Purification method of 1, 2-epoxyhexane

Abstract

The invention provides a method for purifying 1, 2-epoxyhexane, which comprises the following steps: rectifying a 1, 2-epoxyhexane crude product through a dividing wall rectifying tower to obtain a 1, 2-epoxyhexane product; wherein the dividing wall rectifying tower is a middle dividing wall; the pressure of the top of the dividing wall rectifying tower is 6-15kPa, the temperature of the top of the dividing wall rectifying tower is-10-25 DEG C, and the pressure drop of the whole tower is 2-15kPa; the temperature of the tower bottom is 70-105 DEG C, and the reflux ratio of the tower top is 1.1-2.0; the 1, 2-epoxyhexane crude product is obtained by carrying out a catalytic reaction on 1-hexene through a Ti-Beta molecular sieve. By adopting the vacuum dividing wall rectifying tower, the energy consumption is reduced to the greatest extent, and the purified 1, 2-epoxyhexane product is high in purity and high in yield.

Description

Technical Field

[0001] The present invention relates to the technical field of purification of alkylene oxides, and in particular to a method for purifying 1,2-epoxyhexane. Background Art

[0002] 1,2-Epoxyhexane, also known as butyl ethylene oxide, is a colorless liquid at room temperature and pressure. It is a high value-added organic synthesis intermediate, mainly used in the synthesis of polyether polyols, non-ionic surfactants, 1,2-hexanediol and demulsifiers. Among them, polyether polyols are important raw materials for the synthesis of polyurethane foams, thermal insulation materials, elastomers, adhesives and coatings, and various non-ionic surfactants can be widely used in the petroleum, chemical, pesticide, daily chemical, textile and other industries; 1,2-hexanediol, the hydrolysis product of 1,2-epoxyhexane, is also an important fine chemical raw material. It is miscible with water and can be mixed with a variety of organic compounds in any proportion. It has antibacterial and antiseptic activity and can be used in the synthesis of inks for color inkjet printers, high-end cosmetics and pharmaceutical industries.

[0003] Traditional olefin epoxidation methods mainly include peracid method, halogen alcohol method and co-oxidation method, all of which have serious environmental pollution, high production cost and complex process. Ti-molecular sieve has excellent catalytic performance for olefin epoxidation reaction with dilute H2O2 as oxidant, so it is also widely used. 1-Hexene reacts in acetonitrile under the catalysis of dilute H2O2 and Ti-Beta molecular sieve, and the obtained crude 1,2-epoxyhexane usually contains impurities such as water, hexene, n-valeraldehyde, hydrogen peroxide, etc. Since 1,2-epoxyhexane is sensitive to high temperature, the reaction is complex under high temperature conditions and the stability is poor; at the same time, the solvent system is acetonitrile system, acetonitrile and water will produce azeotropic phenomenon during separation, and the by-product n-valeraldehyde and water have similar boiling points, which makes separation difficult and the purity of 1,2-epoxyhexane product is low. The traditional method of purifying alkylene oxide usually uses multiple distillation towers in series to further purify the product. This process is not only long in process, high in equipment investment, and high in energy consumption, but also not suitable for the purification of 1,2-epoxyhexane with a higher boiling point. Most existing purification methods are not suitable for the purification of crude 1,2-epoxyhexane produced by the catalytic reaction of 1-hexene with Ti-Beta molecular sieve, or the purity of the purified 1,2-epoxyhexane product can only reach 96% at most and cannot be further improved, and the yield of 1,2-epoxyhexane is low.

[0004] For example, US Patent Document US3987065 and Chinese Patent Document CN102762266A respectively disclose a new alkylene oxide purification technology, in which alkylene oxide is added to a solution of a high boiling point solvent and butyl lithium and reacted at ambient temperature, impurities easily react with butyl lithium, and then low boiling point alkylene oxide is easily distilled out from the high boiling point solvent solution to obtain a polymerization grade alkylene oxide compound. However, the technique requires the use of butyl lithium, which is highly flammable and irritating, and is not conducive to large-scale use; in addition, the method is more suitable for use with crude alkylene oxides with high purity and only specific trace impurities.

[0005] US Patent Document US49187290, Chinese Patent Documents CN112010823A, CN109851591A and CN112851601A all disclose purification methods of multiple extraction and distillation, which can purify crude alkylene oxides of C4 and below to above 99.9% to obtain polymerization-grade alkylene oxide raw materials. However, the purification of alkylene oxides by connecting multiple distillation towers in series not only has a long process flow and high energy consumption, but also it is difficult to remove impurities from alkylene oxides of C5 and above with a higher boiling point using currently commonly used extractants, and this method is not suitable for the purification and removal of impurities of hexylene oxide.

[0006] Chinese patent document CN116063249A discloses a purification method for alkylene oxides with a carbon number of C5 or above, which firstly distills the product to obtain a crude alkylene oxide product, adsorbs the crude alkylene oxide product to obtain an adsorbed crude alkylene oxide product, and then distills the adsorbed crude alkylene oxide product twice to obtain an alkylene oxide product with a concentration of more than 99.5%. However, the purification method adopts a method combining distillation and adsorption, and the process is relatively complicated, the loss of alkylene oxide is large, and the recovery rate is low.

[0007] Chinese patent document CN109851583B discloses a method for purifying alkylene oxide, comprising the following steps: a) a crude product stream containing alkylene oxide enters a first separation tower, a first light component impurity stream is obtained at the top of the tower, and a first stream is obtained at the bottom of the tower; b) the first stream enters a second separation tower, a second stream is obtained at the top of the tower, and a first heavy component impurity stream is obtained at the bottom of the tower; c) the second stream and an extractant stream enter a third separation tower, a second light component impurity stream is obtained at the top of the tower, and a crude extractant stream is obtained at the bottom of the tower; d) the crude extractant stream enters a fourth separation tower having a first reboiler, an alkylene oxide product is obtained at the top of the tower, and a fourth stream is obtained at the bottom of the tower; e) at least a portion of the fourth stream enters an extractant purifier to obtain a gaseous light component stream and a second heavy component impurity stream; the gaseous light component stream returns to the fourth separation tower; f) optionally, the first heavy component impurity stream and the second heavy component impurity stream enter a subsequent process. However, the purification of alkylene oxide by connecting multiple separation towers in series not only has a long process flow and high energy consumption, but also it is difficult to remove impurities from C5 and above alkylene oxides with higher boiling points using currently commonly used extractants. This method is not suitable for the purification and impurity removal of hexylene oxide.

