A method for preparing 5-hydroxymethylfurfural from chitin catalyzed by a bifunctional catalytic system
By dissolving chitin in hexafluoroisopropanol and carrying out a hydrothermal reaction in an organic/aqueous solvent system, and using formic acid and silicotungstic acid catalysts, the problem of low yield in the conversion of chitin to 5-hydroxymethylfurfural was solved, realizing an efficient and low-cost preparation method suitable for industrial applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INST OF OCEANOLOGY - CHINESE ACAD OF SCI
- Filing Date
- 2024-03-18
- Publication Date
- 2026-06-19
AI Technical Summary
In existing technologies, the yield of chitin to 5-hydroxymethylfurfural is low, and there is a lack of low-cost and simple preparation methods, which limits its industrial production and application.
A bifunctional catalytic system was employed, which involved swelling and dissolving chitin in hexafluoroisopropanol, followed by a hydrothermal reaction in an organic/aqueous two-phase system. Using formic acid and silicotungstic acid catalysts, 5-hydroxymethylfurfural was obtained in high yield through extraction and separation. The catalyst can be recycled and reused.
The method achieves the preparation of 5-hydroxymethylfurfural with high purity and high yield, with a yield of over 40%. It is green, environmentally friendly, and energy-efficient, making it suitable for industrial production.
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Figure CN118146179B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of marine biomass chemistry, and in particular to a method for preparing 5-hydroxymethylfurfural from chitin using a bifunctional catalytic system. Background Technology
[0002] In recent years, value-added processing of crustacean biomass has emerged as a new field. By converting chitin from crustacean waste into value-added chemicals and materials, it not only contributes to environmental protection but also replaces fossil resources, promoting green and sustainable development. For example, a variety of high-value-added chemicals can be produced from chitin, including 5-hydroxymethylfurfural (5-HMF), levulinic acid, and lactic acid. 5-HMF is not only an important biomass chemical intermediate but also a key precursor in the production of plastics, fuels, and other industrial products. As a high-value-added bio-based platform compound, HMF is considered a bridge between traditional chemistry and green chemistry, possessing significant environmental and economic implications.
[0003] Previous research has primarily focused on the preparation of HMF from C6 monosaccharides such as glucose and fructose. However, studies on the direct production of HMF from chitin are relatively limited. Although chitin is an abundant biological resource with broad application potential, its conversion into valuable chemicals such as HMF remains challenging, with current yields of direct HMF conversion below 30%. The chemical stability and structural complexity of chitin are major obstacles to the conversion process. Its stable crystal structure and strong intermolecular hydrogen bonds make it difficult to dissolve in conventional solvents, leading to difficulties in subsequent depolymerization and catalytic reactions. Therefore, a relatively low-cost and simple method for the direct preparation of HMF from chitin is still lacking, severely limiting its industrial production and application. Summary of the Invention
[0004] In order to overcome the above-mentioned problems in the prior art, the present invention proposes a method for preparing 5-hydroxymethylfurfural from chitin using a bifunctional catalytic system.
[0005] The technical solution adopted by this invention to solve its technical problem is: a method for preparing 5-hydroxymethylfurfural from chitin using a bifunctional catalytic system, comprising:
[0006] Step 1: At room temperature, chitin is swollen and dissolved in hexafluoroisopropanol solution for 2-4 hours to obtain pretreated chitin film solid.
[0007] Step 2: Transfer the pretreated chitin from Step 1 to a thick-walled pressure-resistant bottle, add formic acid and silicotungstic acid, and carry out a hydrothermal reaction in an organic / aqueous solvent two-phase system. After the reaction, high-yield 5-hydroxymethylfurfural can be obtained by extraction and separation.
[0008] In step 1, the volume-to-mass ratio of hexafluoroisopropanol solvent to chitin is 500:1-6.
[0009] The volume-to-mass ratio of formic acid to silicotungstic acid is 2:1-3.
[0010] The above-mentioned bifunctional catalytic system for preparing 5-hydroxymethylfurfural from chitin involves a hydrothermal reaction in step 2, followed by repeated extraction of the reaction solution with ethyl acetate. The organic phases are then combined and vacuum rotary evaporation yields high-purity, high-yield 5-hydroxymethylfurfural.
