Method for preparing 3-acetamido-5-acetylfuran from chitin
By using L-zeolite and doped L-zeolite catalytic systems, the corrosiveness and complex separation problems in the preparation of 3-acetamido-5-acetylfuran in existing technologies have been solved, realizing a highly efficient and reusable catalyst preparation method that is suitable for the field of biomass conversion.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2024-10-21
- Publication Date
- 2026-04-21
AI Technical Summary
Existing methods for preparing 3-acetamido-5-acetylfuran suffer from problems such as high corrosivity, low product selectivity, low efficiency, difficulty in reusing catalysts, and complex product separation, making industrialization difficult.
Using L-type molecular sieves and/or doped L-type molecular sieves as catalysts, chitin is converted into 3-acetamido-5-acetylfuran through a heterogeneous catalytic system. The reaction is carried out in a eutectic solvent using L-type molecular sieves with specific compositions and doped L-type molecular sieves. The catalysts are easy to separate and can be reused.
The efficient preparation of 3-acetamido-5-acetylfuran was achieved with high product yield, non-corrosive catalyst, simple process, and reusable catalyst, showing good prospects for industrial application.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of biomass conversion technology, and more specifically, to a method for preparing 3-acetamido-5-acetylfuran using chitin. Background Technology
[0002] Chitin, also known as chitosan, is a polysaccharide composed of N-acetylglucosamine (NAG) linked by β-1,4 glycosidic bonds. It is the only nitrogen-containing polysaccharide found in nature. The structure of chitin is as follows.
[0003]
[0004] Chitin is abundant in natural resources, widely found in shrimp and crab shells, insect exoskeletons, and microorganisms such as fungi and microalgae, with an annual production exceeding 1 billion tons. Furthermore, chitin is the most abundant naturally occurring nitrogen-containing polysaccharide. The conversion of chitin-based biomass into nitrogen-containing chemicals is of great significance for promoting the achievement of "two carbon" targets (carbon dioxide, carbon sequestration, and carbon emissions).
[0005] 3-Acetamido-5-acetylfuran (3A5AF) is a nitrogen-containing platform compound that can be converted into a series of nitrogen-containing downstream chemicals, with applications in materials preparation, pharmaceutical synthesis, pesticide synthesis, and fine chemicals. The structure of 3A5AF is as follows:
[0006]
[0007] From the structural unit NAG of chitin, chitin and NAG are ideal renewable raw materials for the preparation of 3A5AF. However, current research mostly uses N-acetylglucosamine as a raw material to prepare 3A5AF in homogeneous reactions with protic acids such as hydrochloric acid and boric acid, or Lewis acids such as CaCl2 metal salts, or with ionic liquids as catalysts. This method has insurmountable drawbacks such as strong corrosivity, low product selectivity, low efficiency, and complex separation.
[0008] L-type molecular sieves (International Molecular Sieve Association code: LTL) are macroporous molecular sieves with cylindrical crystals and a one-dimensional channel structure parallel to the cylindrical axis. They are formed by the stacking of alternating hexagonal columnar cages and nepheline cages along the C-axis, which are then rotated along a sixfold axis to generate twelve-membered ring channels. The pore size is 0.71 nm, and the kinetic diameter is 0.81 nm. Its pore size is close to that of NAG molecules, which is beneficial for the selective conversion of chitin and the formation of 3A5AF from NAG. Furthermore, by modifying the structure of L-type molecular sieves and controlling their acidity, the conversion efficiency can be improved.
[0009] Current reported methods for preparing 3A5AF from chitin and NAG mainly employ homogeneous catalytic systems, resulting in low yields (below 60%). Furthermore, these methods suffer from difficulties in product separation and the inability to reuse catalysts, hindering industrial-scale implementation. Additionally, the hydrolysis of chitin into chitosan oligosaccharides or NAG byproducts can negatively impact the activity of catalysts catalyzing the conversion of chitosan oligosaccharides or NAG to 3A5AF, leading to reduced catalytic efficiency or deactivation. Developing novel catalytic systems for the direct catalytic preparation of 3A5AF from chitin represents a promising direction for addressing these challenges; however, there are currently no reports on the direct catalytic preparation of 3A5AF from chitin using heterogeneous catalytic systems. Summary of the Invention
[0010] The purpose of this invention is to overcome the above-mentioned defects in the prior art and provide a method for preparing 3-acetamido-5-acetylfuran using chitin. This method utilizes L-zeolite and / or doped L-zeolite for efficient catalytic conversion of chitin to prepare 3A5AF, establishing a green technology for heterogeneous catalytic preparation of 3A5AF. Furthermore, this invention boasts high efficiency, higher product yield than existing methods, easily separable and reusable catalyst, and no corrosion to equipment, demonstrating excellent application prospects.
