Preparation method of 5-hydroxymethylfurfural aqueous solution based on intermittent reaction

Abstract

The invention discloses a preparation method of a 5-hydroxymethylfurfural aqueous solution based on intermittent reaction. Comprising the following steps that a mixed solution containing a glycosyl biomass raw material, a catalyst, inorganic salt, water and an organic solvent reacts in a stirring state, the organic solvent is insoluble in water, and a water phase and an organic phase are obtained after the reaction; after the reaction, water is used as an extracting agent, an organic phase after the reaction is extracted, an aqueous solution of the 5-hydroxymethylfurfural is obtained, and an organic solvent after the extraction can be recycled. In the reaction process, 5-hydroxymethylfurfural generated in a water phase is transferred to an organic phase, so that the generation of a side reaction of generating black rot is inhibited. An aqueous solution of 5-hydroxymethylfurfural is obtained through aqueous phase extraction, high-energy-consumption operation processes such as reduced pressure distillation are not needed, and an organic solvent can be recycled.

Description

Technical Field

[0001] The present application relates to a method for preparing an aqueous solution of 5-hydroxymethylfurfural based on an intermittent reaction, and belongs to the technical field of preparation and synthesis of 5-hydroxymethylfurfural. Background Art

[0002] Under the guidance of the "dual carbon target", bio-based materials are gradually becoming one of the new industrial directions for global scientific and technological innovation and economic development. The reduction of fossil fuel reserves and environmental pollution caused by the increase of greenhouse gases have promoted the huge growth of synthetic fuels and chemicals from sustainable and renewable resources. As a key intermediate for biomass conversion and sustainable energy sources, 5-hydroxymethylfurfural can be obtained by pyrolysis or acid hydrolysis of biomass (such as lignocellulose). It can be further converted into fuels and fuel additives such as 2,5-di(oxymethyl)furan (DMF) and sulfonated hydroxymethylfurfural (HMF-OS). These compounds can be used as combustion fuels, additives for biodiesel, and sustainable energy sources to replace petroleum fuels. 5-Hydroxymethylfurfural can be used as a starting material for the synthesis of many important organic compounds. It can be transformed through a variety of reaction pathways to produce various functional groups and chemical bonds. This makes it used in a wide range of industries such as drugs, dyes, pesticides, fragrances and polymer materials. The chemical activity and diversity of 5-hydroxymethylfurfural provide new possibilities for the synthesis of highly controllable and green chemicals.

[0003] Compared with traditional synthesis methods, organic synthesis using 5-hydroxymethylfurfural can reduce or avoid the use of toxic substances and environmental pollutants. This green synthesis method helps reduce dependence on limited resources, reduce waste generation, and reduce negative impacts on the environment. By developing green synthesis routes for renewable raw materials, this green chemistry method can contribute to a sustainable and environmentally friendly chemical industry.

[0004] 5-Hydroxymethylfurfural has extensive potential in the preparation of functional materials. It can be used as a monomer of polymers, participate in polymer polymerization reactions, and prepare polymer materials with specific properties. In addition, through appropriate functional modification, 5-Hydroxymethylfurfural can also be used to prepare nanomaterials, catalysts, electrochemical materials, etc. These functional materials play an important role in fields including energy storage, catalysts, sensors, etc. As a renewable compound, 5-Hydroxymethylfurfural has many advantages over traditional petrochemicals. It can reduce dependence on limited resources and alleviate energy crises and environmental pollution problems by replacing petrochemicals. By promoting the research and application of 5-Hydroxymethylfurfural, people can achieve the goals of sustainable energy, sustainable chemicals, and sustainable development. In summary, 5-Hydroxymethylfurfural is of great significance in sustainable energy, chemical synthesis, green chemical synthesis, functional material preparation, and sustainable development, and plays an important role in promoting sustainable development and building a sustainable society.

