Process for the production of vinyl ethers by a gas-liquid method

Abstract

The application provides a production process for preparing a vinyl ether by a gas-liquid method. The production process is based on a reaction device which reduces the moving equipment of the reactor, guarantees long-term stable operation of the equipment, improves the reaction yield of acetylene, reduces production cost and waste gas emission, is convenient to operate, and is beneficial to industrialized continuous production.

Description

Technical Field

[0001] This invention relates to the field of organic chemical technology, and in particular to a gas-liquid process for producing vinyl ethers. Background Technology

[0002] Vinyl ethers specifically refer to ether compounds in which an unsaturated carbon-carbon double bond is attached to the ether bond. This carbon-carbon double bond forms a conjugated bond with the adjacent oxygen atom, resulting in an electron-rich structure and exhibiting highly reactive chemical properties. The general formula for divinyl ethers is: H₂C=CHOCH₂-R-CH₂OCH=CH₂, and their structural formula is: ; The general formula for monovinyl ethers is: R1C(R2)=C(R3)OR4, and the structural formula is: ; In the formula: R = saturated chain hydrocarbon or saturated chain hydrocarbon containing functional groups; R1 = H, saturated chain hydrocarbon or saturated chain hydrocarbon containing functional groups; R2 = H, Me, X, etc.; R3 = G, Me, Et, Pr, etc.; R4 = saturated chain hydrocarbon or saturated chain hydrocarbon containing functional groups. Vinyl ether compounds have a wide range of applications in industry: First, as chemical intermediates, they can be used in the synthesis of drugs such as sulfadiazine, disinfectants such as glutaraldehyde, and fragrances; second, some vinyl ethers paralyze the central nervous system, and their anesthetic effect is stronger than that of ether, therefore they are used in medicine as anesthetics and analgesics; third, as polymer monomers, they can be self-polymerized or copolymerized with other monomers to form polymer materials; fourth, as auxiliaries, they are used in softeners, adhesives, coatings, leather coatings, textile surface treatment agents, synthetic rubber modifiers, etc. In recent years, the rapidly developing radiation-cured coatings have expanded the application market for vinyl ethers. Vinyl ethers as reactive diluents or for modifying epoxy resins into oligomers containing vinyl ether functional groups have received considerable attention. The main synthetic methods for vinyl ethers include the acetylene process, dehydrohalogenation process, acetal thermal decomposition process, and transesterification process. The acetylene process is the primary method for large-scale industrial production. The reaction of acetylene with alcohols to produce vinyl ethers is called the acetylene vinylization reaction.

[0003] In 1888, Russian chemist Favorskii discovered the nucleophilic addition reaction of acetylene with alcohols in the presence of a base to produce vinyl ethers. The reaction equation is as follows: ; Building upon Favorskii's research, German chemist Reppe further developed and refined the preparation process of vinyl ethers, achieving industrial-scale production. Typical catalysts for this technology include alkali metal alkoxides and alkali metal hydroxides, and the reaction is strongly exothermic. Literature studies indicate that potassium hydroxide, sodium hydroxide, and cesium hydroxide all exhibit good activity; lithium hydroxide shows similar activity in some systems, and the reaction efficiency decreases with increasing carbon chain length. To improve reaction efficiency, the reaction temperature and pressure can be significantly increased. However, since acetylene is a highly hazardous chemical, the safety of the acetylene vinylation reaction under high temperature and pressure is of paramount importance. To improve reaction temperature and pressure while ensuring safety, various reactors have been used, including fixed-bed reactors, packed tower reactors, and nitrogen-diluted gas-liquid reactors. For example, patent CN108187682A uses a solid base to catalyze the synthesis of 4-hydroxybutylvinyl ether from acetylene and 1,4-butanediol in a fixed bed reactor; patent CN102260144B uses a packed tower. However, fixed-bed reactors have low space-time yields and are prone to blockages, affecting normal production. Therefore, currently, industrially implemented acetylene vinylation reactions are mainly gas-liquid reactions, carried out at atmospheric pressure or below 0.5 MPa, and often in batches. For instance, in patent CN213222199, the reaction pressure of acetylene and ethylene glycol is 0.3 MPa. While nitrogen dilution in a gas-liquid reaction system can increase reaction temperature and pressure, it has several drawbacks: firstly, it requires a large amount of nitrogen; secondly, approximately 5-10% of the acetylene gas in the tail gas is directly emitted into the tail gas treatment device for incineration, resulting in high raw material consumption and increased production costs. For example, patent GB773331 uses a nitrogen dilution method. Industrial practice shows that in the acetylene ethylene reaction, simply relying on the intensity of gas stirring is insufficient to enhance the mixing of the catalyst and the reaction liquid, as well as the effective mass transfer of acetylene. Therefore, external stirring devices or external circulation pumps are often added to enhance mass transfer, but this introduces challenges to the continuous and stable operation of the power equipment. Furthermore, while increasing the reaction temperature significantly improves reaction efficiency, the heat of reaction cannot be effectively removed, necessitating a reduction in the reaction feed rate or the reaction temperature to reduce heat generation and maintain the reaction system temperature, or the installation of an external circulation heat exchanger. Summary of the Invention

