Synthesis method of additive fluoroethylene carbonate for lithium battery electrolyte

Abstract

The preparation method comprises the following steps: by taking chloroethylene carbonate as a raw material and quaternary ammonium salt fluoride as a fluorinating reagent, carrying out halogen exchange reaction in an organic solvent to obtain a fluoroethylene carbonate crude product, and carrying out crude steaming, rectification and crystallization to obtain the high-purity fluoroethylene carbonate. Quaternary ammonium salt fluoride has good solubility in an organic solvent, a reaction system is a homogeneous system, reaction time is short, reaction conditions are mild, no solid salt is generated in the process, product aftertreatment is simple, and three wastes are few. And the prepared product has high yield and high purity, and fills the blank of fluoroethylene carbonate process with simple post-treatment.

Description

Technical Field

[0001] The present application relates to the technical field of organic synthesis, and in particular to a method for synthesizing fluoroethylene carbonate, an additive for lithium battery electrolyte. Background Art

[0002] Today, the application fields of new energy lithium batteries are becoming more and more extensive. Fluorinated ethylene carbonate is a chemical substance that can be used as an additive in lithium-ion battery electrolytes to improve the performance of SEI film formation, form a tight structure layer without increasing impedance, prevent further decomposition of the electrolyte, and improve the low-temperature performance of the electrolyte. It plays an important role in the preparation of lithium-ion batteries.

[0003] At present, the synthesis of fluoroethylene carbonate is mostly carried out by passing fluorine gas into ethylene carbonate for fluorination reaction. However, this reaction will produce monofluoroethylene carbonate and difluoroethylene carbonate, resulting in low product purity, high process requirements, high risk, and complex subsequent treatment, which can no longer meet the performance requirements of lithium-ion batteries. How to simply synthesize fluoroethylene carbonate as an additive for lithium battery electrolyte with a high yield and fill the gap in the relevant field has important practical significance and application value. Summary of the invention

[0004] In order to provide a fluoroethylene carbonate additive for lithium battery electrolyte with high yield, purity and simple post-treatment, the present application provides a method for synthesizing fluoroethylene carbonate additive for lithium battery electrolyte.

[0005] The present application provides a method for synthesizing fluoroethylene carbonate, an additive for lithium battery electrolyte, comprising the following steps: adding chloroethylene carbonate and quaternary ammonium salt fluoride into an organic solvent, stirring for reaction, and obtaining fluoroethylene carbonate.

[0006]

[0007] By adopting the above technical scheme, chloroethylene carbonate raw material and quaternary ammonium salt fluoride are used as fluorination reagents, and halogen exchange reaction is carried out in an organic solvent to obtain a crude fluoroethylene carbonate product. The quaternary ammonium salt fluoride has good solubility in the organic solvent, the reaction system is a homogeneous system, the reaction time is short and the conditions are mild, no solid salt is generated during the process, the product post-processing is simple, and the three wastes are less. The obtained product has high purity and high yield, and at the same time, each intermediate is in a stable state, which is conducive to industrial production.

[0008] In a specific embodiment, the quaternary ammonium salt fluoride has the following structural formula:

[0009] In the formula, R1, R2, R3, and R4 are the same or different alkyl groups or phenyl groups, such as methyl, ethyl, propyl, butyl, and benzyl.

[0010] By adopting the above technical solution, the stability of the reaction is improved, the reaction is thorough, the utilization rate of raw materials is improved, the occurrence of side reactions is reduced, the stability of the reaction is improved, the purity of the obtained fluoroethylene carbonate is high, and the difficulty of subsequent purification is reduced. The reaction speed is fast, the operation is simple, and the selectivity is high.

[0011] In a specific embodiment, the following steps are also included: crude distillation under reduced pressure, rectification, and crystallization.

[0012] By adopting the technical solution, the process is simple, the prepared fluoroethylene carbonate has high purity, and the solvent is fully separated.

[0013] In a specific embodiment, the quaternary ammonium salt fluoride includes one or more of tetramethylammonium fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride, tetrabutylammonium fluoride, and benzyltrimethylammonium fluoride.

[0014] By adopting the above technical solution, the utilization rate of raw materials is improved, the occurrence of side reactions is reduced, and the occurrence of side reactions is reduced.

