Isolation structure and isolation method

Abstract

To provide a separation method which can efficiently recovery carbon dioxide.SOLUTION: A separation method includes a precipitation step and a separation step. The precipitation step supplies carbon dioxide to absorption liquid 10A, and thereby produces a mixture 10B in which a product B formed by bonding carbon dioxide to amine A is precipitated in a solvent. The first separation step separates a solvent 10 contained in the mixture 10B produced in the precipitation step and the product B from each other.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a separation method. [Background technology]

[0002] Carbon dioxide (CO2), which is thought to be one of the causes of global warming, has been directly removed from gases (e.g., air) containing CO2 (DAC: Direct Air Capture) through a technology that has been developed.

[0003] For example, Patent Document 1 mentions DAC using an aqueous amine solution as a carbon dioxide absorption liquid. When carbon dioxide is dissolved in an aqueous amine solution, the neutral amine and carbon dioxide react to generate carbamate ions and protonated amines, thereby absorbing the carbon dioxide. On the other hand, when the carbamate ions and protonated amines are heated, neutral amines and carbon dioxide are generated, thereby recovering the carbon dioxide. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2020-521625 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the DAC using an aqueous amine solution as the carbon dioxide absorbing solution, it is necessary to heat the entire absorbing solution that has absorbed carbon dioxide, which is troublesome.

[0006] An object of the present invention is to provide a separation method that can easily recover carbon dioxide. [Means for solving the problem]

[0007] The separation method according to the present invention includes a precipitation step and a separation step. In the precipitation step, carbon dioxide is supplied to an absorption liquid containing a solvent and an amine dissolved in the solvent, thereby producing a mixture in which a product formed by carbon dioxide bonding with the amine is precipitated in the solvent. In the separation step, the solvent and the product contained in the mixture produced in the precipitation step are separated. [Effects of the Invention]

[0008] According to the present invention, a separation method capable of efficiently recovering carbon dioxide can be provided. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a flow chart illustrating a separation method according to an embodiment of the present invention. [Figure 2] Schematic diagram for explaining the preparation process [Figure 3] Schematic diagram for explaining the deposition process [Figure 4] Schematic diagram for explaining the first separation step [Figure 5] Schematic diagram for explaining a first heating step [Figure 6] Schematic diagram for explaining the second separation step [Figure 7] Schematic diagram for explaining the second heating step DETAILED DESCRIPTION OF THE INVENTION

[0010] The separation method according to this embodiment is used to recover carbon dioxide. Fig. 1 is a flow diagram for explaining the separation method according to this embodiment. Figs. 2 to 7 are schematic diagrams for explaining the separation method according to this embodiment.

[0011] 1, the separation method according to this embodiment includes a preparation step, a precipitation step, a first separation step, a first heating step, a second separation step, and a second heating step. The steps from the precipitation step to the second heating step can be repeatedly performed.

[0012] 1. Preparation process As shown in FIG. 2, a solvent 10 and an amine A are mixed to prepare an absorbing liquid 10A containing the solvent 10 and the amine A dissolved in the solvent 10.

[0013] For example, dimethyl sulfoxide (DMSO), ether, acetone, alcohol, etc. can be used as the solvent 10. DMSO is particularly suitable in view of its low vapor pressure and low environmental impact.

[0014] When amine A combines with carbon dioxide, it produces product B, which has a lower solubility in solvent 10 than amine A. Examples of amine A that can be used include orthophenylenediamine (o-phenylenediamine), cyclohexylamine, ethylenediamine, and styrene oxide. o-Phenylenediamine is particularly suitable because it dissolves easily in a wide range of solvents, including alcohols and ethers. Cyclohexylamine forms 1,3-dicyclohexylurea, which has a long molecular chain conformation, upon absorbing CO2, making it easy to separate as a solid in the first and second separation steps. Similarly, ethylenediamine forms ammonium carbamate, which has a long molecular chain conformation, upon absorbing CO2, making it easy to separate as a solid in the first and second separation steps.

[0015] The content of the solvent 10 in the absorbing solution 10A can be 70 wt % or more and 95 wt % or less, and the content of the amine A in the absorbing solution 10A can be 5 wt % or more and 30 wt % or less.

[0016] 2.Precipitation process As shown in Fig. 3, carbon dioxide is supplied to the prepared absorption solution 10A, and carbon dioxide combines with amine A to produce product B, which is then precipitated in the solvent. Because the solubility of product B in solvent 10 is lower than the solubility of amine A in solvent 10, product B becomes a solid and precipitates in solvent 10. As a result, a mixture 10B of solvent 10 and product B is produced.

