Process and device for preparing and purifying undecylenic acid

Abstract

The invention discloses a process and a device for preparing and purifying undecylenic acid, and the process comprises the following steps: under the condition of negative pressure, firstly carrying out biological enzyme catalytic hydrolysis on methyl undecylenate to obtain undecylenic acid and methanol, and then carrying out filtration, liquid separation and melt crystallization on reaction liquid to obtain purified undecylenic acid, meanwhile, unconverted methyl undecylenate and water are recycled, and generated methanol is recycled. The bio-enzyme is used as a catalyst, the reaction condition is mild, the reaction rate is high, compared with a saponification acidification process, acid utilization and waste salt generation are avoided, and the method is relatively friendly to the environment and equipment; the reaction is carried out under a negative pressure condition, so that the raw material hydrolysis conversion rate is effectively improved; by using a melt crystallization method and a corresponding separation device, a high-yield and high-purity product is easy to obtain. The invention provides a novel process and device for preparation and purification of undecylenic acid, the process conditions are mild, the device is simple, the energy consumption is small, the production efficiency and quality of the product are improved, and the environmental protection property of the production process is also improved.

Description

Technical Field

[0001] The present invention relates to the field of oil and fat chemical industry, and in particular to a new process and device for preparing and purifying undecylenic acid by hydrolysis of methyl undecylenate. Background Art

[0002] Undecylenic acid is an important chemical intermediate and can be used to prepare nylon 11, pharmaceuticals, spices, etc. Undecylenic acid can be prepared by cracking castor oil or directly cracking ricinoleic acid, or by cracking methyl ricinoleate to obtain methyl undecylenate, and then through saponification and acidification. In the process of directly cracking to prepare undecylenic acid, there are problems such as high cracking energy consumption, many by-products, easy coking and low yield; when using methyl ricinoleate to crack and then preparing undecylenic acid from methyl undecylenate, generally, a saponification and acidification process is required (Zhao Xuejing. Chemical Principles and Preparation of Castor Oil-Derived Product Undecylenic Acid [J]. Modern Food, 2015(22): 38-43.), which requires a large amount of alkali liquor and acid liquor, will cause corrosion to the equipment, and will also bring problems in the treatment of waste salt and waste water. Undecylenic acid can also be prepared by hydrolysis of methyl undecylenate. The process described in Chinese Patent CN 116063171A uses pressurized high temperature to produce undecylenic acid. Adding a catalyst can accelerate the chemical reaction rate, but the high temperature results in high energy consumption, and there is also a problem of catalyst reprocessing; Chinese Patent CN 115784866A uses a bubble-cap column as a reactor, which can reduce the energy loss caused by mechanical stirring, and through the contact of the upper and lower liquids for mixing and heat exchange, energy is saved. However, pressurized and high temperature conditions still require a large amount of energy consumption.

[0003] In recent years, due to the mild reaction conditions and fast reaction rate of biological enzymes, Chinese Patent CN 101294170A, Chinese Patent CN 101100628A and Chinese Patent CN 102417916B use lipase to hydrolyze oils and fats, under relatively mild conditions, the reaction process is accelerated, the hydrolysis rate is increased, and the enzyme can be reused.

[0004] The purification process of undecylenic acid generally uses vacuum distillation. However, since undecylenic acid is a thermosensitive substance, the distillation conditions are harsh, chemical reactions are likely to occur during the distillation process, and the distillation yield is low; melt crystallization is a new chemical separation technology and is widely used in the refining and purification of chemical intermediates, pharmaceutical intermediates and biochemical products. Melt crystallization has the characteristics of high separation efficiency, low energy consumption and good environmental protection, and can obtain high-purity products of more than 99%. The melting point of undecylenic acid is relatively high, and the melting point difference from that of methyl undecylenate is large, so melt crystallization can be used for its separation and purification. Summary of the Invention

[0005] The object of the present invention is to overcome the deficiencies existing in the prior art, and to provide a device and process for producing fatty acids by using biological enzymes as catalysts to catalyze fatty acid methyl esters and purifying the fatty acids, which is a new device and process with low energy consumption, high yield and low pollution. The present invention relates to a new process and device for preparing and purifying undecylenic acid.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A process for preparing and purifying undecylenic acid, comprising the following steps:

[0008] 1) Methyl undecylenate, water and biological enzyme are respectively added into the jacketed stirring kettle from the methyl undecylenate feed port, the high-level water tank and the biological enzyme feed port in a certain proportion; start the stirring paddle of the stirring kettle to stir, so that the feed liquid is mixed evenly;

[0009] 2) Vacuum is drawn from the vacuum port to make the reaction system carry out under negative pressure conditions, and the jacketed reaction kettle is heated. After reaching the reaction temperature, keep it constant temperature and carry out stirring reaction;

