Method for comprehensively utilizing biomass charcoal
Through reducing catalytic degradation of phenolic lignin and low-temperature dehydration and solidification technology, combined with nitrogen and oxygen doping, nanohybrid materials with small particle size and high surfactivity were prepared, which solved the application problems of lignin and silica in biomass carbon and achieved efficient utilization of biomass carbon.
Patent Information
- Application Number
- CN202510706268.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-29
- Publication Date
- 2025-08-26
AI Technical Summary
The prior art is difficult to effectively utilize lignin as a raw material to produce functional products on a large scale. The lignin and silica in biomass charcoal have large particle sizes and low surfactivity, making it difficult to be used in rubber composite materials as a substitute for fossil resources.
Reduced catalytic degradation of phenolic lignin technology, combined with low-temperature dehydration solidification carbon and heteroatomic nitrogen-oxygen doping, small-molecule lignin phenol self-assembled with silica to form nanohybrid materials, retain the aromatic ring structure of lignin, and improve surfactivity through surface modification.
Nanohybrid materials with small particle size and high surface activity were prepared, which improved compatibility and chemical bonding function with rubber substrate materials, solved the application problems of lignin and silica in biomass carbon, and achieved efficient utilization of biomass carbon.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of biochar energy chemical industry, and in particular relates to a method for comprehensive utilization of biochar. Background Art
[0002] To date, fossil fuels are the main raw materials for the production of carbon black, but burning fossil fuels emits greenhouse gases and pollutants that are associated with environmental degradation and harm to human health. In addition to the serious environmental impact, the fluctuation of fossil fuel market prices is a significant factor in determining the market price of commercial carbon black products, as it accounts for more than 60% of the manufacturing cost of carbon black. Therefore, there is an urgent need for cost-effective, cleaner, sustainable and environmentally friendly alternatives. To this end, a new development trend is to use renewable raw materials for carbon black production. In recent years, with the excessive consumption of fossil energy and increasingly serious environmental pollution, natural biomass carbon materials have been widely studied by researchers due to their wide distribution, abundant resources, low pollution and renewability.
[0003] The application of biochar in rubber composites not only offers a novel alternative solution for the disposal of agricultural solid waste but also contributes to environmental protection and the development of biorenewable resources for the rubber industry. However, due to inherent drawbacks of biochar, including large particle size, low surface activity, time-consuming processing, the presence of inorganic impurities, and variable composition and properties, its industrial application as an ideal reinforcing filler remains a long way off. Compared to other bioresources, lignin contains a large number of aromatic benzene rings and a carbon content of up to 60%, which facilitates efficient biochar production. Therefore, lignin is an excellent choice for biochar feedstock. Furthermore, lignin is often considered a useless, low-cost industrial solid waste, isolated from biochar feedstocks such as wood and herbaceous plants used in the paper industry, and is primarily burned as fuel or discharged into rivers. The paper and pulp industry produces approximately 50–75 million tons of lignin annually, and with the rise of biorefining, lignin production is projected to exceed 225 million tons in the future. However, currently, only a small fraction (approximately 2–5%) of this lignin is utilized.
[0004] In biochar, hemicellulose can be hydrolyzed into xylose and further processed into xylitol or furfural; cellulose can be used to make paper, or it can be hydrolyzed into glucose and further processed into a series of products such as ethanol; only lignin cannot be degraded into small molecule materials with a unified molecular formula. How to utilize lignin has been a research difficulty in the scientific community in recent years. So far, no feasible technology has been found to use lignin as a raw material for large-scale production of functional products, which has become an obstacle to the comprehensive utilization of biochar resources.
[0005] my country consumes nearly 10 million tons of rubber annually, requiring a similar 10 million tons of carbon black and silica as reinforcing fillers. Developing bio-based materials to replace fossil-based materials and gradually reducing the rubber industry's reliance on fossil resources is an inevitable trend. The design and development of new bio-based reinforcing fillers for rubber is crucial for ensuring the high quality and sustainable development of my country's rubber industry.
[0006] Biochar is agricultural waste. The biochar used in the present invention is wheat straw, wheat husk, rice straw, rice husk, corn stalk, corn cob, and wood pond residue, which contain lignin and silica. Wood pond residue is a solid residue produced during the production of commercial xylose. It has a cellulose content of 45%, 40% lignin, and 8% inorganic ash, and is one of the representatives of bio-based raw materials. According to statistics, my country produces approximately 130 million tons of xylose residue as a by-product each year, most of which is directly discarded or incinerated to generate heat. The effective utilization rate is very low, causing environmental pollution problems and waste of cellulose materials. In order to solve the current situation of low utilization rate of xylose residue, the present invention produces xylose from hemicellulose fibers in corn cobs, dehydrates them to produce furfural, and extracts lignin and silica from the xylose residue to prepare a hybrid material. On the one hand, this improves the utilization rate of xylose residue, and on the other hand, it breaks away from the limitations of petroleum-based raw materials.
