An amine-modified nitrogen-doped carbon material, a preparation method and application thereof

Abstract

The present application relates to the technical field of carbon dioxide adsorption materials, and provides an amine modified nitrogen-doped carbon material, a preparation method and application thereof.The present application prepares a porous carbon material through carbonization of a sugar auxiliary nitrogen-containing amine compound, and obtains the amine modified nitrogen-doped carbon material through impregnation modification of the amine compound.The amine modified nitrogen-doped carbon material prepared by the present application has excellent carbon dioxide adsorption performance, and the adsorption amount of carbon dioxide in flue gas can reach 4.3mmol / g within 2 hours at low temperature and normal pressure, and the material has good repeated use performance, and the adsorption amount of carbon dioxide decreases little after 10 times of repeated use.The preparation method provided by the present application is simple, and the target product can be obtained in two steps, and the raw materials are simple in source and low in cost, and more importantly, no strong acid, strong base and other raw materials with high requirements on production equipment required in preparation of other carbon dioxide adsorbents are used.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide adsorption materials technology, and in particular to an amine-modified nitrogen-doped carbon material, its preparation method, and its application. Background Technology

[0002] Since the Industrial Revolution, humans have released large amounts of flue gas and other waste gases into the atmosphere, with greenhouse gases such as carbon dioxide increasing year by year. The greenhouse effect of the atmosphere has also intensified, and a series of problems caused by this have attracted the attention of countries around the world.

[0003] Solid adsorbents play a crucial role in carbon dioxide adsorption technology. Among them, carbon materials, as porous materials, have adjustable pore sizes, large specific surface areas, stable chemical properties, and most importantly, are inexpensive and readily available, thus attracting widespread attention in carbon dioxide adsorption. Although pure carbon materials adsorb carbon dioxide at a fast rate, the adsorption capacity is not ideal under normal pressure and low temperature conditions, and the selectivity and reusability are also poor (Carbon-based adsorbents for post-combustion capture: a review[J]. Greenhouse Gas-Sci.Technol.2018,8(11–36)). To address these issues, developing a low-cost carbon dioxide adsorbent with excellent adsorption performance and outstanding reusability has become an urgent problem to be solved. Summary of the Invention

[0004] In view of this, the present invention provides an amine-modified nitrogen-doped carbon material, its preparation method, and its application. The amine-modified nitrogen-doped carbon material provided by the present invention exhibits good carbon dioxide adsorption performance at low temperature and normal pressure, good reusability, and the preparation method is simple and low in cost.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] A method for preparing an amine-modified nitrogen-doped carbon material includes the following steps:

[0007] A mixture of sugar-based carbon source and nitrogen-containing amine carbon source is ground, and the resulting mixture is carbonized to obtain a porous carbon material.

[0008] The porous carbon material is impregnated in an amine compound solution to obtain the amine-modified nitrogen-doped carbon material.

[0009] Preferably, the carbohydrate carbon source includes one or more of sucrose, glucose, chitosan, and cellulose; the nitrogen-containing amine carbon source includes one or more of dicyandiamine, melamine, and urea.

[0010] Preferably, the mass ratio of the carbohydrate carbon source to the nitrogen-containing amine carbon source is 1:10 to 50.

[0011] Preferably, the carbonization temperature is 500–900°C, and the holding time is 2–6 hours; the carbonization is carried out in a nitrogen atmosphere.

[0012] Preferably, the amine compound includes one or more of polyethyleneimine, tetraethylenepentamine, and pentaethylenehexamine; the solvent of the amine compound solution is an alcohol solvent; and the mass ratio of the amine compound to the porous carbon material is 0.2 to 0.65:1.

[0013] Preferably, the immersion temperature is room temperature, and the immersion time is 0.5 to 2 hours.

[0014] The present invention also provides an amine-modified nitrogen-doped carbon material prepared by the preparation method described above, comprising a porous carbon material and an amine compound supported in the porous carbon material.

[0015] The present invention also provides the application of the amine-modified nitrogen-doped carbon material described above in carbon dioxide adsorption.

[0016] Preferably, the carbon dioxide is carbon dioxide from flue gas, the adsorption temperature is 30-90°C, and the pressure is atmospheric pressure.

