Method for preparing alkyl levulinate by using molecular sieve to catalyze furfuryl alcohol

Abstract

The invention belongs to the technical field of catalytic chemistry and biomass conversion, and particularly relates to a method for preparing alkyl levulinate by catalyzing furfuryl alcohol through a molecular sieve. The method comprises the following steps: in an inert atmosphere, taking furfuryl alcohol as a raw material, taking an alcohol / water mixed solution as a solvent, adopting a specific catalyst, and carrying out alcoholysis reaction on furfuryl alcohol at a certain reaction temperature and reaction pressure to prepare alkyl levulinate by a one-pot method. The problems that in the prior art, a route for preparing alkyl levulinate from levulinic acid is high in cost and furfuryl alcohol conversion selectivity is low are solved, a high-activity and high-selectivity environment-friendly catalytic system is developed, the conversion rate of furfuryl alcohol in the whole reaction can reach 100%, the yield of alkyl levulinate can reach 85%, and the method is suitable for industrial production. And a very attractive technical route is provided for green, efficient and sustainable production of alkyl levulinate.

Description

Technical Field

[0001] This invention relates to a method for preparing alkyl levulinic acid esters from furfuryl alcohol using molecular sieve catalysis, belonging to the fields of catalytic chemistry and biomass conversion technology. Background Technology

[0002] Biomass is a strategically promising renewable resource, often considered an effective alternative to fossil fuels. Biomass-derived platform molecules are increasingly used in fuel and chemical synthesis, fully demonstrating their value. Among them, alkyl levulinate derived from biomass has become a highly sought-after chemical due to its multifunctional properties, recognized as a highly efficient fuel additive and a versatile fine chemical raw material, widely used in pharmaceutical preparations, cosmetic formulations, fragrance synthesis, and renewable polymer production. Leucylpropionic acid plays a crucial role as a precursor in the synthesis of alkyl levulinate; however, its practical application is significantly constrained. Its high production cost stems primarily from its dependence on inorganic acids and complex separation and purification processes, a deficiency that severely limits its large-scale industrial application. To address these challenges, current technology shifts towards utilizing furfuryl alcohol, a biomass-derived platform molecule, to synthesize alkyl levulinate through its alcoholysis reaction. This route adheres to the principles of green chemistry and sustainability while striving to improve economic feasibility. Traditional alcoholysis processes primarily use liquid and solid acids as catalysts. While liquid acids offer high catalytic efficiency, they suffer from drawbacks such as strong corrosiveness to equipment, difficulty in recycling, and severe environmental pollution, failing to meet the requirements of green chemistry development. Existing solid acid catalysts for the catalytic hydrolysis of furfuryl alcohol to produce alkyl levulinate also face challenges related to demanding reaction conditions and complex catalyst preparation. For example, Chinese patent document CN110963914A discloses a method for preparing alkyl levulinate using an acidic catalyst by controlling the water content. This method achieves a 95% yield of alkyl levulinate with the addition of a third-group azeotropic agent to adjust the moisture content, but the addition of the azeotropic agent increases the cost of product separation. In conclusion, achieving the hydrogenolysis of furfuryl alcohol to produce alkyl levulinate under mild conditions is crucial for improving the product's market competitiveness. Summary of the Invention

[0003] This invention addresses the challenges of low raw material utilization, harsh reaction conditions, insufficient economic efficiency, and complex catalyst preparation by proposing an innovative catalytic method: a one-pot, highly selective alcoholysis to alkyl levulinate using existing molecular sieve catalysts in an alcohol / water mixed solution under an inert atmosphere. This method enables the hydrogenolysis of furfuryl alcohol to produce alkyl levulinate under mild conditions, providing a novel solution for the efficient and green synthesis of alkyl levulinate. To achieve the above objectives, the technical solution adopted by this invention is as follows: A method for preparing alkyl levulinic acid esters from furfuryl alcohol via molecular sieve catalysis includes the following steps: In an inert atmosphere, furfuryl alcohol is used as a raw material, an alcohol / water mixed solution is used as a solvent, and a specific catalyst is employed to carry out the alcoholysis reaction of furfuryl alcohol under certain reaction temperature and pressure to prepare alkyl levulinic acid esters in a one-pot process.

[0004] Furthermore, the alcohol in the alcohol / water mixed solution is an alkyl alcohol solvent, including but not limited to one or more alcohol compounds such as methanol, ethanol, propanol, butanol, ethylene glycol, and propylene glycol.

[0005] Preferably, the volume ratio of alcohol to water in the alcohol / water mixed solution is 10:1.

[0006] Furthermore, the inert atmosphere includes, but is not limited to, one or more of the following atmospheres: nitrogen, argon, helium, carbon dioxide, etc.

[0007] Furthermore, the reaction temperature is 50-300 ℃; the reaction pressure is 0.1-10 MPa.

[0008] Furthermore, the reaction time is 0.5-10 hours.

[0009] Furthermore, in the reaction, the volume ratio of furfuryl alcohol to alcohol in the alcohol / water mixed solution is between 1:2 and 50.

