Method for producing methanol

Abstract

To produce methanol industrially and efficiently from waste.SOLUTION: A method includes: a gas component adjustment process (S3) of adjusting a composition of a waste-derived gas (G1) to be a primary adjustment gas (G2); a CO2 separation process (S4) of selectively separating at least part of carbon dioxide from the primary adjustment gas (G2) to be a secondary adjustment gas (G3); and a conversion process (S7) of converting at least part of the secondary adjustment gas (G3) into methanol as a raw material gas (G4). A volume ratio of hydrogen to carbon monoxide in the primary adjustment gas (G2) is 1.5 to 4.0, inclusive, and a content of CO2 in the secondary adjustment gas (G3) is 1 to 10 vol%, inclusive.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing methanol from waste materials. [Background technology]

[0002] Burnable waste is usually disposed of by landfilling or incineration. Landfilling and even incineration emit carbon dioxide and heat, so improvements are needed from the perspective of global environmental issues such as global warming.

[0003] In consideration of global environmental issues and with the aim of making effective use of waste, methods have been developed for converting waste into hydrogen, a high-energy substance, or methanol or dimethyl ether, one of the most basic organic substances. For example, Patent Document 1 discloses a waste treatment system that includes a process for synthesizing methanol from hydrogen and carbon dioxide obtained by gasifying waste. Meanwhile, Non-Patent Document 1 discloses a method for recovering energy from waste using fluidized-bed gasification technology. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2012-017893 publication [Non-patent literature]

[0005] [Non-Patent Document 1] Kohei Matsunaga and five others, "Energy Recovery from Waste Using Fluidized Bed Gasification Technology," Ebara Times, Ebara Corporation, October 2007, No. 217, pp. 17-21 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the systems disclosed in Patent Document 1 and Non-Patent Document 1, the synthesis of methanol from carbon dioxide is not always carried out efficiently enough due to equilibrium constraints.

[0007] One aspect of the present invention aims to industrially and efficiently produce methanol from waste. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, one embodiment of the present invention provides a production method for producing methanol from waste-derived gas obtained by gasifying waste, the method comprising: a gas component adjustment step of adjusting the composition of the waste-derived gas to obtain a primary regulated gas; a CO separation step of selectively separating at least a portion of carbon dioxide (CO) from the primary regulated gas to obtain a secondary regulated gas; and a conversion step of converting at least a portion of the secondary regulated gas into methanol as a raw gas, wherein the volume ratio of hydrogen (H) to carbon monoxide (CO) in the primary regulated gas is 1.5 to 4.0, and the CO content in the secondary regulated gas is 1 vol% to 10 vol%. [Effects of the Invention]

[0009] According to one aspect of the present invention, methanol can be produced industrially and efficiently from waste. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a flowchart showing an example of a method for producing methanol according to a first embodiment of the present invention. [Figure 2] FIG. 1 is a system diagram schematically illustrating the configuration of a methanol production apparatus according to a first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Embodiment 1] Hereinafter, a method for producing methanol, which is one embodiment of the present invention, will be described in detail together with a production apparatus used therein, with reference to the drawings.

[0012] FIG. 1 is a flowchart showing an example of a methanol production method according to this embodiment. As shown in FIG. 1, the methanol production method of the present invention includes a gas acquisition step S1, a gas composition adjustment step S3, a CO2 separation step S4, and a conversion step S7. The gas acquisition step S1 is a step of decomposing waste to obtain a gas containing carbon oxides and hydrogen (H2) (referred to as a waste-derived gas G1), i.e., a step of gasifying the waste. The gas composition adjustment step S3 is a step of adjusting the composition of the waste-derived gas G1 to obtain a primary adjusted gas G2. The CO2 separation step S4 is a step of removing at least a portion of carbon dioxide (CO2) from the primary adjusted gas G2 obtained through the gas composition adjustment step S3 to obtain a secondary adjusted gas G3. The conversion step S7 is a step of using the secondary adjusted gas G3 obtained through the CO2 separation step S4 as a raw material gas G4 to synthesize methanol from at least a portion of the carbon oxides and hydrogen contained in the raw material gas G4. Here, the carbon oxides include at least one of carbon monoxide (CO) and carbon dioxide (CO2).

