Method for preparing L-PEIx solid amine carbon dioxide adsorbent through lignin in-situ modification
By reacting lignin with amination reagent and formaldehyde, L-PEIx solid amine carbon dioxide adsorbent was prepared, which solved the problems of high energy consumption and low selectivity of existing CO2 capture materials, and achieved efficient and economical carbon dioxide capture effect.
Patent Information
- Application Number
- CN202411757839.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-03
- Publication Date
- 2025-03-07
AI Technical Summary
Existing CO2 capture materials have problems such as high energy consumption, low selectivity, production complexity and high cost, making it difficult to achieve efficient and economical carbon dioxide capture.
L-PEIx solid amine carbon dioxide adsorbent was prepared by dissolving lignin in an alkali solution and reacting with amination reagent and formaldehyde. This method has simple steps and low energy consumption. It can effectively modify lignin and improve its capture performance on CO2.
The prepared L-PEIx solid amine adsorbent has high CO2 selectivity, high adsorption capacity and low production cost, and is suitable as an ideal new carbon dioxide adsorption material.
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Figure CN119569981A_ABST
Abstract
Description
Technical field:
[0001] The invention relates to the technical field of carbon dioxide capture adsorbents, and specifically to a method for preparing an L-PEIx (solid amine) carbon dioxide adsorbent by in-situ modification of lignin. Background technology:
[0002] As the global climate change problem becomes increasingly serious, carbon capture, storage and utilization (CCUS) technology has become one of the effective strategies to reduce the concentration of CO2 in the air. At present, common CO2 capture materials include amine solutions, metal oxides, activated carbon, metal organic frameworks (MOFs), zeolites and silica. However, these materials have certain limitations in practical applications, such as the corrosiveness and high regeneration energy consumption of amine solutions, the high energy consumption release of metal oxides, the low selectivity and high preparation energy consumption of activated carbon, and the high cost and preparation complexity of MOFs. Therefore, there is an urgent need to find a new adsorption material with low price, high CO2 capture efficiency and low regeneration energy consumption.
[0003] Solid amine materials have attracted widespread attention due to their advantages such as high CO2 selectivity, high adsorption capacity, high stability and low cost. Selecting a suitable carrier is the basis for synthesizing solid amine materials. The properties, price and synthesis method of the carrier will affect the performance of the final product. Lignin, as the second largest natural resource in the world after cellulose, has the characteristics of large volume, low price and rich chemical structure such as phenolic hydroxyl groups and ether bonds. It is the main by-product of the papermaking industry. Every year, about 50 million tons of lignin waste is generated by the papermaking industry worldwide, and the annual output of natural lignin is as high as 500 million to 3.6 billion tons. Therefore, using lignin as a carrier for synthesizing solid amines can not only realize the resource utilization of waste, but also effectively reduce production costs.
[0004] Although there have been studies on the preparation of aminated lignin-based adsorbents by modifying lignin through the Mannich reaction, most of these studies use purified lignin as raw material and are mainly applied to the removal of pollutants in water bodies rather than CO2 capture. There are few reports on the direct modification of raw lignin produced by the paper industry and its application in CO2 capture. Summary of the invention:
[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to design and develop a method for preparing L-PEIx solid amine carbon dioxide adsorbent by in-situ modification of lignin. The method has simple steps and low energy consumption, and the prepared adsorbent has excellent CO2 capture performance. To achieve the above purpose, the present invention provides the following technical solutions:
[0006] In one aspect, the present invention provides a method for preparing a L-PEIx solid amine carbon dioxide adsorbent by in-situ modification of lignin, comprising the following steps:
[0007] (1) Dissolve lignin in an alkaline solution to obtain a lignin alkaline solution
[0008] (2) adding an amination reagent and a formaldehyde solution to the lignin alkaline solution obtained in step (1) in sequence to allow for sufficient reaction;
[0009] (3) Adding hydrochloric acid to the solution obtained by the reaction in step (2) to adjust the pH, and then post-treating to obtain the amine-functionalized adsorbent L-PEI X .
[0010] Furthermore, in step (1), the base is one of sodium hydroxide or potassium hydroxide, preferably sodium hydroxide, with a concentration of 0.01M.