[0005] The typical route to produce 5-hydroxymethylfurfural is the acid-catalyzed dehydration of carbohydrates, such as glucose, fructose, cellulose, and sucrose. Various homogeneous or heterogeneous catalysts have been developed, including Lewis acid and Bronsted acid, which have been found to be effective for the synthesis of 5-hydroxymethylfurfural and are widely used in the production of 5-hydroxymethylfurfural. However, due to the high reactivity of the 5-hydroxymethylfurfural produced during the reaction, under the catalytic action of such catalysts, 5-hydroxymethylfurfural will further react to polymerize to form high molecular black rot or decompose to form acetoacetic acid, etc. The generation of these by-products will lead to low selectivity of the reaction, and will also cause equipment corrosion and blockage, making it difficult to clean, making the reaction difficult to carry out, greatly increasing the maintenance and use costs of the equipment, and having poor economic benefits. 5-Hydroxymethylfurfural can be further deeply oxidized in the aqueous phase to prepare a bio-based raw material with important uses, furandicarboxylic acid. Therefore, directly preparing an aqueous solution of 5-hydroxymethylfurfural has great production and economic value, and there is no need for traditional energy-intensive extraction and reduced pressure distillation operations to obtain 5-hydroxymethylfurfural crystals, which are then dissolved in an aqueous phase for deep oxidation. Summary of the invention

[0006] According to one aspect of the present application, a method for preparing an aqueous solution of 5-hydroxymethylfurfural based on an intermittent reaction is provided, wherein an aqueous solution containing a sugar-based biomass raw material and a reaction catalyst is mixed with a water-insoluble organic phase, and the mixture is reacted under stirring. The 5-hydroxymethylfurfural generated in the aqueous phase is transferred to the organic phase during stirring. After the reaction, water is used as an extractant to extract the organic phase after the reaction to obtain an aqueous solution of 5-hydroxymethylfurfural, and the organic phase is reused.

[0007] This application adopts the following technical solutions:

[0008] A preparation method of a 5-hydroxymethylfurfural aqueous solution based on intermittent reaction comprises the steps:

[0009] S1, reacting a mixed solution containing sugar-based biomass, inorganic salts, catalysts, organic solvents, and water to obtain an aqueous phase and an organic phase;

[0010] The organic solvent is insoluble in water;

[0011] S2, extracting the organic phase with water to obtain the 5-hydroxymethylfurfural aqueous solution.

[0012] During the reaction, the 5-hydroxymethylfurfural generated in the aqueous phase is transferred to the organic phase in real time.

[0013] The organic extraction phase directly mixed with the aqueous phase and the added inorganic salt can promote the dissolution of 5-hydroxymethylfurfural in the organic phase at the initial stage of its generation, thereby preventing 5-hydroxymethylfurfural from further side reactions in the aqueous phase to form black rot. At the same time, the aqueous solution of 5-hydroxymethylfurfural is obtained by aqueous phase extraction, and the organic solvent can be reused without high-energy consumption operations such as reduced pressure distillation. Energy consumption is effectively reduced. The system for synthesizing 5-hydroxymethylfurfural aqueous solution used in the present method has great economic benefits, low system cost, little environmental pollution, simple operation, easy repetition, and low equipment maintenance cost.

[0014] Optionally, in step S1, the mixed solution contains:

[0015] 0.5-10 parts by weight of sugar-based biomass, 0.001-2 parts by weight of inorganic salt, 0.01-1 parts by weight of catalyst, 1-50 parts by weight of organic solvent, and 1-20 parts by weight of water.

[0016] Optionally, the weight ratio of the sugar-based biomass to water is 0.5-10:1-20.

[0017] Optionally, the weight ratio of the sugar-based biomass to water is 5-10:5-20.

[0018] Optionally, the weight ratio of the sugar-based biomass to water is 8-10:6-20.

[0019] Optionally, the weight ratio of the sugar-based biomass to water is 5-10:10-20.

[0020] Optionally, the weight ratio of the sugar-based biomass to water is 10:15-20.

[0021] Optionally, the weight ratio of the sugar-based biomass to water is 1:0.8-10.

[0022] Optionally, the weight ratio of the sugar-based biomass to water is independently selected from any value of 1:0.8, 1:1, 1:2, 1:3, 1:0.8, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, or any range therebetween.

[0023] Optionally, the weight ratio of the sugar-based biomass to the catalyst is 0.5-10:0.01-1.

[0024] Optionally, the weight ratio of the sugar-based biomass to the catalyst is 8-10:0.01-1.

[0025] Optionally, the weight ratio of the sugar-based biomass to the catalyst is 10:0.01-1.

