Method for continuously preparing 5-hydroxymethylfurfural aqueous solution

Abstract

The invention discloses a method for continuously preparing a 5-hydroxymethylfurfural aqueous solution. Comprising the following steps: mixing a glycosyl biomass raw material, an inorganic salt, an acidic catalyst, an organic solvent and water, enabling the solution to flow through a heat exchanger, continuously reacting, and extracting the reacted organic phase by using water as an extracting agent after the reaction to obtain a water solution of 5-hydroxymethylfurfural; according to the method, the added organic solvent can effectively promote the 5-hydroxymethylfurfural to enter an organic phase in the generation process and inhibit the generation of a side reaction of generating black rot substances, the production efficiency and the conversion rate of the reaction can be effectively improved in a continuous reaction mode compared with a batch-type reaction mode, a water solution of the 5-hydroxymethylfurfural is obtained through water phase extraction, and the yield of the 5-hydroxymethylfurfural is improved. High-energy-consumption operation processes such as reduced pressure distillation are not needed, and the organic solvent can be recycled.

Description

Technical Field

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

[0002] 5-Hydroxymethylfurfural (5-HMF) is an organic compound with the chemical name 5-Hydroxymethylfurfural. It is a product obtained by the furfural reaction of biomass such as sugars or cellulose under acidic conditions. 5-HMF is an important bio-based chemical with a wide range of applications. 5-HMF is a solid with strong solubility and can be dissolved in water and organic solvents. 5-HMF shows high reactivity in chemical reactions and can undergo a series of chemical reactions, such as addition reactions, oxidation reactions, methylation reactions, etc. In addition, 5-HMF is considered to be a promising biofuel that can be converted into compounds such as 2,5-dimethylfuran through hydrogenation reactions and used as a substitute for biodiesel. Studies have shown that 5-HMF has biological activities such as antioxidant, anti-inflammatory and antibacterial activities, so it has the potential to be developed in the medical field and can be used to treat inflammatory diseases, cancer, etc. -HMF is one of the main components of caramel and can be used to add color, aroma and taste to food and beverages. In addition, it can also be used as a food preservative and sweetener. In summary, 5-HMF is a versatile compound with a wide range of applications. With the increasing demand for renewable resources, 5-HMF is becoming increasingly important as a bio-based chemical with promising applications in the fields of chemical, energy, medicine and food.

[0003] Acid catalysis is one of the most commonly used methods for producing 5-HMF. Acidic catalysts (such as sulfuric acid, aluminum chloride, etc.) act on waste biomass containing sugars or cellulose, and hydrolysis and dehydration reactions are carried out at appropriate reaction temperatures and pressures to generate 5-HMF. The typical reaction form for the traditional production of 5-hydroxymethylfurfural is to use an intermittent reactor. The reactor requires a large amount of labor cost and time, and black rotten substances that are difficult to clean are more likely to appear during the reaction, affecting the continued progress of the reaction and causing a decrease in the yield of HMF. However, since the 5-hydroxymethylfurfural generated during the reaction has a high reactivity, under the catalytic action of such catalysts, 5-hydroxymethylfurfural will further react, polymerize to generate high-molecular black rotten substances or decompose to generate acetoacetic acid, etc. The generation of these by-products will result in a 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 resulting in poor economic benefits. These shortcomings limit its potential industrial applications.

[0004] 5-HMF can be further deeply oxidized in the aqueous phase to prepare furandicarboxylic acid, a bio-based raw material with important uses. Therefore, directly preparing an aqueous solution of 5-HMF has great production and economic value, without the need for traditional energy-intensive extraction and vacuum distillation operations to obtain 5-HMF crystals, which are then dissolved in the aqueous phase for deep oxidation. Summary of the invention

[0005] According to one aspect of the present application, a method for preparing a 5-hydroxymethylfurfural aqueous solution in a continuous manner is provided, wherein a solution containing a sugar-based biomass raw material flows through a heat exchanger, reacts in a continuous manner, and 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. The method can effectively promote the entry of 5-hydroxymethylfurfural into the organic phase during the generation process by adding an organic solvent, inhibit the occurrence of a side reaction of generating black rot, and react in a continuous manner. Compared with an intermittent reaction, the production efficiency and conversion rate of the reaction can be further effectively improved. The aqueous solution of 5-hydroxymethylfurfural is obtained by aqueous phase extraction, and high energy consumption operation processes such as reduced pressure distillation are not required, and the organic solvent can be reused.