[0007] How to prepare and replace fossil resources with lignin and silica in biochar is a pressing challenge for scientists and entrepreneurs. Converting lignin to organic carbon black has yet to be reported. Preserving the organic carbon properties of lignin in finished products and preventing its degradation into inorganic carbon is crucial for nanohybrid materials to replace fossil resources. Therefore, how to utilize lignin and silica in biochar to produce products with the same small particle size, high surface activity, and aromatic ring microstructure as fossil carbon black presents a significant challenge, requiring a novel technical solution within existing technologies to address this issue. Summary of the Invention
[0008] The purpose of the present invention is to address the problems existing in the prior art and to propose a method for comprehensive utilization of biochar.
[0009] The method for comprehensive utilization of biochar described in the present invention adopts the following technical solutions: (1) Using the reduction catalytic degradation of phenolic lignin technology, small molecular lignin phenol is prepared, and the self-assembly with silica in biochar is used to prepare lignin nano-hybrid material particles. The diameter of the primary particles is between 10 and 90 nm, laying the foundation for the production of raw materials for nano-hybrid materials, and preparing lignin-based nano-hybrid materials with the basic characteristics of small particle size of reinforcing materials; (2) Using low-temperature dehydration carbonization technology, lignin molecules are dehydrated, retaining the organic characteristics of the six-membered aromatic rings in the lignin molecules, converting lignin from a carbohydrate into a stable structure of organic macromolecules with aromatic ring characteristics, increasing the carbon content, and preparing lignin-based biomass carbon hybrid materials with a low hydrogen / carbon ratio, high aromaticity, and containing a large number of polycyclic aromatic rings; (3) The simultaneous doping of heteroatoms with nitrogen and oxygen is used to control the surface nitrogen-oxygen functional groups at the edges of carbon black particles. These nitrogen-oxygen functional groups significantly affect the surface properties of carbon black, thereby affecting its application. The surface functional groups contribute to the interactions between filler-filler matrix, filler-rubber matrix, and crosslink density. The interaction between the hybrid material and the elastomer matrix is partly due to the adsorption of polymer chains on the oxides on the surface of the hybrid material.
[0010] The method for comprehensive utilization of biochar according to the present invention comprises the following steps: Step S1: Furfural production from hemicellulose S1 (1) Hydrolysis of raw materials at normal pressure and low temperature 1000kg of biomass on a dry basis is crushed to 10-20mm, mixed with a 1-3wt% dilute sulfuric acid aqueous solution in a reactor at a solid-liquid ratio of 1kg:5-8L, and then heated to 100-120°C to catalytically hydrolyze the hemicellulose in the biomass to produce xylose. After filtration, a 10-15wt% xylose aqueous solution and a hydrolysis residue (mainly composed of cellulose, lignin, and silicate) are obtained. The hydrolysis residue can be sent to the hybrid material and activated carbon production workshop for subsequent comprehensive utilization; S1 (2), fixed bed catalytic dehydration A 1.0-3.0 mol / L aqueous solution of sulfuric acid catalyst is added to a reactor, heated to boiling, and then a co-catalyst is added until saturated, and stirred to form a catalyst rotating liquid surface layer; while nitrogen is continuously introduced into the reactor, a 10-15 wt% xylose aqueous solution obtained in step S1 (1) is sprayed onto the rotating liquid surface layer, so that the xylose aqueous solution and the catalyst rotating liquid surface layer come into contact and undergo a dehydration reaction, and the generated furfural is quickly carried out by a mixed gas of nitrogen and water vapor, and is condensed to obtain a furfural aqueous solution; the nitrogen is collected and returned to the boiler for recycling, and organic matter (protein and fat, etc.) that cannot generate furfural is converted into a solid acid catalyst under the action of the sulfuric acid catalyst, thereby promoting the reaction; S1 (3), concentration and dehydration refining The furfural aqueous solution obtained in step S1 (2) is concentrated to a concentration of 5-10 wt% by reverse osmosis and then subjected to aldehyde-water separation. The wastewater is collected and returned to step S1 (1) for the preparation of a dilute sulfuric acid aqueous solution. The furfural aqueous solution after aldehyde-water separation is further distilled and dehydrated to obtain 110-120 kg of furfural product with a purity greater than 99.5%; Step S2: Alkali and additives synergistically catalyze the degradation of phenolic lignin and dissolved silica The hydrolysis residue obtained in step S1 (1) is washed until neutral, and then added to a horizontal reactor with an alcoholic sodium hydroxide solution at a solid-liquid ratio of 1 kg: 3-8 L. An auxiliary agent is then added to the reactor for degradation and phenolization at a ratio of 