Method for preparing 5-hydroxymethylfurfural from native woody biomass and purifying 5-hydroxymethylfurfural

Abstract

The invention discloses a method for preparing 5-hydroxymethylfurfural from native wood biomass and purifying the 5-hydroxymethylfurfural, and belongs to the technical field of comprehensive utilization of biomass resources. According to the method, metal salt is adopted as a catalyst, primary woody biomass is subjected to high-substrate-concentration hydrolysis in a single-phase system through a one-pot method, then 5-hydroxymethylfurfural is separated and purified through hydrolysate, and high-yield and high-purity 5-hydroxymethylfurfural is obtained through simple steps such as rotary evaporation, extraction and rectification. According to the method provided by the invention, a large amount of organic extractant is replaced with water, a large amount of humus can be removed, the cost is reduced, the operation is simple, industrialization is easy, and the method is green and environment-friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation and purification of 5-hydroxymethylfurfural, and particularly relates to a method for preparing 5-hydroxymethylfurfural from native wood biomass and purifying the same. Background Art

[0002] Bio-based materials can supplement traditional petroleum-based materials due to their advantages such as low carbon, recyclability and renewable nature.

[0003] Lignocellulose is an abundant and renewable resource for fuels and chemicals, mainly composed of cellulose (30-50%), hemicellulose (20-40%) and lignin (15-25%). 5-HMF is an important platform molecule, and its molecular formula contains an aldehyde group and a hydroxymethyl group, so its downstream derivatives have great room for development. However, 5-HMF is currently limited by factors such as raw materials, preparation process, and separation technology, resulting in relatively high production costs. Most of the current industrial preparations of 5-HMF are prepared from fructose, or 5-HMF is prepared from fructose obtained from native biomass raw materials, and most of the current separation technologies are based on the reaction solution of 5-HMF prepared from fructose. Therefore, its share in the bio-based material market is very small. However, with the maturity of the preparation process and the optimization of the separation technology, such as the direct use of native biomass raw materials to prepare 5-HMF, including the separation and purification of 5-HMF with low-cost solvents, the production cost of 5-HMF will be reduced, thereby reducing the price of downstream products. 5-Hydroxymethylfurfural and its derivatives can be widely used in plastics, chemicals, oil additives, food and other industries, and the market prospects are generally promising.

[0004] Patent publication number CN101720320 discloses a method for purifying furfural, which uses one or more non-functional polymer resins to adsorb and desorb an aqueous mixture containing hydroxymethylfurfural synthetic mixture components to purify hydroxymethylfurfural. Under certain circumstances, a cation exchange resin chromatography separation technology is selectively used. This patent describes a method for purifying 5-hydroxymethylfurfural from fructose, and the separation rate is slow, which is not conducive to industrialization.

[0005] Patent publication number CN105377825 discloses a method for preparing 5-hydroxymethylfurfural from sugars. The sugar involved has a yield of more than 50% in a system where a quaternary ammonium salt acts as a solvent. However, the reaction temperature of this invention is 100°C and water is present. Colored impurities and side reaction products are still generated during the reaction, affecting the purity of the product and failing to achieve the purpose of refining.

[0006] Patent publication number CN109897020 discloses a method for refining crude 5-hydroxymethylfurfural, wherein sodium bisulfite is added and then an organic solvent is added for extraction, thereby obtaining 5-hydroxymethylfurfural with higher purity. The purification liquid used is 5-hydroxymethylfurfural crystals, which will incur additional costs in industrial production.

[0007] At present, most of the raw materials for preparing 5-hydroxymethylfurfural, such as fructose, glucose, starch, etc., come from edible resources. Cellulose is the most abundant non-food polysaccharide in nature, and it comes from a wide range of sources, such as cotton, hemp, silk, agricultural waste, etc. The preparation of 5-hydroxymethylfurfural from native woody biomass can not only avoid competition with food, but also effectively utilize waste generated in the production process of agricultural products and textiles, which can turn waste into treasure, reduce environmental burden, and reduce production costs. However, due to the strong stability of non-edible biomass raw materials, its conversion rate is very low and uneconomical. The current preparation process still has problems such as low product yield, many separation steps, and is not conducive to industrial production. And a large amount of organic solvents are needed in the purification process. Therefore, in view of the current problem, it is necessary to seek a more efficient method for purifying 5-hydroxymethylfurfural from native woody biomass hydrolyzate. Summary of the invention

[0008] The present invention aims to overcome the defects of the prior art and provide a method for preparing 5-hydroxymethylfurfural from native wood biomass and purifying the same.

[0009] The technical solution of the present invention is as follows:

[0010] A method for preparing 5-hydroxymethylfurfural from native wood biomass and purifying the same comprises the following steps:

[0011] (1) Adding raw wood biomass (10-20 wt%), a catalyst, water and an organic solvent into a high pressure reactor, heating to 150-200° C. at 200-800 rpm for 30-120 min to obtain a hydrolyzate.

