Method for separating and purifying bis-(5-formyl furfuryl) ether from 5-hydroxymethylfurfural crude product

Abstract

The invention discloses a method for separating and purifying bis-(5-formyl furfuryl) ether from a 5-hydroxymethylfurfural crude product. The method comprises the following steps: adding water into a 5-hydroxymethylfurfural crude product to dissolve 5-hydroxymethylfurfural in water, and filtering to obtain a bis-(5-formyl furfuryl) ether crude product; and adding an organic solvent into the bis-(5-formyl furfuryl) ether crude product to dissolve the bis-(5-formyl furfuryl) ether crude product, and carrying out activated carbon decoloration, cooling crystallization, filtration, washing and drying to obtain the bis-(5-formyl furfuryl) ether crystal. According to the method disclosed by the invention, the 5-hydroxymethylfurfural and the bis-(5-formyl furfuryl) ether are effectively separated, the bis-(5-formyl furfuryl) ether separated and purified by the method is relatively high in purity, the process is green and environment-friendly, the operation is convenient, and the separation and reapplication of the 5-hydroxymethylfurfural and the bis-(5-formyl furfuryl) ether are realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of furan bio-based products, and more specifically, relates to a method for separating and purifying bis-(5-formylfurfuryl) ether (abbreviated as "OBMF") from a crude 5-hydroxymethylfurfural (abbreviated as "HMF"). Background Art

[0002] Bis-(5-formylfurfuryl) ether is a bio-based intermediate with an aromatic furan structure. It is a platform compound with high technical content, great application potential, and clean and environmentally friendly. Bis-(5-formylfurfuryl) ether exists in many plants. People have isolated this compound from hawthorn, honeysuckle, ganoderma lucidum, and chuanxiong. Pharmacological experiments have shown that it has antiviral, antioxidant and tuberculosis inhibitory effects. However, there are few studies on its synthesis. Larousse C. et al. reported that 5-hydroxymethylfurfural was catalytically dehydrated at high temperature (155°C) in DMSO to generate bis-(5-formylfurfuryl) ether. There are also reports that bis-(5-formylfurfuryl) ether was prepared using sucrose as the starting material through three simple reactions: acid dehydration, halogenation, hydrolysis, and room temperature dehydration.

[0003] The bis-(5-formylfurfuryl) ether obtained by the above-reported method is not only of high purity, but also with the realization of the industrialization of 5-hydroxymethylfurfural, the output of bis-(5-formylfurfuryl) ether will increase dramatically, making it have the prospect of industrialization.

[0004] During the synthesis and storage of 5-hydroxymethylfurfural crude products, due to the presence of acid and water, its etherification product, i.e., bis-(5-formylfurfuryl) ether, is easily generated. Therefore, it is necessary to treat such 5-hydroxymethylfurfural crude products to achieve separation of 5-hydroxymethylfurfural and bis-(5-formylfurfuryl) ether and their reuse. Summary of the invention

[0005] Technical issues

[0006] The present invention is designed to solve the above-mentioned problems in the prior art. The purpose of the present invention is to provide a method for separating and purifying bis-(5-formylfurfuryl) ether from a crude 5-hydroxymethylfurfural product. The bis-(5-formylfurfuryl) ether separated and purified by the method has high purity, and the process is green and environmentally friendly, easy to operate, and suitable for industrial application.

[0007] Technical Solution

[0008] In order to achieve the above object, according to the present invention, the present invention provides a method for separating and purifying bis-(5-formylfurfuryl) ether from a crude 5-hydroxymethylfurfural product, the method comprising the following steps:

[0009] Step 1: adding water to the crude 5-hydroxymethylfurfural product, dissolving the 5-hydroxymethylfurfural in the water at a temperature of 35° C. to 75° C., and filtering to obtain a crude bis-(5-formylfurfuryl) ether product;

[0010] Step 2: adding an organic solvent to the crude bis-(5-formylfurfuryl) ether obtained above, dissolving the bis-(5-formylfurfuryl) ether in the solvent at a temperature of 30° C. to 80° C., and then adding activated carbon for activated carbon decolorization to obtain a decolorized bis-(5-formylfurfuryl) ether solution; then cooling the solution for crystallization, filtering, washing, and drying to obtain bis-(5-formylfurfuryl) ether crystals, wherein the organic solvent is selected from methanol, ethanol, isopropanol, methyl acetate, ethyl acetate, and propyl acetate.