[0011] Furthermore, the concentration of the lignin alkali solution is 10-30 mg / mL, preferably 15-25 mg / mL, and more preferably 20 mg / mL.
[0012] Furthermore, the lignin solution in step (1) is prepared by dissolving lignin in a 0.01 M NaOH solution.
[0013] Furthermore, step (1) is stirred at room temperature for 30-60 minutes to prepare a lignin alkaline solution.
[0014] Furthermore, in step (2), the amination reagent is one of urea, acrylamide, tetramethylguanidine, ethanolamine, diethanolamine, diethylenetriamine, dimethylamine or polyethyleneimine, preferably polyethyleneimine.
[0015] Furthermore, in step (2), the concentration of the amination agent solution is 15-35 wt %, preferably 20-30 wt %, and more preferably 25 wt %.
[0016] In step (2), the volume ratio of lignin alkali solution: amination reagent solution: formaldehyde solution is 25:(1-4):1, for example, 25:1:1, 25:1.5:1, 25:2:1, 25:3:1, 25:4:1.
[0017] Furthermore, the concentration of the formaldehyde solution in step (2) is 37%-40%, for example, 37%, 38%, 39%, 40%.
[0018] Furthermore, in step (2), after adding the amination reagent, stirring is carried out at room temperature for 30-60 minutes, and after adding the formaldehyde solution, stirring is continued at 60° C. for 5-8 hours.
[0019] Furthermore, the concentration of the hydrochloric acid solution in step (3) is 0.5-2M, preferably 1M.
[0020] Furthermore, in step (3), hydrochloric acid is used to adjust the pH to 3-4 to produce a brown precipitate.
[0021] Furthermore, the post-treatment step in step (3) includes transferring the reaction solution to filter paper after sufficient shaking and filtering, washing the precipitate with deionized water until it is neutral, and finally collecting the product and vacuum drying it at 60° C. for 48-72 hours.
[0022] Furthermore, the present invention provides a method for preparing an L-PEIx solid amine carbon dioxide adsorbent by in-situ modification of lignin, comprising the following steps:
[0023] (1) Dissolve lignin in an alkaline solution to obtain a 10-30 mg / mL lignin alkaline solution
[0024] (2) adding a 15-35wt% aminating agent and a 37%-40% formaldehyde solution to the lignin alkali solution obtained in step (1); wherein the volume ratio of the lignin alkali solution: the aminating agent solution: the formaldehyde solution is 25:(1-4):1, and the reaction is fully carried out;
[0025] (3) Add hydrochloric acid to the solution obtained in step (2) to adjust the pH to 3-4 to produce a brown precipitate. After being fully shaken, the reaction solution is transferred to filter paper and filtered. The precipitate is washed with deionized water until it is neutral. Finally, the product is collected and vacuum dried at 60° C. for 48-72 hours to obtain an amine-functionalized adsorbent L-PEI. X .
[0026] Beneficial technical effects:
[0027] 1. The method provided by the present invention for preparing L-PEIx solid amine carbon dioxide adsorbent by in-situ modification of lignin has a wide source of raw materials, a simple preparation process, low energy consumption and good carbon dioxide capture effect.
[0028] 2. The L-PEIx solid amine carbon dioxide adsorbent prepared by the present invention has high carbon dioxide adsorption capacity and selectivity, and is an ideal new type of carbon dioxide adsorption material. Description of the drawings:
[0029] Figure 1 This is a schematic diagram of the test process of the CO2 adsorption and desorption test method;
[0030] Figure 2 The XPS spectrum of L-PEI4 solid amine and lignin prepared in Test Example 1;
[0031] Figure 3 CO2 adsorption capacity curve of polyethyleneimine-modified lignin-based adsorbent under wet conditions, 25°C, 10vt% CO2 / Ar and 1 bar. Specific implementation method:
[0032] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention in any way. Unless otherwise specified, the methods, reagents and equipment used in the present invention are conventional methods, reagents and equipment in the art, and the reagents and equipment can be obtained from commercial sources.
