CN113735120A

CN113735120A - Method for joint production of capacitance carbon and high-purity cellulose

Info

Publication number: CN113735120A
Application number: CN202110941028.5A
Authority: CN
Inventors: 翁千越
Original assignee: Shanghai Seprit Biotechnology Co ltd
Current assignee: Shanghai Seprit Biotechnology Co ltd
Priority date: 2021-08-17
Filing date: 2021-08-17
Publication date: 2021-12-03

Abstract

The invention relates to the technical field of material science, in particular to a method for jointly producing capacitance carbon and high-purity cellulose by taking biomass as a raw material. The method comprises the following steps: 1) boiling the bagasse in alkali liquor; 2) filtering the bagasse cooking liquor obtained in the step 1), separating cellulose, and cleaning to obtain pure cellulose; 3) drying and grinding the alkali lignin solution obtained by filtering in the step 2) to obtain alkali lignin powder; 4) mixing the alkali lignin powder provided in the step 3) with an alkali salt activator and an auxiliary activator, aging, carbonizing-activating and post-treating to obtain capacitance carbon; 5) recovering the alkaline salt activator from the washing filtrate obtained in the post-treatment step of the step 4), and recycling the alkaline salt activator for the step 4) and the step 1). The invention can realize high-value co-production of capacitance carbon and cellulose, in the technical circuit, alkali is not only a reagent for separating bagasse cellulose and lignin, but also an activating agent for firing the capacitance carbon, thereby achieving dual purposes of alkali and recycling.

Description

Method for joint production of capacitance carbon and high-purity cellulose

Technical Field

The invention relates to the technical field of material science, in particular to a method for jointly producing capacitance carbon and high-purity cellulose by taking biomass as a raw material.

Background

Due to the excellent performance of super capacitors in the rapid storage and high power release of electric energy, market demand and industrial scale are rapidly increasing, and the demand for high-quality capacitive carbon is increasing. Recent studies have found that the quality of the capacitance carbon produced by using lignin is much higher than that of other types of raw materials, such as plant raw materials (moso bamboo, coconut shell, fruit shell), coal (or petroleum) raw materials and synthetic resin raw materials. The lignin is a natural polymer derived from plants, has the advantages of plant raw materials and resin raw materials, has a plurality of excellent properties different from other capacitance carbon raw materials, and can adopt a brand new carbonization and activation method. The lignin is originally the waste of the alkaline paper-making and pulping industry, and the lignin is discharged in the paper-making black liquor before, thus causing serious pollution; most of the paper mills burn off the concentrated black liquor, which causes huge waste. The extraction of lignin from papermaking black liquor has been studied for many years, and many patent techniques and research papers can be referred to, so that a plurality of procedures are needed to obtain a pure lignin product, which not only has high cost, but also may cause additional pollution. On the other hand, alkali is needed to be used as an activating agent for producing the capacitance carbon by using the lignin, and the alkali lignin generated in the alkaline papermaking black liquor contains alkali, so that the capacitance carbon can be directly produced by using the alkali lignin, and the capacitance carbon and the cellulose are combined to realize the combined production of the lignin capacitance carbon and the cellulose. Theoretically, the capacitance carbon can be manufactured by using the alkali lignin of the papermaking black liquor, but the papermaking industry uses various alkali raw materials such as caustic soda, sodium sulfide, sodium sulfite and the like, the papermaking raw materials have complex sources, and are difficult to control because the papermaking raw materials contain impurities such as silt, scrap iron and the like, so that the alkali lignin of the black liquor has complex components and high ash content, and the capacitance carbon with high quality cannot be manufactured. Therefore, the invention provides a new technical circuit for capacitor carbon-cellulose co-production, which is used for producing high-quality capacitor carbon and high-purity cellulose.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide a method for the joint production of capacitance carbon and high-purity cellulose, which is used for solving the problems in the prior art.

To achieve the above and other related objects, the present invention provides a method for co-producing capacitor carbon and high purity cellulose, the method comprising:

1) boiling the bagasse in alkali liquor;

2) filtering the bagasse cooking liquor obtained in the step 1), separating cellulose, and cleaning to obtain pure cellulose;

3) drying and grinding the alkali lignin solution obtained by filtering in the step 2) to obtain alkali lignin powder;

4) mixing the alkali lignin powder provided in the step 3) with an alkali salt activator and an auxiliary activator, aging, carbonizing-activating and post-treating to obtain capacitance carbon;

5) recovering alkaline salt substances from the washing filtrate obtained in the post-treatment step of the step 4), and recycling the alkaline salt substances for the step 4) and the step 1).

In some embodiments of the invention, in step 1), the bagasse cooking in alkaline solution step comprises mixing bagasse with an alkaline solution, followed by solid-liquid separation after cooking.

In some embodiments of the invention, in the step 2), the cellulose is washed by a solvent and dried to obtain high-purity cellulose; preferably, the solvent is selected from water, dilute acids, alcohols.

In some embodiments of the invention, the alkaline solution of step 1) is selected from KOH solution, NaOH solution, K₂CO₃Solution, Na₂CO₃One or more combinations of solutions.

