5-hydroxymethylfurfural and preparation method thereof
By using the synergistic effect of fructose, inorganic salts and acidic catalysts in a multi-tank series reactor, the problems of excessive black rot by-products and low selectivity in the production of 5-hydroxymethylfurfural were solved, and efficient and low-cost production of high-purity 5-hydroxymethylfurfural was achieved.
Patent Information
- Application Number
- CN202410330011.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-21
- Publication Date
- 2025-09-23
AI Technical Summary
The production of 5-hydroxymethylfurfural in the prior art has the problems of many black rot byproducts, low selectivity and low yield, resulting in high equipment maintenance costs and poor economic benefits.
A mixed solution containing fructose, an inorganic salt, an acidic catalyst and an organic solvent is reacted in a multi-tank series reactor. The occurrence of side reactions is suppressed through the synergistic effect of the inorganic salt and the acidic catalyst, and 5-hydroxymethylfurfural is separated and purified by extraction and reduced pressure distillation.
The production efficiency and conversion rate of the reaction are improved, the generation of by-products is reduced, equipment maintenance and labor costs are reduced, and the efficient production of high-purity 5-hydroxymethylfurfural is achieved.
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Abstract
Description
Technical Field
[0001] The present application relates to the field of chemical technology, and in particular to 5-hydroxymethylfurfural and a preparation method thereof. Background Art
[0002] 5-Hydroxymethylfurfural, as a bio-based chemical, holds significant importance in green chemistry and sustainable development. Its production and utilization help reduce dependence on non-renewable resources and promote sustainable production and consumption patterns. 5-Hydroxymethylfurfural can be used as a chemical raw material in the synthesis of many organic compounds, such as biodiesel, polymers, solvents, and chemicals. Its chemical properties make it an important precursor for the synthesis of other compounds. The production of chemicals from renewable biomass resources not only alleviates the increasingly scarce oil resources crisis but also provides a driving force for innovation in the development of new materials based on the unique structural properties of bio-based chemicals. Bio-based chemical synthesis routes using 5-Hydroxymethylfurfural (HMF) as a platform compound and subsequently converting it into other high-value-added derivatives are a promising future development direction. This series of products can be used to produce new biodegradable plastics, new polyurethanes, specialty nylons, new green solvents, and new oil additives.
[0003] The typical reaction format for the traditional production of 5-HMF (HMF) is a batch reactor. In batch reactions, production must be stopped after each reaction cycle to clean the equipment before the next batch can begin. These reactions typically require more manual intervention and downtime, potentially leading to lower production efficiency. Furthermore, batch systems often generate significant waste or become unstable during the start and end of batch production. This can lead to the formation of difficult-to-clean black rot products, which can hinder the continued progress of the reaction and reduce HMF yield. Various homogeneous and heterogeneous catalysts, including Lewis and Bronsted acids, have been developed and found to be effective for the synthesis of 5-HMF. These catalysts are widely used in the production of 5-HMF. However, due to the high reactivity of the 5-HMF produced during the reaction, these catalysts can cause it to undergo further reactions, polymerizing to form high-molecular-weight black rot products or decomposing to produce acetoacetic acid. The production of these byproducts can lead to low selectivity in the reaction, as well as corrosion and clogging of equipment, making it difficult to clean and making the reaction difficult to carry out. This significantly increases equipment maintenance and operating costs, resulting in poor economic returns. These shortcomings limit its potential industrial applications. Therefore, developing a multi-reactor tandem reaction format for HMF production has important industrial production significance and practical value. Summary of the Invention
[0004] In view of this, the present application provides a 5-hydroxymethylfurfural and a preparation method thereof, the main purpose of which is to solve the technical problems of 5-hydroxymethylfurfural having many black rot by-products, low selectivity and low yield.
[0005] In one aspect, the present application provides a method for preparing 5-hydroxymethylfurfural, comprising the following steps:
[0006] A mixed solution containing fructose, an inorganic salt, an acidic catalyst, an organic solvent and water reacts in a multi-tank series reactor to obtain the 5-hydroxymethylfurfural.