[0011] Beneficial Effects

[0012] The method for separating and purifying bis-(5-formylfurfuryl) ether from a crude 5-hydroxymethylfurfural product provided by the present invention can effectively separate 5-hydroxymethylfurfural from bis-(5-formylfurfuryl) ether. The bis-(5-formylfurfuryl) ether separated and purified by the method has high purity, and the process is green and environmentally friendly, and the operation is convenient. The separation and reuse of 5-hydroxymethylfurfural and bis-(5-formylfurfuryl) ether is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of this specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention.

[0014] In the attached picture:

[0015] Figure 1 is a process flow chart of a method for separating and purifying bis-(5-formylfurfuryl) ether from a crude 5-hydroxymethylfurfural product according to an embodiment of the present invention;

[0016] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of the OBMF separated and purified in Example 1;

[0017] Figure 3 This is a trend chart showing the change in purity of OBMF crystals obtained by separation and purification according to Examples 1 to 13 as a function of the number of times the crystallization mother solution is used;

[0018] Figure 4 This is the mass spectrum of the by-products produced when OBMF was purified using alcohols as solvents. DETAILED DESCRIPTION

[0019] Hereinafter, the method for separating and purifying bis-(5-formylfurfuryl) ether from a crude 5-hydroxymethylfurfural product of the present invention will be described in more detail to help understand the present invention.

[0020] Figure 1 It is a process flow chart of a method for separating and purifying bis-(5-formylfurfuryl) ether from a crude 5-hydroxymethylfurfural product according to an embodiment of the present invention. According to one embodiment of the present invention, the present invention provides a method for separating and purifying bis-(5-formylfurfuryl) ether from a crude 5-hydroxymethylfurfural product, wherein the crude 5-hydroxymethylfurfural product is an etherification product of 5-hydroxymethylfurfural that is easily generated due to the presence of acid and water during the synthesis and storage of 5-hydroxymethylfurfural, i.e., bis-(5-formylfurfuryl) ether, for example, in the crude 5-hydroxymethylfurfural product, by weight, the content of bis-(5-formylfurfuryl) ether is 5% to 15%, the content of 5-hydroxymethylfurfural is 80% to 90%, and the content of other impurities is 1% to 5%.

[0021] According to one embodiment of the present invention, in step 1, water is added to the crude 5-hydroxymethylfurfural product, and the 5-hydroxymethylfurfural is dissolved in the water at a temperature of 35°C to 75°C, and the crude bis-(5-formylfurfuryl) ether is obtained by filtration.

[0022] Here, the different solubility characteristics of HMF and OBMF in water are mainly used, among which HMF is easily soluble in water, while OBMF is difficult to dissolve in water. HMF is dissolved in water, and the filter cake obtained by filtration is the crude OBMF product. Among them, the obtained HMF solution can be subsequently recovered by evaporating water or extraction, or it can be directly used for reaction to generate subsequent derivatives.

[0023] In step 1, the water used may be pure water or deionized water, such as laboratory grade II pure water or ultrapure water; the amount of water used may be such that the weight ratio of water to the HMF crude product is 0.5:1 to 5:1. For example, the water used may be deionized water, and the amount of deionized water used may be such that the weight ratio of deionized water to the HMF crude product is 2:1.

[0024] In step 1, stirring may be performed during the dissolution process, and the stirring method may be magnetic stirring or mechanical stirring, the stirring speed may be 100 rpm to 500 rpm, and the stirring time may be 20 to 60 min. For example, at a temperature of 55±5°C, the stirring method is mechanical stirring, the stirring speed is 400±10 rpm, and the stirring time is 40±2 min.