[0006] This application adopts the following technical solutions:

[0007] A method for continuously preparing a 5-hydroxymethylfurfural aqueous solution comprises the following steps:

[0008] S1, passing a mixed solution containing sugar-based biomass, inorganic salt, acidic catalyst, organic solvent and water through a heat exchanger to react and obtain mutually incompatible aqueous phase and organic phase;

[0009] S2, extracting the organic phase with water to obtain the 5-hydroxymethylfurfural aqueous solution.

[0010] Optionally, the organic solvent is insoluble in water.

[0011] Optionally, in step S1, the mixed solution contains:

[0012] 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 acidic catalyst, 1-20 parts by weight of organic solvent, and 1-20 parts by weight of water.

[0013] Optionally, the mass ratio of the sugar-based biomass to water is 0.5-10:1-20.

[0014] Optionally, the mass ratio of the glycosyl biomass to water is 5-10:5-20.

[0015] Optionally, the mass ratio of the glycosyl biomass to water is 8-10:6-20.

[0016] Optionally, the mass ratio of the sugar-based biomass to water is 5-10:10-20.

[0017] Optionally, the mass ratio of the sugar-based biomass to water is 10:15-20.

[0018] Optionally, the mass ratio of the sugar-based biomass to the acidic catalyst is 0.5-10:0.01-1.

[0019] Optionally, the mass ratio of the sugar-based biomass to the acidic catalyst is 8-10:0.01-1.

[0020] Optionally, the mass ratio of the sugar-based biomass to the acidic catalyst is 10:0.01-1.

[0021] Optionally, the mass ratio of the glycosyl biomass to the inorganic salt is 0.5-10:0.001-2;

[0022] Optionally, the mass ratio of the glycosyl biomass to the inorganic salt is 5-10:0.05-2;

[0023] Optionally, the mass ratio of the glycosyl biomass to the inorganic salt is 8-10:0.5-2;

[0024] Optionally, the mass ratio of the glycosyl biomass to the inorganic salt is 8-10:1-2.

[0025] Optionally, the mass ratio of the sugar-based biomass to the organic solvent is 0.5-10:1-20;

[0026] Optionally, the mass ratio of the sugar-based biomass to the organic solvent is 5-10:5-20;

[0027] Optionally, the mass ratio of the sugar-based biomass to the organic solvent is 8-10:6-20;

[0028] Optionally, the mass ratio of the sugar-based biomass to the organic solvent is 5-10:10-20;

[0029] Optionally, the mass ratio of the sugar-based biomass to the organic solvent is 10:15-20.

[0030] Optionally, the weight ratio of sugar-based biomass, acidic catalyst, organic solvent and water in the mixed solution is 1:(0.001-0.05):(0.8-10):(0.8-10).

[0031] Optionally, the weight ratio of glycosyl biomass to organic solvent in the mixed solution is selected from any value of 1:0.8, 1:0.9, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10 or any range therebetween.

[0032] Optionally, the weight ratio of glycosyl biomass to water in the mixed solution is selected from any value of 1:0.8, 1:0.9, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10 or any range therebetween.

[0033] Optionally, the weight ratio of the glycosyl biomass to the acidic catalyst in the mixed solution is selected from any value of 1:0.1, 1:0.2, 1:0.8, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5 or any range therebetween.

[0034] Optionally, the weight ratio of the inorganic salt to water in the mixed solution is 0.05 to 2:1.

[0035] Optionally, the weight ratio of the inorganic salt to water in the mixed solution is selected from any value of 1:0.05, 1:0.08, 1:0.1, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2 or any range therebetween.

[0036] Optionally, the reaction conditions include: reaction temperature of 60 to 180° C., reaction time of 2 to 10 h, and flow rate of the mixed solution of 0.1 to 20 L / min.

[0037] Optionally, the reaction conditions include: the reaction temperature is selected from any value among 60°C, 70°C, 80°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 175°C, 180°C, or any range between two thereof; the reaction time is selected from any value among 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, or any range between two thereof.

[0038] Optionally, the reaction conditions include: the flow rate of the mixed solution is selected from any value among 0.1L / min, 0.3L / min, 0.5L / min, 1L / min, 3L / min, 5L / min, 9L / min, 12L / min, 15L / min, 19L / min, 20L / min or any range between two values.

[0039] Optionally, the sugar-based biomass is selected from at least one of glucose, fructose, xylose, mannose, galactose, lactose, sucrose, maltose, cellulose and starch;

[0040] Optionally, the cellulose is selected from at least one of cellulose ether, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose and carboxymethyl cellulose.

