A method for recovering methanol and triethylamine from a calcium ketonate salt formation mother liquor
Patent Information
- Application Number
- CN202611132551.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-29
- Publication Date
- 2026-09-22
AI Technical Summary
[0005]有鉴于此，本发明提供了一种从酮酸钙成盐母液中回收甲醇和三乙胺的方法，以解决现有技术中酮酸钙成盐母液的组分复杂、受热易分解，导致甲醇和三乙胺的回收难度大、纯度难以满足回用标准的问题
本发明通过对酮酸钙成盐母液调节pH进行减压低温蒸发，得到含有甲醇、水、乙酸乙酯、酮酸的酸性混合溶液和含有三乙胺盐酸盐、水、氯化钙、甲醇的蒸发残留物；然后将酸性混合溶液转移至精馏塔中，控制回流比进行精馏，收集64~64.5℃之间馏分得到甲醇；同时，通过向蒸发残留物中加入水束缚其中残留的甲醇，并加入碱液调节体系pH，蒸馏得到三乙胺；该方法能够有效克服母液组分复杂、易分解的不利影响，最终甲醇和三乙胺的回收率均不低于70%，且纯度均能满足回用套用的质量要求，大幅降低了生产成本。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of calcium ketoate salt formation mother liquor treatment technology, and in particular to a method for recovering methanol and triethylamine from calcium ketoate salt formation mother liquor. Background Technology
[0002] During the calcium ketoate salt formation process, a mixed mother liquor containing methanol, triethylamine, ethyl acetate, calcium ketoate, and impurities is generated. To reduce production costs and meet GMP quality management requirements, the solvent in this mother liquor must be recovered, and the recovered materials must meet the specified quality standards before they can be reused.
[0003] However, the mother liquor of calcium ketoate salt formation has a complex composition with significant differences in boiling points among its components. Furthermore, during heating, some components are prone to decomposition reactions, generating new impurities and further increasing the number of components in the system. This significantly increases the difficulty of recovering methanol and triethylamine from the calcium ketoate salt formation mother liquor. In addition, there are currently no reports on the recovery of such complex mixed components from the calcium ketoate salt formation mother liquor.
[0004] Therefore, there is an urgent need to provide a method for efficiently and with high purity recovering methanol and triethylamine from calcium ketoate salt mother liquor, and to make it meet the quality requirements for reuse. Summary of the Invention
[0005] In view of this, the present invention provides a method for recovering methanol and triethylamine from calcium ketoate salt formation mother liquor, in order to solve the problems in the prior art where the composition of calcium ketoate salt formation mother liquor is complex and easily decomposed by heat, resulting in the difficulty of recovering methanol and triethylamine and the inability to meet the purity standards for reuse.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for recovering methanol and triethylamine from calcium ketoate salt formation mother liquor, comprising the following steps: 1) Mix the calcium ketoate salt mother liquor with a pH adjuster and evaporate under reduced pressure to obtain an acidic mixed solution and evaporation residue; 2) The acidic mixed solution was subjected to rectification distillation, and the fraction at 64~64.5℃ was collected to obtain methanol; 3) Mix the evaporation residue, water, and alkaline solution, and distill to obtain triethylamine; There is no specific order requirement for steps 2) and 3).
[0007] Preferably, the calcium ketoate salt-forming mother liquor in step 1) comprises the following components by mass percentage: Calcium ketoate 1-8%, triethylamine hydrochloride 2-10%, ethyl acetate 3-10%, methanol 70-90%, calcium chloride 0.5-2%, water 3-8%.
[0008] Preferably, the amount of pH adjuster used in step 1) is such that the pH value of the mixed system is 2 to 4.
[0009] Preferably, the pressure of the reduced pressure evaporation in step 1) is ≤-0.09 MPa and the temperature is ≤45℃.
[0010] Preferably, the pH adjuster in step 1) includes one or more of hydrochloric acid, sulfuric acid, and sulfurous acid.
[0011] Preferably, the reflux ratio of the distillation process in step 2) is 3~6:1.
