A molecular sieve composite material, its preparation method and application

Abstract

This invention discloses a molecular sieve composite material, its preparation method, and its application in carbon dioxide adsorption. The molecular sieve composite material comprises a molecular sieve and polyethyleneimine, wherein the molecular sieve is selected from at least one of SCM-1, SCM-2, and SCM-6. Based on the weight of the composite material, the content of polyethyleneimine is 20%–60%, and the content of the molecular sieve is 40%–80%. The composite material of this invention can support a high content of polyethyleneimine while remaining solid, making it easy to handle, mold, and use, and exhibiting excellent performance in the selective adsorption of carbon dioxide.

Description

Technical Field

[0001] This invention relates to a molecular sieve composite material, its preparation method and application, belonging to the field of carbon dioxide gas adsorption, separation and purification. Background Technology

[0002] Economic and social development has led to a continuous increase in energy demand in various countries. While carbon reduction and emission reduction efforts are being implemented, the current complex situation necessitates ensuring a secure and stable energy supply to maintain economic growth. Therefore, coal and oil are expected to remain the main sources of energy consumption for some time to come, making the development of carbon reduction technologies an urgent need. Carbon dioxide capture, utilization, and storage (CCUS) has attracted increasing attention from researchers and industry professionals as one solution. Solid adsorption separation, with its advantages of low regeneration energy consumption, easy equipment setup, and moderate output, is a promising technology for CCUS.

[0003] Researchers have made many effective attempts to prepare solid adsorbents by loading polyethyleneimine (PEI) onto porous supports for the selective adsorption of carbon dioxide. For example, mesoporous silica materials SBA-15 or MCM-41 modified with polyethyleneimine (Energy & Fuels, 2002, 16, 1463; Microporous and Mesoporous Materials, 2008, 113, 31; Journal of the American Chemical Society, 2009, 131, 5777) can achieve excellent carbon dioxide adsorption capacity at 75℃. However, this performance is not ideal for the actual flue gas capture temperature. At 40-60℃, the advantages of the adsorbent cannot be brought into play, the loaded amine groups are difficult to fully disperse in the mesoporous channels, the specific surface area of ​​the material cannot be fully utilized, and the expected effect cannot be achieved. Lamellar morphology and layered structure have mitigated this problem to some extent. CN104437418B discloses a layered material loaded with polyethyleneimine and its preparation method. A one-pot method can be used to prepare Kenyaite layered silicate materials loaded with polyethyleneimine under conditions of silicon source, heteroatom source, and alkaline substances. However, due to limitations in the synthesis conditions of layered materials, the loading capacity of polyethyleneimine is not high, and the molecular weight is not very large, resulting in limited improvement in carbon dioxide adsorption. Therefore, developing an adsorbent with strong selective carbon dioxide adsorption capacity is of significant importance. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a molecular sieve composite material, its preparation method, and its applications. The composite material of this invention can support a high content of polyethyleneimine while remaining solid, making it easy to handle, mold, and use, and exhibiting excellent performance in the selective adsorption of carbon dioxide.

[0005] Conventional silicon-based materials (such as silica, SBA-15, MCM-41, and Kenyaite layered materials) struggle to support high concentrations of organic amines, and even with high specific surface areas, they often fail to exhibit adsorption capacity advantages, resulting in sticky, solid products that are difficult to handle, mold, and use. The inventors discovered that SCM-1, SCM-2, and / or SCM-6 molecular sieves, with their layered structure and nanosheet morphology, facilitate the dispersion and exposure of polyethyleneimine, allowing them to support very high concentrations of polyethyleneimine while remaining solid. This not only makes them easy to handle, mold, and use, but also demonstrates excellent performance in the selective adsorption of carbon dioxide.

[0006] The first aspect of the present invention provides a molecular sieve composite material, comprising a molecular sieve and polyethyleneimine, wherein the molecular sieve is selected from at least one of SCM-1, SCM-2, and SCM-6, and the content of polyethyleneimine is 20% to 60% and the content of molecular sieve is 40% to 80% based on the weight of the composite material.

[0007] Furthermore, based on the weight of the composite material, the content of polyethyleneimine is 20% to 60%, preferably 45% to 55%, and the content of molecular sieve is 40% to 80%, preferably 45% to 55%.

[0008] Furthermore, the molecule is screened from at least one of SCM-1, SCM-2, and SCM-6, preferably at least one of SCM-1 and SCM-2. Specifically, SCM-1 and SCM-2 are described in CN104511271B, and SCM-6 is described in CN105217651B.

