Preparation method for microporous structure adsorbent for pressure swing adsorption

Abstract

The present invention belongs to the technical field of waste gas adsorption materials. Provided is a preparation method for a microporous structure adsorbent for pressure swing adsorption. The preparation method is characterized by comprising the following steps: mixing a template and an alumina precursor in a mass ratio of 30-40:100 to prepare spheres, and subjecting same to a heat treatment, so as to obtain alumina spheres having a porous structure; and dissolving an amino silane in a solvent, dipping the alumina spheres in same, filtering out the alumina spheres, and then drying and curing same to obtain the adsorbent. The alumina spheres of the present invention have a relatively large specific surface area and a rich pore structure, and can provide more adsorption sites and channels, which is beneficial for diffusing and adsorbing carbon dioxide molecules on the surface of the adsorbent. The cured amino can enhance the interaction force between the adsorbent and carbon dioxide, thereby improving the adsorption selectivity.

Description

Preparation method of adsorbent for microporous pressure swing adsorption Technical Field

[0001] The invention discloses a method for preparing an adsorbent for pressure swing adsorption with a microporous structure, belonging to the technical field of waste gas adsorption materials. Background Art

[0002] Many industrial environments require the adsorption of carbon dioxide from exhaust gases to reduce atmospheric emissions and meet environmental regulations. For example, adsorption of carbon dioxide from coal-, gas-, or oil-fired power plants can help reduce greenhouse gas emissions and comply with environmental regulations. Many chemical plants also adsorb carbon dioxide from their exhaust gases to reduce atmospheric emissions and lower their carbon footprint. Adsorption of carbon dioxide from exhaust gases not only reduces environmental impact but also helps businesses save energy and resources, achieving sustainable development. The carbon dioxide adsorbed on the adsorbent is then released through desorption, yielding a purer form of carbon dioxide, which has a wide range of applications.

[0003] Several pressure swing adsorbents have been developed for carbon dioxide adsorption, such as the metal-organic framework MOF-177, which can adsorb carbon dioxide with high selectivity. However, the relatively high cost of synthesizing and preparing MOF materials hinders their large-scale industrial application. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for preparing an adsorbent for pressure swing adsorption with a microporous structure that has low preparation cost and high efficiency.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a method for preparing an adsorbent for pressure swing adsorption with a microporous structure, characterized by comprising the following steps:

[0006] 1) The template agent and the alumina precursor are mixed in a mass ratio of 30 to 40:100 to form a sphere, and the alumina sphere with a porous structure is obtained by heat treatment;

[0007] 2) dissolving aminosilane in a solvent, impregnating the solvent with alumina balls, filtering out the alumina balls, and then drying and curing the resulting product.

[0008] The alumina spheres of the present invention have a large specific surface area and a rich pore structure, providing more adsorption sites and channels, which facilitates the diffusion and adsorption of carbon dioxide molecules on the adsorbent surface. The solidified amino groups can enhance the interaction between the adsorbent and carbon dioxide, improving adsorption selectivity.

[0009] Preferably, in the above preparation method, the template described in step 1) is a composite template of polystyrene and polyacrylic acid in a mass ratio of 30 to 45:55 to 70. Polystyrene has good solubility and can be mixed with an alumina precursor to form a mixed system. Polyacrylic acid, as a dispersant and stabilizer, can help polystyrene to be evenly dispersed in the alumina precursor, further promoting the formation of pores. The pore size and pore structure of the alumina spheres can be controlled by adjusting the ratio and treatment conditions of polystyrene and polyacrylic acid. At the same time, the addition of polyacrylic acid can change the surface charge of the alumina spheres, affecting the formation of pores and the distribution of pore structure. The mixed system of polystyrene and alumina precursor can form a relatively stable emulsion or colloid, which is beneficial to the stability of the molding process. Polyacrylic acid, as a dispersant and stabilizer, can increase the viscosity and dispersibility of the system, prevent the precipitation and aggregation of particles, and thus improve the stability of the molding. It is easy to remove by heat treatment, leaving alumina spheres with a hollow structure or a porous structure, which is relatively simple.

[0010] Preferably, in the above preparation method, the alumina precursor described in step 1) is a γ-Al2O3 nanopowder, and the γ-Al2O3 nanopowder is fibrous. Using fibrous γ-Al2O3 nanopowder as the alumina precursor is conducive to forming a continuous pore structure. These pores can provide more adsorption sites and channels, which are conducive to the diffusion and adsorption of carbon dioxide and other substances within the porous alumina spheres.

