Method for producing highly polar reaction product, and production system for highly polar reaction product

Abstract

To provide a method which enables synthesis of a high polarity reaction product in a high yield by reacting low polarity gases with each other under mild conditions.SOLUTION: A method for producing a high polarity reaction product comprises: introduction of a low polarity solvent 20, which can form a phase 60 of a carbon dioxide expansion liquid together with carbon dioxide 40, and a high polarity solvent 30 into a pressure-resistant container 10 and introduction of a plurality of low polarity gasses 50 and 40 including carbon dioxide 40 while applying a pressure thereto in a state where the low polarity solvent 20 and the high polarity solvent 30 are phase-separated for the low polarity solvent 20 and carbon dioxide 40 to form a phase 60 of a carbon dioxide expansion liquid and to phase-separate from a phase 70 which contains the high polarity solvent; the reaction of at least two low polarity gases among the plurality of low polarity gases 50 and 40 in the phase 60 of the carbon dioxide expansion liquid to form a high polarity reaction product 80; and migration of the high polarity reaction product 80 from the phase 60 of the carbon dioxide expansion liquid to the phase 70 containing the high polarity solvent.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing highly polar reaction products. [Background technology]

[0002] There is a need to develop technologies that can effectively utilize carbon dioxide (CO2) in order to realize a decarbonized society. Carbon dioxide (CO2) capture and storage (CCS) technology is expected to be used in industries that emit large amounts of carbon dioxide (CO2) during the operation of large plants, steel mills, power plants, etc. Hydrogen (H2) is produced in large quantities as a by-product of oil refining, so there is a need for an inexpensive formic acid (CHOOH) synthesis process that uses the carbon dioxide (CO2) and hydrogen (H2) emitted at petrochemical complexes, without incurring logistics costs.

[0003] Furthermore, formic acid (CHOOH), which is liquid at room temperature, is attracting attention as an energy carrier in the next-generation hydrogen society, along with ammonia (NH3) and organic hydrides.

[0004] For example, Non-Patent Document 1 discloses a method for obtaining formic acid from carbon dioxide (CO2) and hydrogen (H2) in an aqueous reaction field using PdAg alloy nanoparticles supported on TiO2 as a catalyst. In this method, formic acid is synthesized by pressurizing a 1.0 M NaHCO3 aqueous solution with CO2 (1 MPa) and H2 (1 MPa) in the presence of a PdAg alloy nanoparticle catalyst, and the catalyst turnover number (TON) per 24 hours is 2495 (i.e., it is equivalent to a catalyst turnover frequency (TOF) of 10 hours). -1 ), and the catalytic turnover number (TON) per 24 hours without the addition of base was 12 (equivalent to catalytic turnover frequency (TOF) per hour). -1 It is stated that the Non-Patent Document 2 discloses that a PdAg-supported sample synthesized from 3-aminopropyltriethoxysilane (APT) and glutaraldehyde exhibits high catalytic activity in an aqueous reaction field in the absence of base. In this method, formic acid is synthesized by pressurizing CO2 (2 MPa) and H2 (2 MPa), and the catalyst turnover number (TON) per 24 hours is 241 (i.e., the catalyst turnover frequency (TOF) is 10 h). -1 It is stated that the

[0005] As another example of synthesizing a highly polar reaction product by reacting low-polarity gases with each other, Non-Patent Document 3 discloses a method for synthesizing methanol (CH3OH) from methane (CH3) and oxygen (O2) in an aqueous H2O2 solution using a Cu-Fe ZSM-5 catalyst. Non-Patent Document 4 discloses a method for synthesizing ammonia (NH3) from nitrogen (N2) and hydrogen (H2) in a dilute sulfuric acid solution using a catalyst having Ru atoms individually fixed to the micropores of an H-ZMS-5 (HZ) support. Non-Patent Document 5 discloses a method for obtaining methanol (CH3OH) from carbon dioxide (CO2) and hydrogen (H2) using Cu / CeO2 as a catalyst.

