Solid amine adsorbent and its preparation method and application

Abstract

To provide a solid amine adsorbent and its preparation method and application.SOLUTION: The solid amine adsorbent consists of modified organic amines and a porous nano support, with the proportion of secondary amines in the modified organic amines being 70% or higher. The preparation method of the modified organic amines includes the following steps: S1: mixing the organic amine and the organic amine modifying agent into an acetonitrile solvent and stirring to achieve uniform mixing; S2: adding a crosslinking agent to the solution and stirring; S3: gradually adding acetic acid to the solution during stirring to adjust the pH to neutral, then continuing to stir; S4: using a rotary evaporator to evaporate the solvent at 90 to 110°C until completely removed, resulting in the modified organic amine.EFFECT: The modified solid amine adsorbent produced by the present disclosure maintains high stability during cyclic adsorption and desorption processes while also ensuring excellent capacity.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to the technical field of solid amine adsorbents, and in particular to a solid amine adsorbent and its preparation method and application. [Background technology]

[0002] Currently, the increase in global CO2 emissions is further exacerbating the risks of climate change and threats to the ecological environment, and carbon capture, utilization, and storage (CCUS) has attracted widespread attention among scientists as an important means of combating global climate change. Among these, carbon capture is a pioneering and important technology that can effectively curb CO2 emissions by capturing large amounts of CO2 generated from industries, power generation, etc., and efficiently separating and capturing them.

[0003] Solid amine CO2 adsorption technology features high adsorption efficiency, low energy consumption, low cost, and simple process, making it a promising carbon capture technology with wide applications. Organic amines are the components of solid amine adsorbents that react directly with CO2, and their properties crucially determine the adsorbent's performance. In actual CO2 capture processes, the primary and secondary amine groups of organic amine molecules react with CO2 in a 2:1 molar ratio to form reversible aminocarboxylic acid or carbamate products. These products undergo temperature-programmed desorption, which separates the adsorbed CO2 and regenerates the primary and secondary amine groups. To achieve CO2 enrichment and efficient utilization of the organic amines, the adsorbent requires a high-temperature desorption reaction using pure CO2 as a purge gas. However, at high temperatures, poor thermal stability of organic amines can lead to volatilization from the adsorbent carrier surface, resulting in physical amine deactivation. Furthermore, when pure CO2 is used as a purge gas, CO2 adsorbed on the adsorbent is prevented from desorbing due to the concentration gradient. Instead, it reacts further to form irreversible compounds, resulting in the deactivation of the amine groups on the organic amines and chemical deactivation of the adsorbent. To address the two serious problems facing organic amines—physical and chemical deactivation—many scholars have conducted extensive research to address the issue of amine deactivation in adsorbents. However, most of these efforts have resulted in a decline in the adsorption performance of the adsorbent, with a single adsorption capacity decreasing by up to 50% or more. Most current research has focused on improving adsorption stability at the expense of adsorption performance. However, most current research has sacrificed adsorption performance in order to improve stability, which poses a major limitation to practical industrial applications. Therefore, the preparation of solid amine adsorbents with excellent thermal and chemical stability, high adsorption performance, and a secondary amine content of 70% or more is a technological bottleneck that needs to be overcome to promote the industrial application of solid amine adsorbents. Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention provides a solid amine adsorbent and its preparation method and application in response to the shortcomings of the prior art. [Means for solving the problem]

[0005] The present invention provides a solid amine adsorbent comprising a modified organic amine and a porous nanocarrier, wherein the loading amount of the modified organic amine in the adsorbent is 10 wt.%-80 wt.%, and the proportion of secondary amines in the modified organic amine is 70% or more. A method for preparing the modified organic amine includes the following steps: S1: Mix the organic amine and organic amine modifier, add to 5 to 15 times the volume fraction of acetonitrile solvent, and stir at 25 to 60°C at 300 to 600 rpm for 3 to 5 minutes to mix uniformly. S2: Add the cross-linker to the solution and stir at 300-1500 rpm for 5-20 hours at room temperature. S3: While stirring at 300-600 rpm, add acetic acid dropwise to the solution to adjust the pH and maintain it in the neutral range of pH 6.5-7.5, and continue stirring for 15-60 minutes. S4: The above solution is rotary evaporated at 90-110°C using a rotary evaporator until the solvent is completely evaporated, and the resulting substrate is used as a modified organic amine.

