A biomass-based activated carbon material

Abstract

The application discloses a biomass-based activated carbon material, relates to the technical field of activated carbon material preparation, and comprises the following components in parts by weight: 1 part of mandarin peel meal; and 1-2 parts of fir bark. The application further discloses a preparation method of the biomass-based activated carbon material, and specifically comprises the following steps: S1, drying, crushing and mixing the mandarin peel meal and the fir bark to obtain mixed raw material A; S2, placing the mixed raw material A into an evaporator and evaporating at low temperature to obtain mixed raw material A with high sulfuric acid salt content; S3, ultrasonic immersion and drying the mixed raw material A with high sulfuric acid salt content, and then carbonizing and activating the mixed raw material A to obtain mixed carbon material B; and S4, mixing the mixed carbon material B with sodium amide, and activating in an air-tight manner to obtain the biomass-based activated carbon material. The biomass-based activated carbon material with stable quality is prepared by solving the problem of unstable quality of the biomass-based activated carbon material caused by unstable quality of desulfurization waste liquid in the prior art, the pore structure of the biomass-based activated carbon material is further optimized, and the adsorption performance is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of activated carbon material preparation, and particularly relates to a biomass-based activated carbon material. BACKGROUND

[0002] Activated carbon is widely used in the separation of flue gas carbon dioxide and other gases due to its advantages of large specific surface area, adjustable pore size, good surface hydrophobicity, low cost and easy availability. At present, in order to improve the pore structure and CO2 adsorption performance of activated carbon, a large amount of KOH or K2CO3 industrial activator is used in the preparation process of activated carbon. The long-term use of such activators not only causes equipment corrosion and serious environmental pollution, but also increases the cost of activated carbon preparation. At the same time, literature research shows that N atoms have similar structural properties to carbon atoms. When N atoms replace some carbon atoms in carbon materials through N doping, not only the pore structure performance of activated carbon adsorbent can be adjusted, but also the surface performance of the material can be adjusted, thereby improving the surface acidity and alkalinity of the activated carbon material and providing a large number of active sites for the adsorption of CO2 by the activated carbon adsorbent.

[0003] In addition, the desulfurization waste liquid produced in the coke oven gas desulfurization process is a mixed pollutant containing various toxic substances, mainly containing ammonium thiosulfate, ammonium thiocyanate, ammonium sulfate, ammonium sulfite, hydroquinone and suspended sulfur, etc. It cannot be directly treated by biochemical method, and cannot be directly discharged. Therefore, how to effectively treat the coking desulfurization waste liquid is a difficult problem to be solved by coking enterprises.

[0004] As a Chinese patent with application number CN202111178587.1, a biomass-based activated carbon material includes the following raw material components by weight: 1 part of mulan seed meal; 1-2 parts of pine bark. The invention uses mulan seed meal rich in mulan seed oil as raw material to prepare biomass-based activated carbon material, which can improve the utilization value of mulan seed meal. The invention uses desulfurization waste liquid as an activator, which can not only better solve the problem of difficult treatment of desulfurization waste liquid, but also reduce the amount of industrial activator and the cost of activated carbon material preparation. The invention uses mulan seed meal as raw material, which can fully utilize the residual mulan seed oil in the mulan seed meal. In-situ nitrogen element doping is carried out on the obtained biomass-based activated carbon material during carbonization and activation, the surface performance of the material is adjusted, the surface acidity and alkalinity of the activated carbon material is improved, and a large number of active sites are provided for the adsorption of CO2 by the activated carbon. The invention uses desulfurization waste liquid and amine sodium two-step activation to prepare biomass-based activated carbon material, which can reduce the activation temperature to 450-550℃, thereby reducing the energy consumption of activated carbon preparation.

[0005] The above scheme can solve the problem of difficult treatment of desulfurization waste liquid to some extent, but the quality of desulfurization waste liquid is unstable, which can easily lead to unstable quality of biomass-based activated carbon material. SUMMARY

[0006] The embodiment of the present application provides a biomass-based activated carbon material, solves the problem of unstable quality of biomass-based activated carbon material caused by unstable quality of desulfurization waste liquid in the prior art, and prepares the biomass-based activated carbon material with stable quality, further optimizes the pore structure of the biomass-based activated carbon material, and improves the adsorption performance.