In some embodiments of the invention, the concentration of the alkaline solution is 3-5%, and the solid-to-liquid ratio of the bagasse to the alkali liquor is 1: 4: 1: 6.

in some embodiments of the invention, the cooking time is more than or equal to 6h, and the cooking temperature is 120-160 ℃.

In some embodiments of the invention, in the step 3), the drying temperature of the alkali lignin solution is 120-140 ℃; drying to constant weight.

In some embodiments of the invention, it is characterized in that in step 4), the ratio of the alkali lignin powder, the alkali salt activator and the co-activator is 1: 0.5-1.5: 0.25-0.5.

In some embodiments of the invention, in step 4), the alkaline salt activator is selected from alkaline potassium and/or sodium salts.

In some embodiments of the invention, the basic potassium salt is selected from the group consisting of potassium carbonate, potassium formate, and combinations of one or more thereof; the alkaline sodium salt is selected from one or more of sodium carbonate and sodium formate.

In some embodiments of the present invention, in the step 4), the co-activator is selected from one or more of urea and ammonium bicarbonate.

In some embodiments of the present invention, in the step 4), the aging time is not less than 6 h.

In some embodiments of the invention, in the step 4), the carbonization-activation conditions are: under the atmosphere of inert gas; the temperature is 850-880 ℃; preserving the heat for 1-1.5 h, and cooling to room temperature.

In some embodiments of the invention, in the step 4), the post-treatment is to subject the carbonized material obtained by carbonization-activation to a first round of water washing, acid washing, a second round of water washing until the pH is 6-7, and then drying and grinding; the particle size D50 of the capacitance carbon obtained after grinding is 5-8 microns.

In some embodiments of the invention, the method of recovering the basic salt activator in step 5) comprises an evaporation method or an electrodialysis method; and recovering the alkaline salt activator from the filtrate obtained after the first round of water washing of the carbonized material obtained by carbonization-activation.

In some embodiments of the present invention, the method further comprises using the recovered alkaline salt material of step 5) for the lye cooking of step 1) and for the alkaline salt activator of step 4).

The invention also provides capacitance carbon prepared by the method for jointly producing the capacitance carbon and high-purity cellulose.

The invention also provides cellulose prepared by adopting the method for jointly producing the capacitance carbon and the high-purity cellulose.

Drawings

FIG. 1 is a photograph of bagasse staple fibers.

FIG. 2 is a photograph of bagasse that was boiled in lye.

FIG. 3 shows the alkali lignin dried gum scraped from the tray and the alkali lignin powder after grinding in example 1.

FIG. 4 shows the alkali lignin and activator K in the crucible of example 1₂CO₃And photos of co-activator urea blends.

FIG. 5 is a sintered carbon block from the furnace of example 1 containing molten salt of the remaining activator.

FIG. 6 is a scanning electron micrograph of the capacitive carbon prepared in example 1.

FIG. 7 is a graph showing the specific surface data and the pore size distribution of the capacitive carbon of example 1.

FIG. 8 is a photograph of the potassium carbonate recovered in example 1.

FIG. 9 is a photograph of high purity cellulose produced in example 1.

FIG. 10 is a scanning electron micrograph of the capacitive carbon prepared in example 2.

FIG. 11 is a graph showing the specific surface data and the pore size distribution of the capacitive carbon of example 2.

FIG. 12 is a scanning electron micrograph of the capacitive carbon prepared in example 3.

FIG. 13 is a graph showing the specific surface data and the pore size distribution of the capacitive carbon of example 3.

Detailed Description

In order to realize the high-value co-production of capacitance carbon and cellulose and manufacture high-quality products, the invention uses original technology and process lines. In the separation of bagasse lignin and cellulose, KOH (or NaOH) with higher purity is used, the dosage is slightly higher than that of the common pulping process, and K can also be used₂CO₃Or Na₂CO₃The bagasse is steamed at high temperature by alkaline solution, and then is separated by pressure filtration; the filtrate is used for extracting solid alkali lignin, is directly used for firing capacitance carbon, and recovers an alkali activating agent for reuse; and (3) carrying out acid washing, water washing and ethanol washing on the cellulose to obtain a high-purity cellulose product. In the technical circuit, the hemicellulose is not separated separately, part of the hemicellulose and the alkali lignin are burnt together to form capacitance carbon, and part of the hemicellulose in the cellulose is cleaned and removed. The process line can be used for producing high-quality capacitance carbon and high-purity cellulose from the bagasse, the capacitance carbon is used for manufacturing a high-value super capacitor, the high-purity cellulose can reach food and medicine grade and is used for manufacturing degradable tableware and medical appliances, the yield of the bagasse is greatly improved, the industrial chain is prolonged, the cost is reduced, the pollution is reduced, a green, environment-friendly and sustainable development path for the sugarcane industry is provided, and the method has good ecological benefit, social benefit and economic benefit. On the basis of this, the present invention has been completed.

The invention provides a method for jointly producing capacitance carbon and high-purity cellulose, which comprises the following steps:

1) boiling the bagasse in alkali liquor;

5) recovering the alkaline salt activator from the washing filtrate obtained in the post-treatment step of step 4), and recycling the alkaline salt activator for the steps 1) and 4).