[0010] 3) As the reaction proceeds, water and methanol vapor are discharged from the gas outlet, condensed by the condenser and collected in the condensate tank, and then sent to the rectification separation from the condensate outlet to realize the recovery of methanol, and the recovered water is sent from the water feed port to the high-level water tank for recycling; during the reaction process, water is supplemented from the high-level water tank into the jacketed stirring kettle to keep the liquid level of the reaction feed liquid at the initial state;

[0011] 4) After the reaction is completed, the feed liquid is filtered and then sent to the water separation tank through the reaction liquid outlet at the bottom of the stirring kettle; after standing for liquid separation, the aqueous phase is discharged from the lower liquid outlet at the bottom of the water separation tank and sent to the high-level water tank as the raw material water for the hydrolysis of methyl undecylenate for standby; the upper oil phase is subjected to melt crystallization purification treatment to obtain the purified undecylenic acid product.

[0012] In the process for preparing and purifying undecylenic acid, the mass ratio of the reaction raw material water to methyl undecylenate is 3-6:1.

[0013] In the process for preparing and purifying undecylenic acid, the mass concentration of the biological enzyme in the reaction feed liquid is 0.5-20%, preferably 0.5-5%.

[0014] In the process for preparing and purifying undecylenic acid, the biological enzyme is at least one of solid enzyme and liquid enzyme. The biological enzyme is mainly lipase, and the lipase is an esterase that can catalyze the hydrolysis of the ester bond of oil.

[0015] The described process for preparing and purifying undecylenic acid is characterized in that the negative pressure condition in the reaction system is that the pressure is maintained at 1 - 20 kPa, preferably 4 - 10 kPa, the reaction temperature is 40 - 60 °C, and the reaction time is 6 - 10 hours.

[0016] The described process for preparing and purifying undecylenic acid is characterized in that the melt crystallization purification treatment includes the following steps:

[0017] S1: Input the upper oil phase into the melt crystallization tower, start the heat exchange system, control the temperature of the melt crystallization tower to be stable at 26 - 30 °C, and then cool down at a certain rate. During this process, the liquid in the melt crystallization tower is discharged through the transition tank and transported back to the melt crystallization tower by a transfer pump for circulating freezing. After the temperature drops to the final temperature of 8 - 12 °C, it is maintained for 0.5 - 2 h. At this time, the unfrozen residual liquid is discharged into the residual liquid tank through the transition tank, and after being discharged from the residual liquid outlet at the bottom of the residual liquid tank, it is used as the raw material for hydrolysis and sent to the stirring kettle for recycling;

[0018] S2: Heat up the crystalline substance in the melt crystallization tower at a certain rate for sweating. Take samples from the sampling port at the bottom of the melt crystallization tower and analyze the sweating liquid. When the content of undecylenic acid is below 99% - 99.5%, the sweating liquid is discharged into the sweating liquid tank, and subsequently, it can be sent into the melt crystallization tower as the purification raw material through the sweating liquid outlet at the bottom of the sweating liquid tank by a transfer pump for purification recycling; when the content of undecylenic acid is above 99% - 99.5%, the melted liquid is transferred to the product tank;

[0019] S3: Finally, quickly heat up the crystalline substance in the melt crystallization tower by adjusting the temperature of the heat exchange system to completely melt it to obtain the product liquid, which is collected in the product tank and discharged and collected through the product outlet at the bottom of the product tank.

[0020] The described process for preparing and purifying undecylenic acid is characterized in that the cooling rate in step S1 is 0.5 - 2 °C / h, the final cooling temperature is 8 - 10 °C, and the holding time at the final cooling temperature is 1 - 1.5 h; the heating rate for sweating in step S2 is 0.1 - 1 °C / h, preferably 0.1 - 0.5 °C / h, the final heating temperature for sweating is 18 - 23 °C, preferably 20 - 22 °C; the final temperature for rapid heating in step S3 is 26 - 30 °C.

[0021] The present invention also provides a device for a process of preparing and purifying undecylenic acid, which includes a high-level water tank, a stirring kettle, a water separation tank, and a melt crystallization purification system. The top and bottom of the high-level water tank are respectively connected to the top of the stirring kettle. A heat exchange fluid is introduced into the jacket outside the stirring kettle for heating it. A stirring paddle is arranged inside the stirring kettle. An undecylenic acid methyl ester feed port and a biological enzyme feed port are also provided at the top of the stirring kettle. The gas outlet at the top of the stirring kettle is sequentially connected to a condenser and a condensate tank through a pipeline. A vacuum extraction port is provided at the top of the condensate tank. The reaction liquid outlet at the bottom of the stirring kettle is connected to the water separation tank through a filtration pump by a pipeline. The upper oil phase outlet of the water separation tank is connected to the melt crystallization purification system through a pipeline, and the lower water phase outlet is used to discharge the separated aqueous liquid. Among them, the high-level water tank is used to add raw water to the stirring kettle, and a mesh filter is installed at the bottom inside the stirring kettle.