[0011] Preferably, in the above preparation method, the mixing in step 1) is as follows: first dry-mixing the template and the alumina precursor, then adding 3% to 5.5% water by weight of the template and mixing after uniform mixing, and then forming spheres with a particle size of 2 mm to 5 mm using a rolling ball machine after uniform mixing. Adding a small amount of water to the mixture of the template and the alumina precursor not only promotes adhesion during sphere formation, but also slowly vaporizes during the drying process, leaving microchannels for the spheres. These microchannels serve as volatilization channels for the template during heat treatment, effectively preventing cracking and improving the forming rate.

[0012] Preferably, in the above preparation method, the heat treatment in step 1) comprises drying the spheres and then calcining them at a temperature of 305°C to 310°C. The two components of the composite template selected in the present invention have similar thermal decomposition temperatures. The preferred calcination temperature allows the two components to separate from the spheres at an appropriate rate, thereby ensuring a high molding yield.

[0013] Preferably, in the above preparation method, the drying temperature is 70°C to 80°C. The heating rate of the roasting from room temperature to the roasting temperature is 25°C / h to 30°C / h. The vaporization rate of water is controlled by the drying rate, and microchannels are reserved for the spheres while preventing cracks, thereby increasing the forming rate while ensuring the strength of the spheres as much as possible. The heating rate is controlled during roasting, and the strength of the alumina balls will gradually increase with the increase in temperature. The roasting process should reduce thermal expansion before the alumina balls have sufficient strength. The preferred heating rate can effectively reduce the bursting of the spheres caused by thermal expansion of different materials.

[0014] Preferably, in the above-mentioned preparation method, the aminosilane described in step 2) is N-(2-aminoethyl-3-aminopropyl) trimethoxysilane or 3-aminopropyl trimethoxysilane. After the preferred aminosilane is cured in the alumina ball pores, the selectivity to carbon dioxide adsorption can be better enhanced. More preferably, the aminosilane is N-(2-aminoethyl-3-aminopropyl) trimethoxysilane. N-(2-aminoethyl-3-aminopropyl) trimethoxysilane is not only firmly and stably cured with the alumina ball, but also contains two amino groups of aminoethyl and aminopropyl. After curing, the amino density is higher, and the saturation is larger during the adsorption of carbon dioxide.

[0015] Preferably, in the above preparation method, the solvent in step 2) is methanol, ethanol or dimethylformamide (DMF). More preferably, the solvent is DMF. Ethanol and methanol have good solubility for most aminosilanes and are easy to obtain and handle. DMF has good solubility for aminosilanes and can provide higher solubility and dissolution rate.

[0016] Preferably, in the above preparation method, the impregnation in step 2) comprises immersing the alumina spheres in an aminosilane solution for 18 to 24 hours, wherein the concentration of the aminosilane solution is 50% to 60%. The preferred concentration of the aminosilane solution ensures good fluidity and wettability of the solution while ensuring a sufficient density of amino groups attached to the alumina spheres.

[0017] Preferably, in the above preparation method, the curing treatment in step 2) is performed by thermal curing: the impregnated alumina balls are baked at 50°C to 80°C for 5 to 6 hours. The preferred curing temperature and time can maximize the curing rate while avoiding excessively high temperatures that may cause thermal decomposition of the material or other adverse effects.

[0018] Compared with the prior art, the preparation method of an adsorbent for pressure swing adsorption with a microporous structure of the present invention has the following beneficial effects: the present invention uses alumina balls with a microporous structure as the main body of the adsorbent, and after impregnation and curing with aminosilane, an adsorbent for adsorbing carbon dioxide is obtained. The alumina balls prepared by heat treatment of the present invention have a large specific surface area and a rich pore structure, which can provide more adsorption sites and channels, which is conducive to the diffusion and adsorption of carbon dioxide molecules on the surface of the adsorbent. Alumina is selected as the main body, which has good chemical stability and can maintain high adsorption performance during long-term use under various environmental conditions. The cured amino group has a pair of lone pairs of electrons, which can enhance the interaction between the adsorbent and carbon dioxide and improve the adsorption selectivity.

[0019] When using this adsorbent, other acid gases in the gas to be treated should be removed by other equipment as much as possible before adsorption. DETAILED DESCRIPTION

[0020] The present invention will be described in detail below by way of examples. Unless otherwise specified, all raw materials used are commercially available.

[0021] Example 1

[0022] 1) Prefabricating polystyrene and polyacrylic acid into a composite template in a mass ratio of 38:62, dry-mixing the composite template with fibrous γ-Al2O3 nanopowder in a mass ratio of 35:100, adding 4.5% water by mass of the composite template and mixing, and forming spheres with a particle size of 2 mm to 5 mm using a rolling ball machine after uniform mixing; drying the spheres at 75°C and then calcining them to obtain porous alumina spheres, the calcination temperature being 305°C and the heating rate from room temperature to the calcination temperature being 25°C / h.

