CN113149006A - Method for preparing capacitance carbon by using biomass rich in lignin as raw material - Google Patents
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Abstract
The invention discloses a method for preparing capacitance carbon by using biomass rich in lignin as a raw material, which comprises the following steps: (1) pretreatment: cutting off, washing and drying the biomass raw material; (2) hydrothermal coal gasification pretreatment: adding water and hydrogen peroxide into a biomass raw material, keeping the mixture in a hydrothermal kettle at 180-220 ℃ for 2-3 hours, and drying the mixture; (3) material preparation and aging: mixing the hydrothermal raw material carbon powder with an activating agent and an auxiliary activating agent, grinding and aging; (4) carbonization-activation: preserving the heat of the mixture at 850-880 ℃ for 1-1.5 hours, and cooling to room temperature; (5) and (3) capacitor carbon post-treatment: and (4) washing the carbonized material with water, pickling, washing with water, drying and grinding to obtain the capacitive carbon. (6) And (3) recovering an activating agent: and recovering the activating agent from the filtrate of the carbonized material water washing for recycling. The capacitance carbon produced by the invention has large specific surface, high yield, less ash content and low cost, and hardly generates tar and organic gas, and more than 80 percent of activating agent can be recycled.
Description
Technical Field
The invention relates to the technical field of preparation of capacitance carbon, in particular to a method for preparing capacitance carbon by using biomass rich in lignin as a raw material.
Background
The lignin is the second major component of biomass, is a high molecular resin of three phenolic monomers, has an aromatic ring structure with carbon atoms in sp2 state, is easy to graphitize during carbonization, generates graphite crystals, and is the best raw material for manufacturing capacitance carbon. The coconut shell has the highest lignin content of 42 percent and hard texture in various biomasses, is the accepted best raw material for firing the activated carbon for the supercapacitor, is short in supply and has rising price year by year. Meanwhile, in the traditional two-step method of carbonization and activation, the coconut shell is used for firing coconut shell charcoal, 1 ton of coconut shell charcoal can be produced generally only by 3 to 5 tons of coconut shells, KOH is used as an activating agent, 1 ton of capacitance charcoal can be obtained only by activating 2 to 3 tons of coconut shell charcoal, namely 1 ton of capacitance charcoal can be produced only by 6 to 15 tons of coconut shells, and a large amount of tar and smoke are produced, so that the pollution is large, the cost is high, and the quality is limited.
The method for firing the capacitance carbon by using the biomass raw material generally comprises the following two steps of carbonization and activation: firstly, the biomass raw material is carbonized at the temperature of 400 ℃ to 650 ℃, and then the carbonized material is activated into capacitance carbon at high temperature by a physical activation or chemical activation method. When the biomass raw material is carbonized, a large amount of water vapor, volatile gas and tar are generated, the yield is low, and the pollution is serious. Many biomass raw materials are mixed with a large amount of dust and silt, and the raw material quality can not be guaranteed, so that the capacitance carbon of domestic manufacturers has high ash content, many impurities, low conductivity, small specific surface and incapable product quality guarantee. On the other hand, the technologies for activating the carbonized biomass materials are limited, and both the physical activation method and the chemical activation method are developed to the utmost extent, and new methods are difficult to be developed. The physical activation method using water vapor and carbon dioxide gas has the disadvantages of complicated equipment, high energy consumption, long time and limited effect; chemical activation methods using activators such as potassium hydroxide, phosphoric acid, and zinc chloride cause serious pollution and serious corrosion of equipment.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides a method for preparing capacitance carbon by using biomass rich in lignin as a raw material, the capacitance carbon produced by the invention has the advantages of large specific surface, high yield, less ash content, low cost, almost no tar and organic gas, and more than 80 percent of alkali activating agents can be recycled.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a method for preparing capacitance carbon by using biomass rich in lignin as a raw material comprises the following steps:
(1) pretreatment of a biomass raw material: crushing or cutting the biomass raw material into sections or blocks, cleaning and drying to obtain the biomass raw material;
(2) hydrothermal coal gasification pretreatment: adding water and aqueous hydrogen peroxide into a biomass raw material, heating to 180-220 ℃, keeping for 2-3 hours to perform a coalification reaction, washing, and drying to constant weight to obtain hydrothermal biomass charcoal;
(3) material preparation and aging: adding an activating agent and an auxiliary activating agent into hydrothermal biomass charcoal, mixing and grinding to obtain a mixture, and aging the mixture for more than 6 hours in a drying environment at 50-70 ℃;
the activating agent is potassium salt or sodium salt, and the co-activating agent is urea;
(4) carbonization-activation: heating the aged mixture to 850-880 ℃, preserving heat for 1-1.5 hours, and cooling to room temperature to obtain a carbonized material;
(5) and (3) capacitor carbon post-treatment: and (4) washing the carbonized material by a first round of water washing, acid washing and a second round of water washing in sequence, drying and grinding to obtain the capacitance carbon.
