A method for preparing high-purity vinyl ethyl ether by liquid phase cleavage of acetaldehyde diethyl acetal

Abstract

This invention provides a method for preparing high-purity vinyl ethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The method includes the following steps: (1) mixing acetaldehyde diethanol, solvent, and catalyst to obtain a reaction solution; (2) preheating the reaction solution obtained in step (1) and then pumping it into a pipeline reactor for liquid-phase pyrolysis to obtain a pyrolysis solution; (3) flash evaporation and separation purification of the pyrolysis solution obtained in step (2) to obtain vinyl ethyl ether. This invention utilizes specific catalysts and solvents to achieve efficient pyrolysis of acetaldehyde diethanol, and combines flash evaporation and separation purification to achieve the separation and purification of reaction products and raw materials. Moreover, the method has the characteristics of good process stability, mild reaction conditions, continuous long-term production operation, high product purity, low waste, and high energy efficiency, and has good application prospects.

Description

Technical Field

[0001] This invention belongs to the field of vinyl ethyl ether preparation technology, and particularly relates to a method for preparing high-purity vinyl ethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. Background Technology

[0002] Vinyl ethyl ether (EVE) is an important organic synthesis intermediate and monomer for polymers. Its homopolymers and copolymers are widely used in adhesives, coatings, cosmetics, oral care products, lubricants, plasticizers, pesticides, and surface protection materials. Vinyl ether monomers are odorless, have low toxicity, and cure quickly under UV or electron beam light; furthermore, their low viscosity allows for spray application, improving construction efficiency, and thus they are receiving increasing attention.

[0003] The reactive double bond properties of vinyl ethers have led to their wide application in organic synthesis, such as in the Diels-Alder reaction and the preparation of compounds like glutaraldehyde, γ-pyran, and γ-pyridine. Vinyl ethers can also be used in the synthesis of β-lactams, which are important intermediates in the formation of many antibiotic drug skeletons and play a crucial role in the synthesis of β-amino acid drugs. Furthermore, due to the excellent properties of vinyl ether monomers, vinyl ether / N-vinylpyrrolidone copolymers are used as medical hydrogels in the pharmaceutical field due to their good biocompatibility. In the coatings industry, vinyl ethers can act as reactive diluents, reducing system viscosity and participating in free radical curing reactions.

[0004] However, vinyl ethers cannot be prepared using conventional ether preparation methods. This is because vinyl alcohol is not available, and potassium or sodium vinyl alcohol cannot be used to react with haloalkanes; while haloalkenes exhibit almost no nucleophilic substitution activity, and cannot be prepared using vinyl chloride and sodium alkoxides. Currently, the main methods for preparing vinyl ethers are the acetylene process and the acetal cracking process. The synthesis of vinyl ethers using acetylene and ethanol under a strong basic catalyst has a short catalyst lifetime and poor safety. GB 616197A discloses an improved method using a high-boiling-point ether as a solvent and an alkali metal acetylene compound as a catalyst at atmospheric pressure, but this method has a very short start-up time and cannot achieve large-scale production. R. Rigamont et al. studied the nucleophilic addition reaction of acetylene and ethanol under a superbase KOH-DMSO catalyst system, achieving a vinyl ether yield of up to 90%, and the reaction can be carried out at atmospheric pressure. US Patent 3, 341, 606. 1967 reported a method for preparing vinyl ether compounds by direct reaction of CaC2 with alcohols, with a reaction yield of 15.4%. However, the calcium carbide method currently has problems such as significant safety hazards, short catalyst cycle, and low product purity.

[0005] It is evident that the preparation of vinyl ether products still suffers from problems such as low catalyst efficiency, high energy consumption, high cost, environmental unfriendliness, poor process stability, or insufficient product purity. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing high-purity vinyl ethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. This method achieves low-cost and efficient preparation of high-purity vinyl ethyl ether by using a specific pyrolysis catalyst combined with a specific pyrolysis process.

