Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
  • B01J20/26—Synthetic macromolecular compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/30—Processes for preparing, regenerating, or reactivating
  • B01J20/34—Regenerating or reactivating
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B32/00—Carbon; Compounds thereof
  • C01B32/50—Carbon dioxide

Definitions

• This disclosure relates to a carbon dioxide capture method and a carbon dioxide capture device.
• Japanese Patent Application Laid-Open No. 2019-217430 describes a carbon dioxide absorption method that uses a carbon dioxide absorbent that absorbs carbon dioxide contained in a gas containing moisture and carbon dioxide, the carbon dioxide absorbent containing lithium sodium silicate, and the carbon dioxide absorption method includes a supply step of supplying a gas having a carbon dioxide concentration of 0.1% or more and a relative humidity of 35% or more to the carbon dioxide absorbent.
• JP 2010-505613 A describes a method for adsorbing carbon dioxide using a carbon-based adsorbent having an amine compound supported on the carbon-based adsorbent, the surface of which is hydrophobic.
• JP 2017-170359 A describes a gas separation device equipped with an adsorption tower in which an adsorption process in which one or more gas components in a mixed gas are adsorbed onto a gas adsorbent and a regeneration process in which the gas adsorbent is regenerated by heating with water vapor to desorb the gas components, and the gas separation device is characterized in that the gas adsorbent contains an adsorbent that adsorbs the gas components and a moisture-absorbing heat generating agent.
• JP2010-505613A describes a process for removing carbon dioxide from ambient air, which includes a step of blowing the ambient air into contact with an absorbent to absorb carbon dioxide from the air, and a step of delivering the extracted air to the interior of a greenhouse.
• JP Patent Publication 63-252528 describes an air purification method that alternates between an air purification step in which air is introduced into an adsorption tank to adsorb and separate carbon dioxide, followed by a step in which water vapor is directly introduced to regenerate the adsorbent.
• the method stops the introduction of water vapor when the outlet temperature of the adsorption tank exceeds a set value, determines the moisture content in the adsorption tank corresponding to the amount of water vapor supplied during this period, and adjusts the temperature and humidity of the air to be treated so that the moisture content in the adsorption tank in the latter half of the next adsorption step is maintained at a predetermined value.
• An object of the present invention is to provide a carbon dioxide capture method and a carbon dioxide capture device that capture carbon dioxide efficiently with low energy.
• the present disclosure includes the following aspects.
• a method for recovering carbon dioxide comprising the steps of: immersing the adsorbent having adsorbed carbon dioxide in water; and then desorbing carbon dioxide from the adsorbent under a pressure greater than 0 kPa and not greater than 4.5 kPa.
• ⁇ 6> Further comprising a vaporizer for vaporizing water;
• the water supply means is connected to a flow path for supplying water to the vaporizer and a flow path for supplying water to the adsorbent,
• the carbon dioxide capture device according to ⁇ 4> or ⁇ 5>, wherein a flow path for supplying water vapor to the adsorbent is connected to the vaporizer.
• the carbon dioxide adsorption means has a water-permeable membrane therein, and an adsorbent is disposed on the water-permeable membrane.
• the carbon dioxide recovery device according to any one of ⁇ 4> to ⁇ 7>, further comprising a concentration detection means for detecting a carbon dioxide concentration in a gas containing carbon dioxide supplied to the carbon dioxide adsorption means and a carbon dioxide concentration in a gas discharged from the carbon dioxide adsorption means.
• a concentration detection means for detecting a carbon dioxide concentration in a gas containing carbon dioxide supplied to the carbon dioxide adsorption means and a carbon dioxide concentration in a gas discharged from the carbon dioxide adsorption means.
• ⁇ 9> a means for determining whether or not the adsorbent has reached its carbon dioxide adsorption limit based on data on the carbon dioxide concentration obtained by the concentration detection means;
• the carbon dioxide capture device according to ⁇ 8>, further comprising: a means for stopping the supply of carbon dioxide to the carbon dioxide adsorption means when it is determined that the adsorbent has reached its adsorption limit.
• a carbon dioxide capture method and a carbon dioxide capture device are provided that capture carbon dioxide efficiently using low energy.
• FIG. 1 is a schematic configuration diagram showing a carbon dioxide capture device according to one embodiment of the present disclosure.