[0025] According to one embodiment of the present invention, in step 2, an organic solvent is added to the crude bis-(5-formylfurfuryl) ether obtained above, and the bis-(5-formylfurfuryl) ether is dissolved in the solvent at a temperature of 30°C to 80°C, and then activated carbon is added for activated carbon decolorization to obtain a decolorized bis-(5-formylfurfuryl) ether solution; then the solution is cooled and crystallized, and filtered, washed and dried to obtain bis-(5-formylfurfuryl) ether crystals, wherein the organic solvent is selected from methanol, ethanol, isopropanol, methyl acetate, ethyl acetate and propyl acetate.

[0026] The organic solvent is selected from methanol, ethanol, isopropanol, methyl acetate, ethyl acetate and propyl acetate, and the mass fraction of the crude OBMF product is 1% to 20% relative to the total amount of the crude OBMF product and the organic solvent.

[0027] Preferably, the organic solvent is ethyl acetate, and the mass fraction of the crude OBMF product is 1% to 20%, more preferably 4% to 8%, relative to the total amount of the crude OBMF product and ethyl acetate.

[0028] The activated carbon for decolorization can be wood activated carbon, fruit shell (fruit core) activated carbon or coal activated carbon, and the amount of the activated carbon is 0.5% to 5% of the weight of the crude OBMF product; preferably, the activated carbon for decolorization is fruit shell (fruit core) activated carbon, and the amount of the activated carbon is 1% to 2% of the weight of the crude OBMF product. Preferably, the particle size of the activated carbon is 0.2 mm to 2 mm, and more preferably, the particle size of the activated carbon is 0.2 mm to 0.4 mm.

[0029] The dissolution and decolorization of bis-(5-formylfurfuryl) ether are carried out at a temperature of 30°C to 80°C. Stirring can be performed during the dissolution and decolorization process. The stirring method can be magnetic stirring or mechanical stirring. The stirring speed can be 100rpm to 500rpm. Stirring helps dissolve the crude OBMF product. The stirring time during decolorization can be 20 to 60min. For example, at a temperature of 50±5°C, the stirring method is mechanical stirring, the stirring speed is 350±10rpm, and the stirring time during decolorization is 35±2min.

[0030] After filtering, such as suction filtration to remove the activated carbon, a decolorized bis-(5-formylfurfuryl) ether solution is obtained, and the solution is cooled and crystallized. The crystallization method is mechanical stirring crystallization or static crystallization. The crystallization temperature is -10°C to 20°C and the crystallization time is 10 to 60 minutes. Preferably, the crystallization method is static crystallization, the crystallization temperature is 5±2°C, and the crystallization time is 25 minutes.

[0031] After crystallization, filtration is performed to obtain wet crystals and crystallization mother liquor. Figure 1As shown, the obtained crystallization mother liquor can be used in step 2 as an organic solvent for dissolving the crude bis-(5-formylfurfuryl) ether. Optionally, the crystallization mother liquor can be used 2 to 12 times, preferably, the crystallization mother liquor can be used 8 times. When the crystallization mother liquor is no longer recycled, the solvent and the solute therein can be recovered.

[0032] After washing and drying, bis-(5-formylfurfuryl) ether crystals are obtained, wherein the solvent for washing the crystals can be deionized water, methanol, ethanol, isopropanol or ethyl acetate, and the amount of the washing solvent is 5 to 50 g per 100 g of OBMF crystals; preferably, the solvent for washing the crystals is deionized water, and the amount used is 20 to 40 g per 100 g of OBMF crystals.

[0033] The drying can be freeze drying, vacuum drying, oven drying or air drying at room temperature; the drying time is 20 to 120 minutes, and the drying temperature is -30°C to 80°C. Preferably, the drying method is vacuum drying, the drying time is 90 minutes, and the drying temperature is 30°C.

[0034] Example

[0035] Below, the method for separating and purifying bis-(5-formylfurfuryl) ether from 5-hydroxymethylfurfural crude product of the present invention is more specifically described by examples, but the protection scope of the present invention is not limited to these examples.

[0036] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources. Unless otherwise specified, the analytical methods and analytical instruments used were conventional methods and the settings recommended by the manufacturer.

[0037] In the following examples, the purity of OBMF was analyzed by Agilent's 8860 gas chromatograph, and the purity was qualitatively determined by peak area percentage. The moisture content was determined by Shanghai Hegong's Karl Fischer moisture analyzer AKF-1N.