[0007] To achieve this objective, the present invention adopts the following technical solution: This invention provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol, the method comprising the following steps: (1) Mix acetaldehyde diethanol, solvent and catalyst to obtain a reaction solution; (2) The reaction solution obtained in step (1) is preheated and then pumped into a pipeline reactor to carry out liquid phase pyrolysis reaction to obtain pyrolysis solution; (3) The lysate obtained in step (2) is subjected to flash evaporation and separation purification to obtain vinyl ethyl ether.

[0008] This invention utilizes a specific catalyst and solvent to conduct a continuous reaction, achieving efficient cracking of acetaldehyde diethanol. Subsequent flash evaporation and separation purification are then used to separate and purify the reaction products and raw materials. However, reaction systems containing post-restriction agents will experience intermittent reactions, and the role of the restriction agent is to prevent the cracking products from decomposing during storage. The reaction provided by this invention is a continuous reaction and does not require the addition of a restriction agent.

[0009] In addition, the method provided by this invention has the characteristics of good process stability, mild reaction conditions, continuous long-cycle production operation, high product purity, low waste, and high energy efficiency, and has good application prospects.

[0010] As a preferred technical solution of the present invention, the catalyst in step (1) is an organic acid catalyst.

[0011] Preferably, the organic acid catalyst comprises a main component and an auxiliary agent.

[0012] Preferably, the weight ratio of the main component to the auxiliary agent is 10:1 to 3, for example, it can be 10:1, 10:1.5, 10:2, 10:2.5 or 10:3, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0013] Preferably, the main component includes p-toluenesulfonic acid or methanesulfonic acid.

[0014] Preferably, the adjuvant includes amine organic compounds.

[0015] Preferably, the amine organic compound is a high-boiling-point alkyl amine, including any one or a combination of at least two of diisooctylamine, triisooctylamine, or di-n-octylamine. Typical but non-limiting combinations include: a combination of diisooctylamine and triisooctylamine, a combination of diisooctylamine and di-n-octylamine, a combination of triisooctylamine and di-n-octylamine, or a combination of diisooctylamine, triisooctylamine, and di-n-octylamine.

[0016] Preferably, the catalyst content in the reaction solution in step (1) is 0.1~0.25wt%, for example, it can be 0.1wt%, 0.13wt%, 0.16wt%, 0.19wt%, 0.22wt% or 0.25wt%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] The organic acid catalyst described in this invention is widely available, low in cost, highly active, and selective. When used to crack acetaldehyde diethanol, it produces fewer cracking products, and the main components of the cracking products have large boiling point differences under normal pressure, making them easy to separate. However, if the content of the organic acid catalyst is too high, it will lead to an increase in by-product polymers.

[0018] As a preferred embodiment of the present invention, the purity of the acetaldehyde diethanol is ≥99%, for example, it can be 99%, 99.1%, 99.2%, 99.3%, 99.4% or 99.5%, etc., but is not limited to the listed values. Other values ​​not listed within the value range are also applicable.

[0019] Preferably, the content of acetaldehyde diethanol in the reaction solution in step (1) is >30wt%, for example, it can be 35wt%, 40wt%, 50wt%, 55wt%, 60wt%, 70wt% or 75wt%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 60~75wt%.

[0020] Preferably, the solvent in step (1) includes white oil.

[0021] Preferably, the white oil includes any one or at least two combinations of 3# white oil, 5# white oil, 7# white oil, or 10# white oil. Typical but non-limiting combinations include: a combination of 3# white oil and 5# white oil, a combination of 7# white oil and 10# white oil, a combination of 3# white oil, 5# white oil, and 7# white oil, a combination of 5# white oil, 7# white oil, and 10# white oil, or a combination of 3# white oil, 5# white oil, 7# white oil, and 10# white oil.

[0022] In this invention, when the content of acetaldehyde diethanol in the reaction solution is too high, the reaction pressure of the reaction system increases, which in turn leads to an increase in the acetylene feed pressure, increasing the risk of acetylene self-polymerization and increasing equipment investment; when it is too low, the reaction rate will be slow.

