Process for producing paraxylene

Abstract

As a whole of the process including separation of the para-xylene from the reaction mixture, separation of unreacted gas and by-products, recovery, reuse, improvement of the yield of the para-xylene, reduction of the consumed energy are achieved. The method for producing para-xylene is a method for producing para-xylene using a mixed gas of carbon dioxide or carbon monoxide or both and hydrogen as a main raw material, characterized by comprising: a reaction step of obtaining a generated gas mixture containing para-xylene by reacting a raw material mixed gas containing the mixed gas at high temperature and high pressure with a reaction catalyst; a separation step of separating into an aqueous phase containing water-soluble components, an oil phase containing a xylene mixture, and a gas phase containing unreacted gas by cooling the generated gas mixture obtained in the reaction step to condense high-boiling components; and a circulation step of mixing at least a part of the gas phase separated in the separation step into the raw material mixed gas.

Description

Technical Field

[0001] This invention relates to a method for producing paraxylene using carbon dioxide or a mixture of carbon monoxide and hydrogen as the main raw material. Background Technology

[0002] Paraxylene, which is useful as a raw material for polyester fibers and polyethylene terephthalate (PET) resin, has traditionally been manufactured in petrochemical complexes through a modification reaction of naphtha. However, this method not only requires fossil (petroleum) resources but also emits a large amount of carbon dioxide during the manufacturing process.

[0003] On the other hand, as a method for producing para-xylene without using fossil resources, a method using a so-called synthesis gas composed of carbon monoxide and hydrogen as a raw material has been proposed (Non-Patent Document 1, Patent Document 1). This method uses a catalyst with a ZnCr2O4 spinel structure to convert the synthesis gas into methanol, and then uses a catalyst with the outer surface of H-ZSM-5 zeolite (proton-type ZSM-5 zeolite) coated with silica zeolite-1 to convert the methanol into an aromatic compound containing para-xylene. Furthermore, by mixing these catalysts, para-xylene is synthesized from carbon monoxide and hydrogen through a single-stage reaction. Additionally, a method for synthesizing para-xylene in a single stage using carbon dioxide instead of carbon monoxide, along with hydrogen, has also been proposed (Patent Document 2). The method in Patent Document 2 uses a chromium oxide catalyst as a methanol synthesis catalyst and a catalyst with H-ZSM-5 zeolite coated with silica zeolite-1 as a para-xylene synthesis catalyst, thereby improving the para-xylene production efficiency. Simultaneously, by mixing the methanol synthesis catalyst and the para-xylene synthesis catalyst, para-xylene is synthesized from carbon dioxide and hydrogen through a single-stage reaction.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Publication No. 2020-535966

[0007] Patent Document 2: Japanese Patent Application Publication No. 2019-205969

[0008] Non-patent literature

[0009] Non-patent literature 1: Peipei Zhang et al., Chemical Science, The Royal Society of Chemistry, October 2017, Vol. 8, pp. 7941-7946. Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] In Patent Document 2, in Example 1, a catalyst comprising a mixture of a catalyst containing chromium oxide and a catalyst comprising H-ZSM-5 zeolite coated with silica zeolite-1 was used to synthesize p-xylene in high yield from a mixture of carbon dioxide and hydrogen. On the other hand, in Comparative Example 1, a catalyst comprising chromium zinc oxide was used instead of a catalyst containing chromium oxide, and in Comparative Example 2, a catalyst comprising a product further doped (ion-exchanged) with zinc at a portion of the acid sites of H-ZSM-5 coated with silica zeolite-1 was used. However, in Example 1, the yield of p-xylene was 7.61%, which was higher than that of Comparative Example 1 (3.42%) and Comparative Example 2 (5.06%), but there was no change in the low CO2 conversion rate compared to the comparative examples. Therefore, as a whole process, including the reuse of unreacted gases, there is a need to improve the yield of p-xylene and reduce energy consumption.

[0012] Methods for solving problems

[0013] The present invention provides a method for producing para-xylene using a mixture of carbon dioxide or carbon monoxide or both and hydrogen as the main raw material. The method is characterized by comprising: a reaction step of reacting a raw material mixture containing the mixture with a reaction catalyst under high temperature and high pressure to obtain a product gas mixture containing para-xylene; a separation step of cooling the product gas mixture obtained in the reaction step to condense high-boiling-point components and separate them into an aqueous phase containing water-soluble components, an oil phase containing the xylene mixture, and a gas phase containing unreacted gases; and a recycling step of mixing at least a portion of the gas phase separated in the separation step into the raw material mixture, thereby solving the aforementioned problems.

