A process and apparatus for the continuous synthesis of 5-hydroxymethylfurfural in two phases

Abstract

The application provides a method for continuously synthesizing 5-hydroxymethylfurfural in two phases, and belongs to the technical field of organic synthesis; in the method, an inorganic salt commonly used in industry is selected as a water phase density regulator, the system density and the distribution coefficient between the two phases can be changed, and the method has the advantages of being simple and easy to obtain, good stability, low cost and the like; a phase transfer catalyst is added in the reaction system, the mass transfer process of the reaction medium in the system can be adjusted in real time, the reaction rate of the two phases in the countercurrent process is accelerated, and the production efficiency is improved; in the method, the water phase mixed solution containing the catalyst, the water phase density regulator, the phase transfer catalyst and the like is recycled and applied after impurity removal, the removed solvent can also participate in the reaction after being recycled, the continuous production of HMF is realized, the production cost is reduced, and the economic applicability of industrial production is met.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and in particular to a method and apparatus for the two-phase continuous synthesis of 5-hydroxymethylfurfural. Background Technology

[0002] With the increasing consumption of non-renewable petrochemical resources such as coal and oil, it is urgent to develop biomass resources with characteristics such as renewability, reduced carbon emissions, and environmental friendliness.

[0003] 5-Hydroxymethylfurfural (HMF) is an important chemical that can be prepared by hydrolysis of cellulose biomass. Because it contains an aldehyde group and a hydroxymethyl group in its structure, it can be used to prepare a variety of derivatives through different chemical reactions such as hydrogenation, oxidation, esterification, halogenation, polymerization, and hydrolysis. Therefore, HMF is one of the most important platform compounds, and its derivatives can be used in the fields of medicine, fine chemicals, biodegradable plastics, and fuels.

[0004] Currently, HMF's main application markets are in fine chemicals and bio-based environmentally friendly functional materials. Furthermore, EU regulations have included HMF in the list of food flavorings, indicating promising prospects in the flavoring industry. Simultaneously, experiments have shown that HMF, when used in animal feed, can improve the immunity of animals and fish, and has antibacterial and anti-inflammatory effects, suggesting its potential application in animal feed. In addition, HMF possesses pharmacological effects such as antioxidant and antitumor activity.

[0005] HMF and its derivatives are located in the midstream of the bio-based materials industry chain, and can be used to synthesize a variety of organic compounds and novel polymer materials, including pharmaceuticals, resin plastics, and diesel fuel additives. The main derivatives of HMF currently include 2,5-furandicarboxylic acid (FDCA), 2,5-tetrahydrofurandimethylethanol (THFDM), 2,5-furandimethylethanol (FDM), and 2,5-furandicarboxaldehyde (DFF). Among these, FDCA has the largest potential market and has been proposed as a substitute for terephthalic acid in polyester production. FDCA is further used to prepare bio-based PEF polyesters. Compared with petroleum-based PET (polyethylene terephthalate), PEF polyesters have many advantages such as biodegradability, recyclability, lightweight, and superior CO2 barrier and water resistance, so FDCA and HMF have significant market application prospects.

[0006] Although HMF has significant potential applications, its high cost limits its practical use, primarily due to the combination of technical challenges in multiple stages, including reaction, separation, and purification. Therefore, how to achieve low-cost, large-scale production of HMF has long been an unresolved problem in the international chemical industry.

[0007] The main method for synthesizing HMF is through acid-catalyzed dehydration of monosaccharide raw materials. Currently, industrial production of HMF mostly employs batch production. Although this method is relatively mature, it suffers from low production efficiency, uses a single type of raw material, and is not conducive to large-scale industrial production. Summary of the Invention

[0008] In view of this, the purpose of this invention is to provide a method and apparatus for the continuous two-phase synthesis of 5-hydroxymethylfurfural. This invention realizes the continuous production of 5-hydroxymethylfurfural, reduces production costs, and is suitable for industrial production.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] This invention provides a two-phase continuous synthesis method for 5-hydroxymethylfurfural, comprising the following steps:

[0011] 1) The aqueous phase and oil phase are preheated separately and then mixed in countercurrent contact to carry out a dehydration reaction, resulting in the reacted oil phase and the reacted aqueous phase;

[0012] The raw materials in the aqueous and / or oil phases contain hydrophilic solvents; the raw materials in the aqueous phases also include raw sugar, catalyst, and water; the raw materials in the oil phases also include lipophilic solvents.