[0041] 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.

[0042] Optionally, the inorganic salt is selected from at least one of halogen compounds, borides, silicates, aluminates, phosphates and borates.

[0043] 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.

[0044] Optionally, the boride includes at least one of boron fluoride, magnesium boride, titanium boride, chromium boride and calcium boride.

[0045] Optionally, the silicate includes at least one of sodium silicate, calcium silicate, magnesium silicate, ammonium silicate and the like.

[0046] Optionally, the aluminate includes at least one of sodium aluminate, calcium aluminate, magnesium aluminate, ammonium aluminate and the like.

[0047] Optionally, the phosphate includes at least one of sodium phosphate, calcium phosphate, magnesium phosphate, ammonium phosphate and the like.

[0048] Optionally, the acidic catalyst is selected from at least one of phosphoric acid, hydrochloric acid, sulfuric acid, boric acid and p-toluenesulfonic acid.

[0049] Optionally, the hydrochloric acid is a 35.0-40.0 wt % hydrochloric acid solution.

[0050] Optionally, the sulfuric acid is 95.0-99.0 wt % concentrated sulfuric acid.

[0051] Optionally, in step S2, the volume ratio of water to organic phase is 1 to 3:1.

[0052] Optionally, in step S2, the volume ratio of water to the organic phase is selected from any value of 1:1, 1:1.5, 2:1, 2.5:1, 3:1, or any range therebetween.

[0053] Optionally, the extraction is performed 2 to 5 times.

[0054] 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.

[0055] Optionally, in the preparation method, the yield of 5-hydroxymethylfurfural in an organic solvent is greater than 80%.

[0056] Optionally, in the preparation method, the extraction efficiency of 5-hydroxymethylfurfural in the organic solvent after the water extraction reaction is 80% to 95%.

[0057] The preparation route of the present application is to mix a sugar-based biomass raw material, an inorganic salt, an acidic catalyst, an organic solvent and water, and the solution flows through a heat exchanger to react in a continuous manner. After the reaction, water is used as an extractant to extract the organic solvent phase after the reaction to obtain an aqueous solution of 5-hydroxymethylfurfural. The added inorganic salt and the homogeneous continuous reaction, which is different from the intermittent reaction, effectively inhibit further side reactions of 5-hydroxymethylfurfural. After the reaction, no other impurities and black rot are generated. After the reaction, water is used as an extractant to extract 5-hydroxymethylfurfural, and there is no need to use high-energy consumption methods such as reduced pressure distillation to achieve recovery and separation of the organic solvent and the product to obtain an aqueous solution of 5-hydroxymethylfurfural.

[0058] The beneficial effects of this application include:

[0059] (1) The present application provides a method for continuously preparing an aqueous solution of 5-hydroxymethylfurfural. Compared with the traditional method, the preparation process of the present application uses sugar-based biomass as a raw material, and the added organic and inorganic phases, specific organic solvents, and the synergistic effect of inorganic salts and specific acid catalysts can effectively control the occurrence of side reactions, avoid the production of black rot, improve the selectivity of the reaction, and greatly reduce equipment maintenance and labor costs.

[0060] (2) The present application provides a method for continuously preparing an aqueous solution of 5-hydroxymethylfurfural, which is a homogeneous continuous method. Different from the system of synthesizing 5-hydroxymethylfurfural in an intermittent tank reactor, the method has greater economic benefits, lower system cost, less environmental pollution, simple operation, easy repetition, low equipment maintenance cost, and can efficiently produce high-purity 5-hydroxymethylfurfural.

[0061] (3) The present application provides a method for continuously preparing a 5-hydroxymethylfurfural aqueous solution. 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 vacuum distillation operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is the hydrogen nuclear magnetic spectrum of the product synthesized in Example 1 of the present application.

[0063] Figure 2 This is the hydrogen nuclear magnetic spectrum of 5-hydroxymethylfurfural standard.

[0064] Figure 3 This is the carbon nuclear magnetic resonance spectrum of the product synthesized in Example 1 of the present application.

[0065] Figure 4 This is the carbon NMR spectrum of 5-hydroxymethylfurfural standard. DETAILED DESCRIPTION

[0066] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0067] Unless otherwise specified, the raw materials and catalysts in the examples of this application were purchased through commercial channels.

[0068] The analysis method in the examples of this application is as follows:

[0069] 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.

[0070] 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.

[0071] The 5-hydroxymethylfurfural yield and water extraction efficiency were tested by high performance liquid chromatography, and deionized water was added to mix and set the volume during the test.

