阅读说明：本技术 一种三维多孔石墨烯气凝胶材料及其制备方法与应用 (Three-dimensional porous graphene aerogel material and preparation method and application thereof ) 是由 陈水挟 吴景杰 于 2021-07-27 设计创作，主要内容包括：本发明公开了一种三维多孔石墨烯气凝胶材料及其制备方法与应用。本发明的三维多孔石墨烯气凝胶材料的制备方法包括如下步骤：将氧化石墨烯分散液与有机胺混合,水热反应,得到水凝胶；水洗,冷冻,干燥,得到三维多孔石墨烯气凝胶材料。本发明的制备方法简便,成本低廉,得到的三维多孔石墨烯气凝胶材料BET比表面积可达37m～(2)/g；吸附酸性气体,选择性强,吸附量高,CO-(2)的吸附容量可达2.27mmol/g；再生性能稳定,吸附再生10次,再生率可达到91％。(The invention discloses a three-dimensional porous graphene aerogel material, and a preparation method and application thereof. The preparation method of the three-dimensional porous graphene aerogel material comprises the following steps: mixing the graphene oxide dispersion liquid with organic amine, and carrying out hydrothermal reaction to obtain hydrogel; and (4) washing, freezing and drying to obtain the three-dimensional porous graphene aerogel material. The preparation method is simple and convenient, the cost is low, and the BET ratio of the obtained three-dimensional porous graphene aerogel materialThe surface area can reach 37m 2 (ii)/g; strong selectivity, high adsorption quantity and CO adsorption 2 The adsorption capacity of the adsorbent can reach 2.27 mmol/g; the regeneration performance is stable, the adsorption regeneration is carried out for 10 times, and the regeneration rate can reach 91 percent.)

1. A preparation method of a three-dimensional porous graphene aerogel material is characterized by comprising the following steps:

(1) mixing the graphene oxide dispersion liquid with organic amine, and carrying out hydrothermal reaction to obtain hydrogel;

(2) and (2) washing, freezing and drying the hydrogel obtained in the step (1) to obtain the three-dimensional porous graphene aerogel material.

2. The method for preparing the three-dimensional porous graphene aerogel material according to claim 1, wherein the organic amine in the step (1) is at least one of triethylene tetramine, tetraethylene pentamine and polyethyleneimine.

3. The method for preparing the three-dimensional porous graphene aerogel material according to claim 2, wherein the Mw of the polyethyleneimine is 600-10000.

4. The preparation method of the three-dimensional porous graphene aerogel material according to claim 1,

the dosage of the graphene oxide dispersion liquid in the step (1) is 1: 1-5 of the mass ratio of graphene oxide to organic amine;

the concentration of the graphene oxide dispersion liquid in the step (1) is 2-6 mg/mL.

5. The preparation method of the three-dimensional porous graphene aerogel material according to claim 4,

the dosage of the graphene oxide dispersion liquid in the step (1) is in a mass ratio of 1: 3 of graphene oxide to organic amine;

the concentration of the graphene oxide dispersion liquid in the step (1) is 4 mg/mL.

6. The preparation method of the three-dimensional porous graphene aerogel material according to claim 1,

the hydrothermal reaction in the step (1) is carried out for 2-12 h at 140-180 ℃;

adjusting the pH value to 8 before mixing the graphene oxide dispersion liquid and organic amine in the step (1);

the step (2) of water washing is water washing until the pH value of the supernatant is neutral;

the freezing in the step (2) is liquid nitrogen freezing;

and (3) the drying in the step (2) is vacuum freeze drying.

7. The preparation method of the three-dimensional porous graphene aerogel material according to claim 6,

the hydrothermal reaction in the step (1) is carried out for 12 hours at 180 ℃;

the pH value is adjusted by adopting 0.1M NaOH solution;

the freezing time in the step (2) is 10min-30 min;

the vacuum freeze-drying time is 48-72 h.