[0023] As a preferred technical solution of the present invention, the temperature of the preheating treatment in step (2) is 130~140℃, for example, it can be 130℃, 132℃, 134℃, 136℃, 138℃ or 140℃, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] The purpose of the preheating treatment described in this invention is to initiate the pyrolysis reaction immediately when the material enters the reactor; if the preheating temperature is too high, it will lead to an increase in by-product impurities, and if it is too low, it will lead to a slow reaction rate.

[0025] Preferably, the space-time velocity of the pump in step (2) is 0.6~2.0h. -1 For example, it could be 0.6h -1 0.8h -1 1.0h -1 1.2h -1 1.4h -1 1.6h -1 1.8h -1 or 2.0h -1 This applies to, but is not limited to, the listed values; other unlisted values ​​within the range are also applicable.

[0026] The space-time velocity of the pump described in this invention affects the single-pass conversion rate of the reaction. If the velocity is too high, the flow rate will be too large, which will correspondingly increase the load on the distillation column, and the separation cost and equipment investment will increase accordingly; if the velocity is too low, it will lead to an increase in by-products and impurities.

[0027] As a preferred technical solution of the present invention, the temperature of the liquid phase pyrolysis reaction in step (2) is 135~145℃, for example, it can be 135℃, 137℃, 139℃, 141℃, 143℃ or 145℃, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] The temperature of the liquid phase pyrolysis reaction described in this invention is 135~145℃. If the temperature is too low, the reaction rate will be slow, and if the temperature is too high, the by-product impurities will increase. In addition, the pipeline reactor needs to be insulated during the liquid phase pyrolysis reaction, and a back pressure valve is used at the outlet to maintain the pressure; the pressure is 0.35~0.45MPa, for example, it can be 0.35MPa, 0.37MPa, 0.39MPa, 0.41MPa, 0.43MPa or 0.45MPa, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0029] As a preferred technical solution of the present invention, the top temperature of the flash tower used in the flash treatment in step (3) is 45~55℃, for example, it can be 45℃, 47℃, 49℃, 51℃, 53℃ or 55℃, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] In this invention, the condenser at the top of the tower is controlled by reflux using circulating water at 25°C during the flash evaporation process.

[0031] Preferably, the purity of the vinyl ethyl ether in step (3) is ≥98.0%, for example, it can be 98.0%, 98.2%, 98.4%, 98.6%, 98.8% or 99.0%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] Preferably, the ethanol content in the vinyl ether in step (3) is <1%, for example, it can be 0.9%, 0.8%, or 1%. As a preferred embodiment of the present invention, the method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol provided by the present invention includes the following steps: (1) Mix acetaldehyde diethanol with a purity ≥99%, white oil and organic acid catalyst to obtain a reaction solution; The reaction solution contains >30 wt% acetaldehyde diethanol and 0.1-0.25 wt% organic acid catalyst. The organic acid catalyst comprises a main component and an auxiliary agent in a weight ratio of 10:1 to 3; the main component comprises p-toluenesulfonic acid or methanesulfonic acid, and the auxiliary agent comprises any one or a combination of at least two of diisooctylamine, triisooctylamine or di-n-octylamine; (2) The reaction solution obtained in step (1) is preheated, and then subjected to a heat treatment of 0.6~2.0h. -1 The liquid-phase pyrolysis reaction is carried out in a pipeline reactor at a spacetime velocity to obtain a pyrolysis solution. The preheating temperature is 130~140℃; the liquid phase pyrolysis reaction temperature is 135~145℃; (3) The pyrolysis solution obtained in step (2) was flash-treated by a flash evaporator and then separated and purified to obtain vinyl ether with a purity ≥ 98.0%; The temperature at the top of the flash tower is 45~55℃.

