A method for extracting 1,5-pentanediamine, the obtained 1,5-pentanediamine product, and polyamide.

Abstract

This invention provides a method for extracting 1,5-pentanediamine, the obtained 1,5-pentanediamine product, and a polyamide. The method includes: providing a first solution containing 1,5-pentanediamine and water; extracting the 1,5-pentanediamine in the first solution with an extractant to obtain an organic solution containing the 1,5-pentanediamine and the extractant; and separating the 1,5-pentanediamine from the organic solution; wherein the molar ratio of the extractant to the 1,5-pentanediamine in the first solution is (5-300):1, and the extractant is selected from one or more of ether compounds, ester compounds, straight-chain, branched, and cyclic alcohols, straight-chain and cyclic alkanes, haloalkanes, and aromatic compounds. The method of one embodiment of this invention is simple, low-cost, and can extract high-purity pentanediamine.

Description

Technical Field

[0001] This invention relates to 1,5-pentanediamine, specifically a method for extracting 1,5-pentanediamine from an aqueous solution. Background Technology

[0002] 1,5-Pentanediamine (abbreviated as pentanediamine) is an important 5-carbon platform compound in the chemical industry. It can be used to manufacture polyamides, polyurethanes, etc., and can also be used as an important chemical raw material to manufacture isocyanates, pyridine, piperidine, etc.

[0003] Existing literature reports the potential for microbial synthesis of pentanediamine, i.e., the biological preparation of pentanediamine. However, this biological preparation requires pH adjustment during fermentation to introduce acid radicals, which are also present in the culture medium. Consequently, large amounts of pentanediamine carbonate and sulfate are formed in the fermentation broth.

[0004] In existing production processes, alkali substances such as caustic soda (NaOH), Ca(OH)₂, or Mg(OH)₂ are added to the fermentation broth for alkalization, generating free pentanediamine and its salts. The pentanediamine is then extracted by filtration and distillation. However, subsequent distillation recovery of pentanediamine requires stringent distillation conditions and sophisticated equipment if the system composition is complex, and the purification effect is limited. Therefore, extracting high-purity 1,5-pentanediamine remains a challenging problem. Summary of the Invention

[0005] A primary objective of this invention is to provide a method for extracting 1,5-pentanediamine, comprising: providing a first solution containing 1,5-pentanediamine and water; extracting the 1,5-pentanediamine in the first solution with an extractant to obtain an organic solution containing the 1,5-pentanediamine and the extractant; and separating the 1,5-pentanediamine from the organic solution; wherein the molar ratio of the extractant to the 1,5-pentanediamine in the first solution is (5-300):1, and the extractant is selected from one or more of ether compounds, ester compounds, straight-chain, branched and cyclic alcohols, straight-chain and cyclic alkanes, haloalkanes, and aromatic compounds.

[0006] An embodiment of the present invention also provides a 1,5-pentanediamine product, which is prepared by the above method, and the purity of the 1,5-pentanediamine product is above 98.5 wt%.

[0007] One embodiment of the present invention further provides a polyamide whose raw materials include the above-mentioned 1,5-pentanediamine product.

[0008] The method of one embodiment of the present invention is simple in process, low in cost, and can extract high-purity pentanediamine. Detailed Implementation

[0009] Typical embodiments embodying the features and advantages of this invention will be described in detail in the following description. It should be understood that the invention can have various variations in different embodiments without departing from the scope of the invention, and the descriptions herein are for illustrative purposes only and not intended to limit the invention. The terms "first," "second," etc., are used to distinguish between multiple processes or products with the same name and are not intended to limit them.

[0010] One embodiment of the present invention provides a method for extracting 1,5-pentanediamine, comprising: A first solution is provided, the first solution comprising 1,5-pentanediamine and water; The 1,5-pentanediamine in the first solution was extracted using an organic extractant to obtain an organic solution containing 1,5-pentanediamine and the extractant; and Separating 1,5-pentanediamine from organic solutions; The extractant is selected from one or more of the following: ether compounds, ester compounds, straight-chain, branched and cyclic alcohols containing at least four carbon atoms, straight-chain and cyclic alkanes, haloalkanes, and aromatic compounds.

[0011] In one embodiment, the straight-chain, branched, and cyclic alcohol compounds have 4 or more carbon atoms, more specifically 4 to 18, for example 5, 7, 9, 10, 12, 14, 16, or 17.

[0012] In one embodiment, the ester compound contains at least three carbon atoms, and may further contain 3 to 12 carbon atoms. For example, the ester compound may include, but is not limited to, ethyl acetate, ethyl formate, propyl acetate, butyl acetate, phenyl acetate, and combinations thereof.

[0013] In one embodiment, the extractant is an ester compound, such as ethyl acetate or butyl acetate.

[0014] In one embodiment, the ether compound contains at least 4 carbon atoms, and may further contain 4 to 12 carbon atoms. For example, the ether compound may include, but is not limited to, one, two or three of diethyl ether, isopropyl ether, and anisole.

[0015] In one embodiment, the alkane is a straight-chain or cyclic alkane compound containing at least four carbon atoms, including but not limited to n-pentane, n-hexane, cyclohexane, cyclopentane, alkanes containing eight or more carbon atoms, and combinations thereof.

[0016] In one embodiment, the number of carbon atoms in the straight-chain and cyclic alkane compounds can be 4 or more, and more specifically 5 to 12, for example 6, 7, 8, 9, 10, 11, or 12.

[0017] In one embodiment, the haloalkane has 1, 2, or 3 carbon atoms and may be a chloroalkane and / or a bromoalkane.

[0018] In one embodiment, the haloalkane can be a monohaloalkane, dihaloalkane, trihaloalkane, or tetrahaloalkane, such as including but not limited to carbon tetrachloride, chloroform, dichloromethane, tetrachloroethane, and combinations thereof.

[0019] In one embodiment, the aromatic compound may have 6 or more carbon atoms, including but not limited to benzene, p-xylene, o-xylene, m-xylene, toluene, ethylbenzene, chlorobenzene, and combinations thereof.

[0020] In one embodiment, the extraction process includes n or more stages of extraction. n is greater than or equal to 1, further greater than or equal to 2, and further greater than or equal to 3.

[0021] In one embodiment, the extraction process includes primary extraction (n=1), or primary extraction and secondary extraction (n=2), or primary extraction, secondary extraction and tertiary extraction (n=3).

[0022] In one embodiment, after each extraction process is completed, the organic phase and the aqueous phase are separated, and the aqueous phase is used as the starting material for the next extraction process.

[0023] In one embodiment, the aqueous solution to be extracted is concentrated before any first-stage extraction.

