A method for continuous decolorization and concentration of 5-hydroxymethylfurfural

Abstract

The present application relates to a kind of 5-hydroxymethylfurfural continuous decolorization and concentration method.The method comprises the following steps: S1, the crude solution containing HMF is introduced into nanofiltration membrane decolorization device to carry out decolorization separation, and HMF permeate after decolorization and HMF residual liquid enriched impurities are obtained respectively;S2, the HMF permeate is pumped into nanofiltration membrane concentration device to carry out concentration separation, and HMF thick phase and HMF light phase are obtained respectively, and HMF thick phase is collected as HMF product;S3, HMF light phase and / or make-up water are added to the HMF residual liquid and mixed uniformly, then return to the crude solution of HMF to circulate, collect HMF thick phase as HMF product, monitor the HMF content in HMF residual liquid, and when it is lower than the set threshold, discharge HMF residual liquid.The method solves the problem of concentration reduction caused by membrane decolorization process, and the light phase in membrane concentration process is used, which further increases the yield of product and reduces water consumption.

Description

Technical Field

[0001] This invention relates to the field of compound separation, purification and material recovery technology, specifically to a method for continuous decolorization and concentration of 5-hydroxymethylfurfural. Background Technology

[0002] 5-Hydroxymethylfurfural (HMF) is a core furan platform molecule connecting biomass resources and petrochemical systems. It can be produced from hexoses such as glucose and fructose through dehydration reactions. Through oxidation, hydrogenation, and amination reaction pathways, it can derive dozens of high-value-added chemicals such as 2,5-furandicarboxylic acid and 2,5-dimethylfuran, possessing irreplaceable industrial value in fields such as bio-based polyesters, environmental solvents, and pharmaceutical intermediates. However, hexoses are prone to polymerization and Maillard side reactions during isomerization and dehydration, generating 5,5'-oxobis(methylene)bis-2-furfural and humic macromolecular colored impurities. This results in crude HMF solutions with deep color (platinum-cobalt color is usually greater than 200 degrees) and low purity. Furthermore, the pigments can be transferred to downstream reaction end products such as FDCA and PEF, severely restricting the industrial application of HMF in high-end materials.

[0003] Currently, the mainstream decolorization methods in the industry are activated carbon adsorption and ion exchange resin methods. Activated carbon decolorization is inexpensive, but its adsorption selectivity is poor, and it will simultaneously adsorb a large amount of HMF, resulting in a decrease in product yield. In addition, powdered activated carbon requires a set of precision filtration equipment, which increases investment costs and solid waste treatment pressure. Although resin decolorization can be repeatedly regenerated, the regeneration process generates a large amount of waste liquid, and there is also product adsorption loss, making it difficult to adapt to the needs of large-scale continuous production.

[0004] Membrane separation technology offers a new solution for HMF purification. Chinese invention patent CN114805255B discloses a method for the preparation and membrane separation purification of 5-hydroxymethylfurfural, utilizing nanofiltration membranes to remove impurities by retaining humic substances. However, this process only has a single-step decolorization function; the concentration of the membrane permeate decreases after dilution, making it impossible to directly obtain a high-concentration product. Furthermore, the recovery of residual HMF in the residual liquid is insufficient, and the overall process is intermittent, with separate decolorization and concentration steps, resulting in a long process flow, high energy consumption, and difficulty in achieving continuous and stable production. Therefore, developing an HMF purification process that integrates highly selective decolorization, continuous operation, high product yield, and adjustable concentration has significant industrial application value. Summary of the Invention

[0005] The first aspect of this invention provides a continuous decolorization and concentration method for 5-hydroxymethylfurfural, comprising the following steps: S1, the crude solution containing HMF is passed into a nanofiltration membrane decolorization device for decolorization and separation, and the decolorized HMF permeate and the HMF residue enriched with impurities are obtained respectively. S2, the HMF permeate is pumped into a nanofiltration membrane concentration device for concentration and separation to obtain a concentrated HMF phase and a dilute HMF phase, and the concentrated HMF phase is collected as the HMF product. S3, add the dilute HMF phase and / or make-up water to the HMF residue and mix well. Then, return the mixture to the crude HMF solution for circulation. Repeat steps S1 and S2. Monitor the HMF content in the HMF residue. If it is lower than the set threshold, discharge the HMF residue.

