Method for preparing high-purity epoxybutane

Abstract

The invention discloses a method for preparing high-purity epoxybutane. The method comprises the following steps: (1) epoxidizing n-butene under the action of a catalyst by taking methanol as a solvent to generate an epoxybutane reaction solution, and enabling the epoxybutane reaction solution to pass through a coarse rectifying tower to obtain an epoxypentane methanol solution; (2) enabling the epoxybutane methanol solution to pass through a washing device, enabling methanol to mainly remain in a water phase, and separating out epoxybutane as an oil phase in the washing device; (3) refining the water phase in a rectifying tower to obtain an epoxybutane methanol solution, and returning the epoxybutane methanol solution to the washing device; tower bottoms of the rectifying tower enter a methanol refining tower and are refined to obtain methanol and water, and the water enters a washing device. The method has the beneficial effects that the high-purity epoxybutane is prepared by washing the epoxybutane with water, the process is simple, the energy consumption of direct washing preparation is greatly reduced, and the extraction agent is wide in source, low in price, environment-friendly and easy to industrialize.

Description

Technical Field

[0001] The invention relates to a method for preparing high-purity butylene oxide. Background Art

[0002] 1,2-Butane oxide (BO) has a ternary structure and active chemical properties. It is an important raw material for organic synthesis. Due to the presence of highly active epoxy groups, the ternary oxygen ring is opened under the action of alkaline or acidic catalysts, and it is easy to undergo addition reactions with a variety of compounds, such as water, alcohols, amines, ammonia, amines, carboxylic acids, etc. It can be used as a monomer for polyether polyols and other polymer intermediates, such as hydrolysis to produce 1,2-butanediol, and the preparation of polyurethane materials with excellent cold resistance using butylene oxide as a monomer polymerization. It can be used as a diluent for nitrocellulose lacquer, such as replacing acetone as a diluent for nitrocellulose lacquer. It can also be used as an antioxidant for chlorine-containing compounds and an anti-corrosion agent for the production of vinyl chloride resins. It can also be used to prepare foam plastics, synthetic rubber, non-ionic surfactants, etc., and is widely used in the fine chemical and petrochemical industries.

[0003] At present, butylene oxide mainly comes from the byproduct of the chlorohydrin process in the production of propylene oxide. The chlorohydrin process uses toxic chlorine gas, which causes serious environmental pollution and is highly corrosive to equipment. It is facing elimination. The chlorohydrin process for producing propylene oxide has been gradually replaced by green processes, cutting off the source of butylene oxide. Therefore, the production of butylene oxide needs to seek new synthesis processes.

[0004] In recent years, the method of epoxidizing n-butene to produce butylene oxide under the action of a catalyst has attracted widespread attention from scholars. Compared with the chlorohydrin method, this method saves the chlorohydrin process and greatly reduces environmental pollution. In the process of preparing butylene oxide from n-butene as a raw material, when methanol is used as a solvent, the conversion rate of n-butene and the selectivity of butylene oxide can be significantly improved, but the boiling points of butylene oxide and the solvent methanol in the product are similar, and separation is difficult, making it difficult to achieve industrial promotion and application of high-purity butylene oxide produced by this route.

[0005] Chinese invention patent CN109851578 A discloses a method for purifying butylene oxide, wherein a raw material stream containing butylene oxide and impurities containing water and oxygen-containing organic compounds enters a first distillation tower in the presence of an azeotropic agent, a first stream is obtained at the top of the tower, and a first heavy component stream is obtained at the bottom of the tower; the azeotropic agent is selected from C4-C5 alkanes; b) the first heavy component stream enters a second distillation tower, a first impurity stream is obtained at the top of the tower, and a second heavy component stream is obtained at the bottom of the tower; c) the second heavy component stream enters a third distillation tower, a second impurity stream is obtained at the top of the tower, a butylene oxide product stream is obtained at the side line of the upper part of the tower, and a third heavy component stream is obtained at the bottom of the tower. There are problems such as high separation cost, complicated separation procedure, low separation efficiency, high cost of extractant and easy loss.

