Process for the isolation and purification of 5-hydroxymethylfurfural

Abstract

The application discloses a method for separating and purifying 5-hydroxymethylfurfural. The method comprises the following steps: mixing water and an organic solution containing 5-hydroxymethylfurfural and an aprotic polar solvent to obtain a first mixed solution; performing extraction treatment on the first mixed solution by using an extractant to obtain a raffinate phase and an extraction phase containing 5-hydroxymethylfurfural; performing back extraction treatment on the extraction phase by using a sugar aqueous solution to obtain a back extraction raffinate phase and a back extraction extraction phase containing 5-hydroxymethylfurfural; and performing evaporation and crystallization treatment on the back extraction extraction phase to obtain 5-hydroxymethylfurfural. The method for separating and purifying 5-hydroxymethylfurfural has the advantages of mild conditions, high separation efficiency, high product purity, small loss of the aprotic polar solvent and the extractant, and the like, and is suitable for continuous, stable and large-scale production application.

Description

Technical Field

[0001] This invention relates to the field of furfural production technology, and specifically to a method for separating and purifying 5-hydroxymethylfurfural. Background Technology

[0002] Biomass-derived 5-hydroxymethylfurfural (HMF) has a furan ring, an aldehyde group, and a hydroxyl group. It is a chemically active intermediate that can generate a variety of derivatives through oxidation, hydrogenation, and other reactions. It is a bio-based chemical with great application prospects.

[0003] To achieve highly selective dehydration of sugars to prepare high-molecular-weight fatty acids (HMF), aprotic polar solvents are typically used as reaction solvents, with dimethyl sulfoxide (DMSO) being one of the most widely used. Currently, various methods are applied to the extraction and purification of HMF, including distillation, adsorption, crystallization, and extraction. Distillation typically yields high-purity HMF, but thermally unstable HMF often degrades, reducing the yield. Adsorption methods suffer from drawbacks such as long adsorption cycles, easy clogging of the adsorbent, and high regeneration energy consumption, limiting their industrial application. Crystallization requires low-temperature operation and also has high energy consumption. Furthermore, the physicochemical properties of DMSO make it difficult to separate HMF from it using conventional methods. Currently, the main method for separating HMF from DMSO is liquid-liquid extraction, but this method suffers from significant losses of DMSO and extractant, as well as low separation efficiency.

[0004] Therefore, the technology for separating and purifying 5-hydroxymethylfurfural still needs improvement. Summary of the Invention

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, one object of this invention is to provide a method for separating and purifying 5-hydroxymethylfurfural that has advantages such as high separation efficiency and minimal loss of aprotic polar solvents and extractants.

[0006] In one aspect of the invention, a method for separating and purifying 5-hydroxymethylfurfural is provided. According to embodiments of the invention, the method includes:

[0007] (1) Mix water with an organic solution containing 5-hydroxymethylfurfural and an aprotic polar solvent to obtain a first mixture;

[0008] (2) The first mixture is extracted with an extractant to obtain a raffinate phase and an extract phase containing 5-hydroxymethylfurfural;

[0009] (3) The extract phase is back-extracted using a sugar solution to obtain a back-extract residue phase and a back-extract phase containing 5-hydroxymethylfurfural;

[0010] (4) The back-extracted phase is evaporated and crystallized to obtain 5-hydroxymethylfurfural.

