A semi-continuous apparatus and method for the preparation of 2,5-furan dicarboxylic acid coupled with azeotropic distillation for water removal

Abstract

The application discloses a kind of 2,5-furan dicarboxylic acid semi-continuous preparation device and method coupled with constant boiling rectification water removal.The semi-continuous preparation device is composed of two-stage gap reaction kettle in series, the first stage is 1 gap reaction kettle, and the second stage is composed of 2-5 gap reaction kettles in parallel.The method is as follows: 1) the first stage reaction is started;2) the first stage reaction is continuously operated;3) the second stage reaction is charged;4) the second stage reaction is operated in gap;5) the second stage reaction is operated in turn and alternately;6) after cooling, crystallization and recrystallization, the reaction product is obtained.The application can ensure high substrate concentration (30%) while the raw material can be completely converted, the molar yield of 2,5-furan dicarboxylic acid is greatly improved, which is very suitable for large-scale industrial application and has excellent industrial application prospect.

Description

Technical Field

[0001] The invention belongs to the field of semi-continuous reactions in the chemical industry, and particularly relates to a semi-continuous preparation device and method for 2,5-furandicarboxylic acid coupled with azeotropic distillation for water removal. Background Art

[0002] 2,5-Furandicarboxylic acid (2,5-FDCA, CAS No. 3238-40-2) is a monomer in the biodegradable plastic polyethylene furan dicarboxylate (PEF). It has broad application prospects in pharmaceuticals, fine chemicals, solvents, and other fields. In 2004, it was listed by the U.S. Department of Energy as one of twelve biomass-based platform compounds, and future demand is expected to be enormous. The structural formula of 2,5-FDCA is as follows:

[0003]

[0004] Currently, the mainstream route for preparing 2,5-FDCA is to dehydrate and cyclize glucose / fructose to produce 5-hydroxymethylfurfural (5-HMF), which is then oxidized. Due to the high reactivity, poor stability, and difficulty in isolating 5-HMF, the production cost remains high, severely hindering the industrialization of this route.

[0005] 2,5-FDCA can also be prepared from hexoses by first oxidizing them to hexacarboxylic acid, followed by dehydration and cyclization. Advantages of this route include a shorter process; the starting material can be an aqueous solution of a hexose mixture, requiring less purity; and the intermediate hexacarboxylic acid is very stable and relatively easy to separate. Significant breakthroughs have been made in both chemical and biological methods for the preparation of hexacarboxylic acid, making low-cost production a reality. Therefore, the hexacarboxylic acid route for the preparation of 2,5-FDCA holds a very bright future.

[0006] The reaction formula for preparing 2,5-FDCA by catalytic dehydration cyclization of hexaconic acid and / or hexaconic acid salt is as follows (taking glucaric acid as an example):

[0007]

[0008] From the above reaction formula, it can be seen that 3 moles of water will be produced for every 1 mole of 2,5-FDCA produced. The experimental results show that the enrichment of water has a huge impact on the dehydration cyclization reaction. The increase in water content will greatly reduce the selectivity of the target product 2,5-FDCA, thereby affecting the yield. To this end, the research team of the applicant of this patent applied for a device and method for preparing 2,5-furandicarboxylic acid from hexacarboxylic acid (salt) coupled with dehydration cyclization and azeotropic distillation for dehydration (Lv Xiuyang, Lv Xilei, Zheng Liping, Xu Haifeng, Chen Xujie, Jiang Yuxi, Xu Ling, Li Yanchen. Device and method for preparing 2,5-furandicarboxylic acid from hexacarboxylic acid (salt) coupled with dehydration cyclization and azeotropic distillation for dehydration, ZL 202010215086.5 (authorization date: May 17, 2022)), this method adds an entrainer that can form an azeotrope with water to distill water in time through azeotropic distillation, thereby reducing the occurrence of side reactions, thereby greatly improving the yield of the product 2,5-FDCA; in order to solve the problems of low substrate concentration, low space-time yield and poor product uniformity in the process of preparing 2,5-furandicarboxylic acid by catalytic dehydration and cyclization of hexacarbic acid (salt) using an intermittent reactor, the research group of the applicant of this patent applied for a continuous preparation device and method of 2,5-furandicarboxylic acid coupled with multi-stage series reaction and azeotropic distillation for water removal (Lv Xiuyang, Lv Xilei, Wei Qianwen, Jiang Yu Xi, Ren Aotian. "A continuous preparation apparatus and method for 2,5-furandicarboxylic acid coupled with a multi-stage series reaction and azeotropic distillation for water removal," Application Number: 202310425591.6, Application Date: April 20, 2023). However, during the fully mixed-flow multi-stage series reaction, the residence time of the raw materials is normally distributed, with some raw materials having long residence times and others having short residence times. Raw materials with short residence times cannot be fully converted, resulting in a low overall yield. The higher the required raw material conversion rate, the more series reactor stages are required, but this significantly increases equipment costs and operating expenses. Therefore, increasing the number of series reaction stages to increase the raw material conversion rate is economically unfeasible. Summary of the Invention

[0009] The technical problem to be solved by the present invention is that the residence time of the raw materials in the fully mixed flow multi-stage series reaction is in a normal distribution, and the raw materials cannot be fully converted, resulting in a low yield. The hexaconic acid and / or hexaconic acid salts described in this patent include glucaric acid and its salts, galactaric acid (also known as mucic acid) and its salts, mannocaric acid and its salts, etc. The types of hexaconic acid salts include potassium salt, sodium salt, calcium salt, etc.