In the method for jointly producing the capacitance carbon and the high-purity cellulose, step 1) is to cook bagasse in alkali liquor. In order to ensure the quality of the capacitance carbon and enable the cellulose product to reach food and medicine grade, the purity of bagasse raw materials, the chemical reagents and the like must be strictly controlledAnd in the stage, strict equipment and process lines are adopted, so that the co-production of high-quality capacitance carbon and high-purity cellulose is realized. Bagasse is a very clean papermaking raw material, is pressed and soaked in water for 3 to 4 times in a sugar mill, is pressed and soaked in water again, has extremely low ash content and impurities, and is very clean. In general, the bagasse can be used by first screening out powder and debris. Alternatively, alkali separation may be performed from the bagasse pith as a raw material. The bagasse pulp is powder which is separated from bagasse by a bagasse paper mill and cannot be used for paper, accounts for about 35% of the bagasse, and the fiber of the bagasse pulp in a powder state is very short, cannot be used for paper and is generally discarded as waste. The invention takes bagasse or bagasse pith as raw material, uses chemically pure KOH or NaOH to separate lignin and cellulose in the step 1), and uses alkaline sylvite and/or sodium salt as activating agent in the subsequent capacitance carbon production of the step 4), such as K₂CO₃Or Na₂CO₃Most of the KOH and NaOH used in step 1) are converted to K in the subsequent steps₂CO₃And Na₂CO₃The composite material has the function of an activator, and can be used for two purposes, so that the quality of capacitance carbon and cellulose can be guaranteed, and the capacitance carbon and the cellulose can be recycled.

In the step 1), the step of cooking the bagasse in alkali liquor, namely the alkali method separation, comprises the steps of mixing the bagasse with an alkali solution, and carrying out solid-liquid separation after cooking. The filtrate is alkali lignin; the filter residue is cellulose. The alkaline solution may be selected from KOH solution, NaOH solution, and K₂CO₃Solution, Na₂CO₃One or more combinations of solutions, K₂CO₃And Na₂CO₃It can also be used to separate lignin and cellulose, but only slightly less effectively. Typically, KOH (and K)₂CO₃) NaOH (and Na) ratio₂CO₃) Expensive, but when firing the capacitor carbon, K₂CO₃Effect ratio as activator Na₂CO₃Preferably, KOH is used because the carbon capacitor is a high value product and the activator can be recycled. The concentration of the alkaline solution can be 3-5%, and the solid-to-liquid ratio of the bagasse to the alkali liquor is 1: 4: 1: 6. in some embodiments, the concentration of the alkaline solution can also be 3% to 4%; or 4Percent to 5 percent and the like. The solid-liquid ratio of the bagasse to the alkali liquor can also be 1: 4: 1: 5; or 1: 5: 1: 6, and the like. The cooking time can be more than or equal to 6 hours, and the cooking temperature is 120-150 ℃. The alkaline solution of the bagasse can also be cooked by a professional paper pulp cooking pot or a sterilizing pot. After the operations, the alkali lignin solution and the cellulose can be obtained by filtration and separation.

In the step 2), the cellulose is washed by a solvent and dried to obtain high-purity cellulose; preferably, the solvent is selected from the group consisting of water, dilute acids and alcohols. Further, the alcohol is selected from ethanol. In a specific embodiment, the cellulose may be washed with dilute hydrochloric acid, washed with ethanol, washed with water again to remove residual lignin and hemicellulose, and dried to obtain high-purity cellulose.

In the method for jointly producing the capacitance carbon and the high-purity cellulose, the step 3) is to dry and grind the alkali lignin solution provided in the step 1) to obtain alkali lignin powder. The drying mode can be drying or spray drying to obtain alkali lignin powder. Under the common condition, the drying temperature can be, for example, 120 ℃ to 140 ℃; c, 120-130 ℃; or 130 ℃ to 140 ℃ and the like. Drying to obtain alkali lignin dry glue, continuously drying to constant weight, and grinding into alkali lignin powder. In the foregoing process, the alkali wood solution may be placed in a tray, for example, and dried in an oven, wherein the tray may have a teflon coating, for example, to avoid sticking to the pan. Since alkali wood powder has high hygroscopicity, it is preferable to perform in a dry environment using an air dryer.

In the method for jointly producing the capacitance carbon and the high-purity cellulose, NaOH or KOH which is used initially in the step 1) is converted into the activating agent Na in the step 4) through the cooking reaction₂CO₃And K₂CO₃The alkali lignin itself carries a partial alkali salt activator. In the step 4), alkaline potassium salt (or sodium salt) activator (K) is added to the alkali lignin for firing the capacitance carbon₂CO₃Or Na₂CO₃) And an auxiliary activating agent (urea or ammonium bicarbonate), wherein the mass ratio of the auxiliary activating agent to the auxiliary activating agent is 1: 0.5-1.5: 0.25 to 0.5, in that the alkali lignin contains a part of alkali activityThe amount of the catalyst, the actual alkali activator, is higher than the above ratio. And 4) mixing the alkali lignin powder provided in the step 3) with a supplemented alkali salt activator and a supplemented auxiliary activator, aging, carbonizing, activating and post-treating to prepare the capacitance carbon. In general, alkali lignin powder is mixed with an alkali salt activator and a co-activator, and then ground and aged.