[0006] Here, the organic amine modifier is selected from any one of acetaldehyde, propionaldehyde, cyclopentanone, cyclohexanone, acetone, 3-pentanone, and cyclohexanone. The crosslinking agent may be sodium triacetoxyborohydride ((CH3COO)3BHNa), sodium cyanoborohydride (NaBH3CN), or borane-2-methylpyridine complex (CH6H 10 BN). The molar ratio of the organic amine to the organic amine modifier is 1:(1 to 4). The loading of the modified organic amine in the adsorbent is 10 wt.%-80 wt.%.

[0007] The modification of organic amines in adsorbents involves the reduction of the primary amine groups of the organic amine with an aldehyde or ketone, followed by the conversion of the primary amine to a secondary amine using a mild crosslinker. This method, unlike the more reactive epoxy compounds, uses an aldehyde or ketone as a modifier and a mild crosslinker to achieve grafting of the organic amine. However, this method only converts the highly reactive primary amine to a secondary amine; the original secondary amine group has low activity and the presence of spatial site resistance effects in the carbon chain further limits the progress of the grafting reaction. Finally, the dropwise addition of acetic acid during the reaction process controls the reaction pH to a neutral range of 6.5–7.5, ensuring the conversion of the primary amine to a secondary amine while limiting the conversion of the secondary amine to a tertiary amine.

[0008] The modification reaction pathway, shown in Figure 1, targets linear organic amine molecules, including primary, secondary, and tertiary amines. Reaction (1) is the main reaction, while reaction (2) is largely absent. This modification method achieves a primary amine conversion rate of over 80% and a secondary amine conversion rate of less than 10%. The organic amine modification process has the following advantages: first, it increases the molecular weight and improves thermal stability, thereby expanding the application environment and field; second, because primary amines are converted to secondary amines during the modification process, the proportion of highly stable secondary amines in the organic amine molecules is significantly increased, allowing the CO2 desorption reaction to proceed in the direction of desorption rather than the formation of irreversible compounds; and finally, because secondary amines are hardly converted to tertiary amines during the modification process, the degradation of the organic amine adsorption performance is minimal. Finally, the amine efficiency remains essentially high, which is of great significance for promoting the industrial application of solid amine adsorbents for CO2 capture.

[0009] Furthermore, the organic amine is selected from any one of diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), and polyethyleneimine (PEI), and the polyethyleneimine is a branched or linear polymer having a weight-average molecular weight of 300 to 2500, preferably 600 to 1200, in order to ensure that the viscosity and amine density of the modified polyethyleneimine fall within a usable range. Furthermore, the molar ratio of the organic amine to the crosslinking agent is 1:(1 to 4).

[0010] The present invention also provides a method for preparing a solid amine adsorbent, comprising the steps of: S1: The evaporated modified organic amine is dissolved in a base solution with a concentration of 0.5 to 3.0 mol / L, and extracted with an extractant 2 to 10 times until extraction is complete. S2: After mixing all the extraction phases, add porous nanocarriers and rotatory evaporate using a rotary evaporator at 40-140 °C until the solvent is completely evaporated to obtain product 1. S3: Dry the product 1 in a vacuum drying oven at a temperature of 40 to 140°C for 4 to 12 hours to obtain a solid amine adsorbent.

[0011] Furthermore, the alkaline solution is any one of sodium hydroxide, potassium hydroxide, barium hydroxide, and ammonia. Furthermore, the volume of the base solution is 1 to 3 times the volume fraction of acetonitrile. Further, the extractant is any one of ethyl acetate, ethyl ether, diisopropyl ether, or isoamyl alcohol. Furthermore, the extractant is used at one time in an amount of 0.5 to 3 times the volume fraction of acetonitrile. Furthermore, the porous nanocarrier is any one of silica, alumina, zeolite molecular sieves, resins, or MOFs. The present invention also provides the application of said solid amine adsorbent in the field of CO2 adsorption. [Effects of the Invention]

