Method for producing useful hydrocarbons and apparatus for producing useful hydrocarbons

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

[0002] Useful hydrocarbons, such as various lower olefins and aromatic hydrocarbons that serve as basic chemical raw materials, and various liquid fuels (gasoline, liquefied petroleum gas (LPG), aviation fuel, etc.), are hydrocarbons with two or more carbon atoms and are mainly produced from petroleum resources. However, the production processes of these hydrocarbons are a source of geopolitical risk because they primarily rely on petroleum resources. Furthermore, the production and consumption processes of these hydrocarbons emit large amounts of carbon dioxide, which is a problem from the perspective of global warming. Therefore, there is a need to develop cleaner processes that use resources that are not limited to specific geographical areas as raw materials and that produce less carbon dioxide.

[0003] For example, liquefied petroleum gas (LPG) emits less carbon dioxide, one of the causes of global warming, compared to crude oil and gasoline, and research into its potential to mitigate global warming is actively being conducted. Patent Document 1 describes a method for producing LPG, comprising a synthesis gas production step for producing synthesis gas from a carbon-containing raw material and at least one selected from the group consisting of water, oxygen, and carbon dioxide; a lower paraffin production step for producing lower paraffin-containing gas containing low-boiling-point components from the synthesis gas; a separation step for separating low-boiling-point components from the lower paraffin-containing gas; and a recycling step for recycling the low-boiling-point components back into the synthesis gas production step. However, in Patent Document 1, natural resources such as natural gas, naphtha, and coal are used as the carbon-containing raw material for producing LPG.

[0004] In addition to the above, renewable energy sources such as biogas power generation using organic waste like livestock manure and sewage sludge, and solar power generation, have been attracting attention in recent years. However, because these technologies produce electricity, energy transportation can be difficult depending on the transmission capacity. Furthermore, biogas power generation utilizes only methane gas from the methane gas and carbon dioxide obtained from organic waste. Therefore, the current situation where carbon dioxide is not utilized is undesirable from the perspective of global warming.

[0005] Thus, natural resources are not inexhaustible and can only be produced in specific countries or regions. Furthermore, even in the realm of renewable energy, there is a need for energy forms other than electricity from the perspective of energy storage and transportation. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2006-143752 [Overview of the project] [Problems that the invention aims to solve]

[0007] The purpose of this disclosure is to provide a method for producing useful hydrocarbons and an apparatus for producing useful hydrocarbons that can be efficiently manufactured over a long period of time using methane-containing hydrocarbons and carbon dioxide, which are readily available raw materials. [Means for solving the problem]

[0008] [1] A method for producing useful hydrocarbons, comprising: a dry reforming step of producing a first gas containing carbon monoxide and hydrogen from a mixed gas containing methane-containing hydrocarbons and carbon dioxide; a useful hydrocarbon production step of producing a second gas containing useful hydrocarbons from 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 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 with respect to the total carbon molar number M of carbon dioxide in the carbon dioxide-containing gas, in the method for producing useful hydrocarbons according to [1] above. HC , CO2 with respect to the total carbon molar number M of hydrocarbons supplied to the dry reforming step, in the method for producing useful hydrocarbons according to [1] above. HC of (M HC HC / M CO2 CO2 ) in the method for producing useful hydrocarbons according to [1] above. [3] In the method for producing useful hydrocarbons according to [1] or [2] above, the CO2 concentration of the carbon dioxide-containing gas is 50% or more. [4] The method for producing useful hydrocarbons 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 method for producing useful hydrocarbons according to [4] above, the hydrogen supply step adjusts the supply amount of hydrogen supplied to the useful hydrocarbon production step according to the molar number M of hydrogen in the useful hydrocarbon production step. H In the method for producing useful hydrocarbons according to [4] above. [6] The method for producing useful hydrocarbons 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 of carbon monoxide contained in the first gas obtained in the dry reforming step to the molar number M of hydrogen. CO with respect to the molar number M of hydrogen, in the method for producing useful hydrocarbons according to any one of [1] to [5] above. H of (M H H / M CO CO ) in the method for producing useful hydrocarbons according to any one of [1] to [5] above. [7] The method for producing useful hydrocarbons 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] In the method for producing useful hydrocarbons according to any one of [1] to [7] above, the useful hydrocarbon is at least one hydrocarbon selected from the group consisting of olefins, aromatic hydrocarbons, gasoline, liquefied petroleum gas, and liquid hydrocarbons. [9] A method for producing a useful hydrocarbon according to any one of [1] to [8] above, wherein the useful hydrocarbon is liquefied petroleum gas.

[10] A 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 with a carbide number of 3 to 4.

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

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

[13] A 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 a hydrocarbon other than gasoline and carbon monoxide.

[14] A method for producing a useful hydrocarbon according to any one of the above [1] to [8], wherein the useful hydrocarbon is a liquid hydrocarbon, and the carbon dioxide-containing gas contains at least one of a hydrocarbon having 4 or fewer carbon atoms and carbon monoxide.

[15] A apparatus for producing useful hydrocarbons, comprising: a dry reforming section that generates a first gas containing carbon monoxide and hydrogen from a mixed gas containing methane-containing hydrocarbons and carbon dioxide; a useful hydrocarbon generation section to which the first gas generated in the dry reforming section is supplied and which generates a second gas containing useful hydrocarbons from the carbon monoxide and hydrogen in the first gas; and a recycling section that separates a carbon dioxide-containing gas from the second gas generated in the useful hydrocarbon generation section and supplies it to the dry reforming section.

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

[0009] According to this disclosure, it is possible to provide a method for producing useful hydrocarbons and an apparatus for producing useful hydrocarbons that can be efficiently manufactured over a long period of time using methane-containing hydrocarbons and carbon dioxide, which are readily available raw materials. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a block diagram showing an example of a method for producing useful hydrocarbons according to the embodiment. [Figure 2] Figure 2 is a schematic diagram showing an example of a production apparatus for useful hydrocarbons according to the embodiment. [Modes for carrying out the invention]

[0011] The embodiments will be described in detail below with reference to the drawings.

[0012] The inventors focused on dry reforming, a method that can easily produce methane-containing hydrocarbons and carbon dioxide, as well as 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 amount of methane-containing hydrocarbons is greater than a predetermined amount (conditions where carbon dioxide is insufficient), there are concerns that the catalyst used in the reaction will deteriorate significantly (coking), requiring catalyst replacement in a short period of time, and in the worst case, leading to blockage of the reactor, thus compromising efficiency and safety.

