] When the combustion rate of the combustion section is 3% or more, the carbon dioxide shortage in the dry reforming section 2 can be sufficiently suppressed. Also, when the combustion rate of the combustion section is 50% or less, the ratio of the hydrocarbon and carbon dioxide supplied to the dry reforming section 2 is good. Therefore, when the combustion rate of the combustion section is 3% or more and 50% or less, the target useful hydrocarbons can be efficiently produced over a long period.

[0151] Further, when the useful hydrocarbon production apparatus 1 of the embodiment supplies biogas to the dry reforming unit 2, it may be provided with a desulfurization unit (not shown) for desulfurizing the biogas. The desulfurization unit is connected to the upstream side of the dry reforming unit 2. The sulfur component in the biogas deteriorates the catalytic performance of the dry reforming catalyst installed in the dry reforming unit 2 and the useful hydrocarbon production catalyst installed in the useful hydrocarbon production unit 3. By the desulfurization unit desulfurizing the biogas, it is possible to suppress the deterioration of the catalytic performance of the dry reforming catalyst and the useful hydrocarbon production catalyst. Therefore, the target useful hydrocarbon can be stably produced over a long period of time.

[0152] Further, the useful hydrocarbon production apparatus 1 of the embodiment may be provided with a dehydration unit (not shown) for dehydrating the first gas generated in the dry reforming unit 2. The dehydration unit is provided between the dry reforming unit 2 and the useful hydrocarbon production unit 3. By the dehydration unit dehydrating the first gas, the efficiency of the synthesis reaction of the useful hydrocarbon carried out in the useful hydrocarbon production unit 3 can be improved, and further, the deterioration of the catalytic performance of the useful hydrocarbon production catalyst due to moisture can be suppressed.

[0153] Further, the useful hydrocarbon production apparatus 1 of the embodiment may be provided with a compression unit (not shown) for compressing the first gas generated in the dry reforming unit 2. The compression unit is provided between the dry reforming unit 2 and the useful hydrocarbon production unit 3. By the compression unit compressing the first gas, the compressed first gas is supplied to the useful hydrocarbon production unit 3, so that the efficiency of the synthesis reaction of the target useful hydrocarbon carried out in the useful hydrocarbon production unit 3 can be improved.

[0154] Further, the useful hydrocarbon produced by the useful hydrocarbon production apparatus 1 is the same as the useful hydrocarbon produced by the above-described useful hydrocarbon production method, and is 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.

[0155] In the production apparatus 1 of useful hydrocarbons, according to the type of useful hydrocarbons to be produced, various useful hydrocarbon synthesis reactions are carried out under appropriate catalysts and reaction conditions in the useful hydrocarbon production unit 3 to synthesize a hydrocarbon mixture mainly composed of various target useful hydrocarbons from carbon monoxide and hydrogen. The various useful hydrocarbon synthesis reactions carried out in the useful hydrocarbon production unit 3 are the same as the conditions of the useful hydrocarbon production step S20 in the useful hydrocarbon production method described above.

[0156] According to the embodiment described above, paying attention to the methane-containing hydrocarbon and carbon dioxide that can be obtained relatively easily, dry reforming that can generate carbon monoxide and hydrogen from methane-containing hydrocarbon and carbon dioxide, and the fact that the second gas obtained in the useful hydrocarbon production step contains carbon dioxide as an impurity, by supplying the carbon dioxide in the second gas to the dry reforming step for reuse, using easily obtained raw materials, the target useful hydrocarbons can be efficiently produced over a long period.

[0157] Furthermore, in recent years, regarding natural gas produced from gas fields in Indonesia and Malaysia where the reserves of natural gas are abundant and the treatment cost of impurities has become a problem, and the natural gas contains a large amount of carbon dioxide as an impurity, the technology of the present disclosure can also be preferably applied. Instead of the above mixed gas, when a gas with a methane / carbon dioxide molar ratio of 1 or more and 9 or less is used as a raw material and a dry reforming step of generating a first gas containing carbon monoxide and hydrogen from the gas is carried out, a large amount of carbon dioxide can be efficiently supplied to the dry reforming step. Therefore, the target useful hydrocarbons can be efficiently produced over a long period, and the problem of the treatment cost for gas containing a large amount of carbon dioxide as an impurity can be solved.

