Basic subcritical water composition, water-containing composition, device, and container

Abstract

The purpose of the present disclosure is to provide: a basic subcritical water composition capable of decomposing polymers and the like while suppressing corrosion of a reactor apparatus; a water-containing composition; a device; and a container. The present disclosure involves a basic subcritical water composition having a pH of 13.7 or less and a potential of 400 mV or more when the current density exceeds 10 mA / cm2 in an anodic polarization curve when using a steel material as a test electrode.

Description

Basic subcritical water composition, water-containing composition, device, and container

[0001] The present disclosure relates to basic subcritical water compositions, water-containing compositions, devices, and containers.

[0002] In recent years, the need for environmental conservation and the creation of a resource-circulating society has been considered, and various studies have been conducted on the recycling of organic materials such as plastics. Among these, decomposition treatment techniques using subcritical water are being used. For example, Patent Document 1 and Non-Patent Document 1 describe methods for decomposing fluorine-containing polymers by reacting them in subcritical water containing a basic compound such as potassium hydroxide.

[0003] Japanese Patent Application Laid-Open No. 2021-155478

[0004] Jin Hamaura et al. , Eur. Polym. J. 182 (2023), 111724

[0005] An object of the present disclosure is to provide a basic subcritical water composition, a water-containing composition, an apparatus, and a container that can decompose polymers and the like while suppressing corrosion of a reaction apparatus.

[0006] The present disclosure (1) is a method for producing a solution having a pH of 13.7 or less, and a current density of 10 mA / cm in an anodic polarization curve using a steel material as a test electrode. ２ The present invention relates to a basic subcritical water composition having a potential of 400 mV or more when the potential exceeds 100 mV.

[0007] The present disclosure (2) is the basic subcritical water composition of the present disclosure (1) at a temperature of 180°C or higher and lower than 250°C.

[0008] The present disclosure (3) is the basic subcritical water composition according to the present disclosure (1) or (2), in which the steel material contains 8 mass % or more of Ni.

[0009] The present disclosure (4) is a basic subcritical water composition having a pH of 13 or more and 13.5 or less, a temperature of 200°C or more and 235°C or less, and any combination with any of the present disclosures (1) to (3), wherein the steel material contains 15 mass% or more of Ni and 10 mass% or more of Cr.

[0010] The present disclosure (5) also provides a method for producing a galvanic electrode at a temperature of 180°C or higher and lower than 250°C, in which a current density is 10 mA / cm in an anodic polarization curve using a steel material as a test electrode. ２ The water-containing composition has a potential of 400 mV or more and 900 mV or less when the potential exceeds the threshold.

[0011] The present disclosure (6) is the water-containing composition of the present disclosure (5), in which the steel material contains 8 mass% or more of Ni.

[0012] The present disclosure (7) is a water-containing composition according to the present disclosure (5) or (6), having a pH of 10 or more and 13.7 or less.

[0013] The present disclosure (8) is a water-containing composition having a pH of 13 or more and 13.5 or less, a temperature of 200°C or more and 235°C or less, and the steel material containing 15% by mass or more of Ni and 10% by mass or more of Cr, and any combination with any of the present disclosures (5) to (7).

[0014] The present disclosure (9) relates to an apparatus comprising a basic subcritical water composition in any combination with any of the present disclosures (1) to (4), or a water-containing composition in any combination with any of the present disclosures (5) to (8).

[0015] The present disclosure (10) relates to a container comprising a basic subcritical water composition in any combination with any of the present disclosures (1) to (4), or a water-containing composition in any combination with any of the present disclosures (5) to (8).

[0016] According to the present disclosure, it is possible to provide a basic subcritical water composition, a water-containing composition, an apparatus, and a container that can decompose polymers and the like while suppressing corrosion of a reaction apparatus.

[0017] The present disclosure will be specifically described below.