[0012] (2) separating and purifying the hydrolyzate in step (1), and recovering the organic solvent by rotary evaporation.

[0013] (3) The residual liquid of the organic solvent after rotary evaporation in step (2) is added with a salt solution and a small amount of ether to remove humus, and then centrifuged and filtered to obtain an aqueous phase. This step can remove a large amount of humus and replace a large amount of organic solvent with water. A low-concentration alkaline sodium chloride saturated solution and an organic solvent are added to the aqueous phase for extraction, and then layering is performed to retain the organic phase.

[0014] (4) Rotary distillation is performed on the organic phase in step (3) to obtain a residual liquid, which is then distilled to obtain a high-purity 5-hydroxymethylfurfural sample.

[0015] In a preferred embodiment of the present invention, the native woody biomass is: straw, wheat straw, rice straw, bagasse, hemp, bamboo, forest wood and waste.

[0016] In a preferred embodiment of the present invention, the metal salt is Al2(SO4)3·18H2O, ZnSO4·7H2O, K2SO4·7H2O, MgSO4·7H2O, CuSO4 5H2O, AlCl3 6H2O, FeCl3·4H2O, ZnCl2 6H2O, MgCl2 6H2O, CaCl2 6H2O, CuCl2·2H2O, etc.

[0017] In a preferred embodiment of the present invention, the organic solvent is a mixed solvent of one or more of acetonitrile, acetone, butanone, tetrahydrofuran or methyl isobutyl ketone.

[0018] In a preferred embodiment of the present invention, the salt solution is a 5-20% sodium chloride aqueous solution, a potassium chloride aqueous solution, a magnesium chloride aqueous solution, a sodium sulfate aqueous solution, or the like.

[0019] In a preferred embodiment of the present invention, the solvent for extracting 5-hydroxymethylfurfural specifically includes: ether, ethyl acetate, ethanol, butanol, water and the like.

[0020] The method provided by the present invention has a simple process and is easy to industrialize. In the present invention, native wood biomass is used as a substrate and the substrate concentration is high. In the present invention, the solvent for purifying 5-hydroxymethylfurfural is mainly water, which is a common solvent. Since the organic solvent and water are miscible in this reaction system, a large amount of humus is precipitated after the organic solvent is removed. A large amount of humus can be removed by washing with water to obtain a clear aqueous solution. Water is used to replace a large amount of organic solvent, which is highly economical and easy to industrialize.

[0021] Therefore, the present invention uses metal salt as a catalyst, hydrolyzes the original wood biomass with a high substrate concentration in a single-phase system in a one-pot method, and then uses the hydrolyzate to separate and purify 5-hydroxymethylfurfural, and obtains high-yield and high-purity 5-hydroxymethylfurfural through simple steps such as rotary evaporation, extraction, and distillation. The method provided in the present invention replaces a large amount of organic extractant with water and can remove a large amount of humus, reduce costs, is simple to operate, easy to industrialize, and is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The figure is a liquid chromatography-mass spectrum of 5-hydroxymethylfurfural obtained by purification of the present invention.

[0023] Figure 2 The figure is the gas chromatography-mass spectrum of 5-hydroxymethylfurfural obtained by purification in the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further illustrated and described below through specific implementation modes in combination with the accompanying drawings.

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0026] The term "one embodiment" or "embodiment" in the present invention refers to a specific feature, structure or characteristic that can be included in at least one implementation of the present invention. The appearance of "in one embodiment" in different places in this specification does not necessarily refer to the same embodiment, nor is it an embodiment that is exclusive or selective with other embodiments.

[0027] Unless otherwise specified, all reagents and materials used in the present invention are commercially available.

[0028] Example 1

[0029] 400 g of bagasse, 10 g of Al2(SO4)3, 600 g of H2O and 3000 g of tetrahydrofuran were added into a 10 L high pressure reactor, heated to 180°C at 400 rpm for 30 min to obtain a 5-hydroxymethylfurfural hydrolyzate with a concentration of 1.3%.

[0030] Example 2

[0031] 400 g of xylose residue, 10 g of AlCl 3 , 600 g of H 2 O and 3000 g of tetrahydrofuran were added into a 10 L high pressure reactor, heated to 180° C. at 400 rpm for 30 min to obtain a 5-hydroxymethylfurfural hydrolyzate with a concentration of 2.0%.

[0032] Example 3

[0033] The hydrolyzate in Example 2 was subjected to rotary evaporation of the organic solvent, and then 1000 mL of 15% sodium chloride solution was added, and 25 mL of ether was used to remove humus, and then centrifuged and filtered. This step can remove a large amount of humus to obtain an aqueous phase. 600 mL of 1 mol / L NaOH saturated sodium chloride aqueous solution was added to the aqueous phase, and 400 mL of ethyl acetate was used for extraction, and then the organic phase was retained.

[0034] The ethyl acetate solution after extraction was concentrated by rotary evaporation at 50°C under vacuum for 20 min, and the residual liquid was taken for subsequent treatment.