[0026] Optionally, the weight ratio of the sugar-based biomass to the catalyst is independently selected from any value of 10:0.01, 10:0.05, 10:0.1, 10:0.2, 10:0.5, 10:0.7, 10:0.9, 10:1, or any range therebetween.

[0027] Optionally, the weight ratio of the sugar-based biomass to the inorganic salt is 0.5-10:0.001-2;

[0028] Optionally, the weight ratio of the sugar-based biomass to the inorganic salt is 5-10:0.05-2;

[0029] Optionally, the weight ratio of the sugar-based biomass to the inorganic salt is 8-10:0.5-2;

[0030] Optionally, the weight ratio of the sugar-based biomass to the inorganic salt is 8-10:1-2.

[0031] Optionally, the weight ratio of the water to the organic solvent is 0.5-10:1-50.

[0032] Optionally, the weight ratio of the water to the organic solvent is 0.5-10:1-20.

[0033] Optionally, the weight ratio of the water to the organic solvent is 5-10:5-50.

[0034] Optionally, the weight ratio of the water to the organic solvent is 8-10:15-50.

[0035] Optionally, the weight ratio of the water to the organic solvent is 8-10:30-50.

[0036] Optionally, the weight ratio of the water to the organic solvent is 1:1-100.

[0037] Optionally, the weight ratio of water to the organic solvent is independently selected from any value of 1:1, 1:5, 1:10, 1:20, 1:50, 1:70, 1:100 or any range value therebetween.

[0038] Optionally, the reaction conditions include: reaction temperature of 30 to 180° C., and reaction time of 2 to 10 h.

[0039] Optionally, the reaction conditions include:

[0040] The reaction temperature is selected from any value of 30°C, 40°C, 50°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 175°C, 180°C or any range therebetween;

[0041] The reaction time is selected from any value among 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h or any range therebetween.

[0042] Optionally, the sugar-based biomass is selected from at least one of glucose, fructose, xylose, mannose, galactose, lactose, sucrose, maltose, cellulose and starch;

[0043] Optionally, the cellulose is selected from at least one of cellulose ether, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose and carboxymethyl cellulose.

[0044] Optionally, the organic solvent is selected from at least one of isobutyl acrylate, butyl propionate, butyl butyrate, ethyl isobutyrate, ethyl lactate, butyl lactate, amyl lactate, diethyl maleate, dibutyl maleate, soybean oil, sunflower oil, sesame oil, peanut oil, olive oil, castor oil, cottonseed oil, and isopropyl palmitate.

[0045] Optionally, the inorganic salt is selected from at least one of halogen compounds, borides, silicates, aluminates, phosphates and borates.

[0046] Optionally, the halogen compound includes at least one of sodium chloride, sodium fluoride, magnesium chloride, calcium chloride, barium chloride, chromium chloride, ferric chloride, copper chloride, aluminum chloride, sodium bromide, calcium bromide, and magnesium bromide.

[0047] Optionally, the boride includes at least one of boron fluoride, magnesium boride, titanium boride, chromium boride and calcium boride.

[0048] Optionally, the silicate includes at least one of sodium silicate, calcium silicate, magnesium silicate, ammonium silicate and the like.

[0049] Optionally, the aluminate includes at least one of sodium aluminate, calcium aluminate, magnesium aluminate, ammonium aluminate and the like.

[0050] Optionally, the phosphate includes at least one of sodium phosphate, calcium phosphate, magnesium phosphate, ammonium phosphate and the like.

[0051] Optionally, the catalyst is selected from at least one of a water-soluble acid, a solid acid catalyst, an alkoxyaluminum, a phenoxyaluminum, tetrabutyl stannate, an alkoxytitanium, an alkoxyzirconium, ethyl antimonite, and butyl antimonite.

[0052] Optionally, the water-soluble acid includes at least one of phosphoric acid, hydrochloric acid, sulfuric acid and boric acid.

[0053] Optionally, the solid acid catalyst is selected from at least one of a cation exchange resin, a molecular sieve having an acidic site, a sulfide, a natural clay mineral, an amorphous oxide, and a metal organic framework material.

[0054] Optionally, the hydrochloric acid is a 35.0-40.0 wt % hydrochloric acid solution.

[0055] Optionally, the sulfuric acid is 95.0-99.0 wt % concentrated sulfuric acid.

[0056] Optionally, the cation exchange resin is selected from sulfonic acid resins.