[0009] Furthermore, the specific surface area of ​​the molecular sieve is 30 to 1000 square meters per gram, preferably 150 to 700 square meters per gram.

[0010] Furthermore, the average molecular weight of the polyethyleneimine is 300 to 100,000, preferably 500 to 10,000.

[0011] Furthermore, the molecular sieve composite material uses a molecular sieve as a carrier and polyethyleneimine is loaded onto the carrier.

[0012] A second aspect of the present invention provides a method for preparing the above-mentioned molecular sieve composite material, comprising:

[0013] (1) Dissolve polyethyleneimine in a solvent to prepare an impregnation solution, and then add molecular sieve material for impregnation;

[0014] (2) After impregnation, the product is dried to obtain molecular sieve composite material.

[0015] Furthermore, the molecular sieve is selected from one or more of SCM-1, SCM-2, and SCM-6. The molecular sieve material exists in forms including, but not limited to, the raw powder obtained by direct synthesis, or the product after one-step calcination to remove the template agent.

[0016] Furthermore, the average molecular weight of the polyethyleneimine is 300 to 100,000, preferably 500 to 10,000.

[0017] Furthermore, the solvent used in the impregnation solution is selected from one or more of methanol, ethanol, isopropanol, butanol, cyclohexanol, acetone, and water, preferably at least one of methanol, ethanol, and water.

[0018] Furthermore, the impregnation solution contains polyethyleneimine at a mass concentration of 0.05% to 30%, preferably 1% to 25%.

[0019] Furthermore, in step (1), the immersion temperature can be 1 to 50°C, preferably 15 to 40°C, and more preferably 20 to 30°C.

[0020] Furthermore, in step (1), the soaking time can preferably be 3 to 120 hours, more preferably 6 to 72 hours.

[0021] Furthermore, after the impregnation reaction is completed, the drying method can be to obtain the corresponding product by vacuum heating drying, the temperature can be 40-150°C, more preferably 50-130°C, the drying time can be 2-30h, preferably 3-24h, and the solvent extracted by vacuum can be recycled and reused as the solvent of the impregnation liquid of the present invention.

[0022] A third aspect of the present invention provides the application of the above-described composite material in carbon dioxide adsorption.

[0023] Furthermore, the application includes: contacting a carbon dioxide-containing gas with the composite material for adsorption to obtain purified gas.

[0024] Furthermore, in the gas containing carbon dioxide, the volume content of carbon dioxide is 0.04% to 60%, and the other gases include at least one of nitrogen, methane, hydrogen, carbon monoxide, etc.

[0025] Furthermore, the adsorption conditions are as follows: temperature 10–80°C, preferably 40–70°C; pressure 0.01–100 kPa; time 1–60 min; and volume hourly space velocity (VHSV) 5–2400 h⁻¹. -1 .

[0026] Furthermore, the molecular sieve composite material of the present invention is used for selective adsorption of carbon dioxide gas and can be regenerated through multiple cycles. The regeneration conditions are as follows: under no heating or heating conditions, the heating temperature is 40-150°C, preferably 60-130°C, and at least one of nitrogen gas, carbon dioxide gas, and water vapor is used, or the tail gas after adsorption separation and purification is used to purge the composite material to achieve regeneration, or regeneration is achieved by depressurization degassing.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] The molecular sieve composite material of the present invention is made by combining at least one of SCM-1, SCM-2, and SCM-6 molecular sieves with polyethyleneimine, which can significantly increase the loading of polyethyleneimine. When used as a carbon dioxide adsorbent, it can significantly increase the carbon dioxide adsorption capacity and has excellent carbon dioxide adsorption and capture capabilities. Attached Figure Description

[0029] Figure 1 The carbon dioxide gas adsorption-desorption isotherms of SCM-1 molecular sieve and the obtained molecular sieve composite material in Example 1 at 40°C are shown.

[0030] Figure 2 The carbon dioxide gas adsorption-desorption isotherms at 40°C are shown for SCM-2 molecular sieve and the resulting molecular sieve composite material in Examples 5 and 8, and SBA-15 and the resulting molecular sieve composite material in Comparative Example 3.

[0031] Figure 3 The image shows a scanning electron microscope (SEM) image of the molecular sieve composite material obtained in Example 2.

[0032] Figure 4 The image shows a scanning electron microscope (SEM) image of the molecular sieve composite material obtained in Example 9.

