Purification method of propylene glycol methyl ether acetate

Abstract

The invention provides a purification method of propylene glycol methyl ether acetate, and belongs to the technical field of refining and purification. The purification method of propylene glycol methyl ether acetate comprises the following steps: 1) carrying out metal removal treatment on industrial-grade propylene glycol methyl ether acetate in a metal ion adsorption column to obtain propylene glycol methyl ether acetate after metal removal; 2) transferring the demetalized propylene glycol methyl ether acetate into a light component removal rectifying tower for light component removal to obtain light component removed propylene glycol methyl ether acetate; 3) transferring the propylene glycol methyl ether acetate subjected to light component removal into a heavy component removal rectifying tower for heavy component removal to obtain propylene glycol methyl ether acetate subjected to heavy component removal; and 4) filtering the propylene glycol methyl ether acetate subjected to heavy component removal to obtain the high-purity propylene glycol methyl ether acetate. The propylene glycol methyl ether acetate obtained by the method provided by the invention is high in purity, simple in operation process and suitable for industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of refining and purification, and particularly relates to a purification method for propylene glycol methyl ether acetate. Background Art

[0002] Propylene glycol methyl ether acetate (PGMEA) is an important organic solvent. Due to its excellent solubility, low toxicity, and good volatility, it is often used as a solvent for photoresist to help form fine circuit patterns, and can also be used as an efficient solvent to remove residues and impurities generated during the manufacturing process. It can also be used in the production of pharmaceutical preparations and pharmaceutical intermediates, and is widely used in high-end chemical fields such as the semiconductor, liquid crystal display, and pharmaceutical industries.

[0003] With the rapid development of the electronics industry, the purity requirements for PGMEA are getting higher and higher, especially the control of metal ions, moisture, acidity, and impurity content has become a key technical difficulty. In the prior art, the purification methods of PGMEA are difficult to simultaneously meet the ultra-low content requirements of metal ions, moisture, acidity, and various impurities, resulting in limited applications of the product in high-end fields.

[0004] Patent CN 110305012 A discloses a synthesis process for semiconductor-grade propylene glycol methyl ether acetate. Propylene glycol methyl ether and acetic acid are mixed in proportion and then fed into the reactor. A catalyst is added, and the reaction solution is heated. The reaction is carried out under stirring to generate propylene glycol methyl ether acetate. The generated propylene glycol methyl ether acetate is purified by two-stage distillation, then subjected to decolorization treatment and sampled for purity detection. Chelating resin is used to adsorb trace metal ions in propylene glycol methyl ether acetate. Although the metal ion content can be controlled within 1 ppb, this production method has the disadvantages of high cost, complex operation, and high energy consumption. Summary of the Invention

[0005] The present invention provides a purification method for propylene glycol methyl ether acetate. The propylene glycol methyl ether acetate obtained by the method of the present invention has high purity, and the operation process is simple and suitable for industrial production.

[0006] To achieve the above object, the present invention provides a purification method for propylene glycol methyl ether acetate, comprising the following steps:

[0007] 1) Performing metal removal treatment on industrial-grade propylene glycol methyl ether acetate in a metal ion adsorption column to obtain metal-removed propylene glycol methyl ether acetate;

[0008] 2) Transferring the metal-removed propylene glycol methyl ether acetate to a light component removal distillation column for light component removal to obtain light component-removed propylene glycol methyl ether acetate;

[0009] 3) Transferring the light component-removed propylene glycol methyl ether acetate to a heavy component removal distillation column for heavy component removal to obtain heavy component-removed propylene glycol methyl ether acetate;

[0010] 4) Filter the propylene glycol methyl ether acetate after removing heavy components to obtain high-purity propylene glycol methyl ether acetate.

[0011] Preferably, the purity of the industrial-grade propylene glycol methyl ether acetate in step 1) is ≧99 wt%, the single metal ion is ≦10 ppb, and the total metal ion is ≦100 ppb.

[0012] Preferably, the material of the metal ion adsorption column in step 1) is S316, and the adsorption packing is ion exchange resin.

[0013] Preferably, when performing metal removal treatment in step 1), the design pressure is -0.1 to 0.6 MPa, the design temperature is 500 °C, and the operating temperature is 300 to 400 °C.

[0014] Preferably, the number of theoretical plates of the light component removal distillation column in step 2) is 18 to 25. When removing light components, the pressure inside the light component removal distillation column is 1.0 to 1.5 KPa, the bottom temperature is 70 to 90 °C, and the reflux ratio is 5 to 20:1.