[0013] 2) After removing the solvent from the oil phase after the reaction, 5-hydroxymethylfurfural is obtained. The removed solvent can be added back to the oil phase of step 1) for recycling.

[0014] 3) After removing impurities from the aqueous phase following the reaction, it can be added back to the aqueous phase from step 1) for reuse;

[0015] Preferably, the raw sugar in step 1) is at least one of fructose, glucose, starch, inulin, sucrose, maltose, high-fructose corn syrup, cellulose, and galactose.

[0016] Preferably, the catalyst in step 1) is at least one selected from sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, trifluoromethanesulfonic acid, methanesulfonic acid, p-toluenesulfonic acid, sodium dihydrogen phosphate, sodium bisulfate, potassium bisulfate, potassium dihydrogen phosphate, triphenylphosphine trisulfonic acid, trifluoroacetic acid, hydrobromic acid, and hydroiodic acid.

[0017] Preferably, the raw material in the aqueous phase of step 1) further includes an aqueous phase density regulator and / or a phase transfer catalyst.

[0018] Preferably, in step 1), the aqueous phase density adjuster is at least one of sulfate, chloride, nitrate, phosphate, hydrogen sulfate and dihydrogen phosphate; and the phase transfer catalyst is at least one of polyether, cyclic crown ether, quaternary ammonium salt, tertiary amine, quaternary ammonium base and quaternary phosphonium salt.

[0019] Preferably, the phase transfer catalyst in step 1) is at least one of polyethers, cyclic crown ethers, quaternary ammonium salts, tertiary amines, quaternary ammonium bases, and quaternary phosphonium salts.

[0020] Preferably, the hydrophilic solvent in step 1) is at least one of tetrahydrofuran, 1,4-dioxane, 2-methyltetrahydrofuran, methylcyclopentanehexane ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, water, N-methylpyrrolidone, acetone, butanone, sulfolane, 1,3-dimethylimidazolinone (DMI), tert-butanol, and methyl isobutyl ketone.

[0021] Preferably, the lipophilic solvent in step 1) is at least one of toluene, xylene, p-xylene, o-xylene, m-xylene, trimethylbenzene, fluorobenzene, trifluorotoluene, chlorobenzene, nitrobenzene, C4-C12 saturated alkanes, cyclohexane, decahydronaphthalene, biphenyl, anisole, tert-butylbenzene, ethylbenzene, dichloromethane, ethyl acetate, dichloroethane, 1,1-dichloropropane, 1,2-dichloropropane, 1,3-dichloropropane, 2,2-dichloropropane, dichlorobutane, tetrachloroethylene, and perfluorohexanone.

[0022] Preferably, in step 3), the method of reverse contact mixing is to mix the aqueous phase mixture from top to bottom and the oil phase mixture from bottom to top.

[0023] Preferably, the temperature of the dehydration reaction in step 3) is 60–200°C.

[0024] The present invention also provides an apparatus for the two-phase continuous synthesis of 5-hydroxymethylfurfural, comprising an aqueous phase storage tank (1), an oil phase storage tank (2), a reactor (3), a solvent removal device (4), a product storage tank (5), a solvent recovery storage tank (6), a filtration and impurity removal device (7), and an aqueous phase recovery tank (8); the outlet of the aqueous phase storage tank (1) is connected to the upper inlet of the reactor (3), and the outlet of the oil phase storage tank (2) is connected to the lower inlet of the reactor (3); the upper outlet of the reactor (3) is connected to the lower outlet of the solvent removal device (4). The lower outlet of the solvent removal device (4) is connected to the inlet of the product storage tank (5), the upper outlet of the solvent removal device (4) is connected to the inlet of the solvent recovery storage tank (6), and the outlet of the solvent recovery storage tank (6) is connected to the inlet of the oil phase storage tank (2); the lower outlet of the reactor (3) is connected to the inlet of the filtration and impurity removal device (7), the outlet of the filtration and impurity removal device (7) is connected to the inlet of the aqueous phase recovery tank (8), and the outlet of the aqueous phase recovery tank (8) is connected to the inlet of the aqueous phase storage tank (1).

