CN118164929A

CN118164929A - Method for preparing 5-hydroxymethylfurfural by organic-inorganic two-phase continuous fructose

Info

Publication number: CN118164929A
Application number: CN202211586142.1A
Authority: CN
Inventors: 邢嘉成; 徐云鹏; 刘中民; 王磊; 王泽敏; 王艳涛; 梁越
Original assignee: Zhongke Guosheng Hangzhou Technology Co ltd; Dalian Institute of Chemical Physics of CAS
Current assignee: Zhongke Guosheng Hangzhou Technology Co ltd; Dalian Institute of Chemical Physics of CAS
Priority date: 2022-12-09
Filing date: 2022-12-09
Publication date: 2024-06-11

Abstract

The application discloses a method for preparing 5-hydroxymethylfurfural by organic-inorganic two-phase continuous fructose. The preparation method comprises the following steps: mixing fructose, inorganic salt, an acid catalyst and an organic solvent with water, and allowing the solution to flow through a heat exchanger for continuous reaction to obtain the 5-hydroxymethylfurfural; the inorganic salt is selected from at least one of halogen compound, boride, silicate, aluminate and phosphate; the acidic catalyst comprises at least one of an acid dissolved in water; the organic solvent is at least one selected from acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, methyl isobutyl ketone, dimethyl carbonate, ethyl acetate and ethylene glycol. The added specific inorganic salt and the specific acid catalyst react under a continuous mode, so that a synergistic effect can be achieved, and the production efficiency and the conversion rate of the reaction can be effectively improved compared with a batch reaction.

Description

Method for preparing 5-hydroxymethylfurfural by organic-inorganic two-phase continuous fructose

Technical Field

The application relates to a method for preparing 5-hydroxymethylfurfural by organic-inorganic two-phase continuous fructose, belonging to the field of preparation and synthesis of 5-hydroxymethylfurfural.

Background

The preparation of chemicals from renewable biomass resources not only can alleviate the increasingly intense crisis of petroleum resources, but also provides innovative source power for people to develop new materials based on the unique structural characteristics of bio-based chemicals. The synthetic route of the bio-based chemicals which take 5-Hydroxymethylfurfural (HMF) as a platform compound and are further converted into other high-added value derivatives is a future development direction. The series of products can be used for producing novel degradable plastics, novel polyurethane, special nylon, novel green solvents, novel oil additives and the like. The products not only have important application (packaging materials, chemical intermediates, high-end automobile interiors and the like) in the civil field, but also have potential application prospects in the military field (special equipment, high-altitude area military diesel generator fuels and the like). 5-hydroxymethylfurfural (5-hydroxy methylfurfural, HMF) is considered to be the most valuable and potential biobased platform chemical to replace basic chemicals in the petrochemical industry that can be produced from biomass feedstocks and is internationally considered to be a key bridge compound between biobased and petroleum-based chemistry. The European Union BREW "medium and long term challenges in biotechnology production of large scale chemical products from renewable feedstocks" HMF was listed as the most important six carbon platform compound in 2006-2050. The HMF molecule furan ring is provided with aldehyde group and hydroxymethyl, and can be catalyzed and oxidized to generate a series of furan aromatic compounds, thereby replacing benzene bulk chemicals from petroleum sources, and having wide economic and social significance.

A typical reaction form for the traditional production of 5-hydroxymethylfurfural is to use a batch reactor. The reaction kettle needs larger labor cost and time, black rot which is difficult to clean easily occurs in the reaction process, the continuation of the reaction is affected, and the yield of HMF is reduced. Various homogeneous or heterogeneous catalysts have been developed, including Lewis and Bronsted acids, which have been found to be effective in the synthesis of 5-hydroxymethylfurfural and which are widely used in processes for the production of 5-hydroxymethylfurfural. However, because the 5-hydroxymethylfurfural generated in the reaction process has higher reactivity, the 5-hydroxymethylfurfural can further react under the catalysis of the catalyst to generate high-molecular black rot through polymerization or generate acetoacetic acid through decomposition. The generation of these byproducts can lead to lower selectivity of the reaction, and can lead to corrosion and blockage of equipment, so that the reaction is difficult to carry out, the maintenance and use cost of the equipment is greatly increased, and the economic benefit is poor. These disadvantages limit their potential industrial application.

Disclosure of Invention

According to one aspect of the present application, there is provided a process for preparing 5-hydroxymethylfurfural, which comprises mixing a solution comprising fructose, an inorganic salt, an acidic catalyst, an organic solvent and water, passing the solution through a heat exchanger, and reacting under continuous conditions to obtain the 5-hydroxymethylfurfural. In the application, the inorganic salt and the specific acid catalyst are added for reaction under the continuous condition, so that the synergistic effect can be achieved, and the production efficiency and the conversion rate of the reaction can be effectively improved compared with the intermittent reaction. Meanwhile, the problems that the yield of the product is reduced and the maintenance cost of equipment is greatly increased due to the fact that the black rot is formed by side reaction of 5-hydroxymethylfurfural are avoided. The system for synthesizing the 5-hydroxymethylfurfural has the advantages of larger economic benefit, lower system cost, less environmental pollution, simple operation, easy repetition, low equipment maintenance cost and high-purity 5-hydroxymethylfurfural production.

