Solid amine sorbents for adsorbing co2 and methods of making and using the same

Abstract

The present disclosure relates to a solid amine adsorbent for adsorbing CO2 and a preparation method and application thereof, which adopts aminosilica sol to graft modify a cellulose matrix, uniformly introduces mesoporous SiO2 into the fiber network structure, plays a role of structural reinforcement, and avoids abrasion in industrial application; secondly, amine groups on the surface are uniformly distributed on the fiber, can provide a large number of CO2 chemical adsorption sites, and is beneficial to improve the adsorption performance and selectivity of the material to CO2.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a CO2 adsorbent, in particular, to a solid amine adsorbent for adsorbing CO2 and a preparation method and application thereof. BACKGROUND

[0002] Carbon dioxide (CO2) is a major greenhouse gas that causes global warming, and most of it comes from the combustion of fossil fuels. Among various methods for capturing carbon dioxide, the adsorption method has the advantages of good effect, low energy demand, low cost and relatively wide application conditions compared with the absorption method, membrane separation method and low-temperature distillation method. Common adsorbents include activated carbon, molecular sieve, solid amine, mesoporous SiO2 and MOFs, etc. The solid amine adsorbent has been widely used due to its significant CO2 adsorption capacity and selectivity, strong water resistance and many other advantages. The amine group functionalization of porous materials is usually achieved by impregnation to form CO2 adsorption active centers. However, the amine groups on the solid amine adsorbent prepared by impregnation are not uniformly dispersed, so maintaining the high dispersion of amine groups on the carrier is a research hotspot for efficient capture of CO2. SUMMARY

[0003] The purpose of the present disclosure is to provide a solid amine adsorbent for adsorbing CO2 and a preparation method and application thereof. The method can prepare a solid amine adsorbent with a fibrous network structure. The solid amine adsorbent has a large specific surface area, pore volume and mesoporous SiO2, which is beneficial to mass transfer and plays a role in structural reinforcement, overcoming the problems of low mechanical strength and easy pulverization of carbon materials in industrial applications, and prolonging the service life of the adsorbent. The surface of the network structure is also distributed with more uniformly dispersed amine groups, which can improve the adsorption effect of CO2 and achieve efficient and high-selectivity adsorption of CO2.

[0004] To achieve the above-mentioned purpose, the first aspect of the present disclosure provides a preparation method of a solid amine adsorbent for adsorbing CO2, which comprises:

[0005] (1) mixing amino silane, alcohol and water, and sequentially adding an acidic treatment agent and an alkaline treatment agent to the obtained first mixture to obtain an aminated silica sol;

[0006] (2) contacting a biological cellulose matrix with the aminated silica sol, and then placing the obtained second mixture in an ethanol atmosphere for aging treatment to obtain an aminated SiO2 / cellulose composite wet gel;

[0007] (3) performing pre-oxidation treatment and carbonization treatment on the aminated SiO2 / cellulose composite wet gel to obtain an aminated SiO2 / carbon fiber composite aerogel;

[0008] (4) placing the amino-silica / carbon fiber composite aerogel into an alkali solution for impregnation treatment, and then sequentially performing activation treatment, cleaning treatment and drying treatment on the obtained product after drying.

[0009] Optionally, in step (1), the molar ratio of the amino silane, water, alcohol, acidic treating agent and basic treating agent is 1:(2-8.5):(2-40):(0.001-0.02):(0.001-0.02), preferably 1:(2.5-7):(3-30):(0.001-0.01):(0.001-0.01).

[0010] Optionally, in step (1), the amino silane is selected from one or more of N-aminoethyl-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane; the alcohol is selected from one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol and tert-amyl alcohol; the acidic treating agent is selected from one or more of hydrochloric acid, sulfuric acid, acetic acid and nitric acid; and the basic treating agent is selected from an organic amine and / or an inorganic base, the organic amine is selected from one or more of monoethanolamine, triethanolamine, ethylenediamine and isopropanolamine, and the inorganic base is selected from one or more of aqueous ammonia, sodium hydroxide, potassium hydroxide, potassium carbonate and sodium carbonate.

[0011] Optionally, in step (2), the weight ratio of the biological cellulose matrix to the amino-silica sol is 1:(25-60), preferably 1:(30-55); the aging treatment is performed at a temperature of 15-40℃, preferably 20-35℃, for a time of 1-5h, preferably 1.5-4.5h; and the biological cellulose matrix is synthesized from one or more of Acetobacter, Agrobacterium, Rhizobium and Sarcina.

[0012] Optionally, in step (3), the pre-oxidation treatment is performed in an air atmosphere, at a temperature of 50-150℃, preferably 65-145℃, for a time of 1-10h, preferably 2-8h; and the carbonization treatment is performed in a nitrogen atmosphere, at a temperature of 400-800℃, preferably 450-750℃, for a time of 1-8h, preferably 2-6h.

