A method and system for the fixed bed alcoholysis of fusel oils

Abstract

The application belongs to the technical field of fusel oil treatment, and discloses a method and system for fixed-bed alcoholysis of fusel oil, which comprises the following steps: a mixed solution of fusel oil and solvent is divided into two streams, the first stream enters an upper catalyst bed of a fixed-bed alcoholysis reactor, and the second stream enters a lower catalyst bed of the fixed-bed alcoholysis reactor; the material reacted in the upper catalyst bed is led out of the reactor, then mixed with the second stream of the mixed solution of fusel oil and solvent, and then enters the lower catalyst bed for alcoholysis reaction; the material reacted in the lower catalyst bed is divided into two streams, the first stream is taken out as a product and enters a downstream separation unit, and the second stream is divided into two paths, the first path is mixed with the first stream of the mixed solution of fusel oil and solvent, and then enters the upper catalyst bed for alcoholysis reaction, and the second path enters the lower catalyst bed for alcoholysis reaction. The application can solve the problem that a large amount of fusel oil is produced as a byproduct in the oxalate method synthesis route and is difficult to treat.

Description

Technical Field

[0001] This invention relates to the field of fusel oil processing technology, and more specifically, to a method and system for fixed-bed alcoholysis of fusel oil. Background Technology

[0002] Polyglycolic acid (PGA) boasts high heat resistance, high strength, rapid degradation, strong oxygen barrier properties, and excellent solvent resistance, making it widely used in numerous fields such as medicine, agriculture, forestry, and packaging. In recent years, researchers have developed an oxalate ester process for PGA production, building upon ethylene glycol technology by controlling the depth of hydrogenation. PGA production generates a large amount of byproducts, with organic matter accounting for over 50%, primarily monohydric alcohols, dihydric alcohols, and oligomers. Existing manufacturers almost exclusively sell their fusel oil directly, resulting in low market prices. Furthermore, the increasing storage volume poses a concern and burden for these companies. There is an urgent need to develop a fusel oil treatment method that can maximize economic benefits while meeting green production requirements, enabling coal chemical enterprises to move towards clean and low-carbon production.

[0003] Alcohololysis is a commonly used method in the chemical degradation of various polyesters. The alcohololysis process typically utilizes metal and composite metal oxide catalysts, ionic liquid catalysts, or metal salt catalysts. The size of the catalyst affects the contact area between the material and the catalyst, thus influencing the degree of degradation.

[0004] Metal and composite metal oxide solid-phase catalysts are easily separated from the reaction solution after the reaction, thus reducing catalyst contamination of degradation products and improving the purity of the target product. However, their relatively small specific surface area results in a small contact area with the raw materials, leading to low degradation efficiency. They often require high temperature or high pressure conditions, which reduces safety and increases the requirements for reaction equipment materials. Metal salt catalysts, completely dissolved in solution, are difficult to separate. This affects solution recovery and reuse, and the residual metal salts in the solution contaminate the final product, reducing its purity. Furthermore, the acidity of the dissolved metal salts corrodes the reaction vessel, increasing the requirements for reactor materials and raising production costs. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for fixed-bed alcoholysis of fusel oil, which can solve the problem of difficult handling of large amounts of fusel oil produced as a byproduct in the oxalate ester synthesis route. The fixed-bed alcoholysis technology used ensures sufficient contact between the liquid and solid phases, avoids the subsequent complex catalyst recovery steps, reduces equipment requirements and investment, and enhances the operational flexibility of the equipment.

[0006] To achieve the above objectives, one aspect of the present invention provides a method for fixed-bed alcoholysis of fusel oil, the method comprising:

[0007] The mixed solution of fusel oil and solvent is divided into two streams. The first stream enters the upper catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction, and the second stream enters the lower catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction.

[0008] The material after reaction in the upper catalyst bed of the fixed-bed alcoholysis reactor is led out of the reactor and then mixed with a second stream of the mixed solution of fusel oil and solvent before entering the lower catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction.