[0033] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0034] Compared with the prior art, the present invention has the following beneficial effects: (1) The liquid phase pyrolysis method provided by the present invention has the characteristics of good process stability, mild reaction conditions, continuous long-cycle production and operation, simple equipment, low investment, high product purity, less waste, and high energy efficiency, and has good application prospects. (2) This invention uses steam as the heat source for preheating and liquid phase pyrolysis reaction, and white oil as the solvent, which can significantly reduce the reaction temperature and the heat source is clean and environmentally friendly. (3) This invention combines liquid phase pyrolysis and purification, and achieves the separation and purification of reaction products and raw materials simultaneously through flash evaporation of the pyrolysis liquid; (4) The catalyst described in this invention has a wide range of sources, low cost, high catalytic activity, strong selectivity, few components of cracking products, and the main components of cracking products have a large difference in boiling point under normal pressure, making them easy to separate. Attached Figure Description

[0035] Figure 1 A schematic diagram of the apparatus system used in the method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol in Embodiment 1 of the present invention is provided. Among them, 1 is the raw material preparation tank, 2 is the first feed pump, 3 is the preheater, 4 is the pipeline reactor, 5 is the flash tower, 6 is the intermediate storage tank, 7 is the first tail gas collector, 8 is the second feed pump, 9 is the distillation tower, 10 is the second tail gas collector, 11 is the product storage tank, 12 is the reboiler circulation pump, and 13 is the reboiler. Detailed Implementation

[0036] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0037] The reagents used in the following examples and comparative examples are all commercially available products.

[0038] Example 1 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The method employs the following techniques: Figure 1 The device system shown is used, specifically including the following steps: (1) In the raw material preparation tank 1, acetaldehyde diethanol with a purity of 99%, white oil (D80) and organic acid catalyst are mixed to obtain a reaction solution; The reaction solution contains 65 wt% acetaldehyde diethanol and 0.20 wt% organic acid catalyst. The organic acid catalyst comprises a main component and an auxiliary agent in a weight ratio of 10:2; the main component is p-toluenesulfonic acid, and the auxiliary agent is diisooctylamine; (2) The reaction liquid obtained in step (1) is pumped into the preheater 3 by the first feed pump 2 for preheating treatment, and then at 1.0h -1 The liquid phase pyrolysis reaction is carried out by pumping the solution into the pipeline reactor 3 at a spacetime velocity to obtain the pyrolysis liquid. The preheating temperature is 135°C; the liquid phase pyrolysis reaction temperature is 140°C. (3) The pyrolysis liquid obtained in step (2) is flashed in the flash tower 5. The uncondensed gas and the material collected by the first tail gas collector 7 are condensed and mixed to obtain vinyl ethyl ether semi-finished product, which is stored in the intermediate storage tank 6. Then, the second feed pump is used to pump it into the distillation tower 9 for separation and purification. The uncondensed gas at the top of the tower and the material collected by the second tail gas collector 10 are condensed and mixed to obtain vinyl ethyl ether, which is stored in the product storage tank 11. The top of the flash evaporator is controlled by reflux using 25°C circulating water, and the temperature at the top of the tower is controlled to 50°C by controlling the flow rate of the circulating water. The bottom of the distillation column 9 is equipped with a reboiler 13 and a reboiler circulation pump 12; the top temperature of the separation and purification is 33~35℃, and the bottom temperature is 85~90℃.

[0039] Example 2 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol, the method comprising the following steps: (1) In the raw material preparation tank 1, acetaldehyde diethanol with a purity of 99.2%, white oil and organic acid catalyst are mixed to obtain a reaction solution; The reaction solution contains 50 wt% acetaldehyde diethanol and 0.15 wt% organic acid catalyst. The organic acid catalyst comprises a main component and an auxiliary agent in a weight ratio of 10:1; the main component is methanesulfonic acid, and the auxiliary agent is triisooctylamine; (2) The reaction liquid obtained in step (1) is pumped into the preheater 3 by the first feed pump 2 for preheating treatment, and then the reaction liquid is heated for 1.5 hours. -1 The liquid phase pyrolysis reaction is carried out by pumping the solution into the pipeline reactor 3 at a spacetime velocity to obtain the pyrolysis liquid. The preheating temperature is 130°C; the liquid phase pyrolysis reaction temperature is 135°C; (3) The pyrolysis liquid obtained in step (2) is flashed in the flash tower 5. The uncondensed gas and the material collected by the first tail gas collector 7 are condensed and mixed to obtain vinyl ethyl ether semi-finished product, which is stored in the intermediate storage tank 6. Then, the second feed pump is used to pump it into the distillation tower 9 for separation and purification. The uncondensed gas at the top of the tower and the material collected by the second tail gas collector 10 are condensed and mixed to obtain vinyl ethyl ether, which is stored in the product storage tank 11. The top of the flash evaporator is controlled by reflux using 25°C circulating water, and the temperature at the top of the tower is controlled to be 45°C by controlling the flow rate of the circulating water. The bottom of the distillation column 9 is equipped with a reboiler 13 and a reboiler circulation pump 12; the top temperature of the separation and purification is 33~35℃, and the bottom temperature is 85~90℃.

