Method for separating cyclopentyl methyl ether, cyclopentene and methanol through three-tower extractive distillation

Abstract

The invention relates to a method for separating cyclopentyl hexyl methyl ether, cyclopentene and methanol through three-tower extractive distillation. According to the method, an extractive distillation process is adopted, and two extractive distillation towers and a solvent recovery tower are adopted. An organic solvent is used as an extraction agent, cyclopentyl hexyl methyl ether, cyclopentene and methanol firstly enter an extractive distillation tower (EDC1) for extraction separation, high-purity cyclopentene is obtained at the top of the extractive distillation tower (EDC1), materials at the bottom of the extractive distillation tower (EDC1) enter an extractive distillation tower (EDC2) for separation, and high-purity methanol is obtained at the top of the extractive distillation tower (EDC1). Materials at the tower bottom of the extractive distillation tower (EDC2) enter a solvent recovery tower (SRC), high-purity cyclopentyl hexyl methyl ether is obtained at the top of the solvent recovery tower (SRC), and an organic solvent extraction agent is obtained at the bottom of the solvent recovery tower (SRC). The method has the advantages of low energy consumption, simple process, greenness, energy conservation, high product purity after separation and the like, and the adopted organic solvent extraction agent is good in stability, non-toxic and environment-friendly.

Description

Technical Field

[0001] The present invention belongs to the field of chemical separation and purification, and particularly relates to a method for separating a mixture of cyclopentylmethyl ether, cyclopentene and methanol by using two extractive distillation columns and a solvent recovery column.

Background Art

[0002] With the concept of "green chemistry" proposed, more chemical and pharmaceutical processes are developing towards an environmentally friendly direction. As an essential part of chemical processes, the toxicity and environmental friendliness of solvents have received increasing attention. As a new type of ether solvent, cyclopentyl methyl ether has unique chemical properties and excellent physical properties, and has great application potential especially in chemical processes such as extraction, crystallization and polymerization. Due to its hydrophobicity, low toxicity, good solubility and relatively high chemical stability, cyclopentyl methyl ether has gradually become one of the substitutes for traditional harmful solvents. In the extraction process, cyclopentyl methyl ether can effectively dissolve many polar compounds, while avoiding the toxicity and environmental pollution problems of many traditional solvents (such as chloroform, dichloromethane, etc.). In the crystallization process, the low polarity and high stability of cyclopentyl methyl ether provide better control during the dissolution and precipitation processes, improving the selectivity and yield of the crystallization process. In addition, the application of cyclopentyl methyl ether in polymerization reactions also shows significant advantages. Its low toxicity and good solubility make it an ideal solvent in the process of synthesizing polymer materials, especially for environmentally friendly polymerization reactions. As a reaction medium, cyclopentyl methyl ether not only reduces the harm to the environment, but also helps to improve the efficiency of the polymerization reaction and the purity of the product.

[0003] In the process of producing cyclopentyl methyl ether products by etherification reaction with cyclopentene and methanol as raw materials, methanol is likely to form two binary azeotropes with cyclopentyl methyl ether and cyclopentene respectively. The azeotropic boiling points of the two binary azeotropes are 64.48 °C (8.89 wt% cyclopentyl methyl ether, 91.11 wt% methanol) and 36.26 °C (85.12 wt% cyclopentene, 14.88 wt% methanol) respectively, making the purification and refinement of cyclopentyl methyl ether difficult. Due to the existence of various azeotropes in the mixture of cyclopentyl methyl ether, cyclopentene and methanol, simple distillation methods cannot achieve effective separation, so special distillation methods are required.

[0004] The present invention uses an organic solvent extractant to change the relative volatility between cyclopentyl methyl ether, cyclopentene, and methanol to achieve the purification of cyclopentyl methyl ether and the recovery of cyclopentene and methanol. Specifically, the present invention employs two extractive distillation towers and one solvent recovery tower to achieve the efficient separation of the mixture of cyclopentyl methyl ether, cyclopentene, and methanol while efficiently recovering the extractant. The present invention is applicable to the mixture of cyclopentyl methyl ether, cyclopentene, and methanol under near-azeotropic composition, with flexible operation, and can effectively separate two binary azeotropic mixtures through three towers.