[0009] After the reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor, the material is divided into two streams. The first stream is discharged as the product and enters the downstream separation unit. The second stream is further divided into two paths. The first path is mixed with the first stream of the mixed solution of fusel oil and solvent and then enters the upper catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction. The second path enters the lower catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction.

[0010] Another aspect of the present invention provides a system for fixed-bed alcoholysis of fusel oil, the system comprising:

[0011] A fixed-bed alcoholysis reactor, wherein an upper catalyst bed and a lower catalyst bed are provided inside the fixed-bed alcoholysis reactor;

[0012] The feed line for the mixed solution of fusel oil and solvent is divided into two lines. The first line is connected to the first inlet of the fixed-bed alcoholysis reactor, and the second line is connected to the second inlet of the fixed-bed alcoholysis reactor.

[0013] The outlet of the upper catalyst bed of the fixed-bed alcoholysis reactor is connected to the outlet pipeline of the upper catalyst bed, and the outlet pipeline of the upper catalyst bed is connected to the second path of the feed pipeline of the mixed solution of fusel oil and solvent.

[0014] The outlet of the lower catalyst bed of the fixed-bed alcoholysis reactor is connected to the outlet pipeline of the lower catalyst bed. The outlet pipeline of the lower catalyst bed is divided into two paths. The first path is connected to the downstream separation unit, and the second path is further divided into two branches. The first branch is connected to the first path of the feed pipeline of the mixed solution of fusel oil and solvent, and the second branch is connected to the third inlet of the fixed-bed alcoholysis reactor.

[0015] Preferably, the first feed inlet is located at the upper part of the fixed-bed alcoholysis reactor, and the second and third feed inlets are both located in the middle part of the fixed-bed alcoholysis reactor, with the second and third feed inlets situated between the upper catalyst bed and the lower catalyst bed.

[0016] The technical solution of the present invention has the following beneficial effects:

[0017] This invention can solve the problem of the difficult handling of a large amount of fusel oil produced as a byproduct in the oxalate synthesis route. The fixed-bed alcoholysis technology used ensures sufficient contact between the liquid and solid phases, avoids the subsequent complex catalyst recovery steps, reduces equipment requirements and investment, and enhances the operational flexibility of the unit.

[0018] This invention uses a single alcoholysis reactor with catalyst packed in two layers, saving the need for multiple reactor stages, as well as inter-stage equipment and pipelines, thus reducing investment costs.

[0019] By using this invention, the mixed solution is divided into two streams, which enter different catalyst beds respectively, resulting in a more balanced reaction of the fusel oil entering the catalyst bed and effectively ensuring the distribution of the reaction zone and the stability of the reaction temperature.

[0020] In this invention, the material preferably enters from the top of the reactor and exits from the bottom, which makes the material distribution in the reaction bed more uniform, the catalyst utilization rate is high, the reaction effect is good, and the investment is low.

[0021] The reaction operation of this invention is flexible, which is beneficial for improving catalyst selectivity and extending catalyst lifetime.

[0022] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0023] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0024] Figure 1 A schematic structural diagram of a fixed-bed alcoholysis system for fusel oil according to an embodiment of the present invention is shown.

[0025] Explanation of reference numerals in the attached figures:

[0026] 1. Fixed-bed alcoholysis reactor; 2. First heat exchanger; 3. Second heat exchanger; 4. First feed inlet of the fixed-bed alcoholysis reactor; 5. Second feed inlet of the fixed-bed alcoholysis reactor; 6. Third feed inlet of the fixed-bed alcoholysis reactor; 7. Outlet of the lower catalyst bed of the fixed-bed alcoholysis reactor; 101. Fusel oil; 102. Solvent; 103. First stream of material after reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor. Detailed Implementation

[0027] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0028] One aspect of the present invention provides a method for fixed-bed alcoholysis of fusel oil, the method comprising:

[0029] The mixed solution of fusel oil and solvent is divided into two streams. The first stream enters the upper catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction, and the second stream enters the lower catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction.