Further, the biomass raw material in the step (1) is a lignin-rich biomass raw material.
Furthermore, the biomass raw material is not limited to coconut palm, and other biomass raw materials rich in lignin, such as coconut shell, palm, moso bamboo and the like, can also be used. The biomass raw material can be one or more of coconut palm, coconut shell, palm and moso bamboo.
Further, the hydrothermal coalification pretreatment in the step (2) is specifically as follows: according to the mass ratio of 1: 1-1.2: 0.1-0.2 putting the biomass raw material, deionized water and 30% aqueous hydrogen peroxide into a hydrothermal kettle, screwing a kettle cover, heating to 180-220 ℃ in a muffle furnace, keeping for 2-3 hours, taking out, washing with hot water, and drying to constant weight to obtain the hydrothermal biomass charcoal.
Further, in the step (3), the mass ratio of the hydrothermal biomass charcoal, the activating agent and the co-activating agent is 1: 1-1.5: 0.5 to 1.
Further, in the step (5), the carbonized material is ground until D50 is 5-8 microns, and the capacitance carbon is obtained.
Further, the present invention also includes the step (6) of recovering the activating agent: and recovering alkali from the filtrate of the first round washing of the carbonized material by a solvent evaporation method or an electrodialysis method, and recycling the alkali as an activating agent.
Further, the activating agent in the step (3) is not limited to potassium carbonate, and a basic potassium salt or sodium salt such as potassium formate, sodium carbonate, or sodium formate may be used. The activating agent can be one or more of potassium carbonate, potassium formate, sodium carbonate and sodium formate.
Further, in the step (3), the dry environment means that the relative humidity is less than 30%.
The technical principle of the invention for preparing the capacitance carbon is as follows:
the research of the invention finds that the lignin content of the thick coconut coir wrapped outside the coconut shell reaches 38 percent and is far higher than the content of the ordinary biomass by about 20 percent, the yield of the coconut coir is more than that of the coconut shell, and the coconut coir is stripped from the coconut shell and discarded to be decayed when the capacitor charcoal is fired. The invention develops a new technical circuit for manufacturing the capacitance carbon by coconut palm through laboratory research and small-scale production, the activating agent can be recycled, and the produced capacitance carbon has high yield, good quality, low cost and little pollution. Aiming at the problems in the existing biomass capacitance carbon manufacturing technology, the invention uses a new technical circuit to manufacture the biomass capacitance carbon, and particularly pays attention to the following four technical measures:
the method has the advantages that the biomass raw materials such as coconut palm and the like are cleaned, silt is removed, and the quality of the raw materials is guaranteed.
② the carbonization of traditional biomass raw material such as coconut shell is carried out at the temperature of 400 ℃ to 650 ℃, which generates a large amount of tar and VOC, the coconut shell is carbonized basically completely, and has no or few oxygen-containing functional groups, and the activation reaction is basically the reaction of the activator and the carbon. In the invention, a proper amount of hydrogen peroxide solution is added when coconut palm raw materials are subjected to low-temperature hydrothermal coal gasification pretreatment to form a humic acid structure of lignite, and a large number of active functional groups such as carboxyl, phenolic hydroxyl, alcoholic hydroxyl, aldehyde group, carbonyl, ether oxygen group and the like are generated and reserved. The hydrothermal carbon precursor containing a large number of functional groups provides a brand new activation method for the invention, and the auxiliary activator urea is used for opening a hydrogen bond network in the hydrothermal carbon, and acidic and polar functional groups (such as carboxyl, phenolic hydroxyl, alcoholic hydroxyl, aldehyde group, carbonyl, ether oxygen group and the like) and K of the hydrothermal carbon2CO3Or Na2CO3When alkaline activator micromolecules react, precursor macromolecules and the activator micromolecules or ions form a complex body which is uniformly distributed, and during carbonization and activation, high-efficiency fixed-point activation reaction is carried out, so that a large number of uniformly distributed holes and pore system structures are generated on the surface and inside of carbon particles.