[0011] According to the method for separating and purifying 5-hydroxymethylfurfural of the above embodiments of the present invention, by mixing water with an organic solution containing 5-hydroxymethylfurfural and an aprotic polar solvent, a strong interaction is formed between the water and the aprotic polar solvent in the organic solution, which can reduce the effect of the aprotic polar solvent on the extractant and 5-hydroxymethylfurfural during subsequent extraction. The first mixture is then extracted using an extractant, taking advantage of the difference in solubility of 5-hydroxymethylfurfural in the aprotic polar solvent and the extractant, allowing 5-hydroxymethylfurfural to be extracted from the aprotic polar solvent. The solution is transferred to the extractant, yielding a raffinate phase and an extractant phase containing 5-hydroxymethylfurfural. The water in the first mixture reduces the effect of the aprotic polar solvent on the extractant and 5-hydroxymethylfurfural, thus reducing the solubility between the aprotic polar solvent and the extractant, and improving the distribution of 5-hydroxymethylfurfural in the extractant, thereby increasing separation efficiency and reducing the loss of aprotic polar solvent and extractant. Back-extraction of the extractant phase with a sugar solution utilizes the interaction between water and the aprotic polar solvent to remove residual aprotic polar solvent from the extractant phase, thus facilitating the acquisition of high-purity 5-hydroxymethylfurfural. Furthermore, the sugar in the sugar solution, due to its numerous hydroxyl groups, can form strong interactions with both water and the aprotic polar solvent, reducing the interaction between water and the aprotic polar solvent and 5-hydroxymethylfurfural, thereby increasing the partition coefficient of 5-hydroxymethylfurfural in the extractant and improving separation efficiency. On the other hand, it increases water saturation, reducing the solubility of the extractant in water, thus reducing extractant loss. Moreover, sugar is essential for the production of 5-hydroxymethylfurfural. The raw material for furfural, after extraction, yields a back-extraction residue that can be recycled to the sugar dehydration reaction system for the preparation of 5-hydroxymethylfurfural. This reduces the loss of aprotic polar solvents and allows for organic integration with the sugar dehydration reaction system, eliminating the need to separate the sugar from the back-extraction residue, thus facilitating continuous production of 5-hydroxymethylfurfural. Evaporation and crystallization of the back-extraction residue allow 5-hydroxymethylfurfural to precipitate from the extractant, resulting in high-purity 5-hydroxymethylfurfural. Therefore, the method for separating and purifying 5-hydroxymethylfurfural of this invention offers advantages such as mild conditions, high separation efficiency, high product purity, and minimal loss of aprotic polar solvents and extractants, making it suitable for continuous and stable scale-up production applications.

[0012] In addition, the method for separating and purifying 5-hydroxymethylfurfural according to the above embodiments of the present invention may also have the following additional technical features:

[0013] In some embodiments of the present invention, in step (1), the volume ratio of the water to the organic solution is 1:9 to 9:1. This can improve the extraction rate, reduce the solubility of the extractant, reduce extractant loss, and lower the separation cost.

[0014] In some embodiments of the present invention, in step (1), the aprotic polar solvent includes at least one of dimethyl sulfoxide, N,N-dimethylformamide, eutectic solvent and ionic liquid.

[0015] In some embodiments of the present invention, in step (2), the extractant includes at least one of methyl isobutyl ketone, ethyl acetate, methyl propionate, diethyl ether, 2-methyltetrahydrofuran, and n-butanol. This is beneficial for improving the extraction rate.

[0016] In some embodiments of the present invention, in step (2), the volume ratio of the extractant to the first mixture is 1:9 to 9:1. This can improve the extraction rate, reduce the loss of aprotic polar solvent, and lower the recovery cost.

[0017] In some embodiments of the present invention, in step (3), the sugar in the sugar solution includes at least one of sucrose, glucose, fructose, maltose, trehalose, cellobiose, and lactose.

[0018] In some embodiments of the present invention, in step (3), the volume ratio of the sugar aqueous solution to the extract phase is 1:9-9:1. This can improve the recovery rate of 5-hydroxymethylfurfural and facilitate the obtaining of high-purity 5-hydroxymethylfurfural.

[0019] In some embodiments of the present invention, the sugar concentration in the sugar aqueous solution is 10 g / L to 1000 g / L. This reduces the amount of 5-hydroxymethylfurfural entering the aqueous phase and simultaneously reduces the loss of extractant.

[0020] In some embodiments of the present invention, in step (4), the pressure for evaporating the back-extraction phase is 100 Pa to 2000 Pa, and the temperature for crystallizing the back-extraction phase is -30°C to 0°C. This can effectively reduce the loss of 5-hydroxymethylfurfural.

[0021] In some embodiments of the present invention, the above method further includes: (5) feeding the raffinate and the back-extraction raffinate to a reaction system for sugar dehydration to prepare 5-hydroxymethylfurfural, so as to convert the sugar in the raffinate and the back-extraction raffinate into 5-hydroxymethylfurfural. This is beneficial for achieving continuous and stable scale-up production applications.

[0022] In some embodiments of the present invention, before feeding the raffinate and the back-extraction raffinate into the reaction system for the dehydration of sugar to prepare 5-hydroxymethylfurfural, the raffinate and the back-extraction raffinate are mixed to obtain a second mixture, and the second mixture is subjected to adsorption treatment and water content adjustment. This facilitates continuous and stable scale-up production applications.

[0023] In some embodiments of the present invention, the adsorption treatment is carried out using at least one of resin, diatomaceous earth, and activated clay. This facilitates continuous and stable scale-up production applications.

[0024] In some embodiments of the present invention, after the second mixture undergoes adsorption treatment and water content adjustment, the water content in the second mixture is 20wt%-60wt%. This facilitates continuous and stable scale-up production applications.