[0007] The embodiment of the present application provides a biomass-based activated carbon material, and the biomass-based activated carbon material comprises the following components in parts by weight: 1 part of mulanzi meal and 1-2 parts of pine bark.

[0008] The preparation method of the biomass-based activated carbon material comprises the following steps:

[0009] Step S1, the mulanzi meal and the pine bark are dried at 120 DEG C respectively, crushed to 300-500 meshes, then mixed to obtain mixed raw material A;

[0010] Step S2, the mixed raw material A is put into an evaporator, the desulfurization waste liquid is gradually added into the mixed raw material A, stirring is performed while adding, meanwhile, the evaporator is started to perform low-temperature evaporation, the sulfate content in the mixture is monitored through a real-time monitoring system, when the sulfate content reaches a preset standard, the addition of the desulfurization waste liquid and the evaporation operation are stopped, and the mixed raw material A with high sulfate content is obtained;

[0011] Step S3, the mixed raw material A with high sulfate content is ultrasonically immersed for 2-6 h under the condition that the ultrasonic frequency is 25-40 kHz, and then dried at 100-150 DEG C; then carbonization and activation are performed for 2-4 h under the condition that the temperature is 500-700 DEG C and the carbonization and activation temperature rising rate is 5-8 DEG C / min, and the carbonization and activation is performed under the condition of air isolation, and mixed carbon material B is obtained;

[0012] Step S4, the mixed carbon material B and sodium amide are mixed according to the mass ratio 1:1-2, and then activated under the condition that the temperature is 450-550 DEG C and the activation temperature rising rate is 5-8 DEG C / min under the condition of air isolation for 1.5-3 h, and the biomass-based activated carbon material is obtained.

[0013] Further, in step S2, the solid-liquid ratio of the mixed raw material A and the desulfurization waste liquid is 1g / 5-20mL, the heating temperature is 50 DEG C, and the stirring speed is 300-500 rpm; the sulfate ion is not less than 4mol / L.

[0014] Further, the micropore volume of the biomass-based activated carbon material is 0.6-1.44cm / g.

[0015] Further, in step S4, part of the mixed carbon material B contains moisture.

[0016] Further, the mass ratio of the water-containing mixed carbon material B to the water-free mixed carbon material B is 1:1-3; the water content of the water-containing mixed carbon material B is 5%-10%.

[0017] Further, before mixing the mixed carbon material B with the sodium amide, the mixed carbon material B is subjected to water soaking treatment to form a mixed carbon material C.

[0018] Further, the water soaking treatment is specifically as follows: the mixed carbon material B is placed in a water soaking device for 1-2 hours to be fully soaked with water; the water-soaked mixed carbon material B is placed in a low-temperature volatilization device, and the temperature is controlled at 40-60℃ to volatilize part of the water and retain part of the water in the pores, so that the water content of the mixed carbon material B is 5%-10%.

[0019] The mixed material B retaining water is subjected to mechanical stirring at a speed of 200-300 rpm for 10-15 min to form the mixed carbon material C.

[0020] Further, the mixed carbon material C is mixed with the sodium amide at a mass ratio of 1:1-2, and the temperature is raised to 105-110℃, and the temperature is kept stable for 1 h to obtain the biomass-based activated carbon material.

[0021] Further, the mixed carbon material C is also subjected to water content control.

[0022] Further, the mixed material B is placed in clean water for full soaking, and stirring is accelerated to accelerate the dissolution of sulfuric acid and sulfate, and a filter is used to filter out water;

[0023] The mixed material B after filtering out water is placed in an oven at 50℃ for drying, and the sample is taken out every 10 min and weighed, and the weight data of the water loss process are recorded;

[0024] The mixed material after the first drying is soaked with water again, and a filter is used to filter out water, and according to the recorded weight data of the water loss process, the drying time is set in the oven at 50℃ to control the residual water content in the pores;

[0025] The mixed carbon material B after drying and water content control is mixed with the sodium amide at a mass ratio of 1:1-2 to obtain the mixed carbon material C with controlled water content.

