CN111017923B - Free radical induced controllable microspherical activated carbon and preparation method thereof - Google Patents
Free radical induced controllable microspherical activated carbon and preparation method thereof Download PDFInfo
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Abstract
The invention relates to free radical induced controllable microspherical activated carbon and a preparation method thereof, belongs to the field of activated carbon material preparation, and solves the problems of high reaction temperature and low reactant concentration in preparation of precursor materials in activated carbon materials in the prior art. A free radical induced controllable microspherical activated carbon is prepared from the following materials: water-soluble carbohydrates, free radical initiation catalysts, induced nucleation catalysts and hydroxides; water-soluble carbohydrates: free radical initiation catalyst: the molar concentration ratio of the induced nucleation catalyst ranges from 360:2:1 to 72:4: 1. The water-soluble carbohydrate is a combination of two or more carbohydrates selected from saccharides; the carbohydrate composition is comprised of polysaccharide molecules. The invention realizes the preparation of the activated carbon material with high specific surface area and small particle size.
Description
Technical Field
The invention relates to the technical field of high-performance activated carbon materials, in particular to a preparation method of a free radical induced controllable microspherical super activated carbon material.
Background
Due to the limitations of the process of preparing the activated carbon precursor material, most activated carbons have irregular particle shapes and non-uniform particle size distributions. And the shape of the activated carbon particles is irregular and the particle size distribution is not uniform, so that the application prospect of the material in various fields is limited. For example, irregular particle shapes can cause defects in the particle packing structure, affecting its application as an electrode material for energy storage devices; the non-uniform particle size distribution of the particles can cause the inevitable pressure difference between two ends of a particle accumulation layer, and directly limits the application of the activated carbon material in the aspect of preparing the environment-friendly adsorption material.
Therefore, in order to obtain a carbon material having a regular particle shape and a uniform particle size distribution, it is necessary to control the progress of the precursor material of the super-activated carbon. For super-activated carbon precursor materials, the particle morphology can be controlled at the precursor material synthesis stage. However, such methods are complicated to operate and expensive to produce, and are not suitable for the preparation of large amounts of the super activated carbon material. The precursor material of the spherical super-activated carbon material prepared by carbohydrate hydrothermal method in some domestic laboratories is a potential controllable preparation method. However, the prior art has the problems of high reaction temperature, long reaction time, low reaction concentration, low yield and the like.
Disclosure of Invention
In view of the above analysis, the present invention aims to provide a free radical induced controllable microspherical super activated carbon material and a preparation method thereof, which are used for solving the problems of high reaction temperature, long reaction time, low reaction concentration, low yield and the like in the existing activated carbon material preparation process.
The invention is realized by the following technical scheme:
a free radical induced controllable microspherical activated carbon is prepared from the following materials: a water-soluble carbohydrate, a free radical initiation catalyst, an induced nucleation catalyst; water-soluble carbohydrates: free radical initiation catalyst: the molar concentration ratio of the induced nucleation catalyst ranges from 360:2:1 to 72:4: 1;
further, the water-soluble carbohydrate is a combination of two or more carbohydrates among the carbohydrates; the carbohydrate combination contains polysaccharide molecules of varying degrees of polymerization.
Further, the free radical initiation catalyst comprises one or more of dibenzoyl peroxide, tert-butyl hydroperoxide and N-hydroxyphthalimide; the induced nucleation catalyst is one or more of ethyl acrylate, acrylamide and maleic anhydride.
A preparation method of free radical induced controllable microspherical activated carbon comprises the following steps:
step 1: preparing an activated carbon precursor material;
step 2: preparing an activated carbon primary carbonized product;
and step 3: carrying out activation reaction on the primary carbonized product of the activated carbon;
and 4, step 4: the micro-spherical super-active carbon is prepared.
Further, in the step 1, the water-soluble carbohydrate, the free radical initiation catalyst and the induced nucleation catalyst are mixed to obtain a mixed solution, the mixed solution is heated to the temperature of 100-220 ℃ and then is subjected to heat preservation, and the mixed solution is reacted at the temperature to prepare the activated carbon precursor material.
Further, in the step 2, the microspherical activated carbon precursor material is placed in a nitrogen atmosphere, the temperature is set to 400-1200 ℃, and the microspherical activated carbon precursor material is subjected to primary carbonization to obtain an activated carbon primary carbonization product.
Further, in the step 3, the primary carbonized product of the activated carbon is mixed with hydroxide in the nitrogen gas flow, and the mass ratio of the hydroxide to the primary carbonized product of the activated carbon is 2-10; the hydroxide and the primary carbonized product of the activated carbon are subjected to activation reaction at the temperature of 400-1000 ℃ to obtain an activated carbon activated product.
