Preparation method of non-grain bio-based pentamethylene diamine

Abstract

The invention discloses a preparation method of non-grain bio-based pentamethylene diamine, and relates to the technical field of bio-based chemical preparation. The preparation method of the non-grain bio-based pentamethylene diamine comprises the following steps: adding furfural and a first catalyst into a first solvent, introducing hydrogen, carrying out a furfural hydrogenation reaction, and recovering the first catalyst to obtain a reaction liquid of cyclopentanone; adding ammonia water and a second catalyst into the reaction liquid of cyclopentanone, introducing oxygen, carrying out ammoxidation reaction on cyclopentanone, and recovering the second catalyst to obtain a reaction liquid of glutaronitrile; and adding the reaction liquid of the glutaraldehyde and a third catalyst into a second solvent, adding alkali liquor to adjust the pH value to 8-12, introducing hydrogen, carrying out a glutaraldehyde hydrogenation reaction, recovering the third catalyst, and carrying out rectification and purification to obtain the pentamethylene diamine. The preparation method disclosed by the invention does not depend on grain raw materials, the process is green and environment-friendly, the catalyst is stable in circulation, and industrial large-scale production and high-purity application scenarios can be met.

Description

Technical Field

[0001] This invention relates to the field of bio-based chemical preparation technology, specifically to a method for preparing non-grain bio-based pentanediamine. Background Technology

[0002] Global annual consumption of polyamides is approximately 30 million tons, with demand increasing year by year. PA66 and PA6 account for 90% of this consumption. Currently, adipic acid, a raw material for PA66, can be synthesized via biotechnology, but hexamethylenediamine still relies on the petrochemical route. Pentylenediamine, as a homologue of hexamethylenediamine, can replace hexamethylenediamine in the polymerization of adipic acid to form PA56, which has similar properties to PA66, possessing high melting point, good mechanical strength, solvent resistance, fiber dyeability, and excellent abrasion resistance. Furthermore, PA510, formed by polymerization with sebacic acid, also has advantages such as high melting point and low water absorption. Therefore, pentylenediamine is an excellent monomer for synthesizing bio-based polyamides.

[0003] Existing bio-based pentanediamine production technologies mostly focus on microbial fermentation. However, the fermentation process for pentanediamine production from lysine produces complex byproducts, and the toxicity of the products inhibits cell activity. Furthermore, pentanediamine itself is highly corrosive, and the fermentation broth contains many impurities, resulting in low yields, difficult separation, easily damaged equipment, and high costs. Moreover, against the backdrop of increasingly tense food security, this process, which "competees with people for food and with food for land," not only drives up raw material prices but also faces the risk of policy tightening. This tarnishes the "green" label of bio-based pentanediamine with the shadow of "food consumption," becoming a fundamental contradiction restricting its sustainable expansion.

[0004] Furfural, derived from non-grain biomass, has the potential to replace petroleum feedstocks due to its wide availability and low cost. Therefore, using non-grain bio-based furfural as a raw material to prepare pentanediamine avoids the "competition with humans for food" red line and transforms waste into nylon raw materials through high-value utilization, achieving a triple benefit of "zero grain consumption, negative carbon emissions, and low cost." However, current research on the preparation of pentanediamine from furfural is very limited. Patent CN116789555B discloses a method for the continuous preparation of 5-amino-1-pentanol, 1-amino-2-pentanol, and 1,5-pentanediamine from furfural. Existing technologies produce numerous byproducts, have low pentanediamine yields, and the use of large amounts of ammonia increases raw material costs. Furthermore, the recovery and treatment of excess ammonia in the subsequent reaction solution requires additional processes, potentially generating ammonia-containing wastewater and increasing environmental treatment pressure and operation and maintenance costs. Therefore, developing a non-grain bio-based pentanediamine preparation method using furfural as a starting material, with a highly efficient and stable catalyst and mild reaction conditions is of great significance for promoting the development of the bio-based polyamide industry. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing non-grain bio-based pentanediamine, thereby solving the following technical problems: Existing methods for preparing non-grain bio-based pentanediamine suffer from low yield, environmental unfriendliness, and high cost.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for preparing non-grain bio-based pentanediamine includes the following steps: Furfural and the first catalyst are added to the first solvent, hydrogen gas is introduced to carry out the furfural hydrogenation reaction, the first catalyst is recovered, and the reaction solution of cyclopentanone is obtained. Ammonia and the second catalyst are added to the reaction solution of cyclopentanone, oxygen is introduced to carry out the ammoxidation reaction of cyclopentanone, the second catalyst is recovered, and the reaction solution of glutaronitrile is obtained. The reaction solution of the glutaronitrile and the third catalyst were added to the second solvent, and the pH value was adjusted to 8-12 by adding alkali. Hydrogen gas was introduced to carry out the hydrogenation reaction of glutaronitrile. The third catalyst was recovered, and after distillation and purification, non-grain bio-based pentanediamine was obtained.

