A method for preparing and purifying 5-hydroxymethylfurfural crystals
By utilizing acid catalysts and purification methods in water-soluble solvents, the problem of preparing high-purity HMF crystals has been solved, achieving efficient preparation under mild conditions, suitable for industrial production, and reducing energy consumption and costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHONGKE GUOSHENG (HANGZHOU) TECH CO LTD
- Filing Date
- 2023-12-20
- Publication Date
- 2026-06-30
AI Technical Summary
Existing technologies struggle to prepare high-purity and stable 5-hydroxymethylfurfural crystals under mild conditions, primarily due to the unclear mechanism of fructose dehydration and the complexity of the reaction products, leading to unstable chemical properties of HMF.
High-purity HMF crystals were prepared by reacting sugar sources and acid catalysts in a water-soluble solvent, followed by purification through rotary evaporation, extraction, freeze drying, and column chromatography. Brønsted acid and Lewis acid were used as catalysts, and the mixture was decolorized with activated carbon and subjected to reduced pressure column chromatography.
This method enables the efficient preparation of high-purity HMF crystals under mild reaction conditions, reducing energy consumption and making it suitable for industrial production. It also improves substrate conversion and product yield, reduces impurity content, and lowers production costs.
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Figure BDA0004617108730000041
Abstract
Description
Technical Field
[0001] This invention relates to the field of biochemical technology, specifically to a method for preparing and purifying 5-hydroxymethylfurfural crystals. Background Technology
[0002] 5-Hydroxymethylfurfural (HMF) is an important platform molecule compound for the conversion of biomass into liquid fuels and chemicals. It has very active chemical properties and can be used to prepare a series of important chemical products through reactions such as esterification, addition, reduction, halogenation and hydrolysis.
[0003] Existing research on the preparation of HMF mainly focuses on raw materials, catalysts, solvents, and reaction conditions. Research on the preparation of high-purity crystals is still lacking. This is mainly because the mechanism of fructose dehydration reaction is not yet clear, the reaction products are complex, and HMF itself is chemically active and structurally unstable. Therefore, it is difficult to prepare high-purity and stable HMF crystals under room temperature conditions.
[0004] Therefore, developing a method to prepare high-purity HMF crystals under mild conditions would have excellent application prospects and significance. Summary of the Invention
[0005] To address the problems existing in the prior art, the purpose of this invention is to provide a method for preparing and purifying 5-hydroxymethylfurfural (HMF) crystals. This method utilizes a sugar source for dehydration under catalyst-assisted conditions, followed by a series of purification methods to obtain high-purity HMF crystals. The method features a simple reaction system, mild reaction temperature, and low energy consumption. All purification methods used are basic process operations, suitable for industrial production.
[0006] The technical solution adopted in this invention is as follows:
[0007] A method for preparing and purifying 5-hydroxymethylfurfural crystals involves reacting a sugar source and an acid catalyst in a first solvent with stirring to obtain a reaction solution containing crude 5-hydroxymethylfurfural, which is then purified according to the following steps:
[0008] 1) The reaction solution is rotary evaporated to remove the first solvent, and a second solvent is added in the presence of water for extraction and separation. The obtained organic phase is rotary evaporated to remove the second solvent. Water and activated carbon are added to the concentrate for decolorization, followed by filtration. The first solvent is a water-soluble solvent, and the second solvent is a non-polar solvent that is insoluble in water.
[0009] 2) The filtrate obtained in step 1) is subjected to rotary evaporation and freeze drying to remove water. The dried crystals are then separated by column chromatography to obtain high-purity 5-hydroxymethylfurfural crystals.
[0010] Furthermore, the sugar source is one or more of inulin, sucrose, glucose, fructose, and fructooligosaccharides, and the mass purity of the sugar source is between 0.5% and 100%.
[0011] Furthermore, the acid catalyst is a Brønsted acid and / or a Lewis acid, wherein the Brønsted acid is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid, and the Lewis acid is selected from any one or more of aluminum chloride, hydrated aluminum chloride, chromium chloride, and ferric chloride.