[0007] The present application adds inorganic salts and specific acidic catalysts, and reacts in a multi-reactor series mode, with each process condition acting synergistically; wherein, multi-reactor series can effectively improve the production efficiency and conversion rate of the reaction compared to a batch reaction; and it can also avoid the problem that the side reaction of 5-hydroxymethylfurfural forms black rot, which leads to a decrease in product yield and a significant increase in equipment maintenance costs. The system for synthesizing 5-hydroxymethylfurfural used in the present application has great economic benefits, low system cost, little environmental pollution, simple operation, easy repetition, low equipment maintenance cost, and can efficiently produce high-purity 5-hydroxymethylfurfural.
[0008] Optionally, the inorganic salt is selected from at least one of halogen compounds, borides, silicates, aluminates, phosphates and borates.
[0009] The boride of the present application is mainly a compound composed of boron and metal elements; borates mainly include boric acid groups, such as sodium borate and potassium borate.
[0010] Optionally, the halogen compound is selected from 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.
[0011] Optionally, the boride is at least one selected from boron fluoride, magnesium boride, titanium boride, chromium boride and calcium boride.
[0012] Optionally, the silicate is selected from at least one of sodium silicate, calcium silicate, magnesium silicate and ammonium silicate.
[0013] Optionally, the aluminate is selected from at least one of sodium aluminate, calcium aluminate, magnesium aluminate and ammonium aluminate.
[0014] Optionally, the borate is selected from at least one of sodium borate, calcium borate, magnesium borate and ammonium borate.
[0015] Optionally, the phosphate is selected from at least one of sodium phosphate, calcium phosphate, magnesium phosphate and ammonium phosphate.
[0016] Optionally, the organic solvent is selected from at least one of acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, methyl isobutyl ketone, dimethyl carbonate, ethyl acetate and ethylene glycol.
[0017] Optionally, the acidic catalyst comprises at least one acid soluble in water.
[0018] Optionally, the water-soluble acid is an acid that is readily soluble in water.
[0019] Optionally, the acidic catalyst is selected from at least one of phosphoric acid, hydrochloric acid, sulfuric acid, boric acid and p-toluenesulfonic acid.
[0020] Optionally, the hydrochloric acid is selected from a hydrochloric acid solution with a mass concentration of 35.0 to 40.0 wt%.
[0021] Optionally, the sulfuric acid is selected from concentrated sulfuric acid with a mass concentration of 95.0 to 99.0 wt%.
[0022] Optionally, the mass ratio of the fructose, the inorganic salt, the acid catalyst, the organic solvent and the water is 1:(0.001-2):(0.001-1):(0.5-20):(0.5-20).
[0023] Optionally, the mass ratio of the fructose to the inorganic salt is 1:0.05-2.
[0024] Optionally, the mass ratio of fructose to inorganic salt is selected from any value of 1:0.001, 1:0.005, 1:0.01, 1:0.05, 1:0.1, 1:0.2, 1:0.5, 1:0.8, 1:1, 1:1.5, 1:1.8, 1:2, or any range between two of them.
[0025] Optionally, the mass ratio of the fructose to the acidic catalyst is 1:0.001-0.05.
[0026] Optionally, the mass ratio of fructose to acid catalyst is selected from any value of 1:0.001, 1:0.002, 1:0.005, 1:0.01, 1:0.1, 1:0.2, 1:0.5, 1:0.1, 1:0.2, 1:0.5, 1:0.8, 1:1 or any range between two of them.
[0027] Optionally, the mass ratio of the fructose to the organic solvent is 1:0.8-10.
[0028] Optionally, the mass ratio of fructose to organic solvent is selected from any value among 1:0.5, 1:0.8, 1:1, 1:2, 1:5, 1:8, 1:10, 1:12, 1:15, 1:17, 1:18, 1:20 or any range between two values.
[0029] Optionally, the mass ratio of the fructose to the water is 1:0.8-10.
[0030] Optionally, the mass ratio of fructose to water is selected from any value among 1:0.5, 1:0.8, 1:1, 1:2, 1:5, 1:8, 1:10, 1:12, 1:15, 1:17, 1:18, 1:20, or any range value therebetween.
[0031] Optionally, the amount of the acid catalyst added is 0.1 wt% to 5 wt% of the amount of fructose added.
