Adsorbents suitable for ultra-low concentration carbon dioxide capture by thermal swing plate sulfurization phase separation molding and preparation and application thereof

Abstract

The application discloses a kind of adsorbent suitable for ultra-low concentration carbon dioxide capture of hot flat plate sulfuration phase separation forming and its preparation method and application.Preparation method includes: diluent preheating, inert carrier is added, dissolves to form homogeneous solution, then active adsorption component is added and uniformly mixed to form casting solution;The casting solution is placed on the sulfuration flat plate, hot-pressed, then removed and placed in cooling bath to cool and shape, the obtained membrane is soaked in extractant to remove diluent, finally the membrane is soaked in carbonate solution until ion exchange is completed, to obtain adsorbent.The adsorbent of the application can be used for direct carbon dioxide capture of air.

Description

Technical Field

[0001] This invention relates to the field of direct capture technology of carbon dioxide in the air, specifically to an adsorbent formed by hot plate sulfurization phase separation suitable for capturing ultra-low concentration carbon dioxide, its preparation method, and its application. Background Technology

[0002] With the intensification of global climate change, carbon dioxide (CO2) capture and utilization has become an important technological approach to addressing climate issues. Existing technologies for ultra-low concentration CO2 capture (such as direct capture of carbon dioxide from the air) face challenges such as insufficient selectivity, low adsorption capacity, and high energy consumption.

[0003] Chemical adsorption is one of the most widely used technologies today. For example, amine adsorbents are widely used because of their high selectivity for CO2, but they have problems such as strong corrosivity, high energy consumption, and difficulty in regeneration.

[0004] Physical adsorption methods, represented by molecular sieves and activated carbon, adsorb gases through their pore structures. However, their pore distribution is uneven and their adsorption kinetics are poor, especially when dealing with ultra-low concentrations of CO2 in the air, where they exhibit low adsorption efficiency.

[0005] In recent years, the development of composite adsorption materials has provided a possibility for solving the above problems. For example, metal-organic frameworks (MOFs) have attracted widespread attention in the field of gas adsorption due to their high specific surface area and tunable pore structure. Li et al. (Li J.R., Kuppler RJ, Zhou HC Selective gas adsorption and separation in metal-organic frameworks[J]. Chemical Society Reviews,2009,38(5):1477-1504.) achieved efficient gas selective separation by synthesizing MOFs with different structures.

[0006] However, MOF materials have significant shortcomings in terms of preparation cost, moisture resistance, and chemical stability, which limit their practical application. To overcome these technical bottlenecks, thermally induced phase separation (TIPS), as an emerging polymer material preparation technology, has been gradually developed in the preparation of porous adsorbent materials in recent years. Zhang Jun et al. (Zhang Jun, Wang Xiaolin, Luo Feng. Preparation of low-density polyethylene microporous membranes by thermally induced phase separation [J]. Polymer Materials Science and Engineering, 2004, 20(1): 174-178.) successfully prepared low-density polyethylene microporous membranes with high porosity and specific surface area using TIPS technology, proving that this method can generate a uniform pore structure through polymer dissolution, phase separation, and extraction processes, thereby significantly improving the diffusion performance and adsorption efficiency of adsorbent materials.

[0007] Despite the superior performance of TIPS technology, traditional TIPS processes often require high temperatures (>200°C). These high temperatures not only significantly increase energy consumption but can also degrade active adsorbent components (such as styrene-based strong-base anion exchange resins), thereby reducing the adsorption performance and chemical stability of the adsorbent. Furthermore, porous materials generally suffer from decreased adsorption performance in high-humidity environments; for example, amine adsorbents easily absorb water and become ineffective under high humidity conditions, further limiting their application in practical scenarios. Therefore, developing a low-temperature, high-efficiency preparation process to simultaneously produce adsorbents with high porosity, high adsorption capacity, and excellent moisture resistance has become an important technological requirement. Summary of the Invention

[0008] To address the aforementioned technical problems and shortcomings in this field, the present invention provides an adsorbent suitable for ultra-low concentration carbon dioxide capture using a hot-plate sulfidation phase separation molding process, its preparation method, and its application.