[0014] Invention Effects

[0015] According to the method of the present invention, ZSM-5 zeolite coated with a silicon-containing compound (preferably silica zeolite-1) is used as a catalyst in the reaction step. Therefore, the proportion of p-xylene contained in the oil phase separated from the product gas mixture in the separation step is increased, and less energy is required for the refining steps (distillation, adsorption separation, isomerization, disproportionation). In addition, the unreacted gases (carbon dioxide, carbon monoxide, and hydrogen), which account for most of the gas (by volume) in the gas phase separated in the separation step, are returned to the reaction step, thus significantly improving the overall yield of the process. Attached Figure Description

[0016] Figure 1 An example (first aspect) of an apparatus suitable for carrying out the method of the present invention is shown.

[0017] Figure 2 A second embodiment of an apparatus suitable for carrying out the method of the present invention.

[0018] Figure 3 A third embodiment of an apparatus suitable for carrying out the method of the present invention.

[0019] Figure 4 A fourth embodiment of an apparatus suitable for carrying out the method of the present invention.

[0020] Figure 5 This represents the process flow envisioned in the simulations of Examples 1 and 2.

[0021] Figure 6 This represents the process flow envisioned in the simulation of Example 3. Detailed Implementation

[0022] The method of the present invention is a method for producing para-xylene using a mixture of carbon dioxide or carbon monoxide or both and hydrogen as the main raw material, characterized by comprising: a reaction step of reacting a raw material mixture containing the mixture with a reaction catalyst under high temperature and high pressure to obtain a product gas mixture containing para-xylene; a separation step of cooling the product gas mixture obtained in the reaction step to condense the high-boiling-point components and separate them into an aqueous phase containing water-soluble components, an oil phase containing the xylene mixture, and a gas phase containing unreacted gases; and a recycling step of mixing at least a portion of the gas phase separated in the separation step into the raw material mixture.

[0023] <Reaction Process>

[0024] In the case of producing products containing p-xylene from a mixture of carbon monoxide and hydrogen, i.e., synthesis gas, it is assumed that, as shown in formula (1), methanol and dimethyl ether are generated by hydrogenation of carbon monoxide. The methanol and dimethyl ether generated in this way, as shown in formula (2), are then used to generate a mixture of various aromatic compounds via lower olefins.

[0025]

[0026] C3H6, etc. Various aromatic compounds (2)

[0027] In this case, a spinel-structured catalyst composed of a composite oxide of zinc (or copper) and chromium is preferably used as the catalyst for the methanol synthesis reaction of formula (1), and Zn / H-ZSM-5 zeolite is preferably used as the catalyst for selectively synthesizing p-xylene by carrying out the reaction of formula (2). In this case, if the outer surface of the Zn / H-ZSM-5 zeolite is coated with a silicon-containing compound (preferably, a compound with the same lattice structure as ZSM-5 zeolite, such as silica zeolite-1, but without acid sites), the proportion of p-xylene in the generated mixture can be increased. It should be noted that if these catalysts are used in combination, the reaction of formula (1) and the reaction of formula (2) proceed continuously or in parallel, thus enabling the production of products containing p-xylene using a single-stage reactor.

[0028] On the other hand, when a mixture of carbon dioxide and hydrogen is used as the main raw material to produce a product containing paraxylene, the reaction to produce methanol is carried out as shown in equation (3).

[0029]

[0030] That is, since the amount of water produced as a byproduct increases when methanol is generated, as described in Patent Document 2, when using a catalyst composed of chromium oxide (without zinc or copper) instead of the aforementioned composite oxide of zinc (or copper) and chromium as the catalyst for carrying out the reaction of formula (3), and using proton-type H-ZSM-5 without zinc doping as the catalyst for carrying out the reaction of formula (2), the yield of p-xylene can be increased.