[0030] The material after reaction in the upper catalyst bed of the fixed-bed alcoholysis reactor is led out of the reactor and then mixed with a second stream of the mixed solution of fusel oil and solvent before entering the lower catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction.

[0031] After the reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor, the material is divided into two streams. The first stream is discharged as the product and enters the downstream separation unit. The second stream is further divided into two paths. The first path is mixed with the first stream of the mixed solution of fusel oil and solvent and then enters the upper catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction. The second path enters the lower catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction.

[0032] According to the present invention, preferably, after the material reacting in the upper catalyst bed of the fixed-bed alcoholysis reactor is led out of the reactor and heat-exchanged, it is then mixed with a second stream of the mixed solution of fusel oil and solvent before entering the lower catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction; preferably, after heat exchange to 170-220°C, more preferably after heat exchange to 180-210°C, it is then mixed with a second stream of the mixed solution of fusel oil and solvent before entering the lower catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction. This can improve the effective utilization rate of the catalyst.

[0033] According to the present invention, preferably, the second stream of material after reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor is divided into two streams after heat exchange;

[0034] Preferably, after heat exchange to 170–220°C, and more preferably, after heat exchange to 180–210°C, it is divided into two paths.

[0035] In this invention, the alcoholysis reaction material from the lower catalyst bed is extracted for liquid-phase separation. The separated liquid phase may or may not undergo heat exchange, but preferably it is heated to 170-220°C and returned as liquid-phase feedstock for the upper or lower catalyst bed. This improves the effective utilization rate of the catalyst.

[0036] According to the present invention, preferably, the solvent is a saturated monohydric alcohol, more preferably a C1-C4 saturated monohydric alcohol, and more preferably methanol;

[0037] The fusel oil includes: small molecule compounds, high-boiling polymers, and optional heavy impurities;

[0038] The small molecule compounds include: ethylene glycol, optionally glycolic acid, optionally methyl glycolate, and optionally other diols;

[0039] The high-boiling polymer is a polymer generated by polymerization of at least one of ethylene glycol, glycolic acid, and methyl glycolate.

[0040] Preferably, based on the total weight of the fusel oil, the content of the high-boiling polymer is not less than 5 wt%, preferably 10-80 wt%; the content of ethylene glycol is 15-80 wt%, the content of methyl glycolate is 0-30 wt%, the content of glycolic acid is 0-10 wt%, the content of other diols is 0-10 wt%, and the content of heavy impurities is 0-5 wt%.

[0041] Preferably, the pH value of the fusel oil is 2-6;

[0042] Based on the total weight of the mixed solution of the fusel oil and solvent, the concentration of the high-boiling polymer in the mixed solution of the fusel oil and solvent is 2-20% by weight, preferably 3-15% by weight;

[0043] Based on the total weight of the mixed solution of the fusel oil and solvent, the proportions of the first and second portions of the mixed solution of the fusel oil and solvent are each independently 5-95% by weight; preferably, the proportion of the first portion is 50-80% by weight and the proportion of the second portion is 20-50% by weight.

[0044] In this invention, depending on the source of the fusel oil, in addition to the aforementioned common components, the fusel oil may optionally contain trace amounts of non-common components, such as dimethyl oxalate.

[0045] According to the present invention, preferably, when the upper catalyst bed of the fixed-bed alcoholysis reactor reacts to a conversion rate of 20-90% of the high-boiling polymer in the fusel oil, the reacted material is drawn out of the reactor and then mixed with a second stream of the mixed solution of fusel oil and solvent before entering the lower catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction.

[0046] In this invention, when the upper catalyst bed reacts to a conversion rate of 20-90% for high-boiling polymers in the fusel oil, it is then withdrawn from the alcoholysis reactor for heat exchange. This effectively ensures the reaction temperature and improves the effective utilization rate of the catalyst.

