A method for preparing a monolithic carbon dioxide solid adsorbent

Abstract

This invention relates to the field of carbon capture materials technology, specifically disclosing a method for preparing a monolithic solid carbon dioxide adsorbent. Addressing the problems of high pressure drop, difficult molding, and airflow entrainment loss in existing powdered amine adsorbents, this invention employs a template-phase separation composite process: Matrix preparation: 10-30 wt.% polyetherimide is dissolved in an organic solvent, a certain proportion of preheated salt particles are added, and after stirring and dispersion, the mixture is poured into a mold; Phase separation molding: The polymer is immersed in ethanol for 24 hours to induce solidification; Template removal: Salt particles are dissolved in water using ultrasonic assistance to form interconnected channels; Amine functionalization: The dried porous matrix is ​​impregnated with an amine solution to obtain a solid amine-loaded monolithic adsorbent. This invention solves the technical bottlenecks of traditional powdered adsorbents, such as difficult molding, loose structure, and high bed pressure drop, and is particularly suitable for industrial flue gas carbon capture and direct air capture.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide capture technology, specifically to a method for preparing an integral CO2 adsorbent based on a template-phase separation coupled physical impregnation method. The resulting adsorbent is suitable for flue gas and direct air capture systems in coal-fired power plants. Background Technology

[0002] Against the backdrop of accelerated global industrialization, the large-scale consumption of fossil fuels and the continuous enhancement of human production and living activities have led to a sharp increase in carbon dioxide (CO2) emissions, which in turn has driven up global temperatures. This intensifying greenhouse effect not only profoundly affects the stability of natural ecosystems but also poses serious challenges to socio-economic development. To effectively reduce atmospheric CO2 concentrations, carbon capture, utilization, and storage (CCUS) technology is considered one of the most promising emission reduction pathways.

[0003] Currently, CO2 capture methods mainly fall into three categories: pre-combustion capture, oxygen-enriched combustion, and post-combustion capture. Among these, post-combustion capture technology, due to its advantages such as low modification costs and relatively mature technology, demonstrates broad engineering application prospects because it allows for CO2 recovery by adding carbon capture devices without altering the existing main process flow. Currently widely used post-combustion carbon capture technologies include solvent absorption, cryogenic condensation, membrane separation, and adsorption. Adsorption methods, with their significant advantages of large adsorption capacity, low regeneration energy consumption, and non-corrosiveness to equipment, are gradually becoming a research hotspot. However, most solid amine adsorbents currently use molecular sieves, porous carbon, and metal-organic framework materials as carriers. These materials are mostly in granular or powder form, which exposes prominent problems in practical industrial applications, such as loose structure, poor mechanical strength, cumbersome preparation processes, easy loss of amine active components, and easy dust pollution, limiting their large-scale industrial application.

[0004] Therefore, it is necessary to provide a monolithic solid adsorbent to solve the above problems. Summary of the Invention

[0005] To address the problems of traditional powder adsorbents, such as difficulty in molding, low mechanical strength, amine loss, dust pollution, and poor adaptability to industrial filling, this invention innovatively proposes a method for preparing an integral solid amine carbon dioxide capture material based on template-phase separation synergistic molding.

[0006] The technical solution of the present invention is as follows: A method for preparing a monolithic carbon dioxide solid adsorbent based on physical impregnation of organic amines includes the following steps: (1) Pretreatment of polymer materials: The polymer granules are dried in a vacuum oven; (2) Preparation of matrix solution: Dissolve the polymer in an organic solvent to form a homogeneous solution with a mass concentration of 10-25%; (3) Template mixing: Add 100-500% of the polymer mass of pore-forming agent particles to the solution in step (2) and disperse to form a mixed slurry; (4) Phase separation molding: The mixed slurry is poured into a mold and immersed in a non-solvent to induce phase separation and solidification, forming a three-dimensional porous matrix; (5) Template removal: The pore-forming agent is removed by solvent dissolution or ultrasonic assistance to form a through-pore structure and obtain a porous matrix; (6) Amine functionalization: The porous matrix is ​​impregnated with an amine compound solution and dried to obtain a monolithic carbon capture adsorbent.