[0010] Furthermore, the catalyst belongs to the category of molecular sieve catalysts, and the catalyst may be selected from one or more of the following: Hβ molecular sieve, ZSM-5 molecular sieve, Y-type molecular sieve, A-type molecular sieve, mordenite, SAPO-34 molecular sieve, MCM-22 molecular sieve, and SBA-15 molecular sieve.

[0011] Furthermore, the silicon-aluminum molar ratio of the catalyst is between 0 and 100.

[0012] Preferably, the silicon-aluminum molar ratio of the catalyst is between 28 and 100.

[0013] More preferably, the silicon-aluminum molar ratio of the catalyst is between 44 and 100.

[0014] The beneficial effects of this invention are as follows: This invention utilizes a molecular sieve catalyst to successfully achieve the alcoholysis of furfuryl alcohol to prepare alkyl levulinate under conditions of an alcohol / water mixed solution and an inert atmosphere. It overcomes several shortcomings of existing preparation techniques, such as harsh reaction conditions, complex catalyst preparation processes, and environmental pollution caused by traditional methods. This method catalyzes the alcoholysis of furfuryl alcohol to produce alkyl levulinate in a one-pot process. The operation is simple, highly efficient, and environmentally friendly, suitable for large-scale production, and the yield of alkyl levulinate can reach over 85% in 1 hour. Detailed Implementation

[0015] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0016] Unless otherwise specified, the raw materials, reagents or devices used in the following embodiments can be obtained from conventional commercial sources or by existing known methods; unless otherwise specified, the methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0017] The following describes the preparation of alkyl levulinic acid esters from furfuryl alcohol using furfuryl alcohol as the reactant and alkyl alcohol as the solvent, with molecular sieves ZSM-5, Hβ, USY, and MCM-22 (purchased from Nankai University Catalyst Co., Ltd.) as catalysts. The scope of protection of this patent is not limited to the specific embodiments, but is limited by the claims.

[0018] Example 1

[0019] Weigh 250 mg of ZSM-5 catalyst (silicon-aluminum molar ratio 44), 12 mmol of furfuryl alcohol, 10 mL of anhydrous methanol, and 1 mL of ultrapure water, and add them sequentially to the lining of a 25 mL reaction vessel, mixing thoroughly. After sealing the reaction vessel, first purge with nitrogen for 10 min to replace the air inside the vessel, then adjust the nitrogen pressure to 1 MPa. Place the reaction vessel in a heating mantle and heat to 160 °C, starting the timer. After 1 h of reaction, gas chromatography analysis showed that the conversion rate of furfuryl alcohol was 100%, the selectivity of the target product methyl levulinate was 80.5%, and the structural formula of methyl levulinate is [insert structural formula here]. .

[0020] Example 2

[0021] Weigh 250 mg of ZSM-5 catalyst (silicon-aluminum molar ratio 40), 12 mmol of furfuryl alcohol, 10 mL of anhydrous methanol, and 1 mL of ultrapure water, and add them sequentially to the lining of a 25 mL reactor, mixing thoroughly. After sealing the reactor, purge with nitrogen for 10 min to replace the air inside, then adjust the nitrogen pressure to 1 MPa. Place the reactor in a heating mantle and heat to 160 °C, starting the timer. After 2 h of reaction, gas chromatography analysis showed that the conversion rate of furfuryl alcohol was 100%, and the selectivity for the target product, methyl levulinate, was 44.0%.

[0022] Example 3

[0023] Weigh 250 mg of Hβ molecular sieve catalyst with a silica-alumina molar ratio of 28, 12 mmol of furfuryl alcohol, 10 mL of anhydrous methanol, and 1 mL of ultrapure water, and add them sequentially to the lining of a 25 mL reaction vessel, mixing thoroughly. After sealing the reaction vessel, first purge with nitrogen for 10 min to replace the air inside the reaction vessel, then adjust the nitrogen pressure to 2 MPa. Place the reaction vessel in a heating mantle and heat to 160 °C, starting the timer. After 1 h of reaction, gas chromatography analysis showed that the conversion rate of furfuryl alcohol was 100%, and the selectivity for the target product, methyl levulinate, was 32.3%.

[0024] Example 4

[0025] Weigh 250 mg of USY molecular sieve catalyst (silicon-aluminum molar ratio 7), 12 mmol of furfuryl alcohol, 10 mL of anhydrous ethanol, and 1 mL of ultrapure water, and add them sequentially to the lining of a 25 mL reaction vessel, mixing thoroughly. After sealing the reaction vessel, purge with nitrogen for 10 min to replace the air inside, then adjust the nitrogen pressure to 1 MPa. Place the reaction vessel in a heating mantle and heat to 160 °C, starting the timer. After 1 h of reaction, gas chromatography analysis showed that the conversion rate of furfuryl alcohol was 100%, and the selectivity for the target product, ethyl levulinate, was 32.1%.