[0026] The one or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0027] One, by low-temperature evaporation, gradually add desulfurization waste liquid to the mixed raw material A, and low-temperature heating evaporation, can effectively improve the content of sulfate in mixture A, through the setting of the pre-set standard, so that it reaches a relatively stable standard content, which solves the problem of unstable content of sulfate ion in desulfurization waste liquid, so as to ensure the stability of the quality of the subsequent carbonide; through detection, the adsorption capacity of carbon dioxide is improved from 3.24mmol / g to 3.30mmol / g, after 10 times of adsorption / desorption cycle, the adsorption capacity of biomass-based composite activated carbon can still reach 3.297mmol / g, the adsorption capacity only decreases by 0.06%; by using the way of low-temperature evaporation, the problem of unstable quality of carbonide caused by unstable quality of desulfurization waste liquid is solved, low-temperature evaporation evaporates water by heating, and solutes such as sulfate are left in the mixture, realizing the increase of the content of sulfate, the low-temperature evaporation improves the content of sulfate in the mixture, so as to prepare biomass-based activated carbon material with stable quality; the material has excellent pore structure and adsorption performance, and is especially suitable for carbon dioxide capture and separation;

[0028] Second, by containing part of the water in the pore of the mixed carbon material B, the water in the water-containing mixed carbon material B forms water vapor during the heating process, and the sodium amide reacts with the water vapor to expand the pore size and etch the surface of sodium hydroxide. The released gas and heat during the reaction process can further open and expand the pore structure of the carbon material, forming more micropores and mesopores, thereby enhancing the permeability and adsorption capacity of the activated carbon material;

[0029] Third, after the mixed carbon material B is fully soaked in water, it is then evaporated at low temperature to retain appropriate amount of water in the pores. The mixed carbon material B with appropriate amount of water is mixed uniformly by mechanical stirring. The water can be stably retained in the pores and will not flow out due to external force due to capillary action, thereby forming a stable mixed carbon material C. Through the reaction of sodium amide and water vapor in the pores, ammonia gas is released to impact the pores, increasing the pore structure. At the same time, sodium hydroxide produced during the reaction etches the carbonized surface, forming more and more uniform pores, improving the specific surface area and adsorption performance of the material, and preparing a biomass-based activated carbon material with high specific surface area, rich pore structure and excellent adsorption performance, which shows higher cycle stability in carbon dioxide adsorption;

[0030] Through water immersion treatment, the mixed carbon material B can more uniformly absorb water, so that the water in the pores is more uniformly distributed, thereby realizing more uniform pore expansion and surface etching effect in the subsequent reaction with sodium amide; the low-temperature evaporation treatment after water immersion can accurately control the amount of water retained in the pores, so as to more accurately control the reaction rate of sodium amide and the formation of pore structure, avoid excessive violent reaction leading to damage of pore structure, and realize more controllable reaction process;

[0031] Fourthly, by detecting the water loss in the drying process, the drying speed and the final moisture content of the mixture are mastered, which provides a basis for subsequent control of the residual moisture content in the pores; by controlling the drying time and temperature, the residual moisture content in the pores is accurately regulated, which provides a basic condition for the subsequent reaction amount of sodium amide and water; by controlling the moisture content in the pores, the reaction amount of sodium amide and water is regulated, and then the degree of hole expansion and the effect of sodium hydroxide etching surface are controlled, and the pore structure and surface performance of the activated carbon material are optimized; by accurately controlling the residual moisture content in the pores, the reaction amount of sodium amide and water is effectively regulated, and then the fine control of the degree of hole expansion and the sodium hydroxide etching surface is realized; this fine processing method further optimizes the pore structure and surface performance of the activated carbon material, and further improves the adsorption performance and cycle stability of the material. DETAILED DESCRIPTION

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the description herein is for describing the specific embodiments only and is not intended to be limiting of the application; the use herein of the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0033] Example one: a biomass-based activated carbon material, comprising the following components by weight parts: 1 part of mulanzi meal; 1-2 parts of pine bark;

[0034] The preparation method of the biomass-based activated carbon material specifically comprises the following steps:

[0035] Step S1. Dry the mulanzi meal and pine bark at 120℃ respectively, crush to 300-500 mesh, then mix to obtain mixed raw material A;

[0036] Step S2. Put the mixed raw material A into an evaporator, gradually add the desulfurization waste liquid to the mixed raw material A, stir while adding, at the same time, start the evaporator for low-temperature evaporation, monitor the sulfate content in the mixture through a real-time monitoring system, stop adding the desulfurization waste liquid and evaporation operation when the sulfate content reaches the preset standard, and obtain the mixed raw material A with high sulfate content;

[0037] Wherein, the solid-liquid ratio of the mixed raw material A and the desulfurization waste liquid is 1g / 5-20mL, the heating temperature is 50℃, and the stirring speed is 300-500rpm; the sulfate ion is not less than 4mol / L;

[0038] Step S3. The mixed raw material A with high sulfate content is ultrasonically immersed for 2-6h at an ultrasonic frequency of 25-40kHz, and then dried at 100-150℃; and then carbonized and activated for 2-4h at a temperature of 500-700℃ and a carbonization and activation temperature rising rate of 5-8℃ / min in an air-isolated condition, to obtain the mixed carbon material B;

[0039] Step S4. The obtained mixed carbon material B and sodium amide are mixed at a mass ratio of 1:1-2, and then activated in an air-isolated condition at a temperature of 450-550℃ and an activation temperature rising rate of 5-8℃ / min for 1.5-3h, to obtain the biomass-based activated carbon material.

[0040] The biomass-based activated carbon material has a micropore volume of 0.6-1.44cm / g.

[0041] The following experiments are conducted for the technical solution in the embodiment.

[0042] (1) Preparation of the biomass-based activated carbon material:

[0043] 20g of mulianzi meal and 30g of pine bark are dried at 120℃, and then ground to 400 mesh, respectively; and then the ground mulianzi meal and pine bark raw materials are mixed to obtain the mixed raw material A.

[0044] The mixed raw material A is placed in an evaporator, 500ml of desulfurization waste liquid is gradually added into the mixed raw material A, and stirred at a speed of 300rpm while adding, and the evaporator is started at the same time, and low-temperature evaporation is conducted at a temperature of 50℃ for 2h, to obtain the mixed raw material A with high sulfate content.

[0045] The mixed raw material A with high sulfate content is ultrasonically immersed for 2h at an ultrasonic frequency of 25kHz, and then dried at 100℃; and then carbonized and activated for 2h at 600℃ in a nitrogen atmosphere, at a carbonization and activation temperature rising rate of 5℃ / min, to obtain the mixed carbon material B.

[0046] The obtained mixed carbon material B and sodium amide are physically mixed at a mass ratio of 1:1, and then reactivated at 450℃ in a nitrogen atmosphere for 1.5h at an activation temperature rising rate of 5℃ / min, to finally obtain about 13g of the biomass-based activated carbon material.

[0047] (2) Performance test of the biomass-based activated carbon material:

[0048] The 3H-2000PS2 type specific surface and pore size analyzer produced by Beijing Biodas Instrument Technology Co., Ltd. is used to test the CO2 adsorption isotherm of the sample at 25℃. 0.15g of biomass-based composite activated carbon is filled in the test tube, the activated carbon is heated to 200℃ and kept for 4 hours to remove impurity gas in the sample. Then the temperature is reduced to 25℃, and adsorption is carried out in a carbon dioxide atmosphere. The carbon dioxide adsorption capacity of the biomass-based composite activated carbon under this condition is 3.30mmol / g.