[0040] Example 3 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol, the method comprising the following steps: (1) In the raw material preparation tank 1, acetaldehyde diethanol with a purity of 99.5%, white oil and organic acid catalyst are mixed to obtain a reaction solution; The reaction solution contains >30 wt% acetaldehyde diethanol and 0.22 wt% organic acid catalyst. The organic acid catalyst comprises a main component and an auxiliary agent in a weight ratio of 10:1 to 3; the main component is p-toluenesulfonic acid, and the auxiliary agent is di-n-octylamine; (2) The reaction liquid obtained in step (1) is pumped into the preheater 3 by the first feed pump 2 for preheating treatment, and then at 1.6h -1 The liquid phase pyrolysis reaction is carried out by pumping the solution into the pipeline reactor 3 at a spacetime velocity to obtain the pyrolysis liquid. The preheating temperature is 140°C; the liquid phase pyrolysis reaction temperature is 145°C. (3) The pyrolysis liquid obtained in step (2) is flashed in the flash tower 5. The uncondensed gas and the material collected by the first tail gas collector 7 are condensed and mixed to obtain vinyl ethyl ether semi-finished product, which is stored in the intermediate storage tank 6. Then, the second feed pump is used to pump it into the distillation tower 9 for separation and purification. The uncondensed gas at the top of the tower and the material collected by the second tail gas collector 10 are condensed and mixed to obtain vinyl ethyl ether, which is stored in the product storage tank 11. The top of the flash evaporator is controlled by reflux using 25°C circulating water, and the temperature at the top of the tower is controlled to be 55°C by controlling the flow rate of the circulating water. The bottom of the distillation column 9 is equipped with a reboiler 13 and a reboiler circulation pump 12; the top temperature of the separation and purification is 33~35℃, and the bottom temperature is 85~90℃.

[0041] Example 4 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The only difference between this method and Example 1 is that: In this embodiment, the spacetime velocity described in step (2) is adjusted to 0.6h. -1 .

[0042] Example 5 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The only difference between this method and Example 1 is that: In this embodiment, the spacetime velocity described in step (2) is adjusted to 1.5h. -1 .

[0043] Example 6 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The only difference between this method and Example 1 is that: In this embodiment, the spacetime velocity described in step (2) is adjusted to 2.0h. -1 .

[0044] Example 7 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The only difference between this method and Example 1 is that: In this embodiment, the content of acetaldehyde diethanol in the reaction solution in step (1) is adjusted to 60 wt%.

[0045] Example 8 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The only difference between this method and Example 1 is that: In this embodiment, the content of acetaldehyde diethanol in the reaction solution described in step (1) is adjusted to 70 wt%.

[0046] Example 9 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The only difference between this method and Example 1 is that: In this embodiment, the content of acetaldehyde diethanol in the reaction solution described in step (1) is adjusted to 75 wt%.

[0047] Example 10 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The only difference between this method and Example 1 is that: In this embodiment, the content of acetaldehyde diethanol in the reaction solution described in step (1) is adjusted to 20 wt%.