A method for preparing 5-hydroxymethylfurfural by organic-inorganic two-phase continuous fructose preparation, which comprises the following steps:

Introducing a mixed solution containing fructose, inorganic salt, an acid catalyst, an organic solvent and water into a continuous reactor, and reacting for 2-10 hours under the conditions of 60-180 ℃ and liquid phase flow rate of 0.1-20L/min to obtain the 5-hydroxymethylfurfural;

The inorganic salt is selected from at least one of halogen compound, boride, silicate, aluminate, phosphate and borate;

the organic solvent is at least one selected from acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, methyl isobutyl ketone, dimethyl carbonate, ethyl acetate and ethylene glycol.

Optionally, the acid catalyst comprises at least one of an acid dissolved in water.

Optionally, the halogen compound comprises at least one of sodium chloride, sodium fluoride, magnesium chloride, calcium chloride, barium chloride, chromium chloride, ferric chloride, cupric chloride, aluminum chloride, sodium bromide, calcium bromide, and magnesium bromide;

The boride comprises at least one of boron fluoride, magnesium boride, titanium boride, chromium boride and calcium boride;

the silicate comprises at least one of sodium silicate, calcium silicate, magnesium silicate, ammonium silicate and the like;

the aluminate comprises at least one of sodium aluminate, calcium aluminate, magnesium aluminate, ammonium aluminate and the like;

the phosphate comprises at least one of sodium phosphate, calcium phosphate, magnesium phosphate, ammonium phosphate and the like.

The water-soluble acid is an acid that is readily soluble in water.

Optionally, the water-soluble acid comprises at least one of phosphoric acid, hydrochloric acid, sulfuric acid, boric acid, and p-toluenesulfonic acid;

optionally, the hydrochloric acid is a hydrochloric acid solution with the concentration of 35.0-40.0 wt%;

optionally, the sulfuric acid is concentrated sulfuric acid of 95.0 to 99.0 wt%.

Optionally, the mass ratio of the fructose to the inorganic salt is 0.5-10: 0.001-2;

Optionally, the mass ratio of the fructose to the inorganic salt is 5-10:0.05-2;

Optionally, the mass ratio of the fructose to the inorganic salt is 8-10:0.5-2;

optionally, the mass ratio of the fructose to the inorganic salt is 8-10:1-2.

Optionally, the mass ratio of the fructose to the acid catalyst is 0.5-10: 0.01 to 1;

Optionally, the mass ratio of the fructose to the acid catalyst is 8-10:0.01-1;

optionally, the mass ratio of the fructose to the acid catalyst is 10:0.01-1.

Optionally, the organic solvent includes at least one of acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, methyl isobutyl ketone, dimethyl carbonate, ethyl acetate, and ethylene glycol.

Optionally, the mass ratio of the fructose to the organic solvent is 0.5-10: 1-20;

optionally, the mass ratio of the fructose to the organic solvent is 5-10: 5-20;

optionally, the mass ratio of the fructose to the organic solvent is 8-10: 6-20;

Optionally, the mass ratio of the fructose to the organic solvent is 5-10: 10-20 parts;

Optionally, the mass ratio of the fructose to the organic solvent is 10: 15-20.

Optionally, the solvent of the solution comprises water.

Optionally, the mass ratio of the fructose to the solvent is 0.5-10: 1-20;

optionally, the mass ratio of the fructose to the solvent is 5-10: 5-20;

optionally, the mass ratio of the fructose to the solvent is 8-10: 6-20;

Optionally, the mass ratio of the fructose to the solvent is 5-10: 10-20 parts;

optionally, the mass ratio of the fructose to the solvent is 10: 15-20.

Optionally, the reaction conditions include: the reaction temperature is 60-180 ℃;

Optionally, the upper limit of the reaction temperature is selected from 70 ℃, 80 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃, 175 ℃, or 180 ℃; the lower limit is selected from 60 ℃, 70 ℃,90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃ or 175 ℃.

Optionally, the reaction conditions include: the reaction time is 2 to 10 hours;

Alternatively, the upper reaction time limit is selected from 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours; the lower limit is selected from 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours or 9 hours.

Alternatively, the reaction is at atmospheric pressure.

Optionally, the reaction conditions include: the flow rate of the reaction is 0.1L/min-20L/min.

Optionally, the upper limit of the reaction flow rate is selected from 0.5L/min, 1L/min, 3L/min, 5L/min, 9L/min, 12L/min, 15L/min or 20L/min; the lower limit is selected from 0.1L/min, 0.3L/min, 1L/min, 5L/min, 8L/min, 10L/min, 15L/min or 19L/min.

Optionally, after the reaction is finished, the method further comprises a purification step:

And (3) adding an extractant into the reaction liquid to obtain an upper layer extract, and carrying out reduced pressure distillation on the upper layer extract to obtain the 5-hydroxymethylfurfural.

Optionally, the volume ratio of the extractant to the reaction liquid is 1-3:1.

Optionally, the extractant includes at least one of ethyl acetate and dimethyl carbonate.

Optionally, the number of extractions is 2-5.

