Efficient molecular sieve adsorbent for carbon dioxide adsorption and preparation method thereof

Abstract

The invention relates to the technical field of adsorbents, and provides an efficient molecular sieve adsorbent for adsorbing carbon dioxide and a preparation method of the efficient molecular sieve adsorbent aiming at the problem that a traditional Na-type 13X molecular sieve is poor in CO2 adsorption performance under low partial pressure. The adsorbent is prepared by using a template agent, aluminum hydroxide, nano aluminum oxide and silica sol as raw materials through the steps of crystallization, calcination and the like. The template agent is a functional molecule integrating a phosphonic acid group, long-chain alkyl and polyethylene glycol dicarboxylic acid, the phosphonic acid group stabilizes a skeleton, the long-chain alkyl provides a graphene-like layer to inhibit water molecule adsorption, and the polyethylene glycol dicarboxylic acid guides micropores to grow orderly and cooperate with each other to form the efficient molecular sieve adsorbent for carbon dioxide adsorption. The CO2 adsorption capacity, the dynamic adsorption rate and the moisture resistance of the adsorbent under low partial pressure are improved.

Description

Technical Field

[0001] The present application relates to the technical field of adsorbents, and in particular to a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption and a preparation method thereof. Background Art

[0002] Against the backdrop of the world actively promoting the "dual carbon" goals, carbon dioxide capture technology has become a key link in achieving a low-carbon transition. In emission sources such as industrial exhaust and flue gas from coal-fired power plants, carbon dioxide is often in a low partial pressure environment. Although traditional Na-type 13X molecular sieves have a certain adsorption capacity for carbon dioxide due to their low silicon-aluminum ratio, the adsorption amount is easily affected by polar water molecules in a humid environment, resulting in competitive adsorption, a decrease in the adsorption amount of carbon dioxide, and a low adsorption capacity retention rate, making it difficult to meet the demand for efficient capture. In the existing technology, although methods such as cation exchange or post-modification of silane hydrophobic layers can improve performance to a certain extent, they will bring disadvantages such as loss of active sites, pore blockage, and complex methods. In addition, in conventional pressure scenarios, the adsorption capacity of traditional Na-type 13X molecular sieves also has room for improvement, and it cannot simultaneously meet the demand for efficient adsorption of carbon dioxide under low partial pressure in multiple working conditions. Summary of the Invention

[0003] To address the poor CO2 adsorption performance of traditional Na-type 13X molecular sieves at low partial pressures, this application provides a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption and a preparation method thereof. The adsorbent is prepared using a template, aluminum hydroxide, nano-alumina, and silica sol as raw materials through steps such as crystallization and calcination. The template is a functionalized molecule integrating phosphonic acid groups, long-chain alkyl groups, and polyethylene glycol dicarboxylic acid. The phosphonic acid groups stabilize the skeleton, the long-chain alkyl groups provide a graphene-like layer to inhibit water molecule adsorption, and the polyethylene glycol dicarboxylic acid guides the orderly growth of micropores. Together, they form a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption, improving the CO2 adsorption capacity, dynamic adsorption rate, and moisture resistance of the adsorbent at low partial pressures.

[0004] In order to achieve the above purpose, this application adopts the following technical solutions:

[0005] In a first aspect, the present application provides a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption, wherein the high-efficiency molecular sieve adsorbent for carbon dioxide adsorption is prepared from molecular sieve raw powder and clay, wherein the molecular sieve raw powder is obtained by heating and crystallizing a gel precursor and then calcining it under a nitrogen atmosphere; the gel precursor is obtained by reacting a coordination solution, nano-alumina and silica sol, wherein the coordination solution is prepared from aluminum hydroxide and a template; the template is prepared from polyethylene glycol dicarboxylic acid, anhydrous ethanol, a phosphorylated siloxane intermediate and dicyclohexylcarbodiimide; the phosphorylated siloxane intermediate is obtained by reacting a siloxane intermediate, a phosphate and ethanol; and the siloxane intermediate is obtained by reacting a long-chain olefin, a silane coupling agent and chloroplatinic acid.

[0006] In a second aspect, the present application provides a method for preparing a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption, comprising the following steps:

[0007] S1, reacting a long-chain olefin with a silane coupling agent to prepare a siloxane intermediate, then using the siloxane intermediate and a phosphate to prepare a phosphated siloxane intermediate, and using the phosphated siloxane intermediate, polyethylene glycol dicarboxylic acid, and dicyclohexylcarbodiimide to prepare a template;

[0008] S2. dissolving aluminum hydroxide with sodium hydroxide to obtain an aluminum solution, adding a template to the aluminum solution to obtain a coordination solution, adding nano-alumina to the coordination solution, ultrasonically dispersing, adding silica sol, and aging to obtain a gel precursor;

[0009] S3, heating the gel precursor to crystallize and obtain a crystallized material; calcining the crystallized material under a nitrogen atmosphere to obtain a molecular sieve raw powder;

[0010] S4. Mixing the molecular sieve raw powder with clay and granulating the mixture to obtain the high-efficiency molecular sieve adsorbent for carbon dioxide adsorption.

[0011] Beneficial technical effects:

[0012] The present invention utilizes an innovatively designed template containing phosphonic acid groups and long-chain alkyl groups to prepare molecular sieves. By introducing long-chain alkyl groups into the template, self-assembled micelles are formed, which are locked in the gaps of the silicon-aluminum skeleton. After calcination under nitrogen, they are carbonized to form channels, adsorb CO2, and simultaneously generate graphene-like layers that are evenly coated on the channel surface. The carbon-carbon bonds (CC) and carbon-hydrogen bonds (CH) of the graphene-like layers are both non-polar bonds with low surface energy and weak interaction with polar water molecules, which can block the adsorption sites of water molecules, effectively inhibit competitive adsorption of water molecules, and improve the molecular sieve in a humid environment. The adsorption capacity of CO2 in the template is increased; at the same time, the phosphate group is anchored to the siloxane skeleton of the template, and the phosphonic acid group can form an Al-OP bond with the aluminum ion through coordination, thereby enhancing the binding force between the template and the silicon-aluminum skeleton; in addition, the polyethylene glycol dicarboxylic acid chain segment introduced in the template is combined with the silicon hydroxyl group through hydrogen bonding, and the effect of hydrogen bonding forces the silicon-aluminum skeleton to grow in an orderly arrangement around the polyethylene glycol chain segment. The polyethylene glycol chain segment is carbonized during the calcination stage to generate a regular microporous structure, thereby obtaining a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption with a porous structure. The present invention prepares a molecular sieve with a microporous structure by using a template, and a graphene-like layer exists on the pore surface. When adsorbing CO2, the adsorption amount of water molecules is reduced, thereby improving the adsorption performance of the high-efficiency molecular sieve adsorbent for carbon dioxide adsorption under low partial pressure conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the preparation method of the high-efficiency molecular sieve adsorbent for carbon dioxide adsorption of the present invention.

[0014] Figure 2 This is an adsorption kinetics curve of carbon dioxide adsorption capacity-time / pressure of the high-efficiency molecular sieve adsorbent for carbon dioxide adsorption prepared in Example 2 of the present invention at 25°C.

[0015] Figure 3 This is a carbon dioxide adsorption capacity-pressure isotherm test diagram of the high-efficiency molecular sieve adsorbent for carbon dioxide adsorption prepared in Example 2 of the present invention at 25° C. and 250 mmHg.

[0016] Figure 4 This is a scanning electron microscope image of the molecular sieve raw powder prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0017] In order to make the technical problems, technical solutions, and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below with reference to the following examples. However, this should not be construed as limiting the scope of this application to the following examples. Without departing from the above-mentioned method concepts of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0018] In this application, the terms used in this application are for the purpose of describing specific embodiments only and are not intended to be limiting of the application.

[0019] As used in this application, the singular forms "for," "or," "an," "any," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0020] In addition, the terms “first” and “second”, if used, are only used for descriptive purposes and should not be understood as indicating or implying relative importance.

[0021] In a first aspect, the present application provides a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption, wherein the high-efficiency molecular sieve adsorbent for carbon dioxide adsorption is prepared from molecular sieve raw powder and clay, wherein the molecular sieve raw powder is obtained by heating and crystallizing a gel precursor and then calcining it under a nitrogen atmosphere; the gel precursor is obtained by reacting a coordination solution, nano-alumina and silica sol, wherein the coordination solution is prepared from aluminum hydroxide and a template; the template is prepared from polyethylene glycol dicarboxylic acid, anhydrous ethanol, a phosphorylated siloxane intermediate and dicyclohexylcarbodiimide; the phosphorylated siloxane intermediate is obtained by reacting a siloxane intermediate, a phosphate and ethanol; and the siloxane intermediate is obtained by reacting a long-chain olefin, a silane coupling agent and chloroplatinic acid.

[0022] In a feasible implementation scenario, the mass ratio of the molecular sieve powder and clay is (7.9-8.1):(1.95-2.05); the mass ratio of the template, aluminum hydroxide and silica sol is 12:(6.1-6.3):(19.6-20), and the nano-alumina accounts for 2wt%-2.2wt% of the coordination solution; the mass ratio of the polyethylene glycol dicarboxylic acid, anhydrous ethanol, the phosphorylated siloxane intermediate and the dicyclohexylcarbodiimide is (10-10.3):100:(4.5-5.5):(1.8-2.4); the mass ratio of the siloxane intermediate, phosphate and ethanol is 1:(2-2.2):30; the mass ratio of the long-chain olefin, silane coupling agent and chloroplatinic acid is (10-12):15:0.1.

[0023] In a feasible implementation scenario, the clay includes one or more of attapulgite, kaolin, bentonite and montmorillonite; the silica sol is alkaline sodium type, with a particle size of 5-20nm and a SiO2 content of 25%; the phosphate ester includes one of dimethyl methylphosphonate and diethyl methylphosphonate; the long-chain olefin includes one of 1-dodecene, 1-tetradecene and 1-decene; the silane coupling agent is 3-chloropropyltrimethoxysilane; the nano-alumina particle size is ≤50nm; and the polyethylene glycol dicarboxylic acid Mw=1000.

[0024] According to the standard of HG / T 2521-2008, JN-25 series silica sol is alkaline sodium type with SiO2 content of 25%. The particle size of JN-25Ⅰ is less than 10nm, and the particle size of JN-25Ⅱ is 10-20nm. It is easy to dissociate into silicate under alkaline conditions, and quickly condenses with aluminate to form a uniform silicon-aluminum network, avoiding the agglomeration of large particles and causing pore blockage. The methoxy group of dimethyl methylphosphonate undergoes ester exchange with the methoxy group of siloxane intermediate, introducing phosphonic acid group, which is then coordinated with Al 3+ Stable bonding; nano-alumina particle size ≤ 50nm, as a seed, provides heterogeneous nucleation sites, accelerates crystallization, and fine-tunes the micropore diameter to adapt to the CO2 molecular dynamics diameter; polyethylene glycol dicarboxylic acid Mw = 1000 has a moderate chain length, which can not only guide the orderly growth of micropores through hydrogen bonds, but also avoid being too long to make the template difficult to remove.

[0025] In a feasible implementation scenario, the high-efficiency molecular sieve adsorbent for carbon dioxide adsorption is spherical or strip-shaped; the particle size of the spherical high-efficiency molecular sieve adsorbent for carbon dioxide adsorption is 0.5-4.75 mm; the diameter of the strip-shaped high-efficiency molecular sieve adsorbent for carbon dioxide adsorption is 1.6-3 mm and the length is 3-5 mm.

