A biobased resin carbon and a method for producing the same and a method for producing 2,2,4,4-tetramethyl-1,3-cyclobutanedione

Abstract

The application provides a kind of bio-based resin carbon and its preparation method and the preparation method of 2,2,4,4-tetramethyl-1,3-cyclobutanedione, belongs to catalyst technical field.The application can make bio-based resin carbon have abundant porosity, lamellar structure and higher specific surface area by preparing bio-based resin first, then preparing bio-based resin carbon by carbonization, enhance the adsorption capacity of reactant.At the same time, bio-based resin carbon has higher mechanical strength and structural stability, can maintain the integrity of bio-based resin carbon for a long time, and has higher stability.Moreover, the bio-based resin carbon prepared by the application takes carbon skeleton as main body, the surface has abundant defects, heteroatom functional group and multi-level pore channel constitute active system, when it is used as the catalyst for preparing DMK by cracking isobutyric anhydride, it can improve the catalytic effect of cracking, has the advantages of good stability and low cost.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a bio-based resin carbon and its preparation method and a method for preparing 2,2,4,4-tetramethyl-1,3,-cyclobutanedione. Background Technology

[0002] 2,2,4,4-Tetramethyl-1,3,-cyclobutanedione (TMCB) is an important chemical intermediate used to synthesize the high-end polyester monomer 2,2,4,4-tetramethyl-1,3,-cyclobutanediol (CBDO). Currently, TMCB is mainly synthesized using the isobutyric anhydride pyrolysis method, and the synthetic route is as follows: Isobutyric anhydride DMK TMCB In this synthetic route, isobutyric anhydride is thermally pyrolyzed to prepare dimethyl ketene (DMK), and DMK is then dimerized to prepare TMCB. The thermal pyrolysis of isobutyric anhydride to prepare DMK includes direct thermal pyrolysis or thermal pyrolysis under the action of a catalyst. Direct thermal pyrolysis is achieved by precisely controlling thermal pyrolysis conditions such as high temperature, low pressure, and extremely short residence time. Although this process does not require the introduction of a catalyst, the pyrolysis reaction efficiency is low, the DMK yield is poor, and the reactor suffers from severe carbon buildup. Thermal pyrolysis under the action of a catalyst can improve the efficiency of the pyrolysis reaction and the DMK yield. Currently, common catalysts mainly include perovskite oxide catalysts, supported metal oxide catalysts, and magnetic composite supported ionic liquid catalysts. Although these catalysts can improve the efficiency of isobutyric anhydride thermal pyrolysis to prepare DMK, they are prone to problems such as carbon buildup, agglomeration, and loss, resulting in poor catalyst stability; furthermore, catalysts prepared from noble metals and ionic liquids have the problem of high cost.

[0003] Therefore, how to prepare a low-cost thermal cracking catalyst that improves cracking catalytic effect and stability is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a bio-based resin carbon and its preparation method, as well as a method for preparing 2,2,4,4-tetramethyl-1,3,-cyclobutanedione. The bio-based resin carbon prepared by this invention has the characteristics of low cost, improved catalytic cracking effect, and good stability.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing bio-based resin carbon, comprising the following steps: (1) After mixing biomass powder with alkaline solution, the mixture is cooked and then separated into solid and liquid components to obtain a colloidal solution; (2) The colloidal solution obtained in step (1) is mixed with an initiator and subjected to a polymerization reaction to obtain a bio-based resin; (3) The bio-based resin obtained in step (2) is carbonized in an inert atmosphere to obtain bio-based resin carbon.

[0006] Preferably, the biomass powder in step (1) includes one or more of straw powder, branch powder and corn cob powder.

[0007] Preferably, the particle size of the biomass powder in step (1) is 40-70 mesh.

[0008] Preferably, the alkaline solution in step (1) is a sodium hydroxide solution with a concentration of 0.1~1 mol / L.

[0009] Preferably, the temperature of the cooking process in step (1) is 90~120℃, the pressure of the cooking process is 0.1~1MPa, and the cooking time is 2~5h.

[0010] Preferably, the initiator in step (2) includes 2,2-azobisisobutyronitrile or diacetyl peroxide.

[0011] Preferably, the polymerization temperature in step (2) is -20 to -10°C, and the polymerization time is 12 to 24 hours.