[0024] In one embodiment, during the first-stage extraction, the molar ratio of the extractant to 1,5-pentanediamine in the first solution can be (5-300):1, further can be (10-250):1, even further can be (10-150):1, even further can be (10-100):1, even further can be (10-50):1, for example 20:1, 30:1, 40:1, 60:1, 80:1, 120:1, 180:1, etc.

[0025] In one embodiment, during the first-stage extraction, the mass ratio of the extractant to the first solution (oil-water mass ratio) can be (0.2-30):1, further can be (0.5-30):1, further can be (0.5-20):1, further can be (1-15):1, further can be (1-10):1, and even further can be (1-7):1, for example, 2:1, 3:1, 4:1, 6:1, 8:1, 12:1, 15:1, 18:1, etc.

[0026] In one embodiment, the mass ratio of extractant to aqueous phase in the secondary and tertiary extractions is the same as that in the primary extraction.

[0027] In one embodiment, the extraction temperatures for the secondary and tertiary extractions are the same as those for the primary extraction.

[0028] In one embodiment, the pH of the aqueous phase after tertiary extraction is 9.0 to 11.5, more specifically 9.0 to 10.5.

[0029] In one embodiment, the difference between the pH value of the first solution and the pH value of the aqueous phase after tertiary extraction is ≥2, further ≥2.5, further ≥2.7, further ≥3, and further ≥3.4.

[0030] In one embodiment, in order to fully extract pentanediamine, the aqueous phase after the third-stage extraction can be further subjected to fourth-stage extraction, fifth-stage extraction, etc.; or the aqueous phase after the third-stage extraction can be concentrated and then subjected to fourth-stage extraction, fifth-stage extraction, etc.; or the aqueous phase after the third-stage extraction can be mixed with the first solution of the next batch and subjected to n-stage extraction.

[0031] In one embodiment, a first solution (also known as a 1,5-pentanediamine alkalization solution) is prepared by alkalizing a solution containing 1,5-pentanediamine salt and water (the second solution), i.e., by adding an alkaline substance to react the 1,5-pentanediamine salt with the alkaline substance to generate 1,5-pentanediamine.

[0032] In one embodiment, the second solution may be a fermentation broth or enzyme conversion broth containing 1,5-pentanediamine salt, or it may be an aqueous solution of 1,5-pentanediamine salt.

[0033] In one embodiment, the 1,5-pentanediamine salt includes one, two, or three of the sulfate, hydrochloride, and carbonate salts of 1,5-pentanediamine.

[0034] In one embodiment, the alkaline substance added to the second solution may be an inorganic base.

[0035] In one embodiment, the alkaline substance added to the second solution can be a strong base, such as sodium hydroxide or potassium hydroxide; it can also be a weak base, such as ammonia; or it can be a base that is not easily soluble in water, such as calcium hydroxide or magnesium hydroxide.

[0036] In one embodiment, the alkaline substance added to the second solution can be an alkaline oxide, such as calcium oxide or magnesium oxide.

[0037] In this invention, the purity of the alkaline substance is related to the source of the raw materials. As long as it does not contain impurities that affect the quality of the 1,5-pentanediamine product, it can be used in this invention.

[0038] In one embodiment, the alkaline substance may contain other substances that do not react with 1,5-pentanediamine salt, such as calcium carbonate impurities in calcium oxide. Calcium carbonate exists in industrial calcium oxide products as an impurity in the calcium oxide production process, but it does not affect the reaction in this invention.

[0039] In this invention, there are no particular restrictions on the method of adding the alkaline substance to the second solution; it can be added all at once or in batches. The alkaline substance added can be a single type or a mixture of two or more. The components of the mixture can be added separately or mixed first and then added all at once. Preferably, strong alkaline substances such as sodium hydroxide and potassium hydroxide can be added as an aqueous solution with a mass percentage concentration of 10-50%.

[0040] In one embodiment, the reaction time between the second solution and the alkaline substance is ≥1 hour, and may further be ≥1.5 hours.

[0041] In one embodiment, the concentration of 1,5-pentanediamine in the alkalizing solution can be 50 wt% or less, for example, 1 to 50 wt%, further can be 30 wt% or less, further can be 20 wt% or less, further can be 10 wt% or less, for example, 1.13%, 2%, 5%, 9 wt%, 9.05 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, etc.

[0042] In one embodiment, the extraction efficiency is affected differently when using alkalizing solutions of 1,5-pentanediamine with different concentrations; when the concentration of 1,5-pentanediamine is low, a good multi-stage extraction efficiency can still be achieved; however, when the concentration of pentanediamine is too high, for example above 45%, the extraction efficiency decreases significantly.

[0043] In one embodiment, the pH value of the 1,5-pentanediamine alkalinization solution is 7 or higher, and may further be 10 to 14, or may further be 11 to 12.5, such as 10.5, 11, 11.03, 11.5, 12, 12.5, 12.65, 13, 13.23, 13.5, etc.

[0044] In one embodiment, the 1,5-pentanediamine alkalization solution contains residual metal ions from the alkalization process, said metal ions including divalent metal ions, such as Ca. 2+ and / or Mg 2+ Regarding the ions, the present invention does not impose a specific limitation on the concentration of metal ions in the 1,5-pentanediamine alkalinization solution, which can be less than 2 wt%, and more specifically less than 1 wt%, for example 1.5%, 0.8%, 0.5%, 0.3%, or 0.1%.

[0045] In one embodiment, the extraction temperature can be 10–100°C, further 20–60°C, even further 25–45°C, and even further 30–40°C, for example 25°C, 32°C, 34°C, 35°C, 36°C, 38°C, 45°C, 50°C, 55°C, 65°C, 70°C, 80°C, 90°C, etc.

[0046] In one embodiment, the extractant in the 1,5-pentanediamine organic solution obtained by extraction is removed to obtain the 1,5-pentanediamine product.

[0047] In one embodiment, the transmittance of the organic solution is 92% or more, and the content of residual metal ions therein is 500 ppm or less, and more specifically 200 ppm or less.

[0048] In one embodiment, the method for removing the extractant includes, but is not limited to, distillation or rectification. The distillation or rectification process can be carried out in conventional distillation or rectification equipment, such as a distillation column.

[0049] In one embodiment, the pressure of distillation or rectification is not higher than -0.01 MPa; the endpoint temperature of distillation or rectification is above 150°C, further 150-200°C, and further 150-185°C.

[0050] In one embodiment, in the distillation or rectification system, the boiling point of the extractant is lower than that of 1,5-pentanediamine.

[0051] In one embodiment, the second solution may be a fermentation broth containing 1,5-pentanediamine salt produced by biological methods, or an enzyme conversion solution; it may also be an enzyme conversion solution of 1,5-pentanediamine salt obtained by reacting lysine salt under the action of lysine decarboxylase (LDC).