[0025] Beneficial technical effects:

[0026] This invention involves preheating the aqueous phase and oil phase separately, then mixing them in counter-current contact to carry out a dehydration reaction, resulting in a reacted oil phase and a reacted aqueous phase. The raw materials of the aqueous phase and / or oil phase include a hydrophilic solvent. The raw materials of the aqueous phase also include raw sugar, a catalyst, and water. The raw materials of the oil phase also include a lipophilic solvent. After removing the solvent from the reacted oil phase, 5-hydroxymethylfurfural is obtained. The removed solvent can be added back to the oil phase for recycling. After removing impurities from the reacted aqueous phase, it can be added back to the aqueous phase for recycling. This invention selects industrially common inorganic salts as aqueous phase density regulators, which can change the system density and the partition coefficient between the two phases. These salts are simple to obtain, have good stability, and are low in cost. The addition of a phase transfer catalyst to the reaction system allows for real-time adjustment of the mass transfer process in the reaction medium, accelerating the reaction rate of the two phases during countercurrent flow and improving production efficiency. Furthermore, by removing impurities, this invention recycles and reuses the aqueous mixture containing catalysts, aqueous phase density regulators, and phase transfer catalysts. The removed solvent can also be recovered and reused in the reaction, enabling continuous production of HMF, reducing production costs, and meeting the economic applicability requirements for industrial production. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the apparatus for the two-phase continuous synthesis of 5-hydroxymethylfurfural according to the present invention;

[0028] Figure 2 The liquid chromatogram of the crude HMF in Example 1;

[0029] Figure 3 The image shows the 1H NMR spectrum of the crude HMF from Example 1. Detailed Implementation

[0030] This invention provides a two-phase continuous synthesis method for 5-hydroxymethylfurfural, comprising the following steps:

[0031] 1) The aqueous phase and oil phase are preheated separately and then mixed in countercurrent contact to carry out a dehydration reaction, resulting in the reacted oil phase and the reacted aqueous phase;

[0032] The raw materials in the aqueous and / or oil phases contain hydrophilic solvents; the raw materials in the aqueous phases also include raw sugar, catalyst, and water; the raw materials in the oil phases also include lipophilic solvents.

[0033] 2) After removing the solvent from the oil phase after the reaction, 5-hydroxymethylfurfural is obtained. The removed solvent can be added back to the oil phase of step 1) for recycling.

[0034] 3) After removing impurities from the aqueous phase after the reaction, it can be added back to the aqueous phase in step 1) for recycling.

[0035] In this invention, the aqueous phase and the oil phase are preheated separately and then mixed in reverse contact to carry out a dehydration reaction, resulting in a reacted oil phase and a reacted aqueous phase.

[0036] In this invention, the raw materials of the aqueous phase and / or oil phase contain a hydrophilic solvent; in this invention, the first hydrophilic solvent is preferably at least one of tetrahydrofuran, 1,4-dioxane, 2-methyltetrahydrofuran, methylcyclopentanehexane ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, water, N-methylpyrrolidone, acetone, butanone, sulfolane, 1,3-dimethylimidazolinone (DMI), tert-butanol, and methyl isobutyl ketone, more preferably tetrahydrofuran, 1,4-dioxane, dimethyl sulfoxide, or acetone.

[0037] In this invention, the raw materials in the aqueous phase also include raw sugar, catalyst, and water.

[0038] In this invention, the raw sugar is preferably at least one of fructose, glucose, starch, inulin, sucrose, maltose, high-fructose corn syrup, cellulose, and galactose, more preferably fructose, glucose, inulin, or high-fructose corn syrup; the mass concentration of the raw sugar in the aqueous mixture is preferably 40-60%, more preferably 50%.