[0015] In a specific embodiment, the reaction temperature is 20-90°C.

[0016] Preferably, the reaction temperature is 25-50°C.

[0017] By adopting the above technical solution, the reaction temperature and time are optimized, the chloroethylene carbonate raw material and the quaternary ammonium salt fluoride react completely, and the by-products are small.

[0018] In a specific embodiment, the molar ratio of the raw materials is chloroethylene carbonate: quaternary ammonium salt fluoride = (1-1.5):1.

[0019] By adopting the above technical solution, the dosage of chloroethylene carbonate and fluorination reagent is optimized, the occurrence of side reactions is reduced, and it is helpful to improve the yield and purity of the compound.

[0020] In a specific embodiment, the reaction time is 2-6 hours.

[0021] By adopting the above technical solution, the reaction time is optimized, the compound reacts completely, the side reactions are reduced, and the yield and purity of the product are improved.

[0022] In a specific embodiment, the mass ratio of raw materials is ethylene chloride carbonate: organic solvent = 1: (5-10).

[0023] By adopting the above technical solution, the dosage of chloroethylene carbonate and organic solvent is optimized, the occurrence of side reactions is reduced, and it is helpful to improve the yield and purity of the compound.

[0024] In a specific embodiment, the reduced pressure crude distillation temperature is 40-110° C. and the vacuum degree is 5-15 Torr.

[0025] By adopting the above technical solution, the distillation effect is sufficient, which is suitable for the reactant components of this application and can improve the yield and purity of the obtained product.

[0026] In summary, this application has the following beneficial technical effects: The present invention uses chloroethylene carbonate as raw material and quaternary ammonium salt fluoride as fluorination agent, performs halogen exchange reaction in organic solvent, obtains crude fluoroethylene carbonate, and obtains high-purity fluoroethylene carbonate after crude steaming, rectification and crystallization. Quaternary ammonium salt fluoride has good solubility in organic solvent, the reaction system is a homogeneous system, the reaction time is short and the conditions are mild, no solid salt is generated in the process, the product post-processing is simple, and the three wastes are less. DETAILED DESCRIPTION

[0027] To further help understand the technical solution of the present invention, several specific embodiments are provided to describe the technical solution of the present invention in more detail. All the embodiments described are only partial embodiments of the present invention, not all of them; the embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments. The following embodiments are further explanations of the present invention, and the present invention is not limited thereto.

[0028] The components of the preparation examples used in the examples of this application all refer to components obtained by the preparation examples. The experimental reagents in the preparation examples, embodiments, and comparative examples, unless otherwise specified, are conventional commercial brands or obtained by conventional preparation processes. Example Example 1

[0029] Add 185g (1.0mol) of tetraethylammonium fluoride dihydrate and 1000g of acetonitrile to a 2L reaction bottle and stir to dissolve. Under nitrogen protection, heat to 75°C to remove water by azeotropic distillation, and distill out about 200g of a mixture of acetonitrile and water. Under nitrogen protection, lower the reaction liquid temperature to 35°C.

[0030] 165g (1.1mol) of chloroethylene carbonate was added dropwise to the reaction flask under stirring. After the addition was completed, the temperature was kept at 35°C for 3 hours. After the chloroethylene carbonate content monitored by GC no longer changed, the reaction was stopped. The acetonitrile solvent was first distilled off under normal pressure, and then distilled under reduced pressure. The end point temperature of the distillation was controlled at 110°C and the vacuum degree was 5 Torr. 115.6g of crude fluoroethylene carbonate was obtained with a purity of 83.7% and a yield of 91.2%. Example 2

[0031] Add 185g (1.0mol) of tetraethylammonium fluoride dihydrate and 1000g of 2-methyltetrahydrofuran to a 2L reaction bottle and stir to dissolve. Under nitrogen protection, heat to 63°C to remove water by azeotropic distillation, and distill out about 200g of a mixture of 2-methyltetrahydrofuran and water. Lower the temperature of the reaction liquid to 40°C under nitrogen protection.