[0031] That is, in the reaction process of the present invention, a catalyst containing an oxide of at least one metal appropriately selected from chromium, zinc, and copper can be combined and mixed with a catalyst containing a product coated with a silicon-containing compound such as silica zeolite-1, based on the ratio of carbon dioxide to carbon monoxide in the mixed gas used as the main raw material (hereinafter referred to as the "raw material mixed gas") and the content of other components. In this specification, proton-type or H-ZSM-5 zeolite doped (ion-exchanged) with various ions is generally referred to as ZSM-5 series zeolite. In the reaction of formula (2), in order to selectively synthesize p-xylene, it is preferable to use ZSM-5 series zeolite coated with a silicon-containing compound such as silica zeolite-1. It should be noted that, as will be described later, the gaseous components (including unreacted carbon dioxide and carbon monoxide) separated in the separation process of the present invention are returned to the reaction process. Therefore, the ratio of carbon dioxide to carbon monoxide and the content of other components mentioned above should take into account the components at the reactor inlet.

[0032] One of the objectives of this invention is to help reduce the concentration of carbon dioxide in the atmosphere. Therefore, the carbon dioxide used as a constituent gas mixture is preferably carbon dioxide separated from exhaust gas from fuel combustion devices that produce carbon dioxide, such as those used in thermal power plants and various heating furnaces; carbon dioxide separated from ammonia manufacturing plants, ethylene glycol manufacturing plants, and hydrogen manufacturing plants; carbon dioxide separated from the generated gas from gasifiers of coal, biomass, and waste; carbon dioxide separated from blast furnaces in ironworks; and carbon dioxide separated from air in the atmosphere.

[0033] In addition, hydrogen used as a component of the raw material mixture is preferably hydrogen generated by electrolyzing water using electricity generated from renewable energy sources such as sunlight, wind power, hydropower, geothermal energy, biomass, or nuclear power.

[0034] In particular, the preferred raw material mixing gas is syngas generated by a gasifier, exhaust gas discharged from a blast furnace in an ironmaking plant, exhaust gas separated in a hydrogen production unit, syngas generated by co-electrolysis of water and carbon dioxide, or syngas generated by reverse conversion reaction of hydrogen and carbon dioxide.

[0035] Regarding the reactor type, there are no particular limitations as long as it allows for gas-solid contact between the feed gas mixture (gas) and the reaction catalyst (solid), and can maintain the required temperature and pressure (packed bed, moving bed, fluidized bed, etc.). However, a packed bed is preferred due to its good contact efficiency, minimal channeling, and minimal mechanical damage to the catalyst particles. The catalyst loading rate and gas flow rate can be appropriately set. In the case of a packed bed, it is advisable to set these parameters with a space velocity (SV) of approximately 100 to 10,000 per hour based on an empty tower. Furthermore, it is preferable to set the reaction temperature to approximately 250°C to 600°C and the reaction pressure to approximately 1 to 10 MPaG.

[0036] <Separation Process>

[0037] Regarding the gas mixture containing p-xylene obtained in the reaction process, it is cooled in a subsequent separation process, causing the high-boiling-point component containing p-xylene to condense. The liquid phase is further separated into an aqueous phase containing water-soluble components such as water and alcohols generated in the reaction, and an oil phase containing aromatic components (including p-xylene) that are not miscible with water. That is, from the bottom side of the gas-liquid separator, it is sequentially separated into an aqueous phase forming the lower layer, an oil phase forming the middle layer, and a gas phase forming the upper layer, and the fluid of each phase can be extracted from the location where each layer is formed to the outside of the device. Alternatively, after the gas-liquid mixture is first separated into gas and liquid phases, the liquid phase can be separated into oil and water phases by separation methods using the difference in specific gravity, such as centrifugation or sedimentation.

[0038] <Refining Process>

[0039] The oil phase extracted from the gas-liquid separator contains not only p-xylene, the target compound, but also other aromatic compounds such as benzene, toluene, o-xylene, m-xylene, ethylbenzene, and trimethylbenzene. Therefore, these compounds need to be separated as required. Preferably, for the oil phase, a distillation operation is first used to separate benzene and toluene, whose boiling points are lower than those of xylenes (o-xylene, m-xylene, p-xylene, and ethylbenzene), as low-boiling-point components, and trimethylbenzene, whose boiling point is higher than that of xylenes, as high-boiling-point components. On the other hand, the boiling points of o-xylene, m-xylene, and ethylbenzene are close to those of p-xylene, so separating them by distillation alone is inefficient. Therefore, it is preferable to obtain the xylene fraction as a mixture of these compounds, and then use zeolite adsorption to separate this mixture.