[0022] The melt crystallization purification system includes a transfer pump, a melt crystallization tower with a jacket, a transition tank, a residue tank, a sweating tank, and a product tank. A heat exchange medium is introduced into the jacket outside the melt crystallization tower to control its temperature. The bottom outlet of the melt crystallization tower is divided into two paths and is respectively connected to the transition tank and the product tank through pipelines. The residue tank and the sweating tank are respectively connected to the bottom outlet of the transition tank through pipelines.

[0023] A sampling port with a sampling valve is also provided at the bottom of the melt crystallization tower.

[0024] The inlet of the transfer pump is divided into two paths and is respectively connected to the upper oil phase outlet of the water separation tank and the bottom circulating liquid outlet of the transition tank through pipelines. The outlet of the transfer pump is connected to the top inlet of the melt crystallization tower through a pipeline.

[0025] Control valves are provided on the corresponding pipelines.

[0026] The tower body of the melt crystallization tower is connected with a heat exchange system. The inlet and outlet of the jacket outside the melt crystallization tower are respectively connected to the outlet and inlet of the heat exchange system through pipelines. The heat exchange medium in the jacket is provided by the heat exchange system for temperature control.

[0027] Compared with the prior art, the beneficial effects obtained by the present invention are as follows: Using a biological enzyme as a catalyst, the reaction conditions are mild, the reaction rate is fast, the reaction time is short, the use of acids and alkalis and the generation of waste salts are effectively avoided, which is relatively friendly to the environment and equipment and is suitable for industrial production; By adopting a negative pressure reaction condition and a water replenishment measure, the conversion rate of the reactant undecylenic acid methyl ester can be effectively improved; Using the melt crystallization process and device to purify the product can reduce energy consumption, improve the separation efficiency and product yield, and a high-purity product with a purity of more than 99% can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of a device for preparing and purifying undecylenic acid according to the present invention;

[0029] In the figure: 1 - high-level water tank; 1-1 valve; 1-2 flowmeter; 2 - stirring kettle; 2-1 stirring paddle; 2-2 mesh filter; 2-3 pressure gauge; 2-4 vent valve; 2-5 thermometer; 3 - condenser; 4 - condensate tank; 5 - filtration pump; 6 - water separation tank; 7 - transfer pump; 8 - melt crystallization tower; 9 - heat exchange system; 10 - transition tank; 11 - residue tank; 12 - sweating liquid tank; 13 - product tank. a - methyl undecylenate feed inlet; b - water feed inlet; c - bioenzyme feed inlet; d - gas outlet; e - condensate outlet; f - reaction liquid outlet; g - lower aqueous phase outlet; h - sampling port; i - residue outlet; kj - sweating liquid outlet; k - product outlet; l - circulating liquid outlet; m - transfer pump inlet. A - vacuum extraction port. Specific embodiments

[0030] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0031] Embodiment:

[0032] Control Figure 1 The device adopted for the process of preparing and purifying undecylenic acid according to the present invention includes a high-level water tank 1, a jacketed stirring kettle 2, a water separation tank 6, and a melt crystallization purification system. The top of the high-level water tank 1 is provided with a water feed inlet b. The bottom outlet of the high-level water tank 1 is connected to the water inlet at the top of the stirring kettle 2 through a valve 1-1 and a flowmeter 1-2. The top of the high-level water tank 1 and the top of the stirring kettle 2 are connected through a pipeline. The jacket outside the stirring kettle 2 is filled with a heat exchange fluid for heating it. Inside the stirring kettle 2, there is a stirring paddle 2-1 and a thermometer 2-5 for detecting the temperature of the liquid material. The top of the stirring kettle 2 is also provided with a methyl undecylenate feed inlet a, a bioenzyme feed inlet c, a gas outlet d, a pressure gauge 2-3, and a vent valve 2-4. A mesh filter 2-2 is installed at the bottom inside the stirring kettle 2.

[0033] The gas outlet d at the top of the stirring kettle 2 is connected to a condenser 3 and a condensate tank 4 in sequence through a pipeline. The bottom of the condensate tank 4 is provided with a condensate outlet e. The top of the condensate tank 4 is provided with a vacuum extraction port A and is connected to a vacuum pump through this vacuum extraction port A by a pipeline. The reaction liquid outlet f at the bottom of the stirring kettle 2 is connected to the water separation tank 6 through a filtration pump 5 by a pipeline. The upper oil phase outlet of the water separation tank 6 is connected to the melt crystallization purification system through a pipeline, and the lower aqueous phase outlet g is used to discharge the separated aqueous phase liquid.