[0006] In reactions in which highly polar compounds (i.e., hydrophilic compounds) such as formic acid, methanol, and ammonia are produced in the liquid phase, the target product must dissolve in the liquid phase, which is the reaction site, in order to be desorbed from the catalyst surface. Using a hydrophobic organic phase in a reaction to produce highly polar compounds is a major contradiction in this respect, and there have been few research examples to date. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] K. Mori et al. J. Am. Chem. Soc. 140 (2018) 8902-8909. [Non-Patent Document 2] S. Masuda et al. ACS Appl. Energy Mater. 3 (2020) 5847-5855. [Non-Patent Document 3] Tao Yu et al. ACS Catal. 11 (2021) 6684-6691. [Non-Patent Document 4] Xiuyun Wang et al. ACS Catal. 10 (2020) 9504-9514. [Non-Patent Document 5] Leon GA van de Water et al. J. Catal. 364 (2018) 57-68. Summary of the Invention [Problem to be solved by the invention]

[0008] However, conventional technologies for synthesizing highly polar reaction products such as formic acid (CHOOH), methanol (CH3OH), and ammonia (NH3) from low-polarity gases such as carbon dioxide (CO2), hydrogen (H2), methane (CH3), oxygen (O2), and nitrogen (N2) had issues such as being unsuitable for industrial production due to the need for high temperatures and pressures, and having low reaction efficiency.

[0009] In light of the above circumstances, an object of the present invention is to provide a method for producing a highly polar reaction product, which can synthesize a highly polar reaction product with high efficiency by reacting low polarity gases with each other under mild conditions. [Means for solving the problem]

[0010] The present invention includes the following aspects. [1] A method for producing a highly polar reaction product, comprising reacting low polarity gases with each other to synthesize a highly polar reaction product, comprising: A low polarity solvent capable of forming a carbon dioxide expanded liquid phase together with carbon dioxide and a high polarity solvent capable of phase separation from the low polarity solvent are introduced into a pressure vessel, and in a state in which the low polarity solvent and the high polarity solvent are phase separated, multiple types of low polarity gases including carbon dioxide are introduced under pressure, the low polarity solvent and the carbon dioxide form a carbon dioxide expanded liquid phase and separate from a phase containing a high polarity solvent; In the carbon dioxide expanded liquid phase, at least two of the plurality of low polarity gases react with each other to produce a high polarity reaction product; and the highly polar reaction product transitions from the carbon dioxide expanded liquid phase to a phase containing the highly polar solvent; A manufacturing method comprising:

[0011] [2] The method according to [1], wherein the highly polar solvent is water. [3] The method according to [1] or [2], wherein the low polarity solvent has an octanol / water partition coefficient (logPow) of 2.0 to 8.0. [4] The method according to any one of [1] to [3], wherein the plurality of low-polarity gases includes at least hydrogen. [5] The plurality of low polarity gases include carbon dioxide and hydrogen, The method according to [4], wherein the highly polar reaction product comprises formic acid. [6] The method according to any one of [1] to [5], further comprising introducing a catalyst into the pressure vessel. [7] The method according to [6], wherein the catalyst is a hydrophobic catalyst. [8] The method according to any one of [1] to [7], wherein the low-polarity solvent is a hydrocarbon. [9] The method according to [8], wherein the low polarity solvent is an alkane. Effect of the Invention

[0012] According to the present invention, it is possible to provide a method for producing a highly polar reaction product, which is capable of synthesizing a highly polar reaction product with high efficiency by reacting low polarity gases with each other under mild conditions. [Brief description of the drawings]

[0013] [Figure 1] 1(A) to 1(D) are schematic diagrams showing a method for producing a highly polar reaction product according to an embodiment of the present invention. [Diagram 2] 1 is a graph showing the effect of reaction temperature in the synthesis of formic acid by the method for producing a highly polar reaction product of an embodiment. [Diagram 3] 1 is a graph showing the effect of pressurizing carbon dioxide in the synthesis of formic acid by the method for producing a highly polar reaction product of an embodiment. [Figure 4] 1 is a graph showing the effect of the octanol / water partition coefficient (logPow) of a low polarity solvent in the synthesis of formic acid by a method for producing a highly polar reaction product in an example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] <Method of producing highly polar reaction products> The method for producing a highly polar reaction product of the present invention will be described in detail below. In addition, the drawings used in the following description may show characteristic parts in an enlarged scale for the sake of convenience in order to make the characteristics easier to understand, and the dimensional ratios of each component may not necessarily be the same as in reality. The present invention is not limited to the embodiments shown below.