[0025] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0026] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0027] Figure 1 This is a schematic flowchart of a method for separating and purifying 5-hydroxymethylfurfural according to an embodiment of the present invention;

[0028] Figure 2 This is a flowchart of the experimental system according to Embodiment 29 of the present invention, wherein A is an extractor, B is a back extractor, C is a vacuum evaporator, and D is a dehydrator. Detailed Implementation

[0029] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0030] The technical solution of this invention was developed by the inventors based on the following discovery: the separation of 5-hydroxymethylfurfural (HMF) from aprotic polar reaction solutions such as DMSO is affected by the strong interaction between HMF and DMSO, resulting in low liquid-liquid extraction efficiency, large solvent loss, and low product purity. Related technologies improve the partition coefficient of HMF during extraction by adding salts such as NaCl, but the addition of salts significantly increases the cost of solution separation, and chloride ions are highly corrosive to stainless steel equipment, making them difficult to apply in industrial production.

[0031] Therefore, in one aspect of the present invention, a method for separating and purifying 5-hydroxymethylfurfural is provided. According to embodiments of the present invention, refer to... Figure 1 The method includes:

[0032] S100: Mix water with an organic solution containing 5-hydroxymethylfurfural and an aprotic polar solvent.

[0033] In this step, water is mixed with an organic solution containing 5-hydroxymethylfurfural and an aprotic polar solvent to obtain a first mixture. Since the aprotic polar solvent has excellent solubility in many organic solvents, by mixing water with the organic solution containing 5-hydroxymethylfurfural and an aprotic polar solvent, water can form a strong interaction with the aprotic polar solvent in the organic solution. This reduces the effect of the aprotic polar solvent on the extractant and 5-hydroxymethylfurfural during subsequent extraction, thereby reducing the solubility between the aprotic polar solvent and the extractant, improving the distribution of 5-hydroxymethylfurfural in the extractant, thus increasing separation efficiency and reducing the loss of the aprotic polar solvent and extractant. Specifically, the organic solution containing 5-hydroxymethylfurfural and an aprotic polar solvent may include the reaction solution for the preparation of 5-hydroxymethylfurfural by sugar dehydration, and the aprotic polar solvent may include at least one of dimethyl sulfoxide, N,N-dimethylformamide, eutectic solvent (such as a mixture of choline chloride and ethylene glycol in a mass ratio of 2:1) and ionic liquid (such as 1-ethyl-3-methylimidazole chloride).

[0034] According to embodiments of the present invention, the volume ratio of water to the organic solution containing 5-hydroxymethylfurfural and an aprotic polar solvent can be 1:9 to 9:1, for example, 1:9, 2:8, 3:7, 5:5, 6:4, 7:3, 8:2, 9:1, etc. The inventors have found that if the volume ratio of water to the organic solution containing 5-hydroxymethylfurfural and an aprotic polar solvent is too large, it will lead to an increase in the subsequent separation cost of water and the aprotic polar solvent; if the volume ratio is too small, the effect of improving the extraction rate and reducing extractant loss is not significant. The present invention, by controlling the volume ratio of water to the organic solution containing 5-hydroxymethylfurfural and an aprotic polar solvent within the above-mentioned range, can improve the extraction rate, reduce extractant solubility, reduce extractant loss, and lower separation costs.

[0035] S200: Extraction treatment of the first mixture using an extractant.

[0036] In this step, the first mixture is extracted using an extractant. Taking advantage of the difference in solubility of 5-hydroxymethylfurfural in the aprotic polar solvent and the extractant, 5-hydroxymethylfurfural is transferred from the aprotic polar solvent to the extractant, resulting in a raffinate phase and an extract phase containing 5-hydroxymethylfurfural. Furthermore, the water in the first mixture reduces the effect of the aprotic polar solvent on the extractant and 5-hydroxymethylfurfural, thereby reducing the solubility between the aprotic polar solvent and the extractant and improving the distribution of 5-hydroxymethylfurfural in the extractant. This improves separation efficiency and reduces the loss of both the aprotic polar solvent and the extractant.

[0037] It should be noted that the specific composition of the extractant is not particularly limited, and those skilled in the art can choose it according to actual needs, as long as it meets the requirements of low solubility in aprotic polar solvents and good solubility in HMF. For example, the extractant may include at least one of methyl isobutyl ketone, ethyl acetate, methyl propionate, diethyl ether, 2-methyltetrahydrofuran, and n-butanol. This is beneficial for improving the extraction rate.