[0009] The specific technical solution is as follows:

[0010] [1] A method for preparing an adsorbent suitable for ultra-low concentration carbon dioxide capture using a hot-plate sulfidation phase separation molding process, comprising:

[0011] The diluent is preheated, added to the inert carrier, and dissolved to form a homogeneous solution. Then, the active adsorption component is added and mixed evenly to form a casting solution.

[0012] The casting solution is placed on a vulcanizing plate and hot-pressed. Then it is taken out and placed in a cooling bath to cool and set. The resulting membrane is immersed in an extractant to remove the diluent. Finally, the membrane is immersed in a carbonate solution (such as sodium carbonate) until ion exchange is completed to obtain the adsorbent.

[0013] In some embodiments, the diluent may include at least one of diphenyl ether, paraffin oil, toluene, and xylene, preferably diphenyl ether. Under preferred conditions, the adsorbent obtained has a higher carbon dioxide adsorption capacity and adsorption efficiency, good mechanical properties, and no volatility or toxicity issues.

[0014] In some embodiments, the temperature for preheating the diluent can be 90–150°C.

[0015] In some embodiments, the inert carrier may include at least one of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE), preferably low-density polyethylene. Under preferred conditions, the resulting adsorbent has a higher carbon dioxide adsorption capacity and adsorption efficiency.

[0016] In some embodiments, the melting point of the low-density polyethylene may be 105–115°C.

[0017] In some embodiments, the melting point of the linear low-density polyethylene may be 115–125°C.

[0018] In some embodiments, the melting point of the high-density polyethylene may be 130–137°C.

[0019] The active adsorption component of this invention can be derived from existing technologies. In some embodiments, the active adsorption component may include an active adsorption resin, which may include at least one of the following: D290 series, D201 series, D202 series, IRA-900 series macroporous resins, 201*7 series, HPR4800CL gel-type anion exchange resin.

[0020] In some embodiments, the active adsorbent component may be washed with a pretreatment solvent and then dried before use. Further, the pretreatment solvent may include at least one of deionized water, sodium carbonate solution, sodium hydroxide solution, hydrochloric acid solution, and ethanol.

[0021] In some embodiments, the active adsorbent component may be added in particulate form. Further, the particle size of the active adsorbent component may be 30–200 micrometers, preferably 50–80 micrometers.

[0022] In some embodiments, the mixing time for adding the active adsorbent component can be 4 to 8 hours.

[0023] In some embodiments, based on the mass of the diluent being 100%, the mass percentage of the inert carrier may be 10% to 15%, and the mass percentage of the active adsorbent component may be 20% to 25%, such as 22.5%.

[0024] In some embodiments, additive components may also be added to the casting solution.

[0025] In some embodiments, the additive component may account for 5% to 15% of the total mass of the diluent, based on 100% of the diluent mass.

[0026] In some embodiments, the additive components may include one or more of antioxidant components, hydrophobic additives, and antistatic additives.

[0027] In some embodiments, the antioxidant component may include at least one of tetra(methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate)methane and tris(2,4-di-tert-butylphenyl) phosphite.

[0028] In some embodiments, the hydrophobic functional additive may include at least one of polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVC). The weight-average molecular weight of the PVDF may be 180,000-534,000 g / mol. The number-average molecular weight of the PVC may be 50,000-120,000 g / mol.

[0029] In some embodiments, the antistatic additive may include at least one of N,N-bis(2-hydroxyethyl)-N-(3′-dodecyloxy-2′-hydroxypropyl)methylammonium sulfate and stearoyltrimethylammonium chloride.

[0030] In some embodiments, the temperature of the hot pressing can be 80 to 130°C, for example 105°C.

[0031] In some embodiments, the pressure of the hot pressing can be 4 to 20 MPa, such as 10 MPa.

[0032] In some embodiments, the hot pressing time may be 5 to 60 minutes.