1-3% of the total mass of the hydrolysis residue. After stirring evenly, the mixture is heated to 150-200° C. and degraded at a constant temperature for 2-4 hours. The mixed solution is filtered and separated to obtain an alkali-soluble residue (containing 40-50% cellulose, 20-30% undissolved lignin, and the rest water) and a composite filtrate containing degraded phenolized lignin and sodium silicate. Step S3: Self-assembly preparation of lignin-based nanohybrid materials A surfactant in an amount of 0.1 to 0.5% of the total mass of the filtrate is added to the composite filtrate obtained in step S2, the mixture is stirred and mixed for 0.5 to 1 hour, and then the temperature is raised to 70 to 95° C. The pH is then adjusted to 2 to 4 with an acid solution having a concentration of 1 to 5 mol / L, and the mixture is stirred for 1 to 2 hours to prepare a suspension of spherical nano-hybrid materials containing lignin-coated silica; the suspension is filtered to obtain a filter cake of the hybrid material, and the filter cake is washed with water 2 to 4 times and then set aside; the filtrate contains unprecipitated lignin, i.e., a monophenol-containing lignin alcohol aqueous solution is formed; Step S4: Ammonium chloride impregnation The hybrid material filter cake obtained in step S3 and an ammonium chloride aqueous solution with a concentration of 5-15 wt% are added to a reaction vessel at a solid-liquid ratio of 1 kg: 5-10 L, and the mixture is immersed at room temperature for 8-12 hours and then filtered. The obtained filter cake is dried at 80-100° C. to obtain ammonium chloride-impregnated hybrid material particles; Step S5: Carbon fixation and dehydration to prepare nitrogen-oxygen modified SiO2 / CBNO hybrid material The ammonium chloride-impregnated hybrid material particles prepared in step S4 were placed in a tube furnace, and in the presence of a gas medium, the temperature was first raised to 150-300°C at a rate of 3-5°C / min for pretreatment for 0.5-1.0 h, and then steam was introduced for protection, and then the temperature was raised to 600-800°C for treatment for 1-2 h, and finally the temperature was lowered to room temperature to obtain 60-100 kg of nitrogen-oxygen-modified SiO2 / CBNO hybrid material; Step S6: Surface modification of nanohybrid materials S6 (1), mixing the monophenol-containing lignin alcohol aqueous solution obtained in step S3 and the furfural solution obtained in step S1 (2) in a reaction kettle at a phenol-formaldehyde molar ratio of 1:0.8-1, adjusting the pH to 2-3 with a 3-5 mol / L sulfuric acid aqueous solution, then heating to 90-110°C for 1-2 hours, and distilling under reduced pressure until no liquid escapes, to prepare an anhydrous solid phenolic resin; S6 (2), adding 2 to 4 times the mass of anhydrous ethanol to the anhydrous solid phenolic resin obtained in step S6 (1), stirring to dissolve the phenolic resin to prepare an ethanol solution containing the phenolic resin, and recovering the precipitated inorganic salts such as sodium sulfate by filtration; S6 (3), adding the nitrogen oxide modified SiO2 / CBNO hybrid material prepared in step S5 to the ethanol solution containing phenolic resin prepared in step S6 (2) in a mass ratio of 1 to 3:100 of phenolic resin and nano hybrid material, stirring and dispersing for 0.2 to 0.5 hours to form a suspension; then adding a saturated ethanol solution of hexamethylenetetramine as a curing agent to the suspension in a mass ratio of 10 to 15:100 of curing agent and phenolic resin, adsorption reaction for 0.2 to 0.5 hours, recovering ethanol by vacuum distillation, and separating to obtain a solid intermediate phase; S6 (4), curing the solid mesophase obtained in step S6 (3) at a temperature of 80-120°C for 1-5 hours, then cooling to room temperature and breaking up to prepare 120-140 kg of a nano-hybrid material whose surface is modified by a lignin-based phenolic resin; Step S7: Activated carbon preparation S7 (1) Activated carbon is prepared using the alkali soluble residue obtained in step S2 as a raw material: the alkali soluble residue is soaked in 8 to 15 times the volume of a 10 wt% NH4Cl aqueous solution for 20 to 30 hours and then filtered; the filter residue is then dehydrated at 220 to 260°C for 0.5 to 1.0 h, and then carbonized at 550 to 650°C for 50 to 70 min after being protected by steam. After the material is discharged, it is neutralized with dilute acid and then washed with water several times until neutral, thereby preparing 130 to 150 kg of nitrogen oxide-modified food-grade activated carbon; S7 (2), the nitrogen oxide modified food grade activated carbon prepared in step S7 (1) is acid washed and then washed with water for several times until the inorganic metal ions (K + , Ca 2+ , Fe 3+ The content of 2-Hydroxy-1,2-Dimethyl ...
[0011] The present invention comprehensively utilizes 1000 kg of biomass to prepare 110-120 kg of furfural products, 60-100 kg of nitrogen-oxygen-modified SiO2 / CBNO hybrid materials, 100-140 kg of nano-hybrid materials whose surfaces are modified with lignin-based phenolic resins, and 130-150 kg of nitrogen-oxygen-modified food-grade activated carbon. Volatile organic matter and carbon dioxide generated by high-temperature pyrolysis in the process are discharged in the form of gas after environmentally friendly treatment.