[0038] According to embodiments of the present invention, the volume ratio of the extractant to the first mixture can be 1:9-9:1, for example, 1:9, 2:8, 3:7, 1:1, 2:1, 3:1, 4:1, 5:1, 9:1, etc. The inventors have found that if the volume ratio of the extractant to the first mixture is too large, the loss of aprotic polar solvent increases, leading to higher recovery costs. If the volume ratio is too small, the extraction rate decreases. The present invention, by controlling the volume ratio of the extractant to the first mixture within the above-mentioned range, can improve the extraction rate and reduce the loss of aprotic polar solvent, thereby lowering recovery costs. Furthermore, the number of extraction stages for extracting the first mixture using the extractant is preferably 3-12 stages. Through multi-stage extraction, 5-hydroxymethylfurfural in the first mixture can be extracted into the organic solvent as much as possible, thereby improving the recovery rate of 5-hydroxymethylfurfural.

[0039] S300: Back-extraction of the extract phase is performed using a sugar solution.

[0040] In this step, a sugar solution is used to back-extract the extract phase, yielding a back-extract residue phase and a back-extract phase containing 5-hydroxymethylfurfural. Typically, the extract phase after extraction contains a certain amount of aprotic polar solvent, resulting in low purity of 5-hydroxymethylfurfural. Back-extraction with a sugar solution utilizes the interaction between water and the aprotic polar solvent to remove the residual aprotic polar solvent from the extract phase, thus facilitating the acquisition of high-purity 5-hydroxymethylfurfural. Furthermore, the sugar in the sugar solution, due to its numerous hydroxyl groups, can form strong interactions with both water and the aprotic polar solvent, reducing the interaction between water and the aprotic polar solvent. The interaction between 5-hydroxymethylfurfural and other solvents increases the partition coefficient of 5-hydroxymethylfurfural in the extractant, thereby improving the separation efficiency. On the other hand, it can increase the water saturation, reduce the water solubility in the extractant, and thus reduce the loss of the extractant. Furthermore, sugar is the raw material for the production of 5-hydroxymethylfurfural, and the back-extraction residue obtained after extraction can be recycled to the sugar dehydration to prepare 5-hydroxymethylfurfural reaction system. Thus, on the one hand, it can reduce the loss of aprotic polar solvent, and on the other hand, it can be organically combined with the sugar dehydration to prepare 5-hydroxymethylfurfural reaction system, without the need to separate the sugar in the back-extraction residue, which is conducive to the continuous production of 5-hydroxymethylfurfural.

[0041] According to embodiments of the present invention, the volume ratio of the sugar solution to the extract phase can be 1:9-9:1, for example, 1:9, 1:6, 1:3, 1:2, 1:1, 2:1, 3:1, 6:1, 9:1, etc. The inventors have discovered that the interaction between water and 5-hydroxymethylfurfural leads to some 5-hydroxymethylfurfural entering the sugar solution. If the volume ratio of the sugar solution to the extract phase is too large, the recovery rate of 5-hydroxymethylfurfural decreases; if the volume ratio is too small, it is not conducive to obtaining high-purity 5-hydroxymethylfurfural. The present invention improves the recovery rate of 5-hydroxymethylfurfural and facilitates the obtaining of high-purity 5-hydroxymethylfurfural by controlling the volume ratio of the sugar solution to the extract phase within the above-mentioned range. Furthermore, the preferred number of stages for back-extraction of the extract phase using the sugar solution is 2-12 stages. Multi-stage extraction can remove as much aprotic polar solvent as possible from the extract phase, thereby improving the purity of 5-hydroxymethylfurfural.

[0042] It should be noted that the sugar solution is a homogeneous solution, and the specific type of sugar used is not particularly limited. Those skilled in the art can select the appropriate sugar according to actual needs. For example, the sugar used may include at least one of sucrose, glucose, fructose, maltose, trehalose, cellobiose, and lactose. Specifically, the sugar concentration in the sugar solution can be 10 g / L to 1000 g / L. This reduces the amount of 5-hydroxymethylfurfural entering the aqueous phase and simultaneously reduces the loss of the extractant.

[0043] S400: Evaporation and crystallization of the back-extraction phase.

[0044] In this step, the back-extraction phase is evaporated and crystallized to obtain 5-hydroxymethylfurfural. Evaporation and crystallization of the back-extraction phase allows 5-hydroxymethylfurfural to precipitate from the extractant, resulting in 5-hydroxymethylfurfural with high purity. Therefore, the method for separating and purifying 5-hydroxymethylfurfural of the present invention has advantages such as high separation efficiency, high product purity, and minimal loss of aprotic polar solvents and extractants, making it suitable for continuous and stable scale-up production applications.

[0045] According to embodiments of the present invention, the pressure for evaporating the back-extraction phase can be 100 Pa to 2000 Pa, and the temperature for crystallizing the back-extraction phase is -30°C to 0°C. Since 5-hydroxymethylfurfural has very high reactivity and a high boiling point, the present invention can effectively reduce the loss of 5-hydroxymethylfurfural by performing reduced-pressure evaporation and low-temperature crystallization under the above conditions.