Summary of the Invention

[0005] [Technical Problem to be Solved]

[0006] The object of the present invention is to provide a method for separating cyclopentyl methyl ether, cyclopentene, and methanol by three-tower extractive distillation, and to achieve the process design for the efficient separation of two binary azeotropic mixtures by three towers.

[0007] [Technical Solution]

[0008] The present invention proposes a method for separating cyclopentyl methyl ether, cyclopentene, and methanol by three-tower extractive distillation, which uses an organic solvent extractant to change the relative volatility between cyclopentyl methyl ether, cyclopentene, and methanol to achieve the purification of cyclopentyl methyl ether and the recovery of cyclopentene and methanol. Two extractive distillation towers and one solvent recovery tower are used to achieve the efficient separation of cyclopentyl methyl ether, cyclopentene, and methanol.

[0009] The method for separating cyclopentyl methyl ether, cyclopentene, and methanol by three-tower extractive distillation proposed by the present invention is applicable to the mixture of cyclopentyl methyl ether, cyclopentene, and methanol under near-azeotropic composition.

[0010] The method for separating cyclopentyl methyl ether, cyclopentene, and methanol by three-tower extractive distillation proposed by the present invention is characterized in that the device for separating the mixture of cyclopentyl methyl ether, cyclopentene, and methanol mainly comprises the following parts:

[0011] Extractive distillation column (EDC1), extractive distillation column (EDC2), solvent recovery column (SRC), condenser (COND1), condenser (COND2), condenser (COND3), reboiler (ROB1), reboiler (ROB2), reboiler (ROB3), storage tank (T1), storage tank (T2), storage tank (T3), heat exchanger (E1); Feed stream 1 enters from the lower section of the extractive distillation column (EDC1), and the organic solvent extractant stream 2 enters from the upper section of the extractive distillation column (EDC1). The extractive distillation column (EDC1) is respectively connected to the condenser (COND1), storage tank (D1) and reboiler (ROB1) through pipelines; Material stream 4 enters from the lower section of the extractive distillation column (EDC2), and the organic solvent extractant stream 5 enters from the top of the extractive distillation column (EDC2). The extractive distillation column (EDC2) is respectively connected to the condenser (COND2), storage tank (D2) and reboiler (ROB2) through pipelines; Material stream 6 enters from the top of the solvent recovery column (SRC), and is respectively connected to the condenser (COND3), storage tank (D3) and reboiler (ROB3) through pipelines. The pipeline stream 9 is connected to the heat exchanger (E1), and finally the solvent is recovered. After mixing with the supplementary extractant stream 11, it is connected to the extractive distillation column (EDC1) and the extractive distillation column (EDC2).

[0012] A method for separating cyclopentyl methyl ether, cyclopentene and methanol by three - tower extractive distillation invented mainly includes the following steps:

[0013] (1) The raw material liquid of cyclopentyl methyl ether, cyclopentene and methanol enters the extractive distillation column (EDC1) through feed 1, and the organic solvent extractant enters the extractive distillation column (EDC1) through pipeline 2. After extractive separation, it is divided into two outlet streams;

[0014] (2) One outlet stream flows out from pipeline 3 after passing through the condenser (COND1) and enters the storage tank (D1), which is cyclopentane with a purity greater than 0.999. The other outlet stream flows out from pipeline 4 after passing through the reboiler (ROB1), which is a mixed solution of organic solvent extractant, methanol and cyclopentyl methyl ether;

[0015] (3) The mixed solution of organic solvent extractant, methanol and cyclopentyl methyl ether enters the extractive distillation column (EDC2) through pipeline 4, and the organic solvent extractant enters the extractive distillation column (EDC2) through pipeline 5. After extractive separation, it is divided into two outlet streams;

[0016] (4) One outlet stream flows out from pipeline 7 after passing through the condenser (COND2) and enters the storage tank (D2), which is methanol with a purity greater than 0.999. The other outlet stream flows out from pipeline 6 after passing through the reboiler (ROB2), which is a mixed solution of organic solvent extractant and cyclopentyl methyl ether;

[0017] (5) The mixed solution of the organic solvent extractant and cyclopentyl methyl ether enters the solvent recovery column (SRC) through pipeline 6. The cyclopentyl methyl ether and the organic solvent extractant are separated in the column. The cyclopentyl methyl ether (COND3) with a purity greater than 0.999 flows out through pipeline 8 after passing through the condenser (COND3) and enters the storage tank (D3).