Further, the hydroxide is one or more of sodium hydroxide, potassium hydroxide and lithium hydroxide
Further, step 4, washing activated carbon activation products by deionized water, washing excessive hydroxide, and neutralizing by dilute nitric acid to obtain the microspherical activated carbon.
Furthermore, the primary carbonization treatment of the activated carbon is carried out in a corundum tube, the temperature rising rate is 1-10 ℃/min, and the time of the primary carbonization treatment is 0.5-3.0 h.
Further, the activation reaction was carried out in a high-temperature stainless steel tube, and the mixture of the primary carbonized product of activated carbon and hydroxide was placed in a nickel cassette.
Further, nitrogen is used as carrier gas for the primary carbonization reaction and the activation reaction; the nitrogen flow rate of the primary carbonization reaction is 60-600ml/min, and the nitrogen flow rate of the activation reaction is 80-800 ml/min.
Compared with the prior art, the invention can realize at least one of the following beneficial effects:
1. the invention provides free radical induced controllable microspherical activated carbon and a preparation method thereof, which can realize the formation of a controllable nucleation initiated carbon microsphere at a lower reaction temperature, the reaction temperature for preparing a carbon microsphere precursor material by a hydrothermal method in the prior art is controlled at 190-220 ℃, the preparation method of the free radical induced controllable microspherical activated carbon is completed by the synergistic action of an induced nucleation catalyst and a free radical initiated catalyst, the free radical initiated catalyst can release free radicals along with the temperature rise in a solution, and the free radicals can initiate the induced nucleation catalyst to polymerize to form macromolecules with a certain molecular weight. The interaction of the macromolecule and the carbon crystal nucleus formed by dehydration, condensation and aromatic cyclization of the carbohydrate molecule stabilizes the decomposition of the nucleation seeds, and reduces the reaction temperature to 150 ℃ which is lower than the preparation temperature of the precursor material in the prior art.
2. In the invention, regular super carbon microspheres can be prepared under high reaction concentration by the intervention of macromolecules of the induced nucleation catalyst formed by initiating the induced nucleation catalysis by the free radical-guided catalyst in the reaction growth process of the carbon microspheres, the reaction concentration of the water-soluble carbohydrate can reach 1.8mol/L, the yield of the prepared carbon microspheres is higher than 90%, and the specific surface area is larger than 2000m2Per g, up to 2600m2The carbohydrate concentration adopted in the reaction process is generally lower than 0.7 mol/L.
In the invention, the technical schemes can be combined with each other to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.
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The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.
Fig. 1 SEM image of super activated carbon particles.
Detailed Description
The invention provides a free radical induced controllable microspheric super activated carbon material, which comprises the following components: water soluble carbohydrates, free radical initiation catalysts, and induced nucleation catalysts.
The water soluble carbohydrate is saccharide compound including glucose, xylose, sucrose, and lactose; carbohydrate combinations are hydrolyzed mixtures containing polysaccharide molecules of varying degrees of polymerization, e.g., starch, hemicellulose, and cellulose.
The function of the free radical initiation catalyst is to controllably release free radicals under reaction conditions to initiate the formation of spherical cores. The mechanism of free radical generation is primarily the thermal decomposition of the free radical initiating catalyst at the reaction temperature. Free radical initiating catalysts include dibenzoyl peroxide, t-butyl hydroperoxide, N-hydroxyphthalimide.
The induced nucleation catalyst is mainly monomer molecules containing olefinic bonds, and the free radicals released by the free radical initiated catalyst initiate the polymerization of the monomer molecules in the induced nucleation catalyst under reaction conditions. Examples of the nucleation inducing catalyst include ethyl acrylate, acrylamide, and maleic anhydride.
The induced nucleation catalyst and the free radical initiation catalyst act synergistically to form a polymer sphere core structure. The free radical initiation catalyst releases free radicals in solution with the increase of temperature, and the free radicals initiate the polymerization of the nucleation catalyst (comprising ethyl acrylate, acrylamide and maleic anhydride) to form polymer macromolecules with certain molecular weight. The water-soluble carbohydrate forms tiny carbon nucleus seeds under the heating condition, and polymer macromolecules formed by the polymerization of the induced nucleation catalyst can capture the carbon nucleus seeds to prevent the carbon nucleus seeds from aggregating. The carbohydrate molecules are gradually further dehydrated and carbonized by taking the carbon core seeds as the center, thereby forming the carbon microspheres. In the process, polymer macromolecules formed by the induced nucleation catalyst are attached to the surface of the carbon microsphere, so that the aggregation of the carbon microsphere is prevented, and meanwhile, the solid-liquid interfacial tension is reduced, so that the precipitated carbon microsphere keeps a regular spherical shape.