In the step 4), the ratio of the alkali lignin powder, the alkali salt activator and the co-activator is 1: 0.5-1.5: 0.25 to 0.5.

In the step 4), the alkaline salt activator is selected from alkaline potassium salt and/or alkaline sodium salt. Preferably, the basic potassium salt includes, but is not limited to, potassium carbonate, potassium formate. Basic sodium salts include, but are not limited to, sodium carbonate, sodium formate.

In the step 4), the co-activator is selected from one or more of urea and ammonium bicarbonate.

In the step 4), the aging time is more than or equal to 6 hours. Aging, which refers to allowing the solid mixture to stand for a period of time under conditions such that the solid components therein have sufficient reaction time.

In the step 4), the carbonization-activation conditions are as follows:

(a) under an inert gas atmosphere. The inert gas may be, for example, nitrogen, argon, or the like.

(b) The reaction temperature is 850-880 ℃. In some embodiments, the reaction temperature can also be 850-860 ℃; 860-870 ℃; or 870-880 ℃ and the like.

(c) And (5) preserving the heat for 1-1.5 h and then cooling to room temperature.

In the step 4), in the post-treatment step, the post-treatment is to perform first round washing, acid washing and second round washing on the carbonized material obtained by carbonization-activation until the pH value is 6-7, and then drying and grinding the carbonized material; the particle size D50 of the capacitance carbon obtained after grinding is 5-8 microns. Wherein the first water wash may comprise multiple water washes. The acid washing may be, for example, hydrochloric acid washing.

In the method for jointly producing the capacitance carbon and the high-purity cellulose, the step 5) is to recover the alkaline salt activator from the first round of washing filtrate obtained in the post-treatment step of the step 4).

In the step 5), the method for recovering the alkaline substance comprises an evaporation method or an electrodialysis method, and the alkaline salt substance is recovered from the filtrate obtained after the carbonized material obtained by carbonization-activation is subjected to first round of washing. The alkaline salt includes alkaline salt activators brought about and supplemented by the alkaline lignin.

In the step 5), the recovered alkaline salt activator is used in the steps 4) and 1) for recycling. Specifically, the recovered alkaline salt substance in the step 5) is used for the lye cooking in the step 1) and is used for the alkaline salt activator in the step 4).

In a second aspect, the invention provides capacitance carbon prepared by the method for jointly producing the capacitance carbon and high-purity cellulose according to the first aspect of the invention.

In the capacitance carbon provided by the invention, the specific surface area of the capacitance carbon is more than or equal to 1800 m²A/g, and may be as high as 2800m²(ii)/g; the total pore volume of the capacitance carbon is not less than 0.8ml/g and can reach 1.8 ml/g; the aperture of the capacitance carbon reaches 0.8 nm-5 nm; 0.8-2 nm; 2-5 nm; 0.8-1.5 nm; 1.5-3 nm; or 3 to 5 nm.

The third aspect of the invention provides cellulose prepared by the method for jointly producing the capacitance carbon and the high-purity cellulose.

In the cellulose provided by the invention, the purity of the cellulose can reach more than 98%.

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

firstly, the traditional bagasse papermaking and the lignin capacitance carbon manufacturing are two unrelated industries, wherein after cellulose is extracted by a bagasse papermaking factory, black liquor containing lignin is discharged or burnt after concentration; if the capacitance carbon production plant wants to use the lignin as the raw material to manufacture the capacitance carbon, the lignin needs to be extracted from the papermaking black liquor, the process is long, the cost is high, and additional pollution is caused. The new capacitance carbon-cellulose co-production technical line combines two industries, and the paper mill provides the produced pollution waste alkali lignin for the capacitance carbon manufacturing plant, thereby eliminating pollution, obtaining income and recycling the alkali salt activating agent for reuse. The capacitance carbon manufacturing plant uses the alkali lignin to manufacture high-value capacitance carbon, obtains cheap raw materials, saves part of alkali salt activating agent, and can reuse the recovered alkali activating agent for pulping to obtain additional benefit.

Secondly, the traditional capacitance carbon manufacturing process is divided into two steps of carbonization and activation, the raw materials are firstly carbonized at the temperature of 450 ℃ to 650 ℃ to generate a large amount of tar and volatile gas, and then the activation is carried out at the high temperature of more than 850 ℃. The invention combines carbonization and activation into one step, shortens the production time, and improves the production efficiency and the equipment utilization rate.

Thirdly, the traditional lignin capacitance carbon manufacturing process takes pure lignin as raw material, and alkaline activating agents such as KOH, NaOH and the like are added; the invention directly uses the alkali lignin as the raw material, contains the alkali salt activator, and only needs to supplement part of the alkali salt activator and the auxiliary activator, thereby greatly improving the quality of the capacitance carbon and reducing the cost.

Fourthly, in the traditional capacitance carbon production technology, activating agents (KOH and ZnCL) are used in the activation reaction₂、H₃PO₄Etc.) with carbon, the activation method of the present invention is significantly different from the conventional activation method in principle. Firstly, grinding and mixing alkali lignin, an alkaline potassium salt (or sodium salt) activator and an auxiliary activator urea, aging, combining small molecules of the activator with functional groups in the lignin at fixed points to form an intermolecular complex, and basically completing a carbonization reaction at the temperature of more than 650 ℃, and then K₂CO₃And Na₂CO₃Initially decompose to K₂O、Na₂O and CO₂The capacitance carbon is subjected to fixed-point activation pore-forming reaction, and the generated holes are uniformly distributed, high in yield and good in quality.