Optionally, the conditions of the reduced pressure distillation include:

Vacuum degree is 0.01-5 KPa, temperature is 30-60 ℃ and time is 0.5-3 hours.

Optionally, the upper limit of the vacuum degree is selected from 0.02KPa, 0.05KPa, 0.1KPa, 0.5KPa, 1KPa, 2KPa, 3KPa, 4KPa, 4.5KPa or 5KPa; the lower limit is selected from 0.01KPa, 0.02KPa, 0.05KPa, 0.1KPa, 0.5KPa, 1KPa, 2KPa, 3KPa, 4KPa, or 4.5KPa.

Optionally, the upper temperature limit is selected from 60 ℃, 55 ℃, 50 ℃, 45 ℃, 40 ℃ or 35 ℃; the lower limit is selected from 30 ℃, 35 ℃, 40 ℃, 45 ℃, 50 ℃ or 55 ℃.

Alternatively, the upper time limit is selected from 0.6 hours, 0.8 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, or 3 hours; the lower limit is selected from 2.5 hours, 2 hours, 1.5 hours, 1 hour, 0.8 hours, 0.6 hours or 0.5 hours.

Optionally, the yield of 5-hydroxymethylfurfural of the preparation method is more than 80%.

Optionally, the yield of the 5-hydroxymethylfurfural in the preparation method is 80-95%.

As one embodiment, the application discloses a method for preparing 5-hydroxymethylfurfural, which comprises the steps of mixing fructose, inorganic salt, an acid catalyst, an organic solvent and water into a solution, allowing the solution to flow through a heat exchanger, reacting under continuous conditions to obtain the 5-hydroxymethylfurfural, extracting the 5-hydroxymethylfurfural by using an extractant after the reaction, and realizing separation of the 5-hydroxymethylfurfural and recycling of the extractant by adopting a reduced pressure distillation method. The inorganic salt added in the method can effectively improve the reaction selectivity, and simultaneously, the problems of product yield reduction and equipment maintenance cost greatly increase caused by the formation of black rot by side reaction of 5-hydroxymethylfurfural are avoided by adopting a continuous system synthesis. The system for synthesizing the 5-hydroxymethylfurfural has the advantages of larger economic benefit, lower system cost, less environmental pollution, simple operation, easy repetition, low equipment maintenance cost and high-purity 5-hydroxymethylfurfural production.

As an embodiment, the application discloses a preparation method of 5-hydroxymethylfurfural, which comprises the following steps:

(1) Mixing fructose, inorganic salt, an acid catalyst, an organic solvent and water to form a solution, and allowing the solution to flow through a heat exchanger for continuous reaction to obtain the 5-hydroxymethylfurfural.

(2) Extracting 5-hydroxymethylfurfural by using an extractant after the reaction, and recovering and separating an extraction solvent from a product by adopting a reduced pressure distillation method.

Optionally, the inorganic salt includes a halogen compound, boride, and at least one of silicate, aluminate, and phosphate.

Optionally, the acidic catalyst comprises at least one of an acid dissolved in water;

the water-soluble acid is selected from one of phosphoric acid, hydrochloric acid and sulfuric acid;

the phosphate comprises at least one of sodium phosphate, calcium phosphate, magnesium phosphate, ammonium phosphate and the like;

Optionally, the organic solvent comprises at least one of acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, methyl isobutyl ketone, dimethyl carbonate, ethyl acetate, and ethylene glycol;

optionally, the mass ratio of the fructose to the organic solvent is as follows:

Fructose: organic solvent=1:0.8-10.

Optionally, the mass ratio of fructose to water satisfies:

fructose: water=1:0.8 to 10.

The mass ratio of the water to the inorganic salt is as follows:

Water: inorganic salt=1:0.05-2.

The addition amount of the acid catalyst is 0.1-5 wt% of the addition amount of the fructose.

Alternatively, the conditions of the reaction are: the reaction temperature is 60-180 ℃, the reaction time is 2-10 hours, and the flow rate of the reaction is 0.1L/min-20L/min.

Optionally, the detection of the yield of the 5-hydroxymethylfurfural adopts a high performance liquid chromatography method, and deionized water is added for mixing and constant volume during detection.

Optionally, the extracting agent is one of ethyl acetate or dimethyl carbonate, and the extracting process is to add the reaction liquid obtained after the reaction into the extracting agent for extraction operation; after standing and shaking uniformly, layering the solution, wherein the upper layer is an organic solution phase containing 5-hydroxymethylfurfural, and after separating the upper layer, adding ethyl acetate or dimethyl carbonate into the rest lower layer solution again for extraction, and repeating the operation for a plurality of times;

the volume ratio of the extractant to the reaction liquid is as follows: 1-3:1;

optionally, the number of times of repeating the operation of the extraction is 2 to 5.

Optionally, the conditions of the reduced pressure distillation include: the decompression operation is carried out for 0.5 to 3 hours at the temperature of 30 to 60 ℃ under the condition that the vacuum degree is 0.01 to 5 KPa.