[0012] Furthermore, the mass ratio of sugar source to acid catalyst is 1:0.01-0.2, preferably 1:0.02-0.1.
[0013] Furthermore, the reaction temperature is 100-150℃, preferably 120-130℃, and the reaction time is 0.5-5h, preferably 1-3h.
[0014] Furthermore, during the stirring reaction, the mass ratio of the sugar source to the first solvent is 1:1 to 10, preferably 1:2 to 5.
[0015] Further, the water-soluble solvent is one or more of water, tetrahydrofuran, acetone, methanol, ethanol, isopropanol, acetonitrile, N,N dimethylformamide, N,N dimethylacetamide, and dimethyl sulfoxide, preferably a mixture of at least one of tetrahydrofuran, acetone, methanol, ethanol, isopropanol, acetonitrile, N,N dimethylformamide, N,N dimethylacetamide, and dimethyl sulfoxide with water in a mass ratio of 1-10:1.
[0016] Furthermore, the water-soluble solvent is a mixture of at least one of tetrahydrofuran, acetone, methanol, ethanol, isopropanol, and acetonitrile with water in a mass ratio of 2-5:1; in the subsequent purification step 1), the reaction solution is rotary evaporated to remove the organic solvent portion of the first solvent, and 1-3 times the mass of the second solvent is added to the remaining aqueous solution for extraction and separation.
[0017] Further, in step 1), 0.5-3 times the mass of pure water is added to the concentrate from which the second solvent has been removed, and 0.5-5% of the total mass of activated carbon is added to the resulting mixture for decolorization.
[0018] Further, in step 2), the filtrate is first concentrated to below 10% moisture content by rotary evaporation, and then the remaining moisture is removed by freeze drying to below 1%. The freeze drying temperature is -20℃ to 0℃, and the operating pressure is below 1 kPa. This invention first removes most of the water by rotary evaporation for rapid moisture removal; however, rotary evaporation is insufficient to remove all moisture, resulting in a moisture content below 10%. Subsequent freeze drying is used to completely remove the moisture. The presence of moisture significantly affects the preservation and transportation of HMF crystals; generally, if the moisture content exceeds 1%, the crystals easily melt at room temperature.
[0019] Furthermore, in step 2), the elution solvent for column chromatography separation is a mixture of ethyl acetate and petroleum ether in a volume ratio of 1:0.5-4. After elution, the solvent is removed by concentration to obtain high-purity 5-hydroxymethylfurfural crystals.
[0020] Furthermore, in step 2), the column chromatography separation uses a chromatography column system with alumina as the packing material.
[0021] The raw materials or reagents involved in this invention are all commercially available products, and the operations involved are all routine operations in the field unless otherwise specified.
[0022] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined to obtain specific implementation methods.
[0023] The beneficial effects of this invention are as follows: This invention provides a low-energy-consumption method for preparing HMF crystals suitable for industrial production. This method has low requirements for sugar source raw materials, is widely adaptable to crude products obtained from different production methods, and features a mild reaction temperature, high substrate conversion rate, and high product yield. Furthermore, it eliminates the need for expensive precious metal catalysts, significantly reducing industrial production costs. Simultaneously, the purification process utilizes freeze-drying combined with reduced-pressure column chromatography to greatly reduce crystal loss and impurity content, providing technical support and a foundation for the large-scale industrial production of HMF crystals. Detailed Implementation
[0024] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.
[0025] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.
[0026] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.
[0027] In this embodiment of the invention, HMF was detected using a Waters e2489 liquid chromatograph.
[0028] The formula for calculating the molar yield of 5-hydroxymethylfurfural (HMF) is as follows:
[0029]
[0030] In the following embodiments of the present invention, when high-fructose corn syrup is selected as the sugar source, the final HMF yield is calculated based on the amount of fructose equivalents that the high-fructose corn syrup can hydrolyze to produce. This is because the glucose in the high-fructose corn syrup is not converted into HMF in this reaction system, so the HMF yield is calculated based only on the fructose content.