[0026] In a second aspect, the present application provides a method for preparing a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption, comprising the following steps:

[0027] S1, reacting a long-chain olefin with a silane coupling agent to prepare a siloxane intermediate, then using the siloxane intermediate and a phosphate to prepare a phosphated siloxane intermediate, and using the phosphated siloxane intermediate, polyethylene glycol dicarboxylic acid, and dicyclohexylcarbodiimide to prepare a template;

[0028] S2. dissolving aluminum hydroxide with sodium hydroxide to obtain an aluminum solution, adding a template to the aluminum solution to obtain a coordination solution, adding nano-alumina to the coordination solution, ultrasonically dispersing, adding silica sol, and aging to obtain a gel precursor;

[0029] S3, heating the gel precursor to crystallize and obtain a crystallized material; calcining the crystallized material under a nitrogen atmosphere to obtain a molecular sieve raw powder;

[0030] S4. Mixing the molecular sieve raw powder with clay and granulating the mixture to obtain the high-efficiency molecular sieve adsorbent for carbon dioxide adsorption.

[0031] In a feasible implementation, the preparation temperature of the siloxane intermediate is 80-85°C and the time is 5-7 hours; the preparation temperature of the phosphorylated siloxane intermediate is 80-85°C and the time is 10-12 hours; the template is prepared at room temperature and the reaction time is 18-24 hours.

[0032] Long-chain olefins and silane coupling agent 3-chloropropyltrimethoxysilane react with chloroplatinic acid to form a stable C-Si bond through the addition reaction of olefins and silane, generating a siloxane intermediate containing a long-chain alkyl group, which makes the siloxane intermediate hydrophobic. The siloxane intermediate and dimethyl methylphosphonate are heated to reflux in ethanol, and the phosphonic acid group is introduced through the ester exchange reaction between the methoxy group of siloxane and the methoxy group of dimethyl methylphosphonate. The phosphonic acid group can coordinate Al under strong alkaline conditions. 3+ , stable skeleton, Al 3+ In alkaline solution with AlO2 - or hydrated ion [Al(H2O)6] 3+ When the phosphonic acid group dissociates into -PO3 2- After that, its two negatively charged oxygen atoms (O - ) will be simultaneously with Al 3+ The empty orbital forms a coordination bond, forming an Al-OP bond. This bidentate coordination mode has higher energy and greater stability than the monodentate coordination bond. In addition, due to the attraction of positive and negative charges, there may be aluminosilicate around Al 3+ The phenomenon of excessive aggregation will result in uneven pore size, stress concentration in the skeleton, and reduced stability. 2- Able to neutralize Al 3+The charge of the silicon-aluminum skeleton is weakened, and the attraction is weakened, which promotes the uniform growth of the silicon-aluminum skeleton. Excessive chloroplatinic acid > 0.1% will lead to an increase in by-products and affect the purity of the template. Excessive olefins promote the complete reaction of silane, avoiding the hydrolysis of unreacted silane to generate Si-OH, which interferes with the subsequent coordination of phosphonic acid groups.

[0033] Dicyclohexylcarbodiimide mediates the condensation reaction between the phosphorylated siloxane intermediate and polyethylene glycol dicarboxylic acid. In the formed template, the polyethylene glycol dicarboxylic acid chain segment is combined with the silicon hydroxyl group through hydrogen bonding. The hydrogen bonding forces the silicon-aluminum skeleton to grow in an orderly manner around the polyethylene glycol chain segment. The polyethylene glycol chain segment is carbonized during the calcination stage to form a regular microporous structure; the long-chain alkyl forms self-assembled micelles, which are locked in the gaps of the silicon-aluminum skeleton. After calcination under nitrogen, it is carbonized to form pores, adsorbing CO2 and generating a graphene-like layer at the same time. It is evenly coated on the surface of the pore, blocking the adsorption sites of water molecules, effectively inhibiting the competitive adsorption of water molecules, and improving the adsorption capacity of the molecular sieve for CO2 in a humid environment; the long-chain alkyl acts as a hydrophobic segment to induce the formation of mesopores.

[0034] In a feasible implementation scenario, the preparation method of the gel precursor includes: dispersing aluminum hydroxide in deionized water at a solid-liquid ratio of 1:(35-40), heating to 80-85°C, adjusting the pH to 11±0.1 with sodium hydroxide, cooling to room temperature, and adding a template to obtain a coordination solution; adding nano-alumina to the coordination solution, and ultrasonicating for 15-30 minutes; then adding silica sol, adjusting the pH to 10.5±0.1 with HCl, reacting at room temperature for 1-2 hours, and then aging in a closed container for 2-3 hours to obtain a gel precursor.

[0035] NaOH strong base promotes the dissolution of aluminum hydroxide into AlO2 - , coordinates with the phosphonic acid group of the template to form Al-OP bond, pH = 11 inhibits the rapid polycondensation of silicon and aluminum, pH> 11.5 will cause premature solidification of the gel and disordered pores. Silica sol dissociates into silicate ions under alkaline conditions, and reacts with AlO2 in aluminate. - The aluminosilicate network is formed through polycondensation of oxygen bridges (Si-O-Al). Nanoalumina, added at a dosage of 2-2.2wt%, acts as a seed crystal, promoting heterogeneous nucleation of the molecular sieve, accelerating crystallization and fine-tuning the micropore diameter, enhancing physical adsorption capacity. Excessive addition can lead to pore blockage. The long-chain alkane segments of the template self-assemble into micelles, which are then carbonized after calcination under nitrogen to form a pore structure coated with a graphene-like layer, improving carbon dioxide adsorption performance.

[0036] In a feasible implementation scenario, the preparation method of the crystallized material includes: sealing the gel precursor, heating it to 120-130° C. at a heating rate of 3-5° C. / min, and crystallizing it at a constant temperature for 36-48 hours to obtain the crystallized material.

[0037] In a feasible implementation scenario, the preparation method of the molecular sieve raw powder comprises the following steps: the crystallization material is heated to 300-320℃ at a rate of 3-5℃ / min, and then is kept at the temperature for 1.5-2h in an air atmosphere; nitrogen is introduced to protect, and then the temperature is raised to 550-580℃ at a rate of 5-10℃ / min, and then is kept at the temperature for 3-4h; and then the temperature is reduced to room temperature at a rate of 40-50℃ / h, so that the molecular sieve raw powder is obtained.

