Liquid fuel production system and liquid fuel production method

Abstract

The main purpose of the present invention is to prevent the deterioration in reaction yield in a conversion reaction from a raw material gas comprising hydrogen and carbon oxide to a liquid fuel. A liquid fuel production system according to an embodiment of the present invention is provided with: a liquid fuel synthesis unit which allows a conversion reaction from a raw material gas containing at least hydrogen and carbon oxide to a liquid fuel to proceed; a raw material gas supply unit which supplies the raw material gas into the liquid fuel synthesis unit; and a raw material gas circulation unit which re-supplies a remaining portion of the raw material gas, which contains an unreacted portion of the hydrogen, an unreacted portion of the carbon oxide and an acidic by-product of the conversion reaction, from the liquid fuel synthesis unit into the raw material gas supply unit. In the liquid fuel production system, the raw material gas supply unit includes: a mixing unit which mixes an amine compound with the remaining portion of the raw material gas in the presence of water vapor; and a water removal unit which removes a neutralization product between the amine compound and the acidic by-product together with condensed water of the water vapor.

Description

[Technical Field]

[0001] The present invention relates to a liquid fuel production system and a method for producing liquid fuel. [Background technology]

[0002] In recent years, with the aim of realizing a carbon-neutral society, it has been proposed to treat carbon oxides as a carbon resource and convert it into liquid fuel that is useful as a basic industrial raw material. For example, Patent Document 1 discloses a liquid fuel production system that uses a membrane reactor including a catalyst and a water vapor separation membrane to carry out a conversion reaction of a feed gas containing hydrogen and carbon dioxide into methanol. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-8940 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conversion reaction from a feed gas containing hydrogen and carbon dioxide to a liquid fuel as described above, the reaction yield may deteriorate. Specifically, in the conversion reaction, from the viewpoint of energy conservation, the unreacted feed gas is recovered from a liquid fuel production system and resupplied as the feed gas to the liquid fuel production system, thereby recycling the feed gas. However, in the recycling of the feed gas, acidic by-products produced in the conversion reaction accumulate as the number of circulations increases, which may result in a deterioration in the reaction yield.

[0005] A main object of the present invention is to suppress a decrease in reaction yield in a conversion reaction from a feed gas containing hydrogen and carbon oxides to a liquid fuel. [Means for solving the problem]

[0006] [1] According to one aspect of the present invention, there is provided a liquid fuel production system comprising: a liquid fuel synthesis unit that promotes a conversion reaction from a feed gas containing at least hydrogen and carbon oxides to a liquid fuel; a feed gas supply unit that supplies the feed gas to the liquid fuel synthesis unit; and a feed gas circulation unit that re-supplies a remaining feed gas containing unreacted hydrogen and carbon oxides and acidic by-products of the conversion reaction from the liquid fuel synthesis unit to the feed gas supply unit; wherein the feed gas supply unit has a mixing unit that mixes an amine compound with the remaining feed gas in the presence of water vapor, and a water removal unit that removes a neutralized product of the amine compound and the acidic by-products together with water condensed from the water vapor. [2] In the liquid fuel production system described in [1] above, the neutralization raw material gas containing the amine compound may be mixed with the remaining raw material gas in the mixing section. [3] In the liquid fuel production system described in [1] above, the raw material gas may further contain nitrogen, and the amine compound may be ammonia produced from the hydrogen and the nitrogen in the liquid fuel synthesis section. [4] The liquid fuel production system described in [2] above may further include a gas recovery unit that recovers carbon dioxide from the atmosphere or biogas, and the carbon dioxide-containing gas supplied from the gas recovery unit may be used as a constituent component of the neutralization raw material gas. [5] In the liquid fuel production system described in [2] or [4] above, the liquid fuel synthesis unit may have a water vapor separation membrane that is permeable to at least water vapor, and may separate a permeate side gas that has permeated the water vapor separation membrane from the non-permeate side to the permeate side and contains water vapor as a by-product of the conversion reaction, from a non-permeate side gas that has not permeated the water vapor separation membrane and contains the liquid fuel, unreacted hydrogen and carbon oxides, and the acidic by-products.The liquid fuel production system may further include a sweep gas supply unit that supplies a sweep gas that sweeps the permeate side gas and contains an amine compound to the permeate side of the liquid fuel synthesis unit, and the permeate side gas and sweep gas that have flowed out of the liquid fuel synthesis unit may be supplied to the mixing unit. [6] In the liquid fuel production system described in [5] above, the sweep gas may further contain carbon oxides and / or hydrogen. [7] In the liquid fuel production system according to the above [5] or [6], the concentration of the amine compound in the sweep gas may be 10 ppm or more. [8] In the liquid fuel production system described in [3] above, the liquid fuel synthesis unit may have a water vapor separation membrane that allows at least water vapor and ammonia to permeate, and may separate a permeate side gas that permeates the water vapor separation membrane from the non-permeate side to the permeate side and contains water vapor and ammonia as by-products of the conversion reaction, from a non-permeate side gas that does not permeate the water vapor separation membrane and contains the liquid fuel, unreacted hydrogen and carbon oxides, and the acidic by-products.The liquid fuel production system may further include a sweep gas supply unit that supplies a sweep gas that sweeps the permeate side gas to the permeate side of the liquid fuel synthesis unit, and the permeate side gas and sweep gas that flow out of the liquid fuel synthesis unit may be supplied to the mixing unit. [9] In the liquid fuel production system described in [8] above, the ammonia concentration in the mixed gas of the permeate side gas and the sweep gas may be 10 ppm or more.

[10] In the liquid fuel production system according to [2] or [4] above, The liquid fuel synthesis section may have a liquid fuel separation membrane that allows at least liquid fuel to permeate, and may separate a permeate side gas that has permeated the liquid fuel separation membrane from the non-permeate side to the permeate side and contains the liquid fuel, from a non-permeate side gas that has not permeated the liquid fuel separation membrane and contains water vapor, which is a by-product of the conversion reaction, the unreacted hydrogen and carbon oxides, and the acidic by-products.The liquid fuel production system may further include a sweep gas supply section that supplies a sweep gas that sweeps the permeate side gas and contains an amine compound to the permeate side of the liquid fuel synthesis section, and the sweep gas that flows out from the liquid fuel synthesis section may be supplied to the mixing section.

[11] In the liquid fuel production system described in

[10] above, the sweep gas may further contain carbon oxides and / or hydrogen.

[12] In the liquid fuel production system according to the above

[10] or

[11] , the concentration of the amine compound in the sweep gas may be 10 ppm or more.

[13] In the liquid fuel production system described in [3] above, the liquid fuel synthesis unit may have a liquid fuel separation membrane that allows at least liquid fuel and ammonia to permeate, and may separate a permeate-side gas that permeates the liquid fuel separation membrane from the non-permeate side to the permeate side and contains the liquid fuel and the ammonia, from a non-permeate-side gas that does not permeate the liquid fuel separation membrane and contains water vapor, which is a by-product of the conversion reaction, unreacted hydrogen and carbon oxides, and the acidic by-products. The liquid fuel production system may further include a sweep gas supply unit that supplies a sweep gas that sweeps the permeate-side gas to the permeate side of the liquid fuel synthesis unit, and the permeate-side gas and the sweep gas that flow out of the liquid fuel synthesis unit may be supplied to the mixing unit.

[14] In the liquid fuel production system described in

[13] above, the ammonia concentration in the mixed gas of the permeate side gas and the sweep gas may be 10 ppm or more.

[15] In the liquid fuel production system described in [2] above, the liquid fuel synthesis unit may have a first gas flow path in which a catalyst that promotes the conversion reaction is disposed and a second gas flow path through which a temperature control gas that adjusts the temperature of the first gas flow path flows, and the liquid fuel production system may further include a temperature control gas supply unit that supplies a temperature control gas containing an amine compound to the second gas flow path of the liquid fuel synthesis unit, and the temperature control gas flowing out from the liquid fuel synthesis unit may be supplied to the mixing unit.

[16] In the liquid fuel production system described in

[15] above, the temperature control gas may further contain carbon oxides and / or hydrogen.

[17] In the liquid fuel production system described in

[15] above, the amine compound concentration in the temperature control gas may be 10 ppm or more.

[18] According to another aspect of the present invention, there is provided a method for producing a liquid fuel, the method comprising: supplying a feed gas containing at least hydrogen and carbon oxides to a liquid fuel synthesis section including a catalyst for promoting a conversion reaction from the feed gas to a liquid fuel synthesis section; allowing the conversion reaction to proceed while recovering a residual feed gas containing unreacted hydrogen and carbon oxides and acidic by-products from the liquid fuel synthesis section; removing the acidic by-products from the residual feed gas; and re-supplying the residual feed gas from which the acidic by-products have been removed to the liquid fuel synthesis section as a part of the feed gas; wherein removing the acidic by-products from the residual feed gas comprises mixing an amine compound with the residual feed gas in the presence of water vapor to neutralize the acidic by-products with the amine compound.