[0013] Optionally, in step (4), the mass concentration of the alkali in the alkali solution is 20-50 wt%; the temperature of the impregnation treatment is 10-50°C, preferably 25-35°C; the time is 2-5 h, preferably 2.5-4 h; the impregnation ratio of the aminated SiO2 / carbon fiber composite aerogel to the alkali solution is (0.1-5):1, preferably (0.5-3):1; the temperature of the drying is 50-120°C, preferably 80-100°C; the time is 1-7 h, preferably 2-6 h; and the alkali is selected from one or more of potassium hydroxide, sodium hydroxide, potassium carbonate and sodium carbonate.

[0014] Optionally, in step (4), the activation treatment is carried out in a nitrogen atmosphere, the temperature of the activation treatment is 500-750°C, preferably 550-700°C; the time is 1-10 h, preferably 2-8 h; the conditions of the washing treatment include washing the product after activation with an acid solution having a molar concentration of 0.1-0.5 mol / L until the pH of the washing-out liquid is 6.5-7.5; the acid solution is selected from one or more of a hydrochloric acid solution, a sulfuric acid solution, an acetic acid solution and a nitric acid solution; and the temperature of the drying treatment is 50-100°C, and the time is 2-10 h.

[0015] The second aspect of the present disclosure provides a solid amine adsorbent prepared by the preparation method of the first aspect of the present disclosure.

[0016] Optionally, the molar ratio of each element on the surface of the solid amine adsorbent satisfies N:Si:O:C=(1-8):(15-35):(10-45):(28-65), preferably N:Si:O:C=(3-5):(18-25):(24-35):(35-55).

[0017] Optionally, the particle size of the SiO2 particles in the solid amine adsorbent is 30-160 nm, preferably 50-140 nm; the specific surface area of the solid amine adsorbent is 500-1250 m 2 / g, preferably 700-1100 m 2 / g; the most probable pore size distribution is 0.1-8 nm, preferably 0.5-6 nm; the total pore volume is 0.32-0.78 cm 3 / g, preferably 0.43-0.65 cm 3 / g; the pore volume of micropores with a pore size range of 0.5-1.5 nm accounts for 30-60%, preferably 35-55%, of the total pore volume; the pore volume of mesopores with a pore size range of 2.3-6 nm accounts for 40-70%, preferably 45-65%, of the total pore volume; and the tensile strength of the solid amine adsorbent is 5-25 MPa, preferably 7-20 MPa.

[0018] The third aspect of the present disclosure provides an application of the solid amine adsorbent of the second aspect of the present disclosure in adsorptive separation of CO2.

[0019] By the above technical solution, the present disclosure provides a solid amine adsorbent for adsorbing CO2, and a preparation method and application thereof. The method adopts aminosilica sol to graft and modify a cellulose matrix, and introduces mesoporous SiO2 with amino groups into the fiber network structure of cellulose. The mesoporous SiO2 is not only beneficial to mass transfer, but also plays a role in structural reinforcement, avoiding wear in industrial applications. Secondly, the amino groups on the surface of the mesoporous SiO2 provide a large number of CO2 chemical adsorption sites, which is beneficial to improve the adsorption performance and selectivity of the material to CO2. The aminosilica / cellulose composite wet gel is converted into a composite aerogel with more porous structure by pre-oxidation treatment and carbonization treatment, which can further improve the CO2 adsorption capacity of the material. The use of impregnation treatment and activation treatment is beneficial to the formation of oxygen-containing functional groups on the surface of carbon fibers, thereby improving the adsorption of CO2. The solid amine adsorbent provided by the present disclosure has a large specific surface area, pore volume and mesoporous SiO2, which is beneficial to mass transfer and plays a role in structural reinforcement, overcoming the problems of low mechanical strength and easy pulverization of carbon materials in industrial applications, thereby prolonging the service life of the adsorbent. The surface of the network structure is also distributed with a large number of dispersed and uniform amino groups and oxygen-containing functional groups, which can improve the adsorption effect of CO2 and realize efficient and high-selectivity adsorption of CO2.

[0020] Other features and advantages of the present disclosure will be described in detail in the following specific embodiments section. DETAILED DESCRIPTION

[0021] The specific embodiments of the present disclosure are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

[0022] The first aspect of the present disclosure provides a preparation method of a solid amine adsorbent for adsorbing CO2, which comprises:

[0023] (1) mixing aminosilane, alcohol and water, and sequentially adding an acid treatment agent and an alkaline treatment agent to the obtained first mixture to obtain aminosilica sol;

[0024] (2) contacting a biological cellulose matrix with the aminosilica sol, and then placing the obtained second mixture in an ethanol atmosphere for aging treatment to obtain aminosilica / cellulose composite wet gel;

[0025] (3) pre-oxidizing and carbonizing the aminosilica / cellulose composite wet gel to obtain aminosilica / carbon fiber composite aerogel;

[0026] (4) placing the amino-silica / carbon fiber composite aerogel into an alkali solution for impregnation treatment, and drying the product obtained after the treatment, and then sequentially performing activation treatment, cleaning treatment and drying treatment on the product.