[0011] To achieve the above objectives, the technical solution of the present invention is as follows:
[0012] A method for preparing 3-acetamido-5-acetylfuran using chitin includes the following steps: dissolving chitin in a eutectic solvent, reacting it with an L-zeolite or a doped L-zeolite to obtain 3-acetamido-5-acetylfuran; wherein the molar ratio of the L-zeolite composition is (0.9–5.0)M. 2 / n O:Al2O3:(2~50)SiO2; wherein M is one or more of K, Na, Mg, Ca, Cr, Ce, Fe, Sn, B and Zr; n is the valence of M; the doped L molecular sieve is a molecular sieve doped with heteroatoms; the heteroatoms include one or more of Fe, Cr, Mg, Zr, Sn, Cu, Zn, Ni, Ce and B.
[0013] Optionally, the doping amount of heteroatoms in the doped L molecular sieve is 0.1% to 10%.
[0014] Optionally, the chitin has a mass concentration of 0.1% to 15% in the eutectic solvent.
[0015] Optionally, the mass ratio of the L-molecular sieve to chitin is 1:500 to 20:1. 。
[0016] Optionally, the mass ratio of the doped L molecular sieve to chitin is 1:500 to 20:1.
[0017] Optionally, the mass concentration of the chitin is 1% to 10%.
[0018] Optionally, the mass ratio of the L molecular sieve to chitin is 1:100 to 10:1.
[0019] Optionally, the mass ratio of the doped L molecular sieve to chitin is 1:100 to 10:1.
[0020] Optionally, the reaction temperature is 80℃ to 300℃; the reaction time is 10 minutes to 12 hours.
[0021] Optionally, the reaction temperature is 100℃ to 200℃; the reaction time is 10 minutes to 8 hours.
[0022] Optionally, the eutectic solvent includes a hydrogen bond acceptor and a hydrogen bond donor; the hydrogen bond acceptor includes one or more of benzyltrimethylammonium chloride, choline chloride, and trimethylglycine.
[0023] Optionally, the hydrogen bond donor includes one or more of organic acids, lower alcohols, and urea.
[0024] Optionally, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:(1-5).
[0025] Optionally, the organic acid includes one or more of lactic acid, malic acid, citric acid, and oxalic acid.
[0026] Optionally, the lower alcohol includes one or both of ethylene glycol and glycerol.
[0027] Optionally, the reaction is carried out in a reactor; the reactor includes one or more of a fixed-bed reactor, a fluidized-bed reactor, and a batch reactor.
[0028] Optionally, the L-zeolite is prepared by a solvent-free method, comprising the following steps:
[0029] (1) Mix the solid silicon source and the solid potassium source and grind them in a mortar.
[0030] (2) Add the solid aluminum source to the sample ground in step (1) and continue grinding.
[0031] (3) Place the ground sample from step (2) into a reaction vessel and carry out a crystallization reaction.
[0032] (4) The crystallized sample from step (3) is calcined in air to obtain the L molecular sieve.
[0033] Optionally, in step (1), the solid silicon source includes one or more of solid silica gel and fumed silica; the solid potassium source includes one or more of potassium hydroxide, potassium bromide and potassium silicate; the molar ratio of the solid silicon source to the solid potassium source is 1:(1-10); and the grinding time is 10 min to 120 min.
[0034] Optionally, in step (2), the solid aluminum source includes one or more of aluminum hydroxide, sodium aluminate and aluminum sulfate; the molar ratio of the solid aluminum source to the solid silicon source is 1:(3-50); and the grinding time is 10 min to 60 min.
[0035] Optionally, in step (3), the temperature of the crystallization reaction is 170℃~200℃; the time of the crystallization reaction is 4h~24h.