[0012] Preferably, the carbonization temperature in step (3) is 500~900℃ and the carbonization time is 1~6h.

[0013] The present invention also provides bio-based resin carbon prepared by the preparation method described in the above technical solution.

[0014] The present invention also provides a method for preparing 2,2,4,4-tetramethyl-1,3,-cyclobutanedione, comprising: Isobutyric anhydride is mixed with a catalyst and subjected to a thermal pyrolysis reaction to obtain dimethyl ketene; the catalyst is the bio-based resin carbon described in the above technical solution; The dimethyl ketene is absorbed by an absorbent to obtain a saturated solution of dimethyl ketene. The saturated solution of dimethyl ketene is then subjected to a dimerization reaction to obtain 2,2,4,4-tetramethyl-1,3,-cyclobutanedione.

[0015] This invention provides a method for preparing bio-based resin carbon, comprising the following steps: mixing biomass powder with an alkaline solution and then performing a cooking treatment, followed by solid-liquid separation to obtain a colloidal solution; mixing the colloidal solution with an initiator and performing a polymerization reaction to obtain a bio-based resin; and carbonizing the bio-based resin in an inert atmosphere to obtain bio-based resin carbon. This invention first uses an alkaline solution to cook the biomass powder, causing the cellulose chains in the biomass powder to break down, improving the reactivity and swelling properties of cellulose; simultaneously, it breaks the ether and ester bonds in lignin, dissolving and decomposing large-molecule lignin, thus breaking the dense structure of the biomass. This invention removes recalcitrant cellulose, a small amount of residual lignin, residual hemicellulose (alkali-resistant polysaccharide components), primary ash (minerals such as silicon, potassium, calcium, and magnesium, and silt), and stubborn impurities (organic impurities such as waxes and resins) through solid-liquid separation to obtain a colloidal solution. This invention mixes the colloidal solution with an initiator, performs a polymerization reaction to obtain a bio-based resin, and then carbonizes the bio-based resin in an inert atmosphere to obtain bio-based resin carbon. This invention prepares a bio-based resin first, and then prepares bio-based resin carbon through carbonization. In the alkali lignin liquid, macromolecules aggregate and arrange themselves through electrostatic and molecular attraction, forming a gel framework with uniform gaps after cross-linking and curing. The sodium salt remaining after alkali boiling is uniformly embedded in these gaps, acting as a site-filling template to fix the space within the pores. During high-temperature carbonization, small molecule gases escape from the resin, leaving voids. Afterwards, the sodium salt is washed away, transforming the salt-occupied spaces into uniformly sized, neatly arranged, interconnected pores. The cross-linked resin framework is less prone to high-temperature collapse, and the ordered pores are preserved. Therefore, the bio-based resin carbon prepared by this invention possesses abundant porosity, a disordered layered graphite stacked structure formed during carbonization, and a high specific surface area, providing numerous active sites. Its ordered pore structure plays a crucial role in enhancing the mass transfer process and increasing the adsorption capacity of reactants. Simultaneously, the bio-based resin carbon exhibits high mechanical strength and structural stability, resisting breakage or powdering under dynamic water flow or high-pressure reaction conditions, demonstrating high stability. Furthermore, the bio-based resin carbon prepared in this invention is based on a carbon skeleton, with abundant defects, heteroatom functional groups, and hierarchical channels forming an active system. The carbon skeleton mediates electron transfer, driving the catalytic reaction. Oxygen-containing, nitrogen-containing, and sulfonic acid groups in the bio-based resin carbon form acid-base active sites, activating the substrate and lowering the reaction energy barrier. The π-π interactions of the carbon skeleton and the pore structure enable substrate enrichment, mass transfer optimization, and reaction selectivity regulation, improving catalytic reaction efficiency and promoting isobutyric anhydride cleavage and DMK generation. The bio-based resin carbon surface possesses abundant Lewis acid-base sites, which synergistically activate cleavage reactants through electron pair donation and acceptance: Lewis acid sites capture lone pairs of electrons from substrate oxygen atoms, weakening intramolecular CO bonds to promote bond breaking; Lewis base sites supply electron pairs to cleavage radicals, stabilizing intermediates and inhibiting coking; the orderly interconnected pores of the material ensure sufficient contact between reactants and various Lewis sites, significantly improving catalytic activation efficiency.Therefore, the bio-based resin carbon prepared in this invention utilizes the synergistic effect of carbon skeleton + surface defects / heteroatom functional groups + hierarchical channels to drive the reaction through three pathways: electron transfer, acid-base site activation, and adsorption-desorption regulation, forming a "structure-site-function" matching mechanism. When used as a catalyst for the pyrolysis of isobutyric anhydride to prepare DMK, it can increase the yield of DMK by at least 30%, significantly improving the pyrolysis catalytic effect. Furthermore, it has the advantages of good stability and low cost. Detailed Implementation