[0013] In addition to the above steps, the flowchart shown in FIG. 1 also includes a gas cleaning step S2, a compression step S5, a water removal step S6, a cooling and condensation step S8, and a purification step S9. Each step will be described in detail below. In this embodiment, the flowchart shown in FIG. 1 and a methanol production apparatus (hereinafter simply referred to as the "production apparatus") that realizes the production flow shown in the flowchart will be described as an example. However, the gas cleaning step S2, the compression step S5, the water removal step S6, the cooling and condensation step S8, and the purification step S9 are steps that can be incorporated into the production flow as needed. The steps shown in the drawings in this specification are merely typical examples and do not limit the scope of the present invention in any way.

[0014] (Configuration of methanol production equipment) First, an example of the configuration of a manufacturing apparatus 100 according to an embodiment of the present invention will be described. Fig. 2 is a system diagram that schematically shows the configuration of the manufacturing apparatus 100 according to the first embodiment.

[0015] As shown in Fig. 2, the production apparatus 100 of this embodiment is generally configured to include a gas acquisition apparatus 1, a gas scrubbing apparatus 2, a gas composition adjustment apparatus 3, a CO2 separation apparatus 4, a compressor 5, a moisture removal apparatus 6, a reactor 7, a condenser 8, a purification apparatus 9, a residual gas combustion apparatus 10, and paths L1 to L19. The production apparatus 100 of this embodiment is an apparatus for producing methanol from waste. The methanol production method of the present invention is a method in which a gas containing carbon oxides and hydrogen obtained by decomposing waste is supplied as a raw material gas to the reactor 7, and a reaction for converting the gas into methanol is carried out.

[0016] In this embodiment, the waste may be any organic material from which a gas containing hydrogen and carbon oxides can be obtained in the gas obtaining step S1. Examples of the waste include food waste, paper waste, textile waste, plastic waste, sewage sludge, human waste, livestock waste, waste oil, rubber tires, black liquor, blackstrap molasses, and mixtures thereof.

[0017] The gas capture apparatus 1 is an apparatus for carrying out a gas capture step S1 in which waste is decomposed to capture a gas containing carbon oxides and hydrogen (referred to as waste-derived gas G1). The gas capture apparatus 1 reacts waste supplied from a path L1 within the apparatus. As the gas capture apparatus 1, known apparatuses such as a fixed-bed furnace, a fluidized-bed furnace, a bubbling-type fluidized-bed furnace, a circulating fluidized-bed furnace, and a circulating moving-bed furnace can be used.

[0018] A path L2 is provided between the gas acquisition device 1 and the gas scrubbing device 2. As a result, the waste-derived gas G1 is supplied to the gas scrubbing device 2.

[0019] The gas scrubbing apparatus 2 is an apparatus that performs a gas scrubbing step S2 in which impurities are removed from the waste-derived gas G1 to scrub the gas. The gas scrubbing step S2 can be performed by a known method, and known apparatuses such as a wet scrubber and an electrostatic precipitator can be used as the gas scrubbing apparatus 2.

[0020] A path L3 is provided between the gas cleaning device 2 and the gas component adjusting device 3. As a result, the waste-derived gas G1 cleaned by the gas cleaning device 2 is supplied to the gas component adjusting device 3.

[0021] The gas composition adjusting device 3 is a device that performs a gas composition adjusting step S3 of adjusting the components of the raw material gas to be supplied to the reactor 7. The gas composition adjusting device 3 is provided with a path L4, and hydrogen can be supplied via the path L4.

[0022] A path L5 is provided between the gas composition adjuster 3 and the CO2 separator 4. As a result, the primary adjusted gas G2 adjusted in the gas composition adjuster 3 is supplied to the CO2 separator 4. As the gas composition adjuster 3, a known device such as a partial oxidation reactor, a steam reforming reactor, or an aqueous shift reactor can be used.