[0038] Example 1

[0039] Step 1: Weigh 100 g of HMF crude product (of which HMF accounts for 82%, OBMF accounts for 14.5%, and other impurities account for 3.5%), mix it with 200 g of deionized water, start mechanical stirring at a speed of 400 rpm, and heat to 55 ° C. After 40 minutes, stop stirring and temperature control; filter the mixed solution to obtain a crude OBMF product weighing 18.7 g.

[0040] Step 2: 18.7 g of the crude OBMF obtained above was mixed with 374 g of ethyl acetate, and mechanical stirring was started at a speed of 350 rpm. The temperature was raised to 50° C. After the crude OBMF was completely dissolved, 0.5 g of fruit shell (fruit core) activated carbon with a particle size of 0.2 mm-0.4 mm was added, and the stirring state was maintained for 35 minutes, and then the stirring and temperature control were stopped; the activated carbon was filtered out while hot to obtain a filtrate, which was placed in a cold bath at 5° C. for crystallization for 25 minutes.

[0041] The above crystallization liquid was filtered to obtain wet crystals, and the crystallization mother liquor was collected. The crystals were then washed with 3 g of deionized water and vacuum dried. The optimal negative pressure was maintained at 30° C. and dried for 90 min to obtain 8.6 g of OBMF product (yield 59.3%). The product was subjected to gas chromatography purity analysis and Karl Fischer water determination. The results are shown in Table 1 below.

[0042] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of OBMF obtained in Example 1.

[0043] Example 2-Example 13

[0044] Example 1 was repeated to carry out Examples 2-13, except that in step 2, the crystallization mother liquor collected in the previous example was used as an organic solvent to dissolve the crude bis-(5-formylfurfuryl) ether. The data of the obtained OBMF product are shown in Table 1 below. Figure 3 The graph shows the change trend of the purity of the OBMF crystals obtained by separation and purification according to Examples 1 to 13 as a function of the number of times the crystallization mother solution is reused. It can be seen that the number of times the crystallization mother solution can be reused can be 2 to 12 times, with the optimal number being 8 times.

[0045] Table 1: GC purity % and moisture content of OBMF crystals prepared in Examples 1-13

[0046]

[0047] Embodiment 14

[0048] Step 1: Weigh 600 g of HMF crude product (of which HMF accounts for 82%, OBMF accounts for 14.5%, and other impurities account for 3.5%), mix it with 1200 g of deionized water, start mechanical stirring at a speed of 400 rpm, and heat to 55 ° C. After 40 minutes, stop stirring and temperature control; filter the above mixed solution to obtain a crude OBMF product weighing 110 g.

[0049] Step 2: 110 g of the crude OBMF product obtained above was mixed with 2250 g of ethyl acetate, and mechanical stirring was started at a speed of 350 rpm. The temperature was raised to 50° C. After the crude OBMF product was completely dissolved, the mixed solution was divided into 6 parts, and 0.092 g, 0.183 g, 0.367 g, 0.550 g, 0.732 g, and 0.915 g of fruit shell (fruit core) activated carbon with a particle size of 0.2 mm-0.4 mm were added respectively, and the stirring state was maintained for 35 minutes, and then the stirring and temperature control were stopped; the activated carbon was filtered out while hot to obtain a filtrate, which was placed in a cold bath at 5° C. for crystallization for 25 minutes.

[0050] The above crystallization liquid was filtered to obtain wet crystals, and then the crystals were washed with 3g of deionized water and then vacuum dried. The optimal negative pressure was maintained at 30°C and dried for 90min to obtain 8.68g, 8.65g, 8.63g, 8.45g, 8.28g, and 8.01g of OBMF finished products, respectively. The color of the OBMF finished products after the activated carbon treatment of the fruit shell (fruit core) in each ratio was observed, and the data are shown in Tables 2 and 3 below.