[0039] In this invention, the catalyst is preferably at least one selected from sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, trifluoromethanesulfonic acid, methanesulfonic acid, p-toluenesulfonic acid, sodium dihydrogen phosphate, sodium bisulfate, potassium bisulfate, potassium dihydrogen phosphate, triphenylphosphine trisulfonic acid, and trifluoroacetic acid, more preferably hydrochloric acid, nitric acid, methanesulfonic acid, sodium bisulfate, potassium dihydrogen phosphate, or trifluoroacetic acid; the mass of the catalyst is 5-10% of the mass of the raw sugar.

[0040] The raw materials of the aqueous mixture of the present invention also include an aqueous density regulator and / or a phase transfer catalyst.

[0041] In this invention, the aqueous phase density regulator is preferably at least one of sulfate, chloride, nitrate, phosphate, bisulfate, and dihydrogen phosphate, more preferably at least one of sodium chloride, potassium chloride, calcium chloride, aluminum chloride, sodium sulfate, potassium sulfate, magnesium sulfate, ferric sulfate, copper sulfate, sodium bisulfate, potassium bisulfate, sodium phosphate, potassium phosphate, magnesium phosphate, calcium phosphate, sodium nitrate, potassium nitrate, sodium carbonate, potassium carbonate, calcium carbonate, and magnesium carbonate, and most preferably sodium chloride, potassium carbonate, or magnesium sulfate; the mass of the aqueous phase density regulator is 20-30% of the raw sugar. This invention uses industrially common inorganic salts as aqueous phase density regulators, which can change the system density and the partition coefficient between the two phases, and has the advantages of being simple to obtain, having good stability, and being low in cost.

[0042] In this invention, the phase transfer catalyst is at least one selected from polyethers, cyclic crown ethers, quaternary ammonium salts, tertiary amines, quaternary ammonium bases, and quaternary phosphonium salts. More preferably, it is at least one selected from polyethylene glycol, 18-crown ether-6, 15-crown ether-5, benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium hydrogen sulfate, trioctylmethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, pyridine, and tributylamine. Most preferably, it is polyethylene glycol, tetrabutylammonium bromide, 18-crown ether-6, or tributylamine. The mass of the phase transfer catalyst is 1-5% of the mass of the raw sugar. This invention, by adding a phase transfer catalyst to the reaction system, can adjust the mass transfer process of the reaction medium in the system in real time, accelerate the reaction rate of the two phases in the countercurrent process, and improve production efficiency.

[0043] In this invention, the raw material of the oil phase further includes a lipophilic solvent; the lipophilic solvent is preferably at least one of toluene, xylene, p-xylene, o-xylene, m-xylene, trimethylbenzene, fluorobenzene, trifluorotoluene, chlorobenzene, nitrobenzene, C4-C12 saturated alkanes, cyclohexane, decahydronaphthalene, biphenyl, anisole, tert-butylbenzene, ethylbenzene, dichloromethane, ethyl acetate, dichloroethane, 1,1-dichloropropane, 1,2-dichloropropane, 1,3-dichloropropane, 2,2-dichloropropane, dichlorobutane, tetrachloroethylene, and perfluorohexanone, more preferably toluene, xylene, p-xylene, o-xylene, m-xylene, trimethylbenzene, ethylbenzene, or ethyl acetate; the mass ratio of the hydrophilic solvent to the lipophilic solvent is preferably 1:1; the total mass of the hydrophilic solvent and the lipophilic solvent is 5-10 times the mass of the raw sugar.

[0044] In this invention, the temperature of the preheated aqueous phase and oil phase is preferably 40-80°C, more preferably 50-70°C, and most preferably 60-65°C.

[0045] In this invention, the temperature of the dehydration reaction is preferably 60-200°C, more preferably 100-150°C.

[0046] After obtaining the oil phase and the aqueous phase after the reaction, the present invention removes the solvent from the oil phase to obtain 5-hydroxymethylfurfural. The removed solvent can be added back into the oil phase for recycling.

[0047] This invention does not specifically limit the method for removing the solvent; any method well-known to those skilled in the art can be used. In this invention, the removed solvent can be collected and recycled as a hydrophilic solvent.