The preparation method of the free radical induced controllable microsphere provided by the invention is completed by the synergistic effect of the induced nucleation catalyst and the free radical initiation catalyst. Free radical initiating catalysts release free radicals in solution with increasing temperature, and these free radicals initiate the polymerization of the induced nucleation catalyst (including ethyl acrylate, acrylamide, maleic anhydride) to form macromolecules with a certain molecular weight. These macromolecules interact with carbon nuclei formed by dehydration condensation and arylation of carbohydrate molecules to stabilize the nucleation seeds against decomposition, thereby lowering the reaction temperature to 150 ℃. The carbohydrate molecules are further subjected to isotropic dehydration condensation aromatic cyclization with surface functional groups by taking the carbon core seeds as the center gradually, so that the carbon microspheres are formed through gradual carbonization, macromolecules formed by the cooperation of the free radical initiation catalyst and the induced nucleation catalyst are attached to the surfaces of the carbon microspheres in the process, aggregation is prevented, and meanwhile, the solid-liquid interfacial tension is reduced, so that the precipitated carbon microspheres keep a regular spherical shape. Referring to fig. 1, the carbon microspherical activated carbon prepared by the method has a regular spherical structure, good particle dispersibility, no obvious adhesion and reasonable particle size distribution.
The preparation method provided by the invention is mainly realized by the following technical scheme:
(1) preparing an activated carbon precursor material;
mixing water-soluble carbohydrate, a free radical initiation catalyst and an induced nucleation catalyst to obtain a mixed solution, heating the mixed solution to 100-220 ℃, then preserving heat, and reacting the mixed solution at the temperature to prepare the activated carbon precursor material. The concentration of the free radical initiation catalyst in the mixed solution prepared from the carbon sphere precursor material is 0.005-0.05 mol/l, preferably 0.01-0.03 mol/l, the concentration range ensures that the induced nucleation precursor grows at a controllable speed, and the phenomena of too fast reaction early stage and uneven particle size distribution in the reaction later stage are avoided. The concentration of the induced nucleation catalyst in the mixed solution prepared from the carbon sphere precursor material is 0.01-0.2mol/l, preferably 0.05-0.1mol/l, and the concentration ensures that the induced nucleation catalyst is kept in a certain molecular weight distribution, and avoids the phenomenon that the induced nucleation activity is lost due to self-aggregation.
Mixing a water-soluble carbohydrate, a free radical initiation catalyst, and an induction nucleation catalyst according to the weight ratio of water-soluble carbohydrate: free radical initiation catalyst: preparing a mixed solution by using the concentration ratio of the induced nucleation catalyst within the range of 360:2: 1-72: 4:1, adding the prepared mixed solution into a stainless steel reaction container with a polytetrafluoroethylene lining, and standing and heating the mixed solution at 100-220 ℃ for 1-10 hours. The heating temperature is preferably 140-200 ℃, and the treatment time is preferably 3-6 h. Under the conditions of the temperature range and the operation time, the high synthesis yield of the carbon precursor material can be realized, the regular physical appearance and the uniform particle size distribution of the microspherical carbon material are ensured, and the particle size of the carbon microsphere is concentrated to 4.6-5.6 um. The mixed solution was cooled to room temperature, and filtered to obtain an activated carbon precursor material. The activated carbon precursor material is washed by deionized water until the pH value is neutral, and the washing function is to remove acidic micromolecules in the precursor material and ammonium ions and other pollutants formed by nitrogen-containing compounds. Drying the washed activated carbon precursor material at 105 DEG C
(2) Preparing an activated carbon primary carbonized product;
placing the activated carbon precursor material in a nitrogen atmosphere, setting the temperature to be 400-1200 ℃, and carrying out primary carbonization on the microspherical activated carbon precursor material to obtain an activated carbon primary carbonized product.