[0032] 165g (1.1mol) of chloroethylene carbonate was added dropwise to the reaction flask under stirring. After the addition was completed, the temperature was kept at 40°C for 3 hours. After the chloroethylene carbonate content monitored by GC no longer changed, the reaction was stopped. The 2-methyltetrahydrofuran solvent was first distilled off under normal pressure, and then distilled under reduced pressure. The end point temperature of the distillation was controlled at 110°C and the vacuum degree was 6Torr to obtain 113.2g of crude fluoroethylene carbonate with a purity of 88.4% and a yield of 94.4%. Example 3

[0033] Add 185g (1.0mol) of tetraethylammonium fluoride dihydrate and 1000g of 2-methyltetrahydrofuran to a 2L reaction bottle and stir to dissolve. Under nitrogen protection, heat to 63°C to remove water by azeotropic distillation, and distill out about 200g of a mixture of 2-methyltetrahydrofuran and water. Lower the temperature of the reaction liquid to 40°C under nitrogen protection.

[0034] 165g (1.1mol) of chloroethylene carbonate was added dropwise to the reaction flask under stirring. After the addition was completed, the temperature was kept at 40°C for 3 hours. After the chloroethylene carbonate content monitored by GC did not change, the reaction was stopped. The 2-methyltetrahydrofuran solvent was first distilled off under normal pressure, and then distilled under reduced pressure. The end point temperature of the distillation was controlled at 120°C and the vacuum degree was 4 Torr. 114.6g of crude fluoroethylene carbonate was obtained with a purity of 85.4%. Example 4

[0035] Add 185g (1.0mol) of tetraethylammonium fluoride dihydrate and 1000g of 2-methyltetrahydrofuran to a 2L reaction bottle and stir to dissolve. Under nitrogen protection, heat to 63°C to remove water by azeotropic distillation, and distill out about 200g of a mixture of 2-methyltetrahydrofuran and water. Lower the temperature of the reaction liquid to 40°C under nitrogen protection.

[0036] 120g (0.8mol) of chloroethylene carbonate was added dropwise to the reaction flask under stirring. After the addition was completed, the temperature was kept at 40°C for 3 hours. After the chloroethylene carbonate content monitored by GC did not change, the reaction was stopped. The 2-methyltetrahydrofuran solvent was first distilled off under normal pressure, and then distilled under reduced pressure. The end point temperature of the distillation was controlled at 110°C and the vacuum degree was 6 Torr. 89.7g of crude fluoroethylene carbonate was obtained with a purity of 84.4%. Example 5

[0037] Add 185g (1.0mol) of tetraethylammonium fluoride dihydrate and 1000g of 2-methyltetrahydrofuran to a 2L reaction bottle and stir to dissolve. Under nitrogen protection, heat to 63°C to remove water by azeotropic distillation, and distill out about 200g of a mixture of 2-methyltetrahydrofuran and water. Lower the temperature of the reaction liquid to 40°C under nitrogen protection.

[0038] 255g (1.7mol) of chloroethylene carbonate was added dropwise to the reaction flask under stirring. After the addition was completed, the temperature was kept at 40°C for 3 hours. After the chloroethylene carbonate content monitored by GC did not change, the reaction was stopped. The 2-methyltetrahydrofuran solvent was first distilled off under normal pressure, and then distilled under reduced pressure. The end point temperature of the distillation was controlled at 110°C and the vacuum degree was 6 Torr to obtain 101.5g of crude fluoroethylene carbonate with a purity of 85.1%. Example 6

[0039] Add 185g (1.0mol) of tetraethylammonium fluoride dihydrate and 1500g of 2-methyltetrahydrofuran to a 2L reaction bottle and stir to dissolve. Under nitrogen protection, heat to 63°C to remove water by azeotropic distillation, and distill out about 200g of a mixture of 2-methyltetrahydrofuran and water. Under nitrogen protection, lower the reaction liquid temperature to 40°C.

[0040] 165g (1.1mol) of chloroethylene carbonate was added dropwise to the reaction flask under stirring. After the addition was completed, the temperature was kept at 40°C for 3 hours. After the chloroethylene carbonate content monitored by GC no longer changed, the reaction was stopped. The 2-methyltetrahydrofuran solvent was first distilled off under normal pressure, and then distilled under reduced pressure. The end point temperature of the distillation was controlled at 110°C and the vacuum degree was 6 Torr to obtain 108.1g of crude fluoroethylene carbonate with a purity of 88.0%.