[0046] According to embodiments of the present invention, the above method may further include:

[0047] S500: The raffinate and the back-extraction raffinate are fed into the reaction system for sugar dehydration to prepare 5-hydroxymethylfurfural.

[0048] In this step, the raffinate and the back-extraction raffinate are supplied to the reaction system for the preparation of 5-hydroxymethylfurfural (5-HMF) from sugar dehydration, so as to convert the sugar in the raffinate and back-extraction raffinate into 5-HMF. Specifically, before supplying the raffinate and back-extraction raffinate to the reaction system, the raffinate and back-extraction raffinate can be mixed to obtain a second mixture. The second mixture is then subjected to adsorption treatment and water content adjustment to remove impurities such as humic substances (which are generated during the sugar dehydration process for 5-HMF) and to obtain a water content suitable for the sugar dehydration process for 5-HMF. This allows for better compatibility between the extraction step and the sugar dehydration process for 5-HMF, enabling continuous production of 5-HMF and recycling of the reaction solvent. Specifically, the adsorption treatment can be performed using at least one of resin, diatomaceous earth, and activated clay. After adsorption treatment and water content adjustment, the water content in the second mixture can be 20wt%-60wt%.

[0049] Therefore, the method for separating and purifying 5-hydroxymethylfurfural of the present invention, from the perspective of extraction efficiency and operation integration and optimization, effectively improves the efficiency of separating and purifying 5-hydroxymethylfurfural and the purity of the product, reduces the loss of aprotic polar solvent and extractant, and can be organically combined with the reaction system for preparing 5-hydroxymethylfurfural by sugar dehydration, which is conducive to continuous and stable scale-up production applications.

[0050] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0051] Example 1

[0052] Using a reaction solution containing 60 g / L HMF (hydrogen methyl furfural) and DMSO as solvent for the dehydration of sugar to prepare 5-hydroxymethylfurfural as raw material, a water volume ratio of 1:9 was added to obtain a first mixture. The first mixture was then extracted using methyl isobutyl ketone (MIBK) as the extractant, yielding an extract phase and a raffinate phase. The extractant-to-first-mixture volume ratio was 1:1, and the extraction stage was 5 stages. The DMSO mass content in the extract phase, the extractant mass content in the raffinate phase, and the HMF extraction rate are shown in Table 1.

[0053] Example 2

[0054] In Example 2, the volume ratio of water to reaction liquid was 3:7, and other steps and conditions were the same as in Example 1. The mass content of DMSO in the extract phase, the mass content of extractant in the raffinate phase, and the HMF extraction rate are shown in Table 1.

[0055] Example 3

[0056] In Example 3, the volume ratio of water to reaction liquid was 1:1, and other steps and conditions were the same as in Example 1. The mass content of DMSO in the extract phase, the mass content of extractant in the raffinate phase, and the HMF extraction rate are shown in Table 1.

[0057] Example 4

[0058] In Example 4, the volume ratio of water to reaction liquid was 7:3, and other steps and conditions were the same as in Example 1. The mass content of DMSO in the extract phase, the mass content of extractant in the raffinate phase, and the HMF extraction rate are shown in Table 1.

[0059] Example 5

[0060] In Example 5, the volume ratio of water to reaction liquid was 9:1, and other steps and conditions were the same as in Example 1. The mass content of DMSO in the extract phase, the mass content of extractant in the raffinate phase, and the HMF extraction rate are shown in Table 1.

[0061] Example 6

[0062] In Example 6, ethyl acetate was used as the extractant, and the other steps and conditions were the same as in Example 3. The mass content of DMSO in the extract phase, the mass content of extractant in the raffinate phase, and the HMF extraction rate are shown in Table 1.

[0063] Example 7

[0064] In Example 7, diethyl ether was used as the extractant, and the other steps and conditions were the same as in Example 3. The mass content of DMSO in the extract phase, the mass content of extractant in the raffinate phase, and the HMF extraction rate are shown in Table 1.

[0065] Example 8

[0066] In Example 8, 2-methyltetrahydrofuran was used as the extractant, and the other steps and conditions were the same as in Example 3. The mass content of DMSO in the extract phase, the mass content of extractant in the raffinate phase, and the HMF extraction rate are shown in Table 1.

[0067] Example 9

[0068] In Example 9, n-butanol was used as the extractant, and the other steps and conditions were the same as in Example 3. The mass content of DMSO in the extract phase, the mass content of extractant in the raffinate phase, and the HMF extraction rate are shown in Table 1.