[0036] Optionally, in step (4), the calcination temperature is 400℃~600℃; the calcination time is 1h~5h.
[0037] Optionally, the preparation method of the doped L-zeolite is a solvent-free method, comprising the following steps:
[0038] (1) Mix the solid silicon source, solid potassium source and solid heteroatom compound and grind them in a mortar.
[0039] (2) Add the solid aluminum source to the sample ground in step (1) and continue grinding.
[0040] (3) Place the ground sample from step (2) into a reaction vessel and carry out a crystallization reaction.
[0041] (4) The crystallized sample from step (3) is calcined in air to obtain the doped L molecular sieve.
[0042] Optionally, in step (1), the solid potassium source includes one or more of potassium hydroxide, potassium bromide, and potassium silicate; the solid silicon source includes one or two of solid silica gel and precipitated silica; the heteroatom compound includes one or more of ferric chloride, chromium chloride, magnesium chloride, zirconium chloride, tin chloride, copper chloride, zinc chloride, nickel chloride, cerium chloride, boric acid, and boron oxide; the molar ratio of the solid silicon source to the solid potassium source is 1:1 to 1:10; the molar ratio of the heteroatom compound to the solid silicon source is 1:10 to 1:100; and the grinding time is 10 min to 120 min.
[0043] Optionally, in step (2), the solid aluminum source includes one or more of aluminum hydroxide, sodium aluminate and aluminum sulfate; the molar ratio of the solid aluminum source to the solid silicon source is 1:3 to 1:50; and the grinding time is 10 min to 60 min.
[0044] Optionally, in step (3), the temperature of the crystallization reaction is 170℃~200℃; the time of the crystallization reaction is 4h~24h.
[0045] Optionally, in step (4), the calcination temperature is 400℃~550℃ and the calcination time is 1h~6h.
[0046] The present invention also discloses a 3-acetamido-5-acetylfuran prepared by the preparation method described above.
[0047] Implementing the embodiments of the present invention will have the following beneficial effects:
[0048] 1. Based on extensive experiments, this invention has discovered that L molecular sieves with specific compositions can efficiently and directly catalyze the preparation of 3A5AF from chitin, saving the process of hydrolyzing chitin into oligomers or NAG. It has advantages such as high catalytic efficiency, high product selectivity, no corrosion, easy product separation, and simple process.
[0049] 2. The preparation method of 3-acetamido-5-acetylfuran provided by the present invention uses L molecular sieves and doped L molecular sieves as catalysts, which has precise pore type selectivity and suitable acidity, resulting in higher efficiency.
[0050] 3. The method for preparing 3-acetamido-5-acetylfuran by L molecular sieve and doped L molecular sieve catalysis provided by the present invention adopts a multiphase reaction system, the product is easy to separate, and the catalyst can be reused.
[0051] 4. The preparation method of 3-acetamido-5-acetylfuran provided by the present invention uses chitin directly as raw material, which is simple and more economical. Detailed Implementation
[0052] The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention in any way.
[0053] Example 1. Solvent-free preparation of L-molecular sieves
[0054] Weigh 1.80g of solid raw materials, including silica and potassium hydroxide, and grind them in a mortar for 15 minutes. Then add 0.936g of aluminum hydroxide and grind for another 20 minutes. Add the reaction raw materials to a polytetrafluoroethylene stainless steel reactor and crystallize at 170℃ for 24 hours. The product obtained does not need to be filtered or washed. It is directly calcined at 550℃ for 4 hours in air to obtain the final L molecular sieve.
[0055] The silicon source is calculated as SiO2, the potassium source as K2O, and the aluminum source as Al2O3.
[0056] The resulting L molecular sieve has the following molar ratio: 3.5K2O:2Al2O3:10SiO2.
[0057] By adding different amounts of aluminum hydroxide, L molecular sieves with different Si / Al ratios can be prepared.
[0058] Example 2. Solvent-free preparation of L-molecular sieves
[0059] Weigh 1.8g of solid raw material, silica, and 0.841g of sodium hydroxide, and grind them in a mortar for 15 minutes. Then add 0.468g of aluminum hydroxide and grind for another 20 minutes. Add the reaction raw material to a polytetrafluoroethylene stainless steel reactor and crystallize at 170℃ for 24 hours. The product obtained does not need to be filtered or washed. It is directly calcined at 550℃ for 4 hours in air to obtain the final L molecular sieve.