[0051] Example 15-Example 16

[0052] Example 14 was repeated to carry out Examples 15 and 16, except that in step 2, wood activated carbon (particle size 0.2 mm-0.4 mm) and coal activated carbon (particle size 0.2 mm-0.4 mm) were used instead of the fruit shell (fruit core) activated carbon in Example 14, and the quality and color of the obtained OBMF finished products were shown in Tables 2 and 3 below.

[0053] Table 2

[0054]

[0055] Table 3

[0056]

[0057] Conclusion: Table 2 represents the yield of OBMF products after being treated with different activated carbons in different proportions, and Table 3 represents the color, i.e., the decolorization effect, of OBMF products after being treated with different activated carbons in different proportions.

[0058] 1) Comparing the quality of OBMF products after treatment with activated carbon in different proportions, coal-based activated carbon has the highest OBMF yield.

[0059] 2) Comparing the colors of OBMF products after treatment with different activated carbons, it was found that the color of OBMF treated with fruit shell (core) activated carbon was better.

[0060] 3) In view of the fact that the decolorization effect of coal-based activated carbon cannot reach the decolorization effect of fruit shell (fruit core) activated carbon in the range of 0.5%-5.0% activated carbon ratio, and the wood-based activated carbon is inferior to the other two activated carbons in terms of OBMF yield and decolorization effect, the final preferred one is fruit shell (fruit core) activated carbon, and the addition ratio is 1%-2%. Within this ratio range, the OBMF yield is high and the finished product color is good.

[0061] Embodiment 17

[0062] Step 1: Weigh 400 g of HMF crude product (of which HMF accounts for 82%, OBMF accounts for 14.5%, and other impurities account for 3.5%), mix it with 800 g of deionized water, start mechanical stirring at a speed of 400 rpm, and heat to 55 ° C. After 40 minutes, stop stirring and temperature control; filter the above mixed solution to obtain OBMF crude product, weighing 74 g.

[0063] Step 2: 74 g of the crude OBMF obtained above was divided into four parts, and dissolved in 374 g of methanol, ethanol, isopropanol and ethyl acetate respectively under mechanical stirring at 50°C and 350 rpm, and 0.5 g of fruit shell (fruit core) activated carbon (particle size 0.2 mm-0.4 mm) was added to each. After 35 minutes, stirring and temperature control were stopped; the activated carbon was filtered out while hot to obtain the filtrate, which was placed in a cold bath at 5°C for 25 minutes to crystallize.

[0064] The above crystallization liquid was filtered to obtain wet crystals, and then the crystals were washed with 3g of deionized water and vacuum dried. The optimal negative pressure was maintained at 30°C for 90min to obtain 8.65g, 8.66g, 8.65g, and 8.67g of OBMF finished products, respectively. The purity was analyzed by gas chromatography, and the results were as follows:

[0065] Type of solvent used Methanol Ethanol Isopropyl alcohol Ethyl acetate Finished product GC purity % 92.82 93.14 91.57 98.5

[0066] Through mass spectrometry, it was found that OBMF easily generates some aldol condensation by-products in methanol, ethanol, and isopropanol solvents, resulting in a decrease in its purity. Taking methanol as an example, the reaction equation is as follows:

[0067]

[0068] Figure 4 This is the mass spectrum of the by-products produced by purifying OBMF using alcohols as solvents. In methanol, the mass spectrum of the two types of products produced by the reaction of OBMF and methanol.

[0069] Comparative Example 1

[0070] Step 1: Weigh 100 g of HMF crude product (of which HMF accounts for 82%, OBMF accounts for 14.5%, and other impurities account for 3.5%), mix it with 200 g of deionized water, start mechanical stirring at a speed of 400 rpm, and heat to 55 ° C. After 40 minutes, stop stirring and temperature control; filter the mixed solution to obtain a crude OBMF product weighing 18.7 g.

[0071] Step 2: 18.7 g of the crude OBMF obtained above was mixed with 374 g of dimethyl sulfoxide, and mechanical stirring was started at a speed of 350 rpm. The temperature was raised to 50° C. After the crude OBMF was completely dissolved, 0.5 g of fruit shell (fruit core) activated carbon with a particle size of 0.2 mm-0.4 mm was added. The stirring state was maintained for 35 minutes, and then the stirring and temperature control were stopped; the activated carbon was filtered out while hot to obtain a filtrate, which was placed in a cold bath at 5° C. for crystallization for 25 minutes.