[0018] The present disclosure relates to an anodic polarization curve in which the pH is 13.7 or less and a steel material is used as a test electrode, and the current density is 10 mA / cm ２ The present disclosure relates to a basic subcritical water composition having a potential of 400 mV or more when the potential exceeds 100 mV. Because the basic subcritical water composition of the present disclosure has the above-described configuration, it can be used in subcritical water treatment of various objects while suppressing corrosion of the reaction equipment. For example, it can decompose polymers and the like.

[0019] The basic subcritical water composition of the present disclosure contains subcritical water. Subcritical water is water that is pressurized to a liquid state at a temperature above 100°C and lower than the critical temperature of 374°C. Subcritical water has different physical properties from water at temperatures below 100°C. In particular, subcritical water in the range of 200°C to 300°C has a significantly reduced dielectric constant, exhibiting lipid solubility almost equivalent to that of methanol or acetone at room temperature, and exhibiting lipid solubility of 10% or less at room temperature. －１４ The ion product, which was mol / L, is 10 －１１ The temperature of the basic subcritical water composition of the present disclosure is preferably less than 250°C, more preferably 245°C or less, even more preferably 240°C or less, and even more preferably 235°C or less; it is also preferably 180°C or more, more preferably 200°C or more, even more preferably 205°C or more, even more preferably 210°C or more, particularly preferably 215°C or more, even more preferably 220°C or more, and especially preferably 225°C or more.

[0020] The water used to prepare subcritical water is not particularly limited, and any type of water may be used, such as tap water, ion-exchanged water, distilled water, or well water, but ion-exchanged water and distilled water are preferred from the viewpoint of suppressing side reactions caused by the influence of coexisting salts, etc. The amount of water used should be enough to fully immerse the object to be treated, but care must be taken not to introduce an extremely small amount of water into the sealed container for pressurization, as the water will all turn into steam after heating and will not become subcritical water.

[0021] The basic subcritical water composition of the present disclosure preferably contains at least one basic compound selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides.

[0022] Examples of alkali metal hydroxides include lithium hydroxide, sodium hydroxide, potassium hydroxide, and cesium hydroxide. Among these, sodium hydroxide and / or potassium hydroxide are preferred. Potassium hydroxide is known to have a higher activity and higher basicity than sodium hydroxide in a concentrated solution. From this perspective, potassium hydroxide is most preferred.

[0023] Examples of alkaline earth metal hydroxides include calcium hydroxide and barium hydroxide.

[0024] The concentration of the basic compound in the basic subcritical water composition is preferably 0.5 M or less, more preferably 0.45 M or less, even more preferably 0.40 M or less, and even more preferably 0.35 M or less, and is preferably 0.01 M or more, more preferably 0.05 M or more, even more preferably 0.10 M or more, and even more preferably 0.15 M or more. As is well known to those skilled in the art, the unit "M" means mol / L.

[0025] The basic subcritical water composition of the present disclosure exhibits a current density of 10 mA / cm in an anodic polarization curve using a steel material as a test electrode. ２ In the anodic polarization curve using a steel material as the test electrode, the potential when the current density exceeds 10 mA / cm is 400 mV or more. ２ When the potential exceeds this value, it is preferably 450 mV or more, more preferably 500 mV or more, even more preferably 550 mV or more, and is preferably 900 mV or less.

[0026] The anodic polarization curve is measured using a potentiostat at a potential sweep rate of 20 mV / min in accordance with JIS G0577.

[0027] The steel material preferably contains at least one element selected from the group consisting of Ni, Cr, and Fe.

[0028] The steel preferably contains 8% by mass or more of Ni, more preferably 15% by mass or more, and even more preferably 70% by mass or more. The upper limit is not particularly limited, and is usually 90% by mass.

[0029] The steel material preferably contains 10 mass % or more of Cr, more preferably 20 mass % or more, and preferably 40 mass % or less, more preferably 30 mass % or less.

[0030] The steel material preferably contains 5% by mass or more of Fe, more preferably 20% by mass or more, and even more preferably 40% by mass or more, and preferably 80% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less of Fe.

[0031] Examples of the steel material include SUS310S, SUS304L, and NCF600.