[0018] (6) The organic solvent extractant with a purity greater than 0.999 flows out through pipeline 9 after passing through the reboiler (ROB3), enters the heat exchanger (E1). After changing the temperature, it flows out through stream 10, and after mixing with the supplementary extractant stream 11, the extractant is refluxed and re-enters the extractive distillation column (EDC1) and the extractive distillation column (EDC1) for utilization.

[0019] According to another preferred embodiment of the present invention, it is characterized in that: the operating pressure of the extractive distillation column (EDC1) is 0.1 - 0.8 atm, the number of theoretical plates is 30 - 45, the raw material feed position is the 15th - 35th plate, and the extractant feed position is the 2nd - 10th plate; the operating pressure of the extractive distillation column (EDC2) is 0.1 - 0.8 atm, the number of theoretical plates is 50 - 75, the raw material feed position is the 35th - 60th plate, and the extractant feed position is the 2nd - 10th plate; the operating pressure of the solvent recovery column (SRC) is 0.1 - 0.8 atm, the number of theoretical plates is 5 - 10, and the feed position is the 3rd - 7th plate.

[0020] According to another preferred embodiment of the present invention, it is characterized in that: the molar ratio of the feed flow rate of the organic solvent extractant to the mixture of cyclopentyl methyl ether, cyclopentene and methanol is 0.2 - 0.6.

[0021] According to another preferred embodiment of the present invention, it is characterized in that: in the raw material liquid of cyclopentyl methyl ether, cyclopentene and methanol, the molar fraction of cyclopentyl methyl ether is 0.19 - 0.29, the molar fraction of cyclopentene is 0.59 - 0.69, and the molar fraction of methanol is 0.05 - 0.15. The organic solvent extractant is selected from 1,2 - propanediol or ethylene glycol.

[0022] According to another preferred embodiment of the present invention, it is characterized in that: the top temperature range of the extractive distillation column (EDC1) is 10 - 40 °C, the bottom temperature range is 60 - 100 °C, the top temperature range of the extractive distillation column (EDC2) is 15 - 50 °C, the bottom temperature range is 110 - 140 °C, the top temperature range of the solvent recovery column (SRC) is 25 - 55 °C, and the bottom temperature range is 120 - 150 °C.

[0023] According to another preferred embodiment of the present invention, it is characterized in that: after separation, the purities of cyclopentyl methyl ether, cyclopentene and methanol products can all be maintained above 0.999 (mole fraction), and the recovery concentration of the organic solvent extractant is above 0.999 (mole fraction).

[0024] [Beneficial effects]

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The beneficial effect of the present invention is that 1,2 - propanediol or ethylene glycol is used as the organic solvent extractant, which has good solubility, good thermal stability and chemical stability, and can be recycled, reducing the dangerous performance of the process and making the process green.

[0027] (2) The present invention can achieve the efficient separation of two binary azeotropic mixtures of cyclopentyl methyl ether - methanol and cyclopentene - methanol.

[0028] (3) The present invention only uses three towers, with low cost, simple process and flexible operation.

Description of the drawings

[0029] Attached Figure 1 is the extractive distillation process diagram for separating the mixture of cyclopentyl methyl ether, cyclopentene and methanol using an organic solvent extractant.

[0030] In the figure, EDC1 - extractive distillation column; EDC2 - extractive distillation column; SRC - solvent recovery column; COND1 - condenser, COND2 - condenser; COND3 - condenser; ROB1 - reboiler, ROB2 - reboiler, ROB3 - reboiler, D1 - storage tank, D2 - storage tank, D3 - storage tank, E1 - heat exchanger; the numbers represent each stream.

Detailed implementation manners

[0031] The following is further described in conjunction with the drawings, which does not limit the scope involved in the present invention.