Fifthly, the conventional activation method uses KOH and ZnCL₂、H₃PO₄And the like are activating agents, so that the damage to equipment, environment and personnel is serious. The method uses potassium carbonate or sodium carbonate (potassium hydroxide and sodium hydroxide used in pulping)Most of the sodium has been converted to potassium carbonate and sodium carbonate) is an activator, which is not harmful to the environment and personnel and causes much less corrosion to equipment.

Sixth, the activating agent of the invention can be recycled, the recovery rate is above 80%, the resource consumption and the environmental pollution are reduced, the production cost is reduced, and the activating agent has economic benefit and social benefit.

Seventh, the high-purity cellulose produced by applying the technical circuit of the invention meets higher sanitary standard, can be used in the fields of food and medicine, can be used for manufacturing clean degradable appliances, and improves the value of products.

The following examples are provided to further illustrate the advantageous effects of the present invention.

In order to make the objects, technical solutions and advantageous technical effects of the present invention more clear, the present invention is further described in detail below with reference to examples. However, it should be understood that the embodiments of the present invention are only for explaining the present invention and are not for limiting the present invention, and the embodiments of the present invention are not limited to the embodiments given in the specification. The examples were prepared under conventional conditions or conditions recommended by the material suppliers without specifying specific experimental conditions or operating conditions.

Furthermore, it is to be understood that one or more method steps mentioned in the present invention does not exclude that other method steps may also be present before or after the combined steps or that other method steps may also be inserted between these explicitly mentioned steps, unless otherwise indicated; it is also to be understood that a combined connection between one or more devices/apparatus as referred to in the present application does not exclude that further devices/apparatus may be present before or after the combined device/apparatus or that further devices/apparatus may be interposed between two devices/apparatus explicitly referred to, unless otherwise indicated. Moreover, unless otherwise indicated, the numbering of the various method steps is merely a convenient tool for identifying the various method steps, and is not intended to limit the order in which the method steps are arranged or the scope of the invention in which the invention may be practiced, and changes or modifications in the relative relationship may be made without substantially changing the technical content.

In the following examples, reagents, materials and instruments used are commercially available unless otherwise specified.

Taking bagasse of Mingyang paper mill of Guangxi agricultural reclamation bureau as a raw material, taking chemically pure KOH (or NaOH) as a reagent for separating lignin, and K₂CO₃(or Na)₂CO₃) As an alkaline salt activator for firing capacitance carbon, urea is taken as an auxiliary activator, and 7 steps of the technical scheme of the invention are illustrated: (1) separating bagasse by an alkaline method; (2) extracting alkali lignin; (3) burdening and aging; (4) carbonizing and activating; (5) performing capacitor carbon post-treatment; (6) recovering the alkaline substance; (7) and (4) washing cellulose.

(1) Alkaline separation of bagasse

The method comprises the steps of taking bagasse of a paper mill as a raw material, screening out powder and chips, weighing 100 g of the bagasse, putting the bagasse into a 2000ml conical flask, adding 500 g of a 4% KOH solution (containing 20 g of KOH), sealing the conical flask with gauze, heating the conical flask in a 125 ℃ oven for 10 hours, adding water into the conical flask for 3 to 4 times, taking out the conical flask, and performing centrifugal filtration, wherein the filtrate is alkali lignin, and the filter residue is cellulose.

(2) Extraction of alkali lignin

Placing the alkali lignin solution in a tray with a polytetrafluoroethylene coating, drying the tray to dry glue at 130 ℃, scraping the alkali lignin dry glue from the tray, placing the tray in a mortar, continuously drying the tray to constant weight, grinding the tray to obtain alkali lignin powder, obtaining 55 g of alkali lignin dry powder, and estimating by a differential subtraction method to obtain about 25 g of potassium carbonate (20 g of KOH is converted into about 25 g of K)₂CO₃) 30 g of lignin (containing part of hemicellulose and the like).

(3) Compounding and aging

Mixing the alkali lignin dry powder with an activator potassium carbonate and an auxiliary activator urea according to the proportion of 1: 0.5-1: 0.25-5, grinding, and standing for more than 6 hours. (Note: alkali lignin contains a partial alkali salt activator K₂CO₃Here a supplemental alkaline salt activator).

(4) Carbonization-activation

And putting the mixture into a silicon carbide crucible, heating to 880 ℃ in a tubular furnace protected by nitrogen, preserving heat for 1 hour, and cooling to room temperature.

(5) Carbon post-treatment of capacitors

The post-treatment comprises 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, and mixing 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) soaking in 2M hydrochloric acid for 12 hr, and filtering;

(e) water washing 3 to 4 times to pH =6 to 7;

(f) drying for 12 hours at the temperature of 140 ℃;

(g) grinding with jet mill until D50 is 5-8 μm to obtain the product.