[0041] Example 7 Add 185g (1.0mol) of tetraethylammonium fluoride dihydrate and 850g of 2-methyltetrahydrofuran to a 2L reaction bottle and stir to dissolve. Under nitrogen protection, heat to 63°C to remove water by azeotropic distillation, and distill out about 200g of a mixture of 2-methyltetrahydrofuran and water. Lower the temperature of the reaction liquid to 40°C under nitrogen protection.

[0042] 165g (1.1mol) of chloroethylene carbonate was added dropwise to the reaction flask under stirring. After the addition was completed, the temperature was kept at 40°C for 3 hours. After the chloroethylene carbonate content monitored by GC no longer changed, the reaction was stopped. The 2-methyltetrahydrofuran solvent was first distilled off under normal pressure, and then distilled under reduced pressure. The end point temperature of the distillation was controlled at 110°C and the vacuum degree was 6 Torr. 107.1g of crude fluoroethylene carbonate was obtained with a purity of 86.4%. Example 8

[0043] Add 185g (1.0mol) of tetraethylammonium fluoride dihydrate and 700g of 2-methyltetrahydrofuran to a 2L reaction bottle and stir to dissolve. Under nitrogen protection, heat to 63°C to remove water by azeotropic distillation, and distill out about 200g of a mixture of 2-methyltetrahydrofuran and water. Under nitrogen protection, lower the reaction liquid temperature to 40°C.

[0044] 165g (1.1mol) of chloroethylene carbonate was added dropwise to the reaction flask under stirring. After the addition was completed, the temperature was kept at 40°C for 3 hours. After the chloroethylene carbonate content monitored by GC did not change, the reaction was stopped. The 2-methyltetrahydrofuran solvent was first distilled off under normal pressure, and then distilled under reduced pressure. The end point temperature of the distillation was controlled at 110°C and the vacuum degree was 6 Torr. 94.7g of crude fluoroethylene carbonate was obtained with a purity of 75.2%. Example 9

[0045] Add 185g (1.0mol) of tetraethylammonium fluoride dihydrate and 1000g of 2-methyltetrahydrofuran to a 2L reaction bottle and stir to dissolve. Under nitrogen protection, heat to 63°C to remove water by azeotropic distillation, and distill out about 200g of a mixture of 2-methyltetrahydrofuran and water. Lower the temperature of the reaction liquid to 40°C under nitrogen protection.

[0046] 225g (1.5mol) of chloroethylene carbonate was added dropwise to the reaction flask under stirring. After the addition was completed, the temperature was kept at 40°C for 3 hours. After the chloroethylene carbonate content monitored by GC no longer changed, the reaction was stopped. The 2-methyltetrahydrofuran solvent was first distilled off under normal pressure, and then distilled under reduced pressure. The end point temperature of the distillation was controlled at 110°C and the vacuum degree was 6 Torr. 117.1g of crude fluoroethylene carbonate was obtained with a purity of 86.9%. Example 10

[0047] Add 185g (1.0mol) of tetraethylammonium fluoride dihydrate and 1000g of 2-methyltetrahydrofuran to a 2L reaction bottle and stir to dissolve. Under nitrogen protection, heat to 63°C to remove water by azeotropic distillation, and distill out about 200g of a mixture of 2-methyltetrahydrofuran and water. Lower the temperature of the reaction liquid to 40°C under nitrogen protection.

[0048] 150g (1.0mol) of chloroethylene carbonate was added dropwise to the reaction flask under stirring. After the addition was completed, the temperature was kept at 40°C for 3 hours. After the chloroethylene carbonate content monitored by GC did not change, the reaction was stopped. The 2-methyltetrahydrofuran solvent was first distilled off under normal pressure, and then distilled under reduced pressure. The end point temperature of the distillation was controlled at 110°C and the vacuum degree was 6Torr to obtain 111.2g of crude fluoroethylene carbonate with a purity of 88.5%. Embodiment 11

[0049] Add 185g (1.0mol) of tetraethylammonium fluoride dihydrate and 1000g of 2-methyltetrahydrofuran to a 2L reaction bottle and stir to dissolve. Under nitrogen protection, heat to 63°C to remove water by azeotropic distillation, and distill out about 200g of a mixture of 2-methyltetrahydrofuran and water. Lower the temperature of the reaction liquid to 40°C under nitrogen protection.