[0038] The template agent is removed by calcination at a high temperature of 550-580℃ under nitrogen protection, and long-chain alkane is carbonized to form a graphene-like layer composed of carbon atoms. In the structure, both the carbon-carbon bond (C-C) and the carbon-hydrogen bond (C-H) are nonpolar bonds, the surface energy is low, and the interaction with polar water molecules is weak, so that the adsorption of water molecules is inhibited, and the adsorption performance of carbon dioxide is improved.

[0039] In a feasible implementation scenario, the specific method for granulation comprises the following steps: the molecular sieve raw powder is mixed with clay to obtain a premix, 2.9%-3.2% of an aluminum nitrate solution by mass of the premix is added, and then the mixture is uniformly mixed and granulated by a sugar coating machine or an extruder; the granules are calcined at 600-650℃ for 3-4h; and then the high-efficiency molecular sieve adsorbent for carbon dioxide adsorption is obtained after cooling.

[0040] After the molecular sieve raw powder is mixed with clay, the aluminum nitrate solution acts as a binder, and then the mixture is formed into granules with high mechanical strength through extrusion and high-temperature calcination (600-650℃). The aluminum nitrate is decomposed into aluminum oxide at a high temperature, and the strength of the molecular sieve granules is enhanced through Al-O-Si bonds.

[0041] The following will specifically describe a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption and a preparation method thereof provided by the present application in combination with different embodiments.

[0042] Embodiment 1

[0043] As shown in Figure 1 a preparation method of a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption comprises the following steps:

[0044] 1. 1-tetradecene, 3-chloropropyltrimethoxysilane and chloroplatinic acid are mixed at a mass ratio of 10:15:0.1, and then are reacted at 80℃ for 5h. The siloxane intermediate is obtained by vacuum distillation purification. The siloxane intermediate, diethyl methylphosphonate and ethanol are mixed at a mass ratio of 1:2:30, and then are heated to reflux at 80℃ for 10h. The phosphonated siloxane intermediate is obtained. The polyethylene glycol dicarboxylic acid is dissolved in anhydrous ethanol, and then the phosphonated siloxane intermediate and dicyclohexyl carbodiimide are added. The template agent is obtained by reacting at room temperature for 18h. The mass ratio of the polyethylene glycol dicarboxylic acid, the anhydrous ethanol, the phosphonated siloxane intermediate and the dicyclohexyl carbodiimide is 10:100:5.5:1.8;

[0045] 2. Aluminum hydroxide was dispersed in deionized water at a solid-liquid ratio of 1:35, heated to 80°C, and 1 mol / L sodium hydroxide solution was added dropwise to adjust the pH to 12±0.1. After cooling to room temperature, a template was added to obtain a coordination solution. Nano-alumina was added to the coordination solution and ultrasonicated for 15 minutes. The amount of nano-alumina added was 2 wt% of the coordination solution. JN-25Ⅰ silica sol was then added, and the pH was adjusted to 10.5±0.1 with 1 mol / L HCl. The reaction was stirred at room temperature for 1 hour and aged in a sealed container for 2 hours to obtain a gel precursor. The mass ratio of template, aluminum hydroxide, and silica sol was 12:6.1:20.

[0046] 3. After sealing the gel precursor, heat it to 130°C at a heating rate of 5°C / min and crystallize it at this constant temperature for 36 hours. After cooling, wash it with deionized water until it is neutral, centrifuge it, and dry it at 80°C for 12 hours to obtain a crystallized material.

[0047] 4. The crystallized material was heated to 300 ° C at 3 ° C / min and calcined, kept warm for 1.5 hours under air atmosphere, then nitrogen protection was introduced, and the temperature was increased to 550 ° C at 5 ° C / min, kept warm for 3 hours, and cooled to room temperature at a rate of 40 ° C / h to obtain molecular sieve raw powder;

[0048] 5. The molecular sieve powder and kaolin were mixed in a mass ratio of 7.9:2.05 to obtain a premix, and an 8wt% aluminum nitrate solution was added at a concentration of 2.9% by mass of the premix. The mixture was granulated with a sugar coater, and the mixture was sieved through 4-mesh and 8-mesh sieves to obtain particles with a particle size of 2.36-4.75 mm. The particles were calcined at 600°C for 3 hours and cooled to obtain a spherical high-efficiency molecular sieve adsorbent for carbon dioxide adsorption.

[0049] Example 2

[0050] like Figure 1 As shown, a method for preparing a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption comprises the following steps:

[0051] 1. 1-Dodecene, 3-chloropropyltrimethoxysilane, and chloroplatinic acid were mixed in a mass ratio of 11:15:0.1, reacted at 85°C for 6 hours, and purified by vacuum distillation to obtain a siloxane intermediate. The siloxane intermediate, dimethyl methyl phosphate, and ethanol were mixed in a mass ratio of 1:2.1:30, heated under reflux at 80°C for 12 hours to obtain a phosphorylated siloxane intermediate. Polyethylene glycol dicarboxylic acid was dissolved in anhydrous ethanol, and the phosphorylated siloxane intermediate and dicyclohexylcarbodiimide were added and reacted at room temperature for 20 hours to obtain a template. The mass ratio of polyethylene glycol dicarboxylic acid, anhydrous ethanol, phosphorylated siloxane intermediate, and dicyclohexylcarbodiimide was 10.1:100:5:2.1.

[0052] 2. Aluminum hydroxide was dispersed in deionized water at a solid-liquid ratio of 1:38, heated to 85°C, and 1 mol / L sodium hydroxide solution was added dropwise to adjust the pH to 12±0.1. After cooling to room temperature, a template was added to obtain a coordination solution. Nano-alumina was added to the coordination solution and ultrasonicated for 30 minutes. The amount of nano-alumina added was 2.1 wt% of the coordination solution. JN-25Ⅰ silica sol was then added, and the pH was adjusted to 10.5±0.1 with HCl. The reaction was stirred at room temperature for 1.5 hours and aged in a sealed container for 2 hours to obtain a gel precursor. The mass ratio of template, aluminum hydroxide, and JN-25Ⅰ silica sol was 12:6.2:19.8.