[0060] The silicon source is calculated as SiO2, the sodium source as Na2O, and the aluminum source as Al2O3.
[0061] The resulting L molecular sieve has the following molar ratio: 3.5Na2O:2Al2O3:20SiO2.
[0062] Example 3. Preparation of doped L-zeolite
[0063] (1) Solvent-free preparation of 0.7% Cr-L catalyst:
[0064] First, weigh 1.8g of solid raw materials, 1.178g of potassium hydroxide, and 0.475g of chromium chloride, and grind them in a mortar for 15 minutes. Then add 0.234g of aluminum hydroxide and grind for another 20 minutes. Add the reaction raw materials to a polytetrafluoroethylene stainless steel reactor and crystallize at 170℃ for 24 hours. The product obtained does not need to be filtered or washed and is directly calcined at 550℃ for 4 hours in an air atmosphere to obtain the final Cr-doped L molecular sieve.
[0065] Fourier transform infrared spectrum at 900 cm⁻¹ -1 The absorption peak at this point is attributed to the vibration of Si-O-Cr, and the X-ray electron spectroscopy peaks at binding energies of 579.8 eV and 588 eV correspond to Cr 2p, respectively. 3 / 2 and Cr 2p 1 / 2 This further indicates the presence of Cr(VI). All of the above results demonstrate that Cr atoms have entered the L molecular sieve framework.
[0066] (2) Solvent-free preparation of 0.35% Zr-L catalyst:
[0067] First, weigh 1.8g of solid silica gel, 1.178g of potassium hydroxide, and 0.370g of zirconium chloride into a mortar and grind for 15 minutes. Then add 0.234g of aluminum hydroxide and grind for another 20 minutes. Add the reaction materials to a polytetrafluoroethylene stainless steel reactor and crystallize at 170℃ for 24 hours. The product obtained does not need to be filtered or washed. It is directly calcined at 550℃ for 4 hours in air to obtain the final Zr-doped L molecular sieve.
[0068] Fourier transform infrared spectrum at 950 cm⁻¹ -1 The absorption peaks at these locations are attributed to vibrations in Si-O-Zr. The X-ray electron spectroscopy peaks at binding energies of 182.5 eV and 184.9 eV correspond to Zr 3d... 5 / 2 and Zr 3d 3 / 2 The above results all indicate that Zr atoms have entered the L molecular sieve framework.
[0069] (3) Solvent-free preparation of 0.07% Sn-L catalyst:
[0070] First, weigh 1.8g of solid raw materials, 1.19g of potassium bromide, and 0.078g of tin chloride, and grind them in a mortar for 15 minutes. Then, add 0.246g of sodium aluminate and grind for another 20 minutes. Add the reaction raw materials to a polytetrafluoroethylene stainless steel reactor and crystallize at 170℃ for 24 hours. The resulting product does not require filtration or washing and is directly calcined at 550℃ for 4 hours in air to obtain the final Sn-doped L molecular sieve.
[0071] Fourier transform infrared spectrum at 960 cm⁻¹ -1 The absorption peaks at these locations are attributed to the asymmetric stretching vibrations of Si-O-Sn, while the X-ray electron spectroscopy peaks at binding energies of 487.9 eV and 496.4 eV are attributed to the framework tetrahedral Sn species. These results all indicate that Sn atoms have entered the L molecular sieve framework.
[0072] (4) Solvent-free preparation of 0.7% Mg-L catalyst:
[0073] First, weigh 1.8g of solid raw materials, 2.6g of potassium silicate, and 0.286g of magnesium chloride, and grind them in a mortar for 15 minutes. Then add 0.99g of aluminum sulfate and grind for another 20 minutes. Add the reaction raw materials to a polytetrafluoroethylene stainless steel reactor and crystallize at 170℃ for 24 hours. The product obtained does not need to be filtered or washed. It is directly calcined at 550℃ for 4 hours in an air atmosphere to obtain the final Mg-doped L molecular sieve.