[19] In the method for producing a liquid fuel described in

[18] above, removing the acidic by-products from the remaining raw material gas may include mixing the remaining raw material gas with a neutralization raw material gas that is supplied to the liquid fuel synthesis section and contains the amine compound after passing through the liquid fuel synthesis section.

[20] In the method for producing a liquid fuel described in

[18] above, the raw material gas may further contain nitrogen, and the amine compound may be ammonia produced from the hydrogen and the nitrogen in the liquid fuel synthesis section.

[21] In the method for producing a liquid fuel described in

[19] above, the feed gas for neutralization may be prepared using a gas containing carbon dioxide recovered from the atmosphere or biogas.

[22] In the method for producing a liquid fuel according to

[19] or

[21] above, the liquid fuel synthesis section may have a water vapor separation membrane that is permeable to at least water vapor, and the water vapor that is a by-product of the conversion reaction may be permeated from the non-permeation side to the permeation side of the water vapor separation membrane, swept with a sweep gas containing the amine compound, and recovered as an exhaust gas from the liquid fuel synthesis section, and the exhaust gas may be mixed with the remaining raw material gas, and the acidic by-product in the remaining raw material gas may be neutralized with the amine compound.

[23] In the method for producing a liquid fuel according to

[19] or

[21] above, the liquid fuel synthesis section may have a liquid fuel separation membrane that is permeable to at least the liquid fuel, the liquid fuel may be permeated from the non-permeation side to the permeation side of the liquid fuel separation membrane, and may be swept with a sweep gas containing the amine compound, and recovered as a product gas from the liquid fuel synthesis section, and water vapor, which is a by-product of the conversion reaction, may be recovered, and the product gas may be separated into the liquid fuel and the sweep gas, and the sweep gas, the remaining raw material gas, and the water vapor may be mixed, and the acidic by-product in the remaining raw material gas may be neutralized with the amine compound.

[24] In the method for producing a liquid fuel according to the above item

[19] or

[21] , a temperature-controlling gas containing the amine compound for adjusting the reaction temperature of the conversion reaction may be circulated through the liquid fuel synthesis section, and the temperature-controlling gas after circulating through the liquid fuel synthesis section may be mixed with the residual raw material gas to neutralize the acidic by-products in the residual raw material gas with the amine compound.

[25] In the method for producing a liquid fuel described in

[20] above, the liquid fuel synthesis section may have a water vapor separation membrane that is permeable to at least water vapor and ammonia, and the water vapor and ammonia that are by-products of the conversion reaction may be permeated from the non-permeation side to the permeation side of the water vapor separation membrane, swept with a sweep gas, and recovered as exhaust gas from the liquid fuel synthesis section, and the exhaust gas may be mixed with the remaining raw material gas, and the acidic by-products in the remaining raw material gas may be neutralized with the ammonia.

[26] In the method for producing a liquid fuel described in

[20] above, the liquid fuel synthesis section may have a liquid fuel separation membrane that is permeable to at least the liquid fuel and ammonia, and the liquid fuel and the ammonia may be permeated from the non-permeation side to the permeation side of the liquid fuel separation membrane and swept with a sweep gas, and recovered as a product gas from the liquid fuel synthesis section, and water vapor, which is a by-product of the conversion reaction, may be recovered together with the residual raw material gas, and the liquid fuel may be separated from the product gas and then mixed with the residual raw material gas and the water vapor, and the acidic by-product in the residual raw material gas may be neutralized with the ammonia. [Effects of the Invention]

[0007] According to the liquid fuel production system of the present invention, the acidic by-products generated in the conversion reaction are neutralized and removed during the circulation of the feed gas, thereby preventing the deterioration of the reaction yield. Furthermore, while corrosion can occur in the liquid fuel production system due to the acidic by-products, the liquid fuel production method of the present invention can prevent such corrosion. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a liquid fuel production system according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram of a liquid fuel production system according to one embodiment of the present invention. [Figure 3] FIG. 3 is a schematic diagram of a liquid fuel production system according to one embodiment of the present invention. [Figure 4] FIG. 4 is a schematic diagram of a liquid fuel production system according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In addition, in order to clarify the description, the width, thickness, shape, etc. of each part may be shown schematically in the drawings compared to the embodiments, but this is merely an example and does not limit the interpretation of the present invention.

[0010] A. Liquid fuel production system A liquid fuel production system according to an embodiment of the present invention includes: a liquid fuel synthesis unit that converts a feed gas containing at least hydrogen and carbon oxides into a liquid fuel; a raw material gas supply unit that supplies the raw material gas to the liquid fuel synthesis unit; a raw material gas circulation section that re-supplies the remaining raw material gas containing the unreacted hydrogen and carbon oxides and acidic by-products of the conversion reaction from the liquid fuel synthesis section to the raw material gas supply section; Equipped with The raw material gas supply unit a mixing section for mixing an amine compound with the remaining raw material gas in the presence of water vapor; a moisture removal section that removes a neutralized product of the amine compound and the acidic by-product together with condensed water of the water vapor; It has. According to the liquid fuel production system of the embodiment of the present invention, acidic by-products contained in the remaining raw material gas can be neutralized with an amine compound in the presence of water vapor, and the resulting neutralized products can be removed together with condensed water from the water vapor (also referred to as water vapor for removing neutralized products). In one embodiment, the liquid fuel synthesis unit has a separation membrane that separates the liquid fuel from water vapor, which is a by-product of the conversion reaction (also referred to as by-product water vapor).

[0011] FIG. 1 is a schematic diagram of a liquid fuel production system according to one embodiment of the present invention. The liquid fuel production system 1A shown in FIG. 1 includes a liquid fuel synthesis unit 10 that promotes a conversion reaction from a feed gas containing at least hydrogen and carbon oxides to a liquid fuel; a feed gas supply unit 20 that supplies the feed gas to the liquid fuel synthesis unit 10; and a feed gas circulation unit 30 that re-supplies the remaining feed gas containing unreacted hydrogen and carbon oxides and acidic by-products of the conversion reaction from the liquid fuel synthesis unit 10 to the feed gas supply unit 20. The liquid fuel synthesis section 10 has a water vapor separation membrane 14 that allows water vapor to permeate, and separates the gas into a permeation side gas that has permeated the water vapor separation membrane 14 from the non-permeation side to the permeation side and contains water vapor, which is a by-product of the conversion reaction, and a non-permeation side gas that has not permeated the water vapor separation membrane 14 and contains liquid fuel, unreacted hydrogen and carbon oxides, and acidic by-products. The liquid fuel production system 1A further includes a sweep gas supply unit 40 that supplies a gas for sweeping the permeate side gas to the liquid fuel synthesis unit 10. The raw material gas supply unit 20 includes a mixing unit 24 that mixes the amine compound with the remaining raw material gas in the presence of water vapor, and a moisture removal unit 26 that removes a neutralized product of the amine compound and an acidic by-product together with condensed water of the water vapor. According to the liquid fuel production system 1A, a gas containing an amine compound (neutralization raw material gas) is used as the sweep gas, and the sweep gas (neutralization raw material gas) flowing out from the liquid fuel synthesis section 10 is mixed with the water vapor contained in the permeation side gas and the residual raw material gas contained in the non-permeation side gas, thereby neutralizing acidic by-products in the residual raw material gas with the amine compound in the presence of water vapor.

[0012] In this specification, the liquid fuel is a fuel that is in a liquid state at normal temperature and pressure, or a fuel that can be liquefied under normal temperature and pressure. Examples of the fuel that is in a liquid state at normal temperature and pressure include methanol, ethanol, C n H 2(m-2n) (m is an integer less than 90, and n is an integer less than 30), and mixtures thereof. Examples of fuels that can be liquefied under normal temperature and pressure include propane, butane, and mixtures thereof.

[0013] As an example of the conversion reaction, the reaction that may occur when methanol is synthesized by catalytic hydrogenation of a raw material gas containing carbon monoxide, carbon dioxide, and hydrogen in the presence of a catalyst is shown below.