[0048] This invention allows the aqueous phase after the reaction to be purified of impurities and then mixed with sugar raw materials for continued use as a raw material for the aqueous phase.

[0049] The present invention does not specifically limit the method of impurity removal; any impurity removal method well known to those skilled in the art can be selected, such as filtration.

[0050] This invention removes impurities through filtration, allowing the aqueous mixture containing additives such as catalysts, aqueous density modifiers, and phase transfer catalysts to be recycled and reused. The removed solvent can also be recovered and continue to participate in the reaction, enabling continuous production of HMF, reducing production costs, and meeting the economic applicability requirements for industrial production.

[0051] The present invention also provides an apparatus for the two-phase continuous synthesis of 5-hydroxymethylfurfural, comprising an aqueous phase storage tank (1), an oil phase storage tank (2), a reactor (3), a solvent removal device (4), a product storage tank (5), a solvent recovery storage tank (6), a filtration and impurity removal device (7), and an aqueous phase recovery tank (8); the outlet of the aqueous phase storage tank (1) is connected to the upper inlet of the reactor (3), and the outlet of the oil phase storage tank (2) is connected to the lower inlet of the reactor (3); the upper outlet of the reactor (3) is connected to the lower outlet of the solvent removal device (4). The lower outlet of the solvent removal device (4) is connected to the inlet of the product storage tank (5), the upper outlet of the solvent removal device (4) is connected to the inlet of the solvent recovery storage tank (6), and the outlet of the solvent recovery storage tank (6) is connected to the inlet of the oil phase storage tank (2); the lower outlet of the reactor (3) is connected to the inlet of the filtration and impurity removal device (7), the outlet of the filtration and impurity removal device (7) is connected to the inlet of the aqueous phase recovery tank (8), and the outlet of the aqueous phase recovery tank (8) is connected to the inlet of the aqueous phase storage tank (1).

[0052] Specifically, in this invention, raw sugar, catalyst, water, aqueous phase density regulator, phase transfer catalyst, and a first hydrophilic solvent are mixed and added to an aqueous phase storage tank (1) for first preheating to obtain an aqueous phase mixture; a second hydrophilic solvent and an oleophilic solvent are mixed and added to an oil phase storage tank (2) for second preheating to obtain an oil phase mixture; the aqueous phase mixture enters the reactor (3) from the upper inlet and flows from top to bottom due to gravity, while the oil phase mixture enters the reactor (3) from the lower inlet and flows from bottom to top. The two phase mixtures react in the reaction... The reactor (3) is subjected to a dehydration reaction by reverse contact mixing to obtain an oil phase and an aqueous phase after the reaction. The oil phase after the reaction is discharged from the upper outlet of the reactor (3), and after the solvent is removed by the solvent removal device (4), it enters the product storage tank (5). The removed solvent is collected in the solvent recovery storage tank (6) and then added to the oil phase storage tank (2) for recycling. The aqueous phase after the reaction is filtered and impurity removed by the impurity removal device (7) and collected in the aqueous phase recovery tank (8). After the addition of new raw sugar, it is returned to the aqueous phase storage tank (1) for recycling.

[0053] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0054] Example 1

[0055] 1) Mix 500g fructose, 500g water, 25g hydrochloric acid, 100g sodium chloride and 5g tetrabutylammonium chloride evenly, and preheat to 50℃ to obtain an aqueous phase mixture;

[0056] 2) Mix 2000g of tetrahydrofuran and 2000g of chlorobenzene evenly, and preheat to 50℃ to obtain an oil phase mixture;

[0057] 3) The aqueous phase mixture is fed into the reactor at a rate of 500 g / h, and the oil phase mixture is fed into the reactor at a rate of 500 g / h. They are in countercurrent contact with the aqueous phase mixture. The reactor temperature is 100℃ to carry out the dehydration reaction, and the oil phase and aqueous phase after the reaction are obtained.

[0058] 4) The oil phase containing HMF, after the reaction, flows out through the top outlet of the reactor and enters the desolventizing unit. The final crude HMF product is stored in the product storage tank, and the recovered tetrahydrofuran and toluene are recycled. The liquid chromatogram of the obtained crude HMF product is shown below. Figure 2 As shown, the results indicate that the purity of the crude HMF is 96.32%. The 1H NMR spectrum of the obtained crude HMF is shown below. Figure 3 As shown, the interpretation of each peak in the figure confirms that the HMF product was synthesized.