[0052] This invention does not particularly limit the specific preparation method of 1,5-pentanediamine by enzyme conversion solution containing 1,5-pentanediamine salt or by direct fermentation. Those skilled in the art can determine the specific raw materials and process parameters of the enzyme conversion process based on the existing technology, thereby obtaining an aqueous solution containing 1,5-pentanediamine salt.

[0053] In one embodiment, the second solution is an enzyme conversion solution, which can be obtained by reacting a lysine salt solution with lysine decarboxylase (LDC). The lysine salt can be an inorganic or organic salt of lysine, such as commercially available lysine hydrochloride or lysine sulfate.

[0054] In one embodiment, the second solution is a fermentation broth containing 1,5-pentanediamine salt, which can be obtained by: upregulating the expression of lysine decarboxylase in a strain capable of producing lysine using genetic technology, or by recombinantly expressing lysine decarboxylase, so that the lysine produced during fermentation can be simultaneously converted into pentanediamine, thereby directly obtaining a fermentation broth containing 1,5-pentanediamine salt.

[0055] In one embodiment, the second solution is a fermentation broth containing 1,5-pentanediamine salt, so that the first solution after alkalization contains impurities such as metal ions, residual bacterial cells, and anions. These impurities can be separated from the pentanediamine organic solution by alkalization and extraction. At the same time, low-boiling-point substances and impurities in the organic solution can be separated by distillation or rectification to obtain a high-purity pentanediamine product.

[0056] This invention does not have special requirements for recombinant bacteria, as long as 1,5-pentanediamine can be obtained.

[0057] In one embodiment, the enzyme conversion solution or fermentation broth can be an untreated stock solution containing bacterial cells, or a solution system obtained after further treatment (collectively referred to as the treated solution). Examples include a clear solution obtained by filtering bacterial cells and large molecules such as proteins using a ceramic or ultrafiltration membrane, a solution obtained through simple filtration, a clear liquid obtained by centrifugation, or a solution obtained after decolorization and impurity removal using activated carbon. During these processes, insoluble or soluble impurities can be removed, while 1,5-pentanediamine salt can be retained in the solution system. Furthermore, the enzyme conversion solution or fermentation broth, or the treated solution, can be further concentrated using any applicable existing technology, such as evaporation, atmospheric distillation, vacuum distillation, or reverse osmosis.

[0058] In one embodiment, the second solution may be a pure solution system containing an aqueous solution of an inorganic or organic salt of 1,5-pentanediamine, or it may coexist with solid microorganisms or compound impurities.

[0059] In one embodiment, the extraction system is controlled under appropriate conditions to achieve a high extraction rate for pentanediamine while maintaining a low extraction rate for metal ions.

[0060] In one embodiment of the present invention, 1,5-pentanediamine in a first solution is extracted using an organic extractant, causing the 1,5-pentanediamine to transfer from the aqueous phase to the extraction phase (organic phase), after which the extractant is removed. This method, while separating 1,5-pentanediamine, avoids the entry of impurities such as pigments and metal ions into the organic phase, thus achieving further purification.

[0061] In one embodiment of the present invention, when the boiling point of the extractant is lower than that of pentanediamine, the boiling point of the azeotrope formed by pentanediamine and the extractant will also be lower than that of pentanediamine. In this case, the extractant is preferentially distilled out, and the boiling point difference between the extractant and pentanediamine is large, resulting in a higher yield of pentanediamine obtained from distillation. However, when the boiling point of the extractant is higher than that of pentanediamine, pentanediamine will preferentially be distilled out along with the extractant. In this case, if the boiling point difference between the extractant and pentanediamine is relatively small, and there is residual solid residue at the bottom of the vessel, the yield of pentanediamine will decrease.

[0062] In one embodiment of the present invention, the phase separation is good, and no phenomena such as emulsification or flocculent matter that interfere with extraction occur, which is beneficial to subsequent processing.

[0063] In one embodiment of the present invention, a single extractant is used for extraction.

[0064] The method of one embodiment of the present invention involves extracting 1,5-pentanediamine directly from a first solution using an extractant before distillation separation, which can reduce the generation of solid residue in subsequent distillation.

[0065] One embodiment of the present invention provides a 1,5-pentanediamine product prepared by the above method, wherein the purity of the 1,5-pentanediamine product is 98.5 wt% or more, and more preferably 99 wt% or more.

[0066] In one embodiment, the residual extractant content in the 1,5-pentanediamine product is less than 30 ppm, and more specifically less than 10 ppm.

[0067] One embodiment of the present invention further provides a polyamide whose raw materials include the above-mentioned 1,5-pentanediamine product.

[0068] The extraction method of 1,5-pentanediamine according to an embodiment of the present invention will be further described below with reference to specific embodiments.

[0069] Unless otherwise specified, the 1,5-pentanediamine alkalization solution (first solution) used in Examples 1-1 to 1-16 was an alkalization solution containing 1,5-pentanediamine of different concentrations (purchased from Kaisai (Wusu) Biomaterials Co., Ltd.). The 1,5-pentanediamine alkalization solution was obtained by alkalizing fermentation broth containing pentanediamine sulfate and / or pentanediamine carbonate using CaO and / or Ca(OH)2.

[0070] The 1,5-pentanediamine alkalinization solution (first solution) used in Examples 1-17 was obtained by alkalinizing a fermentation broth containing pentanediamine sulfate and / or pentanediamine carbonate using MgO and / or Mg(OH)2.

[0071] In the examples, the ethyl acetate extractant was purchased from Sinopharm Reagent, AR.

[0072] The methods for detecting the performance parameters involved in each embodiment are as follows: 1. Method for determining the purity of pentamethylenediamine: The results were obtained by gas chromatography normalization method, calculated based on the ratio of the peak area of ​​pentanediamine in the gas phase to the total peak area in the gas phase.

[0073] 2. Method for determining the concentration of pentamethylenediamine in the aqueous phase: Nuclear magnetic resonance (NMR) method, using the internal standard method, involves performing NMR analysis on the sample and a heavy aqueous solution of dimethyl sulfoxide (DMSO) as an internal standard.

[0074] 3. The calcium ion concentration was determined by EDTA titration.

[0075] In the examples, the extraction rate of pentanediamine refers to the percentage of 1,5-pentanediamine that enters the organic phase during the extraction process relative to the 1,5-pentanediamine in the aqueous phase before extraction.

[0076] In the examples, the calcium ion extraction rate refers to the percentage of calcium ions that enter the organic phase during the extraction process relative to the calcium ions in the aqueous phase before extraction.

[0077] 4. Light transmittance test: The transmittance of the solution was measured using a UV spectrophotometer at a wavelength of 279 nm, a temperature of 25 °C, and a concentration of 0.1% for 1,5-pentanediamine.

[0078] 5. Determination of extractant content (ppm) in 1,5-pentanediamine products: The results were obtained by gas chromatography normalization method and calculated based on the ratio of the peak area of ​​ethyl acetate to the peak area of ​​pentanediamine in the gas phase.