③ using new activating agent and activating method, using environment-friendly alkaline potassium salt or sodium salt (such as K)2CO3And Na2CO3) As an activator, the humic acid modified humic acid forms a complex combined by chemical bonds with active functional groups of a humic acid precursor, and K combined in a fixed-point way after carbonization at 650℃ is completed2CO3Or Na2CO3Gradually decompose into K2O、Na2O and CO2The method starts a violent activation reaction, generates a large number of uniformly distributed holes and pore structures on the surface and inside of the carbon particles, integrates the carbonization reaction and the activation reaction, effectively improves the yield and the equipment utilization rate, and reduces the energy consumption.
The invention changes the traditional KOH and NaOH activating agents with extremely strong corrosivity into K which is friendly to the environment and equipment2CO3And Na2CO3The activating agent can be recycled, the cost is reduced, the pollution is reduced, a method for producing high-quality capacitance carbon in a green, environment-friendly, sustainable, renewable and low-cost manner is provided, and the method has good social benefit and economic benefit.
The invention has the following beneficial effects:
firstly, the biomass raw materials such as coconut palm are deeply cleaned, silt is effectively removed, ash content of capacitance carbon is greatly reduced, and conductivity is improved.
Second, the conventional biomass carbonization reaction is performed at a temperature of 400 to 650 ℃, which generates a large amount of tar and volatile gas, and the yield is only 25 to 30%. The invention carries out the low-temperature hydrothermal coal gasification reaction of biomass raw materials such as coconut palm at the temperature of 180-220 ℃, generates incomplete carbonization, generates humic acid macromolecules with a large number of functional groups, does not generate tar and volatile gas, and has no pollution, and the yield of the hydrothermal coconut palm charcoal reaches 60%.
Third, the traditional activation reaction is an activator (KOH, ZnCL)2、H3PO4Etc.) with a carbonized material, steam or CO in a physical activation process2The reaction of gas with carbon, the activation process of the present invention is fundamentally different from the conventional activation process. The invention first carries out low-temperature coalification reaction on biomass raw materials such as coconut palm to form humic acid structure similar to lignite, and then carries out low-temperature coalification reaction on the biomass raw materials with an activating agent such as K2CO3Grinding and mixing with auxiliary activator urea, aging, combining small molecules of the activator with functional groups in humic acid at fixed points to form intermolecular complex, and basically completing carbonization reaction at the temperature of over 650 DEG C2CO3Initially decompose to K2O and CO2The coconut palm charcoal is activated at fixed points to form pore, a large amount of holes and pore system distribution are generated in the interior and on the surface of the charcoal particles, the activation efficiency is high, and the quality is good.
Fourthly, the invention integrates carbonization and activation into a whole, is continuous, has simple operation, reduces energy consumption, improves the utilization rate of equipment, can produce 1 ton of high-quality capacitance carbon by less than 4 tons of coconut palm through tests, reduces the production cost and improves the economic benefit.
Fifth, the conventional activation method uses potassium hydroxide as an activator, which is very harmful to equipment, environment and personnel. The invention takes potassium carbonate or sodium carbonate as an activating agent, has no harm to the environment and personnel, and has much less corrosion to equipment.
Sixthly, the activating agent such as potassium carbonate, sodium carbonate and the like can be recycled, the recovery rate is over 80 percent, the resource consumption and the environmental pollution are reduced, and the production cost is reduced.
Drawings
FIG. 1 photograph of coconut coir used in example 1.
FIG. 2 photo of hydrothermal coconut coir char from example 1 after hydrothermal coal pretreatment and drying.
FIG. 3 example 1 aged hydrothermal coconut palm charcoal and activator K2CO3And photos of co-activator urea blends.
FIG. 4 photo of sintered carbon block taken out of furnace after carbonization-activation reaction containing residual molten salt of potassium carbonate in example 1.