[0032] Optionally, the amount of the acid catalyst added is the mass percentage of the fructose added amount selected from any value among 0.1wt%, 0.2wt%, 0.5wt%, 0.8wt%, 1.0wt%, 1.5wt%, 2.0wt%, 2.5wt%, 3.0wt%, 3.5wt%, 4.0wt%, 4.5wt%, 5.0wt% or any range value between two of them.
[0033] Optionally, the reaction conditions include: a reaction temperature of 60 to 180° C., and a reaction residence time of 1 to 10 hours.
[0034] Optionally, 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 values.
[0035] Optionally, the reaction residence time is selected from any value of 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, or any range value therebetween.
[0036] Optionally, the reaction pressure is not particularly limited.
[0037] Optionally, the number of the multi-tank series reactors is 2 to 8.
[0038] Optionally, the number of the series reactors is selected from any value among 2, 3, 4, 5, 6, 7, 8, or a range between any two values.
[0039] Optionally, the method further comprises a purification step: after the reaction is completed, an extractant is added to the reaction solution to extract to obtain an upper extract, and the upper extract is subjected to reduced pressure distillation to obtain 5-hydroxymethylfurfural.
[0040] Optionally, the extraction process includes: adding the reaction solution obtained after the reaction to an extractant for extraction operation; after standing and shaking, the solution is separated into layers, the upper layer is an organic solution phase containing 5-hydroxymethylfurfural, after separating the upper layer, ethyl acetate or dimethyl carbonate is added again to the remaining lower layer solution for extraction, and the operation is repeated multiple times.
[0041] Optionally, the upper layer of ethyl acetate or dimethyl carbonate extract is subjected to reduced pressure distillation to recover the extraction solvent ethyl acetate or dimethyl carbonate, and simultaneously obtain the product 5-hydroxymethylfurfural.
[0042] Optionally, the detection method used is high performance liquid chromatography: 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 based on the concentration.
[0043] Optionally, the volume ratio of the extractant to the reaction solution is 1 to 3:1.
[0044] Optionally, the extractant is selected from ethyl acetate and / or dimethyl carbonate.
[0045] Optionally, the extraction is performed 2 to 5 times.
[0046] Optionally, the 5-hydroxymethylfurfural yield is detected by high performance liquid chromatography, and deionized water is added to mix and constant volume during detection.
[0047] Optionally, the conditions for the reduced pressure distillation include: vacuum degree of 0.01 to 5 KPa, temperature of 30 to 60° C., and time of 0.5 to 3 hours.
[0048] Optionally, the vacuum degree is selected from any value among 0.01KPa, 0.02KPa, 0.05KPa, 0.1KPa, 0.5KPa, 1KPa, 2KPa, 3KPa, 4KPa, 4.5KPa, 5KPa, or any range between any two values.
[0049] Optionally, the temperature is selected from any value among 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C or any range between two values.
[0050] Optionally, the time is selected from any value among 0.5 hours, 0.6 hours, 0.8 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, or any range between two of them.
[0051] Optionally, the yield of 5-hydroxymethylfurfural in the preparation method is greater than 80%.
[0052] Optionally, the yield of 5-hydroxymethylfurfural in the preparation method is between 80% and 95%.
[0053] The present application provides a specific embodiment of 5-hydroxymethylfurfural, including:
[0054] a) mixing a solution containing fructose, an inorganic salt, an acidic catalyst, an organic solvent, and water, and performing a multi-reactor series reaction to obtain the 5-hydroxymethylfurfural. The reaction temperature is between 60° C. and 180° C., the reaction time is between 1 and 10 hours, and the number of reactors in series is 2 to 8;
[0055] b) extracting the reaction solution from step a) multiple times with ethyl acetate or dimethyl carbonate, and then subjecting the ethyl acetate or dimethyl carbonate to reduced pressure distillation. The system vacuum is controlled at 0.01 to 5 kPa, the reaction temperature is between 30° C. and 60° C., and the reduced pressure distillation operation time is between 0.5 and 3 hours to obtain 5-hydroxymethylfurfural as a product.
[0056] The preparation route of the present application is to use raw materials containing fructose, inorganic salts, organic solvents and water, and obtain 5-hydroxymethylfurfural through a dehydration reaction under the catalytic action of an acidic catalyst. The added inorganic salts and the multi-reactor series reaction, which is different from the batch reaction, effectively inhibit the further side reactions of 5-hydroxymethylfurfural. No other impurities and black rot are generated after the reaction. After the reaction, dimethyl carbonate or ethyl acetate is used as an extractant to extract 5-hydroxymethylfurfural, and the extraction solvent and the product are recovered and separated by a reduced pressure distillation method. 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.