[0023] The CO2 separator 4 is an apparatus that performs a CO2 separation step S4, in which CO2 is selectively separated from the supplied primary adjusted gas G2 to produce a secondary adjusted gas G3. The CO2 separator 4 is provided with a carbon dioxide discharge path L6, through which carbon dioxide can be discharged. The CO2 separator 4 may be any known apparatus, such as a pressure swing adsorption apparatus, an absorption / stripping tower, a cryogenic carbon dioxide separator, or a carbon dioxide separation membrane facility. The gas composition adjustment performed in the gas composition adjuster 3 and the CO2 separator 4 will be described in detail in the description of the gas composition adjustment step below.

[0024] A path L7 is provided between the CO2 separator 4 and the compressor 5. As a result, the secondary regulated gas G3 obtained through the CO2 separator 4 is supplied to the compressor 5. The compressor 5 is a device that performs a compression step S5 in which the secondary regulated gas G3 is compressed to a pressure suitable for methanol synthesis. As the compressor 5, a known compression device such as a centrifugal compressor, an axial compressor, or a reciprocating compressor can be used.

[0025] A path L8 is provided between the compressor 5 and the moisture removal device 6. As a result, the compressed secondary conditioned gas G3 is supplied to the moisture removal device 6. The moisture removal device 6 is a device that performs a moisture removal step S6 in which moisture is removed from the compressed secondary conditioned gas G3 to reduce the amount of moisture in the secondary conditioned gas G3. The moisture removal device 6 may be composed of multiple devices. For example, the moisture removal device 6 may be composed of a cooler and a gas-liquid separator.

[0026] A path L9 is provided between the moisture remover 6 and the reactor 7. As a result, the secondary adjusted gas G3, the moisture content of which has been reduced in the moisture remover 6, is supplied to the reactor 7 as the raw material gas G4.

[0027] The reactor 7 is a reactor that carries out a conversion step S7 in which a gas containing carbon oxides and hydrogen, which is supplied as the raw material gas G4, is reacted in the presence of a catalyst to convert it into methanol.

[0028] The reactor 7 can be a known methanol synthesis reactor, such as a quench-type multistage adiabatic reactor or a heat exchanger-type isothermal reactor. When using a heat exchanger-type isothermal reactor, heat generated by the reaction in the catalyst layer can be recovered via a heat medium. The reactor 7 can also be a combination of multiple reactors, and the methanol production rate can be improved by connecting reactors of the same type or different structures in series. In this case, a condenser 8 can be provided between each of the multiple reactors.

[0029] A path L10 is provided between the reactor 7 and the condenser 8. This allows the gas discharged from the reactor 7 to be supplied to the condenser 8. The condenser 8 is a device that performs a cooling and condensation step S8 in which the gas discharged from the reactor 7 is cooled and separated into an unreacted residual gas G5 and a condensed liquid containing methanol and water. As the condenser 8, a known device such as a water-cooled condenser, an air-cooled condenser, or an evaporative condenser can be used.

[0030] A path L11 is provided between the condenser 8 and the purification device 9. As a result, the condensed liquid containing methanol and water discharged from the condenser is supplied to the purification device 9 via the path L11.

[0031] In addition, a path L14 is provided between the condenser 8 and the residual gas combustion device 10. As a result, the unreacted residual gas G5 discharged from the condenser 8 is supplied to the residual gas combustion device 10 via the path L14.

[0032] The purifier 9 is an apparatus for carrying out a purification step S9 in which the condensate is purified and water and impurities are separated therefrom to purify methanol. The condensate obtained from the condenser 8 is obtained as a liquid mixture containing the product methanol and water. The method for extracting methanol from the mixture in the purifier 9 is not particularly limited, but for example, methanol may be obtained by removing water and impurities through dehydration and purification treatment using a known method. Examples of dehydration and purification treatment methods include distillation and membrane separation.