FIG. 5 scanning electron micrograph of coconut palm fiber capacitance carbon prepared in example 1.
FIG. 6 specific surface data and pore size distribution plots from MBET testing of coconut palm capacitive carbon from example 1.
FIG. 7 photograph of potassium carbonate recovered in example 1.
FIG. 8 scanning electron micrograph of coconut palm fiber capacitance carbon prepared in example 2.
Fig. 9 specific surface data and pore size distribution plots from MBET method testing of coconut palm capacitive carbon from example 2.
FIG. 10 is a photograph of a moso bamboo subjected to hydrothermal coal preparation pretreatment in example 3.
Fig. 11 specific surface data and pore size distribution plots for MBET method testing of moso bamboo capacitance carbon of example 3.
Detailed Description
The invention is further described with reference to the following figures and specific examples.
Example 1
A method for preparing capacitance carbon by using biomass rich in lignin as a raw material comprises the following specific operation steps of taking coconut palm peeled from coconuts produced in Wenchang county, Hainan as a precursor of carbon, taking potassium carbonate as an activating agent and taking urea as an auxiliary activating agent:
(1) pretreatment of coconut palm
Cutting coconut palm into segments of 2-3 cm, adding 0.2% detergent into cleaning water, washing with a high-pressure water gun, removing silt, rinsing for three times, and drying at 130 deg.C for 6 hr to obtain coconut palm raw material.
(2) Hydrothermal coalification pretreatment
In a polytetrafluoroethylene cylinder of a hydrothermal kettle, adding a solvent according to the weight ratio of 1: 1.1: 0.1, adding 50 g of coconut palm raw material, 55 g of deionized water and 5 g of 30% aqueous hydrogen peroxide, screwing down a kettle cover, heating to 200 ℃ in a muffle furnace, keeping for 3 hours, taking out, washing for 2 times by hot water, washing off water-soluble substances, and drying to constant weight to obtain 30.5 g of hydrothermal coconut palm charcoal with the yield of 60%.
(3) Compounding and aging
According to the following steps: 1: 0.5, adding 30 g of activating agent potassium carbonate and 15 g of co-activating agent urea into 30 g of hydrothermal coconut palm charcoal, uniformly mixing, finely grinding, and aging in a drying environment (the relative humidity is 25-28%) at 60 ℃ for 6 hours.
(4) Carbonization-activation
Placing the aged hydrothermal coconut palm charcoal-activator-co-activator mixture into a silicon carbide crucible, compacting, heating to 880 ℃ in a nitrogen-protected tube furnace, preserving heat for 1.5 hours, and cooling to room temperature.
(5) Carbon post-treatment of capacitors
The post-treatment comprises the following 7 steps:
(a) taking out the agglomerated mixed material, namely the carbonized material, in the crucible after calcination, placing the carbonized material in a mortar, pouring a small amount of deionized water, and finely grinding the mixture into slurry;
(b) soaking in hot water for 1 hr, filtering, storing the filtrate, soaking in hot water for 1 hr, filtering, and mixing the filtrate with the first filtrate for recovering potassium carbonate;
(c) washing and filtering the carbon filter residue with hot water for 2 times, and keeping the filtrate for neutralizing the subsequent pickling solution;
(d) adding 1M hydrochloric acid until the carbon powder is just immersed, soaking for 12 hours, and filtering;
(e) washing with water for 4 times until the pH value is 7;
(f) drying for 12 hours at 140 ℃;
(g) the jet mill milled to D50 at 6 microns to give a capacitive char of 13.88 g with a yield of 27.8% calculated as 50 g coconut coir.
(6) Potassium carbonate activator recovery
Drying the filtrate in a blast drying oven, discharging the carbonized stub bar, washing for 2 times, and recovering K2CO325.2 g of potassium carbonate is obtained, and the recovery rate is 84 percent.
The capacitance carbon product obtained in this example was subjected to a multi-point MBET test, and as shown in fig. 6, the specific surface data and the pore size distribution map of the MBET method test of the coconut palm capacitance carbon of example 1 were shown, and the test results are as follows: the specific surface reaches 2379m2The total pore volume is 1.475ml/g, which exceeds the highest standard (2000 m) of the national standard of capacitance carbon20.80ml/g) in a yield of 27.8% calculated on the coconut palm raw material.