[0017] Preferably, after the amine-modified nitrogen-doped carbon material adsorbs carbon dioxide, the method further includes desorbing the amine-modified nitrogen-doped carbon material after adsorbing carbon dioxide. The desorption method is to purge the amine-modified nitrogen-doped carbon material after adsorbing carbon dioxide with nitrogen gas at a temperature of 100-120°C.

[0018] This invention provides a method for preparing amine-modified nitrogen-doped carbon materials, comprising the following steps: mixing and grinding a sugar-based carbon source and a nitrogen-containing amine carbon source; carbonizing the resulting mixture to obtain a porous carbon material; and impregnating the porous carbon material in an amine compound solution to obtain the amine-modified nitrogen-doped carbon material. This invention uses a nitrogen-containing amine compound as the nitrogen source and utilizes a sugar compound to assist in the carbonization of the nitrogen-containing amine compound, enabling the obtained porous carbon material to have a larger pore size and pore volume, thereby improving the carbon dioxide adsorption performance of the final amine-modified nitrogen-doped carbon material. Furthermore, the raw materials used in this invention are widely available, low in cost, and the synthesis method is simple. The material carrier is synthesized in one step, and impregnation is sufficient to meet the application requirements. More importantly, it does not use the strong acids and strong alkalis required in the preparation of other carbon dioxide adsorbents, which place extremely high demands on production equipment, thus facilitating industrial application. The results of the examples show that, under low temperature and normal pressure, the amine-modified nitrogen-doped carbon material prepared in this invention can adsorb carbon dioxide in flue gas up to 4.3 mmol / g within 2 hours, and has good reusability. After being reused 10 times, the adsorption capacity of carbon dioxide decreases very little. Attached Figure Description

[0019] Figure 1 The results show the cyclic adsorption performance of the amine-modified nitrogen-doped carbon material obtained in Example 1. Detailed Implementation

[0020] This invention provides a method for preparing amine-modified nitrogen-doped carbon materials, comprising the following steps:

[0021] A mixture of sugar-based carbon source and nitrogen-containing amine carbon source is ground, and the resulting mixture is carbonized to obtain a porous carbon material.

[0022] The porous carbon material is impregnated in an amine compound solution to obtain the amine-modified nitrogen-doped carbon material.

[0023] This invention involves mixing and grinding a carbohydrate carbon source and a nitrogen-containing amine carbon source, then carbonizing the resulting mixture to obtain a porous carbon material. In this invention, the carbohydrate carbon source preferably includes one or more of sucrose, glucose, chitosan, and cellulose; the nitrogen-containing amine carbon source preferably includes one or more of dicyandiamine, melamine, and urea. When multiple nitrogen-containing amine carbon sources are used, melamine and urea are preferred, or melamine and dicyandiamine are preferred. When melamine and urea are used, the mass ratio of melamine to urea is preferably 1:1 to 1.5, more preferably 1.1; when melamine and dicyandiamine are used, the mass ratio of melamine to dicyandiamine is preferably 1:1 to 1.5, more preferably 1.1.

[0024] In this invention, the mass ratio of the carbohydrate carbon source to the nitrogen-containing amine carbon source is preferably 1:10 to 50, more preferably 1:15 to 40.

[0025] The present invention does not have any special requirements for the specific method of mixing and grinding; any method known to those skilled in the art can be used.

[0026] In this invention, the carbonization temperature is preferably 500-900℃, more preferably 600-850℃, and the heating rate to the carbonization temperature is preferably 2℃ / min; the carbonization holding time is preferably 2-6h, more preferably 2-3h; the carbonization is preferably carried out in a nitrogen atmosphere; after the carbonization is completed, it is preferably naturally cooled to room temperature to obtain the porous carbon material.

[0027] After obtaining the porous carbon material, the present invention impregnates the porous carbon material in an amine compound solution to obtain the amine-modified nitrogen-doped carbon material. In the present invention, the amine compound preferably includes one or more of polyethyleneimine, tetraethylenepentamine, and pentaethylenehexamine; the solvent of the amine compound solution is an alcohol solvent, more preferably ethanol, specifically anhydrous ethanol; the impregnation method is equal-volume impregnation; the mass ratio of the amine compound to the porous carbon material is preferably 0.2–0.65:1, more preferably 0.3–0.5:1.