[0033] The residual gas combustion device 10 is a device that performs a residual gas combustion step in which unreacted residual gas G5 is combusted to obtain thermal energy. Note that this residual gas combustion step is not shown in the flowchart of FIG. 1. A known device such as a direct combustion device or a catalytic combustion device can be used as the residual gas combustion device 10. Furthermore, the waste-derived gas G1 from which impurities have been removed by the gas scrubbing device 2 may be supplied to the residual gas combustion device 10 via a combustion gas bypass path (path L18 shown in FIG. 2) to obtain additional thermal energy. The thermal energy obtained in the residual gas combustion device 10 can be used as a heat source for the gas component adjustment step S3 (path L17 shown in FIG. 2). The residual gas combusted in the residual gas combustion device 10 is discharged as exhaust gas via path L19.

[0034] Furthermore, a path for re-supplying the unreacted residual gas G5 may be connected to the path L14. For example, the path L15 may be connected to the path L7, and the unreacted residual gas G5 may be merged into the secondary adjusted gas G3. The path L16 may be connected to the gas composition adjuster 3, and the unreacted residual gas G5 may be supplied to the gas composition adjuster 3. This allows the unreacted carbon oxides and / or hydrogen to be recovered as the unreacted residual gas G5 in the conversion step S7 in the reactor 7 and reused.

[0035] (Method of producing methanol) The method for producing methanol according to the first embodiment is carried out, for example, according to the flowchart shown in Fig. 1. Note that the flowchart shown in Fig. 1 is an example, and the present invention is not limited to this. Each step in the method for producing methanol according to the first embodiment will be described in detail.

[0036] (Gas acquisition process S1) The gas obtaining step S1 is a step of obtaining a gas containing carbon oxides and hydrogen from waste. When waste containing unsaturated hydrocarbon components, such as plastic waste, is used as the waste, it is assumed that the reactions represented by the following formulas (1) to (4) occur in the gas obtaining device 1 due to the reaction between the hydrocarbon and water vapor or oxygen.

[0037] CnH2n+nH2O→nCO+2nH2(1) CnH2n+2nH2O→nCO2+3nH2(2) CnH2n+0.5nO2→nCO+nH2(3) CnH2n+nO2→nCO2+nH2(4) In the above formulas (1) and (3), carbon monoxide is produced along with hydrogen, but the methanol production method of the present invention may also include a step in which carbon monoxide and water are used as raw materials to obtain carbon dioxide and hydrogen through the reaction of formula (5) below. Furthermore, the method may also include a step in which carbon monoxide and oxygen are used as raw materials to obtain thermal energy and carbon dioxide required for the gasification reaction (gas production reaction) through the reaction of formula (6) below.

[0038] CO+H2O→CO2+H2(5) CO+0.5O2→CO2(6) In the reactions of the above formulas (1) to (6), 1 to 3 moles of hydrogen are obtained per mole of carbon atoms.

[0039] On the other hand, when waste containing naturally occurring organic matter is used as the waste, it is thought that, for example, a reaction represented by the following formula (7) and / or a reaction represented by the following formula (8) occurs within the gas acquisition device 1.

[0040] (C6H 12 O6)n → 6nCO + 6nH2(7) (C6H 12 O6)n + 6nH2O → 6nCO2 + 12nH2(8) In the above formula (7), carbon monoxide is produced together with hydrogen, but carbon dioxide and hydrogen may be obtained by using the carbon monoxide and water as raw materials and subjecting them to the reaction of the above formula (5). In the above formulas (7) to (8), 1 to 2 moles of hydrogen are obtained per mole of carbon atom.

[0041] In the reaction for obtaining carbon monoxide and hydrogen from organic substances as described above, the reaction may need to be carried out at a higher temperature than in the reaction for obtaining carbon dioxide and hydrogen. Also in view of the energy cost involved in raising the temperature, it is expected that the method for obtaining carbon dioxide and hydrogen may be more advantageous.