[0016] This invention provides a method for preparing bio-based resin carbon, comprising the following steps: (1) After mixing biomass powder with alkaline solution, the mixture is cooked and then separated into solid and liquid components to obtain a colloidal solution; (2) The colloidal solution obtained in step (1) is mixed with an initiator and subjected to a polymerization reaction to obtain a bio-based resin; (3) The bio-based resin obtained in step (2) is carbonized in an inert atmosphere to obtain bio-based resin carbon.

[0017] This invention involves mixing biomass powder with alkaline solution, then cooking the mixture, followed by solid-liquid separation to obtain a colloidal solution.

[0018] In this invention, the biomass powder preferably includes one or more of straw powder, branch powder, and corn cob powder. This invention uses the above-mentioned biomass powder, which has the advantages of abundant sources and low cost.

[0019] In this invention, the particle size of the biomass powder is preferably 40-70 mesh. As an embodiment of this invention, the particle size of the biomass powder can be 40 mesh, 50 mesh, 60 mesh, or 70 mesh. By controlling the particle size of the biomass powder, this invention can increase the contact area with the alkali solution, thereby ensuring sufficient cellulose chain scission in the biomass powder.

[0020] In this invention, the method for preparing the biomass powder preferably includes: drying and pulverizing the biomass in sequence to obtain biomass powder.

[0021] In this invention, the biomass preferably includes one or more of straw, branches, and corn cobs.

[0022] In this invention, the drying temperature is preferably 60°C, and the drying time is preferably 12 hours. This invention removes moisture from biomass through drying, which is more conducive to the thorough pulverization into biomass powder.

[0023] The present invention does not impose any special limitations on the operation method of the pulverization. Conventional pulverization methods can be used to achieve the required particle size of the biomass powder.

[0024] In this invention, the alkaline solution is preferably a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is preferably 0.1~1 mol / L. As an embodiment of this invention, the concentration of the sodium hydroxide solution can be 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, or 1 mol / L. This invention controls the concentration of the sodium hydroxide solution within the above range, achieving a higher concentration, which is more conducive to the complete scission of cellulose chains in biomass powder.

[0025] In this invention, the preferred ratio of the mass of the biomass powder to the volume of the alkaline solution is (5~30) g: (100~400) mL, and more preferably 20 g: 300 mL.

[0026] The present invention does not have any particular limitation on the method of mixing the biomass powder and the alkaline solution; it is sufficient to mix the two evenly.

[0027] In this invention, the preferred temperature for the cooking treatment is 90-120°C; the preferred pressure for the cooking treatment is 0.1-1 MPa; and the preferred cooking time is 2-5 hours. As an embodiment of this invention, the cooking temperature can be 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, or 120°C; the cooking pressure can be 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, or 1 MPa; and the cooking time can be 2 hours, 3 hours, 4 hours, or 5 hours. Under the above conditions, the cooking treatment of this invention allows for a complete reaction between the biomass powder and the alkaline solution.

[0028] The present invention does not specifically limit the method of solid-liquid separation. Any conventional solid-liquid separation method that can separate the filtrate from the solid impurities can be used.

[0029] After obtaining the colloidal solution, the present invention mixes the colloidal solution with an initiator and carries out a polymerization reaction to obtain a bio-based resin.

[0030] In this invention, the initiator preferably includes 2,2-azobisisobutyronitrile or diacetyl peroxide. By using the initiator, this invention enables polymerization reactions with soluble alkali lignin and dissolved hemicellulose degradation products (such as polysaccharides and monosaccharides) in colloidal solutions to obtain bio-based resins.

[0031] In this invention, the initiator preferably comprises 1-5% by mass of the colloidal solution. As an embodiment of this invention, the initiator may comprise 1%, 2%, 3%, 4%, or 5% by mass of the colloidal solution.