[0027] The method provided by the present disclosure adopts amino-silica sol to graft and modify the cellulose matrix, and uniformly introduces mesoporous SiO2 with amino into the fiber network structure of cellulose. The mesoporous SiO2 is not only beneficial to mass transfer, but also plays a role in structural reinforcement, avoiding abrasion in industrial applications. In addition, the amino on the surface of the mesoporous SiO2 provides a large number of CO2 chemical adsorption sites, which is beneficial to improve the adsorption performance and selectivity of the material to CO2. The pre-oxidation treatment and carbonization treatment can convert the amino-silica / cellulose composite wet gel into a composite aerogel with more porous structure, which can further improve the CO2 adsorption capacity of the material. The impregnation treatment and activation treatment are beneficial to the formation of oxygen-containing functional groups on the surface of carbon fibers, thereby improving the CO2 adsorption.

[0028] In an embodiment of the present disclosure, in step (1), the molar ratio of the amino silane, water, alcohol, acidic treatment agent and basic treatment agent is 1:(2-8.5):(2-40):(0.001-0.02):(0.001-0.02), and preferably 1:(2.5-7):(3-30):(0.001-0.01):(0.001-0.01). In the above embodiment, the amino silane, alcohol, water, acidic treatment agent and basic treatment agent are selected in the preferred ratio, which is beneficial to the formation of amino-silica sol with a specific microstructure.

[0029] In an embodiment of the present disclosure, in step (1), the amino silane is selected from one or more of N-aminoethyl-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane; the alcohol is selected from one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol and tert-amyl alcohol; the acidic treatment agent is selected from one or more of hydrochloric acid, sulfuric acid, acetic acid and nitric acid; and the basic treatment agent is selected from organic amine and / or inorganic base, the organic amine is selected from one or more of monoethanolamine, triethanolamine, ethylenediamine and isopropanolamine, and the inorganic base is selected from one or more of ammonia, sodium hydroxide, potassium hydroxide, potassium carbonate and sodium carbonate.

[0030] In one embodiment of the present disclosure, in step (2), the weight ratio of the biological cellulose matrix to the aminated silica sol is 1:(25-60), preferably 1:(30-55); the temperature of the aging treatment is 15-40°C, preferably 20-35°C; the time is 1-5h, preferably 1.5-4.5h; and the biological cellulose matrix is synthesized from one or more of Acetobacter, Agrobacterium, Rhizobium and Sarcina. The biological cellulose matrix of the present disclosure has good biodegradability, high porosity, strong flexibility and strength. Mixing the biological cellulose matrix with the aminated silica sol and performing the aging treatment can facilitate the uniform introduction of mesoporous SiO2 into the fiber network structure, playing a role in structural reinforcement; meanwhile, the aminos on the mesoporous SiO2 can be introduced into the cellulose, improving the adsorption performance and selectivity of the material to CO2.

[0031] In one embodiment of the present disclosure, in step (3), the pre-oxidation treatment is performed in an air atmosphere, the temperature of the pre-oxidation treatment is 50-150°C, preferably 65-145°C; the time is 1-10h, preferably 2-8h; the carbonization treatment is performed in a nitrogen atmosphere, the temperature of the carbonization treatment is 400-800°C, preferably 450-750°C; and the time is 1-8h, preferably 2-6h. In the above embodiment, the preferred pre-oxidation treatment is adopted to make the gelation process proceed slowly, which is conducive to the regulation of the ratio of micropores and mesopores; and the preferred high-temperature carbonization treatment is adopted, which is conducive to the conversion of the aminated SiO2 / cellulose composite wet gel into an aminated SiO2 / carbon fiber composite aerogel, and the aerogel has the characteristics of high porosity and specific surface area, high content of amino functional groups, etc., effectively improving the adsorption amount of CO2.

[0032] In one embodiment of the present disclosure, in step (4), the mass concentration of the alkali in the alkali solution is 20-50% by weight; the temperature of the immersion treatment is 10-50°C, preferably 25-35°C; the time is 2-5h, preferably 2.5-4h; the immersion ratio of the aminated SiO2 / carbon fiber composite aerogel to the alkali solution is (0.1-5):1, preferably (0.5-3):1; the temperature of the drying is 50-120°C, preferably 80-100°C; the time is 1-7h, preferably 2-6h; and the alkali is selected from one or more of potassium hydroxide, sodium hydroxide, potassium carbonate and sodium carbonate. The immersion ratio refers to the weight ratio of the aminated SiO2 / carbon fiber composite aerogel to the alkali solution. In the above embodiment, the aminated SiO2 / carbon fiber composite aerogel is subjected to the immersion treatment with the alkali solution, which can form abundant pores on the surface of the carbon fiber, adjust the pore size distribution, and also produce defects and unsaturated bonds on the surface, so that oxygen is adsorbed on the defects to form surface oxygen-containing functional groups, improving the adsorption of CO2.

