Purification method for 5-hydroxymethylfurfural

Abstract

A purification method for 5-hydroxymethylfurfural, comprising: providing a 5-hydroxymethylfurfural solution, which is a reaction solution generated by a dehydration reaction of hexose by means of dimethyl sulfoxide; adding a first solvent into the reaction solution, mixing same and layering to obtain a first supernatant and a first subnatant, wherein the volume ratio of the first solvent to the reaction solution is 50 / 50-150 / 10; separating the first supernatant from the first subnatant; recovering the first solvent from the first supernatant and obtaining an extract liquid, wherein the extract liquid comprises 5-hydroxymethylfurfural and dimethyl sulfoxide; and injecting the extract liquid to at least one chromatography column, and enabling a first flow cleaning agent and a second flow cleaning agent to pass through the at least one chromatography column to separate 5-hydroxymethylfurfural from dimethyl sulfoxide and obtain a flow cleaning liquid containing 5-hydroxymethylfurfural.

Description

Purification method of 5-hydroxymethylfurfural Technical Field

[0001] The present invention relates to a method for purifying 5-hydroxymethylfurfural, in particular to a method for purifying 5-hydroxymethylfurfural from a dehydration reaction medium. Background Art

[0002] 5-Hydroxymethylfurfural is a biomass-derived platform chemical, primarily prepared from six-carbon (C6) carbohydrates through hydrolysis and dehydration reactions in different systems. Its derivatives can be further developed into various resins, polymers, solvents, and fuels, and therefore have the potential to replace or substitute petrochemical materials.

[0003] The dehydration reaction of hexoses is primarily influenced by the catalyst, temperature, and solvent. Acidic catalysts are typically used in various solvents, with the solvent significantly affecting HMF conversion. Dimethyl sulfoxide (DMSO) has been shown to offer high conversion rates, but subsequent separation of HMF from the reaction solution presents another challenge. Numerous studies have attempted to separate HMF using solvent extraction (e.g., MIBK), molecular distillation, or adsorption, with adsorption being considered the most cost-effective technique.

[0004] After hexose dehydration to HMF, it often undergoes secondary hydration with water to produce levulinic acid (LA) and formic acid (FA), which then copolymerize with hexose to form humins. The presence of humins often deactivates or renders adsorbents in downstream purification processes inoperable. Therefore, removing highly water-soluble humin impurities from the dehydration reaction solution presents a new challenge in integrating adsorption technology into HMF purification. While activated carbon filtration can partially remove humins, it cannot guarantee the activity and functionality of the subsequent adsorbent. Furthermore, the heating required for distillation is not suitable for temperature-sensitive HMF. Therefore, a low-temperature method for separating HMF from byproducts could ensure that HMF can be economically and sustainably developed as a biomass-derived platform chemical.

[0005] Summary of the Invention

[0006] The present invention provides a method for purifying 5-hydroxymethylfurfural, which can remove by-products of a hexose dehydration reaction, improve the recovery rate of 5-hydroxymethylfurfural and obtain higher purity.

[0007] The present invention provides a method for purifying 5-hydroxymethylfurfural, comprising the steps of: providing a 5-hydroxymethylfurfural solution, which is a reaction solution generated by a hexose dehydration reaction using dimethyl sulfoxide; adding a first solvent to the reaction solution, mixing, and then separating the layers to obtain a first upper layer and a first lower layer, wherein the volume ratio of the first solvent to the reaction solution is 50 / 50-150 / 10; separating the first upper layer and the first lower layer; recovering the first solvent from the first upper layer to obtain an extract, wherein the extract contains 5-hydroxymethylfurfural and dimethyl sulfoxide; injecting the extract into at least one chromatography column, and passing a first wash solution and a second wash solution through the at least one chromatography column to separate the 5-hydroxymethylfurfural and dimethyl sulfoxide to obtain a wash solution containing 5-hydroxymethylfurfural.

[0008] The present invention adopts a first solvent, which can separate into layers after mixing with the reaction solution to produce an upper layer liquid containing 5-hydroxymethylfurfural and dimethyl sulfoxide, thereby separating it from the by-products in the lower layer. Moreover, by introducing the adsorption and desorption technology of chromatography, 5-hydroxymethylfurfural with higher purity can be recovered.

[0009] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, which can be implemented in accordance with the contents of the specification, and to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following specifically cites preferred embodiments and describes them in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG1 is a schematic flow diagram of a method for purifying 5-hydroxymethylfurfural according to an embodiment of the present invention.

[0011] FIG. 2A is a HMF calibration curve according to an embodiment of the present invention.

[0012] FIG. 2B is a DMSO calibration curve according to an embodiment of the present invention.

[0013] FIG. 2C is an LA calibration curve according to an embodiment of the present invention.

[0014] FIG3 is another schematic flow chart of a method for purifying 5-hydroxymethylfurfural according to an embodiment of the present invention.

[0015] FIG4A is a graph showing the activity coefficients of toluene and DMSO according to an embodiment of the present invention.

[0016] FIG. 4B is a temperature-composition phase diagram of toluene and DMSO according to an embodiment of the present invention.

[0017] 5A is a temperature (T)-composition (x, y) phase diagram of a two-component solution of toluene and dimethyl sulfoxide (DMSO) at different pressures according to an embodiment of the present invention.

[0018] FIG. 5B is an XY phase diagram of a binary component (x, y) of toluene and dimethyl sulfoxide (DMSO) at different pressures according to an embodiment of the present invention.