[0049] The biomass-based composite activated carbon material is tested for 10 times of carbon dioxide adsorption and desorption by using the above-mentioned 3H-2000PS2 type specific surface and pore size analyzer, and the adsorption process is carried out at 25℃ in a 99.99% CO2 atmosphere, and the desorption process is carried out at 200℃. 0.15g of adsorbent is filled in the test tube, and the temperature is raised to 200℃ and kept for 4 hours. Then the temperature is reduced to 25℃, and adsorption is carried out in a carbon dioxide atmosphere. After the adsorption process is completed, the temperature is raised to 200℃ again, and the adsorbent is desorbed at 200℃ for 4 hours. Then the temperature is reduced to 25℃ again, and the adsorption reaction is carried out again in a carbon dioxide atmosphere. The above process is repeated for 10 times. Under this condition, after 10 times of adsorption / desorption cycle process, the adsorption capacity of the biomass-based composite activated carbon can still reach 3.297mmol / g, and the adsorption capacity decreases by only 0.06%. It shows that the biomass-based activated carbon has good carbon dioxide adsorption cycle stability.

[0050] The comparative example is prepared by the method of Chinese patent with application number CN202111178587.1, and the difference from the present scheme is that the evaporator is not used for low-temperature evaporation of the desulfurization waste liquid;

[0051] After detection, the carbon dioxide adsorption capacity of the biomass-based composite activated carbon of the comparative example is 3.24mmol / g; after 10 times of adsorption / desorption cycle, the adsorption capacity decreases to 3.237mmol / g, and the decrease rate is 0.1%.

[0052] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages:

[0053] By means of low-temperature evaporation, the desulfurization waste liquid is gradually added to the mixed raw material A, and low-temperature heating evaporation can effectively increase the content of sulfate in the mixture A. By setting a pre-set standard, it can reach a relatively stable standard content, which solves the problem of unstable content of sulfate ions in the desulfurization waste liquid, thereby ensuring the stability of the quality of the subsequent carbide. Through detection, the carbon dioxide adsorption capacity is increased from 3.24 mmol / g to 3.30 mmol / g. After 10 adsorption / desorption cycles, the adsorption capacity of the biomass-based composite activated carbon can still reach 3.297 mmol / g, and the adsorption capacity only decreases by 0.06%;

[0054] During the carbonization and activation process, the sulfate decomposes at high temperature to form acid etching effect, which can form pores on the carbonization surface. By accurately controlling the content of sulfate, the pore structure of the activated carbon material can be further optimized, the specific surface area and micropore volume can be increased, and the adsorption performance can be enhanced. At the same time, low-temperature evaporation and precise process control can reduce energy consumption and waste emissions.

[0055] By using the low-temperature evaporation method, the problem of unstable quality of the carbide caused by the unstable quality of the desulfurization waste liquid is solved. Low-temperature evaporation evaporates water by heating, and solutes such as sulfate are left in the mixture, achieving an increase in the content of sulfate. The low-temperature evaporation method increases the content of sulfate in the mixture, thereby preparing a biomass-based activated carbon material with stable quality. The material has excellent pore structure and adsorption performance, and is particularly suitable for carbon dioxide capture and separation.

[0056] This embodiment makes full use of the waste peony seed meal and pine bark resources, improves the added value, effectively treats the desulfurization waste liquid which is difficult to be directly discharged, reduces environmental pollution, reduces the preparation cost of activated carbon material, improves the economic benefit, and ensures the stability and consistency of the product through low-temperature evaporation and standardized treatment. The prepared biomass-based activated carbon material can be widely used in flue gas treatment, gas separation and other fields.

[0057] Example two: The above example one uses the low-temperature evaporation method to solve the problem of unstable quality of the carbide caused by the unstable quality of the desulfurization waste liquid, increases the content of sulfate in the mixture, and thereby prepares a biomass-based activated carbon material with excellent pore structure and stable quality. The adsorption performance of the biomass-based activated carbon material is improved. On the basis of example one, further improvement is made to improve the stability and adsorption performance of the biomass-based activated carbon material.

[0058] The mixed carbon material B also contains part of water, and the mass ratio of the water-containing mixed carbon material B to the mixed carbon material B without water is 1:1-3. The content of water in the water-containing mixed carbon material B is 5%-10%.

[0059] For the technical solution in this embodiment, on the basis of embodiment one, the following experiments are done: the mass ratio of the water-containing mixed carbon material B to the mixed carbon material B without water in the mixed carbon material B is 1:2, and the water content of the water-containing mixed carbon material B is 7.5%;

[0060] It is detected that the carbon dioxide adsorption capacity of the biomass-based composite activated carbon in this embodiment is 3.34 mmol / g; after 10 adsorption / desorption cycles, the adsorption capacity decreases to 3.338 mmol / g, and the decrease rate is 0.05%.