[0033] In some embodiments, the temperature of the cooling bath can be 0 to 60°C, such as 0°C, 20°C, 40°C, 60°C, etc., preferably 10 to 30°C, more preferably 15 to 25°C, and even more preferably 20°C. Under these preferred conditions, the adsorbent has a higher carbon dioxide adsorption capacity and adsorption efficiency.

[0034] In some embodiments, the thickness of the diaphragm may be 0.2 to 2 mm.

[0035] In some embodiments, the extractant may include at least one of ethanol, methanol, and cyclohexane, preferably cyclohexane, and under preferred conditions, the resulting adsorbent has a higher carbon dioxide adsorption capacity and adsorption efficiency.

[0036] [2] The adsorbent prepared according to the preparation method described in [1].

[0037] In some embodiments, the BET specific surface area of ​​the adsorbent is greater than 9 m². 2 / g, porosity greater than 60%, total pore volume greater than 0.5cm³ 3 / g.

[0038] [3] Application of the adsorbent according to [2] in carbon dioxide capture. Furthermore, the adsorbent can be used for direct capture of carbon dioxide from the air.

[0039] Compared with the prior art, the beneficial effects of this invention are as follows:

[0040] This invention employs a combination of hot plate vulcanization and thermally induced phase separation techniques to prepare the adsorbent. Using styrene-based macroporous strong-base anion exchange resin as the active adsorbent component, a porous structure is formed through a dissolution-extraction phase separation process involving polymer materials. Optimized processing temperature and steps significantly improve the adsorbent's kinetic performance, adsorption capacity, and porosity. This adsorbent exhibits excellent adsorption capacity and good mechanical properties in capturing ultra-low concentrations of carbon dioxide from the air, and can be used for environmental remediation and industrial gas separation. Attached Figure Description

[0041] Figure 1 The image shows the infrared spectrum of the porous composite adsorbent sample from Example 1.

[0042] Figure 2 This is a scanning electron microscope (SEM) image of the porous composite adsorbent sample from Comparative Example 1.

[0043] Figure 3 This is a SEM image of the porous composite adsorbent sample from Example 1. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Operating methods not specifically specified in the following embodiments are generally performed under conventional conditions or as recommended by the manufacturer.

[0045] Adsorption Experiment: The experiment first involved an airtightness check. After closing some valves, a nitrogen purging device was used, and the carbon dioxide concentration was monitored using an infrared analyzer. When the concentration dropped to an extremely low value, a measured amount of carbon dioxide was injected, and the leakage rate was observed to assess the airtightness of the device. Next, the purging phase began. The desorbed material was placed in a constant-temperature sealed chamber. By adjusting the temperature and using the nitrogen purging system, the concentrations of carbon dioxide and water vapor inside the chamber were ensured to reach extremely low levels, confirming that the adsorbent material was in a blank state, free from external interference. Finally, the testing phase was conducted. Carbon dioxide was injected to bring the gas concentration in the test environment to the target value (air carbon dioxide concentration, i.e., 400 ppm). The change in carbon dioxide concentration in response to the adsorbent material was monitored, and the above process was repeated multiple times until the final ambient gas concentration approached 400 ppm, confirming that the adsorbent material was saturated.

[0046] Desorption Experiment: The experiment begins with an airtightness check, consistent with the steps described above, and will not be repeated here. Next, the purging phase begins. The fully saturated porous composite adsorbent material is placed in a transparent, sealed test chamber within a constant-temperature test chamber. Temperature is adjusted, and nitrogen is used for purging to ensure the carbon dioxide concentration in the test environment drops to an extremely low level. Finally, during the testing phase, humidified nitrogen is introduced into the test chamber, and changes in carbon dioxide and water vapor concentrations are monitored until the carbon dioxide concentration at the outlet drops to near-blank levels, confirming complete desorption of carbon dioxide from the adsorbent material. The experiment then concludes.