[0047] According to the present invention, preferably, the operating conditions of the upper catalyst bed of the fixed-bed alcoholysis reactor include: a reaction temperature of 170–220°C, preferably 180–210°C; a reaction pressure of 0.1–4 MPa, preferably 0.5–4 MPa; and / or a space velocity of 0.5–5 h⁻¹. -1 Preferably 0.5-3h -1 ;

[0048] The operating conditions of the lower catalyst bed in the fixed-bed alcoholysis reactor include: a reaction temperature of 170–220°C, preferably 180–210°C; a reaction pressure of 0.1–4 MPa, preferably 0.5–4 MPa; and / or a space velocity of 0.5–5 h⁻¹. -1 Preferably 0.5-3h -1 .

[0049] According to the present invention, preferably, based on the total weight of the material after reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor, the first portion of the material after reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor accounts for 10-80% by weight, and the remainder is the second portion of the material after reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor.

[0050] Based on the total weight of the second stream of material after reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor, the first stream and the second stream each independently account for 5 to 95% by weight; preferably, the first stream accounts for 20 to 50% by weight and the second stream accounts for 50 to 80% by weight.

[0051] In this invention, 10-80% by weight of the liquid phase is obtained and sent to the subsequent separation system as a reaction product, while the remainder is returned as a liquid phase feedstock for the upper or lower catalyst bed. This improves the effective utilization rate of the catalyst.

[0052] According to the present invention, preferably, both the upper catalyst bed and the lower catalyst bed of the fixed-bed alcoholysis reactor are filled with catalyst.

[0053] In this invention, the catalyst in each bed of the fixed-bed alcoholysis reactor is not limited, and any alcoholysis catalyst can be used.

[0054] Another aspect of the present invention provides a system for fixed-bed alcoholysis of fusel oil, the system comprising:

[0055] A fixed-bed alcoholysis reactor, wherein an upper catalyst bed and a lower catalyst bed are provided inside the fixed-bed alcoholysis reactor;

[0056] The feed line for the mixed solution of fusel oil and solvent is divided into two lines. The first line is connected to the first inlet of the fixed-bed alcoholysis reactor, and the second line is connected to the second inlet of the fixed-bed alcoholysis reactor.

[0057] The outlet of the upper catalyst bed of the fixed-bed alcoholysis reactor is connected to the outlet pipeline of the upper catalyst bed, and the outlet pipeline of the upper catalyst bed is connected to the second path of the feed pipeline of the mixed solution of fusel oil and solvent.

[0058] The outlet of the lower catalyst bed of the fixed-bed alcoholysis reactor is connected to the outlet pipeline of the lower catalyst bed. The outlet pipeline of the lower catalyst bed is divided into two paths. The first path is connected to the downstream separation unit, and the second path is further divided into two branches. The first branch is connected to the first path of the feed pipeline of the mixed solution of fusel oil and solvent, and the second branch is connected to the third inlet of the fixed-bed alcoholysis reactor.

[0059] Preferably, the first feed inlet is located at the upper part of the fixed-bed alcoholysis reactor, and the second and third feed inlets are both located in the middle part of the fixed-bed alcoholysis reactor, with the second and third feed inlets situated between the upper catalyst bed and the lower catalyst bed.

[0060] According to the present invention, preferably, a first heat exchanger is provided on the discharge pipeline of the upper catalyst bed;

[0061] A second heat exchanger is provided on the second branch of the discharge pipeline of the lower catalyst bed, and the second heat exchanger is located upstream of the first branch and the second branch.

[0062] This invention employs an alcoholysis reactor, which can effectively ensure stable reaction conditions, high catalyst utilization, low investment, and small temperature variation in the reaction bed, which is beneficial for improving catalyst selectivity and extending catalyst life.

[0063] The present invention is further illustrated by the following examples:

[0064] The catalysts used in the following examples were prepared by a method including the following steps:

[0065] Weigh 60 parts by mass of titanium oxide (TiO2), 20 parts by mass of tin oxide (SnO2) and 20 parts by mass of molybdenum oxide (MoO3), mix them and grind them in a ball mill for 1 hour to obtain a mixture with an average particle size of 80 μm; dry the ground mixture in a drying oven at 120°C for 8 hours, and then shape it to obtain a round granular catalyst.