[0007] As a further aspect of the present invention: the furfural is obtained by hydrolysis of agricultural waste using dilute sulfuric acid followed by distillation purification. The agricultural waste is one or more of corn cobs, sugarcane bagasse, and cottonseed hulls. The concentration of the dilute sulfuric acid is 0.5-5 wt%. The hydrolysis time is 0.5-2 h, the reaction temperature is 120-160 °C, the purity of the furfural is ≥98 wt%, and the mass ratio of the first solvent to the furfural is 5:1-10:1. The first solvent is one or more of water, isopropanol, or dimethyl sulfoxide mixed together.

[0008] As a further aspect of the present invention: the first catalyst is a bimetallic catalyst or a supported catalyst, wherein the active metal in the bimetallic catalyst is at least two of Pd, Cu, Ni, Fe or Co, and the active metal in the supported catalyst is at least one of Pd, Cu, Ni, Fe, Co, Ru or Pt, and the support is at least one of Al2O3, MOF material, molecular sieve, TiO2 or activated carbon.

[0009] As a further embodiment of the present invention: the hydrogen pressure of the furfural hydrogenation reaction is 2-8 MPa, the reaction temperature is 110-180℃, the stirring speed is 300-800 r / min, and the reaction time is 2-10 h.

[0010] As a further aspect of the present invention: the second catalyst is a composite catalyst of cuprous bromide and phenanthroline, wherein the molar ratio of cuprous bromide to phenanthroline is 1:0.5-1:5, the amount of the second catalyst added is 5-10% of the mass of cyclopentanone, the phenanthroline is 1,10-phenanthroline or 4,7-dimethyl-1,10-phenanthroline, the molar ratio of ammonia molecules to cyclopentanone in the ammonia water is 5:1-10:1, and the concentration of the ammonia water is 20-25 wt%.

[0011] As a further aspect of the present invention: the oxygen pressure in the cyclopentanone ammoxidation reaction is 4-6 atm, the reaction temperature is 80-120℃, the stirring speed is 300-600 r / min, and the reaction time is 4-8 h.

[0012] As a further aspect of the present invention: the second solvent is one or a mixture of water, isopropanol or dimethyl sulfoxide, and the alkaline solution is ammonia water with a concentration of 20-25wt%.

[0013] As a further aspect of the present invention: the third catalyst is one of a Raney type catalyst, a supported noble metal catalyst, or a metal oxide composite catalyst. The Raney type catalyst is Raney nickel or Raney cobalt, and is activated with 5wt% NaOH solution for 1-2 hours before use. The supported noble metal catalyst has at least one noble metal selected from Au, Pd, Pt, or Rh, and the support is at least one selected from activated carbon, SiO2, or Al2O3, with the noble metal loading being 0.5-5wt%. The metal oxide composite catalyst is a Cu-Zn-Al oxide composite catalyst or a Ni-Fe oxide composite catalyst.

[0014] As a further aspect of the present invention: the hydrogen pressure in the hydrogenation reaction of glutaronitrile is 2-10 MPa, the reaction temperature is 80-150℃, the stirring speed is 400-600 r / min, and the reaction time is 4-10 h.

[0015] The beneficial effects of this invention are: This invention provides a method for preparing non-grain bio-based pentanediamine, using furfural derived from the hydrolysis of agricultural waste (corn cob, sugarcane bagasse, cottonseed hulls) as raw material. This method is completely independent of grain resources, with widely available and inexpensive raw materials, while simultaneously achieving high-value utilization of agricultural waste. Through a three-step continuous reaction involving furfural hydrogenation, cyclopentanone ammoxidation, and glutaronitrile hydrogenation, combined with catalyst system optimization and precise control of reaction parameters, the method solves the problems of excessive byproducts in furfural hydrogenation, the need for strong oxidants in cyclopentanone ammoxidation, and the difficulty in controlling side reactions in glutaronitrile hydrogenation. The method for preparing non-grain bio-based pentanediamine provided by this invention features widely available raw materials, a green and efficient process, and significantly reduced costs, achieving efficient, green, and large-scale preparation of non-grain bio-based pentanediamine.