[0074] Fourier transform infrared spectrum at 640 cm⁻¹ -1The absorption peak at this location is attributed to the vibrational peak of Si-O-Mg, and the X-ray electron spectroscopy peak at a binding energy of 52.2 eV is attributed to the Mg species in the framework. These results all indicate that Mg atoms have entered the L-zeolite framework.
[0075] (5) Solvent-free preparation of 0.7% Ce-L catalyst:
[0076] First, weigh 1.8g of solid raw materials, 1.178g of potassium hydroxide, and 0.739g of cerium chloride, and grind them in a mortar for 15 minutes. Then add 0.234g of aluminum hydroxide and grind for another 20 minutes. Add the reaction raw materials to a polytetrafluoroethylene stainless steel reactor and crystallize at 170℃ for 24 hours. The product obtained does not need to be filtered or washed. It is directly calcined at 550℃ for 4 hours in an air atmosphere to obtain the final Ce-doped L molecular sieve.
[0077] Fourier transform infrared spectrum at 960 cm⁻¹ -1 The absorption peak at [location] is attributed to the vibrational peak of Si-O-Ce, and the X-ray electron spectroscopy peak at a binding energy of 916 eV is attributed to the Ce species in the framework. These results all indicate that Ce atoms have entered the L molecular sieve framework.
[0078] (6) Solvent-free preparation of 0.7% Zn-L catalyst:
[0079] First, weigh 1.8g of solid raw materials, 1.178g of potassium hydroxide, and 0.408g of zinc chloride, and grind them in a mortar for 15 minutes. Then add 0.234g of aluminum hydroxide and grind for another 20 minutes. Add the reaction raw materials to a polytetrafluoroethylene stainless steel reactor and crystallize at 170℃ for 24 hours. The product obtained does not need to be filtered or washed. It is directly calcined at 550℃ for 4 hours in an air atmosphere to obtain the final Zn-doped L molecular sieve.
[0080] Fourier transform infrared spectrum at 968 cm⁻¹ -1 The absorption peak at [location] is attributed to the vibrational peak of Si-O-Zn, and the X-ray electron spectroscopy peak at a binding energy of 1022.5 eV is attributed to the Zn species in the framework. These results all indicate that Zn atoms have entered the L-zeolite framework.
[0081] (7) Solvent-free preparation of 0.7% Ni-L catalyst:
[0082] First, weigh 1.8g of solid raw materials, 1.178g of potassium hydroxide, and 0.389g of nickel chloride, and grind them in a mortar for 15 minutes. Then add 0.234g of aluminum hydroxide and grind for another 20 minutes. Add the reaction raw materials to a polytetrafluoroethylene stainless steel reactor and crystallize at 170℃ for 24 hours. The product obtained does not need to be filtered or washed and is directly calcined at 550℃ for 4 hours in an air atmosphere to obtain the final Ni-doped L molecular sieve.
[0083] Fourier transform infrared spectrum at 970 cm⁻¹ -1 The absorption peaks at this point are attributed to the vibrations of Si-O-Ni. The X-ray electron spectroscopy peaks at binding energies of 858.7 eV and 876.5 eV correspond to Ni 2P, respectively. 3 / 2 and Ni 2P 1 / 2 This indicates the presence of a four-coordinated nickel framework. All of the above results demonstrate that Ni atoms have entered the L-zeolite framework.
[0084] (8) Solvent-free preparation of 0.7% Cu-L catalyst:
[0085] First, weigh 1.8g of solid raw materials, 1.178g of potassium hydroxide, and 0.403g of copper chloride, and grind them in a mortar for 15 minutes. Then add 0.234g of aluminum hydroxide and grind for another 20 minutes. Add the reaction raw materials to a polytetrafluoroethylene stainless steel reactor and crystallize at 170℃ for 24 hours. The product obtained does not need to be filtered or washed. It is directly calcined at 550℃ for 4 hours in an air atmosphere to obtain the final Cu-doped L molecular sieve.
[0086] Fourier transform infrared spectrum at 960 cm⁻¹ -1 The absorption peak at this point is attributed to the asymmetric stretching vibration peak of Si-O-Cu, and the X-ray electron spectroscopy peaks at binding energies of 934 eV and 953.4 eV correspond to Cu2P, respectively. 3 / 2 and Cu 2P 1 / 2 The above results all indicate that Cu atoms have entered the L molecular sieve framework.