[0053] 3. After sealing the gel precursor, heat it to 120°C at a heating rate of 4°C / min and crystallize it at constant temperature for 42 hours. After cooling, wash it with deionized water until it is neutral, centrifuge it, and dry it at 80°C for 12 hours to obtain a crystallized material;

[0054] 4. The crystallized material was heated to 300 ° C at 4 ° C / min and calcined, kept warm for 2 hours under air atmosphere, then nitrogen protection was introduced, and the temperature was increased to 580 ° C at 5 ° C / min, kept warm for 4 hours, and cooled to room temperature at a rate of 40 ° C / h to obtain molecular sieve raw powder;

[0055] 5. The molecular sieve powder and attapulgite were mixed in a mass ratio of 8:2 to obtain a premix, and an 8wt% aluminum nitrate solution was added at a concentration of 3% of the premix. The mixture was granulated with a sugar coater, and the mixture was sieved through 8-mesh and 12-mesh sieves to obtain particles with a particle size of 1.70-2.36 mm. The mixture was calcined at 650°C for 3 hours and cooled to obtain a spherical high-efficiency molecular sieve adsorbent for carbon dioxide adsorption.

[0056] Example 3

[0057] like Figure 1 As shown, a method for preparing a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption comprises the following steps:

[0058] 1. 1-decene, 3-chloropropyltrimethoxysilane, and chloroplatinic acid were mixed in a mass ratio of 12:15:0.1, reacted at 85°C for 7 hours, and purified by vacuum distillation to obtain a siloxane intermediate; the siloxane intermediate, dimethyl phenylphosphonate, and ethanol were mixed in a mass ratio of 1:2.2, heated under reflux at 85°C for 12 hours to obtain a phosphorylated siloxane intermediate; polyethylene glycol dicarboxylic acid was dissolved in anhydrous ethanol, and the phosphorylated siloxane intermediate and dicyclohexylcarbodiimide were added and reacted at room temperature for 24 hours to obtain a template; the mass ratio of polyethylene glycol dicarboxylic acid, anhydrous ethanol, phosphorylated siloxane intermediate, and dicyclohexylcarbodiimide was 10.3:100:4.5:2.4;

[0059] 2. Aluminum hydroxide was dispersed in deionized water at a solid-liquid ratio of 1:40, heated to 85°C, and 1 mol / L sodium hydroxide solution was added dropwise to adjust the pH to 12±0.1. After cooling to room temperature, a template was added to obtain a coordination solution. Nano-alumina was added to the coordination solution and ultrasonicated for 20 minutes. The amount of nano-alumina added was 2.2 wt% of the coordination solution. JN-25Ⅱ silica sol was then added, and the pH was adjusted to 10.5±0.1 with HCl. The reaction was stirred at room temperature for 2 hours and aged in a sealed container for 2 hours to obtain a gel precursor. The mass ratio of template, aluminum hydroxide, and JN-25Ⅱ silica sol was 12:6.3:19.6.

[0060] 3. After sealing the gel precursor, heat it to 120°C at a heating rate of 3°C / min and crystallize it at constant temperature for 48 hours. After cooling, wash it with deionized water until it is neutral, centrifuge it, and dry it at 80°C for 12 hours to obtain a crystallized material;

[0061] 4. The crystallized material was heated to 320 ° C at 5 ° C / min and calcined, kept warm for 2 hours under air atmosphere, then nitrogen protection was introduced, and the temperature was increased to 580 ° C at 10 ° C / min, kept warm for 4 hours, and cooled to room temperature at a rate of 50 ° C / h to obtain molecular sieve raw powder;

[0062] 5. The molecular sieve raw powder and attapulgite were mixed in a mass ratio of 8.1:1.95 to obtain a premix, and an 8wt% aluminum nitrate solution was added at a concentration of 3.2% of the premix. After mixing, strip particles with a diameter of 1.6 mm and a length of 3 mm were extruded using an extruder. The particles were calcined at 650°C for 4 h and sieved to obtain a strip-shaped high-efficiency molecular sieve adsorbent for carbon dioxide adsorption.

[0063] Example 4

[0064] like Figure 1 As shown, a method for preparing a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption comprises the following steps:

[0065] 1. 1-Dodecene, 3-chloropropyltrimethoxysilane, and chloroplatinic acid were mixed in a mass ratio of 11:15:0.1, reacted at 85°C for 6 hours, and purified by vacuum distillation to obtain a siloxane intermediate. The siloxane intermediate, dimethyl methyl phosphate, and ethanol were mixed in a mass ratio of 1:2.1:30, heated under reflux at 80°C for 12 hours to obtain a phosphorylated siloxane intermediate. Polyethylene glycol dicarboxylic acid was dissolved in anhydrous ethanol, and the phosphorylated siloxane intermediate and dicyclohexylcarbodiimide were added and reacted at room temperature for 20 hours to obtain a template. The mass ratio of polyethylene glycol dicarboxylic acid, anhydrous ethanol, phosphorylated siloxane intermediate, and dicyclohexylcarbodiimide was 10.1:100:5:2.1.

[0066] 2. Aluminum hydroxide was dispersed in deionized water at a solid-liquid ratio of 1:38, heated to 85°C, and 1 mol / L sodium hydroxide solution was added dropwise to adjust the pH to 12±0.1. After cooling to room temperature, a template was added to obtain a coordination solution. Nano-alumina was added to the coordination solution and ultrasonicated for 30 minutes. The amount of nano-alumina added was 2.1 wt% of the coordination solution. JN-25Ⅰ silica sol was then added, and the pH was adjusted to 10.5±0.1 with HCl. The reaction was stirred at room temperature for 1.5 hours and aged in a sealed container for 2 hours to obtain a gel precursor. The mass ratio of template, aluminum hydroxide, and JN-25Ⅰ silica sol was 12:6.2:19.8.