As shown in FIG. 1, the photographs of coconut coir peeled from coconut shells showed that the coconut coir was present in a larger amount than the coconut shells, had a high lignin content, and was a good raw material for firing capacitor charcoal.
As shown in fig. 2, the photo of the hydrothermal coconut carbon after hydrothermal coal gasification and drying has a structure similar to that of lignite, and a large amount of active functional groups are newly generated and reserved.
As shown in FIG. 3, the aged hydrothermal coconut palm charcoal of example 1 and an activating agent K are used2CO3And a photograph of the co-activator urea mixture, compacted and packed in a silicon carbide crucible.
As shown in FIG. 4, a photograph of the sintered carbon block taken out of the furnace after the carbonization-activation reaction of example 1 was taken, containing the remaining molten salt of potassium carbonate.
As shown in FIG. 5, which is a scanning electron micrograph of the coconut palm fiber capacitance carbon prepared in example 1, the particle surface has a large number of pores.
As shown in FIG. 6, the MBET test of the capacitive carbon of example 1 reports a specific surface as high as 2379m2V, total pore volume 1.475 ml/g.
As shown in FIG. 7, which is a photograph of the potassium carbonate recovered in example 1, the recovery rate reached 84%.
Example 2
The embodiment of the method for preparing capacitance carbon by using biomass rich in lignin as a raw material uses sodium carbonate Na with low price2CO3The method is characterized in that coconut palm produced in Wenchang county of Hainan is taken as a precursor of carbon, urea is taken as an auxiliary activating agent, and the method comprises the following specific operation steps:
(1) pretreatment of coconut palm
Cutting coconut palm into segments of 2-3 cm, adding 0.2% detergent into cleaning water, washing with a high-pressure water gun, removing silt, rinsing for three times, and drying at 130 deg.C for 6 hr to obtain coconut palm raw material.
(2) Hydrothermal coalification pretreatment
According to the following steps: 1.1: 0.1, adding 50 g of coconut palm raw material, 55 g of deionized water and 5 g of 30% aqueous hydrogen peroxide solution into a hydrothermal kettle, screwing a kettle cover, heating to 200 ℃ in a muffle furnace, keeping for 2 hours, taking out, washing with hot water, filtering for 2 times, and drying to constant weight to obtain the hydrothermal coconut palm carbon.
(3) Compounding and aging
According to the following steps: 1: 0.5, adding activating agent sodium carbonate and auxiliary activating agent urea into the hydrothermal coconut palm charcoal, finely grinding, mixing, and aging in a drying environment (the relative humidity is 25-28%) at 50 ℃ for 6 hours.
(4) Carbonization-activation
Putting the aged hydrothermal coconut brown carbon-activator-co-activator mixture into a silicon carbide crucible, heating to 860 ℃ in a tubular furnace protected by nitrogen, preserving the heat for 1.5 hours, and cooling to room temperature.
(5) Carbon post-treatment of capacitors
The post-treatment comprises the following 7 steps:
(a) taking out the sintered mixed material in the crucible, placing the sintered mixed material in a mortar, pouring a small amount of deionized water, and finely grinding the mixed material into slurry;
(b) soaking in hot water for 1 hr, filtering, storing the filtrate, soaking in hot water for 1 hr, filtering, and mixing the filtrate with the first filtrate for recovering sodium carbonate;
(c) washing with hot water and filtering for 2 times, and keeping filtrate for neutralizing acid washing solution;
(d) adding appropriate amount of 1M hydrochloric acid until carbon powder is just immersed, soaking for 12 hr, and filtering;
(e) washing with water for 3 times until the pH value is 6;
(f) drying for 12 hours at 140 ℃;
(g) the residue was ground with a jet mill to a D50 value of 6.2 μm to give a capacitive char of 14.4 g, in a yield of 28.8% calculated on 50 g of coconut coir starting material.
(6) Activating agent for recovering sodium carbonate
Recovering Na from filtrate of 2-time water washing of discharged carbonized stub bar by evaporation method2CO324.61 g of sodium carbonate is obtained, and the recovery rate is 82%.