[0057] In a second aspect, the present application provides a 5-hydroxymethylfurfural, which is prepared using the above-mentioned preparation method.
[0058] Compared with the prior art, the advantages of this application include:
[0059] 1) The addition of organic and inorganic phases, the synergistic effect of specific inorganic salts and specific acid catalysts in the preparation process of 5-hydroxymethylfurfural provided in this application 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 preparation process of the present application adopts a multi-reactor series type, which is different from the system for synthesizing 5-hydroxymethylfurfural using an intermittent reactor reactor. It 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. BRIEF DESCRIPTION OF THE DRAWINGS
[0061] Figure 1 Schematic diagram of a multi-reactor series reaction device used in the examples of this application;
[0062] Figure 2 This is the H NMR spectrum of the product synthesized in Example 1 of the present application;
[0063] Figure 3 This is the H NMR spectrum of the 5-hydroxymethylfurfural standard in this application;
[0064] Figure 4 This is the carbon NMR spectrum of the product synthesized in Example 1 of the present application;
[0065] Figure 5 This is the carbon NMR spectrum of the 5-hydroxymethylfurfural standard in this application. DETAILED DESCRIPTION
[0066] The present application will be further described below in conjunction with specific embodiments. The following description is merely a few embodiments of the present application and does not limit the present application in any form. Although the present application discloses the preferred embodiments below, it is not intended to limit the present application. Any person skilled in the art who, without departing from the scope of the technical solution of the present application, makes slight changes or modifications using the above disclosed technical content is equivalent to an equivalent implementation case and falls within the scope of the technical solution.
[0067] Unless otherwise specified, the raw materials 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 an AVANCE II 400M liquid nuclear magnetic spectrometer produced by Bruker, and the reaction solution was dissolved in a deuterated reagent.
[0070] The yield of 5-hydroxymethylfurfural in the examples of the present application was calculated by the following method:
[0071] 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 based on the concentration.
[0072] The concentrations of concentrated sulfuric acid and hydrochloric acid used in the examples of this application are as follows:
[0073] Concentrated sulfuric acid: H2SO4 is 98.0wt%;
[0074] Hydrochloric acid: HCl is 37.0 wt%.
[0075] The preparation method of 5-hydroxymethylfurfural provided in the present application comprises the following steps:
[0076] a) mixing a solution containing fructose, an inorganic salt, an acidic catalyst, an organic solvent and water, and reacting the mixture in a multi-reactor series reaction mode to obtain the 5-hydroxymethylfurfural, wherein the reaction temperature is between 60° C. and 180° C., the reaction residence time is between 1 and 10 hours, and the number of series reaction reactors is 2 to 8.
[0077] b) taking a small amount of the reaction liquid after the reaction in step a) for liquid chromatography analysis to determine the yield of 5-hydroxymethylfurfural; adding ethyl acetate or dimethyl carbonate to the reaction liquid for multiple extraction operations, the number of extraction operations being 2 to 5 times; after the extraction is completed, performing a vacuum distillation operation to obtain the generated product 5-hydroxymethylfurfural, and connecting the device to a water pump or an oil pump to perform vacuum distillation, controlling the system vacuum degree to 0.01 to 5 kPa, the vacuum distillation temperature to 30 to 60° C., and the vacuum distillation operation time to 0.5 to 3 hours.
[0078] As a preferred embodiment of the above, the inorganic salt includes at least one of a halogen compound, a boride, a silicate, aluminate, a borate and a phosphate;
[0079] 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;
[0080] The boride comprises at least one of boron fluoride, magnesium boride, titanium boride, chromium boride and calcium boride;
[0081] The silicate includes at least one of sodium silicate, calcium silicate, magnesium silicate and ammonium silicate;
[0082] The aluminate includes at least one of sodium aluminate, calcium aluminate, magnesium aluminate and ammonium aluminate;
[0083] The borate includes at least one of sodium borate, calcium borate, magnesium borate and ammonium borate;
[0084] The phosphate includes at least one of sodium phosphate, calcium phosphate, magnesium phosphate, and ammonium phosphate.