[0007] Further, in step (1), the polymer is at least one of polyetherimide (PEI), polysulfone (PSF), polyethersulfone (PES), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), and polyether ether ketone (PEEK); the drying temperature is 100~120℃, and the drying time is 4h~6h.

[0008] Further, in step (2), the organic solvent is at least one of halogenated hydrocarbons, amides, and ketones; in step (3), the pore-forming agent is a water-soluble inorganic salt or a sublimable solid; in step (4), the non-solvent is an alcohol or water; in step (6), the amine compound is a primary amine, secondary amine, tertiary amine, or a sterically hindered amine.

[0009] Further, in step (2), the organic solvent is at least one of dichloromethane, chloroform, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), and acetone; dissolution is achieved by magnetic stirring at 45-80°C for more than 3 hours.

[0010] Further, in step (3), the pore-forming agent is sodium chloride, potassium chloride, sucrose or ammonium carbonate, and the particle size range of the pore-forming agent is 125-500μm, preferably 10-200μm; the pore-forming agent needs to be preheated to 40-60℃ and stirred and dispersed for 30-90 minutes to form a mixed slurry before use.

[0011] Furthermore, in step (4), the non-solvent is ethanol, methanol, isopropanol or deionized water; the phase separation soaking time is 12-48 hours, and the non-solvent is replaced every 4-12 hours.

[0012] Furthermore, in step (5), the pore-forming agent is dissolved in water or acid solution, and the dissolution process is supplemented by ultrasonic vibration. The total treatment time is 2-8 hours, and the dissolving solution is replaced every 1-2 hours. When using acid solution for dissolution, the concentration of the acid solution is 0.1-1M.

[0013] Further, in step (6), the amine compound is one or more of polyethyleneimine (PEI), piperazine, monoethanolamine (MEA), diethanolamine (DEA), diethylenetriamine (DETA), triethylenetetramine (TETA), and tetraethylenepentamine (TEPA), and the loading of the amine compound is 30-70% of the matrix mass.

[0014] A monolithic solid carbon dioxide adsorbent based on physical impregnation of organic amines has a compressive strength ≥ 1 MPa. Under pure CO2 conditions at 40℃, it exhibits a dynamic adsorption capacity ≥ 100 mg / g, with a capacity decay rate < 15% after 5 adsorption-desorption cycles.

[0015] Compared with existing technologies, this invention achieves the following breakthrough advantages through technological innovation: Innovative material system: Engineering plastics with high glass transition temperature (Tg≥200℃) (such as polyetherimide and polyethersulfone) are selected as solid amine support matrix. Their excellent heat resistance and chemical stability overcome the structural collapse problem of traditional silicon-based carriers in high-temperature regeneration, while also broadening the range of raw material selection.

[0016] Innovative matrix structure: Employing a template-phase separation synergistic pore-forming technology, a bilevel pore structure is constructed within the polymer matrix: macroscopic interconnected channels (pore size 10-500 μm, oriented by salt templates, porosity ≥80%); and micro / nano-scale network pores (generated by phase separation). This structure enables the adsorbent to possess both low airflow resistance and high mechanical strength, effectively addressing the shortcomings of powdered adsorbents such as high flow resistance and easy backflow entrainment loss.

[0017] Advanced process integration: It innovatively integrates non-solvent-induced phase separation (NIPS) and soluble template method to achieve one-step molding of three-dimensional integral structure, reducing 2-3 steps compared with traditional extrusion-granulation process.

[0018] Industrial application value: This technology is compatible with mainstream carbon capture reactors such as fixed bed / rotating bed reactors, and shows significant advantages in coal-fired power plants (CO2 capture efficiency ≥90%), steel kilns (operating temperature ≤150℃) and direct air capture (DAC) systems.