[0067] 3. After sealing the gel precursor, heat it to 120°C at a heating rate of 4°C / min and crystallize it at constant temperature for 42 hours. After cooling, wash it with deionized water until it is neutral, centrifuge it, and dry it at 80°C for 12 hours to obtain a crystallized material;

[0068] 4. The crystallized material was heated to 300 ° C at 4 ° C / min and calcined, kept warm for 2 hours under air atmosphere, then nitrogen protection was introduced, and the temperature was increased to 580 ° C at 5 ° C / min, kept warm for 4 hours, and cooled to room temperature at a rate of 40 ° C / h to obtain molecular sieve raw powder;

[0069] 5. The molecular sieve raw powder and bentonite are mixed in a mass ratio of 8:2 to obtain a premix, and an 8wt% aluminum nitrate solution is added at a concentration of 3% of the premix. After mixing, strip particles with a diameter of 3 mm and a length of 5 mm are extruded using an extruder and calcined at 650°C for 3 hours. After cooling, a strip-shaped high-efficiency molecular sieve adsorbent for carbon dioxide adsorption is obtained.

[0070] Example 5

[0071] like Figure 1 As shown, a method for preparing a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption comprises the following steps:

[0072] 1. 1-Dodecene, 3-chloropropyltrimethoxysilane, and chloroplatinic acid were mixed in a mass ratio of 11:15:0.1, reacted at 85°C for 6 hours, and purified by vacuum distillation to obtain a siloxane intermediate. The siloxane intermediate, dimethyl methyl phosphate, and ethanol were mixed in a mass ratio of 1:2.1:30, heated under reflux at 80°C for 12 hours to obtain a phosphorylated siloxane intermediate. Polyethylene glycol dicarboxylic acid was dissolved in anhydrous ethanol, and the phosphorylated siloxane intermediate and dicyclohexylcarbodiimide were added and reacted at room temperature for 20 hours to obtain a template. The mass ratio of polyethylene glycol dicarboxylic acid, anhydrous ethanol, phosphorylated siloxane intermediate, and dicyclohexylcarbodiimide was 10.1:100:5:2.1.

[0073] 2. Aluminum hydroxide was dispersed in deionized water at a solid-liquid ratio of 1:38, heated to 85°C, and 1 mol / L sodium hydroxide solution was added dropwise to adjust the pH to 12±0.1. After cooling to room temperature, a template was added to obtain a coordination solution. Nano-alumina was added to the coordination solution and ultrasonicated for 30 minutes. The amount of nano-alumina added was 2.1 wt% of the coordination solution. JN-25Ⅰ silica sol was then added, and the pH was adjusted to 10.5±0.1 with HCl. The reaction was stirred at room temperature for 1.5 hours and aged in a sealed container for 2 hours to obtain a gel precursor. The mass ratio of template, aluminum hydroxide, and JN-25Ⅰ silica sol was 12:6.2:19.8.

[0074] 3. After sealing the gel precursor, heat it to 120°C at a heating rate of 4°C / min and crystallize it at constant temperature for 42 hours. After cooling, wash it with deionized water until it is neutral, centrifuge it, and dry it at 80°C for 12 hours to obtain a crystallized material;

[0075] 4. The crystallized material was heated to 300 ° C at 4 ° C / min and calcined, kept warm for 2 hours under air atmosphere, then nitrogen protection was introduced, and the temperature was increased to 580 ° C at 5 ° C / min, kept warm for 4 hours, and cooled to room temperature at a rate of 40 ° C / h to obtain molecular sieve raw powder;

[0076] 5. The molecular sieve powder and montmorillonite were mixed in a mass ratio of 8:2 to obtain a premix. An 8wt% aluminum nitrate solution was added at a concentration of 3% of the premix. The mixture was granulated with a sugar coater and sieved through 12-mesh and 35-mesh sieves to separate particles with a particle size of 0.50-1.70 mm. The mixture was calcined at 650°C for 3 hours and cooled to obtain a spherical high-efficiency molecular sieve adsorbent for carbon dioxide adsorption.

[0077] Comparative Example 1

[0078] A method for preparing a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption, wherein the implementation steps and parameters are the same as those in Example 2, except that a silylated intermediate is directly used for template synthesis, and dimethyl methyl phosphate is not used.

[0079] Comparative Example 2

[0080] A method for preparing a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption, wherein the implementation steps and parameters are the same as those in Example 2, except that 1-dodecene is not used.

[0081] Comparative Example 3

[0082] A method for preparing a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption, wherein the implementation steps and parameters are the same as those in Example 2, except that no template is used.

[0083] Comparative Example 4

[0084] A method for preparing a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption, wherein the implementation steps and parameters are the same as those of Example 2, except that nano-alumina is not used.

[0085] Performance Testing:

[0086] Static CO2 adsorption capacity: According to HG / T 2690-2012 "13X Molecular Sieve", the static CO2 adsorption capacity of the high-efficiency molecular sieve adsorbents for carbon dioxide adsorption prepared in Examples 1 to 5 and Comparative Examples 1 to 4 of the present invention was tested at 25°C under 250 mmHg and 2 mmHg using the static gravimetric method (VVS). The results are shown in Table 1.

[0087] Dynamic adsorption rate: According to G / T 2691-2024 “Determination of dynamic carbon dioxide adsorption by molecular sieves”, the dynamic adsorption rate of CO2 of the high-efficiency molecular sieve adsorbents for carbon dioxide adsorption prepared in Examples 1 to 5 and Comparative Examples 1 to 4 of the present invention was tested. The volume fraction of CO2 at the inlet was 450×10 -6 , the outlet CO2 volume fraction exceeds 1×10 -6 The dynamic CO2 breakthrough time was recorded to obtain the dynamic CO2 adsorption capacity, and the dynamic adsorption rate of the adsorption amount per unit volume of sample per unit time at the dynamic CO2 breakthrough time, i.e., the dynamic adsorption rate, was calculated. The results are shown in Table 1.