[0032] The present invention does not have any particular limitation on the method of mixing the colloidal solution and the initiator; it is sufficient to mix the two evenly.

[0033] In this invention, the preferred temperature for the polymerization reaction is -20 to -10°C; the preferred reaction time is 12 to 24 hours. As an embodiment of this invention, the polymerization reaction temperature can be -20°C, -19°C, -18°C, -17°C, -16°C, -15°C, -14°C, -13°C, -12°C, -11°C, or -10°C; the reaction time can be 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, or 24 hours. This invention enables the colloidal solution and initiator to fully react at the above temperatures and times to form a bio-based resin.

[0034] In this invention, the polymerization reaction is preferably carried out in a spherical mold. By conducting the polymerization reaction in a spherical mold and controlling the mold to a certain size, this invention can control the uniform particle size of the bio-based resin.

[0035] In an embodiment of the present invention, the diameter of the sphere in the spherical mold can be 0.4 cm; the width of the outer shell of the spherical mold can be 15 cm and the length can be 30 cm.

[0036] After obtaining the bio-based resin, the present invention performs carbonization treatment on the bio-based resin in an inert atmosphere to obtain bio-based resin carbon.

[0037] In this invention, the inert atmosphere is preferably nitrogen. By performing carbonization treatment under an inert atmosphere, this invention enables the bio-based resin to be fully carbonized while minimizing losses.

[0038] In this invention, the carbonization temperature is preferably 500~900℃; the carbonization time is preferably 1~6h. As an embodiment of this invention, the carbonization temperature can be 500℃, 600℃, 700℃, 800℃ or 900℃; the carbonization time can be 1h, 2h, 3h, 4h, 5h or 6h.

[0039] The present invention also provides bio-based resin carbon prepared by the preparation method described in the above technical solution.

[0040] In this invention, the particle size of the bio-based resin carbon is preferably 0.2~1 cm, more preferably 0.4 cm; the specific surface area of ​​the bio-based resin carbon is preferably 400~800 m². 2 / g, more preferably 500~650m 2 / g; the pore size of the bio-based resin carbon is preferably 20~50nm, more preferably 30~40nm.

[0041] The present invention also provides a method for preparing 2,2,4,4-tetramethyl-1,3,-cyclobutanedione, comprising: Isobutyric anhydride is mixed with a catalyst and subjected to a thermal pyrolysis reaction to obtain dimethyl ketene; the catalyst is the bio-based resin carbon described in the above technical solution; The dimethyl ketene is absorbed by an absorbent to obtain a saturated solution of dimethyl ketene. The saturated solution of dimethyl ketene is then subjected to a dimerization reaction to obtain 2,2,4,4-tetramethyl-1,3,-cyclobutanedione.

[0042] In this invention, isobutyric anhydride is mixed with a catalyst and subjected to a thermal cracking reaction to obtain dimethyl ketone.

[0043] In this invention, the mixing of isobutyric anhydride and catalyst is preferably carried out in a pyrolysis reactor. The preferred method for mixing is to add the catalyst to the pyrolysis reactor and then introduce isobutyric anhydride. This invention does not impose any particular limitation on the type of pyrolysis reactor; any conventional pyrolysis reactor may be used.

[0044] In this invention, the catalyst is the bio-based resin carbon described in the above-mentioned technical solution. This invention utilizes the bio-based resin carbon described in the above-mentioned technical solution. The bio-based resin carbon contains oxygen-, nitrogen-, and sulfonic acid functional groups to form acid-base active sites, activating the substrate and lowering the reaction energy barrier. The π-π interactions of the carbon skeleton and the pore structure enable substrate enrichment, mass transfer optimization, and reaction selectivity regulation, thereby improving catalytic reaction efficiency and promoting the cracking of isobutyric anhydride and the generation of DMK.

[0045] In this invention, the feed rate of isobutyric anhydride is preferably 80~150mL / h, more preferably 120mL / h.

[0046] In this invention, when the feed rate of isobutyric anhydride is 120 mL / h, the mass of the catalyst is preferably 5-10 g, more preferably 5-8 g. This invention improves the efficiency of isobutyric anhydride cracking by controlling the feed rate of isobutyric anhydride and the volume of the catalyst, thus enabling a more complete isobutyric anhydride cracking reaction.