[0015] Preferably, the number of theoretical plates of the heavy component removal distillation column in step 3) is 22 to 28. When removing heavy components, the pressure inside the heavy component removal distillation column is 0.5 to 1.0 KPa, the bottom temperature is 80 to 100 °C, and the reflux ratio is 2 to 7:1.

[0016] Preferably, the diameter of the light component removal distillation column is DN40, the height is 2.5 m, the material is S316, and the packing specification is 3×3 mm θ ring;

[0017] The diameter of the heavy component removal distillation column is DN40, the height is 2.5 m, the material is S316, and the packing specification is 3×3 mm θ ring.

[0018] Preferably, when filtering in step 4), the material of the filter is PFA, and the filter diameter is 30 to 70 nm.

[0019] Preferably, in step 1), a feed pump is used to pump propylene glycol methyl ether acetate into the metal ion adsorption column. The pump head material of the feed pump is 316L, and the grade is EP.

[0020] Preferably, in the high-purity propylene glycol methyl ether acetate obtained in step 4), the single metal ion is ≦10 ppt, the total metal ion is ≦49 ppt, the moisture is ≦30 ppm, the acidity is ≦30 ppm, the purity is ≧99.99 wt%, the content of 2-methoxy-1-propyl acetate is ≦5 ppm, and the acetic acid content is ≦0.1 ppm.

[0021] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0022] The purification method provided by the present invention applies metal ion adsorption to the purification process of propylene glycol methyl ether acetate, and further combines light component removal, heavy component removal by distillation, and filtration for impurity removal. The steps cooperate with each other to achieve a good impurity removal effect, enabling the single metal ion in the purified propylene glycol methyl ether acetate to be ≤ 10 ppt, the total metal ion to be ≤ 49 ppt, the water content to be ≤ 30 ppm, the acidity to be ≤ 30 ppm, the purity to be ≥ 99.99 wt%, the content of 2-methoxy-1-propyl acetate to be ≤ 5 ppm, and the acetic acid content to be ≤ 0.1 ppm.

[0023] The purification method provided by the present invention has a simple operation process, a continuous and efficient production process, easy-to-control conditions, stable production and high efficiency, and is very suitable for large-scale industrial applications. Specific Embodiments

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] The present invention provides a purification method for propylene glycol methyl ether acetate, which includes the following steps:

[0026] 1) Performing metal removal treatment on industrial-grade propylene glycol methyl ether acetate in a metal ion adsorption column to obtain metal-removed propylene glycol methyl ether acetate;

[0027] 2) Transferring the metal-removed propylene glycol methyl ether acetate to a light component removal distillation column for light component removal to obtain light component-removed propylene glycol methyl ether acetate;

[0028] 3) Transferring the light component-removed propylene glycol methyl ether acetate to a heavy component removal distillation column for heavy component removal to obtain heavy component-removed propylene glycol methyl ether acetate;

[0029] 4) Filtering the heavy component-removed propylene glycol methyl ether acetate to obtain high-purity propylene glycol methyl ether acetate.

[0030] The present invention performs a metal removal treatment on industrial-grade propylene glycol methyl ether acetate in a metal ion adsorption column to obtain metal-removed propylene glycol methyl ether acetate. In the present invention, the purity of the industrial-grade propylene glycol methyl ether acetate is preferably ≥ 99 wt%, the single metal ion is preferably ≤ 10 ppb, and the total metal ions are preferably ≤ 100 ppb. The present invention has no special limitation on the source of the industrial-grade propylene glycol methyl ether acetate, and conventional commercially available products in the art can be used. In the present invention, the material of the metal ion adsorption column is preferably S316, and the adsorption filler is preferably an ion exchange resin, more preferably a polished resin. The resin used in the examples of the present invention is an ultra-pure water anion-cation mixed resin of model SNT / 18. In the present invention, the design pressure during the metal removal treatment is preferably -0.1 to 0.6 MPa, the design temperature is preferably 500 °C, and the operating temperature is preferably 300 to 400 °C. In the present invention, it is preferred to use a feed pump to pump the propylene glycol methyl ether acetate into the metal ion adsorption column. The pump head material of the feed pump is 316L, and the grade is EP. In the present invention, using the pump head of the above material can avoid product contamination by metal ions or particles, reduce the risks of corrosion and wear, reduce the equipment maintenance frequency, and meet the stringent requirements of industries such as semiconductors (SEMI F20) and pharmaceuticals (USP Class VI) for high-purity fluid equipment.

