Device and method for refining and purifying industrial-grade epsilon-caprolactone
By controlling the temperature and rate parameters during falling film crystallization, the problem of insufficient ε-caprolactone purity in the prior art is solved, and efficient and low-cost high-purity ε-caprolactone preparation is achieved, improving the quality and stability of downstream products.
Patent Information
- Application Number
- CN202510445474.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-10
- Publication Date
- 2025-07-11
AI Technical Summary
The prior art is difficult to efficiently obtain high-purity ε-caprolactone, resulting in poor quality and stability of downstream products, limiting its application in high-end fields.
By using the falling film crystallization technology, by controlling parameters such as crystallization temperature, cooling rate, sweating temperature and heating rate, a single falling film crystallization can achieve the index of high-quality ε-caprolactone, including purity ≥99.99w%, acid value ≤0.05mgKOH/g, moisture content ≤0.01w%, and chromaticity ≤5Hazen units.
It has achieved efficient and low-cost acquisition of high-purity ε-caprolactone, which has improved the quality and stability of downstream products and expanded its application potential in high-end fields.
Smart Images
Figure CN120285606A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of chemical engineering, and particularly to an apparatus and a method for refining and purifying industrial-grade ε-caprolactone. Background Art
[0002] ε-Caprolactone is a cyclic ester monomer with good reactivity and plastic compatibility, and is usually used as a solvent or a reactive monomer. Ring-opening polymerization of ε-caprolactone can obtain polymers such as polycaprolactone polyol, polyether ester copolymer, and high molecular weight polycaprolactone. These polymers have excellent biocompatibility, biodegradability, good hydrolysis resistance, weather resistance, and low-temperature flexibility, and are widely used in new energy vehicles, medical devices, biodegradable products, superfine leather and other fields.
[0003] The preparation of ε-caprolactone usually adopts the cyclohexanone oxidation method. First, hydrogen peroxide reacts with a short-chain organic acid to prepare peroxyacid, and then ε-caprolactone is prepared by oxidizing cyclohexanone with peroxyacid. Due to the high risk and technical difficulty of its process, only four enterprises in the world have achieved industrial production of ε-caprolactone, namely 55,000 tons / year of China Julen New Materials, 40,000 tons / year of the United States Invista, 10,000 tons / year of Japan Daicel, and 3,000 tons / year of Germany BASF. At present, the market is mainly supplied with industrial-grade ε-caprolactone.
[0004] The main control indexes of industrial-grade ε-caprolactone are as follows: caprolactone content requirement (mass fraction w / %): ≥99.5; acid value requirement (calculated as KOH, mg / g): ≤0.50; moisture requirement (mass fraction w / %): ≤0.050; chromaticity requirement (platinum-cobalt color number, Hazen unit): ≤20. Although it can be used to prepare polycaprolactone, the quality stability of the polymer is poor. Therefore, further improving the quality of ε-caprolactone is an urgent problem to be solved at present.
[0005] At present, the purification methods for ε-caprolactone are usually rectification purification and melt crystallization purification. Rectification purification is generally applicable to the purification of low-purity caprolactone. The purity of caprolactone obtained by rectification purification is often lower than 99.90w%, and it is difficult to obtain high-purity caprolactone. The quality and stability of downstream products prepared from this level of caprolactone are poor. For example, when preparing polyurethane, problems such as unstable reaction activity, abnormal mechanical properties of products, and decreased hydrolysis resistance will occur, which limits the application of caprolactone in high-end fields.
[0006] As a separation technology that achieves separation and purification based on the different freezing points of different substances, the melt crystallization technology has the characteristics of low energy consumption, low-temperature operation, environmental friendliness, and obtaining high-purity products. As an efficient, low-energy, and low-pollution separation technology, the melt crystallization technology has attracted much attention and is particularly suitable for separating azeotropic systems, thermosensitive systems, and isomer systems. Compared with traditional separation technologies such as distillation and extraction, the advantage of melt crystallization is its good selectivity, low energy consumption, and good operating conditions.
[0007] Melt crystallization is generally divided into film crystallization (falling film crystallization) and static melt crystallization. Film crystallization has the characteristics of fast growth rate, no fouling, easy solid-liquid separation, and easy device scaling. However, during the falling film crystallization process, the mother liquor carrying impurities will impregnate, wash, and crystallize the crystal layer, and impurity components are easily wrapped and retained in the crystal layer. To achieve the target purity, it is usually necessary to repeatedly melt and recrystallize the purified liquid for purification. Static melt crystallization has the characteristics of simple device, low complexity of the process flow, and high product purity, but has disadvantages such as long processing cycle and small single processing capacity.