[0019] FIG6 is another schematic flow chart of a method for purifying 5-hydroxymethylfurfural according to an embodiment of the present invention.

[0020] FIG7A is a single column chromatogram of the first-flow washing liquid according to one embodiment of the present invention.

[0021] FIG7B is a single column chromatogram of the second washing liquid according to an embodiment of the present invention.

[0022] FIG8 is another schematic flow chart of a method for purifying 5-hydroxymethylfurfural according to an embodiment of the present invention.

[0023] FIG9 is a schematic diagram of a configuration of a simulated moving bed according to an embodiment of the present invention.

[0024] FIG10 is an HPLC / UV analysis chart of the simulated moving bed eluent according to an embodiment of the present invention.

[0025] FIG. 11 is a HPLC / UV analysis chart of a simulated moving bed eluent according to another embodiment of the present invention.

[0026] FIG12 is an HPLC / UV analysis chart of a simulated moving bed eluent according to another embodiment of the present invention.

[0027] FIG. 13A is a graph showing the activity coefficients of two components of methanol and DMSO according to an embodiment of the present invention.

[0028] FIG. 13B is a temperature-composition phase diagram of methanol and DMSO according to an embodiment of the present invention.

[0029] FIG. 14A is a temperature-composition phase diagram of a two-component structure of methanol and DMSO at different pressures according to an embodiment of the present invention.

[0030] FIG. 14B is an XY phase diagram of a two-component structure of methanol and DMSO at different pressures according to an embodiment of the present invention.

[0031] FIG15 is a schematic diagram of a configuration of a simulated moving bed according to another embodiment of the present invention.

[0032] FIG16 is an HPLC / RI analysis spectrum of a simulated moving bed product according to another embodiment of the present invention. DETAILED DESCRIPTION

[0033] As used herein, the products of chromatography and simulated moving bed chromatography can include the wash liquid, raffinate, or extract from the wash end, raffinate end, or extract end. Chromatography feeds and simulated moving bed chromatography feeds can include various solvents and samples containing the target compound, such as 5-hydroxymethylfurfural, or byproducts, such as dimethyl sulfoxide, levulinic acid, and formic acid. Examples of samples include extracts, wash liquids, and wash liquids after solvent recovery, as well as dilutions thereof.

[0034] The present invention provides a method for purifying 5-hydroxymethylfurfural (HMF). The 5-hydroxymethylfurfural purified by the present invention is derived from a dehydration reaction of a hexose, preferably a reactant produced by the dehydration reaction using dimethyl sulfoxide (DMSO). As shown in FIG1 , the purification method of the present invention includes step S610: providing a 5-hydroxymethylfurfural solution, which is a reaction solution generated by a hexose dehydration reaction using dimethyl sulfoxide; step S620: adding a first solvent to the reaction solution, mixing, and separating the layers to obtain a first upper layer and a first lower layer, wherein the volume ratio of the first solvent to the reaction solution is 50 / 50-150 / 10; step S630: separating the first upper layer and the first lower layer; step S640: recovering the first solvent from the first upper layer to obtain an extract, wherein the extract contains 5-hydroxymethylfurfural and dimethyl sulfoxide; and step S650: injecting the extract into at least one chromatography column, and passing the first and second wash streams through the at least one chromatography column to separate the 5-hydroxymethylfurfural and dimethyl sulfoxide to obtain 5-hydroxymethylfurfural.

[0035] [Preparation of 5-hydroxymethylfurfural solution]

[0036] The 5-hydroxymethylfurfural solution purified in the present embodiments, i.e., the 5-hydroxymethylfurfural solution in step S610, is a reaction solution generated by dehydrating a hexose using dimethyl sulfoxide. The hexose can be fructose or glucose, with fructose being preferred. The dehydration reaction is preferably catalyzed by a solid acid. In certain embodiments of the present invention, the reaction solution was provided by the CPC Green Energy Technology Research Institute in Taiwan, China.

[0037] Fructose undergoes dehydration to produce 5-HMF and water. Water then reacts with 5-HMF to produce levulinic acid (LA) and formic acid (FA). Levulinic acid, formic acid, and water polymerize, then copolymerize with 5-HMF to produce humin. Therefore, the reaction mixture in step S610 may contain levulinic acid, formic acid, water, and humin in addition to 5-HMF and DMSO. The levulinic acid, formic acid, water, humin, and DMSO solvent can be separated from 5-HMF in steps S620-S640 to yield 5-HMF.

[0038] Step S610 may further include a dehydration step to remove water from the reaction solution. Dehydration can be performed using, for example, molecular sieves, as shown in Example 1.

[0039] <Example 1: Dehydration of Reaction Solution>

[0040] 1.1 First filter the reaction solution through a filter membrane with a pore size of 0.22 μm;

[0041] 1.2 and then 3 angstroms The reaction solution and the molecular sieves can be dehydrated at a ratio of, for example, 10 ml:3 g, and allowed to stand at room temperature for 2 hours. Afterwards, a dehydrated reaction solution can be obtained.

[0042] The dehydration reaction liquid has a dark color, primarily derived from the colored humins. The dehydration step does not necessarily completely remove water from the reaction liquid. For example, a Kart-Fisher moisture analyzer can reveal 1-3 g% of unremoved water in the dehydrated reaction liquid. The present inventors have observed that a small amount of water can cause stratification after mixing toluene and DMSO, with the upper layer primarily consisting of toluene and dissolved DMSO and HMF. Whether the amount of water affects the stratification phenomenon and the amount of the upper layer will be discussed later in the present invention.