[0015] 1(A) to 1(D) are schematic diagrams showing a method for producing a highly polar reaction product according to an embodiment of the present invention. The method for producing a highly polar reaction product in this embodiment is a method for synthesizing a highly polar reaction product by reacting low polarity gases with each other. In the method, a low polarity solvent 20 capable of forming a carbon dioxide expanded liquid phase 60 together with carbon dioxide 40 and a high polarity solvent 30 capable of phase separation from the low polarity solvent 20 are introduced into a pressure-resistant vessel 10, and in a state in which the low polarity solvent 20 and the high polarity solvent 30 are phase-separated, a plurality of low polarity gases 50, 40 including carbon dioxide 40 are introduced under pressure (FIG. 1(A)). The process includes: the formation of carbon dioxide expanded liquid phase 60 from the low polarity gas 40 and phase separation from phase 70 containing the high polarity solvent (Figures 1(A) to 1(B)); in the carbon dioxide expanded liquid phase 60, at least two of the multiple low polarity gases 50, 40 react with each other to produce a high polarity reaction product 80 (Figures 1(B) to 1(C)); and the migration of the high polarity reaction product 80 from the carbon dioxide expanded liquid phase 60 to phase 70 containing the high polarity solvent (Figures 1(C) to 1(D)).

[0016] In FIG. 1(A), a low polarity solvent 20 and a high polarity solvent 30 are introduced into a pressure-resistant vessel 10 through an inlet 12, and while the low polarity solvent 20 and the high polarity solvent 30 are in a phase-separated state, multiple types of low polarity gases 50, 40 including carbon dioxide 40 are introduced under pressure.

[0017] The low polarity solvent 20 is not limited as long as it can form the carbon dioxide expanded liquid phase 60 together with the carbon dioxide 40. The low polarity means that it is low polarity enough to form the carbon dioxide expanded liquid phase 60 together with the carbon dioxide 40, and it may be non-polar. When the carbon dioxide 40 is introduced under pressure into the pressure vessel 10 in which the low polarity solvent 20 and the high polarity solvent 30 are present, the carbon dioxide 40 forms the carbon dioxide expanded liquid phase 60 together with the low polarity solvent 20 because the carbon dioxide 40 is non-polar.

[0018] As for the low polarity solvent 20, since the high polarity reaction product 80 easily migrates from the carbon dioxide expanded liquid phase 60 to the high polarity solvent-containing phase 70, the octanol / water partition coefficient (logPow) of the low polarity solvent 20 is preferably 2.0 or more, more preferably 3.0 or more, and even more preferably 3.5 or more. Since it is easy to select a combination with the high polarity solvent 30, the octanol / water partition coefficient (logPow) of the low polarity solvent 20 is preferably 2.0 to 8.0, more preferably 3.0 to 7.0, and even more preferably 3.5 to 6.0.

[0019] Examples of low polarity solvents 20 include, but are not limited to, n-decane (logPow=5.89, bp=174.0°C), n-hexane (logPow=3.90, bp=68.7°C), cyclohexane (logPow=3.40, bp=81.0°C), toluene (logPow=2.69, bp=111.0°C), etc.

[0020] The low polarity solvent 20 is preferably a hydrocarbon, more preferably an alkane. The alkane preferably has 5 to 15 carbon atoms, more preferably 6 to 14 carbon atoms.

[0021] The high polarity solvent 30 is not limited as long as it is a solvent that can be phase-separated from the low polarity solvent 20 and has a higher polarity than the low polarity solvent 20 .

[0022] The highly polar solvent 30 may be a highly polar protic solvent or an highly polar aprotic solvent. Examples of highly polar protic solvents include water, alcohols having 1 to 8 carbon atoms such as methanol and ethanol, and organic acids such as formic acid and acetic acid, with water being preferred for reasons such as ease of handling. By using water as the highly polar solvent 30, the density of the carbon dioxide expanded liquid phase that absorbs and expands carbon dioxide is about 1.00 g / cm 3The density of the carbon dioxide expanded liquid becomes smaller than that of the aqueous phase (i.e., the phase containing the highly polar solvent), and the carbon dioxide expanded liquid becomes the upper phase and the aqueous phase becomes the lower phase, making it easier to separate the two. This makes it possible to carry out continuous production by, for example, designing a continuous tank reactor that circulates only the lower aqueous phase in which the highly polar reaction product is dissolved, which has a great advantage in industrialization. Examples of the aprotic highly polar solvent include dimethylformamide (DMF) and dimethylsulfoxide (DMSO).

[0023] The multiple types of low polarity gases 50, 40 include carbon dioxide 40. The multiple types of low polarity gases 50, 40 are not limited as long as at least two types of low polarity gases react with each other to produce a high polarity reaction product 80. It is preferable that the multiple types of low polarity gases 50 include at least hydrogen.