[0004] To address the shortcomings of existing acetylene vinylization reaction systems, this invention provides a gas-liquid process for preparing vinyl ethers, which improves mass transfer efficiency, reduces waste gas emissions, and solves the problem of reactor heat transfer.

[0005] The purpose of this invention is: (1) Increase the nitrogen / acetylene dilution ratio to solve the mass transfer mixing problem; (2) Reduce production costs and waste gas emissions through nitrogen recycling; (3) Solve the problem of heat transfer in the reaction by using gas to carry away and evaporate the product; (4) Increase the reaction temperature to enhance reaction efficiency, or simultaneously increase the pre-reactor to improve acetylene conversion rate; To achieve the above objectives, the present invention adopts the following technical solution: This invention provides an acetylene ethylene reaction apparatus and production process. The reaction apparatus includes a nitrogen / acetylene mixing tank 1, a compressor 2, two reactors, a flash tank 4, a crude separation tower 6, and several condensers.

[0006] Acetylene, circulating nitrogen, supplementary nitrogen, and the mixed gas from flash tank 4 are fed into nitrogen / acetylene mixing tank 1 for mixing, and then sent to reactor I 3 via compressor 2; In reactor I3, the reactants from reactor II8 react with acetylene from compressor 2. Part of the heat of reaction is carried away by inert nitrogen and part is carried away by the evaporated vinyl ether. This heat is removed through heat exchange in condenser I5. The condensed product, mainly vinyl ether, is sent to the subsequent refining process. The condensed nitrogen is sent to reactor II8 to continue the reaction and consume the unreacted acetylene.

[0007] In reactor II8, the reactant alcohol or alcohol / solvent from outside the interface, the supplementary catalyst, and the acetylene from condenser I5 react in reactor II8. Part of the heat of reaction is carried away by inert nitrogen and part is carried away by the evaporated vinyl ether. This heat is removed through heat exchange in condenser III9, while the condensed vinyl ether is returned to reactor II8. The condensed nitrogen is sent to acetylene / nitrogen mixing tank 1.

[0008] The liquid stream from reactor I3 is fed into flash tank 4 for flash evaporation. A small amount of unreacted acetylene and inert nitrogen are sent to acetylene / nitrogen mixing tank 1. The liquid stream from flash tank 4 is then sent to coarse separator 6 for separation. The top material of coarse separator 6 mainly consists of vinyl ether, low-boiling byproducts, a small amount of alcohol, and nitrogen, and is sent to the subsequent purification process. The bottom material of coarse separator 6 mainly consists of catalyst, unreacted alcohol or solvent, and a small amount of high-boiling substances. Most of this stream is returned to reactor I3, and a small amount is sent to the subsequent recovery process.