[0033] In one embodiment of the present disclosure, in step (4), the activation treatment is performed in a nitrogen atmosphere, the temperature of the activation treatment is 500-750°C, preferably 550-700°C; the time is 1-10h, preferably 2-8h; the cleaning treatment is performed by using an acid solution with a molar concentration of 0.1-0.5mol / L to clean the product after activation until the pH of the washing liquid is 6.5-7.5; the acid solution is selected from one or more of hydrochloric acid solution, sulfuric acid solution, acetic acid solution and nitric acid solution; the drying treatment is performed at a temperature of 50-100°C for 2-10h. In the above embodiment, the preferred activation treatment is beneficial to form active sites and promote the formation of pores in the carbon fiber material; the cleaning treatment can remove the excess alkali solution in the aerogel.

[0034] The second aspect of the present disclosure provides a solid amine adsorbent prepared by the preparation method of the first aspect of the present disclosure.

[0035] In one embodiment of the present disclosure, the molar ratio of each element on the surface of the solid amine adsorbent satisfies N:Si:O:C=(1-8):(15-35):(10-45):(28-65), preferably N:Si:O:C=(3-5):(18-25):(24-35):(35-55).

[0036] The solid amine adsorbent provided by the present disclosure has a surface with uniformly dispersed amino groups and oxygen-containing functional groups, which is beneficial to improve the adsorption effect of CO2 and realize efficient and selective adsorption of CO2.

[0037] In one embodiment of the present disclosure, the particle size of SiO2 in the solid amine adsorbent is 30-160nm, preferably 50-140nm; the specific surface area of the solid amine adsorbent is 500-1250m 2 / g, preferably 700-1100m 2 / g; the most probable pore size distribution is 0.1-8nm, preferably 0.5-6nm; the total pore volume is 0.32-0.78cm 3 / g, preferably 0.43-0.65cm 3wherein the pore volume of micropores with a pore size ranging from 0.5 to 1.5 nm accounts for 30 to 60%, preferably 35 to 55% of the total pore volume; wherein the pore volume of mesopores with a pore size ranging from 2.3 to 6 nm accounts for 40 to 70%, preferably 45 to 65% of the total pore volume; and the tensile strength of the solid amine adsorbent is 5 to 25 MPa, preferably 7 to 20 MPa. The solid amine adsorbent of the present disclosure has a fiber cross-linked network structure, which has a large specific surface area, pore volume and mesoporous structure, and is beneficial to mass transfer. In addition, the uniformly dispersed mesoporous SiO2 on the solid amine adsorbent plays a role in structural reinforcement, effectively solving the problem of easy wear of carbon-based materials in industrial applications, overcoming the defects of low mechanical strength and easy pulverization of carbon materials in industrial applications, and prolonging the service life of the adsorbent.

[0038] The third aspect of the present disclosure provides the use of the solid amine adsorbent of the second aspect of the present disclosure in adsorptive separation of CO2.

[0039] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited in any way by the following examples.

[0040] In the examples and comparative examples of the present disclosure, the raw materials used are commercially available materials.

[0041] Elemental analysis of N, Si, O and C in the solid amine adsorbent was performed by X-ray photoelectron spectrometer (Thermo, model K-Alpha);

[0042] The tensile strength of the material was tested by a universal testing machine (AGX-100PLUS, shimadzu, Japan) at a test speed of 2 mm / min;

[0043] The particle size of SiO2 particles was observed by scanning electron microscope (FlexSEM1000II, HITACHI);

[0044] The specific surface area and total pore volume of the solid amine adsorbent were measured by a specific surface area tester (Micromeritics, model ASAP2020), and the specific method was as follows: the sample was placed in a sample treatment system, vacuumized at 300°C to 1.33x10 -2 Pa, and the sample was purified for 4 h; the adsorption and desorption amounts of nitrogen of the purified sample under different specific pressures P / P0 were tested at a liquid nitrogen temperature of -196°C, and the N2 adsorption-desorption isotherm curve was obtained, the specific surface area was calculated by the BET method, and the micropore volume and mesopore volume of the sample were calculated by the t-plot method, and the adsorption amount at a specific pressure P / P0 of 0.98 or less was taken as the total pore volume of the sample.