[0031] To obtain the metal-removed propylene glycol methyl ether acetate, the present invention transfers the metal-removed propylene glycol methyl ether acetate to a light component removal distillation column for light component removal to obtain light component-removed propylene glycol methyl ether acetate. In the present invention, the number of theoretical plates of the light component removal distillation column is preferably 18 to 25. When performing light component removal, the column pressure in the light component removal distillation column is preferably 1.0 to 1.5 KPa, the bottom temperature is preferably 70 to 90 °C, and the reflux ratio is preferably 5 to 20:1. In the present invention, setting the number of theoretical plates, reflux ratio, etc. within the above ranges can perform light component removal more fully on the basis of minimizing energy consumption. In the present invention, the column diameter of the light component removal distillation column is preferably DN40, the column height is preferably 2.5 m, the material is preferably S316, and the packing specification is preferably 3 × 3 mm θ rings. In the present invention, impurities such as water and methanol in the propylene glycol methyl ether acetate can be removed by light component removal distillation.

[0032] After obtaining the propylene glycol methyl ether acetate with light components removed, the present invention transfers the propylene glycol methyl ether acetate with light components removed into a heavy component removal rectification column for heavy component removal, thereby obtaining the propylene glycol methyl ether acetate after heavy component removal. In the present invention, the number of theoretical plates of the heavy component removal rectification column is preferably 22 - 28. When performing heavy component removal, the pressure inside the heavy component removal rectification column is preferably 0.5 - 1.0 KPa, the bottom temperature is preferably 80 - 100 °C, and the reflux ratio is preferably 2 - 7:1. In the present invention, setting the number of theoretical plates, reflux ratio, etc. within the above ranges can more fully perform heavy component removal on the basis of minimizing energy consumption. In the present invention, the column diameter of the heavy component removal rectification column is preferably DN40, the column height is preferably 2.5 m, the material is preferably S316, and the packing specification is preferably 3×3 mm θ ring. In the present invention, impurities such as 2-methoxy-1-propyl acetate and acetic acid in the propylene glycol methyl ether acetate can be removed through heavy component removal rectification.

[0033] After obtaining the propylene glycol methyl ether acetate after heavy component removal, the present invention filters the propylene glycol methyl ether acetate after heavy component removal to obtain high-purity propylene glycol methyl ether acetate. In the present invention, when performing filtration, the material of the filter is preferably PFA (perfluoroalkoxy alkane), and the filter pore size is preferably 30 - 70 nm, more preferably 50 nm. In the present invention, a filter made of PFA material is used because it does not contain metal components (such as Fe, Cr, Ni in stainless steel) itself, and no stabilizer or plasticizer needs to be added during the processing, ensuring that the leaching amount of trace metal ions is extremely low (can reach below the ppb level), meeting the stringent requirements for reagent purity in the semiconductor industry (such as SEMI C12 standard).

[0034] The purification method provided by the present invention first adsorbs and removes impurities from industrial-grade propylene glycol methyl ether acetate through a metal ion adsorption column. During this process, trace metal ions in the industrial-grade propylene glycol methyl ether acetate can be adsorbed and removed. The propylene glycol methyl ether acetate after metal adsorption is then successively passed through a light component removal rectification column and a heavy component removal rectification column, where water, methanol and other impurities can be removed by light component removal first, and 2-methoxy-1-propyl acetate, acetic acid and other impurities can be removed by heavy component removal. The propylene glycol methyl ether acetate after heavy component removal is filtered again to remove some residual metal ions, as well as organic substances and particles. The present invention applies metal ion adsorption to the purification process of propylene glycol methyl ether acetate, and further combines light component removal, heavy component removal rectification and filtration to remove impurities. The synergistic effect among various steps achieves a good impurity removal effect, and high-purity propylene glycol methyl ether acetate can be purified and prepared. In the obtained high-purity propylene glycol methyl ether acetate, the single metal ion content is ≤10 ppt, the total metal ion content is ≤49 ppt, the water content is ≤30 ppm, the acidity is ≤30 ppm, the purity is ≥99.99 wt%, the content of 2-methoxy-1-propyl acetate is ≤5 ppm, and the acetic acid content is ≤0.1 ppm. Moreover, the production cost is relatively low. At the same time, using this device to purify propylene glycol methyl ether acetate has a simple operation process, a continuous and efficient production process, easy control of conditions, stable production and high efficiency, and is very suitable for large-scale industrial applications.