[0057] Optionally, the molecular sieve having an acidic site is selected from at least one of ZSM-5 molecular sieve, TS-1 molecular sieve, 13X molecular sieve and Y molecular sieve.

[0058] Optionally, the natural clay mineral is selected from kaolin.

[0059] Optionally, the metal organic framework material is selected from metal organic framework material MIL-125;

[0060] Optionally, the reaction pressure is not particularly limited and may be at normal pressure.

[0061] Optionally, in step S2, the volume ratio of water to organic phase is 1 to 3:1.

[0062] Optionally, in step S2, the volume ratio of water to the organic phase is any value among 1:1, 1.5:1, 2:1, 2.5:1, 5:1, or any range therebetween.

[0063] Optionally, the extraction is performed 2 to 5 times.

[0064] The extraction 2 to 5 times refers to adding water to the organic phase obtained after the reaction for extraction, and after standing and shaking, the solution is separated into layers. After the aqueous phase is separated, water is added again to the remaining organic phase for extraction, and the operation is repeated multiple times.

[0065] Optionally, in the preparation method, the yield of 5-hydroxymethylfurfural in an organic solvent is greater than 80%.

[0066] Optionally, in the preparation method, the extraction efficiency of 5-hydroxymethylfurfural in the organic solvent after the water extraction reaction is 80% to 95%.

[0067] The preparation route of the present application is to mix sugar-based biomass with an inorganic salt aqueous solution, a catalyst and an organic extraction solvent, and use water to extract the organic phase containing 5-hydroxymethylfurfural after the reaction to obtain a 5-hydroxymethylfurfural aqueous solution, thereby realizing the reuse of the organic extraction phase. The added organic phase and inorganic salt effectively inhibit the further side reactions of 5-hydroxymethylfurfural, and no other impurities and black rot are generated after the reaction. After the reaction, the organic phase is extracted with water to obtain a 5-hydroxymethylfurfural aqueous solution, which can be reused to realize the recovery and separation of the extraction solvent and the product without distilling the organic phase. However, the traditional preparation process of 5-hydroxymethylfurfural is difficult to control the occurrence of its side reactions, and the generated black rot is very likely to cause equipment corrosion and blockage. Compared with the traditional pure water phase reaction system, the invention can effectively avoid the side reaction of 5-hydroxymethylfurfural, the reaction liquid after the reaction is clear and transparent, and has a high conversion rate and selectivity. Compared with the atmospheric pressure or reduced pressure distillation process required by the traditional organic solvent, the use of water extraction can effectively reduce the energy consumption of its recycling process, is environmentally friendly, and has a low economic cost, which is conducive to industrial production and expansion, and the equipment maintenance cost is low, and the 5-hydroxymethylfurfural aqueous solution can be efficiently produced.

[0068] The beneficial effects of this application include:

[0069] (1) The present application provides a method for preparing an aqueous solution of 5-hydroxymethylfurfural based on an intermittent reaction. Compared with the traditional method, the inorganic salt added in the preparation process of the present invention directly mixes the aqueous phase with the organic solvent extraction phase to produce a synergistic effect, and the product is transferred from the aqueous phase to the organic phase, which can effectively control the occurrence of side reactions, avoid the generation of black rot, improve the selectivity of the reaction, and greatly reduce equipment maintenance and labor costs.

[0070] (2) The present application provides a method for preparing a 5-hydroxymethylfurfural aqueous solution based on an intermittent reaction. After the reaction is completed, 5-hydroxymethylfurfural in the organic phase of the reaction is extracted with water to obtain a 5-hydroxymethylfurfural aqueous solution. The organic solvent can be reused without the need for energy-intensive reduced pressure distillation operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 This is the hydrogen nuclear magnetic spectrum of the product synthesized in Example 1 of the present application.

[0072] Figure 2 This is the hydrogen nuclear magnetic spectrum of 5-hydroxymethylfurfural standard.

[0073] Figure 3 This is the carbon nuclear magnetic resonance spectrum of the product synthesized in Example 1 of the present application.

[0074] Figure 4 This is the carbon NMR spectrum of 5-hydroxymethylfurfural standard. DETAILED DESCRIPTION

[0075] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0076] Unless otherwise specified, the raw materials and catalysts in the examples of this application were purchased through commercial channels.