[0034] Control Figure 1, the melt crystallization purification system includes a transfer pump 7, a melt crystallization tower 8 with a jacket, a transition tank 10, a residue tank 11, a sweating tank 12, and a product tank 13. The tower body of the melt crystallization tower 8 is connected to a heat exchange system 9. The inlet and outlet of the jacket outside the melt crystallization tower 8 are respectively connected to the outlet and inlet of the heat exchange system 9 through pipelines. The heat exchange medium in the jacket is provided with temperature control by the heat exchange system 9, and the heat exchange medium is introduced into the jacket outside the melt crystallization tower 8 to control its temperature.

[0035] The bottom outlet of the melt crystallization tower 8 is divided into two paths and is respectively connected to the transition tank 10 and the product tank 13 through pipelines. The residue tank 11 and the sweating tank 12 are respectively connected to the bottom outlet of the transition tank 10 through pipelines; a sampling port h with a sampling valve is also provided at the bottom of the melt crystallization tower 8. The inlet m of the transfer pump 7 is divided into two paths and is respectively connected to the upper oil phase outlet of the water separation tank 6 and the circulating liquid outlet l at the bottom of the transition tank 10 through pipelines. The outlet of the transfer pump 7 is connected to the top inlet of the melt crystallization tower 8 through a pipeline, and control valves are provided on the corresponding pipelines.

[0036] The bottoms of the residue tank 11, the sweating tank 12, and the product tank 13 are respectively provided with a residue outlet i, a sweating outlet j, and a product outlet k. The residue discharged from the residue outlet i is used as the raw material for hydrolysis to the methyl undecylenate feed port a; the sweating can be subsequently discharged from the sweating outlet j, enter the melt crystallization tower 8 through the inlet m of the transfer pump, and be recycled as the purification raw material. Specific Example 1

[0038] The immobilized lipase Lipozyme 435 was added to a stirred kettle with a jacket through a funnel. Water and methyl undecylenate were respectively added to the stirred kettle by pumps at a mass ratio of 4:1. The mass concentration of the enzyme in the liquid in the stirred kettle was 0.5%. The stirring motor was turned on to start stirring, and at the same time, a negative pressure of about 20 kPa was drawn through a vacuum pump. The jacket was heated until the temperature in the stirred kettle stabilized at 50 °C, and the reaction started. During the reaction, the water in the high-level water tank was controlled to be added to the stirred kettle with a jacket at a certain speed to keep the reaction liquid level at the starting liquid level. The methanol and water vapor generated during the reaction were condensed and collected, and then separated by rectification. Among them, methanol was recycled, and water was recycled as the hydrolysis raw material. After 8 hours of reaction, the acid value of the oil phase was analyzed to be 171 mgKOH / g (the theoretical acid value that the reaction could reach was 304 mgKOH / g), and the reaction conversion rate was 56%.

[0039] The liquid material after 8 hours of reaction is pumped from the bottom of the stirred tank with a mesh filter into the water separation tank through a filtration pump. After standing for liquid separation, the lower aqueous phase is pumped into the elevated tank for recycling by a circulation pump. The upper oil phase is pumped into the melt crystallization tower by a transfer pump at a certain flow rate. After the liquid material enters the melt crystallization tower, the heat exchange system is started to make the initial temperature of the melt crystallization tower 28 °C. Then, the melt crystallization tower cools down at a rate of 0.5 °C / h and keeps at 10 °C for 1 h. During this process, the liquid material is pumped out of the transition tank by a transfer pump and then enters the melt crystallization tower for circulating freezing. After keeping at 10 °C for 1 h, the unfrozen residual liquid is discharged into the residual liquid tank for hydrolysis reaction recycling. The crystalline substance in the melt crystallization tower is heated and sweated at a heating rate of 0.1 °C / h. The sweated liquid material is analyzed through the sampling port. When the content of undecylenic acid is below 99.5%, the sweat liquid is discharged into the sweat liquid tank for recycling. When the content of undecylenic acid is above 99.5%, the melted liquid material is transferred to the product tank. The final temperature of the heating and sweating is 20 - 22 °C. The crystalline substance in the melt crystallization tower is rapidly heated by adjusting the temperature of the heat exchange system, and the final temperature of the rapid heating is 28 °C, so that all the product liquid material is collected in the product tank. Finally, the purity of undecylenic acid obtained is greater than 99.5%, and the yield of undecylenic acid is 98%, with basically no loss. Specific Example 2