[0011] In the above-mentioned bifunctional catalytic system for the preparation of 5-hydroxymethylfurfural from chitin, after the chitin is dissolved and swollen in step 1, it is transferred to a flask and separated by vacuum rotary evaporation to obtain a portion of hexafluoroisopropanol until a relatively hard chitin film-like solid is formed.
[0012] In the above-mentioned bifunctional catalytic system for the preparation of 5-hydroxymethylfurfural from chitin, the hydrothermal reaction temperature in step 2 is 120℃-170℃, and the reaction time is 30-150min.
[0013] The method for preparing 5-hydroxymethylfurfural from chitin using the above-mentioned bifunctional catalytic system, wherein the volume / mass (ml / g) ratio of chitin to the water / organic solvent two-phase system is 1:4-8.
[0014] The above-mentioned bifunctional catalytic system for preparing 5-hydroxymethylfurfural from chitin uses a water / organic solvent two-phase system, in which one of γ-valerolactone, dimethyltetrahydrofuran, methyl isobutyl ketone, and dimethyl sulfoxide-n-butanol is selected, and the aqueous phase is an aqueous formic acid solution.
[0015] The beneficial effects of this invention are as follows: The preparation process uses chitin as a raw material. Chitin can swell and dissolve in hexafluoroisopropanol reagent at low temperature and without a catalyst, and the internal structure of chitin undergoes reorganization, which is beneficial for improving the yield of 5-hydroxymethylfurfural. The bifunctional acid site catalytic system constructed in this invention enables the direct and efficient generation of 5-hydroxymethylfurfural (5-HMF) from chitin in an aqueous / organic two-phase solvent system. The reaction time is short and the reaction conditions are easy to achieve. In the two-phase system of the organic solvent, the generated HMF is continuously extracted into the organic phase, and the product can be obtained by concentrating the organic phase. Under preferred conditions, the 5-hydroxymethylfurfural prepared by this invention has few impurities, requires no purification treatment, and the yield can reach over 40%. The method of this invention is green, environmentally friendly, low-energy-consumption, simple in steps, and low in production cost. The catalyst can be recovered. Since the catalyst used is present in the aqueous phase, the unreacted catalyst can be recovered by extraction and filtration methods and directly used in the next reaction, which is more conducive to industrial production. Attached Figure Description
[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0017] Figure 1 This is a flowchart illustrating the preparation process of 5-hydroxymethylfurfural according to the present invention.
[0018] Figure 2 This is a high-performance liquid chromatogram of 5-hydroxymethylfurfural prepared in Example 1 of the present invention;
[0019] Figure 3 The image shows the solid XRD pattern of the chitin thin film prepared in Example 1 of this invention.
[0020] Figure 4 The image shows the carbon NMR spectrum of 5-hydroxymethylfurfural prepared in Example 1 of this invention. Detailed Implementation
[0021] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
[0022] This embodiment discloses a method for preparing 5-hydroxymethylfurfural from chitin using a bifunctional catalytic system. The preparation process is as follows: Figure 1 As shown, the specific steps include the following:
[0023] Step 1: At room temperature, chitin is swollen and dissolved in hexafluoroisopropanol solution for 2-4 hours to obtain pretreated chitin film solid.
[0024] Step 2: Transfer the pretreated chitin from Step 1 to a thick-walled, pressure-resistant bottle, add formic acid and silicotungstic acid, and carry out a hydrothermal reaction in an organic / aqueous two-phase system. After the reaction, extraction and separation yields 5-hydroxymethylfurfural in high yield. Since the added formic acid and silicotungstic acid catalysts are both present in the aqueous phase, the unreacted catalyst can be recovered by extraction filtration or other methods after the reaction is complete.
[0025] In step 1, the volume-to-mass ratio of hexafluoroisopropanol solvent to chitin is 500:1-6;
[0026] The volume-to-mass ratio of formic acid to silicotungstic acid is 2:1-3.
[0027] After the hydrothermal reaction in step 2, the reaction solution is repeatedly extracted with ethyl acetate, the organic phases are combined, and high-purity, high-yield 5-hydroxymethylfurfural is obtained by vacuum rotary evaporation.
[0028] After the chitin in step 1 is dissolved and swollen, it is transferred to a flask and separated by vacuum rotary evaporation to obtain some hexafluoroisopropanol until a relatively hard chitin film-like solid is formed.
[0029] In step 2, the hydrothermal reaction temperature is 120℃-170℃, and the reaction time is 30-150min.