[0014] CO + 2H2 ⇔ CH3OH (1) CO2 + 3H2 ⇔ CH3OH + H2O (2) CO2 + H2 ⇔ CO + H2O (3)

[0015] The above reaction is an equilibrium reaction, and in order to increase both the conversion rate and the reaction rate, it is preferable to carry out the reaction under high temperature and high pressure. The reaction temperature is, for example, 180°C or higher, preferably 200°C or higher and 350°C or lower, and more preferably 200°C or higher and 300°C or lower. The reaction pressure is, for example, 1 MPa (G) or higher, preferably 2.0 MPa (G) or higher and 6.0 MPa (G) or lower, and more preferably 2.5 MPa (G) or higher and 4.0 MPa (G) or lower. The liquid fuel is in a gaseous state when synthesized and remains in this state at least until it flows out of the liquid fuel synthesis section.

[0016] A-1.Liquid fuel synthesis department The liquid fuel synthesis unit 10 is a so-called membrane reactor for converting a raw material gas into a liquid fuel. The shape of the liquid fuel synthesis unit 10 is not particularly limited, and may be, for example, a monolith, a flat plate, a tubular, a cylindrical, a columnar, or a polygonal prism. The monolith shape refers to a shape having multiple cells penetrating in the longitudinal direction, and is a concept that includes a honeycomb shape.

[0017] The liquid fuel synthesis unit 10 has a catalyst 12, a water vapor separation membrane 14, a non-permeation side space 10A, and a permeation side space 10B. In the illustrated example, the water vapor separation membrane 14 is supported by a porous support 16. The liquid fuel synthesis unit 10 is provided with a first supply port s1 and a first discharge port d1 that communicate with each other via the non-permeation side space 10A, and a second supply port s2 and a second discharge port d2 that communicate with each other via the permeation side space 10B. The liquid fuel synthesis unit 10 preferably has heat resistance and pressure resistance suitable for the synthesis conditions of the desired liquid fuel.

[0018] The catalyst 12 promotes the conversion reaction from the raw material gas to liquid fuel. The catalyst is disposed in the non-permeation side space 10A, which is the non-permeation side of the water vapor separation membrane 14. The catalyst is preferably filled in the non-permeation side space 10A, but may also be disposed in the form of layers or islands on the surface of the water vapor separation membrane 14. When the catalyst is in a particulate form as in the illustrated example, the particle size (diameter) of the catalyst particles can be, for example, 0.5 mm or more and 10 mm or less. The catalyst particles may be composed of catalyst alone, or may be configured such that the catalyst is supported on carrier particles. The carrier particles are preferably porous particles.

[0019] Any catalyst suitable for the conversion reaction to the desired liquid fuel can be used as the catalyst. Specifically, metal catalysts (copper, palladium, etc.), oxide catalysts (zinc oxide, zirconia, gallium oxide, etc.), and catalysts made by combining these (copper-zinc oxide, copper-zinc oxide-alumina, copper-zinc oxide-chromium oxide-alumina, copper-cobalt-titania, and catalysts obtained by modifying these with palladium, etc.) can be used.

[0020] The water vapor separation membrane 14 allows water vapor, a by-product of the conversion reaction from the feed gas to liquid fuel, to pass through, thereby utilizing the equilibrium shift effect to shift the reaction equilibrium of the above formula (2) to the product side.

[0021] The molecular diameter of water (0.26 nm) is close to that of hydrogen (0.296 nm), so not only water vapor, which is a by-product of the conversion reaction, but also some of the hydrogen contained in the raw material gas can permeate the water vapor separation membrane 14.

[0022] The water vapor separation membrane 14 has a resistance of 100 nmol / (s·Pa·m 2 The water vapor permeability coefficient can be determined by a known method (see Ind. Eng. Chem. Res., 40, 163-175 (2001)).

[0023] The water vapor separation membrane 14 preferably has a separation factor of 100 or more. The larger the separation factor, the easier it is for water vapor to permeate and the less permeable it is for components other than water vapor (such as hydrogen, carbon oxides, oxygen, and liquid fuel). The separation factor can be determined by a known method (see Fig. 1 in "Separation and Purification Technology 239 (2020) 116533").

[0024] An inorganic membrane can be used as the water vapor separation membrane 14. Inorganic membranes are preferred because they are heat-resistant, pressure-resistant, and water vapor-resistant. Examples of inorganic membranes include zeolite membranes, silica membranes, alumina membranes, and composite membranes of these. For example, an LTA-type zeolite membrane, in which the molar ratio (Si / Al) of silicon element (Si) to aluminum element (Al) is 1.0 or more and 3.0 or less, is preferred because of its excellent water vapor permeability.

[0025] The zeolite membrane used as the water vapor separation membrane 14 can be obtained, for example, by the manufacturing method described in JP 2004-66188 A. The silica membrane used as the water vapor separation membrane 14 can be obtained, for example, by the manufacturing method described in WO 2008 / 050812 A.

[0026] The porous support 16 is made of a porous material. Porous materials that can be used include ceramic materials, metal materials, resin materials, and composite materials of these, with ceramic materials being particularly suitable. Examples of aggregates for ceramic materials include alumina (Al2O3), titania (TiO2), mullite (Al2O3·SiO2), cerium dioxide, and cordierite (Mg2Al4Si5O 18 ), and composite materials containing two or more of these can be used, with alumina being preferred in consideration of availability, clay stability, and corrosion resistance. As the inorganic binder for the ceramic material, at least one of titania, mullite, sinterable alumina, silica, glass frit, clay minerals, and sinterable cordierite can be used. The ceramic material does not necessarily need to contain an inorganic binder.

[0027] The average pore diameter of the porous support can be 5 μm or more and 25 μm or less. The average pore diameter of the porous support can be measured by mercury intrusion porosimetry. The porosity of the porous support can be 25% or more and 50% or less. The average particle diameter of the porous material constituting the porous support can be 1 μm or more and 100 μm or less. In this embodiment, the average particle diameter is the arithmetic mean value of the maximum diameters of 30 particles (randomly selected) measured by cross-sectional microstructure observation using a SEM (Scanning Electron Microscope).

[0028] The non-permeate side space 10A is the space on the non-permeate side of the water vapor separation membrane 14. The raw material gas supplied from the raw material gas supply unit 20 flows into the non-permeate side space 10A via the first supply port s1. Liquid fuel is synthesized from the raw material gas in the catalyst 12, and the resulting liquid fuel flows out as non-permeate side gas together with unreacted raw material gas (remaining raw material gas) from the non-permeate side space 10A via the first outlet d1 to the raw material gas circulation unit 30. The non-permeate side gas contains the liquid fuel and remaining raw material gas. The remaining raw material gas further contains acidic by-products in addition to unreacted hydrogen and carbon oxides. Acidic by-products refer to by-products of the conversion reaction that act as so-called Brønsted acids. Examples of acidic by-products include formic acid and methyl formate.

[0029] The permeate side space 10B is a space on the permeate side of the water vapor separation membrane 14. Water vapor produced in the conversion reaction and hydrogen and the like in the raw material gas permeate through the water vapor separation membrane 14 and flow into the permeate side space 10B.

[0030] The liquid fuel synthesis section 10 having the above configuration allows the conversion reaction to proceed by supplying a raw material gas, and separates the gas into a permeation side gas that has permeated the water vapor separation membrane from the non-permeation side space 10A to the permeation side space 10B and contains water vapor, a by-product of the conversion reaction, and a non-permeation side gas that has not permeated and contains liquid fuel, unreacted hydrogen and carbon oxides, and acidic by-products.

[0031] A sweep gas is supplied to the permeate side space 10B from the sweep gas supply unit 40 through the second supply port s2. The permeate side gas and the sweep gas flow out as exhaust gas from the permeate side space 10B through the second outlet d2 to the raw material gas supply unit 20.

[0032] A-2. Sweep gas supply section The sweep gas supply unit 40 is disposed upstream of the permeate side space 10B. The sweep gas supply unit 40 includes a sweep gas reservoir 42, a sweep gas supply pipe 44 connecting the sweep gas reservoir 42 with the second inlet s2 of the liquid fuel synthesis unit 10, and a heating unit 46 disposed in the sweep gas supply pipe 44.

[0033] The sweep gas storage section 42 stores the sweep gas. The sweep gas is heated to a desired temperature (for example, 150°C or higher and 350°C or lower) in the heating section 46, and then supplied from the second inlet s2 to the liquid fuel synthesis section 10. The heating section 46 is not particularly limited as long as it can heat the sweep gas.

[0034] The sweep gas contains an amine compound and preferably further contains one or both of hydrogen and carbon oxide. As will be described later with respect to the raw material gas supply unit, in this embodiment, the raw material gas is prepared using a mixed gas of exhaust gas containing the sweep gas and the remaining raw material gas. Here, by containing the amine compound in the sweep gas, acidic by-products in the remaining raw material gas can be neutralized and removed by the amine compound.

[0035] Any appropriate amine compound can be used as the amine compound as long as the effects of the present invention can be obtained. The amino group possessed by the amine compound other than ammonia may be a primary amino group, a secondary amino group, a tertiary amino group, or a combination of two or more of these.