[0045] Example 1

[0046] (1) mixing N-aminoethyl-3-aminopropyltrimethoxysilane (aminosilane), ethanol and deionized water to obtain a first mixture, then adding sulfuric acid (acidic treatment agent) drop by drop into the first mixture to obtain an aminosilica sol after hydrolysis; wherein the molar ratio of N-aminoethyl-3-aminopropyltrimethoxysilane: deionized water: ethanol: sulfuric acid: ammonia is 1:2.5:3:0.001:0.001;

[0047] (2) placing the biological cellulose hydrogel prepared by fermentation of acetic acid bacteria in a beaker, soaking in clean water for 30 min, replacing the water for 3 times, then cutting into blocks with a size of 0.5 cm*0.5 cm*0.5 cm, removing the water in the substrate after freeze-drying to obtain a biological cellulose substrate; immersing 3 g of the biological cellulose substrate in 90 g of the aminosilica sol for 15 min (the weight ratio of the biological cellulose substrate to the aminosilica sol is 1:30), then placing the obtained second mixture in an ethanol atmosphere for aging treatment, the temperature of the aging treatment is 20℃, and the time is 1.5 h to obtain an aminosilica / cellulose composite wet gel;

[0048] (3) placing the aminosilica / cellulose composite wet gel in an air atmosphere for pre-oxidation treatment under normal pressure, the temperature of the pre-oxidation treatment is 65℃, and the time is 2 h; the obtained product is heated to 450℃ under a nitrogen atmosphere for carbonization treatment for 2 h, then cooled to room temperature to obtain an aminosilica / carbon fiber composite aerogel;

[0049] (4) immersing the aminosilica / carbon fiber composite aerogel in a potassium hydroxide solution (alkali, mass concentration is 20%) for immersion treatment, the temperature of the immersion treatment is 25℃, and the time is 2.5 h, the obtained product after drying the water is placed in a tube furnace, heated to 550℃ under a nitrogen protective atmosphere for activation treatment for 2 h; then washing with 0.1 mol / L hydrochloric acid (acid solution) until the washing liquid is neutral (i.e. pH is 6.5-7.5), placing the washed product in an oven for drying treatment at 50℃ for 10 h to obtain a solid amine adsorbent, and the structural characteristics are shown in Table 1.

[0050] Example 2

[0051] The same as example 1, the only difference is that:

[0052] (1) 3-aminopropyltrimethoxysilane (aminosilane), methanol and deionized water were mixed and stirred uniformly, then hydrochloric acid (acidic treatment agent) was added dropwise into the first mixture and stirred, after sufficient hydrolysis, ethylenediamine (alkaline treatment agent) was added dropwise into the mixture and stirred, to obtain aminosilica sol; the molar ratio of 3-aminopropyltrimethoxysilane: deionized water: methanol: hydrochloric acid: ethylenediamine was 1:7:30:0.01:0.01;

[0053] (2) 3g of the biological cellulose matrix was immersed in 165g of the aminosilica sol for 5min (the weight ratio of the biological cellulose matrix to the aminosilica sol was 1:55), then the second mixture was placed in an ethanol atmosphere for aging treatment, the aging treatment was carried out at 35℃ for 4.5h, to obtain SiO2 / cellulose composite wet gel;

[0054] (3) the aminosilica / cellulose composite wet gel was placed in an air atmosphere for pre-oxidation treatment at normal pressure, the pre-oxidation treatment was carried out at 145℃ for 8h; the obtained product was heated to 750℃ under nitrogen atmosphere for carbonization treatment for 6h, then cooled to room temperature, to obtain aminosilica / carbon fiber composite aerogel;

[0055] (4) the aminosilica / carbon fiber composite aerogel was immersed in potassium hydroxide solution (alkali, mass concentration was 50%) for immersion treatment, the immersion treatment was carried out at 35℃ for 4h, the obtained product after drying the moisture was placed in a tube furnace, heated to 700℃ under nitrogen protective atmosphere for activation treatment for 8h; then washed with 0.5mol / L hydrochloric acid (acid solution) until the washing liquid was neutral (i.e. pH was 6.5-7.5), placed in an oven for drying treatment at 50℃ for 10h, to obtain solid amine adsorbent, the structural characteristics were shown in Table 1.