8. A three-dimensional porous graphene aerogel material, which is prepared by the preparation method of any one of claims 1 to 7.

9. Use of the three-dimensional porous graphene aerogel material of claim 8 in acid gas adsorption.

10. The use according to claim 9, wherein the acid gas is CO₂。

Technical Field

The invention relates to the technical field of environment function adsorption materials, in particular to a three-dimensional porous graphene aerogel material and a preparation method and application thereof.

Background

Since the industrial revolution, with the increasing frequency of human activities, the concentration of carbon dioxide in the atmosphere has been increasing. CO 2₂As an important member of greenhouse gases, the increase in their concentration causes global warming, which in turn destroys the ecological environment. Therefore, how to effectively capture CO in the atmosphere₂Is a concern for people all over the world. In the capture of CO in a plurality of₂Among the methods, the adsorption method has been paid attention by researchers because of its advantages such as low cost, wide adsorption temperature range, low regeneration energy consumption, etc.

The important point to be considered in the adsorption method is the selection of the adsorbent, and the solid amine adsorbent becomes a research hotspot in the field of carbon dioxide capture due to the advantages of high adsorption capacity, high adsorption rate, high selectivity and the like. At present, a solid amine adsorbent using a porous material as a carrier has been extensively studied, and the porous material mainly includes carbon materials, metal organic framework Materials (MOFs), zeolite base, and the like. Among them, graphene has excellent mechanical properties and a large specific surface area (2600 m theoretically)²The,/g), good mass transfer and heat transfer capabilities, etc. have attracted a great deal of researchers. However, graphene is a two-dimensional material that is easily stacked during use, limiting its specific surface area. In addition, graphene alone has a low capacity for carbon dioxide adsorption at low pressure because it lacks a pore structure and is not loaded with basic compounds (e.g., amines). The three-dimensional porous graphene aerogel has a hierarchical pore structure and comprises micropores, mesopores and macropores. In addition, the pore channel has larger size and small mass transfer resistance, and is an ideal solid amine adsorption material.

Chinese patent CN105254916A discloses a preparation method of graphene oxide/poly-dopamine composite aerogel, specifically, dopamine is adsorbed on the surface of graphene oxide by means of the interaction between dopamine and functional groups on the surface of graphene oxide. And then, under the alkaline environment and the oxygen condition, polymerizing dopamine on the surface of the graphene oxide to obtain the graphene oxide/polydopamine composite aerogel. The organic amine reagent used in the method is dopamine, and the content of amino groups in dopamine molecules is low, so that the active adsorption sites of the composite aerogel are few, and the adsorption effect of the composite aerogel applied to carbon dioxide is poor (the adsorption quantity is only 1.02mmol/g through experimental tests). In addition, the interaction force between dopamine molecules and graphene oxide is weak, graphene oxide lamella cannot be crosslinked in the form of chemical bonds, the structural stability is poor, and the effect in the carbon dioxide adsorption regeneration process is poor (the regeneration efficiency is low).

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a preparation method of a three-dimensional porous graphene aerogel material.

Another object of the present invention is to provide a three-dimensional porous graphene aerogel material prepared by the above preparation method.

The invention further aims to provide application of the three-dimensional porous graphene aerogel material.

The purpose of the invention is realized by the following technical scheme: a preparation method of a three-dimensional porous graphene aerogel material comprises the following steps:

(1) mixing the graphene oxide dispersion liquid with organic amine, and carrying out hydrothermal reaction to obtain hydrogel;

(2) and (2) washing, freezing and drying the hydrogel obtained in the step (1) to obtain the three-dimensional porous graphene aerogel material.

Preferably, the concentration of the graphene oxide dispersion liquid in the step (1) is 2-6 mg/mL; more preferably, the concentration is 4 mg/mL.

Preferably, the mixing in step (1) is performed by dropping organic amine into the graphene oxide dispersion liquid.

Preferably, the graphene oxide dispersion liquid in the step (1) is adjusted to have a pH of 8 before being mixed with the organic amine.