[0019] This provides core technical support for the large-scale application of the present invention in the field of carbon capture and storage (CCUS). Attached Figure Description

[0020] Figure 1 This is a technical roadmap for the present invention; Figure 2 Adsorption capacity diagram of monolithic adsorbents loaded with different amines; Figure 3 Infrared spectra of monolithic adsorbents loaded with different amines and MOPP substrate before loading; Figure 4 The graph shows the cycle capacity and cycle efficiency of the monolithic adsorbent prepared in Example 5. Figure 5 This is a stress-strain curve of the material. Detailed Implementation

[0021] Example 1 1) Raw material pretreatment: Place the polyetherimide granules in a vacuum drying oven and dry them at 110℃ for 4 hours for later use.

[0022] 2) Solution preparation: Weigh 2g of dried polyetherimide granules, add 11.334g of chloroform solution, and stir magnetically at 45℃ for 3h to obtain a 15 wt.% polymer solution.

[0023] 3) Template addition: Weigh 8g of NaCl particles with a particle size of 125-200 μm, preheat to 45℃, mix with the polymer solution in 2), and stir magnetically for 60 minutes to make it evenly distributed.

[0024] 4) Curing: Pour the mixed solution from step 3) into the mold, and then place it in anhydrous ethanol solution for 24 hours (replace the ethanol solution every 8 hours) to cure the polymer material through non-solvent phase separation.

[0025] 5) Template removal and drying: The cured material is placed in deionized water and sonicated for 4 hours (the dissolving solution is changed every 2 hours) to completely dissolve and remove the salt particles. Then it is placed in an oven for drying to obtain a porous matrix.

[0026] 6) Amine loading and post-treatment: Weigh out monoethanolamine (MEA) of equal mass to the porous matrix, add 10 ml of anhydrous ethanol, stir for 30 min, add to the porous matrix, impregnate with vacuum assistance until no more bubbles are generated, remove excess liquid, dry in a vacuum oven at 55 °C overnight, and finally obtain adsorbent MM.

[0027] Example 2 1) Raw material pretreatment: Place the polyetherimide granules in a vacuum drying oven and dry them at 110℃ for 4 hours for later use.

[0028] 2) Solution preparation: Weigh 2g of dried polyetherimide granules, add 11.334g of chloroform solution, and stir magnetically at 45℃ for 3h to obtain a 15 wt.% polymer solution.

[0029] 3) Template addition: Weigh 8g of NaCl particles with a particle size of 125-200 μm, preheat to 45℃, mix with the polymer solution in 2), and stir magnetically for 60 minutes to make it evenly distributed.

[0030] 4) Curing: Pour the mixed solution from step 3) into the mold, and then place it in anhydrous ethanol solution for 24 hours (replace the ethanol solution every 8 hours) to cure the polymer material through non-solvent phase separation.

[0031] 5) Template removal and drying: The cured material is placed in deionized water and sonicated for 4 hours (the dissolving solution is changed every 2 hours) to completely dissolve and remove the salt particles. Then it is placed in an oven for drying to obtain a porous matrix.

[0032] 6) Amine loading and post-treatment: Weigh diethanolamine (DEA) of the same mass as the porous matrix, add 10 ml of anhydrous ethanol, stir for 30 min, add to the porous matrix, impregnate with vacuum assistance until no more bubbles are generated, remove excess liquid, dry in a vacuum oven at 55 °C overnight, and finally obtain adsorbent DM.

[0033] Example 3 1) Raw material pretreatment: Place the polyetherimide granules in a vacuum drying oven and dry them at 110℃ for 4 hours for later use.

[0034] 2) Solution preparation: Weigh 2g of dried polyetherimide granules, add 11.334g of chloroform solution, and stir magnetically at 45℃ for 3h to obtain a 15 wt.% polymer solution.

[0035] 3) Template addition: Weigh 8g of NaCl particles with a particle size of 125-200 μm, preheat to 45℃, mix with the polymer solution in 2), and stir magnetically for 60 minutes to make it evenly distributed.

[0036] 4) Curing: Pour the mixed solution from step 3) into the mold, and then place it in anhydrous ethanol solution for 24 hours (replace the ethanol solution every 8 hours) to cure the polymer material through non-solvent phase separation.

