Solid amine adsorbent and amino modification method therefor

Abstract

A solid amine adsorbent and an amino modification method therefor. The amino modification method comprises the following steps: S1: mixing an organic amine modifier and an organic amine, adding a dispersing agent, stirring to uniformly mix, and naturally cooling; S2, adding an adsorbent carrier into a mixture solution obtained in S1, and continuously stirring to volatilize the dispersing agent; and S3, after stirring until the dispersing agent is volatilized, performing vacuum drying until the dispersing agent is completely evaporated to dryness, so as to obtain a residual solid substance, i.e., a synthesized solid amine adsorbent. The organic amine modifier is glycerol, the organic amine is polyethyleneimine, the weight-average molecular weight of the polyethyleneimine is 600-2500, and the molar ratio of hydroxyl in the organic amine modifier to the sum of primary and secondary amines of the organic amine is (0.5-1.5):1. The amino modification method is simple and economical, and the synthesized solid amine adsorbent has excellent urea resistance and has high stability in the cycle process under the high-temperature pure CO2 desorption condition.

Description

A solid amine adsorbent and its amine group modification method Technical Field

[0001] The present invention relates to the technical field of solid amine adsorbents, and in particular to a solid amine adsorbent and an amino group modification method thereof. Background Art

[0002] In recent years, the greenhouse effect caused by the massive CO2 emissions from global industrialization has led to a series of climate issues, including rising sea levels and global warming. Carbon capture technology, currently the only carbon reduction technology capable of achieving negative emissions, holds significant significance for achieving my country's "dual carbon goals." my country's carbon emissions primarily come from electricity, construction, industrial production, transportation, agriculture, and other sectors, with energy and electricity accounting for the largest share, approximately 40%. Data indicates that annual CO2 emissions from coal-fired power plants have reached billions of tons, making the task of carbon reduction a formidable one.

[0003] Currently, liquid amine chemical absorption technology, the most mainstream carbon capture technology, has achieved large-scale industrial application. However, liquid amine has drawbacks such as corrosiveness, volatility, low toxicity, and the tendency to corrode equipment, making it difficult to overcome in a short period of time. Solid amine adsorbents, synthesized by impregnation or grafting of porous supports with organic amines, are a new type of low-temperature CO2 adsorbent. They offer advantages such as fast adsorption rate, high selectivity, and large adsorption capacity, and have broad application prospects.

[0004] At present, the main desorption and regeneration method of solid amine adsorbents is temperature swing adsorption. After the adsorption is completed, the adsorbent is raised to the required temperature and the purge gas is switched to perform a desorption reaction to release CO2. In this process, in order to ensure the purity of the desorption gas, pure CO2 is often required as the desorption purge gas. As shown in Figure 1, under high temperature and CO2 atmosphere, the organic amine in the adsorbent faces the problem of chemical deactivation due to the irreversible formation of urea compounds. During the cyclic adsorption and desorption process, the performance of the adsorbent will gradually decrease until it is completely deactivated. The core problem of the current cyclic application of solid amine adsorbents is to inhibit the formation of urea compounds during the desorption process of solid amine adsorbents under high temperature and CO2 atmosphere. Therefore, it is necessary to provide a solid amine adsorbent that is simple and economical to synthesize and has high cyclic stability during the cyclic process of high-temperature pure CO2 desorption conditions, so as to promote the industrial application of solid amine adsorbents.

[0005] Summary of the Invention

[0006] In view of the defects in the prior art, the present invention provides a solid amine adsorbent and an amino modification method thereof.

[0007] The present invention provides a method for modifying the amino group of a solid amine adsorbent, comprising the following steps:

[0008] S1: Mix the organic amine modifier and the organic amine, add 5 to 25 times the volume of the dispersant, stir at 300 to 1200 rpm for 3 to 15 minutes to mix evenly, and cool naturally to room temperature of 15-25°C;

[0009] S2: adding the adsorbent carrier to the mixture solution obtained in S1, stirring continuously at 300-1200 rpm for 4-8 hours at room temperature to 60°C in a ventilated environment to allow the dispersant to gradually evaporate;

[0010] S3: After stirring until the dispersant is basically volatilized, place the sample in a vacuum drying oven and dry it in a vacuum environment at 50-105°C for 4-6 hours until the dispersant is completely evaporated. The remaining solid matter is the synthesized solid amine adsorbent;

[0011] The organic amine modifier is glycerol having two secondary hydroxyl groups and one tertiary hydroxyl group. Experiments of the present invention show that polyhydroxy glycerol has a significant promoting effect on the cyclic stability of the solid amine adsorbent.