[0032] The basic subcritical water composition of the present disclosure has a pH of 13.7 or less. The pH of the basic subcritical water composition is preferably 10 or more, more preferably 11 or more, even more preferably 12 or more, and even more preferably 13 or more, and is preferably 13.6 or less, more preferably 13.5 or less.

[0033] The present disclosure also provides a method for producing a galvanic electrode using a steel material at a temperature of 180°C or higher and lower than 250°C, in which the current density is 10 mA / cm ２ The water-containing composition of the present disclosure has a potential of 400 mV or more and 900 mV or less when the potential exceeds 100 mV. Because the water-containing composition of the present disclosure has the above-mentioned configuration, it can be used to treat various objects while suppressing corrosion of reaction equipment. For example, it can decompose polymers and the like.

[0034] The temperature of the water-containing composition of the present disclosure is less than 250°C, preferably 245°C or less, more preferably 240°C or less, and even more preferably 235°C or less, and is 180°C or more, preferably 200°C or more, more preferably 205°C or more, even more preferably 210°C or more, even more preferably 215°C or more, particularly preferably 220°C or more, and even more preferably 225°C or more.

[0035] The water-containing composition of the present disclosure exhibits a current density of 10 mA / cm in an anodic polarization curve using a steel material as a test electrode. ２ In the anodic polarization curve using a steel material as the test electrode, the potential when the current density exceeds 10 mA / cm is 400 mV or more and 900 mV or less. ２ When the potential exceeds this value, it is preferably 450 mV or more, more preferably 500 mV or more, and even more preferably 550 mV or more.

[0036] In the water-containing composition of the present disclosure, the steel material may be any of those listed in the basic subcritical water composition of the present disclosure.

[0037] The water-containing composition of the present disclosure preferably comprises subcritical water.

[0038] The water-containing composition of the present disclosure preferably contains at least one basic compound selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides. As the alkali metal hydroxide and alkaline earth metal hydroxide, those exemplified for the basic subcritical water composition of the present disclosure can be used.

[0039] The concentration of the basic compound in the water-containing composition of the present disclosure can be in the same range as described for the basic subcritical water composition of the present disclosure.

[0040] The pH of the water-containing composition of the present disclosure is preferably 10 or higher, more preferably 11 or higher, even more preferably 12 or higher, and even more preferably 13 or higher, and is preferably 13.7 or lower, more preferably 13.6 or lower, and even more preferably 13.5 or lower.

[0041] The basic subcritical water composition and water-containing composition of the present disclosure are preferably used in contact with the above-mentioned steel material. For example, they are more preferably used in contact with a container made of the above-mentioned steel material. They are also preferably used for treating an object (preferably subcritical water treatment) in a container made of the above-mentioned steel material. The basic subcritical water composition and water-containing composition of the present disclosure are unlikely to corrode the above-mentioned steel material even when they come into contact with the steel material.

[0042] The basic subcritical water composition and water-containing composition of the present disclosure can be used to treat various objects, and can be preferably used in subcritical water treatment, and is suitable for decomposing polymers and the like.

[0043] Examples of the polymer include polyolefin resins such as polyethylene and polypropylene; polyamide [PA] resins such as nylon 6, nylon 11, nylon 12, nylon 46, nylon 66, nylon 610, nylon 612, and nylon MXD6; polyester resins such as polyethylene terephthalate [PET], polybutylene terephthalate [PBT], polyarylate, aromatic polyester (including liquid crystal polyester), and polycarbonate [PC]; polyacetal [POM] resin; polyether resins such as polyphenylene oxide [PPO], modified polyphenylene ether, and polyether ether ketone [PEEK]; polyamide imide [PAI] resins such as polyamino bismaleimide; polysulfone resins such as polysulfone [PSF] and polyethersulfone [PES]; vinyl polymers such as ABS resin and poly 4-methylpentene-1 (TPX resin), as well as polyphenylene sulfide [PPS], polyketone sulfide, polyetherimide, and polyimide [PI]. Further examples include fluororesins such as ethylene (Et) / TFE copolymer (ETFE), polyvinyl fluoride (PVF), and polyvinylidene fluoride (PVdF). The nylon MXD6 is a crystalline polycondensate obtained from metaxylenediamine (MXD) and adipic acid. Polycondensation systems such as polyester resins and epoxy resins are preferred because they are easily depolymerized, with polyester resins being more preferred. Oligomers constituting polymers and oligomers to which functional groups have been added may also be used. The use of the basic subcritical water composition and water-containing composition of the present disclosure can promote the decomposition of the above polymers and the like.