[0085] The acidic catalyst includes at least one of water-soluble acids such as phosphoric acid, hydrochloric acid, sulfuric acid and p-toluenesulfonic acid; the water-soluble acid includes at least one of sulfuric acid and sulfonic acid.
[0086] The organic solvent includes at least one of acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, methyl isobutyl ketone, dimethyl carbonate, ethyl acetate and ethylene glycol.
[0087] As a preference of the above embodiment, the mass ratio of fructose, inorganic salt, acid catalyst, organic solvent and water is 1:(0.001-2):(0.001-1):(0.5-20):(0.5-20).
[0088] As a preference of the above embodiment, the mass ratio of fructose to the inorganic salt is 1:0.05-2; the mass ratio of fructose to the acidic catalyst is 1:0.001-0.05; the mass ratio of fructose to the organic solvent is 1:0.8-10; and the mass ratio of fructose to water is 1:0.8-10.
[0089] Example 1
[0090] 7g of fructose, 3g of sodium chloride, 5g of tetrahydrofuran, and 8g of water were added to a container. 0.2g of concentrated sulfuric acid was added dropwise while stirring as a catalyst. After the raw materials were fully dissolved, the mixture was heated to 100°C in a multi-reactor reactor with four reactors in series. The reaction was allowed to proceed for 6 hours, and the color of the reaction solution gradually deepened. After the reaction, a small amount of the reaction solution was analyzed by high-performance liquid chromatography (HPLC), revealing an 81% yield of 5-hydroxymethylfurfural with a selectivity of 93%. Dimethyl carbonate (4:1 by volume) was added to the reaction solution, and extraction was performed four times. The extract was then connected to a water or oil pump for vacuum distillation. The vacuum was maintained at 1.5 kPa, the distillation temperature was kept at 45°C, and the distillation time was kept at 2 hours. The resulting 5-hydroxymethylfurfural had a purity of 98%.
[0091] Example 2
[0092] 5g of fructose, 1g of aluminum chloride, 10g of acetonitrile, and 5g of water were added to a container. 0.2g of phosphoric acid was added as a catalyst while stirring. After the raw materials were fully dissolved, the reaction mixture was heated to 120°C in a two-pot series reactor. The reaction was allowed to proceed for 3 hours, and the color of the reaction solution gradually deepened. After the reaction, a small amount of the reaction solution was analyzed by high-performance liquid chromatography (HPLC), revealing a 90% yield of 5-hydroxymethylfurfural with a selectivity of 96%. Dimethyl carbonate (3:1 by volume) was added to the reaction solution, and extraction was performed five times. After the extraction, the extract was connected to a water or oil pump for vacuum distillation. The vacuum was maintained at 2 kPa, the vacuum distillation temperature was maintained at 45°C, and the vacuum distillation time was maintained at 2 hours. The resulting 5-hydroxymethylfurfural had a purity of 97%.
[0093] Examples 3 to 11
[0094] The specific ingredients, materials and reaction conditions are shown in Table 1 below. Other operations during the synthesis process are the same as in Example 1.
[0095] Table 1. Raw material composition, proportions and vacuum distillation conditions of Examples 3 to 11
[0096]
[0097]
[0098] Example 12
[0099] 3g of fructose, 8g of water, 5g of tetrahydrofuran, and 1g of sodium chloride were added to a container. 0.1g of hydrochloric acid was added as a catalyst while stirring. Two reactors were connected in series, and the temperature was raised to 120°C via a heat exchanger. The reaction was held for 3 hours, and the color of the reaction solution gradually deepened. After the reaction, a small amount of the reaction solution was analyzed by high-performance liquid chromatography (HPLC). The results showed an 82% yield of 5-hydroxymethylfurfural with a selectivity of 93%. Ethyl acetate (3:1 by volume) was added to the reaction solution, and extraction was performed five times. After the extraction, the extract was connected to a water or oil pump for vacuum distillation. The vacuum level of the system was maintained at 2 kPa, the vacuum distillation temperature was maintained at 40°C, and the vacuum distillation operation time was maintained at 2 hours. The resulting 5-hydroxymethylfurfural had a purity of 96%.