[0050] 165g (1.1mol) of chloroethylene carbonate was added dropwise to the reaction flask under stirring. After the addition was completed, the temperature was kept at 40°C for 6 hours. After the chloroethylene carbonate content monitored by GC no longer changed, the reaction was stopped. The 2-methyltetrahydrofuran solvent was first distilled off under normal pressure, and then distilled under reduced pressure. The end point temperature of the distillation was controlled at 110°C and the vacuum degree was 6 Torr. 116.4g of crude fluoroethylene carbonate was obtained with a purity of 88.3%. Example 12

[0051] Add 185g (1.0mol) of tetraethylammonium fluoride dihydrate and 1000g of 2-methyltetrahydrofuran to a 2L reaction bottle and stir to dissolve. Under nitrogen protection, heat to 63°C to remove water by azeotropic distillation, and distill out about 200g of a mixture of 2-methyltetrahydrofuran and water. Lower the temperature of the reaction liquid to 40°C under nitrogen protection.

[0052] 165g (1.1mol) of chloroethylene carbonate was added dropwise to the reaction flask under stirring. After the addition was completed, the temperature was kept at 40°C for 3 hours. After the chloroethylene carbonate content monitored by GC no longer changed, the reaction was stopped. The 2-methyltetrahydrofuran solvent was first distilled off under normal pressure, and then distilled under reduced pressure. The end point temperature of the distillation was controlled at 110°C and the vacuum degree was 15 Torr. 113.0g of crude fluoroethylene carbonate was obtained with a purity of 88.5%. Example 13

[0053] Add 185g (1.0mol) of tetraethylammonium fluoride dihydrate and 1000g of 2-methyltetrahydrofuran to a 2L reaction bottle and stir to dissolve. Under nitrogen protection, heat to 63°C to remove water by azeotropic distillation, and distill out about 200g of a mixture of 2-methyltetrahydrofuran and water. Lower the temperature of the reaction liquid to 40°C under nitrogen protection.

[0054] 165g (1.1mol) of chloroethylene carbonate was added dropwise to the reaction flask under stirring. After the addition was completed, the temperature was kept at 60°C for 3 hours. After the chloroethylene carbonate content monitored by GC did not change, the reaction was stopped. The 2-methyltetrahydrofuran solvent was first distilled off under normal pressure, and then distilled under reduced pressure. The end point temperature of the distillation was controlled at 110°C and the vacuum degree was 6Torr to obtain 109.2g of crude fluoroethylene carbonate with a purity of 83.4%. Embodiment 14

[0055] Add 185g (1.0mol) of tetraethylammonium fluoride dihydrate and 1000g of 2-methyltetrahydrofuran to a 2L reaction bottle and stir to dissolve. Under nitrogen protection, heat to 63°C to remove water by azeotropic distillation, and distill out about 200g of a mixture of 2-methyltetrahydrofuran and water. Lower the temperature of the reaction liquid to 40°C under nitrogen protection.

[0056] 165g (1.1mol) of chloroethylene carbonate was added dropwise to the reaction flask under stirring. After the addition was completed, the reaction was maintained at 100°C for 3 hours. After the chloroethylene carbonate content monitored by GC no longer changed, the reaction was stopped. The 2-methyltetrahydrofuran solvent was first distilled off under normal pressure, and then distilled under reduced pressure. The end point temperature of the distillation was controlled at 110°C and the vacuum degree was 6Torr to obtain 91.7g of crude fluoroethylene carbonate with a purity of 64.4%. Embodiment 15

[0057] Add 185g (1.0mol) of tetraethylammonium fluoride dihydrate and 1000g of 2-methyltetrahydrofuran to a 2L reaction bottle and stir to dissolve. Under nitrogen protection, heat to 63°C to remove water by azeotropic distillation, and distill out about 200g of a mixture of 2-methyltetrahydrofuran and water. Lower the temperature of the reaction liquid to 40°C under nitrogen protection.