[0006] In existing single-step nanofiltration decolorization processes, to improve HMF recovery, the decolorization residue needs to be diluted with water and then recycled for further decolorization. This continuously dilutes the product concentration in the permeate, resulting in a low HMF content in the final decolorized solution, which cannot directly meet the downstream high-concentration feed requirements. Furthermore, the large amount of water replenishment increases the wastewater treatment load. This application addresses this issue by using a nanofiltration membrane based on the coupling mechanism of molecular weight sieving and solvent retention. First, a decolorizing nanofiltration membrane selectively retains large-molecule colored impurities, allowing small-molecule HMF to permeate with the solvent, forming a low-color permeate. Then, the decolorized permeate is passed through a high-desalination-rate concentrating nanofiltration membrane. Under high pressure, HMF molecules are retained while water molecules permeate, achieving efficient enrichment and concentration of the product, directly obtaining the target concentration of concentrated HMF. Simultaneously, the dilute phase containing trace amounts of HMF generated during the concentration process is reused for dilution of the decolorization residue. This recovers residual product from the dilute phase to improve the overall yield and replaces fresh water replenishment, reducing system water consumption and wastewater output, forming a continuous closed-loop process with synergistic decolorization and concentration.

[0007] The crude solution is prepared by isomerization or dehydration of a hexose.

[0008] The crude solution contains 2-15% HMF by mass and 50-5000 ppm 5,5'-oxobis(methylene)bis-2-furfural.

[0009] The crude solution has a platinum-cobalt colorimetric value (GB / T 3143-1982) greater than 200 degrees.

[0010] The HMF product contains ≥5% HMF by mass.

[0011] Optionally, the HMF product contains ≥8% HMF by mass.

[0012] The platinum-cobalt colorimetric value of the HMF product is less than 50 degrees.

[0013] Optionally, the platinum-cobalt colorimetric value of the HMF product is less than 35 degrees.

[0014] The yield of the HMF product is >95%.

[0015] The nanofiltration membrane decolorization device uses a spiral wound nanofiltration membrane module, wherein the membrane separation layer is composed of polyamide polymerized from aromatic amines and heterocyclic aliphatic amines. The nanofiltration membrane decolorization device can retain impurities with a molecular weight ≥200 Da.

[0016] The nanofiltration membrane concentration device uses a spiral wound nanofiltration membrane module, wherein the membrane separation layer is composed of fully aromatic cross-linked polyamide, and the desalination rate of the nanofiltration membrane concentration device is >98%.

[0017] The operating parameters of the nanofiltration membrane decolorization device include: operating pressure of 0.3~2.5MPa and feed temperature of crude solution of 10~50℃.

[0018] Optionally, the operating parameters of the nanofiltration membrane decolorization device include: operating pressure of 0.3~1.0MPa and feed temperature of crude solution of 15~30℃.

[0019] The operating parameters of the nanofiltration membrane concentration device include: operating pressure of 1.5~5.0MPa and feed solution temperature of 10~50℃.

[0020] Optionally, the operating parameters of the nanofiltration membrane concentration device include: operating pressure of 2.0~4.0MPa and feed solution temperature of 15~30℃.

[0021] The set threshold is that the mass percentage of 5-hydroxymethylfurfural in the HMF residue is less than 0.25 wt%.

[0022] Optionally, the set threshold is that the mass percentage of 5-hydroxymethylfurfural in the HMF residue is less than 0.2%.

[0023] Beneficial effects 1. This invention combines the decolorization and concentration processes to solve the problem of concentration reduction caused by membrane decolorization. At the same time, the light phase in the membrane concentration process is reused, which further increases the product yield and reduces water consumption.

[0024] 2. This invention uses a spiral wound nanofiltration decolorization membrane capable of retaining impurities with a molecular weight ≥200 Da. Compared with activated carbon and resin adsorption decolorization, it avoids product loss due to entrainment by the adsorbent and eliminates the need for subsequent filtration and separation processes.

[0025] 3. The present invention sets up a nanofiltration membrane decolorization device and a nanofiltration membrane concentration device in series, which significantly increases the throughput per unit time compared with the intermittent decolorization process.