[0035] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0036] The composition of the industrial-grade PGMEA in the following examples and comparative examples is as follows: the purity is 99.0 wt%, the total metal ion content is 100 ppb, the water content is 200 ppm, the acidity is 200 ppm, the content of 2-methoxy-1-propyl acetate is 20 ppm, and the acetic acid content is 10 ppm.

[0037] Example 1

[0038] Use a feed pump (the pump head material of the feed pump is 316L, and the grade is EP) to pump 200 Kg of industrial-grade PGMEA into a metal ion adsorption column pre-activated at 300 °C at a rate of 8 Kg / h (the specification of the metal ion adsorption column is DN50×1000, the material is S316, the adsorption packing is SNT-18 polished resin, the particle size is 0.315 - 1.250 mm, and the pressure is 0.1 MPa) for removing metal impurities. Pump the obtained metal-free propylene glycol methyl ether acetate into a light-component removal distillation column (the column diameter of the light-component removal distillation column is DN40, the number of theoretical plates is 18, the column height is 2.5 m, the material is S316, and the packing specification is 3×3 mm θ ring), control the reflux ratio of the light-component removal distillation column to be 8:1, the bottom heating temperature to be 78 °C, and the column pressure to be 0.001 MPa. Pump the light-component-removed propylene glycol methyl ether acetate into a heavy-component removal distillation column (the column diameter of the heavy-component removal distillation column is DN40, the number of theoretical plates is 28, the column height is 2.5 m, the material is S316, and the packing specification is 3×3 mm θ ring) for continuous distillation, control the reflux ratio of the heavy-component removal distillation column to be 3:1, the bottom heating temperature to be 83 °C, and the column pressure to be 0.001 MPa. After dehydration and removal of organic impurities, filter through an ultra-high purity filter at normal temperature and pressure (the material of the filter is PFA, and the filter diameter is 50 nm) to remove some metal impurities, organic substances, and particles to obtain high-purity PGMEA. Analyze and detect the obtained product. In the obtained high-purity PGMEA, each single-phase metal ion is ≤10 ppt, the total metal is 26 ppt, the water content is 23 ppm, the acidity is 28 ppm, the purity is 99.99%, the content of 2-methoxy-1-propyl acetate is 2.91 ppm, and the content of acetic acid is 0.10 ppm.

[0039] Example 2

[0040] Use a feed pump (the pump head material of the feed pump is 316L, and the grade is EP) to pump 200 Kg of industrial-grade PGMEA into a metal ion adsorption column pre-activated at 400 °C at a rate of 10 Kg / h (the specification of the metal ion adsorption column is DN50×1000, the material is S316, the adsorption packing is SNT-18 polished resin, the particle size is 0.315 - 1.250 mm, and the pressure is 0.6 MPa) for the removal of metal impurities. Pump the obtained metal-free propylene glycol methyl ether acetate into a light component removal distillation column (the column diameter of the light component removal distillation column is DN40, the number of theoretical plates is 25, the column height is 2.5 m, the material is S316, and the packing specification is 3×3 mm θ ring), control the reflux ratio of the light component removal distillation column to be 20:1, the bottom heating temperature to be 90 °C, and the pressure inside the column to be 0.0015 MPa. Pump the light component-removed propylene glycol methyl ether acetate into a heavy component removal distillation column (the column diameter of the heavy component removal distillation column is DN40, the number of theoretical plates is 22, the column height is 2.5 m, the material is S316, and the packing specification is 3×3 mm θ ring) for continuous distillation, control the reflux ratio of the heavy component removal distillation column to be 2:1, the bottom heating temperature to be 100 °C, and the pressure inside the column to be 0.0005 MPa. After dehydration and removal of organic impurities, filter through an ultra-high purity filter at normal temperature and pressure (the material of the filter is PFA, and the filter diameter is 50 nm) to remove some metal impurities, organic substances, and particles to obtain high-purity PGMEA. Analyze and detect the obtained product. In the obtained high-purity PGMEA, each single-phase metal ion is ≤10 ppt, the total metal is 49 ppt, the water content is 25 ppm, the acidity is 29 ppm, the purity is 99.99%, the content of 2-methoxy-1-propyl acetate is 2.96 ppm, and the content of acetic acid is 0.06 ppm.