[0012] In summary, the present invention achieves the following technical advantages over the prior art: (1) The solid amine adsorbent prepared by the present invention can achieve high stability of organic amines in the desorption process while considering the stability of the adsorption capacity. (2) In all of the preparation methods of the present invention, the conversion rate of primary amine is 80% or more, and the conversion rate of secondary amine is 10% or less. (3) The solid amine adsorbent prepared by the present invention has a secondary amine content of 70% or more among the modified organic amines, and is highly stable. (4) The adsorption capacity of the solid amine adsorbent prepared according to the present invention remains stable after 10 cycles. [Brief explanation of the drawings]

[0013] In order to more clearly explain the technical solutions of the embodiments of the present invention, the following briefly introduces the accompanying drawings used in the embodiments. However, the following accompanying drawings only illustrate specific embodiments of the present invention, and therefore should not be considered as limiting the scope. It should be understood that a person of ordinary skill in the art can obtain other related accompanying drawings based on these drawings without any creative efforts.

[0014] [Figure 1] FIG. 1 is a schematic diagram of the organic amine modification process of the present invention. [Figure 2] FIG. 1 is a schematic diagram of the molecular structures of the major isomers of unmodified TEPA of Comparative Form 1 and modified TEPA of Embodiment 1 of the present invention. [Figure 3] 1 is a schematic diagram of the molecular structures of comparative form 2 of the unmodified PEHA of the present invention and the major isomers of the modified PEHA of embodiment 2. FIG. [Figure 4] FIG. 1 is a schematic diagram of the molecular structures for unmodified B-PEI-1200 and modified B-PEI-1200 of Comparative Form 3 of the present invention. [Figure 5]1 shows the distribution of primary, secondary, and tertiary amine ratios of organic amines in Embodiments 1-3 and Comparative Examples 1-3. DETAILED DESCRIPTION OF THE INVENTION

[0015] In order to enable those skilled in the art to better understand the embodiments of the present invention, the following clearly and completely describes the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention, but it is obvious that the described embodiments are only a part of the embodiments of the present invention, and are not all of the embodiments. Based on the embodiments in the present invention, all other embodiments that can be obtained by those skilled in the art without any creative efforts shall fall within the protection scope of the present invention.

[0016] 1. Embodiments and Proportional Forms of Raw Material Sources Propanetriol: CAS: 6-81-5, Shanghai ▲ ro ▼ test; B-PEI-300: CAS: 9002-98-6, Thermo Fisher Scientific Chemicals; B-PEI-1200: CAS: 9002-98-6, Thermo Fisher Scientific Chemicals; B-PEI-600: CAS: 9002-98-6, Thermo Fisher Scientific Chemicals; B-PEI-1800: CAS: 9002-98-6, Thermo Fisher Scientific Chemicals; TEPA: CAS: 112-57-2, Shanghai Aladdin; PEHA: CAS: 4067-16-7, Shanghai Aladdin; NaBH3CN: CAS: 25895-60-7, Shanghai Aladdin; (CH3COO)3BHNa: CAS: 56553-60-7,Vokai; Borane-2-methylpyridine complex (CH 10 BN): CAS: 3999-38-0;Alfa Sodium hydroxide: CAS: 1310-73-2, Shanghai Aladdin; Acetonitrile: CAS: 75-05-8, Shanghai Aladdin; Diethyl ether: CAS: 2679-89-2, Shanghai Aladdin; Ethyl acetate: CAS: 141-78-6, Shanghai Aladdin; Acetone: CAS: 127-06-0, Shanghai Aladdin; Cyclopentanone: CAS: 120-92-3, Shanghai Aladdin; Cyclohexanone: CAS: 108-94-1, Shanghai Aladdin; Propylene oxide: CAS: 75-56-9,Vokai; Methanol: CAS: 67-56-1, Shanghai ▲ ▲ ▼ .