[0026] 4. By adjusting the operating parameters of the nanofiltration membrane concentration device, this invention can prepare HMF concentrated phase products of different concentrations, adapting to the feeding requirements of different application scenarios.

[0027] 5. This invention adopts the physical sieving principle of membrane separation throughout the process, without adding solid adsorbents such as activated carbon and resin, and without generating solid waste such as waste adsorbents. Attached Figure Description

[0028] Figure 1 This is a process flow diagram for Example 1.

[0029] Figure 2 This is a process flow diagram for Example 2. Detailed Implementation

[0030] Example 1 A continuous decolorization and concentration method for 5-hydroxymethylfurfural comprises the following steps: like Figure 1 As shown in the process flow diagram, 30 kg of crude HMF solution with a content of 2 wt% was taken. The crude solution contained 4000 ppm of 5,5'-oxobis(methylene)bis-2-furfural and had a platinum-cobalt color value greater than 200 degrees. It was first passed through a nanofiltration membrane decolorization device (molecular weight cutoff of 200 Da; using a spiral wound nanofiltration membrane module; the membrane separation layer was composed of polyamide polymerized from m-phenylenediamine and piperazine). The operating pressure of the membrane decolorization device was 0.3 MPa, and the feed temperature was 25°C. After membrane decolorization, HMF permeate and HMF were obtained. The residual HMF solution was then pumped into a nanofiltration membrane concentration unit (using a spiral wound nanofiltration membrane module; the membrane separation layer is composed of polyamide polymerized with m-phenylenediamine; desalination rate > 98%) for concentration. The membrane concentration unit operated at a pressure of 3.2 MPa and a feed temperature of 30°C, yielding 6.8 kg of concentrated HMF and diluted HMF. The diluted HMF was added to the residual HMF solution, mixed, and then returned to the crude HMF solution for further nanofiltration decolorization. When the HMF content in the residual HMF solution was below 0.2%, the residual HMF solution could be discharged from the nanofiltration system.

[0031] Example 2 A continuous decolorization and concentration method for 5-hydroxymethylfurfural comprises the following steps: like Figure 2As shown in the process flow diagram, 30 kg of crude HMF solution with a content of 15 wt% was taken. The crude solution contained 100 ppm of 5,5'-oxobis(methylene)bis-2-furfural and had a platinum-cobalt color value greater than 200 degrees. It was first passed through a nanofiltration membrane decolorization device (molecular weight cutoff of 200 Da; using a spiral wound nanofiltration membrane module; the membrane separation layer was composed of polyamide polymerized from m-phenylenediamine and piperazine), operating at a pressure of 2.0 MPa and a feed temperature of 50°C. After membrane decolorization, HMF permeate and HMF residue were obtained. The HMF permeate was then pumped into a nanofiltration membrane concentration unit (using a spiral wound nanofiltration membrane module; the membrane separation layer is composed of polyamide polymerized with m-phenylenediamine; desalination rate > 98%) for concentration. The membrane concentration unit operated at a pressure of 5.0 MPa and a feed temperature of 50°C, yielding 20.8 kg of concentrated HMF and dilute HMF phases respectively. Water and dilute HMF phases were added to the HMF residue, mixed, and then returned to the crude HMF solution for further nanofiltration decolorization. When the HMF content in the HMF residue was below 0.15%, the HMF residue could be discharged from the nanofiltration system.

[0032] Example 3 A continuous decolorization and concentration method for 5-hydroxymethylfurfural comprises the following steps: Take 30 kg of crude HMF solution with a content of 5 wt% and a content of 2000 ppm of 5,5'-oxobis(methylene)bis-2-furfural. The platinum-cobalt color value of the crude solution is greater than 200 degrees. First, pass it through a nanofiltration membrane decolorization device (molecular weight cutoff of 200 Da; using a spiral wound nanofiltration membrane module; the membrane separation layer is composed of polyamide polymerized from m-phenylenediamine and piperazine), with an operating pressure of 0.6 MPa and a feed temperature of 30℃. After membrane decolorization, HMF permeate and HMF residue are obtained. Then, HMF... MF permeate is pumped into a nanofiltration membrane concentration unit (using a spiral wound nanofiltration membrane module; the membrane separation layer is composed of polyamide polymerized with m-phenylenediamine; desalination rate > 98%) for concentration. The membrane concentration unit operates at a pressure of 3.2 MPa and a feed temperature of 30°C, yielding 11.8 kg of concentrated HMF and diluted HMF phases respectively. The diluted HMF phase is added to the HMF residue, mixed, and then returned to the crude HMF solution for further nanofiltration decolorization. When the HMF content in the HMF residue is below 0.05%, the HMF residue can be discharged from the nanofiltration system.