The prepared activated carbon precursor material is subjected to primary carbonization treatment, the primary carbonization treatment is carried out in a corundum tube, the activated carbon precursor material is placed in a corundum crucible, the performance of the corundum tube is stable under the high-temperature condition, and the corundum tube is suitable for the corundum crucible. The carbonization temperature is set to be 400-1200 ℃, preferably 500-900 ℃, the primary carbonization process is to further remove impurity atoms in the raw materials and remove volatile micromolecules, and the operation in the carbonization temperature range can effectively improve the carbon content of the active carbon precursor material to be more than 95%. The temperature rise rate of the primary carbonization process is 1-10 ℃/min, preferably 3-7 ℃/min, and the temperature rise rate can prevent the activated carbon precursor material from generating heat-induced aggregation in the primary carbonization process. The whole primary carbonization treatment process is carried out under the nitrogen protection atmosphere, the nitrogen flow is 60-600ml/min, preferably 200-400ml/min, the nitrogen is used as carrier gas, the cost is low, secondary pollution is avoided, the nitrogen flow is set according to the discharge rate of small molecular volatile matters in the primary carbonization process, and the flow range is selected to effectively take the volatile matters away from the surface of the raw material. The time of the primary carbonization treatment is 0.5 to 3.0 hours, preferably 1.0 to 2.0 hours. The treated material was cooled to room temperature in a nitrogen stream to obtain an activated carbon primary carbonized product. The primary carbonization treatment aims to form a more dense carbon structure, remove heteroatoms from the structure, and further increase the mechanical strength of the spherical structure. The direct activation treatment with the activated carbon precursor material without primary carbonization treatment can directly cause the destruction of the spherical structure, and the purpose of activating and pore-forming can not be achieved due to the existence of a large amount of volatile molecules.
(3) Carrying out activation reaction on the primary carbonized product of the activated carbon;
mixing the primary carbonized product of the activated carbon with hydroxide in a nitrogen gas flow, and carrying out an activation reaction at the temperature of 400-1000 ℃ to obtain an activated carbon activated product.
The method comprises the steps of placing the primary carbonized product of the activated carbon in a high-temperature stainless steel tube for activation reaction, placing a mixed sample of the primary carbonized product of the activated carbon and hydroxide in a nickel box, enabling the hydroxide to have strong corrosion action on corundum, quartz and the like under a high-temperature condition, enabling the high-temperature stainless steel and metal nickel to be resistant to the corrosion action of the hydroxide at a high temperature, and placing the raw materials in a nickel container for treatment to prevent heteroatom pollution caused by the fact that the hydroxide corrodes equipment. Examples of the hydroxide used for activating the primary carbonized product of activated carbon include sodium hydroxide, potassium hydroxide, and lithium hydroxide. The mass ratio of the hydroxide to the primary carbonized product of the activated carbon is 2-10, preferably 3-6, and the selection of the ratio range is favorable for fully impregnating the primary carbonized product after the hydroxide is melted in the reaction process, so that the reaction pore-forming is further effectively completed. The temperature during the activation reaction is 400-1000 deg.C, preferably 500-850 deg.C. The heating rate in the activation process is 1-10 ℃/min, preferably 2-6 ℃/min. The activation reaction process of the primary carbonized product of the activated carbon is carried out under the nitrogen protection atmosphere, the nitrogen flow is 80-800ml/min, preferably 200-500ml/min, and the activation time is 0.2-3.0 h, preferably 0.8-2.0 h. The main principle of the activation process is that sodium or potassium atoms are intercalated to cause the structure to expand to generate structural pores, and the sodium or potassium atoms are generated by the direct action of hydroxide and carbon under the heated condition. In the intercalation process, a high porosity can be formed in the rapid temperature rise process, and a high hole making effect is generated. The selection of the reaction conditions is favorable for realizing the efficient activation pore-forming of the primary carbonized product by the hydroxide. The activation process adopts nitrogen as carrier gas, mainly considering the cost problem, other inert gases such as argon can be used, but the cost is higher, and the activation process is not suitable for a large number of long-time operation conditions.
(4) Preparing micro-spherical super active carbon;
washing the activated carbon activation product by deionized water, washing off excessive hydroxide, and neutralizing by 5% dilute nitric acid to obtain the microsphere-type super activated carbon.
The activated carbon primary carbonized product after completion of activation was cooled to room temperature in a nitrogen stream. Washing the activated carbon activation product by deionized water, washing off excessive hydroxide, and neutralizing by 5% dilute nitric acid to obtain the microsphere-type super activated carbon. The induced nucleation catalyst and the free radical initiation catalyst act synergistically to form a polymer sphere core structure. Free radical initiating catalysts release free radicals in solution with increasing temperature, and these free radicals initiate the polymerization of the induced nucleation catalyst (including ethyl acrylate, acrylamide, maleic anhydride) to form macromolecules with a certain molecular weight. The water-soluble carbohydrate can form tiny carbon nucleus seeds under the heating condition, macromolecules formed by the polymerization of the induced nucleation catalyst can capture the carbon nucleus seeds to prevent the aggregation of the carbon nucleus seeds, the carbohydrate molecules can gradually take the carbon nucleus seeds as the center for further dehydration and carbonization to form the carbon microspheres, the macromolecules formed by the induced nucleation catalyst can be attached to the surfaces of the carbon microspheres in the process to prevent the aggregation, and meanwhile, the solid-liquid interface tension is reduced to ensure that the precipitated carbon microspheres keep a regular spherical shape.