[0036] In one embodiment, an amine compound is used having a boiling point of 100° C. or higher and 500° C. or lower, preferably 170° C. or higher and 350° C. or lower. Such an amine compound can be well maintained in a gaseous state in the sweep gas.

[0037] Specific examples of the amine compound include ammonia, polyethyleneimine, monoethanolamine, diethanolamine, triethanolamine, tetraethyleneaminepentamine, methyldiethanolamine, dibutylamine, ethylenediamine, diethylenetriamine, triethylenetetramine, hexaethylenediamine, benzylamine, N-(3-aminopropyl)diethanolamine, aminopropyltrimethoxysilane, polyvinylamine, 3-aminopropyltriethoxysilane, and aminosilane coupling agents such as N-(2-aminoethyl)-3-aminopropyltrimethoxysilane. The amine compounds can be used alone or in combination.

[0038] The amine compound concentration in the sweep gas is not limited as long as the effects of the present invention can be obtained. The amine compound concentration in the sweep gas is, for example, 10 ppm or more from the viewpoint of neutralizing acidic by-products. Although there is no particular upper limit for the amine compound concentration, since some catalysts are inhibited by alkali, the concentration may be appropriately adjusted to a value that prevents a decrease in catalytic activity. The amine compound concentration in the sweep gas is the amine compound concentration of the sweep gas at the second supply port s2 of the liquid fuel synthesis section.

[0039] In one embodiment, the sweep gas contains hydrogen or carbon oxide as a main component, preferably hydrogen as a main component. Incidentally, "containing hydrogen or carbon oxide as a main component" means that the concentration of hydrogen or carbon oxide is the highest in the sweep gas. The hydrogen concentration in the sweep gas is, for example, about 50% by volume or more and 90% by volume or less, preferably 65% ​​by volume or more and 80% by volume or less. The carbon oxide concentration is, for example, about 10% by volume or more and less than 50% by volume, preferably 20% by volume or more and 35% by volume or less. When the sweep gas is essentially composed of hydrogen, carbon oxide, and an amine compound, the exhaust gas can be suitably reused as part of the raw material gas without separating it into hydrogen derived from the raw material gas and the sweep gas.

[0040] A-3. Raw material gas circulation section The raw material gas circulation section 30 has a non-permeate side gas recovery pipe 31, a first condenser 32, a first drain trap 33, a liquid fuel recovery pipe 34, and a raw material gas circulation pipe 35. One end of the non-permeate side gas recovery pipe 31 is connected to the first outlet d1 of the liquid fuel synthesis section 10, and the other end is connected to the first condenser 32. The raw material gas circulation pipe 35 has one end connected to the first drain trap 33, and the other end connected to the raw material gas supply section 20 (more specifically, the mixing section 24).

[0041] The non-permeate gas recovered from the liquid fuel synthesis section 10 via the non-permeate gas recovery pipe 31 is supplied to the first condenser 32, whereby the liquid fuel is condensed (liquefied). The liquefied liquid fuel is separated from the remaining raw material gas by the first drain trap 33 and recovered from the liquid fuel recovery pipe 34.

[0042] The non-permeate gas (i.e., the remaining raw material gas) after separation of the liquid fuel contains unreacted hydrogen and carbon oxides as well as trace amounts of acidic by-products. The remaining raw material gas is supplied to the raw material gas supply unit 20 (more specifically, the mixing unit 24) via the raw material gas circulation pipe 35.

[0043] As shown in the drawing, the raw material gas circulation pipe 35 may be provided with a purge valve 36. The purge valve 36 is installed at one or more arbitrary positions in the raw material gas circulation pipe 35, and discharges a portion of the remaining raw material gas flowing through the raw material gas circulation pipe 35 to the outside.

[0044] A-4. Raw material gas supply unit The raw material gas supply unit 20 has a neutralization raw material gas supply pipe 22, a mixing unit 24, a moisture removal unit 26, and a pressure booster unit 28. The moisture removal unit 26 has a second condenser 26a, a second drain trap 26b, and a moisture recovery pipe 26c. One end of the neutralization raw material gas supply pipe 22 is connected to the second outlet d2 of the liquid fuel synthesis unit 10, and the other end is connected to the second condenser 26a of the moisture removal unit 26. In addition, the raw material gas circulation pipe 35 is connected to the neutralization raw material gas supply pipe 22 upstream of the moisture removal unit 26 so as to merge with the neutralization raw material gas supply pipe 22, and this connection point forms the mixing unit 24. The mixing section may have any configuration as long as it is capable of mixing the neutralization raw material gas and the remaining raw material gas. For example, a tank (mixing section) may be provided upstream of the moisture removal section 26, the neutralization raw material gas supply pipe 22 and the raw material gas circulation pipe 35 may be connected to the tank independently, and the neutralization raw material gas and the remaining raw material gas may be mixed inside the tank.

[0045] According to the above configuration, the exhaust gas (permeate gas and sweep gas) recovered from the liquid fuel synthesis unit 10 via the neutralization feed gas supply pipe 22 is mixed with the remaining raw material gas upstream of the moisture remover 26. As a result, acidic by-products contained in the remaining raw material gas are neutralized by the amine compounds (amine compounds derived from the sweep gas) contained in the exhaust gas. When the mixed gas of the exhaust gas and the remaining raw material gas is supplied to the second condenser 26a, the water vapor (water vapor derived from the permeate gas) contained in the exhaust gas is condensed, and the neutralized products generated by the neutralization are transferred (dissolved) into the condensed water. Water is generated during the neutralization, and the amount of condensed water increases. As a result, the amount of dissolved neutralized products increases, allowing the neutralized products to efficiently transfer into the condensed water. The condensed water containing the neutralized products is separated from the remaining gas components by the second drain trap 26b and recovered (removed) from the moisture recovery pipe 26c. The amine compound concentration in the exhaust gas (the amine compound concentration at the second outlet d2 of the liquid fuel synthesis section) is, for example, 10 ppm or more. Note that the upper limit of the amine compound concentration in the exhaust gas is not particularly limited, but since some catalysts are inhibited by alkali, the concentration can be appropriately adjusted to a value that prevents a decrease in catalytic activity.

[0046] The gas components after separation of the condensed water and neutralized products are pressurized and heated in the pressure booster section 28, and then supplied as a feed gas to the non-permeation side space 10A of the liquid fuel synthesis section 10. The feed gas is a recycled version of the remaining feed gas, but the accumulation of acidic by-products associated with an increase in the number of circulations is suppressed. Although not shown, if necessary, the gas components after separation of the condensed water and neutralized products can be mixed with hydrogen and / or carbon oxides to adjust the feed gas to a desired composition.

[0047] As described above, the raw material gas contains at least hydrogen and carbon oxide. The carbon oxide concentration in the raw material gas is, for example, 10% by volume to 40% by volume, preferably 20% by volume to 30% by volume. The hydrogen concentration in the raw material gas is, for example, 60% by volume to 90% by volume, preferably 70% by volume to 80% by volume.

[0048] A-5. Variation 1 FIG. 2 is a schematic configuration diagram of a liquid fuel production system according to another embodiment of the present invention. 2 includes a liquid fuel synthesis unit 10, a raw material gas supply unit 20, a raw material gas circulation unit 30, and a sweep gas supply unit 40. The liquid fuel production system 1B differs from the liquid fuel production system 1A shown in FIG. 1 in that the sweep gas supply unit 40 includes a carbon dioxide recovery unit 41, a carbon dioxide supply pipe 43, a hydrogen generation unit 45, a hydrogen supply pipe 47, a sweep gas supply pipe 44, and a heating unit 46.

[0049] For example, the carbon dioxide capture unit 41 includes a carbon dioxide adsorbent that adsorbs carbon dioxide upon contact with a carbon dioxide-containing gas and desorbs the carbon dioxide by heating, depressurizing, or the like. The carbon dioxide adsorbent can be used to capture a gas containing carbon dioxide at a higher concentration than the carbon dioxide-containing gas (carbon dioxide-enriched gas). More specifically, the carbon dioxide capture unit 41 brings the carbon dioxide-containing gas into contact with the carbon dioxide adsorbent to adsorb carbon dioxide, then heats and / or depressurizes the carbon dioxide adsorbent to desorb the carbon dioxide, and then sucks the desorbed carbon dioxide using a pump or the like to capture the carbon dioxide-enriched gas. In one embodiment, the carbon dioxide capture unit 41 is a carbon dioxide capture system that utilizes direct air capture (DAC) technology. Amine compounds are typically used as carbon dioxide adsorbents. Specific examples of amine compounds are as described above for the sweep gas. Due to the incorporation of the carbon dioxide adsorbent during the capture of the carbon dioxide-enriched gas, the carbon dioxide-enriched gas may contain a trace amount of the carbon dioxide adsorbent, i.e., the amine compound. Furthermore, the carbon dioxide-enriched gas may contain nitrogen derived from the atmosphere. Furthermore, for example, the carbon dioxide capture unit 41 may be a carbon dioxide capture facility that captures carbon dioxide from biogas using a separation membrane. Biogas is a gas generated by fermentation (methane fermentation) using biomass such as food waste, paper waste, and livestock manure as raw materials. The main components of biogas are methane and carbon dioxide, and it may also contain trace amounts of nitrogen, etc.