[0033] Comparative Example 1 A method for decolorizing and concentrating 5-hydroxymethylfurfural comprises the following steps: Take 30 kg of crude HMF solution with a content of 5 wt%. The crude solution contains 4000 ppm of 5,5'-oxobis(methylene)bis-2-furfural and has a platinum-cobalt color value greater than 200 degrees. First, pass the solution into a nanofiltration membrane decolorization device (molecular weight cutoff of 600 Da; spiral wound nanofiltration membrane module; membrane separation layer composed of polyamide polymerized from m-phenylenediamine and piperazine). The operating pressure is 0.4 MPa and the feed temperature is 30℃. After membrane decolorization, HMF permeate and HMF residue are obtained. Then... HMF permeate is pumped into a nanofiltration membrane concentration unit (using a spiral wound nanofiltration membrane module; the membrane separation layer is composed of polyamide polymerized with m-phenylenediamine; desalination rate > 98%) for concentration. The membrane concentration unit operates at a pressure of 1.3 MPa and a feed temperature of 30°C, yielding 21.6 kg of concentrated HMF and diluted HMF. The diluted HMF is added to the HMF residue, mixed, and then returned to the crude HMF solution for further nanofiltration decolorization. When the HMF content in the HMF residue is below 0.3%, the HMF residue can be discharged from the nanofiltration system.

[0034] Comparative Example 2 A method for decolorizing and concentrating 5-hydroxymethylfurfural comprises the following steps: Take 30 kg of crude HMF solution with a content of 5 wt%. The crude solution contains 4000 ppm of 5,5'-oxobis(methylene)bis-2-furfural and has a platinum-cobalt color value greater than 200 degrees. First, pass the solution into a nanofiltration membrane decolorization device (molecular weight cutoff of 200 Da; using a spiral wound nanofiltration membrane module; the membrane separation layer is composed of polyamide polymerized from m-phenylenediamine and piperazine). The operating pressure is 0.3 MPa and the feed temperature is 25°C. After membrane decolorization, HMF permeate and HMF residue are obtained. Then, the HMF permeate is pumped into a nanofiltration membrane concentration device (using... A spiral wound nanofiltration membrane module; the membrane separation layer is composed of polyamide polymerized with m-phenylenediamine; the desalination rate is >98%; the membrane concentration unit operates at a pressure of 0.8 MPa and a feed temperature of 30℃, yielding 45.6 kg of concentrated HMF and diluted HMF respectively. The diluted HMF is added to the HMF residue. Due to the low concentration pressure, the amount of diluted HMF is small, requiring an additional 18.5 kg of water to be added to the HMF residue. After mixing, the solution is returned to the crude HMF solution for further nanofiltration decolorization. When the HMF content in the HMF residue is below 0.05%, the HMF residue can be discharged from the nanofiltration system.

[0035] Comparative Example 3 A method for decolorizing and concentrating 5-hydroxymethylfurfural comprises the following steps: 30 kg of crude HMF solution with a content of 2 wt% was taken. The crude solution contained 4000 ppm of 5,5'-oxobis(methylene)bis-2-furfural and had a platinum-cobalt color value greater than 200 degrees. It was first passed through a nanofiltration membrane decolorization device (molecular weight cutoff of 100 Da; spiral wound nanofiltration membrane module; membrane separation layer composed of polyamide polymerized from m-phenylenediamine and piperazine) at an operating pressure of 0.3 MPa and a feed temperature of 25°C. After membrane decolorization, HMF permeate and HMF residue were obtained. The HMF permeate was then pumped into a nanofiltration membrane concentration device (using a spiral wound nanofiltration membrane module; membrane separation layer composed of polyamide polymerized from m-phenylenediamine; desalination rate > 98%) for concentration. The membrane concentration device operated at a pressure of 3.2 MPa and a feed temperature of 30°C, yielding 3.2 MPa and 3.2 MPa of HMF residue. kg HMF concentrated phase and HMF dilute phase are mixed. The HMF dilute phase is added to the HMF residue and then returned to the crude HMF solution for further nanofiltration decolorization. The HMF content in the HMF residue is as high as 1.7%, and HMF cannot pass through the nanofiltration membrane decolorization device in large quantities.

