Preparation method for and use of amino-functionalized adsorbent material with highly dispersed active sites

Abstract

Disclosed in the present invention are a preparation method for and the use of an amino-functionalized adsorbent material with highly dispersed active sites. The preparation method comprises: loading a graphene aerogel into a tubular furnace, and subjecting same to thermal reduction treatment; loading a thermally reduced sample into a plasma vapor deposition tube, and under vacuum conditions, subjecting the sample to plasma treatment in different atmospheres, so as to prepare a carrier; and drying the carrier overnight, placing a polyamino organic amine and the carrier into a reaction kettle, heating same in a blast oven, then taking out a reaction product, removing the organic amine attached to the surface thereof, soaking same in ethanol, and drying same in the blast oven overnight, so as to obtain the material. In the amino-functionalized adsorbent material of the present invention, a large number of point defects are manufactured on a carbon material by means of thermal reduction and plasma treatment, additional proton acceptors are introduced, and different organic amines are grafted. By means of the preparation method provided by the present invention, the amino-functionalized adsorbent material, in which the loading amount of amino groups can be flexibly regulated and controlled to achieve high dispersion of amino molecules and the proton transfer can be enhanced to improve the adsorption performance, can be prepared.

Description

Preparation method and application of an amine-functionalized adsorption material with highly dispersed active sites Technical Field

[0001] The present invention belongs to the field of functional material preparation, and in particular relates to a preparation method and application of an amino-functional adsorption material with highly dispersed active sites. Background Art

[0002] In recent years, the dual carbon goals have attracted widespread attention from all over the world, and "carbon peak" and "carbon neutrality" have become hot words on the Internet. The reason for this phenomenon is that people emit large amounts of carbon dioxide, causing global warming, sea level rise, ozone layer depletion, ocean acidification, unpredictable weather conditions and other series of disasters, which endanger people's lives. Therefore, controlling carbon dioxide emissions and capturing carbon dioxide have become urgent matters.

[0003] Post-combustion carbon dioxide capture technology is easier to implement in practical applications, and adsorption is the post-combustion carbon dioxide treatment technology that currently attracts the most attention. Based on the strength of the adsorption effect, the adsorption method can be summarized as physical adsorption and chemical adsorption. The adsorption effect of physical adsorption is relatively weak, so its regeneration energy consumption is low and its selectivity is poor. The adsorption effect of chemical adsorption is strong and has specific selection. It can adsorb a certain substance with high selectivity, but its regeneration energy consumption is relatively high. Amine-functionalized adsorption materials are a type of adsorbent that is currently widely used due to their high carbon dioxide adsorption capacity. The adsorption of CO2 mainly conforms to the zwitterion theory, but there are still some specific factors that affect the adsorption mechanism. For example, when there are no additional proton acceptors, the protons of the zwitterions can only be transferred to the adjacent amine functional groups, causing them to lose the ability to adsorb CO2 molecules, which means that two adsorption sites can capture one CO2 molecule; when there are additional proton acceptors (especially those with a proton acceptance capacity greater than that of the amine functional groups), the zwitterions will preferentially transfer protons to the proton acceptors, thereby achieving the ideal situation of one adsorption site capturing one CO2 molecule, greatly improving the utilization efficiency of the amine groups. Amine-functionalized adsorbent materials achieve a higher carbon dioxide adsorption capacity by loading a certain amount of organic amines. However, organic amines are prone to agglomeration, leading to clogging of the pores of the base material.

[0004] This invention creates a large number of point defects in the amine-functionalized adsorbent material, allowing the organic amine to combine with the defects. This allows for flexible control of the amine loading and achieves a high degree of dispersion of the amine molecules, significantly improving the problem of organic amine agglomeration. Furthermore, the introduction of additional proton acceptors enhances proton transfer, thereby improving the adsorption performance of the adsorbent material. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention provides a preparation method and application of an amine-functionalized adsorption material with highly dispersed active sites. The amine-functionalized adsorption material with highly dispersed active sites is prepared by the following method:

[0006] (1) 10-30 mg of graphene aerogel was placed into a corundum tube of a tubular furnace and subjected to thermal reduction treatment to prepare a thermally reduced sample.

[0007] (2) 10 to 30 mg of the sample obtained in step (1) is placed in a plasma vapor deposition tube, and the sample is subjected to plasma treatment in different atmospheres under vacuum conditions with an absolute pressure of less than 30 kPa to prepare the carrier used subsequently.

[0008] (3) Dry the carrier obtained in step (2) overnight. Take 10-50 mL of pure organic amine and 10-30 mg of the carrier and put them into a reactor, and heat them in a 60-100°C forced air oven for 8-15 hours. Then take out the sample and gently dry the organic amine attached to the surface with a paper towel. Soak the sample in 150-200 mL of anhydrous ethanol for 10-40 minutes, and dry it in a 60-100°C forced air oven overnight to obtain an amino-functionalized adsorption material with highly dispersed active sites.