[0072] The crystallization liquid was filtered to obtain wet crystals, and the crystallization mother liquor was collected. The crystals were then washed with 3 g of deionized water and vacuum dried. The optimal negative pressure was maintained at 30° C. and dried for 90 min to obtain 0.55 g of OBMF finished product (yield 3.79%).

[0073] Comparative Example 2

[0074] Step 1: Weigh 100 g of HMF crude product (of which HMF accounts for 82%, OBMF accounts for 14.5%, and other impurities account for 3.5%), mix it with 200 g of deionized water, start mechanical stirring at a speed of 400 rpm, and heat to 55 ° C. After 40 minutes, stop stirring and temperature control; filter the mixed solution to obtain a crude OBMF product weighing 18.7 g.

[0075] Step 2: 18.7 g of the crude OBMF obtained above was mixed with 374 g of N,N-dimethylformamide, and mechanical stirring was started at a speed of 350 rpm. The temperature was raised to 50° C. After the crude OBMF was completely dissolved, 0.5 g of fruit shell (fruit core) activated carbon with a particle size of 0.2 mm-0.4 mm was added, and the stirring state was maintained for 35 minutes, and then the stirring and temperature control were stopped; the activated carbon was filtered out while hot to obtain a filtrate, which was placed in a cold bath at 5° C. for crystallization for 25 minutes.

[0076] The above crystallization liquid was filtered to obtain wet crystals, and the crystallization mother liquor was collected. The crystals were then washed with 3 g of deionized water and vacuum dried. The optimal negative pressure was maintained at 30° C. and dried for 90 min to obtain 3.68 g of OBMF finished product (yield 25.38%).

Claims

1. A method for separating and purifying bis-(5-formylfurfuryl) ether from a crude 5-hydroxymethylfurfural product, the method comprising the steps of: Step 1: adding water to the crude 5-hydroxymethylfurfural product, dissolving the 5-hydroxymethylfurfural in the water at a temperature of 35° C. to 75° C., and filtering to obtain a crude bis-(5-formylfurfuryl) ether product; Step 2: adding an organic solvent to the crude bis-(5-formylfurfuryl) ether obtained above, dissolving the bis-(5-formylfurfuryl) ether in the solvent at a temperature of 30° C. to 80° C., and then adding activated carbon for activated carbon decolorization to obtain a decolorized bis-(5-formylfurfuryl) ether solution; then cooling the solution for crystallization, filtering, washing, and drying to obtain bis-(5-formylfurfuryl) ether crystals, wherein the organic solvent is selected from methanol, ethanol, isopropanol, methyl acetate, ethyl acetate, and propyl acetate.

2. The method for separating and purifying bis-(5-formylfurfuryl) ether from 5-hydroxymethylfurfural crude product according to claim 1, characterized in that, In the crude 5-hydroxymethylfurfural product, by weight, the content of bis-(5-formylfurfuryl) ether is 5% to 15%, the content of 5-hydroxymethylfurfural is 80% to 90%, and the content of other impurities is 1% to 5%.

3. The method for separating and purifying bis-(5-formylfurfuryl) ether from 5-hydroxymethylfurfural crude product according to claim 1 or 2, characterized in that, In the step 1, the water used is pure water or deionized water, and the amount of water used is a weight ratio of water to 5-hydroxymethylfurfural crude product of 0.5:1 to 5:1; stirring is performed during the dissolution process, the stirring method is magnetic stirring or mechanical stirring, the stirring speed is 100rpm to 500rpm, and the stirring time is 20 to 60min.

4. The method for separating and purifying bis-(5-formylfurfuryl) ether from 5-hydroxymethylfurfural crude product according to claim 1 or 2, characterized in that, In the step 2, the mass fraction of the crude bis-(5-formylfurfuryl) ether is 1% to 20% relative to the total amount of the crude bis-(5-formylfurfuryl) ether and the organic solvent.