[0036] Comparative Example 4 A continuous decolorization and concentration method for 5-hydroxymethylfurfural comprises the following steps: Take 30 kg of crude HMF solution with a content of 2 wt% and a content of 4000 ppm of 5,5'-oxobis(methylene)bis-2-furfural. The platinum-cobalt color value of the crude solution is greater than 200 degrees. First, pass it into a nanofiltration membrane decolorization device (molecular weight cutoff of 200 Da; spiral wound nanofiltration membrane module; membrane separation layer is composed of polyamide polymerized from m-phenylenediamine and piperazine). The membrane decolorization device operates at a pressure of 0.3 MPa and a feed temperature of 25℃. After membrane decolorization, HMF permeate and HMF residue are obtained. The HMF permeate was then pumped into a nanofiltration membrane concentration unit (using a spiral wound nanofiltration membrane module; the membrane separation layer is composed of polyamide polymerized with m-phenylenediamine; desalination rate > 98%) for concentration. The membrane concentration unit operated at a pressure of 3.2 MPa and a feed temperature of 5°C, yielding 11.1 kg of concentrated HMF and diluted HMF. The diluted HMF was added to the HMF residue, mixed, and then returned to the crude HMF solution for further nanofiltration decolorization. When the HMF content in the HMF residue was below 0.2%, the HMF residue could be discharged from the nanofiltration system.

[0037] Comparative Example 5 A continuous decolorization and concentration method for 5-hydroxymethylfurfural comprises the following steps: Take 30 kg of crude HMF solution with a content of 2 wt% and a content of 4000 ppm of 5,5'-oxobis(methylene)bis-2-furfural. The platinum-cobalt color value of the crude solution is greater than 200 degrees. First, pass it into a nanofiltration membrane decolorization device (molecular weight cutoff of 200 Da; spiral wound nanofiltration membrane module; membrane separation layer is composed of polyamide polymerized from m-phenylenediamine and piperazine). The membrane decolorization device operates at a pressure of 0.1 MPa and a feed temperature of 25℃. After membrane decolorization, HMF permeate and HMF residue are obtained. The HMF permeate was then pumped into a nanofiltration membrane concentration unit (using a spiral wound nanofiltration membrane module; the membrane separation layer is composed of polyamide polymerized with m-phenylenediamine; desalination rate > 98%) for concentration. The membrane concentration unit operated at a pressure of 3.2 MPa and a feed temperature of 30°C, yielding 5.7 kg of concentrated HMF and diluted HMF. The diluted HMF was added to the HMF residue, mixed, and then returned to the crude HMF solution for further nanofiltration decolorization. When the HMF content in the HMF residue was below 0.6%, the HMF residue could be discharged from the nanofiltration system.

[0038] Performance testing methods and data The crude product and the obtained pure product (HMF concentrated phase) in the examples and comparative examples were tested for content, platinum-cobalt color value and yield. The test data are listed in Table 1.