[0040] Zeolite, with its fine pores the size of p-xylene molecules, effectively adsorbs p-xylene but adsorbs almost none of o-xylene, m-xylene, or ethylbenzene, thus functioning as a molecular sieve. That is, components other than p-xylene (o-xylene, m-xylene, and other impurities) are not adsorbed onto the zeolite and pass through the adsorption tower. Therefore, by repeatedly adsorbing and desorbing this mixture using zeolite, p-xylene can be concentrated and purified. Specifically, by having a xylene mixture flow through an adsorption tower lined with adsorbent (zeolite), only p-xylene is adsorbed. This adsorbent containing p-xylene then comes into contact with a desorbent, causing the p-xylene to desorb. The mixture of desorbent and p-xylene is then separated in a distillation tower, thereby obtaining a high concentration of p-xylene.

[0041] <Circular Process>

[0042] The gas phase extracted from the gas-liquid separator contains unreacted gases such as carbon dioxide, carbon monoxide, and hydrogen, and is therefore returned to the inlet side of the heater at the front of the reactor for recirculation. However, in addition to these unreacted gases, the gas phase also contains lower alkanes (mainly methane) with carbon numbers of 1 to 4 as byproducts. These lower alkanes hardly participate in the p-xylene synthesis reaction within the reactor, and thus gradually accumulate in the gas in the recirculation path. Therefore, a portion of the gas in the recirculation path must be purged to the outside. If approximately 1 to 20% by volume of the entire recirculation volume is purged, the concentration of lower alkanes in the recirculation path can be maintained at less than 40% by volume.

[0043] <Other ancillary processes>

[0044] To increase para-xylene production, isomerization and disproportionation treatments are preferably performed as needed. The o-xylene and m-xylene residues remaining after obtaining high-purity para-xylene in the refining process are isomerized, converting a portion into para-xylene, which can then be returned to the inlet side of the refining process. Specifically, the mixture of o-xylene and m-xylene after para-xylene separation is heated and passed through a reactor lined with a zeolite catalyst to perform isomerization.

[0045] In addition, the toluene and trimethylbenzene separated by distillation are disproportionated, and a portion of them is converted into a xylene mixture containing para-xylene, which can then be returned to the inlet side of the refining process. Specifically, the disproportionation is performed by heating the mixture containing toluene and trimethylbenzene and passing it through a reactor lined with a zeolite catalyst.

[0046] In the recycling process, the purging gas contains carbon monoxide, hydrogen, and lower alkanes in addition to carbon dioxide, which is an unreacted gas, making it suitable for use as fuel. However, to reduce the amount of hydrogen required as a feedstock gas, it is preferable to separate the hydrogen contained in the purging gas using membrane separation, adsorption separation (such as Pressure Swing Adsorption), etc., to recover only the hydrogen from the purging gas for recycling.

[0047] In addition to hydrogen, carbon dioxide and carbon monoxide can be recovered from the purge gas. These gases can be separated and recovered from the purge gas using appropriate membrane separation.

[0048] For heating the feed gas mixture at the reactor inlet and cooling the product gas mixture at the reactor outlet, it is preferable to use the heat recovered from cooling the product gas mixture for heating the feed gas mixture, thus saving energy required for heating and cooling. Furthermore, if sufficient cooling of the product gas mixture cannot be expected through heat exchange alone, the product gas mixture, whose temperature has already been reduced to a certain extent, can be further cooled through heat exchange operations.

[0049] Example

[0050] <First Method>

[0051] Figure 1This illustrates an example of an apparatus suitable for carrying out the method of the present invention. In the method of the present invention, a raw material gas mixture is heated by a heater 1 and then introduced into a reactor 2. Inside the reactor 2, a catalyst comprising an oxide of at least one metal selected from chromium, zinc, and copper and a catalyst comprising ZSM-5 zeolite coated with silica zeolite-1 are mixed and filled to form a mixed catalyst layer. The raw material gas mixture introduced into the reactor is brought into contact with the mixed catalyst in a high-temperature and high-pressure atmosphere of 250°C to 600°C and 1 to 10 MPaG, thereby reacting to form a product gas mixture containing paraxylene (reaction step).

[0052] The resulting gas mixture is cooled to near room temperature using cooler 3 and then introduced into gas-liquid separator 4. The condensed high-boiling-point components are separated into three layers in the gas-liquid separator: an aqueous phase (lower layer) containing water-soluble components, an oil phase (middle layer) containing paraxylene, and a gas phase (upper layer) containing unreacted gases (separation process).