[0050] The hydrogen generator 45 is, for example, a hydrogen production facility that uses water electrolysis technology.

[0051] The carbon dioxide supply pipe 43 connects the carbon dioxide capture unit 41 and the heating unit 46, and the hydrogen supply pipe 47 connects the hydrogen generation unit 45 and the carbon dioxide supply pipe 43. Thus, the carbon dioxide-enriched gas supplied from the carbon dioxide capture unit 41 and the hydrogen supplied from the hydrogen generation unit 45 are mixed to generate a sweep gas. The sweep gas is heated in the heating unit 46 and then supplied to the liquid fuel synthesis unit 10 via the sweep gas supply pipe 44. That is, the carbon dioxide-enriched gas is supplied to the raw gas supply unit 10 as a component of the sweep gas (neutralization raw gas). However, the carbon dioxide contained in the sweep gas may be entirely or partially derived from a carbon dioxide-enriched gas (e.g., carbon dioxide-enriched gas recovered from the atmosphere using a DAC or carbon dioxide-enriched gas recovered from biogas using a separation membrane). As described above, since carbon dioxide-enriched gas may contain trace amounts of amine compounds, a mixed gas of carbon dioxide-enriched gas and hydrogen can be used as a sweep gas without the addition of an amine compound or by adding only a very small amount of an amine compound.

[0052] A-6. Variation 2 The separation membrane for separating water vapor and liquid fuel is not limited to a water vapor separation membrane that allows water vapor to pass through, and a liquid fuel separation membrane that allows at least liquid fuel to pass through can be used. In the present invention, the separation membrane for separating water vapor and liquid fuel has a higher selective permeability for one than the other, and does not necessarily completely separate the two, as long as the effects of the present invention can be achieved. For example, the liquid fuel separation membrane allows liquid fuel to pass through with higher selectivity than water vapor, but does not completely separate the two. FIG. 3 is a schematic configuration diagram of a liquid fuel production system according to another embodiment of the present invention. The liquid fuel production system 1C shown in FIG. 3 includes a liquid fuel synthesis unit 10 that promotes a conversion reaction from a feed gas containing at least hydrogen and carbon oxides to a liquid fuel; a feed gas supply unit 20 that supplies the feed gas to the liquid fuel synthesis unit 10; and a feed gas circulation unit 30 that re-supplies the remaining feed gas containing unreacted hydrogen and carbon oxides and acidic by-products of the conversion reaction from the liquid fuel synthesis unit 10 to the feed gas supply unit 20. The liquid fuel synthesis section 10 has a liquid fuel separation membrane 14a that allows liquid fuel to permeate, and separates the gas into a permeation side gas that has permeated the liquid fuel separation membrane 14a from the non-permeation side to the permeation side and contains at least liquid fuel, and a non-permeation side gas that has not permeated the liquid fuel separation membrane 14a and contains by-product water vapor, unreacted hydrogen and carbon oxides, and acidic by-products. The liquid fuel production system 1C further includes a sweep gas supply unit 40 that supplies a gas for sweeping the permeate side gas to the permeate side of the liquid fuel synthesis unit 10. The raw material gas supply unit 20 has a mixing unit 24 that mixes the amine compound and the remaining raw material gas in the presence of water vapor, and a moisture removal unit 26 that removes a neutralized product of the amine compound and an acidic by-product together with condensed water of the water vapor. According to the liquid fuel production system 1C, by using a gas (neutralization feed gas) containing an amine compound as the sweep gas, the sweep gas (neutralization feed gas) flowing out from the liquid fuel synthesis section 10 is mixed with the non-permeation side gas containing by-product steam and the remaining feed gas, and acidic by-products in the remaining feed gas can be neutralized with the amine compound. The main points of the second modification will be explained below. The rest are as explained for the liquid fuel production system 1A.

[0053] The liquid fuel synthesis unit 10 includes a catalyst 12, a liquid fuel separation membrane 14a, a non-permeation side space 10A, and a permeation side space 10B. The liquid fuel separation membrane 14a may be supported by a porous support 16, as shown in the example. The liquid fuel synthesis unit 10 includes a first supply port s1 and a first discharge port d1 that communicate with each other via the non-permeation side space 10A, and a second supply port s2 and a second discharge port d2 that communicate with each other via the permeation side space 10B. Examples of separation membranes that selectively allow liquid fuel to permeate include those described in JP 2020-23488 A.

[0054] The non-permeate side space 10A is the space on the non-permeate side of the liquid fuel separation membrane 14a, and the permeate side space 10B is the space on the permeate side of the liquid fuel separation membrane 14a. A raw material gas supplied from a raw material gas supply unit 20 flows into the non-permeate side space 10A via a first supply port s1. A liquid fuel is synthesized from the raw material gas in the catalyst 12, and the liquid fuel permeates through the liquid fuel separation membrane 14a and flows into the permeate side space 10B. A sweep gas is supplied from a sweep gas supply unit 40 via a second supply port s2 to the permeate side space 10B. The permeate side gas and the sweep gas flow as product gases from the permeate side space 10B to the raw material gas supply unit 20 via a second outlet port d2. Meanwhile, the remaining raw material gas, together with by-product steam, flows as non-permeate side gas from the non-permeate side space 10A to the raw material gas circulation unit 30 via a first outlet port d1.

[0055] The raw material gas circulation section 30 has a non-permeate side gas recovery pipe 31. One end of the non-permeate side gas recovery pipe 31 is connected to the first outlet d1 of the liquid fuel synthesis section 10, and the other end is connected to the neutralization raw material gas supply pipe 22, so that the non-permeate side gas can be supplied to the mixing section 24.

[0056] The raw material gas supply section 20 includes a neutralization raw material gas supply pipe 22, a mixing section 24, a moisture removal section 26, a pressure booster section 28, a third condenser 21, a third drain trap 23, and a liquid fuel recovery pipe 25. The product gas recovered from the liquid fuel synthesis section 10 via the neutralization raw material gas supply pipe 22 is separated into a liquid fuel and a sweep gas by the third condenser 21 and the third drain trap 23, and the liquefied liquid fuel is recovered via the liquid fuel recovery pipe 25. The sweep gas is sent to the moisture removal section 26 and mixed with the non-permeate side gas (in other words, the remaining raw material gas and by-product steam) in the mixing section 24 upstream of the moisture removal section 26. As a result, acidic by-products contained in the remaining raw material gas are neutralized by the amine compound contained in the sweep gas. When the mixed gas of the sweep gas and non-permeate gas is supplied to the second condenser 26a, the by-product water vapor derived from the non-permeate gas is condensed, and the neutralized products generated by the neutralization are transferred (dissolved) into the condensed water. The condensed water containing the neutralized products is separated from the remaining gas components by the second drain trap 26b and recovered (removed) from the moisture recovery pipe 26c.

[0057] In addition, with a liquid fuel separation membrane that does not completely separate liquid fuel and water vapor, the permeate side gas may contain liquid fuel and by-product water vapor, and therefore the product gas may contain the amine compound-containing sweep gas, liquid fuel, and water vapor. Therefore, even if the non-permeate side gas does not contain water vapor or water vapor is separated from the non-permeate side gas, the amine compound and the remaining feed gas can be mixed in the presence of water vapor by mixing the product gas after separation of the liquid fuel with the remaining feed gas. As described above, in embodiments using the liquid fuel separation membrane, water vapor present when the amine compound and the remaining feed gas are mixed may be recovered together with the remaining feed gas and contained in the non-permeate side gas and / or recovered as the permeate side gas and contained in the product gas.