As shown in fig. 8, which is a scanning electron micrograph of the coconut palm fiber capacitance carbon prepared in example 2, it can be seen that a large number of pores are formed on the surface of the carbon particles.
As shown in fig. 9, the specific surface data and the pore size distribution map of the MBET method test of the coconut palm capacitive carbon of example 2 are shown. The specific surface of the capacitance carbon product prepared by the embodiment reaches 1836m through a multipoint MBET test2The total pore volume is 0.831ml/g, which reaches the II-grade standard (1500 m) of the national standard of capacitance carbon20.55ml/g) higher than that of Japanese Coli Standard YP50F (1600 m)2In terms of/g and 0.70ml/g), the yield, calculated on the coconut palm starting material, was 28.8%. Na (Na)2CO3Is not as effective as K in activating2CO3But at a cost much lower than that of Na2CO3。
Example 3
The lignin content of the moso bamboo is about 30 percent and is higher than the content of the common biomass by 20 percent. The moso bamboo has strong updating and regenerating capability and high yield, the moso bamboo resources in China are rich, a large number of moso bamboo resources are used as scaffold for building in the past, and the existing steel pipes are changed into the scaffold for building, so that new application needs to be found for the moso bamboo. Because the bamboo has high lignin content, the alkali consumption is large when the bamboo is used for manufacturing paper pulp, the bamboo is not generally used for papermaking, but the bamboo is a good raw material for firing capacitance carbon. The present example illustrates the specific operation steps and implementation results of example 3, using moso bamboo as a carbon precursor, potassium carbonate as an activator, and urea as an activating aid.
A method for preparing capacitance carbon by using biomass rich in lignin as a raw material comprises the following steps:
(1) pretreatment of moso bamboo
Taking disposable bamboo chopsticks used in a dining room, cleaning the disposable bamboo chopsticks with 0.2% of detergent, removing oil stains, rinsing for three times, drying for 6 hours at 120 ℃, and cutting the disposable bamboo chopsticks into small sections to obtain the bamboo chopstick raw material.
(2) Hydrothermal coalification pretreatment
In a polytetrafluoroethylene cylinder of a hydrothermal kettle, adding a solvent according to the weight ratio of 1: 1.1: 0.1, adding 50 g of bamboo chopstick raw material, 55 g of deionized water and 5 g of 30% hydrogen peroxide aqueous solution, screwing a kettle cover, heating to 200 ℃ in a muffle furnace, keeping for 3 hours, taking out, washing for 2 times by using hot water, washing off water-soluble substances, and drying to constant weight to obtain 25.5 g of hydrothermal bamboo charcoal with the yield of 51%.
(3) Compounding and aging
According to the following steps: 1: 0.5, adding 25 g of activator potassium carbonate and 12.5 g of co-activator urea into 25 g of hydrothermal bamboo charcoal, uniformly mixing, finely grinding, and aging in a drying environment (the relative humidity is 25-28%) at 60 ℃ for 6 hours.
(4) Carbonization-activation
Putting the aged hydrothermal bamboo charcoal-activator-co-activator mixture into a silicon carbide crucible, compacting, heating to 880 ℃ in a nitrogen-protected tube furnace, preserving heat for 1.5 hours, and cooling to room temperature.
(5) Carbon post-treatment of capacitors
The post-treatment comprises the following 7 steps:
(a) taking out the sintered mixed material in the crucible, placing the sintered mixed material in a mortar, pouring a small amount of deionized water, and finely grinding the mixed material into slurry;
(b) soaking in hot water for 1 hr, filtering, storing the filtrate, soaking in hot water for 1 hr, filtering, and mixing the filtrate with the first filtrate for recovering potassium carbonate;
(c) washing with hot water and filtering for 2 times, and keeping filtrate for neutralizing acid washing solution;
(d) adding 1M hydrochloric acid until the carbon powder is just immersed, soaking for 12 hours, and filtering;
(e) washing with water for 4 times until the pH value is 7;
(f) drying for 12 hours at 140 ℃;
(g) the obtained product was ground with a jet mill to D50 of 6 μm to obtain 6.43 g of carbon, and the yield was 12.86% based on 50 g of dried bamboo chopsticks.
(6) Recovered potassium carbonate activating agent
Drying the filtrate in a blast drying oven, discharging the carbonized stub bar, washing for 2 times, and recovering K2CO320.5 g of potassium carbonate is obtained, and the recovery rate is 82 percent.