[0042] (Gas cleaning process S2) The gas cleaning step S2 is a step of cleaning the waste-derived gas G1 by removing impurities. The waste-derived gas G1 may contain solid impurities such as soot and fly ash that poison the catalyst. Furthermore, other impurities may include reaction-inhibiting components such as sulfur, chlorine, and nitrogen. In such cases, it is preferable to clean the waste-derived gas G1 using the gas cleaning step S2 before supplying it to the downstream reactor 7. The gas cleaning step S2 can reduce, for example, the chloride and sulfide concentrations in the waste-derived gas G1. This can reduce the chloride and sulfide concentrations in the raw material gas G4 supplied to the reactor 7 to 100 ppb or less, respectively. The gas cleaning step S2 is usually performed depending on the solid content or reaction-inhibiting components contained in the waste-derived gas G1, and can be performed using a known cleaning method.

[0043] By cleaning the gas in the gas cleaning step S2 so that the concentrations of chlorides and sulfides in the raw material gas G4 supplied to the reactor 7 are each 100 ppb or less, the deterioration rate of the catalyst used in the conversion step S7 can be reduced and the catalyst life can be extended.

[0044] (Gas component adjustment process S3, CO2 separation process S4) The gas component adjustment step S3 is a step of adjusting the composition of the waste-derived gas G1 to obtain a primary adjusted gas G2. The CO2 separation step S4 is a step of removing at least a portion of carbon dioxide (CO2) from the primary adjusted gas G2 obtained through the gas component adjustment step S3 to obtain a secondary adjusted gas G3. By passing through the gas component adjustment step S3 and the CO2 separation step S4, the waste-derived gas G1 can be adjusted to a composition suitable for methanol synthesis.

[0045] The amount of hydrogen required for methanol production is 2 moles per mole of carbon monoxide (CO) and 3 moles per mole of carbon dioxide (CO2). Therefore, the volume fractions of hydrogen, carbon monoxide, and carbon dioxide in the raw material gas G4 supplied to the reactor 7 are ideally adjusted so that the index SN shown in the following equation (9) is 2. In the following equation (9), yH2, yCO2, and yCO are the volume fractions of hydrogen, carbon dioxide, and carbon monoxide, respectively, in the raw material gas supplied to the reactor 7.

[0046] SN=(yH2-yCO2) / (yCO+yCO2) (9) On the other hand, when high-energy waste such as polyolefin is used as the waste, it is sometimes necessary to secure thermal energy through the oxidation reaction of carbon monoxide shown in the above formula (6) in order to carry out gasification without inputting thermal energy from an external source. Therefore, as the proportion of carbon dioxide increases, the index SN shown in the above formula (9) becomes approximately 1.

[0047] In the methanol production method of the present invention, when the waste-derived gas G1 obtained in the gas obtaining step S1 contains hydrogen, carbon dioxide, and carbon monoxide, it is desirable to adjust the carbon dioxide concentration to preferably 0.1 to 20 vol%, more preferably 1 to 10 vol%, and supply it to the reactor 7. Therefore, when the value of the indicator SN is low, it is preferable to adjust the SN value in advance before supplying the waste-derived gas G1 to the reactor 7 as the raw material gas G4. The value of the indicator SN is preferably adjusted to 1 or more and 10 or less, and more preferably 1.5 or more and 3 or less.

[0048] The gas composition adjustment step S3 may be performed by performing at least one of the following methods: (i) a partial oxidation reaction of hydrocarbons contained in the waste-derived gas G1; (ii) a steam reforming reaction of hydrocarbons contained in the waste-derived gas G1; (iii) an aqueous shift reaction of carbon dioxide contained in the waste-derived gas G1; and (iv) adding hydrogen to the waste-derived gas G1. This allows the volume ratio of hydrogen to carbon monoxide (H2 / CO) in the primary adjusted gas G2 obtained through the gas composition adjustment step S3 to be adjusted to 1.5 or more and 4.0 or less. By subjecting the primary adjusted gas G2 having an H2 / CO ratio of 1.5 or more and 4.0 or less to the CO2 separation step S4, the index SN of the secondary adjusted gas G3 after carbon dioxide separation can be adjusted to 1.5 or more and 3 or less.