[0069] Example 10

[0070] In Example 10, the volume ratio of the extractant to the first mixture was 2:1, and the other steps and conditions were the same as in Example 3. The HMF extraction rate is shown in Table 1.

[0071] Example 11

[0072] In Example 11, the volume ratio of the extractant to the first mixture was 3:1, and the other steps and conditions were the same as in Example 3. The HMF extraction rate is shown in Table 1.

[0073] Example 12

[0074] In Example 12, the volume ratio of the extractant to the first mixture was 4:1, and the other steps and conditions were the same as in Example 3. The HMF extraction rate is shown in Table 1.

[0075] Example 13

[0076] In Example 13, the volume ratio of the extractant to the first mixture was 5:1, and the other steps and conditions were the same as in Example 3. The HMF extraction rate is shown in Table 1.

[0077] Table 1

[0078]

[0079] As shown in Examples 1-5, with the increase of water addition, the mass content of DMSO in the extract phase and MIBK in the raffinate phase gradually decreased, while the extraction rate of HMF gradually increased. This indicates that increasing the water content is beneficial for improving the extraction rate of HMF and reducing solvent loss. This is because hydrogen bonds are formed between water and DMSO, reducing the effect of DMSO on the extractant and HMF. However, adding too much water will increase the cost of subsequent water-DMSO separation. In actual production, the amount of water added needs to be determined based on production costs.

[0080] As can be seen from Examples 3 and 6-9, the highest HMF extraction rate was achieved with ethyl acetate and the lowest with n-butanol. At the same time, when n-butanol was used as the extractant, the solubility of DMSO in the extract phase was the highest, and the solubility of the extractant in the extract phase was also the highest. This is mainly because the hydroxyl group of n-butanol caused a strong interaction between it and DMSO.

[0081] As can be seen from Examples 10-13, the extraction rate of HMF gradually increases with the increase of the amount of extractant.

[0082] Example 14

[0083] Using a reaction solution containing 60 g / L HMF and DMSO as solvent for the dehydration of sugar to prepare 5-hydroxymethylfurfural as raw material, a water volume ratio of 1:1 was added to obtain a first mixture. The first mixture was then extracted with methyl isobutyl ketone (MOH) as the extractant to obtain an extract phase and a raffinate phase. The volume ratio of the extractant to the first mixture was 1:1, and the extraction stage was 5 stages. A sugar aqueous solution was added to the obtained extract phase for back-extraction. The volume ratio of the sugar aqueous solution to the extract phase was 1:1, the glucose concentration in the sugar aqueous solution was 500 g / L, and the back-extraction stage was 5 stages. The mass fraction of DMSO in the back-extraction extractant phase, the mass fraction of water in the back-extraction extractant phase, the mass fraction of MIBK in the back-extraction raffinate phase, the HMF recovery rate, and the HMF purity are shown in Table 2.

[0084] Example 15

[0085] In Example 15, the glucose concentration in the added sugar solution was 300 g / L, and the other steps and conditions were the same as in Example 14. The mass fraction of DMSO in the back-extraction phase, the mass fraction of water in the back-extraction phase, the mass fraction of MIBK in the back-extraction residue phase, the HMF recovery rate, and the HMF purity are shown in Table 2.

[0086] Example 16

[0087] In Example 16, the glucose concentration in the added sugar solution was 100 g / L, and the other steps and conditions were the same as in Example 14. The mass fraction of DMSO in the back-extraction phase, the mass fraction of water in the back-extraction phase, the mass fraction of MIBK in the back-extraction residue phase, the HMF recovery rate, and the HMF purity are shown in Table 2.

[0088] Example 17

[0089] In Example 17, the volume ratio of the added sugar solution to the extraction phase was 1:3, and the other steps and conditions were the same as in Example 14. The HMF recovery rate and HMF purity are shown in Table 2.

[0090] Example 18

[0091] In Example 18, the volume ratio of the added sugar solution to the extraction phase was 1:2, and the other steps and conditions were the same as in Example 14. The HMF recovery rate and HMF purity are shown in Table 2.

[0092] Example 19

[0093] In Example 19, the volume ratio of the added sugar solution to the extraction phase was 2:1, and the other steps and conditions were the same as in Example 14. The HMF recovery rate and HMF purity are shown in Table 2.

[0094] Example 20

[0095] In Example 20, the back-extraction stage was 2 stages, and the other steps and conditions were the same as in Example 14. The HMF recovery rate and HMF purity are shown in Table 2.

[0096] Example 21

[0097] In Example 21, the back-extraction stage was 3 stages, and the other steps and conditions were the same as in Example 14. The HMF recovery rate and HMF purity are shown in Table 2.