[0024] If the combination of multiple low polarity gases 50, 40 is carbon dioxide (CO2) and hydrogen (H2), formic acid (CHOOH) can be synthesized as the high polarity reaction product 80. CO2+H2⇒CHOOH

[0025] It is preferable to introduce a catalyst into the pressure vessel 10. Any known catalyst that reacts the above-mentioned low polarity gases with each other to produce a high polarity reaction product can be selected.

[0026] Examples of catalysts for synthesizing formic acid (CHOOH) from carbon dioxide (CO2) and hydrogen (H2) include platinum group catalysts such as ruthenium (Ru), rhodium (Rh), palladium (Pd), and platinum (Pt).

[0027] The catalyst is preferably a hydrophobic catalyst, more specifically, a catalyst using activated carbon (C) which is a hydrophobic carrier, so that the catalyst is unevenly distributed in the carbon dioxide expanded liquid phase 60 containing the low polarity solvent 20 and carbon dioxide 40. For example, palladium on carbon (Pd / C) is an example of a hydrophobic catalyst for synthesizing formic acid (CHOOH) from carbon dioxide (CO2) and hydrogen (H2).

[0028] If the combination of multiple low polarity gases 50, 40 is carbon dioxide (CO2), methane (CH4) and oxygen (O2), methanol (CH3OH) can be synthesized as the high polarity reaction product 80. CH4+(1 / 2)O2⇒CH3OH Examples of catalysts for synthesizing methanol (CH3OH) from methane (CH4) and oxygen (O2) include platinum group catalysts such as ruthenium (Ru), rhodium (Rh), palladium (Pd), and platinum (Pt). A catalyst in which a platinum group element is supported on a hydrophobic carrier such as activated carbon (C) is more preferred.

[0029] If the combination of multiple low polarity gases 50, 40 is carbon dioxide (CO2), nitrogen (N2) and hydrogen (H2), ammonia (NH3) can be synthesized as the high polarity reaction product 80. N2+3H2⇒2NH3 Examples of catalysts for synthesizing ammonia (NH3) from nitrogen (N2) and hydrogen (H2) include platinum group catalysts such as ruthenium (Ru), rhodium (Rh), palladium (Pd), and platinum (Pt).

[0030] If the combination of multiple low polarity gases 50, 40 is carbon dioxide (CO2), carbon monoxide (CO) and hydrogen (H2), methanol (CH3OH) can be synthesized as the high polarity reaction product 80. CO+2H2⇒CH3OH Examples of catalysts for synthesizing methanol (CH3OH) from carbon monoxide (CO) and hydrogen (H2) include platinum group catalysts such as ruthenium (Ru), rhodium (Rh), palladium (Pd), and platinum (Pt).

[0031] As shown in FIG. 1B, the low polarity solvent 20 and carbon dioxide 40 form a carbon dioxide expanded liquid phase 60, which is separated from a phase 70 containing a high polarity solvent. The carbon dioxide expanded liquid phase 60 can absorb a plurality of low polarity gases 50, 40 at a relatively low pressure, so that the reaction between low polarity gases can proceed with high efficiency without excessively high pressure conditions. Even when explosive gases such as hydrogen (H2) and oxygen (O2) are used, high pressure conditions can be avoided, and the risk can be reduced. 1(B) shows a state in which the carbon dioxide expanded liquid phase 60 is in the upper part and the highly polar solvent-containing phase 70 is in the lower part, but the present invention is not limited to this embodiment. It is sufficient that the carbon dioxide expanded liquid phase 60 and the highly polar solvent-containing phase 70 are phase-separated, and the two phases may be in a turbid state by stirring.

[0032] As shown in FIG. 1(C), in the carbon dioxide expanded liquid phase 60, at least two of the multiple low polarity gases 50, 40 react with each other to generate a highly polar reaction product 80. The multiple low polarity gases 50, 40 have a higher affinity with the carbon dioxide expanded liquid phase 60 than the phase 70 containing a highly polar solvent. Therefore, the multiple low polarity gases 50, 40 are unevenly distributed in the carbon dioxide expanded liquid phase 60, and the carbon dioxide expanded liquid phase 60 becomes a reaction field between the multiple low polarity gases. By introducing the multiple low polarity gases 50, 40 while pressurizing them, dissolution into the carbon dioxide expanded liquid phase 60 is promoted, contributing to an improvement in the catalyst turnover number (TON) and catalyst turnover frequency (TOF).