[0059] 5) After the reaction, the aqueous phase flows out through the bottom outlet of the reactor and enters a filtration and impurity removal device. New fructose is added, and the mixture is recycled. High-performance liquid chromatography (HPLC) analysis showed a fructose conversion rate of 99%, a HMF yield of 91%, and a purity of over 95%. (The conversion rate is calculated as 100% - the concentration of residual fructose in the aqueous phase after the reaction; the yield is calculated as the molar amount of HMF obtained from the reaction / the theoretically expected molar amount of HMF × 100%.)

[0060] Example 2

[0061] Using the same reaction apparatus and conditions as in Example 1, but replacing the catalyst with 25g of nitric acid, the conversion rate of fructose was 99%, the yield of HMF was 88%, and the purity was over 95%, as determined by high performance liquid chromatography.

[0062] Example 3

[0063] Using the same reaction apparatus and conditions as in Example 1, but replacing the catalyst with 25g of methanesulfonic acid, the conversion rate of fructose was 99%, the yield of HMF was 81%, and the purity was over 95%, as determined by high performance liquid chromatography.

[0064] Example 4

[0065] Using the same reaction apparatus and conditions as in Example 1, but with the catalyst replaced by 25g sodium bisulfate, the conversion rate of fructose was 98%, the yield of HMF was 79%, and the purity was over 95%, as determined by high performance liquid chromatography.

[0066] Example 5

[0067] Using the same reaction apparatus and reaction conditions as in Example 1, but replacing the catalyst with 25g of potassium dihydrogen phosphate, the conversion rate of fructose was 98%, the yield of HMF was 75%, and the purity was above 95%, as determined by high performance liquid chromatography.

[0068] Example 6

[0069] Using the same reaction apparatus and conditions as in Example 1, but with the catalyst replaced by 25g of trifluoroacetic acid, the conversion rate of fructose was 98%, the yield of HMF was 75%, and the purity was above 95%, as determined by high performance liquid chromatography.

[0070] Example 7

[0071] Using the same reaction apparatus and conditions as in Example 1, but with the raw material changed to 500g of glucose, the conversion rate of fructose was 95%, the yield of HMF was 81%, and the purity was over 90%, as determined by high performance liquid chromatography.

[0072] Example 8

[0073] Using the same reaction apparatus and conditions as in Example 1, but with the raw material changed to 500g of starch, the fructose conversion rate was 73%, the HMF yield was 45%, and the purity was over 70%, as determined by high performance liquid chromatography.

[0074] Example 9

[0075] Using the same reaction apparatus and conditions as in Example 1, the raw material was changed to 500g of high fructose syrup F90. The fructose conversion rate was 96%, the HMF yield was 76%, and the purity was over 95%, as determined by high performance liquid chromatography.

[0076] Example 10

[0077] Using the same reaction apparatus and reaction conditions as in Example 1, but with the raw material changed to 500g of sucrose, the conversion rate of fructose was 79% and the yield of HMF was 49% by high performance liquid chromatography, with a purity of over 70%.

[0078] Example 11

[0079] Using the same reaction apparatus and reaction conditions as in Example 1, but with the raw material changed to 500g of inulin, the conversion rate of fructose was 94%, the yield of HMF was 68%, and the purity was over 90%, as determined by high performance liquid chromatography.

[0080] Example 12

[0081] Using the same reaction apparatus and reaction conditions as in Example 1, but replacing sodium chloride with 100g of potassium carbonate, the conversion rate of fructose was 99% and the yield of HMF was 85%, with a purity of over 95%, as determined by high performance liquid chromatography.

[0082] Example 13

[0083] Using the same reaction apparatus and reaction conditions as in Example 1, but replacing sodium chloride with 100g magnesium sulfate, the conversion rate of fructose was 99% and the yield of HMF was 80%, with a purity of over 95%, as determined by high performance liquid chromatography.