[0028] In this invention, the impregnation temperature is preferably room temperature, and the impregnation time is preferably 0.5 to 2 hours, more preferably 0.5 to 1 hour. In a specific embodiment of this invention, it is preferable to first pulverize the obtained porous carbon material before impregnation.

[0029] In this invention, after impregnation, it is preferable to remove the alcohol solvent in the impregnation system to obtain the amine-modified nitrogen-doped carbon material; the preferred method for removing the alcohol solvent is rotary evaporation, and the preferred temperature for rotary evaporation is 60°C.

[0030] The present invention also provides an amine-modified nitrogen-doped carbon material prepared by the preparation method described above, comprising a porous carbon material and an amine compound supported in the porous carbon material.

[0031] This invention also provides the application of the amine-modified nitrogen-doped carbon material described above in carbon dioxide adsorption. In this invention, the carbon dioxide is preferably carbon dioxide from flue gas; the adsorption temperature is preferably 30–90°C, more preferably 40–80°C, and even more preferably 75°C; the adsorption pressure is preferably atmospheric pressure, specifically 0.82–0.85 atm. In practical applications, the amine-modified nitrogen-doped carbon material requires no treatment and can be used directly. In a specific embodiment of this invention, the carbon dioxide adsorption performance of the amine-modified nitrogen-doped carbon material is tested using simulated flue gas, with a gas flow rate of 50–100 mL / min.

[0032] After the amine-modified nitrogen-doped carbon material adsorbs carbon dioxide, preferably after adsorbing carbon dioxide to saturation, the method further includes desorbing the amine-modified nitrogen-doped carbon material after adsorbing carbon dioxide. The desorption method is preferably to purge the amine-modified nitrogen-doped carbon material after adsorbing carbon dioxide with nitrogen gas. The nitrogen purging temperature is preferably 100-120°C. The nitrogen purging time is preferably 0.5-1 h.

[0033] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0034] Example 1

[0035] Weigh 0.82g of glucose, 7.50g of melamine, and 7.50g of urea, mix them thoroughly, and grind them. Place the ground mixture in a ceramic boat. Heat the mixture to 850℃ in a tube furnace under nitrogen protection at a heating rate of 2℃ / min, hold for 1 hour, and then allow it to cool naturally to room temperature to obtain porous carbon material.

[0036] The obtained porous carbon material was pulverized into powder. Polyethyleneimine was weighed and completely dissolved in 10 mL of anhydrous ethanol to obtain a polyethyleneimine solution, wherein the mass of polyethyleneimine was 50% of the mass of the porous carbon material. The obtained polyethyleneimine solution was used to impregnate the modified porous carbon material for 0.5 h at room temperature. After impregnation, the anhydrous ethanol solvent was evaporated at 60 °C to obtain the amine-modified nitrogen-doped carbon material.

[0037] To increase the rigor and accuracy of the test results, the amine-modified nitrogen-doped carbon material was first purified, and then an adsorption experiment was conducted using simulated flue gas. Specifically, 11.91 mg of the prepared amine-modified nitrogen-doped carbon material was placed in a 60 μL alumina crucible and purged with nitrogen at 100 mL / min for 2 hours at 120°C to remove moisture and other impurities. The temperature was then lowered to 80°C, and under a pressure of 0.82 atm, the nitrogen gas was replaced with simulated flue gas (the volume fractions of each gas component in the simulated flue gas were: CO2 19%, O2 3%, N2 78%). The flow rate of the simulated flue gas was 50 mL / min, and the adsorption time was 2 hours. The carbon dioxide adsorption capacity of the amine-modified nitrogen-doped carbon material after 2 hours was measured to be 4.3 mmol / g.

[0038] The adsorbed amine-modified nitrogen-doped carbon material was purged with nitrogen at 110℃ for 1 hour to desorb carbon dioxide. After desorption, simulated flue gas was introduced again, and adsorption experiments were conducted under the same conditions. After 10 cycles, the carbon dioxide adsorption capacity remained at 4.1 mmol / g. The results of the cyclic adsorption experiment are as follows: Figure 1 As shown.