[0061] The technical solution in the above embodiments of the present application has at least the following technical effects or advantages:

[0062] By allowing the water-containing mixed carbon material B to contain part of water in the pores, the water forms water vapor during the heating process, and the sodium amide reacts with the water vapor, achieving the effects of expanding the pore size and etching the surface of sodium hydroxide. The gas and heat released during the reaction process can further open and expand the pore structure of the carbon material, forming more micropores and mesopores, thereby enhancing the permeability and adsorption capacity of the activated carbon material;

[0063] By controlling the ratio of water-containing and water-free mixed carbon material B in the mixed carbon material B and the water content of the water-containing mixed carbon material B, the reaction rate of sodium amide is controlled, and at the same time, the pore structure is finely controlled, avoiding excessive and violent reaction that damages the pore structure, achieving a more controllable reaction process, thereby preparing activated carbon materials with specific pore structures and adsorption properties to meet the needs of different application fields and improve the flexibility and adaptability of biomass-based activated carbon materials;

[0064] The reaction between water and sodium amide is an exothermic process. By increasing the temperature of the mixture during the reaction process, the reaction activity is enhanced, which can achieve more effective activation at a lower temperature, thereby saving energy and reducing production costs.

[0065] In the above embodiment two, the reaction of the water-containing mixed carbon material B and sodium amide is introduced to further expand the pore size and enhance the permeability and adsorption capacity of the activated carbon material. To improve the stability and adsorption performance of biomass-based activated carbon materials, further improvements are made on the basis of embodiment two.

[0066] Before mixing the mixed carbon material B with sodium amide, water immersion treatment is performed, specifically, the mixed carbon material B is placed in a water immersion device for 1-2 hours to allow it to fully absorb water, and the water is adsorbed in the pores;

[0067] The water-immersed mixed carbon material B is placed in a low-temperature volatilization device, and the temperature is controlled at 40-60°C to volatilize part of the water, leaving part of the water in the pores, so that the water content of the mixed carbon material B is 5%-10%.

[0068] The mixture B retaining water is subjected to mechanical stirring at a speed of 200-300 rpm for 10-15 min to form a mixed carbon material C;

[0069] The mixed carbon material C is mixed with sodium amide at a mass ratio of 1:1-2, and is heated to 105-110°C and kept at the temperature for 1 h to obtain the biomass-based activated carbon material.

[0070] For the technical solution in the embodiment, the following experiment is conducted on the basis of Embodiment Two: The mixed carbon material B is placed in a water immersion device for 1.5 hours to allow it to fully absorb water, and the water is adsorbed in the pores;

[0071] The mixed carbon material B after water immersion is placed in a low-temperature volatilization device, and the temperature is controlled at 40-60°C to allow part of the water to volatilize, and a part of the water is retained in the pores, so that the water content of the mixed carbon material B is 8%;

[0072] The mixture B retaining water is subjected to mechanical stirring at a speed of 250 rpm for 15 min to form a mixed carbon material C;

[0073] The mixed carbon material C is mixed with sodium amide at a mass ratio of 1:1.5, and is heated to 105-110°C and kept at the temperature for 1 h to obtain the biomass-based activated carbon material.

[0074] It is detected that the carbon dioxide adsorption capacity of the biomass-based composite activated carbon in the embodiment is 3.39 mmol / g, and after 10 adsorption / desorption cycles, the adsorption capacity decreases to 3.388 mmol / g, with a decrease rate of 0.05%.