As shown in fig. 10, the photograph of the pretreatment of the bamboo in example 3 for hydrothermal coal gasification was similar in appearance to lignite.
As shown in fig. 11, is the specific surface and pore size distribution of the MBET method test of the moso bamboo capacitance carbon of example 3. The capacitance carbon product prepared by the embodiment has the specific surface reaching 2172m after being tested by multi-point MBET2The total pore volume is 0.956ml/g and exceeds the highest standard (2000 m) of the national standard of capacitance carbon20.80ml/g) and a yield of 12.86% based on dry bamboo.
Example 4
A method for preparing capacitance carbon by using biomass rich in lignin as a raw material comprises the following specific operation steps of taking coconut shells produced in Wenchang county of Hainan as a carbon precursor, taking potassium formate as an activating agent and taking urea as an auxiliary activating agent:
(1) crushing coconut shells into pieces with the size of a unitary coin, adding 0.5% of detergent into cleaning water, washing with a high-pressure water gun to remove silt, rinsing for three times, drying at 130 ℃ for 6 hours, and crushing into powder with 40 meshes by using a powder grinding machine to obtain a coconut shell powder raw material;
(2) pretreatment of hydrothermal coal: according to the mass ratio of 1: 1.2: 0.2 placing the coconut husk powder raw material, deionized water and 30% hydrogen peroxide water solution into a polytetrafluoroethylene cylinder of a hydrothermal kettle, screwing a kettle cover, heating to 180 ℃ in a muffle furnace, keeping for 3 hours, taking out, filtering, washing for 2 times by hot water, and drying to constant weight to obtain the hydrothermal coconut husk charcoal.
(3) Material preparation and aging: adding an activating agent potassium formate and an auxiliary activating agent urea into hydrothermal raw coconut shell charcoal, mixing, finely grinding to obtain a mixture, and aging the mixture for 7 hours in a drying environment (the relative humidity is 20-25%) at 50 ℃; the mass ratio of the hydrothermal coconut shell carbon to the activating agent to the co-activating agent is 1: 1.5: 1.
(4) carbonization-activation: placing the aged mixture into a silicon carbide crucible, compacting, heating to 850 ℃ in a nitrogen-protected tube furnace, preserving heat for 1 hour, and cooling to room temperature to obtain a carbonized material;
(5) and (3) capacitor carbon post-treatment: and (3) sequentially carrying out first round washing, acid washing and second round washing on the carbonized material, drying and grinding until D50 is 5 micrometers, so as to obtain the capacitance carbon (the specific steps are the same as those in example 1).
(6) Recovering the potassium formate activating agent: and recovering potassium formate from the filtrate obtained by 2 times of water washing of the carbonized stub bar by an evaporation method, and recycling the potassium formate as an activating agent.
Example 5
A method for preparing capacitance carbon by using biomass rich in lignin as a raw material comprises the following specific operation steps of taking palm fibers stripped from palm trees grown in Nanning as a precursor of carbon, taking sodium formate as an activating agent and urea as an auxiliary activating agent:
(1) pretreatment of a biomass raw material: cutting the palm fiber into small sections of 2-3 cm, washing with a high-pressure water gun, removing silt, rinsing for three times, and drying at 130 ℃ for 6 hours to obtain a palm raw material;
(2) hydrothermal coal gasification pretreatment: according to the mass ratio of 1: 1.1: 0.2 putting the palm raw material, deionized water and 30% aqueous hydrogen peroxide into a polytetrafluoroethylene cylinder of a hydrothermal kettle, screwing a kettle cover, heating to 220 ℃ in a muffle furnace, keeping for 2 hours, taking out, washing with hot water, and drying to constant weight to obtain the hydrothermal palm carbon.
(3) Material preparation and aging: adding sodium formate as an activating agent and urea as an auxiliary activating agent into hydrothermal palm charcoal, mixing and grinding to obtain a mixture, and aging the mixture in a dry environment (the relative humidity is 20-25%) at 70 ℃ for more than 6 hours; the mass ratio of the hydrothermal palm carbon to the activating agent to the co-activating agent is 1: 1.2: 0.7.