[0033] Figure 5 Thermogravimetric analysis curve of the molecular sieve composite material obtained in Example 2 under air atmosphere;

[0034] Figure 6 Thermogravimetric analysis curve of the molecular sieve composite material obtained in Example 1 under air atmosphere;

[0035] Figure 7 The graph shows a comparison of the CO2 adsorption effects of the molecular sieve composite material obtained in this invention with other materials loaded with different amounts of PEI. Detailed Implementation

[0036] According to the present invention, the aforementioned molecular sieve composite material can be used in any physical form, such as powder, granules, or molded form (e.g., strips, cloverleaf shapes, etc.). These physical forms can be obtained in any manner conventionally known in the art, without particular limitation.

[0037] In the context of this specification, including in the following examples and comparative examples, the scanning electron microscope (SEM) used for molecular sieves and their composites is a model S-4800II field emission scanning electron microscope.

[0038] In the context of this specification, including in the following examples and comparative examples, the thermogravimetric analysis instrument used for molecular sieves and their composites is a TA Instrument SDT Q600 from the USA, and the test was conducted in an air atmosphere at a rate of 100 mL / min.

[0039] In the context of this specification, including in the following examples and comparative examples, the specific surface area and isoporous structure characterization of the molecular sieves and their composites were determined by the nitrogen physical adsorption-desorption method (BET method): the nitrogen adsorption-desorption isotherm of the molecular sieves and their composites at 77 K was measured using an adsorption analyzer (Microtrac BELSORP max II adsorption analyzer), and then calculated using the BET equation and t-plot equation; the carbon dioxide adsorption capacity of the molecular sieves and their composites was characterized by the carbon dioxide gas adsorption-desorption isotherm: measured using the volumetric method, the carbon dioxide adsorption-desorption isotherm of the molecular sieves and their composites at 0–40 °C was measured using an adsorption analyzer. The experimental conditions for the molecular sieves and their composites were: measurement temperature -169 °C (i.e., 77 K, the boiling point of liquid nitrogen for testing nitrogen adsorption-desorption using the BET method) or 0–60 °C (accurate adjustment can be achieved using water bath circulation temperature control), and the molecular sieve composites were pretreated in vacuum at 100–150 °C for 4–6 hours before measurement.

[0040] The present invention will be further described in detail below with reference to the embodiments, but the present invention is not limited to these embodiments.

[0041] Example 1

[0042] 1.00 g of polyethyleneimine (purity 99 wt%, average molecular weight 600) was dissolved in 8 g of anhydrous methanol and stirred until homogeneous. Then, 1.00 g of calcined SCM-1 molecular sieve powder (preparation method as in Example I-1 of CN104511271B, specific surface area 524 m²) was added. 2(g), stir to fully disperse and continue stirring in air at 25°C for 24 hours. After completion, place in a vacuum drying oven at 50°C and keep under vacuum for 6 hours to obtain the molecular sieve composite material. The solvent extracted under vacuum can be recycled and reused as the solvent for the impregnation solution of this invention.

[0043] Example 2

[0044] 0.4286 g of polyethyleneimine (99 wt% purity, average molecular weight 600) was dissolved in 5 g of anhydrous methanol and stirred until homogeneous. Then, 1.00 g of calcined SCM-1 molecular sieve powder (same as in Example 1) was added, and the mixture was stirred until completely dispersed and continuously stirred in air at 25–30°C for 36 hours. After completion, the mixture was placed in a vacuum drying oven at 55°C and kept under vacuum for 8 hours to obtain the molecular sieve composite material. The solvent extracted under vacuum can be recovered and reused as the solvent for the impregnation solution of this invention.

[0045] Example 3

[0046] 0.6667 g of polyethyleneimine (99 wt% purity, average molecular weight 600) was dissolved in 4 g of anhydrous ethanol and stirred until homogeneous. Then, 1.00 g of raw SCM-2 molecular sieve powder (uncalcined, prepared according to the same method as Example II-2 of CN104511271B, with a specific surface area of ​​533 m²) was added. 2 (g), stir to fully disperse and continue stirring in air at 20°C for 48 hours. After completion, place in a vacuum drying oven at 50°C for 8 hours with ventilation to obtain the molecular sieve composite material. The solvent extracted by vacuum can be recycled and reused as the solvent of the impregnation solution of this invention.