[0017] II. Performance test method (1) Cyclic adsorption method using solid amine CO2 adsorbent An adsorption test was performed using a thermogravimetric analyzer with 15 mg of the prepared adsorbent under the following conditions: adsorption temperature and atmosphere: 60°C, CO2 concentration: 15%, adsorption time: 60 minutes, desorption temperature and atmosphere: 150°C, CO2 concentration: 100%, desorption time: 30 minutes. The above adsorption and desorption conditions were repeated 10 times. (2) Test method for the ratio of primary, secondary, and tertiary amines in modified organic amines The ratio of primary, secondary, and tertiary amines in the organic amine molecules in this method is examined using a liquid 13C nuclear magnetic resonance (NMR; Bruker, Ascend TM500 MHz, Germany) spectrometer. 13C spectra are quantitatively analyzed using the inverse gate decoupling pulse method, and the distribution of primary, secondary, and tertiary amines is calculated using the quantitative area integral method, which examines the areas of characteristic carbon atoms corresponding to primary, secondary, and tertiary amines. (3) Conversion rate test for organic amine modification Conversion rate of primary amines to secondary amines = (proportion of primary amines before modification - proportion of primary amines after modification) / proportion of primary amines before modification Conversion rate of secondary amine to tertiary amine = (proportion of tertiary amine after modification - proportion of tertiary amine before modification) / proportion of secondary amine before modification (4) CO2 adsorption test The CO2 adsorption characteristics of the adsorbent in this study were tested using a Setsys EVO Easy 1750 thermogravimetric analyzer (TGA; SETARAM, France). The test was performed by weighing 15–25 mg of adsorbent and stabilizing it at 150°C in a 100% Ar atmosphere for 30 minutes. The mass after degassing was taken as the initial mass M1. The temperature and atmosphere were then switched to 60°C in a 15% CO2 atmosphere. The mass after adsorption for 60 minutes was taken as the saturated mass M2. The adsorption capacity Q (unit: mmol / g adsorbent) was calculated as follows:

[0018]

number

[0019] (Embodiment 1) The solid amine adsorbent obtained by the preparation of this embodiment includes an organic amine modification step and an adsorbent preparation step.

[0020] <Modification of organic amines> S1: Add 11.4 g of TEPA and 9.80 g of cyclohexanone (molar ratio 1.2:2) to 200 mL of acetonitrile solvent and stir at 400 rpm at 25°C for 3 minutes to obtain a homogeneous mixture. S2: 6.30 g of NaBH3CN (2:1 molar ratio to TEPA) is added to this solution and stirred at 1000 rpm at room temperature for 10 hours. S3: While stirring at 300 rpm, add acetic acid dropwise to adjust the pH of the solution to 7.0, and continue stirring for 30 minutes. S4: The above solution is rotary evaporated using a vacuum rotary evaporator at 100°C until the solvent is completely evaporated to obtain the modified organic amine.

[0021] <Preparation of adsorbent> S5: The evaporated modified organic amine is dissolved in 200 mL of 1.0 mol / L aqueous sodium hydroxide solution and extracted four times with 100 mL of ether each time. S6: All the extraction phases are mixed, 9.45 g of silica carrier is added, and rotary evaporated using a vacuum rotary evaporator at 40° C. until the solvent is completely evaporated to obtain product 1. S7: Product 1 is dried in a vacuum oven at 40°C for 6 hours to prepare a solid amine CO2 adsorbent with an organic amine loading of 50 wt%.

[0022] (Embodiment 2) The solid amine adsorbent obtained by the preparation of this embodiment includes an organic amine modification step and an adsorbent preparation step.

[0023] <Modification of organic amines> S1: 11.6 g of PEHA and 14.7 g of cyclopentanone (molar ratio 1:3.5) were added to 300 mL of acetonitrile solvent and stirred at 500 rpm at 35°C for 3 minutes to obtain a homogeneous mixture. S2: To this solution, 9.45 g of NaBH3CN (3:1 molar ratio to PEHA) is added and stirred at 1000 rpm at room temperature for 15 hours. S3: While stirring at 500 rpm, add acetic acid dropwise to adjust the pH of the solution to 7.0 to maintain neutrality, and continue stirring for 30 minutes. S4: The above solution is rotary evaporated using a vacuum rotary evaporator at 100°C until the solvent is completely evaporated to obtain the modified organic amine.