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

Examples

[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 FIG. 2, liquefied petroleum gas, which is a useful hydrocarbon, was produced by the production method shown in FIG. 1. Specifically, it is as follows.

[0161] A fixed-bed flow reactor was used in the dry reforming section 2. A reaction tube made of quartz glass was used. As described above, biogas contains more methane than carbon dioxide. Therefore, assuming that carbon dioxide was supplied from the recycling section 4, a raw material having the same ratio of methane to carbon dioxide (on a carbon basis) was supplied to the dry reforming section 2. Regarding the raw material supplied to the dry reforming section 2, the total flow rate of methane and carbon dioxide was set to 10 ml / min. A dry reforming catalyst was filled so that GHSV = 2170 (1 / h), and quartz wool was packed above and below it to fix the dry reforming catalyst. As the dry reforming catalyst, the above-mentioned dry reforming catalyst containing 1% by mass of Ni was used. 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 with a gas pack and analyzed by GC-TCD. In addition, as a pretreatment, the dry reforming catalyst was subjected to a reduction treatment at 700°C for 1.5 hours under hydrogen flow.

[0162] For the useful hydrocarbon production unit 3, a fixed-bed flow reactor was used. A stainless-steel reaction tube was employed. As described above, in the dry reforming unit 2, carbon monoxide and hydrogen are produced in the same proportion. Therefore, assuming that hydrogen is not supplied from the hydrogen supply unit 5, a first gas with the same molar ratio of carbon monoxide to hydrogen was supplied to the useful hydrocarbon production unit 3. The flow rate of the first gas supplied to the useful hydrocarbon production unit 3 was set at 37.2 ml / min. The useful hydrocarbon production catalyst (LPG production catalyst) was filled so that GHSV = 2000 (1 / h), and quartz wool was packed above and below it to fix the LPG production catalyst. As the LPG production catalyst, a catalyst obtained by physically mixing a methanol synthesis catalyst substance and a ZSM-5 type zeolite catalyst substance supporting Pt and Pd in a weight ratio of 1:1 was used. The heating temperature of the LPG production catalyst was set at 280 °C. The pressure inside the useful hydrocarbon production unit 3 was set at 5.0 MPa. The second gas produced in the useful hydrocarbon production unit 3 was collected with a gas pack and analyzed by GC-TCD and FID. As a pretreatment, the LPG production catalyst was subjected to a reduction treatment at 380 °C for 2 hours under hydrogen flow.

[0163] (Comparative Examples 1-1 to 1-3) Except for the changes shown in Table 1, the same procedures as in the above examples were performed. In Comparative Examples 1-1 to 1-3, a method was assumed in which carbon dioxide was not supplied from the recycling unit 4.

[0164] Regarding the ranking of the syngas yield in Table 1, when the syngas yield is 1.20 kg / Nm 3 or more, it is rated as "good", and when the syngas yield is less than 1.20 kg / Nm 3 it is rated as "bad". Also, regarding the ranking of the comprehensive evaluation, when the ranks of both the initial and 7-day syngas yields are good, it is marked as "〇", when only one of the ranks of the initial and 7-day syngas yields is good, it is marked as "△", and when the ranks of both the initial and 7-day syngas yields are bad, it is marked as "×".

[0165]

Table 1

[0166] As shown in Table 1, in the example where carbon dioxide is supplied from the recycling section 4 to the dry reforming section 2, compared with the comparative example, since the carbon molar ratio of hydrocarbon / carbon dioxide in the inlet gas of the dry reforming process is good, the synthesis gas yield could be increased. At this time, when the carbon molar ratio of hydrocarbon / carbon dioxide is 1.30 or less, the synthesis gas yield is good. More preferably, when it is 1.00 or less, catalyst deterioration can be well suppressed, suggesting that synthesis gas can be efficiently produced over a long period and the yield of useful hydrocarbons can be increased.