[0072] In the examples of the present application, the yield of 5-hydroxymethylfurfural is calculated in the following manner:

[0073] 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.

[0074] In the examples of the present application, the concentrations of concentrated sulfuric acid and hydrochloric acid used are described as follows:

[0075] Concentrated sulfuric acid: H SO is 98.0wt%;

[0076] Hydrochloric acid: HCl is 37.0 wt%.

[0077] The yield, selectivity and extraction efficiency of 5-hydroxymethylfurfural in the examples of the present application are calculated as follows:

[0078] Yield of 5-hydroxymethylfurfural = number of moles of 5-hydroxymethylfurfural produced / number of moles of reaction substrate added

[0079] Selectivity of 5-hydroxymethylfurfural = number of moles of 5-hydroxymethylfurfural produced / number of moles of reaction substrate involved in the reaction

[0080] 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.

[0081] Example 1

[0082] 8g fructose, 1.2g sodium chloride, 4g soybean oil, and 5g water were added to the container, and 0.08g concentrated sulfuric acid was added as a catalyst under stirring. After the raw materials were fully dissolved, the temperature was raised to 110°C through the heat exchanger at a flow rate of 3L / min. The continuous reaction time was 3 hours, and the color of the reaction liquid gradually deepened. After the reaction, a small amount of organic phase was taken for high-performance liquid chromatography analysis. The results showed that the yield of 5-hydroxymethylfurfural was 81% and the selectivity was 94%. Water (the volume ratio of water to reaction liquid was 3:1) was used in the organic phase after the reaction for multiple extraction operations. The number of extractions was 2 times. After the extraction was completed, an extract was obtained, and the extraction efficiency was 87%. The obtained 5-hydroxymethylfurfural aqueous solution.

[0083] Example 2

[0084] 10g carboxymethyl cellulose, 1.5g aluminum chloride, 8g dibutyl maleate, and 3g water were added to the container, and 0.15g hydrochloric acid was added as a catalyst under stirring. After the raw materials were fully dissolved into a homogeneous phase, the mixture was passed through a heat exchanger at a flow rate of 12L / min, and the temperature was raised to 130°C. The continuous reaction time was 2 hours, and the color of the reaction liquid gradually deepened. After the reaction, a small amount of organic phase was taken for high-performance liquid chromatography analysis. The results showed that the yield of 5-hydroxymethylfurfural was 91% and the selectivity was 96%. Water was added to the organic phase after the reaction (the volume ratio of water to the reaction liquid was 2:1) for multiple extraction operations. The number of extractions was 4 times, and the extraction efficiency was 91%. After the extraction was completed, a 5-hydroxymethylfurfural aqueous solution was obtained.

[0085] Embodiments 3 to 11

[0086] 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.

[0087] Table 1 Raw material composition, ratio and water extraction conditions of Examples 3 to 11

[0088]

[0089] Example 12 Liquid NMR Analysis

[0090] 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.

[0091] 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.

[0092] The test results of 5-hydroxymethylfurfural in other embodiments are similar to the above, and standard 5-hydroxymethylfurfural is obtained through the present invention.

[0093] 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 continuously preparing a 5-hydroxymethylfurfural aqueous solution, characterized in that: The steps include: S1, passing a mixed solution containing sugar-based biomass, inorganic salt, acidic catalyst, organic solvent and water through a heat exchanger to react and obtain mutually incompatible aqueous phase and organic phase; S2, extracting the organic phase with water to obtain the 5-hydroxymethylfurfural aqueous solution.

2. The 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 acidic catalyst, 1-20 parts by weight of organic solvent, and 1-20 parts by weight of water.

3. The method according to claim 1, characterized in that The reaction conditions include: reaction temperature of 60-180° C., reaction time of 2-10 h, and flow rate of the mixed solution of 0.1-20 L / min.

4. The 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.

5. The 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.

6. The method according to claim 5, characterized in that The cellulose is selected from at least one of cellulose ether, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose and carboxymethyl cellulose.

7. The 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.

8. The method according to claim 1, characterized in that The acidic catalyst is selected from at least one of phosphoric acid, hydrochloric acid, sulfuric acid, boric acid and p-toluenesulfonic acid.

9. The method according to claim 1, characterized in that: In the step S2, the volume ratio of water to the organic solvent is 1 to 3:

1.

10. The method according to claim 1, characterized in that In the step S2, the extraction is performed 2 to 5 times.

Images