[0058] A-7. Variation 3 FIG. 4 is a schematic configuration diagram of a liquid fuel production system according to another embodiment of the present invention. The liquid fuel production system 1D shown in FIG. 4 includes a liquid fuel synthesis unit 10a that promotes a conversion reaction from a feed gas containing at least hydrogen and carbon oxides to a liquid fuel; a feed gas supply unit 20 that supplies the feed gas to the liquid fuel synthesis unit 10a; and a feed gas circulation unit 30 that recovers the remaining feed gas containing unreacted hydrogen and carbon oxides and acidic by-products of the conversion reaction from the liquid fuel synthesis unit 10a and supplies it to the feed gas supply unit 20. The liquid fuel production system 1D further includes a temperature-adjusting gas supply unit 40a that supplies a temperature-adjusting gas that adjusts the temperature of the first gas flow channel 10A to the liquid fuel synthesis unit 10a. The raw material gas supply unit 20 has a mixing unit 24 that mixes the amine compound and the remaining raw material gas in the presence of water vapor, and a moisture removal unit 26 that removes a neutralized product of the amine compound and an acidic by-product together with condensed water of the water vapor. According to the liquid fuel production system 1D, by using a gas containing water vapor and an amine compound (neutralization raw material gas) as the temperature control gas, the temperature control gas flowing out from the liquid fuel synthesis section 10a can be mixed with the remaining raw material gas, and the acidic by-products in the remaining raw material gas can be neutralized with the amine compound and removed together with the condensed water.

[0059] The liquid fuel synthesis unit 10a has a first gas flow path 10A in which a catalyst 12 for promoting a conversion reaction is disposed, and a second gas flow path 10B through which a temperature-controlling gas for controlling the temperature of the first gas flow path 10A flows. In the illustrated example, the first gas flow path 10A and the second gas flow path 10B are vertically separated by a partition wall 18, but the second gas flow path 10B may be disposed so as to be able to control the temperature of the first gas flow path 10A. For example, the liquid fuel synthesis unit may have a double-pipe structure, with one of the inner and outer pipes serving as the first gas flow path and the other serving as the second gas flow path. The partition wall 18 is typically gas-impermeable.

[0060] The raw material gas supplied from the raw material gas supply unit 20 flows into the first gas flow path 10A via the first supply port s1. Liquid fuel is synthesized from the raw material gas in the catalyst 12, and the produced liquid fuel flows out of the first gas flow path 10A, together with the remaining raw material gas, as product gas via the first outlet port d1 to the raw material gas circulation unit 30. The product gas contains the liquid fuel, water vapor, which is a by-product of the conversion reaction, and the remaining raw material gas. The remaining raw material gas further contains acidic by-products in addition to unreacted hydrogen and carbon oxides.

[0061] The temperature control gas supplied from the temperature control gas supply unit 40a flows into the second gas flow passage 10B via the second supply port s2 and flows out to the raw material gas supply unit 20 from the second exhaust port d2.

[0062] The temperature control gas supply unit 40a has a temperature control gas storage unit 42 that stores the temperature control gas, a temperature control gas supply pipe 44 that connects the temperature control gas storage unit 42 with the second inlet s2 of the liquid fuel synthesis unit 10a, and a heating unit 46 that is interposed in the temperature control gas supply pipe 44. In the illustrated example, the temperature control gas is supplied to the liquid fuel synthesis unit 10a so as to flow countercurrently to the raw material gas, but the temperature control gas may also be supplied so as to flow cocurrently.

[0063] The temperature-adjusted gas is heated to a desired temperature (for example, 150°C or higher and 350°C or lower) in the heating section 46, and then supplied to the liquid fuel synthesis section 10a from the second inlet s2. The heating section 46 is not particularly limited as long as it can heat the temperature-adjusted gas.

[0064] The temperature control gas contains an amine compound and water vapor, and preferably further contains one or both of hydrogen and carbon oxide. The same explanation as for the sweep gas applies to the components of the temperature control gas other than water vapor. The water vapor dew point of the temperature control gas is, for example, 40°C or higher and 150°C or lower.

[0065] The same explanations as in sections A-4 and A-5 can be applied to the raw material gas supply unit 20 and the raw material gas circulation unit 30. Specifically, the raw material gas circulation unit 30 has a product gas recovery pipe 31a, a first condenser 32, a first drain trap 33, a liquid fuel recovery pipe 34, and a raw material gas circulation pipe 35. The raw material gas supply unit 20 has a neutralization raw material gas supply pipe 22, a mixing unit 24, a moisture removal unit 26, and a pressure booster unit 28.

[0066] The product gas recovered via the product gas recovery pipe 31a contains liquid fuel, by-product steam, and residual raw material gas containing unreacted hydrogen, carbon oxides, and acidic by-products. The product gas is separated into gas and liquid by the first condenser 32 and the first drain trap 33, and the liquefied liquid fuel and water are recovered via the liquid fuel recovery pipe 34, while the residual raw material gas is supplied to the raw material gas supply unit 20 (more specifically, the mixing unit 24) via the raw material gas circulation pipe 35. The liquid fuel and water recovered from the liquid fuel recovery pipe 34 are further separated and recovered as necessary.

[0067] Meanwhile, in the raw material gas supply unit 20, the temperature control gas containing the amine compound and water vapor recovered from the liquid fuel synthesis unit 10a via the neutralization raw material gas supply pipe 22 is mixed with the remaining raw material gas upstream of the moisture remover 26. As a result, the acidic by-products contained in the remaining raw material gas are neutralized by the amine compound contained in the temperature control gas, and the neutralized product produced by the neutralization is removed from the moisture remover 26 together with the condensed water of the water vapor. Note that the entire amount of water vapor generated by the conversion reaction may not be recovered in the liquid fuel recovery pipe 34 due to the difference in boiling point between the water vapor and methanol, and a portion of the by-product water vapor may be supplied to the mixing unit 24 via the raw material gas circulation pipe 35. Therefore, even if the temperature control gas does not contain water vapor, the amine compound and the acidic by-products may be neutralized in the presence of the by-product water vapor supplied via the raw material gas circulation pipe 35.

[0068] The gas components after separation of the condensed water and neutralized products are pressurized and heated in the pressure booster 28, and then supplied as a raw material gas to the first gas flow path 10A of the liquid fuel synthesis section 10a.

[0069] A-8. Variation 4 The amine compound used to neutralize the acidic by-products may be ammonia, which is generated from hydrogen and nitrogen in the liquid fuel synthesis section when a feed gas containing nitrogen in addition to hydrogen and carbon oxides is used. Ammonia has a small molecular diameter and is more easily permeable to separation membranes than other gases. Therefore, for example, if the liquid fuel synthesis section has a water vapor separation membrane, ammonia generated in the non-permeation side space of the liquid fuel synthesis section permeates the water vapor separation membrane as a permeation side gas together with water vapor, and may be swept by the sweep gas and discharged as exhaust gas from the liquid fuel synthesis section (more specifically, from the outlet d2 of the permeation side space). Therefore, the exhaust gas (a mixture of the permeation side gas and the sweep gas) contains water vapor and ammonia. By supplying such exhaust gas to the mixing section and mixing it with the remaining feed gas, the acidic by-products in the remaining feed gas can be neutralized using the ammonia contained in the permeation side gas in the presence of water vapor. Furthermore, for example, if the liquid fuel synthesis section has a liquid fuel separation membrane, ammonia produced in the non-permeate side space of the liquid fuel synthesis section permeates the liquid fuel separation membrane as a permeate side gas together with the liquid fuel, and can be swept by the sweep gas and discharged as product gas from the liquid fuel synthesis section (more specifically, from the outlet d2 of the permeate side space). Therefore, the product gas (a mixture of the permeate side gas and the sweep gas) contains liquid fuel and ammonia. Furthermore, the non-permeate side gas discharged from the outlet d1 of the non-permeate side space of the liquid fuel synthesis section contains water vapor and the remaining feed gas. Therefore, by separating the liquid fuel from the product gas, supplying it to the mixing section and mixing it with the non-permeate side gas, acidic by-products in the remaining feed gas can be neutralized in the presence of water vapor using the ammonia contained in the permeate side gas. Furthermore, with a liquid fuel separation membrane that does not completely separate liquid fuel and water vapor, ammonia produced in the non-permeate side space of the liquid fuel synthesis section permeates the liquid fuel separation membrane as a permeate side gas together with the liquid fuel and water vapor, and can be swept by the sweep gas and discharged as a product gas from the liquid fuel synthesis section. Therefore, even when the non-permeate side gas does not contain water vapor or when water vapor is separated from the non-permeate side gas, by supplying the product gas after separation of the liquid fuel and the remaining feed gas to the mixing section and mixing them, acidic by-products in the remaining feed gas can be neutralized in the presence of water vapor using ammonia contained in the permeate side gas. The ammonia concentration in the exhaust gas or product gas is, for example, 10 ppm or more, or, for example, less than 10,000 ppm. Note that this ammonia concentration is the concentration at the outlet d2 of the liquid fuel synthesis section, and is the concentration calculated excluding condensable components in the exhaust gas or product gas. Furthermore, the liquid fuel production system of Variation 4 may be configured to include a carbon dioxide capture unit as described in Variation 1, and to prepare a feedstock gas using a gas containing carbon dioxide captured from the atmosphere or biogas by the carbon dioxide capture unit. Because the gas containing carbon dioxide captured from the atmosphere or biogas may contain a small amount of nitrogen in addition to carbon dioxide, a feedstock gas can be prepared without adding nitrogen separately or by adding only a small amount of nitrogen.