[0013] Furthermore, the inventors have observed that when a gas containing useful hydrocarbons (second gas) is generated from carbon monoxide and hydrogen in a useful hydrocarbon generation step performed after the dry reforming step, unreacted substances or by-products from the dry reforming step and the useful hydrocarbon generation step, such as carbon dioxide, are included in the second gas. The inventors have found that by supplying the carbon dioxide, which is an impurity contained in the second gas, to the dry reforming step for reuse, the degradation reaction of the catalyst during the dry reforming step can be suppressed, and useful hydrocarbons can be produced efficiently over a long period of time. This disclosure is based on these findings.

[0014] The embodiment of the method for producing useful hydrocarbons includes 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 production step of generating a second gas containing useful hydrocarbons from the carbon monoxide and hydrogen in the first gas; and a recycling step of separating the 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 this embodiment includes a dry reforming section that generates a first gas containing carbon monoxide and hydrogen from a mixed gas containing methane-containing hydrocarbons and carbon dioxide; a useful hydrocarbon generation section that receives the first gas generated in the dry reforming section and generates a second gas containing useful hydrocarbons from the carbon monoxide and hydrogen in the first gas; and a recycling section that separates the carbon dioxide-containing gas from the second gas generated in the useful hydrocarbon generation section and supplies it to the dry reforming section.

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

[0017] As shown in Figure 1, the method for producing useful hydrocarbons includes a dry reforming step S10, a useful hydrocarbon generation 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 hydrocarbons and carbon dioxide. The methane-containing hydrocarbon supplied to the dry reforming step S10 consists 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. In this case, the ratio of the number of moles of methane to the number of moles of hydrocarbons having 2 to 6 carbon atoms (methane / hydrocarbons having 2 to 6 carbon atoms) is preferably 1 or more. When a mixed gas containing methane-containing hydrocarbons as described above is supplied to the dry reforming step S10, the yield of useful hydrocarbons is improved.

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

[0020] In the dry reforming process S10, carbon monoxide and hydrogen are synthesized from methane and carbon dioxide contained in the mixed gas by dry reforming, for example, as shown in equation (1) below. Furthermore, since the hydrocarbon used as a raw material for dry reforming is not limited to methane, generalizing equation (1) to saturated hydrocarbons, for example, results in equation (2) below. At this time, equal amounts of carbon and carbon dioxide contained in the raw material hydrocarbons react.

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

[0022] In the dry reforming step S10, a catalyst (hereinafter also simply referred to as the dry reforming catalyst) is used to synthesize carbon monoxide and hydrogen from methane-containing hydrocarbons and carbon dioxide contained in the mixed gas by dry reforming. In the dry reforming step S10, the mixed gas is supplied to the dry reforming catalyst, and the dry reforming catalyst is heated, so that the methane-containing hydrocarbons and carbon dioxide in the supplied mixed gas react with the dry reforming catalyst to produce a first gas containing carbon monoxide and hydrogen.

[0023] While there are no particular limitations on the catalyst for dry reforming, it is preferable that the catalyst for dry reforming comprises a porous support structure composed of a zeolite-type compound, and at least one catalytic substance inherent in the support, wherein the supports have passages communicating with each other, the ratio of the long side dimension L to the thickness dimension d in the support (L / d ratio) is 5.0 or more, and the catalytic substance is present in at least the passages of the support.

[0024] For such catalyst structures, the L / d ratio of the support is 5.0 or higher, preferably 5.0 to 35.0, and more preferably 7.0 to 25.0. A support L / d ratio of 5.0 or higher improves catalytic activity. Furthermore, an L / d ratio of 35.0 or lower improves the manufacturing yield of the catalyst structure.

[0025] Furthermore, for such catalyst structures, the average particle size of the catalyst material is preferably between 1.00 nm and 13.00 nm. When the average particle size of the catalyst material is within the above range, the catalytic activity increases sufficiently, and as the average particle size decreases, the catalytic activity can be further improved. Also, from the viewpoint of achieving both high catalytic activity and coking resistance, the average particle size of the catalyst material is preferably 9.00 nm or less, and more preferably 4.50 nm or less.

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

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

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

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

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

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

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

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

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

[0035] Therefore, in the recycling process S30, by supplying carbon dioxide-containing gas (so-called off-gas), which is an impurity in the second gas produced in the useful hydrocarbon production process S20, to the dry reforming process S10, coking of the dry reforming catalyst caused by a decrease in the ratio of carbon dioxide to methane-containing hydrocarbons can be suppressed, thereby suppressing the decrease in the activity of the dry reforming catalyst. As a result, useful hydrocarbons can be produced efficiently over a long period of time. In addition, since the carbon dioxide emitted from the useful hydrocarbon production process S20 is reused as a raw material in the dry reforming process S10, global warming can be suppressed. If the carbon dioxide-containing gas contains hydrocarbons other than useful hydrocarbons, the yield of useful hydrocarbons will be further improved.

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

[0037] Thus, in addition to being a renewable energy resource, biogas is more readily available than natural resources such as natural gas. Therefore, using biogas as a raw material in the production of useful hydrocarbons ensures a stable supply of raw materials without the risk of shortages.

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

[0039] To address these concerns, the recycling process S30 supplies a carbon dioxide-containing off-gas to the dry reforming process S10, thereby compensating for any excess carbon dioxide in the biogas. In this way, even when biogas is used as a raw material, the recycling process S30 can suppress the shortage of biogas-derived carbon dioxide in the dry reforming process S10, allowing the dry reforming process S10 to be carried out stably over a long period of time. Furthermore, it can suppress coking of the dry reforming catalyst caused by a decrease in the ratio of carbon dioxide to methane-containing hydrocarbons, thereby suppressing the decrease in the activity of the dry reforming catalyst. As a result, useful hydrocarbons can be produced efficiently over a long period of time.

[0040] Furthermore, the recycling process S30 involves the total number of carbon moles M of carbon dioxide in the mixed gas supplied to the dry reforming process S10 and the carbon dioxide-containing gas. CO2 Total number of carbon moles M of hydrocarbons supplied to the dry reforming process S10 HC The ratio (M HC / M CO2It is preferable to adjust the amount of carbon dioxide-containing gas supplied to the dry reforming process S10 according to the following. The hydrocarbons supplied to the dry reforming process S10 are methane-containing hydrocarbons in the mixed gas and hydrocarbons contained in the carbon dioxide-containing gas.

[0041] In the dry reforming process S10, under conditions where the amount of methane-containing hydrocarbons is greater than a predetermined amount, coking of the dry reforming catalyst and a carbon dioxide deficiency may occur. Therefore, the recycling process S30 is performed in the dry reforming process S10, with the above ratio (M HC / M CO2 When the ratio (M) is very large, increasing the amount of carbon dioxide-containing gas supplied to the dry reforming process S10 can suppress coking and carbon dioxide deficiency in the dry reforming process S10. HC / M CO2 By adjusting the amount of carbon dioxide-containing gas supplied to the dry reforming process S10 according to the above, coking and carbon dioxide deficiency in the dry reforming process S10 can be further suppressed.