[0044] Next, a method for decomposing a polymer by reacting it in the basic subcritical water composition and water-containing composition of the present disclosure will be described. For example, water, the polymer to be treated, and optionally a basic compound are added to a pressure vessel of a size appropriate for the amount of the polymer to be treated, and the pressure vessel is then pressurized and sealed. To pressurize the pressure vessel, a gas may be enclosed. Examples of such gases include air, argon, and nitrogen. The degree of pressurization may be about 0.5 MPa, but is not particularly limited thereto.

[0045] The pressure vessel that has undergone the above process is heated to initiate the decomposition reaction. The basic subcritical water composition and water-containing composition of the present disclosure may be produced in the pressure vessel during the decomposition reaction. The heating temperature is less than 250°C, but is preferably 245°C or less, more preferably 240°C or less, and even more preferably 235°C or less. It is also preferably 180°C or more, more preferably 200°C or more, more preferably 205°C or more, even more preferably 210°C or more, even more preferably 215°C or more, particularly preferably 220°C or more, and even more preferably 225°C or more. If the pressure vessel itself is equipped with a heating means, heating can be performed using that heating means. If the pressure vessel itself is not equipped with a heating means, the entire pressure vessel can be heated in an autoclave or oven. The reaction time can be approximately 1 minute to 100 hours, and may be 1 hour to 100 hours, but 1 minute to 1 hour is preferred, and 1 to 30 minutes is more preferred. The reaction pressure can be approximately 0.1 to 22 MPa.

[0046] The aqueous solution after the decomposition reaction contains the monomers and hydrocarbon compounds that constituted the polymer. The decomposition method may include a recovery step of recovering the produced monomers and hydrocarbon compounds after the decomposition step. By including the recovery step, the decomposition method can make effective use of resources.

[0047] The decomposition method preferably includes, prior to the decomposition step, a pulverization step of pulverizing the polymer into pulverized particles having a maximum linear length of 3 mm or less. By including the pulverization step in the decomposition method, the polymer can be easily decomposed.

[0048] The pulverization method is not particularly limited, but includes freeze pulverization, disk mill, hammer mill, stone mill, jet mill, and the like.

[0049] The grinding temperature is preferably −200° C. or higher and 90° C. or lower, more preferably 40° C. or lower, and even more preferably 0° C. or lower.

[0050] The maximum linear length of the pulverized polymer particles is preferably 3 mm or less, more preferably 2 mm or less, even more preferably 1 mm or less, and particularly preferably 500 μm or less. Also, it is preferably 10 μm or more, more preferably 30 μm or more, and even more preferably 100 μm or more. When the average particle size of the pulverized polymer particles is within the above range, the polymer is more easily decomposed.

[0051] The maximum linear length was determined by observing 100 or more secondary particles using SEM images, measuring the major axis of each secondary particle, and determining the largest major axis among the secondary particles.

[0052] The present disclosure also relates to an apparatus comprising the above-described basic subcritical water composition or the above-described water-containing composition.

[0053] The basic subcritical water composition and water-containing composition of the present disclosure can be used to treat various objects while suppressing corrosion of the reaction equipment, and can preferably be used for subcritical water treatment, making the apparatus of the present disclosure suitable for use in subcritical water treatment.Furthermore, the basic subcritical water composition and water-containing composition of the present disclosure can decompose polymers and the like while suppressing corrosion of the reaction equipment, making the apparatus of the present disclosure particularly suitable for use in decomposing polymers and the like.

[0054] In the apparatus of the present disclosure, the portion that comes into contact with the basic subcritical water composition and the water-containing composition is preferably made of the above-mentioned steel material. The apparatus of the present disclosure also preferably includes the container of the present disclosure described below.