[0033] Example 1
[0034] Weigh 2g of lignin in a 250mL round-bottom flask, add 100mL of 0.01M NaOH solution, stir at room temperature for 30min to fully dissolve the lignin and partially remove impurities. Add 4mL of 25wt% polyethyleneimine solution and continue stirring at room temperature for 30min to allow polyethyleneimine to fully contact lignin. Add 4mL of 38% formaldehyde solution and stir continuously at 60°C for 5h to graft polyethyleneimine to the surface of lignin through the Mannich reaction to form the precursor of L-PEIx solid amine adsorbent. After the reaction is completed, wait for the solution to cool to room temperature and adjust the pH to 3-4 with 1M HCl solution. At this time, a brown precipitate will be produced, which is the L-PEI4 solid amine adsorbent. Wash the precipitate with deionized water to neutrality to remove unreacted raw materials and impurities. Dry at 60°C in a vacuum drying oven for 48h to obtain the final L-PEI4 solid amine adsorbent.
[0035] Example 2
[0036] Weigh 2g of lignin in a 250mL round-bottom flask, add 100mL of 0.01M NaOH solution, stir at room temperature for 30min to fully dissolve the lignin and partially remove impurities. Add 6mL of 25wt% polyethyleneimine solution and continue stirring at room temperature for 30min to allow polyethyleneimine to fully contact lignin. Add 4mL of 38% formaldehyde solution and stir continuously at 60°C for 5h to graft polyethyleneimine to the surface of lignin through the Mannich reaction to form the precursor of L-PEIx solid amine adsorbent. After the reaction is completed, wait for the solution to cool to room temperature and adjust the pH to 3-4 with 1M HCl solution. At this time, a brown precipitate will be produced, which is the L-PEI6 solid amine adsorbent. Wash the precipitate with deionized water to neutrality to remove unreacted raw materials and impurities. Dry at 60°C in a vacuum drying oven for 48h to obtain the final L-PEI6 solid amine adsorbent.
[0037] Example 3
[0038] Weigh 2g of lignin in a 250mL round-bottom flask, add 100mL of 0.01M NaOH solution, stir at room temperature for 30min to fully dissolve the lignin and partially remove impurities. Add 8mL of 25wt% polyethyleneimine solution and continue stirring at room temperature for 30min to allow polyethyleneimine to fully contact lignin. Add 4mL of 38% formaldehyde solution and stir continuously at 60°C for 5h to graft polyethyleneimine to the surface of lignin through the Mannich reaction to form the precursor of the L-PEIx solid amine adsorbent. After the reaction is completed, wait for the solution to cool to room temperature and adjust the pH to 3-4 with 1M HCl solution. At this time, a brown precipitate will be produced, which is the L-PEI8 solid amine adsorbent. Wash the precipitate with deionized water to neutrality to remove unreacted raw materials and impurities. Dry at 60°C in a vacuum drying oven for 48h to obtain the final L-PEI8 solid amine adsorbent.
[0039] Test Example 1: XPS Spectrum and Elemental Analysis
[0040] The lignin and the L-PEIx adsorbents prepared in Examples 1-3 were subjected to XPS analysis, and the results are shown in Tables 1 and Figure 2 shown.
[0041] Experimental results and analysis:
[0042] Table 1: Analysis of products and lignin elements in Examples 1-3
[0043]
[0044] The results of XPS total spectrum and elemental analysis showed that the nitrogen content in the L-PEIx adsorbent increased significantly, indicating that polyethyleneimine had been successfully grafted onto the lignin surface.
[0045] Test Example 2: CO2 adsorption and desorption test method
[0046] First, use 50mL / min of N2 to remove the residual air in the pipeline to ensure the purity of the test environment. Then introduce 10% CO2 / Ar mixed gas (50mL / min) into pipeline No. 2 until the CO2 equilibrium baseline is reached as the initial state of the test. Switch the 10% CO2 / Ar mixed gas to enter the quartz tube containing the adsorbent at a flow rate of 50mL / min, and observe the changes in the CO2 concentration curve through a computer. At the beginning, the CO2 concentration will drop rapidly. As the adsorption proceeds, the concentration gradually increases until the CO2 concentration returns to the baseline position after adsorption saturation. By calculating the change in CO2 concentration before and after adsorption, the CO2 adsorption capacity can be obtained. The test flow chart is as follows Figure 1 shown.