[0008] In summary, developing a method for purifying 1,2-epoxyhexane with high product purity, high yield and low energy consumption is a technical problem that needs to be solved urgently. Summary of the invention

[0009] In view of this, the present invention provides a method for purifying 1,2-epoxyhexane, which adopts an intermediate-type dividing wall tower for distillation, and combined with the parameters such as the pressure and temperature of the dividing wall distillation tower, can directly obtain a 1,2-epoxyhexane product with a purity greater than 99% and a recovery rate greater than 98%. Not only does it simplify the overall process, it also has the advantages of low energy consumption and high thermodynamic efficiency.

[0010] To achieve the above object, the present invention adopts the following technical solution:

[0011] A method for purifying 1,2-epoxyhexane comprises the following steps:

[0012] The crude 1,2-epoxyhexane product is distilled in a distillation tower to obtain a 1,2-epoxyhexane product;

[0013] Wherein, the distillation tower next door is a middle partition;

[0014] The top pressure of the distillation tower is 6-15 kPa; the top temperature is -10-25°C (to ensure that 1,2-epoxyhexane will not be thermally decomposed), the pressure drop of the whole tower is 2-15 kPa; the bottom temperature is 70-105°C, and the reflux ratio is 1.1-2.0;

[0015] The crude 1,2-epoxyhexane product is obtained by catalytic reaction of 1-hexene with Ti-Beta molecular sieve, and the crude 1,2-epoxyhexane product contains impurities such as 1,2-epoxyhexane, acetonitrile, n-valeraldehyde, water, hexene, hexylene glycol and hydrogen peroxide. Generally, in terms of mass percentage, in the crude 1,2-epoxyhexane product obtained by catalytic reaction of 1-hexene with Ti-Beta molecular sieve, the mass ratio of acetonitrile to 1,2-epoxyhexane is (14-22):1, preferably (16-20):1; wherein the mass ratio of 1,2-epoxyhexane, water and 1-hexene is (5-6):(9-15):(2-4), and the mass ratio of the total amount of n-valeraldehyde and hexylene glycol to the crude 1,2-epoxyhexane product is about 0.8‰ to 1.5‰.

[0016] Optionally, in the method for purifying 1,2-epoxyhexane provided by the present invention, the interior of the distillation tower next door is divided into a common distillation section, a pre-fractionation section, a main tower section and a common stripping section; the crude 1,2-epoxyhexane enters the distillation tower next door through the pre-fractionation section, and the 1,2-epoxyhexane product is discharged from the middle side line of the main tower section; the heavy component (component containing hexanediol) is discharged from the bottom of the distillation tower next door (i.e., the bottom of the common stripping section).

[0017] Optionally, in the dividing wall distillation tower in the purification method of 1,2-epoxyhexane provided by the present invention, the theoretical number of plates of the pre-fractionation section and the main tower section are 5 to 25 respectively; the theoretical number of plates of the common distillation section and the common stripping section are 5 to 15 respectively.

[0018] Optionally, the method for purifying 1,2-epoxyhexane provided by the present invention further comprises the step of separating the light components (including acetonitrile and hexene, etc.) obtained at the top of the common distillation section in an extractive distillation tower under the action of an extractant to obtain a mixture containing acetonitrile, hexene and water (discharged from the top of the extractive distillation tower) and a mixture containing an extractant and water (discharged from the bottom of the extractive distillation tower);

[0019] The mixture containing acetonitrile, hexene and water has an acetonitrile content of 90 wt% to 98 wt%, a hexene content of 3 wt% to 4.5 wt%, and a water content of 1 wt% to 3 wt%.

[0020] Optionally, in the method for purifying 1,2-epoxyhexane provided by the present invention, the extractant is selected from ethylene glycol, glycerol or N,N-dimethylformamide;

[0021] The mass ratio of the light component obtained from the top of the distillation tower to the extractant is 1:0.5-1.5.

[0022] Optionally, in the method for purifying 1,2-epoxyhexane provided by the present invention, the top pressure of the extractive distillation tower is atmospheric pressure, the top temperature is 50-60° C., the bottom temperature is 121-290° C., and the number of theoretical plates is 25-40.

[0023] Optionally, in the method for purifying 1,2-epoxyhexane provided by the present invention, the light component obtained from the top of the next-door distillation tower enters the extractive distillation tower from the upper middle section of the extractive distillation tower, and the extractant enters the extractive distillation tower from the bottom of the extractive distillation tower; preferably, the light component enters from the 20th to 30th theoretical plates of the extractive distillation tower, and the extractant enters from the 3rd to 6th theoretical plates of the extractive distillation tower; the reflux ratio of the extractive distillation tower is 1.1 to 1.4.

[0024] Optionally, in the method for purifying 1,2-epoxyhexane provided by the present invention, the mixture containing the extractant and water is regenerated in a regeneration tower to obtain a regenerated extractant which is circulated into the extractive distillation tower, and the purity of the regenerated extractant is above 98%.

[0025] Optionally, in the method for purifying 1,2-epoxyhexane provided by the present invention, excess water and other impurities (n-valeraldehyde and a small amount of solvent) in the mixture containing the extractant and water are discharged from the top of the regeneration tower, and the purified and regenerated extractant is obtained at the bottom of the tower and circulated into the extractive distillation tower for cyclic extractive distillation.

[0026] Optionally, in the method for purifying 1,2-epoxyhexane provided by the present invention, the theoretical plate number of the regeneration tower is 12 to 40, the reflux ratio is 1 to 1.4, the atmospheric pressure, the top temperature is 100°C, and the bottom temperature is 153 to 290°C; preferably, the theoretical plate number of the regeneration tower is 15 to 35, and the reflux ratio is 1.1 to 1.2.

[0027] The mixture containing the extractant and water enters the regeneration tower from the 8th to 16th theoretical plates.

[0028] Optionally, in the method for purifying 1,2-epoxyhexane provided by the present invention, the purity of the 1,2-epoxyhexane product is above 99%, and the yield is above 98%.