[0041] Example 3

[0042] Use a feed pump (the pump head material of the feed pump is 316L, and the grade is EP) to pump 200 Kg of industrial-grade PGMEA into a metal ion adsorption column pre-activated at 400 °C at a rate of 10 Kg / h (the specification of the metal ion adsorption column is DN50×1000, the material is S316, the adsorption packing is SNT-18 polished resin, the particle size is 0.315 - 1.250 mm, and the pressure is 0.3 MPa) for the treatment of removing metal impurities. Then pump the de-metallized propylene glycol methyl ether acetate into a light-component stripping column (the column diameter of the light-component stripping column is DN40, the number of theoretical plates is 20, the column height is 2.5 m, the material is S316, and the packing specification is 3×3 mm θ ring), control the reflux ratio of the light-component stripping column to be 5:1, the bottom heating temperature to be 70 °C, and the pressure inside the column to be 0.0012 MPa. Pump the light-component stripped propylene glycol methyl ether acetate into a heavy-component stripping column (the column diameter of the heavy-component stripping column is DN40, the number of theoretical plates is 25, the column height is 2.5 m, the material is S316, and the packing specification is 3×3 mm θ ring) for continuous distillation, control the reflux ratio of the heavy-component stripping column to be 7:1, the bottom heating temperature to be 80 °C, and the pressure inside the column to be 0.001 MPa. After dehydration and removal of organic impurities, filter through a normal-temperature and normal-pressure ultra-high purity filter (the material of the filter is PFA, and the filter diameter is 50 nm) to remove some metal impurities, organic substances, and particles, and obtain high-purity PGMEA. Analyze and detect the obtained product. In the obtained high-purity PGMEA, each single-phase metal ion is ≤ 10 ppt, the total metal is 33 ppt, the water content is 25 ppm, the acidity is 20 ppm, the purity is 99.99%, the content of 2-methoxy-1-propyl acetate is 1.42 ppm, and the content of acetic acid is 0.08 ppm.

[0043] Comparative Example 1

[0044] Charge 200 Kg of industrial-grade PGMEA into the light-component removal rectification column (the column diameter of the light-component removal rectification column is DN40, the number of theoretical plates is 18, the column height is 2.5 m, the material is S316, and the packing specification is 3×3 mm θ-ring). Control the reflux ratio of the light-component removal rectification column to be 8:1, the bottom heating temperature to be 78 °C, and the internal pressure of the column to be 0.001 MPa. Charge the propylene glycol methyl ether acetate after light-component removal into the heavy-component removal rectification column (the column diameter of the heavy-component removal rectification column is DN40, the number of theoretical plates is 28, the column height is 2.5 m, the material is S316, and the packing specification is 3×3 mm θ-ring) for continuous rectification. Control the reflux ratio of the heavy-component removal rectification column to be 3:1, the bottom heating temperature to be 83 °C, and the internal pressure of the column to be 0.001 MPa. After heavy-component removal, use a feed pump (the pump head material of the feed pump is 316L, and the grade is EP) to charge it into a metal ion adsorption column pre-activated at 300 °C at a rate of 8 Kg / h (the specification of the metal ion adsorption column is DN50×1000, the material is S316, the adsorption packing is SNT-18 polished resin, the particle size is 0.315 - 1.250 mm, and the pressure is 0.1 MPa) for the removal of gold impurities. Finally, transfer it to a normal-temperature and normal-pressure ultra-high purity filter for filtration (the material of the filter is PFA, and the filter diameter is 50 nm) to filter out some metal impurities, organic substances, and particles to obtain high-purity PGMEA. Analyze and detect the obtained product. In the high-purity PGMEA obtained, the content of each single-phase metal ion is ≤100 ppt, the total metal is 10 ppb, the water content is 70 ppm, the acidity is 68 ppm, the purity is 99.73%, the content of 2-methoxy-1-propyl acetate is 7.37 ppm, and the content of acetic acid is 4.25 ppm.