[0070] B. Liquid Fuel Manufacturing Methods A method for producing a liquid fuel according to an embodiment of the present invention includes: supplying the feed gas containing at least hydrogen and carbon oxides to a liquid fuel synthesis section including a catalyst for promoting a conversion reaction from the feed gas to a liquid fuel (Step I); allowing the conversion reaction to proceed while recovering a residual feed gas containing unreacted hydrogen and carbon oxides and acidic by-products from the liquid fuel synthesis section (step II); removing the acidic by-products from the residual feed gas (Step III); and resupplying the remaining raw material gas after removing the acidic by-products to the liquid fuel synthesis unit as part of the raw material gas (step IV); Includes. Typically, the removal of acidic by-products from the remaining raw material gas is carried out by mixing an amine compound with the remaining raw material gas in the presence of water vapor and neutralizing the acidic by-products in the remaining raw material gas with the amine compound. The neutralized products produced by the neutralization are removed together with the condensed water of the water vapor. Preferably, the gas obtained after removing the condensed water and neutralized products from the mixed gas is supplied to the liquid fuel synthesis section as a constituent component of the raw material gas.

[0071] In a liquid fuel production method in which unreacted feed gas is recovered and circulated to be reused as the feed gas, the concentration of acidic by-products in the feed gas gradually increases as the number of circulations increases, which may result in a decrease in the liquid fuel yield and corrosion of the liquid fuel production system. In contrast, in a liquid fuel production method according to an embodiment of the present invention, an amine compound is mixed with the remaining feed gas, so that the acidic by-products can be neutralized and removed by the amine compound, and the mixed gas after removal can be used as a constituent component of the feed gas, thereby preventing the problem of concentration of acidic by-products.

[0072] The liquid fuel production method according to the embodiment of the present invention can be suitably carried out using the liquid fuel production system described in Section A. Hereinafter, an embodiment using liquid fuel production system 1A in which the liquid fuel synthesis unit includes a water vapor separation membrane and a sweep gas containing an amine compound is used as a neutralization feed gas will be described. However, it goes without saying that the liquid fuel production method according to the embodiment of the present invention can also be carried out as described in Section A when using a liquid fuel production system in which the liquid fuel synthesis unit includes a liquid fuel separation membrane, or a liquid fuel production system that includes a separation membrane and uses a feed gas containing nitrogen in addition to carbon oxides and hydrogen, etc. Furthermore, the liquid fuel production method according to the embodiment of the present invention can be carried out in the same manner as when using liquid fuel production system 1A, even when using liquid fuel production system 1D and using the temperature control gas after circulating through the liquid fuel synthesis unit as the neutralization feed gas to adjust the reaction temperature of the conversion reaction. For example, a temperature control gas containing an amine compound and water vapor can be circulated through the liquid fuel synthesis unit, and the temperature control gas after circulating through the liquid fuel synthesis unit can be used to neutralize and remove acidic by-products.

[0073] B-1. Process I In step I, a feed gas containing at least hydrogen and carbon oxides is supplied to a liquid fuel synthesis section including a catalyst for converting the feed gas into a liquid fuel and a water vapor separation membrane that allows water vapor to pass through. As described in section A, the liquid fuel synthesis section 10 includes a catalyst 12, a water vapor separation membrane 14, a non-permeation side space 10A, and a permeation side space 10B. The feed gas is supplied to the non-permeation side space 10A of the liquid fuel synthesis section 10 from a first inlet s1.

[0074] As described above, the raw material gas contains at least hydrogen and carbon oxide. The concentrations of hydrogen and carbon oxide in the raw material gas are as described above. The concentration of acidic by-products in the raw material gas (when two or more acidic by-products are present, the total concentration) is preferably as low as possible, for example, 30 ppm or less, preferably 20 ppm or less.

[0075] B-2. Process II In step II, the above conversion reaction is allowed to proceed, while the remaining feed gas containing unreacted hydrogen and carbon oxides and acidic by-products is recovered from the liquid fuel synthesis section.

[0076] The conversion reaction proceeds on the catalyst 12, thereby producing liquid fuel and water vapor. Specifically, as shown in reaction formula (2) above, methanol and water vapor are produced by catalytically hydrogenating a feed gas containing CO2 and hydrogen in the presence of a catalyst. In addition, trace amounts of acidic components (acidic by-products) are produced as by-products other than water vapor. The reaction conditions are as described in Section A.

[0077] The liquid fuel produced in the non-permeate side space 10A flows out through the first outlet d1 into the non-permeate side gas recovery piping 31 together with the remaining raw material gas containing unreacted hydrogen and carbon oxides and acidic by-products, and is separated into gas and liquid from the remaining raw material gas in the first condenser 32 and the first drain trap 33. As a result, the liquid fuel is recovered from the liquid fuel recovery piping 34, and the remaining raw material gas is recovered from the raw material gas circulation piping 35.

[0078] B-3. ​​Process III In step III, acidic by-products are removed from the remaining raw material gas. The liquid fuel production system 1A is configured to prepare a raw material gas by mixing a sweep gas and a remaining raw material gas, each of which is separately recovered from the liquid fuel synthesis unit 10. Therefore, by using a sweep gas containing an amine compound, acidic by-products contained in the remaining raw material gas can be removed by neutralization with the amine compound. Specifically, this is as follows.

[0079] In the liquid fuel production system 1A, water vapor generated in the non-permeation side space 10A and a portion of the hydrogen in the feed gas permeate through the water vapor separation membrane 14 and flow into the permeate side space 10B. A sweep gas containing an amine compound and, optionally, hydrogen and / or carbon oxides flows into the permeate side space 10B through the second inlet s2. The water vapor and hydrogen that flowed into the permeate side space 10B are swept by the sweep gas and flow out as exhaust gas through the second outlet d2 to the neutralization feed gas supply pipe (exhaust gas recovery pipe) 22. The feed gas circulation pipe 35 merges with the neutralization feed gas supply pipe 22 at the mixing section 24, whereby the exhaust gas and the remaining feed gas are mixed. As a result, acidic by-products derived from the remaining feed gas are neutralized by the amine compound derived from the sweep gas contained in the exhaust gas. The mixed gas of the exhaust gas and the remaining raw material gas passes through the second condenser 26a and the second drain trap 26b in this order, during which the water vapor is condensed and separated into gas and liquid, and the resulting mixture is recovered (removed) from the moisture recovery pipe 26c. Preferably, the neutralized product produced by the neutralization is dissolved in the condensed water and removed together with the condensed water from the moisture recovery pipe 26c.

[0080] B-4. Process IV In step IV, the remaining raw material gas after removal of the acidic by-products is re-supplied as part of the raw material gas to the liquid fuel synthesis section. Specifically, the mixed gas after moisture removal in step III is adjusted to the desired temperature and pressure in the pressure booster section 28 as the raw material gas, and then supplied to the liquid fuel synthesis section 10. As described above, if necessary, hydrogen and / or carbon oxides may be mixed with the mixed gas after moisture removal in step III to prepare the raw material gas to have a desired composition. [Industrial Applicability]

[0081] A liquid fuel production system according to an embodiment of the present invention can be suitably used to produce liquid fuels such as methanol. [Explanation of symbols]

[0082] 1A-D Liquid fuel production system 10 Liquid fuel synthesis department 20 Raw material gas supply section 30 Raw material gas circulation section 40 Sweep gas supply unit

Claims

1. a liquid fuel synthesis unit that promotes a conversion reaction from a feed gas containing at least hydrogen and carbon oxides to a liquid fuel; a raw material gas supply unit that supplies the raw material gas to the liquid fuel synthesis unit; a raw material gas circulation section that re-supplies the remaining raw material gas containing the unreacted hydrogen and carbon oxides and acidic by-products of the shift reaction from the liquid fuel synthesis section to the raw material gas supply section; Equipped with The raw material gas supply unit a mixing section for mixing an amine compound and the remaining raw material gas in the presence of water vapor; a water removal unit that removes a neutralized product of the amine compound and the acidic by-product together with condensed water of the water vapor, Liquid fuel production system.

2. 2. The liquid fuel production system according to claim 1, wherein the neutralization raw material gas containing the amine compound and the remaining raw material gas are mixed in the mixing section.