[0029] Optionally, the purification method of 1,2-epoxyhexane provided by the present invention uses a device including a distillation tower, an extractive distillation tower and a regeneration tower connected in sequence with a middle distillation wall; the purification method comprises the following steps:

[0030] The crude 1,2-epoxyhexane product enters the diverting tower from the pre-fractionation section for distillation separation, and the light components containing acetonitrile and water are discharged from the common distillation section, thereby separating the solvent and the product; the 1,2-epoxyhexane product is discharged from the middle side line of the main tower section; the heavy components containing hexanediol and hydrogen peroxide are discharged from the bottom of the common stripping section;

[0031] The light component enters the extractive distillation tower from the middle and upper section of the extractive distillation tower, and is mixed with the extractant entering from the bottom of the extractive distillation tower for distillation and extraction. The mixture containing acetonitrile, hexene and water discharged from the top of the extractive distillation tower can separate the acetonitrile and hexene therein through subsequent treatment and be recycled respectively; the mixture containing the extractant and water and other impurities discharged from the bottom of the extractive distillation tower enters the regeneration tower from the middle side line of the regeneration tower to regenerate the extractant, and excess water and other component impurities are removed from the top of the regeneration tower, and the regenerated and purified extractant is obtained from the bottom of the regeneration tower and enters the extractive distillation tower through the bottom of the extractive distillation tower for recycling;

[0032] The top pressure of the distillation tower is 6-15 kPa; the top temperature is -10-25°C, the pressure drop of the whole tower is 2-15 kPa; the bottom temperature is 70-105°C, and the reflux ratio is 1.1-2.0;

[0033] The crude 1,2-epoxyhexane is obtained by catalyzing 1-hexene with Ti-Beta molecular sieve.

[0034] Optionally, in the purification method of 1,2-epoxyhexane provided by the present invention, the temperature of the top of the tower is controlled at -10 to 25 ° C by using a full condenser at the top of the distillation tower next door, and combined with other parameters, acetonitrile is discharged from the top of the distillation tower next door and enters the extractive distillation tower. Provide a guarantee. If the bottom temperature is too high, it will cause deviations in the separation of acetonitrile in the distillation tower next door, which will lead to the purity and yield of the 1,2-epoxyhexane product cannot be guaranteed. Therefore, in order to ensure the purity and yield of the 1,2-epoxyhexane product, it is necessary to strictly control the temperature conditions of the distillation tower next door. If the temperature is too low, a cryogenic refrigerant is required to cool the top components. The use of cryogenic refrigerants will greatly increase the operating costs, and will also increase the equipment material and increase investment; if the temperature is too high (above 60 ° C, especially above 100 ° C), the 1,2-epoxyhexane product will decompose, the purity will decrease, and the yield will decrease. By using a full condenser at the top of the distillation tower to cool the top stream of the distillation tower to -10 to 25°C, full condensation of the top of the tower under vacuum can be achieved without too low a temperature, thereby significantly reducing operating costs.

[0035] Optionally, in the purification method of 1,2-epoxyhexane provided by the present invention, the temperature of the top of the extractive distillation tower is controlled at 50-60°C by adopting a full condenser. The main difficulty of this extractive separation is how to ensure that the product ratio obtained at the top of the tower is appropriate to facilitate the subsequent recovery and reuse of hexene and acetonitrile. Therefore, the components obtained from the top of the extractive distillation tower need to maintain a high recovery rate of hexene and acetonitrile, wherein the hexene recovery rate is above 98%, preferably higher than 99.9%; the acetonitrile recovery rate is above 96%, preferably above 98%; the present invention can ensure the product ratio obtained at the top of the tower by controlling the amount of the extractant and the parameters of the extractive distillation tower, which is conducive to the subsequent process.

[0036] Optionally, in the method for purifying 1,2-epoxyhexane provided by the present invention, the top of the regeneration tower is a full condenser, and the components (water and other impurities) obtained at the top of the regeneration tower are no longer recycled. The purity of the regenerated extractant obtained at the bottom of the regeneration tower is above 98%, preferably above 99.8%, and can be directly fed into the extractive distillation tower for recycling.

[0037] Optionally, in the purification method of 1,2-epoxyhexane provided by the present invention, the tops of the partition wall distillation tower, the extractive distillation tower and the regeneration tower are provided with a heat exchanger and a top reflux tank, which can increase the liquid load on the top of the tower by controlling the condensation and reflux of the top of the tower, thereby improving the contact degree between the liquid and the gas near the top of the tower and improving the separation efficiency.

[0038] Optionally, in the purification method of 1,2-epoxyhexane provided by the present invention, the bottoms of the distillation tower, the extractive distillation tower and the regeneration tower are all provided with a reboiler, and the reboiler is selected from any one of a thermosyphon reboiler, a kettle reboiler or a forced circulation reboiler. The reboiler can help maintain the temperature and pressure in the tower stable, and at the same time, the reboiler can increase the chance of re-fractionation in the fractionation tower, thereby improving the purity of the obtained product and reducing unnecessary losses.

[0039] Compared with the prior art, the effects of the present invention are as follows:

[0040] Beneficial effect 1: The purification method of 1,2-epoxyhexane provided by the present invention is mainly aimed at separating and purifying crude 1,2-epoxyhexane generated by catalytic reaction of 1-hexene with Ti-Beta molecular sieve, and by using a distillation tower to replace the traditional distillation tower, the mixture obtained by catalytic reaction of 1-hexene with Ti-Beta molecular sieve is directly introduced into the distillation tower, and combined with limiting the operating pressure and temperature of the distillation tower, a high-purity 1,2-epoxyhexane product of more than 99% can be directly obtained from the middle section of the distillation tower, and the recovery rate of 1,2-epoxyhexane can reach more than 98%, while significantly reducing the energy consumption of the purification process and the investment cost of the equipment.

[0041] Beneficial effect 2: The purification method of 1,2-epoxyhexane provided by the present invention is to condense the light components obtained from the top of the distillation tower next door into the extractive distillation tower, and fully separate them under the action of a suitable extractant, and finally obtain a mixture of acetonitrile, hexene and water in a suitable proportion at the top of the extractive distillation tower. The mixture can be further separated to obtain high-purity raw material hexene and solvent acetonitrile for recycling, which not only shortens the process flow but also reduces costs. The contaminated extractant enters the regeneration tower through the bottom of the extractive distillation tower, and the purified extractant is obtained at the bottom of the regeneration tower, and circulates into the extractive distillation tower to participate in material extraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A purification device used in a method for purifying 1,2-epoxyhexane provided by the present invention;

[0043] Figure 2 These are two vacuum distillation devices connected in series used in Comparative Example 2 of the present invention.

[0044] Among them, 1, crude 1,2-epoxyhexane; 2, light components; 3, 1,2-epoxyhexane product; 4, heavy components; 5, overhead materials; 6, contaminated extractant; 7, impurities; 8, regenerated extractant; 9, fresh extractant; 10, mixed extractant; 12, light components of the first vacuum distillation tower; 13, heavy components of the first vacuum distillation tower; 14, light components of the second vacuum distillation tower; 15, heavy components of the second vacuum distillation tower;

[0045] A, next-wall distillation tower; B, E, H, M, B-1, E-1, heat exchanger; C, I, N, C-1, F-1, reflux tank; D, J, O, D-1, G-1, bottom reboiler; F, K, pump; G, extractive distillation tower; L, regeneration tower; P, mixer; Ⅰ, common distillation section; Ⅱ, pre-fractionation section; Ⅲ, main tower section; Ⅳ, common stripping section; A-1, A-2, vacuum distillation tower. DETAILED DESCRIPTION

[0046] The present invention is described in detail below by way of examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art in this field can make some non-essential improvements and adjustments to the present invention based on the above content of the present invention.