[0049] In the gas composition adjustment step S3, for example, hydrocarbons contained in the waste-derived gas G1 may be reformed into carbon monoxide and hydrogen by partial oxidation and / or steam reforming, followed by a water-gas shift reaction, which makes it easier to adjust the H / CO ratio to 1.5 or more and 4.0 or less.

[0050] Alternatively, in the gas component adjustment step S3, the hydrocarbons contained in the waste-derived gas G1 may be reformed into carbon monoxide and hydrogen by partial oxidation and / or steam reforming, and then hydrogen (hydrogen gas) may be added (supplemented). This makes it easier to adjust the H2 / CO ratio to 1.5 or more and 4.0 or less. Methods for obtaining this hydrogen include known techniques such as reforming of fossil fuels, decomposition reactions, electrolysis of water, and water decomposition using a photocatalyst.

[0051] In the CO2 separation step S4, for example, the primary regulated gas G2 can be treated by chemical absorption using an amine solution to separate carbon dioxide, an acidic gas, from the primary regulated gas G2. This allows for the production of a secondary regulated gas G3 with a carbon dioxide concentration adjusted to 0.1 to 20 vol%, preferably 1 to 10 vol%. Alternatively, in the CO2 separation step S4, the primary regulated gas G2 can be treated by cryogenic separation to separate carbon dioxide, which has the highest boiling point among hydrogen, carbon monoxide, and carbon dioxide. Alternatively, carbon dioxide can be separated by a membrane separation method using a separation membrane that selectively blocks carbon dioxide, or more preferably, a separation membrane that selectively allows carbon dioxide to pass through. The carbon dioxide separated in the CO2 separation step S4 may be used for other purposes.

[0052] By adjusting the gas components in the gas component adjustment step S3 and the CO2 separation step S4, the composition of the raw material gas G4 can be adjusted to be suitable for the methanol conversion reaction (synthesis reaction) in the subsequent conversion step S7, thereby improving the conversion rate to methanol in the conversion step S7.

[0053] (Compression step S5) The pressure of the raw material gas G4 supplied to the reactor 7 is preferably a pressure suitable for methanol synthesis. In the compression step S5, the secondary adjusted gas G3 obtained through the CO2 separation step S4 is increased to a pressure suitable for methanol synthesis by the compressor 5. The energy required for gas compression increases depending on the amount of gas supplied to the compressor 5. Therefore, it is desirable to compress the gas after removing carbon dioxide in the CO2 separation step S4. The pressure of the secondary adjusted gas G3 after compression may be 0.2 to 10 MPaG, more preferably 2 to 6 MPaG. By passing through the compression step S5, the pressure of the raw material gas G4 supplied to the reactor 7 becomes 0.2 to 10 MPaG, preferably 2 to 6 MPaG, thereby improving the efficiency of methanol synthesis.

[0054] (Moisture removal process S6) Moisture contained in the raw material gas G4 supplied to the reactor 7 inhibits the reaction and reduces the catalytic activity, so it is desirable to reduce it before the conversion step S7. As a method for removing moisture in the moisture removal step S6, for example, the compressed secondary adjusted gas G3 is cooled in a cooler to below the dew point of water to liquefy the vapor, which is then separated in a gas-liquid separator. The moisture removal step S6 can reduce the amount of moisture in the raw material gas G4 supplied to the reactor 7 to 5 vol% or less, preferably 2.5 vol% or less. This improves the reaction efficiency in the conversion step S7 and extends the catalyst life. is more preferred.

[0055] (Conversion step S7) The conversion step S7 is a step in which at least a portion of the gas obtained from the waste is brought into contact with a catalyst and converted into methanol in the gas phase.

[0056] Here, the catalyst used in the conversion step S7 will be explained. When methanol is obtained by the reaction of carbon dioxide and hydrogen, water is produced as a by-product, as represented by the following formula (10). On the other hand, when methanol is obtained by the reaction of carbon monoxide and hydrogen, water is not produced as a by-product, as represented by the following formula (11).

