A method for purifying dioxanone
By combining vacuum distillation and molecular sieve adsorption, the problems of difficult operation, high cost and low yield in the purification of p-dioxanone in the existing technology have been solved, and a high-purity and high-yield p-dioxanone product has been achieved, which is suitable for industrial application.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-12-02
- Publication Date
- 2026-06-02
AI Technical Summary
Existing methods for purifying dioxane have problems such as difficult operation, high cost, low yield, easy introduction of toxic substances or generation of waste, low crystallization temperature and low efficiency.
A method of vacuum distillation coupled with molecular sieve adsorption was adopted. After removing light and heavy impurities by vacuum distillation, 3A, 4A, 5A, 10X, and 13X molecular sieves were used to adsorb and remove water and impurities with similar boiling points, respectively, to achieve high-purity purification of dioxane.
It has achieved high yield and high purity of p-dioxanone product. The process is simple, energy-efficient, and low-cost, making it suitable for industrial applications.
Abstract
Description
Technical Field
[0001] This invention relates to the field of p-dioxanone separation and purification technology, and more specifically, to a method for purifying p-dioxanone by vacuum distillation coupled with molecular sieve adsorption. Background Technology
[0002] Poly(p-dioxanone) (PPDO) is an aliphatic polyether ester. Its molecular structure contains both ester and ether bonds, giving it excellent biodegradability, physical and mechanical properties, and thermal properties. It also exhibits excellent biodegradability and absorbability.
[0003] Since the preparation of p-dioxanone (PDO) monomer, there have been continuous reports on its purification. Currently, there are three main methods for purifying PDO monomer: The first method involves repeatedly dissolving the crude PDO monomer at high temperatures and recrystallizing it at low temperatures using a suitable organic solvent. European patents EP0617029A1 and EP0617029B1 disclose the specific process steps of this purification method. However, since the crystallization temperature of PDO monomer is relatively low, approximately 26°C, purification using recrystallization requires temperatures as low as -20°C or even lower, making the operation inconvenient. Furthermore, the yield of PDO monomer purified by recrystallization is very low, only about 30%. Therefore, this method of purifying PDO monomer through repeated recrystallization results in excessively high preparation costs. The second method involves repeated vacuum distillation of the PDO monomer, collecting distillate fractions within a certain boiling range under a certain vacuum. This method generally has limited purification effects on PDO monomer. Some impurities with boiling points close to PDO, such as ethylene glycol, require a high reflux ratio; otherwise, they are difficult to remove by distillation. The third method involves reacting first and then vacuum distilling. US Patent 5391707 adds benzylpyridine and pyridine as blocking agents to crude p-dioxanone to inhibit the hydroxyl groups, followed by vacuum distillation. However, the blocking agents used are not only toxic and have an unpleasant odor, but also generate a large amount of distillation waste. Similarly, Korean Patent No. 196097 uses methylene diphenyl diisocyanate (MDI) as a blocking agent and dimorpholine diethyl ether (DMDEE) as a catalyst for vacuum distillation, yielding 90 wt% p-dioxanone and a distillation yield of 99.99 wt%. Chinese Patent Publication No. CN101824023B, entitled "A Purification Method for P-dioxanone Monomer," discloses a purification method for p-dioxanone (PDO) monomer. The process involves extracting crude sodium hydroxyethoxyacetate (SHA) using a mixed solvent of water and organic solvent under stirring. After extraction, a portion of the SHA dissolved in the mixed solvent is precipitated with a precipitant, filtered, and dried to obtain purified SHA. Crude PDO monomer is then prepared from the purified SHA. The crude PDO monomer is treated by soaking it in a strong active hydrogen removal reagent at 26–50°C, followed by vacuum treatment at 26–50°C in the presence of the strong active hydrogen removal reagent, and then slowly heated to the boiling point. The purified PDO monomer is then distilled under reduced pressure. The PDO monomer purified using this invention has a high purity, exceeding 99.5%, and a high purification yield, exceeding 75%. Polymerization yields high molecular weight poly(p-dioxanone). However, this patented process involves multiple steps and requires the use of strong active hydrogen removal reagents such as calcium hydride (CaH2) and sodium hydride (NaH), which can be hazardous.CN116621808A discloses a method for purifying p-dioxanone with low water content. The method involves adding solid p-dioxanone to a reaction vessel and heating it until completely melted. Internal gas circulation is then initiated, and the material is treated with a dehydrating agent and an oxygen-scavenging agent until completely dry. The purified p-dioxanone is then obtained through one-step vacuum distillation. However, this method requires a long drying time, at least 12 hours.