[0047] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0048] Example 1

[0049] This embodiment provides a method for purifying 1,2-epoxyhexane, using Figure 1 The purification device shown specifically comprises the following steps:

[0050] 1-Hexene is subjected to a catalytic reaction with Ti-Beta molecular sieve to obtain crude 1,2-epoxyhexane. After testing, the mass ratio of acetonitrile, 1,2-epoxyhexane, hydrogen peroxide, water and 1-hexene in the crude 1,2-epoxyhexane is 80:5:1:11:3; the total amount of 1,2-hexanediol and n-valeraldehyde accounts for 1‰ of the total mass of the crude 1,2-epoxyhexane.

[0051] (1) The above-mentioned 1,2-epoxyhexane crude product 1 at 60° C. is passed through the middle part (the 4th plate) of the pre-fractionation section II of the distillation tower A to enter the distillation tower A for separation, and the light components 2 (including acetonitrile, water, hexene and n-valeraldehyde, etc.) are separated from the main tower section III of the distillation tower A, and the light components 2 are discharged from the top of the distillation tower A (i.e., the top of the common distillation section I), and the intermediate component 1,2-epoxyhexane product 3 is discharged from the side line (the 5th plate) in the middle part of the main tower section III; the heavy components 4 (including hydrogen peroxide, etc.) are discharged from the bottom of the distillation tower A (i.e., the bottom of the common stripping section IV).

[0052] In the above separation process, the reflux ratio of the top of the distillation tower next door is 1.2, the operating pressure of the top of the tower is 10kPa, the top temperature is -10°C, the bottom temperature is 82°C, and the pressure drop of the whole tower is 6kPa. The top of the distillation tower next door is provided with a heat exchanger E and a reflux tank C, and a full condenser is realized by the heat exchanger E and the reflux tank C to control the temperature of the top of the tower. The bottom of the distillation tower next door is provided with a forced circulation reboiler D, and the stability of the bottom of the tower is controlled by the reboiler.

[0053] The pre-fractionation section of the adjacent distillation tower has 5 theoretical plates, the main tower section has 12 theoretical plates, and the common distillation section and the common stripping section each have 10 theoretical plates.

[0054] The acetonitrile in the light component discharged from the top of the tower accounts for 99.99wt% of the acetonitrile in the crude 1,2-epoxyhexane product. The purity of the 1,2-epoxyhexane product discharged from the side line in the middle of the main tower section is 99.2%, accounting for 98.3wt% of the 1,2-epoxyhexane in the crude 1,2-epoxyhexane product.

[0055] (2) After the light component 2 is heat exchanged in the heat exchanger E, it is introduced into an extractive distillation tower G having 32 tower plates from the 25th tower plate by means of a pump F. A mixed extractant 10 (ethylene glycol) is introduced into the extractive distillation tower G from the 3rd tower plate. The amount of the mixed extractant 10 is about 0.75 times that of the light component 2. Under the action of the mixed extractant 10, the light component 2 is separated at normal pressure, a tower top temperature of 55° C., a tower bottom temperature of 150° C., and a reflux ratio controlled at 1.3. The tower top material 5 discharged from the tower top contains acetonitrile, hexene, water and a small amount of n-valeraldehyde, wherein the mass ratio of acetonitrile, hexene, water to n-valeraldehyde is 94:3.5:2.4:0.1. The contaminated extractant 6 is discharged from the tower bottom.

[0056] The top of the extractive distillation tower G is provided with a heat exchanger M and a reflux tank I. The condensed liquid is partially refluxed to the top of the tower through the heat exchanger. This reflux liquid helps to improve the efficiency of distillation. The bottom of the tower is provided with a bottom reboiler J. Part of the bottom material is reintroduced into the reboiler, which can reduce the energy loss of reheating the outside of the tower and improve the overall energy utilization efficiency.

[0057] (3) After the contaminated extractant 6 is heated in the bottom reboiler J, it enters the regeneration tower L from the 8th tray (the regeneration tower has 18 trays in total) with the help of pump K. The reflux ratio is controlled to be 1.2. Impurities 7 such as water are discharged from the top of the regeneration tower L at normal pressure, a top temperature of 100°C, and a bottom temperature of 197°C. The regenerated extractant 8 is discharged from the bottom of the regeneration tower L and mixed with the fresh extractant 9 in the mixer P to form a mixed extractant 10, which is then circulated to the extractive distillation tower G.

[0058] The purity of the regenerated extractant 8 is 99.99%. Taking the total mass of the mixed extractant 10 added into the extractive distillation tower G as 100%, the recovery rate of the regenerated extractant 8 is 99.8%.

[0059] A heat exchanger M and a reflux tank N are provided at the top of the regeneration tower L. The condensed liquid is partially refluxed to the top of the tower through the heat exchanger. This reflux liquid helps to improve the efficiency of distillation. A bottom reboiler O is provided at the bottom of the regeneration tower L. Part of the bottom product is reintroduced into the reboiler, which can reduce the energy loss of reheating the outside of the tower and improve the overall energy utilization efficiency.

[0060] The top product obtained from the extractive distillation tower can discharge the by-product n-valeraldehyde to the maximum extent, which is beneficial to the subsequent reaction.

[0061] Example 2

[0062] This embodiment provides a method for purifying 1,2-epoxyhexane, which only uses Figure 1 The dividing wall distillation tower A shown in the figure specifically comprises the following steps:

[0063] 1-Hexene is subjected to a catalytic reaction with Ti-Beta molecular sieve to obtain crude 1,2-epoxyhexane. After testing, the mass ratio of acetonitrile, 1,2-epoxyhexane, hydrogen peroxide, water and 1-hexene in the crude 1,2-epoxyhexane is 82:5:1:9:3; the total amount of 1,2-hexanediol and n-valeraldehyde accounts for 1‰ of the total mass of the crude 1,2-epoxyhexane.