[0030] The volume / mass (ml / g) ratio of chitin to the water / organic solvent two-phase system is 1:4-8.
[0031] The water / organic solvent two-phase system consists of one of γ-valerolactone, dimethyltetrahydrofuran, methyl isobutyl ketone, or dimethyl sulfoxide-n-butanol, with the aqueous phase being an aqueous formic acid solution.
[0032] Based on the above method, 5-hydroxymethylfurfural was prepared by selecting specific proportions of reactants and solvents, and comparisons were made with other conditions and proportions compared with the method disclosed in this embodiment, as follows.
[0033] Example 1
[0034] 1) Swelling and dissolution of chitin:
[0035] Chitosan (6g) was added to hexafluoroisopropanol (500ml) and stirred rapidly. After the chitosan swelled and dissolved in hexafluoroisopropanol for a period of time, it was transferred to a flask, and some of the hexafluoroisopropanol was separated by vacuum rotary evaporation until a relatively hard chitosan film-like solid was formed. The XRD pattern of the obtained chitosan film-like solid is shown below. Figure 3 As shown, from Figure 3 As can be seen, the structure of chitin changes significantly after dissolving and swelling in hexafluoroisopropanol solvent.
[0036] 2) Preparation of 5-hydroxymethylfurfural
[0037] The chitin film solid (200 mg) obtained after swelling and dissolution was transferred to a thick-walled pressure-resistant bottle (35 ml), and 4 ml of formic acid aqueous solution (11 M), 100 mg of silicotungstic acid, and 8 ml of dimethyltetrahydrofuran were added. The reaction was carried out at 170 °C for 150 min, cooled to room temperature in an ice-water bath, and the original reaction solution was taken. The pH was adjusted to neutral, and the yield of 5-hydroxymethylfurfural was determined to be 42.7% by high performance liquid chromatography. Since the added formic acid and silicotungstic acid catalysts are both present in the aqueous phase, the unreacted catalyst can be recovered by extraction filtration or other methods after the reaction is completed.
[0038] The high-performance liquid chromatogram of the prepared 5-hydroxymethylfurfural is shown below. Figure 2 As shown, the carbon NMR spectrum is as follows: Figure 4 As shown, by Figure 2 The high-performance liquid chromatogram shows that 5-hydroxymethylfurfural is present at wavelengths of 240 nm to 280 nm and retention times of 10 min to 13 min, with a distinct product peak and few impurity peaks.
[0039] Example 2
[0040] 1) Swelling and dissolution of chitin
[0041] Chitosan (6g) was added to hexafluoroisopropanol (500ml) and stirred rapidly. After the chitosan swelled and dissolved in hexafluoroisopropanol for a period of time, it was transferred to a flask and some of the hexafluoroisopropanol was separated by vacuum rotary evaporation until a relatively hard chitosan film-like solid was formed.
[0042] 2) Preparation of 5-hydroxymethylfurfural
[0043] The chitin film solid (200 mg) obtained after swelling and dissolution was transferred to a thick-walled pressure-resistant bottle (35 ml), and 4 ml of formic acid aqueous solution (14 M), 50 mg of silicotungstic acid, and 8 ml of dimethyltetrahydrofuran were added. The reaction was carried out at 170 °C for 150 min, cooled to room temperature in an ice-water bath, and the original reaction solution was taken. The pH was adjusted to neutral, and the yield of 5-hydroxymethylfurfural was determined to be 35.2% by high performance liquid chromatography. Since the added formic acid and silicotungstic acid catalysts were both present in the aqueous phase, the unreacted catalysts could be recovered by extraction and filtration after the reaction was completed.
[0044] Comparative Example 1
[0045] 1) Preparation of 5-hydroxymethylfurfural
[0046] Chitosan powder (200 mg) was transferred to a thick-walled pressure-resistant bottle (35 ml), 4 ml of formic acid aqueous solution (8 M) and 8 ml of dimethyltetrahydrofuran were added, and the mixture was reacted at 160 °C for 150 min. The mixture was then cooled to room temperature in an ice-water bath. The original reaction solution was taken, and the pH was adjusted to neutral. The yield of 5-hydroxymethylfurfural was determined to be 4.21% by high performance liquid chromatography.
[0047] Comparative Example 2
[0048] 1) Swelling and dissolution of chitin
[0049] Chitosan (6g) was added to hexafluoroisopropanol (500ml) and stirred rapidly. After the chitosan swelled and dissolved in hexafluoroisopropanol for a period of time, it was transferred to a flask and some of the hexafluoroisopropanol was separated by vacuum rotary evaporation until a relatively hard chitosan film-like solid was formed.