[0098] Example 22

[0099] In Example 22, the back-extraction stage was 4 stages, and the other steps and conditions were the same as in Example 14. The HMF recovery rate and HMF purity are shown in Table 2.

[0100] Example 23

[0101] In Example 23, the back-extraction stage was 6 stages, and the other steps and conditions were the same as in Example 14. The HMF recovery rate and HMF purity are shown in Table 2.

[0102] Example 24

[0103] In Example 24, the back-extraction stage was 7 stages, and the other steps and conditions were the same as in Example 14. The HMF recovery rate and HMF purity are shown in Table 2.

[0104] Example 25

[0105] In Example 25, the extraction stage was 3 stages, and the other steps and conditions were the same as in Example 14. The HMF recovery rate and HMF purity are shown in Table 2.

[0106] Example 26

[0107] In Example 26, the raw material was a reaction solution for the dehydration of sugar to prepare 5-hydroxymethylfurfural using N,N-dimethylformamide (DMF) as solvent, containing 60 g / L HMF. The extraction stage was 3 stages, and other steps and conditions were the same as in Example 14. The HMF recovery rate and HMF purity are shown in Table 2.

[0108] Example 27

[0109] In Example 27, the raw material was a reaction solution for the dehydration of sugar to prepare 5-hydroxymethylfurfural containing 60 g / L HMF, using a eutectic solvent (a mixture of choline chloride and ethylene glycol in a mass ratio of 2:1) as the solvent. The extraction stage was 3 stages, and other steps and conditions were the same as in Example 14. The HMF recovery rate and HMF purity are shown in Table 2.

[0110] Example 28

[0111] In Example 28, the raw material was a reaction solution for the dehydration of sugar to prepare 5-hydroxymethylfurfural containing 60 g / L HMF and using an ionic liquid (1-ethyl-3-methylimidazolium chloride) as the solvent. The extraction stage was 3 stages, and other steps and conditions were the same as in Example 14. The HMF recovery rate and HMF purity are shown in Table 2.

[0112] Comparative Example 1

[0113] In Comparative Example 1, water (sugar-free) was added to the obtained extract phase for back-extraction, and other steps and conditions were the same as in Example 14. The mass fraction of DMSO in the back-extraction extract phase, the mass fraction of water in the back-extraction extract phase, the mass fraction of MIBK in the back-extraction raffinate, the HMF recovery rate, and the HMF purity are shown in Table 2.

[0114] Table 2

[0115]

[0116]

[0117] As can be seen from Comparative Example 1 and Examples 14-16, the recovery rate and purity of HMF both increase with increasing sugar concentration. Furthermore, the mass fractions of DMSO and water in the back-extraction phase gradually decrease, as does the mass fraction of the extractant in the raffinate phase. This indicates that increasing sugar concentration helps reduce solvent loss and increases the recovery rate and purity of HMF. Molecular dynamics simulations show that a large number of hydrogen bonds form between sugar and water, reducing the hydrogen bonding between water and HMF. Additionally, sugar dissolving in water increases water saturation; as sugar concentration increases, water saturation increases, reducing the dissolution of the extractant by water and thus decreasing extractant loss.

[0118] As can be seen from Examples 14 and 17-19, the purity of HMF gradually increases with the increase of the amount of sugar solution added, but the recovery rate of HMF gradually decreases. This is because the sugar solution reacts with DMSO, causing DMSO to enter the sugar solution and increasing the purity of HMF. However, the interaction between water and HMF also causes some HMF to enter the sugar solution, and the loss of HMF increases with the increase of the amount of sugar solution. Therefore, the amount of sugar solution used needs to be determined specifically based on actual production.

[0119] As can be seen from Examples 20-24, the purity of HMF gradually increases with the increase of the number of back-extraction stages, but the recovery rate of HMF decreases slightly. This is mainly because the contact time between the sugar solution and HMF increases with the increase of the number of back-extraction stages, resulting in a certain loss of HMF.

[0120] As can be seen from Examples 25-28, the method of separating and purifying 5-hydroxymethylfurfural of the present invention can separate and purify 5-hydroxymethylfurfural from the reaction solution of sugar dehydration to prepare 5-hydroxymethylfurfural using different aprotic polar solvents, with an HMF recovery rate of not less than 92.19% and an HMF purity of not less than 99.85%.

[0121] Example 29

[0122] Full-process simulation of continuous and stable production process

[0123] according to Figure 2 The process shown is a process simulation of a continuous production process in which extractant and water are recycled during the HMF separation and purification process.