[0010] The present invention uses a "1+N" two-stage series reaction technology to achieve semi-continuous preparation of 2,5-furandicarboxylic acid, wherein the first-stage reaction is carried out continuously in one reactor. The second-stage reaction is carried out alternately and intermittently in multiple (N) parallel reactors. A continuous feeding technology is used to feed and react in the first-stage intermittent reactor, so that the actual concentration of the reaction raw materials in the reactor remains low, achieving operation with a high reaction substrate concentration. The generated water is promptly distilled off by coupling with a constant boiling distillation technology, ensuring high reaction selectivity and yield. The "1+N" two-stage series reaction technology achieves a semi-continuous process, solves the problem of the raw materials not being fully converted in fully mixed-flow multi-stage series reactions, and thereby improves the yield of the target product, 2,5-furandicarboxylic acid.

[0011] To achieve the above objectives, the present invention provides a semi-continuous preparation apparatus and method for 2,5-furandicarboxylic acid coupled with azeotropic distillation for water removal. The present invention is achieved through the following technical solutions:

[0012] A semi-continuous preparation device for 2,5-furandicarboxylic acid coupled with azeotropic distillation for water removal comprises two interstitial reactors connected in series, wherein the first stage comprises one interstitial reactor and the second stage comprises multiple interstitial reactors connected in parallel, wherein the number of interstitial reactors connected in parallel is 2-5; each interstitial reactor comprises a dehydration and cyclization reactor, a distillation tower, a condenser, and a phase separator, wherein the dehydration and cyclization reactor is connected to the distillation tower, the top of the distillation tower is connected to a condenser and a phase separator, and the phase separator is connected to the top of the distillation tower.

[0013] Preferably, the number of the second-stage parallel-connected intermittent reactors is 3-4.

[0014] Accordingly, the present invention also provides a method for semi-continuous preparation of 2,5-furandicarboxylic acid by coupling a semi-continuous preparation device with azeotropic distillation for water removal, comprising a first-stage reaction and a second-stage reaction, wherein the first-stage reaction adopts a continuous reaction and the second-stage reaction adopts a parallel, alternating batch reaction. The method comprises the following steps:

[0015] 1) Starting the first stage reaction: turning on the stirring of the reactor and the heating steam of the reactor jacket, sequentially adding the mixed solution of the entrainer, the reaction solvent and the catalyst to the dehydration cyclization reactor, the vapor phase containing water, the entrainer and the reaction solvent and the liquid phase refluxed in the upper layer of the phase separator in the distillation tower to perform vapor-liquid mass transfer, the reaction solvent enters the liquid phase and returns to the reactor, the azeotropic vapor phase formed by the entrainer and water is distilled from the top of the tower and enters the condenser for condensation, the condensate is separated into layers in the phase separator, the upper entrainer layer is refluxed, and the lower water layer is discharged, wherein the temperature of the first stage reaction is 90-110° C., and the mass ratio of the reaction solvent to the catalyst in the mixed solution of the reaction solvent and the catalyst is 20:1-20:3;

[0016] 2) Continuous operation of the first stage reaction: a mixture of hexacaric acid and / or hexacaric acid salt, a reaction solvent, and a catalyst is continuously added to the first stage intermittent reactor, and the mixture flows to the second stage at the same flow rate from the bottom of the reactor, wherein the space time of the first stage reaction is 0.5-2 hours, and the mass flow ratio of hexacaric acid and / or hexacaric acid salt to the mixture of the reaction solvent and the catalyst is 1:10 to 3:10;

[0017] 3) Second stage reaction feeding: Turn on the stirring of the reactor and the steam heating of the reactor jacket, add the entrainer to the dehydration cyclization reactor, and continuously add the bottom effluent of the reactor in step 2) to the reactor to the set reaction volume. The vapor phase containing water, entrainer, and reaction solvent undergoes vapor-liquid mass transfer with the liquid phase refluxed in the upper layer of the phase separator in the distillation tower. The reaction solvent enters the liquid phase and returns to the reactor. The azeotropic vapor phase formed by the entrainer and water is distilled from the top of the tower and condensed in the condenser. The condensate is separated into layers in the phase separator, the upper layer of entrainer is refluxed, and the lower layer of water is discharged;

[0018] 4) Second stage reaction intermittent operation: intermittent reaction at a reaction temperature of 110-140°C for 1.5-7.5 hours, and release the reaction product after the reaction is completed;

[0019] 5) The second stage reaction is operated alternately: after the addition of step 3) is completed, the valve is switched to transfer the bottom effluent of step 2) to the parallel intermittent reactor, and steps 3) and 4) are repeated, and the cycle is repeated in sequence;

[0020] 6) The reaction products discharged from steps 4) and 5) are cooled, crystallized, and recrystallized to obtain 2,5-furandicarboxylic acid product, and the crystallization mother liquor is returned to the first stage reaction after impurities are removed.

[0021] Preferably, the reaction solvent in step 1) is sulfolane, 3-methylsulfolane, 3-sulfolene, dimethyl sulfone, diethyl sulfone, n-butyl sulfone, or methyl phenyl sulfone. The above reaction solvents all contain sulfone compounds, and their structural formulas, melting points, and boiling points are shown below.

[0022]

[0023]

[0024] Preferably, the catalyst in step 1) is sulfuric acid, p-toluenesulfonic acid, methanesulfonic acid, or trifluoromethanesulfonic acid.