[0087] (9) Solvent-free preparation of 0.7% Fe-L catalyst:
[0088] First, weigh 1.8g of solid raw materials, 1.178g of potassium hydroxide, and 0.487g of ferric chloride, and grind them in a mortar for 15 minutes. Then add 0.234g of aluminum hydroxide and grind for another 20 minutes. Add the reaction raw materials to a polytetrafluoroethylene stainless steel reactor and crystallize at 170℃ for 24 hours. The product obtained does not need to be filtered or washed. It is directly calcined at 550℃ for 4 hours in an air atmosphere to obtain the final Fe-doped L molecular sieve.
[0089] Fourier transform infrared spectrum at 652 cm⁻¹ -1The absorption peak at this point is attributed to the asymmetric stretching vibration peak of Si-O-Fe, and the X-ray electron spectroscopy peaks at binding energies of 711.1 eV and 724 eV correspond to Fe 2P, respectively. 3 / 2 and Fe 2P 1 / 2 The above results all indicate that Fe atoms have entered the L molecular sieve framework.
[0090] (10) Solvent-free preparation of 0.7% BL catalyst:
[0091] First, weigh 1.8g of solid raw materials, 1.178g of precipitated silica, 0.185g of potassium hydroxide, and 0.185g of boric acid. Pour them into a mortar and grind for 15 minutes. Then add 0.234g of aluminum hydroxide and grind for another 20 minutes. Add the reaction raw materials to a polytetrafluoroethylene stainless steel reactor and crystallize at 170℃ for 24 hours. The product obtained does not need to be filtered or washed. It is directly calcined at 550℃ for 4 hours in an air atmosphere to obtain the final B-doped L molecular sieve.
[0092] Fourier transform infrared spectrum at 900 cm⁻¹ -1 The absorption peak at this point is attributed to the vibrational peak of Si-OB, and the X-ray electron spectroscopy peak at a binding energy of 1310 eV is attributed to the B species in the framework. These results all indicate that B atoms have entered the L molecular sieve framework.
[0093] (11) Solvent-free preparation of 0.7% BL catalyst:
[0094] First, weigh 1.8g of solid raw materials, 1.178g of potassium hydroxide, and 0.209g of boron oxide, and grind them in a mortar for 15 minutes. Then add 0.234g of aluminum hydroxide and grind for another 20 minutes. Add the reaction raw materials to a polytetrafluoroethylene stainless steel reactor and crystallize at 170℃ for 24 hours. The product obtained does not need to be filtered or washed and is directly calcined at 550℃ for 4 hours in an air atmosphere to obtain the final B-doped L molecular sieve.
[0095] (12) Solvent-free preparation of 0.35% BL catalyst:
[0096] First, weigh 1.8g of solid raw materials, 1.178g of potassium hydroxide, and 0.105g of boron oxide, and grind them in a mortar for 15 minutes. Then add 0.234g of aluminum hydroxide and grind for another 20 minutes. Add the reaction raw materials to a polytetrafluoroethylene stainless steel reactor and crystallize at 170℃ for 24 hours. The product obtained does not need to be filtered or washed and is directly calcined at 550℃ for 4 hours in an air atmosphere to obtain the final B-doped L molecular sieve.
[0097] (13) Solvent-free preparation of 0.07% BL catalyst:
[0098] First, weigh 1.8g of solid raw materials, 1.178g of potassium hydroxide, and 0.021g of boron oxide, and grind them in a mortar for 15 minutes. Then add 0.234g of aluminum hydroxide and grind for another 20 minutes. Add the reaction raw materials to a polytetrafluoroethylene stainless steel reactor and crystallize at 170℃ for 24 hours. The product obtained does not need to be filtered or washed and is directly calcined at 550℃ for 4 hours in an air atmosphere to obtain the final B-doped L molecular sieve.
[0099] Example 4. L-type molecular sieve catalysis for the preparation of 3-acetamido-5-acetylfuran from chitin.
[0100] Typical preparation process of eutectic solvent: Add hydrogen bond donor and hydrogen bond acceptor to a round bottom flask according to the set molar ratio, and stir at 400 rpm for 1 hour under heating at 100°C to form a transparent solution.