[0024] <Preparation of adsorbent> S5: The evaporated substrate is dissolved in 300 mL of 1.5 mol / L aqueous sodium hydroxide solution and extracted three times with 200 mL of ethyl acetate. S6: All the extraction phases are mixed, an alumina carrier is added, and the mixture is rotary evaporated in a vacuum rotary evaporator at 85°C until the solvent is completely evaporated to obtain product 1. S7: Product 1 is dried in a vacuum oven at 85°C for 4 hours to prepare a solid amine CO2 adsorbent with an organic amine loading of 50 wt%.

[0025] In this embodiment, the modified organic amine was prepared with a primary amine, secondary amine, and tertiary amine ratio of 4:80:16. As can be seen from Figure 5, a comparison with the unmodified organic amine shows that the conversion rate of primary amine to secondary amine after modification was 89.7%, while the conversion rate of secondary amine to tertiary amine was only 4.3%. The prepared CO2 adsorbent had a CO2 adsorption capacity of 3.72 mmol / g for the first run and 3.55 mmol / g for the tenth run, resulting in a residual adsorption rate of 95.4%. As a result, the modified organic amine and the prepared CO2 adsorbent exhibited excellent stability while taking into account adsorption performance.

[0026] (Embodiment 3) The solid amine adsorbent obtained by the preparation of this embodiment includes an organic amine modification step and an adsorbent preparation step.

[0027] <Modification of organic amines> S1: 4.3 g of branched polyethyleneimine (B-PEI-1200) with a weight-average molecular weight of 1200 and 8.7 g of acetone (molar ratio 1:1.5) are added to 100 mL of acetonitrile solvent, and the mixture is stirred at 500 rpm at 50°C for 5 minutes to form a homogeneous mixture. S2: To this solution, 9.45 g of NaBH3CN (1.5:1 molar ratio to polyethyleneimine) is added and stirred at 1000 rpm for 20 hours at room temperature. S3: While stirring at 500 rpm, add acetic acid dropwise to adjust the pH of the solution to 7.0, and continue stirring for 30 minutes. S4: The above solution is rotary evaporated using a vacuum rotary evaporator at 100°C until the solvent is completely evaporated to obtain the modified organic amine.

[0028] <Preparation of adsorbent> S5: The evaporated substrate is dissolved in 200 mL of 2.0 mol / L aqueous sodium hydroxide solution and extracted five times with 50 mL of ether each time. S6: All the extraction phases are mixed and a resin carrier is added in a vacuum evaporator at 45°C until the solvent is completely evaporated, and the modified organic amine product is obtained. S7: The synthesized product prepared above is dried in a vacuum oven at 45°C for 6 hours to prepare a solid amine CO2 adsorbent with a loading rate of 50 wt.% relative to the organic amine.

[0029] (Embodiment 4) The organic amine modifier and adsorbent are prepared in the same manner as in Example 1, except that the masses of TEPA, cyclohexanone, and NaBH3CN used are 9.45 g, 14.7 g, and 9.45 g (molar ratio 1:3:3).

[0030] (Embodiment 5) The organic amine modifier and adsorbent are prepared in the same manner as in Example 2, except that the masses of PEHA, cyclopentanone, and NaBH3CN used are 11.6 g, 16.8 g, and 12.6 g (molar ratio 1:4:4).

[0031] (Embodiment 6) The organic amine modifier and adsorbent are prepared in the same manner as in Example 3, except that the amounts of branched polyethyleneimine (B-PEI-1200) with a weight-average molecular weight of 1200, acetone, and NaBH3CN used are 4.3 g, 5.8 g, and 6.3 g (molar ratio 1:1:1).

[0032] (Embodiment 7) The organic amine modification and adsorbent were prepared in the same manner as in Example 3, except that the porous nanocarrier used was silica.

[0033] (Embodiment 8) The organic amine modification and adsorbent were prepared in the same manner as in Example 3, except that the porous nanocarrier used was alumina.

[0034] (Embodiment 9) The organic amine modification and adsorbent were prepared in the same manner as in Example 3, except that the porous nanocarrier used was a zeolite molecular sieve.

[0035] (Embodiment 10) The organic amine modification and the adsorbent were prepared in the same manner as in Example 6, except that the organic amine used was branched polyethyleneimine with a weight-average molecular weight of 1800 (B-PEI-1800).

[0036] (Embodiment 11) The organic amine modification and the adsorbent were prepared in the same manner as in Example 6, except that the organic amine used was branched polyethyleneimine with a weight-average molecular weight of 600 (B-PEI-600).