[0064] (1) The above-mentioned 1,2-epoxyhexane crude product 1 at 60° C. is passed through the middle part (the third plate) of the pre-fractionation section II of the distillation tower A to enter the distillation tower A for separation, and the light components 2 (including acetonitrile, water, hexene and n-valeraldehyde, etc.) are separated from the main tower section III of the distillation tower A, and the light components 2 are discharged from the top of the distillation tower A (i.e., the top of the common distillation section I), and the intermediate component 1,2-epoxyhexane product 3 is discharged from the side line (the third plate) in the middle part of the main tower section III; the heavy components 4 (including hydrogen peroxide, etc.) are discharged from the bottom of the distillation tower A (i.e., the bottom of the common stripping section IV).

[0065] In the above separation process, the reflux ratio of the top of the distillation tower next door is 1.8, the operating pressure of the top of the tower is 8kPa, the top temperature is -10°C, the bottom temperature is 100°C, and the pressure drop of the whole tower is 2kPa. The top of the distillation tower next door is provided with a heat exchanger E and a reflux tank C, and a full condenser is realized by the heat exchanger E and the reflux tank C to control the temperature of the top of the tower. The bottom of the distillation tower next door is provided with a forced circulation reboiler D, and the stability of the bottom of the tower is controlled by the reboiler.

[0066] The pre-fractionation section of the adjacent distillation tower has 6 theoretical plates, the main tower section has 8 theoretical plates, and the common distillation section and the common stripping section each have 8 theoretical plates.

[0067] The acetonitrile in the light component discharged from the top of the tower accounts for 99.99wt% of the acetonitrile in the crude 1,2-epoxyhexane product. The purity of the 1,2-epoxyhexane product discharged from the side line in the middle of the main tower section is 99%, accounting for 99.4wt% of the 1,2-epoxyhexane in the crude 1,2-epoxyhexane product.

[0068] Example 3

[0069] This embodiment provides a method for purifying 1,2-epoxyhexane, which only uses Figure 1 The dividing wall distillation tower A shown in the figure specifically comprises the following steps:

[0070] 1-Hexene is subjected to a catalytic reaction with Ti-Beta molecular sieve to obtain crude 1,2-epoxyhexane. After testing, the mass ratio of acetonitrile, 1,2-epoxyhexane, hydrogen peroxide, water and 1-hexene in the crude 1,2-epoxyhexane is 82:5:1:9:3; the total amount of 1,2-hexanediol and n-valeraldehyde accounts for 1‰ of the total mass of the crude 1,2-epoxyhexane.

[0071] (1) The above-mentioned 1,2-epoxyhexane crude product 1 at 60° C. is passed through the middle part (the third plate) of the pre-fractionation section II of the distillation tower A to enter the distillation tower A for separation, and the light components 2 (including acetonitrile, water, hexene and n-valeraldehyde, etc.) are separated from the main tower section III of the distillation tower A, and the light components 2 are discharged from the top of the distillation tower A (i.e., the top of the common distillation section I), and the intermediate component 1,2-epoxyhexane product 3 is discharged from the side line (the third plate) in the middle part of the main tower section III; the heavy components 4 (including hydrogen peroxide, etc.) are discharged from the bottom of the distillation tower A (i.e., the bottom of the common stripping section IV).

[0072] In the above separation process, the reflux ratio of the top of the distillation tower next door is 1.8, the operating pressure of the top of the tower is 8kPa, the top temperature is 10°C, the bottom temperature is 100°C, and the pressure drop of the whole tower is 2kPa. The top of the distillation tower next door is provided with a heat exchanger E and a reflux tank C, and a full condenser is realized by the heat exchanger E and the reflux tank C to control the temperature of the top of the tower. The bottom of the distillation tower next door is provided with a forced circulation reboiler D, and the stability of the bottom of the tower is controlled by the reboiler.

[0073] The pre-fractionation section of the adjacent distillation tower has 6 theoretical plates, the main tower section has 8 theoretical plates, and the common distillation section and the common stripping section each have 8 theoretical plates.

[0074] The acetonitrile in the light component discharged from the top of the tower accounts for 99.92wt% of the acetonitrile in the crude 1,2-epoxyhexane product. The purity of the 1,2-epoxyhexane product discharged from the side line in the middle of the main tower section is 98.8%, accounting for 99.5wt% of the 1,2-epoxyhexane in the crude 1,2-epoxyhexane product.

[0075] Example 4

[0076] This embodiment provides a method for purifying 1,2-epoxyhexane, which only uses Figure 1 The dividing wall distillation tower A shown in the figure specifically comprises the following steps:

[0077] 1-Hexene is subjected to a catalytic reaction with Ti-Beta molecular sieve to obtain crude 1,2-epoxyhexane. After testing, the mass ratio of acetonitrile, 1,2-epoxyhexane, hydrogen peroxide, water and 1-hexene in the crude 1,2-epoxyhexane is 82:5:1:9:3; the total amount of 1,2-hexanediol and n-valeraldehyde accounts for 1‰ of the total mass of the crude 1,2-epoxyhexane.

[0078] (1) The above-mentioned 1,2-epoxyhexane crude product 1 at 60° C. is passed through the middle part (the third plate) of the pre-fractionation section II of the distillation tower A to enter the distillation tower A for separation, and the light components 2 (including acetonitrile, water, hexene and n-valeraldehyde, etc.) are separated from the main tower section III of the distillation tower A, and the light components 2 are discharged from the top of the distillation tower A (i.e., the top of the common distillation section I), and the intermediate component 1,2-epoxyhexane product 3 is discharged from the side line (the third plate) in the middle part of the main tower section III; the heavy components 4 (including hydrogen peroxide, etc.) are discharged from the bottom of the distillation tower A (i.e., the bottom of the common stripping section IV).

[0079] In the above separation process, the reflux ratio of the top of the distillation tower next door is 1.8, the operating pressure of the top of the tower is 8kPa, the top temperature is 20°C, the bottom temperature is 100°C, and the pressure drop of the whole tower is 2kPa. The top of the distillation tower next door is provided with a heat exchanger E and a reflux tank C, and a full condenser is realized by the heat exchanger E and the reflux tank C to control the temperature of the top of the tower. The bottom of the distillation tower next door is provided with a forced circulation reboiler D, and the stability of the bottom of the tower is controlled by the reboiler.

[0080] The pre-fractionation section of the adjacent distillation tower has 6 theoretical plates, the main tower section has 8 theoretical plates, and the common distillation section and the common stripping section each have 8 theoretical plates.

[0081] The acetonitrile in the light component discharged from the top of the tower accounts for 99.85wt% of the acetonitrile in the crude 1,2-epoxyhexane product. The purity of the 1,2-epoxyhexane product discharged from the side line in the middle of the main tower section is 98.3%, accounting for 99.6wt% of the 1,2-epoxyhexane in the crude 1,2-epoxyhexane product.