[0031] Example 1
[0032] Prepare a 500g fructose aqueous solution (50% fructose by mass) by mixing 500g fructose and 500g water. Add 10g phosphoric acid and 10g calcium chloride. Use tetrahydrofuran (THF) as the organic solvent (2040g of THF). React the mixture in a multi-functional reactor at 130℃ for 1 hour to obtain a preliminary reaction solution. Remove THF by rotary evaporation at an absolute pressure below 1 kPa and a temperature of 30℃ to obtain 1008g of aqueous solution. Add 2016g of ethyl acetate in a 2:1 ratio for extraction. Remove the ethyl acetate from the extracted organic phase by rotary evaporation at an absolute pressure of 0.1-1 kPa and a temperature of 38℃ to obtain solution 1. Take 11000g of solution and add pure water at a 1:1 mass ratio. Add 2% activated carbon for decolorization. Remove most of the water from the filtrate obtained by pressure filtration by rotary evaporation (the water content of the solution should be below 10%). The rotary evaporation conditions are an absolute pressure below 1 kPa and a temperature of 50℃. The crystals were then freeze-dried to remove all moisture (reducing the moisture content to below 1%) at temperatures ranging from -20°C to 0°C and absolute pressures below 0.2 kPa. The resulting dried crystals were then transferred to a chromatography column packed with alumina, using ethyl acetate and petroleum ether as eluents in a 1:1 volume ratio. Vacuum chromatography was performed using a diaphragm pump. The eluent was then rotary evaporated and freeze-dried to obtain high-purity HMF crystals with a purity of 98.12% and a yield of 89.44%.
[0033] Example 2
[0034] The conditions of Example 1 were repeated, but without decolorization using activated carbon, and all other conditions remained unchanged, to obtain HMF crystals with a purity of 82.54% and a yield of 92.5%.
[0035] Example 3
[0036] The conditions of Example 1 were repeated, but column chromatography was not performed at the end. All other conditions remained unchanged, and HMF crystals were obtained with a purity of 94.23% and a yield of 93.9%.
[0037] Example 4
[0038] The conditions of Example 1 were repeated. The aqueous solution obtained after removing tetrahydrofuran from the initial reaction solution was directly subjected to column chromatography for separation. Other conditions remained unchanged. The purity of HMF was 76.80% and the yield was 98.9%.
[0039] Example 5
[0040] The conditions of Example 1 were repeated. The aqueous solution obtained after removing tetrahydrofuran from the initial reaction solution was first decolorized with activated carbon (i.e., the step of replacing activated carbon decolorization). The subsequent steps were repeated, with other conditions remaining unchanged. The control results showed that the purity of HMF was 99.31% and the yield was 87.69%.
[0041] Example 6
[0042] Take 1000g of 70% fructose syrup, add 10g of sulfuric acid and 10g of magnesium chloride, and use acetone as the organic solvent, adding 2040g. React in a multifunctional reactor at 150℃ for 1.5h to obtain a preliminary reaction solution. After evaporating the acetone at an absolute pressure below 1kPa and a temperature of 20℃, 286g of aqueous solution is obtained. Add 572g of ethyl acetate at twice the ratio for extraction. The organic phase obtained after extraction is evaporated at an absolute pressure below 1kPa and a temperature of 38℃ to remove ethyl acetate, obtaining solution 1. Add pure water to solution 1 at a 1:1 mass ratio, and add activated carbon at 2% of the total mass for decolorization. The filtrate obtained by pressure filtration is evaporated to remove most of the water (at this point, the water content of the solution should be less than 10%). The evaporation conditions are an absolute pressure below 1kPa and a temperature of 50℃. Then, freeze-dry to remove all water (reducing the water content to below 1%). The freeze-drying temperature is -20℃ to 0℃, and the absolute pressure is below 0.2kPa. The dried crystals were then transferred to a silica gel-filled chromatography column system, with ethyl acetate and petroleum ether as the elution solvents in a volume ratio of 1:3. The chromatography was performed under reduced pressure using a diaphragm pump. The eluent was then subjected to rotary evaporation and freeze-drying to obtain high-purity HMF crystals with a purity of 96.42% and a yield of 85.87%.