[0066] In the following embodiments:

[0067] Conversion rate of high-boiling polymer (%) = (Weight of high-boiling polymer in the mixed solution of fusel oil and solvent - Weight of high-boiling polymer in the reaction product) ÷ Weight of high-boiling polymer in the mixed solution of fusel oil and solvent × 100%.

[0068] Total selectivity % = ((weight of glycolate in reaction product - weight of glycolate in mixed solution of fusel oil and solvent) + (weight of ethylene glycol in reaction product - weight of ethylene glycol in mixed solution of fusel oil and solvent)) ÷ ((weight of high-boiling polymer in mixed solution of fusel oil and solvent - weight of high-boiling polymer in reaction product) + (weight of methanol in mixed solution of fusel oil and solvent - weight of methanol in reaction product)) × 100%.

[0069] The composition of the components was determined using gas chromatography according to the normalization method. The type and content of each component were determined by chromatographic peaks. The specific molecular structures of heavy impurities and high-boiling polymers were difficult to determine. However, their retention times in the chromatograms were fixed, and the content of high-boiling polymers decreased significantly after the reaction, while the content of heavy impurities increased slightly before and after the reaction. This allowed for the determination of the type and content of each component.

[0070] Example 1

[0071] like Figure 1 As shown, this embodiment provides a fixed-bed alcoholysis system for fusel oil. The system includes: a fixed-bed alcoholysis reactor 1, which has an upper catalyst bed and a lower catalyst bed; a feed line for a mixed solution of fusel oil and solvent is divided into two branches, the first branch connected to the first inlet 4 of the fixed-bed alcoholysis reactor 1, and the second branch connected to the second inlet 5 of the fixed-bed alcoholysis reactor 1; the outlet of the upper catalyst bed of the fixed-bed alcoholysis reactor 1 is connected to the outlet line of the upper catalyst bed. The discharge pipeline of the upper catalyst bed is connected to the second branch of the feed pipeline of the mixed solution of fusel oil and solvent; the discharge port 7 of the lower catalyst bed of the fixed bed alcoholysis reactor 1 is connected to the discharge pipeline of the lower catalyst bed, and the discharge pipeline of the lower catalyst bed is divided into two branches. The first branch is connected to the downstream separation unit, and the second branch is further divided into two branches. The first branch is connected to the first branch of the feed pipeline of the mixed solution of fusel oil and solvent, and the second branch is connected to the third inlet 6 of the fixed bed alcoholysis reactor 1.

[0072] The first feed inlet 4 is located at the upper part of the fixed-bed alcoholysis reactor 1, the second feed inlet 5 and the third feed inlet 6 are both located in the middle of the fixed-bed alcoholysis reactor 1, and the second feed inlet 5 and the third feed inlet 6 are both located between the upper catalyst bed and the lower catalyst bed.

[0073] The upper catalyst bed is provided with a first heat exchanger 2 on its discharge pipeline.

[0074] A second heat exchanger 3 is provided on the second branch of the discharge pipeline of the lower catalyst bed, and the second heat exchanger 3 is located upstream of the first branch and the second branch.

[0075] Using the above-described fixed-bed alcoholysis system for fusel oil, this embodiment also provides a method for fixed-bed alcoholysis of fusel oil, the method comprising:

[0076] The solvent 102 for the incoming fusel oil is methanol. Fusel oil 101 at a pH of 3.1, at a rate of 2137 kg / h, is mixed with 3000 kg / h of solvent 102 to obtain a mixed solution of 5137 kg / h. The mixed solution comprises 58.4 wt% methanol, 3.4 wt% methyl glycol, 24.13 wt% ethylene glycol, 1.98 wt% dimethyl oxalate, 1.27 wt% other diols, and 10.82 wt% high-boiling polymer (based on the total weight of the mixed solution of fusel oil and solvent). Based on the total weight of the mixed solution of fusel oil and solvent, the mixed solution is divided into two streams at a 50 wt% to 50 wt% ratio. The first stream enters the upper catalyst bed of the fixed-bed alcoholysis reactor 1 for alcoholysis, and the second stream enters the lower catalyst bed of the fixed-bed alcoholysis reactor 1 for alcoholysis.