• FIG. 2 is a graph showing the amount of carbon dioxide adsorbed when the relative humidity during contact of the mixed gas with the adsorbent in the examples was adjusted to 0%, 10%, 20%, 50%, and 80%.
• FIG. 3 is a diagram showing the amount of adsorbed carbon dioxide when the adsorption step and the desorption step are repeatedly performed.
• FIG. 4 is a diagram showing the amount of adsorbed carbon dioxide when the internal pressure of the adsorbent tank in the desorption step is adjusted to 3 kPa, 4.5 kPa, 6.5 kPa, 10 kPa, and 50 kPa, respectively.
• FIG. 1 is a schematic diagram showing a carbon dioxide capture device according to an embodiment of the present disclosure.
• the carbon dioxide capture device 100 includes a carbon dioxide tank 11 and a nitrogen tank 12, which are examples of means for supplying a gas containing carbon dioxide to an adsorbent, an adsorbent tank 20, which is an example of means for adsorbing carbon dioxide when filled with an adsorbent 21, a water supply device 30, which is an example of means for supplying water, a desorption section 50, which is an example of means for holding the adsorbent in a reduced pressure environment and desorbing carbon dioxide from the adsorbent, and a detector 60, which is an example of means for detecting the concentration of carbon dioxide.
• the carbon dioxide tank 11 is a tank that stores carbon dioxide.
• a flow path P11 is connected to the carbon dioxide tank 11.
• the nitrogen tank 12 is a tank that stores nitrogen.
• a flow path P12 is connected to the nitrogen tank 12.
• Flow path P13 is connected to flow path P11 and flow path P12.
• Flow path P11 is a flow path for supplying carbon dioxide to flow path P13.
• a valve V1 is provided on flow path P11. When valve V1 is open, carbon dioxide is supplied to flow path P13 via P11. On the other hand, when valve V1 is closed, the supply of carbon dioxide is stopped.
• a mass flow controller (not shown) is provided on flow path P11, closer to the carbon dioxide tank 11 than valve V1. The mass flow controller adjusts the flow rate of carbon dioxide.
• Flow path P12 is a flow path for supplying nitrogen to flow path P13.
• Valve V2 is provided on flow path P12. When valve V2 is open, nitrogen is supplied to flow path P13 via flow path P12. On the other hand, when valve V2 is closed, the supply of nitrogen is stopped.
• a mass flow controller (not shown) is provided on P12, closer to the nitrogen tank 12 than valve V2. The mass flow controller adjusts the flow rate of the nitrogen.
• flow path P13 the carbon dioxide supplied from flow path P11 and the nitrogen supplied from flow path P12 are mixed to generate a mixed gas containing carbon dioxide and nitrogen.
• valve V1 When valve V1 is closed and valve V2 is open, only nitrogen is sent to flow path P13.
• the carbon dioxide concentration in the gas containing carbon dioxide is not particularly limited, but it is preferable to set it to about 400 ppm, similar to the carbon dioxide concentration in the atmosphere.
• a mixed gas containing carbon dioxide is supplied to the flow path P13 using the carbon dioxide tank 11 and the nitrogen tank 12, but air may be directly supplied to the flow path P13 without using the carbon dioxide tank 11 and the nitrogen tank 12.
• Flow path P13 branches and is connected to flow path P14 and flow path P15.
• Valve V3 is provided on flow path P14.
• Valve V4 is provided on flow path P15.
• valve V3 When valve V3 is open and valve V4 is closed, gas is sent from flow path P13 to flow path P14. On the other hand, when valve V4 is open and valve V3 is closed, gas is sent from flow path P13 to flow path P15.
• Flow path P14 is connected to detector 60 via flow path P17.
• Valve V6 is provided on flow path P14.
• valve V3 When valve V3 is open, valve V4 is closed, valve V6 is open, and valve V7 (described later) is closed, gas is sent from flow path P13 to detector 60.
• the detector 60 is a device for performing gas analysis (e.g., analyzing the carbon dioxide concentration).
• the detector 60 is, for example, an FT-IR (Fourier transform infrared spectrophotometer).