[0048] Example 11 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The only difference between this method and Example 1 is that: In this embodiment, the catalyst content in the reaction solution described in step (1) is adjusted to 0.1 wt%. Example 12 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The only difference between this method and Example 1 is that: In this embodiment, the content of catalyst in the reaction solution described in step (1) is adjusted to 0.15 wt%.

[0049] Example 13 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The only difference between this method and Example 1 is that: In this embodiment, the catalyst content in the reaction solution described in step (1) is adjusted to 0.25 wt%. Example 14 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The only difference between this method and Example 1 is that: In this embodiment, the content of catalyst in the reaction solution described in step (1) is adjusted to 0.30 wt%.

[0050] Example 15 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The only difference between this method and Example 1 is that: In this embodiment, the temperature of the liquid phase pyrolysis reaction in step (2) is adjusted to 125°C.

[0051] Example 16 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The only difference between this method and Example 1 is that: In this embodiment, the temperature of the liquid phase pyrolysis reaction in step (2) is adjusted to 150°C.

[0052] Example 17 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The only difference between this method and Example 1 is that: In this embodiment, the solvent in step (1) is adjusted to an equal amount of methyl silyl ether.

[0053] Example 18 This embodiment provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The only difference between this method and Example 1 is that: The catalyst auxiliary agent is omitted in this embodiment.

[0054] Comparative Example 1 This comparative example provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The only difference between this method and Example 1 is that: In this comparative example, steps (1)-(2) are adjusted to: mixing acetaldehyde diethanol, liquid medium (phenylmethyl silyl ether), catalyst (p-toluenesulfonic acid) and retarder (pyridine); and then carrying out the pyrolysis reaction at 250°C; The catalyst is used at 0.5% of the liquid medium, and the retarder is used at 8% of the raw materials.

[0055] Comparative Example 2 This comparative example provides a method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol. The only difference between this method and Example 1 is that: The preheating process is omitted in this comparative example.

[0056] Application examples The products obtained using the methods provided in the above embodiments and comparative examples were analyzed, and the results are shown in Table 1.

[0057] Table 1 Note: The methyl silyl ether used in Example 17 has a low boiling point and requires a high pressure for the reaction. It cannot react under low pressure conditions, so it is indicated by "-".

[0058] According to Table 1, the following points can be observed: (1) Comprehensive analysis of Examples 1-3 shows that the method provided by the present invention can achieve efficient cracking of acetaldehyde diethanol; and the obtained product has high purity; (2) Comprehensive analysis of Examples 1 and 4-6 shows that the space-time velocity affects the single-pass conversion efficiency; as the space-time velocity increases, the reaction conversion rate gradually decreases and the selectivity gradually increases, but the product purity decreases; if the space-time velocity is too high, it will lead to an increase in the single-pass conversion rate and an increase in side reactions. (3) Comprehensive analysis of Examples 1 and 7-10 shows that the content of acetaldehyde diethanol in the reaction solution will affect the change of reaction pressure; as its content increases, the reaction conversion rate gradually decreases, the selectivity gradually increases, and the product purity also increases; if the content of acetaldehyde diethanol in the reaction solution is too low, the reaction rate will decrease. (4) Comprehensive analysis of Examples 1 and 11-14 shows that the content of catalyst in the reaction solution affects the reaction rate; as the catalyst content increases, the reaction conversion rate increases, but the product purity decreases; if the catalyst content is too high, it will lead to an increase in side reactions. (5) Comprehensive analysis of Examples 1 and 15-16 shows that a higher temperature in the liquid phase pyrolysis reaction will lead to an increase in side reactions, while a lower temperature will lead to a slower reaction. (6) Comprehensive analysis of Examples 1 and 17-18 shows that the composition of the reaction system during the liquid phase pyrolysis reaction affects the progress of the reaction process; if the solvent is changed to methyl silyl ether (as in Example 17), the boiling point of the system will decrease, the reaction pressure required to raise the system to the reaction temperature will increase significantly, and the compressor equipment required for acetylene feed will be more expensive; if the auxiliary agent in the catalyst is omitted (as in Example 18), the system will be too acidic, the product will polymerize in small amounts, resulting in more impurities and a lower yield; thus further illustrating the uniqueness of the catalyst and solvent selected in the pyrolysis system provided by the present invention. (7) Comprehensive analysis of Example 1 and Comparative Example 1 shows that, compared with the reaction system provided by the present invention, the reaction system provided by Comparative Example 1 has disadvantages such as high reaction temperature, high reaction pressure, and inability to react continuously.