[0167] Also, from Examples 1-5, in order to appropriately adjust the above carbon molar ratio of hydrocarbon / carbon dioxide, if the concentration of carbon dioxide in the recycle gas is 50% or more, by adjusting the amount of recycle gas in the recycle process, the amount of carbon dioxide for favorably adjusting the carbon molar ratio of hydrocarbon / carbon dioxide can be ensured.

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

[0169] (Examples 2 to 3) It was carried out in the same manner as in Example 1-1 except that it was changed to the first gas having the molar ratio of carbon monoxide and hydrogen shown in Table 2. That is, in Examples 2 to 3, it is a method of supplying hydrogen from the hydrogen supply section 5.

[0170]

Table 2

[0171] As shown in Table 2, by supplying hydrogen from the hydrogen supply section 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 unit was operated at the combustion rates shown in Table 3, and the amount of carbon dioxide supplied from the recycling unit 4 to the dry reforming unit 2 was adjusted. Then, the total amount of hydrocarbons excluding the liquefied petroleum gas component in the second gas and the amount of carbon dioxide in the second gas were measured, and the ratio of the total hydrocarbons excluding the liquefied petroleum gas component to carbon dioxide in the second gas was calculated. In Example 3-1, the combustion unit did not operate.

[0173] [Table 3]

[0174] As shown in Table 3, it was suggested that changing the combustion rate of the combustion unit can adjust the amount of carbon dioxide, and thus increase the production amount of liquefied petroleum gas.

[0175] From the above, it was suggested that according to the above examples, liquefied petroleum gas can be efficiently produced over a long period using easily obtainable raw materials.

[0176] (Example 4) As the catalyst for producing useful hydrocarbons (catalyst for producing olefins) filled in the useful hydrocarbon production unit 3, a physical mixture of a methanol synthesis catalyst and a ZSM-5 type zeolite catalyst substance carrying P in a weight ratio of 1:1 was used. The reaction temperature was 320 °C, GHSV = 2000 h -1 , and olefins were produced in the same manner as in the above examples except that the pressure was 5.0 MPa and the supplied H2 / CO ratio was 2.0.

[0177] (Example 5) As the catalyst for producing useful hydrocarbons (catalyst for producing aromatic hydrocarbons) filled in the useful hydrocarbon production unit 3, a physical mixture of a methanol synthesis catalyst and a ZSM-5 type zeolite (ZnCr2O4 / ZSM-5) obtained by physically mixing 1 wt% of ZnCr2O4 in a weight ratio of 1:1 was used. The reaction temperature was 350 °C, GHSV = 500 h-1 , and aromatic hydrocarbons were produced in the same manner as in the above examples except that the pressure was 5.0 MPa and the supplied H2 / CO ratio was 2.5.

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

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

[0180]

Table 4

[0181] As shown in Table 4, by appropriately changing the catalyst and reaction conditions, olefins, aromatic hydrocarbons, gasoline fractions, and liquid hydrocarbons could also be produced in the useful hydrocarbon production process.

[0182] Kumagai et al., "Chemical fuel conversion by co-pyrolysis of lignocellulosic biomass / waste plastic mixture", Journal of the Japan Society for Waste Resources Recycling, Vol. 28, No. 1, pp. 4-12, 2017 reported that the gas composition obtained by pyrolyzing lignocellulosic biomass is as shown in (1) of Table 5 (all C2-C4 components are converted as C2). At this time, assuming that only methane and ethane were produced as hydrocarbons, when the recycle gas (2) in the recycle process was added to the gas component (1) after pyrolysis, the concentration could be adjusted to the composition of (3) in Table 5, and it was found that the carbon molar ratio of hydrocarbons and carbon dioxide could be adjusted to a suitable value equivalent to that of the above examples in Table 1.