[0077] When the upper catalyst bed of the fixed-bed alcoholysis reactor 1 reacts to a conversion rate of 70% for high-boiling polymers in the fusel oil, the reacted material is led out of the reactor, heated to 200°C by a heat exchanger, and then mixed with a second stream of the mixed solution of fusel oil and solvent before entering the lower catalyst bed of the fixed-bed alcoholysis reactor 1 for alcoholysis reaction to generate high-value-added products.

[0078] After the reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor 1, the liquid phase material is divided into two streams. The first stream 103 is discharged as product and sent to the subsequent distillation system for separation. The second stream, after being heated to 200°C, is further divided into two paths. The first path mixes with the first stream of the mixed solution of fusel oil and solvent and then enters the upper catalyst bed of the fixed-bed alcoholysis reactor 1 for alcoholysis. The second path enters the lower catalyst bed of the fixed-bed alcoholysis reactor 1 for alcoholysis. Specifically, based on the total weight of the material after the reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor 1, the first stream accounts for 75% by weight, with the remainder being the second stream. Based on the total weight of the second stream, the first stream accounts for 50% by weight, and the second stream accounts for 50% by weight. The reaction products at the outlet of the lower catalyst bed, based on the total weight of the reaction products, consist of 46.17% by weight of methanol, 15.49% by weight of methyl glycol, 34.63% by weight of ethylene glycol, 1.98% by weight of dimethyl oxalate, 1.37% by weight of other diols, 0.13% by weight of high-boiling polymers, and 0.23% by weight of heavy impurities.

[0079] The operating conditions for the upper catalyst bed include: a reaction temperature of 200℃, a reaction pressure of 2MPa, and a space velocity of 1.5h⁻¹. -1 The operating conditions for the lower catalyst bed include: a reaction temperature of 200℃, a reaction pressure of 2MPa, and a space velocity of 2h⁻¹. -1 .

[0080] Both the upper and lower catalyst beds of the fixed-bed alcoholysis reactor 1 are filled with catalyst.

[0081] After reaction in fixed-bed alcoholysis reactor 1, the total conversion rate of high-boiling polymers was 98.8%, and the total selectivity was 98.6%.

[0082] Example 2

[0083] Using the fixed-bed alcoholysis system of Example 1, this embodiment also provides a method for fixed-bed alcoholysis of fusel oil, the method comprising:

[0084] The solvent 102 for the incoming fusel oil is methanol. Fusel oil 101 at a pH of 3.3, at a rate of 2137 kg / h, and solvent 102 at a rate of 2750 kg / h, are mixed to obtain a mixed solution of 4887 kg / h. The mixed solution comprises 56.27 wt% methanol, 3.55 wt% methyl glycol, 25.37 wt% ethylene glycol, 2.09 wt% dimethyl oxalate, 1.34 wt% other diols, and 11.38 wt% high-boiling polymer (based on the total weight of the mixed solution of fusel oil and solvent). Based on the total weight of the mixed solution of fusel oil and solvent, the mixed solution is divided into two streams at a ratio of 60 wt% and 40 wt%. The first stream (60 wt%) enters the upper catalyst bed of the fixed-bed alcoholysis reactor 1 for alcoholysis, and the second stream (40 wt%) enters the lower catalyst bed of the fixed-bed alcoholysis reactor 1 for alcoholysis.

[0085] When the upper catalyst bed of the fixed-bed alcoholysis reactor 1 reacts to a conversion rate of 67% for high-boiling polymers in the fusel oil, the reacted material is led out of the reactor, heated to 210°C by a heat exchanger, and then mixed with a second stream of the mixed solution of fusel oil and solvent before entering the lower catalyst bed of the fixed-bed alcoholysis reactor 1 for alcoholysis reaction to generate high-value-added products.