[0037] (Embodiment 12) The organic amine modification and the adsorbent were prepared in the same manner as in Example 6, except that the organic amine used was branched polyethyleneimine with a weight-average molecular weight of 300 (B-PEI-300).

[0038] (Embodiment 13) The organic amine modification and adsorbent were prepared in the same manner as in Example 3, except that the cross-linking agent used was (CH3COO)3BHNa.

[0039] (Comparative form 1) In Comparative Example 1, compared with Example 1, the organic amine modification is not carried out, and the adsorbent is directly prepared. S1: 9.45 g of TEPA is mixed with 400 mL of ether, followed by adding 9.45 g of silica support, and rotary evaporating using a vacuum rotary evaporator at 45° C. until the solvent is completely evaporated to obtain product 1. S2: Product 1 is dried in a vacuum oven at 45°C for 6 hours to prepare a solid amine CO2 adsorbent with an organic amine loading of 50 wt%.

[0040] (Comparative form 2) Comparing Comparative Example 2 with Embodiment 2, the adsorbent is directly prepared without modification of the organic amine. S1: 11.6 g of PEHA is mixed with 600 mL of ethyl acetate, and then 11.6 g of alumina support is added, and the mixture is rotary evaporated using a vacuum rotary evaporator at 85° C. until the solvent is completely evaporated to obtain product 1. S2: Product 1 is dried in a vacuum oven at 85°C for 4 hours to prepare a solid amine CO2 adsorbent with an organic amine loading of 50 wt%.

[0041] (Comparative form 3) Comparing Comparative Example 3 with Embodiment 3, the adsorbent is directly prepared without modification of the organic amine. Mix 4.3 g of S1:B-PEI-1200 with 250 mL of ether, then add 4.3 g of resin support, and rotatory evaporate using a vacuum rotary evaporator at 45 °C until the solvent is completely evaporated to obtain product 1. S2: Product 1 is dried in a vacuum oven at 45°C for 6 hours to prepare a solid amine CO2 adsorbent with an organic amine loading of 50 wt%.

[0042] (Comparative form 4) Comparing embodiment 4 with embodiment 3, the organic amine modifier was prepared in the same manner as the adsorbent, except that a mass of 8.6 g of B-PEI-1200 was used, along with 2.32 g of acetone and 2.52 g of NaBHCN (molar ratio 1:0.2:0.2).

[0043] (Comparative form 5) Comparing the fifth embodiment with the third embodiment, the method for preparing the adsorbent is the same, but the difference is that the reaction pH is controlled to 4 in step S3 of the organic amine modification.

[0044] (Comparative form 6) The preparation method of Comparative Example 6 is the same as that of Example 1, except that the organic amine modification method used is a propylene oxide ring-opening grafting method. Propylene oxide and TEPA are mixed in a 2:1 molar ratio, and added to 10 times the volume of methanol. The mixture is stirred at room temperature for 12 hours to obtain a methanol solution of the organic amine to be modified. A silica carrier is then added, and the mixture is rotary evaporated in a vacuum rotary evaporator at 70°C until the solvent is completely evaporated. The remaining substrate is placed in a vacuum drying oven at 70°C for 4 hours to prepare a solid amine CO2 adsorbent carrying 50 wt.% of the organic amine.

[0045] [Table 1]

[0046] In embodiments 1 to 13, the organic amine is modified, and the conversion rate of primary amines to secondary amines in the organic amine is 85% or more, and the conversion rate of secondary amines to tertiary amines is 7.3% or less. The proportion of secondary amines in the resulting modified organic amine is 70% or more. The solid amine adsorbents obtained using the modified organic amines are highly stable, with the remaining adsorption capacity remaining at 93% or more after 10 cycles. The high adsorption capacity of the adsorbent indicates that the modified solid amine adsorbents obtained by the formulation and preparation methods of the present application can improve thermal stability and chemical stability while taking adsorption performance into consideration. This shows that they have obvious advantages over comparable forms and can effectively meet customer and market needs to a high level.