[0053] After the oil phase forming the middle layer is extracted from the gas-liquid separator 4, a refining process 5, which combines distillation separation, adsorption separation, isomerization treatment, and disproportionation treatment, is used to obtain the target high-purity para-xylene. Furthermore, the amount of para-xylene can be increased relative to the outlet of the gas-liquid separator 4 (refining process).

[0054] The upper gas phase contains unreacted gases such as hydrogen, carbon dioxide, and carbon monoxide. Therefore, after being extracted from the gas-liquid separator 4, it is mixed as a recirculating gas into the feed gas stream at the inlet side of the heater 1, reheated, and returned to the reactor 2. It should be noted that, to prevent the accumulation of lower alkanes, a portion of the recirculating gas is purged outside the system (recirculation process).

[0055] To remove water-soluble organic matter, the aqueous phase that forms the lower layer is sent to the wastewater treatment unit 6 for treatment. On the other hand, a portion of the purge gas extracted from the circulating gas is effectively utilized as fuel gas in a nearby heating furnace or other heat source.

[0056] <Second Method>

[0057] Figure 2 Another example of an apparatus suitable for carrying out the method of the present invention. Figure 2 The basic structure of the device and Figure 1 The apparatus is the same, except that hydrogen is separated from the purge gas and combined with the recycle gas. The following is for... Figure 2 To explain, regarding the relationship with Figure 1 The same structure is used, so the explanation is omitted.

[0058] In addition to unreacted carbon dioxide, carbon monoxide, and hydrogen, the purge gas also contains small amounts of lower alkanes (methane, ethane, propane, etc.) as reaction byproducts. These lower alkanes do not participate in the p-xylene synthesis reaction within the reactor, and therefore must be extracted as purge gas to prevent their accumulation in the recycle gas. On the other hand, the hydrogen contained in the purge gas can be recovered by a hydrogen separator 7, which consists of membrane separation and adsorption separation (such as Pressure Swing Adsorption). Therefore, only hydrogen is recovered from the purge gas, which is then combined with the recycle gas and returned to the reactor, allowing it to be reused as a feedstock.

[0059] exist Figure 2 In this device, instead of using the total amount of purge gas as fuel gas, most of the hydrogen contained in it is reused as feed gas, thus reducing the amount of feed hydrogen used.

[0060] <Third Method>

[0061] Figure 3 This is yet another example of an apparatus suitable for carrying out the method of the present invention. Figure 3 The basic structure of the device and Figure 1 The apparatus is the same, except that heat exchanger 8 is used for heating (preheating) the raw material mixture and cooling the generated gas mixture. The following is for... Figure 3 To explain, regarding the relationship with Figure 1 The same structure is used, so the explanation is omitted.

[0062] One of the objectives of this invention is to reduce the concentration of carbon dioxide in the atmosphere by using carbon dioxide as a raw material for the production of paraxylene. Therefore, the amount of carbon dioxide emitted during the process of this invention and the resulting energy consumption should be minimized. Figure 3 The device reduces the amount of heat sources (steam, fuel gas, etc.) that must be supplied from the outside to heat the raw material mixture.

[0063] exist Figure 3 In this apparatus, a heat exchanger 8 is used to combine an inlet flow path for the feed gas mixture to the reactor and an outlet flow path for the product gas mixture from the reactor, thereby using the heat obtained from cooling the product gas mixture to heat the feed gas mixture. A conventional shell-and-tube heat exchanger can be used as the heat exchanger.

[0064] <Fourth Method>

[0065] Figure 4 This is yet another example of an apparatus suitable for carrying out the method of the present invention. Figure 4 The basic structure of the device and Figure 3The apparatus is the same as that of the circulating gas, except that the purge gas from the circulating gas is burned in a nearby heating furnace 9, and then CO2 is separated and recovered by the CO2 recovery device 10 and recycled as part of the raw material gas.

[0066] exist Figure 4 In this method, CO2 from the combustion of purge gas is also recovered as a raw material, which greatly helps to reduce the overall carbon dioxide emissions.

[0067] <Example 1>

[0068] Imagine Figure 5 The process flow shown is used to simulate the production of paraxylene at a rate of 12,500 kg / h (100,000 tons / year) using a feedstock mixture of carbon dioxide and hydrogen. The simulation results are used as... Figure 5 The temperature, pressure, flow rate, and composition at points 1 through 7 are shown in Table 1.

[0069] <Example 2>

[0070] Imagine Figure 5 The process flow shown is used to simulate the production of paraxylene at a rate of 12,500 kg / h (100,000 tons / year) using a feedstock mixture of carbon monoxide and hydrogen. The simulation results are used as... Figure 5 The temperature, pressure, flow rate, and composition at points 1 through 7 are shown in Table 2.