[0012] Preferably, the mass ratio of the evaporation residue to water in step 3) is 2~5:5~10:500~1000 kg; the amount of alkali solution used is such that the pH value of the mixed system is 13~14.
[0013] Preferably, the distillation temperature in step 3) is 80~95℃ and the time is 2~4 h.
[0014] Preferably, the alkaline solution in step 3) includes one or more of sodium hydroxide, potassium hydroxide, and sodium carbonate.
[0015] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows: This invention involves adjusting the pH of the calcium ketoate salt formation mother liquor and then subjecting it to reduced pressure and low-temperature evaporation to obtain an acidic mixed solution containing methanol, water, ethyl acetate, and keto acids, and an evaporation residue containing triethylamine hydrochloride, water, calcium chloride, and methanol. The acidic mixed solution is then transferred to a distillation column, and distillation is performed under controlled reflux ratio. The fraction collected at 64-64.5°C yields methanol. Simultaneously, water is added to the evaporation residue to bind any residual methanol, and an alkaline solution is added to adjust the pH of the system before distillation to obtain triethylamine. This method effectively overcomes the adverse effects of the complex composition and easy decomposition of the mother liquor. The final recovery rates of both methanol and triethylamine are not less than 70%, and the purity meets the quality requirements for reuse, significantly reducing production costs. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0017] Figure 1 The chromatogram of methanol recovered in Example 1; Figure 2The chromatogram is of the triethylamine recovered in Example 1. Detailed Implementation
[0018] This invention provides a method for recovering methanol and triethylamine from calcium ketoate salt formation mother liquor, comprising the following steps: 1) Mix the calcium ketoate salt mother liquor with a pH adjuster and evaporate under reduced pressure to obtain an acidic mixed solution and evaporation residue; 2) The acidic mixed solution was subjected to rectification distillation, and the fraction at 64~64.5℃ was collected to obtain methanol; 3) Mix the evaporation residue, water, and alkaline solution, and distill to obtain triethylamine; There is no specific order requirement for steps 2) and 3).
[0019] In this invention, the calcium ketoate salt-forming mother liquor in step 1) preferably comprises the following components by mass percentage: calcium ketoate 1-8%, triethylamine hydrochloride 2-10%, ethyl acetate 3-10%, methanol 70-90%, calcium chloride 0.5-2%, and water 3-8%; more preferably, it comprises the following components by mass percentage: calcium ketoate 3-6%, triethylamine hydrochloride 3-5%, ethyl acetate 4-6%, methanol 75-80%, calcium chloride 1-1.5%, and water 4-6%.
[0020] In this invention, the acidic mixed solution in step 1) preferably includes methanol, water, ethyl acetate and keto acid; the evaporation residue preferably includes triethylamine hydrochloride, water, calcium chloride and methanol.
[0021] In this invention, the amount of pH adjuster used in step 1) is such that the pH value of the mixed system is 2 to 4, preferably 2.5 to 3.5, and more preferably 3.
[0022] In this invention, the pressure of the reduced pressure evaporation in step 1) is ≤-0.09 MPa, preferably -0.01~-0.085 MPa, more preferably -0.02~-0.07 MPa, and even more preferably -0.03~-0.05 MPa; the temperature of the reduced pressure evaporation is ≤45℃, preferably 35~44℃, more preferably 38~43℃, and even more preferably 40~42℃.
[0023] In this invention, the pH adjuster mentioned in step 1) preferably includes one or more of hydrochloric acid, sulfuric acid, and sulfurous acid.
[0024] In this invention, the reflux ratio of the distillation process in step 2) is 3 to 6:1, preferably one of 3:1, 4:1, 5:1, and 6:1.
[0025] In this invention, the fractions before 64°C and after 64.5°C during the distillation process in step 2) are preferably discarded.
[0026] In this invention, the mass ratio of the evaporation residue to water in step 3) is 2~5:5~10, preferably 2.2~4.5:5.5~9, more preferably 2.5~4:6~8.5, and even more preferably 3~3.5:7~8; the role of the water is to bind the methanol remaining in the evaporation residue; the amount of alkaline solution used is to make the pH value of the mixed system 13~14, preferably one of 13, 13.5, and 14.