[0043] [Analysis method]

[0044] In this embodiment of the present invention, a high-performance liquid chromatography with ultraviolet detection (HPLC / UV) instrument was used to establish an analytical method for HMF, DMSO, and LA. This method is used to quantitatively analyze HMF, DMSO, and LA in samples containing HMF, DMSO, and LA, such as the first supernatant, the first lower layer, and the extract. The instrument and operating conditions are exemplified in Example 2.

[0045] <Example 2>:

[0046] HPLC column: Phenomenex column )5μm C18 4.6×250 mm

[0047] Wash mode and flow rate: isocratic elution, 1 ml / min.

[0048] UV wavelength: 280 nanometers (nm) for detecting HMF, 220 nm for detecting DMSO, and 266 nm for detecting LA.

[0049] Injection volume: 5 microliters (μL)

[0050] In this example, a series of standard solutions of varying concentrations were prepared for HMF, DMSO, and LA to generate calibration curves. The HMF concentrations were 0.126, 0.314, 0.628, 0.942, and 1.26 mg / mL; the DMSO concentrations were 2.646, 6.614, 9.912, 13.23, and 19.84 mg / mL; and the LA concentrations were 1.0653, 2.6634, 5.3268, and 7.9902 g / L. As shown in Figures 2A-2C , the horizontal axis represents the injected concentration (x) and the vertical axis represents the peak area (y) of the HPLC chromatogram. A calibration curve was generated, and the regression equations were: y = 28712x(HMF), y = -7.2851x(HMF), 2 +335.59x (DMSO), and y=35.43x (LA).

[0051] [Extraction of 5-hydroxymethylfurfural solution]

[0052] The first solvent of step S620 may undergo stratification after mixing with the reaction liquid. Furthermore, the first solvent may be any solvent that undergoes stratification after mixing with dimethyl sulfoxide. In an embodiment of the present invention, the first solvent is preferably toluene, and the upper layer liquid after stratification is preferably transparent in color, mainly containing toluene and DMSO and HMF dissolved therein, and may also contain LA and FA. The lower layer liquid is darker in color, mainly containing FA, water and humins. In an embodiment of the present invention, stratification is performed with a toluene / dehydration reaction liquid volume ratio (v / v) = 15 / 1, 9 / 1, 8 / 2, 5 / 5, 4 / 6, 2.5 / 7.5, 3 / 7. The operation examples of steps S620-S630 are shown in Example 2.

[0053] <Steps S620-S630: Example 2>

[0054] 2.1 Toluene and the dehydration reaction solution were mixed in v / v ratios of 15 / 1, 9 / 1, 8 / 2, 5 / 5, 4 / 6, 2.5 / 7.5, and 3 / 7, respectively, and five groups were performed for each ratio.

[0055] 2.2 After mixing, place the five groups in a constant temperature water bath at 60℃, 40℃, and 20℃, an ice bath at 0℃, a -20℃ refrigerator with an actual temperature of -22.5℃, and a -40℃ refrigerator with an actual temperature of -36.7℃ for 10 minutes respectively.

[0056] 2.3 After standing, centrifuge at 13,000 rpm for 1 minute to separate the layers to obtain the first upper layer and the first lower layer.

[0057] 2.4 Separate the first upper layer liquid and the first lower layer liquid, and record the volume and weight.

[0058] 2.5 The first upper layer was diluted 10 times with acetone and then analyzed by HPLC.

[0059] Observations show that the color of the first upper layer increases with increasing temperature and decreases with decreasing temperature. It also increases with increasing reaction liquid ratios. The higher the reaction liquid ratio, the lower the temperature required for stratification. For example, a 5 / 5 ratio requires stratification below 0°C, a 4 / 6 ratio requires stratification below -20°C, and a 7 / 3 ratio requires stratification at -40°C.

[0060] In some embodiments of the present invention, the first lower layer liquid of step S620 is further extracted. As shown in Figure 3, step S630 may further include step S710: adding a first solvent to the first lower layer liquid, mixing and separating the layers to obtain a second upper layer liquid and a second lower layer liquid, and step S720: separating the second upper layer liquid and the second lower layer liquid. The operations of steps S710-S720 are illustrated in Example 3.

[0061] <Steps S710-S720: Example 3>

[0062] 3.1 According to Example 2.1, toluene and the dehydrated reaction solution were mixed in a v / v ratio of 9 / 1. After mixing, the mixture was allowed to stand at room temperature and separated into layers to obtain a first upper layer and a first lower layer. The first upper layer and the first lower layer were separated and analyzed for HMF content.

[0063] 3.2 Take 46 μL of the first lower layer liquid, add 100, 300, 500, 700, and 900 μL of toluene respectively, mix, let it stand and separate after mixing, to obtain the second upper layer liquid and the second lower layer liquid.

[0064] 3.3 Separate the second upper liquid layer and the second lower liquid layer, and analyze the HMF content therein.

[0065] In certain embodiments of the present invention, the dehydration reaction liquid contains, for example, 66.89 g / L of HMF. In this case, the HMF contents obtained in the first upper layer and the first lower layer in step 3.1 may be, for example, 5.2 mg and 1.5 mg, respectively. The HMF content obtained in step 3.3 may be, for example, 0.4-0.9 mg, depending on the amount of toluene. This indicates that re-extraction can increase the amount of HMF recovered from the dehydration reaction liquid.