[0100] Example 13
[0101] 2g of fructose, 10g of water, 5g of tetrahydrofuran, and 1g of sodium chloride were added to a container. 0.05g of sulfuric acid was added as a catalyst while stirring. In a multi-reactor series reactor with four reactors connected in series, the temperature was raised to 120°C via a heat exchanger. The reaction was allowed to proceed for 2 hours, and the color of the reaction solution gradually deepened. After the reaction, a small amount of the reaction solution was analyzed by high-performance liquid chromatography (HPLC), which showed an 88% yield of 5-hydroxymethylfurfural with a selectivity of 94%. Dimethyl carbonate (4:1 by volume) was added to the reaction solution, and extraction was performed twice. After the extraction, the extract was connected to a water or oil pump for vacuum distillation. The vacuum level of the system was maintained at 2 kPa, the vacuum distillation temperature was maintained at 40°C, and the vacuum distillation operation time was maintained at 2 hours. The resulting 5-hydroxymethylfurfural had a purity of 93%.
[0102] Comparative Example 1
[0103] The difference between Comparative Example 1 and Example 12 is that the reaction is carried out in a single batch reactor that is not connected in series.
[0104] The specific operation includes: adding 3g fructose, 8g water, 5g tetrahydrofuran, and 1g sodium chloride, adding 0.1g hydrochloric acid as a catalyst while stirring, raising the temperature to 120°C, and reacting for 3 hours. The color of the reaction solution gradually deepens. After the reaction is completed, a small amount of the reaction solution is taken for high-performance liquid chromatography analysis. The results show that the yield of 5-hydroxymethylfurfural is 71% and the selectivity is 82%. Ethyl acetate is added to the reaction solution (the volume ratio of ethyl acetate to reaction solution is 3:1) and multiple extraction operations are performed. The number of extractions is 5 times. After the extraction is completed, the extract is connected to a water pump or oil pump for vacuum distillation. The system vacuum is controlled at 2kPa, the vacuum distillation temperature is between 40°C, and the vacuum distillation operation time is between 2 hours. The resulting 5-hydroxymethylfurfural has a purity of 87%.
[0105] Comparative Example 2
[0106] The difference between Comparative Example 2 and Example 13 is that no inorganic salt is added to the reactants.
[0107] The specific procedure involves adding 2g of fructose, 10g of water, and 5g of tetrahydrofuran to a container. While stirring, 0.05g of sulfuric acid was added as a catalyst. In a multi-reactor series reactor, four reactors were connected in series. The temperature was raised to 120°C via a heat exchanger and the reaction was allowed to proceed for two hours, with the color of the reaction solution gradually deepening. After the reaction, a small amount of the reaction solution was analyzed by high-performance liquid chromatography (HPLC), which revealed a 79% yield of 5-hydroxymethylfurfural with an 85% selectivity. Dimethyl carbonate (4:1 by volume) was added to the reaction solution, and extraction was performed twice. After the extraction, the extract was connected to a water or oil pump for vacuum distillation. The vacuum was maintained at 2 kPa, the vacuum distillation temperature was maintained at 40°C, and the vacuum distillation time was maintained at 2 hours. The resulting 5-hydroxymethylfurfural had a purity of 89%.
[0108] Example 14 Liquid NMR Analysis
[0109] The 5-hydroxymethylfurfural prepared in Examples 1 to 13 was subjected to liquid nuclear magnetic resonance analysis. 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 spectrum.
[0110] Figure 3The 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.
[0111] The test results of 5-hydroxymethylfurfural in other examples are similar to those described above, and standard 5-hydroxymethylfurfural is obtained through this application.
[0112] After testing, the yield of 5-hydroxymethylfurfural prepared in Examples 1-13 of the present application was between 80% and 95%, the selectivity was between 93% and 96%, and the purity was between 93% and 99%.
[0113] Comparison of Example 12 and Comparative Example 1 shows that, under identical reaction conditions, Comparative Example 1 employs a batch reactor, and the yield of 5-hydroxymethylfurfural produced is 71%, the selectivity is 82%, and the purity is 87%. Example 12 employs two reactors connected in series, and the yield of 5-hydroxymethylfurfural produced is 82%, the selectivity is 93%, and the purity is 96%. This demonstrates that the present application utilizes a series of reactors to produce 5-hydroxymethylfurfural, resulting in a stable, continuous, and efficient production process that reduces byproduct generation, improves production efficiency, enhances product quality, and further increases the yield, selectivity, and purity of 5-hydroxymethylfurfural.