[0035] The residual liquid is distilled at 160°C for 0.5h to obtain 5-hydroxymethylfurfural.

[0036] The experimental results showed that the purity of 5-hydroxymethylfurfural was 98.27% and the recovery rate was 52.34%.

[0037] Example 4

[0038] After the organic solvent was rotary evaporated from the hydrolyzate in Example 2, 500 mL of 10% sodium chloride solution and 25 mL of ether were added, and the humus was removed and then centrifuged to obtain an aqueous phase. 600 mL of 1 mol / L NaOH saturated sodium chloride aqueous solution was added to the aqueous phase. This step can remove a large amount of humus. 300 mL of ether was extracted, and then layered, and the organic phase was retained.

[0039] The ether solution after extraction was concentrated by rotary evaporation at 40°C under vacuum for 20 min, and the residual liquid was taken for subsequent treatment.

[0040] The residual liquid is distilled at 160°C for 0.5h to obtain 5-hydroxymethylfurfural.

[0041] The experimental results showed that the purity of 5-hydroxymethylfurfural was 98.35% and the recovery rate was 45.34%.

[0042] Comparative Example 1

[0043] After the organic solvent was rotary evaporated from the hydrolyzate in Example 1, 100 g of sodium chloride and 500 mL of ethyl acetate were added four times, and the residual liquid was extracted.

[0044] The ethyl acetate solution after extraction was concentrated by rotary evaporation to obtain a concentrated solution.

[0045] The concentrate was added with 200 g of water, 200 mL of ethyl acetate and 13 g of NaHSO 3 , and the layers were separated to obtain an aqueous phase.

[0046] The aqueous solution was concentrated by rotary evaporation, and 300 mL of diethyl ether was added to obtain a diethyl ether solution.

[0047] The ether solution was concentrated by rotary evaporation at 40°C and vacuum for 20 minutes to obtain a concentrated solution. The concentrated solution was distilled at 160°C for 0.5 hours to obtain 5-hydroxymethylfurfural. The purity of 5-hydroxymethylfurfural was 96.35%, and the recovery rate was 23.45%.

[0048] It can be seen from the above examples that when water is the main extractant, the purity and recovery rate of 5-hydroxymethylfurfural are high, and the process is less, so 5-hydroxymethylfurfural can be efficiently purified from the hydrolyzate.

[0049] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing 5-hydroxymethylfurfural from native woody biomass and purifying it, characterized in that: The steps include: (1) adding raw wood biomass, a catalyst, water and an organic solvent into a high pressure reactor, heating to 150-200° C. to react and obtain a hydrolyzate; (2) filtering the hydrolyzate in step (1) to remove solid residues, separating and purifying the liquid phase, and recovering the organic solvent by rotary evaporation; (3) adding a salt solution and ether to the residual liquid of the organic solvent after rotary evaporation in step (2) to remove humus, and then centrifugally filtering to obtain an aqueous phase; adding a saturated alkaline sodium chloride solution and an organic solvent to the aqueous phase for extraction, and then layering to retain the organic phase; (4) Rotating and distilling the organic phase in step (3) to obtain a residual liquid, and then rectifying it to obtain a high-purity 5-hydroxymethylfurfural sample.

2. The method according to claim 1, characterized in that: The native woody biomass is agricultural and forestry waste, such as straw, wheat straw, rice straw, bagasse, hemp, bamboo, forest trees or their wastes.

3. The method according to claim 1, characterized in that: The specific operation in step (1) is as follows: 10-20 wt% of original woody biomass, a catalyst, water and an organic solvent are added into a high-pressure reactor, heated to 150-200° C. at 200-800 rpm and reacted for 30-120 min to obtain a hydrolyzate.

4. The method according to claim 1, characterized in that: The catalyst is MgSO4·7H2O, ZnCl2 6H2O, CuSO45H2O, Al2(SO4)3·18H2O, ZnSO4·7H2O, K2SO4·7H2O, AlCl3 6H2O, FeCl3·4H2O, MgCl2 6H2O, CaCl2 6H2O or CuCl2·2H2O.

5. The method according to claim 1, characterized in that: The organic solvent is one or more mixed solvents selected from acetonitrile, acetone, butanone, tetrahydrofuran or methyl isobutyl ketone.

6. The method according to claim 1, characterized in that: The salt solution is a sodium chloride aqueous solution, a potassium chloride aqueous solution, a magnesium chloride aqueous solution, or a sodium sulfate aqueous solution.

7. The method according to claim 1, characterized in that: The concentration of the salt solution is 5-20%; the concentration of the alkaline sodium chloride saturated solution is 0.1-2 mol / L; and the mass ratio of the added amount of ether to the residual liquid is 0.01-0.

05.

8. The method according to claim 1, characterized in that: The solvent for extracting 5-hydroxymethylfurfural specifically includes: ether, ethyl acetate, ethanol, butanol or water.

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