[0077] The analysis method in the examples of this application is as follows:

[0078] Carbon and hydrogen nuclear magnetic spectra were analyzed using a liquid nuclear magnetic spectrometer, model AVANCE II 400M, produced by Bruker Corporation, and the reaction solution was dissolved in a deuterated reagent.

[0079] The high performance liquid chromatograph used was produced by Waters Corporation, model 7890A, and the test conditions were water as the mobile phase, and ultraviolet visible light and differential refractometer detectors were used.

[0080] The 5-hydroxymethylfurfural yield is detected by high performance liquid chromatography, and deionized water is added to mix and constant volume during the detection.

[0081] In the embodiments of the present application, the yield of 5-hydroxymethylfurfural is calculated in the following manner:

[0082] The liquid chromatography peak area is obtained by configuring the 5-hydroxymethylfurfural content in the standard solution, and the peak area is used as the abscissa and the concentration of 5-hydroxymethylfurfural is used as the ordinate to obtain a standard curve; further, the concentration of 5-hydroxymethylfurfural in the reaction solution after the reaction can be calculated, and the yield of 5-hydroxymethylfurfural can be calculated through the concentration.

[0083] In the examples of the present application, the concentrations of concentrated sulfuric acid and hydrochloric acid used are described as follows:

[0084] Concentrated sulfuric acid: H2SO4 is 98.0wt%;

[0085] Hydrochloric acid: HCl is 37.0 wt%.

[0086] The yield, selectivity and extraction efficiency of 5-hydroxymethylfurfural in the examples of the present application are calculated as follows:

[0087] Yield of 5-hydroxymethylfurfural = number of moles of 5-hydroxymethylfurfural produced / number of moles of reaction substrate added

[0088] Selectivity of 5-hydroxymethylfurfural = number of moles of 5-hydroxymethylfurfural produced / number of moles of reaction substrate involved in the reaction

[0089] The extraction efficiency of 5-hydroxymethylfurfural = the number of moles of 5-hydroxymethylfurfural in the aqueous solution / the number of moles of 5-hydroxymethylfurfural in the organic phase before extraction.

[0090] Example 1

[0091] 7g of glucose, 15g of soybean oil, 2g of aluminum chloride and 10g of water were added to an intermittent reactor, and 0.12g of hydrochloric acid was added dropwise as a catalyst under stirring, and the temperature was raised to 120°C. The reaction time was 3 hours, and the colors of the aqueous reaction liquid and the organic extraction phase gradually deepened. After the reaction, a small amount of organic phase was taken for high performance liquid chromatography analysis, and the results showed that the yield of 5-hydroxymethylfurfural was 85%, and the selectivity was 93%. In the organic phase after the reaction, water (the volume ratio of water to the reaction liquid was 4:1) was used for multiple extraction operations, and the number of extractions was 4 times. After the extraction was completed, an extract was obtained, and the extraction efficiency was 93%, and the obtained 5-hydroxymethylfurfural aqueous solution was obtained.

[0092] Example 2

[0093] 15g methylcellulose, 30g isobutyl acrylate and 30g water were added to an intermittent reactor, 0.5g ZSM-5 molecular sieve was added as a catalyst under stirring, the temperature was raised to 130°C, the reaction time was 6 hours, and the colors of the aqueous reaction liquid and the organic extraction phase gradually deepened. After the reaction, a small amount of organic phase was taken for high performance liquid chromatography analysis, and the results showed that the yield of 5-hydroxymethylfurfural was 89%, and the selectivity was 92%. In the organic phase after the reaction, water (the volume ratio of water to the reaction liquid was 2:1) was used for multiple extraction operations, the number of extractions was 2 times, and the extraction was completed to obtain an extract, and the extraction efficiency was 85%, and the obtained 5-hydroxymethylfurfural aqueous solution was obtained.

[0094] Embodiments 3 to 11

[0095] The specific ingredient types, materials and reaction conditions are shown in Table 1 below. Other operations during the synthesis process are the same as in Example 1.

