Gamma-butyrolactone heavy component recovery device and method

Abstract

The invention provides a gamma-butyrolactone heavy component recovery device and a gamma-butyrolactone heavy component recovery method. The device comprises a dehydration cyclization reactor, separation equipment, a film evaporator, a gamma-butyrolactone separation tower and a normal-pressure dehydration tower. Wherein the dehydration cyclization reactor is provided with a gamma-butyrolactone heavy component feeding hole; a solid acid catalyst is arranged in the dehydration cyclization reactor; a feeding hole of the separation equipment is communicated with a discharging hole in the top of the dehydration cyclization reactor; a feeding hole of the film evaporator is communicated with a discharging hole in the bottom of the dehydration cyclization reactor; a feeding hole of the gamma-butyrolactone separating tower is communicated with a gas-phase discharging hole of the film evaporator, and a gamma-butyrolactone discharging hole is formed in a tower kettle of the gamma-butyrolactone separating tower; a feeding hole of the normal-pressure dehydrating tower is communicated with a discharging hole of the separating equipment, and a tetrahydrofuran discharging hole is formed in a tower kettle of the normal-pressure dehydrating tower. The method has the advantages that the atom utilization rate is high, gamma-butyrolactone heavy components are efficiently recycled, and an existing production device is not affected.

Description

Technical Field

[0001] The present invention belongs to the field of new chemical materials, and particularly relates to a device and method for recovering heavy components of γ-butyrolactone. Background Art

[0002] γ-Butyrolactone (GBL) is commonly used in the production of pharmaceuticals such as cyclopropylamine and pyrrolidone, and can also be used as an industrial solvent, diluent, curing agent, etc. With the rapid increase in the market demand for N-methylpyrrolidone (NMP), GBL, as the main raw material for synthesizing NMP, has become an important product in chemical production.

[0003] In the conventional process of synthesizing GBL by dehydrogenation of 1,4-butanediol (BDO), the raw material 1,4-butanediol is vaporized in a vaporization tower and then undergoes a dehydrogenation reaction in a dehydrogenation reactor. The crude GBL product after the reaction contains by-products such as tetrahydrofuran, water, unreacted BDO, and heavier coking substances. After distillation to remove light components and heavy components, a refined GBL product is obtained.

[0004] In this process, the heavy components of γ-butyrolactone generated after the removal of heavy components from the crude GBL product contain γ-butyrolactone, 1,4-butanediol, and other heavy components. The current production process treats it as hazardous waste, which causes a large amount of resource waste. In order to reduce the unit consumption, some production enterprises reuse part of the heavy components as raw materials before returning them to the vaporization tower, thereby improving the utilization rate of raw materials. However, using the heavy components of γ-butyrolactone as raw materials will cause the catalyst in the dehydrogenation reactor to be poisoned and aged and inactivated. At this time, it is necessary to increase the reaction temperature to achieve the required reaction effect, and the increase in temperature will produce more coking by-products, ultimately resulting in a reduction in the service life of the dehydrogenation reaction catalyst, an increase in the amount of catalyst used and operating costs, and the generation of a large amount of catalyst solid waste. For example, CN115819311B discloses a method for collecting heavy components of crude GBL. It rectifies the GBL heavy components through a rectification tower, and the rectified liquid of the GBL heavy components at the top of the tower is returned to before the vaporization tower for recycling, and the heavy components at the bottom of the tower are treated as hazardous waste. This technology can recover some useful components in the heavy components, but the recovered materials are directly returned to the BDO dehydrogenation reactor, which will affect the service life of the BDO dehydrogenation reactor catalyst, and most of the heavy components are still difficult to recover. Therefore, it is necessary to provide a new method to improve the above problems. Summary of the Invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a device and method for recovering heavy components of γ-butyrolactone. The device for recovering heavy components of γ-butyrolactone has a high atom utilization rate, can achieve the efficient recovery of heavy components of γ-butyrolactone, and does not affect the existing production device.