Aiming at the defects in the prior art, the invention provides a high-efficiency solution. The invention provides a method for catalyzing fructose to be converted into 5-hydroxymethylfurfural by using inorganic salt, fructose, an organic solvent, water and an acid catalyst under continuous conditions. Compared with the traditional solvent system, the added inorganic salt can effectively avoid side reaction of the 5-hydroxymethylfurfural, improve the reaction conversion rate, ensure that the reacted reaction liquid is clear and transparent, has higher conversion rate and selectivity, is environment-friendly, has lower economic cost, is beneficial to industrial production and amplification, has low equipment maintenance cost, and can efficiently produce the high-purity 5-hydroxymethylfurfural.

Compared with the traditional method, the preparation method of the 5-hydroxymethylfurfural can effectively control the occurrence of side reaction, avoid the occurrence of black rot, improve the selectivity of the reaction and greatly reduce the equipment maintenance and labor cost.

The preparation method comprises the steps of adopting raw materials containing fructose, inorganic salt, organic solvent and water, carrying out dehydration reaction under the catalysis of an acid catalyst to obtain 5-hydroxymethylfurfural, wherein the added inorganic salt and homogeneous continuous reaction different from batch reaction effectively inhibit side reactions of the 5-hydroxymethylfurfural, no other impurities or black rot are generated after the reaction, extracting the 5-hydroxymethylfurfural by using dimethyl carbonate or ethyl acetate as an extractant after the reaction, and recycling and separating the extraction solvent from products by adopting a reduced pressure distillation method, wherein the side reactions are difficult to control in the traditional preparation process of the 5-hydroxymethylfurfural, and the generated black rot is extremely easy to cause equipment corrosion and blockage.

The preparation method of the 5-hydroxymethylfurfural comprises the following steps: the method comprises the steps of enabling a solution to flow through a heat exchanger under the catalysis of an acid catalyst, and reacting under continuous conditions to obtain the 5-hydroxymethylfurfural.

Optionally, the acid catalyst comprises at least one of an acid dissolved in water;

Alternatively, the water-soluble acid is a water-soluble acid selected from one of phosphoric acid, hydrochloric acid, sulfuric acid, and p-toluenesulfonic acid.

fructose: organic solvent=1:0.8-10;

Optionally, the upper limit of the mass ratio of the fructose to the organic solvent is selected from 1:0.8, 1:0.9, 1:

1. 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, or 1:9; the lower limit is selected from 1:10, 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, or 1:0.9.

Optionally, the mass ratio of fructose to water satisfies:

Fructose: water=1:0.8 to 10;

Optionally, the upper mass ratio of fructose to water is selected from 1:0.8, 1:0.9, 1:1, 1:dd220679i2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8 or 1:9; the lower limit is selected from 1:10, 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, or 1:0.9.

Optionally, the mass ratio of water to inorganic salt satisfies:

water: inorganic salt=1:0.05-2;

Optionally, the upper mass ratio of water to inorganic salt is selected from 1:0.05, 1:0.08, 1:0.1, 1:0.5, 1:0.8, 1:1.2, 1:1.4, 1.5, 1:1.6 or 1:1.8; the lower limit is selected from 1:2, 1:1.8, 1:1.5, 1:1.3, 1:1.2, 1:1, 1:0.8, 1:0.6, 1:0.8, 1:0.4, or 1:0.05.

Optionally, the addition amount of the acid catalyst is 0.1-5 wt% of the addition amount of the fructose.

Optionally, the upper limit of the mass percentage content of the added amount of the acid catalyst is selected from 0.2wt%, 0.5wt%, 0.8wt%, 1.0wt%, 1.5wt%, 2.0wt%, 2.5wt%, 3.0wt%, 3.5wt%, 4.0wt%, 4.5wt% or 5.0wt%; the lower limit is selected from 0.1wt%, 0.2wt%, 0.5wt%, 0.8wt%, 1.0wt%, 1.5wt%, 2.0wt%, 2.5wt%, 3.0wt%, 3.5wt%, 4.0wt% or 4.5wt%.

Alternatively, the conditions of the reaction are: the reaction temperature is 60-180 ℃, the reaction time is 2-10 hours, the flow rate of the reaction is 0.1L/min-20L/min, and the reaction liquid is obtained after the reaction.

Optionally, the reaction to produce 5-hydroxymethylfurfural is performed under stirring.

Alternatively, the upper temperature limit of the reaction is selected from 70 ℃, 80 ℃, 100 ℃,110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃, 175 ℃, or 180 ℃; the lower limit is selected from 60 ℃, 70 ℃, 90 ℃, 100 ℃,110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃ or 175 ℃.

Alternatively, the upper time limit of the reaction is selected from 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours; the lower limit is selected from 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours or 9 hours.

Optionally, after the reaction is finished, a certain amount of reaction liquid after the reaction is taken, deionized water is added to mix and fix the volume, and the detection of the yield of the 5-hydroxymethylfurfural is carried out.

Alternatively, the detection method used is high performance liquid chromatography: obtaining a liquid chromatography peak area by configuring the content of 5-hydroxymethylfurfural in a standard solution, and obtaining a standard curve by taking the peak area as an abscissa and the concentration of 5-hydroxymethylfurfural as an ordinate; further, the concentration of 5-hydroxymethylfurfural in the reaction liquid after the reaction can be calculated, and the yield of 5-hydroxymethylfurfural is calculated through the concentration.