(4) carbonization-activation: putting the aged hydrothermal palm carbon-activator-co-activator mixture into a silicon carbide crucible, compacting, heating to 870 ℃ in a nitrogen-protected tube furnace, preserving heat for 1 hour, and cooling to room temperature to obtain a carbonized material;
(5) and (3) capacitor carbon post-treatment: and (3) sequentially carrying out first round washing, acid washing and second round washing on the carbonized material, drying and grinding until D50 is 8 microns to obtain the capacitance carbon (the specific steps are the same as those in example 1).
(6) Recovering a sodium formate activating agent: sodium formate is recovered from the filtrate of 2 times of water washing of the carbonized stub bar by an evaporation method and is used as an activating agent for recycling.
Although the present invention has been described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (9)
1. A method for preparing capacitance carbon by using biomass rich in lignin as a raw material is characterized by comprising the following steps:
(1) pretreatment of a biomass raw material: cleaning and drying the biomass raw material to obtain the biomass raw material;
(2) hydrothermal coal gasification pretreatment: adding water and aqueous hydrogen peroxide into a biomass raw material, heating to 180-220 ℃, performing a coalification reaction, keeping for 2-3 hours, washing, and drying to constant weight to obtain hydrothermal biomass charcoal;
(3) material preparation and aging: adding an activating agent and an auxiliary activating agent into hydrothermal biomass charcoal, mixing and grinding to obtain a mixture, and aging the mixture for more than 6 hours in a drying environment at 50-70 ℃;
the activating agent is potassium salt or sodium salt, and the co-activating agent is urea;
(4) carbonization-activation: heating the aged mixture to 850-880 ℃, preserving heat for 1-1.5 hours, and cooling to room temperature to obtain a carbonized material;
(5) and (3) capacitor carbon post-treatment: and (4) washing the carbonized material by a first round of water washing, acid washing and a second round of water washing in sequence, drying and grinding to obtain the capacitance carbon.
2. The method for preparing the capacitance carbon by using the biomass rich in the lignin as the raw material according to claim 1, wherein the method comprises the following steps: the biomass raw material in the step (1) is a biomass raw material rich in lignin.
3. The method for preparing the capacitance carbon by using the biomass rich in the lignin as the raw material according to claim 2, wherein the method comprises the following steps: the biomass raw material comprises but is not limited to one or more of coconut palm, coconut shell, palm and moso bamboo.
4. The method for preparing the capacitance carbon by using the biomass rich in the lignin as the raw material according to claim 1, wherein the method comprises the following steps: the hydrothermal coalification pretreatment in the step (2) is specifically as follows: according to the mass ratio of 1: 1-1.2: 0.1-0.2 putting the biomass raw material, deionized water and 30% aqueous hydrogen peroxide into a hydrothermal kettle, screwing a kettle cover, heating to 180-220 ℃ in a muffle furnace, keeping for 2-3 hours, taking out, washing with hot water, and drying to constant weight to obtain the hydrothermal biomass charcoal.
5. The method for preparing the capacitance carbon by using the biomass rich in the lignin as the raw material according to claim 1, wherein the method comprises the following steps: in the step (3), the mass ratio of the hydrothermal biomass charcoal, the activating agent and the co-activating agent is 1: 1-1.5: 0.5 to 1.
6. The method for preparing the capacitance carbon by using the biomass rich in the lignin as the raw material according to claim 1, wherein the method comprises the following steps: in the step (5), the carbonized material is ground until D50 is 5-8 microns, and the capacitance carbon is obtained.
7. The method for preparing capacitance carbon by using biomass rich in lignin as raw material according to claim 1, further comprising the step (6) of recovering an activating agent: and recovering alkali from the filtrate of the first round washing of the carbonized material by a solvent evaporation method or an electrodialysis method, and recycling the alkali as an activating agent.
8. The method for preparing the capacitance carbon by using the biomass rich in the lignin as the raw material according to claim 1, wherein the method comprises the following steps: in the step (3), the activating agent includes but is not limited to one or more of potassium carbonate, potassium formate, sodium carbonate and sodium formate.
9. The method for preparing the capacitance carbon by using the biomass rich in the lignin as the raw material according to claim 1, wherein the method comprises the following steps: in the step (3), the dry environment means that the relative humidity is less than 30%.
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