[0050] 2) Preparation of 5-hydroxymethylfurfural
[0051] The chitin film solid (200 mg) obtained after swelling and dissolution was transferred to a thick-walled pressure-resistant bottle (35 ml), 4 ml of formic acid aqueous solution (8 M) and 8 ml of dimethyltetrahydrofuran were added, and the reaction was carried out at 160 °C for 150 min. The mixture was then cooled to room temperature in an ice-water bath. The original reaction solution was taken, and the pH was adjusted to neutral. The yield of 5-hydroxymethylfurfural was determined to be 18.99% by high performance liquid chromatography.
[0052] Comparative Example 3
[0053] 1) Swelling and dissolution of chitin
[0054] Chitosan (6g) was added to hexafluoroisopropanol (500ml) and stirred rapidly. After the chitosan swelled and dissolved in hexafluoroisopropanol for a period of time, it was transferred to a flask and some of the hexafluoroisopropanol was separated by vacuum rotary evaporation until a relatively hard chitosan film-like solid was formed.
[0055] 2) Preparation of 5-hydroxymethylfurfural
[0056] The chitin film solid (200 mg) obtained after swelling and dissolution was transferred to a thick-walled pressure-resistant bottle (35 ml), and 4 ml of formic acid aqueous solution (11 M), 100 mg of silicotungstic acid, and 8 ml of methyl isobutyl ketone were added. The reaction was carried out at 170 °C for 150 min, cooled to room temperature in an ice-water bath, and the original reaction solution was taken. The pH was adjusted to neutral, and the yield of 5-hydroxymethylfurfural was determined to be 23.41% by high performance liquid chromatography. Since the added formic acid and silicotungstic acid catalysts were both present in the aqueous phase, the unreacted catalysts could be recovered by extraction and filtration after the reaction was completed.
[0057] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its scope and spirit, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of the present invention.
Claims
1. A process for the preparation of 5-hydroxymethylfurfural from chitin catalyzed by a bifunctional catalytic system, characterized in that, include: Step 1, swelling and dissolution of chitin: Add 6g of chitosan to 500ml of hexafluoroisopropanol and stir rapidly. After the chitosan swells and dissolves in hexafluoroisopropanol for a period of time, transfer it to a flask and separate some of the hexafluoroisopropanol by vacuum rotary evaporation until a relatively hard chitosan film-like solid is formed. Step 2, Preparation of 5-hydroxymethylfurfural: 200 mg of the chitin film solid obtained after swelling and dissolution was transferred to a 35 ml thick-walled pressure-resistant bottle. 4 ml of 11 M formic acid aqueous solution, 100 mg of silicotungstic acid, and 8 ml of dimethyltetrahydrofuran were added. The mixture was reacted at 170 °C for 150 min, cooled to room temperature in an ice-water bath, and the original reaction solution was taken. The pH was adjusted to neutral. The yield of 5-hydroxymethylfurfural was determined to be 42.7% by high performance liquid chromatography. After the reaction was completed, the unreacted catalyst was recovered by extraction and filtration.
2. A method for preparing 5-hydroxymethylfurfural from chitin using a bifunctional catalytic system, characterized in that, include: Step 1, swelling and dissolution of chitin Add 6g of chitosan to 500ml of hexafluoroisopropanol and stir rapidly. After the chitosan swells and dissolves in hexafluoroisopropanol for a period of time, transfer it to a flask and separate some of the hexafluoroisopropanol by vacuum rotary evaporation until a relatively hard chitosan film-like solid is formed. Step 2, Preparation of 5-hydroxymethylfurfural: 200 mg of chitin film solid obtained after swelling and dissolution was transferred to a 35 ml thick-walled pressure-resistant bottle, 4 ml of 14 M formic acid aqueous solution, 50 mg of silicotungstic acid, and 8 ml of dimethyltetrahydrofuran were added. The mixture was reacted at 170 °C for 150 min, cooled to room temperature in an ice-water bath, and the original reaction solution was taken. The pH was adjusted to neutral. The yield of 5-hydroxymethylfurfural was determined to be 35.2% by high performance liquid chromatography. After the reaction was completed, the unreacted catalyst was recovered by extraction and filtration.