[0016] The three-step reaction provided by this invention employs a highly selective dedicated catalyst to achieve efficient synergy in the reaction process and effective suppression of byproducts. In the first step, furfural hydrogenation to cyclopentanone, furfural and a first catalyst are added to a first solvent, and hydrogen gas is introduced to carry out the furfural hydrogenation reaction. The first solvent is a mixed solvent system of water and dimethyl sulfoxide, which simultaneously improves the solubility of furfural and inhibits excessive hydrogenation of the furan ring, reducing byproducts such as tetrahydrofurfuryl alcohol. The first catalyst is selected as a bimetallic catalyst or a supported catalyst, which significantly improves the selectivity of cyclopentanone through the acid-base synergy of the metal and the support or the pore confinement effect. In the second step, the ammoxidation of cyclopentanone to glutaronitrile, ammonia and a second catalyst are added to the reaction solution of cyclopentanone, and oxygen is introduced to carry out the ammoxidation reaction of cyclopentanone. The second catalyst is a composite catalyst of cuprous bromide and phenanthroline. Phenanthroline can form a stable coordination structure with cuprous bromide, avoiding copper ion oxidation and deactivation, and improving catalytic activity and cycle stability. In addition, excess ammonia is added to ensure that cyclopentanone is fully aminated, reducing the formation of cyclopentanone oxime byproducts. Oxygen is used as the oxidant to replace traditional strong oxidants (such as potassium permanganate, chromate, etc.) to avoid the generation of saline wastewater. In the third step, the hydrogenation of glutaronitrile to produce pentanediamine, the reaction solution of glutaronitrile and the third catalyst are added to the second solvent. Alkali solution is added to adjust the pH to 8-12, and hydrogen gas is introduced to carry out the hydrogenation reaction of glutaronitrile. The third catalyst is one of a Raney catalyst, a supported catalyst, or a metal oxide composite catalyst, which can be flexibly selected and recycled according to requirements. The alkali solution is used to maintain the pH of the reaction system at 8-12, effectively inhibiting the further reaction of amino and cyano groups to generate secondary and tertiary amine byproducts, protecting the active sites of the third catalyst from being damaged by acidic substances. Simultaneously, the alkali solution is recycled from the excess ammonia water in the second step, eliminating additional discharge of ammonia-containing wastewater and reducing environmental treatment costs. In this invention, each of the three steps is adapted to a high-selectivity dedicated catalyst, ensuring high conversion rates and selectivity in each step. All catalysts can be recovered and reused through filtration, and the three reaction materials are continuously connected, eliminating the need for multiple distillation purifications of intermediate products, reducing production costs. The entire process uses environmentally friendly solvents such as water and dimethyl sulfoxide, with no use or discharge of toxic or harmful solvents, ensuring safety and environmental protection.

[0017] This invention provides a method for preparing non-grain bio-based pentanediamine with a final pentanediamine yield ≥72% and a product purity ≥98% after purification. This method can meet the polymerization requirements of different types of bio-based polyamides such as PA56 and PA510, and is suitable for applications in fibers, engineering plastics, films, and other fields. It provides the bio-based polyamide industry with a zero-grain-consumption, highly selective, and low-cost method for preparing non-grain bio-based pentanediamine. The reaction conditions are mild, and the high-pressure reactor, filtration equipment, and distillation apparatus used are all mature equipment in the chemical industry, requiring no specialized customized equipment. Raw materials can be collected and processed locally, reducing transportation and storage costs. This method is suitable for large-scale and decentralized plant construction and is highly replicable. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1: The preparation method of non-grain bio-based pentanediamine includes the following steps: 100g furfural, 600g water / dimethyl sulfoxide mixed solvent (volume ratio 8:2), and 15g of the first catalyst, Pd-Cu / Al2O3 bimetallic catalyst (Pd loading 2wt%, Cu loading 10wt%), were added to a 2L high-pressure reactor. The reactor was purged with hydrogen three times, maintaining a hydrogen pressure of 5MPa. The temperature was raised to 150℃, the stirring speed was 500r / min, and the reaction was carried out for 4 hours. The first catalyst was recovered by filtration, yielding a reaction solution for obtaining cyclopentanone. The furfural conversion rate was 99.2%, and the cyclopentanone selectivity was 88.5%. The above-mentioned cyclopentanone reaction solution (containing approximately 87g of cyclopentanone), 200g of 22wt% ammonia water, and 5g of the second catalyst, CuBr-1,10-phenanthroline composite catalyst (molar ratio 1:2), were added to a 2L reactor. Oxygen was introduced to purge the catalyst three times, maintaining an oxygen pressure of 5 atm. The temperature was raised to 100℃, and the stirring speed was 400 r / min. The reaction was carried out for 6 hours. The second catalyst was recovered by filtration, yielding a glutaronitrile reaction solution. The cyclopentanone conversion rate was 95.6%, and the glutaronitrile selectivity was 95.2%. The above-mentioned glutaronitrile reaction solution (containing approximately 75g of glutaronitrile), 750g of water, and 12g of the third catalyst, Raney nickel (activated with 5wt% NaOH for 1.5h), were added to a 2L high-pressure reactor. Excess ammonia was added as an alkaline solution to adjust the pH to 10. Hydrogen gas was purged three times to maintain a hydrogen pressure of 6MPa. The temperature was raised to 120℃, the stirring speed was 500r / min, and the reaction was carried out for 8h. The third catalyst was recovered by filtration. After multi-step distillation purification, non-grain bio-based pentanediamine was obtained, with a pentanediamine yield of 72.8% and a purity of 98.5%.