[0009] To improve reactor efficiency, and based on the chemical properties of alcohols, the acetylene / alcohol ratio in the feed is 1~2:1, with a preferred feed ratio of 1~1.5:1; the reaction pressure is generally 0.1~1.0 MPa, with a preferred reaction pressure of 0.3~0.7 MPa; the reaction temperature is 100~200℃, with a preferred reaction temperature of 140~180℃; and the residence time of the material in reactor I3 is controlled to be 30~240 minutes.

[0010] This invention provides another acetylene ethylene reaction apparatus and production process. To improve the acetylene conversion rate, the reaction temperature of this process is increased by 5-10°C compared to the previous process. The production apparatus includes a nitrogen / acetylene mixing tank 1, a compressor 2, a reactor, a flash tank 4, a crude separation tower 6, and several condensers.

[0011] Acetylene, circulating nitrogen, supplementary nitrogen, and the mixed gas from flash tank 4 are fed into nitrogen / acetylene mixing tank 1 for mixing, and then sent to reactor I 3 via compressor 2; In reactor I3, the reactants alcohol or alcohol / solvent from outside the reactor, the supplementary catalyst, and acetylene from compressor 2 react in the reactor. Part of the heat of reaction is carried away by inert nitrogen and part is carried away by the evaporated vinyl ether. This heat is removed through heat exchange in condenser I5, while the condensed vinyl ether is returned to reactor I3. The condensed nitrogen is sent to acetylene / nitrogen mixing tank 1.

[0012] The liquid stream from reactor I3 is fed into flash tank 4 for flash evaporation. A small amount of unreacted acetylene and inert nitrogen are sent to acetylene / nitrogen mixing tank 1. The liquid stream from flash tank 4 is then sent to coarse separator 6 for separation. The top material of coarse separator 6 mainly consists of vinyl ether, low-boiling byproducts, a small amount of alcohol, and nitrogen, and is sent to the subsequent purification process. The bottom material of coarse separator 6 mainly consists of catalyst, unreacted alcohol or solvent, and a small amount of high-boiling substances. Most of this stream is returned to reactor I3, and a small amount is sent to the subsequent recovery process.

[0013] To ensure effective mixing of acetylene, supplementary nitrogen, and circulating nitrogen, a mixing tank 1 is installed in the reaction system. Supplementary nitrogen and acetylene from the outside, nitrogen transferred from the reactor for heat dissipation, and nitrogen from the flash tank are effectively mixed in this mixing tank. The nitrogen / acetylene feed ratio is 1~2:1, preferably 1~1.5:1. To improve the efficient removal of reaction heat within the reactor, this reaction system employs two heat removal methods: First, it increases the circulation rate of inert nitrogen gas, with the nitrogen / acetylene ratio entering reactor I3 being 1-6:1, preferably 3-4:1; this large amount of nitrogen carries away a significant amount of heat. Second, the generated vinyl ether has a lower boiling point than the raw alcohol; the condensed vinyl ether product is returned to the reactor, increasing the vinyl ether content in the reactor, thereby allowing a large amount of vinyl ether to evaporate and remove the reaction heat. The vinyl ether content in reactor I3 is 10%-70%, preferably 20%-40%.

[0014] Compared with the prior art, the present invention has the following advantages in reaction system: (1) This reaction system reduces the number of moving parts in the reactor, ensuring long-term stable operation of the equipment.