[0041] The immobilized lipase Lipozyme 435 is added to the jacketed stirred tank through a funnel. Water and methyl undecylenate are respectively added to the stirred tank through pumps at a mass ratio of 4:1. The mass concentration of the enzyme in the liquid material in the stirred tank is 0.5%. The stirring motor is turned on to start stirring, and at the same time, the negative pressure is pumped to about 5 kPa through a vacuum pump, and the jacket is heated until the temperature in the stirred tank is stable at 50 °C, and the reaction starts. Methanol and water vapor generated during the reaction are collected after condensation and then separated by rectification. Among them, methanol is recycled, and water is recycled as a hydrolysis raw material. After 8 hours of reaction, the acid value of the oil phase is analyzed to be 278 mgKOH / g (the theoretical acid value that the reaction can reach is 304 mgKOH / g), and the reaction conversion rate is 91%.

[0042] After 8 hours of reaction, the liquid material is pumped from the bottom of the stirred tank with a mesh filter into the water separation tank through a filter pump. After standing for liquid separation, the lower aqueous phase is pumped into the elevated tank for recycling by a circulation pump, and the upper oil phase is pumped into the melt crystallization tower by a transfer pump at a certain flow rate. After the liquid material enters the melt crystallization tower, start the heat exchange system to make the initial temperature of the melt crystallization tower 28 °C, and then the melt crystallization tower cools at a rate of 0.5 °C / h until it reaches 10 °C and is maintained for 1 h. During this process, the liquid material is pumped out of the transition tank by a transfer pump and then enters the melt crystallization tower for circulating freezing. After being maintained at 10 °C for 1 h, the unfrozen residual liquid is discharged into the residual liquid tank for hydrolysis reaction recycling. The crystalline substance in the melt crystallization tower is heated and sweated at a heating rate of 0.1 °C / h. The sweated liquid material is analyzed through the sampling port. When the content of undecylenic acid is below 99.5%, the sweat liquid is discharged into the sweat liquid tank for recycling. When the content of undecylenic acid is above 99.5%, the melted liquid material is transferred to the product tank, where the final temperature of the heating and sweating is 20 - 22 °C. The crystalline substance in the melt crystallization tower is rapidly heated by adjusting the temperature of the heat exchange system, and the final temperature of the rapid heating is 28 °C, so that all the product liquid material is collected in the product tank. Finally, the purity of undecylenic acid obtained is greater than 99.5%, the yield of undecylenic acid is 98%, and there is basically no loss. Specific Example 3

[0044] The immobilized lipase Lipozyme 435 is added to the stirred tank with a jacket through a funnel. Water and methyl undecylenate are respectively added to the stirred tank by pumps at a mass ratio of 4:1. The mass concentration of the enzyme in the liquid material in the stirred tank is 0.5%. Turn on the stirring motor to start stirring, and at the same time, draw a negative pressure of about 5 kPa through a vacuum pump, and heat the jacket until the temperature in the stirred tank is stable at 50 °C, and then start the reaction. During the reaction, control the water in the elevated water tank and add it to the stirred tank with a jacket at a certain speed to keep the reaction liquid level at the starting liquid level. The methanol and water vapor generated during the reaction are collected after condensation and then separated by rectification. Among them, methanol is recycled, and water is recycled as a hydrolysis raw material. After 8 hours of reaction, the acid value of the oil phase is analyzed to be 295 mgKOH / g (the theoretical acid value that the reaction can reach is 304 mgKOH / g), and the reaction conversion rate is 97%.

[0045] The liquid material after 8 hours of reaction is filtered and then transferred to a rectification kettle, and rectified under the condition of a negative pressure of about 100 Pa and discharged at a reflux ratio of 6:1. When it reaches the boiling point of undecylenic acid, it is analyzed by GC. When the purity reaches 99%, it is collected in a new bottle. Finally, the purity of undecylenic acid obtained is greater than 99%, the yield of undecylenic acid is 90%, the yield is low, and side reactions occur to undecylenic acid. Specific Example 4

[0047] The immobilized lipase Lipozyme 435 was added to a jacketed stirred tank through a funnel. Water and methyl undecylenate were respectively pumped into the stirred tank at a mass ratio of 4:1. The mass concentration of the enzyme in the liquid in the stirred tank was 0.5%. The stirring motor was turned on to start stirring, and at the same time, a negative pressure of about 5 kPa was drawn through a vacuum pump. The jacket was heated until the temperature in the stirred tank stabilized at 50 °C, and the reaction started. During the reaction, the water in the high-level water tank was controlled to be added to the jacketed stirred tank at a certain speed to keep the reaction liquid level at the starting level. Methanol and water vapor generated during the reaction were condensed and collected, and then separated by rectification. Among them, methanol was recycled, and water was recycled as a hydrolysis raw material. After 8 hours of reaction, the acid value of the oil phase was analyzed to be 295 mg KOH / g (the theoretical acid value that the reaction could reach was 304 mg KOH / g), and the reaction conversion rate was 97%.