(6) Alkaline salt activator recovery

Mixing the filtrates, placing in a tray with polytetrafluoroethylene coating, drying at 130 deg.C in an air-flow oven to constant weight, and scraping K on the tray₂CO₃And grinding the alkali layer into powder for recycling.

(7) Cellulose cleaning

The cellulose is washed by hot water, then is washed by ethanol and then is washed by water to remove residual lignin and hemicellulose, and the high-purity cellulose is obtained.

Example 1

The bagasse of Guangxi agricultural reclamation office Mingyang paper mill is used as a raw material, potassium hydroxide (KOH) is used as a reagent for extracting alkali lignin, and potassium carbonate (K)₂CO₃) The specific procedure and results of example 1 are illustrated with urea as co-activator, an alkaline salt activator for the capacitive carbon. KOH is more expensive than NaOH, but the effect of KOH as an activator is far better than NaOH, and since the capacitance carbon is a high-value product and the activator can be recycled, the use of KOH for pulping is economical. Most of the KOH has been converted to K in the pulping process₂CO₃Truly activateActing is K₂CO₃。

(1) Alkaline separation of bagasse

Taking bagasse of Mingyang paper mill of Guangxi agricultural reclamation office as a raw material, screening out powder and debris, weighing 100 g of the bagasse, placing the bagasse into a 2000ml conical flask, adding 500 g of a 4% KOH solution (containing 20 g of KOH), tying the conical flask with gauze, heating the conical flask in an oven at 125 ℃ for 10 hours, adding 4 times of water into the conical flask, taking out the conical flask, performing centrifugal filtration, and extracting alkali lignin from filtrate and purifying cellulose from filter residues.

(2) Extraction of alkali lignin

Putting the alkali lignin solution in a tray with a polytetrafluoroethylene coating, drying for 10h at 130 ℃ in an oven until the alkali lignin is dry, scraping the alkali lignin dry glue from the tray, putting the alkali lignin dry glue in a mortar, continuously drying until the alkali lignin is constant in weight, grinding into alkali lignin powder to obtain 55 g of alkali lignin dry powder, estimating by using a differential subtraction method to obtain alkali lignin powder containing 30 g of lignin and K₂CO₃25 g (20 g KOH to about 25 g K)₂CO₃）。

(3) Compounding and aging

Adding 27.5 g K into 55 g alkali lignin powder according to the proportion of 1:0.5:0.5₂CO₃And 27.5 grams of urea, finely ground, mixed well, and aged for 6 hours.

(4) Carbonization-activation

And (3) placing the aged alkali lignin-alkaline salt activator-co-activator mixture into a silicon carbide crucible, heating to 880 ℃ in a tubular furnace protected by nitrogen, preserving heat for 1 hour, and cooling to room temperature.

(5) Carbon post-treatment of capacitors

The post-treatment comprises the following 7 steps:

(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;

(d) adding appropriate amount of 2M hydrochloric acid until the carbon powder is just immersed, soaking for 12 hours, and filtering;

(e) water washing 4 times to pH = 7;

(f) drying for 12 hours at the temperature of 140 ℃;

(g) the jet mill was operated to grind D50 at 6 μm to give a capacitive carbon of 13.44 g, with a yield of 13.4% based on 100 g bagasse.

(6) Recovered potassium carbonate activating agent

The filtrate from the 2-time water washing of the discharged carbonized stub bars is combined, placed in a tray, and dried in an oven at 125 ℃ to constant weight to obtain 42.4 g of anhydrous potassium carbonate, and the recovery rate is 80.8%. (Note: 20 g KOH was used for extraction of alkali lignin, which was converted to K during cooking and firing of the capacitor charcoal₂CO₃Total 25 g K₂CO₃(ii) a When the capacitance carbon is fired, 27.5 g of activating agent K is added₂CO₃Total 52.5 g K₂CO₃The recovery was 80.8% and the remainder was consumed as activator).

(7) Cellulose cleaning

The cellulose is washed by hot water, then washed by 1M dilute hydrochloric acid, washed by ethanol and washed by water for 3 times to remove residual lignin and hemicellulose, 55.5 g of high-purity cellulose is obtained, and the yield is 55.5 percent according to 100 g of bagasse.

The capacitance carbon product is tested by multipoint MBET, and the specific surface reaches 2952m²The total pore volume is 1.722ml/g, which exceeds the highest national standard (2000 m) of capacitance carbon²/g，0.80 ml/g）。

Example 2

The bagasse pulp is waste which is separated from bagasse in a bagasse paper mill and cannot be used for making paper, accounts for about 35% of the bagasse, and the fibers of the powdery bagasse pulp are very short, cannot be used for making paper and are generally discarded as waste. In this example, bagasse pith was used as a raw material, sodium hydroxide (NaOH) was used as a reagent for extracting alkali lignin, and sodium carbonate (Na) was used as a reagent for extracting alkali lignin₂CO₃) The specific procedure and results of example 2 are illustrated with urea as co-activator, an alkaline salt activator for the capacitive carbon. NaOH is cheaper than KOH, is a common agent for pulping processes, is cooked in bagasse pith and is alkaliMost of lignin is converted into Na in the carbonization process₂CO₃And may also function as an alkaline salt activator.