[0183] As described above, the above embodiments and examples are applicable to various raw materials. For example, there are biogas obtained by methane fermentation of organic waste such as livestock manure, lignocellulosic biomass, and gas obtained by pyrolysis and gasification of waste plastics.

[0184]

Table 5

Explanation of Reference Signs

[0185] 1 Production apparatus for useful hydrocarbons 2 Dry reforming section 3 Useful hydrocarbon generation section 4 Recycling section 5 Hydrogen supply section

Claims

1. A dry reforming step of producing a first gas containing carbon monoxide and hydrogen from a mixed gas containing methane-containing hydrocarbon 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 it to the dry reforming step A method for producing useful hydrocarbons having the above steps.

2. The recycling step adjusts the supply amount of the carbon dioxide-containing gas supplied to the dry reforming step according to the ratio (M ＣＯ２ / M ＣＯ２ ) of the total carbon molar number M of carbon dioxide in the mixed gas supplied to the dry reforming step and the total carbon molar number M of hydrocarbons supplied to the dry reforming step with respect to the carbon dioxide in the carbon dioxide-containing gas. ＣＯ２ The method for producing useful hydrocarbons according to claim 1, ＨＣ wherein the supply amount of the carbon dioxide-containing gas supplied to the dry reforming step is adjusted according to the ratio (M ＨＣ / M ＣＯ２ ) of the total carbon molar number M of hydrocarbons supplied to the dry reforming step to the total carbon molar number M of carbon dioxide in the mixed gas supplied to the dry reforming step and the carbon dioxide in the carbon dioxide-containing gas. ＨＣ / M ＣＯ２ )

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

4. The method for producing useful hydrocarbons according to any one of claims 1 to 3, further comprising a hydrogen supply step of separating hydrogen from the second gas and supplying it to the useful hydrocarbon production step.

5. The hydrogen supply step adjusts the supply amount of hydrogen supplied to the useful hydrocarbon production step according to the number of moles M of hydrogen in the useful hydrocarbon production step. Ｈ The method for producing a useful hydrocarbon according to claim 4, wherein the supply amount of hydrogen supplied to the useful hydrocarbon production step is adjusted according to M.

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

7. The method further comprises a combustion step of separating a substance containing carbon atoms from the second gas and burning the substance containing carbon atoms to produce carbon dioxide, In the recycling step, the carbon dioxide-containing gas and the carbon dioxide generated in the combustion step are supplied to the dry reforming step. The method for producing useful hydrocarbons according to any one of claims 1 to 6.

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

9. The useful hydrocarbon is liquefied petroleum gas. The method for producing useful hydrocarbons according to any one of claims 1 to 8.

10. The useful hydrocarbon is liquefied petroleum gas, and the carbon dioxide-containing gas contains hydrocarbons other than those having 3 to 4 carbon atoms. The method for producing useful hydrocarbons according to any one of claims 1 to 8.

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

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

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

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

15. A dry reforming unit that generates a first gas containing carbon monoxide and hydrogen from a mixed gas containing a methane-containing hydrocarbon and carbon dioxide; A useful hydrocarbon generation unit that is supplied with the first gas generated by the dry reforming unit and generates a second gas containing a useful hydrocarbon from carbon monoxide and hydrogen in the first gas; A recycling unit that separates a carbon dioxide-containing gas from the second gas generated by the useful hydrocarbon generation unit and supplies it to the dry reforming unit A useful hydrocarbon production apparatus comprising:

16. A dry reforming step of generating a first gas containing carbon monoxide and hydrogen from a gas in which methane / carbon dioxide is 1 or more and 9 or less in molar conversion; A useful hydrocarbon generation step of generating a second gas containing a useful hydrocarbon 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 it to the dry reforming step A method for producing a useful hydrocarbon having:

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