[0058] 165g (1.1mol) of chloroethylene carbonate was added dropwise to the reaction flask under stirring. After the addition was completed, the temperature was kept at 50°C for 3 hours. After the chloroethylene carbonate content monitored by GC did not change, the reaction was stopped. The 2-methyltetrahydrofuran solvent was first distilled off under normal pressure, and then distilled under reduced pressure. The end point temperature of the distillation was controlled at 110°C and the vacuum degree was 6 Torr. 113.1g of crude fluoroethylene carbonate was obtained with a purity of 88.3%. Embodiment 15

[0059] Add 185g (1.0mol) of tetraethylammonium fluoride dihydrate and 1000g of 2-methyltetrahydrofuran to a 2L reaction bottle and stir to dissolve. Under nitrogen protection, heat to 63°C to remove water by azeotropic distillation, and distill out about 200g of a mixture of 2-methyltetrahydrofuran and water. Lower the temperature of the reaction liquid to 40°C under nitrogen protection.

[0060] 165g (1.1mol) of chloroethylene carbonate was added dropwise to the reaction flask under stirring. After the addition was completed, the temperature was kept at 25°C for 3 hours. After the chloroethylene carbonate content monitored by GC no longer changed, the reaction was stopped. The 2-methyltetrahydrofuran solvent was first distilled off under normal pressure, and then distilled under reduced pressure. The end point temperature of the distillation was controlled at 110°C and the vacuum degree was 6 Torr. 113.0g of crude fluoroethylene carbonate was obtained with a purity of 88.4% and a yield of 94.4%.

[0061] The present application uses chloroethylene carbonate as a raw material and quaternary ammonium salt fluoride as a fluorination agent, performs a halogen exchange reaction in an organic solvent, controls the molar ratio of the reactants in each process step during the process, improves the utilization rate of the raw materials, reduces the occurrence of side reactions, and provides convenience for subsequent separation and purification; at the same time, the intermediate product is purified to improve the purity of the intermediate product, so that the final product has the advantages of high yield and high purity.

[0062] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for synthesizing fluoroethylene carbonate as an additive for lithium battery electrolyte, characterized in that: The method comprises the following steps: adding chloroethylene carbonate and quaternary ammonium salt fluoride into an organic solvent, stirring and reacting, and obtaining fluoroethylene carbonate. 。 2. The method for synthesizing fluoroethylene carbonate as an additive for lithium battery electrolyte according to claim 1, characterized in that: The quaternary ammonium salt fluoride has the following structural formula: In the formula, R1, R2, R3, and R4 are the same or different alkyl groups or phenyl groups, such as methyl, ethyl, propyl, butyl, and benzyl.

3. The method for synthesizing fluoroethylene carbonate as an additive for lithium battery electrolyte according to claim 1, characterized in that: The process also comprises the following steps: crude distillation under reduced pressure, rectification and crystallization.

4. The method for synthesizing fluoroethylene carbonate as an additive for lithium battery electrolyte according to claim 2, characterized in that: The quaternary ammonium salt fluoride includes one or more of tetramethylammonium fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride, tetrabutylammonium fluoride and benzyltrimethylammonium fluoride.

5. The method for synthesizing fluoroethylene carbonate as an additive for lithium battery electrolyte according to claim 1, characterized in that: The reaction temperature is 20-90°C.

6. The method for synthesizing fluoroethylene carbonate as an additive for lithium battery electrolyte according to claim 1, characterized in that: The organic solvent includes one or more of dichloroethane, acetonitrile, tetrahydrofuran, and 2-methyltetrahydrofuran.

7. The method for synthesizing fluoroethylene carbonate as an additive for lithium battery electrolyte according to claim 1, characterized in that: The molar ratio of raw materials is ethylene chloride carbonate: quaternary ammonium salt fluoride = (1-1.5):

1.

8. The method for synthesizing fluoroethylene carbonate as an additive for lithium battery electrolyte according to claim 1, characterized in that: The reaction time is 2-6h.

9. A method for synthesizing fluoroethylene carbonate as an additive for lithium battery electrolyte according to any one of claims 1 to 7, characterized in that: The mass ratio of raw materials is ethylene chloride carbonate: organic solvent = 1: (5-10).

10. The method for synthesizing fluoroethylene carbonate as an additive for lithium battery electrolyte according to claim 3, characterized in that: The reduced pressure crude distillation temperature is 40-110°C and the vacuum degree is 5-15 Torr.

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