[0032] Example 1:

[0033] The feed temperature is 25°C, the feed flow rate is 1000 kmol / h, the pressure is 2 atm (absolute pressure), and the mole fractions of cyclopentyl methyl ether, cyclopentene, and methanol in the raw material are 0.245, 0.649, and 0.106 (mole fraction), respectively. The raw material first enters the extractive distillation column (EDC1) through a pipeline. The operating pressure is 0.41 atm (absolute pressure). The number of theoretical plates in the extractive distillation column (EDC1) is 38. The feed location of the raw material is the 16th plate, and the feed location of the organic solvent extractant (1,2-propanediol) is the 4th plate. The top temperature is 19.93°C, and the bottom temperature is 81.37°C. The mixed solution of 1,2-propanediol, methanol, and cyclopentyl methyl ether enters the extractive distillation column (EDC2) through a pipeline. The operating pressure is 0.41 atm (absolute pressure). The number of theoretical plates in the extractive distillation column (EDC2) is 54. The feed location of the mixed solution is the 37th plate, and the feed location of the organic solvent extractant (1,2-propanediol) is the 3rd plate. The top temperature is 43.33°C, and the bottom temperature is 117.28°C. The mixed solution of 1,2-propanediol and cyclopentyl methyl ether enters the solvent recovery column (SRC) through a pipeline. The operating pressure of the solvent recovery column (SRC) is 0.10 atm (absolute pressure), the number of theoretical plates is 8, the feed location is the 4th plate, the top temperature is 41.99°C, and the bottom temperature of the kettle is 134.87°C. After separation, the mole fractions of cyclopentyl methyl ether, cyclopentene, and methanol are 0.999, and the mole fraction of the recovered 1,2-propanediol is 0.999.

[0034] Example 2:

[0035] The feed temperature is 25°C, the feed flow rate is 1000 kmol / h, the pressure is 2 atm (absolute pressure), and the mole fractions of cyclopentyl methyl ether, cyclopentene, and methanol in the raw material are 0.234, 0.654, and 0.112 (mole fraction), respectively. The raw material first enters the extractive distillation column (EDC1) through a pipeline. The operating pressure is 0.40 atm (absolute pressure). The number of theoretical plates in the extractive distillation column (EDC1) is 37. The feed location of the raw material is the 31st plate, and the feed location of the organic solvent extractant (ethylene glycol) is the 3rd plate. The top temperature is 19.36°C, and the bottom temperature is 82.35°C. The mixed solution of ethylene glycol, methanol, and cyclopentyl methyl ether enters the extractive distillation column (EDC2) through a pipeline. The operating pressure is 0.11 atm (absolute pressure). The number of theoretical plates in the extractive distillation column (EDC2) is 70. The feed location of the mixed solution is the 55th plate, and the feed location of the organic solvent extractant (ethylene glycol) is the 5th plate. The top temperature is 17.63°C, and the bottom temperature is 124.50°C. The mixed solution of ethylene glycol and cyclopentyl methyl ether enters the solvent recovery column (SRC) through a pipeline. The operating pressure of the solvent recovery column (SRC) is 0.10 atm (absolute pressure), the number of theoretical plates is 8, the feed location is the 6th plate, the top temperature is 42.38°C, and the bottom temperature of the column kettle is 149.30°C. After separation, the mole fractions of cyclopentyl methyl ether, cyclopentene, and methanol are 0.999, and the mole fraction of the recycled ethylene glycol is 0.999.

Claims

1. A method for separating cyclopentyl methyl ether, cyclopentene and methanol by three-tower extractive distillation, characterized in that The device for separating a mixture of cyclopentyl methyl ether, cyclopentene and methanol mainly comprises the following parts: an extractive distillation tower (EDC1), an extractive distillation tower (EDC2), a solvent recovery tower (SRC), a condenser (COND1), a condenser (COND2), a condenser (COND3), a reboiler (ROB1), a reboiler (ROB2), a reboiler (ROB3), a storage tank (T1), a storage tank (T2), a storage tank (T3), and a heat exchanger (E1); a raw material stream 1 enters from the lower section of the extractive distillation tower (EDC1), and an organic solvent extractant stream 2 enters from the upper section of the extractive distillation tower (EDC1); the extractive distillation tower (EDC1) is connected to the condenser (COND1), the storage tank (T2), the solvent recovery tower (SRC), and the heat exchanger (E1) through pipelines. The tank (D1) is connected to the reboiler (ROB1); the material stream 4 enters from the lower section of the extractive distillation tower (EDC2), and the organic solvent extractant stream 5 enters from the top of the extractive distillation tower (EDC2). The extractive distillation tower (EDC2) is respectively connected to the condenser (COND2), the storage tank (D2) and the reboiler (ROB2) through pipelines; the material stream 6 enters from the top of the solvent recovery tower (SRC), and is respectively connected to the condenser (COND3), the storage tank (D3) and the reboiler (ROB3) through pipelines, and is connected to the heat exchanger (E1) through the pipeline stream 9, and finally the solvent is recovered, and after mixing with the supplementary extractant stream 11, it is connected to the extractive distillation tower (EDC1) and the extractive distillation tower (EDC2).