[0047] In this invention, the temperature of the thermal decomposition reaction is preferably 200~500℃, more preferably 450℃; the pressure of the thermal decomposition reaction is preferably -0.05~0.1MPa. As an embodiment of this invention, the temperature of the thermal decomposition reaction can be 200℃, 250℃, 300℃, 350℃, 400℃, 450℃, or 500℃; the pressure of the thermal decomposition reaction can be -0.05MPa, -0.06MPa, -0.07MPa, -0.08MPa, -0.09MPa, or 0.1MPa.

[0048] After obtaining dimethyl ketene, the present invention uses an absorbent to absorb the dimethyl ketene to obtain a saturated solution of dimethyl ketene.

[0049] In this invention, the absorbent preferably includes one or more of isobutyl isobutyrate, ethyl acetate, chloroform, carbon tetrachloride, cyclohexane, n-hexane, and n-heptane.

[0050] The present invention does not have a specific limitation on the amount of absorbent used; it can be adjusted according to the required amount of product.

[0051] In this invention, the preferred temperature for the dimerization reaction is 150-300°C; the preferred time for the dimerization reaction is 2-6 hours; and the preferred pressure for the dimerization reaction is 0.5-2 MPa. As an embodiment of this invention, the temperature for the dimerization reaction can be 150°C, 200°C, 250°C, or 300°C; the preferred time for the dimerization reaction can be 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours; and the preferred pressure for the dimerization reaction can be 0.5 MPa, 1 MPa, 1.5 MPa, or 2 MPa. Under the above-mentioned temperatures and times, this invention can promote a faster and more complete dimerization reaction.

[0052] The present invention preferably involves evaporating the product obtained from the dimerization reaction to remove the absorbent, thereby obtaining 2,2,4,4-tetramethyl-1,3,-cyclobutanedione.

[0053] This invention uses biomass powder as raw material, preparing bio-based resin through sequential cooking and polymerization reactions. The bio-based resin is then carbonized to obtain bio-based resin carbon, which possesses abundant porosity, a layered structure, and a high specific surface area, improving catalytic reaction efficiency and promoting the cracking of isobutyric anhydride and the generation of DMK. This significantly increases the conversion rate of isobutyric anhydride and the yield of DMK. After the obtained dimethyl ketone is absorbed by an absorbent to obtain a saturated solution, a dimerization reaction yields high-purity 2,2,4,4-tetramethyl-1,3,-cyclobutanedione.

[0054] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0055] Example 1 A method for preparing bio-based resin carbon, comprising the following steps: (1) 20g of straw was dried and crushed to obtain biomass powder with a particle size of 60 mesh. The biomass powder was mixed with 300mL of sodium hydroxide solution with a concentration of 1mol / L and then subjected to cooking treatment. The cooking treatment temperature was 110℃, the cooking treatment pressure was 1MPa, and the cooking treatment time was 3h. Then the residue was filtered and discarded, and the filtrate was obtained as a colloidal solution. (2) Mix 100g of the colloidal solution obtained in step (1) with 3g of initiator 2,2-azobisisobutyronitrile and pour the mixture into a spherical mold (15×30cm, diameter 0.4cm). Freeze at -20℃ for 12h to obtain bio-based resin. (3) The bio-based resin obtained in step (2) is carbonized at 900°C for 2 hours in a nitrogen atmosphere to obtain 15g of straw bio-based resin carbon, i.e., bio-based resin carbon.

[0056] Example 2 A method for preparing 2,2,4,4-tetramethyl-1,3,-cyclobutanedione: (1) 5g of the bio-based resin carbon prepared in Example 1 was added to the pyrolysis reactor, and then isobutyric anhydride was introduced. The feed rate of isobutyric anhydride was 2mL / min. The pressure in the pyrolysis reactor was controlled at -0.08MPa. The pyrolysis reaction was carried out at 450℃ for 2h. The conversion rate of isobutyric anhydride was 76%, the selectivity of DMK was 85%, and the yield of DMK was 65% as determined by online chromatography.

[0057] (2) DMK obtained in step (1) was absorbed by isobutyl isobutyrate to obtain a DMK saturated solution. The DMK saturated solution was transferred into an autoclave and subjected to a dimerization reaction at 2 MPa and 150 °C for 5 h to obtain an isobutyl isobutyrate sample rich in TMCB. After evaporation to remove isobutyl isobutyrate, the TMCB yield was detected by gas chromatography and found to be 55%.