[0004] RU2042672C1 discloses a method for purifying dioxane monomer, which involves distilling crude p-dioxane once or twice without a catalyst to obtain a product with a purity of 99.5-99.7%, followed by the addition of a small amount of boric acid and continued vacuum distillation to obtain p-dioxane with a purity of 99.99%. However, this method has a low yield and introduces boric acid, which is prone to side reactions at high temperatures, making the residual liquid difficult to handle.
[0005] US5,391,768 describes a method for purifying p-dioxanone using a solvent. The method involves dissolving p-dioxanone in an aliphatic ester solvent, ethyl acetate, and recrystallizing to obtain p-dioxanone with high purity. However, since p-dioxanone dissolves completely around -3°C, the crystallization temperature must be lowered to -30°C, making room temperature operation difficult and resulting in low yields.
[0006] KR100301218B1 proposes a method for purifying p-dioxanone, comprising: (a) dissolving a mixture of p-dioxanone in isopropanol to prepare a mixed solution; (b) crystallizing p-dioxanone from the mixed solution; (c) filtering to obtain p-dioxanone crystals with a higher purity than the reaction mixture; (d) repeating steps (a) to (c) recrystallization; and (e) removing isopropanol from the final product obtained in the above steps under reduced pressure and distilling to obtain high-purity p-dioxanone. This method can purify p-dioxanone to over 99.97%. However, this method also suffers from low crystallization temperature, low product yield, and requires multiple recrystallizations, resulting in low purification efficiency.
[0007] KR100567926B1 proposes a method for purifying p-dioxanone. In step (1), crude p-dioxanone is cooled and crystallized. Considering crushing and filtration, the cooling temperature of the crude p-dioxanone crystallization is about 24°C below the melting point of p-dioxanone, preferably -30 to 20°C. In step (2), the p-dioxanone crystals obtained in step (1) are crushed to a size of less than 1 cm using a grinder or extruder, and then filtered under pressure or reduced pressure. When the size of the crushed crystals is too large, it is difficult to remove impurities mixed in with the p-dioxanone crystals and it takes a lot of time. In step (3), the filtered p-dioxanone crystal particles are dried under high vacuum at 10-24°C for 1 to 50 hours. Subsequently, in step (4), the dried p-dioxanone crystals are heated in solution and then distilled under reduced pressure of 0.05 to 5 torr to obtain p-dioxanone with a high purity of 99.9%. This method requires mechanical crushing, which can easily lead to material loss, and the high vacuum conditions can easily cause blockages and high energy consumption.
[0008] KR100761001B1 provides a purification method: 1) After maintaining a mixture of p-dioxanone at 30-40°C, seed crystals are added, and the mixture is cooled to 5-15°C at a cooling rate of 0.1-5°C / min to obtain p-dioxanone crystals; 2) The p-dioxanone crystals are then heated to 20-35°C at a rate of 0.1-1°C / min to recover high-purity p-dioxanone. To ensure high-purity p-dioxanone, this method has low cooling and heating rates, long crystallization time, and does not completely remove impurities of specific components in the dioxanone crystals, requiring an additional multi-stage solution crystallization process. KR100675964B1 further employs a combination of solution crystallization-solution crystallization-vacuum distillation, resulting in an excessively long purification process, high operational difficulty, and reduced reliability. Summary of the Invention
[0009] To address the shortcomings of existing technologies, the purpose of this invention is to provide a combined purification process that employs vacuum distillation coupled with molecular sieve adsorption purification to obtain high-purity p-dioxanone products in high yield, thereby meeting the demand for high-quality p-dioxanone.