[0012] The biochar in step S1 (1) is one or a mixture of wheat straw or wheat husk (including winter wheat), rice straw or rice husk, corn straw, corn cob, wood pond residue (industrial waste residue of xylose enterprise) containing lignin and silicon dioxide; The co-catalyst in step S1 (2) is one or a mixture of sodium chloride, potassium chloride, ferric chloride, and chromium chloride; The mass concentration of sodium hydroxide in the sodium hydroxide alcohol aqueous solution in step S2 is 3-8wt%, and the mass ratio of alcohol to water is 1:0.5-1; the alcohol is ethanol, ethylene glycol, etc.; The auxiliary agent in step S2 is sodium thiosulfate, sodium sulfite or hydrogen bromide; The surfactant in step S3 is one of PEG400, PEG2000, T-80, and sodium lauryl benzene sulfonate; The acid solution in step S3 is a sulfuric acid aqueous solution or a hydrochloric acid aqueous solution; The gas medium in step S5 is nitrogen, air, or a mixture of air and nitrogen.
[0013] Through the above technical solution, the present invention can bring the following beneficial effects: (1) The present invention uses alkali and additives to synergistically degrade phenolic lignin and reduce its molecular weight, laying the foundation for the preparation of nano-hybrid material particles; (2) The present invention adopts a method of surfactant dispersion in conjunction with alcohol-water solvent acid precipitation. Under the cooperation of alcohol-water solvent and surfactant, the surface tension is changed, the molecular surface hydroxyl groups of degraded phenolic lignin form hydrogen bonds with the surface hydroxyl groups of silica, completing the self-assembly process to prepare hybrid material nanoparticles, thus overcoming the technical obstacle of preparing hybrid material nanoparticles due to the different precipitation pH values of lignin and silica; (3) The present invention uses a monophenol-containing lignin alcohol-water solution (step S3) instead of phenol, and uses furfural (step S1 (2)) instead of formaldehyde to prepare a thermoplastic phenolic resin under sulfuric acid catalysis, which serves as a surface sealant and modifier for nano-hybrid material particles, seals surface voids, and improves compatibility with the rubber base material and chemical bonding function; (4) The present invention adopts a process of first dehydrating and then dissolving the phenolic resin with ethanol to precipitate inorganic salts, thereby eliminating the negative impact of inorganic salts on the reinforcement of rubber by nano-hybrid material particles; (5) The present invention completes the adsorption self-assembly process of nano-hybrid material particles, phenolic resin and curing agent in ethanol solution, and solidifies after dealcoholization to complete the surface chemical modification of nano-carbon black particles; (6) In the present invention, under the action of ammonium chloride, lignin is dehydrated and carbonized at low temperature, retaining the six-membered ring structure of lignin carbon and the organic carbon characteristics of the lignin aromatic ring, laying the foundation for the preparation of biomass carbon-based hybrid materials with the same microstructure as fossil carbon black; (7) The present invention uses nitrogen and oxygen as heteroatoms to be doped into the carbon skeleton structure, utilizing the lone pair electrons of nitrogen atoms to increase the electron cloud density on the surface of the material, and using oxygen to modify the surface of lignin carbon, thereby imparting surface active functional groups and improving the reaction activity with rubber; (8) The low-temperature carbonization of the present invention improves the yield of lignin carbon and obtains organic carbon with a microstructure similar to that of petroleum carbon black. This solves the technical problem that in the traditional pyrolysis method, lignin forms disordered inorganic carbon, which has significant differences in performance from petroleum carbon black and cannot be used as a reinforcing material. (9) Due to the low-temperature carbon fixation technology of the present invention, the lignin-based hybrid material contains a cross-linked aromatic structure. Under high-temperature treatment, carbon atoms can be conserved instead of being converted into carbon-containing gases. The structure is stable, which makes high-carbon-content lignin a promising precursor for producing valuable carbon materials. (10) In the present invention, different gas atmospheres are used to control the content of heteroatom nitrogen oxides on the carbon black surface during the low-temperature nitrogen-oxygen doping carbon fixation process; (11) The preparation method of the lignin-based hybrid material proposed in the present invention can also be used to prepare lignin-based nanohybrid materials or nanohybrid materials whose surfaces are modified with monophenol lignin / furfural-based phenolic resins according to market demand to meet different market demands for cost-effectiveness; (12) The present invention uses water vapor as a protective gas, which is more economical, environmentally friendly and reduces costs than nitrogen; (13) The cost of producing capacitor carbon by acid washing and then water washing of food-grade activated carbon is low, and the price advantage in participating in market competition is great; (14) The present invention utilizes the advantages of forming a hollow precursor after dissolving hemicellulose and part of lignin from biochar, which is a raw material for producing high-performance activated carbon; (15) The present invention does not require the complete dissolution of lignin, but leaves a portion of lignin in the cellulose to prepare activated carbon, which has better performance, saving extractants and improving product performance. At the same time, the water contained in the lignin can react with the carbon to activate it after high-temperature gasification. (16) The alkaline pulping method used in the present invention is the best method for extracting lignin from biochar; (17) In the present invention, NH4Cl serves as both a dehydration catalyst for lignin and a nitrogen source for nitrogen doping; (18) my country has both the production base for furfural and abundant biochar raw materials for furfural production. DETAILED DESCRIPTION
[0014] To more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention. To avoid obscuring the essence of the present invention, well-known methods and processes are not described in detail.