[0039] Example 2

[0040] 0.43g of cellulose and 15.02g of melamine were weighed, mixed evenly, and then ground. The resulting mixture was placed in a ceramic boat. Under nitrogen protection, the mixture was heated to 800℃ in a tube furnace at a heating rate of 3℃ / min, held for 2 hours, and then allowed to cool naturally to room temperature to obtain porous carbon material.

[0041] The obtained porous carbon material was pulverized into powder. Polyethyleneimine was weighed and completely dissolved in 10 mL of anhydrous ethanol to obtain a polyethyleneimine solution, wherein the mass of polyethyleneimine was 50% of the mass of the porous carbon material. The obtained polyethyleneimine solution was used to impregnate the modified porous carbon material for 0.5 h. After impregnation, the anhydrous ethanol solvent was evaporated at 65 °C to obtain the amine-modified nitrogen-doped carbon material.

[0042] 10.23 mg of the prepared amine-modified nitrogen-doped carbon material was placed in a 60 μL alumina crucible and purged with nitrogen at 100 mL / min for 1 h at 120 °C to remove moisture and other impurities. The temperature was then lowered to 70 °C, and under a pressure of 0.82 atm, the nitrogen gas was replaced with simulated flue gas (the volume fractions of the simulated flue gas were: CO2 19%, O2 3%, N2 78%), with a flow rate of 50 mL / min and an adsorption time of 2 h. The carbon dioxide adsorption capacity of the amine-modified nitrogen-doped carbon material obtained in this example was 3.6 mmol / g after 2 h.

[0043] Example 3

[0044] 0.78g of cellulose, 7.51g of melamine, and 7.52g of dicyandiamide were weighed, mixed evenly, and then ground. The resulting mixture was placed in a ceramic boat. Under nitrogen protection, the mixture was heated to 800℃ in a tube furnace at a heating rate of 3℃ / min, held for 1 hour, and then allowed to cool naturally to room temperature to obtain porous carbon material.

[0045] The obtained porous carbon material was pulverized into powder. Polyethyleneimine was weighed and completely dissolved in 10 mL of anhydrous ethanol to obtain a polyethyleneimine solution, wherein the mass of polyethyleneimine was 50% of the mass of the porous carbon material. The obtained polyethyleneimine solution was used to impregnate the modified porous carbon material for 0.5 h. After impregnation, the anhydrous ethanol solvent was evaporated at 60 °C to obtain the amine-modified nitrogen-doped carbon material.

[0046] 12.03 mg of the prepared amine-modified nitrogen-doped carbon material was placed in a 60 μL alumina crucible and purged with nitrogen at 100 mL / min for 2 h at 120 °C to remove moisture and other impurities. The mixture was then cooled to 70 °C and subjected to a pressure of 0.82 atm. Simulated flue gas (with volume fractions of CO2 19%, O2 3%, N2 78%) was used as the nitrogen gas, with a flow rate of 50 mL / min and an adsorption time of 2 h. The carbon dioxide adsorption capacity of the amine-modified nitrogen-doped carbon material obtained in this example was 3.9 mmol / g after 2 h.

[0047] Example 4

[0048] Weigh 0.30g of chitosan and 15.00g of urea, mix them evenly, and then grind them. Place the resulting mixture in a ceramic boat. Under nitrogen protection, heat the mixture in a tube furnace at a rate of 5℃ / min to 700℃, hold for 2 hours, and then allow it to cool naturally to room temperature to obtain porous carbon material.

[0049] The obtained porous carbon material was pulverized into powder. Pentaethylenehexamine was weighed and completely dissolved in 10 mL of anhydrous ethanol to obtain a pentaethylenehexamine solution, wherein the mass of pentaethylenehexamine was 50% of the mass of the porous carbon material. The obtained pentaethylenehexamine solution was used to impregnate the modified porous carbon material for 1 hour. The anhydrous ethanol solvent was evaporated at 60℃ to obtain the amine-modified nitrogen-doped carbon material.