[0009] Furthermore, the thermal reduction treatment method in step (1) is: removing oxygen in the tube by argon-vacuum cycle operation 2 to 3 times, raising the temperature to 1200-1600°C at a heating rate of 8-12°C (preferably 10°C) per minute under 10-20 mL / min argon protection, maintaining for 2-3 hours, and then cooling naturally.

[0010] Furthermore, the plasma atmosphere in step (2) is argon, helium, hydrogen, or carbon monoxide.

[0011] Furthermore, the plasma treatment method in step (2) is: removing oxygen in the tube by vacuum cycle operation 2 to 3 times, heating to 600 to 900° C. at a heating rate of 8 to 12° C. (preferably 10° C.) per minute under different atmosphere protection of 10 to 20 mL / min, the plasma power is set to 200 W, and the treatment time is 1 to 180 min.

[0012] Furthermore, the polyamino organic amine in step (3) is TETA (triethylenetetramine), TEPA (tetraethylenepentamine) and MMEN (N,N'-dimethylethylenediamine).

[0013] Furthermore, the oven temperature in step (3) is 60-90°C.

[0014] Furthermore, the anhydrous ethanol soaking temperature in step (3) is 30-50°C,

[0015] The present invention also provides an exploration of the amine loading capacity of an amine-functionalized adsorption material with highly dispersed active sites.

[0016] Compared to existing technologies, the present invention offers the following advantages: The amine-functionalized adsorbent material with highly dispersed active sites is prepared by creating a large number of point defects on a carbon material through thermal reduction and plasma treatment, followed by grafting of different organic amines. The key point is that the plasma treatment creates sufficient point defects to uniformly disperse the amine molecules, preventing organic amine agglomeration. This allows for flexible control of the amine loading and achieves a high degree of dispersion. Furthermore, the introduction of additional proton acceptors enhances proton transfer, thereby improving the adsorption performance of the adsorbent material. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG1 is an electron microscope image of spherical aberration corrected GA of the present invention before and after plasma treatment;

[0018] FIG2 is an XPS full spectrum analysis of dGA and TEPA-dGA of the present invention;

[0019] FIG3 is a Raman mapping of rGA, dGA and TEPA-dGA of the present invention (I D / I G );

[0020] FIG4 is a high-resolution N1s spectrum analysis of dGA and TEPA-dGA of the present invention; DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0022] The graphene aerogel used in this embodiment was prepared by the following method:

[0023] (1) Graphene oxide aqueous dispersion (12.55 mg / g) and ultrapure water were mixed at a volume ratio of 1:1 and stirred for 10 minutes to prepare a uniform dilution of 6.275 mg / g.

[0024] (2) 16 g of the diluted solution was spread evenly on a plastic Petri dish with a diameter of 60 mm, and dried in an oven at 60°C for 6 hours to obtain graphene oxide flakes.

[0025] (3) Immerse the graphene oxide flakes in a 30 vol% hydrazine hydrate solution at room temperature and foam for 3 hours until the flakes gradually become fluffy and foamy.

[0026] (4) The foamed sample was completely immersed in 20 mL of anhydrous ethanol for 3 hours, and the anhydrous ethanol was replaced with fresh anhydrous ethanol each time. This step was repeated three times. The above steps were repeated using n-hexane instead of anhydrous ethanol. The sample was placed in a 60°C oven and dried overnight to obtain a graphene aerogel.

[0027] Example 1

[0028] The present invention provides a method for preparing TEPA-modified graphene aerogel, the specific steps of which are as follows:

[0029] (1) 20 mg of graphene aerogel was placed in a corundum tube of a tubular furnace and subjected to thermal reduction treatment (the oxygen in the tube was removed by argon-vacuum cycle operation 3 times, and the temperature was raised to 1400°C at a rate of 10°C per minute under 15 mL / min argon protection, maintained for 2.5 hours, and then naturally cooled to ambient temperature) to obtain rGA.

[0030] (2) 20 mg of the sample obtained in step (1) was taken and placed in a plasma vapor deposition tube, and the sample was treated with argon plasma under vacuum conditions with an absolute pressure of less than 30 kPa (the oxygen in the tube was removed by vacuum cycling twice, and the temperature was raised to 750°C at a rate of 10°C per minute under the protection of a 15 mL / min argon atmosphere, the plasma power was set to 200 W, and the treatment time was 90 min) to obtain dGA.