[0010] The technical solution adopted in this invention is as follows: A method for purifying p-dioxanone involves first removing light and heavy components from crude p-dioxanone through vacuum distillation. The purified p-dioxanone then enters a first adsorption column, where a first molecular sieve adsorbs and removes water. Next, it enters a second adsorption column, where a second molecular sieve adsorbs and removes impurities with similar boiling points, yielding a high-purity p-dioxanone product. The method includes the following steps: S1: The crude p-dioxanone is fed into a vacuum distillation column for vacuum distillation to remove light and heavy components from the crude product, especially to remove impurities with a large difference in boiling point from p-dioxanone, and to obtain purified p-dioxanone. S2: The purified p-dioxanone by distillation is fed into the first adsorption column to remove the water in the p-dioxanone. The first adsorption column is equipped with a first molecular sieve. S3: The dehydrated p-dioxanone is fed into the second adsorption column to remove impurities with similar boiling points from the p-dioxanone, thereby obtaining a high-purity p-dioxanone product. The second adsorber is equipped with a second molecular sieve.
[0011] In step S1, the purity of the crude dioxane is between 70% and 97%, and more preferably between 80% and 95%.
[0012] In step S1, the vacuum distillation column can be operated continuously or intermittently. The number of trays in the vacuum distillation column is 10-200, more preferably 20-100. The absolute pressure of the vacuum distillation column is 10Pa-20000Pa, more preferably 100Pa-2000Pa. The operating temperature of the vacuum distillation column is 60℃-200℃, more preferably 80℃-150℃. The reflux ratio of the vacuum distillation column is 1-50, more preferably 2-20.
[0013] In step S1, after distillation, the purity of crude dioxane is increased to 95%-99.7%, and more preferably 97%-99.5%.
[0014] The first molecular sieve is one or more of 3A molecular sieve, 4A molecular sieve, and 5A molecular sieve. The main purpose of selecting the above-mentioned small-pore molecular sieve is to remove water from p-dioxanone and prevent water from interfering with the adsorption of impurities in the second adsorption column.
[0015] The first molecular sieve used in step S2 is activated at a temperature of 100-600℃ for 2-8 hours before use.
[0016] The adsorption pressure in step S2 is 0.1-1 MPa, the adsorption temperature is 28-100℃, and the feed mass hourly space velocity (WHSV) for dioxane is 0.5-10 h⁻¹. -1 .
[0017] The second molecular sieve is one or both of 10X and 13X molecular sieves. These molecular sieves have pores with a diameter larger than that of impurity molecules in p-dioxanone. Utilizing their polarity and large pore characteristics, they can adsorb and remove impurities with boiling points close to those of p-dioxanone but different polarities.
[0018] The second molecular sieve used in step S3 is activated at a temperature of 100-600℃ for 2-8 hours before use.
[0019] The adsorption pressure in step S3 is 0.1-1 MPa, the adsorption temperature is 28-100℃, and the feed mass hourly space velocity (WHSV) for p-dioxanone is 0.5-10 h⁻¹. -1 .
[0020] In the above technical solution, in step S3, the purity of p-dioxanone is increased to 99.7% or higher, and more preferably to 99.9% or higher.
[0021] This invention combines vacuum distillation with molecular sieve adsorption purification, achieving a high yield and high purity of p-dioxanone compared to existing technologies. It features a simple separation and purification process, low energy consumption, and low cost, and has promising prospects for industrial application. Detailed Implementation
[0022] The crude p-dioxanone in all embodiments of the present invention was prepared using the method disclosed in CN1739852A.
[0023] The present invention will be further described in detail below with reference to the embodiments, but the present invention is not limited to these embodiments. Example
[0024] 1 kg of crude p-dioxanone (80% purity) was melted by heating and placed in the reboiler of a vacuum distillation column. The column was packed with packing material and had 40 equivalent trays. The reboiler was heated to 80°C, and the vacuum pump was turned on to maintain the absolute pressure of the column at 100 Pa. The temperature was then increased to continue vacuum distillation, maintaining a reflux ratio of 10:1. Vacuum distillation initially yielded 105 g of a light component. This was then transferred to a product tank, and further distillation yielded 710 g of p-dioxanone with a purity of 98.5%.
[0025] The 3A molecular sieve was activated at 120℃ for 2 hours, then heated to 550℃ at a rate of 10℃ / min, and activated at 550℃ for another 4 hours. It was then allowed to cool naturally to 120℃ and cooled to room temperature under nitrogen protection for later use.
[0026] The activated 3A molecular sieve was loaded into the first adsorption column.