Example 1
The invention provides a free radical induction controllable microspherical super activated carbon preparation material which comprises glucose, a free radical initiation catalyst, an induction nucleation catalyst and potassium hydroxide. Wherein the concentration of glucose was 1.8mol/l, the amounts of the radical initiation catalyst and the nucleation inducing catalyst used were as shown in Table 1.
The preparation method provided by the invention is mainly realized by the following technical scheme:
(1) preparing an activated carbon precursor material;
32.4g of glucose, a free radical initiation catalyst and an induced nucleation catalyst are mixed to prepare 100ml of mixed solution, and the mixed solution is added into a stainless steel reaction vessel with a polytetrafluoroethylene lining. The stainless steel reactor was heated at 150 ℃ for 5.5 h. And after the heating reaction is finished, cooling the stainless steel reactor to room temperature, and filtering the mixed solution to obtain the activated carbon precursor material. The obtained activated carbon precursor material was washed with deionized water until the pH was neutral, and the activated carbon precursor material was dried at 105 ℃.
(2) Preparing an activated carbon primary carbonized product;
the primary carbonization treatment was performed in a corundum tube, and the activated carbon precursor material obtained above was placed in a corundum crucible. The primary carbonization treatment temperature was set at 800 ℃. The whole primary carbonization treatment process is carried out under the nitrogen protection atmosphere, and the nitrogen flow is 300 ml/min. The time for the primary carbonization treatment was 1.5 hours. The activated carbon precursor material is subjected to primary carbonization treatment to obtain an activated carbon primary carbonization product, and the activated carbon primary carbonization product is placed in nitrogen flow to be cooled to room temperature.
(3) Carrying out activation reaction on the primary carbonized product of the activated carbon;
and placing the primary carbonized product of the activated carbon and potassium hydroxide in a nickel box in a layered and tiled mode, placing the nickel box in a high-temperature resistant stainless steel tube for activation reaction, and cooling to room temperature in nitrogen airflow to obtain the microspheric super activated carbon material. Wherein the mass ratio of the potassium hydroxide to the primary carbonized product of the activated carbon is 4.5. The temperature during the activation reaction was 700 ℃. The temperature rise rate in the treatment process is 4 ℃/min. The activation reaction process is carried out under the nitrogen protection atmosphere, and the nitrogen flow is 350 ml/min. The time for the activation reaction was 1.5 h.
(4) Preparing micro-spherical super active carbon;
and (3) neutralizing the excessive hydroxide on the surface of the activated carbon material by using dilute nitric acid to obtain the microspherical super activated carbon. The properties of the super activated carbon are shown in table 2.
Table 1: free radical initiation catalyst and induced nucleation catalyst usage
TABLE 2 Properties of super-activated carbons
Example 2
The invention provides a preparation material of free radical induced controllable microspheric super active carbon, which comprises carbohydrate, N-hydroxyphthalimide, maleic anhydride and potassium hydroxide. Wherein the N-hydroxyphthalimide concentration is 0.025mol/l, the maleic anhydride concentration is 0.1mol/l, and the type of carbohydrate used, the addition concentration, and the reaction temperature were carried out according to the data in Table 3.
The preparation method provided by the invention is mainly realized by the following technical scheme:
(1) preparing an activated carbon precursor material;
carbohydrate, 0.41g N-hydroxyphthalimide (0.025 mol/l) and 0.1g maleic anhydride (0.1 mol/l) are mixed to prepare 100ml of mixed solution, and the mixed solution is added into a stainless steel reaction vessel with a polytetrafluoroethylene lining. The reaction conditions therein were carried out according to the data in Table 3. And after the heating reaction is finished, cooling the stainless steel reactor to room temperature, and filtering the mixed solution to obtain the activated carbon precursor material. The obtained activated carbon precursor material was washed with deionized water until the pH was neutral, and the activated carbon precursor material was dried at 105 ℃.