[0101] 3.72 g (16.3 mmol) of benzyltrimethylammonium chloride and 6.28 g (32.6 mmol) of citric acid were added to a 100 mL round-bottom flask and stirred at 400 rpm for 1 h at 100 °C to form a clear solution. 0.50 g of chitin was dissolved in the above solvent; 0.05 g of the L molecular sieve with a Si / Al ratio of 2.5 prepared in Example 1 was added, and the reaction was carried out at 160 °C for 60 min. High-performance liquid chromatography (HPLC) analysis showed that the yield of 3A5AF was 78.5%.
[0102] Comparative Example 2. Hydrothermal Preparation of L-Molecular Sieves Catalyzed Chitin for the Preparation of 3-Acetamido-5-Acetfuran
[0103] 3.72 g (16.3 mmol) of benzyltrimethylammonium chloride and 6.28 g (32.6 mmol) of citric acid were added to a 100 mL round-bottom flask and stirred at 400 rpm for 1 h at 100 °C to form a clear solution. 0.50 g of chitin was dissolved in the above solvent; 0.05 g of L molecular sieve with a Si / Al ratio of 2.5 prepared by hydrothermal method was added, and the reaction was carried out at 160 °C for 60 min. High-performance liquid chromatography (HPLC) analysis showed that the yield of 3A5AF was 21.3%.
[0104] Example 5. Preparation of 3-acetamido-5-acetylfuran from chitin catalyzed by doped L-zeolite
[0105] 3.72 g (16.3 mmol) of benzyltrimethylammonium chloride and 6.28 g (32.6 mmol) of citric acid were added to a 100 mL round-bottom flask and stirred at 400 rpm for 1 h at 100 °C to form a clear solution. 0.50 g of chitin was dissolved in the above solvent; 0.05 g of the B-doped L molecular sieve prepared in Example 3 (10) was added, and the mixture was reacted at 160 °C for 60 min. High-performance liquid chromatography analysis showed that the yield of 3A5AF was 87.6%.
[0106] Comparative Example 3
[0107] In the traditional comparative example 1, the impregnation method was used to synthesize B-supported L molecular sieve (B / L) to catalyze the preparation of 3-acetamido-5-acetamidofuran from N-acetylglucosamine.
[0108] 3.72 g (16.3 mmol) of benzyltrimethylammonium chloride and 6.28 g (32.6 mmol) of citric acid were added to a 100 mL round-bottom flask and stirred at 400 rpm for 1 h at 100 °C to form a clear solution. 0.50 g of chitin was dissolved in the above solvent; 0.05 g of the B-doped L molecular sieve prepared in Comparative Example 1 was added, and the reaction was carried out at 160 °C for 60 min. High-performance liquid chromatography (HPLC) analysis showed that the yield of 3A5AF was 27.6%.
[0109] The heteroatom-doped L molecular sieve prepared by this invention shows a significant increase in the yield of 3A5AF after heteroatom doping modification, indicating that the method of this invention can effectively improve the catalytic performance of L molecular sieves, thereby increasing the yield of 3A5AF.
[0110] Example 6. Preparation of 3-acetamido-5-acetylfuran from chitin catalyzed by L-zeolite and doped L-zeolite under different conditions.
[0111] L-molecule sieves and doped L-molecule sieves prepared according to the methods of Examples 1-3 were used to catalyze the chitin conversion to prepare 3-acetamido-5-acetylfuran under different conditions. The yield of 3A5AF obtained in Example 4 was analyzed by high performance liquid chromatography, and the results are shown in Table 1.
[0112] Table 1. Preparation of 3A5AF from chitin catalyzed by L-zeolite and doped L-zeolite under different conditions
[0113]
[0114]
[0115]
[0116] Example 7. Lifetime experiment of L-molecular sieve catalysis for the preparation of 3-acetamido-5-acetylfuran from chitin.