[0025] Preferably, the entrainer in step 1) is cyclohexane, benzene, toluene, xylene, or anisole. The azeotropic points and compositions of these entrainers with water are as follows:

[0026] The azeotropic point of cyclohexane and water is 68.95°C, and the azeotropic composition is: 91.6% cyclohexane, 8.4% water.

[0027] The azeotropic point of benzene and water is 69.3℃, and the azeotropic composition is: 91.1% benzene, 8.9% water.

[0028] The azeotropic point of toluene and water is 84.1°C, and the azeotropic composition is: 80.84% ​​toluene, 19.16% water.

[0029] The azeotropic point of xylene and water is 92.0℃, and the azeotropic composition is: xylene 62.5%, water 37.5%.

[0030] The azeotropic point of anisole and water is 95.5°C, and the azeotropic composition is: anisole 59.5%, water 40.5%.

[0031] The space time of the first-stage intermittent reaction in step 2) refers to the ratio of the effective volume of the reactor to the volume flow rate of the feed. Preferably, the space time of the first-stage reaction is 30 min-1.5 h.

[0032] In step 2), the hexaconic acid is one or more of galactaric acid, glucaric acid, and mannoic acid; and the hexaconic acid salt is one or more of monopotassium glucarate, monosodium glucarate, and calcium glucarate.

[0033] Preferably, in step 3), the mass flow ratio of the hexacaric acid and / or hexacarate to the mixed solution of the reaction solvent and the catalyst is 3:20 to 1:4.

[0034] Among them, the volumes of the second-stage parallel reactors are the same, while the volumes of the first-stage and second-stage series reactors can be the same or different; the reaction temperature of the second-stage series reaction is 90-110°C for the first stage and 110-140°C for the second stage.

[0035] Preferably, the time of the intermittent reaction in step 4) is 2.5-6 hours.

[0036] The operating pressure of the distillation tower D is 1 atm, and the theoretical plates are 3 to 10. A packed tower is preferably used. The boiling point difference between the reaction solvent and the azeotrope determines the difficulty of separation. The larger the boiling point difference, the easier the separation is, and the fewer theoretical plates are required. Conversely, the smaller the boiling point difference, the more difficult the separation is, and the more theoretical plates are required.

[0037] Beneficial effects

[0038] Compared with the invention patent previously applied for by the applicant (Lv Xiuyang, Lv Xilei, Wei Qianwen, Jiang Yuxi, Ren Aotian. A continuous preparation device and method of 2,5-furandicarboxylic acid coupled with multi-stage cascade reaction and azeotropic distillation for water removal, application number: 202310425591.6, application date: April 20, 2023), the present invention can achieve a raw material conversion rate of 100% and a product yield of 72.6% under the premise that the substrate concentration can be as high as 30% (i.e., 0.3 kg hexanoic acid (salt) / L catalyst-reaction solvent solution). At the same time, the semi-continuous preparation technology has a higher space-time yield (slightly lower than continuous operation, but much higher than intermittent operation). BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of a semi-continuous preparation device for 2,5-furandicarboxylic acid with a "1+2" ​​two-stage series connection and coupled azeotropic distillation for water removal;

[0040] Figure 2 This is a schematic diagram of a semi-continuous preparation device for 2,5-furandicarboxylic acid with a "1+3" two-stage series connection coupled with azeotropic distillation for water removal;

[0041] Figure 3 This is a schematic diagram of a semi-continuous preparation device for 2,5-furandicarboxylic acid with a "1+4" two-stage series connection coupled with azeotropic distillation for water removal;

[0042] Figure 4 This is a schematic diagram of a semi-continuous preparation device for 2,5-furandicarboxylic acid using a "1+5" two-stage series connection coupled with azeotropic distillation to remove water.

[0043] The first-stage interstitial reactor is labeled as follows: dehydration cyclization reactor R1, distillation tower D1, condenser C1, phase separator S1.

[0044] The second-stage parallel intermittent reactors are marked as follows: dehydration and cyclization reactors R2, R3, R4, R5, R6, distillation towers D2, D3, D4, D5, D6, condensers C2, C3, C4, C5, C6, phase separators S2, S3, S4, S5, S6.

[0045] The switching valves are denoted by reference numerals: three-way switching valve V1 , four-way switching valve V2 , five-way switching valve V3 , and six-way switching valve V4 . DETAILED DESCRIPTION

[0046] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0047] Raw material conversion analysis: The conversion of hexaconic acid (salt) was quantified using an external standard method using HPLC (Agilent 1260, UV detector). Chromatographic conditions were: Agilent Hi-Plex H 300 x 7.7 mm column; mobile phase: 5 mmol / L aqueous sulfuric acid; flow rate: 0.6 mL / min; column temperature: 65°C; injection volume: 20 μL; detection wavelength: 210 nm.

[0048] The calculation formula of the hexacarboxylic acid (salt) conversion rate of the present invention is as follows:

[0049]

[0050] Product Analysis: The reaction product, 2,5-FDCA, was quantified using an external standard HPLC (Agilent 1260, UV detector). Chromatographic conditions included an Agilent Hi-Plex H 300 x 7.7 mm column, a mobile phase of 5 mmol / L aqueous sulfuric acid at a flow rate of 0.6 mL / min, a column temperature of 65°C, an injection volume of 20 μL, and a detection wavelength of 265 nm.