(2) Preparing an activated carbon primary carbonized product;
the primary carbonization treatment was performed in a corundum tube, and the activated carbon precursor material obtained above was placed in a corundum crucible. The primary carbonization treatment temperature was set at 800 ℃. The whole primary carbonization treatment process is carried out under the nitrogen protection atmosphere, and the nitrogen flow is 300 ml/min. The time for the primary carbonization treatment was 1.5 hours. The activated carbon precursor material is subjected to primary carbonization treatment to obtain an activated carbon primary carbonization product, and the activated carbon primary carbonization product is placed in nitrogen flow to be cooled to room temperature.
(3) Carrying out activation reaction on the primary carbonized product of the activated carbon;
and placing the primary carbonized product of the activated carbon and potassium hydroxide in a nickel box in a layered and tiled mode, placing the nickel box in a high-temperature resistant stainless steel tube for activation reaction, and cooling to room temperature in nitrogen airflow to obtain the microspheric super activated carbon material. Wherein the mass ratio of the potassium hydroxide to the primary carbonized product of the activated carbon is 4.5. The temperature during the activation reaction was 700 ℃. The temperature rise rate in the treatment process is 4 ℃/min. The activation reaction process is carried out under the nitrogen protection atmosphere, and the nitrogen flow is 350 ml/min. The time for the activation reaction was 1.5 h.
(4) Preparing micro-spherical super active carbon;
and (3) neutralizing the excessive hydroxide on the surface of the activated carbon material by using dilute nitric acid to obtain the microspherical super activated carbon, wherein the properties of the prepared super activated carbon microsphere are shown in Table 4.
TABLE 3 carbohydrate type, concentration and reaction conditions
TABLE 4 Properties of super-activated carbons
Example 3
The invention provides a free radical induced controllable microspheric super activated carbon material, which comprises 100ml of mixed solution prepared from 32.4g of glucose, 0.41g N-hydroxyphthalimide (molar concentration) and 0.1g of maleic anhydride (molar concentration). The preparation method provided by the invention is mainly realized by the following technical scheme:
(1) preparing an activated carbon precursor material;
adding the mixed solution into a stainless steel reaction vessel with a polytetrafluoroethylene lining, standing and heating at the temperature of 150 ℃ for 5.5 h. And after the reaction is finished, cooling to room temperature, filtering to obtain a carbon sphere precursor material, washing with deionized water until the pH value is neutral, and drying the solid material at 105 ℃.
(2) Preparing an activated carbon primary carbonized product;
the primary carbonization treatment was carried out in a corundum tube, and the treated sample was placed in a corundum crucible. The conditions of the primary carbonization treatment were carried out in accordance with the data in Table 5. The treated material was cooled to room temperature in a nitrogen stream.
(3) Carrying out activation reaction on the primary carbonized product of the activated carbon;
the material subjected to primary carbonization is subjected to activation reaction in a high-temperature resistant stainless steel pipe, and carbon powder and potassium hydroxide are placed in a nickel box in a layered and flat-laying manner. Wherein the mass ratio of the potassium hydroxide to the carbon powder is 4.5. The temperature during the activation reaction was 700 ℃. The temperature ramp rate during the treatment was 4 deg.C/min. The whole activation reaction process is carried out under the nitrogen protection atmosphere, and the nitrogen flow is 350 ml/min. The time for the activation reaction was 1.5 h. The treated material was cooled to room temperature in a nitrogen stream.
(4) Preparing micro-spherical super active carbon;
washing off excessive hydroxide by using deionized water, and neutralizing by using dilute nitric acid to obtain the microspherical super-active carbon, wherein the basic properties of the prepared carbon microsphere are shown in table 6 (the basic properties are shown in table 6).
TABLE 5 Primary carbonization treatment conditions
TABLE 6 basic properties of the carbosphere
Example 4
The invention provides a preparation material of free radical induced controllable microspheric super active carbon, which comprises glucose, N-hydroxyphthalimide, maleic anhydride and hydroxide. 100ml of the mixed solution, wherein 32.4g of glucose (concentration of 1.8mol/l), 0.41g of N-hydroxyphthalimide (concentration of 0.025mol/l) and 0.1g of maleic anhydride are contained.
The preparation method provided by the invention is mainly realized by the following technical scheme:
(1) preparing an activated carbon precursor material;
the glucose, the N-hydroxyphthalimide and the maleic anhydride are mixed to prepare 100ml of mixed solution, and the mixed solution is added into a stainless steel reaction vessel with a polytetrafluoroethylene lining. The stainless steel reactor was heated at 150 ℃ for 5.5 h. And after the heating reaction is finished, cooling the stainless steel reactor to room temperature, and filtering the mixed solution to obtain the activated carbon precursor material. The obtained activated carbon precursor material was washed with deionized water until the pH was neutral, and the activated carbon precursor material was dried at 105 ℃.