[0008] Patent CN114377422A discloses a purification device for polymer-grade ε-caprolactone, including a distillation column, a dividing wall column, a static crystallizer, a raw material tank, a crude product tank, a finished product storage tank, and a residue tank. This patent uses the static crystallizer technology, and the purification efficiency is low. At the same time, this patent needs to be used in combination with a caprolactone production and refining system, and the cost investment is too large. It is difficult for enterprises without a supporting caprolactone production line to further purify ε-caprolactone. At the same time, when using a static crystallizer for melt crystallization, the melt crystallization cycle is long and the purification efficiency is low. Summary of the Invention
[0009] To solve the above technical problems, the present invention proposes a device and method for refining and purifying industrial-grade ε-caprolactone.
[0010] The object of the present invention is achieved by the following technical solutions:
[0011] A method for refining and purifying industrial-grade ε-caprolactone includes the following steps:
[0012] Step 1: Transport the industrial-grade ε-caprolactone in the raw material tank (V1001) to the falling film crystallizer (C101); and circulate the material at the discharge port of the falling film crystallizer (C101) to the inside of the falling film crystallizer (C101) through a material circulation pump.
[0013] Step 2: Lower the temperature of the falling film crystallizer to the crystallization starting temperature, and then lower the temperature to the crystallization end temperature at a rate of 0.03 - 0.06 °C / min. When the crystallization end temperature is reached and the residual liquid volume is 7 - 10% of the industrial grade ε-caprolactone, the material circulation pump stops the material circulation, and the uncrystallized residual liquid is transported to the residual liquid tank (V1002).
[0014] Step 3: Heat up the falling film crystallizer at a rate of 0.02 - 0.05 °C / min. After the temperature in the crystallizer rises to -2.0 ± 0.1 to -0.5 ± 0.1 °C, stop heating. At this time, sweating is completed, and the sweat is transported to the sweat tank (V1003).
[0015] Step 4: Raise the temperature of the material in the crystallizer to 10 ± 2 °C to melt all the remaining crystals. After the crystals are completely melted, transport the melt to the product tank (V1004) to obtain refined and purified caprolactone.
[0016] For further improvement, it also includes Step 5. The residual liquid in the residual liquid tank V1002 is transported to the falling film crystallizer C101, and Steps 2 to 4 are cycled.
[0017] For further improvement, the solution in the sweat tank V1003 and the next batch of industrial grade ε-caprolactone to be purified are jointly input into the falling film crystallizer C101.
[0018] For further improvement, in Step 2, the crystallization starting temperature is -1.5 ± 0.1 to -0.5 ± 0.1 °C, and the crystallization end temperature is -21.0 ± 0.1 to -13.0 ± 0.1 °C.
[0019] For further improvement, in Step 1, detect the middle and heavy component content and light component content of the industrial grade ε-caprolactone, and determine the crystallization starting temperature, crystallization end temperature, and sweating end temperature according to the middle and heavy component content and light component content of the industrial grade ε-caprolactone:
[0020]
[0021]
[0022] A device for refining and purifying industrial grade ε-caprolactone for implementing the above method for refining and purifying industrial grade ε-caprolactone includes a raw material tank V1001. The raw material tank V1001 is connected to the feed inlet of the falling film crystallizer C101 through a raw material pump; the discharge outlet of the falling film crystallizer C101 is respectively connected to the sweat tank V1003, the product tank V1004, and the residual liquid tank V1002 through a discharge pump and is connected to the feed inlet of the falling film crystallizer C101 through a material circulation pump; the residual liquid tank V1002 is connected to the feed inlet of the falling film crystallizer C101 through a residual liquid pump, and the sweat tank V1003 is connected to the raw material tank V1001 through a sweat pump.
[0023] The beneficial effects of the present invention are as follows:
[0024] The present invention refines and purifies industrial-grade ε-caprolactone by means of falling film crystallization. According to the impurity composition and content (such as light components and heavy components) in the industrial-grade ε-caprolactone raw material, the crystallization temperature, cooling rate, sweating temperature, heating rate and residual liquid quality in the melting crystallization process are controlled. Through a single falling film crystallization, the product index requirements of high-quality ε-caprolactone can be achieved. The indexes are as follows: caprolactone purity ≥ 99.99 w%, acid value ≤ 0.05 mgKOH / g, moisture content ≤ 0.01 w%, and chromaticity ≤ 5 Hazen units. Description of the Drawings
[0025] The present invention will be further described with reference to the accompanying drawings, but the content in the drawings does not constitute any limitation to the present invention.