[0043] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.
Claims
1. A method for preparing and purifying 5-hydroxymethylfurfural crystals, characterized in that, The sugar source and acid catalyst were reacted in the first solvent by stirring to obtain a reaction solution containing crude 5-hydroxymethylfurfural, which was then purified according to the following steps: 1) The reaction solution is rotary evaporated to remove the first solvent, and a second solvent is added in the presence of water for extraction and separation. The obtained organic phase is rotary evaporated to remove the second solvent. Water and activated carbon are added to the concentrate for decolorization, followed by filtration. The first solvent is a water-soluble solvent, and the second solvent is a non-polar solvent that is insoluble in water. 2) The filtrate obtained in step 1) was subjected to rotary evaporation and freeze drying to remove water. The dried crystals were then separated by column chromatography to obtain high-purity 5-hydroxymethylfurfural crystals. The water-soluble solvent is a mixture of at least one of tetrahydrofuran, acetone, methanol, ethanol, isopropanol, and acetonitrile with water in a mass ratio of 2-5:1; in the subsequent purification step 1), the reaction solution is rotary evaporated to remove the organic solvent portion of the first solvent, and 1-3 times the mass of the second solvent is added to the remaining aqueous solution for extraction and separation. In step 1), 0.5-3 times the mass of pure water is added to the concentrate after removing the second solvent, and 0.5-5% of the total mass of activated carbon is added to the resulting mixture for decolorization. In step 2), the filtrate is first concentrated to a moisture content of less than 10% by rotary evaporation, and then the remaining moisture is removed by freeze drying. The sugar source is fructose, and the purity of the sugar source is between 0.5% and 100%. The acid catalyst is orthophosphoric acid and calcium chloride, or sulfuric acid and magnesium chloride; The mass ratio of sugar source to acid catalyst is 1:0.01-0.
2.
2. The method for preparing and purifying 5-hydroxymethylfurfural crystals as described in claim 1, characterized in that... The mass ratio of sugar source to acid catalyst is 1:0.02-0.
1.
3. The method for preparing and purifying 5-hydroxymethylfurfural crystals as described in claim 1, characterized in that... The reaction temperature is 100-150℃, and the reaction time is 0.5-5h.
4. The method for preparing and purifying 5-hydroxymethylfurfural crystals as described in claim 3, characterized in that... The reaction temperature is 120-130℃, and the reaction time is 1-3h.
5. The method for preparing and purifying 5-hydroxymethylfurfural crystals as described in claim 1, characterized in that... During the stirring reaction, the mass ratio of sugar source to first solvent is 1:1 to 10.
6. The method for preparing and purifying 5-hydroxymethylfurfural crystals as described in claim 5, characterized in that... During the stirring reaction, the mass ratio of sugar source to the first solvent is 1:2-5.
7. The method for preparing and purifying 5-hydroxymethylfurfural crystals as described in claim 1, characterized in that... In step 2), the moisture content is removed to below 1%, the freeze-drying temperature is -20℃ to 0℃, and the operating pressure is below 1 kPa.
8. The method for preparing and purifying 5-hydroxymethylfurfural crystals as described in claim 1, characterized in that... In step 2), the elution solvent for column chromatography is a mixture of ethyl acetate and petroleum ether in a volume ratio of 1:0.5-4. After elution, the solvent is removed by concentration to obtain high-purity 5-hydroxymethylfurfural crystals.
9. The method for preparing and purifying 5-hydroxymethylfurfural crystals as described in claim 1, characterized in that... Step 2) The column chromatography separation uses a chromatography column system with alumina as the packing material.