[0056] Example 3

[0057] The same as Example 1, the only difference was that:

[0058] (1) 3-aminopropyltrimethoxysilane (aminosilane), methanol and deionized water were mixed and stirred uniformly, then hydrochloric acid (acidic treatment agent) was added dropwise into the first mixture and stirred, after sufficient hydrolysis, ethylenediamine (alkaline treatment agent) was added dropwise into the mixture and stirred, to obtain aminosilica sol; the molar ratio of 3-aminopropyltrimethoxysilane: deionized water: methanol: hydrochloric acid: ethylenediamine was 1:7:30:0.01:0.01;

[0059] (2) 2 g of the bio-type cellulose matrix was immersed in 80 g of the aminated silica sol for 10 min (the weight ratio of the bio-type cellulose matrix to the aminated silica sol was 1:40), and then the obtained second mixture was placed in an ethanol atmosphere for aging treatment at 28°C for 3 h to obtain an aminated SiO2 / cellulose composite wet gel;

[0060] (3) The aminated SiO2 / cellulose composite wet gel was placed in an air atmosphere for pre-oxidation treatment at normal pressure at 100°C for 5 h, and then the obtained product was heated to 600°C under a nitrogen atmosphere for carbonization treatment for 4 h, and then cooled to room temperature to obtain an aminated SiO2 / carbon fiber composite aerogel;

[0061] (4) The aminated SiO2 / carbon fiber composite aerogel was immersed in a potassium hydroxide solution (alkali liquor, mass concentration of 35%) for immersion treatment at 30°C for 3 h, and then the obtained product after drying the moisture was placed in a tube furnace and heated to 620°C under a nitrogen protective atmosphere for activation treatment for 6 h; then the product was cleaned with 0.3 mol / L hydrochloric acid (acid solution) until the washing liquid was neutral (i.e., pH was 6.5-7.5), and then the product was placed in an oven for drying treatment at 75°C for 6 h to obtain a solid amine adsorbent, and the structural characteristics of the solid amine adsorbent are shown in Table 1.

[0062] Example 4

[0063] The same as Example 1, except that in step (3), the pre-oxidation treatment was performed at 50°C for 1 h, and finally a solid amine adsorbent was obtained, and the structural characteristics of the solid amine adsorbent are shown in Table 1.

[0064] Example 5

[0065] The same as Example 1, except that in step (3), the carbonization treatment was performed at 400°C for 1 h, and finally a solid amine adsorbent was obtained, and the structural characteristics of the solid amine adsorbent are shown in Table 1.

[0066] Example 6

[0067] The same as Example 1, except that in step (4), the immersion treatment was performed at 10°C for 2 h, and finally a solid amine adsorbent was obtained, and the structural characteristics of the solid amine adsorbent are shown in Table 1.

[0068] Example 7

[0069] The same as Example 1, except that in step (4), the activation treatment was performed at 500°C for 1 h, and finally a solid amine adsorbent was obtained, and the structural characteristics of the solid amine adsorbent are shown in Table 1.

[0070] Comparative Example 1

[0071] (1) The bio-type cellulose hydrogel prepared by acetic acid bacteria fermentation was placed in a beaker and soaked in clean water for 30 min, and the water was replaced for 3 times. Then, the bio-type cellulose hydrogel was cut into blocks with a size of 0.5 cm*0.5 cm*0.5 cm, and the water in the blocks was removed by freeze-drying to obtain a bio-type cellulose matrix. The bio-type cellulose matrix was subjected to pre-oxidation treatment in an air atmosphere at a normal pressure, and the pre-oxidation treatment temperature was 50°C, and the time was 10 h. The obtained product was subjected to carbonization treatment at 400°C for 8 h under a nitrogen atmosphere, and then cooled to room temperature to obtain carbon fiber aerogel.

[0072] (2) The carbon fiber aerogel was immersed in a potassium hydroxide solution (mass concentration 50%) for immersion treatment, and the immersion treatment temperature was 10°C, and the time was 2 h. The obtained product was placed in a tube furnace and subjected to activation treatment at 500°C for 10 h under a nitrogen protective atmosphere. Then, the product was cleaned with 0.1 mol / L hydrochloric acid until the washing liquid was neutral (i.e., pH was 6.5-7.5), and was subjected to drying treatment at 50°C in an oven for 10 h to obtain a carbon fiber adsorbent, and the structural characteristics of which are shown in Table 1.

[0073] Comparative Example 2

[0074] The same as Example 1, the only difference is that in step (1), N-aminoethyl-3-aminopropyl trimethoxysilane (aminosilane) is replaced by the same amount of tetraethyl orthosilicate, and finally a comparative solid amine adsorbent without amino groups is obtained, and the structural characteristics of which are shown in Table 1.

[0075] Comparative Example 3

[0076] The same as Example 1, the only difference is that step (3) is not performed, and the aminated SiO2 / cellulose composite wet gel obtained in step (2) is placed in 300 mL of n-hexane, 20 mL of trimethylchlorosilane is added, and it is left to stand at room temperature for 8 h, and then it is taken out and dried at 60°C for 1 h to obtain an aminated SiO2 / cellulose composite aerogel. The aminated SiO2 / cellulose composite aerogel is subjected to step (4), and finally a comparative solid amine adsorbent is obtained, and the structural characteristics of which are shown in Table 1.

[0077] Comparative Example 4

[0078] The same as Example 1, the only difference is that step (4) is not performed, and the aminated SiO2 / carbon fiber composite aerogel obtained in step (3) is used as the final comparative solid amine adsorbent, and the structural characteristics of which are shown in Table 1.