[0027] The 10X molecular sieve was activated at 120℃ for 2 hours, then heated to 600℃ at a rate of 10℃ / min, and activated at that temperature for another 4 hours. It was then allowed to cool naturally to 120℃ and cooled to room temperature under nitrogen protection for later use.
[0028] The activated 10X molecular sieve was then loaded into the second adsorption column.
[0029] The first and second adsorption columns were washed with dioxane (water content less than 0.001%, purity 99.9%) to remove trace impurities such as ash from the molecular sieve.
[0030] 500g of 98.5% pure p-dioxanone obtained by distillation was fed at a mass hourly space velocity (MSV) of 2h. -1 The first and second adsorption columns were pumped sequentially, with an adsorption pressure of 0.1 MPa and an adsorption temperature of 28 °C, yielding 705 g of high-purity p-dioxanone with a purity of 99.7% and a yield of 87.86%. Example
[0031] 1 kg of crude p-dioxanone (80% purity) was melted by heating and placed in the reboiler of a vacuum distillation column. The column was packed with packing material and had 40 equivalent trays. The reboiler was heated to 80°C, and the vacuum pump was turned on to maintain the absolute pressure of the column at 100 Pa. The temperature was then increased to continue vacuum distillation, maintaining a reflux ratio of 10:1. Vacuum distillation initially yielded 110 g of a light fraction. This fraction was then transferred to a product tank and further distilled to obtain 705 g of p-dioxanone with a purity of 98.8%.
[0032] The 3A molecular sieve was activated at 120℃ for 2 hours, then heated to 550℃ at a rate of 10℃ / min, and activated at this temperature for another 4 hours. It was then allowed to cool naturally to 120℃ and cooled to room temperature under nitrogen protection for later use.
[0033] The activated 3A molecular sieve was loaded into the first adsorption column.
[0034] The 10X molecular sieve was activated at 120℃ for 2 hours, then heated to 600℃ at a rate of 10℃ / min, and activated at that temperature for another 4 hours. It was then allowed to cool naturally to 120℃ and cooled to room temperature under nitrogen protection for later use.
[0035] The activated 10X molecular sieve was then loaded into the second adsorption column.
[0036] The first and second adsorption columns were washed with dioxane (water content less than 0.001%, purity 99.9%).
[0037] 500g of 98.8% pure p-dioxanone obtained by distillation was fed at a mass hourly space velocity (MSV) of 2h. -1 The first and second adsorption columns were pumped sequentially, with an adsorption pressure of 0.1 MPa and an adsorption temperature of 28 °C, yielding 700 g of high-purity p-dioxanone with a purity of 99.8% and a yield of 87.32%. Example
[0038] 1 kg of crude p-dioxanone (85% purity) was melted by heating and placed in the reboiler of a vacuum distillation column. The column was packed with packing material and had 30 equivalent trays. The reboiler was heated to 80°C, and the vacuum pump was turned on to maintain the absolute pressure of the column at 100 Pa. The temperature was then increased to continue vacuum distillation, maintaining a reflux ratio of 15:1. Vacuum distillation initially yielded 102 g of a light component. This was then transferred to a product tank, and further distillation yielded 720 g of p-dioxanone with a purity of 99.1%.
[0039] The 4A molecular sieve was activated at 120℃ for 2 hours, then heated to 550℃ at a rate of 10℃ / min, and activated at this temperature for another 4 hours. It was then allowed to cool naturally to 120℃ and cooled to room temperature under nitrogen protection for later use.
[0040] The activated 4A molecular sieve was loaded into the first adsorption column.
[0041] The 13X molecular sieve was activated at 120℃ for 2 hours, then heated to 550℃ at a rate of 10℃ / min, and activated at this temperature for another 4 hours. It was then allowed to cool naturally to 120℃ and cooled to room temperature under nitrogen protection for later use.
[0042] The activated 13X molecular sieve was then loaded into the second adsorption column.
[0043] The first and second adsorption columns were washed with dioxane (water content less than 0.001%, purity 99.9%).