(2) Preparing an activated carbon primary carbonized product;
the primary carbonization treatment was performed in a corundum tube, and the activated carbon precursor material obtained above was placed in a corundum crucible. The primary carbonization treatment temperature was set at 800 ℃. The whole primary carbonization treatment process is carried out under the nitrogen protection atmosphere, and the nitrogen flow is 300 ml/min. The time for the primary carbonization treatment was 1.5 hours. The activated carbon precursor material is subjected to primary carbonization treatment to obtain an activated carbon primary carbonization product, and the activated carbon primary carbonization product is placed in nitrogen flow to be cooled to room temperature.
(3) Carrying out activation reaction on the primary carbonized product of the activated carbon;
and placing the primary carbonized product of the activated carbon and the hydroxide in a nickel box in a layered and tiled mode, placing the nickel box in a high-temperature resistant stainless steel tube for activation reaction, and cooling to room temperature in nitrogen airflow to obtain the microspheric super activated carbon material. The layered tiling mode is to tile the primary carbonized product in a nickel box in advance, and then tile the calculated amount of hydroxide powder on a carbon powder layer to form a two-layer tiling with a lower layer of carbon powder and an upper layer of hydroxide. Physical milling mixing refers to subjecting the primary carbonized product to mechanical agitation milling mixing at 300r/min for 1.0 minute with a calculated amount of hydroxide. Specific preparation conditions were carried out according to the data in table 7. The temperature during the activation reaction was 700 ℃. The temperature rise rate in the treatment process is 4 ℃/min. The activation reaction process is carried out under the nitrogen protection atmosphere, and the nitrogen flow is 350 ml/min. The time for the activation reaction was 1.5 h.
(4) Preparing micro-spherical super active carbon;
and (3) neutralizing the excessive hydroxide on the surface of the activated carbon material by using dilute nitric acid to obtain the microspherical super activated carbon.
Table 7: the active carbon primary carbonized material and the hydroxide are used
Example 5
The invention provides a preparation material of free radical induced controllable microspherical super active carbon, which comprises glucose, N-hydroxyphthalimide, maleic anhydride and potassium hydroxide. 100ml of the mixed solution, wherein 32.4g of glucose, 0.41g of N-hydroxyphthalimide and 0.1g of maleic anhydride are contained.
The preparation method provided by the invention is mainly realized by the following technical scheme:
(1) preparing an activated carbon precursor material;
the glucose, the free radical initiation catalyst and the induced nucleation catalyst are mixed to prepare 100ml of mixed solution, and the mixed solution is added into a stainless steel reaction vessel with a polytetrafluoroethylene lining. The stainless steel reactor was heated at 150 ℃ for 5.5 h. And after the heating reaction is finished, cooling the stainless steel reactor to room temperature, and filtering the mixed solution to obtain the activated carbon precursor material. The obtained activated carbon precursor material was washed with deionized water until the pH was neutral, and the activated carbon precursor material was dried at 105 ℃.
(2) Preparing an activated carbon primary carbonized product;
the primary carbonization treatment was performed in a corundum tube, and the activated carbon precursor material obtained above was placed in a corundum crucible. The primary carbonization treatment temperature was set at 800 ℃. The whole primary carbonization treatment process is carried out under the nitrogen protection atmosphere, and the nitrogen flow is 300 ml/min. The time for the primary carbonization treatment was 1.5 hours. The activated carbon precursor material is subjected to primary carbonization treatment to obtain an activated carbon primary carbonization product, and the activated carbon primary carbonization product is placed in nitrogen flow to be cooled to room temperature.
(3) Carrying out activation reaction on the primary carbonized product of the activated carbon;
and placing the primary carbonized product of the activated carbon and potassium hydroxide in a nickel box in a layered and tiled mode, placing the nickel box in a high-temperature resistant stainless steel tube for activation reaction, and cooling to room temperature in nitrogen airflow to obtain the microspheric super activated carbon material. Wherein the mass ratio of the potassium hydroxide to the primary carbonized product of the activated carbon is 4.5. The conditions for the activation reaction process were carried out according to the data in Table 8. The activation reaction process is carried out under the nitrogen protection atmosphere, and the nitrogen flow is 350 ml/min. The time for the activation reaction was 1.5 h.
(4) Preparing micro-spherical super active carbon;
and (3) neutralizing the excessive hydroxide on the surface of the activated carbon material by using dilute nitric acid to obtain the microspherical super activated carbon.