[0047] Example 4

[0048] 0.25 g of polyethyleneimine (purity 99 wt%, average molecular weight 1800) was dissolved in 5 g of anhydrous isopropanol and stirred until homogeneous. Then, 1.00 g of calcined SCM-6 molecular sieve powder (preparation method as in Example 1 of CN105217651B, specific surface area 394 m²) was added. 2 (g), stir to fully disperse and continue stirring in air at 30-35°C for 12 hours. After completion, place in a vacuum drying oven at 50°C and keep under vacuum for 6 hours to obtain the molecular sieve composite material. The solvent extracted under vacuum can be recovered and reused as the solvent of the impregnation solution of this invention.

[0049] Example 5

[0050] 0.25 g of polyethyleneimine (99 wt% purity, average molecular weight 600) was dissolved in a mixed solvent of 3 g methanol and 2 g ethanol, and stirred until homogeneous. Then, 1.00 g of SCM-2 molecular sieve powder (same as in Example 3) was added, and the mixture was stirred until completely dispersed and continuously stirred in air at 25–30°C for 24 hours. After completion, the mixture was placed in a vacuum drying oven at 60°C and kept under vacuum for 9 hours to obtain the molecular sieve composite material. The mixed solvent extracted under vacuum can be recycled and reused as the solvent for the impregnation solution of this invention.

[0051] Example 6

[0052] 2.00 g of polyethyleneimine (99 wt% purity, average molecular weight 10,000) was dissolved in 13 g of methanol and stirred until homogeneous. Then, 2.00 g of calcined SCM-1 molecular sieve powder (same as in Example 1) was added, and the mixture was stirred until completely dispersed and continuously stirred in air at 25–30 °C for 48 hours. After completion, the mixture was placed in a vacuum drying oven at 55 °C and kept under vacuum for 10 hours to obtain the molecular sieve composite material. The solvent extracted under vacuum can be recovered and reused as the solvent for the impregnation solution of this invention.

[0053] Example 7

[0054] Dissolve 8.00 g of a 25% aqueous solution of polyethyleneimine (average molecular weight 3000) in 8 g of ethanol, and stir until homogeneous. Then add 2.00 g of SCM-6 molecular sieve powder (uncalcined, prepared according to the same method as Example 1 in CN105217651B), stir until completely dispersed, and continue stirring in air at 25-30°C for 60 hours. After completion, place in a vacuum drying oven at 60°C for 18 hours with ventilation to obtain the molecular sieve composite material. The solvent extracted under vacuum can be recovered and reused as the solvent for the impregnation solution of this invention.

[0055] Example 8

[0056] 1.00 g of polyethyleneimine (99 wt% purity, average molecular weight 1800) was dissolved in a mixed solvent of 3 g methanol and 2 g ethanol, and stirred until homogeneous. Then, 1.00 g of SCM-2 molecular sieve powder (same as in Example 3) was added, and stirred until completely dispersed. The mixture was then continuously stirred in air at 25–30°C for 24 hours. After completion, the mixture was placed in a vacuum drying oven at 60°C and kept under vacuum for 12 hours to obtain the molecular sieve composite material. The mixed solvent extracted under vacuum can be recycled and reused as the solvent for the impregnation solution of this invention.

[0057] Example 9

[0058] 1.50 g of polyethyleneimine (99 wt% purity, average molecular weight 1200) was dissolved in a mixed solvent of 4 g methanol and 2 g isopropanol, and stirred until homogeneous. Then, 1.00 g of calcined SCM-1 molecular sieve powder (same as in Example 1) was added, and stirred until completely dispersed. The mixture was then continuously stirred in air at 25°C for 24 hours. After completion, the mixture was placed in a vacuum drying oven at 60°C and kept under vacuum for 12 hours to obtain the molecular sieve composite material. The mixed solvent extracted under vacuum can be recycled and reused as the solvent for the impregnation solution of this invention.

[0059] Comparative Example 1

[0060] The carrier used for impregnation is 1.00 gram of 100-200 mesh porous silica (specific surface area of ​​337 m²). 2 / g), the rest is the same as in Example 1.

[0061] Comparative Example 2

[0062] The carrier used for impregnation is 1.00 gram of 200-300 mesh porous silica (specific surface area of ​​363 m²). 2 / g), the rest is the same as in Example 2.

[0063] Comparative Example 3

[0064] The carrier used for impregnation is 1.00 g of SBA-15 mesoporous silicon material (specific surface area of ​​767 m²). 2 / g), the rest is the same as in Example 1.