[0051] The yield of 2,5-furandicarboxylic acid of the present invention is a molar yield, and the calculation formula is as follows:

[0052]

[0053] Example 1

[0054] use Figure 1 The "1+2" ​​two-stage cascade system with coupled azeotropic distillation for the semi-continuous production of 2,5-furandicarboxylic acid is shown. The second-stage intermittent reactors are connected in parallel, with two. Each intermittent reactor comprises a dehydration and cyclization reactor, a distillation column, a condenser, and a phase separator. The dehydration and cyclization reactor is connected to the distillation column, the top of which is connected to a condenser and a phase separator, which is then connected to the top of the distillation column. The first-stage intermittent reactors comprise dehydration and cyclization reactor R1, distillation column D1, condenser C1, and phase separator S1. The second-stage intermittent reactors are connected in parallel, comprising dehydration and cyclization reactors R2 and R3, distillation columns D2 and D3, condensers C2 and C3, and phase separators S2 and S3. The first and second intermittent reactors are connected by a three-way switching valve V1, allowing R1 to be switched between R2 and R3.

[0055] The volume of the first-stage dehydration and cyclization reactor R1 is 10L, and the volumes of the two second-stage parallel dehydration and cyclization reactors R2 and R3 are both 30L.

[0056] The experimental steps are as follows:

[0057] 1) Start of the first stage reaction: Start the dehydration cyclization reactor R1 and stir (stirring speed is 300 r / min) and heat the reactor jacket with steam. Add 1 L of entrainer, 5 L of reaction solvent and catalyst mixture to the reactor in sequence. The vapor phase containing water, entrainer and reaction solvent performs vapor-liquid mass transfer with the liquid phase refluxed in the upper layer of phase separator S1 in the distillation tower D1. The reaction solvent enters the liquid phase and returns to the reactor. The azeotropic vapor phase formed by the entrainer and water is distilled from the top of the tower and condensed in the condenser C1. The condensate is separated into layers in the phase separator S1. The upper layer of entrainer is refluxed and the lower layer of water is discharged. The constant boiling distillation and water removal operation is stably operated.

[0058] 2) Continuous operation of the first stage reaction: a mixture of hexacaric acid and / or hexacarate, a reaction solvent, and a catalyst is continuously added to the first stage intermittent reactor, and the mixture flows to the second stage at the same flow rate from the bottom of the reactor, stably operating the first stage continuous reaction;

[0059] 3) Second stage reaction feeding: Turn on the stirring of the second stage dehydration cyclization reactor R2 (stirring speed is 300r / min) and the reactor jacket heating steam, add 3L of entrainer to the reactor, and continuously add the bottom effluent of the reactor in step 2) to the reactor to the set reaction volume. The vapor phase containing water, entrainer, and reaction solvent performs vapor-liquid mass transfer with the liquid phase refluxed on the upper layer of the phase separator in the distillation tower. The reaction solvent enters the liquid phase and returns to the reactor. The azeotropic vapor phase formed by the entrainer and water is distilled from the top of the tower and condensed in the condenser. The condensate is separated into layers in the phase separator, the upper layer of entrainer is refluxed, and the lower layer of water is released. The constant boiling distillation and water removal operation is stably operated;

[0060] 4) Second stage reaction intermittent operation: react at the set reaction temperature for the set time, and release the reaction product after the reaction is completed;

[0061] 5) The second stage reaction is operated alternately: after the addition of step 3) is completed, the valve is switched to transfer the bottom effluent of step 2) to the parallel intermittent reactor R3, and steps 3) and 4) are repeated, and the cycle is repeated in sequence;

[0062] 6) Sampling the reaction products discharged from steps 4) and 5) and performing HPLC analysis and calculation to obtain the conversion rate of the raw material hexaccharic acid (salt) and the molar yield of the product 2,5-FDCA. The reaction products are collected and then cooled, crystallized, and recrystallized to obtain the 2,5-furandicarboxylic acid product. The crystallization mother liquor is returned to the first stage reaction after impurities are removed.

[0063] The experimental results are shown in Table 1 below, wherein the reaction raw material is monopotassium glucarate, the reaction solvent is sulfolane, the catalyst is sulfuric acid, the mass ratio of the reaction solvent to the catalyst is 10:1, and the mass flow rate of the reaction raw material: reaction solvent and catalyst mixture is 2:10.

[0064] Table 1

[0065]

[0066] Example 2

[0067] use Figure 2 The "1+3" two-stage cascade system with coupled azeotropic distillation for the semi-continuous production of 2,5-furandicarboxylic acid is shown. The second-stage intermittent reactors are connected in parallel to three reactors. Each reactor comprises a dehydration and cyclization reactor, a distillation column, a condenser, and a phase separator. The dehydration and cyclization reactor is connected to the distillation column, the top of which is connected to a condenser and a phase separator, which is then connected to the top of the distillation column. The first-stage intermittent reactors comprise dehydration and cyclization reactor R1, distillation column D1, condenser C1, and phase separator S1. The second-stage intermittent reactors are connected in parallel to dehydration and cyclization reactors R2, R3, and R4, distillation columns D2, D3, and D4, condensers C2, C3, and C4, and phase separators S2, S3, and S4. The first and second intermittent reactors are connected by a four-way switching valve V2, allowing R1 to be connected and switched to R2, R3, and R4, respectively.

[0068] The volume of the first-stage dehydration and cyclization reactor R1 is 10L, and the volumes of the three second-stage parallel dehydration and cyclization reactors R2, R3 and R4 are all 20L.