Optionally, the reaction solution obtained after the reaction is added with ethyl acetate or dimethyl carbonate for extraction operation. After standing and shaking, layering the solution, wherein the upper layer is an organic solution phase containing 5-hydroxymethylfurfural, and after separating the upper layer, adding ethyl acetate or dimethyl carbonate into the rest lower layer solution again for extraction, and repeating the operation for a plurality of times.

Optionally, the volume ratio of the ethyl acetate or the dimethyl carbonate serving as the extractant to the reaction liquid is as follows: 1-3:1.

Optionally, the upper limit of the volume ratio of the extractant to the reaction liquid is selected from 3:1, 2.5:1, 2:1 or 1.5:1; the lower limit is selected from 1:1, 1.5:1, 2:1 or 2.5:1.

Optionally, the number of times of repeated operation of the extraction is 2-5 times.

Optionally, the upper limit of the number of extraction operations is selected from 5, 4 or 3; the lower limit is selected from 2, 3 or 4 times.

Optionally, the solvent ethyl acetate or dimethyl carbonate for extraction is recovered by vacuum distillation of the upper ethyl acetate or dimethyl carbonate extract, and the product 5-hydroxymethylfurfural is obtained.

Optionally, the conditions of the reduced pressure distillation include: and under the condition of vacuum degree of 0.01-5 KPa, the temperature is 30-60 ℃, and the pressure is reduced for 0.5-3 hours.

Optionally, in the reduced pressure distillation process, the upper limit of the vacuum degree of the system is selected from 0.02KPa, 0.05KPa, 0.1KPa, 0.5KPa, 1KPa, 2KPa, 3KPa, 4KPa, 4.5KPa or 5KPa; the lower limit is selected from 0.01KPa, 0.02KPa, 0.05KPa, 0.1KPa, 0.5KPa, 1KPa, 2KPa, 3KPa, 4KPa, or 4.5KPa.

Optionally, in the reduced pressure distillation process, the upper temperature limit of the reaction is selected from 60 ℃,55 ℃,50 ℃, 45 ℃,40 ℃ or 35 ℃; the lower limit is selected from 30 ℃, 35 ℃,40 ℃, 45 ℃,50 ℃ or 55 ℃.

Alternatively, in the reduced pressure distillation process, the upper time limit of the reduced pressure distillation operation is selected from 0.6 hours, 0.8 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours; the lower limit is selected from 2.5 hours, 2 hours, 1.5 hours, 1 hour, 0.8 hours, 0.6 hours or 0.5 hours.

Optionally, the yield of 5-hydroxymethylfurfural during the reaction is greater than 80%.

Optionally, the yield of 5-hydroxymethylfurfural in the reaction process is 80% -95%.

Optionally, the method comprises:

a) Mixing fructose, inorganic salt, an acid catalyst, an organic solvent and water to form a solution, and allowing the solution to flow through a heat exchanger for continuous reaction to obtain the 5-hydroxymethylfurfural. The reaction temperature is between 60 and 180 ℃, the reaction time is between 2 and 10 hours, and the flow rate of the reaction is between 0.1 and 20L/min;

b) And c), extracting the reaction liquid obtained after the reaction in the step a) with ethyl acetate or dimethyl carbonate for a plurality of times, and performing reduced pressure distillation on the ethyl acetate or the dimethyl carbonate after the plurality of times of extraction. Controlling the vacuum degree of the system at 0.01-5 KPa, the reaction temperature at 30-60 ℃, and the reduced pressure distillation operation time at 0.5-3 hours, thus obtaining the product 5-hydroxymethylfurfural.

As a specific embodiment, the method comprises:

1) Fructose, inorganic salt, organic solvent, water and catalyst are mixed uniformly and flow through a heat exchanger to react in a homogeneous phase state, the reaction temperature is between 60 and 180 ℃, the reaction time is between 2 and 10 hours, and the flow rate of the reaction is between 0.1 and 20L/min.

2) And (3) taking a small amount of the reaction liquid after the reaction in the step (1) to carry out liquid chromatography analysis, and determining the yield of the 5-hydroxymethylfurfural, wherein the yield of the 5-hydroxymethylfurfural is more than 80%. Adding ethyl acetate or dimethyl carbonate into the reaction liquid for multiple extraction operations, wherein the extraction times are 2-5 times, and after the extraction is finished, adopting reduced pressure distillation operation to obtain the product 5-hydroxymethylfurfural, connecting the device with a water pump or an oil pump for reduced pressure distillation, controlling the vacuum degree of the system to be 0.01-5 KPa, and controlling the reduced pressure distillation temperature to be 30-60 ℃ and the reduced pressure distillation operation time to be 0.5-3 hours.

The application has the beneficial effects that:

1) The application provides a preparation method of 5-hydroxymethylfurfural. Compared with the traditional method, the organic and inorganic phases added in the preparation process of the application have the advantages that the synergistic effect of the specific inorganic salt and the specific acid catalyst can effectively control the occurrence of side reaction, avoid the generation of black rot, improve the selectivity of the reaction and greatly reduce the equipment maintenance and labor cost.