[0006] To achieve the above object, the present invention provides a device for recovering heavy components of γ-butyrolactone, which comprises a dehydration cyclization reactor, a separation device, a thin-film evaporator, a γ-butyrolactone separation column and an atmospheric-pressure dehydration column. Among them, the dehydration cyclization reactor has a feed inlet for heavy components of γ-butyrolactone; and a solid acid catalyst is provided in the dehydration cyclization reactor; the feed inlet of the separation device is communicated with the discharge port at the top of the dehydration cyclization reactor; the feed inlet of the thin-film evaporator is communicated with the discharge port at the bottom of the dehydration cyclization reactor; the feed inlet of the γ-butyrolactone separation column is communicated with the gas-phase discharge port of the thin-film evaporator, and the bottom of the γ-butyrolactone separation column has a discharge port for γ-butyrolactone; the feed inlet of the atmospheric-pressure dehydration column is communicated with the discharge port of the separation device, and the bottom of the atmospheric-pressure dehydration column has a discharge port for tetrahydrofuran.

[0007] In the conventional BDO dehydrogenation process for synthesizing GBL, the raw material BDO is vaporized in a vaporization tower and then undergoes a dehydrogenation reaction in a dehydrogenation reactor. The crude GBL product after the reaction contains by-products such as tetrahydrofuran, water, unreacted BDO and heavier coking substances. This crude GBL product continues to undergo light-component removal and heavy-component removal by distillation to obtain a refined GBL product and heavy-component removal waste (i.e., the heavy components of γ-butyrolactone to be recovered and treated in the present invention). The heavy components of γ-butyrolactone generated after the heavy-component removal of the crude γ-butyrolactone product contain γ-butyrolactone, 1,4-butanediol and other heavy components, and the boiling points of γ-butyrolactone, 1,4-butanediol and the heavy components are close, making it difficult to directly and effectively separate the three.

[0008] The present invention first introduces a dehydration cyclization reactor to convert 1,4-butanediol and most other heavy components in the heavy components of γ-butyrolactone into tetrahydrofuran under the action of a solid acid catalyst, increasing the cracking rate of the heavy components; then introduces a separation device to separate the tetrahydrofuran and water in the gas phase generated by the dehydration reaction to obtain the product material; and also introduces an atmospheric-pressure dehydration column to continue the dehydration treatment of the product material obtained by the separation device, thereby obtaining a tetrahydrofuran product with low water content and high purity at the bottom of the column.

[0009] At the same time, the present invention also introduces a thin-film evaporator to evaporate the dehydration reaction residue after the dehydration reaction, and makes the gas-phase material obtained by the evaporation treatment enter the γ-butyrolactone separation column for separation treatment, thereby obtaining γ-butyrolactone with low impurity content and high purity at the bottom of the γ-butyrolactone separation column.

[0010] The present invention realizes the beneficial effect of converting 1,4-butanediol and most other heavy components into higher-value tetrahydrofuran for effective utilization, and also simultaneously realizes the efficient recovery of γ-butyrolactone, with a higher recovery rate of heavy components, greatly reducing the discharge of heavy components and improving the economic benefits of the γ-butyrolactone device.

[0011] Further, the discharge port at the top of the γ-butyrolactone separation column is communicated with the feed inlet of the separation device.

[0012] Further, the outlet of the top of the atmospheric pressure dehydration tower is communicated with the inlet of the separation equipment.

[0013] In some alternative embodiments, the γ-butyrolactone outlet of the bottom of the γ-butyrolactone separation tower may be communicated with the heavy component removal equipment in the above-mentioned main device for the BDO dehydrogenation synthesis of GBL process, and continue to participate in the heavy component removal treatment and enter the γ-butyrolactone heavy component recovery device again for recovery treatment. After all, in some embodiments, the thin film evaporator may also evaporate some of the unreacted BDO in the dehydration cyclization reactor, thus entering the γ-butyrolactone separation tower. However, this part of the unreacted BDO can enter the heavy components of the main device again and return as the γ-butyrolactone heavy components to be recovered in the present invention, with a higher recovery rate.

[0014] In a preferred embodiment, the separation equipment is a membrane separation unit, and the inlet of the atmospheric pressure dehydration tower is communicated with the outlet of the retentate side of the membrane separation unit. Using the membrane separation unit can further significantly reduce the production energy consumption.

[0015] In some alternative embodiments, the number of theoretical plates of the γ-butyrolactone separation tower is 20 - 40.

[0016] In some alternative embodiments, the number of theoretical plates of the atmospheric pressure dehydration tower is 20 - 40.

[0017] In some alternative embodiments, the solid acid catalyst includes one or a combination of two or more of macroporous cation exchange resins (such as T62 type cation exchange resin, 732 type cation exchange resin, etc.), molecular sieves (such as Y type molecular sieve, ZSM-5 molecular sieve, etc.), and γ-aluminum oxide, and preferably cation exchange resins (such as T62 type cation exchange resin, 732 type cation exchange resin, etc.).