[0042] Furthermore, biogas is produced from various types of organic waste. Therefore, the ratio of methane-containing hydrocarbons to carbon dioxide in the biogas differs depending on the type of organic waste. Even when biogas is supplied to the dry reforming process S10, the recycling process S30 adjusts the above ratio (M) in the dry reforming process S10. HC / M CO2 The amount of carbon dioxide-containing gas supplied to the dry reforming process S10 is adjusted accordingly. Therefore, even if the ratio of methane-containing hydrocarbons to carbon dioxide in the biogas differs, coking and carbon dioxide deficiency in the dry reforming process S10 can be further suppressed.

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

[0044] Furthermore, the CO2 concentration of the carbon dioxide-containing gas supplied to the dry reforming process S10 by the recycling process 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, coking generation and carbon dioxide deficiency in the dry reforming process S10 can be sufficiently suppressed by adjusting the amount of recycled gas supplied in the recycling process S30.

[0045] Furthermore, the method for producing useful hydrocarbons in 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 involves a thermal decomposition treatment using biomass resources such as woody biomass or waste plastics as raw materials, or a gasification treatment in which these raw materials are oxidatively decomposed by adding an oxidizing agent (H2O, oxygen, or carbon dioxide).

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

[0047] In this embodiment, the method for producing useful hydrocarbons may include a separation step between the mixed gas generation step and the dry reforming step S10, in which carbon monoxide and hydrogen are separated from the gas containing hydrocarbons and carbon dioxide.

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

[0049] In the dry reforming process S10, if the amount of hydrocarbons is greater than the specified amount (i.e., there is a shortage of carbon dioxide), the recycling process S30 supplies carbon dioxide-containing gas, which is an impurity in the second gas produced in the useful hydrocarbon production process S20, to the dry reforming process S10. This suppresses coking of the dry reforming catalyst caused by a decrease in the ratio of carbon dioxide to hydrocarbons, thereby suppressing a decrease in the activity of the dry reforming catalyst. As a result, the desired useful hydrocarbons can be produced efficiently over a long period of time. Furthermore, since the carbon dioxide emitted from the useful hydrocarbon production process S20 is reused as a raw material in the dry reforming process S10, global warming can be mitigated.

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

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

[0052] As shown in equation (3) above, the useful hydrocarbon production step S20 requires twice the amount of hydrogen compared to carbon monoxide. On the other hand, the ratio of carbon monoxide to hydrogen in the first gas produced in the dry reforming step S10 is the same as shown in equations (1) and (2) above. Thus, since the same ratio of carbon monoxide and hydrogen is produced in the dry reforming step S10, and twice the amount of hydrogen compared to carbon monoxide is required in the useful hydrocarbon production step S20, a hydrogen deficiency will occur if the useful hydrocarbon production step S20 is carried out for a long period of time. As a result, there will be an excess of carbon monoxide, and the amount of useful hydrocarbons produced in the useful hydrocarbon production step S20 will decrease.

[0053] Therefore, in the hydrogen supply process S40, hydrogen (so-called off-gas), which is an impurity in the second gas produced in the useful hydrocarbon production process S20, is supplied to the useful hydrocarbon production process S20, thereby compensating for any excess of hydrogen, which is the raw material for the useful hydrocarbon production process S20. In this way, the hydrogen supply process S40 can suppress hydrogen shortages caused by the useful hydrocarbon production process S20 over a long period, allowing the useful hydrocarbon production process S20 to be carried out stably over a long period. As a result, useful hydrocarbons that are easy to store and transport can be produced efficiently over a long period. In addition, since the hydrogen discharged from the useful hydrocarbon production process S20 is reused as a raw material for the useful hydrocarbon production process S20, the environmental burden can be reduced.

[0054] Furthermore, the hydrogen supply process S40 is performed using the number of moles M of hydrogen in the useful hydrocarbon production process S20. H It is preferable to adjust the amount of hydrogen supplied to the useful hydrocarbon production step S20 accordingly, and the above number of moles M H Furthermore, it is more preferable to adjust the amount of hydrogen supplied to the useful hydrocarbon production step S20 depending on the type of useful hydrocarbon to be produced and the reaction.

[0055] For example, when producing liquefied petroleum gas as a useful hydrocarbon, the number of moles of hydrogen M in the useful hydrocarbon production step S20. HWhen there is a large amount of hydrogen, the useful hydrocarbon synthesis reaction proceeds smoothly. On the other hand, the number of moles of hydrogen M in the useful hydrocarbon production step S20 H If the amount is insufficient, it may lead to a hydrogen deficiency in the useful hydrocarbon synthesis reaction. Therefore, in the hydrogen supply step S40, the number of moles of hydrogen M in the useful hydrocarbon production step S20 H When the supply of hydrogen is low, increasing the amount of hydrogen supplied to the useful hydrocarbon production process S20 can suppress hydrogen deficiency in the useful hydrocarbon production process S20.

[0056] Thus, in the hydrogen supply process S40, the number of moles of hydrogen M in the useful hydrocarbon production process S20 H When the amount of hydrogen supplied to the useful hydrocarbon production process S20 is small, the amount of hydrogen supplied to the useful hydrocarbon production process S20 is increased, and so on. H By adjusting the amount of hydrogen supplied to the useful hydrocarbon production process S20 accordingly, the desired useful hydrocarbons can be produced more efficiently.

[0057] Furthermore, the hydrogen supply process S40 is the number of moles M of carbon monoxide in the useful hydrocarbon production process S20. CO The number of moles of hydrogen M H Mole ratio (M H / M CO Depending on the situation, it is preferable to adjust the amount of hydrogen supplied to the useful hydrocarbon production process S20.

[0058] Molar ratio (M) of useful hydrocarbon production step S20 H / M CO Regarding this, if the ratio of hydrogen to carbon monoxide is very low, a hydrogen deficiency may occur. Therefore, in the hydrogen supply process S40, the molar ratio (M) in the useful hydrocarbon production process S20 is H / M CO When the molar ratio (M) in the useful hydrocarbon production process S20 is very low, increasing the amount of hydrogen supplied to the useful hydrocarbon production process S20 can suppress hydrogen deficiency in the useful hydrocarbon production process S20. H / M COBy adjusting the amount of hydrogen supplied to the useful hydrocarbon production process S20 according to the conditions, hydrogen deficiency in the useful hydrocarbon production process S20 can be more reliably suppressed.