2) The method used in the method is a homogeneous continuous type, is different from a system for synthesizing the 5-hydroxymethylfurfural by using a batch kettle type reactor, has larger economic benefit, lower system cost, less environmental pollution, simple operation, easy repetition, low equipment maintenance cost and can efficiently produce the high-purity 5-hydroxymethylfurfural.

Drawings

FIG. 1 is a hydrogen nuclear magnetic resonance spectrum of the product synthesized in example 1 of the present application.

FIG. 2 is a hydrogen nuclear magnetic spectrum of a 5-hydroxymethylfurfural standard.

FIG. 3 is a carbon nuclear magnetic spectrum of the product synthesized in example 1 of the present application.

FIG. 4 is a carbon nuclear magnetic spectrum of a 5-hydroxymethylfurfural standard.

Detailed Description

The present application is described in detail below with reference to examples, but the present application is not limited to these examples.

Unless otherwise indicated, all starting materials in the examples of the present application were purchased commercially.

The analysis method in the embodiment of the application is as follows:

the reaction solution was dissolved in deuteration reagent by using liquid nuclear magnetic resonance spectrometer model AVANCE II 400M manufactured by Bruce company to analyze nuclear magnetic resonance chart of carbon and hydrogen.

In the examples of the present application, the yield of 5-hydroxymethylfurfural was calculated by:

Obtaining a liquid chromatography peak area by configuring the content of 5-hydroxymethylfurfural in a standard solution, and obtaining a standard curve by taking the peak area as an abscissa and the concentration of 5-hydroxymethylfurfural as an ordinate; further, the concentration of 5-hydroxymethylfurfural in the reaction liquid after the reaction can be calculated, and the yield of 5-hydroxymethylfurfural is calculated through the concentration.

In the examples of the present application, the concentrations of concentrated sulfuric acid and hydrochloric acid used are described below:

concentrated sulfuric acid: h ₂SO₄ is 98.0 wt.%;

Hydrochloric acid: HCl was 37.0wt%.

According to one embodiment of the present application, the method for preparing 5-hydroxymethylfurfural comprises the steps of:

a) Mixing fructose, inorganic salt, an acid catalyst, an organic solvent and water to form a solution, flowing the solution through a heat exchanger, and reacting under homogeneous phase continuous reaction to obtain the 5-hydroxymethylfurfural, wherein the reaction temperature is between 60 and 180 ℃, the reaction time is between 2 and 10 hours, and the reaction flow rate is between 0.1 and 20L/min.

B) And c) taking a small amount of the reaction liquid after the reaction in the step a), and carrying out liquid chromatography analysis to determine the yield of the 5-hydroxymethylfurfural, wherein the yield of the 5-hydroxymethylfurfural is more than 80%. Adding ethyl acetate or dimethyl carbonate into the reaction liquid for multiple extraction operations, wherein the extraction times are 2-5 times, and after the extraction is finished, adopting reduced pressure distillation operation to obtain the product 5-hydroxymethylfurfural, connecting the device with a water pump or an oil pump for reduced pressure distillation, controlling the vacuum degree of the system to be 0.01-5 KPa, and controlling the reduced pressure distillation temperature to be 30-60 ℃ and the reduced pressure distillation operation time to be 0.5-3 hours.

Optionally, the inorganic salt in step a); including at least one of halogen compounds, borides, silicates, aluminates and phosphates;

The halogen compound comprises at least one of sodium chloride, sodium fluoride, magnesium chloride, calcium chloride, barium chloride, chromium chloride, ferric chloride, cupric chloride, aluminum chloride, sodium bromide, calcium bromide and magnesium bromide;

alternatively, the acidic catalyst in step a) comprises at least one of an acid dissolved in water such as phosphoric acid, hydrochloric acid, sulfuric acid, p-toluenesulfonic acid and the like;

alternatively, the water-soluble acid is a readily water-soluble acid;

optionally, the water-soluble acid includes at least one of sulfuric acid and sulfonic acid.

Optionally, the fructose and the organic solvent in step a) have the following mass ratios:

fructose: organic solvent=1:0.8-10;

Optionally, the fructose and water in step a) have the following mass ratios:

Fructose: water=1:0.8 to 10;

Optionally, the water and inorganic salt in step a) have the following mass ratios:

water: inorganic salt=1:0.05-5;

Optionally, the reaction conditions in step a) are: the reaction temperature is 60-180 ℃, the reaction time is 2-10 hours, the flow rate of the reaction is 0.1L/min-20L/min, and the reaction liquid is obtained after the reaction.

Optionally, taking a certain amount of reaction liquid after the reaction in the step b), adding deionized water, mixing to a certain volume, and detecting the yield of the 5-hydroxymethylfurfural.

Optionally, in the step b), the reaction solution obtained after the reaction is added into ethyl acetate or dimethyl carbonate for extraction operation. After standing and shaking, layering the solution, wherein the upper layer is an organic solution phase containing 5-hydroxymethylfurfural, and after separating the upper layer, adding ethyl acetate or dimethyl carbonate into the rest lower layer solution again for extraction, and repeating the operation for a plurality of times.

Optionally, the volume ratio of ethyl acetate or dimethyl carbonate in the step b) as the extractant to the reaction liquid is: 1-3:1.

Optionally, the number of times of repeating the operation of the extraction in the step b) is 2to 5.