[0065] Comparative Example 4

[0066] 0.6667 g of polyethyleneimine (99 wt% purity, average molecular weight 600) was dissolved in 5 g of anhydrous methanol and stirred until homogeneous. Then, 1.00 g of calcined MCM-22 molecular sieve powder (specific surface area 430 m²) was added. 2 (g), stir to ensure complete dispersion and continue stirring in air at 25-30°C for 36 hours. After completion, place in a vacuum drying oven at 55°C for 8 hours with ventilation to obtain the molecular sieve composite material. The solvent extracted under vacuum can be recycled and reused as the solvent for the impregnation solution of this invention.

[0067] Comparative Example 5

[0068] 1.00 g of polyethyleneimine (99 wt% purity, average molecular weight 1800) was dissolved in a mixed solvent of 3 g methanol and 2 g ethanol, and stirred until homogeneous. Then, 1.00 g of raw MCM-22 molecular sieve powder (uncalcined, specific surface area 386 m²) was added. 2(g), stir to fully disperse and continue stirring in air at 25-30°C for 24 hours. After completion, place in a vacuum drying oven at 60°C and keep under vacuum for 12 hours to obtain the molecular sieve composite material. The solvent extracted under vacuum can be recovered and reused as the solvent for the impregnation solution of this invention.

[0069] Table 1. Adsorption performance results of Examples 1-9 and Comparative Examples 1-5

[0070]

[0071] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A molecular sieve composite material, comprising a molecular sieve and polyethyleneimine, wherein the molecular sieve is selected from at least one of SCM-1, SCM-2, and SCM-6, and the content of polyethyleneimine is 20% to 60% and the content of molecular sieve is 40% to 80% based on the weight of the composite material; the specific surface area of ​​the molecular sieve is 150 to 1000 square meters per gram; and the average molecular weight of the polyethyleneimine is 300 to 100,000.

2. The molecular sieve composite material according to claim 1, characterized in that, Based on the weight of the composite material, the content of polyethyleneimine is 45%~55%, and the content of molecular sieve is 45%~55%.

3. The molecular sieve composite material according to claim 1, characterized in that, The molecular sieve has a specific surface area of ​​150-700 m² / g; and / or the polyethyleneimine has an average molecular weight of 500-10000.

4. A method for preparing the molecular sieve composite material according to any one of claims 1-3, comprising: (1) Dissolve polyethyleneimine in a solvent to prepare an impregnation solution, and then add molecular sieve material for impregnation; (2) After impregnation, the product is dried to obtain molecular sieve composite material.

5. The preparation method according to claim 4, characterized in that, The solvent used in the impregnation solution is selected from one or more of methanol, ethanol, isopropanol, butanol, cyclohexanol, acetone, and water; and / or, the mass concentration of polyethyleneimine in the impregnation solution is 0.05% to 30%.

6. The preparation method according to claim 5, characterized in that, The impregnation solution is provided by at least one of methanol, ethanol and water; and / or, the impregnation solution contains 1% to 25% by mass of polyethyleneimine.

7. The preparation method according to claim 4, characterized in that, In step (1), the immersion temperature is 1~50 °C; and / or the immersion time is 3~120 hours.

8. The preparation method according to claim 7, characterized in that, In step (1), the immersion temperature is 15~40°C; and / or the immersion time is 6~72 hours.

9. The preparation method according to claim 8, characterized in that, In step (1), the immersion temperature is 20~30°C.

10. The preparation method according to claim 4, characterized in that, In step (2), the drying temperature is 40~150 °C and the drying time is 2~30h.

11. The preparation method according to claim 10, characterized in that, In step (2), the drying temperature is 50~130 °C and the drying time is 3~24 h.

12. The application of the molecular sieve composite material according to any one of claims 1-3 in carbon dioxide adsorption.

13. The application according to claim 12, characterized in that, The application includes: contacting carbon dioxide-containing gas with the molecular sieve composite material for adsorption to obtain purified gas.

14. The application according to claim 13, characterized in that, The carbon dioxide-containing gas has a volume content of 0.04% to 60%, and the other gases include at least one of nitrogen, methane, hydrogen, and carbon monoxide.

15. The application according to claim 13, characterized in that, The adsorption conditions are as follows: temperature 10–80 °C, pressure 0.01–100 kPa, time 1–60 min, and volumetric hourly space velocity (VHSV) 5–2400 h⁻¹. -1 .

16. The application according to claim 15, characterized in that, The adsorption conditions are as follows: temperature 40~80 °C.

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