[0069] The experimental steps are as follows:

[0070] 1) Start of the first stage reaction: Start the dehydration cyclization reactor R1 and stir (stirring speed is 300 r / min) and heat the reactor jacket with steam. Add 1 L of entrainer, 5 L of reaction solvent and catalyst mixture to the reactor in sequence. The vapor phase containing water, entrainer and reaction solvent performs vapor-liquid mass transfer with the liquid phase refluxed in the upper layer of phase separator S1 in the distillation tower D1. The reaction solvent enters the liquid phase and returns to the reactor. The azeotropic vapor phase formed by the entrainer and water is distilled from the top of the tower and condensed in the condenser C1. The condensate is separated into layers in the phase separator S1. The upper layer of entrainer is refluxed and the lower layer of water is discharged. The constant boiling distillation and water removal operation is stably operated.

[0071] 2) Continuous operation of the first stage reaction: a mixture of hexacaric acid and / or hexacarate, a reaction solvent, and a catalyst is continuously added to the first stage intermittent reactor, and the mixture flows to the second stage at the same flow rate from the bottom of the reactor, stably operating the first stage continuous reaction;

[0072] 3) Second stage reaction feeding: Turn on the stirring of the second stage dehydration cyclization reactor R2 (stirring speed is 300r / min) and the reactor jacket heating steam, add 2L of entrainer to the reactor, and continuously add the bottom effluent of the reactor in step 2) to the reactor to the set reaction volume. The vapor phase containing water, entrainer, and reaction solvent performs vapor-liquid mass transfer with the liquid phase refluxed on the upper layer of the phase separator in the distillation tower. The reaction solvent enters the liquid phase and returns to the reactor. The azeotropic vapor phase formed by the entrainer and water is distilled from the top of the tower and enters the condenser for condensation. The condensate is separated into layers in the phase separator, the upper layer of entrainer is refluxed, and the lower layer of water is released. The constant boiling distillation and water removal operation is stably operated;

[0073] 4) Second stage reaction intermittent operation: react at the set reaction temperature for the set time, and release the reaction product after the reaction is completed;

[0074] 5) The second stage reaction is operated alternately: after the addition of step 3) is completed, the valve is switched to switch the bottom effluent of step 2) to the parallel gap reactor R3, and steps 3) and 4) are repeated, and then the valve is switched to the dehydration cyclization reactor R4, and steps 3) and 4) are repeated, and the cycle is repeated in sequence;

[0075] 6) Sampling the reaction products discharged from steps 4) and 5) and performing HPLC analysis and calculation to obtain the conversion rate of the raw material hexaccharic acid (salt) and the molar yield of the product 2,5-FDCA. The reaction products are collected and then cooled, crystallized, and recrystallized to obtain the 2,5-furandicarboxylic acid product. The crystallization mother liquor is returned to the first stage reaction after impurities are removed.

[0076] The experimental results are shown in Table 2 below, where the reaction raw material is monopotassium glucarate, the entrainer is toluene, the mass ratio of the reaction solvent to the catalyst is 10:1, and the mass flow rate of the reaction raw material: reaction solvent and catalyst mixture is 2:10.

[0077] Table 2

[0078]

[0079]

[0080] Example 3

[0081] use Figure 2The "1+3" two-stage cascade system with coupled azeotropic distillation for the semi-continuous production of 2,5-furandicarboxylic acid is shown. The second-stage intermittent reactors are connected in parallel to three reactors. Each reactor comprises a dehydration and cyclization reactor, a distillation column, a condenser, and a phase separator. The dehydration and cyclization reactor is connected to the distillation column, the top of which is connected to a condenser and a phase separator, which is then connected to the top of the distillation column. The first-stage intermittent reactors comprise dehydration and cyclization reactor R1, distillation column D1, condenser C1, and phase separator S1. The second-stage intermittent reactors are connected in parallel to dehydration and cyclization reactors R2, R3, and R4, distillation columns D2, D3, and D4, condensers C2, C3, and C4, and phase separators S2, S3, and S4. The first and second intermittent reactors are connected by a four-way switching valve V2, allowing R1 to be connected and switched to R2, R3, and R4, respectively.

[0082] The volume of the first-stage dehydration and cyclization reactor R1 is 10L, and the volumes of the three second-stage parallel dehydration and cyclization reactors R2, R3 and R4 are all 20L.

[0083] The experimental steps are as follows:

[0084] 1) Start of the first stage reaction: Start the dehydration cyclization reactor R1 and stir (stirring speed is 300 r / min) and heat the reactor jacket with steam. Add 1 L of entrainer, 5 L of reaction solvent and catalyst mixture to the reactor in sequence. The vapor phase containing water, entrainer and reaction solvent performs vapor-liquid mass transfer with the liquid phase refluxed in the upper layer of phase separator S1 in the distillation tower D1. The reaction solvent enters the liquid phase and returns to the reactor. The azeotropic vapor phase formed by the entrainer and water is distilled from the top of the tower and condensed in the condenser C1. The condensate is separated into layers in the phase separator S1. The upper layer of entrainer is refluxed and the lower layer of water is discharged. The constant boiling distillation and water removal operation is stably operated.