[0017] For example, when solvent 10 is DSMO and amine A is o-phenylenediamine, carbon dioxide combines with o-phenylenediamine to produce 1,3-Dihydro-2H-benzimidazol-2-one. Because the solubility of 2-benzimidazolone in DSMO is lower than that of o-phenylenediamine, the 2-benzimidazolone solidifies and precipitates in the DSMO. Carbon dioxide can be recovered at a high recovery rate of over 95%.

[0018] In this way, carbon dioxide is apparently absorbed into the absorbing solution 10A by producing product B from carbon dioxide and amine A. This step can be carried out at room temperature (for example, 20°C or higher and 25°C or lower) and under normal pressure.

[0019] 3.First separation step The liquid solvent 10 and the solid product B contained in the mixture 10B produced in the precipitation step are separated into solid and liquid, and the product B is collected.

[0020] A PF (particulate filter) in which a first space and a second space are separated by a partition wall can be used for solid-liquid separation of the solvent 10 and the product B. The PF preferably has a so-called honeycomb structure. As a PF having a honeycomb structure, a GPF (gasoline particulate filter) or a DPF (diesel particulate filter) can be used, and details thereof are disclosed in, for example, JP 2014-193782 A, Japanese Patent No. 4136319 A, and WO 2011 / 043434 A.

[0021] In this embodiment, the PF20 shown in FIG. 4 is used for solid-liquid separation. The PF20 has a first space 21, a second space 22, and a partition wall 23. The first space 21 and the second space 22 are separated by the partition wall 23. The partition wall 23 has pores that are small enough to allow the liquid solvent 10 to pass through but not the solid product B. The partition wall 23 can be made of, for example, a ceramic material. The partition wall 23 has a first surface S1 on the first space 21 side and a second surface S2 on the second space 22 side.

[0022] As shown in FIG. 4, when the mixture 10B is supplied to the first space 21, the solvent 10 passes through the partition wall 23 while the product B adheres to the first surface S1 of the partition wall 23.

[0023] As described above, according to this embodiment, since the product B is precipitated in the solvent 10 in the precipitation step, the product B can be easily separated from the solvent 10 in this step by a known solid-liquid separation method.

[0024] Here, when product B adheres to the first surface S1 of the partition wall 23, the pressure loss of the fluid gradually increases. When the amount of adhered product B exceeds a predetermined threshold, the supply of the mixture 10B to the first space 21 is stopped, and the process proceeds to the next first heating step. The amount of adhered product B can be estimated based on the pressure loss value of the fluid.

[0025] 4.First heating process Product B, which has been separated in the first separation step and adhered to the first surface S1 of the partition wall 23, is heated to produce an amine and carbon dioxide. As a result, carbon dioxide is liberated from product B, and solid amine A is produced (regenerated), as shown in Fig. 5. Amine A remains adhered to the first surface S1 of the partition wall 23.

[0026] For example, when product B is 2-benzimidazolone, the 2-benzimidazolone dissociates into o-phenylenediamine and carbon dioxide by heating at a temperature of 50° C. or higher and 60° C. or lower under normal pressure.

[0027] As described above, in this embodiment, it is only necessary to heat the solid product B separated from the liquid solvent 10, and therefore carbon dioxide can be easily recovered.

[0028] In this step, product B may be heated by externally heating PF20, or product B may be heated by supplying hot air to product B. Fig. 5 illustrates the case where hot air is supplied from the first space 21 side.

[0029] 5.Second separation step In this step, similarly to the first separation step, the solvent 10 and product B contained in the mixture 10B are subjected to solid-liquid separation, while the amine A produced in the first heating step is dissolved in the separated solvent 10. Thus, in this step, the collection of product B and the removal (recovery) of amine A proceed simultaneously.

[0030] In this embodiment, as shown in Fig. 6, the mixture 10B produced in the precipitation step is supplied to the second space 22. Then, the solvent 10 passes through the partition wall 23, while the product B adheres to the second surface S2 of the partition wall 23. Furthermore, the amine A left on the first surface S1 of the partition wall 23 in the first heating step dissolves in the solvent 10 which passes through the partition wall 23 and flows into the first space 21. The dissolution of the amine A in the solvent 10 results in the preparation of a new absorption liquid 10A'. The newly prepared absorption liquid 10A' is recovered from the first space 21 to the outside and is subjected to the precipitation step.

[0031] In this way, by using the solvent 10 contained in the mixture 10B, the amine A produced in the first heating step can be easily removed. In particular, in this embodiment, since the mixture 10B is supplied to the second space 22, the amine A can be smoothly backwashed by the solvent 10 passing through the partition wall 23.