[0088] Moisture resistance: The high-efficiency molecular sieve adsorbents for carbon dioxide adsorption prepared in Examples 1 to 5 and Comparative Examples 1 to 4 of the present invention were placed in an environmental chamber at RH 60% and 25°C for 24 hours to simulate humid working conditions. The CO2 adsorption capacity at 2 mmHg was then tested and compared with the adsorption capacity under dry conditions. The capacity retention rate was calculated. The results are shown in Table 1.

[0089] The above performance tests were conducted under the same conditions using UOP APGⅢ molecular sieve from Honeywell, USA as a competitor. The results are shown in Table 1.

[0090] Table 1 Performance test results

[0091]

[0092] From Table 1 and Figure 2 、 Figure 3It can be seen that under the conventional pressure of 250mmHg, the CO2 adsorption capacity of the high-efficiency molecular sieve adsorbent for carbon dioxide adsorption of Examples 1 to 5 is 18.8% to 19.7%, and that of UOP APGⅢ is 19.7%. Under the low partial pressure condition of 2mmHg, the adsorption capacity reaches 6.1% to 6.2%, which is higher than the 6.0% of UOP APGⅢ; the dynamic adsorption rate is 0.18 to 0.23mmol / (g·min), and that of UOP APGⅢ is only 0.11mmol / (g·min); under the humidity condition of RH60%, the capacity retention rate reaches 78% to 88%, and that of UOP APGⅢ is 33%. The high-efficiency molecular sieve adsorbent for carbon dioxide adsorption prepared by the present invention has excellent adsorption performance for carbon dioxide, which is significantly better than its competitor UOPAPGⅢ. Figure 4 It can be seen that the molecular sieve raw powder prepared by the template agent of the present invention has a uniform particle size, an average particle size of 10-12 μm, and can be mixed with clay to form a granular molecular sieve adsorbent.

[0093] Comparative Example 1 omitted the phosphate and directly used the silanized intermediate to prepare the template. The absence of the phosphate resulted in the loss of the phosphonic acid group in the template. The phosphate provided the phosphonic acid group in the template, which was coordinated with Al by bidentate. 3+ Form a stable Al-OP bond, enhance the binding force between the template and the silicon-aluminum skeleton, and inhibit Al 3+ With SiO3 2- The excessive attraction between the template and the Al promotes the uniform polycondensation of the aluminosilicate network. 3+ The coordination effect is weakened, the charge adsorption and aggregation are enhanced during the assembly of the silicon-aluminum skeleton, the skeleton structure is disordered, the pore size distribution is uneven, the adsorption sites are reduced, and the uneven condensation of the silicon-aluminum network will cause some pores to collapse or be blocked. The CO2 adsorption capacity at 250 mmHg and 2 mmHg is reduced to 21.5% and 3.1% respectively, and the dynamic adsorption rate of 0.12 mmol / (g·min) is significantly lower than that of the embodiment. The mass transfer efficiency is reduced due to the deterioration of the pore structure. The molecular sieve skeleton is not stable enough and is easily destroyed by water molecules in a humid environment, with a capacity retention rate of only 45%.

[0094] Comparative Example 2 does not use long-chain olefins. Long-chain olefins self-assemble in the template to form micelles, providing spatial guidance for the molecular sieve pore structure. The pore structure formed after calcination can adsorb CO2. At the same time, the generated graphene-like layer coats the pore surface, inhibiting competitive adsorption of water molecules. The lack of long-chain olefins leads to a decrease in the pore structure content. At a low partial pressure (2mmHg), the CO2 adsorption capacity is only 2.8%, and the dynamic adsorption rate is 0.10mmol / (g·min), less than half of that in Example 2. At the same time, the lack of the graphene hydrophobic layer enhances the hydrophilicity of the pore surface, allowing water molecules to compete with CO2 for adsorption sites. The capacity retention rate at RH 60% is only 38%.

[0095] Comparative Example 3 did not use a template agent, which is a functionalized molecule integrating phosphonic acid group, long-chain alkyl and polyethylene glycol dicarboxylic acid. The phosphonic acid group stabilizes the framework, the long-chain alkyl provides the graphene-like layer to inhibit water molecule adsorption, and the polyethylene glycol dicarboxylic acid guides the ordered growth of micropores. Without the template agent, the silicon-aluminum species spontaneously condenses to form an unordered network with a wide pore size distribution and lacks effective pores that fit CO2 molecules (kinetic diameter 0.33 nm), with an adsorption capacity of only 16.0% at 250 mmHg and 2.2% at 2 mmHg, indicating the important role of the template agent in pore size design. The absence of the template agent results in a lack of graphene-like layers and a stable framework in the molecular sieve, with a dynamic adsorption rate of 0.08 mmol / (g·min) and a capacity retention rate of 32%, which are significantly lower than the examples, verifying the key role of the template agent in mass transfer acceleration and moisture resistance.

[0096] Comparative Example 4 did not use nano-alumina, which acts as a crystal seed to promote heterogeneous nucleation of the molecular sieve, accelerate the crystallization process, fine-tune the micropore size, and enhance the physical adsorption capacity. The absence of nano-alumina leads to a decrease in nucleation efficiency during the crystallization process, uneven crystal growth, and a micropore size that deviates from the CO2 molecule fitting range, with adsorption capacities of 20.4% at 250 mmHg and 3.5% at 2 mmHg, and a dynamic adsorption rate of 0.15 mmol / (g·min) lower than the examples, indicating the importance of the crystal seed for micropore optimization. Incomplete crystallization also leads to an increase in defects in the framework, although the graphene-like layer still exists due to the template agent, but the capacity retention rate (59%) is lower than that of Example 2, indicating that nano-alumina has an auxiliary role in improving the framework integrity and moisture resistance.

[0097] The above results show and describe the basic principles and main features of the present application and the advantages of the present application.

[0098] Those skilled in the art should understand that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection claimed by the present application is defined by the equivalents of the appended claims.