Preferably, the pH adjustment is carried out using a 0.1M NaOH solution.

Preferably, the organic amine in step (1) is at least one of triethylene tetramine, tetraethylene pentamine and polyethyleneimine.

Preferably, the polyethyleneimine has a Mw of 600-10000.

Preferably, the amount of the graphene oxide dispersion liquid in the step (1) is 1: 1-5 according to the mass ratio of the graphene oxide to the organic amine; more preferably, the mass ratio of the graphene oxide to the organic amine is 1: 3.

Preferably, the hydrothermal reaction in the step (1) is carried out for 2-12 h at 140-180 ℃; more preferably, the hydrothermal reaction is carried out at 180 ℃ for 12 h.

Preferably, the water washing in the step (2) is water washing until the pH value of the supernatant is neutral.

Preferably, the freezing of step (2) is liquid nitrogen freezing.

Preferably, the freezing time of the step (2) is 10-30 min; more preferably, the time for freezing is 10 min.

Preferably, the drying of step (2) is vacuum freeze drying.

Preferably, the vacuum freeze-drying time is 48-72 h; more preferably, the time for freeze-drying is 48 h.

The three-dimensional porous graphene aerogel material is prepared by the preparation method.

The three-dimensional porous graphene aerogel material is applied to acid gas adsorption.

Preferably, the acid gas is CO₂。

Compared with the prior art, the invention has the following beneficial effects:

according to the preparation method, organic amine with high amino content is selected as a cross-linking agent and a reducing agent, and the three-dimensional porous graphene aerogel material is prepared by adopting a one-step hydrothermal method, so that the operation is simple and convenient, and the cost is low; the organic amine contains rich amino groups, can provide adsorption sites for adsorbing acid gas, and has strong selectivity, high adsorption quantity and CO₂The adsorption capacity of the adsorbent can reach 2.27 mmol/g; organic amine molecular intercalation enters between graphene sheet layers, agglomeration among the graphene can be effectively reduced, a multi-stage pore channel structure is endowed with the freeze drying technology, the specific surface area of the material is increased, and the BET specific surface area can reach 37m²(ii)/g; in addition, the three-dimensional porous graphene aerogel material has stable regeneration performance, and is subjected to adsorption regeneration 1The regeneration rate can reach 91 percent after 0 time.

Drawings

FIG. 1 is a scanning electron micrograph of TEPA-GA-3-1 in example 1.

FIG. 2 is a scanning electron micrograph of TETA-GA-3-1 in example 2.

FIG. 3 is a scanning electron micrograph of TEPA-GA-5-1 in example 3.

FIG. 4 is a scanning electron micrograph of RGO in comparative example 1.

FIG. 5 is a scanning electron micrograph of GO in comparative example 2.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A preparation method of a three-dimensional porous graphene aerogel material comprises the following steps:

0.20g of Graphene Oxide (GO) powder is dispersed in 50mL of deionized water by ultrasonic for 1h to prepare 4mg/mL of graphene oxide dispersion liquid. The dispersion was transferred to a 100mL Teflon lined compact autoclave, the pH of the dispersion was adjusted to 8 with 0.1M NaOH solution, and then 0.60g of Tetraethylenepentamine (TEPA) solution was added dropwise at a rate of 1 drop for 5 seconds with a dropper and stirred continuously, and the mixture was viscous. The reaction kettle is sealed and placed in an oven to react for 12 hours at 180 ℃. And after the reaction is finished, taking out the hydrogel, washing the hydrogel with deionized water until the pH of the supernatant is neutral, freezing the hydrogel in liquid nitrogen for 10min, and further carrying out vacuum freeze drying for 48h to obtain the graphene aerogel (TEPA-GA-3-1).