[0020] Example 2: The preparation method of non-grain bio-based pentanediamine includes the following steps: 100g furfural, 800g dimethyl sulfoxide, and 18g of the first catalyst, Cu-Ni / Al2O3 bimetallic catalyst (Cu loading 15wt%, Ni loading 5wt%), were added to a 2L high-pressure reactor. The reactor was purged with hydrogen three times to maintain a hydrogen pressure of 4MPa. The temperature was raised to 160℃, the stirring speed was 600r / min, and the reaction was carried out for 3 hours. The first catalyst was recovered by filtration to obtain the reaction solution for cyclopentanone. The conversion rate of furfural was 99.5%, and the selectivity of cyclopentanone was 90.3%. The above-mentioned cyclopentanone reaction solution (containing approximately 89g of cyclopentanone), 200g of 25wt% ammonia water, and 6g of the second catalyst, CuBr-4,7-dimethyl-1,10-phenanthroline composite catalyst (molar ratio 1:3), were added to a 2L reactor. Oxygen was introduced to purge the catalyst three times, maintaining an oxygen pressure of 5 atm. The temperature was raised to 100℃, and the stirring speed was 500 r / min. The reaction was carried out for 5 hours. The second catalyst was recovered by filtration, yielding a glutaronitrile reaction solution. The cyclopentanone conversion rate was 96.1%, and the glutaronitrile selectivity was 95.8%. The above-mentioned glutaronitrile reaction solution (containing approximately 77g of glutaronitrile), 770g of water, and 12g of the third catalyst, Pd / activated carbon catalyst (Pd loading 3wt%), were added to a 2L high-pressure reactor. Excess ammonia was added as an alkaline solution to adjust the pH to 11. Hydrogen gas was purged three times to maintain a hydrogen pressure of 4MPa. The temperature was raised to 100℃, the stirring speed was 450r / min, and the reaction was carried out for 6 hours. The third catalyst was recovered by filtration. After multi-step distillation purification, non-grain bio-based pentanediamine was obtained, with a glutaronitrile conversion rate of 98.8% and a pentanediamine selectivity of 96.2%.

[0021] Example 3: The preparation method of non-grain bio-based pentanediamine includes the following steps: 100g furfural, 500g isopropanol, and 16g of the first catalyst, Ni-Fe / SAPO-11 supported catalyst (Ni loading 10wt%, Fe loading 4wt%), were added to a 2L high-pressure reactor. The reactor was purged with hydrogen three times, maintaining a hydrogen pressure of 5MPa. The temperature was raised to 170℃, the stirring speed was 700r / min, and the reaction was carried out for 2.5h. The first catalyst was recovered by filtration, yielding a reaction solution for obtaining cyclopentanone. The furfural conversion rate was 99.1%, and the cyclopentanone selectivity was 80.7%. The above-mentioned cyclopentanone reaction solution (containing approximately 85g of cyclopentanone), 180g of 20wt% ammonia water, and 4.5g of the second catalyst, CuBr-1,10-phenanthroline composite catalyst (molar ratio 1:1), were added to a 2L reactor. Oxygen was introduced to purge the catalyst three times, maintaining an oxygen pressure of 5 atm. The temperature was raised to 80℃, and the stirring speed was 350 r / min. The reaction was carried out for 8 hours. The second catalyst was recovered by filtration, yielding a glutaronitrile reaction solution. The cyclopentanone conversion rate was 95.2%, and the glutaronitrile selectivity was 95.1%. The above-mentioned glutaronitrile reaction solution (containing approximately 73g of glutaronitrile), 770g of water, and 15g of the third catalyst, Cu-Zn-Al oxide catalyst (Cu:Zn:Al molar ratio 1:1:1), were added to a 2L high-pressure reactor. Excess ammonia was added as an alkaline solution to adjust the pH to 11. Hydrogen gas was purged three times to maintain a hydrogen pressure of 7MPa. The temperature was raised to 130℃, the stirring speed was 550r / min, and the reaction was carried out for 9 hours. The third catalyst was recovered by filtration. After purification by multi-step distillation, non-grain bio-based pentanediamine was obtained, with a glutaronitrile conversion rate of 98.1% and a pentanediamine selectivity of 95.0%.