[0124] Using a reaction solution containing 60 g / L HMF (hydrogen methyl furfural) and DMSO as solvent for the dehydration of sugar to prepare 5-hydroxymethylfurfural as raw material, water was added to extractor A at a volume ratio of 1:1 to the reaction solution to obtain a first mixture. This first mixture was then extracted with methyl isobutyl ketone (MOH) as the extractant to obtain an extract phase and a raffinate phase. The volume ratio of the extractant to the first mixture was 1:1, and the extraction process consisted of 5 stages. The resulting extract phase was then added to back-extractor B, and a sugar aqueous solution was added for back-extraction. The volume ratio of the sugar aqueous solution to the extract phase was 1:1, and the glucose concentration in the sugar aqueous solution was 500 g / L. The back-extraction process consisted of 5 stages, yielding a back-extracted extract phase and a back-extracted raffinate phase. The back-extracted extract phase was then subjected to vacuum evaporation and low-temperature crystallization in vacuum evaporator C to recover the extractant and obtain the HMF product. The raffinate phase and the back-extracted raffinate phase were then dehydrated in dehydrator D, and the removed water was recycled for use in the extraction and back-extraction processes. After the simulation process reached steady-state convergence, the recovery rate of HMF was 92.98%, and the purity was 99.99%. When the reaction solution for the preparation of 5-hydroxymethylfurfural from sugar dehydration using DMSO as solvent, containing HMF, was processed at a capacity of 2218 t / h, the system could operate stably, requiring only the addition of 0.29 kg / h of DMSO solvent and 17 kg / h of MIBK extractant. This indicates that the method provided by this invention can achieve stable extraction and purification of HMF, and is easily scaled up and used for continuous production.

[0125] As can be seen from Examples 1-29, the method for separating and purifying 5-hydroxymethylfurfural of the present invention, from the perspective of extraction efficiency and operation integration and optimization, effectively improves the efficiency of separating and purifying 5-hydroxymethylfurfural and the purity of the product, reduces the loss of aprotic polar solvent and extractant, and can be organically combined with the reaction system for preparing 5-hydroxymethylfurfural by sugar dehydration, which is conducive to continuous and stable scale-up production applications.

[0126] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0127] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for separating and purifying 5-hydroxymethylfurfural, characterized in that, include: (1) Mix water with an organic solution containing 5-hydroxymethylfurfural and an aprotic polar solvent to obtain a first mixture; (2) The first mixture is extracted with an extractant to obtain a raffinate phase and an extract phase containing 5-hydroxymethylfurfural; (3) The extract phase is back-extracted using a sugar solution to obtain a back-extract residue phase and a back-extract phase containing 5-hydroxymethylfurfural; (4) The back-extracted phase is subjected to evaporation and crystallization to obtain 5-hydroxymethylfurfural; In step (1), the volume ratio of the water to the organic solution is 1:1 to 9:1; The aprotic polar solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, a mixture of choline chloride and ethylene glycol in a mass ratio of 2:1, and 1-ethyl-3-methylimidazole chloride. In step (2), the extractant is at least one of methyl isobutyl ketone, ethyl acetate, and methyl propionate; The volume ratio of the extractant to the first mixture is 1:1 to 9:1; In step (3), the sugar concentration in the sugar solution is 10 g / L-1000 g / L.

2. The method according to claim 1, characterized in that, In step (3), the sugar in the sugar solution includes at least one of sucrose, glucose, fructose, maltose, trehalose, cellobiose and lactose.

3. The method according to claim 1, characterized in that, In step (3), the volume ratio of the sugar solution to the extraction phase is 1:9-9:

1.

4. The method according to claim 1, characterized in that, In step (4), the pressure for evaporating the back-extraction phase is 100Pa-2000Pa, and the temperature for crystallizing the back-extraction phase is -30℃-0℃.

5. The method according to claim 1, characterized in that, Also includes: (5) The raffinate and the back-extraction raffinate are supplied to the reaction system for sugar dehydration to prepare 5-hydroxymethylfurfural, so as to convert the sugar in the raffinate and the back-extraction raffinate into 5-hydroxymethylfurfural.

6. The method according to claim 5, characterized in that, Before feeding the raffinate and the back-extraction raffinate into the reaction system for the dehydration of sugar to prepare 5-hydroxymethylfurfural, the raffinate and the back-extraction raffinate are mixed to obtain a second mixture, and the second mixture is subjected to adsorption treatment and water content adjustment.

7. The method according to claim 6, characterized in that, The adsorption treatment is carried out using at least one of resin, diatomaceous earth, and activated clay.

8. The method according to claim 6, characterized in that, After the second mixture is subjected to adsorption treatment and water content adjustment, the water content in the second mixture is 20wt%-60wt%.

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