[0012] The organic amine is polyethyleneimine (PEI), which has high thermal stability and a weight-average molecular weight of 600-2500. The molar ratio of the hydroxyl groups (-OH) in the glycerol to the sum of the primary and secondary amines (-NH2 and -NH) in the PEI is hydroxyl:primary and secondary amine = (0.5-1.5):1. Figure 4 shows the functional group locations and interaction diagram of glycerol, polyethylene glycol, and PEI.

[0013] Furthermore, the adsorbent carrier is nano-SiO2. The optional nano-SiO2 material is commercially available nano-SiO2, with reference models including SAB-15, MCM-41 and Degussa-310, in powder or granular form.

[0014] Furthermore, the dispersant is any one of methanol, water and ethanol. During the loading process, the dispersant functions to completely disperse and mix the organic amine and the organic amine modifier and gradually load them into the pore structure of the carrier.

[0015] Furthermore, the amino modification method further includes the following evaluation step after step S3: using a thermogravimetric analyzer or a fixed bed, the adsorbent synthesized in step S3 is subjected to single adsorption and cyclic adsorption tests by selecting an appropriate program according to the properties of the sample, and compared with the unmodified solid amine adsorbent to compare the adsorption amount and cyclic stability; and using infrared spectroscopy to test the characteristic functional groups of the sample after cyclic adsorption to determine the formation of urea compounds, which are deactivation products of the solid amine adsorbent.

[0016] Furthermore, in the test procedure of the adsorption performance of the adsorbent in the evaluation step, the adsorption temperature for single adsorption and cyclic adsorption is 100-150°C, and the adsorption atmosphere is 50 mL min -1 Ar or CO2, the desorption temperature is 30-105℃, and the desorption atmosphere is 50mL·min -1 of CO2.

[0017] Preferably, the infrared spectroscopy method in the evaluation step is to use a Fourier transform spectrometer to test the characteristic functional groups of the sample by a tablet pressing method. The test resolution is 8 cm -1 , the number of scans is 64 times·min -1 .

[0018] The present invention also provides a solid amine adsorbent prepared by the amino modification method.

[0019] In summary, compared with the prior art, the present invention achieves the following technical effects:

[0020] 1. The solid amine modification method of the present invention uses economical and environmentally friendly propylene glycol as a modifier. As shown in Figure 2, after being directly stirred and mixed with an organic amine, it can be directly used to load and synthesize a solid amine adsorbent. This greatly simplifies the synthesis steps and costs, has low site requirements and is easy to operate.

[0021] 2. The solid-state amine modification method of the present invention selects highly thermally stable polymeric organic amine (PEI) and glycerol containing secondary and tertiary hydroxyl groups as adsorbent raw materials. By optimizing the molecular weight of PEI, the thermal stability and adsorption capacity of the solid-state amine adsorbent are ensured. By optimizing the ratio of modifier to organic amine, adsorbent modification is achieved without compromising the efficiency of the organic amine. As shown in Table 1, the initial adsorption capacity of the modified solid-state amine adsorbents synthesized in Examples 1-5 is nearly identical to that of the unmodified adsorbent synthesized in Comparative Example 1.

[0022] 3. The solid-state amine modification method of the present invention utilizes glycerol, which has a high hydroxyl density, as an organic amine modifier. The adjacent secondary and tertiary hydroxyl groups of the glycerol molecules can form hydrogen bonds with the amine groups of the organic amine molecules. As shown in Figures 4 and 5, compared to PEG-200, the adjacent hydroxyl groups of the glycerol molecules can interact with the adjacent amine groups of the PEI molecules, resulting in increased viscosity and improved stability. Under actual desorption conditions, this can significantly reduce the irreversible conversion of amine groups to urea groups, thereby improving the cyclic stability of the solid-state amine adsorbent. Figure 7 shows that the adsorption performance of the unmodified adsorbent rapidly declines, while the glycerol-modified adsorbent exhibits excellent stability during the cyclic process, with an average performance drop of only approximately 1% per adsorption. Figure 3 also shows that after cycling, the unmodified adsorbent exhibits three characteristic urea peaks, while the modified adsorbent exhibits only a faint urea peak. Therefore, the glycerol-modified solid-state amine adsorbent prepared by this method exhibits excellent urea resistance in applications, significantly promoting the industrial application of solid-state amine adsorbents. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0024] FIG1 is a schematic diagram showing the adsorption principle and urea deactivation of a solid amine adsorbent in the prior art of the present invention.