[0059] Furthermore, the method for producing useful hydrocarbons in the embodiment involves the number of moles M of carbon monoxide contained in the first gas obtained in the dry reforming step S10. CO The number of moles of hydrogen M H Mole ratio (M H / M CO The process may further include adjustment steps (not shown) to adjust the following: The adjustment steps are performed before the dry reforming step S10.

[0060] The adjustment process involves adjusting the molar ratio (M) of the first gas obtained in the dry reforming process S10. H / M CO ) is adjusted. The adjustment process is performed before the dry reforming process S10, and the molar ratio (M) in the first gas is adjusted. H / M CO It is preferable to adjust the molar ratio (M) in the first gas, depending on the conditions of the reaction to produce useful hydrocarbons carried out in the useful hydrocarbon production step S20. H / M CO ) will be adjusted.

[0061] The molar ratio (M) is determined by the adjustment process. H / M CO When the first gas, which has been adjusted, is supplied to the useful hydrocarbon production process S20, hydrogen deficiency during the long-term useful hydrocarbon production process S20 can be suppressed, allowing the useful hydrocarbon production process S20 to be carried out stably over a long period of time. Therefore, the target useful hydrocarbons can be produced efficiently over a long period of time.

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

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

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

[0065] The recycling process S30 supplies the carbon dioxide-containing gas separated from the second gas produced in the useful hydrocarbon production process S20, as well as the carbon dioxide produced in the combustion process, to the dry reforming process S10. The amount of carbon dioxide supplied to the dry reforming process S10 can be increased by the combustion process. Therefore, coking generation and carbon dioxide shortage in the dry reforming process S10 can be further suppressed, enabling the efficient production of the target useful hydrocarbons over a long period of time. In addition, the heat generated in the combustion process can be recovered and used in the dry reforming process S10 and the useful hydrocarbon production process S20.

[0066] Furthermore, it is preferable to adjust the combustion rate of the combustion process according to the ratio of lower hydrocarbons to carbon dioxide in the hydrocarbons supplied to the dry reforming process S10. The combustion rate of the combustion process is the ratio of hydrocarbons other than the target useful hydrocarbon component in the second gas that are burned and converted into carbon dioxide, as shown in equation (4) below, and can be calculated from the following equation. For example, if the combustion rate of the combustion process is 100%, the combustion process burns all hydrocarbons other than the target useful hydrocarbon component in the second gas to produce carbon dioxide.

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

[0068] Burnup rate (%) = 100 - (Total amount of hydrocarbons (C-mol) excluding the target useful hydrocarbon components burned in the combustion process × 100 / Total amount of hydrocarbons (C-mol) excluding the target useful hydrocarbon components in the second gas)

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

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

[0071] Furthermore, the method for producing useful hydrocarbons in the embodiment may include a desulfurization step (not shown) for desulfurizing biogas when biogas is supplied to the dry reforming step S10. The desulfurization step is performed before the dry reforming step S10. Biogas contains sulfur components such as sulfur compounds like hydrogen sulfide. Sulfur components in 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 biogas in the desulfurization step, the reduction in catalytic performance of the dry reforming catalyst and the useful hydrocarbon production catalyst can be suppressed. Therefore, the desired useful hydrocarbons can be produced stably over a long period of time.

[0072] Furthermore, the method for producing useful hydrocarbons in the embodiment may include 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 carried out in the useful hydrocarbon production step S20 can be improved, and furthermore, the decrease in catalytic performance of the catalyst for useful hydrocarbon production due to moisture can be suppressed.

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

[0074] Furthermore, the useful hydrocarbon produced by the method for producing useful hydrocarbons 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.

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

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

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

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

[0079] For such catalysts, it is preferable that the ZSM-5 type zeolite catalyst material contains phosphorus (P). When the ZSM-5 type zeolite catalyst material contains P, the acidity of the ZSM-5 type zeolite catalyst material can be appropriately controlled, thereby suppressing the growth of excessive hydrocarbon chains and increasing the amount of olefins such as ethylene and propylene produced.

[0080] Furthermore, for such catalysts, the ratio of moles of SiO2 to moles of Al2O3 (moles of SiO2 / moles of Al2O3) in the ZSM-5 type zeolite catalyst material is preferably between 20 and 60. By replacing some of the silicon atoms in the silicate that constitutes the zeolite skeleton of the ZSM-5 type zeolite catalyst material with aluminum atoms, the aluminum atoms become acid sites, and the zeolite catalyst material exhibits the function of a solid acid. If the above ratio is 60 or less, the number of acid sites in the ZSM-5 type zeolite catalyst material increases, thereby increasing the amount of olefins produced. If the above ratio is 20 or more, catalyst degradation such as coking caused by an excessive number of acid sites can be suppressed.

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

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

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

[0084] The proportion of olefins contained in the second gas can be appropriately adjusted depending on 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 the hydrocarbons other than the target olefin and carbon monoxide. When the carbon dioxide-containing gas contains the above substances, the yield of olefins is significantly improved.

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

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

[0088] For such catalysts, it is preferable that the ZSM-5 type zeolite catalyst material supports one or more of the following as active metal oxides: MnO, MnCr2O4, MnAl2O4, MnZrO4, ZnO, ZnCr2O4, and ZnAl2O4. It is preferable that it supports one or more of the following: MnO, MnCr2O4, MnAl2O4, and MnZrO4. When the ZSM-5 type zeolite catalyst material supports the above metal oxides, the amount of aromatic hydrocarbons produced can be increased.

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

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

[0091] The pressure for the aromatic hydrocarbon synthesis reaction is preferably between 0.1 MPa and 6.0 MPa.

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

[0093] The proportion of aromatic hydrocarbons contained in the second gas can be appropriately adjusted depending on 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 the hydrocarbons other than the target aromatic hydrocarbon and carbon monoxide. When the carbon dioxide-containing gas contains the above substances, the yield of aromatic hydrocarbons is significantly improved.

[0095] Furthermore, for example, when producing gasoline as a useful hydrocarbon, in the useful hydrocarbon production step S20, a useful hydrocarbon production catalyst (gasoline production catalyst) is used to synthesize gasoline from carbon monoxide and hydrogen contained in the first gas to carry out a gasoline synthesis reaction. In the useful hydrocarbon production step S20, the gasoline production catalyst is heated while the first gas is supplied to it, so that the carbon monoxide and hydrogen in the supplied first gas react with the gasoline production catalyst to produce a second gas containing gasoline.