[0066] The present invention also investigates the HMF recovery rate from steps S630 and S720. The formula is as follows:

[0067] HMF recovery rate = total amount of HMF in the first upper layer liquid or the second upper layer liquid (mg) / total amount of HMF in the dehydration reaction liquid (mg)

[0068] Results showed that the HMF recovery rate in the first upper layer was higher when the extraction ratios in step S630 were 15 / 1, 9 / 1, and 8 / 2, with the ratios of 15 / 1 and 9 / 1 being more preferred. Furthermore, the HMF recovery rate also increased at higher temperatures, as shown in Table 1 below.

[0069] Table 1: HMF recovery of Example 2

[0070] The re-extraction in step S720 can further increase the total recovery rate of the reaction solution. For example, the recovery rate of 70% to 80% in Table 1 can be increased to 90%.

[0071] As mentioned above, the present invention also explores the relationship between water content and stratification. Therefore, in certain embodiments of the present invention, water is further added to the reaction solution in step S620. In these embodiments, stratification was observed using water / toluene / dehydrated reaction solution (v / v / v) ratios of 0 / 900 / 100, 50 / 850 / 100, 100 / 800 / 100, and 150 / 750 / 100. The operation is illustrated in Example 4.

[0072] <Example 4: Discussion on Water Volume and Stratification>

[0073] 4.1 Mix water, toluene, and 100 μL of the dehydrated reaction solution in a v / v / v ratio of 0 / 900 / 100, 50 / 850 / 100, 100 / 800 / 100, and 150 / 750 / 100, respectively.

[0074] 4.2 After mixing, let it stand at room temperature for 10 minutes.

[0075] 4.3 After standing, centrifuge at 13,000 rpm for 1 minute to separate the layers to obtain the first upper layer liquid and the first lower layer liquid.

[0076] 4.4 Separate the first upper layer liquid and the first lower layer liquid, and record the volume and weight.

[0077] 4.5 The first upper layer was diluted 10 times with acetone and then analyzed by HPLC.

[0078] Observations indicate that the volume of the first lower layer increases with increasing water content, while its color also lightens. Analysis also indicates that, after the addition of water, the DMSO and HMF originally dissolved in the first upper layer tend to dissolve into the first lower layer. Furthermore, analysis indicates that the HMF / DMSO weight ratio increases with increasing water content. In summary, the presence of a small amount of water allows for the extraction and separation of colored humins, polar byproducts such as LA and FA, and unreacted hexoses. The increase in the HMF / DMSO weight ratio with increasing water content indicates that a mixture of toluene and water can be used for the extraction and separation of HMF and DMSO. However, it should be noted that excessive water reduces the recovery of HMF and DMSO, and the presence of water may cause further dehydration of HMF to form LA and FA, potentially leading to the formation of humins during subsequent operations. Furthermore, the present invention is not limited to the presence of a small amount of water to induce demixing. Any second solvent that can induce demixing upon mixing with toluene and the dehydration reaction solution and can be used for the extraction and separation of HMF can be used in step S620.

[0079] [Recovery of the first solvent]

[0080] In an embodiment of the present invention, the recovery of the first solvent in step S640 preferably includes the recovery of toluene. The recovery method may vary depending on the first solvent. In a preferred embodiment of the present invention, toluene is recovered by distillation. The conditions for toluene distillation can be determined according to conventional methods, as exemplified in Example 5.

[0081] <Example 5: Toluene Recovery>

[0082] 5.1 Since the primary components of the first upper layer were toluene and DMSO, we obtained binary equilibrium data for DMSO / toluene from the literature and fitted the experimental data using the two-component Margules activity coefficient model. The fitting results are shown in Figures 4A-4B , with Figure 4A showing the activity coefficient fitting result and Figure 4B showing the temperature-composition phase diagram fitting result.

[0083] 5.2 The results of Figures 4A-4B further yield the temperature-composition phase diagram of Figure 5A and the XY phase diagram of Figure 5B. Based on the predicted results shown in Figure 5B, a vacuum distillation of 10 mmHg and a temperature below 80°C was used to separate toluene from DMSO without destroying HMF.

[0084] 5.3 After toluene separation, an extract can be obtained. The extract mainly contains DMSO and HMF. In the embodiment of the present invention, the extract is light yellow and transparent.

[0085] In addition, step S640 may further include combining the first upper layer liquid and the second upper layer liquid of step S720, and then recovering the first solvent from the combined upper layer liquid to obtain an extract.

[0086] [Separation of 5-hydroxymethylfurfural by column chromatography]

[0087] In an embodiment of the present invention, as shown in Figure 6, step S650 further includes step S651: allowing a first eluent to remove HMF from at least one chromatography column to obtain a first eluent; and step S652: allowing a second eluent to remove DMSO to obtain a second eluent. In a preferred embodiment of the present invention, the first eluent can be, for example, ethyl acetate, and the second eluent can be, for example, methanol. The chromatography column can utilize surface-modified silica filler. The chromatography column can be installed in a high-performance liquid chromatograph (HPLC) and equipped with a detector to detect the composition and elution time of the first and second eluents. An example of the operations of steps S651-S652 is shown in Example 6.