[0022] Example 4: The preparation method of non-grain bio-based pentanediamine includes the following steps: 100g furfural, 700g water, and 14g of Cu / TiO2 supported catalyst (Cu loading 12wt%) were added to a 2L high-pressure reactor. The reactor was purged with hydrogen three times, maintaining a hydrogen pressure of 4MPa. The temperature was raised to 140℃, and the stirring speed was 600r / min. The reaction was carried out for 8 hours. The first catalyst was recovered by filtration, and the reaction solution for obtaining cyclopentanone was obtained. The conversion rate of furfural was 99.3%, and the selectivity of cyclopentanone was 84.2%. The above-mentioned cyclopentanone reaction solution (containing approximately 84g of cyclopentanone), 190g of 23wt% ammonia water, and 7g of the second catalyst, CuBr-4,7-dimethyl-1,10-phenanthroline composite catalyst (molar ratio 1:5), were added to a 2L reactor. Oxygen was introduced to purge the catalyst three times, maintaining an oxygen pressure of 5 atm. The temperature was raised to 90℃, and the stirring speed was 450 r / min. The reaction was carried out for 7 hours. The second catalyst was recovered by filtration, yielding a glutaronitrile reaction solution. The cyclopentanone conversion rate was 95.4%, and the glutaronitrile selectivity was 95.5%. The above-mentioned glutaronitrile reaction solution (containing approximately 72g of glutaronitrile), 720g of water, and 11g of the third catalyst, Raney nickel (activated with 5wt% NaOH for 1h), were added to a 2L high-pressure reactor. Excess ammonia was added as an alkaline solution to adjust the pH to 10.5. Hydrogen gas was purged three times to maintain a hydrogen pressure of 8MPa. The temperature was raised to 130℃, the stirring speed was 500r / min, and the reaction was carried out for 10h. The third catalyst was recovered by filtration. After purification by multi-step distillation, non-grain bio-based pentanediamine was obtained, with a glutaronitrile conversion rate of 98.5%, a pentanediamine selectivity of 95.3%, and a yield of 72.2%.

[0023] Example 5: The preparation method of non-grain bio-based pentanediamine includes the following steps: 100g of furfural, 550g of isopropanol-dimethyl sulfoxide mixed solvent (volume ratio 7:3), and 17g of the first catalyst, a Co-Pd / activated carbon bimetallic catalyst (Co loading 6wt%, Pd loading 3wt%), were added to a 2L high-pressure reactor. The reactor was purged with hydrogen three times to maintain a hydrogen pressure of 4MPa, heated to 160℃, stirred at 550r / min, and reacted for 10h. The first catalyst was then recovered by filtration to obtain a reaction solution for cyclopentanone. The furfural conversion rate was 99.4%, and the cyclopentanone selectivity was 89.7%. The above-mentioned cyclopentanone reaction solution (containing approximately 88g of cyclopentanone), 210g of 24wt% ammonia water, and 5.5g of the second catalyst, CuBr-1,10-phenanthroline composite catalyst (molar ratio 1:3), were added to a 2L reactor. Oxygen was introduced to purge the catalyst three times, maintaining an oxygen pressure of 5 atm. The temperature was raised to 105℃, and the stirring speed was 400 r / min. The reaction was carried out for 5.5 h. The second catalyst was recovered by filtration, yielding a glutaronitrile reaction solution. The cyclopentanone conversion rate was 95.8%, and the glutaronitrile selectivity was 95.7%. The above-mentioned glutaronitrile reaction solution (containing approximately 76g of glutaronitrile), 760g of water, and 8g of the third catalyst, Rh / Al₂O₃ catalyst (Rh loading 2wt%), were added to a 2L high-pressure reactor. Excess ammonia was added as an alkaline solution to adjust the pH to 11. Hydrogen gas was purged three times to maintain a hydrogen pressure of 5MPa. The temperature was raised to 90℃, the stirring speed was 400r / min, and the reaction was carried out for 5 hours. The third catalyst was recovered by filtration. After multi-step distillation purification, non-grain bio-based pentanediamine was obtained. The conversion rate of glutaronitrile was 99.0%, the selectivity of pentanediamine was 96.5%, the yield was 73.9%, and the purity was 99.3%.