[0006] Chinese patent CN111978274A discloses a method for preparing butylene oxide, comprising: a. contacting a raw material mixture containing n-butene, methanol and an oxidant with an oxidation catalyst in the presence of an acid or a base to react, thereby obtaining a second mixture containing methanol and butanediol; b. separating the second mixture obtained in step a to obtain butanediol; c. contacting the butanediol obtained in step b with a dehydration catalyst to perform a dehydration reaction, thereby obtaining butylene oxide. This method is very complicated relative to the route, and the production cost is relatively high.

[0007] Chinese patent CN110357838B discloses a new method for fractionation extraction separation and purification of 1,2-butylene oxide. It uses the different distribution behaviors of methanol and butylene oxide in different solvent systems, takes the butylene-1-epoxidation reaction solution as the feed liquid phase; takes n-octane as the organic phase; takes deionized water as the aqueous phase; uses the centrifugal force of the centrifugal extractor to further enhance the mass transfer efficiency. After the extraction equilibrium, the methanol and butylene oxide in the feed liquid phase are separated into the aqueous phase and the organic phase respectively; the purity of butylene oxide in the organic phase reaches 100%, and the yield exceeds 80%. This technology has high equipment cost, complex operation and high maintenance cost. Summary of the invention

[0008] The technical problem to be solved by the present invention is that the product separation in the existing butylene oxide reaction liquid is difficult, the extraction and distillation process is complicated, the butylene oxide yield is low, the extraction agent is expensive and the loss is large. Therefore, a method for preparing high-purity butylene oxide is provided.

[0009] The technical scheme of the present invention is: a method for preparing high-purity butylene oxide, comprising the following steps: (1) the butylene oxide reaction liquid generated by epoxidation of n-butene with methanol as solvent under the action of a catalyst passes through a crude distillation tower to obtain an butylene oxide methanol solution; (2) the butylene oxide methanol solution passes through a water washing device, methanol mainly remains in the water phase, and butylene oxide is precipitated in the water washing device as an oil phase; (3) the water phase enters a distillation tower for refining to obtain a butylene oxide methanol solution, which is returned to the water washing device; the bottom liquid of the distillation tower is sent to a methanol refining tower to obtain methanol and water, and the water is sent to the water washing device.

[0010] In step (1) of the above scheme, the number of plates of the crude distillation tower is 10-80, the operating pressure is 30-200 kPa, the bottom temperature is 60-100 °C, the top temperature is 40-70 °C, and the crude distillation reflux ratio is 5-30.

[0011] In step (1) of the above scheme, the number of plates of the crude distillation tower is 15-60, the operating pressure is 60-160 kPa, the bottom temperature is 60-90 °C, the top temperature is 46-65 °C, and the crude distillation reflux ratio is 10-28.

[0012] In step (2) of the above scheme, the volume flow ratio of pentane oxide methanol solution to water is 1:1-1:8, the extraction flow ratio of the top of the tower to the bottom of the tower is 1:2-1:10, and the temperature is 20-50°C.

[0013] In step (2) of the above scheme, the volume flow ratio of pentane oxide methanol solution to water is 1:1-1:6, the extraction flow ratio of the top of the tower to the bottom of the tower is 1:2-1:8, and the temperature is 25-45°C.

[0014] The number of plates of the distillation tower in step (3) of the above scheme is 10 to 50, the operating pressure is -0.1 to -0.8 MPa, the bottom temperature is 30 to 80 °C, the top temperature is 20 to 60 °C, the distillation reflux ratio is 5 to 30, and the butylene oxide methanol solution is enriched at the top of the tower, and then refined into high-purity butylene oxide in a water washing tower.

[0015] In step (3) of the above scheme, the bottom temperature of the tower is 35-75°C, the top temperature of the tower is 30-50°C, and the distillation reflux ratio is 10-28.

[0016] The beneficial effect of the present invention is to provide a method for preparing high-purity butylene oxide which can be efficiently applied in industry, and has the characteristics of simple and efficient process, low energy consumption, environmental friendliness and easy industrial operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0018] The technical scheme of the present invention is described clearly and completely below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments by ordinary technicians in the field without creative work are within the protection scope of the present invention.