[0031] (3) The support obtained in step (2) was dried overnight for 12 hours. 25 mL of pure TEPA and 20 mg of the support were placed in a reaction kettle and heated in a forced air oven at 90°C for 10 hours. The sample was then removed and the organic amine attached to the surface was gently blotted with a paper towel. The sample was then immersed in 170 mL of 40°C anhydrous ethanol for 20 minutes and dried at 80°C overnight for 12 hours to obtain the adsorption material TEPA-dGA.

[0032] The spherical aberration-corrected electron microscope image and XPS spectrum of the graphene aerogel prepared in this example are shown in Figures 1 and 2. After argon plasma treatment, the regular diffraction pattern of rGA is destroyed, and dGA has successfully introduced a large number of point defects. Before TEPA modification, there is almost no nitrogen on the dGA surface, while the nitrogen content on the surface of the TEPA-modified graphene aerogel is 20%. Figure 3 shows the Raman mapping images of the thermally reduced sample rGA, the carrier dGA after plasma treatment, and TEPA-dGA. It can be seen that the overall I D / I G The value is between 0.4 and 0.5. After argon plasma bombardment, dGA significantly increases to 0.6, indicating that a large number of point defects are introduced and evenly distributed on the dGA surface. After TEPA modification, the overall I D / I GThe value is reduced to 0.55, indicating that TEPA can accurately and evenly combine with the dispersed sites of point defects.

[0033] Figure 4 shows high-resolution N1s spectra before and after TEPA modification. The nitrogen on the TEPA-dGA surface primarily exists in three forms: pyridinic nitrogen, pyrrolic nitrogen, and graphitic nitrogen. The TEPA molecule itself exhibits the characteristics of pyridinic and pyrrolic nitrogen in XPS analysis, but does not contain graphitic nitrogen. Graphitic nitrogen is a form consisting of one nitrogen atom bonded to three carbon atoms. This unique nitrogen form can only be formed by covalent bonding of the amino functional groups of the TEPA molecule to point defects on the dGA surface. Therefore, TEPA-dGA is confirmed to be an amine-functionalized adsorption material that meets the requirements for highly dispersed active sites.

[0034] The amino loading capacity of the TEPA-dGA prepared in this example was investigated. The TGA curve of the modified TEPA exhibited a single weight loss peak, indicating that the loaded amines were all grafted onto the material, with no physical adsorption of organic amines. The TEPA loading on the TEPA-dGA reached 16 wt%, 36 wt%, 44 wt%, 66 wt%, 74 wt%, and 87 wt% when treated with argon plasma for 1, 5, 15, 30, 60, and 180 min, respectively.

[0035] Through DFT calculations, it was found that the TEPA-dGA prepared in this example can simultaneously complete the CO2 chemical adsorption and deprotonation process in just one step, which simplifies the reaction process and makes it easier to help the zwitterions formed after the amino group adsorbs CO2 to complete the deprotonation process, thereby achieving the purpose of improving the CO2 adsorption performance.

[0036] Furthermore, the prepared material can be used to manipulate amine groups. By varying the duration of the argon plasma treatment, the desired TEPA loading can be achieved. When used for CO2 adsorption, the highly dispersed TEPA bound to the graphene aerogel surface prevents TEPA from agglomerating, improving adsorption performance. Under 100% CO2 static adsorption for 30 minutes, the CO2 adsorption capacity reached 12 mmol / g, with an amine group utilization rate of 90%.

[0037] Example 2

[0038] The present invention provides a method for preparing TETA-modified graphene aerogel, which comprises the following steps:

[0039] (1) 30 mg of graphene aerogel was placed in a corundum tube of a tubular furnace and subjected to thermal reduction treatment (oxygen in the tube was removed by argon-vacuum cycle operation twice, and the temperature was raised to 1500°C at a rate of 12°C per minute under 18 mL / min argon protection, maintained for 2 hours, and then naturally cooled to ambient temperature) to obtain rGA.

[0040] (2) 25 mg of the sample obtained in step (1) was taken and placed in a plasma vapor deposition tube, and the sample was treated with argon plasma under vacuum conditions with an absolute pressure of less than 30 kPa (the oxygen in the tube was removed by vacuum cycling three times, and the temperature was raised to 650°C at a rate of 8°C per minute under the protection of a 10 mL / min argon atmosphere, the plasma power was set to 200 W, and the treatment time was 150 min) to obtain dGA.

[0041] The support obtained in step (2) was dried overnight for 11 hours. 25 mL of pure TETA and 20 mg of the support were placed in a reaction kettle and heated in a forced-air oven at 90°C for 10 hours. The sample was then removed and the organic amine attached to the surface was gently blotted with a paper towel. The sample was then immersed in 170 mL of 35°C anhydrous ethanol for 20 minutes and dried at 80°C overnight for 13 hours to obtain the adsorption material TETA-dGA.