[0033] On the other hand, the highly polar reaction product 80 has a better compatibility with the highly polar solvent-containing phase 70 than with the carbon dioxide expanded liquid phase 60 .

[0034] Thus, as shown in FIG. 1(D), highly polar reaction products 80 migrate from the carbon dioxide expanded liquid phase 60 to the highly polar solvent-containing phase 70. If the highly polar reaction product 80 remains in the reaction field, the concentration of the highly polar reaction product 80 in the reaction field increases, which may cause a decrease in the reaction rate. In many conventional formic acid synthesis processes in an aqueous phase, a base is added as an additive because the pH drop associated with the production of formic acid is a reaction inhibitor. However, in the method for producing a highly polar reaction product of this embodiment, the highly polar reaction product 80 migrates from the carbon dioxide expanded liquid phase 60 to the phase 70 containing a highly polar solvent, so that the concentration of the highly polar reaction product 80 in the carbon dioxide expanded liquid phase 60 can be prevented from becoming excessive without the need for an additive such as a base. Therefore, the migration of the generated highly polar reaction product 80 to the phase 70 containing a highly polar solvent further contributes to an improvement in the catalyst turnover number (TON) and catalyst turnover frequency (TOF). EXAMPLES

[0035] The present invention will be described in more detail below with reference to specific examples, although the present invention is not limited to the following examples.

[0036] [Example 1] Toluene (low polarity solvent, 9 mL), ultrapure water (high polarity solvent, 6 mL), palladium on carbon (Pd / C) (catalyst, 10 mg) and a stirrer were introduced into a pressure vessel, the temperature was raised to 50°C, and the gas phase was replaced with hydrogen. After that, carbon dioxide (CO2) at 5 MPa and hydrogen (H2) at 1 MPa were introduced while stirring at 1000 rpm at 50°C for 3 hours. Palladium on carbon (Pd / C) was adjusted so that the mass ratio of palladium to the total mass of palladium on carbon (Pd / C) was 10 mass%.

[0037] When the stirring was stopped, the lower aqueous phase and the upper carbon dioxide expansion liquid phase separated. When the temperature and pressure were returned to normal, the aqueous phase was analyzed by HPLC under the following conditions. 2.8 mmol of formic acid (CHOOH, elution time: 7-9 min) was detected per 1 g of catalyst. No methanol (CH3OH, elution time: 6-7 min) or formaldehyde (HCHO, elution time: 5-6 min) was detected.

[0038] (HPLC analysis conditions) Analyzer: HPLC (manufactured by JASCO Corporation, LC-200 Plus) Column: Shodex RSpak DE-413L (Showa Denko K.K.) Eluent: Phosphoric acid aqueous solution (10mmol / L) Flow rate: 0.6mL / min Detection device: UV detector Detection wavelength: 250 nm

[0039] [Comparative Example 1] An experiment of Comparative Example 1 was carried out in the same manner as in Example 1, except that toluene (low polarity solvent) was not introduced. HPLC analysis of the aqueous phase under the same conditions detected 0.8 mmol of formic acid (CHOOH) per gram of catalyst, but no methanol (CH3OH) or formaldehyde (HCHO). In many previous studies, an aqueous phase has been used as a reaction field for the liquid-phase synthesis of formic acid from carbon dioxide (CO2) and hydrogen (H2), as in the experiment of Comparative Example 1. However, due to the low solubility of the gaseous reactants, especially hydrogen (H2), the transfer of hydrogen (H2) from the gas phase to the aqueous phase is rate-limiting. In the experiment of Comparative Example 1, in handling the catalyst, the catalyst and the reaction product formic acid exist in the same reaction field (aqueous phase), and therefore a process for separating them after the reaction is required.

[0040] [Comparative Example 2] An experiment of Comparative Example 2 was carried out in the same manner as in Example 1, except that water (highly polar solvent) was not introduced. In the Comparative Example 2 experiment, toluene (a low polarity solvent) formed the carbon dioxide expansion liquid phase. After the reaction, the temperature and pressure were returned to normal, stirring was stopped, 9 mL of ultrapure water was introduced into the reactor, and the mixture was thoroughly stirred at 1000 rpm for about 30 s using a magnetic stirrer. The aqueous phase was then analyzed by HPLC under the same conditions, and no formic acid (CHOOH), methanol (CH3OH), or formaldehyde (HCHO) was detected.