[0096] Table 1 Raw material composition, ratio and water extraction conditions of Examples 3 to 11

[0097]

[0098] Example 12 Liquid NMR Analysis

[0099] Liquid nuclear magnetic resonance analysis was performed on the 5-hydroxymethylfurfural prepared in Examples 1 to 11. Typical results are as follows: Figure 1 and Figure 3 As shown, Figure 2 and Figure 4 This is the standard spectrum of 5-hydroxymethylfurfural. Figure 1 The hydrogen nuclear magnetic resonance spectrum of 5-hydroxymethylfurfural prepared in Example 1 is as follows: Figure 1 and Figure 2 It can be seen from the comparison that the 5-hydroxymethylfurfural prepared in Example 1 has a typical standard 5-hydroxymethylfurfural hydrogen nuclear magnetic resonance spectrum.

[0100] Figure 3 The carbon nuclear magnetic resonance spectrum of 5-hydroxymethylfurfural prepared in Example 1 is as follows: Figure 3 and Figure 4 It can be seen from the comparison that the 5-hydroxymethylfurfural prepared in Example 1 has a typical standard 5-hydroxymethylfurfural carbon nuclear magnetic resonance spectrum.

[0101] The test results of 5-hydroxymethylfurfural in other embodiments are similar to the above, and standard 5-hydroxymethylfurfural is obtained through the present invention.

[0102] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a 5-hydroxymethylfurfural aqueous solution based on an intermittent reaction, characterized in that: The steps include: S1, reacting a mixed solution containing sugar-based biomass, inorganic salts, catalysts, organic solvents, and water to obtain an aqueous phase and an organic phase; The organic solvent is insoluble in water; S2, extracting the organic phase with water to obtain the 5-hydroxymethylfurfural aqueous solution.

2. The preparation method according to claim 1, characterized in that: In step S1, the mixed solution contains: 0.5-10 parts by weight of sugar-based biomass, 0.001-2 parts by weight of inorganic salt, 0.01-1 parts by weight of catalyst, 1-50 parts by weight of organic solvent, and 1-20 parts by weight of water.

3. The preparation method according to claim 1, characterized in that: The reaction conditions include: reaction temperature of 30 to 180° C., and reaction time of 2 to 10 hours.

4. The preparation method according to claim 1, characterized in that: The inorganic salt is selected from at least one of halogen compounds, borides, silicates, aluminates, phosphates, and borates; Preferably, the halogen compound includes at least one of sodium chloride, sodium fluoride, magnesium chloride, calcium chloride, barium chloride, chromium chloride, ferric chloride, copper chloride, aluminum chloride, sodium bromide, calcium bromide and magnesium bromide.

5. The preparation method according to claim 1, characterized in that: The sugar-based biomass is selected from at least one of glucose, fructose, xylose, mannose, galactose, lactose, sucrose, maltose, cellulose and starch; Preferably, the cellulose is selected from at least one of cellulose ether, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose and carboxymethyl cellulose.

6. The preparation method according to claim 1, characterized in that: The organic solvent is selected from at least one of isobutyl acrylate, butyl propionate, butyl butyrate, ethyl isobutyrate, ethyl lactate, butyl lactate, amyl lactate, diethyl maleate, dibutyl maleate, soybean oil, sunflower oil, sesame oil, peanut oil, olive oil, castor oil, cottonseed oil, and isopropyl palmitate.

7. The preparation method according to claim 1, characterized in that: The catalyst is selected from at least one of water-soluble acids, solid acid catalysts, alkoxyaluminum, phenoxyaluminum, tetrabutyl stannate, alkoxytitanium, alkoxyzirconium, ethyl antimonite, and butyl antimonite.

8. The preparation method according to claim 7, characterized in that: The water-soluble acid includes at least one of phosphoric acid, hydrochloric acid, sulfuric acid, and boric acid; Preferably, the solid acid catalyst is selected from at least one of a cation exchange resin, a molecular sieve having an acidic site, a sulfide, a natural clay mineral, an amorphous oxide, and a metal organic framework material.

9. The preparation method according to claim 1, characterized in that: The cation exchange resin is selected from sulfonic acid resin; Preferably, the molecular sieve having an acidic site is selected from at least one of ZSM-5 molecular sieve, TS-1 molecular sieve, 13X molecular sieve, and Y molecular sieve; Preferably, the natural clay mineral is selected from kaolin; Preferably, the metal organic framework material is selected from the metal organic framework material MIL-125.

10. The preparation method according to claim 1, characterized in that: In step S2, the volume ratio of water to organic phase is 1 to 3:1; Preferably, the extraction is performed 2 to 5 times.

Images