[0024] Example 6: The preparation method of non-grain bio-based pentanediamine includes the following steps: The preparation steps for the hydrogenation of furfural to cyclopentanone were the same as in Example 1, yielding a reaction solution of cyclopentanone, wherein the furfural conversion rate was 99.2% and the cyclopentanone selectivity was 88.5%. In the preparation step of cyclopentanone ammoxidation to glutaronitrile, the second catalyst was selected as CuBr-1,10-phenanthroline composite catalyst (molar ratio 1:0.5). The other steps were the same as in Example 1, and a reaction solution of glutaronitrile was obtained, wherein the conversion rate of cyclopentanone was 95.8% and the selectivity of glutaronitrile was 95.7%. In the preparation steps of pentanediamine by hydrogenation of glutaronitrile, the reaction solution of glutaronitrile was obtained in this embodiment, and the other steps were the same as in Example 1, to obtain non-grain bio-based pentanediamine, wherein the conversion rate of glutaronitrile was 98.1%, the selectivity of pentanediamine was 95.2%, and the yield was 72.3%.

[0025] Example 7: The preparation method of non-grain bio-based pentanediamine includes the following steps: The preparation steps for the hydrogenation of furfural to cyclopentanone were the same as in Example 2, yielding a reaction solution of cyclopentanone, wherein the furfural conversion rate was 99.5% and the cyclopentanone selectivity was 90.3%. The above-mentioned cyclopentanone reaction solution (containing approximately 89 g of cyclopentanone), 220 g of 25 wt% ammonia water, and 8.9 g of the second catalyst, CuBr-4,7-dimethyl-1,10-phenanthroline composite catalyst (molar ratio 1:3), were added to a 2 L reactor. Oxygen was introduced to purge the catalyst three times, maintaining an oxygen pressure of 5 atm. The temperature was raised to 100 °C, and the stirring speed was 500 r / min. The reaction was carried out for 5 h. The second catalyst was recovered by filtration, yielding a glutaronitrile reaction solution. The cyclopentanone conversion rate was 96.3%, and the glutaronitrile selectivity was 96.1%. In the preparation steps of pentanediamine by hydrogenation of glutaronitrile, the reaction solution of glutaronitrile was obtained in this embodiment, and the other steps were the same as in Example 1, to obtain non-grain bio-based pentanediamine, wherein the selectivity of pentanediamine was 96.8% and the yield was 74.2%.

[0026] Example 8: The preparation method of non-grain bio-based pentanediamine includes the following steps: The preparation steps for the hydrogenation of furfural to cyclopentanone were the same as in Example 3, yielding a reaction solution of cyclopentanone, wherein the furfural conversion rate was 99.1% and the cyclopentanone selectivity was 80.7%. The preparation steps for the ammoxidation of cyclopentanone to glutaronitrile are the same as in Example 3, yielding a reaction solution of glutaronitrile, wherein the conversion rate of cyclopentanone is 95.2% and the selectivity of glutaronitrile is 95.1%. The above-mentioned glutaronitrile reaction solution (containing approximately 73g of glutaronitrile), 730g of water, and 15g of the third catalyst, Cu-Zn-Al oxide catalyst (Cu:Zn:Al molar ratio 1:1:1), were added to a 2L high-pressure reactor. Excess ammonia was added as an alkaline solution to adjust the pH to 9. Hydrogen gas was purged three times to maintain a hydrogen pressure of 5MPa. The temperature was raised to 120℃, and the stirring speed was 550r / min. The reaction was carried out for 8 hours. The third catalyst was recovered by filtration. After purification by multi-step distillation, non-grain bio-based pentanediamine was obtained. The conversion rate of glutaronitrile was 98.9%, the selectivity of pentanediamine was 95.6%, the yield was 73.3%, and the purity was 98.6%.