[0058] Example 3 A method for preparing bio-based resin carbon differs from Example 1 in that the biomass in step (1) is corn cob. The remaining steps are the same as in Example 1, resulting in corn cob bio-based resin carbon, i.e., bio-based resin carbon.

[0059] Example 4 A method for preparing 2,2,4,4-tetramethyl-1,3,-cyclobutanedione: (1) 5g of the bio-based resin carbon prepared in Example 3 was added to the pyrolysis reactor, and then isobutyric anhydride was introduced. The feed rate of isobutyric anhydride was 2mL / min. The pressure in the pyrolysis reactor was controlled at -0.08MPa. The pyrolysis reaction was carried out at a temperature of 450℃. The conversion rate of isobutyric anhydride was 57%, the selectivity of DMK was 70%, and the yield of DMK was 42% as determined by online chromatography.

[0060] (2) DMK obtained in step (1) was absorbed by isobutyl isobutyrate to obtain a DMK saturated solution. The DMK saturated solution was transferred into an autoclave and subjected to a dimerization reaction at 2 MPa and 150 °C for 5 h to obtain an isobutyl isobutyrate sample rich in TMCB. After evaporation to remove isobutyl isobutyrate, the TMCB yield was detected by gas chromatography and found to be 37%.

[0061] Example 5 A method for preparing bio-based resin carbon differs from Example 1 in that the biomass in step (1) is wheat straw. The remaining steps are the same as in Example 1, resulting in wheat straw bio-based resin carbon, i.e., bio-based resin carbon.

[0062] Example 6 A method for preparing 2,2,4,4-tetramethyl-1,3,-cyclobutanedione: (1) 5g of the bio-based resin carbon prepared in Example 5 was added to the pyrolysis reactor, and then isobutyric anhydride was introduced. The feed rate of isobutyric anhydride was 2mL / min. The pressure in the pyrolysis reactor was controlled at -0.08MPa. The pyrolysis reaction was carried out at 450℃ for 2h. The conversion rate of isobutyric anhydride was 55%, the selectivity of DMK was 67%, and the yield of DMK was 43% as determined by online chromatography.

[0063] (2) DMK obtained in step (1) was absorbed by isobutyl isobutyrate to obtain a saturated DMK solution. The saturated DMK solution was transferred into an autoclave and subjected to a dimerization reaction at 2 MPa and 150 °C for 5 h to obtain an isobutyl isobutyrate sample rich in TMCB. After evaporation to remove isobutyl isobutyrate, the TMCB yield was detected by gas chromatography and found to be 39%.

[0064] Comparative Example 1 A method for preparing biochar: Biochar (boron-doped sludge biochar) is carbonized at 900°C for 2 hours in a nitrogen atmosphere to obtain biochar.

[0065] Comparative Example 2 A method for preparing 2,2,4,4-tetramethyl-1,3,-cyclobutanedione: (1) 5g of biochar prepared in Comparative Example 1 was added to the pyrolysis reactor, and then isobutyric anhydride was introduced. The feed rate of isobutyric anhydride was 2mL / min. The pressure in the pyrolysis reactor was controlled at -0.08MPa. The pyrolysis reaction was carried out at a temperature of 450℃. The conversion rate of isobutyric anhydride was 47%, the selectivity of DMK was 59%, and the yield of DMK was 31% as determined by online chromatography.

[0066] (2) DMK obtained in step (1) was absorbed by isobutyl isobutyrate to obtain a saturated DMK solution. The saturated DMK solution was transferred into an autoclave and subjected to a dimerization reaction at 2 MPa and 150 °C for 5 h to obtain an isobutyl isobutyrate sample of TMCB. After evaporation to remove isobutyl isobutyrate, the TMCB yield was detected by gas chromatography.

[0067] As can be seen from the comparative examples, the yield of TMCB in Comparative Example 2 is significantly reduced. This is because when the biochar prepared in Example 1 is used as a catalyst in Comparative Example 2, there are many side reactions during the pyrolysis in step (1), and a large amount of acidic impurities and oligomers are absorbed along with DMK. These impurities in the DMK saturated solution can trigger competitive side reactions. Under high temperature and pressure, these impurities can cause random polymerization and coking of DMK, which seriously consumes the raw materials and leads to a significant reduction in the yield of TMCB formed by dimerization.