[0044] 500g of 99.1% pure p-dioxanone obtained by distillation was fed at a mass hourly space velocity (MSV) of 1 h⁻¹. -1 The first and second adsorption columns were pumped sequentially, with an adsorption pressure of 0.1 MPa and an adsorption temperature of 35 °C, yielding 715 g of high-purity p-dioxanone with a purity of 99.91% and a yield of 87.86%. Example
[0045] 1 kg of crude p-dioxanone (85% purity) was melted by heating and placed in the reboiler of a vacuum distillation column. The column was packed with packing material and had 30 equivalent trays. The reboiler was heated to 80°C, and the vacuum pump was turned on to maintain the absolute pressure of the column at 100 Pa. The temperature was then increased to continue vacuum distillation, maintaining a reflux ratio of 15:1. Vacuum distillation initially yielded 108 g of a light fraction. This fraction was then transferred to a product tank and further distilled to obtain 715 g of p-dioxanone with a purity of 99.2%.
[0046] The 4A molecular sieve was activated at 120℃ for 2 hours, then heated to 550℃ at a rate of 10℃ / min, and activated at this temperature for another 4 hours. It was then allowed to cool naturally to 120℃ and cooled to room temperature under nitrogen protection for later use.
[0047] The activated 4A molecular sieve was loaded into the first adsorption column.
[0048] The 13X molecular sieve was activated at 120℃ for 2 hours, then heated to 550℃ at a rate of 10℃ / min, and activated at this temperature for another 4 hours. It was then allowed to cool naturally to 120℃ and cooled to room temperature under nitrogen protection for later use.
[0049] The activated 13X molecular sieve was then loaded into the second adsorption column.
[0050] The first and second adsorption columns were washed with dioxane (water content less than 0.001%, purity 99.9%).
[0051] 500g of 99.2% pure p-dioxanone obtained by distillation was fed at a mass hourly space velocity (MSV) of 1 h⁻¹. -1 The first and second adsorption columns were pumped sequentially, with an adsorption pressure of 0.1 MPa and an adsorption temperature of 40 °C, yielding 710 g of high-purity p-dioxanone with a purity of 99.93% and a yield of 83.47%. Example
[0052] 1 kg of crude p-dioxanone (90% purity) was melted by heating and placed in the reboiler of a vacuum distillation column. The column was packed with packing material and had 20 equivalent trays. The reboiler was heated to 80°C, and the vacuum pump was turned on to maintain the absolute pressure of the column at 100 Pa. The temperature was then increased to continue vacuum distillation, maintaining a reflux ratio of 20:1. Vacuum distillation initially yielded 98 g of a light component. This was then transferred to a product tank, and further distillation yielded 730 g of p-dioxanone with a purity of 99.2%.
[0053] The 5A molecular sieve was activated at 120℃ for 2 hours, then heated to 550℃ at a rate of 10℃ / min, and activated at this temperature for another 4 hours. It was then allowed to cool naturally to 120℃ and cooled to room temperature under nitrogen protection for later use.
[0054] The activated 5A molecular sieve was loaded into the first adsorption column.
[0055] Equal portions of 10X and 13X molecular sieves were activated at 120℃ for 2 hours, then heated to 550℃ at a rate of 10℃ / min, and activated at this temperature for another 4 hours. The mixture was then allowed to cool naturally to 120℃ and cooled to room temperature under nitrogen protection for later use.
[0056] The activated equal portions of 10X and 13X molecular sieves were loaded into the second adsorption column.
[0057] The first and second adsorption columns were washed with dioxane (water content less than 0.001%, purity 99.9%).
[0058] 500g of 99.2% pure p-dioxanone obtained by distillation was fed at a mass hourly space velocity (MSV) of 1 h⁻¹. -1 The first and second adsorption columns were pumped sequentially, with an adsorption pressure of 0.1 MPa and an adsorption temperature of 45 °C, yielding 725 g of high-purity p-dioxanone with a purity of 99.94% and a yield of 80.5%. Example
[0059] 1 kg of crude p-dioxanone (90% purity) was melted and placed in the reboiler of a vacuum distillation column. The column was packed with packing material and had 20 equivalent trays. The reboiler was heated to 80°C, and the vacuum pump was turned on to maintain the absolute pressure of the column at 100 Pa. The temperature was then increased to continue vacuum distillation, maintaining a reflux ratio of 20:1. Vacuum distillation initially yielded 110 g of a light fraction. This fraction was then transferred to a product tank and further distilled to obtain 720 g of p-dioxanone with a purity of 99.3%.