[0015] Example 1: Step S1: Furfural production from hemicellulose S1 (1) Hydrolysis of raw materials at normal pressure and low temperature 1000kg (dry basis) of corn straw was crushed to 20mm and mixed with a 1wt% dilute sulfuric acid aqueous solution in a reactor at a solid-liquid ratio of 1kg:8L. The mixture was then heated to 100°C to catalytically hydrolyze the hemicellulose in the biomass to produce xylose. After filtration, a 10wt% xylose aqueous solution and hydrolysis residue were obtained. The hydrolysis residue (mainly composed of cellulose, lignin, and silicate) was sent to the hybrid material and activated carbon production workshop for comprehensive utilization in subsequent steps. S1 (2), fixed bed catalytic dehydration A 2 mol / L aqueous solution of sulfuric acid catalyst is added to a reactor, heated to boiling, and then sodium chloride as a co-catalyst is added to saturation, and stirred to form a catalyst rotating liquid surface layer; while nitrogen is continuously introduced into the reactor, a 10 wt% xylose aqueous solution obtained in step S1 (1) is sprayed onto the rotating liquid surface layer, so that the xylose aqueous solution and the catalyst rotating liquid surface layer come into contact and undergo a dehydration reaction, and the generated furfural is quickly carried out by a mixture of nitrogen and water vapor, and is condensed in a condensing device to obtain a furfural aqueous solution; the nitrogen is collected and returned to the boiler for recycling, and organic matter (protein and fat, etc.) that cannot generate furfural is converted into a solid acid catalyst under the action of sulfuric acid, thereby promoting the reaction; S1 (3), concentration and dehydration refining The furfural aqueous solution obtained in step S1 (2) is concentrated to a concentration of 10 wt% by reverse osmosis and then enters the aldehyde-water separation device for aldehyde-water separation. The wastewater is collected and returned to step S1 (1) for use in preparing a dilute sulfuric acid aqueous solution. The furfural aqueous solution after aldehyde-water separation is further distilled and dehydrated to obtain 110 kg of furfural product with a purity of 99.7%; Step S2: Alkali and additives synergistically catalyze the degradation of phenolic lignin and dissolved silica The hydrolysis residue in step S1 (1) is washed with water until it is neutral, and then added to a horizontal reactor with a sodium hydroxide alcohol aqueous solution (the mass concentration of sodium hydroxide in the sodium hydroxide alcohol aqueous solution is 5wt%, the mass ratio of alcohol to water is 1:0.5, and the alcohol is ethanol) at a solid-liquid ratio of 1kg:8L, and then an auxiliary agent sodium thiosulfate is added according to 1wt% of the total mass of the hydrolysis residue for degradation of phenolization. After stirring evenly, the mixture is heated to 180°C and degraded at a constant temperature for 3h. After the mixed solution is separated by filtration, an alkali-soluble residue (containing 45% cellulose, 25% undissolved lignin, and 30% water) and a mixed filtrate containing degraded phenolized lignin and sodium silicate are obtained; Step S3: Self-assembly preparation of lignin-based nanohybrid materials To the mixed filtrate obtained in step S2, a surfactant PEG2000 was added at a concentration of 0.2% of the total mass of the filtrate, and the mixture was stirred for 0.5 h, then heated to 90° C., neutralized with a 2 mol / L aqueous sulfuric acid solution to a pH of 2, and then stirred for 1 h to prepare a suspension of spherical nano-hybrid materials containing lignin-coated silica; the suspension was filtered to obtain a hybrid material filter cake, which was washed twice and then set aside; the filtrate contained unprecipitated lignin, i.e., a monophenol-containing lignin alcohol aqueous solution was formed; Step S4: Ammonium chloride impregnation The hybrid material filter cake obtained in step S3 and an ammonium chloride aqueous solution with a concentration of 10 wt % were added to a reaction vessel at a solid-liquid ratio of 1 kg:5 L, and the mixture was immersed at room temperature for 12 hours and then filtered. The obtained filter cake was dried at 100° C. to obtain ammonium chloride-impregnated hybrid material particles; Step S5: Carbon fixation and dehydration to prepare nitrogen-oxygen modified SiO2 / CBNO hybrid material The ammonium chloride-impregnated hybrid material particles prepared in step S4 were placed in a tube furnace and pretreated at a rate of 5°C / min to 250°C for 1.0 h in the presence of air. After water vapor protection, the temperature was raised to 600°C for 2 h, and finally cooled to room temperature to obtain nitrogen oxide-modified SiO2 / CBNO hybrid material (yield 100 kg) with a particle size of 50 nm.