[0048] The liquid after 8 hours of reaction was pumped from the bottom of the stirred tank with a mesh filter into a water separation tank through a filter pump. After standing and separating, the lower aqueous phase was pumped into the high-level tank for recycling by a circulation pump, and the upper oil phase was pumped into a melt crystallization tower at a certain flow rate by a transfer pump. After the liquid entered the melt crystallization tower, the heat exchange system was started to make the initial temperature of the melt crystallization tower 28 °C, and then the melt crystallization tower was cooled at a rate of 3 °C / h. After cooling to 10 °C, it was maintained for 1 h. During this process, the liquid was pumped out of the transition tank through a transfer pump and then entered the melt crystallization tower for circulating freezing. After maintaining at 10 °C for 1 h, the unfrozen residual liquid was discharged into the residual liquid tank for recycling in the hydrolysis reaction. The crystalline substance in the melt crystallization tower was heated at a rate of 0.1 °C / h for sweating. The liquid for sweating was analyzed through a sampling port. When the content of undecylenic acid was below 99.5%, the sweating liquid was discharged into the sweating liquid tank for recycling. When the content of undecylenic acid was above 99.5%, the melted liquid was transferred to the product tank. The final temperature for the heating of sweating was 20 - 22 °C. The crystalline substance in the melt crystallization tower was rapidly heated by adjusting the temperature of the heat exchange system, and the final temperature for the rapid heating was 28 °C, so that all the product liquid was collected in the product tank. Finally, the purity of undecylenic acid obtained was 98%, and the yield of undecylenic acid was 97%. Specific Example 5

[0050] The immobilized lipase Lipozyme 435 was added to a jacketed stirred tank through a funnel. Water and methyl undecylenate were respectively pumped into the stirred tank at a mass ratio of 4:1. The mass concentration of the enzyme in the liquid in the stirred tank was 0.5%. The stirring motor was turned on to start stirring. At the same time, a negative pressure of about 5 kPa was drawn through a vacuum pump, and the jacket was heated until the temperature in the stirred tank stabilized at 50 °C, and then the reaction started. During the reaction, the water in the high-level water tank was controlled to be added to the jacketed stirred tank at a certain speed to keep the reaction liquid level at the initial level. The methanol and water vapor generated during the reaction were collected after condensation and then separated by rectification. Among them, methanol was recycled, and water was recycled as a hydrolysis raw material. After 8 hours of reaction, the acid value of the oil phase was analyzed to be 295 mgKOH / g (the theoretical acid value that the reaction could reach was 304 mgKOH / g), and the reaction conversion rate was 97%.

[0051] The liquid after 8 hours of reaction was pumped from the bottom of the stirred tank with a mesh filter into a water separation tank through a filter pump. After standing and liquid separation, the lower aqueous phase was pumped into the high-level tank for recycling by a circulating pump, and the upper oil phase was pumped into a melt crystallization tower at a certain flow rate by a transfer pump. After the liquid entered the melt crystallization tower, the heat exchange system was started to make the initial temperature of the melt crystallization tower 28 °C, and then the melt crystallization tower was cooled at a rate of 0.5 °C / h. After cooling to 10 °C, it was maintained for 1 h. During this process, the liquid was pumped from the transition tank through a transfer pump and then entered the melt crystallization tower for circulating freezing. After being maintained at 10 °C for 1 h, the unfrozen residual liquid was discharged into the residual liquid tank for recycling in the hydrolysis reaction. Without temperature raising and sweating, the product was directly obtained by rapid temperature raising, and the final temperature of the rapid temperature raising was 28 °C. Finally, the purity of undecylenic acid was 96%, and the yield of undecylenic acid was 95%. Specific Example 6

[0053] The immobilized lipase Lipozyme 435 was added to a jacketed stirred tank through a funnel. Water and methyl undecylenate were respectively pumped into the stirred tank at a mass ratio of 4:1. The mass concentration of the enzyme in the liquid in the stirred tank was 0.5%. The stirring motor was turned on to start stirring. At the same time, a negative pressure of about 5 kPa was drawn through a vacuum pump, and the jacket was heated until the temperature in the stirred tank stabilized at 50 °C, and then the reaction started. During the reaction, the water in the high-level water tank was controlled to be added to the jacketed stirred tank at a certain speed to keep the reaction liquid level at the initial level. The methanol and water vapor generated during the reaction were collected after condensation and then separated by rectification. Among them, methanol was recycled, and water was recycled as a hydrolysis raw material. After 8 hours of reaction, the acid value of the oil phase was analyzed to be 295 mgKOH / g (the theoretical acid value that the reaction could reach was 304 mgKOH / g), and the reaction conversion rate was 97%.