Table 8: conditions for activating the reaction process
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Claims (8)
1. A preparation method of free radical induced controllable microspherical activated carbon is characterized in that the preparation material of the free radical induced controllable microspherical activated carbon comprises the following steps: water-soluble carbohydrates, free radical initiation catalysts, induced nucleation catalysts; the water-soluble carbohydrate: free radical initiation catalyst: the molar concentration ratio of the induced nucleation catalyst is 360:2: 1-72: 4: 1;
the free radical initiation catalyst is one or more of dibenzoyl peroxide, tert-butyl hydroperoxide and N-hydroxyphthalimide; the induced nucleation catalyst is one or more of ethyl acrylate, acrylamide and maleic anhydride;
the preparation method comprises the following steps:
step 1: preparing an activated carbon precursor material;
in the step 1, mixing a water-soluble carbohydrate, a free radical initiation catalyst and an induced nucleation catalyst to obtain a mixed solution, heating the mixed solution to the temperature of 100-220 ℃, and then carrying out heat preservation on the mixed solution, wherein the mixed solution reacts at the temperature to prepare an activated carbon precursor material;
the concentration of the water-soluble carbohydrate is 32.4-63g/100 mL;
step 2: preparing an activated carbon primary carbonized product;
in the step 2, the microspherical activated carbon precursor material is placed in a nitrogen atmosphere, the temperature is set to 400-1200 ℃, and the microspherical activated carbon precursor material is subjected to primary carbonization to obtain an activated carbon primary carbonization product;
the primary carbonization treatment of the activated carbon is carried out in a corundum tube, the temperature rising rate is 1-10 ℃/min, and the time of the primary carbonization treatment is 0.5-3.0 h;
and step 3: carrying out activation reaction on the primary carbonized product of the activated carbon;
in the step 3, the activated carbon primary carbonized product is mixed with hydroxide in a nitrogen gas flow, the mass ratio of the hydroxide to the activated carbon primary carbonized product is 2-10, and the hydroxide and the activated carbon primary carbonized product are subjected to an activation reaction at the temperature of 400-1000 ℃ to obtain an activated carbon activated product;
and 4, step 4: the micro-spherical super-active carbon is prepared.
2. The method as claimed in claim 1, wherein in step 1, the water-soluble carbohydrate, the radical initiation catalyst and the nucleation inducing catalyst are mixed to obtain a mixed solution, the mixed solution is heated to a temperature of 150 ℃ to 220 ℃ and then is subjected to heat preservation, and the mixed solution is reacted at the temperature to prepare the activated carbon precursor material.
3. The method as claimed in claim 1, wherein in step 2, the microspherical activated carbon precursor material is placed in a nitrogen atmosphere at a temperature of 800-1200 ℃ to perform primary carbonization on the microspherical activated carbon precursor material to obtain the activated carbon primary carbonized product.
4. The method as claimed in claim 1, wherein in step 3, the primary carbonized product of activated carbon is mixed with hydroxide in a nitrogen gas flow, the mass ratio of hydroxide to the primary carbonized product of activated carbon is 4.5-10, and the hydroxide and the primary carbonized product of activated carbon are activated at 1000 ℃ to obtain the activated carbon activated product.
5. The method for preparing a free radical induced controllable microspherical activated carbon as claimed in claim 1, wherein said step 4 comprises washing activated carbon activation products with deionized water, washing off excess hydroxide, and neutralizing with dilute nitric acid to obtain microspherical activated carbon.
6. The method for preparing the free radical induced controllable microspherical activated carbon according to claim 3, wherein the primary carbonization treatment of the activated carbon is carried out in a corundum tube, the temperature rise rate is 4-10 ℃/min, and the time of the primary carbonization treatment is 1.5.5-3.0 h.
7. The method for preparing the free radical induced controllable microspherical activated carbon as claimed in claim 4, wherein the activation reaction is performed in a high temperature stainless steel tube, and the mixture of the primary carbonized product of the activated carbon and the hydroxide is placed in a nickel box.
8. The method for preparing the free radical induced controllable microspherical activated carbon as claimed in claim 4 or 5, wherein nitrogen is used as a carrier gas for the primary carbonization reaction and the activation reaction; the nitrogen flow rate of the primary carbonization reaction is 60-600ml/min, and the nitrogen flow rate of the activation reaction is 80-800 ml/min.
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| CN108383117A (en) * | 2017-09-01 | 2018-08-10 | 深圳市环球绿地新材料有限公司 | High performance spherical activated carbon, preparation method and use |
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| CN107640757A (en) * | 2017-09-07 | 2018-01-30 | 中南大学 | A kind of preparation method of compound carbosphere and compound carbosphere and its lithium-ion capacitor being prepared |
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