[0079] Example 1-1 Extraction Treatment

[0080] Take 500g of ethyl acetate as the extractant and 500g of pentanediamine alkalization solution as the raw material. The alkalization solution contains 9.05% pentanediamine by mass. The alkalization solution contains Ca... 2+ The concentration was 4893 ppm, and the pH was 12.65.

[0081] Primary extraction: Ethyl acetate and pentanediamine alkalization solution were placed in a 5L reactor and stirred at 30℃ and 300rpm for 1 hour. After standing for 30 minutes, the two phases completely separated. The organic phase was colorless and transparent, and the phase separation was uniform. The organic phase and aqueous phase were then separated.

[0082] Secondary extraction: Using the aqueous phase obtained after primary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the secondary extraction process is the same as in the primary reaction. The secondary extraction is carried out according to the steps and parameters of the primary extraction.

[0083] Tertiary extraction: Using the aqueous phase obtained after secondary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the tertiary extraction process is the same as that in the primary reaction. The tertiary extraction is carried out according to the steps and parameters of the primary extraction.

[0084] The extraction rates of pentanediamine and calcium ions in the organic phase separated after each extraction stage were measured, as well as the pH of the aqueous phase separated after the third extraction stage.

[0085] The parameters involved in the process and the measured data are shown in Table 1.

[0086] Example 1-2 Extraction Treatment

[0087] Take 1500g of ethyl acetate and 500g of pentanediamine alkalization solution. The alkalization solution contains 9.05% pentanediamine by mass and contains Ca. 2+ The concentration was 4893 ppm, and the pH was 12.65.

[0088] Primary extraction: Ethyl acetate and pentanediamine alkalization solution were placed in a 5L reactor and stirred at 30℃ and 300rpm for 1 hour. After standing for 30 minutes, the two phases completely separated. The organic phase was colorless and transparent, and the phase separation was uniform. The organic phase and aqueous phase were then separated.

[0089] Secondary extraction: Using the aqueous phase obtained after primary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the secondary extraction process is the same as in the primary reaction. The secondary extraction is carried out according to the steps and parameters of the primary extraction.

[0090] Tertiary extraction: Using the aqueous phase obtained after secondary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the tertiary extraction process is the same as that in the primary reaction. The tertiary extraction is carried out according to the steps and parameters of the primary extraction.

[0091] The extraction rates of pentanediamine and calcium ions in the organic phase separated after each extraction stage were measured, as well as the pH of the aqueous phase separated after the third extraction stage.

[0092] The parameters involved in the process and the measured data are shown in Table 1.

[0093] Examples 1-3 Extraction Treatment

[0094] Take 2500g of ethyl acetate and 500g of pentanediamine alkalization solution. The alkalization solution contains 9.05% pentanediamine by mass and contains Ca. 2+ The concentration was 4893 ppm, and the pH was 12.65.

[0095] Primary extraction: Ethyl acetate and pentanediamine alkalization solution were placed in a 5L reactor and stirred at 30℃ and 300rpm for 1 hour. After standing for 30 minutes, the two phases completely separated. The organic phase was colorless and transparent, and the phase separation was uniform. The organic phase and aqueous phase were then separated.

[0096] Secondary extraction: Using the aqueous phase obtained after primary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the secondary extraction process is the same as in the primary reaction. The secondary extraction is carried out according to the steps and parameters of the primary extraction.

[0097] Tertiary extraction: Using the aqueous phase obtained after secondary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the tertiary extraction process is the same as that in the primary reaction. The tertiary extraction is carried out according to the steps and parameters of the primary extraction.

[0098] The extraction rates of pentanediamine and calcium ions in the organic phase separated after each extraction stage were measured, as well as the pH of the aqueous phase separated after the third extraction stage.

[0099] The parameters involved in the process and the measured data are shown in Table 1.

[0100] Examples 1-4 Extraction Treatment

[0101] Take 5000g of ethyl acetate and 500g of pentanediamine alkalization solution. The alkalization solution contains 9.05% pentanediamine by mass and contains Ca. 2+ The concentration was 4893 ppm, and the pH was 12.65.

[0102] Primary extraction: Ethyl acetate and pentanediamine alkalization solution were placed in a 10L reactor and stirred at 30℃ and 300rpm for 1 hour. After standing for 30 minutes, the two phases completely separated. The organic phase was colorless and transparent, and the phase separation was uniform. The organic phase and aqueous phase were then separated.

[0103] Secondary extraction: Using the aqueous phase obtained after primary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the secondary extraction process is the same as in the primary reaction. The secondary extraction is carried out according to the steps and parameters of the primary extraction.

[0104] Tertiary extraction: Using the aqueous phase obtained after secondary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the tertiary extraction process is the same as that in the primary reaction. The tertiary extraction is carried out according to the steps and parameters of the primary extraction.

[0105] The extraction rates of pentanediamine and calcium ions in the organic phase separated after each extraction stage were measured, as well as the pH of the aqueous phase separated after the third extraction stage.

[0106] The parameters involved in the process and the measured data are shown in Table 1.

[0107] Examples 1-5 Extraction Treatment

[0108] Take 10 kg of ethyl acetate and 500 g of pentanediamine alkalization solution. The alkalization solution contains 9.05% pentanediamine by mass and contains Ca. 2+ The concentration was 4893 ppm, and the pH was 12.65.

[0109] Primary extraction: Ethyl acetate and pentanediamine alkalization solution were placed in a 15L reactor and stirred at 30℃ and 300rpm for 1 hour. After standing for 30 minutes, the two phases completely separated. The organic phase was colorless and transparent, and the phase separation was uniform. The organic phase and aqueous phase were then separated.

[0110] Secondary extraction: Using the aqueous phase obtained after primary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the secondary extraction process is the same as in the primary reaction. The secondary extraction is carried out according to the steps and parameters of the primary extraction.

[0111] Tertiary extraction: Using the aqueous phase obtained after secondary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the tertiary extraction process is the same as that in the primary reaction. The tertiary extraction is carried out according to the steps and parameters of the primary extraction.

[0112] The extraction rates of pentanediamine and calcium ions in the organic phase separated after each extraction stage were measured, as well as the pH of the aqueous phase separated after the third extraction stage.

[0113] The parameters involved in the process and the measured data are shown in Table 1.

[0114] Examples 1-6 Extraction Treatment

[0115] Take 2500g of ethyl acetate and 500g of pentanediamine alkalization solution. The alkalization solution contains 1.13% pentanediamine by mass and contains Ca. 2+ The concentration was 4365 ppm, and the pH was 11.03.

[0116] Primary extraction: Ethyl acetate and pentanediamine alkalization solution were placed in a 5L reactor and stirred at 30℃ and 300rpm for 1 hour. After standing for 30 minutes, the two phases completely separated. The organic phase was colorless and transparent, and the phase separation was uniform. The organic phase and aqueous phase were then separated.

