CN117263888A - Method for decoloring and impurity removing of 5-hydroxymethylfurfural - Google Patents

Abstract

The invention discloses a method for decoloring and impurity removing of 5-hydroxymethylfurfural, which comprises the following steps: 1) Adding a crude HMF raw material into a beaker containing water, stirring while adding until the crude HMF raw material is fully dissolved to obtain an HMF aqueous solution, standing the HMF aqueous solution for primary sedimentation, and filtering after the sedimentation is finished to obtain supernatant for later use; 2) Adding the supernatant into a beaker, regulating the pH value of the supernatant, adding a flocculating agent to carry out secondary sedimentation, and filtering after the sedimentation is finished to obtain a clarified aqueous solution; 3) Adding a decoloring agent into the obtained clear aqueous solution for decoloring treatment, and filtering after the treatment is finished to obtain a colorless and transparent HMF aqueous solution; 4) Extracting the obtained colorless transparent HMF aqueous solution by using an organic solvent, and carrying out phase separation and distillation after extraction, wherein white HMF can be obtained after distillation is completed; the method adopts a two-stage sedimentation and decoloration mode, and effectively removes pigments and impurities of the crude HMF raw material.

Description

A method for decolorizing and removing impurities of 5-hydroxymethylfurfural

Technical field

The invention relates to the technical field of preparation of 5-hydroxymethylfurfural, and in particular to a method for decolorizing and removing impurities of 5-hydroxymethylfurfural.

Background technique

5-Hydroxymethylfurfural (HMF) is a very versatile compound that can be obtained from renewable biomass energy, especially sugar compounds. A variety of high value-added chemical monomers can be prepared through HMF , its downstream derivatives include 2,5-furandicarboxylic acid (DFF), 2,5-furandicarboxylic acid (FDCA), 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) and maleic acid (MA), etc. Starting from these derivatives, numerous chemical products that can replace petroleum-based products can be synthesized. They have huge potential in industry, so they are known as the "sleeping giant".

There are many methods for preparing HMF, but the method with the most research and reports at present and the fastest industrialization process is the acid-catalyzed sugar dehydration process. That is, a catalyst containing B acid is used, sugar is used as raw material, water, organic solvent, or a two-phase system of water and organic solvent is used to obtain HMF at a certain temperature. At present, the most commonly used solid acid catalysts are rich in B acid sites. The sugars used are mostly fructose and glucose, and the reaction is carried out under high temperature and high pressure. The conversion rate of fructose and the yield of HMF obtained in this way are relatively high, which is the first step to scale up HMF. Produce the most promising processes.

However, in this process, sugars are prone to excessive side reactions at high temperatures and generate more impurities, which makes subsequent separation and purification of HMF more difficult. Among them, the most difficult to deal with are the pigments and humins produced by the Maillard reaction of sugars. These impurities further polymerize under high temperature conditions, producing more black and difficult-to-remove humus, which not only makes equipment contamination difficult to clean, but also seriously affects the environment. Due to the quality of HMF, HMF often appears dark brown, which increases the difficulty of downstream derivative applications.

To this end, the present invention proposes a method for removing pigments from HMF during the preparation process. First, a sedimentation method is used to remove humus, and then a decolorizing agent is used to remove pigments. The resulting HMF is lighter in color and higher in purity; the method is simple and suitable Expand production on a large scale.

Contents of the invention

In view of the problems existing in the prior art, the object of the present invention is to provide a method for decolorizing and removing impurities of 5-hydroxymethylfurfural with a simple process route, high purification efficiency, and low product loss rate.

The technical solution of the present invention is as follows:

A method for decolorizing and removing impurities of 5-hydroxymethylfurfural, comprising the following steps:

1) Add the crude HMF raw material to the beaker filled with water and stir while adding until it is fully dissolved to obtain the HMF aqueous solution. Then let it stand for one-stage sedimentation. After the sedimentation is completed, filter it to obtain the supernatant liquid for later use;

2) Add the supernatant liquid obtained in step 1) into a beaker, adjust the pH value, and then add flocculant for second-stage sedimentation. After the sedimentation is completed, filter it to obtain a clear aqueous solution;

3) Add a decolorizing agent to the clear aqueous solution obtained in step 2) for decolorization. After the treatment is completed, filter to obtain a colorless and transparent HMF aqueous solution;

4) Use an organic solvent to extract the colorless and transparent HMF aqueous solution obtained in step 3). After extraction, perform phase separation and distillation. After the distillation is completed, white HMF can be obtained.

Further, in step 1) the content of HMF in the crude HMF raw material is not less than 40%; the water used is industrial water; the mass ratio of the crude HMF raw material equivalent to HMF dry weight and water is 1:1~100.

Further, the first-level settling time in step 1) is 5 to 30 minutes.

Further, the flocculant in step 2) is at least one of aluminum sulfate, ferric chloride, polyaluminum chloride, and polyacrylamide; wherein the mass ratio of the flocculant to the HMF aqueous solution in step 1) is 1:0.01 ~0.1; adjust the pH value to 5~9.