[0079] Table 1

[0080]

[0081] Test Example

[0082] The solid amine adsorbents prepared in the examples and the comparative solid amine adsorbents prepared in the comparative examples were subjected to CO2 adsorption performance test in a fixed bed reactor. Specifically, 1 g of the solid amine adsorbent was filled in the fixed bed, and then the fixed bed was heated to 105℃ at a heating rate of 5℃ / min, and 50 mL / min of high-purity N2 was introduced to remove water and air impurities remaining in the pores of the solid amine adsorbent for 1 h. When the temperature cooled to the adsorption temperature of 50℃, 15% CO2 / 85% N2 mixed gas (flow rate 60 mL / min) was introduced until the solid amine adsorbent was saturated, and then the atmosphere was changed to pure nitrogen, and the nitrogen flow rate was 50 mL / min. The fixed bed was subjected to desorption at 110℃ for 60 min. The above process was repeated 10 times, and the test results are shown in Table 2:

[0083] Table 2

[0084]

[0085] As can be seen from the data in Tables 1-2, the solid amine adsorbents prepared in Examples 1-7 using the preparation method provided in the present disclosure have a larger specific surface area, more amino groups and mesoporous SiO2. When the solid amine adsorbent is used for adsorption and separation of CO2, it has excellent CO2 saturated adsorption capacity and high compressive strength, overcoming the problem of low mechanical strength and easy pulverization of carbon materials in industrial applications, prolonging the service life of the adsorbent, and maintaining excellent CO2 adsorption effect after 10 cycles. The comparative solid amine adsorbents prepared in Comparative Examples 1-4 do not use the preparation method of the present disclosure, and the CO2 adsorption effect of the comparative solid amine adsorbents is poor, and the service life is short.

[0086] Among them, the comparison of the data of Example 1 and Example 4 shows that when the pre-oxidation treatment temperature of Example 1 is 65-145℃ and the time is 2-8h, it is beneficial to prepare a solid amine adsorbent with appropriate mesopore content, improve the selective adsorption of CO2; the comparison of the data of Example 1 and Example 5 shows that when the carbonization treatment temperature of Example 1 is 450-750℃ and the time is 2-6h, it is beneficial to improve the pore volume and specific surface area of the solid amine adsorbent, and increase the amino content; the comparison of the data of Example 1 and Example 6 shows that when the impregnation treatment temperature of Example 1 is 25-35℃ and the time is 2.5-4h, it is beneficial to form oxygen-containing functional groups on the surface of the adsorbent, and improve the adsorption of CO2; the comparison of the data of Example 1 and Example 7 shows that when the activation treatment temperature of Example 1 is 550-700℃ and the time is 2-8h, it is beneficial to form active sites, promote the formation of pores in the carbon fiber material, and prepare a solid amine adsorbent with appropriate pore structure, and improve the adsorption effect of CO2.

[0087] The preferred embodiments of the present disclosure are described in detail above, but the present disclosure is not limited to the specific details described in the above embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

[0088] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations are not described again in the present disclosure.

[0089] In addition, any combination of various different embodiments of the present disclosure can also be made, as long as it does not deviate from the idea of the present disclosure, and it should also be considered as disclosed in the present disclosure.

Claims

1. A method for the preparation of a solid amine sorbent for the adsorption of CO2, characterized in that, The preparation method comprises: (1) mixing amino silane, alcohol and water, sequentially adding acid treatment agent and alkaline treatment agent into the obtained first mixture to obtain amino-silica sol; (2) contacting biological cellulose matrix with the amino-silica sol, and then placing the obtained second mixture in ethanol atmosphere for aging treatment to obtain amino-SiO2 / cellulose composite wet gel; the biological cellulose matrix is synthesized by one or more of Acetobacter, Agrobacterium, Rhizobium and Sarcina; (3) performing pre-oxidation treatment and carbonization treatment on the amino-SiO2 / cellulose composite wet gel to obtain amino-SiO2 / carbon fiber composite aerogel; (4) immersing the amino-SiO2 / carbon fiber composite aerogel in lye for impregnation treatment, and sequentially performing activation treatment, cleaning treatment and drying treatment on the obtained product after drying.

2. The production method according to claim 1, characterized by, In step (1), the molar ratio of the amino silane, water, alcohol, acid treatment agent and alkaline treatment agent is 1:(2-8.5):(2-40):(0.001-0.02):(0.001-0.02).

3. The preparation method according to claim 2, characterized in that, In step (1), the molar ratio of the amino silane, water, alcohol, acid treatment agent and alkaline treatment agent is 1:(2.5-7):(3-30):(0.001-0.01):(0.001-0.01).