[0117] Secondary extraction: Using the aqueous phase obtained after primary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the secondary extraction process is the same as in the primary reaction. The secondary extraction is carried out according to the steps and parameters of the primary extraction.

[0118] Tertiary extraction: Using the aqueous phase obtained after secondary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the tertiary extraction process is the same as that in the primary reaction. The tertiary extraction is carried out according to the steps and parameters of the primary extraction.

[0119] The extraction rates of pentanediamine and calcium ions in the organic phase separated after each extraction stage were measured, as well as the pH of the aqueous phase separated after the third extraction stage.

[0120] The parameters involved in the process and the measured data are shown in Table 1.

[0121] Examples 1-7 Extraction Treatment

[0122] Take 2500g of ethyl acetate and 500g of pentanediamine alkalization solution. The alkalization solution contains 50.76% pentanediamine by mass and contains Ca. 2+ The concentration was 6291 ppm, and the pH was 13.23.

[0123] Primary extraction: Ethyl acetate and pentanediamine alkalization solution were placed in a 5L reactor and stirred at 30℃ and 300rpm for 1 hour. After standing for 30 minutes, the two phases completely separated. The organic phase was colorless and transparent, and the phase separation was uniform. The organic phase and aqueous phase were then separated.

[0124] Secondary extraction: Using the aqueous phase obtained after primary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the secondary extraction process is the same as in the primary reaction. The secondary extraction is carried out according to the steps and parameters of the primary extraction.

[0125] Tertiary extraction: Using the aqueous phase obtained after secondary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the tertiary extraction process is the same as that in the primary reaction. The tertiary extraction is carried out according to the steps and parameters of the primary extraction.

[0126] The extraction rates of pentanediamine and calcium ions in the organic phase separated after each extraction stage were measured, as well as the pH of the aqueous phase separated after the third extraction stage.

[0127] The parameters involved in the process and the measured data are shown in Table 1.

[0128] Examples 1-8 Extraction Treatment

[0129] Take 2500g of ethyl acetate and 500g of pentanediamine alkalization solution. The alkalization solution contains 9.05% pentanediamine by mass and contains Ca. 2+ The concentration was 4893 ppm, and the pH was 12.65.

[0130] Primary extraction: Ethyl acetate and pentanediamine alkalization solution were placed in a 5L reactor and stirred at 10℃ and 300rpm for 1 hour. After standing for 30 minutes, the two phases completely separated. The organic phase was colorless and transparent, and the phase separation was uniform. The organic phase and aqueous phase were then separated.

[0131] Secondary extraction: Using the aqueous phase obtained after primary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the secondary extraction process is the same as in the primary reaction. The secondary extraction is carried out according to the steps and parameters of the primary extraction.

[0132] Tertiary extraction: Using the aqueous phase obtained after secondary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the tertiary extraction process is the same as that in the primary reaction. The tertiary extraction is carried out according to the steps and parameters of the primary extraction.

[0133] The extraction rates of pentanediamine and calcium ions in the organic phase separated after each extraction stage were measured, as well as the pH of the aqueous phase separated after the third extraction stage.

[0134] The parameters involved in the process and the measured data are shown in Table 1.

[0135] Examples 1-9 Extraction Treatment

[0136] Take 2500g of ethyl acetate and 500g of pentanediamine alkalization solution. The alkalization solution contains 9.05% pentanediamine by mass and contains Ca. 2+ The concentration was 4893 ppm, and the pH was 12.65.

[0137] Primary extraction: Ethyl acetate and pentanediamine alkalization solution were placed in a 5L reactor, equipped with a reflux condenser, and stirred at 100℃ and 200rpm for 1 hour, followed by standing for 30 minutes. After cooling, the two phases completely separated; the organic phase was colorless and transparent, and the phase separation was uniform. The organic phase and aqueous phase were then separated.

[0138] Secondary extraction: Using the aqueous phase obtained after primary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the secondary extraction process is the same as in the primary reaction. The secondary extraction is carried out according to the steps and parameters of the primary extraction.

[0139] Tertiary extraction: Using the aqueous phase obtained after secondary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the tertiary extraction process is the same as that in the primary reaction. The tertiary extraction is carried out according to the steps and parameters of the primary extraction.

[0140] The extraction rates of pentanediamine and calcium ions in the organic phase separated after each extraction stage were measured, as well as the pH of the aqueous phase separated after the third extraction stage.

[0141] The parameters involved in the process and the measured data are shown in Table 1.

[0142] Extraction treatment in Examples 1-10

[0143] Take 2500g of butyl acetate and 500g of pentanediamine alkalization solution. The alkalization solution contains 9.05% pentanediamine by mass and contains Ca. 2+ The concentration was 4893 ppm, and the pH was 12.65.

[0144] Primary extraction: Butyl acetate and pentanediamine alkalization solution were placed in a 5L reactor and stirred at 30℃ and 300rpm for 1 hour. After standing for 30 minutes, the two phases completely separated. The organic phase was colorless and transparent, and the phase separation was uniform. The organic phase and aqueous phase were then separated.

[0145] Secondary extraction: Using the aqueous phase obtained after primary extraction as the raw material, butyl acetate is used as the extractant. The mass ratio of butyl acetate to aqueous phase in the secondary extraction process is the same as in the primary reaction. The secondary extraction is carried out according to the steps and parameters of the primary extraction.

[0146] Tertiary extraction: Using the aqueous phase obtained after secondary extraction as the raw material, butyl acetate is used as the extractant. The mass ratio of butyl acetate to aqueous phase in the tertiary extraction process is the same as that in the primary reaction. The tertiary extraction is carried out according to the steps and parameters of the primary extraction.

[0147] The extraction rates of pentanediamine and calcium ions in the organic phase separated after each extraction stage were measured, as well as the pH of the aqueous phase separated after the third extraction stage.

[0148] The parameters involved in the process and the measured data are shown in Table 1.

[0149] Extraction treatment in Examples 1-11

[0150] Take 2500g of methyl benzoate and 500g of pentanediamine alkalization solution. The alkalization solution contains 9.05% pentanediamine by mass and contains Ca. 2+ The concentration was 4893 ppm, and the pH was 12.65.

[0151] Primary extraction: Methyl benzoate and pentanediamine alkaline solution were placed in a 5L reactor and stirred at 30℃ and 300rpm for 1 hour. After standing for 30 minutes, the two phases completely separated. The organic phase was colorless and transparent, and the phase separation was uniform. The organic phase and aqueous phase were then separated.

[0152] Secondary extraction: Using the aqueous phase obtained after primary extraction as the raw material, methyl benzoate is used as the extractant. The mass ratio of methyl benzoate to aqueous phase in the secondary extraction process is the same as in the primary reaction. The secondary extraction is carried out according to the steps and parameters of the primary extraction.