[0026] Figure 1 It is a schematic structural diagram of the present invention. Detailed Embodiments
[0027] In order to make the objectives, technical solutions and advantages of the invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and examples.
[0028] Example 1
[0029] The acid value, purity and chromaticity in the present invention are all tested by the HG / T 5618 test method.
[0030] The specific embodiments are as follows
[0031] Example One
[0032] ε-caprolactone with a purity of 99.733 w%, a light component content of 0.242 w%, a heavy component content of 0.025 w%, an acid value of 0.41 mgKOH / g, a water content of 0.033 w%, and a chromaticity of 15 HAzen units in the raw material tank V1001 is transported from the raw material tank V101 to the falling film crystallizer C101. After the temperature of the falling film crystallizer is lowered to -0.5 ± 0.1 °C by the refrigerant, the material circulation pump is started to circulate and transport the uncrystallized caprolactone for falling film crystallization. The cooling rate is controlled at 0.03 °C / min to cool the falling film crystallizer. When the temperature of the falling film crystallizer drops to -21.0 ± 0.1 °C, the material circulation pump is turned off, the crystallization is stopped, and the uncrystallized residual liquid is transported to the residual liquid tank V1002. At this time, the residual liquid content accounts for about 7% of the initial ε-caprolactone mass.
[0033] After discharging the uncrystallized residual liquid completely, slowly raise the temperature of the crystallizer by means of the heating medium for sweating, controlling the heating rate at 0.02 °C / min. When the temperature of the crystallizer reaches -0.5 ± 0.1 °C, stop sweating and transfer the sweat to the sweat tank V1003. At this time, the sweat content accounts for about 4% of the initial mass of ε-caprolactone.
[0034] After discharging the sweat completely, quickly raise the temperature of the falling film crystallizer to 10 ± 2 °C. After the crystals have completely melted, transfer the molten ε-caprolactone to the product tank V1004 to obtain high-purity ε-caprolactone.
[0035] After testing, the indicators of high-purity ε-caprolactone are as follows:
[0036] The purity is 99.992 w%, the acid value is 0.04 mg KOH / g, the water content is 0.004 w%, and the chromaticity is 5 Hazen units.
[0037] Example 2
[0038] Transfer the ε-caprolactone with a purity of 99.902 w%, a light component content of 0.091 w%, a heavy component content of 0.007 w%, an acid value of 0.29 mg KOH / g, a water content of 0.028 w%, and a chromaticity of 15 HAzen units in the raw material tank V1001 from the raw material tank V101 to the falling film crystallizer C101. Lower the temperature of the falling film crystallizer to -1.5 ± 0.1 °C by means of the refrigerant, then start the material circulation pump to circulate and convey the uncrystallized caprolactone for falling film crystallization, controlling the cooling rate at 0.04 °C / min to cool the falling film crystallizer. When the temperature of the falling film crystallizer drops to -18.0 ± 0.1 °C, turn off the material circulation pump, stop crystallization, and transfer the uncrystallized residual liquid to the residual liquid tank V1002. At this time, the residual liquid content accounts for about 10% of the initial mass of ε-caprolactone.
[0039] After discharging the uncrystallized residual liquid completely, slowly raise the temperature of the crystallizer by means of the heating medium for sweating, controlling the heating rate at 0.04 °C / min. When the temperature of the crystallizer reaches -1.5 ± 0.1 °C, stop sweating and transfer the sweat to the sweat tank V1003. At this time, the sweat content accounts for about 4% of the initial mass of ε-caprolactone.
[0040] After discharging the sweat completely, quickly raise the temperature of the falling film crystallizer to 10 ± 2 °C. After the crystals have completely melted, transfer the molten ε-caprolactone to the product tank V1004 to obtain high-purity ε-caprolactone.
[0041] After testing, the indicators of high-purity ε-caprolactone are as follows:
[0042] The purity is 99.992 w%, the acid value is 0.05 mg KOH / g, the water content is 0.006 w%, and the chromaticity is 5 Hazen units.