When the TEPA-GA-3-1 obtained in example 1 was analyzed by scanning electron microscopy (FIG. 1), the TEPA-GA-3-1 exhibited a three-dimensional porous structure and a BET specific surface area of 37m²(ii) in terms of/g. Applying it to CO₂Adsorption performance measurement ofTest for CO₂The adsorption capacity of (2) was 2.27mmol/g, and the adsorption was regenerated 10 times at a regeneration rate of 91%.

CO₂The adsorption performance test method comprises the following steps:

0.45g of aerogel was weighed into an adsorption column of fixed internal diameter (. PHI.: 1.5cm) and length (L.: 20cm) and pure N was passed in before the test₂Pretreating for 30min to remove residual CO in the adsorption column₂And water, introducing the adsorption column into gas chromatography, introducing CO₂And N₂Detecting CO at the outlet of the adsorption column at time intervals of 2min₂And (4) concentration. Determination of adsorbent vs. CO by means of breakthrough curve and cumulative adsorption curve₂The adsorption capacity of (c). CO of all adsorbents₂The adsorption capacity is calculated by the following formula:

wherein Q (mmol/g) is CO₂The adsorption capacity of (a); c_inAnd C_effRespectively an inlet and an outlet CO of the adsorption column₂Concentration (vol%); v (mL/min) denotes the mixed gas flow rate; t (min) represents CO₂The adsorption time of (c); w (g) is the mass of the adsorbent; 22.4 (unit: mL/mmol) is the gas molar volume in the standard state.

Regeneration efficiency after 10 cycles: e ═ Q₁₀/Q₁×100％。

Example 2

The difference between this example and example 1 is only that the organic amine reagent in this example is triethylene tetramine (TETA) and the prepared graphene aerogel is named TETA-GA-3-1.

The amounts of other raw materials and the operation procedure were the same as in example 1.

Scanning Electron microscopy analysis (FIG. 2) was performed on TETA-GA-3-1 obtained in example 2, and TETA-GA-3-1 exhibited a three-dimensional porous structure and a BET specific surface area of 25m²(ii) in terms of/g. Applying it to CO₂Adsorption Performance test of (1), on CO₂The adsorption capacity of (2) was 2.15mmol/g, and the adsorption was regenerated 10 times at a regeneration rate of 90%.

Example 3

The difference between this example and example 1 is only that the organic amine reagent TEPA is added in an amount of 1.00g, and the prepared graphene aerogel is named TEPA-GA-5-1.

The amounts of other raw materials and the operation procedure were the same as in example 1.

When the TEPA-GA-5-1 obtained in example 3 was analyzed by scanning electron microscopy (FIG. 3), the TEPA-GA-5-1 exhibited a three-dimensional porous structure and a BET specific surface area of 15m²(ii) in terms of/g. Applying it to CO₂Adsorption Performance test of (1), on CO₂The adsorption capacity of (2) was 2.12mmol/g, and the adsorption was regenerated 10 times at a regeneration rate of 91%.

Comparative example 1

The difference between this comparative example and example 1 is that, in this example, no organic amine reagent is added, and the prepared GO dispersion is directly subjected to hydrothermal reduction to prepare three-dimensional Reduced Graphene Oxide (RGO).

The amounts of other raw materials and the operation procedure were the same as in example 1.

The RGO obtained in this comparative example was analyzed by scanning electron microscopy (FIG. 4), and the RGO exhibited a three-dimensional porous structure. Applying it to CO₂Adsorption Performance test of (1), on CO₂Has an adsorption capacity of 1.08mmol/g and CO content as compared with that in examples 1, 2 and 3₂Because of the lack of loading of amine species.

Comparative example 2

This comparative example directly tests Graphene Oxide (GO) powder for CO₂The adsorption performance of (3). Scanning electron microscope shows that (figure 5), the graphene oxide shows an agglomerated morphology, has no obvious pore structure, and has a BET specific surface area of only 12m²(ii) in terms of/g. Applying it to CO₂Adsorption Performance test of (1), on CO₂The adsorption capacity of (A) was only 0.45 mmol/g.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.