[0153] Tertiary extraction: Using the aqueous phase obtained after secondary extraction as the raw material, methyl benzoate is used as the extractant. The mass ratio of methyl benzoate to aqueous phase in the tertiary extraction process is the same as that in the primary reaction. The tertiary extraction is carried out according to the steps and parameters of the primary extraction.

[0154] The extraction rates of pentanediamine and calcium ions in the organic phase separated after each extraction stage were measured, as well as the pH of the aqueous phase separated after the third extraction stage.

[0155] The parameters involved in the process and the measured data are shown in Table 1.

[0156] Extraction treatment in Examples 1-12

[0157] Take 1250g of ethyl acetate, 1250g of butyl acetate, and 500g of pentanediamine alkalization solution. The alkalization solution contains 9.05% pentanediamine by mass and contains Ca. 2+ The concentration was 4893 ppm, and the pH was 12.65.

[0158] Primary extraction: Ethyl acetate, butyl acetate, and pentanediamine alkalization solution were placed in a 5L reactor and stirred at 30℃ and 300rpm for 1 hour. After standing for 30 minutes, the two phases completely separated. The organic phase was colorless and transparent, and the phase separation was uniform. The organic phase and aqueous phase were then separated.

[0159] Secondary extraction: Using the aqueous phase obtained after primary extraction as the raw material, ethyl acetate and butyl acetate are used as extractants, with the same molar ratio of ethyl acetate to butyl acetate as in primary extraction. The mass ratio of extractant to aqueous phase in secondary extraction is the same as in primary reaction. Secondary extraction is carried out according to the steps and parameters of primary extraction.

[0160] Tertiary extraction: Using the aqueous phase obtained after secondary extraction as the raw material, ethyl acetate and butyl acetate are used as extractants, with the same molar ratio of ethyl acetate to butyl acetate as in primary extraction. The mass ratio of extractant to aqueous phase in tertiary extraction is the same as in primary reaction. Tertiary extraction is carried out according to the steps and parameters of primary extraction.

[0161] The extraction rates of pentanediamine and calcium ions in the organic phase separated after each extraction stage were measured, as well as the pH of the aqueous phase separated after the third extraction stage.

[0162] The parameters involved in the process and the measured data are shown in Table 1.

[0163] Examples 1-13 Extraction Treatment

[0164] Take 2500g of dichloromethane and 500g of pentanediamine alkalization solution. The alkalization solution contains 9.05% pentanediamine by mass and contains Ca. 2+The concentration was 4893 ppm, and the pH was 12.65.

[0165] Primary extraction: Dichloromethane and pentanediamine alkalization solution were placed in a 5L reactor and stirred at 30℃ and 300rpm for 1 hour. After standing for 30 minutes, the two phases completely separated. The organic phase was colorless and transparent, and the phase separation was uniform. The organic phase and aqueous phase were then separated.

[0166] Secondary extraction: Using the aqueous phase obtained after primary extraction as the raw material, dichloromethane is used as the extractant. The mass ratio of dichloromethane to aqueous phase in the secondary extraction process is the same as in the primary reaction. The secondary extraction is carried out according to the steps and parameters of the primary extraction.

[0167] Tertiary extraction: Using the aqueous phase obtained after secondary extraction as the raw material, dichloromethane is used as the extractant. The mass ratio of dichloromethane to aqueous phase in the tertiary extraction process is the same as that in the primary reaction. The tertiary extraction is carried out according to the steps and parameters of the primary extraction.

[0168] The extraction rates of pentanediamine and calcium ions in the organic phase separated after each extraction stage were measured, as well as the pH of the aqueous phase separated after the third extraction stage.

[0169] The parameters involved in the process and the measured data are shown in Table 1.

[0170] Examples 1-14 Extraction Treatment

[0171] Take 2500g of isopropyl ether and 500g of pentanediamine alkalization solution. The alkalization solution contains 9.05% pentanediamine by mass and contains Ca. 2+ The concentration was 4893 ppm, and the pH was 12.65.

[0172] Primary extraction: Isopropyl ether and pentanediamine alkalization solution were placed in a 5L reactor and stirred for 1 hour at 30℃ and 300 rpm. After standing for 30 minutes, the two phases completely separated. The organic phase was colorless and transparent, and the phase separation was uniform. The organic phase and aqueous phase were then separated.

[0173] Secondary extraction: Using the aqueous phase obtained after primary extraction as the raw material, isopropyl ether is used as the extractant. The mass ratio of isopropyl ether to aqueous phase in the secondary extraction process is the same as in the primary reaction. The secondary extraction is carried out according to the steps and parameters of the primary extraction.

[0174] Tertiary extraction: Using the aqueous phase obtained after secondary extraction as the raw material, isopropyl ether is used as the extractant. The mass ratio of isopropyl ether to aqueous phase in the tertiary extraction process is the same as that in the primary reaction. The tertiary extraction is carried out according to the steps and parameters of the primary extraction.

[0175] The extraction rates of pentanediamine and calcium ions in the organic phase separated after each extraction stage were measured, as well as the pH of the aqueous phase separated after the third extraction stage.

[0176] The parameters involved in the process and the measured data are shown in Table 1.

[0177] Examples 1-15 Extraction Treatment

[0178] Take 2500g of xylene and 500g of pentanediamine alkalization solution. The alkalization solution contains 9.05% pentanediamine by mass and contains Ca. 2+ The concentration was 4893 ppm, and the pH was 12.65.

[0179] Primary extraction: Xylene and pentanediamine alkalization solution were placed in a 5L reactor and stirred at 30℃ and 300rpm for 1 hour. After standing for 30 minutes, the two phases were completely separated. The organic phase was transparent but contained a small amount of pigment. The phase separation was uniform and good. The organic phase and aqueous phase were then separated.

[0180] Secondary extraction: Using the aqueous phase obtained after primary extraction as the raw material, xylene is used as the extractant. The mass ratio of xylene to aqueous phase in the secondary extraction process is the same as in the primary reaction. The secondary extraction is carried out according to the steps and parameters of the primary extraction.

[0181] Tertiary extraction: Using the aqueous phase obtained after secondary extraction as the raw material, xylene is used as the extractant. The mass ratio of xylene to aqueous phase in the tertiary extraction process is the same as that in the primary reaction. The tertiary extraction is carried out according to the steps and parameters of the primary extraction.

[0182] The extraction rates of pentanediamine and calcium ions in the organic phase separated after each extraction stage were measured, as well as the pH of the aqueous phase separated after the third extraction stage.

[0183] The parameters involved in the process and the measured data are shown in Table 1.