[0082] Example 5

[0083] This embodiment provides a method for purifying 1,2-epoxyhexane, using Figure 1 The purification device shown specifically comprises the following steps:

[0084] 1-Hexene is subjected to a catalytic reaction with Ti-Beta molecular sieve to obtain crude 1,2-epoxyhexane. After testing, the mass ratio of acetonitrile, 1,2-epoxyhexane, hydrogen peroxide, water and 1-hexene in the crude 1,2-epoxyhexane is 85:6:1:9:3; the total amount of 1,2-hexanediol and n-valeraldehyde accounts for 1‰ of the total mass of the crude 1,2-epoxyhexane.

[0085] (1) The above-mentioned 1,2-epoxyhexane crude product 1 at 60° C. is passed through the middle part (the sixth plate) of the pre-fractionation section II of the distillation tower A to enter the distillation tower A for separation, and the light components 2 (including acetonitrile, water, hexene and n-valeraldehyde, etc.) are separated from the main tower section III of the distillation tower A, and the light components 2 are discharged from the top of the distillation tower A (i.e., the top of the common distillation section I), and the intermediate component 1,2-epoxyhexane product 3 is discharged from the side line in the middle part of the main tower section III (the sixth plate); the heavy components 4 (including hydrogen peroxide, etc.) are discharged from the bottom of the distillation tower A (i.e., the bottom of the common stripping section IV).

[0086] In the above separation process, the reflux ratio of the top of the distillation tower next door is 1.2, the operating pressure of the top of the tower is 15kPa, the top temperature is -10°C, the bottom temperature is 92°C, and the pressure drop of the whole tower is 8kPa. The top of the distillation tower next door is provided with a heat exchanger E and a reflux tank C, and a full condenser is realized by the heat exchanger E and the reflux tank C to control the temperature of the top of the tower. The bottom of the distillation tower next door is provided with a forced circulation reboiler D, and the stability of the bottom of the tower is controlled by the reboiler.

[0087] The pre-fractionation section of the adjacent distillation tower has 9 theoretical plates, the main tower section has 16 theoretical plates, and the common distillation section and the common stripping section each have 11 theoretical plates.

[0088] The acetonitrile in the light component discharged from the top of the tower accounts for 99.99wt% of the acetonitrile in the crude 1,2-epoxyhexane product. The purity of the 1,2-epoxyhexane product discharged from the side line in the middle of the main tower section is 99%, accounting for 98.6wt% of the 1,2-epoxyhexane in the crude 1,2-epoxyhexane product.

[0089] (2) After the light component 2 is heat exchanged in the heat exchanger E, it is introduced into an extractive distillation tower G having 36 trays from the 27th tray by means of a pump F. A mixed extractant 10 (N,N-dimethylformamide) is introduced into the extractive distillation tower G from the 5th tray. The amount of the mixed extractant 10 is about 1.2 times that of the light component 2. Under the action of the mixed extractant 10, the light component 2 is separated at normal pressure, a top temperature of 52° C., a bottom temperature of 121° C., and a reflux ratio controlled at 1.4. The top material 5 discharged from the top of the tower contains acetonitrile, hexene, water and a small amount of n-valeraldehyde, wherein the mass ratio of acetonitrile, hexene, water to n-valeraldehyde is 94.4:3.6:2:0.1. The contaminated extractant 6 is discharged from the bottom of the tower.

[0090] The top of the extractive distillation tower G is provided with a heat exchanger M and a reflux tank I. The condensed liquid is partially refluxed to the top of the tower through the heat exchanger. This reflux liquid helps to improve the efficiency of distillation. The bottom of the tower is provided with a bottom reboiler J. Part of the bottom product is reintroduced into the reboiler, which can reduce the energy loss of reheating the outside of the tower and improve the overall energy utilization efficiency.

[0091] (3) After the contaminated extractant 6 is heated in the bottom reboiler J, it enters the regeneration tower L from the 16th tray (the regeneration tower has 34 trays in total) with the help of pump K. The reflux ratio is controlled to be 1.4, the pressure is normal, the top temperature is 100°C, and the bottom temperature is 153°C. Impurities 7 such as water are discharged from the top of the regeneration tower L, and the regenerated extractant 8 is discharged from the bottom of the regeneration tower L and mixed with the fresh extractant 9 in the mixer P to form a mixed extractant 10, which is circulated to the extractive distillation tower G.

[0092] The purity of the regenerated extractant 8 is 99.99%. Taking the total mass of the mixed extractant 10 added into the extractive distillation tower G as 100%, the recovery rate of the regenerated extractant 8 is 99.9%.

[0093] A heat exchanger M and a reflux tank N are provided at the top of the regeneration tower L. The condensed liquid is partially refluxed to the top of the tower through the heat exchanger. This reflux liquid helps to improve the efficiency of distillation. A bottom reboiler O is provided at the bottom of the regeneration tower L. Part of the bottom product is reintroduced into the reboiler, which can reduce the energy loss of reheating the outside of the tower and improve the overall energy utilization efficiency.

[0094] Example 6

[0095] This embodiment provides a method for purifying 1,2-epoxyhexane, using Figure 1 The purification device shown specifically comprises the following steps:

[0096] 1-Hexene is subjected to a catalytic reaction with Ti-Beta molecular sieve to obtain crude 1,2-epoxyhexane. After testing, the mass ratio of acetonitrile, 1,2-epoxyhexane, hydrogen peroxide, water and 1-hexene in the crude 1,2-epoxyhexane is 78:5:1:13:3; the total amount of 1,2-hexanediol and n-valeraldehyde accounts for 1‰ of the total mass of the crude 1,2-epoxyhexane.

[0097] (1) The above-mentioned 1,2-epoxyhexane crude product 1 at 60° C. is passed through the middle part (at the 8th plate) of the pre-fractionation section II of the distillation tower A to enter the distillation tower A for separation, and the light components 2 (including acetonitrile, water, hexene and n-valeraldehyde, etc.) are separated from the main tower section III of the distillation tower A, and the light components 2 are discharged from the top of the distillation tower A (i.e., the top of the common distillation section I), and the intermediate component 1,2-epoxyhexane product 3 is discharged from the side line in the middle part of the main tower section III (at the 8th plate); the heavy components 4 (including hydrogen peroxide, etc.) are discharged from the bottom of the distillation tower A (i.e., the bottom of the common stripping section IV).

[0098] In the above separation process, the reflux ratio of the top of the distillation tower next door is 1.4, the operating pressure of the top of the tower is 15kPa, the top temperature is -10°C, the bottom temperature is 100°C, and the pressure drop of the whole tower is 15kPa. The top of the distillation tower next door is provided with a heat exchanger E and a reflux tank C, and a full condenser is realized by the heat exchanger E and the reflux tank C to control the temperature of the top of the tower. The bottom of the distillation tower next door is provided with a forced circulation reboiler D, and the stability of the bottom of the tower is controlled by the reboiler.