[0084] Example 14

[0085] Using the same reaction apparatus and conditions as in Example 1, but replacing tetrabutylammonium bromide with 5g of polyethylene glycol, the conversion rate of fructose was 99% and the yield of HMF was 82%, with a purity of over 95%, as determined by high performance liquid chromatography.

[0086] Example 15

[0087] Using the same reaction apparatus and conditions as in Example 1, but replacing tetrabutylammonium bromide with 10g of 18-crown ether-6, the conversion rate of fructose was 98% and the yield of HMF was 79%, with a purity of over 95%, as determined by high performance liquid chromatography.

[0088] Example 16

[0089] Using the same reaction apparatus and conditions as in Example 1, tetrabutylammonium bromide was replaced with 20g of tributylamine. The conversion rate of fructose was 99%, the yield of HMF was 81%, and the purity was over 95%, as determined by high performance liquid chromatography.

[0090] Example 17

[0091] Using the same reaction apparatus and reaction conditions as in Example 1, but replacing "100g sodium chloride" with "0g sodium chloride", the conversion rate of fructose was 79% and the yield of HMF was 59% by high performance liquid chromatography, with a purity of over 75%.

[0092] Example 18

[0093] Using the same reaction apparatus and reaction conditions as in Example 1, the amount of "5g tetrabutylammonium bromide" was changed to "0g tetrabutylammonium bromide". The conversion rate of fructose was 72% and the yield of HMF was 53% by high performance liquid chromatography. The purity was above 75%.

[0094] Example 19

[0095] Using the same reaction apparatus and reaction conditions as in Example 1, the reaction mixture was changed from "100g sodium chloride, 5g tetrabutylammonium bromide" to "0g sodium chloride, 0g tetrabutylammonium bromide". The fructose conversion rate was 70%, the HMF yield was 50%, and the purity was over 70% as determined by high performance liquid chromatography.

[0096] Example 20

[0097] 1) Mix 1000g fructose, 1500g water, 100g hydrochloric acid, 300g sodium chloride, 50g tetrabutylammonium chloride, and 100g 1,4-dioxane evenly, and preheat to 80℃ to obtain an aqueous phase mixture;

[0098] 2) Mix 5000g of 1,4-dioxane and 5000g of toluene evenly and preheat to 80℃ to obtain an oil phase mixture;

[0099] 3) The aqueous phase mixture is fed into the reactor at a rate of 500 g / h, and the oil phase mixture is fed into the reactor at a rate of 500 g / h. They are then brought into countercurrent contact with the aqueous phase mixture. The reactor temperature is 150℃ to carry out the dehydration reaction, and the resulting oil phase and aqueous phase are obtained.

[0100] 4) The oil phase containing HMF after the reaction flows out through the outlet above the reactor and enters the desolventizing unit. The final HMF is stored in the product storage tank, and the recovered tetrahydrofuran and toluene are recycled.

[0101] 5) The aqueous phase after the reaction flows out through the bottom outlet of the reactor and enters a filtration and impurity removal device. New fructose is added, and the mixture is recycled. High-performance liquid chromatography (HPLC) showed a fructose conversion rate of 98% and a HMF yield of 89%.

[0102] Comparative Example 1

[0103] Using the same reaction apparatus and reaction conditions as in Example 20, but changing the reactor temperature to 250°C, the conversion rate of fructose was 98% and the yield of HMF was 63% as determined by high performance liquid chromatography.

[0104] Comparative Example 2

[0105] Using the same reaction apparatus and reaction conditions as in Example 20, the aqueous phase density regulator was replaced with 100g of sodium chloride, and the phase transfer catalyst was replaced with 5g of tetrabutylammonium chloride. The conversion rate of fructose was 70% and the yield of HMF was 47% as determined by high performance liquid chromatography.

[0106] Comparative Example 3

[0107] Using the same reaction apparatus and reaction conditions as in Example 20, the reaction mixture was changed from "1000g fructose, 1500g water" to "500g fructose, 2000g water". The conversion rate of fructose was 80% and the yield of HMF was 51% as determined by high performance liquid chromatography.