[0032] Here, similarly to the first separation step, the pressure loss of the fluid gradually increases when product B adheres to second surface S2 of partition wall 23. When the amount of adhered product B exceeds a predetermined threshold, the supply of mixture 10B to second space 22 is stopped, and the process proceeds to the next second heating step.

[0033] 6.Second heating process Product B, which has been separated in the second separation step and adhered to the second surface S2 of the partition wall 23, is heated to produce an amine and carbon dioxide. As a result, carbon dioxide is liberated from product B, and solid amine A is produced (regenerated), as shown in Fig. 7. Amine A remains adhered to the second surface S2 of the partition wall 23.

[0034] In this step, product B may be heated by externally heating PF20, or product B may be heated by supplying hot air to product B. Fig. 7 illustrates the case where hot air is supplied from the second space 22 side.

[0035] 7. After the second heating process When the second heating step is completed, the process returns to the first separation step. That is, by supplying the mixture 10B to the first space 21, the mixture 10B is separated into the solvent 10 and the product B in a solid-liquid state.

[0036] However, in the second and subsequent first separation steps, the solvent 10 and product B contained in the mixture 10B are subjected to solid-liquid separation, while the amine A produced in the second heating step dissolves in the separated solvent 10. In this way, in the second and subsequent first separation steps, the collection of product B and the removal (recovery) of amine A proceed simultaneously, as described in the second separation step.

[0037] (Modification of the embodiment) Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention.

[0038] [Variation 1] In the above embodiment, the separation method includes the preparation step, the precipitation step, the first separation step, the first heating step, the second separation step, and the second heating step, but the preparation step, the first heating step, the second separation step, and the second heating step are optional steps. The separation method only needs to include at least the precipitation step and the first separation step.

[0039] [Variation 2] In the above embodiment, the mixture 10B is supplied to the second space 22 in the second separation step, but the mixture 10B may be supplied to the first space 21.

[0040] In this case, product B adheres to the first surface S1 of partition wall 23, while amine A adhering to first surface S1 dissolves in solvent 10 and passes through partition wall 23. In this way, even if mixture 10B is supplied to first space 21 in the second separation step, collection of product B and removal of amine A can proceed simultaneously.

[0041] However, if the amine A dissolves in the solvent 10, the viscosity may increase, making it difficult for the amine A to pass through the partition wall 23. Therefore, it is preferable to backwash the amine A as in the above embodiment rather than forward wash the amine A as in this modified example.

[0042] When the mixture 10B is supplied to the first space 21 in the second separation step, the amine A remains on the first surface S1 of the partition wall 23 in the second heating step, and in the second or subsequent first separation steps, the product B adheres to the first surface S1 of the partition wall 23, while the amine A adhering to the first surface S1 dissolves in the solvent 10 and passes through the partition wall 23. [Explanation of symbols]

[0043] A amine B product 10 Solvent 10A Absorbent 10B mixture 20 PF (particulate filter) 21 1st space 22 Second space 23 Bulkhead S1 First Surface S2 Second Surface

Claims

1. a precipitating step of supplying carbon dioxide to an absorption liquid containing a solvent and an amine dissolved in the solvent, thereby producing a mixture in which a product in which carbon dioxide is bound to the amine is precipitated in the solvent; a first separation step of separating the solvent and the product contained in the mixture produced in the precipitation step; a first heating step, after the first separation step, of heating the product separated in the first separation step to produce an amine and carbon dioxide; a second separation step, after the first heating step, of separating the solvent and the product contained in the mixture produced in the precipitating step, and dissolving the amine produced in the first heating step in the separated solvent; A separation method comprising:

2. In the first and second separation steps, a particulate filter in which a first space and a second space are separated by a partition wall is used, In the first separation step, the mixture is supplied to the first space, In the second separation step, the mixture is supplied to the second space. The separation method according to claim 1 .

3. After the second separation step, a second heating step is further provided in which the product separated in the second separation step is heated to produce an amine and carbon dioxide. The separation method according to claim 1 or 2.

4. a precipitating step of supplying carbon dioxide to an absorption liquid containing a solvent and an amine dissolved in the solvent, thereby producing a mixture in which a product in which carbon dioxide is bound to the amine is precipitated in the solvent; a first separation step of separating the solvent and the product contained in the mixture produced in the precipitation step; Equipped with the solvent is dimethyl sulfoxide, the amine is orthophenylenediamine, The product is 2-benzimidazolone. Separation method.

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