[0088] <Steps S651-S652: Example 6>

[0089] 6.1 Equipment:

[0090] Chromatography column: filled with Zeochem 60,40-63μm silica,4.6×250mm

[0091] Detector: Refractometer (Waters 410 differential refractometer)

[0092] 6.2 First and second flow detergents:

[0093] Ethyl acetate, methanol, flow rate: 1 ml / min

[0094] 6.3 Injection:

[0095] Sample: 10-fold diluted DMSO with the following solvents / 10-fold diluted hexane (as a control) / 10-fold diluted toluene (to confirm whether there is toluene in the supernatant); HMF at a concentration of 500 μg / mL

[0096] Solvent: A mixture of ethyl acetate and methanol 56 / 44 (v / v)

[0097] The results are shown in FIG7A-7B , where in step S651 , ethyl acetate causes HMF to elute at 6.75 min, while DMSO is not eluted ( FIG7A ). In step S652 , methanol causes DMSO to elute at 4.85 min, thereby separating HMF and DMSO.

[0098] [Separation of 5-hydroxymethylfurfural by simulated moving bed chromatography]

[0099] In other embodiments of the present invention, step S650 further passes the first and second eluents through multiple chromatography columns and includes step S800: separating HMF and DMSO using simulated moving bed chromatography. As shown in FIG8 , step S800 further includes steps S810 and S820. Step S810: Providing a simulated moving bed comprising a mobile phase and a stationary phase, and including at least one eluent end, a feed inlet, a raffinate end, and a purge end, as well as a first segment, a second segment, and a third segment disposed in sequence. The mobile phase flows from the at least one eluent end through the first segment, the second segment, and the third segment in the same direction relative to the simulated moving bed, and the stationary phase simulates movement in the opposite direction relative to the mobile phase. Step S820: Injecting the extract from the feed inlet into the space between the second and third sections of the simulated moving bed, and allowing 5-hydroxymethylfurfural and dimethyl sulfoxide to move with the mobile phase to the raffinate end of the third section and the wash end between the first and second sections, respectively, to separate 5-hydroxymethylfurfural and dimethyl sulfoxide.

[0100] In an embodiment of the present invention, as shown in FIG9 , the simulated moving bed 100 may include eight chromatography columns C1-C8. The chromatography columns C1-C8 may be, for example, 1 mm in inner diameter and 25 mm in length (1 cm). ID ×25cm L ), but not limited to this. Eight chromatography columns are connected in series, with columns C1-C2 forming a first section 110, columns C3-C5 forming a second section 120, and columns C6-C8 forming a third section 130. In an embodiment of the present invention, the stationary phase can be, for example, a surface-modified silica filler, which is filled in columns C1-C8, and the first and second eluents forming the mobile phase.

[0101] As shown in Figure 9, the at least one wash end further includes a first wash end D1 and a second wash end D2. The first wash end D1 is located between the first section 110 and the second section 120. A first wash agent is injected into the first wash end D1, which flows through the second section 120 and the third section 130 to remove HMF from the raffinate end R and produce a first wash liquid. The second wash end D2 is injected into the second wash end D2, which flows through the first section to remove DMSO from the wash end W and produce a second wash liquid. The operations of steps S810 and S820 are illustrated in Examples 7-1-7-3.

[0102] <Steps S810-S820: Example 7-1>

[0103] 7-1.1 Chromatography columns C1-C8: Zeochem Eight stainless steel columns were filled with 60, 40-63 μm silica and then attached to the HPLC equipment.

[0104] 7-1.2 First and second flow washing solvents: ethyl acetate and methanol.

[0105] 7-1.3 Sampling:

[0106] Sample: Dissolve the extract in ethyl acetate at a volume of 100 g / L. For example, dissolve 100 g of the extract in ethyl acetate and quantify to 1 L. Then, flow at a flow rate of 1 mL / min (Q F ) is injected into the simulated moving bed 100 from the feed port F.

[0107] First flow wash: at a flow rate of 3 mL / min (Q D ) Ethyl acetate is injected from the first flow washing end D1.

[0108] Second flow wash: at a flow rate of 6 mL / min (Q W ) Methanol is injected from the second flow washing end D2.

[0109] Under the above conditions, the operation was repeated with switching times of 5, 6, 7.5, 8.0, and 8.5 minutes, respectively. The results are shown in Figure 10 and Table 2 below. As the switching time increases, the HMF signal at the raffinate end R gradually increases, while the HMF signal at the wash end W gradually decreases. After a switching time of 7.5 minutes, the HMF signal at the wash end W is almost absent.

[0110] Table 2

[0111] In Table 2, the calculation method of HMF purity is [Formula 1]:

[0112] Among them C dried HMF is the HMF concentration (mg / mL) of the dried solution (mg / L), where the dried solution is the solution after evaporation. The HMF recovery rate (Recovery) is calculated as [Equation 2]:

[0113] where Q R is the flow rate of the first washing liquid at the raffinate end R, Q F is the flow rate of the extract solution at the feed end F, C F HMF is the HMF concentration of the extract solution at the feed end F, and Q F is 1 mL / min, C F HMFThe HMF recovery rate was 7.25 mg / L. As shown in Table 2, HMF recovery increased with increasing switching time, but purity decreased. This is presumably due to a small amount of DMSO remaining in the first-stream wash, which was not removed during the concentration process and affected HMF purity. HMF Nos. 1-3 exhibited higher purity.