4. The production method according to claim 1, characterized by, In step (1), the amino silane is selected from one or more of N-aminoethyl-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane; the alcohol is selected from one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol and tert-amyl alcohol; the acid treatment agent is selected from one or more of hydrochloric acid, sulfuric acid, acetic acid and nitric acid; the alkaline treatment agent is selected from organic amine and / or inorganic base, the organic amine is selected from one or more of monoethanolamine, triethanolamine, ethylenediamine and isopropanolamine, and the inorganic base is selected from one or more of ammonia, sodium hydroxide, potassium hydroxide, potassium carbonate and sodium carbonate.

5. The preparation method according to claim 1, characterized in that, In step (2), the weight ratio of the biological cellulose matrix to amino-silica sol is 1:(25-60), and the aging treatment is performed at a temperature of 15-40℃ for 1-5h.

6. The production method according to claim 5, wherein In step (2), the weight ratio of the biological cellulose matrix to amino-silica sol is 1:(30-55), and the aging treatment is performed at a temperature of 20-35℃ for 1.5-4.5h.

7. The preparation method according to claim 1, characterized in that, In step (3), the pre-oxidation treatment is performed in air atmosphere, and the pre-oxidation treatment is performed at a temperature of 50-150℃ for 1-10h; the carbonization treatment is performed in nitrogen atmosphere, and the carbonization treatment is performed at a temperature of 400-800℃ for 1-8h.

8. The preparation method according to claim 7, characterized in that, In step (3), the pre-oxidation treatment is performed at a temperature of 65-145℃ for 2-8h; the carbonization treatment is performed at a temperature of 450-750℃ for 2-6h.

9. The method of claim 1, wherein, In step (4), the mass concentration of alkali in the alkaline solution is 20~50% by weight; the temperature of the impregnation treatment is 10~50℃ and the time is 2~5h; the impregnation ratio of the aminated SiO2 / carbon fiber composite aerogel to the alkaline solution is (0.1~5):1; The drying temperature is 50~120℃, and the time is 1~7h; The alkali is selected from one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, and sodium carbonate.

10. The method of claim 9, wherein, In step (4), the impregnation treatment temperature is 25~35℃ and the time is 2.5~4h; the impregnation ratio of the aminated SiO2 / carbon fiber composite aerogel to the alkaline solution is (0.5~3):1; The drying temperature is 80~100℃, and the time is 2~6h.

11. The method of claim 1, wherein, In step (4), the activation treatment is carried out in a nitrogen atmosphere, the temperature of the activation treatment is 500~750℃, and the time is 1~10h; The cleaning process includes washing the activated product with an acid solution of 0.1-0.5 mol / L until the pH of the washing solution is 6.5-7.5; the acid solution is selected from one or more of hydrochloric acid solution, sulfuric acid solution, acetic acid solution and nitric acid solution. The drying process is carried out at a temperature of 50~100℃ for 2~10 hours.

12. The method of claim 11, wherein, In step (4), the activation treatment is performed at a temperature of 550~700℃ for 2~8h.

13. A solid amine adsorbent prepared by any one of claims 1 to 12.

14. The solid amine adsorbent of claim 13, wherein, The molar ratio of each element on the surface of the solid amine adsorbent satisfies: N:Si:O:C = (1~8):(15~35):(10~45):(28~65).

15. The solid amine adsorbent of claim 14, wherein, The molar ratio of each element on the surface of the solid amine adsorbent satisfies: N:Si:O:C = (3~5):(18~25):(24~35):(35~55).

16. The solid amine adsorbent of claim 13, wherein, The SiO2 particle size of the solid amine adsorbent is 30-160 nm, the specific surface area of the solid amine adsorbent is 500-1250 m 2 / g, the most probable pore size distribution is 0.1-8 nm, and the total pore volume is 0.32-0.78 cm 3 / g; wherein the pore volume of micropores with a pore size range of 0.5-1.5 nm accounts for 30-60% of the total pore volume, and the pore volume of mesopores with a pore size range of 2.3-6 nm accounts for 40-70% of the total pore volume. The tensile strength of the solid amine adsorbent is 5~25 MPa.

17. The solid amine adsorbent of claim 16, wherein, The SiO2 particle size of the solid amine adsorbent is 50-140 nm, the specific surface area of the solid amine adsorbent is 700-1100 m 2 / g, the most probable pore size distribution is 0.5-6 nm, and the total pore volume is 0.43-0.65 cm 3 / g; wherein the pore volume of micropores with a pore size range of 0.5-1.5 nm accounts for 35-55% of the total pore volume, and the pore volume of mesopores with a pore size range of 2.3-6 nm accounts for 45-65% of the total pore volume. The tensile strength of the solid amine adsorbent is 7~20 MPa.

18. The use of the solid amine adsorbent according to any one of claims 13 to 17 in the adsorption and separation of CO2.

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