[0075] The technical solution in the above embodiment of the application has at least the following technical effects or advantages:

[0076] After the mixed carbon material B is immersed in water, it fully absorbs water, and then through low-temperature volatilization, a proper amount of water is retained in the pores. Through mechanical stirring, the mixed carbon material B retaining a proper amount of water is uniformly mixed, and the water is stably retained in the pores and will not flow out due to external force because of capillary action, so that a stable mixed carbon material C is formed. Through the reaction of sodium amide and water vapor in the pores, ammonia gas is released to impact the pores and increase the pore structure, and sodium hydroxide produced in the reaction process etches the carbonized surface to form more and more uniform pores, thereby improving the specific surface area and adsorption performance of the material, and preparing a biomass-based activated carbon material with high specific surface area, rich pore structure and excellent adsorption performance, which exhibits higher cycle stability in carbon dioxide adsorption;

[0077] Through the water immersion treatment, the mixed carbon material B can more evenly absorb water, making the water distribution in the pores more uniform, so that in the subsequent reaction with sodium amide, more uniform pore expansion and surface etching effect can be achieved;

[0078] The low-temperature volatilization treatment after water immersion can accurately control the amount of water remaining in the pores, thereby more accurately regulating the reaction rate of sodium amide and the formation of pore structure, avoiding excessive violent reaction leading to the destruction of the pore structure, and realizing a more controllable reaction process;

[0079] The water remaining in the pores forms water vapor during the heating process, and after reacting with sodium amide, ammonia gas is released to impact the pores, and sodium hydroxide is produced to etch the carbonized surface, which can form more and more uniform micropores and mesopores, thereby optimizing the pore structure of the activated carbon material;

[0080] By optimizing the pore structure, the specific surface area and adsorption performance of the material are improved, so that the prepared biomass-based activated carbon material exhibits higher cycle stability in carbon dioxide adsorption; the activated carbon material with specific pore structure and adsorption performance can meet the needs of different application fields, improving the flexibility and adaptability of the biomass-based activated carbon material; due to the heat released during the reaction process, the temperature of the mixture is increased, and the reaction activity is enhanced, so that more effective activation can be achieved at a lower temperature, thereby saving energy and reducing production cost.

[0081] Example Four: The above-mentioned example three through water immersion treatment, the mixed carbon material B can more evenly absorb water, making the water distribution in the pores more uniform, so that in the subsequent reaction with sodium amide, more uniform pore expansion and surface etching effect can be achieved, in order to improve the stability and adsorption performance of the biomass-based activated carbon material quality, on the basis of example three, do further improvement.

[0082] The mixed carbon material C also controls the water content, specifically:

[0083] The mixed material B is placed in clean water for sufficient soaking, while stirring to accelerate the dissolution of sulfuric acid and sulfate, and a filter is used to filter out water;

[0084] The mixed material B after filtering out water is placed in an oven at 50°C for drying, and samples are taken every 10 minutes and weighed, and the weight data of the water loss process is recorded;

[0085] The mixed material after the first drying is soaked in water again, and a filter is used to filter out water, and according to the recorded weight data of the water loss process, the drying time is set in the oven at 50°C to control the residual water content in the pores;

[0086] The mixed carbon material B with controlled water content is mixed with sodium amide at a mass ratio of 1:1-2 to obtain a mixed carbon material C with controlled water content.

[0087] For the technical solutions in this embodiment, on the basis of Example Three, the following experiments are conducted: the mixed material B is placed in clean water for sufficient soaking, while stirring to accelerate the dissolution of sulfuric acid and sulfate, and a filter is used to filter out water;

[0088] The mixed material B after filtering out water is placed in an oven at 50°C for drying, and samples are taken every 10 minutes for weighing, and the weight data of the water loss process are recorded;

[0089] The mixture after the first drying is soaked with water again, and a filter is used to filter out water, and according to the recorded weight data of the water loss process, the drying time is set in the oven at 50°C to control the residual water content in the pores to be 10%;

[0090] The mixed carbon material B with controlled water content at 10% is mixed with sodium amide at a mass ratio of 1:1.5 to obtain a mixed carbon material C with controlled water content;

[0091] It is detected that the carbon dioxide adsorption capacity of the biomass-based composite activated carbon in this embodiment is 3.44 mmol / g, and after 10 adsorption / desorption cycles, the adsorption capacity decreases to 3.438 mmol / g, with a decrease rate of 0.04%.