[0019] A method for preparing high-purity pentyl oxide, as shown in FIG1 , is as follows: 1. The pentyl oxide reaction liquid is subjected to crude distillation to obtain an pentyl oxide methanol solution, wherein the pentyl oxide reaction liquid mainly contains methanol, butylene oxide, and corresponding alcohols and ethers; 2. The butylene oxide methanol solution is passed through a water washing device, wherein methanol is mainly in the water phase, and high-purity butylene oxide is precipitated as an oil phase in the water washing device; 3. The water phase enters a distillation tower for refining, and when the butylene oxide methanol solution is obtained, it is returned to the water washing device; 4. The bottom liquid of the distillation tower is removed to a methanol refining tower, and the methanol obtained by refining is returned to the n-butene epoxidation reactor, and the water is removed to the water washing device, so that recycling is well achieved without increasing wastewater. The water washing device here can be a water washing tower.

[0020] The butylene oxide reaction liquid is initially refined by a crude distillation tower, and a butylene oxide methanol azeotropic solution is obtained at the top of the tower; the butylene oxide methanol azeotropic solution is washed with water in a water washing tower, and methanol and other water-soluble substances are mainly dissolved in the water phase, while butylene oxide is insoluble in water and precipitates at the top of the tower in the form of an oil phase to obtain high-purity butylene oxide; since butylene oxide is slightly soluble in the water phase and methanol exists in the water phase, a certain amount of butylene oxide is in the water phase, and the water phase of the water washing tower is refined, so that the butylene oxide in the water phase is azeotropic with methanol again, and the butylene oxide methanol solution is enriched and enters the water washing tower for washing to prepare high-purity butylene oxide.

[0021] The number of plates of the crude distillation tower for butylene oxide reaction liquid is 10 to 80, preferably 15 to 60, more preferably 20 to 36, the operating pressure is 30 to 200 kPa, preferably 60 to 160 kPa, more preferably 80 to 120 kPa, the bottom temperature is 60 to 100 ° C, preferably 60 to 90 ° C, more preferably 66 to 80 ° C, the top temperature is 40 to 70 ° C, preferably 46 to 65 ° C, more preferably 48 to 63 ° C, the crude distillation reflux ratio is 5 to 30, preferably 10 to 28, more preferably 15 to 25; the top of the tower is butylene oxide methanol solution, and the bottom of the tower is the heavy component.

[0022] The butylene oxide reaction liquid is fed into the lower part of the water washing tower, and water is fed into the upper part of the water washing tower. The mixed water is washed in the water washing tower. The butylene oxide methanol solution is fed into the lower part of the tower, and water is fed into the upper part of the tower. The volume flow ratio of the pentane oxide methanol solution to water is 1:1-1:8, preferably 1:1-1:6, and more preferably 1:2-1:5; the extraction flow ratio of the top of the tower to the bottom of the tower is 1:2-1:10, preferably 1:2-1:8, and more preferably 1:2-1:6. The temperature is 20-50°C, preferably 25-45°C, and more preferably 28-43°C.

[0023] The number of plates of the water washing liquid distillation tower is 10 to 50, the operating pressure is -0.1 to -0.8 MPa, the bottom temperature is 30 to 80 ° C, preferably 35 to 75 ° C, more preferably 40 to 65 ° C, the top temperature is 20 to 60 ° C, preferably 30 to 50 ° C, more preferably 32 to 46 ° C, the distillation reflux ratio is 5 to 30, preferably 10 to 28, more preferably 15 to 25; the top of the tower is butylene oxide methanol solution, and the bottom of the tower is mainly methanol aqueous solution. The enriched butylene oxide methanol azeotropic liquid is refined into high-purity butylene oxide by dewatering the washing tower.