[0043] Example 3
[0044] ε - caprolactone with a purity of 99.933 w%, light component content of 0.050 w%, heavy component content of 0.017 w%, acid value of 0.24 mgKOH / g, water content of 0.024 w%, and chromaticity of 10 Hazen units in the raw material tank V1001 is transported from the raw material tank V101 to the falling film crystallizer C101. After the temperature of the falling film crystallizer is reduced to -1.5 ± 0.1 °C by the refrigerant, the material circulation pump is started to circulate and transport the uncrystallized caprolactone for falling film crystallization. The cooling rate is controlled at 0.04 °C / min to cool the falling film crystallizer. When the temperature of the falling film crystallizer drops to -14.0 ± 0.1 °C, the material circulation pump is closed, crystallization stops, and the uncrystallized residual liquid is transported to the residual liquid tank V1002. At this time, the residual liquid content accounts for about 10% of the initial mass of ε - caprolactone.
[0045] After the uncrystallized residual liquid is drained completely, the crystallizer is slowly heated and sweated by the heating medium, with the heating rate controlled at 0.04 °C / min. When the crystallizer temperature reaches -1.5 ± 0.1 °C, sweating stops, and the sweat is transported to the sweat tank V1003. At this time, the sweat content accounts for about 4% of the initial mass of ε - caprolactone.
[0046] After the sweat is drained completely, the temperature of the falling film crystallizer is rapidly raised to 10 ± 2 °C. After the crystals are completely melted, the molten ε - caprolactone is transported to the finished product tank V1004 to obtain high - purity ε - caprolactone.
[0047] After testing, the indicators of high - purity ε - caprolactone are as follows:
[0048] Purity is 99.992 w%, acid value is 0.03 mgKOH / g, water content is 0.006 w%, and chromaticity is 5 Hazen units.
[0049] Example 4
[0050]
[0051] ε - Caprolactone with a purity of 99.961 w%, a light component content of 0.036 w%, a heavy component content of 0.003 w%, an acid value of 0.18 mg KOH / g, a water content of 0.013 w%, and a chromaticity of 5 Hazen units in the raw material tank V1001 is transported from the raw material tank V101 to the falling film crystallizer C101. After the temperature of the falling film crystallizer is lowered to -3.0 ± 0.1 °C by the refrigerant, the material circulation pump is started to circulate and transport the uncrystallized caprolactone for falling film crystallization. The cooling rate is controlled at 0.06 °C / min to cool the falling film crystallizer. When the temperature of the falling film crystallizer drops to -13.0 ± 0.1 °C, the material circulation pump is turned off, crystallization stops, and the uncrystallized residual liquid is transported to the residual liquid tank V1002. At this time, the residual liquid content accounts for about 8% of the initial mass of ε - caprolactone.
[0052] After the uncrystallized residual liquid is drained completely, the crystallizer is slowly heated and sweated by the heat medium, with the heating rate controlled at 0.05 °C / min. When the temperature of the crystallizer reaches -2.0 ± 0.1 °C, sweating stops, and the sweat is transported to the sweat tank V1003. At this time, the sweat content accounts for about 3% of the initial mass of ε - caprolactone.
[0053] After the sweat is drained completely, the temperature of the falling film crystallizer is rapidly raised to 10 ± 2 °C. After the crystals are completely melted, the molten ε - caprolactone is transported to the finished product tank V1004 to obtain high - purity ε - caprolactone.
[0054] After testing, the indicators of high - purity ε - caprolactone are as follows:
[0055] Purity is 99.994 w%, acid value is 0.02 mg KOH / g, water content is 0.005 w%, and chromaticity is 5 Hazen units.
[0056] Comparative Example 1
[0057] Keeping the raw materials and conditions in Example 2 unchanged, adjusting the initial crystallization temperature to -3.0 ± 0.1 °C, the final residual liquid content accounts for about 10% of the initial mass of ε - caprolactone. After sweating, the sweat content accounts for about 4% of the initial mass of ε - caprolactone.
[0058] After testing, the indicators of high - purity ε - caprolactone are as follows:
[0059] Purity is 99.972 w%, acid value is 0.11 mg KOH / g, water content is 0.012 w%, and chromaticity is 5 Hazen units.
[0060] Comparative Example 2
[0061] Keeping the raw materials and conditions in Example 2 unchanged, adjusting the final crystallization temperature to -13.0 ± 0.1 °C, the final residual liquid content accounts for about 10% of the initial mass of ε - caprolactone. At this time, the sweat content accounts for about 5% of the initial mass of ε - caprolactone.
[0062] After detection, the indicators of high-purity ε-caprolactone are as follows:
[0063] The purity is 99.963 w%, the acid value is 0.17 mg KOH / g, the water content is 0.014 w%, and the chromaticity is 10 Hazen units.