[0018] The present invention also provides a method for recovering γ-butyrolactone heavy components, which includes the following steps:

[0019] Let the γ-butyrolactone heavy components enter the dehydration cyclization reactor to carry out dehydration reaction under the action of a solid acid catalyst. A first part of the gas-phase tetrahydrofuran and water is taken out from the top of the dehydration cyclization reactor, and the dehydration reaction residual liquid is taken out from the bottom.

[0020] Let the first part of the gas-phase tetrahydrofuran and water enter the separation equipment for the first separation treatment, and let the material obtained by the separation equipment enter the atmospheric pressure dehydration tower for dehydration treatment, and tetrahydrofuran is obtained at the bottom of the atmospheric pressure dehydration tower.

[0021] The dehydrated reaction residue is fed into a thin-film evaporator for evaporation treatment, and the gaseous material obtained from the evaporation treatment is fed into a γ-butyrolactone separation column for a second separation treatment, and γ-butyrolactone is obtained at the bottom of the γ-butyrolactone separation column.

[0022] Further, the material withdrawn from the top of the γ-butyrolactone separation column is fed into a separation device to participate in the first separation treatment.

[0023] Further, the material withdrawn from the top of the atmospheric pressure dehydration column is refluxed into the separation device to participate in the first separation treatment.

[0024] In a preferred embodiment, the separation device adopts a membrane separation unit. Tetrahydrofuran and water in the form of a first part of the gas phase enter the membrane separation unit for separation treatment, and the material obtained on the retentate side of the membrane separation unit is fed into the atmospheric pressure dehydration column for dehydration treatment, and tetrahydrofuran is obtained at the bottom of the atmospheric pressure dehydration column; while the wastewater on the permeate side of the membrane separation unit is discharged.

[0025] Further, tar is discharged from the bottom of the thin-film evaporator.

[0026] Further, the γ-butyrolactone at the bottom of the γ-butyrolactone separation column is continuously recycled to the process section for removing heavy components of the crude γ-butyrolactone product.

[0027] Further, the reaction pressure in the dehydration cyclization reactor is 0 to 0.5 MpaG, the reaction temperature is 100 to 140 °C, preferably 130 °C.

[0028] Further, the treatment pressure of the thin-film evaporator is 2 to 10 KPa.

[0029] Further, the treatment pressure of the membrane separation unit is 0.2 to 0.4 Mpa.

[0030] Further, the separation pressure of the γ-butyrolactone separation column is 2 to 10 KPa.

[0031] In the conventional BDO dehydrogenation process for synthesizing GBL, the raw material BDO is gasified in a gasification tower and then undergoes a dehydrogenation reaction in a dehydrogenation reactor. The crude GBL product after the reaction contains by-products such as tetrahydrofuran, water, unreacted BDO, and heavier coking substances. This crude GBL product is further subjected to light component removal and heavy component removal by distillation to obtain a refined GBL product and heavy component removal waste (i.e., γ-butyrolactone heavy components). In some possible embodiments, the γ-butyrolactone heavy components include 10 to 15 wt% of γ-butyrolactone, 50 to 60 wt% of 1,4-butanediol, and the balance of inevitable impurity heavy components (such as 1,4-butanediol high polymers, macromolecular ethers, acetals, etc., with a content of about 10 to 15 wt%). Description of the Drawings

[0032] Figure 1Shows a schematic diagram of a γ-butyrolactone heavy component recovery device in an embodiment of the present invention.

[0033] 1 - dehydration cyclization reactor; 2 - membrane separation unit; 3 - thin film evaporator; 4 - γ-butyrolactone separation column; 5 - atmospheric pressure dehydration column. Detailed implementation manners

[0034] It should be noted that the terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects and do not necessarily describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances for the embodiments of this application described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0035] For a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the technical solutions of the present invention are described in detail below, but it should not be construed as a limitation on the scope of implementation of the present invention.