[0041] [Comparative Example 3] Into a pressure vessel containing palladium on carbon (Pd / C) (catalyst, 10 mg), 5 MPa of carbon dioxide (CO2) and 1 MPa of hydrogen (H2) were introduced at 50°C for 3 hours. HPLC analysis of the gas phase revealed that no formic acid (CHOOH), methanol (CH3OH), or formaldehyde (HCHO) were detected. Gas-phase reactions usually require high temperature and pressure conditions. It was confirmed that carbon dioxide (CO2) at 5 MPa and hydrogen (H2) at 1 MPa do not react at 50°C.

[0042] The results of Example 1 and Comparative Examples 1 to 3 are shown in Table 1. In Example 1 of the method for producing a highly polar reaction product of the present invention, formic acid was synthesized with high efficiency from carbon dioxide and hydrogen, which are low polarity gases. Palladium on carbon (Pd / C) is low polarity, so it disperses well in the carbon dioxide expanded liquid phase containing carbon dioxide and toluene (low polarity solvent). Hydrogen, which is a low polarity gas, dissolves in high concentration in the carbon dioxide expanded liquid phase. Formic acid generated on the catalyst needs to be desorbed from the catalyst, but since the desorbed formic acid has a better affinity with the aqueous phase than the carbon dioxide expanded liquid phase, it is considered that the formic acid gradually migrated from the carbon dioxide expanded liquid phase to the aqueous phase. It is considered that these points were the factors that enabled the highly efficient synthesis of formic acid in Example 1. In the experiment of Comparative Example 1, since the catalyst is dispersed in the aqueous phase together with the reaction product formic acid, an operation to separate the formic acid and the catalyst is required. In addition, in many conventional studies on the production of formic acid in an aqueous phase, a base is added as an additive because the decrease in pH accompanying the production of formic acid is a reaction inhibitor. In contrast, in Example 1, the catalyst is unevenly distributed in the carbon dioxide-expanded liquid phase, and formic acid is synthesized in the carbon dioxide-expanded liquid phase. However, the formic acid gradually migrates from the carbon dioxide-expanded liquid phase to the aqueous phase, making it easy to separate the formic acid from the catalyst. In addition, there is no need to add a base, so that continuous and efficient production of formic acid can be expected.

[0043] [Table 1]

[0044] [Examples 2 to 4] The experiments of Examples 2 to 4 were carried out in the same manner as Example 1, except that the stirring at 50°C for 3 hours at 1000 rpm in the experiment of Example 1 was changed to stirring at 30°C (Example 2), 80°C (Example 3), or 100°C (Example 4) for 3 hours at 1000 rpm. When the aqueous phase was analyzed by HPLC under the same conditions, the amount of formic acid (CHOOH) produced per gram of catalyst was shown in Figure 2. In Figure 2, the horizontal axis is the reaction temperature [°C], and the vertical axis is the amount of formic acid (CHOOH) produced per gram of catalyst [mmol g -1 No methanol (CH3OH) or formaldehyde (HCHO) was detected.

[0045] From the experiments of Examples 1 to 4, it was found that the reaction rate of the formic acid production reaction in the method for producing a highly polar reaction product of the present invention is higher at lower temperatures, and the reaction proceeds only with pressurization and stirring without requiring any external heating. In addition, it is thought that the pH of the aqueous phase decreases as formic acid is produced, but the effect on the carbon dioxide expanded liquid phase, which is the main reaction site, is small, and it was found that the reaction proceeds continuously without the use of additives such as bases.

[0046] [Examples 5 to 6] The experiment of Example 5 was carried out in the same manner as in Example 1, except that in the experiment of Example 1, the introduction of toluene (low polarity solvent, 9 mL) was changed to the introduction of n-hexane (low polarity solvent, 9 mL). In addition, the experiment of Example 6 was carried out in the same manner as Example 5, except that in the experiment of Example 5 (n-hexane), stirring at 1000 rpm for 3 hours at 50°C was changed to stirring at 1000 rpm for 3 hours at 30°C (Example 6). When the aqueous phase was subjected to HPLC analysis under the same conditions, the amount of formic acid (CHOOH) produced per gram of catalyst was shown in FIG. The amount of formic acid (CHOOH) produced in the experiment in Example 6 (n-hexane, 30°C) was 11.4 mmol / g, which corresponds to a catalyst turnover number (TON) of 73 and a catalyst turnover frequency (TOF) of 24 h. -1 is equivalent to. No methanol (CH3OH) or formaldehyde (HCHO) was detected.