[0039] Table 1

[0040] As shown in Table 1, the test results indicate that Examples 1-3, which adopted the process parameters specified in this invention, all achieved excellent comprehensive treatment results. The HMF purity content obtained was 8.5%-21%, the platinum-cobalt color value was reduced to 21-32 degrees (all below 50 degrees), and the product yield was 96.3%-99.1% (all above 95%). The production goals of efficient decolorization, concentration and enrichment, and high product yield can be achieved simultaneously. In comparison, Comparative Example 1 used a decolorizing nanofiltration membrane with a molecular weight cutoff of 600 Da and the operating pressure of the concentration unit was too low, which could not effectively remove large molecular colored impurities. The final pure platinum-cobalt color only dropped to 184 degrees, and the decolorization effect was significantly reduced. At the same time, the insufficient concentration efficiency resulted in the product concentration and yield being significantly lower than the levels of the examples. Comparative Example 2 used a nanofiltration concentration unit with an operating pressure of only 0.8 MPa, which made it difficult to effectively permeate water through the concentration membrane and could not achieve effective concentration of HMF components. The mass content of the obtained HMF product was only 3.2%, and the yield of the concentrated light phase was insufficient, requiring a large amount of additional process water. Comparative Example 3 used a decolorizing nanofiltration membrane with a molecular weight cutoff of 100 Da. The HMF molecules were blocked from passing through the membrane, and a large amount of product remained in the residual liquid and could not be fully recovered. The overall product yield was only 22.9%. In Comparative Example 4, the feed temperature of the concentration unit was reduced to 5°C. The viscosity of the system increased, the membrane flux decreased at low temperature, and the enrichment concentration of the concentrated HMF phase was significantly reduced. Comparative Example 5 The decolorization unit operates at a pressure of only 0.1 MPa, resulting in insufficient driving force for liquid permeation. HMF cannot fully permeate through the decolorization membrane, and the final product yield is only 75.1%, with a large amount of unrecovered HMF remaining in the residual liquid.

Claims

1. A continuous decolorization and concentration method for 5-hydroxymethylfurfural, characterized in that, Includes the following steps: S1, the crude solution containing HMF is passed into a nanofiltration membrane decolorization device for decolorization and separation, and the decolorized HMF permeate and the HMF residue enriched with impurities are obtained respectively. S2, the HMF permeate is pumped into a nanofiltration membrane concentration device for concentration and separation to obtain a concentrated HMF phase and a dilute HMF phase, and the concentrated HMF phase is collected as the HMF product. S3, add the dilute HMF phase and / or make-up water to the HMF residue and mix evenly, then return it to the crude HMF solution for circulation, repeat steps S1 and S2, monitor the HMF content in the HMF residue, and discharge the HMF residue when it is lower than the set threshold. The set threshold is that the mass percentage of 5-hydroxymethylfurfural in the HMF residue is less than 0.25%.

2. The method according to claim 1, characterized in that, The crude product solution satisfies at least one of the following conditions: (1) The crude solution is prepared by isomerization or dehydration of hexoses; (2) The mass percentage of HMF in the crude product solution is 2-15%, and the content of 5,5'-oxobis(methylene)bis-2-furfural is 50-5000 ppm; (3) The platinum-cobalt color value of the crude solution is greater than 200 degrees.

3. The method according to claim 1, characterized in that, The method satisfies at least one of the following conditions: (1) The mass percentage of HMF in the HMF product is ≥5%; (2) The platinum-cobalt colorimetric value of HMF products is less than 50 degrees; (3) The yield of HMF products is >95%.

4. The method according to claim 1, characterized in that, The nanofiltration membrane decolorization device satisfies at least one of the following conditions: (1) A spiral wound nanofiltration membrane module is used; (2) The membrane separation layer is composed of polyamide, which is polymerized from aromatic amines and heterocyclic aliphatic amines; (3) It can retain impurities with a molecular weight ≥200 Da.

5. The method according to claim 1, characterized in that, The nanofiltration membrane concentration device satisfies at least one of the following conditions: (1) A spiral wound nanofiltration membrane module is used; (2) The membrane separation layer is composed of fully aromatic cross-linked polyamide; (3) Desalination rate > 98%.

6. The method according to claim 4, characterized in that, The operating parameters of the nanofiltration membrane decolorization device include: operating pressure of 0.3~2.5MPa and feed temperature of crude solution of 10~50℃.

7. The method according to claim 6, characterized in that, The operating parameters of the nanofiltration membrane decolorization device include: operating pressure of 0.3~1.0MPa and feed temperature of crude solution of 15~30℃.

8. The method according to claim 5, characterized in that, The operating parameters of the nanofiltration membrane concentration device include: operating pressure of 1.5~5.0MPa and feed solution temperature of 10~50℃.

9. The method according to claim 8, characterized in that, The operating parameters of the nanofiltration membrane concentration device include: operating pressure of 2.0~4.0MPa and feed solution temperature of 15~30℃.

10. The method according to claim 1, characterized in that, The set threshold is that the mass percentage of 5-hydroxymethylfurfural in the HMF residue is less than 0.2%.

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