[0023] 2) N-(2-aminoethyl-3-aminopropyl)trimethoxysilane was dissolved in DMF to prepare an impregnation solution with a mass concentration of 55%, and the obtained alumina balls were immersed in the impregnation solution for 20 hours. After filtering out the alumina balls, they were baked and cured at 80°C for 5.5 hours.

[0024] Example 2

[0025] 1) Polystyrene and polyacrylic acid are prefabricated into a composite template in a mass ratio of 35:65, the composite template is dry-mixed with fibrous γ-Al2O3 nanopowder in a mass ratio of 33:100, and after uniform mixing, water (3.5% by mass of the composite template) is added and mixed, and after uniform mixing, spheres with a particle size of 2 mm to 5 mm are formed using a rolling ball machine; the spheres are dried at 75°C and then calcined to obtain porous alumina spheres, the calcination temperature being 310°C and the heating rate from room temperature to the calcination temperature being 30°C / h.

[0026] 2) N-(2-aminoethyl-3-aminopropyl)trimethoxysilane was dissolved in DMF to prepare an impregnation solution with a mass concentration of 55%. The obtained alumina balls were immersed in the impregnation solution for 22 hours. The alumina balls were filtered out and then baked and cured at 80°C for 5.5 hours.

[0027] Example 3

[0028] 1) Prefabricating polystyrene and polyacrylic acid into a composite template in a mass ratio of 40:60, dry-mixing the composite template with fibrous γ-Al2O3 nanopowder in a mass ratio of 38:100, adding 4.5% water by mass of the composite template and mixing after uniform mixing, and forming spheres with a particle size of 2 mm to 5 mm using a rolling ball machine after uniform mixing; drying the spheres at 75°C and then calcining them to obtain porous alumina spheres, the calcination temperature being 305°C and the heating rate from room temperature to the calcination temperature being 28.

[0029] 2) N-(2-aminoethyl-3-aminopropyl)trimethoxysilane was dissolved in DMF to prepare an impregnation solution with a mass concentration of 55%, and the obtained alumina balls were immersed in the impregnation solution for 20 hours. After filtering out the alumina balls, they were baked and cured at 80°C for 5.5 hours.

[0030] Example 4

[0031] 1) Polystyrene and polyacrylic acid are prefabricated into a composite template in a mass ratio of 30:70, the composite template is dry-mixed with fibrous γ-Al2O3 nanopowder in a mass ratio of 30:100, and after uniform mixing, water (5.5% by mass of the composite template) is added and mixed, and after uniform mixing, spheres with a particle size of 2 mm are formed using a rolling ball machine; the spheres are dried at 70°C and then calcined to obtain porous alumina spheres, the calcination temperature being 305°C and the heating rate from room temperature to the calcination temperature being 25°C / h.

[0032] 2) N-(2-aminoethyl-3-aminopropyl)trimethoxysilane was dissolved in methanol to prepare an impregnation solution with a mass concentration of 50%, and the obtained alumina balls were immersed in the impregnation solution for 24 hours. After filtering out the alumina balls, they were baked and cured at 50°C for 5 hours.

[0033] Example 5

[0034] 1) Polystyrene and polyacrylic acid are prefabricated into a composite template in a mass ratio of 45:55, the composite template is dry-mixed with fibrous γ-Al2O3 nanopowder in a mass ratio of 40:100, and after uniform mixing, water (3% by mass of the composite template) is added and mixed, and after uniform mixing, spheres with a particle size of 5 mm are formed using a rolling ball machine; the spheres are dried at 80°C and then calcined to obtain porous alumina spheres, the calcination temperature being 310°C and the heating rate from room temperature to the calcination temperature being 30°C / h.

[0035] 2) N-(2-aminoethyl-3-aminopropyl)trimethoxysilane was dissolved in ethanol to prepare an impregnation solution with a mass concentration of 60%, and the obtained alumina balls were immersed in the impregnation solution for 18 hours. The alumina balls were filtered out and then baked and cured at 65°C for 5 hours.

[0036] Example 6

[0037] 1) Dry-mixing polystyrene and fibrous γ-Al2O3 nanopowder in a mass ratio of 35:100, adding 3.5% water by mass of the composite template agent and mixing, and forming spheres with a particle size of 2 mm to 5 mm using a rolling ball machine after mixing, drying the spheres at 75°C and then calcining them at 305°C to obtain porous alumina spheres. The calcination temperature is 305°C, and the heating rate from room temperature to the calcination temperature is 25°C / hh.