• FT-IR Fastier transform infrared spectrophotometer
• a carbon dioxide sensor may be provided as the detector 60, and the carbon dioxide concentration may be analyzed by inputting the detection value of the carbon dioxide sensor into a computer and comparing it with a predetermined threshold value.
• the flow path P15 is connected to the upper end (inlet) of the adsorbent tank 20.
• the lower end (outlet) of the adsorbent tank 20 is connected to the flow path P16, which is connected to the detector 60 via the flow path P17.
• a valve V4 is provided on the flow path P15. The details of the adsorbent tank 20 will be described later.
• valve V4 When valve V4 is open, valve V3 is closed, valve V7 is open, and valve V6 is closed, the gas discharged from the lower end (outlet) of the adsorbent tank 20 flows through flow path P16 and is sent to the detector 60.
• flow path P18a and flow path P18b are connected to the water supply device 30.
• the flow path P18a is a flow path for supplying water from the water supply device 30 to the adsorbent tank 20.
• a valve V5a is provided on the flow path P18a. When the valve V5a is open, water flows through the flow path P18a and is supplied to the adsorbent tank 20. On the other hand, when the valve V5a is closed, the supply of water to the adsorbent tank 20 is stopped.
• Flow path P18b is a flow path for supplying water vapor from the water supply device 30 to the adsorbent tank 20.
• a valve V5b and a vaporizer 80 are provided in this order from the water supply device 30 toward the adsorbent tank 20.
• valve V5b When valve V5b is open, water is vaporized in the vaporizer 80 to become water vapor, which flows through flow path P18b and is supplied to the adsorbent tank 20.
• valve V5b is closed, the supply of water vapor to the adsorbent tank 20 is stopped.
• the detector 60 is also connected to the desorption section 50, which is equipped with a vacuum pump (not shown), via a flow path P19.
• the flow path P19 branches, and the flow path other than the flow path connected to the desorption section 50 is a flow path for discharging gas to the outside, and ends in a gas exhaust port.
• Valve V8 is provided on the flow path that branches off from flow path P19 and leads to desorption section 50.
• Valve V9 is provided on the flow path that leads to the gas exhaust port.
• the adsorbent tank 20 has a water-permeable membrane 22 inside, and the adsorbent 21 is arranged in the antigravity direction of the water-permeable membrane 22.
• the relative humidity inside the adsorbent tank 20 can be adjusted to the range of 10% to 50% by sending a predetermined amount of water vapor from the water supply device 30 to the adsorbent tank 20 via the flow path P18b.
• the adsorbent 21 is preferably an anion exchange resin having a quaternary ammonium group.
• the anion exchange resin having a quaternary ammonium group preferably contains a structural unit derived from styrene having a quaternary ammonium group.
• Examples of styrene having a quaternary ammonium group include vinylbenzyltrialkylammonium salts such as vinylbenzyltrimethylammonium salts.
• Examples of the counter ion in the ammonium salt include halide ion, hydroxide ion, phosphate ion, and carboxylate ion.
• the anion exchange resin having a quaternary ammonium group preferably contains a structural unit derived from styrene having a quaternary ammonium group and a structural unit derived from divinylbenzene, more preferably contains a structural unit derived from vinylbenzyltrimethylammonium salt and a structural unit derived from divinylbenzene, and even more preferably contains a structural unit derived from vinylbenzyltrimethylammonium chloride and a structural unit derived from divinylbenzene.
• the water-permeable membrane 22 is not particularly limited as long as it is a membrane that allows water to pass through.
• the permeable membrane is disposed to hold the adsorbent in a predetermined position within the adsorbent tank.
• the permeable membrane is preferably a porous material, and more preferably porous polytetrafluoroethylene.
• the carbon dioxide capture method disclosed herein includes a process of contacting a gas containing carbon dioxide with an adsorbent in an environment with a relative humidity of 10% to 50% to allow the adsorbent to adsorb the carbon dioxide (hereinafter also referred to as the "adsorption process"), and a process of immersing the adsorbent with the carbon dioxide adsorbed in water and then desorbing the carbon dioxide from the adsorbent under a pressure of more than 0 kPa and not more than 4.5 kPa (hereinafter also referred to as the "desorption process").
• valves V1 to V9 are closed. Carbon dioxide is stored in the carbon dioxide tank 11. Nitrogen is stored in the nitrogen tank 12.