[0055] The present disclosure also relates to a container comprising the above-described basic subcritical water composition or the above-described water-containing composition.

[0056] The basic subcritical water composition and water-containing composition of the present disclosure can be used to treat various objects, preferably for subcritical water treatment, while suppressing corrosion of a reaction apparatus, and therefore the container of the present disclosure is suitable as a container used for subcritical water treatment. Furthermore, the basic subcritical water composition and water-containing composition of the present disclosure can decompose polymers and the like while suppressing corrosion of a reaction apparatus, and therefore the container of the present disclosure is particularly suitable as a container used for decomposing polymers and the like.

[0057] The container of the present disclosure is preferably made from the steel material described above.

[0058] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

[0059] Next, the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0060] The values ​​in the examples were measured by the following methods.

[0061] (1) Measurement of corrosion initiation potential The anodic polarization curve was measured in accordance with JIS G0577. The potential was measured from the natural potential by a potentiostat using a dynamic potential method at a potential sweep rate of 20 mV / min and a current density of 10 mA / cm. ２ The potential at which this was reached was taken as the corrosion initiation potential.

[0062] (Example 1) NCF600 (Ni: 72.00 mass% or more, Cr: 14.00 to 17.00 mass%, Fe: 6.00 to 10.00 mass%) was used as a test electrode, and an aqueous potassium hydroxide solution adjusted to pH 13.5 was placed in a container, pressurized to 0.8 MPa with argon gas, and then heated to 230°C. The voltage was increased using a potentiostat at a potential sweep rate of 20 mV / min, and the current density was 10 mA / cm. ２ The potential when the potential exceeded the limit was confirmed. The results are shown in Table 1.

[0063] (Example 2) NCF600 was used as a test electrode, and an aqueous potassium hydroxide solution adjusted to pH 13 was placed in a container, pressurized to 0.8 MPa with argon gas, and then heated to 230° C. Using a potentiostat, the voltage was increased at a potential sweep rate of 20 mV / min, and the current density was 10 mA / cm. ２ The potential when the potential exceeded the limit was confirmed. The results are shown in Table 1.

[0064] (Example 3) A test electrode was made of SUS310S (Ni: 19.00 to 22.00 mass%, Cr: 24.00 to 26.00 mass%), and a potassium hydroxide aqueous solution adjusted to pH 13 was placed in a container. The container was pressurized to 0.8 MPa with argon gas and then heated to 200°C. The voltage was increased using a potentiostat at a potential sweep rate of 20 mV / min, and the current density was increased to 10 mA / cm. ２ The potential when the potential exceeded the limit was confirmed. The results are shown in Table 1.

[0065] (Example 4) SUS310S was used for the test electrode, and a potassium hydroxide aqueous solution adjusted to pH 13.3 was placed in a container, pressurized to 0.8 MPa with argon gas, and then heated to 200° C. Using a potentiostat, the voltage was increased at a potential sweep rate of 20 mV / min, and the current density was increased to 10 mA / cm. ２ The potential when the potential exceeded the limit was confirmed. The results are shown in Table 1.

[0066] (Example 5) SUS310S was used for the test electrode, and an aqueous potassium hydroxide solution adjusted to pH 13 was placed in a container, pressurized to 0.8 MPa with argon gas, and then heated to 230° C. Using a potentiostat, the voltage was increased at a potential sweep rate of 20 mV / min, and the current density was increased to 10 mA / cm. ２ The potential when the potential exceeded the limit was confirmed. The results are shown in Table 1.

[0067] (Comparative Example 1) NCF600 was used as a test electrode, and an aqueous potassium hydroxide solution adjusted to pH 14 was placed in a container, pressurized to 0.8 MPa with argon gas, and then heated to 230° C. Using a potentiostat, the voltage was increased at a potential sweep rate of 20 mV / min, and the current density was 10 mA / cm. ２ The potential when the potential exceeded the limit was confirmed. The results are shown in Table 1.