[0047] Comparative Example 1:

[0048] Traditional hot-pressing method: First, D290 resin particles are alkali-washed, acid-washed, and alcohol-washed respectively with sodium carbonate solution, dilute hydrochloric acid, and ethanol. They are then rinsed with deionized water and dried, followed by ultra-fine grinding and sieving to obtain D290 resin powder of 50–80 μm. Next, 15 g of LDPE particles are slowly added to a 135°C internal mixer. Once the particles have completely melted into a transparent gel, 22.5 g of resin powder is slowly added. After the system is thoroughly mixed, the internal mixer is turned off, and the mixed material is removed. The mixed material removed from the internal mixer is preheated to a surface temperature of 80°C and placed on a two-roll mill. The mill is started, and the mixed material is pressed into sheets approximately 3 mm thick. After cooling to room temperature, the mixed material is again rolled into sheets of 0.4–1 mm thickness using the two-roll mill. These sheets are then cut into 5 cm × 5 cm pieces for testing and repeatedly immersed and washed in sodium carbonate solution until carbonate ion exchange is complete, finally obtaining a shaped porous composite adsorbent sample.

[0049] Example 1:

[0050] First, D290 resin particles were washed with sodium carbonate solution, dilute hydrochloric acid, and ethanol respectively (alkali washing, acid washing, and alcohol washing), rinsed with deionized water, dried, and then ultra-finely pulverized and screened to obtain D290 resin powder with a particle size of 50–80 μm. Next, 15 g of LDPE particles were preheated and dissolved in 100 g of diphenyl ether, and 22.5 g of resin powder was added in batches while stirring at high speed to form a homogeneous casting solution. The casting solution was placed in a flat vulcanizing machine, sandwiched with a polytetrafluoroethylene film, and hot-pressed at 105 °C and 10 MPa for 5 minutes, then rapidly cooled and shaped in a 20 °C cooling bath. The resulting membrane was immersed in cyclohexane for 24 hours to extract the diluent, and then repeatedly immersed and washed in sodium carbonate solution until carbonate ion exchange was complete, finally obtaining a formed porous composite adsorbent sample, designated D290 / LDPE-1, with a maximum tensile stress of 1.0 MPa and a tensile strain (displacement) of 57%.

[0051] The molding material obtained in Example 1 was subjected to an air concentration CO2 adsorption test at 20°C and 5ppt water vapor partial pressure, and the results were compared with those obtained by the conventional hot pressing method in Comparative Example 1. The results are shown in Table 1, indicating that the material prepared by hot plate vulcanization according to the present invention has higher adsorption capacity and kinetic performance.

[0052] Table 1

[0053]

[0054] Figure 1 The infrared spectrum of the material prepared by hot plate vulcanization in Example 1 is shown. The scanning results show that at 2915 cm⁻¹... -1 and 718cm -1 The band exhibits distinct characteristic peaks, which are induced by the typical CH stretching vibrations in the benzene ring structure of polystyrene resin. (1378 cm⁻¹) -1 With 1460cm -1 The characteristic peaks at 1630 cm⁻¹ correspond to the NX stretching vibration and CN stretching vibration, respectively. Combined with the above, it can be seen that the quaternary ammonium resin, as the active component, has been well integrated with the engineering plastic carrier, and the peak at 1630 cm⁻¹... -1 The vibrational peak induced by C=O at the point indicates that HCO3 has been formed in the adsorbent material after ion exchange treatment. - The material has a structure that allows it to adsorb ultra-low concentrations of CO2 from the air.

[0055] Figure 2 , Figure 3 Table 2 compares the SEM characterization and BET results of the materials prepared in Comparative Example 1 and Example 1. The material prepared by hot plate vulcanization in Example 1 has a significantly more porous and dispersed pore structure, and the pore structure in the organic continuous phase left by the diluent, which acts as both a solvent and a pore-forming agent, during extraction is more uniform.

[0056] Table 2

[0057]

[0058] Example 2:

[0059] The only difference from Example 1 is that HDPE of the same mass is used instead of LDPE, while all other aspects are the same, resulting in a shaped porous composite adsorbent sample.