[0024] Embodiment 1: The pentyl oxide methanol solution is pumped to the lower part of the water scrubber, and water is pumped to the upper part of the water scrubber. The two are mixed in a 1:1 ratio in a special water scrubber, and the washing temperature is 35 °C and the washing time is 1.5 h to dissolve methanol in the water phase. The water phase is refined to obtain butylene oxide methanol azeotropic liquid, which is returned to the water scrubber to prepare butylene oxide, and the heavy components are recycled in subsequent processes.

[0025] Embodiment 2: The pentyl oxide methanol solution is pumped to the lower part of the water scrubber, and water is pumped to the upper part of the water scrubber. The two are mixed in a ratio of 1:2 in a special water scrubber, the washing temperature is 35 °C, and the washing time is 1 h to dissolve methanol in the water phase. The water phase is refined to obtain butylene oxide methanol azeotropic liquid, which is returned to the water scrubber to prepare butylene oxide, and the heavy components are recycled in subsequent processes.

[0026] Embodiment 3: The pentyl oxide methanol solution is pumped to the lower part of the water scrubber, and water is pumped to the upper part of the water scrubber. The two are mixed in a ratio of 1:3 in a special water scrubber, the washing temperature is 35 °C, and the washing time is 1.5 h to dissolve methanol in the water phase. The water phase is refined to obtain butylene oxide methanol azeotropic liquid, which is returned to the water scrubber to prepare butylene oxide, and the heavy components are recycled in subsequent processes.

[0027] Embodiment 4: The pentyl oxide methanol solution is pumped to the lower part of the water scrubber, and water is pumped to the upper part of the water scrubber. The two are mixed in a special water scrubber at a ratio of 1:4, the washing temperature is 35 °C, and the washing time is 1.5 h to dissolve methanol in the water phase. The water phase is refined to obtain butylene oxide methanol azeotropic liquid, which is returned to the water scrubber to prepare butylene oxide, and the heavy components are recycled in subsequent processes.

[0028] Embodiment 5: The pentyl oxide methanol solution is pumped to the lower part of the water scrubber, and water is pumped to the upper part of the water scrubber. The two are mixed in a ratio of 1:3 in a special water scrubber, the washing temperature is 30 °C, and the washing time is 1.5 h to dissolve methanol in the water phase. The water phase is refined to obtain butylene oxide methanol azeotropic liquid, which is returned to the water scrubber to prepare butylene oxide, and the heavy components are recycled in subsequent processes.

[0029] Embodiment 6: The pentyl oxide methanol solution is pumped to the lower part of the water scrubber, and water is pumped to the upper part of the water scrubber. The two are mixed in a ratio of 1:3 in a special water scrubber, the washing temperature is 40 °C, and the washing time is 1.5 h to dissolve methanol in the water phase. The water phase is refined to obtain butylene oxide methanol azeotropic liquid, which is returned to the water scrubber to prepare butylene oxide, and the heavy components are recycled in subsequent processes.

[0030] Embodiment 7: The pentyl oxide methanol solution is pumped to the lower part of the water scrubber, and water is pumped to the upper part of the water scrubber. The two are mixed in a ratio of 1:3 in a special water scrubber, the washing temperature is 35 °C, and the washing time is 1 h to dissolve methanol in the water phase. The water phase is refined to obtain butylene oxide methanol azeotropic liquid, which is returned to the water scrubber to prepare butylene oxide, and the heavy components are recycled in subsequent processes.

[0031] Embodiment 8: The pentyl oxide methanol solution is pumped to the lower part of the water scrubber, and water is pumped to the upper part of the water scrubber. The two are mixed in a ratio of 1:3 in a special water scrubber, the washing temperature is 35 °C, and the washing time is 2 h to dissolve methanol in the water phase. The water phase is refined to obtain butylene oxide methanol azeotropic liquid, which is returned to the water scrubber to prepare butylene oxide, and the heavy components are recycled in subsequent processes.