[0068] (Comparative Example 2) NCF600 was used as a test electrode, and a potassium hydroxide aqueous solution adjusted to pH 14 was placed in a container, pressurized to 0.8 MPa with argon gas, and then heated to 250° C. Using a potentiostat, the voltage was increased at a potential sweep rate of 20 mV / min, and the current density was increased to 10 mA / cm. ２ The potential when the potential exceeded the limit was confirmed. The results are shown in Table 1.

[0069] (Comparative Example 3) NCF600 was used as a test electrode, and pure water was placed in a container, pressurized to 0.8 MPa with argon gas, and then heated to 200° C. Using a potentiostat, the voltage was increased at a potential sweep rate of 20 mV / min, and the current density was 10 mA / cm ２ The potential when the potential exceeded the limit was confirmed. The results are shown in Table 1.

[0070]

[0071] Example 6: 100 mg of PET film ("Lumirror Film" manufactured by Toray Industries, Inc.) and 20 ml of potassium hydroxide aqueous solution adjusted to pH 13.5 were placed in an inner cylinder, and the inner cylinder was placed in a pressure vessel, which was then closed. The atmosphere inside the pressure vessel was then replaced with nitrogen, and the vessel was placed in an electric furnace and heated to 230°C. Once the internal temperature of the pressure vessel reached 230°C, the reaction was allowed to proceed for 1 minute. The pressure during the reaction was set to 2.8 MPa. After the reaction was completed, the electric furnace was stopped, and the pressure vessel was removed from the furnace and cooled by blowing air. The remaining film after the treatment was recovered, washed with pure water, dried, and then weighed to calculate the remaining amount. The results are shown in Table 2. Since the composition of Example 6 had the same pH, temperature, and composition as the composition of Example 1, the corrosion onset potential was also the same.

[0072] (Examples 7 to 9, Comparative Example 4) In Example 6, an aqueous potassium hydroxide solution adjusted to a pH shown in Table 2 or pure water was used instead of the aqueous potassium hydroxide solution adjusted to pH 13.5, and the reaction temperature, reaction pressure, and reaction time were changed as shown in Table 2, and the remaining amount of film was calculated in the same manner as in Example 6. The results are shown in Table 2. The composition of Example 7 has the same pH, temperature, and composition as the composition of Example 2, the composition of Example 8 has the same composition as the composition of Example 3, and the composition of Example 9 has the same corrosion onset potential as the composition of Example 4.

[0073]

Claims

1. The pH is 13.7 or less, and the current density is 10 mA / cm in the anodic polarization curve using steel as the test electrode. ２ The basic subcritical water composition has a potential of 400 mV or more when the potential exceeds 100 mV.

2. The basic subcritical water composition according to claim 1, which has a temperature of 180°C or higher and lower than 250°C.

3. The basic subcritical water composition according to claim 1 or 2, wherein the steel material contains 8 mass % or more of Ni.

4. A basic subcritical water composition according to any one of claims 1 to 3, having a pH of 13 or more and 13.5 or less, a temperature of 200°C or more and 235°C or less, and the steel material containing 15 mass% or more of Ni and 10 mass% or more of Cr.

5. At 180°C or higher and lower than 250°C, the current density is 10mA / cm2 in the anodic polarization curve using steel as the test electrode. ２ The water-containing composition has a potential of 400 mV or more and 900 mV or less when the potential exceeds the threshold value.

6. The water-containing composition according to claim 5, wherein the steel material contains 8 mass % or more of Ni.

7. The water-containing composition according to claim 5 or 6, having a pH of 10 or more and 13.7 or less.

8. A water-containing composition according to any one of claims 5 to 7, having a pH of 13 or more and 13.5 or less, a temperature of 200°C or more and 235°C or less, and the steel material containing 15 mass% or more of Ni and 10 mass% or more of Cr.

9. An apparatus comprising the basic subcritical water composition according to any one of claims 1 to 4, or the water-containing composition according to any one of claims 5 to 8.

10. A container comprising the basic subcritical water composition according to any one of claims 1 to 4 or the water-containing composition according to any one of claims 5 to 8.

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