5. The method for separating and purifying bis-(5-formylfurfuryl) ether from 5-hydroxymethylfurfural crude product according to claim 1 or 2, characterized in that, In the step 2, the organic solvent is ethyl acetate, and the mass fraction of the crude bis-(5-formylfurfuryl) ether is 4% to 8% relative to the total amount of the crude bis-(5-formylfurfuryl) ether and ethyl acetate.

6. The method for separating and purifying bis-(5-formylfurfuryl) ether from a crude 5-hydroxymethylfurfural product according to claim 1 or 2, characterized in that, In the step 2, the activated carbon used for decolorization is wood activated carbon, fruit shell (core) activated carbon or coal activated carbon, the amount of the activated carbon is 0.5% to 5% of the weight of the crude product of bis-(5-formylfurfuryl) ether, and the particle size of the activated carbon is 0.2 mm to 2 mm; stirring is performed during the dissolution and decolorization process, the stirring method is magnetic stirring or mechanical stirring, the stirring speed is 100 rpm to 500 rpm, and the stirring time during decolorization is 20 to 60 min.

7. The method for separating and purifying bis-(5-formylfurfuryl) ether from a crude 5-hydroxymethylfurfural product according to claim 1 or 2, characterized in that, In step 2, the activated carbon used for decolorization is fruit shell (fruit core) activated carbon, the amount of activated carbon used is 1% to 2% of the weight of the crude product of bis-(5-formylfurfuryl) ether, and the particle size of the activated carbon is 0.2 mm to 0.4 mm.

8. The method for separating and purifying bis-(5-formylfurfuryl) ether from a crude 5-hydroxymethylfurfural product according to claim 1 or 2, characterized in that, In the step 2, after filtering and removing the activated carbon, a decolorized bis-(5-formylfurfuryl) ether solution is obtained, and the solution is cooled and crystallized, the crystallization method is mechanical stirring crystallization or static crystallization, the crystallization temperature is -10°C to 20°C, and the crystallization time is 10 to 60 minutes; after crystallization, filtering, washing and drying are performed, wherein the solvent for washing the crystals is deionized water, methanol, ethanol, isopropanol or ethyl acetate, and the amount of the washing solvent is 5 to 50 g per 100 g of bis-(5-formylfurfuryl) ether crystals, and the drying is freeze drying, vacuum drying, oven drying or air drying at room temperature.

9. The method for separating and purifying bis-(5-formylfurfuryl) ether from a crude 5-hydroxymethylfurfural product according to claim 1 or 2, characterized in that, In the step 2, filtering is performed after crystallization to obtain wet crystals and crystallization mother liquor, and the obtained crystallization mother liquor is used in the step 2 as an organic solvent for dissolving the crude bis-(5-formylfurfuryl) ether.

10. The method for separating and purifying bis-(5-formylfurfuryl) ether from a crude 5-hydroxymethylfurfural product according to claim 1 or 2, characterized in that In the step 1, the water used is deionized water, and the amount of deionized water used is a weight ratio of deionized water to 5-hydroxymethylfurfural crude product of 2:1; the solution is dissolved under stirring at a temperature of 55±5°C, the stirring method is mechanical stirring, the stirring speed is 400±10rpm, and the stirring time is 40±2min; In the step 2, the organic solvent is ethyl acetate, and the mass fraction of the crude bis-(5-formylfurfuryl) ether is 4% to 8% relative to the total amount of the crude bis-(5-formylfurfuryl) ether and ethyl acetate; the activated carbon for decolorization is fruit shell (fruit core) activated carbon, the amount of activated carbon is 1% to 2% of the weight of the crude bis-(5-formylfurfuryl) ether, and the particle size of the activated carbon is 0.2 mm to 0.4 mm; stirring is performed during the dissolution and decolorization process, the temperature is 50±5°C, the stirring method is mechanical stirring, the stirring speed is 350±10rpm, and the stirring time during decolorization is 35±2min; the crystallization method is static crystallization, the crystallization temperature is 5±2°C, and the crystallization time is 25min; filtering, washing and drying are performed after crystallization, wherein the solvent for washing the crystals is deionized water, the amount of the washing solvent is 20 to 40g per 100g of bis-(5-formylfurfuryl) ether crystals, and the drying is vacuum drying.

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