Optionally, the extraction liquid of the upper ethyl acetate or the dimethyl carbonate in the step b) is subjected to a reduced pressure distillation method, the solvent ethyl acetate or the dimethyl carbonate for extraction is recovered, and the product 5-hydroxymethylfurfural is obtained at the same time.

Optionally, the conditions of reduced pressure distillation in step b) include: and under the condition of vacuum degree of 0.01-5 KPa, the temperature is 30-60 ℃, and the pressure is reduced for 0.5-3 hours.

Example 1

5G of fructose, 6.84g of sodium chloride, 4g of tetrahydrofuran and 5g of water are added into a container, 0.12g of concentrated sulfuric acid is dropwise added as a catalyst under the stirring state, after the raw materials are fully dissolved, the raw materials pass through a heat exchanger at the flow rate of 5L/min, the temperature is raised to 100 ℃, the continuous reaction time is 6 hours, and the color of a reaction solution is gradually deepened. And after the reaction is finished, taking a small amount of reaction liquid for high performance liquid chromatography analysis, wherein the result shows that the yield of the 5-hydroxymethylfurfural is 83%, the selectivity is 96%, dimethyl carbonate (the volume ratio of the dimethyl carbonate to the reaction liquid is 3:1) is added into the reaction liquid for multiple extraction operations, the extraction times are 2 times, the extraction liquid is obtained after the extraction is finished, the device is connected with a water pump or an oil pump for reduced pressure distillation, the vacuum degree of the system is controlled at 2KPa, the reduced pressure distillation temperature is 40 ℃, the reduced pressure distillation operation time is 1.5 hours, and the purity of the obtained 5-hydroxymethylfurfural is 97%.

Example 2

8G of fructose, 3g of aluminum chloride, 5g of acetonitrile and 6g of water are added into a container, 0.1g of phosphoric acid is added under stirring to serve as a catalyst, and after the raw materials are fully dissolved into homogeneous phase, the mixture passes through a heat exchanger at a flow rate of 5L/min, is heated to 150 ℃ and continuously reacts for 5 hours, so that the color of a reaction solution is gradually deepened. And after the reaction is finished, taking a small amount of reaction liquid for high performance liquid chromatography analysis, wherein the result shows that the yield of the 5-hydroxymethylfurfural is 88%, the selectivity is 98%, dimethyl carbonate (the volume ratio of the dimethyl carbonate to the reaction liquid is 2:1) is added into the reaction liquid for multiple extraction operations, the extraction times are 5 times, the extraction liquid is obtained after the extraction is finished, the device is connected with a water pump or an oil pump for reduced pressure distillation, the vacuum degree of the system is controlled at 3KPa, the reduced pressure distillation temperature is 50 ℃, the reduced pressure distillation operation time is 3 hours, and the purity of the obtained 5-hydroxymethylfurfural is 98%.

Examples 3 to 11

The specific ingredients, materials and reaction conditions are shown in Table 1, and the other operations in the synthesis process are the same as in example 1.

TABLE 1 raw material compositions, proportions and reduced pressure distillation conditions of examples 3 to 11

Example 12 liquid Nuclear magnetic resonance analysis

Liquid nuclear magnetic resonance analysis was performed on the 5-hydroxymethylfurfural prepared in examples 1 to 11, and typical examples are shown in fig. 1 and 3, and fig. 2 and 4 are standard spectra of 5-hydroxymethylfurfural. Fig. 1 corresponds to the hydrogen nuclear magnetic resonance spectrum of 5-hydroxymethylfurfural prepared in example 1, and it can be seen from a comparison of fig. 1 and fig. 2 that the 5-hydroxymethylfurfural prepared in example 1 has a typical standard hydrogen nuclear magnetic spectrum of 5-hydroxymethylfurfural.

FIG. 3 corresponds to the carbon nuclear magnetic resonance spectrum of 5-hydroxymethylfurfural prepared in example 1. As can be seen from a comparison of FIGS. 3 and 4, the carbon nuclear magnetic spectrum of 5-hydroxymethylfurfural prepared in example 1 has typical standard 5-hydroxymethylfurfural.

The test results for 5-hydroxymethylfurfural in other examples were similar to those described above, and standard 5-hydroxymethylfurfural was obtained by the present invention.

Comparative example 1

5G of fructose, 10g of water, 10g of tetrahydrofuran and 5g of sodium chloride are added into a batch kettle reactor, 0.1g of hydrochloric acid is added into the batch kettle reactor as a catalyst under a stirring state, the temperature is raised to 150 ℃, the reaction time is 5 hours, and the color of a reaction solution is gradually deepened. And after the reaction is finished, taking a small amount of reaction liquid for high performance liquid chromatography analysis, wherein the result shows that the yield of the 5-hydroxymethylfurfural is 74%, the selectivity is 84%, dimethyl carbonate (the volume ratio of the dimethyl carbonate to the reaction liquid is 2:1) is added into the reaction liquid for multiple extraction operations, the extraction times are 5 times, the extraction liquid is obtained after the extraction is finished, the device is connected with a water pump or an oil pump for reduced pressure distillation, the vacuum degree of the system is controlled at 3KPa, the reduced pressure distillation temperature is 50 ℃, the reduced pressure distillation operation time is 3 hours, and the purity of the obtained 5-hydroxymethylfurfural is 86%.