[0184] Examples 1-16 Extraction Treatment

[0185] Take 2500g of n-hexane and 500g of pentanediamine alkalization solution. The alkalization solution contains 9.05% pentanediamine by mass and contains Ca. 2+ The concentration was 4893 ppm, and the pH was 12.65.

[0186] Primary extraction: Hexane and pentanediamine alkalization solution were placed in a 5L reactor and stirred for 1 hour at 30℃ and 300 rpm. After standing for 30 minutes, the two phases completely separated. The organic phase was colorless and transparent, with good phase separation. The organic and aqueous phases were then separated.

[0187] Secondary extraction: Using the aqueous phase obtained after primary extraction as the raw material, n-hexane is used as the extractant. The mass ratio of n-hexane to aqueous phase in the secondary extraction process is the same as in the primary reaction. The secondary extraction is carried out according to the steps and parameters of the primary extraction.

[0188] Tertiary extraction: Using the aqueous phase obtained after secondary extraction as the raw material, n-hexane is used as the extractant. The mass ratio of n-hexane to aqueous phase in the tertiary extraction process is the same as that in the primary reaction. The tertiary extraction is carried out according to the steps and parameters of the primary extraction.

[0189] The extraction rates of pentanediamine and calcium ions in the organic phase separated after each extraction stage were measured, as well as the pH of the aqueous phase separated after the third extraction stage.

[0190] The parameters involved in the process and the measured data are shown in Table 1.

[0191] Examples 1-17 Extraction Treatment

[0192] Take 2500g of ethyl acetate and 500g of pentanediamine alkalization solution. The alkalization solution contains 8.93% pentanediamine by mass and contains Mg. 2+ The concentration was 4329 ppm, and the pH was 12.28.

[0193] Primary extraction: Ethyl acetate and pentanediamine alkalization solution were placed in a 5L reactor and stirred at 30℃ and 300rpm for 1 hour. After standing for 30 minutes, the two phases completely separated. The organic phase was colorless and transparent, and the phase separation was uniform. The organic phase and aqueous phase were then separated.

[0194] Secondary extraction: Using the aqueous phase obtained after primary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the secondary extraction process is the same as in the primary reaction. The secondary extraction is carried out according to the steps and parameters of the primary extraction.

[0195] Tertiary extraction: Using the aqueous phase obtained after secondary extraction as the raw material, ethyl acetate is used as the extractant. The mass ratio of ethyl acetate to aqueous phase in the tertiary extraction process is the same as that in the primary reaction. The tertiary extraction is carried out according to the steps and parameters of the primary extraction.

[0196] The extraction rates of pentanediamine and magnesium ions in the organic phase separated after each extraction stage were measured, as well as the pH of the aqueous phase separated after the third extraction stage.

[0197] The parameters involved in the process and the measured data are shown in Table 1.

[0198] Table 1

[0199] Referring to Table 1, different amounts of extractant have varying effects on the extraction results. Higher amounts of extractant have a positive effect on pentamethylenediamine extraction, but when the oil-to-water ratio of the extractant to the alkalizing solution reaches 5:1 or higher, the increase in extraction efficiency at each stage slows down. Simultaneously, the extraction rate of metal ions is relatively low. However, when the oil-to-water ratio increases to 10:1 or higher, the extraction rate of metal ions also increases significantly.

[0200] Furthermore, extraction efficiency can be further improved by controlling an appropriate extraction temperature. Extraction at low temperatures is mainly due to the restriction of molecular motion within the system at lower temperatures, which inhibits extraction to some extent.

[0201] Extraction efficiency varies considerably depending on the type of extractant used. When esters are used as extractants, they exhibit high extraction efficiency for pentanediamine in the system, while ensuring minimal extraction of metal ions, thus reducing solid residue in subsequent distillation processes. Furthermore, the extracted organic phase is colorless and transparent, with no pigment incorporation, and exhibits excellent phase separation.

[0202] Examples 2-1 to 2-9: Distillation Treatment

[0203] Organic phase solutions were obtained by extraction according to Examples 1-1 to 1-9, and relevant distillation experiments were performed respectively. The specific procedures are as follows: The organic phases obtained from each extraction stage were collected, and 1 kg of the collected sample was subjected to vacuum distillation. During vacuum distillation, the pressure was -0.01 MPa and the temperature was 45–50 °C, during which ethyl acetate was distilled off. After the ethyl acetate was completely distilled off, the temperature was raised to 80 °C to distill off a small amount of water in the system. Subsequently, the temperature was raised to 160 °C to gradually distill off pentamethylenediamine.

[0204] Example 2-10 Distillation Treatment

[0205] The organic phase solutions obtained by extraction treatment according to Examples 1-10 were subjected to relevant distillation experiments, and the specific procedures are as follows: The organic phases obtained from each extraction stage were collected, and 1 kg of the collected sample was subjected to vacuum distillation. During vacuum distillation, the pressure was -0.01 MPa, and the temperature was raised to 80°C to evaporate a small amount of water from the system. Subsequently, the temperature was raised to 105°C, and butyl acetate was distilled off. After the butyl acetate distillation was complete, the temperature was raised to 160°C to gradually distill off pentamethylenediamine.

[0206] Example 2-11 Distillation Treatment

[0207] The organic phase solutions obtained by extraction treatment according to Examples 1-11 were subjected to relevant distillation experiments, and the specific procedures are as follows: The organic phases obtained from each extraction stage were collected, and 1 kg of the collected sample was subjected to vacuum distillation. During vacuum distillation, the pressure was -0.01 MPa, and the temperature was raised to 80°C to remove a small amount of water from the system. The temperature was then raised to 160°C, and pentanediamine was distilled off. After the pentanediamine was completely distilled off, the temperature was raised to 190°C, and methyl benzoate was gradually distilled off.

[0208] Example 2-12 Distillation Treatment

[0209] The organic phase solutions obtained by extraction in Examples 1-12 were subjected to relevant distillation experiments, and the specific procedures are as follows: The organic phases obtained from each extraction stage were collected, and 1 kg of the collected sample was subjected to vacuum distillation. During vacuum distillation, the pressure was -0.01 MPa and the temperature was 45–50 °C, during which ethyl acetate was distilled off. After the ethyl acetate was completely distilled off, the temperature was raised to 105 °C to distill off small amounts of water and butyl acetate. Subsequently, the temperature was raised to 160 °C to gradually distill off pentamethylenediamine.

[0210] Example 2-13 Distillation Treatment

[0211] The organic phase solutions obtained by extraction treatment according to Examples 1-13 were subjected to relevant distillation experiments, the specific procedures of which are as follows: The organic phases obtained from each extraction stage were collected, and 1 kg of the collected sample was subjected to vacuum distillation. During vacuum distillation, the pressure was -0.01 MPa and the temperature was 40 °C, during which dichloromethane was distilled off. After the dichloromethane was completely distilled off, the temperature was raised to 80 °C to distill off a small amount of water in the system. Subsequently, the temperature was raised to 160 °C to gradually distill off pentamethylenediamine.