[0025] FIG2 is a process diagram for synthesizing a modified solid amine adsorbent.

[0026] Figure 3 is the infrared spectrum of the solid amine adsorbent prepared by loading propylene glycol-modified and unmodified PEI onto a mesoporous SiO2 carrier after 10 cycles.

[0027] Figure 4 shows the molecular structures of glycerol (a), PEG-200 (b), and PEI-1200 (c), as well as a schematic diagram of the interaction principle of PEI-1200 modified with PEG-200 (d) and glycerol (e).

[0028] Figure 5 shows the time-dependent viscosity curves of PEI modified with glycerol and PEG-200. Top: glycerol modification; bottom: PEG-200 modification.

[0029] FIG6 is a line graph showing the change in adsorption amount after 10 cycles of adsorption in Examples 1 to 5.

[0030] FIG7 is a line graph showing the change in adsorption amount after 10 cycles of adsorption in Comparative Examples 1 to 3.

[0031] FIG8 is a line graph showing the change in adsorption amount after 10 cycles of adsorption in Comparative Examples 4 to 5.

[0032] FIG9 is a line graph showing the change in adsorption amount after 10 cycles of adsorption in Comparative Examples 6 to 8.

[0033] FIG10 is a line graph showing the change in adsorption amount after 10 cycles of adsorption in Comparative Examples 9 to 10. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0035] The object of the present invention is to provide a method for synthesizing a modified solid amine adsorbent. In this method, an organic amine PEI and a hydroxyl-rich organic amine modifier glycerol are loaded onto a carrier by an impregnation method to prepare a modified solid amine adsorbent. In order to achieve efficient and stable utilization of the solid amine adsorbent, the present application introduces additional polyhydroxy compounds to make it have higher cyclic stability and urea resistance. The modification mechanism is shown in Figures 4 and 5. The primary amine (-NH2) and secondary amine (-NH) adjacent to the surface of the organic amine molecular chain can interact with the adjacent secondary and tertiary hydroxyl groups (-OH) on the glycerol molecule through hydrogen bonds during the adsorption of CO2, thereby increasing the viscosity and improving the stability. Furthermore, the original pathway of the reaction between the amine group and CO2 as shown in Figure 1 is changed. The new pathway protonates the hydroxyl groups on the glycerol molecule while generating carbamate. Furthermore, the protonated hydroxyl groups undergo a dehydration reaction, which inhibits the formation of urea compounds. The specific reaction equation is as follows:

[0036] This significantly improves the stability of the organic amine's amino group, effectively enhancing cyclic stability during the temperature swing adsorption process. Furthermore, the organic amine modifier glycerol can effectively improve the dispersion of the organic amine on the carrier surface, promoting the diffusion and adsorption of CO2 during the adsorption process, ensuring the efficiency of the modified solid amine adsorbent.

[0037] The raw materials in the examples and comparative examples of the present invention can be obtained commercially, as follows:

[0038] Glycerol: CAS: 6-81-5, Shanghai test;

[0039] PEI-300: weight average molecular weight 300, CAS: 9002-98-6, Thermo Fisher Scientific;

[0040] PEI-600: weight average molecular weight 600, CAS: 9002-98-6, Thermo Fisher Scientific;

[0041] PEI-1200: weight average molecular weight 1200, CAS: 9002-98-6, Thermo Fisher Scientific;

[0042] PEI-1800: weight average molecular weight 1800, CAS: 9002-98-6, Thermo Fisher Scientific;

[0043] PEI-10000: weight-average molecular weight 10,000, CAS: 9002-98-6, Thermo Fisher Scientific;

[0044] PEG-200: weight average molecular weight is 200, CAS: 25322-68-3, Shanghai Hu trial;

[0045] CTAB: molecular weight 364.45, CAS: 57-09-0, Shanghai Hushi;

[0046] PEHA: molecular weight 232.38, CAS: 4067-16-7, Shanghai Aladdin;

[0047] EG: molecular weight is 62.068, CAS: 107-21-1, Shanghai Aladdin.