[0060] The 5A molecular sieve was activated at 120℃ for 2 hours, then heated to 550℃ at a rate of 10℃ / min, and activated at this temperature for another 4 hours. It was then allowed to cool naturally to 120℃ and cooled to room temperature under nitrogen protection for later use.
[0061] The activated 5A molecular sieve was loaded into the first adsorption column.
[0062] Equal portions of 10X and 13X molecular sieves were activated at 120℃ for 2 hours, then heated to 550℃ at a rate of 10℃ / min, and activated at this temperature for another 4 hours. The mixture was then allowed to cool naturally to 120℃ and cooled to room temperature under nitrogen protection for later use.
[0063] The activated equal portions of 10X and 13X molecular sieves were loaded into the second adsorption column.
[0064] The first and second adsorption columns were washed with dioxane (water content less than 0.001%, purity 99.9%).
[0065] 500g of 99.3% pure p-dioxanone obtained by distillation was fed at a mass hourly space velocity (MSH) of 0.5 h⁻¹. -1 The first and second adsorption columns were pumped sequentially, with an adsorption pressure of 0.1 MPa and an adsorption temperature of 50 °C, yielding 715 g of high-purity p-dioxanone with a purity of 99.95% and a yield of 79.4%. Example
[0066] 1 kg of crude p-dioxanone (80% purity) was melted by heating and placed in the reboiler of a vacuum distillation column. The column was packed with packing material and had 100 equivalent trays. The reboiler was heated to 200°C, and the vacuum pump was turned on to maintain the absolute pressure of the column at 5000 Pa. The temperature was then increased to continue vacuum distillation, maintaining a reflux ratio of 2:1. Vacuum distillation initially yielded 110 g of a light component. This was then transferred to a product tank, and further distillation yielded 720 g of p-dioxanone with a purity of 99.1%.
[0067] The 3A molecular sieve was activated at 100℃ for 2 hours, then heated to 600℃ at a rate of 25℃ / min, and activated at this temperature for another 6 hours. It was then allowed to cool naturally to 120℃ and cooled to room temperature under nitrogen protection for later use.
[0068] The activated 3A molecular sieve was loaded into the first adsorption column.
[0069] The 10X molecular sieve was activated at 120℃ for 2 hours and then cooled to room temperature under nitrogen protection for later use.
[0070] The activated 10X molecular sieve was then loaded into the second adsorption column.
[0071] The first and second adsorption columns were washed with dioxane (water content less than 0.001%, purity 99.9%).
[0072] 500g of 99.1% pure p-dioxanone obtained by distillation was fed at a mass hourly space velocity (MSH) of 0.5 h⁻¹. -1 The first and second adsorption columns were pumped sequentially, with an adsorption pressure of 0.1 MPa and an adsorption temperature of 65 °C, yielding 715 g of high-purity p-dioxanone with a purity of 99.9% and a yield of 89.29%. Example
[0073] 1 kg of crude p-dioxanone (80% purity) was melted and placed in the reboiler of a vacuum distillation column. The column was packed with packing material and had 60 equivalent trays. The reboiler was heated to 150°C, and the vacuum pump was turned on to maintain the absolute pressure of the column at 2500 Pa. The temperature was increased further for vacuum distillation, with the reflux ratio maintained at 5:1. The vacuum distillation initially yielded 110 g of a light fraction. This fraction was then transferred to a product tank and further distilled to obtain 720 g of p-dioxanone with a purity of 99.2%.
[0074] The 3A molecular sieve was activated at 100℃ for 2 hours, then heated to 600℃ at a rate of 20℃ / min, and activated at this temperature for another 6 hours. It was then allowed to cool naturally to 120℃ and cooled to room temperature under nitrogen protection for later use.
[0075] The activated 3A molecular sieve was loaded into the first adsorption column.
[0076] The 13X molecular sieve was activated at 100℃ for 8 hours and then cooled to room temperature under nitrogen protection for later use.
[0077] The activated 13X molecular sieve was then loaded into the second adsorption column.
[0078] The first and second adsorption columns were washed with dioxane (water content less than 0.001%, purity 99.9%).