[0068] Comparative Example 3 A method for preparing 2,2,4,4-tetramethyl-1,3,-cyclobutanedione: (1) Isobutyric anhydride was introduced into the pyrolysis reactor at a feed rate of 2 mL / min. The pressure inside the pyrolysis reactor was controlled at -0.08 MPa. The pyrolysis reaction was carried out at a temperature of 450 °C. The conversion rate of isobutyric anhydride was 45%, the selectivity of DMK was 55%, and the yield of DMK was 25% as determined by online chromatography.

[0069] (2) DMK obtained in step (1) was absorbed by isobutyl isobutyrate to obtain a saturated DMK solution. The saturated DMK solution was transferred into an autoclave and subjected to a dimerization reaction at 2 MPa and 150 °C for 5 h to obtain an isobutyl isobutyrate sample of TMCB. After evaporation to remove isobutyl isobutyrate, the TMCB yield was detected by gas chromatography and found to be 15%.

[0070] The results above demonstrate that the bio-based resin carbon prepared in this invention significantly enhances the catalytic effect of isobutyric anhydride cracking, improving both the efficiency of the cracking reaction and the yield of DMK. This is because the present invention first prepares a bio-based resin, then carbonizes it to produce bio-based resin carbon, which possesses abundant porosity, a layered structure, and a high specific surface area, thus enhancing the adsorption capacity of reactants. Simultaneously, the bio-based resin carbon exhibits high mechanical strength and structural stability, making it resistant to breakage or powdering under high-pressure conditions during thermal cracking reactions. Its high structural stability allows it to maintain its catalytic activity over a long period. Furthermore, the bio-based resin carbon prepared in this invention is predominantly composed of a carbon skeleton, with abundant defects, heteroatom functional groups, and hierarchical pores forming an active system that improves catalytic reaction efficiency and promotes isobutyric anhydride cracking and DMK generation. Therefore, when used as a catalyst for the cracking of isobutyric anhydride to DMK, the bio-based resin carbon prepared in this invention enhances the catalytic effect and offers advantages such as good stability and low cost.

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing bio-based resin carbon, characterized in that, Includes the following steps: (1) After mixing biomass powder with alkaline solution, the mixture is cooked and then separated into solid and liquid components to obtain a colloidal solution; (2) The colloidal solution obtained in step (1) is mixed with an initiator and subjected to a polymerization reaction to obtain a bio-based resin; (3) The bio-based resin obtained in step (2) is carbonized in an inert atmosphere to obtain bio-based resin carbon.

2. The method for preparing bio-based resin carbon according to claim 1, characterized in that, The biomass powder in step (1) includes one or more of straw powder, branch powder and corn cob powder.

3. The method for preparing bio-based resin carbon according to claim 1 or 2, characterized in that, The particle size of the biomass powder in step (1) is 40-70 mesh.

4. The method for preparing bio-based resin carbon according to claim 1, characterized in that, The alkaline solution in step (1) is a sodium hydroxide solution with a concentration of 0.1~1 mol / L.

5. The method for preparing bio-based resin carbon according to claim 1, characterized in that, In step (1), the cooking temperature is 90~120℃, the cooking pressure is 0.1~1MPa, and the cooking time is 2~5h.

6. The method for preparing bio-based resin carbon according to claim 1, characterized in that, The initiator in step (2) includes 2,2-azobisisobutyronitrile or diacetyl peroxide.

7. The method for preparing bio-based resin carbon according to claim 1, characterized in that, The polymerization temperature in step (2) is -20 to -10°C, and the polymerization time is 12 to 24 hours.

8. The method for preparing bio-based resin carbon according to claim 1, characterized in that, The carbonization temperature in step (3) is 500~900℃ and the carbonization time is 1~6h.

9. Bio-based resin carbon prepared by the preparation method according to any one of claims 1 to 8.

10. A method for preparing 2,2,4,4-tetramethyl-1,3,-cyclobutanedione, comprising: Isobutyric anhydride is mixed with a catalyst and subjected to a thermal pyrolysis reaction to obtain dimethyl ketene; the catalyst is the bio-based resin carbon described in claim 9; The dimethyl ketene is absorbed by an absorbent to obtain a saturated solution of dimethyl ketene. The saturated solution of dimethyl ketene is then subjected to a dimerization reaction to obtain 2,2,4,4-tetramethyl-1,3,-cyclobutanedione.

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