[0037] 5) Template removal and drying: The cured material is placed in deionized water and sonicated for 4 hours (the dissolving solution is changed every 2 hours) to completely dissolve and remove the salt particles. Then it is placed in an oven for drying to obtain a porous matrix.

[0038] 6) Amine loading and post-treatment: Weigh out the same mass of diethylenetriamine (DETA) as the porous matrix, add 10 ml of anhydrous ethanol, stir for 30 min, add to the porous matrix, impregnate with vacuum assistance until no more bubbles are generated, remove excess liquid, dry in a vacuum oven at 55 °C overnight, and finally obtain the adsorbent DT-M.

[0039] Example 4 1) Raw material pretreatment: Place the polyetherimide granules in a vacuum drying oven and dry them at 110℃ for 4 hours for later use.

[0040] 2) Solution preparation: Weigh 2g of dried polyetherimide granules, add 11.334g of chloroform solution, and stir magnetically at 45℃ for 3h to obtain a 15 wt.% polymer solution.

[0041] 3) Template addition: Weigh 8g of NaCl particles with a particle size of 125-200 μm, preheat to 45℃, mix with the polymer solution in 2), and stir magnetically for 60 minutes to make it evenly distributed.

[0042] 4) Curing: Pour the mixed solution from step 3) into the mold, and then place it in anhydrous ethanol solution for 24 hours (replace the ethanol solution every 8 hours) to cure the polymer material through non-solvent phase separation.

[0043] 5) Template removal and drying: The cured material is placed in deionized water and sonicated for 4 hours (the dissolving solution is changed every 2 hours) to completely dissolve and remove the salt particles. Then it is placed in an oven for drying to obtain a porous matrix.

[0044] 6) Amine loading and post-treatment: Weigh out tetraethylenepentamine (TEPA) of the same mass as the porous matrix, add 10 ml of anhydrous ethanol, stir for 30 min, add to the porous matrix, impregnate with vacuum assistance until no more bubbles are generated, remove excess liquid, dry in a vacuum oven at 55 °C overnight, and finally obtain adsorbent TM.

[0045] Example 5 1) Raw material pretreatment: Place the polyetherimide granules in a vacuum drying oven and dry them at 110℃ for 4 hours for later use.

[0046] 2) Solution preparation: Weigh 2g of dried polyetherimide granules, add 11.334g of chloroform solution, and stir magnetically at 45℃ for 3h to obtain a 15 wt.% polymer solution.

[0047] 3) Template addition: Weigh 8g of NaCl particles with a particle size of 125-200 μm, preheat to 45℃, mix with the polymer solution in 2), and stir magnetically for 60 minutes to make it evenly distributed.

[0048] 4) Curing: Pour the mixed solution from step 3) into the mold, and then place it in anhydrous ethanol solution for 24 hours (replace the ethanol solution every 8 hours) to cure the polymer material through non-solvent phase separation.

[0049] 5) Template removal and drying: The cured material is placed in deionized water and sonicated for 4 hours (the dissolving solution is changed every 2 hours) to completely dissolve and remove the salt particles. Then it is placed in an oven for drying to obtain a porous matrix.

[0050] 6) Amine loading and post-treatment: Weigh out polyethyleneimine (PEI, Ms=1800) of the same mass as the porous matrix, add 10 ml of anhydrous ethanol, stir for 30 min, add to the porous matrix, impregnate with vacuum assistance until no more bubbles are generated, remove excess liquid, dry in a vacuum oven at 55 °C overnight, and finally obtain the adsorbent PM.

[0051] The adsorbent was used to capture pure CO2 gas. First, the adsorbent was degassed in an adsorption container with high-purity N2. After its mass remained constant, the adsorption temperature was set to 40℃, and an adsorption experiment was conducted under pure CO2 gas. The CO2 capture capacity of the adsorbent was measured by the weight change. The results are as follows: Figure 2 As shown.