[0027] In this invention, the distillation temperature in step 3) is 80~95℃, preferably 82~93℃, more preferably 85~92℃, and even more preferably 88~90℃; the distillation time is 2~4 h, preferably 2.2~3.8 h, more preferably 2.5~3.5 h, and even more preferably 3 h.
[0028] In this invention, the alkaline solution in step 3) preferably includes one or more of sodium hydroxide, potassium hydroxide, and sodium carbonate.
[0029] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0030] Example 1
[0031] 1) The calcium ketoate salt mother liquor (2% calcium ketoate, 10% triethylamine hydrochloride, 8% ethyl acetate, 70% methanol, 2% calcium chloride, and 8% water) was mixed with hydrochloric acid in a reaction vessel. The pH of the system was adjusted to 2, the vacuum degree was controlled at -0.09 MPa, and the temperature was 45℃ for vacuum evaporation to obtain an acidic mixed solution containing methanol, water, ethyl acetate and keto acid and an evaporation residue containing triethylamine hydrochloride, water, calcium chloride and methanol. 2) Transfer the acidic mixed solution obtained in step 1) to a distillation column, control the reflux ratio to 3:1 for distillation, collect the fraction at 64~64.5℃ to the methanol product tank to obtain methanol, and discard the fraction before 64℃ and the fraction after 64.5℃. 3) Mix the evaporation residue obtained in step 1) with purified water (the mass ratio of evaporation residue to purified water is 200 kg: 500 kg), and slowly add 30% sodium hydroxide to adjust the pH of the system to 14. Control the temperature at 85℃ and distill for 2 hours to obtain triethylamine.
[0032] Testing showed that the recovery rates of methanol and triethylamine recovered in this embodiment were 75% and 78%, respectively; and the purities were 99.96% and 99.84%, respectively, meeting the quality requirements for reuse.
[0033] The chromatogram of the methanol recovered in this embodiment is as follows: Figure 1 As shown, the chromatogram of triethylamine is as follows. Figure 2 As shown; where, Figure 1 The chromatographic parameters of each component are shown in Table 1. Figure 2 The chromatographic parameters of each component are shown in Table 2.
[0034] Table 1 Figure 1 Chromatographic parameters of each component
[0035] Table 2 Figure 2 Chromatographic parameters of each component
[0036] from Figures 1-2 As can be seen from the data, the quality of both the recovered methanol and the recovered triethylamine has reached the quality standards of freshly purchased solvents, and they can be reused to reduce costs.
[0037] Example 2
[0038] 1) The calcium ketoate salt mother liquor (calcium ketoate 3%, triethylamine hydrochloride 9%, ethyl acetate 7%, methanol 75%, calcium chloride 0.5%, water 5.5%) was mixed with hydrochloric acid in a reaction vessel. The pH of the system was adjusted to 4, the vacuum degree was controlled at -0.09 MPa, and the temperature was 40℃ for vacuum evaporation to obtain an acidic mixed solution containing methanol, water, ethyl acetate and keto acid and an evaporation residue containing triethylamine hydrochloride, water, calcium chloride and methanol. 2) Transfer the acidic mixed solution obtained in step 1) to a distillation column, control the reflux ratio to 4:1 for distillation, collect the fraction at 64~64.5℃ to the methanol product tank to obtain methanol, and discard the fraction before 64℃ and the fraction after 64.5℃. 3) Mix the evaporation residue obtained in step 1) with purified water (the mass ratio of evaporation residue to purified water is 500 kg: 800 kg), and slowly add 30% potassium hydroxide to adjust the pH of the system to 13. Control the temperature at 90℃ and distill for 3 hours to obtain triethylamine.
[0039] Testing showed that the recovery rates of methanol and triethylamine recovered in this embodiment were 80% and 82%, respectively; and the purities were 99.87% and 99.79%, respectively, meeting the quality requirements for reuse.