• Pretreatment process In the carbon dioxide recovery method of the present disclosure, it is preferable to carry out the following pretreatment step before carrying out the adsorption step and the desorption step.
• the adsorbent is an anion exchange resin
• it is first subjected to ion exchange using an alkaline aqueous solution (e.g., an aqueous sodium hydroxide solution), and then washed with water (preferably ultrapure water). After washing with water, the mixture is dried in a vacuum dryer.
• the drying temperature and drying time are not particularly limited, and can be appropriately adjusted so that the absorbance of water is 0.1 or less.
• the adsorbent is dried with nitrogen until the absorbance of water is less than 0.1.
• the inside of the adsorbent tank is filled with the adsorbent.
• valve V1 is opened.
• carbon dioxide is supplied to the flow path P11, and the carbon dioxide and nitrogen are mixed in the flow path P13.
• a mixed gas containing carbon dioxide and nitrogen is supplied to the flow paths P14 and P17.
• the flow rates of carbon dioxide and nitrogen are adjusted so that the carbon dioxide concentration in the mixed gas becomes a predetermined value (preferably in the range of 390 ppm to 410 ppm). In the following, an example in which the carbon dioxide concentration is 400 ppm will be described.
• Valve V5b is opened to adjust the relative humidity inside the adsorbent tank 20 to 10% to 50%.
• the relative humidity is preferably 15% to 45%, and more preferably 15% to 30%.
• the temperature inside the adsorbent tank 20 is preferably 20° C. to 35° C.
• the pressure inside the adsorbent tank 20 is preferably normal pressure.
• the relative humidity can be adjusted by the amount of water supplied from the water supply device 30 to the vaporizer 80 .
• the detector 60 detects the carbon dioxide concentration in the carbon dioxide-containing mixed gas before the mixed gas is supplied to the adsorbent tank 20 .
• detector 60 confirms that the carbon dioxide concentration in the carbon dioxide-containing mixed gas is 400 ppm and a hygrometer (not shown) confirms that the relative humidity inside adsorbent tank 20 is a predetermined relative humidity, valves V3, V5b, and V6 are closed and valves V4 and V7 are opened.
• the mixed gas carbon dioxide concentration: 400 ppm
• Carbon dioxide is adsorbed into the adsorbent 21 filled in the adsorbent tank 20.
• the mixed gas with a reduced carbon dioxide concentration is discharged from the lower end (outlet) of the adsorbent tank 20 to the flow path P16.
• the detector 60 detects the carbon dioxide concentration in the gas discharged from the adsorbent tank 20.
• the detector 60 is electrically connected to a computer (control unit) (not shown) that transmits detected carbon dioxide concentration data and stores and processes the data.
• the detector 60 confirms that the carbon dioxide concentration is decreasing from 400 ppm.
• the detector 60 confirms that the carbon dioxide concentration, which had once decreased, rises again and finally reaches 400 ppm.
• the carbon dioxide concentration decreases from 400 ppm and then returns to 400 ppm it is determined that the adsorbent 21 has reached its carbon dioxide adsorption limit.
• the detector 60 collects data on the carbon dioxide concentration (concentration data), and the obtained concentration data is sent to a computer. Based on the sent concentration data, a determination unit (not shown) of the computer performs processing to determine whether the concentration data is less than a threshold concentration (400 ppm), for example, to determine whether the adsorbent 21 has reached its carbon dioxide adsorption limit.
• concentration data concentration data
• a determination unit not shown
• processing to determine whether the concentration data is less than a threshold concentration (400 ppm), for example, to determine whether the adsorbent 21 has reached its carbon dioxide adsorption limit.
• valve V1 is closed and valves V3 and V6 are opened. This causes flow paths P14, P15, P16, P17, the adsorbent tank 20, and the detector 60 to be purged with nitrogen. On the other hand, if the judgment unit determines that the adsorbent 21 has not reached its carbon dioxide adsorption limit, valve V1 is maintained in the open state until the concentration data returns to 400 ppm.
• All valves are now closed. All valves can be controlled by a control unit (not shown). The result of the determination by the determination unit is sent to the control unit, which then opens and closes the valves.
• valve V7 is closed and valve V6 is opened.
• the flow paths P14 and P17 are in a reduced pressure state (for example, greater than 0 kPa and equal to or less than 4.5 kPa).