[0117] 0.50 g of chitin was dissolved in a eutectic solvent of 10 g benzyltrimethylammonium chloride and citric acid in a ratio of 1:2. 0.10 g of the L-type molecular sieve with a Si / Al ratio of 5 prepared in Example 2 was added, and the mixture was reacted at 170°C for 1 hour. The molecular sieve was separated by centrifugation, and the mixture was again added to a eutectic solvent of 10 g benzyltrimethylammonium chloride and citric acid in a ratio of 1:2 containing 0.50 g of chitin. The reaction was repeated at 170°C for 1 hour; this process was repeated 5 times. Using 3A5AF obtained in Example 4 as a standard, high-performance liquid chromatography (HPLC) analysis showed that the yields of 3A5AF after the five reactions were 90.6%, 90.3%, 90.4%, 90.1%, and 89.9%, respectively, indicating that the catalytic activity of the molecular sieve remained essentially unchanged.
[0118] Example 8. Preparation of 3-acetamido-5-acetylfuran from chitin catalyzed by doped L-zeolite in different reactors
[0119] The doped L molecular sieve prepared in Example 11 was used in fixed bed, fluidized bed and moving bed, respectively, with other conditions the same as in Example 7. The reaction was run for 1 hour, and the results are shown in Table 2.
[0120] Table 2. Reaction results in different reactors
[0121] Reactor type Chitin conversion rate (%) 3-Acetamido-5-acetylfuran selectivity (%) Fixed bed 99.5 95.6 fluidized bed 99.8 96.5 mobile bed 99.7 95.7
[0122] As shown in Table 3, different reactor types can all achieve the L-zeolite catalytic conversion of chitin to prepare 3-acetamido-5-acetylfuran.
[0123] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.
Claims
1. A method for preparing 3-acetamido-5-acetylfuran using chitin, characterized in that, Includes the following steps: Chitin was dissolved in a eutectic solvent and reacted with L molecular sieves or doped L molecular sieves to obtain 3-acetamido-5-acetylfuran. The molar ratio of the L-zeolite is (0.9–5.0)M. 2 / n O:Al2O3:(2~50)SiO2; Where M is one or more of K, Na, Mg, Ca, Cr, Ce, Fe, Sn, B and Zr; n is the valence of M; The doped L-type molecular sieve is a molecular sieve doped with heteroatoms; The heteroatoms include one or more of Fe, Cr, Mg, Zr, Sn, Cu, Zn, Ni, Ce, and B.
2. The method for preparing 3-acetamido-5-acetylfuran using chitin according to claim 1, characterized in that, The doping amount of heteroatoms in the doped L molecular sieve is 0.1% to 10%.
3. The method for preparing 3-acetamido-5-acetylfuran using chitin according to claim 1, characterized in that, The chitin has a mass concentration of 0.1% to 15% in the eutectic solvent; The mass ratio of L molecular sieve to chitin is 1:500 to 20:1; The mass ratio of the doped L molecular sieve to chitin is 1:500 to 20:
1.
4. The method for preparing 3-acetamido-5-acetylfuran using chitin according to claim 3, characterized in that, The mass concentration of the chitin is 1% to 10%; The mass ratio of L molecular sieve to chitin is 1:100 to 10:1; The mass ratio of the doped L molecular sieve to chitin is 1:100 to 10:
1.
5. The method for preparing 3-acetamido-5-acetylfuran using chitin according to claim 1, characterized in that, The reaction temperature is 80℃ to 300℃; the reaction time is 10 minutes to 12 hours.
6. The method for preparing 3-acetamido-5-acetylfuran using chitin according to claim 5, characterized in that, The reaction temperature is 100℃~200℃; the reaction time is 10 minutes~8 hours.
7. The method for preparing 3-acetamido-5-acetylfuran using chitin according to claim 1, characterized in that, The eutectic solvent includes hydrogen bond acceptors and hydrogen bond donors; The hydrogen bond acceptor includes one or more of benzyltrimethylammonium chloride, choline chloride, and trimethylglycine; The hydrogen bond donor includes one or more of organic acids, low-carbon alcohols, and urea. The molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:(1-5); The organic acids mentioned include one or more of lactic acid, malic acid, citric acid, and oxalic acid; The lower alcohols include one or both of ethylene glycol and glycerol.
8. The method for preparing 3-acetamido-5-acetylfuran using chitin according to claim 1, characterized in that, The reaction is carried out in a reactor; The reactor includes one or more of the following: fixed-bed reactor, fluidized-bed reactor, and batch reactor.
9. A 3-acetamido-5-acetylfuran prepared by the preparation method according to any one of claims 1-8.