[0079] 500g of 99.2% pure p-dioxanone obtained by distillation was fed at a mass hourly space velocity (MSV) of 10 h⁻¹. -1 The first and second adsorption columns were pumped sequentially, with an adsorption pressure of 1 MPa and an adsorption temperature of 100 °C, yielding 715 g of high-purity p-dioxanone with a purity of 99.7% and a yield of 89.11%. Example
[0080] 1 kg of crude p-dioxanone (80% purity) was melted and placed in the reboiler of a vacuum distillation column. The column was packed with packing material and had 60 equivalent trays. The reboiler was heated to 150°C, and the vacuum pump was turned on to maintain the absolute pressure of the column at 2500 Pa. The temperature was increased further for vacuum distillation, with the reflux ratio maintained at 5:1. The vacuum distillation initially yielded 110 g of a light fraction. This fraction was then transferred to a product tank and further distilled to obtain 720 g of p-dioxanone with a purity of 99.2%.
[0081] The 3A molecular sieve was activated at 100℃ for 2 hours, then heated to 600℃ at a rate of 20℃ / min, and activated at this temperature for another 6 hours. It was then allowed to cool naturally to 120℃ and cooled to room temperature under nitrogen protection for later use.
[0082] The activated 3A molecular sieve was loaded into the first adsorption column.
[0083] The 13X molecular sieve was activated at 100℃ for 8 hours and then cooled to room temperature under nitrogen protection for later use.
[0084] The activated 13X molecular sieve was then loaded into the second adsorption column.
[0085] The first and second adsorption columns were washed with 99.9% p-dioxanone with a water content of less than 0.001%.
[0086] 500g of 99.2% pure p-dioxanone obtained by distillation was fed at a mass hourly space velocity (MSV) of 5h. -1 The first and second adsorption columns were pumped sequentially, with an adsorption pressure of 0.5 MPa and an adsorption temperature of 100 °C, yielding 715 g of high-purity p-dioxanone with a purity of 99.8% and a yield of 89.2%.
Claims
1. A method for purifying dioxane, characterized in that, Includes the following steps: S1: The crude p-dioxanone is fed into a vacuum distillation column for vacuum distillation to remove light and heavy components from the crude product, thereby obtaining purified p-dioxanone. S2: The purified p-dioxanone by distillation is fed into the first adsorption column to remove the water in the p-dioxanone. The first adsorption column is equipped with a first molecular sieve. S3: The dehydrated p-dioxanone is fed into the second adsorption column to remove impurities with similar boiling points to p-dioxanone, thus obtaining a high-purity p-dioxanone product; the second adsorber is equipped with a second molecular sieve.
2. The purification method for dioxane according to claim 1, characterized in that, In step S1, the purity of the crude dioxane is between 70% and 97%, and more preferably between 80% and 95%.
3. The purification method for dioxane according to claim 1, characterized in that, In step S1, the vacuum distillation column is operated continuously or intermittently. The number of trays in the vacuum distillation column is 20-100, the absolute pressure of the vacuum distillation column is 100Pa-5000Pa, the operating temperature of the vacuum distillation column is 80℃-200℃, and the reflux ratio of the vacuum distillation column is 2-20.
4. The purification method for dioxane according to claim 1, characterized in that, After distillation in step S1, the purity of crude dioxane is increased to 95%-99.7%, and more preferably to 97%-99.5%.
5. The purification method for dioxanone according to claim 1, characterized in that, The first molecular sieve is one or more of 3A molecular sieve, 4A molecular sieve, and 5A molecular sieve.
6. The purification method for dioxane according to claim 1, characterized in that, The first molecular sieve used in step S2 is activated at a temperature of 100-600°C for 2-8 hours before use.
7. The purification method for dioxane according to claim 1, characterized in that, The adsorption pressure in step S2 is 0.1-1 MPa, the adsorption temperature is 28-100℃, and the feed mass hourly space velocity (WHSV) for p-dioxanone is 0.5-10 h⁻¹. -1 .
8. The method for purifying dioxane according to claim 1, characterized in that, The second molecular sieve is one or both of 10X molecular sieve and 13X molecular sieve.
9. The method for purifying dioxane according to claim 1, characterized in that, The second molecular sieve used in step S3 is activated at a temperature of 100-600°C for 2-8 hours before use.
10. The method for purifying dioxane according to claim 1, characterized in that, The adsorption pressure in step S3 is 0.1-1 MPa, the adsorption temperature is 28-100℃, and the feed mass hourly space velocity (WHSV) for p-dioxanone is 0.5-10 h⁻¹. -1 .