[0054] The liquid material after 8 hours of reaction is pumped from the bottom of the stirred kettle with a mesh filter into the water separation tank through a filter pump. After standing for liquid separation, the lower aqueous phase is pumped into the elevated tank for recycling by a circulating pump, and the upper oil phase is pumped into the melt crystallization tower by a transfer pump at a certain flow rate. After the liquid material enters the melt crystallization tower, the heat exchange system is started to make the initial temperature of the melt crystallization tower 28°C, and then the melt crystallization tower is cooled at a rate of 0.5°C / h until it reaches 10°C and is maintained for 1 h. During this process, the liquid material is pumped out of the transition tank by a transfer pump and then enters the melt crystallization tower for cyclic freezing. After being maintained at 10°C for 1 h, the unfrozen residual liquid is discharged into the residual liquid tank for use in the hydrolysis reaction cycle. The crystalline material in the melt crystallization tower is heated and sweated at a heating rate of 0.1°C / h. The sweating liquid material is analyzed through the sampling port. When the content of undecylenic acid is below 99.5%, the sweating liquid is discharged into the sweating liquid tank for recycling; when the content of undecylenic acid is above 99.5%, the melted liquid material is transferred to the product tank, and the final temperature of the heating and sweating is 20 - 22°C. The crystalline material in the melt crystallization tower is rapidly heated by adjusting the temperature of the heat exchange system, and the final temperature of the rapid heating is 28°C, so that all the product liquid material is collected in the product tank. Finally, the purity of undecylenic acid obtained is greater than 99.5%, and the yield of undecylenic acid is 98%, with basically no loss.

[0055] The content described in this specification is only an enumeration of the implementation forms of the inventive concept, and the protection scope of the present invention should not be regarded as limited to the specific forms stated in the embodiments.

Claims

1. A process for preparing and purifying undecylenic acid, characterized in that It includes the following steps: 1) Methyl undecylenate, water and biocatalyst are respectively added into the jacketed stirring kettle (2) from the methyl undecylenate feed port (a), the elevated water tank (1) and the biocatalyst feed port (c) in a certain proportion; start the stirring paddle (2-1) of the stirring kettle (2) to stir and mix the liquid materials. 2) Evacuate through the vacuum port (A) to make the reaction system proceed under negative pressure conditions, and heat the jacketed reaction kettle (2). After reaching the reaction temperature, keep it constant temperature and carry out stirring reaction. 3) As the reaction proceeds, water and methanol vapor are discharged from the gas outlet (d), condensed by the condenser (3) and collected in the condensate tank (4), and then sent to the rectification separation from the condensate outlet (e) to recover methanol, and the recovered water is sent from the water feed port (b) to the elevated water tank (1) for recycling; during the reaction, water is supplemented from the elevated water tank (1) into the jacketed stirring kettle (2) to keep the liquid level of the reaction liquid materials at the initial state. 4) After the reaction is completed, the liquid material is filtered and pumped into the water separation tank (6) through the reaction liquid outlet (f) at the bottom of the stirring kettle (2); after standing and separating, the aqueous phase is discharged from the lower layer liquid outlet (g) at the bottom of the water separation tank (6) and sent to the elevated water tank (1) as the raw material water for the hydrolysis of methyl undecylenate for standby; the upper oil phase is subjected to melt crystallization purification treatment to obtain the purified undecylenic acid product.

2. The process for preparing and purifying undecylenic acid according to claim 1, characterized in that The mass ratio of the reaction raw material water to methyl undecylenate is 3-6:

1.

3. A process for preparing and purifying undecylenic acid as claimed in claim 1, characterized in that The mass concentration of the biocatalyst in the reaction liquid materials is 0.5-20%, preferably 0.5-5%.

4. A process for preparing and purifying undecylenic acid as claimed in claim 1, characterized in that The biocatalyst is at least one of solid enzyme and liquid enzyme. The biocatalyst is mainly lipase, and the lipase is an esterase that can catalyze the hydrolysis of the ester bond of grease.

5. A process for preparing and purifying undecylenic acid as claimed in claim 1, characterized in that The negative pressure condition in the reaction system is that the pressure is maintained at 1-20 kPa, preferably 4-10 kPa, the reaction temperature is 40-60 °C, and the reaction time is 6-10 hours.