[0108] Comparative Example 4

[0109] Using the same reaction apparatus and reaction conditions as in Example 20, but replacing the catalyst with 100g of hydrochloric acid, the conversion rate of fructose was 77% and the yield of HMF was 60% as determined by high performance liquid chromatography.

[0110] Comparative Example 5

[0111] Using the same reaction apparatus and reaction conditions as in Example 20, the oil phase mixture was replaced with 3000g of 1,4-dioxane and 3000g of toluene, which were mixed uniformly. The fructose conversion rate was 72% and the HMF yield was 63% as determined by high performance liquid chromatography.

[0112] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for the continuous two-phase synthesis of 5-hydroxymethylfurfural, characterized in that, Includes the following steps: 1) The aqueous phase and oil phase are preheated separately and then mixed in countercurrent contact to carry out a dehydration reaction, resulting in the reacted oil phase and the reacted aqueous phase; The raw materials in the aqueous and / or oil phases contain hydrophilic solvents; the raw materials in the aqueous phases also include raw sugar, catalyst, and water; the raw materials in the oil phases also include lipophilic solvents; the mass ratio of the hydrophilic solvent to the lipophilic solvent is 1:1; the total mass of the hydrophilic solvent and the lipophilic solvent is 5 to 10 times the mass of the raw sugar. 2) After removing the solvent from the oil phase after the reaction, 5-hydroxymethylfurfural is obtained. The removed solvent can be added back to the oil phase of step 1) for recycling. 3) After removing impurities from the aqueous phase following the reaction, it can be added back to the aqueous phase from step 1) for reuse; In step 1), the raw sugar is at least one selected from fructose, glucose, starch, inulin, sucrose, maltose, high-fructose corn syrup, cellulose, and galactose; the mass concentration of the raw sugar in the aqueous mixture is 40-60%. The catalyst in step 1) is at least one selected from sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, trifluoromethanesulfonic acid, methanesulfonic acid, p-toluenesulfonic acid, sodium dihydrogen phosphate, sodium bisulfate, potassium bisulfate, potassium dihydrogen phosphate, triphenylphosphine trisulfonic acid, trifluoroacetic acid, hydrobromic acid, and hydroiodic acid; the mass of the catalyst is 5-10% of the mass of the raw sugar. The raw materials for the aqueous phase in step 1) also include an aqueous phase density regulator and a phase transfer catalyst; In step 1), the aqueous phase density regulator is at least one of sulfate, chloride, nitrate, phosphate, hydrogen sulfate, and dihydrogen phosphate; the mass of the aqueous phase density regulator is 20-30% of the raw sugar. The phase transfer catalyst is at least one of polyethers, cyclic crown ethers, quaternary ammonium salts, tertiary amines, quaternary ammonium bases, and quaternary phosphonium salts; the mass of the phase transfer catalyst is 1 to 5% of the mass of the raw sugar.

2. The method according to claim 1, characterized in that, The hydrophilic solvent in step 1) is at least one of tetrahydrofuran, 1,4-dioxane, 2-methyltetrahydrofuran, methylcyclopentanehexane ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, water, N-methylpyrrolidone, acetone, butanone, sulfolane, 1,3-dimethylimidazolinone, tert-butanol, and methyl isobutyl ketone.

3. The method according to claim 1, characterized in that, In step 1), the lipophilic solvent is at least one of toluene, xylene, trimethylbenzene, fluorobenzene, trifluorotoluene, chlorobenzene, nitrobenzene, C4-C12 saturated alkanes, cyclohexane, decahydronaphthalene, biphenyl, anisole, tert-butylbenzene, ethylbenzene, dichloromethane, ethyl acetate, dichloroethane, 1,1-dichloropropane, 1,2-dichloropropane, 1,3-dichloropropane, 2,2-dichloropropane, dichlorobutane, tetrachloroethylene, and perfluorohexanone.

4. The method according to claim 1, characterized in that, The method of reverse contact mixing in step 1) is to mix the aqueous phase mixture from top to bottom and the oil phase mixture from bottom to top in a reverse mixing process.

5. The method according to claim 1, characterized in that, The temperature of the dehydration reaction in step 1) is 60~200℃.

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