Further, in step 2), the flocculant is preferably polyaluminum chloride; the preferred pH value is 6~7.

Further, the time for secondary sedimentation in step 2) is 1 to 4 hours.

Further, the decolorizing agent in step 3) is at least one of activated clay, activated carbon, anion exchange resin, hydrogen peroxide, sodium hypochlorite, and ozone; the temperature of the decolorizing treatment is 50°C to 80°C, and the pH value is 3 to 6.

Further, in step 3), the decolorizing agent is activated carbon, and the addition ratio is 0.5% of the mass of the solution to be decolorized. Further, the pH value of the solution to be decolorized in step 3) is 4.

Further, the organic solvent in step 4) is at least one of ethyl acetate, dimethyl carbonate, methyl isobutyl ketone, dimethyl sulfoxide, and cyclohexane; the volume ratio of the organic solvent to the aqueous solution is 1 :0.1~10.

Compared with the prior art, the beneficial effects of the present invention are as follows:

1) This method uses flocculants and decolorants, and adopts two-stage sedimentation and decolorization methods to effectively remove pigments and impurities in crude HMF raw materials, and obtain high-purity and low-color HMF crystals with a purity of ≧99.8%;

2) The decolorization and impurity removal method of the present invention is simple, has high purification efficiency and low product loss rate, and can be completed using conventional industrial-grade reagents, making it suitable for large-scale production.

Description of the drawings

Figure 1 is a diagram of the product purified in Example 7 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the examples, but the scope of protection of the present invention is not limited to the described scope.

It should be noted that the crude HMF in the present invention is derived from the low-purity liquid HMF obtained by the inventor using acid-catalyzed dehydration of fructose, and other raw materials and solvents are conventional reagents.

Example 1

Add 100g of water to the beaker, then add 15g of crude HMF raw material with a purity of about 70%, stir for 5 minutes, fully dissolve, let stand for 60 minutes, perform a sedimentation, and then filter it to obtain the supernatant liquid. Adjust the pH value of the clear liquid to 4. Add 0.2g polyaluminum chloride, stir and mix, then let it stand for 2 hours for secondary sedimentation; then the solid and liquid are separated, and the obtained filtrate is used for later use.

Example 2

Add 100g of water to the beaker, then add 15g of crude HMF raw material with a purity of about 70%, stir for 5 minutes, let it stand for 60 minutes after being fully dissolved, perform a sedimentation, and then filter it to obtain the supernatant liquid. Adjust the pH of the clear liquid to 6 , add 0.2g aluminum sulfate, stir and mix, then let stand for 2 hours for secondary sedimentation. Afterwards, the solid and liquid are separated, and the obtained filtrate is used for later use.

Example 3

Add 100g of water to the beaker, then add 15g of crude HMF raw material with a purity of about 70%, stir for 5 minutes, let it stand for 60 minutes after being fully dissolved, perform a sedimentation, and then filter it to obtain the supernatant liquid. Adjust the pH of the clear liquid to 4 , add 0.2g ferric chloride, stir and mix, then let stand for 2 hours for secondary sedimentation. Afterwards, the solid and liquid are separated, and the obtained filtrate is used for later use.

Example 4

Add 100g of water to the beaker, then add 15g of crude HMF raw material with a purity of about 70%, stir for 5 minutes, fully dissolve, then let stand for 60 minutes, and perform a sedimentation. Then filter it to obtain the supernatant liquid, adjust the pH of the clear liquid to 4, add 0.2g polyacrylamide, stir and mix, and then let it stand for 2 hours for secondary sedimentation. Afterwards, the solid and liquid are separated, and the obtained filtrate is used for later use. The results of Examples 1-4 are shown in Table 1 below:

Table 1 Experimental results of Examples 1-4

Types of flocculants Polyaluminium chloride Aluminum sulfate ferric chloride polyacrylamide HMF concentration after treatment 9.95% 9.32% 9.54% 8.69% Precipitation quality 3.35g 2.17g 1.32g 0.44g Yellowness value 14.5 15.1 17.8 24.2

Examples 1 to 4 evaluated the flocculation and sedimentation effects of different flocculants. By comparison, it was found that the HMF aqueous solution after primary sedimentation obtained by using polyaluminum chloride in Example 1 had a lighter overall color, and more solid humus precipitation was obtained during the treatment process. , the best flocculation and sedimentation effect.

Example 5

Weigh 100g of the filtrate obtained in Example 1, add 1g of activated carbon, adjust the pH value to 4~5, stir and decolorize for 60 minutes at a temperature of 60°C, perform one decolorization, filter and separate the activated carbon after decolorization is completed, and obtain the filtrate. Add to the filtrate 0.5g activated carbon, stir and decolorize at 60°C for 30 minutes, perform secondary decolorization, and then filter and separate the activated carbon. The obtained colorless and transparent HMF aqueous solution is ready for use.