6. A process for preparing and purifying undecylenic acid as claimed in claim 1, characterized in that The melt crystallization purification treatment includes the following steps: S1: Input the upper oil phase into the melt crystallization tower (8), start the heat exchange system (9), control the temperature of the melt crystallization tower (8) to be stable at 26-30 °C, and then cool down at a certain rate. During this process, the liquid material in the melt crystallization tower (8) is discharged through the transition tank (10) and transported back to the melt crystallization tower (8) by the transfer pump (7) for circulating freezing. After the above cooling reaches the final temperature of 8-12 °C, keep it for 0.5-2 h. At this time, the unfrozen residual liquid is discharged into the residual liquid tank (11) through the transition tank (10), and is discharged from the residual liquid outlet (i) at the bottom of the residual liquid tank (11) as the raw material for hydrolysis and sent to the stirring kettle (2) for recycling. S2: Heat up the crystalline substance in the melt crystallization tower (8) at a certain rate for sweating. Take samples from the sampling port (h) at the bottom of the melt crystallization tower (8), and analyze the sweating liquid. When the content of undecylenic acid is below 99% - 99.5%, discharge the sweating liquid into the sweating liquid tank (12). Subsequently, it can be sent from the sweating liquid outlet (j) at the bottom of the sweating liquid tank (12) to the melt crystallization tower (8) through a transfer pump as a purification raw material for purification recycling. When the content of undecylenic acid is above 99% - 99.5%, transfer the melted liquid to the product tank (13). S3: Finally, quickly heat up the crystalline substance in the melt crystallization tower (8) by adjusting the temperature of the heat exchange system (9) to completely melt it to obtain a product liquid, which is collected in the product tank (13) and discharged and collected through the product outlet (k) at the bottom of the product tank (13).

7. A process for preparing and purifying undecylenic acid according to claim 6, characterized in that The cooling rate in step S1 is 0.5 - 2 °C / h, the final cooling temperature is 8 - 10 °C, and the holding time at the final cooling temperature is 1 - 1.5 h. The heating rate for sweating in step S2 is 0.1 - 1 °C / h, preferably 0.1 - 0.5 °C / h, the final heating temperature for sweating is 18 - 23 °C, preferably 20 - 22 °C. The final temperature for rapid heating in step S3 is 26 - 30 °C.

8. An apparatus for a process of preparing and purifying undecylenic acid as claimed in claim 1, characterized in that It includes a high-level water tank (1), a stirring kettle (2), a water separation tank (6), and a melt crystallization purification system. The top and bottom of the high-level water tank (1) are respectively connected to the top of the stirring kettle (2). A heat exchange fluid is introduced into the jacket outside the stirring kettle (2) for heating it. A stirring paddle (2-1) is provided inside the stirring kettle (2). An undecylenic acid methyl ester feed port (a) and a biological enzyme feed port (c) are also provided at the top of the stirring kettle (2). The gas outlet (d) at the top of the stirring kettle (2) is connected to a condenser (3) and a condensate tank (4) in sequence through a pipeline. A vacuum extraction port (A) is provided at the top of the condensate tank (4). The reaction liquid outlet (f) at the bottom of the stirring kettle (2) is connected to the water separation tank (6) through a filtration pump (5) by a pipeline. The upper oil phase outlet of the water separation tank (6) is connected to the melt crystallization purification system through a pipeline, and the lower water phase outlet (g) is used to discharge the separated water phase liquid. Among them, the high-level water tank is used to add raw water to the stirring kettle, and a mesh filter (2-2) is installed at the bottom inside the stirring kettle (2).

9. The device according to claim 8, characterized in that The melt crystallization purification system includes a transfer pump (7), a melt crystallization tower (8) with a jacket, a transition tank (10), a residue tank (11), a sweating liquid tank (12), and a product tank (13). A heat exchange medium is introduced into the jacket outside the melt crystallization tower (8) to control its temperature. The bottom outlet of the melt crystallization tower (8) is divided into two paths and is respectively connected to the transition tank (10) and the product tank (13) through pipelines. The residue tank (11) and the sweating liquid tank (12) are respectively connected to the bottom outlet of the transition tank (10) through pipelines. A sampling port (h) with a sampling valve is also provided at the bottom of the melt crystallization tower (8). The inlet (m) of the transfer pump (7) is divided into two paths and is respectively connected to the upper oil-phase outlet of the water separation tank (6) and the bottom circulating liquid outlet (l) of the transition tank (10) through pipelines. The outlet of the transfer pump (7) is connected to the top inlet of the melt crystallization tower (8) through a pipeline. Control valves are provided on the corresponding pipelines.

10. The device according to claim 9, characterized in that The tower body of the melt crystallization tower (8) is connected with a heat exchange system (9). The inlet and outlet of the jacket on the outside of the melt crystallization tower (8) are respectively connected to the outlet and inlet of the heat exchange system (9) through pipelines. The heat exchange medium in the jacket is controlled by the heat exchange system (9).

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