[0212] Example 2-14 Distillation Treatment

[0213] The organic phase solutions obtained by extraction treatment according to Examples 1-14 were subjected to relevant distillation experiments, and the specific procedures are as follows: The organic phases obtained from each extraction stage were collected, and 1 kg of the collected sample was subjected to vacuum distillation. During vacuum distillation, the pressure was -0.01 MPa and the temperature was 70 °C, during which isopropyl ether was distilled off. After the isopropyl ether was completely distilled off, the temperature was raised to 80 °C to distill off a small amount of water in the system. Subsequently, the temperature was raised to 160 °C to gradually distill off pentamethylenediamine.

[0214] Example 2-15 Distillation Treatment

[0215] The organic phase solutions obtained by extraction in Examples 1-15 were subjected to relevant distillation experiments, and the specific procedures are as follows: The organic phases obtained from each extraction stage were collected, and 1 kg of the collected sample was subjected to vacuum distillation. During vacuum distillation, the pressure was -0.01 MPa, and the temperature was raised to 80°C to evaporate a small amount of water from the system. The temperature was then raised to 120°C to gradually evaporate xylene. Finally, the temperature was raised to 160°C to gradually evaporate pentamethylenediamine.

[0216] Example 2-16 Distillation Treatment

[0217] The organic phase solutions obtained by extraction in Examples 1-16 were subjected to relevant distillation experiments, and the specific procedures are as follows: The organic phases obtained from each extraction stage were collected, and 1 kg of the collected sample was subjected to vacuum distillation. During vacuum distillation, the pressure was -0.01 MPa and the temperature was 70 °C, during which n-hexane was distilled off. After the n-hexane distillation was complete, the temperature was raised to 80 °C to distill off a small amount of water in the system. Subsequently, the temperature was raised to 160 °C to gradually distill off pentanediamine.

[0218] Example 2-17 Distillation Treatment

[0219] Organic phase solutions were obtained by extraction according to Examples 1-17, and relevant distillation experiments were performed accordingly. The specific procedures are as follows: The organic phases obtained from each extraction stage were collected, and 1 kg of the collected sample was subjected to vacuum distillation. During vacuum distillation, the pressure was -0.01 MPa and the temperature was 45–50 °C, during which ethyl acetate was distilled off. After the ethyl acetate was completely distilled off, the temperature was raised to 80 °C to distill off a small amount of water in the system. Subsequently, the temperature was raised to 160 °C to gradually distill off pentamethylenediamine.

[0220] The samples and final products involved in Examples 2-1 to 2-17 were subjected to relevant tests, and the specific results are shown in Table 2.

[0221] Table 2

[0222] Unless otherwise specified, the terms used in this invention have the meanings commonly understood by those skilled in the art.

[0223] The embodiments described in this invention are for illustrative purposes only and are not intended to limit the scope of protection of this invention. Those skilled in the art can make various other substitutions, changes and improvements within the scope of this invention. Therefore, this invention is not limited to the above embodiments, but is only defined by the claims.

Claims

1. A method for extracting 1,5-pentanediamine, comprising: A first solution is provided, the first solution comprising 1,5-pentanediamine and water; The 1,5-pentanediamine in the first solution was extracted with an extractant to obtain an organic solution containing the 1,5-pentanediamine and the extractant. as well as The 1,5-pentanediamine was separated from the organic solution; The first solution contains metal ions, including calcium ions and / or magnesium ions. Wherein, the molar ratio of the extractant to 1,5-pentanediamine in the first solution is (5-300):1, the extractant is ethyl acetate, the mass ratio of the extractant to the first solution is (1-7):1, and the extraction process includes n or more stages of extraction, where n≥3.

2. The method according to claim 1, wherein, The pH of the aqueous phase after tertiary extraction is 9.0–11.5; and / or the difference between the pH of the first solution and the pH of the aqueous phase after tertiary extraction is ≥2.

3. The method according to claim 2, wherein, The pH of the aqueous phase after tertiary extraction is 9.0–10.

5.

4. The method according to claim 2, wherein, The difference between the pH value of the first solution and the pH value of the aqueous phase after tertiary extraction is ≥2.

5.

5. The method according to claim 2, wherein, The difference between the pH value of the first solution and the pH value of the aqueous phase after tertiary extraction is ≥2.

7.

6. The method according to claim 1, further comprising concentrating the aqueous solution to be extracted before performing any first-stage extraction.

7. The method according to claim 1, wherein, The molar ratio of the extractant to 1,5-pentanediamine in the first solution is (10-250):1; and / or the extraction temperature is 10-100°C.

8. The method according to claim 1 or 7, wherein, The concentration of the 1,5-pentanediamine in the first solution is less than or equal to 50 wt%.

9. The method according to claim 1 or 7, wherein, The concentration of the 1,5-pentanediamine in the first solution is less than or equal to 30 wt%.

10. The method according to claim 1 or 7, wherein, The concentration of the 1,5-pentanediamine in the first solution is less than or equal to 20 wt%.

11. The method according to claim 1 or 7, wherein, The concentration of metal ions in the first solution is less than 2 wt%.

12. The method according to claim 11, wherein, The concentration of metal ions in the first solution is less than 1 wt%.

13. The method according to claim 1, wherein, The 1,5-pentanediamine is separated from the organic solution by a distillation or fractionation process.

14. The method according to claim 1, wherein, The preparation process of the first solution includes: Provide a second solution comprising 1,5-pentanediamine salt and water; and An alkaline substance is added to the second solution, and the 1,5-pentanediamine salt reacts with the alkaline substance to generate 1,5-pentanediamine; the 1,5-pentanediamine salt includes one, two or three of the sulfate, hydrochloride or carbonate salts of 1,5-pentanediamine.

15. The method according to claim 14, wherein, The second solution is an aqueous solution of 1,5-pentanediamine salt, or a fermentation broth or enzyme conversion broth containing 1,5-pentanediamine salt produced by biological methods.

16. The method according to claim 1 or 13, wherein, The organic solution has a light transmittance of over 92% and a metal ion content of less than 500 ppm.

17. The method according to claim 16, wherein, The content of metal ions in the organic solution is below 200 ppm.

18. The method according to claim 1, wherein, The purity of the obtained 1,5-pentanediamine product was above 98.5 wt%.

19. The method according to claim 1, wherein, The content of the extractant in the obtained 1,5-pentanediamine product is less than 30 ppm.

20. The method according to claim 1, wherein, The content of the extractant in the obtained 1,5-pentanediamine product is less than 10 ppm.

21. A method for producing polyamide, comprising carrying out the method according to any one of claims 1-20, and producing polyamide from the resulting 1,5-pentanediamine product.

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