[0032] Embodiment 9: The pentyl oxide methanol solution is pumped to the lower part of the water scrubber, and water is pumped to the upper part of the water scrubber. The two are mixed in a ratio of 1:3 in a special water scrubber, the washing temperature is 35 °C, and the washing time is 2.5 h to dissolve methanol in the water phase. The water phase is refined to obtain butylene oxide methanol azeotropic liquid, which is returned to the water scrubber to prepare butylene oxide, and the heavy components are recycled in subsequent processes.

[0033] The experimental results of Examples 1 to 9 are shown in Table 1: Table 1 Experimental data of butylene oxide purification

[0034] Comparative Example 1: The implementation method is the same as that of Example 8, except that the refining tower is eliminated, the purity of butylene oxide at the top of the water washing tower is 99.93%, and the butylene oxide yield is 67.61%; it can be seen that the butylene oxide yield is significantly reduced.

[0035] Comparative Example 2: The butylene oxide methanol azeotropic liquid obtained by crude distillation is prepared by extractive distillation, the amount of extractant used is 7:1, and the butylene oxide obtained by extractive distillation has a purity of 96.21%. The extractant needs to be treated for recycling. The methanol is further refined and recycled. The purity of the obtained butylene oxide product needs to be further refined to obtain high-purity butylene oxide. The amount of extractant used is 10:1, and the purity of the obtained butylene oxide is 99.93%.

[0036] The invention prepares high-purity butylene oxide by washing butylene oxide with water, has the advantages of simple process, greatly reduced energy consumption of direct water washing preparation, wide source of extractant, low price, environmental friendliness and easy industrialization.

Claims

1. A method for preparing high-purity butylene oxide, characterized in that: The following steps are involved: (1) The reaction liquid of butylene oxide produced by epoxidation of n-butene with methanol as solvent under the action of a catalyst is passed through a crude distillation tower to obtain a methanol solution of pentyl oxide; (2) The methanol solution of butylene oxide is passed through a water washing device, and methanol mainly remains in the water phase, while butylene oxide is precipitated as an oil phase in the water washing device; (3) The water phase enters a distillation tower for refining to obtain a methanol solution of butylene oxide, which is returned to the water washing device; the bottom liquid of the distillation tower is sent to a methanol refining tower to obtain methanol and water, and the water is sent to the water washing device.

2. A method for preparing high-purity butylene oxide as claimed in claim 1, characterized in that: In the step (1), the number of plates of the crude distillation tower is 10 to 80, the operating pressure is 30 to 200 kPa, the bottom temperature is 60 to 100 °C, the top temperature is 40 to 70 °C, and the crude distillation reflux ratio is 5 to 30.

3. A method for preparing high-purity butylene oxide as claimed in claim 2, characterized in that: In the step (1), the crude distillation tower has 15 to 60 plates, an operating pressure of 60 to 160 kPa, a bottom temperature of 60 to 90 °C, a top temperature of 46 to 65 °C, and a crude distillation reflux ratio of 10 to 28.

4. A method for preparing high-purity butylene oxide as claimed in claim 1, characterized in that: In the step (2), the volume flow ratio of pentyl oxide methanol solution to water is 1:1-1:8, the extraction flow ratio of the top of the tower to the bottom of the tower is 1:2-1:10, and the temperature is 20-50°C.

5. A method for preparing high-purity butylene oxide as claimed in claim 4, characterized in that: In the step (2), the volume flow ratio of pentyl oxide methanol solution to water is 1:1-1:6, the extraction flow ratio of the top of the tower to the bottom of the tower is 1:2-1:8, and the temperature is 25-45°C.

6. A method for preparing high-purity butylene oxide as claimed in claim 1, characterized in that: The number of plates of the distillation tower in step (3) is 10 to 50, the operating pressure is -0.1 to -0.8 MPa, the bottom temperature is 30 to 80°C, the top temperature is 20 to 60°C, the distillation reflux ratio is 5 to 30, and the butylene oxide methanol solution is enriched at the top of the tower, and then refined into high-purity butylene oxide in a water washing tower.

7. A method for preparing high-purity butylene oxide as claimed in claim 6, characterized in that: The bottom temperature in step (3) is 35-75°C, the top temperature is 30-50°C, and the distillation reflux ratio is 10-28.

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