• Valve V5a is opened to supply water (e.g., ultrapure water) from the water supply device 30 to the adsorbent tank 20.
• water e.g., ultrapure water
• the adsorbent 21 filled in the adsorbent tank 20 is immersed in water.
• the time for immersing the adsorbent 21 in water is, for example, 30 minutes to 3 hours.
• the water temperature when immersing the adsorbent 21 in water is preferably higher than 0° C. and equal to or lower than 35° C.
• the valve V5a is closed to stop the supply of water from the water supply device 30 to the adsorbent tank 20. Turn on the vacuum pump and open valves V7 and V8. As a result, the inside of the adsorbent tank 20, the flow path P16, and the flow path P17 are placed in a reduced pressure state (for example, 3 kPa).
• the pressure is preferably adjusted to more than 0 kPa and not more than 4.5 kPa, and more preferably adjusted to 3 kPa to 4.5 kPa.
• the carbon dioxide adsorbed in the adsorbent 21 is desorbed and sent to flow paths P16 and P17.
• the concentration of carbon dioxide in the detector 60 By measuring the concentration of carbon dioxide in the detector 60, the mass of desorbed carbon dioxide can be calculated.
• valve V8 is closed, and valve V9 is opened. This allows the desorbed carbon dioxide to be discharged to the outside.
• valves V2, V3, V4, and V6 are opened. This causes flow paths P14, P15, P16, and P17, the adsorbent tank 20, and the detector 60 to be purged with nitrogen.
• Valves V3 and V6 are closed, and valves V4 and V7 are opened. As a result, nitrogen is supplied to the flow paths P12, P13, P15, and P16. Nitrogen is supplied until it is determined that the absorbance of water is below 0.1.
• valves V3 and V6 are opened and the above-mentioned adsorption step and desorption step are carried out.
• the adsorption efficiency is maintained even if the adsorption and desorption steps are repeated.
• the adsorbent that has adsorbed carbon dioxide is immersed in water and then the pressure is reduced, allowing the carbon dioxide to be desorbed, making it possible to capture carbon dioxide with less energy than conventional methods.
• ⁇ Preparation of adsorbent> A polymerization reaction was carried out using vinylbenzyltrimethylammonium chloride and divinylbenzene as polymerizable monomers, 2,2'-azobis(2-methylpropionamidine) dihydrochloride as a polymerization initiator, and ethanol as a solvent. After the polymerization reaction was completed, the mixture was dried and pulverized in a pulverizer to obtain an adsorbent having a particle size of 100 ⁇ m or less.
• Ion exchange was performed with sodium hydroxide for 16 hours, and the sample was washed twice with ultrapure water. After washing, the sample was dried in a vacuum dryer at 30°C for 24 hours. The sample was dried at 30°C using nitrogen until the absorbance of water was 0.1 or less.
• a mixed gas having a carbon dioxide concentration of 400 ppm was supplied to the adsorbent tank.
• the relative humidity when the mixed gas was brought into contact with the adsorbent was adjusted to each of 0%, 10%, 20%, 50%, and 80%.
• the mixed gas was supplied until the carbon dioxide concentration discharged from the outlet of the adsorbent tank decreased from 400 ppm and returned to 400 ppm.
• Figure 2 shows the amount of carbon dioxide adsorbed when the relative humidity during contact of the mixed gas with the adsorbent was adjusted to 0%, 10%, 20%, 50%, and 80%.
• FIG. 3 shows the amount of carbon dioxide adsorbed when the adsorption step and desorption step were repeatedly performed. As shown in FIG. 3, it was found that the amount of adsorbed carbon dioxide was maintained even when the adsorption step and the desorption step were repeatedly performed.
• FIG. 4 shows the results of the amount of carbon dioxide adsorption when the internal pressure of the adsorbent tank in the desorption step was adjusted to 3 kPa, 4.5 kPa, 6.5 kPa, 10 kPa, and 50 kPa, respectively.
• the amount of adsorption was large when the pressure inside the adsorbent tank in the desorption step was set to more than 0 kPa and 4.5 kPa or less.

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Citations (11)

• 2024
  • 2024-01-22 JP JP2024573046A patent/JPWO2024157938A1/ja active Pending
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