[0048] Example 1

[0049] A method for modifying the amino group of a solid amine adsorbent, comprising the following steps:

[0050] Step 1. Weigh 1 part glycerol (GI) and 1 part PEI-1200 in a 1:1 molar ratio of secondary and tertiary hydroxyl groups (-OH) in glycerol to the sum of the primary and secondary amines of PEI-1200 in the organic amine (-NH2 and -NH) (the mass ratio of glycerol to PEI-1200 is 1:2). Add the mixture to 25 parts of methanol solution, stir continuously at 400 rpm for 5 minutes, and then cool naturally to room temperature for use.

[0051] Step 2. Add 1 part of commercial SiO2 (Degussa-310, pore volume V P =1.2g·cm -3 ) was added to the above solution and stirred at 600 rpm for about 6 hours until the methanol solution gradually evaporated;

[0052] Step 3. After the methanol solution has basically evaporated, place the sample in a vacuum drying oven and vacuum dry it at 60°C for 6 hours until the methanol solution is completely evaporated. The remaining solid material is the synthesized solid amine adsorbent;

[0053] Step 4. The adsorption performance of the above-synthesized adsorbent was tested. The single adsorption procedure was set as follows: In the first stage, the air flow rate was 50 mL min -1 Ar was used as the carrier gas and the sample was heated at 10 °C·min -1 The heating rate was raised from 30°C to 120°C, and the temperature was kept stable for 30 min for degassing, and then the temperature was raised at 5°C·min -1 The temperature was lowered to 90°C at a cooling rate of 100 mL / min and the carrier gas was immediately switched to 50 mL / min. -1 The sample was adsorbed by CO2 and kept stable at this temperature for 60 minutes. In the third stage, after the adsorption was completed, the carrier gas was switched to 50 mL min -1 Ar, at 10℃·min -1 The temperature was raised to 120°C at a heating rate to start desorption, and the procedure was terminated after stabilizing at the desorption temperature for 30 minutes.

[0054] The cyclic adsorption program was set as follows: in the first stage, degassing was performed according to the above degassing program. After stabilization at the degassing temperature for 15 min, the temperature was lowered to the specific adsorption temperature of 90 °C, and the carrier gas was immediately switched to 50 mL min -1 The CO2 was stabilized at this temperature for 30 minutes, and the sample was adsorbed. In the third stage, after the adsorption was completed, the sample was heated at 10℃·min -1 The temperature was raised to 150 ° C at a heating rate of 100 ° C to start desorption, and it was stabilized at this desorption temperature for 15 minutes, and then the temperature was lowered to 90 ° C. In the fourth stage, the cycle began, and after the cooling was completed, the procedures of the second and third stages were repeated 9 times, completing 10 cycles of adsorption-desorption.

[0055] Example 2

[0056] A method for amino modification of a solid amine adsorbent is the same as Example 1 except that the organic amine used is PEI-600.

[0057] Example 3

[0058] A method for amino modification of a solid amine adsorbent is the same as Example 1 except that the organic amine used is PEI-1800.

[0059] Example 4

[0060] A method for amino modification of a solid amine adsorbent, the other contents being the same as those of Example 1, except that the molar ratio of the hydroxyl group (-OH) in glycerol to the sum of the primary and secondary amines in the organic amine (-NH2 and -NH) is 0.5:1 (the mass ratio of glycerol to PEI-1200 is 1:4). One part of glycerol and one part of PEI-1200 are weighed.

[0061] Example 5

[0062] A method for amino modification of a solid amine adsorbent, the other contents being the same as those of Example 1, except that the molar ratio of the hydroxyl group (-OH) in glycerol to the sum of the primary and secondary amines in the organic amine (-NH2 and -NH) is 1.5:1 (the mass ratio of glycerol to PEI-1200 is 3:4). One part of glycerol and one part of PEI-1200 are weighed.