[0085] 2) Continuous operation of the first stage reaction: a mixture of hexacaric acid and / or hexacarate, a reaction solvent, and a catalyst is continuously added to the first stage intermittent reactor, and the mixture flows to the second stage at the same flow rate from the bottom of the reactor, stably operating the first stage continuous reaction;

[0086] 3) Second stage reaction feeding: Turn on the stirring of the second stage dehydration cyclization reactor R2 (stirring speed is 300r / min) and the reactor jacket heating steam, add 2L of entrainer to the reactor, and continuously add the bottom effluent of the reactor in step 2) to the reactor to the set reaction volume. The vapor phase containing water, entrainer, and reaction solvent performs vapor-liquid mass transfer with the liquid phase refluxed on the upper layer of the phase separator in the distillation tower. The reaction solvent enters the liquid phase and returns to the reactor. The azeotropic vapor phase formed by the entrainer and water is distilled from the top of the tower and enters the condenser for condensation. The condensate is separated into layers in the phase separator, the upper layer of entrainer is refluxed, and the lower layer of water is released. The constant boiling distillation and water removal operation is stably operated;

[0087] 4) Second stage reaction intermittent operation: react at the set reaction temperature for the set time, and release the reaction product after the reaction is completed;

[0088] 5) The second stage reaction is operated alternately: after the addition of step 3) is completed, the valve is switched to switch the bottom effluent of step 2) to the parallel gap reactor R3, and steps 3) and 4) are repeated, and then the valve is switched to the dehydration cyclization reactor R4, and steps 3) and 4) are repeated, and the cycle is repeated in sequence;

[0089] 6) Sampling the reaction products discharged from steps 4) and 5) and performing HPLC analysis and calculation to obtain the conversion rate of the raw material hexaccharic acid (salt) and the molar yield of the product 2,5-FDCA. The reaction products are collected and then cooled, crystallized, and recrystallized to obtain the 2,5-furandicarboxylic acid product. The crystallization mother liquor is returned to the first stage reaction after impurities are removed.

[0090] The experimental results are shown in Table 3 below, wherein the reaction raw material is monopotassium glucarate, the reaction solvent is sulfolane, the catalyst is sulfuric acid, the entrainer is toluene, the mass ratio of the reaction solvent to the catalyst is 10:1, and the mass flow rate of the reaction raw material: the reaction solvent and the catalyst mixture is 2:10.

[0091] Table 3

[0092]

[0093] Example 4

[0094] use Figure 3 The "1+4" two-stage, series-connected, semi-continuous production apparatus for 2,5-furandicarboxylic acid, coupled with azeotropic distillation for water removal, features four parallel batch reactors in the second stage. Each batch reactor comprises a dehydration and cyclization reactor, a distillation column, a condenser, and a phase separator. The dehydration and cyclization reactor is connected to the distillation column, the top of which is connected to a condenser and a phase separator, which is then connected to the top of the distillation column. The first-stage batch reactors comprise dehydration and cyclization reactor R1, distillation column D1, condenser C1, and phase separator S1. The second-stage batch reactors comprise dehydration and cyclization reactors R2, R3, R4, and R5, distillation columns D2, D3, D4, and D5, condensers C2, C3, C4, and C5, and phase separators S2, S3, S4, and S5. The first and second batch reactors are connected via a five-way switching valve V3, allowing R1 to be connected and switched to R2, R3, R4, and R5, respectively.

[0095] The volume of the first-stage dehydration and cyclization reactor R1 is 10L, and the volumes of the four second-stage parallel dehydration and cyclization reactors R2, R3, R4 and R5 are all 15L.

[0096] The experimental steps are as follows:

[0097] 1) Start of the first stage reaction: Start the dehydration cyclization reactor R1 and stir (stirring speed is 300 r / min) and heat the reactor jacket with steam. Add 1 L of entrainer, 5 L of reaction solvent and catalyst mixture to the reactor in sequence. The vapor phase containing water, entrainer and reaction solvent performs vapor-liquid mass transfer with the liquid phase refluxed in the upper layer of phase separator S1 in the distillation tower D1. The reaction solvent enters the liquid phase and returns to the reactor. The azeotropic vapor phase formed by the entrainer and water is distilled from the top of the tower and condensed in the condenser C1. The condensate is separated into layers in the phase separator S1. The upper layer of entrainer is refluxed and the lower layer of water is discharged. The constant boiling distillation and water removal operation is stably operated.

[0098] 2) Continuous operation of the first stage reaction: a mixture of hexacaric acid and / or hexacarate, a reaction solvent, and a catalyst is continuously added to the first stage intermittent reactor, and the mixture flows to the second stage at the same flow rate from the bottom of the reactor, stably operating the first stage continuous reaction;

[0099] 3) Second stage reaction feeding: Turn on the stirring of the second stage dehydration cyclization reactor R2 (stirring speed is 300r / min) and the reactor jacket heating steam, add 1.5L of entrainer to the reactor, and continuously add the bottom effluent of the reactor in step 2) to the reactor to the set reaction volume. The vapor phase containing water, entrainer, and reaction solvent performs vapor-liquid mass transfer with the liquid phase refluxed on the upper layer of the phase separator in the distillation tower. The reaction solvent enters the liquid phase and returns to the reactor. The azeotropic vapor phase formed by the entrainer and water is distilled from the top of the tower and enters the condenser for condensation. The condensate is separated into layers in the phase separator, the upper layer of entrainer is refluxed, and the lower layer of water is released. The constant boiling distillation and water removal operation is stably operated;

[0100] 4) Second stage reaction intermittent operation: react at the set reaction temperature for the set time, and release the reaction product after the reaction is completed;

[0101] 5) The second stage reaction is operated alternately: after the addition of step 3) is completed, the valve is switched to switch the bottom effluent of step 2) to the parallel gap reactor R3, and steps 3) and 4) are repeated, and then the effluent is switched to the dehydration cyclization reactor R4, and steps 3) and 4) are repeated, and then the effluent is switched to R5, and steps 3) and 4) are repeated, and the cycle is repeated in sequence;

[0102] 6) Sampling the reaction products discharged from steps 4) and 5) and performing HPLC analysis and calculation to obtain the conversion rate of the raw material hexaccharic acid (salt) and the molar yield of the product 2,5-FDCA. The reaction products are collected and then cooled, crystallized, and recrystallized to obtain the 2,5-furandicarboxylic acid product. The crystallization mother liquor is returned to the first stage reaction after impurities are removed.