[0015] (2) The reaction system uses nitrogen circulation, which reduces production costs and waste gas emissions; (3) This reaction system improves the reaction yield of acetylene; it not only improves the safety of the reaction, but also enhances the reaction mass transfer; (4) The reaction system is easy to operate and is conducive to continuous industrial production. Attached Figure Description

[0016] Figure 1 This is a simplified diagram of the reaction system of the present invention; Figure 2 A simplified diagram of the reaction system with one reactor. Among them: 1, nitrogen / acetylene mixing tank, 2, compressor, 3, reactor I, 4, flash tank, 5, condenser I, 6, coarse separator, 7, condenser II, 8, reactor II, 9, condenser III, and the lines are process pipelines. Detailed Implementation

[0017] All features disclosed in this specification, or steps in all disclosed methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

[0018] Any feature disclosed in this specification (including any appended claims, abstract, and drawings) may be replaced by other equivalent or similar features, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0019] The reaction apparatus and reaction system for synthesizing vinyl ethers according to the present invention will be described in more detail below.

[0020] According to an exemplary embodiment of the present invention, the reaction system for synthesizing vinyl ethers includes a nitrogen / acetylene mixing tank 1, a compressor 2, a reactor, several condensers, a flash tank 4, and a crude separator 6 connected in sequence.

[0021] Example 1: Nitrogen:acetylene was input into the reaction system at a ratio of 1:1, and the nitrogen / acetylene ratio entering reactor I was 3:1. Polyethylene glycol dimethyl ether was used as the solvent, the pressure inside the controller was 0.4 MPa, the reaction temperature was 130°C, and the residence time was 40 minutes. The acetylene:methanol ratio was 1:1, and the acetylene content in the tail gas of crude separator 6 was less than 0.3%. The yield of vinyl methyl ether was 95% (based on methanol).

[0022] Example 2: Nitrogen:acetylene was input into the reaction system at a ratio of 2:1, the nitrogen / acetylene ratio entering reactor I was 4:1, the pressure inside the controller was 0.7 MPa, the reaction temperature was 180°C, and the residence time was 90 minutes; the acetylene:n-butanol ratio was 1.5:1; the acetylene content in the tail gas of crude separator 6 was less than 0.5%; the yield of n-butyl vinyl ether was 90% (based on n-butanol).

[0023] However, this process is not limited to the synthesis of vinyl methyl ether and n-butyl vinyl ether, but also includes the synthesis of various alcohol compounds or condensed compounds of alcohols with hydroxyl groups, such as: ethanol, n-propanol, isobutanol, ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, etc. The vinyl ethers that can be synthesized include: vinyl ethyl ether, vinyl propyl ether, vinyl isobutyl ether, vinyl ethylene glycol ether, diethylene glycol monovinyl ether, diethylene glycol divinyl ether, etc.

[0024] In summary, the reactor and reaction system for synthesizing vinyl ethers of the present invention not only improves the safety of the reaction and enhances the mass transfer and heat transfer, but also ensures long-term stable operation of the reactor by eliminating the use of moving equipment, making it easy to operate and facilitate continuous industrial production.

[0025] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A gas-liquid process for preparing vinyl ethers, based on a reaction apparatus comprising a nitrogen / acetylene mixing tank (1), a compressor (2), two reactors, a flash tank (4), a crude separator (6), and several condensers; Its features are: The process includes the following steps: ① The mixture of acetylene, circulating nitrogen, supplementary nitrogen and flash tank (4) is fed into nitrogen / acetylene mixing tank (1) for mixing. The feed ratio of nitrogen / acetylene into nitrogen / acetylene mixing tank (1) is 1~2:

1. Then it is fed into reactor I (3) through compressor (2). The composition ratio of nitrogen / acetylene into reactor I (3) is 3~4:

1. ② The reactants from reactor II (8) react with acetylene from compressor (2) in reactor I (3). The nitrogen / acetylene composition ratio entering reactor I (3) is 1~6:

1. Part of the heat of reaction is carried out by inert nitrogen and part is carried out by the evaporated vinyl ether. The heat is removed by heat exchange through condenser I (5). The condensed product vinyl ether is sent to the subsequent refining process. The condensed nitrogen is sent to reactor II (8) to continue the reaction and consume the unreacted acetylene. The vinyl ether content in reactor I (3) is 10%~70%. ③ The reactants alcohol or alcohol / solvent from the outside, the supplementary catalyst and the acetylene from condenser I (5) react in reactor II (8). Part of the heat of reaction is carried out by inert nitrogen and part is carried out by the evaporated vinyl ether. This heat is removed by heat exchange through condenser III (9), and the condensed vinyl ether is returned to reactor II (8). The condensed nitrogen is sent into the acetylene / nitrogen mixing tank (1). ④ The liquid phase stream from reactor I (3) is sent to flash tank (4) for flashing. The small amount of unreacted acetylene and inert nitrogen is sent to acetylene / nitrogen mixing tank (1). The liquid phase stream from flash tank (4) is sent to crude separator (6) for separation. The top material of crude separator (6) includes vinyl ether, low-boiling byproduct, a small amount of alcohol and nitrogen. The top material of crude separator (6) is sent to the subsequent purification process. The bottom material of crude separator (6) includes catalyst, unreacted alcohol or solvent and a small amount of high-quality waste. Most of the bottom material of crude separator (6) is returned to reactor I (3), and a small amount is sent to the subsequent recovery process.

2. The production process for preparing vinyl ethers according to claim 1, characterized in that: The acetylene / alcohol feed ratio is 1~2:1, the reaction pressure is 0.1~1.0 MPa, and the reaction temperature is 100~200℃; the residence time of the material in reactor I (3) is controlled to be 30~240 minutes.

3. The production process for preparing vinyl ethers according to claim 2, characterized in that: The acetylene / alcohol feed ratio is 1~1.5:1, the reaction pressure is 0.3~0.7 MPa, and the reaction temperature is 140~180℃.

4. A gas-liquid process for preparing vinyl ethers, based on a reaction apparatus comprising a nitrogen / acetylene mixing tank (1), a compressor (2), a reactor, a flash tank (4), a crude fractionation tower (6), and several condensers; characterized in that: The process includes the following steps: ① The mixture of acetylene, circulating nitrogen, supplementary nitrogen and flash tank (4) is fed into nitrogen / acetylene mixing tank (1) for mixing. The feed ratio of nitrogen / acetylene into nitrogen / acetylene mixing tank (1) is 1~2:

1. Then it is fed into reactor I (3) through compressor (2). The composition ratio of nitrogen / acetylene into reactor I (3) is 3~4:

1. ② The reactants alcohol or alcohol / solvent from the outside, the supplementary catalyst, and the acetylene from the compressor (2) react in reactor I (3). The nitrogen / acetylene composition ratio entering reactor I (3) is 1~6:

1. Part of the heat of reaction is carried out by inert nitrogen and part is carried out by the evaporated vinyl ether. This heat is removed through heat exchange in condenser I (5), and the condensed vinyl ether is returned to reactor I (3). The condensed nitrogen is sent to the acetylene / nitrogen mixing tank (1). The vinyl ether content in reactor I (3) is 10%~70%. ③ The liquid phase stream from reactor I (3) is sent to flash tank (4) for flashing. The small amount of unreacted acetylene and inert nitrogen is sent to acetylene / nitrogen mixing tank (1). The liquid phase stream from flash tank (4) is sent to coarse separator (6) for separation. The top material of coarse separator (6) includes vinyl ether, low-boiling byproduct, a small amount of alcohol and nitrogen. The top material of coarse separator (6) is sent to the subsequent purification process. The bottom material of coarse separator (6) includes catalyst, unreacted alcohol or solvent and a small amount of high-quality waste. Most of the bottom material of coarse separator (6) is returned to reactor I (3), and a small amount is sent to the subsequent recovery process.

5. A production process for preparing vinyl ethers according to claim 1 or 4, characterized in that: The feed ratio of nitrogen / acetylene into the nitrogen / acetylene mixing tank (1) is 1~1.5:

1.

6. A production process for preparing vinyl ethers according to claim 1 or 4, characterized in that: The vinyl ether content in reactor I (3) is 20%~40%.

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