[0060] The porous composite adsorbent material obtained in this embodiment was subjected to an air concentration CO2 adsorption test at 20°C and 5ppt water vapor partial pressure. The saturated adsorption capacity of the adsorbent material was found to be 0.52 mmol / g, and the half-adsorption time was 32 min.

[0061] Example 3:

[0062] The only difference from Example 1 is that the same mass of LLDPE was used instead of LDPE, and all other aspects are the same, resulting in a shaped porous composite adsorbent sample.

[0063] The porous composite adsorbent material obtained in this embodiment was subjected to an air concentration CO2 adsorption test at 20°C and 5ppt water vapor partial pressure. The saturated adsorption capacity of the adsorbent material was found to be 0.81 mmol / g, and the half-adsorption time was 27 min.

[0064] Example 4:

[0065] The only difference from Example 1 is that the cooling bath temperature used is 0°C, and all other aspects are the same, resulting in a shaped porous composite adsorbent sample.

[0066] The porous composite adsorbent material obtained in this embodiment was subjected to an air concentration CO2 adsorption test at 20°C and 5ppt water vapor partial pressure. The saturated adsorption capacity of the adsorbent material was found to be 0.71 mmol / g, and the half-adsorption time was 29 min.

[0067] Example 5:

[0068] The only difference from Example 1 is that the cooling bath temperature used is 40°C, and all other conditions are the same, resulting in a shaped porous composite adsorbent sample.

[0069] The porous composite adsorbent material obtained in this embodiment was subjected to an air concentration CO2 adsorption test at 20°C and 5ppt water vapor partial pressure. The saturated adsorption capacity of the adsorbent material was found to be 0.84 mmol / g, and the half-adsorption time was 24 min.

[0070] Example 6:

[0071] The only difference from Example 1 is that the cooling bath temperature used is 60°C, and all other conditions are the same, resulting in a shaped porous composite adsorbent sample.

[0072] The porous composite adsorbent material obtained in this embodiment was subjected to an air concentration CO2 adsorption test at 20°C and 5ppt water vapor partial pressure. The saturated adsorption capacity of the adsorbent material was found to be 0.82 mmol / g, and the half-adsorption time was 23 min.

[0073] Example 7:

[0074] The only difference from Example 1 is that the same mass of ethanol is used instead of cyclohexane as the extractant; all other aspects are the same, resulting in a shaped porous composite adsorbent sample.

[0075] The porous composite adsorbent material obtained in this embodiment was subjected to an air concentration CO2 adsorption test at 20°C and 5ppt water vapor partial pressure. The saturated adsorption capacity of the adsorbent material was found to be 0.82 mmol / g, and the half-adsorption time was 22 min.

[0076] Example 8:

[0077] The only difference from Example 1 is that the same mass of methanol is used instead of cyclohexane as the extractant; all other aspects are the same, resulting in a shaped porous composite adsorbent sample.

[0078] The porous composite adsorbent material obtained in this embodiment was subjected to an air concentration CO2 adsorption test at 20°C and 5ppt water vapor partial pressure. The saturated adsorption capacity of the adsorbent material was found to be 0.91 mmol / g, and the half-adsorption time was 18 min.

[0079] Example 9:

[0080] The blank control group differed from Example 1 only in that deionized water was used instead of sodium carbonate solution for ion exchange treatment; all other aspects were the same, resulting in a well-formed porous composite adsorbent sample.

[0081] The porous composite adsorbent material obtained in this embodiment was subjected to an air concentration CO2 adsorption test at 20°C and 5ppt water vapor partial pressure, and the saturated adsorption capacity of the adsorbent material was found to be 0.02mmol / g.

[0082] Example 10:

[0083] The only difference from Example 1 is that the same mass of paraffin oil is used instead of diphenyl ether as a diluent; all other aspects are the same, resulting in a shaped porous composite adsorbent sample.