[0114] By comparing Example 13 and Comparative Example 2, it can be seen that under the same reaction conditions, an inorganic salt is added to the reactants of Example 13, and the yield of the prepared 5-hydroxymethylfurfural is 88%, the selectivity is 94%, and the purity is 93%; in Comparative Example 2, no inorganic salt is added, and the yield of the prepared 5-hydroxymethylfurfural is 79%, the selectivity is 85%, and the purity is 89%, indicating that the addition of an inorganic salt to the reactants in this application can improve the yield and selectivity of 5-hydroxymethylfurfural.
[0115] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present 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 5-hydroxymethylfurfural, characterized in that, The preparation method comprises the following steps: A mixed solution containing fructose, an inorganic salt, an acidic catalyst, an organic solvent and water reacts in a multi-tank series reactor to obtain the 5-hydroxymethylfurfural.
2. A method for preparing 5-hydroxymethylfurfural 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 is selected from 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; Preferably, the boride is at least one selected from boron fluoride, magnesium boride, titanium boride, chromium boride and calcium boride; Preferably, the silicate is selected from at least one of sodium silicate, calcium silicate, magnesium silicate and ammonium silicate; Preferably, the aluminate is selected from at least one of sodium aluminate, calcium aluminate, magnesium aluminate and ammonium aluminate; Preferably, the phosphate is selected from at least one of sodium phosphate, calcium phosphate, magnesium phosphate and ammonium phosphate; Preferably, the borate is selected from at least one of sodium borate, calcium borate, magnesium borate and ammonium borate.
3. A method for preparing 5-hydroxymethylfurfural according to claim 1, characterized in that, The organic solvent is selected from at least one of acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, methyl isobutyl ketone, dimethyl carbonate, ethyl acetate and ethylene glycol.
4. A method for preparing 5-hydroxymethylfurfural according to claim 1, characterized in that, The acidic catalyst includes a water-soluble acid; Preferably, the acid catalyst is selected from at least one of phosphoric acid, hydrochloric acid, sulfuric acid, boric acid and p-toluenesulfonic acid; Preferably, the hydrochloric acid is selected from a hydrochloric acid solution with a mass concentration of 35.0 to 40.0 wt%; Preferably, the sulfuric acid is selected from concentrated sulfuric acid with a mass concentration of 95.0 to 99.0 wt%.
5. The method for preparing 5-hydroxymethylfurfural according to claim 1, wherein The mass ratio of the fructose, the inorganic salt, the acid catalyst, the organic solvent and the water is 1:(0.001-2):(0.001-1):(0.5-20):(0.5-20); Preferably, the mass ratio of the fructose to the inorganic salt is 1:0.05-2; Preferably, the mass ratio of the fructose to the acidic catalyst is 1:0.001-0.05; Preferably, the mass ratio of the fructose to the organic solvent is 1:0.8-10; Preferably, the mass ratio of the fructose to the water is 1:0.8-10.
6. The method for preparing 5-hydroxymethylfurfural according to claim 1, wherein The reaction conditions include: reaction temperature of 60 to 180° C., and reaction residence time of 1 to 10 hours.
7. The method for preparing 5-hydroxymethylfurfural according to claim 1, wherein The number of the multi-tank series reactors is 2 to 8.
8. The method for preparing 5-hydroxymethylfurfural according to claim 1, wherein The method further comprises a purification step: After the reaction is completed, an extractant is added to the reaction solution to extract and obtain an upper extract. The upper extract is distilled under reduced pressure to obtain 5-hydroxymethylfurfural.
9. The method for preparing 5-hydroxymethylfurfural according to claim 8, wherein The volume ratio of the extractant to the reaction solution is 1 to 3:1; Preferably, the extractant is selected from ethyl acetate and / or dimethyl carbonate; Preferably, the extraction is performed 2 to 5 times; Preferably, the conditions for the reduced pressure distillation include: vacuum degree of 0.01 to 5 KPa, temperature of 30 to 60° C., and time of 0.5 to 3 hours.
10. A 5-hydroxymethylfurfural, characterized in that The invention is prepared by the preparation method according to any one of claims 1 to 9.