[0036] Examples 1 - 3

[0037] (1) This embodiment provides a γ-butyrolactone heavy component recovery device, as Figure 1 shown, which includes a dehydration cyclization reactor 1, a membrane separation unit 2, a thin film evaporator 3, a γ-butyrolactone separation column 4, and an atmospheric pressure dehydration column 5; among them,

[0038] The dehydration cyclization reactor 1 has a γ-butyrolactone heavy component feed port; and a solid acid catalyst T62 cation exchange resin is provided in the dehydration cyclization reactor 1;

[0039] The feed port of the membrane separation unit 2 is connected to the discharge port at the top of the dehydration cyclization reactor 1;

[0040] The feed port of the thin film evaporator 3 is connected to the discharge port at the bottom of the dehydration cyclization reactor 1;

[0041] The feed port of the γ-butyrolactone separation column 4 is connected to the gas phase discharge port of the thin film evaporator 3; the bottom of the γ-butyrolactone separation column 4 has a γ-butyrolactone discharge port; the discharge port at the top of the γ-butyrolactone separation column 4 is connected to the feed port of the membrane separation unit 2;

[0042] The feed inlet of the atmospheric pressure dehydration tower 5 is communicated with the discharge outlet on the retentate side of the membrane separation unit 2; the bottom of the atmospheric pressure dehydration tower 5 has a tetrahydrofuran discharge outlet; the discharge outlet at the top of the atmospheric pressure dehydration tower 5 is communicated with the feed inlet of the membrane separation unit 2;

[0043] Both the γ-butyrolactone separation tower 4 and the atmospheric pressure dehydration tower 5 have 30 trays.

[0044] (2) This embodiment provides a method for recovering γ-butyrolactone heavy components, which includes the following steps:

[0045] Let the γ-butyrolactone heavy components enter the dehydration cyclization reactor 1 for dehydration reaction. A first part of tetrahydrofuran and water in gaseous form is taken out from the top of the dehydration cyclization reactor 1, and the dehydration reaction residual liquid is taken out from the bottom;

[0046] Let the first part of tetrahydrofuran and water in gaseous form enter the membrane separation unit 2 for membrane separation treatment. The wastewater on the permeate side of the membrane separation unit is discharged externally, and the material obtained on the retentate side of the membrane separation unit 2 enters the atmospheric pressure dehydration tower 5 for dehydration treatment. Tetrahydrofuran is obtained at the bottom of the atmospheric pressure dehydration tower 5, and the material taken out from the top of the atmospheric pressure dehydration tower is refluxed into the membrane separation unit to participate in the membrane separation treatment;

[0047] Let the dehydration reaction residual liquid enter the thin-film evaporator 3 for evaporation treatment. The tar at the bottom of the thin-film evaporator 3 is discharged externally, and the gaseous material obtained from the evaporation treatment enters the γ-butyrolactone separation tower 4 for separation treatment. γ-Butyrolactone is obtained at the bottom of the γ-butyrolactone separation tower 4, and this part of γ-butyrolactone is recovered into the γ-butyrolactone product deweighting tower of the main device. The material taken out from the top of the γ-butyrolactone separation tower 4 enters the membrane separation unit 2 to participate in the membrane separation treatment.

[0048] Among them, the operating conditions of Example 1 and Example 3 are shown in Table 1 below.

[0049] Table 1

[0050]

[0051]

[0052] Before the recovery treatment, all the γ-butyrolactone heavy components were treated as waste liquid and outsourced after the deweighting treatment (that is, the total tar discharge amount was 1000 kg / h). After the recovery treatment of the present invention, the tar discharge amount can be reduced to 100 - 201 kg / h, and even can be reduced by 90% under better conditions.

[0053] Example 4

[0054] The difference between Example 4 and Example 3 is only that the membrane separation unit is replaced by a traditional distillation column. The operating conditions of Example 3 and Example 4 are shown in Table 2 below.

[0055] Table 2

[0056] Serial number Example 4 Example 3 Reaction pressure of the dehydration cyclization reactor, MpaG 0.4 0.4 Separation pressure of the γ-butyrolactone separation column / MpaG 0.4 0.4 Reaction temperature of the dehydration cyclization reactor / °C 130 130 BDO conversion rate in the dehydration cyclization reactor >99％ >99％ Purity of the THF product in the outlet of the atmospheric pressure dehydration column 99.9％ 99.9％ Feed rate of γ-butyrolactone heavy components (dehydration cyclization reactor), kg / h 1000 1000 Tar discharge amount (thin film evaporator), kg / h 100 100 Wastewater discharge amount (separation equipment), kg / h 160 160 Steam consumption / t / tTHF 1.06 0.61

[0057] The distillation column can also achieve the separation effect, but it will affect the energy consumption of the separation process. It can be seen from the steam consumption in the separation process that Example 3 using the membrane separation technology is more energy-efficient than Example 4 by more than 40%.