[0047] [Examples 7 to 10] The experiment of Example 7 was carried out in the same manner as in Example 1, except that in the experiment of Example 1, the introduction of toluene (low polarity solvent, 9 mL) was changed to the introduction of n-decane (low polarity solvent, 9 mL). In addition, the experiment of Example 6 was carried out in the same manner as Example 7, except that in the experiment of Example 7 (n-decane), the stirring at 50°C for 3 hours at 1000 rpm was changed to stirring at 30°C (Example 8), 80°C (Example 9), or 100°C (Example 10) for 3 hours at 1000 rpm. When the aqueous phase was analyzed by HPLC under the same conditions, the amount of formic acid (CHOOH) produced per gram of catalyst was shown in Figure 2. No methanol (CH3OH) or formaldehyde (HCHO) was detected.

[0048] [Examples 11 to 13] The experiments of Examples 11 to 13 were carried out in the same manner as in Example 1, except that in the experiment of Example 1 (toluene, 50°C), the introduction of carbon dioxide (CO2) at 5 MPa was changed to the introduction of carbon dioxide (CO2) at 1 MPa (Example 11), 6 MPa (Example 12), or 7 MPa (Example 13). When the aqueous phase was analyzed by HPLC under the same conditions, the amount of formic acid (CHOOH) produced per gram of catalyst was shown in Figure 3. In Figure 3, the horizontal axis is the partial pressure of carbon dioxide (CO2) [MPa], and the vertical axis is the amount of formic acid (CHOOH) produced per gram of catalyst [mmol g -1 No methanol (CH3OH) or formaldehyde (HCHO) was detected. With increasing partial pressure of carbon dioxide, the amount of formic acid (CHOOH) produced increased.

[0049] [Examples 14 to 18] The experiments of Examples 14 to 18 were carried out in the same manner as in Example 6, except that in the experiment of Example 6 (n-hexane, 30°C), the introduction of carbon dioxide (CO2) at 5 MPa was changed to the introduction of carbon dioxide (CO2) at 1 MPa (Example 14), 2 MPa (Example 15), 3 MPa (Example 16), 4 MPa (Example 17), or 6 MPa (Example 18). When the aqueous phase was analyzed by HPLC under the same conditions, the amount of formic acid (CHOOH) produced per gram of catalyst was shown in Figure 3. No methanol (CH3OH) or formaldehyde (HCHO) was detected.

[0050] [Example 19] The experiment of Example 19 was carried out in the same manner as in Example 1, except that in the experiment of Example 1, the introduction of toluene (low polarity solvent, 9 mL) was changed to the introduction of cyclohexane (low polarity solvent, 9 mL). The aqueous phase was subjected to HPLC analysis under the same conditions to measure the amount of formic acid (CHOOH) produced per gram of catalyst. The measurement results of Example 19 are shown in FIG. 4 together with the measurement results of Examples 1, 5, and 7. In FIG. 4, the horizontal axis represents the octanol / water partition coefficient (logPow), and the vertical axis represents the amount of formic acid (CHOOH) produced per gram of catalyst [mmol g -1 No methanol (CH3OH) or formaldehyde (HCHO) was detected.

[0051] As shown in Figure 4, a good positive correlation was obtained between the octanol / water partition coefficient (logPow) of the low polarity solvent and the amount of formic acid produced. Because formic acid produced on the catalyst surface exhibits polarity, this result suggests that the lower the affinity of the highly polar reaction product with the low polarity solvent and the carbon dioxide expanded liquid phase, the more the desorption of formic acid from the catalyst and the migration of formic acid from the carbon dioxide expanded liquid phase to the aqueous phase are promoted.

[0052] [Example 20] The experiment of Example 20 was carried out in the same manner as in Example 6, except that in the experiment of Example 6 (n-hexane, 30°C), the introduction of carbon dioxide (CO2) at 5 MPa and hydrogen (H2) at 1 MPa was changed to the introduction of carbon dioxide (CO2) at 4 MPa and hydrogen (H2) at 4 MPa. When the aqueous phase was analyzed by HPLC under the same conditions, the amount of formic acid (CHOOH) produced per gram of catalyst was 23.1 mmol / g. This corresponds to a catalyst turnover number (TON) of 148 and a catalyst turnover frequency (TOF) of 49 h -1 No methanol (CH3OH) or formaldehyde (HCHO) was detected.