By contrast, the same reaction conditions were used, and the specific procedure was as follows: 5g of fructose, 10g of water, 10g of tetrahydrofuran and 5g of sodium chloride are added into a continuous reactor, 0.1g of hydrochloric acid is added into the reactor as a catalyst under stirring, the temperature is raised to 150 ℃ through a heat exchanger, the reaction time is 5 hours, and the color of a reaction solution is gradually deepened. And after the reaction is finished, taking a small amount of reaction liquid for high performance liquid chromatography analysis, wherein the result shows that the yield of the 5-hydroxymethylfurfural is 82%, the selectivity is 97%, dimethyl carbonate (the volume ratio of the dimethyl carbonate to the reaction liquid is 2:1) is added into the reaction liquid for multiple extraction operations, the extraction times are 5 times, the extraction liquid is obtained after the extraction is finished, the device is connected with a water pump or an oil pump for reduced pressure distillation, the vacuum degree of the system is controlled at 3KPa, the reduced pressure distillation temperature is 50 ℃, the reduced pressure distillation operation time is 3 hours, and the purity of the obtained 5-hydroxymethylfurfural is 97%.

Comparative example 2

5G of fructose, 8g of water and 4g of acetonitrile are added with 0.1g of sulfuric acid as a catalyst under stirring, and the temperature is raised to 140 ℃ through a heat exchanger in a continuous reactor, the reaction time is 3 hours, and the color of the reaction solution is gradually deepened. And after the reaction is finished, taking a small amount of reaction liquid for high performance liquid chromatography analysis, wherein the result shows that the yield of the 5-hydroxymethylfurfural is 63%, the selectivity is 84%, dimethyl carbonate (the volume ratio of the dimethyl carbonate to the reaction liquid is 2:1) is added into the reaction liquid for multiple extraction operations, the extraction times are 5 times, the extraction liquid is obtained after the extraction is finished, the device is connected with a water pump or an oil pump for reduced pressure distillation, the vacuum degree of the system is controlled at 3KPa, the reduced pressure distillation temperature is 50 ℃, the reduced pressure distillation operation time is 3 hours, and the purity of the obtained 5-hydroxymethylfurfural is 86%.

In contrast, using the same reaction conditions, 5g of sodium chloride was additionally added to the reaction, as follows: 5g of fructose and 8g of water are added with 0.1g of sulfuric acid as a catalyst under stirring, and the temperature is raised to 140 ℃ through a heat exchanger in a continuous reactor, the reaction time is 3 hours, and the color of the reaction solution is gradually deepened. And after the reaction is finished, taking a small amount of reaction liquid for high performance liquid chromatography analysis, wherein the result shows that the yield of the 5-hydroxymethylfurfural is 86%, the selectivity is 98%, dimethyl carbonate (the volume ratio of the dimethyl carbonate to the reaction liquid is 2:1) is added into the reaction liquid for multiple extraction operations, the extraction times are 5, the extraction liquid is obtained after the extraction is finished, the device is connected with a water pump or an oil pump for reduced pressure distillation, the vacuum degree of the system is controlled at 3KPa, the reduced pressure distillation temperature is 50 ℃, the reduced pressure distillation operation time is 3 hours, and the purity of the obtained 5-hydroxymethylfurfural is 98%.

While the application has been described in terms of preferred embodiments, it will be understood by those skilled in the art that various changes and modifications can be made without departing from the scope of the application, and it is intended that the application is not limited to the specific embodiments disclosed.

Claims

1. A method for preparing 5-hydroxymethylfurfural by organic-inorganic two-phase continuous fructose preparation, which is characterized by comprising the following steps:

2. The method of preparing according to claim 1, wherein the acid catalyst comprises at least one of phosphoric acid, hydrochloric acid, sulfuric acid, boric acid, and p-toluenesulfonic acid.

3. The preparation method according to claim 1, wherein the mass ratio of the fructose to the inorganic salt is 0.5 to 10: 0.001-2.

4. The preparation method according to claim 1, wherein the mass ratio of the fructose to the acidic catalyst is 0.5 to 10:0.01 to 1.

5. The preparation method according to claim 1, wherein the mass ratio of the fructose to the organic solvent is 0.5 to 10:1 to 20.

6. The preparation method according to claim 1, wherein the mass ratio of fructose to water is 0.5-10: 1 to 20.

7. The method of claim 1, further comprising the step of purifying:

After the reaction is finished, an extractant is added into the reaction liquid, an upper layer extract is obtained by extraction, and the upper layer extract is distilled under reduced pressure to obtain the 5-hydroxymethylfurfural.

8. The method of claim 7, wherein the volume ratio of the extractant to the reaction solution is 1-3:1.

9. The method of claim 7, wherein the extractant comprises at least one of ethyl acetate, dimethyl carbonate;

preferably, the number of extractions is 2 to 5.

10. The method according to claim 7, wherein the conditions of the reduced pressure distillation are: vacuum degree is 0.01-5 KPa, temperature is 30-60 ℃ and time is 0.5-3 hours.