[0045] Comparative Example 2

[0046] Using a feed pump (the pump head material of the feed pump is 316L, and the grade is EP), 200 Kg of industrial-grade PGMEA is pumped into a metal ion adsorption column pre-activated at 300 °C at a rate of 8 Kg / h (the specification of the metal ion adsorption column is DN50×1000, the material is S316, the adsorption packing is SNT-18 polished resin, the particle size is 0.315 - 1.250 mm, and the pressure is 0.1 MPa) for the removal of gold impurities. The de-metallized propylene glycol methyl ether acetate is then pumped into a light component removal distillation column (the column diameter of the light component removal distillation column is DN40, the number of theoretical plates is 18, the column height is 2.5 m, the material is S316, and the packing specification is 3×3 mm θ ring). The reflux ratio of the light component removal distillation column is controlled at 4:1, the bottom heating temperature is 62 °C, and the pressure inside the column is 0.002 MPa. The light component-removed propylene glycol methyl ether acetate is pumped into a heavy component removal distillation column (the column diameter of the heavy component removal distillation column is DN40, the number of theoretical plates is 28, the column height is 2.5 m, the material is S316, and the packing specification is 3×3 mm θ ring) for continuous distillation. The reflux ratio of the heavy component removal distillation column is controlled at 3:1, the bottom heating temperature is 83 °C, and the pressure inside the column is 0.001 MPa. After dehydration and removal of organic impurities, it is filtered through an ultra-high purity filter at normal temperature and pressure (the material of the filter is PFA, and the filtration diameter is 50 nm) to remove some metal impurities, organic substances, and particles, obtaining high-purity PGMEA. The obtained product is analyzed and tested. In the obtained high-purity PGMEA, each single-phase metal ion is ≤50 ppt, the total metal is 5 ppb, the water content is 119 ppm, the acidity is 43 ppm, the purity is 99.26%, the content of 2-methoxy-1-propyl acetate is 6.10 ppm, and the content of acetic acid is 1.13 ppm.

[0047] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A purification method of propylene glycol methyl ether acetate, characterized in that, It includes the following steps: 1) Perform metal removal treatment on industrial-grade propylene glycol methyl ether acetate in a metal ion adsorption column to obtain metal-removed propylene glycol methyl ether acetate; 2) Transfer the metal-removed propylene glycol methyl ether acetate to a light component removal distillation column for light component removal to obtain light component-removed propylene glycol methyl ether acetate; 3) Transfer the light component-removed propylene glycol methyl ether acetate to a heavy component removal distillation column for heavy component removal to obtain heavy component-removed propylene glycol methyl ether acetate; 4) Filter the heavy component-removed propylene glycol methyl ether acetate to obtain high-purity propylene glycol methyl ether acetate.

2. The purification method according to claim 1, characterized in that, In step 1), the purity of the industrial-grade propylene glycol methyl ether acetate is ≥99 wt%, the single metal ion is ≤10 ppb, and the total metal ions are ≤100 ppb.

3. The purification method according to claim 1, characterized in that, In step 1), the material of the metal ion adsorption column is S316, and the adsorption packing is ion exchange resin.

4. The purification method according to claim 1, characterized in that, In step 1), when performing metal removal treatment, the design pressure is -0.1 to 0.6 MPa, the design temperature is 500 °C, and the operating temperature is 300 to 400 °C.

5. The purification method according to claim 1, wherein In step 2), the theoretical number of trays of the light component removal distillation column is 18 to 25. When performing light component removal, the column pressure in the light component removal distillation column is 1.0 to 1.5 KPa, the bottom temperature is 70 to 90 °C, and the reflux ratio is 5 to 20:

1.

6. The purification method according to claim 1, wherein In step 3), the theoretical number of trays of the heavy component removal distillation column is 22 to 28. When performing heavy component removal, the column pressure in the heavy component removal distillation column is 0.5 to 1.0 KPa, the bottom temperature is 80 to 100 °C, and the reflux ratio is 2 to 7:

1.

7. The purification method according to claim 1, characterized in that, The diameter of the light component removal distillation column is DN40, the height is 2.5 m, the material is S316, and the packing specification is 3×3 mm θ ring; The diameter of the heavy component removal distillation column is DN40, the height is 2.5 m, the material is S316, and the packing specification is 3×3 mm θ ring.

8. The purification method according to claim 1, characterized in that, In step 4), when performing filtration, the material of the filter is PFA, and the filter diameter is 30 to 70 nm.

9. The purification method according to claim 1, characterized in that, In step 1), a feed pump is used to pump propylene glycol methyl ether acetate into the metal ion adsorption column. The pump head material of the feed pump is 316L, and the grade is EP.

10. The preparation method according to claim 1, characterized in that, In the high-purity propylene glycol methyl ether acetate obtained in step 4), the single metal ion is ≤10 ppt, the total metal ions are ≤49 ppt, the water content is ≤30 ppm, the acidity is ≤30 ppm, the purity is ≥99.99 wt%, the content of 2-methoxy-1-propyl acetate is ≤5 ppm, and the acetic acid content is ≤0.1 ppm.