[0053] [Example 21] The experiment of Example 21 was carried out in the same manner as in Example 7, except that in the experiment of Example 7 (n-decane, 30°C), the introduction of carbon dioxide (CO2) at 5 MPa and hydrogen (H2) at 1 MPa was changed to the introduction of carbon dioxide (CO2) at 4 MPa and hydrogen (H2) at 4 MPa. When the aqueous phase was analyzed by HPLC under the same conditions, the amount of formic acid (CHOOH) produced per gram of catalyst was 25.5 mmol / g. This corresponds to a catalyst turnover number (TON) of 163 and a catalyst turnover frequency (TOF) of 55 h -1 No methanol (CH3OH) or formaldehyde (HCHO) was detected.

[0054] The results of Examples 19 to 21 are shown in Table 2 in comparison with the results of a previous study on the synthesis of formic acid from carbon dioxide (CO2) and hydrogen (H2). The methods for synthesizing formic acid from carbon dioxide (CO2) and hydrogen (H2) disclosed in Examples 19 to 21 were shown to be significantly superior in terms of catalyst turnover frequency (TOF) to previous studies in experiments at a reaction temperature of 30°C.

[0055] [Table 2] [Industrial Applicability]

[0056] The present invention can, for example, react low-polarity gases such as carbon dioxide (CO2) and hydrogen (H2) with each other at room temperature to synthesize high-polarity reaction products such as formic acid with high efficiency. As a technology for effectively utilizing carbon dioxide (CO2) toward realizing a carbon-free society, technological advances in carbon dioxide capture and storage (CCS) have made it relatively easy to concentrate emitted carbon dioxide, and it is expected that this technology will be used in industries that emit large amounts of carbon dioxide (CO2) during the operation of large plants, steel mills, power plants, and other such facilities. The direct conversion of low polarity gases to high polarity reaction products according to the present invention can be achieved at low cost without the addition of external energy such as light, electricity or heat. The method for producing a highly polar reaction product of the present invention utilizes a known catalyst to react various low polarity gases with each other at room temperature, and can be used to produce a large number of highly polar compounds. [Explanation of symbols]

[0057] 10...pressure vessel, 20...low polarity solvent, 30...high polarity solvent, 40...carbon dioxide, 50...low polarity gas, 60...carbon dioxide expanded liquid phase, 70...phase containing high polarity solvent, 80...high polarity reaction product

Claims

1. A method for producing a highly polar reaction product by reacting low-polarity gases with each other to synthesize a highly polar reaction product, comprising: introducing into a pressure-resistant container a low-polarity solvent capable of forming a phase of a carbon dioxide-expanded liquid together with carbon dioxide and a high-polarity solvent capable of phase-separating from the low-polarity solvent, and introducing a plurality of types of low-polarity gases containing carbon dioxide while pressurizing them in a state where the low-polarity solvent and the high-polarity solvent are phase-separated.

2. The production method according to claim 1, wherein the high-polarity solvent is water.

3. The production method according to claim 1 or 2, wherein the octanol / water partition coefficient (logPow) of the low-polarity solvent is 2.0 to 8.

0.

4. The production method according to claim 1 or 2, wherein the plurality of types of low-polarity gases contain at least hydrogen.

5. The plurality of types of low-polarity gases contain carbon dioxide and hydrogen, and the production method according to claim 4, wherein the highly polar reaction product contains formic acid.

6. The production method according to claim 1 or 2, wherein a catalyst is introduced into the pressure-resistant container.

7. The production method according to claim 6, wherein the catalyst is a hydrophobic catalyst.

8. The production method according to claim 1 or 2, wherein the low-polarity solvent is a hydrocarbon.

9. The production method according to claim 8, wherein the low-polarity solvent is an alkane.

10. A production system for a highly polar reaction product by reacting low-polarity gases with each other to synthesize a highly polar reaction product, comprising: a pressure-resistant container containing a low-polarity solvent and a high-polarity solvent and capable of introducing a predetermined gas into the interior while pressurizing it through an inlet provided at the upper part, wherein the low-polarity solvent is a low-polarity solvent capable of forming a phase of a carbon dioxide-expanded liquid together with carbon dioxide and is accommodated in the pressure-resistant container in a state of being phase-separated from the high-polarity solvent, and the predetermined gas is a plurality of types of low-polarity gases containing carbon dioxide. A production system for a highly polar reaction product.

11. In the phase of the carbon dioxide-expanded liquid formed by the low-polarity solvent and carbon dioxide, among the low-polarity gases, at least two types of low-polarity gases react with each other to generate a highly polar reaction product. The production system for a highly polar reaction product according to claim 10.

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