Claims

1. A device for recovering heavy components of γ-butyrolactone, wherein, It includes a dehydration cyclization reactor, a separation device, a thin film evaporator, a γ-butyrolactone separation column, and an atmospheric pressure dehydration column; The dehydration cyclization reactor has a γ-butyrolactone heavy component feed inlet; and a solid acid catalyst is provided in the dehydration cyclization reactor; The feed inlet of the separation device is communicated with the discharge outlet at the top of the dehydration cyclization reactor; The feed inlet of the thin film evaporator is communicated with the discharge outlet at the bottom of the dehydration cyclization reactor; The feed inlet of the γ-butyrolactone separation column is communicated with the gas phase discharge outlet of the thin film evaporator, and the bottom of the γ-butyrolactone separation column has a γ-butyrolactone discharge outlet; The feed inlet of the atmospheric pressure dehydration column is communicated with the discharge outlet of the separation device, and the bottom of the atmospheric pressure dehydration column has a tetrahydrofuran discharge outlet.

2. The γ-butyrolactone heavy component recovery device according to claim 1, wherein, The discharge outlet at the top of the γ-butyrolactone separation column is communicated with the feed inlet of the separation device.

3. The γ-butyrolactone heavy component recovery device according to claim 1 or 2, wherein, The discharge outlet at the top of the atmospheric pressure dehydration column is communicated with the feed inlet of the separation device.

4. The γ-butyrolactone heavy component recovery device according to claim 1, wherein, The separation device is a membrane separation unit, and the feed inlet of the atmospheric pressure dehydration column is communicated with the discharge outlet on the retentate side of the membrane separation unit.

5. The γ-butyrolactone heavy component recovery device according to claim 1, wherein, The number of theoretical plates of the γ-butyrolactone separation column is 20 - 40; and / or, The number of theoretical plates of the atmospheric pressure dehydration column is 20 - 40; and / or, The solid acid catalyst includes one or a combination of two or more of macroporous cation exchange resin, molecular sieve, and alumina.

6. A method for recovering heavy components of γ-butyrolactone, wherein, Using the γ-butyrolactone heavy component recovery device according to any one of claims 1 to 5, the γ-butyrolactone heavy component recovery method includes the following steps: Let the γ-butyrolactone heavy component enter the dehydration cyclization reactor, and carry out a dehydration reaction under the action of the solid acid catalyst. A first part of tetrahydrofuran and water in the form of gas is taken out from the top of the dehydration cyclization reactor, and the dehydration reaction residue liquid is taken out from the bottom; Let the first part of tetrahydrofuran and water in the form of gas enter the separation device for the first separation treatment, and let the material obtained by the separation device enter the atmospheric pressure dehydration column for dehydration treatment, and tetrahydrofuran is obtained at the bottom of the atmospheric pressure dehydration column; Let the dehydration reaction residue liquid enter the thin film evaporator for evaporation treatment, and let the gas phase material obtained by the evaporation treatment enter the γ-butyrolactone separation column for the second separation treatment, and γ-butyrolactone is obtained at the bottom of the γ-butyrolactone separation column.

7. The method for recovering the heavy components of γ-butyrolactone according to claim 6, wherein, Let the material taken out from the top of the γ-butyrolactone separation column enter the separation device to participate in the first separation treatment.

8. The method for recovering the recombinant fraction of γ-butyrolactone according to claim 6 or 7, wherein, Let the material taken out from the top of the atmospheric pressure dehydration column flow back into the separation device to participate in the first separation treatment.

9. The method for recovering the recombinant fraction of γ-butyrolactone according to claim 6, wherein, The reaction pressure in the dehydration cyclization reactor is 0 - 0.5 MpaG, and the reaction temperature is 100 - 140 °C; and / or, The treatment pressure of the thin film evaporator is 2 - 10 KPa; and / or, The treatment pressure of the membrane separation unit is 0.2 - 0.4 Mpa; and / or, The separation pressure of the γ-butyrolactone separation column is 2 - 10 KPa.

10. The method for recovering the heavy components of γ-butyrolactone according to claim 6, wherein, The γ-butyrolactone heavy component includes 10 - 15 wt% of γ-butyrolactone, 50 - 60 wt% of 1,4-butanediol, and the balance of inevitable heavy impurity components.

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