[0103] The experimental results are shown in Table 4 below, wherein the reaction raw material is monopotassium glucarate, the reaction solvent is sulfolane, the catalyst is sulfuric acid, and the entrainer is toluene.

[0104] Table 4

[0105]

[0106]

[0107] Example 5

[0108] use Figure 4 The "1+5" two-stage cascade system with coupled azeotropic distillation for the semi-continuous production of 2,5-furandicarboxylic acid features five parallel batch reactors in the second stage. Each batch reactor comprises a dehydration and cyclization reactor, a distillation column, a condenser, and a phase separator. The dehydration and cyclization reactor is connected to the distillation column, the top of which is connected to a condenser and a phase separator, which is then connected to the top of the distillation column. The first-stage batch reactors comprise dehydration and cyclization reactor R1, distillation column D1, condenser C1, and phase separator S1. The second-stage batch reactors comprise dehydration and cyclization reactors R2, R3, R4, R5, and R6; distillation columns D2, D3, D4, D5, and D6; condensers C2, C3, C4, C5, and C6; and phase separators S2, S3, S4, S5, and S6. The first-stage gap reactor and the second-stage gap reactor are connected through a six-way switching valve V4, and R1 can be connected and switched with R2, R3, R4, R5, and R6 respectively.

[0109] The volume of the first-stage dehydration and cyclization reactor R1 is 10L, and the volumes of the five second-stage parallel dehydration and cyclization reactors R2, R3, R4, R5 and R6 are also 10L.

[0110] The experimental steps are as follows:

[0111] 1) Start of the first stage reaction: Start the dehydration cyclization reactor R1 and stir (stirring speed is 300 r / min) and heat the reactor jacket with steam. Add 1 L of entrainer, 5 L of reaction solvent and catalyst mixture to the reactor in sequence. The vapor phase containing water, entrainer and reaction solvent performs vapor-liquid mass transfer with the liquid phase refluxed in the upper layer of phase separator S1 in the distillation tower D1. The reaction solvent enters the liquid phase and returns to the reactor. The azeotropic vapor phase formed by the entrainer and water is distilled from the top of the tower and condensed in the condenser C1. The condensate is separated into layers in the phase separator S1. The upper layer of entrainer is refluxed and the lower layer of water is discharged. The constant boiling distillation and water removal operation is stably operated.

[0112] 2) Continuous operation of the first stage reaction: a mixture of hexacaric acid and / or hexacarate, a reaction solvent, and a catalyst is continuously added to the first stage intermittent reactor, and the mixture flows to the second stage at the same flow rate from the bottom of the reactor, stably operating the first stage continuous reaction;

[0113] 3) Second stage reaction feeding: Turn on the stirring of the second stage dehydration cyclization reactor R2 (stirring speed is 300r / min) and the reactor jacket heating steam, add 1L of entrainer to the reactor, and continuously add the bottom effluent of the reactor in step 2) to the reactor to the set reaction volume. The vapor phase containing water, entrainer, and reaction solvent performs vapor-liquid mass transfer with the liquid phase refluxed on the upper layer of the phase separator in the distillation tower. The reaction solvent enters the liquid phase and returns to the reactor. The azeotropic vapor phase formed by the entrainer and water is distilled from the top of the tower and condensed in the condenser. The condensate is separated into layers in the phase separator, the upper layer of entrainer is refluxed, and the lower layer of water is released. The constant boiling distillation and water removal operation is stably operated;

[0114] 4) Second stage reaction intermittent operation: react at the set reaction temperature for the set time, and release the reaction product after the reaction is completed;

[0115] 5) The second stage reaction is operated alternately: after the addition of step 3) is completed, the valve is switched to switch the bottom effluent in step 2) to the parallel gap reactor R3, repeating steps 3) and 4), then switching to the dehydration cyclization reactor R4, repeating steps 3) and 4), then switching to the dehydration cyclization reactor R5, repeating steps 3) and 4), then switching to the dehydration cyclization reactor R6, repeating steps 3) and 4), and repeating the cycle in sequence;

[0116] 6) Sampling the reaction products discharged from steps 4) and 5) and performing HPLC analysis and calculation to obtain the conversion rate of the raw material hexaccharic acid (salt) and the molar yield of the product 2,5-FDCA. The reaction products are collected and then cooled, crystallized, and recrystallized to obtain the 2,5-furandicarboxylic acid product. The crystallization mother liquor is returned to the first stage reaction after impurities are removed.

[0117] The experimental results are shown in Table 5 below, wherein the reaction solvent is sulfolane, the catalyst is sulfuric acid, the entrainer is toluene, the mass ratio of the reaction solvent to the catalyst is 10:1, and the mass flow rate of the reaction raw material: the reaction solvent and catalyst mixture is 2:10.