(1) Alkaline separation of sugarcane pith

Taking waste bagasse pith of Mingyang paper mill of Guangxi agricultural reclamation office as a raw material, screening out powder and debris in the waste bagasse pith, weighing 100 g of bagasse pith short fiber, putting the bagasse pith short fiber into a 2000ml conical flask, adding 500 g of 4% NaOH solution (containing 20 g of NaOH), tying the opening of the conical flask with gauze, heating the conical flask in a drying oven at 125 ℃ for 10 hours, adding 4 times of water in the middle of the conical flask, taking out the conical flask, performing centrifugal filtration, wherein the filtrate is used for extracting alkali lignin, and the filter residue is used for purifying cellulose.

(2) Extraction of alkali lignin

Putting the alkali lignin solution in a tray with a polytetrafluoroethylene coating, drying the tray in an oven at 130 ℃ until the alkali lignin is dry, scraping the alkali lignin dry glue from the tray, putting the tray in a mortar, continuously drying the tray until the weight is constant, and grinding the tray into alkali lignin powder to obtain 70.23 g of alkali lignin dry powder.

(3) Compounding and aging

70.23 g of alkali lignin powder is added with 52 g of Na according to the proportion of 1:0.75:0.5₂CO₃And 35 g of urea, finely grinding, mixing well, and aging for 6 hours.

(4) Carbonization-activation

And (3) placing the aged alkali lignin-alkaline salt activator-co-activator mixture into a silicon carbide crucible, heating to 860 ℃ in a tubular furnace protected by nitrogen, preserving heat for 1 hour, and cooling to room temperature.

(5) Carbon post-treatment of capacitors

The post-treatment comprises the following 7 steps:

(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;

(e) water washing 4 times to pH = 7;

(f) drying for 12 hours at the temperature of 140 ℃;

(g) the jet mill was operated to grind D50 at 6 μm to give 22.36 g of capacitive carbon, with a yield of 22.3% calculated on 100 g of bagasse pith.

(6) Activating agent for recovering alkaline salt of sodium carbonate

The filtrate from the 2-time water washing of the discharged carbonized stub bars is combined, placed in a tray and dried in an oven at 125 ℃ to constant weight, and 63.6 g of anhydrous sodium carbonate is obtained. (Note: 20 g NaOH was used for alkali lignin extraction and converted to Na during cooking and firing of the capacitor charcoal₂CO₃26.5 g of Na₂CO₃(ii) a When the capacitance carbon is fired, 52 g of activating agent Na is added₂CO₃78.5 g total Na₂CO₃The recovery was 81%, the remainder was consumed and lost as activator).

(7) Cellulose cleaning

The cellulose is washed by hot water, then washed by 1M dilute hydrochloric acid, washed by ethanol and then washed by water for 3 times to remove residual lignin and hemicellulose, and 51.5 g of high-purity cellulose is obtained, and the yield is 51.5 percent according to 100 g of bagasse pith.

The specific surface of the capacitance carbon product reaches 1954m through multi-point MBET test²The total pore volume is 0.936ml/g, which exceeds the II-level standard (1500 m) of the national standard of capacitance carbon²G, 0.55 ml/g). In this example, the waste bagasse pith was used as a raw material, and NaOH, which is an inexpensive reagent, was used, and the quality of the produced capacitor carbon was lower than that of example 1, but it was also economical.

Example 3

In the first two examples, alkali KOH and NaOH are used as reagents for separating lignin and cellulose, and K is used₂CO₃And Na₂CO₃As an alkaline salt activator for the capacitor carbon, K is finally recovered₂CO₃And Na₂CO₃. For this example K₂CO₃Can be used as lignin-cellulose separating agent and alkaline salt activator of capacitance carbon, and is the most suitable for the capacitance carbonAfter-recovery is also K₂CO₃The complete recycling of the separating agent and the alkaline salt activator can be realized.

(1) Alkaline separation of bagasse

Taking medulla Sacchari sinensis of Ming Yang paper mill of Guangxi agricultural reclamation office as raw material, sieving to remove powder and debris, weighing 100 g, placing in 2000ml conical flask, adding 500 g 4% K₂CO₃Solution (containing 20 g of K)₂CO₃) Tying with gauze, heating in a drying oven at 125 deg.C for 10 hr, adding water in the middle for 4 times, taking out, centrifuging, filtering to obtain filtrate for extracting alkali lignin, and purifying cellulose with filter residue.

(2) Extraction of alkali lignin

Putting the alkali lignin solution in a tray with a polytetrafluoroethylene coating, drying the tray in an oven at 130 ℃ until the alkali lignin is dry, scraping the alkali lignin dry glue from the tray, putting the tray in a mortar, continuously drying the tray until the weight is constant, and grinding the tray into alkali lignin powder to obtain 59.68 g of alkali lignin dry powder.

(3) Compounding and aging

Adding 30 g K into 59.68 g alkali lignin powder at a ratio of 1:0.5:0.25₂CO₃And 15 g of urea, finely ground, mixed well, and aged for 6 hours.

(4) Carbonization-activation

(5) Carbon post-treatment of capacitors

The post-treatment comprises the following 7 steps:

(e) water washing 4 times to pH = 7;

(f) drying for 12 hours at the temperature of 140 ℃;

(g) the jet mill was operated to mill D50 at 6 μm to give a capacitive carbon of 15.36 g with a yield of 15.36% based on 100 g bagasse.