[0047] The calculation method is shown in formula (1):
[0048]
[0049] in (mmol / min) is the CO2 molar flow rate at the feed port before adsorption, (mmol / min) is the molar flow rate of CO2 at the outlet after adsorption, (mmol / min) is the molar flow rate of CO2 at the outlet of the blank group, T s and t s (min) are the duration of CO2 adsorption by the adsorbent and the duration of N2 discharge by the blank group, respectively, and M (g) is the mass of the adsorbent.
[0050] The solid amine adsorbent prepared in Examples 1-3 was tested for CO2 adsorption and desorption. Figure 2 As shown, the results show that with the increase in the amount of polyethyleneimine, the CO2 adsorption capacity of the adsorbent first increases and then tends to stabilize. Among them, L-PEI8 prepared in Example 3 shows the highest CO2 adsorption capacity.
[0051] Conclusion: The present invention proposes a method for preparing L-PEIx solid amine carbon dioxide adsorbent by in-situ modification of lignin, which has the advantages of low raw material price, simple preparation process, low energy consumption and good carbon dioxide capture effect. The prepared L-PEIx solid amine adsorbent has the characteristics of high CO2 selectivity, high adsorption capacity and high stability, and has broad application prospects in the field of carbon capture.
[0052] The applicant declares that the present invention illustrates the detailed method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.
Claims
1. A method for preparing L-PEIx solid amine carbon dioxide adsorbent by in-situ modification of lignin, characterized in that: The following steps are involved: (1) dissolving lignin in an alkaline solution to obtain a lignin alkaline solution; (2) adding an aminating agent and a formaldehyde aqueous solution to the lignin alkaline solution obtained in step (1) in sequence to allow for sufficient reaction; (3) Adding hydrochloric acid to the solution obtained by the reaction in step (2) to adjust the pH, and post-treating to obtain the amine-functionalized adsorbent L-PEI X .
2. The method according to claim 1, characterized in that The alkali in step (1) is one of sodium hydroxide or potassium hydroxide, and the concentration is 0.01M. Step (1) is stirred at room temperature for 30-60 minutes to prepare a lignin alkali solution with a concentration of 10-30 mg / mL.
3. The method according to claim 1, characterized in that In step (2), the aminating agent is one of urea, acrylamide, tetramethylguanidine, ethanolamine, diethanolamine, diethylenetriamine, dimethylamine or polyethyleneimine, and the concentration of the aminating agent is 15-35wt%.
4. The method according to claim 1, characterized in that: The concentration of the formaldehyde solution in step (2) is 37%-40%.
5. The method according to claim 1, characterized in that In step (2), after adding the amination reagent, stir at room temperature for 30-60 minutes, and after adding the formaldehyde solution, stir continuously at 60° C. for 5-8 hours.
6. The method according to claim 1, characterized in that In step (2), the volume ratio of lignin alkali solution: amination reagent solution: formaldehyde solution is 25:(1-4):
1.
7. The method according to claim 1, characterized in that In step (3), the concentration of hydrochloric acid is 0.5-2M.
8. The method according to claim 1, characterized in that In step (3), hydrochloric acid is used to adjust the pH to 3-4 to produce a brown precipitate.
9. The method according to claim 1, characterized in that: The post-treatment step in step (3) includes transferring the reaction solution to filter paper after thorough shaking and filtering, washing the precipitate with deionized water until it is neutral, and finally collecting the product and vacuum drying it at 60° C. for 48-72 hours.
10. A method for preparing L-PEIx solid amine carbon dioxide adsorbent by in-situ modification of lignin, comprising the following steps: (1) Dissolve lignin in an alkaline solution to obtain a 10-30 mg / mL lignin alkaline solution (2) adding a 15-35wt% aminating agent and a 37%-40% formaldehyde solution to the lignin alkali solution obtained in step (1); wherein the volume ratio of the lignin alkali solution: the aminating agent solution: the formaldehyde solution is 25:(1-4):1, and the reaction is fully carried out; (3) Add hydrochloric acid to the solution obtained in step (2) to adjust the pH to 3-4 to produce a brown precipitate. After being fully shaken, the reaction solution is transferred to filter paper and filtered. The precipitate is washed with deionized water until it is neutral. Finally, the product is collected and vacuum dried at 60° C. for 48-72 hours to obtain an amine-functionalized adsorbent L-PEI. X .