[0057] CO2 + 3H2 → CH3OH + H2O (49.4 kJ / mol (exothermic reaction)) (10) CO + 2H → CHOH (90.4 kJ / mol (exothermic reaction)) (11) The by-product water may reduce the reaction activity of the catalyst and decrease the productivity of methanol. Therefore, in the methanol production method of the present invention, it is preferable to use a catalyst that is less susceptible to the influence of water.

[0058] For this reason, in this embodiment, it is preferable to use a catalyst whose activity is not easily reduced by water, such as a copper-based catalyst. For example, a catalyst containing copper, zinc, aluminum, and silicon as essential components and optionally containing zirconium, palladium, and gallium is used. Generally, catalysts used to obtain methanol by reacting carbon dioxide and hydrogen tend to be able to obtain methanol even when carbon monoxide and hydrogen are used as raw materials. Therefore, catalysts containing components such as copper are suitable for use in the methanol production method of this embodiment because they are active in both the reaction between carbon dioxide and hydrogen and the reaction between carbon monoxide and hydrogen, and are durable against the by-product water.

[0059] When a copper-containing catalyst is used as the catalyst, its particle size is not particularly limited, but may be, for example, 1 mm to 20 mm, 2 mm to 20 mm, 3 mm to 20 mm, 3 mm to 15 mm, or 3 mm to 10 mm. Having the catalyst particle size within the above range not only makes the catalyst easy to handle, but is also suitable in terms of catalyst strength, and is also suitable when the catalyst is loaded into a fixed bed to form a catalyst layer. The method for producing a catalyst with the above particle size is not particularly limited, and known methods can be used. A tableting method is preferably used.

[0060] The reaction temperature in the catalyst layer may be, for example, about 180°C or higher and 260°C or lower, and preferably 220°C or higher and 240°C or lower.

[0061] The conversion step S7 in the reactor 7 may be carried out in the presence of a so-called inert gas that does not contribute to the conversion reaction or to the decrease in activity of the catalyst.

[0062] (Cooling and condensation process S8) In the cooling and condensing step S8, the gas discharged from the reactor 7 is cooled using a condenser 8 and separated into an unreacted residual gas G5 and a condensed liquid containing methanol and water.

[0063] (Purification step S9) In the purification step S9, the condensate obtained in the cooling and condensing step S8 is purified to separate water and impurities, thereby purifying methanol.

[0064] (Residual gas combustion process) In the residual gas combustion step, thermal energy is obtained by combusting at least a portion of the waste-derived gas G1 and / or the unreacted residual gas G5 discharged from the condenser 8. The heat obtained by the residual gas combustion step can be used as at least a portion of the heat source for carrying out the gas component adjustment step S3.

[0065] (summary) A production method according to one embodiment of the present invention is a method for producing methanol from a waste-derived gas G1 obtained by gasifying waste. The method includes a gas component adjustment step S3 in which the composition of the waste-derived gas G1 is adjusted to produce a primary regulated gas G2, a CO2 separation step S4 in which at least a portion of the carbon dioxide is selectively separated from the primary regulated gas G2 to produce a secondary regulated gas G3, and a conversion step S7 in which at least a portion of the secondary regulated gas G3 is converted into methanol as a feed gas G4. The volume ratio of hydrogen to carbon monoxide in the primary regulated gas G2 is 1.5 to 4.0, and the CO2 content in the secondary regulated gas G3 is 1 vol% to 10 vol%.

[0066] The above configuration enables more efficient production of methanol from waste, enabling effective utilization of waste. It also contributes to reducing carbon dioxide emissions from fossil fuels that accompany conventional methanol production. This will contribute to achieving the Sustainable Development Goals (SDGs).

[0067] The production method according to one aspect of the present invention may further include a gas cleaning step S2 for removing impurities, and the concentrations of chlorides and sulfides in the source gas G4 may each be 100 ppb or less.