[0016] Example 2: The sulfuric acid in step S3 of Example 1 was replaced by hydrochloric acid, and the other conditions were the same as those in Example 1 to obtain a nitrogen oxide-modified SiO2 / CBNO hybrid material (yield 100 kg) with a particle size of 135 nm.
[0017] Example 3: The mass concentration of sodium hydroxide in the sodium hydroxide alcohol aqueous solution in step S2 in Example 1 was changed to 5 wt % and the mass ratio of ethanol to water was 1:1. Other conditions were the same as in Example 1 to obtain a nitrogen oxide-modified SiO2 / CBNO hybrid material (yield 100 kg) with a particle size of 105 nm.
[0018] Example 4: The alcohol in the sodium hydroxide alcohol aqueous solution in step S2 of Example 1 was changed to ethylene glycol; other conditions were the same as in Example 1, and a nitrogen oxide-modified SiO2 / CBNO hybrid material (yield 100 kg) with a particle size of 58 nm was obtained.
[0019] Example 5: The surfactant PEG2000 in step S3 of Example 1 was replaced with T-80; other conditions were the same as in Example 1, and a nitrogen oxide-modified SiO2 / CBNO hybrid material (yield 100 kg) with a particle size of 68 nm was obtained.
[0020] Example 6: The heat treatment temperature in step S5 in Example 1 was changed from 600° C. to 800° C., and other conditions were the same as in Example 1 to obtain a nitrogen-oxygen modified SiO 2 / CBNO hybrid material (yield 85 kg) with a particle size of 56 nm.
[0021] Example 7: The corn straw in step S1 of Example 1 was replaced with winter wheat straw. Other conditions were the same as those in Example 1, and a nitrogen oxide-modified SiO2 / CBNO hybrid material (yield 60 kg) with a particle size of 48 nm was obtained.
[0022] Example 8: The corn straw in step S1 of Example 1 was replaced with wheat straw. Other conditions were the same as those in Example 1, and a nitrogen oxide-modified SiO2 / CBNO hybrid material (yield 60 kg) with a particle size of 43 nm was obtained.
[0023] Example 9: The corn straw in step S1 of Example 1 was replaced with rice straw. Other conditions were the same as those in Example 1, and a nitrogen oxide-modified SiO2 / CBNO hybrid material (yield 80 kg) with a particle size of 50 nm was obtained.
[0024] Example 10: The surface of the nano-hybrid material prepared in Example 1 was modified as follows: (1) The monophenol-containing lignin alcohol aqueous solution obtained in step S3 of Example 1 and the furfural solution obtained in step S1 (2) were mixed in a reactor at a phenol-formaldehyde molar ratio of 1:1, and the pH was adjusted to 2 with a 5 mol / L sulfuric acid aqueous solution. The mixture was then heated to 100° C. and reacted for 1 h. The mixture was then distilled under reduced pressure until no liquid escaped, thereby preparing an anhydrous solid phenolic resin. (2) adding 3 times the mass of anhydrous ethanol to the anhydrous solid phenolic resin obtained in step (1) of this embodiment, stirring to dissolve the phenolic resin to prepare an ethanol solution containing the phenolic resin, and recovering the precipitated inorganic salts such as sodium sulfate by filtration; (3) The nitrogen oxide modified SiO2 / CBNO hybrid material prepared in step S5 of Example 1 was added to the ethanol solution containing phenolic resin prepared in step (2) of this Example at a mass ratio of 1.5:100 between the phenolic resin and the nano-hybrid material, and the mixture was stirred and dispersed for 0.5 h to form a suspension; then, a saturated ethanol solution of hexamethylenetetramine, a curing agent, was added to the suspension at a mass ratio of 15:100 between the curing agent and the phenolic resin, and the mixture was subjected to adsorption reaction for 0.5 h. The ethanol was recovered by vacuum distillation, and a solid intermediate phase was separated; (4) The solid mesophase obtained in step (3) of this example was cured at 100°C for 2 h, then cooled to room temperature and dispersed to prepare 118 kg of a nanohybrid material with a surface modified by a lignin-based phenolic resin and a particle size of 82 nm.
[0025] Example 11: The alkali slag prepared in step S2 of Example 1 is subjected to carbonization / activation modification to prepare activated carbon, and the steps are as follows: (1) Activated carbon was prepared using the alkali-soluble residue obtained in step S2 of Example 1 as a raw material: the alkali-soluble residue was soaked in 10 times the volume of a 10 wt% NH4Cl aqueous solution for 24 hours and then filtered; the filter residue was then dehydrated at 250°C for 0.5 hours, passed through a steam protection chamber, and carbonized at 600°C for 60 minutes. After discharge, the material was neutralized with dilute acid and washed with water several times until neutral, thereby preparing 135 kg of nitrogen-oxide-modified food-grade activated carbon; (2) The food-grade activated carbon modified with nitrogen oxides prepared in step (1) of Example 1 was acid-washed and then washed with water for several times until the inorganic metal ions (K + , Ca 2+ , Fe 3+ The content of 2-Hydroxy-1,2-Dimethyl ...