Claims

1. A high-efficiency molecular sieve adsorbent for carbon dioxide adsorption, characterized in that: The high-efficiency molecular sieve adsorbent for carbon dioxide adsorption is prepared from molecular sieve raw powder and clay, wherein the molecular sieve raw powder is obtained by heating and crystallizing a gel precursor and then calcining it under a nitrogen atmosphere; the gel precursor is obtained by reacting a coordination solution, nano-alumina and silica sol, wherein the coordination solution is prepared from aluminum hydroxide and a template; the template is prepared from polyethylene glycol dicarboxylic acid, anhydrous ethanol, a phosphorylated siloxane intermediate and dicyclohexylcarbodiimide; the phosphorylated siloxane intermediate is obtained by reacting a siloxane intermediate, a phosphate and ethanol; and the siloxane intermediate is obtained by reacting a long-chain olefin, a silane coupling agent and chloroplatinic acid.

2. The high-efficiency molecular sieve adsorbent for carbon dioxide adsorption according to claim 1, characterized in that: The mass ratio of the molecular sieve powder and clay is (7.9-8.1):(1.95-2.05); the mass ratio of the template, aluminum hydroxide and silica sol is 12:(6.1-6.3):(19.6-20), and the nano-alumina accounts for 2wt%-2.2wt% of the coordination solution; the mass ratio of the polyethylene glycol dicarboxylic acid, anhydrous ethanol, the phosphorylated siloxane intermediate and the dicyclohexylcarbodiimide is (10-10.3):100:(4.5-5.5):(1.8-2.4); the mass ratio of the siloxane intermediate, phosphate and ethanol is 1:(2-2.2):30; the mass ratio of the long-chain olefin, silane coupling agent and chloroplatinic acid is (10-12):15:0.

1.

3. The high-efficiency molecular sieve adsorbent for carbon dioxide adsorption according to claim 1, characterized in that: The clay comprises one or more of attapulgite, kaolin, bentonite and montmorillonite; the silica sol is of alkaline sodium type, has a particle size of 5-20 nm and an SiO2 content of 25%; the phosphate ester comprises one of dimethyl methylphosphonate and diethyl methylphosphonate; the long-chain olefin comprises one of 1-dodecene, 1-tetradecene and 1-decene; the silane coupling agent is 3-chloropropyltrimethoxysilane; the particle size of the nano-alumina is ≤50 nm; and the polyethylene glycol dicarboxylic acid has an Mw of 1000.

4. The high-efficiency molecular sieve adsorbent for carbon dioxide adsorption according to claim 1, characterized in that: The high-efficiency molecular sieve adsorbent for carbon dioxide adsorption is spherical or strip-shaped; the particle size of the spherical high-efficiency molecular sieve adsorbent for carbon dioxide adsorption is 0.5-4.75 mm; the diameter of the strip-shaped high-efficiency molecular sieve adsorbent for carbon dioxide adsorption is 1.6-3 mm and the length is 3-5 mm.

5. The method for preparing a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, reacting a long-chain olefin with a silane coupling agent to prepare a siloxane intermediate, then using the siloxane intermediate and a phosphate to prepare a phosphated siloxane intermediate, and using the phosphated siloxane intermediate, polyethylene glycol dicarboxylic acid, and dicyclohexylcarbodiimide to prepare a template; S2. dissolving aluminum hydroxide with sodium hydroxide to obtain an aluminum solution, adding a template to the aluminum solution to obtain a coordination solution, adding nano-alumina to the coordination solution, ultrasonically dispersing, adding silica sol, and aging to obtain a gel precursor; S3, heating the gel precursor to crystallize and obtain a crystallized material; calcining the crystallized material under a nitrogen atmosphere to obtain a molecular sieve raw powder; S4. Mixing the molecular sieve raw powder with clay and granulating the mixture to obtain the high-efficiency molecular sieve adsorbent for carbon dioxide adsorption.

6. The method for preparing a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption according to claim 5, characterized in that: The preparation temperature of the siloxane intermediate is 80-85°C and the time is 5-7 hours; the preparation temperature of the phosphorylated siloxane intermediate is 80-85°C and the time is 10-12 hours; the template is prepared at room temperature and the reaction time is 18-24 hours.

7. The method for preparing a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption according to claim 5, characterized in that: The preparation method of the gel precursor includes: dispersing aluminum hydroxide in deionized water at a solid-liquid ratio of 1:(35-40), heating to 80-85°C, adjusting the pH to 11±0.1 with sodium hydroxide, cooling to room temperature, and adding a template to obtain the coordination solution; adding nano-alumina to the coordination solution, and ultrasonicating for 15-30 minutes; then adding silica sol, adjusting the pH to 10.5±0.1 with HCl, reacting at room temperature for 1-2 hours, and then aging in a closed container for 2-3 hours to obtain the gel precursor.

8. The method for preparing a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption according to claim 5, characterized in that: The preparation method of the crystallized material comprises: sealing the gel precursor, heating it to 120-130° C. at a heating rate of 3-5° C. / min, and crystallizing it at a constant temperature for 36-48 hours to obtain the crystallized material.

9. The method for preparing a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption according to claim 5, characterized in that: The preparation method of the molecular sieve raw powder includes: heating the crystallized material to 300-320°C at 3-5°C / min, keeping the temperature under air atmosphere for 1.5-2 hours, introducing nitrogen protection, heating the material to 550-580°C at 5-10°C / min, keeping the temperature for 3-4 hours, and cooling the material to room temperature at a rate of 40-50°C / h to obtain the molecular sieve raw powder.

10. The method for preparing a high-efficiency molecular sieve adsorbent for carbon dioxide adsorption according to claim 5, characterized in that: The specific granulation method comprises: mixing the molecular sieve raw powder with clay to obtain a premix, adding 2.9% to 3.2% of the weight of the premix by weight of aluminum nitrate solution, mixing well, granulating with a sugar coater or an extruder, calcining at 600-650° C. for 3-4 hours, and cooling to obtain the high-efficiency molecular sieve adsorbent for carbon dioxide adsorption; the concentration of the aluminum nitrate solution is 7-8wt%.

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