[0052] The monolithic adsorbent obtained in Example 5 was subjected to five adsorption-desorption cycles at an adsorption temperature of 40°C, pure CO2 gas, and a desorption temperature of 120°C. The cycle capacity and cycle efficiency of the adsorbent were obtained, and the results are shown in the figure. Figure 4 As shown. A single compression test was performed on the monolithic adsorbent obtained in Example 5 using a texture analyzer. The initial load was set to 5 N, and the maximum load to 1000 N. Data on the force and thickness changes were obtained, and the stress-strain curve of the material was calculated. The results are shown below. Figure 5 As shown, the material exhibits a significant yield peak at approximately 2% strain, and the calculated compressive strength at this point is 1.85 MPa.

[0053] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing an integral carbon dioxide solid adsorbent, characterized in that, Includes the following steps: (1) Pretreatment of polymer materials: The polymer granules are dried in a vacuum oven; (2) Preparation of matrix solution: Dissolve the polymer in an organic solvent to form a homogeneous solution with a mass concentration of 10-25%; (3) Template mixing: Add 100-500% of the polymer mass of pore-forming agent particles to the solution in step (2) and disperse to form a mixed slurry; (4) Phase separation molding: The mixed slurry is poured into a mold and immersed in a non-solvent to induce phase separation and solidification, forming a three-dimensional porous matrix; (5) Template removal: The pore-forming agent is removed by solvent dissolution or ultrasonic assistance to form a through-pore structure and obtain a porous matrix; (6) Amine functionalization: The porous matrix is ​​impregnated with an amine compound solution and dried to obtain a monolithic carbon capture adsorbent.

2. The preparation method according to claim 1, characterized in that: In step (1), the polymer is at least one of polyetherimide, polysulfone, polyethersulfone, polyacrylonitrile, polytetrafluoroethylene, and polyetheretherketone; the drying temperature is 100~120℃ and the drying time is 4h~6h.

3. The preparation method according to claim 1, characterized in that: In step (2), the organic solvent is at least one of halogenated hydrocarbons, amides, and ketones; in step (3), the pore-forming agent is a water-soluble inorganic salt or a sublimable solid; in step (4), the non-solvent is an alcohol or water; in step (6), the amine compound is a primary amine, secondary amine, tertiary amine, or a sterically hindered amine.

4. The preparation method according to claim 1, characterized in that: In step (2), the organic solvent is at least one of dichloromethane, chloroform, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and acetone; dissolution is achieved by magnetic stirring at 45-80°C for more than 3 hours.

5. The preparation method according to claim 1, characterized in that: In step (3), the pore-forming agent is sodium chloride, potassium chloride, sucrose or ammonium carbonate, and the particle size range of the pore-forming agent is 125-500μm, preferably 10-200μm. The pore-forming agent needs to be preheated to 40-60℃ and stirred and dispersed for 30-90 minutes to form a mixed slurry before use.

6. The preparation method according to claim 1, characterized in that: In step (4), the non-solvent is ethanol, methanol, isopropanol or deionized water; the phase separation soaking time is 12-48 hours, and the non-solvent is replaced every 4-12 hours.

7. The preparation method according to claim 1, characterized in that: In step (5), the pore-forming agent is dissolved in water or acid solution. The dissolution process is supplemented by ultrasonic vibration. The total treatment time is 2-8 hours. The dissolving solution is replaced every 1-2 hours. When using acid solution for dissolution, the concentration of the acid solution is 0.1-1M.

8. The preparation method according to claim 1, characterized in that: In step (6), the amine compound is one or more of polyethyleneimine, piperazine, monoethanolamine, diethanolamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine, and the loading of the amine compound is 30-70% of the matrix mass.

9. A monolithic solid carbon dioxide adsorbent based on physical impregnation of organic amines, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. The monolithic carbon dioxide solid adsorbent based on physical impregnation of organic amines according to claim 9, characterized in that, Compressive strength ≥ 1MPa; under pure CO2 and 40℃ conditions, dynamic adsorption capacity ≥ 100 mg / g, and capacity decay rate < 15% after 5 adsorption-desorption cycles.

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