[0071] <Example 3>

[0072] Imagine Figure 6 The process flow shown is used to simulate the production of paraxylene at a rate of 12,500 kg / h (100,000 tons / year) using a feedstock mixture of carbon dioxide and hydrogen. The simulation results are used as... Figure 6 The temperature, pressure, flow rate and composition at points 1 to 8 are shown in Table 3.

[0073] [Table 1]

[0074]

[0075] [Table 2]

[0076]

[0077] [Table 3]

[0078]

[0079] This application claims priority to Japanese Patent Application No. 2021-78065, filed on April 30, 2021, the contents of which are incorporated herein by reference.

[0080] Explanation of reference numerals in the attached figures

[0081] 1 heater

[0082] 2 Reactor

[0083] 3 Cooler

[0084] 4. Gas-liquid separator

[0085] 5 Refining Process

[0086] 6. Drainage treatment device

[0087] 7 Hydrogen Separator

[0088] 8. Heat exchanger

[0089] 9. Heating Furnace

[0090] 10 CO2 recovery unit

Claims

1. A method for manufacturing p-xylene, characterized in that: p-xylene is manufactured using carbon dioxide or carbon monoxide, or a mixture of both and hydrogen, as the main raw material; include: A reaction step involving contacting a feed gas mixture containing the mixed gas with a catalyst at high temperature and pressure to obtain a product gas mixture containing para-xylene; a separation step involving cooling the product gas mixture obtained in the reaction step to condense high-boiling-point components and separate them into an aqueous phase containing water-soluble components, an oil phase containing the xylene mixture, and a gas phase containing unreacted gases; and a recycling step involving mixing at least a portion of the gas phase separated in the separation step into the feed gas mixture, wherein, in the recycling step, a portion of the recycled gas is purged, and hydrogen recovered from the purged gas is mixed into the feed gas mixture.

2. The method according to claim 1, wherein, The reaction catalyst used in the reaction process is a mixed catalyst, which comprises: a catalyst containing an oxide of a metal selected from at least one of chromium, zinc and copper, and a catalyst containing ZSM-5 series zeolite whose surface is coated with a silicon-containing compound.

3. The method according to claim 1 or 2, wherein, In the reaction process, the raw material mixed gas is brought into contact with the reaction catalyst at a reaction temperature of 250-600°C and a reaction pressure of 1-10 MPaG.

4. The method according to claim 1 or 2, wherein, In the separation process, the gas-liquid mixture obtained by cooling the generated gas mixture is first separated into a liquid phase and a gas phase. Then, the separated liquid phase is separated into an oil phase and a water phase by using a separation method based on the difference in specific gravity.

5. The method according to claim 1, wherein, In the cycle process, a PSA (Pressure Swing Adsorption) or hydrogen separation membrane is used as a method to recover hydrogen from the purge gas.

6. The method according to claim 1 or 2, wherein, In the circulation process, a portion of the circulating gas is purged, and the purged gas is effectively utilized as fuel gas.

7. The method according to claim 1 or 2, wherein, After heat exchange between the raw material gas mixture and the generated gas mixture, the raw material gas mixture is transferred to the reaction process.

8. The method according to claim 1 or 2, wherein, Carbon dioxide separated from combustion exhaust from thermal power plants or heating furnaces, carbon dioxide separated from ammonia manufacturing plants, ethylene glycol manufacturing plants or hydrogen manufacturing plants, carbon dioxide separated from the generated gas from coal, biomass or waste gasifiers, carbon dioxide separated from blast furnaces in ironmaking plants, or carbon dioxide separated from air in the atmosphere are used as at least a portion of the carbon dioxide constituting the raw material mixture.

9. The method according to claim 1 or 2, wherein, Hydrogen generated by electrolyzing water using electricity produced from sunlight, wind, water, geothermal energy, biomass, or atomic forces will be used as at least a portion of the hydrogen constituting the feedstock mixture.

10. The method according to claim 1 or 2, wherein, Syngas generated by a gasifier, waste gas discharged from a blast furnace in an ironmaking plant, waste gas separated in a hydrogen production unit, syngas generated by co-electrolysis of water and carbon dioxide, or syngas generated by reverse conversion reaction of hydrogen and carbon dioxide are used as at least a portion of the raw material mixture.

Images