[0063] Comparative Example 1

[0064] A method for modifying the amino group of a solid amine adsorbent is the same as that of Example 1 except that only PEI-1200 is added instead of glycerol as a modifier.

[0065] Comparative Example 2

[0066] A method for amino modification of a solid amine adsorbent, the other contents being the same as those of Example 1, except that the molar ratio of the hydroxyl group (-OH) in glycerol to the sum of the primary and secondary amines in the organic amine (-NH2 and -NH) is 0.2:1 (the mass ratio of glycerol to PEI-1200 is 1:10). One part of glycerol and one part of PEI-1200 are weighed.

[0067] Comparative Example 3

[0068] A method for amino modification of a solid amine adsorbent, the other contents being the same as those of Example 1, except that the molar ratio of the hydroxyl group (-OH) in glycerol to the sum of the primary and secondary amines in the organic amine (-NH2 and -NH) is 2:1 (the mass ratio of glycerol to PEI-1200 is 1:1). One part of glycerol and one part of PEI-1200 are weighed.

[0069] Comparative Example 4

[0070] A method for amino modification of a solid amine adsorbent is the same as Example 1 except that the organic amine used is PEI-300.

[0071] Comparative Example 5

[0072] A method for amino modification of a solid amine adsorbent is the same as Example 1 except that the organic amine used is PEI-10000.

[0073] Comparative Example 6

[0074] A method for modifying the amino group of a solid amine adsorbent is the same as that of Example 1 except that the modifier used is PEG-200.

[0075] Comparative Example 7

[0076] A method for modifying the amino group of a solid amine adsorbent is the same as that of Example 1 except that ethylene glycol (EG) is used as the modifier.

[0077] Comparative Example 8

[0078] A method for modifying the amino group of a solid amine adsorbent is the same as that of Example 1 except that the modifier used is cetyltrimethylammonium bromide (CTAB).

[0079] Comparative Example 9

[0080] A method for modifying the amino group of a solid amine adsorbent is the same as that of Example 1 except that the organic amine used is pentaethylenehexamine (PEHA).

[0081] Comparative Example 10

[0082] A method for modifying the amino group of a solid amine adsorbent is the same as that of Example 1 except that the organic amine used is pentaethylenehexamine (PEHA) and the modifier used is ethylene glycol.

[0083] The test results of the initial adsorption amount, the adsorption amount after 10 cycles and the remaining percentage of adsorption amount of Examples 1 to 5 and Comparative Examples 1 to 10 are shown in Table 1:

[0084] Table 1. Test results of Examples and Comparative Examples

[0085] The results of Examples 1-3 show that the molecular weight of PEI affects the initial adsorption capacity and cyclic stability of the adsorbent. As the molecular weight of PEI increases, the first adsorption capacity of the synthesized adsorbent decreases, and the cyclic stability also decreases. The reason is that the increase in molecular weight leads to the folding of the organic amine molecules, the exposed available amino groups are reduced, and the interaction between propylene glycol and PEI is also spatially restricted, and the anti-urea performance is not fully exerted. Compared with PEI-300 in Comparative Example 4 and PEI-10000 in Comparative Example 5, as shown in Figure 8, the organic amine PEI in the molecular weight range of 600 to 2500 preferred by this application performs well in both cyclic stability and adsorption capacity. The first and final adsorption capacities can be maintained at around 3 mmol / g, and the remaining adsorption capacity after 10 cycles is also above 88.6%.

[0086] The test results of Examples 1, 4, and 5 show that the addition of glycerol improves the cyclic stability of the adsorbent but has a slight impact on the adsorption capacity. This is because glycerol occupies the remaining pores in the support available for gas diffusion. The results of Comparative Examples 1 and 2 indicate that the absence of glycerol or too low an addition level will reduce the adsorbent's urea resistance. However, as shown in Comparative Example 3, excessive glycerol addition will directly block the adsorbent's gas diffusion channels, significantly reducing the adsorption capacity.