[0114] <Example 7-2>

[0115] The difference between Example 7-2 and Example 7-1 is that the ethyl acetate solution of the extract was injected into the simulated moving bed 100 from feed port F at an increased flow rate of 2 mL / min, and the switching times were 5.5, 6.5, 7.5, and 8.5 min. The results are shown in Figure 11 and Table 3 below. As the switching time increased, the HMF signal at the raffinate end R gradually increased, while the HMF signal at the wash end W gradually decreased. After a switching time of 7.5 minutes, the HMF signal at the wash end W was almost absent. However, after a switching time of 6.5 minutes, DMSO signal appeared in the first wash stream from the raffinate end R. This indicates that the column was not effectively cleaned during the cleaning phase, resulting in a large amount of DMSO remaining in the column, affecting the separation and purification process.

[0116] Table 3

[0117] The calculation method of HMF purity and recovery rate in Table 3 is the same as [Formula 1] and [Formula 2], except that Q in 7-2 is shown as an example. F 2mL / min, C F HMF As shown in Table 3, the HMF recovery rate increased with the increase of the switching time. However, in terms of purity, high-purity HMF was only obtained at a switching time of 5.5 minutes (No. 6). At the remaining switching times, the purity decreased due to the large amount of residual DMSO.

[0118] <Example 7-3>

[0119] Example 7-3 differs from Example 7-1 and Example 7-2 in that the ethyl acetate solution of the extract is injected into the simulated moving bed 100 from feed port F at a reduced flow rate of 0.2 mL / min or 0.1 mL / min, while the extract volume is increased proportionally to 500 g / L and 1120 g / L, respectively. The switching time is 7.5 minutes, and the results are compared with those of Example 3. As shown in Figure 12 and Table 4 below, all three groups exhibit almost no HMF signal at the wash end W. However, a trace amount of DMSO signal appears at an extract concentration of 1120 g / L. This indicates that under the conditions of Example 11, DMSO remains in the column, leaving residual DMSO in the first wash stream at the raffinate end R. Based on these results, the maximum concentration that can be injected into the simulated moving bed 100 is 500 g / L.

[0120] Table 4

[0121] The calculation method of HMF purity and recovery rate in Table 4 is the same as [Formula 1] and [Formula 2], except that Q in 7-3 is shown as an example. F The corresponding C F HMF As shown in Table 4, the recovery rates of the different concentrations were not significantly different, but in terms of purity, DMSO No. 11 affected the purity of HMF.

[0122] [Recovery of the second-stream detergent]

[0123] As shown in FIG6 , this embodiment of the present invention may further include step S653: recovering a first stream wash solvent from the first stream wash liquid, and recovering a second stream wash solvent from the second stream wash liquid. In a preferred embodiment of the present invention, for example, ethyl acetate is recovered by evaporation, and methanol is recovered by distillation. The conditions for methanol distillation can be determined according to conventional methods, as exemplified in Example 8.

[0124] <Example 8: Methanol Recovery>

[0125] 8.1 Since the main components of the second-stream wash solution were methanol and DMSO, we obtained binary equilibrium data for DMSO / methanol from the literature and fitted the experimental data using the binary Margules activity coefficient model. The fitting results are shown in Figures 13A-13B, where Figure 13A shows the activity coefficient fitting result and Figure 13B shows the temperature-composition phase diagram fitting result.

[0126] 8.2 The results in Figures 13A-13B provide the temperature-composition phase diagram in Figure 14A and the XY phase diagram in Figure 14B. Based on the predicted results shown in Figure 14B, methanol and DMSO can be separated by atmospheric distillation.

[0127] [5-Hydroxymethylfurfural crystals are formed]

[0128] In preferred embodiments of the present invention, purification of HMF further includes crystallization. Crude HMF crystals can be formed under low humidity and room temperature conditions. Furthermore, HMF crystallization can be completed by evaporating ethyl acetate in step S653, followed by concentration and drying. Certain embodiments of the present invention utilize low-temperature, reduced-pressure concentration. An example of the HMF crystallization process is shown in Example 9.

[0129] <Example 9: HMF Crystallization (1)>

[0130] 9.1 Obtain the first-flow washes 2, 3, 6, and 10 from Example 7-1-7-3 and concentrate them at 50°C and 610 mmHg for 10 minutes to 1 hour. The concentrated first-flow washes are light orange to light yellow solutions.

[0131] 9.2 Place the concentrated HMF sample into a 50 mL centrifuge tube containing silica gel desiccant, seal it, and place it in a -20°C refrigerator overnight to obtain orange-yellow crystals.

[0132] The temperature at which HMF crystals can be completely melted (T m ) is generally 31-34°C. If the crystals are impure, such as if they contain other impurities, their melting temperature may deviate from the Tm value. In this example, the orange-yellow crystals at 9.2°C were placed in a constant-temperature water bath and their melting point was measured by gradually increasing the temperature. HMF crystals can also be dissolved in a solvent and analyzed for LA content by HPLC / UV. The results are shown in Table 5 below.

[0133] Table 5

[0134] In order to improve the purity of HMF crystals, in some embodiments of the present invention, HMF is crystallized in methyl tert-butyl ether (MTBE), as shown in Example 10.

[0135] <Example 10: HMF Crystallization (2)>

[0136] 10.1 Take 500 μL each of HMF from Example 7-1, Nos. 2 and 3 (or, HMF-containing samples prepared under the simulated moving bed conditions of Example 7-1, Nos. 2 and 3), add 2 mL of MTBE to each, mix thoroughly, ultrasonically shake for 30 seconds, and place in a -40°C freezer for crystallization. The HMF used is preferably purified HMF, such as an HMF concentrate obtained by low-temperature, reduced-pressure concentration. The HMF-containing samples from Nos. 2 and 3 crystallize as a light yellow solid and a dark orange solid, respectively.