[0099] The pre-fractionation section of the adjacent distillation tower has 14 theoretical plates, the main tower section has 21 theoretical plates, and the common distillation section and the common stripping section each have 15 theoretical plates.

[0100] The acetonitrile in the light component discharged from the top of the tower accounts for 99.99wt% of the acetonitrile in the crude 1,2-epoxyhexane product. The purity of the 1,2-epoxyhexane product discharged from the side line in the middle of the main tower section is 99%, accounting for 99.1wt% of the 1,2-epoxyhexane in the crude 1,2-epoxyhexane product.

[0101] (2) After the light component 2 is heat exchanged in the heat exchanger E, it is introduced into an extractive distillation tower G having 34 trays from the 26th tray by means of a pump F. A mixed extractant 10 (glycerol) is introduced into the extractive distillation tower G from the 5th tray. The amount of the mixed extractant 10 is about 1.3 times that of the light component 2. Under the action of the mixed extractant 10, the light component 2 is separated at normal pressure, a top temperature of 52° C., a bottom temperature of 290° C., and a reflux ratio controlled at 1.1. The top material 5 discharged from the top of the tower contains acetonitrile, hexene, water and a small amount of n-valeraldehyde, wherein the mass ratio of acetonitrile, hexene, water to n-valeraldehyde is 93.8:4.2:2:0.1. The contaminated extractant 6 is discharged from the bottom of the tower.

[0102] The top of the extractive distillation tower G is provided with a heat exchanger M and a reflux tank I. The condensed liquid is partially refluxed to the top of the tower through the heat exchanger. This reflux liquid helps to improve the efficiency of distillation. The bottom of the tower is provided with a bottom reboiler J. Part of the bottom product is reintroduced into the reboiler, which can reduce the energy loss of reheating the outside of the tower and improve the overall energy utilization efficiency.

[0103] (3) After the contaminated extractant 6 is heated in the bottom reboiler J, it enters the regeneration tower L from the 8th tray (the regeneration tower has 16 trays in total) with the help of pump K. The reflux ratio is controlled to be 1.1, the pressure is normal, the top temperature is 100°C, and the bottom temperature is 290°C. Impurities 7 such as water are discharged from the top of the regeneration tower L, and the regenerated extractant 8 is discharged from the bottom of the regeneration tower L and mixed with the fresh extractant 9 in the mixer P to form a mixed extractant 10, which is circulated to the extractive distillation tower G.

[0104] The purity of the regenerated extractant 8 is 99.99%. Taking the total mass of the mixed extractant 10 added into the extractive distillation tower G as 100%, the recovery rate of the regenerated extractant 8 is 99.9%.

[0105] A heat exchanger M and a reflux tank N are provided at the top of the regeneration tower L. The condensed liquid is partially refluxed to the top of the tower through the heat exchanger. This reflux liquid helps to improve the efficiency of distillation. A bottom reboiler O is provided at the bottom of the regeneration tower L. Part of the bottom product is reintroduced into the reboiler, which can reduce the energy loss of reheating the outside of the tower and improve the overall energy utilization efficiency.

[0106] Comparative Example 1

[0107] The purification method of 1,2-epoxyhexane provided in this comparative example is similar to that in Example 1, except that some operating parameters of the distillation tower next door are different, and other parameters remain unchanged. The operating parameters of the distillation tower next door in this comparative example that are different from those in Example 1 are as follows:

[0108] (1) The operating pressure of the distillation tower is atmospheric pressure, the temperature at the top of the tower is 68°C, the temperature at the bottom of the tower is 118°C, and the reflux ratio at the top of the tower is 2.4.

[0109] In this comparative example, the acetonitrile in the light component finally discharged from the top of the distillation tower next door accounts for 87wt% of the acetonitrile in the crude 1,2-epoxyhexane. The 1,2-epoxyhexane product discharged from the side line in the middle of the main tower section of the distillation tower next door accounts for 86wt% of the 1,2-epoxyhexane in the crude 1,2-epoxyhexane, and the purity of the 1,2-epoxyhexane product is 72%. The 1,2-epoxyhexane discharged from the bottom of the distillation tower next door accounts for 4wt% of the 1,2-epoxyhexane in the crude 1,2-epoxyhexane.

[0110] (2) After the light component 2 is heat exchanged in the heat exchanger E, it is fed into an extractive distillation tower G having 32 plates from the 25th plate by means of a pump F. A mixed extractant 10 (ethylene glycol) is fed into the extractive distillation tower G from the 3rd plate. The amount of the mixed extractant 10 is about 0.75 times that of the light component 2. Under the action of the mixed extractant 10, the light component 2 is separated at normal pressure, a tower top temperature of 55° C., a tower bottom temperature of 150° C., and a reflux ratio controlled at 1.3. The tower top material 5 discharged from the tower top contains acetonitrile, hexene, water, and a small amount of n-valeraldehyde and 1,2-epoxyhexane, wherein the mass ratio of acetonitrile, hexene, water, n-valeraldehyde and 1,2-epoxyhexane is 93.6:4.1:2:0.1:0.2. The contaminated extractant 6 is discharged from the tower bottom.

[0111] The top of the extractive distillation tower G is provided with a heat exchanger M and a reflux tank I. The condensed liquid is partially refluxed to the top of the tower through the heat exchanger. This reflux liquid helps to improve the efficiency of distillation. The bottom of the tower is provided with a bottom reboiler J. Part of the bottom product is reintroduced into the reboiler, which can reduce the energy loss of reheating the outside of the tower and improve the overall energy utilization efficiency.

[0112] (3) After the contaminated extractant 6 is heated by the bottom reboiler J, it enters the regeneration tower L from the 8th tray (the regeneration tower has 18 trays in total) with the help of pump K, and the reflux ratio is controlled to be 1.2, the pressure is normal, the top temperature is 100°C, and the bottom temperature is 197°C. Impurities 7 such as water are discharged from the top of the regeneration tower L, and the regenerated extractant 8 is discharged from the bottom of the regeneration tower L, and is mixed with the fresh extractant 9 in the mixer P to form a mixed extractant 10, which is circulated to the extractive distillation tower G.

[0113] The purity of the regenerated extractant 8 is 99%. Taking the total mass of the mixed extractant 10 added into the extractive distillation tower G as 100%, the recovery rate of the regenerated extractant 8 is 99.7%.