[0042] The TETA loading on the TETA-dGA prepared in this example was investigated at different argon treatment times, with the highest being 54.0 wt%. TETA-dGA was applied to CO2 adsorption, with a CO2 adsorption capacity of 6 mmol / g after static adsorption at 100% CO2 for 30 min.

[0043] Example 3

[0044] The present invention provides a method for preparing MMEN-modified graphene aerogel, the specific steps of which are as follows:

[0045] (1) 30 mg of graphene aerogel was placed in a corundum tube of a tubular furnace and subjected to thermal reduction treatment (the oxygen in the tube was removed by argon-vacuum cycle operation 3 times, and the temperature was raised to 1300°C at a rate of 8°C per minute under the protection of 12 mL / min argon, maintained for 2 hours, and then naturally cooled to ambient temperature) to obtain rGA.

[0046] (2) 25 mg of the sample obtained in step (1) was taken and placed in a plasma vapor deposition tube, and the sample was treated with hydrogen plasma under vacuum conditions with an absolute pressure of less than 30 kPa (the oxygen in the tube was removed by vacuum cycling twice, and the temperature was raised to 850°C at a rate of 12°C per minute under the protection of a 20 mL / min argon atmosphere, the plasma power was set to 200 W, and the treatment time was 60 min) to obtain dGA.

[0047] (3) The support obtained in step (2) was dried overnight for 13 hours. 25 mL of pure MMEN and 20 mg of the support were placed in a reaction kettle and heated in a forced air oven at 90°C for 10 hours. The sample was then removed and the organic amine attached to the surface was gently blotted with a paper towel. The sample was then immersed in 170 mL of 45°C anhydrous ethanol for 20 minutes and dried at 80°C overnight for 11 hours to obtain the adsorption material MMEN-dGA.

[0048] The MMEN loading on the MMEN-dGA prepared in this example was investigated at different hydrogen treatment times, with the highest being 45.0 wt %. The MMEN-dGA was applied to CO 2 adsorption, with a CO 2 adsorption capacity of 5 mmol / g after static adsorption at 100% CO 2 for 30 min.

[0049] The above description is merely a preferred embodiment of the present invention and therefore cannot be used to limit the scope of the present invention. In other words, equivalent changes and modifications made according to the scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A method for preparing an amine-functionalized adsorption material with highly dispersed active sites, characterized in that: The following steps are involved: (1) The graphene aerogel is placed in a tubular furnace and subjected to thermal reduction treatment to obtain a thermally reduced sample; (2) placing the thermally reduced sample obtained in step (1) into a plasma vapor deposition tube, and subjecting the sample to plasma treatment in different atmospheres under vacuum conditions to obtain a carrier; (3) The carrier obtained in step (2) is dried overnight for 8 to 16 hours, the polyamino organic amine and the carrier are placed in a reaction kettle, and heated in a 60 to 100° C. forced air oven for 8 to 15 hours. The reactants are then taken out to remove the organic amine attached to the surface, and then immersed in ethanol for 10 to 40 minutes, and dried in a 60 to 100° C. forced air oven for 8 to 16 hours to obtain an amino-functionalized adsorption material with highly dispersed active sites.

2. The preparation method according to claim 1, characterized in that In step (1), the thermal reduction treatment specifically includes: removing oxygen in the tube by argon-vacuum cycle operation 2 to 3 times, raising the temperature to 1200 to 1600°C at a heating rate of 8 to 12°C per minute under the protection of 10 to 20 mL / min argon, maintaining it for 2 to 3 hours, and then cooling it naturally.

3. The preparation method according to claim 1, characterized in that In step (2), the sample is subjected to plasma treatment in different atmospheres under vacuum conditions with an absolute pressure of less than 30 kPa.

4. The preparation method according to claim 1, characterized in that In step (2), the atmosphere is argon, helium, hydrogen or carbon monoxide.

5. The preparation method according to claim 1, characterized in that In step (2), the plasma treatment specifically includes: removing oxygen in the tube by vacuum cycle operation 2 to 3 times, heating the temperature to 600 to 900° C. at a heating rate of 8 to 12° C. per minute under different atmosphere protection of 10 to 20 mL / min, setting the plasma power to 180 to 220 W, and the treatment time being 1 to 180 min.

6. The preparation method according to claim 1, characterized in that In step (3), the polyamino organic amine is TETA, TEPA or MMEN.

7. The preparation method according to claim 1, characterized in that In step (3), the oven temperature is 60-90°C.

8. The preparation method according to claim 1, characterized in that In step (3), the temperature of ethanol soaking is 30-50°C.

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