[0026] Adsorption and electrochemical performance test results show that the activated carbon performance: specific surface area 2200m 2 / g, the methylene blue adsorption value is 2320 mg / g, the iodine adsorption value is 1100 mg / g, the capacitor carbon performance: mass specific capacity 173 F / g, volume specific capacity 74 F / cc, and the capacitance retention rate after 1000 cycles is 94%.
[0027] Mechanical properties of the nitroxide-modified SiO2 / CBNO hybrid materials prepared in Examples 1-9 and the nanohybrid material with a lignin-based phenolic resin surface modification prepared in Example 10 were tested for their reinforcing properties in rubber. The specific rubber formulation used for testing consisted of the following components: 100 parts natural rubber, 50 parts hybrid material, 6 parts aromatic oil, 5 parts zinc oxide, 1 part antioxidant 4010NA, 2.5 parts stearic acid, 2.3 parts sulfur, 1 part paraffin wax, and 0.7 part accelerator NOBS (except for the homemade hybrid material, all others were purchased commercially). The test results are shown in Table 1.
[0028] Table 1: Sample particle size and mechanical properties of filled vulcanizates
[0029] As can be seen from Table 1, under the action of surfactants and alcohols (ethanol and ethylene glycol), the hybrid materials prepared in Examples 1 to 10 significantly improved the mechanical properties of the rubber products after being added to the rubber products. The hybrid material modified with phenolic resin in Example 10 had a better mechanical property reinforcement effect.
Claims
1. A method for comprehensive utilization of biochar, characterized by: The steps are as follows: Step S1: Furfural production from hemicellulose S1 (1) Hydrolysis of raw materials at normal pressure and low temperature 1000kg of biomass on a dry basis is crushed to 10-20mm, mixed with a 1-3wt% dilute sulfuric acid aqueous solution in a reactor at a solid-liquid ratio of 1kg:5-8L, and then heated to 100-120°C to catalytically hydrolyze the hemicellulose in the biomass to produce xylose. After filtration, a 10-15wt% xylose aqueous solution and hydrolysis residue are obtained. The hydrolysis residue is sent to the hybrid material and activated carbon production workshop for subsequent comprehensive utilization; S1 (2), fixed bed catalytic dehydration A 1.0-3.0 mol / L aqueous solution of sulfuric acid catalyst is added to a reactor, heated to boiling, and then a co-catalyst is added until saturated, and stirred to form a catalyst rotating liquid surface layer; while nitrogen is continuously introduced into the reactor, a 10-15 wt% xylose aqueous solution obtained in step S1 (1) is sprayed onto the rotating liquid surface layer, so that the xylose aqueous solution and the catalyst rotating liquid surface layer come into contact and undergo a dehydration reaction, and the generated furfural is quickly carried out by a mixed gas of nitrogen and water vapor, and is condensed to obtain a furfural aqueous solution; the nitrogen is collected and returned to the boiler for recycling, and organic matter that cannot generate furfural is converted into a solid acid catalyst under the action of the sulfuric acid catalyst, thereby promoting the reaction; S1 (3), concentration and dehydration refining The furfural aqueous solution obtained in step S1 (2) is concentrated to a concentration of 5-10 wt% by reverse osmosis and then subjected to aldehyde-water separation. The wastewater is collected and returned to step S1 (1) for the preparation of a dilute sulfuric acid aqueous solution. The furfural aqueous solution after aldehyde-water separation is further distilled and dehydrated to obtain 110-120 kg of furfural product with a purity greater than 99.5%; Step S2: Alkali and additives synergistically catalyze the degradation of phenolic lignin and dissolved silica The hydrolysis residue obtained in step S1 (1) is washed until neutral, and then added to a horizontal reactor with a sodium hydroxide alcohol aqueous solution at a solid-liquid ratio of 1 kg: 3-8 L. Then, an auxiliary agent is added according to 1-3% of the total mass of the hydrolysis residue for degradation of phenolization. After stirring evenly, the mixture is heated to 150-200°C and degraded at a constant temperature for 2-4 hours. The mixed solution is filtered and separated to obtain an alkali-soluble residue and a composite filtrate containing degraded phenolized lignin and sodium silicate; Step S3: Self-assembly preparation of lignin-based nanohybrid materials Adding a surfactant in an amount of 0.1 to 0.5% of the total mass of the filtrate to the composite filtrate obtained in step S2, stirring and mixing for 0.5 to 1 hour, then heating to 70 to 95° C., adjusting the pH to 2 to 4 with an acid solution having a concentration of 1 to 5 mol / L, and continuing stirring for 1 to 2 hours to prepare a suspension of spherical nano-hybrid materials containing lignin-coated silica; The suspension is filtered to obtain a filter cake of the hybrid material, which is washed 2 to 4 times and then set aside; the filtrate contains unprecipitated lignin, which forms a monophenol-containing