3. the source gas further contains nitrogen, 2. The liquid fuel production system according to claim 1, wherein the amine compound is ammonia produced from the hydrogen and the nitrogen in the liquid fuel synthesis section.

4. Further provided is a gas recovery unit that recovers carbon dioxide from the atmosphere or biogas; 3. The liquid fuel production system according to claim 2, wherein the carbon dioxide-containing gas supplied from the gas recovery section is used as a constituent component of the neutralization feed gas.

5. the liquid fuel synthesis section has a water vapor separation membrane that allows at least water vapor to permeate, and separates a permeation-side gas that has permeated the water vapor separation membrane from the non-permeation side to the permeation side and contains water vapor as a by-product of the conversion reaction, from a non-permeation-side gas that has not permeated the water vapor separation membrane and contains the liquid fuel, unreacted hydrogen and carbon oxides, and acidic by-products; a sweep gas supply unit configured to supply a sweep gas containing an amine compound to the permeate side of the liquid fuel synthesis unit; The liquid fuel production system according to claim 2 , wherein the permeate side gas and the sweep gas flowing out from the liquid fuel synthesis section are supplied to the mixing section.

6. The liquid fuel production system according to claim 5 , wherein the sweep gas further contains carbon oxides and / or hydrogen.

7. The liquid fuel production system according to claim 5 , wherein the concentration of the amine compound in the sweep gas is 10 ppm or more.

8. the liquid fuel synthesis section has a water vapor separation membrane that allows at least water vapor and ammonia to permeate, and separates a permeation-side gas that has permeated the water vapor separation membrane from the non-permeation side to the permeation side and contains water vapor and ammonia as by-products of the conversion reaction, from a non-permeation-side gas that has not permeated the water vapor separation membrane and contains the liquid fuel, unreacted hydrogen and carbon oxides, and acidic by-products; a sweep gas supply unit that supplies a sweep gas that sweeps the permeate side gas to the permeate side of the liquid fuel synthesis unit; The liquid fuel production system according to claim 3 , wherein the permeate side gas and the sweep gas flowing out from the liquid fuel synthesis section are supplied to the mixing section.

9. 9. The liquid fuel production system according to claim 8, wherein the ammonia concentration in the mixed gas of the permeate side gas and the sweep gas is 10 ppm or more.

10. the liquid fuel synthesis section has a liquid fuel separation membrane that allows at least liquid fuel to permeate, and separates a permeation-side gas that has permeated the liquid fuel separation membrane from the non-permeation side to the permeation side and contains the liquid fuel, from a non-permeation-side gas that has not permeated the liquid fuel separation membrane and contains water vapor, which is a by-product of the shift reaction, the unreacted hydrogen and carbon oxides, and the acidic by-products; a sweep gas supply unit configured to supply a sweep gas containing an amine compound to the permeate side of the liquid fuel synthesis unit; The liquid fuel production system according to claim 2 , wherein the sweep gas flowing out from the liquid fuel synthesis section is supplied to the mixing section.

11. The liquid fuel production system according to claim 10 , wherein the sweep gas further contains carbon oxides and / or hydrogen.

12. The liquid fuel production system according to claim 10 , wherein the concentration of the amine compound in the sweep gas is 10 ppm or more.

13. the liquid fuel synthesis section has a liquid fuel separation membrane that allows at least liquid fuel and ammonia to permeate, and separates a permeation-side gas that has permeated the liquid fuel separation membrane from the non-permeation side to the permeation side and contains the liquid fuel and the ammonia, from a non-permeation-side gas that has not permeated the liquid fuel separation membrane and contains water vapor that is a by-product of the shift reaction, the unreacted hydrogen and carbon oxides, and the acidic by-products; a sweep gas supply unit that supplies a sweep gas that sweeps the permeate side gas to the permeate side of the liquid fuel synthesis unit; The liquid fuel production system according to claim 3 , wherein the permeate side gas and the sweep gas flowing out from the liquid fuel synthesis section are supplied to the mixing section.

14. 14. The liquid fuel production system according to claim 13, wherein the ammonia concentration in the mixed gas of the permeate gas and the sweep gas is 10 ppm or more.

15. the liquid fuel synthesis unit has a first gas flow path in which a catalyst for promoting the conversion reaction is disposed and a second gas flow path through which a temperature control gas for adjusting a temperature of the first gas flow path flows, a temperature control gas supply unit that supplies a temperature control gas containing an amine compound to the second gas flow path of the liquid fuel synthesis unit; The liquid fuel production system according to claim 2 , wherein the temperature control gas flowing out from the liquid fuel synthesis section is supplied to the mixing section.

16. The liquid fuel production system according to claim 15, wherein the temperature control gas further contains carbon oxides and / or hydrogen.

17. The liquid fuel production system according to claim 15, wherein the concentration of the amine compound in the temperature control gas is 10 ppm or more.

18. supplying the feed gas containing at least hydrogen and carbon oxides to a liquid fuel synthesis section including a catalyst for promoting a conversion reaction from the feed gas to a liquid fuel; allowing the conversion reaction to proceed while recovering a residual feed gas containing unreacted hydrogen and carbon oxides and acidic by-products from the liquid fuel synthesis section; removing said acidic by-products from said residual feed gas; and resupplying the remaining raw material gas after removing the acidic by-products to the liquid fuel synthesis unit as part of the raw material gas; A method for producing a liquid fuel, comprising: removing the acidic by-products from the remaining raw material gas includes mixing an amine compound with the remaining raw material gas in the presence of water vapor to neutralize the acidic by-products with the amine compound; A method for producing a liquid fuel, comprising:

19. 19. The production method according to claim 18, wherein removing the acidic by-products from the remaining raw material gas comprises mixing the remaining raw material gas with a neutralization raw material gas that has been supplied to the liquid fuel synthesis section and contains the amine compound after passing through the liquid fuel synthesis section.

20. the source gas further contains nitrogen, The method for producing a fuel according to claim 18, wherein the amine compound is ammonia produced from the hydrogen and the nitrogen in the liquid fuel synthesis section.

21. The method according to claim 19, wherein the neutralization raw material gas is prepared using a gas containing carbon dioxide recovered from the atmosphere or biogas.

22. the liquid fuel synthesis unit has a water vapor separation membrane that allows at least water vapor to pass through, allowing water vapor, a by-product of the conversion reaction, to permeate from the non-permeation side to the permeation side of the water vapor separation membrane, sweeping the water vapor with a sweep gas containing the amine compound, and recovering the water vapor as an exhaust gas from the liquid fuel synthesis section; 20. The production method according to claim 19, wherein the exhaust gas and the remaining raw material gas are mixed, and the acidic by-products in the remaining raw material gas are neutralized with the amine compound.

23. the liquid fuel synthesis unit has a liquid fuel separation membrane that allows at least liquid fuel to permeate; permeating the liquid fuel from the non-permeation side to the permeation side of the liquid fuel separation membrane, sweeping with a sweep gas containing the amine compound, recovering the liquid fuel as a product gas from the liquid fuel synthesis section, and recovering water vapor as a by-product of the conversion reaction; separating the product gas into the liquid fuel and the sweep gas; 20. The method according to claim 19, wherein the sweep gas, the remaining raw material gas, and the water vapor are mixed together, and the acidic by-products in the remaining raw material gas are neutralized with the amine compound.

24. a temperature control gas containing the amine compound for adjusting the reaction temperature of the conversion reaction is circulated in the liquid fuel synthesis section; The manufacturing method according to claim 19, wherein the temperature control gas after flowing through the liquid fuel synthesis section is mixed with the remaining raw material gas, and the acidic by-products in the remaining raw material gas are neutralized with the amine compound.

25. the liquid fuel synthesis unit has a water vapor separation membrane that allows at least water vapor and ammonia to permeate; permeating the water vapor and the ammonia, which are by-products of the conversion reaction, from the non-permeation side to the permeation side of the water vapor separation membrane, sweeping them with a sweep gas, and recovering them as exhaust gas from the liquid fuel synthesis section; The production method according to claim 20, wherein the exhaust gas and the remaining raw material gas are mixed, and the acidic by-products in the remaining raw material gas are neutralized with the ammonia.

26. the liquid fuel synthesis unit has a liquid fuel separation membrane that allows at least the liquid fuel and ammonia to permeate; permeating the liquid fuel and the ammonia from the non-permeation side to the permeation side of the liquid fuel separation membrane, sweeping with a sweep gas, and recovering the liquid fuel and the ammonia as product gas from the liquid fuel synthesis section, and recovering water vapor, which is a by-product of the conversion reaction, together with the remaining feed gas; The method of claim 20, wherein the liquid fuel is separated from the product gas and then mixed with the remaining feedstock gas and the steam, and the acidic by-products in the remaining feedstock gas are neutralized with the ammonia.

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