Example 6

Weigh 100g of the filtrate obtained in Example 1, add 1g of Tulsimer® A-30 MP anionic decolorizing resin for sugar, adjust the pH value to 8~9, stir and decolorize at 60°C for 60 minutes, perform one decolorization, and then filter and separate. Obtain the filtrate, add 0.5g of resin to the filtrate, stir and decolorize at 60°C for 30 minutes, perform secondary decolorization, and then filter and separate. The obtained colorless and transparent HMF aqueous solution is ready for use. The experimental results of Examples 5-6 are shown in Table 2 below.

Table 2 Experimental results of Examples 5-6

Types of decolorizing agents activated carbon anion exchange resin HMF concentration after treatment 8.71% 7.42% Yellowness value of primary decolorization 3.7 6.9 Secondary decolorization yellowness value 0.8 3.5 HMF loss rate 12% 15%

Examples 5 to 6 evaluated the decolorizing effects of two decolorizing agents. By comparison, it was found that the decolorized HMF aqueous solution obtained by using activated carbon in Example 5 had a significant decolorizing effect. The color was almost colorless after secondary decolorization, and the HMF loss rate during the treatment process was relatively small. Low, the decolorization effect is the best.

Example 7

Weigh 100g of the colorless and transparent HMF aqueous solution obtained in Example 5, add 500g of ethyl acetate, and stir and mix at 40°C for 60 minutes. Afterwards, the ethyl acetate is distilled out at 80°C, and the obtained liquid solution containing HMF is left to stand at -20°C for 6 to 12 hours for crystallization to obtain high-purity HMF crystals, as shown in Figure 1, with a purity of ≧99.8%. .

Claims (10)

1. A method for decolorizing and removing impurities of 5-hydroxymethylfurfural, which is characterized by comprising the following steps: 1) Add the crude HMF raw material to the beaker filled with water and stir while adding until it is fully dissolved to obtain the HMF aqueous solution. Then let it stand for one-stage sedimentation. After the sedimentation is completed, filter it to obtain the supernatant liquid for later use; 2) Add the supernatant liquid obtained in step 1) into a beaker, adjust the pH value, and then add flocculant for second-stage sedimentation. After the sedimentation is completed, filter it to obtain a clear aqueous solution; 3) Add a decolorizing agent to the clear aqueous solution obtained in step 2) for decolorization. After the treatment is completed, filter to obtain a colorless and transparent HMF aqueous solution; 4) Use an organic solvent to extract the colorless and transparent HMF aqueous solution obtained in step 3). After extraction, perform phase separation and distillation. After the distillation is completed, white HMF can be obtained. 2. A method for decolorizing and removing impurities of 5-hydroxymethylfurfural according to claim 1, characterized in that the content of HMF in the crude HMF raw material in step 1) is not less than 40%; the water used is industrial water. ; The mass of crude HMF raw material equivalent to the dry weight of HMF and water is 1:1~100. 3. A method for decolorizing and removing impurities of 5-hydroxymethylfurfural according to claim 1, characterized in that the primary sedimentation time in step 1) is 5 to 30 minutes. 4. A method for decolorizing and removing impurities of 5-hydroxymethylfurfural according to claim 1, characterized in that the flocculant in step 2) is aluminum sulfate, ferric chloride, polyaluminum chloride, polyacrylamide At least one of the following; wherein the mass ratio of the flocculant to the HMF aqueous solution in step 1) is 1:0.01~0.1; and the pH value is adjusted to 5~9. 5. A method for decolorizing and removing impurities of 5-hydroxymethylfurfural according to claim 4, characterized in that in step 2) the flocculant is preferably polyaluminum chloride; the preferred pH value is 6~7. 6. A method for decolorizing and removing impurities of 5-hydroxymethylfurfural according to claim 1, characterized in that the secondary sedimentation time in step 2) is 1 to 4 hours. 7. A method for decolorizing and removing impurities of 5-hydroxymethylfurfural according to claim 1, characterized in that the decolorizing agent in step 3) is activated clay, activated carbon, anion exchange resin, hydrogen peroxide, sodium hypochlorite, ozone At least one of the above; the temperature of the decolorization treatment is 50℃~80℃, and the pH value is 3~6. 8. A method for decolorizing and removing impurities of 5-hydroxymethylfurfural according to claim 1, characterized in that in step 3), the decolorizing agent is activated carbon, and the addition ratio is 0.5% of the mass of the solution to be decolorized. 9. A method for decolorizing and removing impurities of 5-hydroxymethylfurfural according to claim 1, characterized in that the pH value of the solution to be decolorized in step 3) is 4. 10. A method for decolorizing and removing impurities of 5-hydroxymethylfurfural according to claim 1, characterized in that the organic solvent in step 4) is ethyl acetate, dimethyl carbonate, methyl isobutyl ketone, Dimethyl sulfoxide, at least one of cyclohexane; the volume ratio of organic solvent to aqueous solution is 1:0.1~10.