(6) Recovered potassium carbonate activating agent

And (3) combining the filtrate obtained by 2 times of water washing from the discharged carbonized stub bars, putting the combined filtrate into a tray, and drying the combined filtrate in an oven at 125 ℃ to constant weight to obtain 42.4 g of anhydrous sodium potassium carbonate. (Note: 20 g of K was used for the extraction of alkali lignin₂CO₃30 g of alkaline salt activator K is added when the capacitance carbon is fired₂CO₃50 grams total, recovery was 84.8%, the remainder was consumed and lost as activator).

(7) Cellulose cleaning

The cellulose is washed by hot water, then washed by 1M dilute hydrochloric acid, washed by ethanol and washed by water for 3 times to remove residual lignin and hemicellulose, 58.2 g of high-purity cellulose is obtained, and the yield is 58.2 percent according to 100 g of bagasse pith.

The specific surface of the capacitance carbon product reaches 2817m through multi-point MBET test²The total pore volume is 1.511ml/g, the highest standard of national standard of super capacitance carbon (2000 m)²/g，0.80 ml/g）。

Alkaline salt activator for firing capacitor carbon with alkaline lignin, one part of alkali from alkali lignin belt and the other part of supplementary alkaline salt activator, the ratio of total lignin to alkaline potassium (or sodium) salt activator and co-activator is 1: 1.5-2: 0.5-1, and the ratio of alkali lignin to alkali potassium (or sodium) salt activator and co-activator is 1: 0.5-1.5: 0.25-0.5, and needs to be optimized according to experimental results.

Among them, the test method of the specific surface is the multipoint BET Method (MBET), and the method of the total pore volume is the density functional method (DFT).

The above embodiments are merely illustrative of the principles and utilities of the present application and are not intended to limit the application. Any person skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present application. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical concepts disclosed in the present application shall be covered by the claims of the present application.

Claims

1. A method for the combined production of capacitance carbon and high purity cellulose, the method comprising:

1) boiling the bagasse in alkali liquor;

2. The method for jointly producing capacitance carbon and high-purity cellulose according to claim 1, wherein in the step 1), the bagasse cooking step in alkali liquor comprises mixing bagasse with an alkali solution, and performing solid-liquid separation after cooking;

and/or, in the step 2), the cellulose is washed by a solvent and dried to obtain high-purity cellulose; preferably, the solvent is selected from water, dilute acids, alcohols.

3. The method for co-producing capacitor carbon and high-purity cellulose according to claim 2, wherein the alkaline solution in step 1) is selected from KOH solution, NaOH solution and K₂CO₃Solution, Na₂CO₃One or more combinations in solution;

and/or the concentration of the alkaline solution is 3% -5%;

and/or the solid-liquid ratio of the bagasse to the alkali liquor is 1: 4: 1: 6;

and/or the cooking time is more than or equal to 6 hours, and the cooking temperature is 120-160 ℃.

4. The method for jointly producing capacitance carbon and high-purity cellulose according to claim 1, wherein in the step 3), the drying temperature of the alkali lignin solution is 120-140 ℃; drying to constant weight.

5. The method for jointly producing capacitance carbon and high-purity cellulose according to claim 1, wherein in the step 4), the ratio of the alkali lignin powder, the alkali salt activator and the co-activator is 1: 0.5-1.5: 0.25-0.5.

6. The method for co-producing capacitance carbon and high-purity cellulose according to claim 1, wherein in the step 4), the alkaline salt activator is selected from alkaline potassium salt and/or alkaline sodium salt; preferably, the alkaline potassium salt is selected from one or more of potassium carbonate and potassium formate; the alkaline sodium salt is selected from one or more of sodium carbonate and sodium formate; and/or, in the step 4), the co-activator is selected from one or more of urea and ammonium bicarbonate;

and/or, in the step 4), the aging time is more than or equal to 6 hours;

and/or, in the step 4), the carbonization-activation conditions are as follows: under the atmosphere of inert gas; the temperature is 850-880 ℃; preserving the heat for 1 to 1.5 hours, and cooling to room temperature;

and/or in the step 4), the post-treatment is to perform first round washing, acid washing and second round washing on the carbonized material obtained by carbonization-activation until the pH value is 6-7, and then drying and grinding; the particle size D50 of the capacitance carbon obtained after grinding is 5-8 microns.

7. The method for co-producing capacitance carbon and high-purity cellulose according to claim 1, wherein in the step 5), the method for recovering the alkali salt activator comprises an evaporation method or an electrodialysis method; and recovering the alkaline salt activator from the filtrate obtained after the first round of water washing of the carbonized material obtained by carbonization-activation.

8. The method for co-producing capacitance carbon and high-purity cellulose according to claim 1, further comprising using the recovered alkaline salt substance of step 5) for the alkali digestion of step 1) and for the alkaline salt activator of step 4).

9. Capacitance carbon prepared by the method for producing capacitance carbon and high-purity cellulose in combination according to any one of claims 1 to 8.

10. Cellulose prepared by the method for jointly producing capacitance carbon and high-purity cellulose according to any one of claims 1 to 9.