[0114] A heat exchanger M and a reflux tank N are provided at the top of the regeneration tower L. The condensed liquid is partially refluxed to the top of the tower through the heat exchanger. This reflux liquid helps to improve the efficiency of distillation. A bottom reboiler O is provided at the bottom of the regeneration tower L. Part of the bottom product is reintroduced into the reboiler, which can reduce the energy loss of reheating the outside of the tower and improve the overall energy utilization efficiency.

[0115] Comparative Example 2

[0116] The purification method of 1,2-epoxyhexane provided in this comparative example is similar to that in Example 2, except that two vacuum distillation towers connected in series are used instead of the distillation tower next to the wall (such as Figure 2 As shown), and the parameters of the two vacuum distillation towers are different from those of the distillation tower next door, the purification method of this comparative example specifically comprises the following steps:

[0117] The above-mentioned 1,2-epoxyhexane crude product 1 at 60°C (the same as the crude product in Example 2) enters the 12th tower plate (a total of 29 tower plates) of the vacuum distillation tower A-1, and is distilled and separated in the tower. The obtained first vacuum distillation tower light component 12 is discharged from the top of the vacuum distillation tower A-1, and the first vacuum distillation tower heavy component 13 (including 1,2-epoxyhexane, hydrogen peroxide, etc.) is discharged from the bottom of the vacuum distillation tower A-1; the top reflux ratio of the vacuum distillation tower A-1 is controlled to be 1.1, the top operating pressure is 10 kPa, the top temperature is -10°C, the bottom temperature is 82°C, and the pressure drop of the whole tower is 6 kPa.

[0118] The first vacuum distillation tower heavy component 13 obtained at the bottom of the vacuum distillation tower A-1 enters the 7th tower plate of the vacuum distillation tower A-2, and the second vacuum distillation tower light component 14 (mainly 1,2-epoxyhexane) and the second vacuum distillation tower heavy component 15 (including hydrogen peroxide, etc.) are separated in the tower. The top reflux ratio is 1.3, the top operating pressure is 10 kPa, the top temperature is 55°C, the bottom temperature is 89°C, the whole tower pressure drop is 6 kPa, and there are 19 tower plates in total.

[0119] The top of the vacuum distillation tower A-1 is provided with a heat exchanger B-1 and a reflux tank C-1. The condensed liquid is partially refluxed to the top of the tower through the heat exchanger. This reflux liquid helps to improve the efficiency of distillation. The bottom of the tower is provided with a bottom reboiler D-1. Part of the bottom product is reintroduced into the reboiler, which can reduce the energy loss of reheating outside the tower and improve the overall energy utilization efficiency.

[0120] The top of the vacuum distillation tower A-2 is provided with a heat exchanger E-1 and a reflux tank F-1. The condensed liquid is partially refluxed to the top of the tower through the heat exchanger. This reflux liquid helps to improve the efficiency of distillation. The bottom of the tower is provided with a bottom reboiler G-1. Part of the bottom product is reintroduced into the reboiler, which can reduce the energy loss of reheating outside the tower and improve the overall energy utilization efficiency.

[0121] Table 1

[0122] Product recovery rate (%) Product purity (%) Total tower load (GJ / hr) Example 2 (behind-the-wall tower) 99.4 99.0 0.233 Comparative Example 2 (Double Towers) 98.6 99.1 0.586

[0123] From the data in the above table, it can be seen that the existing method of separating and purifying crude 1,2-epoxyhexane using two vacuum distillation towers in series has the same purity and yield as Example 2, but the total load of the double towers in Comparative Example 2 is significantly increased, indicating that its energy consumption is large.

[0124] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for purifying 1,2-epoxyhexane, characterized in that: The steps include: The crude 1,2-epoxyhexane product is distilled in a distillation tower to obtain a 1,2-epoxyhexane product; Wherein, the distillation tower next door is a middle partition; The top pressure of the distillation tower is 6-15 kPa, the top temperature is -10-25°C, the pressure drop of the whole tower is 2-15 kPa; the bottom temperature is 70-105°C, and the reflux ratio of the top is 1.1-2.0; The crude 1,2-epoxyhexane is obtained by catalyzing 1-hexene with Ti-Beta molecular sieve.

2. The method for purifying 1,2-epoxyhexane according to claim 1, characterized in that: The interior of the distillation tower is divided into a common distillation section, a pre-fractionation section, a main tower section and a common stripping section; the crude 1,2-epoxyhexane enters the distillation tower from the pre-fractionation section, and the 1,2-epoxyhexane product is discharged from the middle side line of the main tower section.

3. The method for purifying 1,2-epoxyhexane according to claim 2, characterized in that: The number of theoretical plates of the pre-fractionation section and the main tower section is 5 to 25; the number of theoretical plates of the common rectification section and the common stripping section is 5 to 15.

4. The method for purifying 1,2-epoxyhexane according to claim 3, characterized in that: The light components obtained at the top of the common distillation section are separated in an extractive distillation tower under the action of an extractant to obtain a mixture containing acetonitrile, hexene and water, and a mixture containing an extractant and water; The mixture containing acetonitrile, hexene and water has an acetonitrile content of 90 wt% to 98 wt%, a hexene content of 3 wt% to 4.5 wt%, and a water content of 1 wt% to 3 wt%.

5. The method for purifying 1,2-epoxyhexane according to claim 4, characterized in that: The extractant is selected from ethylene glycol, glycerol or N,N-dimethylformamide; The mass ratio of the light component obtained from the top of the distillation tower to the extractant is 1:0.5-1.

5.

6. The method for purifying 1,2-epoxyhexane according to claim 4, characterized in that: The number of theoretical plates of the extractive distillation tower is 25-40.

7. The method for purifying 1,2-epoxyhexane according to claim 6, characterized in that: The light component enters from the upper end of the extractive distillation tower, and the extractant enters from the bottom of the extractive distillation tower; preferably, the light component enters from the 20th to 30th theoretical plates of the extractive distillation tower, and the extractant enters from the 3rd to 6th theoretical plates of the extractive distillation tower.

8. The method for purifying 1,2-epoxyhexane according to claim 4, characterized in that: The mixture containing the extractant and water is regenerated in the regeneration tower to obtain the regenerated extractant which is circulated into the extractive distillation tower. The purity of the regenerated extractant is above 98%.

9. The method for purifying 1,2-epoxyhexane according to claim 8, characterized in that: The number of theoretical plates of the regeneration tower is 15 to 35.

10. The method for purifying 1,2-epoxyhexane according to any one of claims 1 to 9, characterized in that: The purity of the 1,2-epoxyhexane product is above 99%, and the yield is above 98%.

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