[0137] 10.2 After crystallization, pour off the MTBE and wash with ice-cold hexane. Then, scoop out the crystalline solid and store it in a desiccant.

[0138] 10.3 The melting point was measured according to the above method. The results are shown in Table 6 below.

[0139] Table 6

[0140] As shown in Table 6, the use of MTBE can increase the Tm of HMF crystallization to the range of 31-34°C, indicating that its purity has been improved.

[0141] [Separation of levulinic acid by simulated moving bed chromatography]

[0142] In step S620, the upper layer after separation may contain LA and FA in addition to DMSO and HMF. LA and FA may not have had the opportunity to be separated in steps S630-S650 and therefore remain in the HMF-containing sample, affecting the purity of the HMF crystals. Therefore, in certain embodiments of the present invention, the purification of HMF may include the separation of LA. Example 11 illustrates the separation of LA using simulated mobility chromatography, but the separation of LA is not limited to this method.

[0143] <Example 11>

[0144] As shown in FIG15 , the simulated moving bed 200 may include eight packed columns C11-C18. The packed columns C11-C8 may be, for example, 25 mm ID ×150mm L The eight chromatography columns are connected in series, with packed columns C11-C12 forming the first section 210, packed columns C13-C15 forming the second section 220, and packed columns C16-C18 forming the third section 230. The feed port F' is located between the second section 220 and the third section 230, the wash port D is located in the first section 210, the extraction port E' is located between the first section 210 and the second section 220, and the raffinate port R' is located in the third section 230. In an embodiment of the present invention, the stationary phase may be, for example, an ion exchange resin and is packed in columns C11-C18. The mobile phase may be deionized water.

[0145] 11.1 Packing columns C11-C18: Eight stainless steel columns were packed with Dowex 50wx8 resin (H-form, 100 μm) and then attached to the HPLC equipment.

[0146] 11.2 Sample: The HMF-containing sample obtained from step S650 may be, for example, the first-stream washing liquid or the first-stream washing liquid after the first-stream washing agent is recovered.

[0147] 11.3 The sample is injected into the simulated moving bed 200 from the feed port F' at a flow rate of 2 mL / min. The deionized water wash is injected into the simulated moving bed 200 from the wash end D' at a flow rate of 12.0 mL / min. The raffinate containing the weakly retentive LA flows out from the raffinate end R' at a flow rate of, for example, 10 mL / min, and the extract containing the strongly retentive HMF flows out from the extraction end E' at a flow rate of, for example, 4.0 mL / min.

[0148] Under the above conditions, the process was continued with switching times of 9, 10-12, 12.5, and 13.5 minutes, respectively. RI analysis was performed for the LA and HMF contents in the raffinate and extract. The results are shown in Figure 16 and Table 7 below. When the switching time was 11-12 minutes, HMF of higher purity was obtained from the extract end E', while the purity of LA from the raffinate end R' also improved. At a switching time of 12.5 minutes, 100% purity LA and HMF were obtained from the extract end E' and the raffinate end R', respectively, demonstrating the effective separation of LA and HMF by simulated moving bed chromatography. Once the switching time exceeded 13.5 minutes, the purity of LA and HMF began to decline.

[0149] Table 7

[0150] In summary, through steps S610-S630, the present invention separates HMF from dehydration reaction byproducts and removes humins that could interfere with adsorption and desorption, ensuring the execution of S650 and allowing for the recovery of more HMF under appropriate conditions. Chromatographic techniques or simulated moving bed chromatography, under appropriate conditions, can effectively recover HMF while ensuring purity.

[0151] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with the present profession can make slight changes or modifications to equivalent embodiments of equivalent changes using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for purifying 5-hydroxymethylfurfural, characterized in that: Includes steps: Providing a 5-hydroxymethylfurfural solution, wherein the 5-hydroxymethylfurfural solution is a reaction solution generated by using dimethyl sulfoxide to perform a dehydration reaction on hexose; Adding a first solvent to the reaction liquid, mixing and layering to obtain a first upper layer liquid and a first lower layer liquid; wherein the volume ratio of the first solvent to the reaction liquid is 50 / 50-150 / 10; Separating the first upper layer liquid and the first lower layer liquid; Recover the first solvent from the first upper liquid to obtain an extract, wherein the extract contains 5-hydroxymethylfurfural and dimethyl sulfoxide; The extract is injected into at least one chromatography column, and the first washing agent and the second washing agent are passed through the at least one chromatography column to separate 5-hydroxymethylfurfural and dimethyl sulfoxide and obtain a washing agent containing 5-hydroxymethylfurfural.

2. The method for purifying 5-hydroxymethylfurfural as claimed in claim 1, characterized in that: The step of layering further includes allowing the mixed solution to stand at a temperature of 0-60°C.

3. The method for purifying 5-hydroxymethylfurfural as claimed in claim 1, characterized in that: The purification method further comprises the steps of: adding the first solvent and the second solvent to the reaction solution; the volume of the second solvent is smaller than the volume of the first solvent, and the volume ratio of the second solvent to the reaction solution is smaller than 1.

4. The method for purifying 5-hydroxymethylfurfural as claimed in claim 3, characterized in that: The first solvent is toluene, and the second solvent is water.

5. The method for purifying 5-hydroxymethylfurfural as claimed in claim 1, characterized in that: The reaction solution contains 1-3% water.