[0064] Comparative Example 3
[0065] Keep the raw materials and conditions in Example 3 unchanged, adjust the initial crystallization temperature to -0.5 ± 0.1 °C, and the final residual liquid content accounts for about 10% of the mass of the initial ε-caprolactone. At this time, the sweat content accounts for about 4% of the mass of the initial ε-caprolactone.
[0066] After detection, the indicators of high-purity ε-caprolactone are as follows:
[0067] The purity is 99.961 w%, the acid value is 0.12 mg KOH / g, the water content is 0.011 w%, and the chromaticity is 10 Hazen units.
[0068] Comparative Example 4
[0069] Keep the raw materials and conditions in Example 3 unchanged, adjust the final crystallization temperature to -21.0 ± 0.1 °C, and the final residual liquid content accounts for about 8% of the mass of the initial ε-caprolactone. At this time, the sweat content accounts for about 7% of the mass of the initial ε-caprolactone.
[0070] After detection, the indicators of high-purity ε-caprolactone are as follows:
[0071] The purity is 99.983 w%, the acid value is 0.09 mg KOH / g, the water content is 0.007 w%, and the chromaticity is 5 Hazen units.
[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.
Claims
1. A method for refining and purifying industrial-grade ε-caprolactone, characterized in that, It includes the following steps: Step 1: Transport industrial-grade ε-caprolactone in the raw material tank (V1001) to the falling film crystallizer (C101); and circulate the material at the discharge port of the falling film crystallizer (C101) back into the falling film crystallizer (C101) through the material circulation pump; Step 2: Lower the temperature of the falling film crystallizer to the crystallization starting temperature, and then lower the temperature at a rate of 0.03 - 0.06 °C / min to the crystallization end temperature. When the crystallization end temperature is reached and the residual liquid volume is 7 - 10% of the industrial-grade ε-caprolactone, stop the material circulation of the material circulation pump, and transport the uncrystallized residual liquid to the residual liquid tank (V1002); Step 3: Raise the temperature of the falling film crystallizer at a rate of 0.02 - 0.05 °C / min. After the temperature in the crystallizer rises to -2.0 ± 0.1 to -0.5 ± 0.1 °C, stop raising the temperature. At this time, sweating is completed, and the sweat is transported to the sweat tank (V1003); Step 4: Raise the temperature of the material in the crystallizer to 10 ± 2 °C to melt all the remaining crystals. After the crystals are completely melted, transport the melt to the finished product tank (V1004) to obtain refined and purified caprolactone.
2. The method for refining and purifying industrial-grade ε-caprolactone according to claim 1, characterized in that, It further includes Step 5: Transport the residual liquid in the residual liquid tank (V1002) to the falling film crystallizer (C101), and repeat Steps 2 to 4 in a cycle.
3. The method for refining and purifying industrial-grade ε-caprolactone according to claim 1, characterized in that, The solution in the sweat tank (V1003) and the next batch of industrial-grade ε-caprolactone to be purified are jointly input into the falling film crystallizer (C101).
4. The method for refining and purifying industrial-grade ε-caprolactone according to claim 1, characterized in that, In Step 2, the crystallization starting temperature is -3.0 ± 0.1 to -0.5 ± 0.1 °C, and the crystallization end temperature is -13.0 ± 0.1 to -21.0 ± 0.1 °C.
5. The method for refining and purifying industrial-grade ε-caprolactone according to claim 4, characterized in that, In Step 1, detect the content of medium and heavy components and light components in the industrial-grade ε-caprolactone, and determine the crystallization starting temperature, crystallization end temperature, and sweating end temperature according to the content of medium and heavy components and light components in the industrial-grade ε-caprolactone:
6. An apparatus for refining and purifying industrial-grade ε-caprolactone, characterized in that, A method for refining and purifying industrial-grade ε-caprolactone for implementing any one of claims 1 - 5, including a raw material tank (V1001). The raw material tank (V1001) is connected to the inlet of the falling film crystallizer (C101) through a raw material pump; the discharge port of the falling film crystallizer (C101) is respectively connected to the sweat tank (V1003), the finished product tank (V1004), and the residual liquid tank (V1002) through a discharge pump and is connected to the inlet of the falling film crystallizer (C101) through a material circulation pump; the residual liquid tank (V1002) is connected to the inlet of the falling film crystallizer (C101) through a residual liquid pump, and the sweat tank (V1003) is connected to the raw material tank (V1001) through a sweat pump.