lignin alcohol aqueous solution; Step S4: Ammonium chloride impregnation The hybrid material filter cake obtained in step S3 and an ammonium chloride aqueous solution with a concentration of 5-15 wt% are added to a reaction vessel at a solid-liquid ratio of 1 kg: 5-10 L, and the mixture is immersed at room temperature for 8-12 hours and then filtered. The obtained filter cake is dried at 80-100° C. to obtain ammonium chloride-impregnated hybrid material particles; Step S5: Carbon fixation and dehydration to prepare nitrogen-oxygen modified SiO2 / CBNO hybrid material The ammonium chloride-impregnated hybrid material particles prepared in step S4 were placed in a tube furnace, and in the presence of a gas medium, the temperature was first raised to 150-300°C at a rate of 3-5°C / min for pretreatment for 0.5-1.0 h, and then steam was introduced for protection, and then the temperature was raised to 600-800°C for treatment for 1-2 h, and finally the temperature was lowered to room temperature to obtain 60-100 kg of nitrogen-oxygen-modified SiO2 / CBNO hybrid material; Step S6: Surface modification of nanohybrid materials S6 (1), mixing the monophenol-containing lignin alcohol aqueous solution obtained in step S3 and the furfural solution obtained in step S1 (2) in a reaction kettle at a phenol-formaldehyde molar ratio of 1:0.8-1, adjusting the pH to 2-3 with a 3-5 mol / L sulfuric acid aqueous solution, then heating to 90-110°C for 1-2 hours, and distilling under reduced pressure until no liquid escapes, to prepare an anhydrous solid phenolic resin; S6 (2), adding 2 to 4 times the mass of anhydrous ethanol to the anhydrous solid phenolic resin obtained in step S6 (1), stirring and dissolving the phenolic resin to prepare an ethanol solution containing the phenolic resin, and recovering the precipitated sodium sulfate inorganic salt by filtration; S6 (3), adding the nitrogen oxide modified SiO2 / CBNO hybrid material prepared in step S5 to the ethanol solution containing phenolic resin prepared in step S6 (2) in a mass ratio of 1 to 3:100 of phenolic resin and nano hybrid material, stirring and dispersing for 0.2 to 0.5 hours to form a suspension; then adding a saturated ethanol solution of hexamethylenetetramine as a curing agent to the suspension in a mass ratio of 10 to 15:100 of curing agent and phenolic resin, adsorption reaction for 0.2 to 0.5 hours, recovering ethanol by vacuum distillation, and separating to obtain a solid intermediate phase; S6 (4), curing the solid mesophase obtained in step S6 (3) at a temperature of 80-120°C for 1-5 hours, then cooling to room temperature and breaking up to prepare 120-140 kg of a nano-hybrid material whose surface is modified by a lignin-based phenolic resin; Step S7: Activated carbon preparation S7 (1) Activated carbon is prepared using the alkali soluble residue obtained in step S2 as a raw material: the alkali soluble residue is soaked in 8 to 15 times the volume of a 10 wt% NH4Cl aqueous solution for 20 to 30 hours and then filtered; the filter residue is then dehydrated at 220 to 260°C for 0.5 to 1.0 h, and then carbonized at 550 to 650°C for 50 to 70 min after being protected by steam. After the material is discharged, it is neutralized with dilute acid and then washed with water several times until neutral, thereby preparing 130 to 150 kg of nitrogen oxide-modified food-grade activated carbon; S7 (2) washing the nitrogen oxide modified food-grade activated carbon prepared in step S7 (1) with acid and then with water for multiple times until the inorganic metal ion content is less than 100 ppm, thereby obtaining capacitor carbon.
2. The method for comprehensive utilization of biochar according to claim 1, wherein: The biochar in step S1 (1) is a mixture of one or more of wheat straw or wheat husk, rice straw or rice husk, corn straw, corn cob, and wood pond residue containing lignin and silicon dioxide.
3. The method for comprehensive utilization of biochar according to claim 1, wherein: The co-catalyst in step S1 (2) is one or a mixture of sodium chloride, potassium chloride, ferric chloride, and chromium chloride.
4. The method for comprehensive utilization of biochar according to claim 1, wherein: In step S2, the mass concentration of sodium hydroxide in the sodium hydroxide alcohol aqueous solution is 3-8 wt %, and the mass ratio of alcohol to water is 1:0.5-1; the alcohol is ethanol or ethylene glycol.
5. The method for comprehensive utilization of biochar according to claim 1, wherein: The auxiliary agent in step S2 is sodium thiosulfate, sodium sulfite or hydrogen bromide.
6. The method for comprehensive utilization of biochar according to claim 1, wherein: The surfactant in step S3 is one of PEG400, PEG2000, T-80, and sodium lauryl benzene sulfonate.
7. The method for comprehensive utilization of biochar according to claim 1, characterized in that: The acid solution in step S3 is a sulfuric acid aqueous solution or a hydrochloric acid aqueous solution.
8. The method for comprehensive utilization of biochar according to claim 1, wherein: The gas medium in step S5 is nitrogen, air, or a mixture of air and nitrogen.