[0038] 2) N-(2-aminoethyl-3-aminopropyl)trimethoxysilane was dissolved in DMF to prepare an impregnation solution with a mass concentration of 55%, and the obtained alumina balls were immersed in the impregnation solution for 20 hours. The alumina balls were filtered out and then baked and cured at 80°C for 6 hours.

[0039] Example 7

[0040] 1) Prefabricating polystyrene and polyacrylic acid into a composite template in a mass ratio of 38:62, dry-mixing the composite template with fibrous γ-Al2O3 nanopowder in a mass ratio of 35:100, adding 4.5% water by mass of the composite template and mixing, and forming spheres with a particle size of 2 mm to 5 mm using a rolling ball machine after uniform mixing; drying the spheres at 75°C and then calcining them to obtain porous alumina spheres, the calcination temperature being 305°C and the heating rate from room temperature to the calcination temperature being 25°C / h.

[0041] 2) 3-aminopropyltrimethoxysilane was dissolved in ethanol to prepare an impregnation solution with a mass concentration of 55%, and the obtained alumina balls were immersed in the impregnation solution for 20 hours. The alumina balls were filtered out and then baked and cured at 60° C. for 5 hours.

[0042] Samples (d is 1.6 mm to 2.5 mm) were taken from the molecular sieves prepared in the examples as samples and some performance tests were performed according to GBT 13550-2015.

[0043] CO2 adsorption rate: prepare a mixed gas of CO2 and N2 at a volume ratio of 3:7, and add 1m 3 The mixed gas was passed through an adsorption column having a cross-section of 20 cm×20 cm and a length of 50 cm, which was filled with the adsorbent obtained in Example 1, and the CO2 loss rate was measured.

[0044] The experimental results are shown in Table 1.

[0045] Table 1 Experimental results

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.

Claims

1. A method for preparing a microporous structured pressure swing adsorption adsorbent, characterized in that: The following steps are involved: 1) The template agent and the alumina precursor are mixed in a mass ratio of 30 to 40:100 to form a sphere, and the alumina sphere with a porous structure is obtained by heat treatment; 2) dissolving aminosilane in a solvent, impregnating the solvent with alumina balls, filtering out the alumina balls, and then drying and curing the resulting product.

2. The method for preparing a microporous structured pressure swing adsorption adsorbent according to claim 1, characterized in that: The template agent in step 1) is a composite template agent with a mass ratio of polystyrene to polyacrylic acid of 30-45:55-70.

3. The method for preparing a microporous structured pressure swing adsorption adsorbent according to claim 1, characterized in that: The alumina precursor in step 1) is γ-Al2O3 nanopowder, and the γ-Al2O3 nanopowder is fibrous.

4. The method for preparing a microporous structured pressure swing adsorption adsorbent according to claim 1, characterized in that: The mixing in step 1) is as follows: first dry-mix the template and the alumina precursor, and then add 3% to 5.5% of water by mass of the template and mix them evenly. After mixing evenly, use a ball rolling machine to form spheres with a particle size of 2mm to 5mm.

5. The method for preparing a microporous structured pressure swing adsorption adsorbent according to claim 1, characterized in that: The heat treatment in step 1) is as follows: drying the spheres and then calcining them at a temperature of 305° C. to 310° C.

6. The method for preparing a microporous structured pressure swing adsorption adsorbent according to claim 5, characterized in that: The drying temperature is 70° C. to 80° C. The heating rate of the calcination from room temperature to the calcination temperature is 25° C. / h to 30° C. / h.

7. The method for preparing a microporous structured pressure swing adsorption adsorbent according to claim 1, characterized in that: The aminosilane described in step 2) is N-(2-aminoethyl-3-aminopropyl)trimethoxysilane.

8. The method for preparing a microporous structured pressure swing adsorption adsorbent according to claim 1, characterized in that: The solvent in step 2) is methanol, ethanol or DMF dimethylformamide.

9. The method for preparing a microporous structured pressure swing adsorption adsorbent according to claim 1, characterized in that: The immersion in step 2) is to immerse the alumina balls in an aminosilane solution for 18 to 24 hours, wherein the mass concentration of the aminosilane solution is 50% to 60%.

10. The method for preparing a microporous structured pressure swing adsorption adsorbent according to claim 1, characterized in that: The curing treatment in step 2) adopts a thermal curing method: the impregnated alumina balls are baked at 50° C. to 80° C., and the baking time is controlled to be 5 h to 6 h.

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