[0050] 20.12 mg of the prepared amine-modified nitrogen-doped carbon material was placed in a 60 μL alumina crucible and purged with nitrogen at 100 mL / min for 1 h at 120 °C to remove moisture and other impurities. The mixture was then cooled to 30 °C and subjected to a pressure of 0.82 atm. Simulated flue gas (with volume fractions of CO2 19%, O2 3%, N2 78%) was used as the nitrogen gas, with a flow rate of 50 mL / min and an adsorption time of 2 h. The carbon dioxide adsorption capacity of the amine-modified nitrogen-doped carbon material obtained in this example was 2.8 mmol / g after 2 h.

[0051] Example 5

[0052] Weigh 0.82g of sucrose and 15.00g of dicyandiamine, mix them evenly, and grind them. Place the resulting mixture in a ceramic boat. In a tube furnace under nitrogen protection, heat the mixture to 800℃ at a rate of 2℃ / min, hold it for 1.5h, and then allow it to cool naturally to room temperature to obtain porous carbon material.

[0053] The obtained porous carbon material was pulverized into powder. Tetraethylenepentamine was weighed and completely dissolved in 10 mL of anhydrous ethanol to obtain a tetraethylenepentamine solution, wherein the mass of tetraethylenepentamine was 50% of the mass of the porous carbon material. The obtained tetraethylenepentamine solution was used to impregnate the modified porous carbon material for 2 hours. After impregnation, the anhydrous ethanol solvent was evaporated at 65 °C to obtain the amine-modified nitrogen-doped carbon material.

[0054] 12.85 mg of the prepared amine-modified nitrogen-doped carbon material was placed in a 60 μL alumina crucible and purged with nitrogen at 100 mL / min for 2 hours at 120 °C to remove moisture and other impurities. The mixture was then cooled to 75 °C and subjected to a pressure of 0.82 atm. Simulated flue gas (with volume fractions of CO2 19%, O2 3%, N2 78%) was used as the nitrogen gas, with a flow rate of 50 mL / min and an adsorption time of 2 hours. The carbon dioxide adsorption capacity of the amine-modified nitrogen-doped carbon material obtained in this example was 3.7 mmol / g after 2 hours of testing.

[0055] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of amine-modified nitrogen-doped carbon materials in carbon dioxide adsorption, characterized in that, The preparation steps of the amine-modified nitrogen-doped carbon material are as follows: A carbohydrate carbon source and a nitrogen-containing amine carbon source are mixed and ground, and the resulting mixture is carbonized to obtain a porous carbon material; the carbohydrate carbon source is one or more of sucrose, glucose, and cellulose; the nitrogen-containing amine carbon source is one or more of dicyandiamine and melamine, or melamine and urea; the mass ratio of the carbohydrate carbon source to the nitrogen-containing amine carbon source is 1:15~40; The porous carbon material is impregnated in an amine compound solution to obtain the amine-modified nitrogen-doped carbon material; The amine compound includes one or more of polyethyleneimine, tetraethylenepentamine, and pentaethylenehexamine; the mass ratio of the amine compound to the porous carbon material is 0.2 to 0.65:

1.

2. The application according to claim 1, characterized in that, The carbonization temperature is 500~900℃, and the holding time is 2~6h; the carbonization is carried out in a nitrogen atmosphere.

3. The application according to claim 1, characterized in that, The solvent for the amine compound solution is an alcohol solvent.

4. The application according to claim 1, characterized in that, The immersion temperature is room temperature, and the immersion time is 0.5 to 2 hours.

5. The application according to claim 1, characterized in that, The amine-modified nitrogen-doped carbon material includes porous carbon material and amine compounds supported in the porous carbon material.

6. The application according to claim 1, characterized in that, The carbon dioxide is carbon dioxide from the flue gas, and the adsorption temperature is 30~90℃, and the pressure is atmospheric pressure.

7. The application according to claim 6, characterized in that, After the amine-modified nitrogen-doped carbon material adsorbs carbon dioxide, the method further includes desorbing the amine-modified nitrogen-doped carbon material after adsorbing carbon dioxide. The desorption method is to purge the amine-modified nitrogen-doped carbon material after adsorbing carbon dioxide with nitrogen gas at a temperature of 100~120℃.

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