[0092] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages:

[0093] By detecting the water loss during drying, the drying speed and the final water content of the mixture are mastered, providing a basis for subsequent control of the residual water content in the pores; by controlling the drying time and temperature, the residual water content in the pores is accurately controlled, providing a basic condition for the subsequent reaction amount of sodium amide and water; by controlling the water content in the pores, the reaction amount of sodium amide and water is controlled, and then the degree of hole expansion and the effect of sodium hydroxide etching the surface are controlled, and the pore structure and surface properties of the activated carbon material are optimized;

[0094] By accurately controlling the residual water content in the pores, the reaction amount of sodium amide and water is effectively controlled, and then the fine control of the degree of hole expansion and the etching of the surface by sodium hydroxide is realized; this fine processing method further optimizes the pore structure and surface properties of the activated carbon material, and further improves the adsorption performance and cycle stability of the material;

[0095] Due to the accurate control of the water content in the pores and the reaction degree, the scheme can more effectively utilize energy and raw materials in the preparation process, thereby reducing the production cost, and by adjusting the drying time and temperature and the like, the residual water content in the pores and the reaction degree can be flexibly controlled, the performance requirements of the activated carbon material in different application scenarios are met, and the adaptability and flexibility of the activated carbon material are further improved.

[0096] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A biomass-based activated carbon material, characterized by, By weight parts, including the following components: 1 part of mulanzi meal; 1-2 parts of pine bark; The preparation method of the biomass-based activated carbon material specifically comprises the following steps: Step S1. Dry the mulanzi meal and pine bark at 120℃ respectively, crush to 300-500 mesh, then mix to obtain mixed raw material A; Step S2. Put the mixed raw material A into an evaporator, gradually add the desulfurization waste liquid to the mixed raw material A while stirring, and start the evaporator at the same time to perform low-temperature evaporation. Monitor the sulfate content in the mixture through a real-time monitoring system. When the sulfate content reaches the preset standard, stop adding the desulfurization waste liquid and evaporation operation to obtain mixed raw material A with high sulfate content; Step S3. Ultrasonic dip the mixed raw material A with high sulfate content at an ultrasonic frequency of 25-40 kHz for 2-6 h, and then dry at 100-150℃. Then perform carbonization and activation at a temperature of 500-700℃ and a carbonization and activation temperature rising rate of 5-8℃ / min for 2-4 h. The carbonization and activation is performed in an air-tight condition to obtain mixed carbon material B; Before mixing the mixed carbon material B with sodium amide, perform water immersion treatment to form mixed carbon material C; The water immersion treatment specifically comprises the following steps: place the mixed carbon material B in a water immersion device for 1-2 hours to allow it to fully absorb water; place the water-immersed mixed carbon material B in a low-temperature volatilization equipment and control the temperature at 40-60℃ to allow part of the water to volatilize, leaving a part of water in the pores, so that the water content of the mixed carbon material B is 5%-10%; Mechanically stir the mixed material B retaining water at a speed of 200-300 rpm for 10-15 min to form mixed carbon material C; Mix the mixed carbon material C with sodium amide according to a mass ratio of 1:1-2, and heat to 105-110℃ and keep the temperature stable for 1 h to obtain the biomass-based activated carbon material.

2. The biomass-based activated carbon material according to claim 1, wherein In step S2, the solid-liquid ratio of the mixed raw material A to the desulfurization waste liquid is 1g / 5-20mL, the heating temperature is 50℃, and the stirring speed is 300-500 rpm. The sulfate ion content is not less than 4 mol / L.

3. The biomass-based activated carbon material of claim 1, wherein The micropore volume of the biomass-based activated carbon material is 0.6-1.44 cm3 / g.

4. The biomass-based activated carbon material of claim 1, wherein The water content of the mixed carbon material C is also controlled.

5. The biomass-based activated carbon material according to claim 4, wherein Place the mixed material B in clean water for full immersion, and stir to accelerate the dissolution of sulfuric acid and sulfate. Use a filter to remove water; Place the mixed material B after removing water in an oven at 50℃, take samples every 10 minutes and weigh them to record the weight data of the water loss process; Soak the mixed material after the first drying in water again, use a filter to remove water, and according to the recorded weight data of the water loss process, set the drying time in the oven at 50℃ to control the residual water content in the pores.