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

[0097] Furthermore, for such catalysts, the ratio of moles of SiO2 to moles of Al2O3 (moles of SiO2 / moles of Al2O3) in the ZSM-5 type zeolite catalyst material is preferably at least 12. The ZSM-5 type zeolite catalyst material also has a pore size formed by up to 12-membered rings, more preferably up to 10-membered rings. By replacing some of the silicon atoms in the silicate constituting the zeolite skeleton of the ZSM-5 type zeolite catalyst material with aluminum atoms, the aluminum atoms become acid sites, and the zeolite catalyst material exhibits the function of a solid acid. With a ZSM-5 type zeolite catalyst material as described above, the amount of gasoline produced can be increased. Examples of such ZSM-5 type zeolite catalyst materials include ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, and ZSM-38.

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

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

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

[0101] The proportion of gasoline contained in the second gas can be adjusted as appropriate by the conditions of the gasoline synthesis reaction, such as the heating temperature of the gasoline 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 the hydrocarbons other than the target gasoline and carbon monoxide. When the carbon dioxide-containing gas contains the above substances, the gasoline yield is significantly improved.

[0103] Furthermore, for example, when producing liquefied petroleum gas as a useful hydrocarbon, in the useful hydrocarbon production step S20, a catalyst for useful hydrocarbon production (LPG production catalyst) is used to synthesize liquefied petroleum gas from carbon monoxide and hydrogen contained in the first gas, and the liquefied petroleum gas synthesis reaction is carried out. In the useful hydrocarbon production step S20, the first gas is supplied to the LPG production catalyst, and the LPG production catalyst is heated, causing the carbon monoxide and hydrogen in the supplied first gas to react with the LPG production catalyst to produce a second gas containing liquefied petroleum gas.

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

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

[0106] Furthermore, it is preferable that such a catalyst contains phosphorus (P) in the ZSM-5 type zeolite catalyst material. When the ZSM-5 type zeolite catalyst material contains P, the acidity of the ZSM-5 type zeolite catalyst material can be appropriately controlled, thereby increasing the amount of liquefied petroleum gas produced and the proportion of propane.

[0107] Furthermore, for such catalysts, the ratio of moles of SiO2 to moles of Al2O3 (moles of SiO2 / moles of Al2O3) in the ZSM-5 type zeolite catalyst material is preferably between 20 and 60. By replacing some of the silicon atoms in the silicate that constitutes the zeolite skeleton of the ZSM-5 type zeolite catalyst material with aluminum atoms, the aluminum atoms become acid sites, and the zeolite catalyst material exhibits the function of a solid acid. If the above ratio is 60 or less, the number of acid sites in the ZSM-5 type zeolite catalyst material increases, which can increase the amount of liquefied petroleum gas produced and the propane content. If the above ratio is 20 or more, catalyst degradation such as coking caused by an excessive number of acid sites can be suppressed.

[0108] The heating temperature of the LPG production catalyst is set appropriately depending on the type of LPG production catalyst, the amount of first gas supplied, etc. For example, the heating temperature of the LPG production catalyst is between 240°C and 350°C.

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

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

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

[0112] When the useful hydrocarbon is liquefied petroleum gas, the carbon dioxide-containing gas preferably contains hydrocarbons other than those with 3 to 4 carbon atoms, more preferably contains at least one of hydrocarbons with 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] Furthermore, for example, when producing liquid hydrocarbons as useful hydrocarbons, in the useful hydrocarbon production step S20, a useful hydrocarbon production catalyst (liquid hydrocarbon production catalyst) is used to synthesize liquid hydrocarbons from carbon monoxide and hydrogen contained in the first gas, and a liquid hydrocarbon synthesis reaction is carried out. In the useful hydrocarbon production step S20, the first gas is supplied to the liquid hydrocarbon production catalyst, and the liquid hydrocarbon production catalyst is heated, so that the carbon monoxide and hydrogen in the supplied first gas react with the liquid hydrocarbon production catalyst to produce a second gas containing liquid hydrocarbons.

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

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

[0116] Furthermore, the FT synthesis catalyst may be a catalyst structure listed as a preferred example of a dry reforming catalyst, and may contain Co encapsulated within it.

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

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

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

[0120] The proportion of liquid hydrocarbons contained in the second gas can be appropriately adjusted depending on 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 a hydrocarbon with four or fewer 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] [Equipment for the production of useful hydrocarbons] Next, the apparatus for producing useful hydrocarbons according to the embodiment will be described. Figure 2 is a schematic diagram showing an example of the apparatus for producing useful hydrocarbons according to the embodiment. The apparatus for producing useful hydrocarbons according to the embodiment 1 is an apparatus for producing useful hydrocarbons according to the above embodiment.

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

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

[0125] When a mixed gas is supplied to the dry reforming unit 2, which is equipped with a heated dry reforming catalyst, the dry reforming unit 2 reacts the methane-containing hydrocarbons and carbon dioxide in the mixed gas with the dry reforming catalyst to produce 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 useful hydrocarbon production unit 3, which constitutes the useful hydrocarbon production apparatus 1, is supplied with the first gas produced in the dry reforming unit 2. The useful hydrocarbon production unit 3 includes a useful hydrocarbon production catalyst (not shown) and a heating unit (not shown) for heating the useful hydrocarbon production catalyst. For example, the heating unit is a heating furnace. The useful hydrocarbon production catalyst is heated to a predetermined temperature by the heating unit.

[0127] When the first gas is supplied to the useful hydrocarbon production unit 3, which is equipped with a catalyst for generating useful hydrocarbons in a heated state, the useful hydrocarbon production unit 3 reacts carbon monoxide and hydrogen in the first gas with the catalyst for generating useful hydrocarbons to produce a second gas containing the desired useful hydrocarbons. In this way, a useful hydrocarbon synthesis reaction is carried out in the useful hydrocarbon production unit 3 with respect to the first gas.

[0128] The recycling unit 4, which constitutes the useful hydrocarbon production apparatus 1, separates carbon dioxide-containing gas from the second gas produced in the useful hydrocarbon generation unit 3 and supplies the carbon dioxide-containing gas to the dry reforming unit 2. By supplying the carbon dioxide-containing gas separated from the second gas discharged from the useful hydrocarbon generation unit 3 to the dry reforming unit 2 via the recycling unit 4, coking generation and carbon dioxide deficiency in the dry reforming unit 2 can be suppressed. Therefore, the desired useful hydrocarbons can be produced efficiently over a long period of time.

[0129] Furthermore, the recycling unit 4 supplies the mixed gas to the dry reforming unit 2 with a total number of carbon moles M of carbon dioxide in the mixed gas and the carbon dioxide-containing gas. CO2 Total number of carbon moles M of hydrocarbons supplied to the dry reforming section 2 HC The ratio (M HC / M CO2 It is preferable to adjust the amount of carbon dioxide-containing gas supplied to the dry reforming section 2 according to the following. The hydrocarbons supplied to the dry reforming section 2 are methane-containing hydrocarbons in the mixed gas and hydrocarbons contained in the carbon dioxide-containing gas.