6. The method for purifying 5-hydroxymethylfurfural as claimed in claim 1, characterized in that: The step of separating the first upper layer liquid and the first lower layer liquid further comprises: Adding the first solvent to the first lower layer liquid, mixing and separating the mixture to obtain a second upper layer liquid and a second lower layer liquid; and The second upper layer liquid and the second lower layer liquid are separated.

7. The method for purifying 5-hydroxymethylfurfural as claimed in claim 6, characterized in that: The purification method further comprises the steps of: The first upper layer liquid and the second upper layer liquid are combined, and the first solvent is recovered from the combined upper layer liquid to obtain the extract.

8. The method for purifying 5-hydroxymethylfurfural as claimed in claim 1, characterized in that: The step of passing the first eluent and the second eluent through the at least one chromatography column further comprises: Allowing the first-flow washing agent to carry out 5-hydroxymethylfurfural from the at least one chromatography column and obtain a first-flow washing liquid; and The second wash is allowed to carry out the dimethyl sulfoxide and obtain a second wash liquid.

9. The method for purifying 5-hydroxymethylfurfural as claimed in claim 8, characterized in that: The purification method further comprises the steps of recovering the first flow washing agent from the first flow washing liquid, and recovering the second flow washing agent from the second flow washing liquid.

10. The method for purifying 5-hydroxymethylfurfural according to claim 1, characterized in that: The first eluent is ethyl acetate, and the second eluent is methanol.

11. The method for purifying 5-hydroxymethylfurfural according to claim 1, characterized in that: The purification method further comprises the step of: allowing 5-hydroxymethylfurfural to form crystals in a low-humidity environment, and the melting point of the crystals is greater than 28°C.

12. The method for purifying 5-hydroxymethylfurfural according to claim 11, characterized in that: The melting point of the crystals is 31-34°C.

13. The method for purifying 5-hydroxymethylfurfural according to claim 1, characterized in that: The step of separating 5-hydroxymethylfurfural and dimethyl sulfoxide further comprises separation by simulated moving bed chromatography.

14. The method for purifying 5-hydroxymethylfurfural according to claim 13, characterized in that: The simulated moving bed chromatography method comprises: (i) providing a simulated moving bed; the simulated moving bed is composed of a mobile phase and a stationary phase, and comprises at least a wash end, a feed inlet, a raffinate end and a wash end, and a first section, a second section and a third section arranged in sequence, wherein the mobile phase flows from the at least one wash end through the first section, the second section and the third section in the same direction relative to the simulated moving bed, and the stationary phase simulates movement in the opposite direction relative to the mobile phase; (ii) injecting the extract from the feed inlet into the space between the second section and the third section of the simulated moving bed, and allowing 5-hydroxymethylfurfural and dimethyl sulfoxide to move with the mobile phase to the raffinate end of the third section and the wash end between the first section and the second section, respectively, to separate 5-hydroxymethylfurfural and dimethyl sulfoxide.

15. The method for purifying 5-hydroxymethylfurfural according to claim 14, characterized in that: The first wash agent and the second wash agent constitute the mobile phase, and the at least one wash end includes a first wash end and a second wash end; the first wash agent flows from the first wash end between the first section and the second section through the second section and the third section to remove 5-hydroxymethylfurfural from the raffinate end and obtain a first wash liquid; the second wash agent flows from the second wash end of the first section through the first section to remove dimethyl sulfoxide from the cleaning end and obtain a second wash liquid.

16. The method for purifying 5-hydroxymethylfurfural according to claim 14, characterized in that: The simulated moving bed chromatography method further comprises: diluting the extract and then performing step (ii).

17. The method for purifying 5-hydroxymethylfurfural according to claim 16, characterized in that: The step of diluting the extract further comprises dissolving the extract in the first washing agent at a concentration of 100-500 g / L.

18. The method for purifying 5-hydroxymethylfurfural according to claim 17, characterized in that: The separation conditions of the simulated moving bed include: The flow rate of the first washing agent is 3 mL / min, and the flow rate of the second washing agent is 6 mL / min; the flow rate of the extract diluent at the feed port is 0.2-2 mL / min, and the switching time of the simulated moving bed is more than 5 minutes to 7.5 minutes.

19. The method for purifying 5-hydroxymethylfurfural according to claim 1, characterized in that: The 5-hydroxymethylfurfural solution contains levulinic acid, and the purification method further comprises the steps of: 5-Hydroxymethylfurfural and levulinic acid are separated from the washing liquid containing 5-Hydroxymethylfurfural.

20. The method for purifying 5-hydroxymethylfurfural according to claim 19, characterized in that: The step of separating 5-hydroxymethylfurfural and levulinic acid from the washing liquid containing 5-hydroxymethylfurfural further comprises separating by simulated moving bed chromatography, comprising: (iii) providing a simulated moving bed; the simulated moving bed is composed of a mobile phase and a stationary phase, and includes a flow washing end, a feed inlet, a raffinate end and an extraction end, and a first section, a second section and a stationary phase arranged in sequence; The mobile phase flows from the wash end through the first section, the second section and the third section in the same direction relative to the simulated moving bed, and the stationary phase simulates movement in the opposite direction relative to the mobile phase; (iv) injecting the washing liquid containing 5-hydroxymethylfurfural from the feed inlet between the second section and the third section of the simulated moving bed, allowing 5-hydroxymethylfurfural to move with the stationary phase to the extraction end between the first section and the second section, and allowing levulinic acid to move with the mobile phase to the raffinate end of the third section, so as to separate and purify 5-hydroxymethylfurfural.

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