[0027] Example 9: The preparation method of non-grain bio-based pentanediamine includes the following steps: The preparation steps for the hydrogenation of furfural to cyclopentanone were the same as in Example 4, yielding a reaction solution of cyclopentanone, wherein the furfural conversion rate was 99.3% and the cyclopentanone selectivity was 82.4%. The above-mentioned cyclopentanone reaction solution (containing approximately 84g of cyclopentanone), 130g of 23wt% ammonia water, and 7g of the second catalyst, CuBr-4,7-dimethyl-1,10-phenanthroline composite catalyst (molar ratio 1:5), were added to a 2L reactor. Oxygen was introduced three times to replace the catalyst, maintaining an oxygen pressure of 5 atm. The temperature was raised to 90℃, and the stirring speed was 450 r / min. The reaction was carried out for 7 hours. The second catalyst was recovered by filtration, yielding a glutaronitrile reaction solution. The cyclopentanone conversion rate was 95.1%, and the glutaronitrile selectivity was 95.3%. In the preparation steps of glutaronitrile hydrogenation to pentanediamine, the reaction solution of glutaronitrile was obtained in this embodiment, and the other steps were the same as in Example 4, to obtain non-grain bio-based pentanediamine, wherein the conversion rate of glutaronitrile was 98.2%, the purity was 98.1%, and the yield was 72.0%.

[0028] Example 10: The preparation method of non-grain bio-based pentanediamine includes the following steps: The preparation steps for the hydrogenation of furfural to cyclopentanone were the same as in Example 5, yielding a reaction solution of cyclopentanone, wherein the furfural conversion rate was 99.4% and the cyclopentanone selectivity was 89.7%. The preparation steps for the ammoxidation of cyclopentanone to glutaronitrile are the same as in Example 5, yielding a reaction solution of glutaronitrile, wherein the conversion rate of cyclopentanone is 95.8% and the selectivity of glutaronitrile is 95.7%. The above-mentioned glutaronitrile reaction solution (containing approximately 76g of glutaronitrile), 760g of water, and 10g of the third catalyst, Au / C catalyst (Au loading 0.5wt%), were added to a 2L high-pressure reactor. Excess ammonia water was added as an alkaline solution to adjust the pH to 11. Hydrogen gas was purged three times to maintain a hydrogen pressure of 3MPa. The temperature was raised to 110℃, the stirring speed was 400r / min, and the reaction was carried out for 7 hours. The third catalyst was recovered by filtration. After multi-step distillation purification, non-grain bio-based pentanediamine was obtained. The conversion rate of glutaronitrile was 98.7%, the selectivity of pentanediamine was 96.3%, the yield was 73.4%, and the purity was 99.0%.

[0029] Example 11: The preparation method of non-grain bio-based pentanediamine includes the following steps: The preparation steps for furfural hydrogenation to cyclopentanone, cyclopentanone ammoxidation to glutaronitrile, and glutaronitrile hydrogenation to pentanediamine were the same as in Example 1. The only difference was that in the glutaronitrile hydrogenation to pentanediamine preparation step, Raney nickel (5 wt% NaOH) recovered after two cycles was selected as the third catalyst. The obtained glutaronitrile conversion rate was 98.0%, the pentanediamine selectivity was 95.1%, and the pentanediamine yield was 72.1%.

[0030] Example 12: The preparation method of non-grain bio-based pentanediamine includes the following steps: The preparation steps for furfural hydrogenation to cyclopentanone, cyclopentanone ammoxidation to glutaronitrile, and glutaronitrile hydrogenation to pentanediamine were the same as in Example 1. The only difference was that in the glutaronitrile hydrogenation to pentanediamine preparation step, Raney nickel (5 wt% NaOH) recovered after 5 cycles was selected as the third catalyst. The yield of pentanediamine obtained was 71.2%, the purity was 97.8%, and the activity retention rate of the third catalyst was 97.8%.

[0031] In summary, the preparation steps of the non-grain bio-based pentanediamine provided in Examples 1-12 of this invention achieve furfural conversion ≥99%, cyclopentanone selectivity ≥82%, cyclopentanone conversion ≥95%, glutaronitrile selectivity ≥95%, glutaronitrile conversion ≥98%, and pentanediamine selectivity ≥95%, with a final pentanediamine yield ≥72% and purity ≥97.8%. The catalysts in Examples 11 and 12 exhibit excellent recycling performance, with the Raney catalyst retaining ≥97% activity after 5 cycles. The reaction conditions are mild, and the environmental performance is excellent, fully meeting the needs of industrial-scale production and effectively supporting the sustainable development of the bio-based polyamide industry.