[0130] Carbon molar ratio (M) in dry reforming section 2 HC / M CO2 If the carbon molar ratio (M) is large, it may cause coking and carbon dioxide deficiency in the dry reforming section 2. Therefore, the carbon molar ratio (M) in the dry reforming section 2 should be large. HC / M CO2 When the ) is large, increasing the amount of carbon dioxide-containing gas supplied by the recycling unit 4 to the dry reforming unit 2 can suppress coking generation and carbon dioxide deficiency in the dry reforming unit 2.

[0131] Thus, the carbon molar ratio (M) in the dry reforming section 2 HC / M CO2When the carbon molar ratio (M) in the dry reforming section 2 is large, the amount of carbon dioxide-containing gas supplied by the recycling section 4 to the dry reforming section 2 is increased. HC / M CO2 By adjusting the amount of carbon dioxide-containing gas supplied from the recycling unit 4 to the dry reforming unit 2 according to the ratio (M) in the dry reforming unit 2, the target useful hydrocarbons can be produced more efficiently. HC / M CO2 The above effects can be further improved by controlling the value of ) to preferably 1.30 or less, and more preferably 1.00 or less.

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

[0133] Furthermore, the useful hydrocarbon production apparatus 1 of the embodiment may further include a mixed gas generation unit (not shown). The mixed gas generation unit generates a mixed gas containing methane-containing hydrocarbons and carbon dioxide and supplies it to the dry reforming unit 2. The mixed gas generation unit preferably performs a thermal decomposition treatment using biomass resources such as woody biomass or waste plastics as raw materials, or a gasification treatment in which these raw materials are oxidatively decomposed by adding an oxidizing agent (H2O, oxygen, or carbon dioxide).

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

[0135] In this embodiment, the useful hydrocarbon production apparatus 1 may include a separation unit between the mixed gas generation unit and the dry reforming unit 2 for separating carbon monoxide and hydrogen from a gas containing hydrocarbons and carbon dioxide.

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

[0137] Furthermore, the useful hydrocarbon production apparatus 1 of the embodiment preferably further includes a hydrogen supply unit 5 that separates hydrogen from the second gas produced in the useful hydrocarbon production unit 3 and supplies it to the useful hydrocarbon production unit 3. By supplying hydrogen, which is an impurity in the second gas discharged from the useful hydrocarbon production unit 3, to the useful hydrocarbon production unit 3 via the hydrogen supply unit 5, hydrogen deficiency in the useful hydrocarbon production unit 3 can be suppressed. As a result, the target useful hydrocarbon can be produced efficiently 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 burden can be reduced.

[0138] Furthermore, the hydrogen supply unit 5 controls the number of moles M of hydrogen in the useful hydrocarbon generation unit 3. H It is preferable to adjust the amount of hydrogen supplied to the useful hydrocarbon generation unit 3 accordingly, and the above number of moles M H Furthermore, it is more preferable to adjust the amount of hydrogen supplied to the useful hydrocarbon generation unit 3 depending on the type of useful hydrocarbon to be produced and the reaction.

[0139] For example, when producing liquefied petroleum gas as a useful hydrocarbon, the number of moles M of hydrogen in the useful hydrocarbon generation section 3. HIf the amount is insufficient, a hydrogen deficiency may occur in the useful hydrocarbon generation section 3. Therefore, the number of moles of hydrogen M in the useful hydrocarbon generation section 3 is important. H When the hydrogen supply is low, increasing the amount of hydrogen supplied by the hydrogen supply unit 5 to the useful hydrocarbon generation unit 3 can suppress hydrogen deficiency in the useful hydrocarbon generation unit 3.

[0140] Thus, the number of moles of hydrogen M in the useful hydrocarbon generation section 3. H When the amount of hydrogen supplied by the hydrogen supply unit 5 to the useful hydrocarbon generation unit 3 is small, the amount of hydrogen supplied by the hydrogen supply unit 5 to the useful hydrocarbon generation unit 3 is increased, and so on. H By adjusting the amount of hydrogen supplied by the hydrogen supply unit 5 to the useful hydrocarbon production unit 3 accordingly, the desired useful hydrocarbons can be produced more efficiently.

[0141] Furthermore, the hydrogen supply unit 5 controls the number of moles M of carbon monoxide in the useful hydrocarbon generation unit 3. CO The number of moles of hydrogen M H Mole ratio (M H / M CO It is preferable to adjust the amount of hydrogen supplied to the useful hydrocarbon generation unit 3 according to the following.

[0142] Molar ratio of useful hydrocarbon generation section 3 (M H / M CO Regarding this, if the ratio of hydrogen to carbon monoxide is very low, a hydrogen deficiency may occur. Therefore, the molar ratio (M) in the useful hydrocarbon generation section 3 is important. H / M CO When the molar ratio (M) in the useful hydrocarbon production unit 3 is very low, increasing the amount of hydrogen supplied by the hydrogen supply unit 5 to the useful hydrocarbon production unit 3 can suppress hydrogen deficiency in the useful hydrocarbon production unit 3. H / M CO By adjusting the amount of hydrogen supplied by the hydrogen supply unit 5 to the useful hydrocarbon generation unit 3 in accordance with the conditions, hydrogen deficiency in the useful hydrocarbon generation unit 3 can be more reliably suppressed.

[0143] In addition, 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 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.

[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 is preferably 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.

[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.

[0146] <00^00583>In addition, 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. <00^00585> ​​​​In the combustion section, carbon-containing substances in the second gas discharged from the useful hydrocarbon generation section 3 are separated from the second gas, and the separated carbon-containing substances are burned to produce carbon dioxide. The carbon-containing substances 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 hydrocarbon. The carbon-containing substances burned in the combustion section may or may not include carbon dioxide.

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

[0149] Furthermore, it is preferable to adjust the combustion rate of the combustion section according to the ratio of hydrocarbons to 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, by adjusting the combustion rate of the combustion section according to the ratio of hydrocarbons to carbon dioxide supplied to the dry reforming section 2, the amount of carbon dioxide generated can be adjusted, and the amount of carbon dioxide supplied to the dry reforming section 2 in the recycling section 4 can be adjusted, thereby increasing the amount of useful hydrocarbons produced.

[0150] If the combustion rate of the combustion section is 3% or higher, the carbon dioxide deficiency in the dry reforming section 2 can be sufficiently suppressed. Furthermore, if the combustion rate of the combustion section is 50% or lower, the ratio of hydrocarbons to carbon dioxide supplied to the dry reforming section 2 is favorable. Therefore, if the combustion rate of the combustion section is between 3% and 50%, the desired useful hydrocarbons can be produced efficiently over a long period of time.