[0059] In summary, this invention utilizes specific catalysts and solvents to achieve efficient cracking of acetaldehyde diethanol, and combines flash evaporation and separation purification to separate and purify the reaction products and raw materials. Furthermore, the method features good process stability, mild reaction conditions, continuous long-cycle production operation, high product purity, low waste, and high energy efficiency, and has promising application prospects.

[0060] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol, characterized in that, The method includes the following steps: (1) Mix acetaldehyde diethanol, solvent and catalyst to obtain a reaction solution; (2) The reaction solution obtained in step (1) is preheated and then pumped into a pipeline reactor to carry out liquid phase pyrolysis reaction to obtain pyrolysis solution; (3) The lysate obtained in step (2) is subjected to flash evaporation and separation purification to obtain vinyl ethyl ether.

2. The method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol according to claim 1, characterized in that, The catalyst mentioned in step (1) is an organic acid catalyst; Preferably, the organic acid catalyst comprises a main component and an auxiliary agent.

3. The method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol according to claim 2, characterized in that, The weight ratio of the main component to the auxiliary agent is 10:1~3; Preferably, the main component includes p-toluenesulfonic acid or methanesulfonic acid; Preferably, the adjuvant includes amine organic compounds; Preferably, the amine organic compound includes any one or a combination of at least two of diisooctylamine, triisooctylamine, or di-n-octylamine.

4. The method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol according to claim 2, characterized in that, The catalyst content in the reaction solution in step (1) is 0.1~0.25wt%.

5. The method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol according to claim 1, characterized in that, The purity of the acetaldehyde diethanol is ≥99%; Preferably, the content of acetaldehyde diethanol in the reaction solution in step (1) is >30wt%.

6. The method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol according to claim 1, characterized in that, The solvent in step (1) includes white oil.

7. The method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol according to claim 1, characterized in that, The temperature of the preheating treatment in step (2) is 130~140℃; Preferably, the space-time velocity of the pump in step (2) is 0.6~2.0h. -1 .

8. The method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol according to claim 1, characterized in that, The temperature of the liquid phase pyrolysis reaction in step (2) is 135~145℃.

9. The method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol according to claim 1, characterized in that, The top temperature of the flash tower used in step (3) is 45~55℃; Preferably, the purity of the vinyl ethyl ether in step (3) is ≥98.0%.

10. The method for preparing high-purity vinyl diethyl ether by liquid-phase pyrolysis of acetaldehyde diethanol according to any one of claims 1-9, characterized in that, The method includes the following steps: (1) Mix acetaldehyde diethanol with a purity ≥99%, solvent and organic acid catalyst to obtain reaction solution; The reaction solution contains >30 wt% acetaldehyde diethanol and 0.1-0.25 wt% organic acid catalyst. The organic acid catalyst comprises a main component and an auxiliary agent in a weight ratio of 10:1 to 3; the main component comprises p-toluenesulfonic acid or methanesulfonic acid, and the auxiliary agent comprises any one or a combination of at least two of diisooctylamine, triisooctylamine or di-n-octylamine; (2) The reaction solution obtained in step (1) is preheated, and then subjected to a heat treatment of 0.6~2.0h. -1 The liquid-phase pyrolysis reaction is carried out in a pipeline reactor at a spacetime velocity to obtain a pyrolysis solution. The preheating temperature is 130~140℃; the liquid phase pyrolysis reaction temperature is 135~145℃; (3) The pyrolysis solution obtained in step (2) was flash-treated by a flash evaporator and then separated and purified to obtain vinyl ether with a purity ≥ 98.0%; The temperature at the top of the flash tower is 45~55℃.

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