[0032] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0033] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for preparing non-grain bio-based pentanediamine, characterized in that, Includes the following steps: Furfural and the first catalyst are added to the first solvent, hydrogen gas is introduced to carry out the furfural hydrogenation reaction, the first catalyst is recovered, and the reaction solution of cyclopentanone is obtained. Ammonia and the second catalyst are added to the reaction solution of cyclopentanone, oxygen is introduced to carry out the ammoxidation reaction of cyclopentanone, the second catalyst is recovered, and the reaction solution of glutaronitrile is obtained. The reaction solution of the glutaronitrile and the third catalyst were added to the second solvent, and the pH value was adjusted to 8-12 by adding alkali. Hydrogen gas was introduced to carry out the hydrogenation reaction of glutaronitrile. The third catalyst was recovered, and after distillation and purification, non-grain bio-based pentanediamine was obtained.

2. The method for preparing a non-grain bio-based pentanediamine according to claim 1, characterized in that, The furfural is obtained by hydrolyzing agricultural waste using dilute sulfuric acid followed by distillation purification. The agricultural waste is one or more of corn cobs, sugarcane bagasse, and cottonseed hulls. The concentration of the dilute sulfuric acid is 0.5-5 wt%. The hydrolysis time is 0.5-2 h, the reaction temperature is 120-160 °C, and the purity of the furfural is ≥98 wt%. The mass ratio of the first solvent to the furfural is 5:1-10:

1. The first solvent is one or more of water, isopropanol, or dimethyl sulfoxide mixed together.

3. The method for preparing a non-grain bio-based pentanediamine according to claim 1, characterized in that, The first catalyst is a bimetallic catalyst or a supported catalyst. The active metal in the bimetallic catalyst is at least two of Pd, Cu, Ni, Fe or Co. The active metal in the supported catalyst is at least one of Pd, Cu, Ni, Fe, Co, Ru or Pt, and the support is at least one of Al2O3, MOF material, molecular sieve, TiO2 or activated carbon.

4. The method for preparing a non-grain bio-based pentanediamine according to claim 1, characterized in that, The hydrogen pressure for the furfural hydrogenation reaction is 2-8 MPa, the reaction temperature is 110-180℃, the stirring speed is 300-800 r / min, and the reaction time is 2-10 h.

5. The method for preparing a non-grain bio-based pentanediamine according to claim 1, characterized in that, The second catalyst is a composite catalyst of cuprous bromide and phenanthroline, wherein the molar ratio of cuprous bromide to phenanthroline is 1:0.5-1:5, the amount of the second catalyst added is 5-10% of the mass of cyclopentanone, the phenanthroline is 1,10-phenanthroline or 4,7-dimethyl-1,10-phenanthroline, the molar ratio of ammonia molecules to cyclopentanone in the ammonia water is 5:1-10:1, and the concentration of the ammonia water is 20-25 wt%.

6. The method for preparing a non-grain bio-based pentanediamine according to claim 1, characterized in that, The oxygen pressure in the cyclopentanone ammoxidation reaction is 4-6 atm, the reaction temperature is 80-120℃, the stirring speed is 300-600 r / min, and the reaction time is 4-8 h.

7. The method for preparing a non-grain bio-based pentanediamine according to claim 1, characterized in that, The second solvent is one or a mixture of water, isopropanol, or dimethyl sulfoxide, and the alkaline solution is ammonia solution with a concentration of 20-25 wt%.

8. The method for preparing a non-grain bio-based pentanediamine according to claim 1, characterized in that, The third catalyst is one of a Raney type catalyst, a supported noble metal catalyst, or a metal oxide composite catalyst. The Raney type catalyst is Raney nickel or Raney cobalt, and is activated with 5wt% NaOH solution for 1-2 hours before use. The supported noble metal catalyst has at least one noble metal selected from Au, Pd, Pt, or Rh, and the support is at least one selected from activated carbon, SiO2, or Al2O3, with the noble metal loading being 0.5-5wt%. The metal oxide composite catalyst is a Cu-Zn-Al oxide composite catalyst or a Ni-Fe oxide composite catalyst.

9. The method for preparing a non-grain bio-based pentanediamine according to claim 1, characterized in that, In the hydrogenation reaction of glutaronitrile, the hydrogen pressure is 2-10 MPa, the reaction temperature is 80-150℃, the stirring speed is 400-600 r / min, and the reaction time is 4-10 h.