[0151] Furthermore, the useful hydrocarbon production apparatus 1 of this embodiment may include a desulfurization unit (not shown) for desulfurizing biogas when biogas is supplied to the dry reforming unit 2. The desulfurization unit is connected to the upstream side of the dry reforming unit 2. Sulfur components in biogas reduce 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 desulfurizing the biogas with the desulfurization unit, the reduction in catalytic performance of the dry reforming catalyst and the useful hydrocarbon production catalyst can be suppressed. Therefore, the desired useful hydrocarbons can be produced stably over a long period of time.

[0152] Furthermore, the useful hydrocarbon production apparatus 1 of the embodiment may also include 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 dehydrating the first gas with the dehydration unit, the efficiency of the useful hydrocarbon synthesis reaction carried out in the useful hydrocarbon production unit 3 can be improved, and furthermore, the decrease in catalytic performance of the catalyst for useful hydrocarbon production due to moisture can be suppressed.

[0153] Furthermore, the useful hydrocarbon production apparatus 1 of the embodiment may also include a compression unit (not shown) for compressing the first gas produced 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 compressing the first gas with the compression unit, the compressed first gas is supplied to the useful hydrocarbon production unit 3, thereby improving the efficiency of the synthesis reaction of the target useful hydrocarbon carried out in the useful hydrocarbon production unit 3.

[0154] Furthermore, the useful hydrocarbons produced by the useful hydrocarbon production apparatus 1 are the same as the useful hydrocarbons produced by the above-described method for producing useful hydrocarbons, and 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.

[0155] In the useful hydrocarbon production apparatus 1, depending on the type of useful hydrocarbon to be produced, a hydrocarbon mixture mainly composed of the desired useful hydrocarbon can be synthesized from carbon monoxide and hydrogen by various useful hydrocarbon synthesis reactions in the useful hydrocarbon production section 3 under appropriate catalysts and reaction conditions. The various useful hydrocarbon synthesis reactions carried out in the useful hydrocarbon production section 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 embodiments described above, by focusing on the fact that carbon dioxide, an impurity, is contained in the second gas obtained in the dry reforming process, which can produce carbon monoxide and hydrogen from methane-containing hydrocarbons and carbon dioxide that can be obtained relatively easily, and by supplying the carbon dioxide in the second gas to the dry reforming process for reuse, it is possible to efficiently produce the target useful hydrocarbons over a long period of time using easily obtainable raw materials.

[0157] Furthermore, the technology of this disclosure can be suitably applied to natural gas containing a large amount of carbon dioxide as an impurity, which is produced from gas fields in Indonesia and Malaysia, where natural gas reserves are abundant, and where the cost of processing impurities has become a problem in recent years. By using a gas with a methane / carbon dioxide ratio of 1 to 9 on a molar basis as a raw material instead of the above-mentioned mixed gas, and performing a dry reforming process to produce a first gas containing carbon monoxide and hydrogen from this gas, a large amount of carbon dioxide can be efficiently supplied to the dry reforming process. This allows for the efficient production of the target useful hydrocarbons over a long period of time, and also eliminates the problem of processing costs for gases containing a large amount of carbon dioxide as an impurity.

[0158] Although embodiments have been described above, the present invention is not limited to the embodiments described above, and includes all aspects included in the concepts and claims of this disclosure, and can be modified in various ways within the scope of this 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 Figure 2, liquefied petroleum gas, a useful hydrocarbon, was produced using the manufacturing method shown in Figure 1. Specifically, the process was as follows:

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

[0162] The useful hydrocarbon production section 3 used a fixed-bed flow reactor. A stainless steel reaction tube was used. As described above, in the dry reforming section 2, carbon monoxide and hydrogen are produced at the same ratio. Therefore, assuming that hydrogen is not supplied from the hydrogen supply section 5, a first gas with the same molar ratio of carbon monoxide and hydrogen was supplied to the useful hydrocarbon production section 3. The flow rate of the first gas supplied to the useful hydrocarbon production section 3 was set to 37.2 ml / min. 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. For 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 at a weight ratio of 1:1 was used. The heating temperature of the LPG production catalyst was set to 280°C. The pressure inside the useful hydrocarbon production section 3 was set to 5.0 MPa. The second gas produced in the useful hydrocarbon production section 3 was collected with a gas pack and analyzed by GC-TCD and FID. In addition, 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, it was a method assuming that carbon dioxide was not supplied from the recycling section 4.

[0164] Regarding the ranking of the syngas yield in Table 1, when the syngas yield is 1.20 kg / Nm 3 or more is considered "good", and when the syngas yield is less than 1.20 kg / Nm 3 it is considered "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 embodiment where carbon dioxide is supplied from the recycling unit 4 to the dry reforming unit 2, the synthesis gas yield was increased compared to the comparative example because the carbon molar ratio of hydrocarbons to carbon dioxide in the inlet gas of the dry reforming process was better. At this time, the synthesis gas yield was good when the carbon molar ratio of hydrocarbons to carbon dioxide was 1.30 or less. More preferably, when it was 1.00 or less, catalyst degradation was also well suppressed, suggesting that synthesis gas could be produced efficiently over a long period of time and the yield of useful hydrocarbons could be increased.

[0167] Furthermore, as shown in Examples 1-5, in order to appropriately adjust the carbon molar ratio of hydrocarbons / carbon dioxide as described above, if the carbon dioxide concentration in the recycled gas is 50% or higher, the amount of carbon dioxide necessary to properly adjust the carbon molar ratio of hydrocarbons / carbon dioxide can be secured by adjusting the amount of recycled gas in the recycling process.

[0168] As described above, it was suggested that maintaining favorable CO2 concentration in the recycled gas and the hydrocarbon / carbon dioxide molar ratio in the inlet gas of the dry reforming process can enable efficient synthesis gas production over the long term and increase the yield of useful hydrocarbons.

[0169] (Examples 2-3) The procedure was the same as in Example 1-1, except that the first gas had the molar ratio of carbon monoxide to hydrogen shown in Table 2. In other words, in Examples 2 and 3, hydrogen was supplied from the hydrogen supply unit 5.

[0170] [Table 2]

[0171] As shown in Table 2, hydrogen is supplied from the hydrogen supply unit 5. one By doubling the molar ratio of hydrogen to carbon oxide, 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 rate shown in Table 3 to adjust the amount of carbon dioxide supplied from the recycling unit 4 to the dry reforming unit 2. Then, the total amount of hydrocarbons excluding liquefied petroleum gas components in the second gas and the amount of carbon dioxide in the second gas were measured, and the ratio of total hydrocarbons excluding liquefied petroleum gas components to carbon dioxide in the second gas was calculated. In Example 3-1, the combustion unit was not operated.