[0047] None of the comparative forms 1 to 3 were modified. The solid amine adsorbents prepared from unmodified organic amines had a high proportion of primary amines, resulting in a high amine deactivation rate during the cycling process. The residual adsorption amount after 10 cycles was only in the range of 14.2% to 32.6%, indicating that the stability of the CO2 adsorbents prepared using unmodified organic amines in the cycling adsorption process was poor. In the organic amine modification of comparative form 4, the amount of added modifier was too small and the amount of added crosslinker was insufficient, resulting in incomplete conversion of primary amines to secondary amines. This resulted in poor stability of the prepared organic amines during repeated adsorption and desorption in the adsorbents. In comparative form 5, the organic amine was not stable in an acidic environment. The modified organic amine of Comparative Form 6 was modified by propylene oxide ring-opening graft polymerization, and the initial adsorption capacity of the CO2 adsorbent prepared with the modified amine was reduced by 25.1% compared with the unmodified Comparative Form 1, resulting in a significant decrease in amine utilization efficiency. However, the initial adsorption capacity of the CO2 adsorbent prepared with the modified amine of Embodiment 1 of the present application was almost unchanged compared with the unmodified Comparative Form 1, indicating that the adsorbents prepared using the modified organic amine of the present application can take into account both stability and adsorption performance.

[0048] The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. CO ２ The application of a solid amine adsorbent in the field of adsorption is characterized in that the solid amine adsorbent is composed of a modified organic amine and a porous nanocarrier, the proportion of secondary amine in the modified organic amine is 70% or more, and the loading amount of the modified organic amine in the adsorbent is 10 wt% to 80 wt%, and the preparation method of the modified organic amine comprises the following process: S1: Mix an organic amine and an organic amine modifier, add to a 5 to 15-fold amount of acetonitrile solvent, and stir at 25 to 60°C at 300 to 600 rpm for 3 to 5 minutes to obtain a uniform mixture; S2: Add the cross-linking agent to the solution and stir at 300-1500 rpm for 5-20 hours at room temperature; S3: While stirring at 300-600 rpm, add acetic acid dropwise to the solution to adjust the pH to maintain it in the neutral range of pH 6.5-7.5, and continue stirring for 15-60 minutes; S4: The solution is subjected to rotary evaporation at 90-110°C using a rotary evaporator until the solvent is completely evaporated, and the resulting substrate is a modified organic amine; wherein the organic amine modifier is selected from any one of acetaldehyde, propionaldehyde, cyclopentanone, acetone, 3-pentanone, and cyclohexanone; the cross-linking agent is selected from any one of sodium triacetoxyborohydride, sodium cyanoborohydride, or borane-2-methylpyridine complex; the molar ratio of the organic amine to the organic amine modifier is 1:(1-4); The molar ratio of the organic amine to the organic amine crosslinking agent is 1:(1-4). ２ Applications of solid amine adsorbents in the adsorption field.

2. 2. The application of claim 1, wherein the organic amine is selected from any one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenepentamine, or polyethyleneimine.

3. 2. The application of claim 1, wherein the method for preparing the solid amine adsorbent comprises the following process: S1: The evaporated modified organic amine is dissolved using a base solution with a concentration of 0.5 to 3.0 mol / L, and extracted with an extractant 2 to 10 times until the extraction is complete; S2: After mixing all the extraction phases, add porous nanocarriers and rotatory evaporate using a rotary evaporator at 40-140°C until the solvent is completely evaporated to obtain product 1; S3: Product 1 is dried in a vacuum drying oven at a temperature of 40 to 140° C. for 4 to 12 hours to obtain a solid amine adsorbent.

4. 4. The application according to claim 3, wherein the alkaline aqueous solution is one of sodium hydroxide, potassium hydroxide, barium hydroxide, and ammonia.

5. 4. The application according to claim 3, wherein the volume of the alkaline solution is 1 to 3 times the volume of acetonitrile.

6. 4. The application of claim 3, wherein the extractant is one of ethyl acetate, ethyl ether, diisopropyl ether or isoamyl alcohol.

7. 4. The application according to claim 3, characterized in that the extractant is used in an amount of 0.5 to 3 times the volume of acetonitrile per application.

8. 4. The application of claim 3, wherein the porous nanocarriers are either silica, alumina, zeolite molecular sieves, resins or MOFs.

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