[0084] The porous composite adsorbent material obtained in this embodiment was subjected to an air concentration CO2 adsorption test at 20°C and 5ppt water vapor partial pressure. The saturated adsorption capacity of the adsorbent material was found to be 0.42 mmol / g, and the half-adsorption time was 41 min.

[0085] Furthermore, the molding material obtained in this embodiment is prone to falling apart and has poor mechanical structure.

[0086] Example 11:

[0087] The only difference from Example 1 is that xylene is used instead of diphenyl ether as a diluent, while all other aspects are the same, resulting in a shaped porous composite adsorbent sample.

[0088] The porous composite adsorbent material obtained in this embodiment was subjected to an air concentration CO2 adsorption test at 20°C and 5ppt water vapor partial pressure. The saturated adsorption capacity of the adsorbent material was found to be 0.87 mmol / g, and the half-adsorption time was 25 min.

[0089] Furthermore, the molding material obtained in this embodiment has the problems of high volatility and high toxicity.

[0090] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. An adsorbent formed by hot-plate sulfidation phase separation suitable for capturing ultra-low concentration carbon dioxide, characterized in that, The method for preparing the adsorbent includes: The diluent diphenyl ether is preheated, and then added to the inert carrier low-density polyethylene to dissolve and form a homogeneous solution. Subsequently, the active adsorption component is added and mixed evenly to form a casting solution. Based on the mass of the diluent (100%), the inert carrier accounts for 10% to 15% of the mass, and the active adsorption component accounts for 20% to 25% of the mass. The active adsorption component includes an active adsorption resin, which includes at least one of the following: D290 series, D201 series, D202 series, IRA-900 series macroporous resins, 201*7 series, and HPR4800CL gel-type anion exchange resin. The casting solution is placed on a vulcanizing plate and hot-pressed at a temperature of 80–130°C and a pressure of 4–20 MPa. Then, it is removed and placed in a 20°C cooling bath to cool and set. The resulting membrane is then immersed in the extractant cyclohexane to remove the diluent. Finally, the membrane is immersed in a carbonate solution until ion exchange is completed to obtain the adsorbent. The BET specific surface area of ​​the adsorbent is greater than 9 m². 2 / g, porosity greater than 60%, total pore volume greater than 0.5cm³ 3 / g.

2. The application according to claim 1, characterized in that, The preheating temperature of the diluent is 90–150°C; The melting point of the low-density polyethylene is 105-115℃.

3. The application according to claim 1, characterized in that, The active adsorbent component is washed with a pretreatment solvent and then dried before use; the pretreatment solvent includes at least one of deionized water, sodium carbonate solution, sodium hydroxide solution, hydrochloric acid solution, and ethanol. The active adsorption component is added in particulate form; the particle size of the active adsorption component is 30-200 micrometers. The active adsorbent component is added and mixed for 4 to 8 hours.

4. The application according to claim 3, characterized in that, The particle size of the active adsorbent component is 50–80 micrometers.

5. The application according to claim 1, characterized in that, Additive components are also added to the casting solution; Based on a diluent mass of 100%, the additive component mass percentage is 5% to 15%. The additive components include one or more of antioxidant components, hydrophobic additives, and antistatic additives; The antioxidant component includes at least one of tetrakis(methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate)methane and tris(2,4-di-tert-butylphenyl) phosphite; The hydrophobic functional additive includes at least one of polyvinylidene fluoride and polyvinyl fluoride; the weight-average molecular weight of the polyvinylidene fluoride is 180,000-534,000 g / mol; and the number-average molecular weight of the polyvinyl fluoride is 50,000-120,000 g / mol. The antistatic additive includes at least one of N,N-bis(2-hydroxyethyl)-N-(3′-dodecyloxy-2′-hydroxypropyl)methylammonium sulfate and stearoyltrimethylammonium chloride.

6. The application according to claim 1, characterized in that, The hot pressing time is 5 to 60 minutes; The thickness of the diaphragm is 0.2 to 2 mm.

7. The application according to claim 1, characterized in that, The adsorbent is used for the direct capture of carbon dioxide from the air.

Images