[0173] [Table 3]

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

[0175] From the above, it is suggested that liquefied petroleum gas can be efficiently produced over a long period of time using readily available raw materials, as demonstrated by the above examples.

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

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

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

[0179] (Example 7) The catalyst for generating useful hydrocarbons (liquid hydrocarbon catalyst) to be packed into the useful hydrocarbon generation section 3 is 0.5 wt% Co-supported SiO2, with a reaction temperature of 230°C and GHSV = 3000. h-1 Liquid hydrocarbons were produced in the same manner as in the above example, except that the pressure was set to 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] In Kumagai et al., "Chemical raw material conversion by co-thermal decomposition of woody biomass / waste plastic mixture," Journal of the Japan Society of Waste Management and Resource Recycling, Vol. 28, No. 1, pp. 4-12, 2017, it is reported that the gas composition obtained by thermal decomposition of woody biomass is (1) in Table 5 (all C2-C4 components are converted as C2). In this case, assuming that only methane and ethane hydrocarbons are produced, it can be seen that by adding recycled gas (2) in the recycling process to the gas component (1) after thermal decomposition, the concentration can be adjusted to the composition (3) in Table 5, and the carbon molar ratio of hydrocarbons to carbon dioxide can be adjusted to a suitable value equivalent to that of the above example in Table 1.

[0183] As described above, the above embodiments and examples are applicable to a variety of raw materials, such as biogas obtained by methane fermentation of organic waste such as livestock manure, woody biomass, and gas obtained by thermal decomposition and gasification of waste plastics.

[0184] [Table 5] [Explanation of Symbols]

[0185] 1. Equipment for producing useful hydrocarbons 2. Dry reforming section 3. Useful hydrocarbon generation section 4. Recycling Department 5. Hydrogen Supply Unit

Claims

1. A dry reforming process that generates a first gas containing carbon monoxide and hydrogen from a mixed gas containing methane-containing hydrocarbons and carbon dioxide using a dry reforming catalyst, A liquefied petroleum gas production step, which involves generating a second gas containing liquefied petroleum gas from carbon monoxide and hydrogen in the first gas using a catalyst for liquefied petroleum gas production, A hydrogen supply process that separates a hydrogen-containing off-gas from the second gas and supplies it to the liquefied petroleum gas production process so that the number of moles of hydrogen in the liquefied petroleum gas production process is twice the number of moles of carbon monoxide. A method for producing liquefied petroleum gas having [a specific characteristic].

2. The hydrogen supply process involves the number of moles M of hydrogen in the liquefied petroleum gas production process. Ｈ A method for producing liquefied petroleum gas according to claim 1, wherein the amount of hydrogen supplied to the liquefied petroleum gas production process is adjusted accordingly.

3. The number of moles of carbon monoxide M contained in the first gas obtained in the dry reforming step. ＣＯ The number of moles of hydrogen M Ｈ Mole ratio (M Ｈ / M ＣＯ A method for producing liquefied petroleum gas according to claim 1 or 2, further comprising an adjustment step for adjusting ).

4. A method for producing liquefied petroleum gas according to any one of claims 1 to 3, further comprising a recycling step of separating a carbon dioxide-containing gas from the second gas and supplying it to the dry reforming step.

5. The total carbon mole number M of carbon dioxide in the mixed gas supplied to the dry reforming process and carbon dioxide in the carbon dioxide-containing gas ＣＯ２ to the total carbon mole number M of the hydrocarbon supplied to the dry reforming process ＨＣ The ratio (M ＨＣ / M ＣＯ２ ) is 1.30 or less. The method for producing liquefied petroleum gas according to claim 4

6. The method for producing liquefied petroleum gas according to any one of claims 1 to 5, wherein the carbon dioxide conversion rate of the dry reforming step is 82% or more.

7. The method for producing liquefied petroleum gas according to any one of claims 1 to 6, wherein the dry reforming catalyst comprises at least one selected from Ir, Ru, Rh, Pt, Pd, Ni, Co, and Fe.

8. The dry reforming catalyst is MgO, Al ２ O ３ SiO ２ , CEO ２ CaO, ZrO ２ , TiO ２ La ２ O ３ A method for producing liquefied petroleum gas according to any one of claims 1 to 7, comprising at least one selected from ZnO, silicalite-1, MCM-41, and SBA-15.

9. The method for producing liquefied petroleum gas according to any one of claims 1 to 8, wherein the catalyst for producing liquefied petroleum gas comprises a catalyst for methanol synthesis and a ZSM-5 type zeolite catalyst.

10. A method for producing liquefied petroleum gas according to any one of claims 1 to 9, wherein the heating temperature of the dry reforming catalyst is 400°C or more and 1000°C or less.

11. The method for producing liquefied petroleum gas according to any one of claims 1 to 10, wherein the heating temperature of the catalyst for producing liquefied petroleum gas is 240°C or higher and 350°C or lower.

12. The method for producing liquefied petroleum gas according to any one of claims 1 to 11, wherein the reaction pressure in the liquefied petroleum gas production step is 2.0 MPa or more and 6.0 MPa or less.

13. The hydrogen supply process involves the number of moles M of carbon monoxide in the liquefied petroleum gas production process. ＣＯ The number of moles of hydrogen M Ｈ Mole ratio (M Ｈ / M ＣＯ A method for producing liquefied petroleum gas according to any one of claims 1 to 12, wherein the supply amount of the off-gas containing hydrogen is increased when the ratio is less than twice.

14. A method for producing liquefied petroleum gas according to any one of claims 1 to 13, further comprising supplying steam to the dry reforming step.

15. The method for producing liquefied petroleum gas according to any one of claims 1 to 14, wherein the dry reforming step is performed using a fixed-bed reactor.

16. A dry reforming section that generates a first gas containing carbon monoxide and hydrogen from a mixed gas containing methane-containing hydrocarbons and carbon dioxide using a dry reforming catalyst, A liquefied petroleum gas generation unit is supplied with the first gas generated in the dry reforming unit, and generates a second gas containing liquefied petroleum gas from carbon monoxide and hydrogen in the first gas using a catalyst for liquefied petroleum gas generation, A hydrogen supply unit separates a hydrogen-containing off-gas from the second gas produced in the liquefied petroleum gas production unit and supplies it to the liquefied petroleum gas production unit so that the number of moles of hydrogen in the liquefied petroleum gas production unit is twice the number of moles of carbon monoxide. A liquefied petroleum gas manufacturing apparatus equipped with [a specific feature].

Images