[0068] The above configuration can extend the life of the catalyst in the conversion step S7.

[0069] Furthermore, the production method according to one aspect of the present invention may further include a moisture removal step S6 for reducing moisture before the conversion step S7, and the moisture content in the source gas G4 may be 2.5 vol % or less.

[0070] With the above configuration, the efficiency of methanol synthesis in the conversion step S7 can be improved, and the life of the catalyst in the reactor 7 can be extended.

[0071] Furthermore, the production method according to one embodiment of the present invention may further include a compression step of compressing the secondary conditioned gas G3 before the conversion step S7, and the pressure of the raw material gas G4 may be 2 MPaG or more and 6 MPaG or less.

[0072] The above configuration can improve the efficiency of methanol synthesis in the conversion step S7.

[0073] In addition, a manufacturing method according to one embodiment of the present invention may use heat generated by burning waste-derived gas G1 and / or unreacted residual gas G5 in the conversion process S7 as at least part of the heat source for carrying out the gas component adjustment process S3.

[0074] The above configuration makes it possible to reduce energy consumption in methanol production.

[0075] In the production method according to one aspect of the present invention, at least one of a partial oxidation reaction, a steam reforming reaction, a water gas shift reaction, and hydrogenation may be carried out in the gas composition adjusting step S3.

[0076] With the above configuration, the composition of the raw material gas G4 can be made suitable for methanol synthesis, and the efficiency of methanol synthesis can be improved.

[0077] In the production method according to one aspect of the present invention, a water gas shift reaction may be carried out after the partial oxidation reaction and / or the steam reforming reaction.

[0078] With the above configuration, the composition of the raw material gas G4 can be more easily adjusted to a composition suitable for methanol synthesis.

[0079] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0080] S1: Gas acquisition process S2: Gas cleaning process S3: Gas composition adjustment process S4...CO2 separation process S5: Compression process S6...Moisture removal process S7...Conversion process S8: Cooling and condensing process S9...Purification process 1. Gas acquisition device 2. Gas cleaning equipment 3. Gas composition adjustment device 4...CO2 separation equipment 5. Compressor 6...Moisture removal device 7. Reactor 8. Condenser 9... Purification equipment 10. Residual gas combustion device 100...Manufacturing equipment

Claims

1. 1. A method for producing methanol from waste-derived gas obtained by gasifying waste, comprising: a gas component adjusting step of adjusting the composition of the waste-derived gas to obtain a primary adjusted gas; At least a portion of carbon dioxide (CO ２ ) as a secondary conditioning gas. ２ a separation step; a conversion step of converting at least a portion of the secondary conditioned gas into methanol as a feed gas; The ratio of hydrogen (H) to carbon monoxide (CO) in the primary conditioning gas ２ ) is 1.5 or more and 4.0 or less in volume ratio, CO in the secondary conditioning gas ２ The content of is 1 vol% or more and 10 vol% or less.

2. further comprising a gas scrubbing step to remove impurities prior to said converting step; 2. The method according to claim 1, wherein the concentrations of chlorides and sulfides in the raw material gas are each 100 ppb or less.

3. The method further comprises a moisture removal step of reducing moisture prior to the conversion step, 3. The method according to claim 1, wherein the water content in the raw material gas is 2.5 vol % or less.

4. further comprising a compression step of compressing the secondary conditioned gas prior to the converting step; The method according to claim 1 , wherein the pressure of the source gas is 2 MPaG or more and 6 MPaG or less.

5. 5. The production method according to claim 1, wherein heat generated by burning the waste-derived gas and / or the unreacted residual gas in the conversion step is used as at least a part of the heat source for carrying out the gas component adjustment step.

6. The method according to claim 1 , wherein the gas composition adjustment step comprises performing at least one of a partial oxidation reaction, a steam reforming reaction, a water gas shift reaction, and hydrogenation.

7. The production method according to claim 6, wherein in the gas composition adjustment step, a water gas shift reaction is carried out after the partial oxidation reaction and / or the steam reforming reaction.

Images