[0118] Table 5

[0119]

[0120] It can be seen from the above embodiments and experimental data that: while ensuring a high substrate concentration, the conversion rate of the raw material hexacarboxylic acid and / or hexacarate salt of the scheme described in the present invention can reach 100%, and the molar yield of the target product 2,5-furandicarboxylic acid is increased to 72.6%, which is significantly improved compared with the maximum yield of 65.2% of the invention patent previously applied for by the applicant (Lv Xiuyang, Lv Xilei, Wei Qianwen, Jiang Yuxi, Ren Aotian. A continuous preparation device and method of 2,5-furandicarboxylic acid coupled with multi-stage cascade reaction and azeotropic distillation and water removal, application number: 202310425591.6, application date: April 20, 2023).

[0121] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the description of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A semi-continuous preparation device for 2,5-furandicarboxylic acid coupled with azeotropic distillation for water removal, characterized in that: The semi-continuous preparation device is composed of two-stage interstitial reactors connected in series, the first stage is one interstitial reactor, and the second stage is composed of multiple interstitial reactors connected in parallel. Each interstitial reactor includes a dehydration and cyclization reactor, a distillation tower, a condenser and a phase separator, wherein the dehydration and cyclization reactor is connected to the distillation tower, the top of the distillation tower is connected to the condenser and the phase separator in sequence, and the phase separator is then connected to the top of the distillation tower.

2. The semi-continuous preparation device according to claim 1, characterized in that: The number of the second-stage parallel intermittent reactors is 2-5.

3. A method for semi-continuous preparation of 2,5-furandicarboxylic acid using the semi-continuous preparation device coupled with azeotropic distillation for water removal as described in any one of claims 1-2, characterized in that: The first-stage reaction adopts a continuous reaction, and the second-stage reaction adopts a parallel, alternating intermittent reaction. The method comprises the following steps: Step 1, starting the first-stage reaction: turning on the stirring and jacket heating steam of the first-stage dehydration cyclization reactor, sequentially adding a mixture of an entrainer, a reaction solvent, and a catalyst into the reactor, wherein the vapor phase containing water, the reaction solvent, and the entrainer performs vapor-liquid mass transfer with the liquid phase refluxed in the upper layer of the phase separator in the distillation tower, wherein the reaction solvent enters the liquid phase and returns to the reactor, the azeotropic vapor phase formed by water and the entrainer is distilled from the top of the distillation tower and enters the condenser for condensation, the resulting condensate enters the phase separator for stratification, the upper layer of entrainer is refluxed into the distillation tower, and the lower layer of water is discharged; wherein the temperature of the first-stage reaction is 90-110° C., and the mass ratio of the reaction solvent to the catalyst in the mixture of the reaction solvent and the catalyst is 20:1-20:3; Step 2, continuous operation of the first-stage reaction: a mixture of a reaction solvent and a catalyst, hexacaric acid and / or a hexacaric acid salt are continuously added to the first-stage intermittent reactor, and the mixture flows from the bottom of the reactor to the second-stage intermittent reactor at the same flow rate; wherein the space time of the first-stage reaction is 0.5-2 hours, and the mass flow rate ratio of hexacaric acid and / or a hexacaric acid salt to the mixture of the reaction solvent and the catalyst is 1:10-3:10; Step 3, second-stage reaction feeding: turn on the stirring and jacket heating steam of the second-stage dehydration and cyclization reactor, add the entrainer to the reactor, and continuously add the bottom effluent of the reactor in step 2 to the reactor to the set reaction volume. The vapor phase containing water, reaction solvent, and entrainer performs vapor-liquid mass transfer with the liquid phase refluxed on the upper layer of the phase separator in the distillation tower, wherein the reaction solvent enters the liquid phase and returns to the reactor, and the azeotropic vapor phase formed by water and entrainer is distilled from the top of the distillation tower and enters the condenser for condensation. The resulting condensate enters the phase separator for stratification, and the upper layer of entrainer is refluxed into the distillation tower, and the lower layer of water is discharged; Step 4: Second stage reaction intermittent operation: intermittent reaction at a reaction temperature of 110-140°C for 1.5-7.5 hours, and release the reaction product after the reaction is completed; Step 5, alternating operation of the second stage reaction: after the addition of step 3 is completed, the valve is switched to switch the bottom effluent of step 2 to the second stage parallel gap reactor, and steps 3 and 4 are repeated, and the cycle is repeated in sequence; The reaction products discharged from step 6, step 4 and step 5 are cooled, crystallized and recrystallized in sequence to obtain 2,5-furandicarboxylic acid product. The obtained crystallization mother liquor is returned to the first stage reaction after impurities are removed.

4. The semi-continuous preparation method according to claim 3, wherein: In step 1, the entrainer is toluene, cyclohexane, xylene, benzene, or anisole.

5. The semi-continuous preparation method according to claim 3, wherein: In step 1, the reaction solvent is 3-methylsulfolane, diethyl sulfone, 3-sulfolene, n-butyl sulfone, sulfolane, dimethyl sulfone, or methyl phenyl sulfone.

6. The semi-continuous preparation method according to claim 3, wherein: In step 1, the catalyst is methanesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, or sulfuric acid.

7. The semi-continuous preparation method according to claim 3, wherein: In step 2, the hexaconic acid is one or a combination of mannocaric acid, glucaric acid and galactaric acid; the hexaconic acid salt is one or a combination of glucaric acid calcium salt, glucaric acid monosodium salt and glucaric acid monopotassium salt.

8. The semi-continuous preparation method according to claim 3, wherein: In step 2, the mass flow ratio of the hexacaric acid and / or hexacarate to the mixed solution of the reaction solvent and the catalyst is 3:20 to 1:

4.

9. The semi-continuous preparation method according to claim 3, wherein In step 4, the intermittent reaction time is 2.5-6 h.

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