[0040] Example 3
[0041] 1) The calcium ketoate salt mother liquor (1% calcium ketoate, 6% triethylamine hydrochloride, 4% ethyl acetate, 80% methanol, 1% calcium chloride, and 8% water) was mixed with hydrochloric acid in a reaction vessel. The pH of the system was adjusted to 3, the vacuum degree was controlled at -0.09 MPa, and the temperature was 42℃ for vacuum evaporation to obtain an acidic mixed solution containing methanol, water, ethyl acetate and keto acid and an evaporation residue containing triethylamine hydrochloride, water, calcium chloride and methanol. 2) Transfer the acidic mixed solution obtained in step 1) to a distillation column, control the reflux ratio to 6:1 for distillation, collect the fraction at 64~64.5℃ to the methanol product tank to obtain methanol, and discard the fraction before 64℃ and the fraction after 64.5℃. 3) Mix the evaporation residue obtained in step 1) with purified water (the mass ratio of evaporation residue to purified water is 300 kg: 1000 kg), and slowly add 30% sodium hydroxide to adjust the pH of the system to 14. Control the temperature at 95℃ and distill for 2 hours to obtain triethylamine.
[0042] Testing showed that the recovery rates of methanol and triethylamine recovered in this embodiment were 79% and 78%, respectively; and the purities were 99.93% and 99.82%, respectively, meeting the quality requirements for reuse.
[0043] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for recovering methanol and triethylamine from calcium ketoate salt formation mother liquor, characterized in that, The steps include the following: 1) Mix the calcium ketoate salt mother liquor with a pH adjuster and evaporate under reduced pressure to obtain an acidic mixed solution and evaporation residue; 2) The acidic mixed solution was subjected to rectification distillation, and the fraction at 64~64.5℃ was collected to obtain methanol; 3) Mix the evaporation residue, water, and alkaline solution, and distill to obtain triethylamine; There is no specific order requirement for steps 2) and 3).
2. The method for recovering methanol and triethylamine from calcium ketoate salt formation mother liquor according to claim 1, characterized in that, The calcium ketoate salt-forming mother liquor described in step 1) comprises the following components by mass percentage: Calcium ketoate 1-8%, triethylamine hydrochloride 2-10%, ethyl acetate 3-10%, methanol 70-90%, calcium chloride 0.5-2%, water 3-8%.
3. The method for recovering methanol and triethylamine from calcium ketoate salt formation mother liquor according to claim 2, characterized in that, The amount of pH adjuster used in step 1) is such that the pH value of the mixed system is 2 to 4.
4. A method for recovering methanol and triethylamine from calcium ketoate salt formation mother liquor according to any one of claims 1 to 3, characterized in that, The pressure for vacuum evaporation in step 1) is ≤-0.09 MPa and the temperature is ≤45℃.
5. The method for recovering methanol and triethylamine from calcium ketoate salt formation mother liquor according to claim 4, characterized in that, The pH adjuster mentioned in step 1) includes one or more of hydrochloric acid, sulfuric acid, and sulfurous acid.
6. The method for recovering methanol and triethylamine from calcium ketoate salt formation mother liquor according to claim 5, characterized in that, The reflux ratio for the distillation process described in step 2) is 3~6:
1.
7. The method for recovering methanol and triethylamine from calcium ketoate salt formation mother liquor according to claim 6, characterized in that, The mass ratio of the evaporation residue to water in step 3) is 2~5:5~10; The amount of alkali solution used is such that the pH value of the mixed system is 13-14.
8. The method for recovering methanol and triethylamine from calcium ketoate salt formation mother liquor according to claim 7, characterized in that, The distillation temperature in step 3) is 80~95℃, and the time is 2~4 h.
9. A method for recovering methanol and triethylamine from calcium ketoate salt formation mother liquor according to claim 7 or 8, characterized in that, The alkaline solution mentioned in step 3) includes one or more of sodium hydroxide, potassium hydroxide, and sodium carbonate.