[0087] In addition, the present invention compares the modification effects of similar modifiers widely used in current research, such as PEG-200 (polyethylene glycol, molecular weight 200), EG (ethylene glycol), and CTAB (cetyltrimethylammonium bromide), on organic amine-loaded synthetic adsorbents. The results show that EG and PEG-200, which have two primary hydroxyl groups, as well as the surfactant CTAB, only slightly improve the cyclic stability of the adsorbent, which is difficult to meet the requirements of practical industrial application. The difference between the modification effects of PEG-200 and glycerol on PEI can be demonstrated in Figures 4 and 5: glycerol has adjacent secondary and tertiary hydroxyl groups, which can interact with adjacent amine groups of PEI. The macroscopic manifestation is an increase in viscosity, thereby achieving a protective effect on the amine groups of PEI. However, due to the single and distant hydroxyl groups of PEG-200, it cannot protect every group of PEI. Instead, it acts as a surfactant to improve dispersibility. The macroscopic manifestation is a decrease in viscosity, and it cannot achieve a protective effect on the amine groups of PEI.

[0088] Comparative Examples 9 and 10 demonstrate the adsorption performance and cyclic stability of adsorbents synthesized after modification of small molecule organic amine PEHA with propylene glycol and PEG-200. It can be found that the modification effect of both on small molecule organic amines is obvious. The reason is that the molecules of small molecule amines are relatively small and can actively react with the single hydroxyl group of propylene glycol or PEG-200 to achieve the effect of protecting the amino group.

[0089] In summary, the organic amine adsorbent prepared by mixing the preferred glycerol modifier of this application with an organic amine PEI with a molecular weight of 600-2500 at a molar ratio of hydroxyl group to the sum of primary and secondary amines of (0.5-1.5):1 has excellent adsorption performance and cyclic stability, and has broad industrial application prospects.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for modifying the amine group of a solid amine adsorbent, characterized in that: The steps include: S1: Mix the organic amine modifier and the organic amine, add the dispersant, stir to make the mixture uniform, and cool naturally; S2: adding the adsorbent carrier to the mixture solution obtained in S1, and continuously stirring to volatilize the dispersant; S3: After stirring until the dispersant is volatilized, vacuum drying is performed until the dispersant is completely evaporated, and the remaining solid matter is the synthesized solid amine adsorbent; The organic amine modifier is propylene glycol, the organic amine is polyethyleneimine, the weight average molecular weight of the polyethyleneimine is 600-2500, and the molar ratio of the sum of hydroxyl groups and primary and secondary amines of the organic amine in the organic amine modifier is hydroxyl group: primary and secondary amine = (0.5-1.5):

1.

2. The amino modification method according to claim 1, characterized in that: The adsorbent carrier is nano-SiO2.

3. The amino modification method according to claim 1, characterized in that: The dispersant is any one of methanol, water and ethanol.

4. The amino modification method according to claim 1, characterized in that: The amino modification method further includes the following evaluation steps after step S3: The adsorbent synthesized in step S3 is subjected to single adsorption and cyclic adsorption tests using a thermogravimetric analyzer or a fixed bed, and a suitable program is selected according to the properties of the sample, and the adsorption amount and cyclic stability are compared with the unmodified solid amine adsorbent; Infrared spectroscopy was used to test the characteristic functional groups of the samples after cyclic adsorption to determine the generation of urea compounds; thus, a comprehensive comparison was made to evaluate the effectiveness of the synthesis method.

5. The amino modification method according to claim 4, characterized in that: The program setting of a single adsorption in the test program of the adsorbent adsorption performance in the evaluation step is as follows: In the first stage, the air flow rate was 50 mL min -1 Ar was used as the carrier gas and the sample was heated at 10 °C min -1 The heating rate was raised from 30°C to 120°C, and the sample was degassed for 30 min at this temperature to remove moisture, CO2 and other impurities in the sample. -1 The temperature is lowered to the adsorption temperature at a cooling rate of 30 to 105° C. In the second stage, when the temperature drops to the adsorption temperature, the carrier gas is immediately switched to 50 mL min -1 The sample was adsorbed at the adsorption temperature for 60 min. In the third stage, after the adsorption is completed, the carrier gas is switched to 50 mL min -1 Ar or CO2, at 10℃·min -1 The temperature is raised to a specific desorption temperature at a heating rate of 100 to 150° C. to start desorption, and the procedure is terminated after stabilizing at the desorption temperature for 30 minutes or 40 minutes.

6. A solid amine adsorbent prepared by the amino modification method according to any one of claims 1 to 5.

Images