2. According to claim 1, it is characterized in that A three-tower extractive distillation method for separating cyclopentyl methyl ether, cyclopentene and methanol is as follows: The raw material liquid of cyclopentyl methyl ether, cyclopentene and methanol enters the extractive distillation tower (EDC1) through feed 1, and the organic solvent extractant enters the extractive distillation tower (EDC1) through pipeline 2. After extraction and separation, the raw material liquid is divided into two streams of discharge; One stream of the output material flows out of pipeline 3 after passing through the condenser (COND1) and enters the storage tank (D1), which is cyclopentane with a purity greater than 0.

999. Another stream flows out of pipeline 4 through the reboiler (ROB1), which is a mixed solution of organic solvent extractant, methanol and cyclopentyl methyl ether; the mixed solution of organic solvent extractant, methanol and cyclopentyl methyl ether enters the extractive distillation tower (EDC2) through pipeline 4, and the organic solvent extractant enters the extractive distillation tower (EDC2) through pipeline 5. After extraction and separation, it is divided into two streams of output material; One stream of the output material flows out of pipeline 7 after passing through the condenser (COND2) and enters the storage tank (D2), which is methanol with a purity greater than 0.

999. Another stream flows out of pipeline 6 through the reboiler (ROB2), which is a mixed solution of organic solvent extractant and cyclopentyl methyl ether; the mixed solution of organic solvent extractant and cyclopentyl methyl ether enters the solvent recovery tower (SRC) through pipeline 6, and the cyclopentyl methyl ether and organic solvent extractant are separated through the tower, and the cyclopentyl methyl ether (COND3) with a purity greater than 0.999 flows out of pipeline 8 and enters the storage tank (D3) after passing through the condenser (COND3); The organic solvent extractant with a purity greater than 0.999 flows out from the pipeline 9 after passing through the reboiler (ROB3), enters the heat exchanger (E1), and after changing the temperature, flows out through the stream 10. After being mixed with the supplementary extractant stream 11, the extractant is refluxed and re-enters the extractive distillation tower (EDC1) and the extractive distillation tower (EDC1) for utilization. The operating pressure of the extractive distillation tower (EDC1) is 0.1-0.8 atm, the number of theoretical plates is 30-45, the raw material feeding position is the 15th to 35th plates, and the extractant feeding position is the 2nd to 10th plates; the operating pressure of the extractive distillation tower (EDC2) is 0.1-0.8 atm, the number of theoretical plates is 50-75, the raw material feeding position is the 35th to 60th plates, and the extractant feeding position is the 2nd to 10th plates; the operating pressure of the solvent recovery tower (SRC) is 0.1-0.8 atm, the number of theoretical plates is 5-10, and the feeding position is the 3rd to 7th plates. The molar ratio of the feed flow rate of the organic solvent extractant to the feed flow rate of the mixture of cyclopentyl methyl ether, cyclopentene and methanol is 0.2 to 0.

6. In the raw material liquid of cyclopentyl methyl ether, cyclopentene and methanol, the molar fraction of cyclopentyl methyl ether is 0.19-0.29, the molar fraction of cyclopentene is 0.59-0.69, and the molar fraction of methanol is 0.05-0.

15. The organic solvent extractant is 1,2-propylene glycol or ethylene glycol. The top temperature range of the extractive distillation tower (EDC1) is 10-40°C, and the bottom temperature range is 60-100°C. The top temperature range of the extractive distillation tower (EDC2) is 15-50°C, and the bottom temperature range is 110-140°C. The top temperature range of the solvent recovery tower (SRC) is 25-55°C, and the bottom temperature range is 120-150°C.

3. According to claims 1-2, it is characterized in that: After separation, the purity of cyclopentyl methyl ether, cyclopentene and methanol products can be maintained above 0.999 (molar fraction), and the recovery concentration of the organic solvent extractant is above 0.999 (molar fraction).

Images