[0086] After the reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor 1, the liquid phase material is divided into two streams. The first stream 103 is discharged as product and sent to the subsequent distillation system for separation. The second stream, after being heated to 210°C, is further divided into two paths. The first path mixes with the first stream of the mixed solution of fusel oil and solvent and then enters the upper catalyst bed of the fixed-bed alcoholysis reactor 1 for alcoholysis. The second path enters the lower catalyst bed of the fixed-bed alcoholysis reactor 1 for alcoholysis. Specifically, based on the total weight of the material after the reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor 1, the first stream accounts for 65% by weight, with the remainder being the second stream. Based on the total weight of the second stream, the first stream accounts for 20% by weight, and the second stream accounts for 80% by weight. The reaction products at the outlet of the lower catalyst bed, based on the total weight of the reaction products, consist of 43.41 wt% methanol, 16.28 wt% methyl glycol, 36.4 wt% ethylene glycol, 2.09 wt% dimethyl oxalate, 1.44 wt% other diols, 0.11 wt% high-boiling polymers, and 0.27 wt% heavy impurities.

[0087] The operating conditions for the upper catalyst bed include: a reaction temperature of 210℃, a reaction pressure of 2.5 MPa, and a space velocity of 2.5 h⁻¹. -1 The operating conditions for the lower catalyst bed include: a reaction temperature of 210℃, a reaction pressure of 2.5 MPa, and a space velocity of 2 h⁻¹. -1 .

[0088] Both the upper and lower catalyst beds of the fixed-bed alcoholysis reactor 1 are filled with catalyst.

[0089] After reaction in fixed-bed alcoholysis reactor 1, the total conversion rate of high-boiling polymers was 99.0%, and the total selectivity was 98.5%.

[0090] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for fixed-bed alcoholysis of fusel oil, characterized in that, The method includes: The mixed solution of fusel oil and solvent is divided into two streams. The first stream enters the upper catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction, and the second stream enters the lower catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction. The material after reaction in the upper catalyst bed of the fixed-bed alcoholysis reactor is led out of the reactor and then mixed with a second stream of the mixed solution of fusel oil and solvent before entering the lower catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction. After the reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor, the material is divided into two streams. The first stream is discharged as the product and enters the downstream separation unit. The second stream is further divided into two paths. The first path is mixed with the first stream of the mixed solution of fusel oil and solvent and then enters the upper catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction. The second path enters the lower catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction.

2. The method according to claim 1, wherein, After the material reacts in the upper catalyst bed of the fixed-bed alcoholysis reactor, it is led out of the reactor and heat-exchanged. Then it is mixed with the second stream of the mixed solution of fusel oil and solvent and enters the lower catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction. Preferably, after being heated to 170–220°C, and more preferably to 180–210°C, the mixture is then mixed with a second stream of the mixed solution of fusel oil and solvent before entering the lower catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction.

3. The method according to claim 1, wherein, The second stream of material after reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor is divided into two streams after heat exchange; Preferably, after heat exchange to 170–220°C, and more preferably, after heat exchange to 180–210°C, it is divided into two paths.

4. The method according to claim 1, wherein, The solvent is a saturated monohydric alcohol, preferably a C1-C4 saturated monohydric alcohol, and more preferably methanol; The fusel oil includes: small molecule compounds, high-boiling polymers, and optional heavy impurities; The small molecule compounds include: ethylene glycol, optionally glycolic acid, optionally methyl glycolate, and optionally other diols; The high-boiling polymer is a polymer generated by polymerization of at least one of ethylene glycol, glycolic acid, and methyl glycolate. Preferably, based on the total weight of the fusel oil, the content of the high-boiling polymer is not less than 5 wt%, preferably 10-80 wt%; the content of ethylene glycol is 15-80 wt%, the content of methyl glycolate is 0-30 wt%, the content of glycolic acid is 0-10 wt%, the content of other diols is 0-10 wt%, and the content of heavy impurities is 0-5 wt%. Preferably, the pH value of the fusel oil is 2-6; Based on the total weight of the mixed solution of the fusel oil and solvent, the concentration of the high-boiling polymer in the mixed solution of the fusel oil and solvent is 2-20% by weight, preferably 3-15% by weight; Based on the total weight of the mixed solution of the fusel oil and solvent, the proportions of the first and second portions of the mixed solution of the fusel oil and solvent are each independently 5-95% by weight; preferably, the proportion of the first portion is 50-80% by weight and the proportion of the second portion is 20-50% by weight.

5. The method according to claim 1, wherein, When the upper catalyst bed of the fixed-bed alcoholysis reactor reacts to a conversion rate of 20-90% for high-boiling polymers in the fusel oil, the reacted material is drawn out of the reactor and then mixed with a second stream of the mixed solution of fusel oil and solvent before entering the lower catalyst bed of the fixed-bed alcoholysis reactor for alcoholysis reaction.

6. The method according to claim 1, wherein, The operating conditions of the upper catalyst bed in the fixed-bed alcoholysis reactor include: a reaction temperature of 170–220°C, preferably 180–210°C; a reaction pressure of 0.1–4 MPa, preferably 0.5–4 MPa; and / or a space velocity of 0.5–5 h⁻¹. -1 Preferably 0.5-3h -1 ; The operating conditions of the lower catalyst bed in the fixed-bed alcoholysis reactor include: a reaction temperature of 170–220°C, preferably 180–210°C; a reaction pressure of 0.1–4 MPa, preferably 0.5–4 MPa; and / or a space velocity of 0.5–5 h⁻¹. -1 Preferably 0.5-3h -1 .

7. The method according to claim 1, wherein, Based on the total weight of the material after reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor, the first portion of the material after reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor accounts for 10-80% by weight, and the remainder is the second portion of the material after reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor. Based on the total weight of the second stream of material after reaction in the lower catalyst bed of the fixed-bed alcoholysis reactor, the first stream and the second stream each independently account for 5 to 95% by weight; preferably, the first stream accounts for 20 to 50% by weight and the second stream accounts for 50 to 80% by weight.

8. The method according to claim 1, wherein, Both the upper and lower catalyst beds of the fixed-bed alcoholysis reactor are filled with catalyst.

9. A system for fixed-bed alcoholysis of fusel oil, characterized in that, The system includes: A fixed-bed alcoholysis reactor, wherein an upper catalyst bed and a lower catalyst bed are provided inside the fixed-bed alcoholysis reactor; The feed line for the mixed solution of fusel oil and solvent is divided into two lines. The first line is connected to the first inlet of the fixed-bed alcoholysis reactor, and the second line is connected to the second inlet of the fixed-bed alcoholysis reactor. The outlet of the upper catalyst bed of the fixed-bed alcoholysis reactor is connected to the outlet pipeline of the upper catalyst bed, and the outlet pipeline of the upper catalyst bed is connected to the second path of the feed pipeline of the mixed solution of fusel oil and solvent. The outlet of the lower catalyst bed of the fixed-bed alcoholysis reactor is connected to the outlet pipeline of the lower catalyst bed. The outlet pipeline of the lower catalyst bed is divided into two paths. The first path is connected to the downstream separation unit, and the second path is further divided into two branches. The first branch is connected to the first path of the feed pipeline of the mixed solution of fusel oil and solvent, and the second branch is connected to the third inlet of the fixed-bed alcoholysis reactor. Preferably, the first feed inlet is located at the upper part of the fixed-bed alcoholysis reactor, and the second and third feed inlets are both located in the middle part of the fixed-bed alcoholysis reactor, with the second and third feed inlets situated between the upper catalyst bed and the lower catalyst bed.

10. The system according to claim 9, wherein, A first heat exchanger is installed on the discharge pipeline of the upper catalyst bed. A second heat exchanger is provided on the second branch of the discharge pipeline of the lower catalyst bed, and the second heat exchanger is located upstream of the first branch and the second branch.

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