[0026] Example 5

[0027] Weigh 250 mg of pure silica molecular sieve MCM-22 catalyst, 12 mmol of furfuryl alcohol, 10 mL of anhydrous methanol, and 1 mL of ultrapure water, and add them sequentially to the lining of a 25 mL reaction vessel, mixing thoroughly. After sealing the reaction vessel, first purge with nitrogen for 10 min to replace the air inside the vessel, then adjust the nitrogen pressure to 1 MPa. Place the reaction vessel in a heating mantle and heat to 200 °C, starting the timer. After 1 h of reaction, gas chromatography analysis showed that the conversion rate of furfuryl alcohol was 100%, and the selectivity for the target product methyl levulinate was 67.5%.

[0028] Example 6

[0029] Weigh 250 mg of ZSM-5 catalyst (silicon-aluminum molar ratio 40), 12 mmol of furfuryl alcohol, 10 mL of anhydrous methanol, and 1 mL of ultrapure water, and add them sequentially to the lining of a 25 mL reaction vessel, mixing thoroughly. After sealing the reaction vessel, first purge with nitrogen for 10 min to replace the air inside the vessel, then adjust the nitrogen pressure to 1 MPa. Place the reaction vessel in a heating mantle and heat to 160 °C, starting the timer. After 1 h of reaction, gas chromatography analysis showed that the conversion rate of furfuryl alcohol was 100%, and the selectivity for the target product, methyl levulinate, was 56%.

[0030] Example 7

[0031] Weigh 250 mg of Hβ molecular sieve catalyst with a silica-alumina molar ratio of 28, 12 mmol of furfuryl alcohol, 10 mL of anhydrous methanol, and 1 mL of ultrapure water, and add them sequentially to the lining of a 25 mL reaction vessel, mixing thoroughly. After sealing the reaction vessel, first purge with nitrogen for 10 min to replace the air inside the reaction vessel, then adjust the nitrogen pressure to 1 MPa. Place the reaction vessel in a heating mantle and heat to 160 °C, starting the timer. After 1 h of reaction, gas chromatography analysis showed that the conversion rate of furfuryl alcohol was 100%, and the selectivity for the target product methyl levulinate was 23.8%.

[0032] Example 8

[0033] Example 8 differs from Example 1 in that the solvent was changed to anhydrous ethanol, while all other operations were the same as in Example 1. Gas chromatography analysis showed that the conversion rate of furfuryl alcohol was 100%, and the selectivity for the target product, ethyl levulinate, was 82%.

[0034] Example 9

[0035] Example 9 differs from Example 1 in that the catalyst was changed to ZSM-5 catalyst with a silicon-to-aluminum ratio of 70; all other operations were the same as in Example 1. Gas chromatography analysis showed that the conversion rate of furfuryl alcohol was 100%, and the selectivity for the target product, methyl levulinate, was 86%.

[0036] Example 10

[0037] Example 10 differs from Example 1 in that the reaction time is changed to 25 min, while other operations are the same as in Example 1. Gas chromatography analysis showed that the conversion rate of furfuryl alcohol was 85%, and the selectivity for the target product, methyl levulinate, was 63%.

[0038] Example 11

[0039] Example 11 differs from Example 1 in that the reaction temperature is changed to 80 °C, while other operations are the same as in Example 1. Gas chromatography analysis showed that the conversion rate of furfuryl alcohol was 43%, and the selectivity for the target product, methyl levulinate, was 25%.

[0040] Example 12

[0041] Example 12 differs from Example 1 in that the molecular sieve used for the catalyst is changed to ZSM-5 with a silica-to-alumina ratio of 30; all other operations are the same as in Example 1. Gas chromatography analysis showed that the conversion rate of furfuryl alcohol was 100%, and the selectivity for the target product methyl levulinate was 41.4%.

[0042] Example 13

[0043] Example 13 differs from Example 12 in that the nitrogen pressure in the reaction is changed to 0 MPa, while other operations are the same as in Example 12. Gas chromatography analysis showed that the conversion rate of furfuryl alcohol was 100%, and the selectivity for the target product methyl levulinate was 40.9%.

[0044] Example 14

[0045] Weigh 250 mg of ZSM-5 catalyst (silicon-aluminum molar ratio 30), 12 mmol of furfuryl alcohol, and 10 mL of anhydrous methanol, and add them sequentially to the lining of a 25 mL reaction vessel, mixing thoroughly. After sealing the reaction vessel, purge with nitrogen for 10 min to replace the air inside, then adjust the nitrogen pressure to 1 MPa. Place the reaction vessel in a heating mantle and heat to 160 °C, starting the timer. After 1 h of reaction, gas chromatography analysis showed that the conversion rate of furfuryl alcohol was 100%, and the selectivity for the target product, methyl levulinate, was 38.6%.

[0046] Example 15

[0047] Example 15 differs from Example 1 in that the amount of water added in the reaction is changed to 2 mL, while other operations are the same as in Example 1. Gas chromatography analysis showed that the conversion rate of furfuryl alcohol was 100%, and the selectivity of the target product methyl levulinate was 85%.

[0048] Example 16

[0049] Weigh 250 mg of Hβ molecular sieve catalyst with a silica-alumina molar ratio of 28, 12 mmol of furfuryl alcohol, 10 mL of anhydrous methanol, and 1.5 mL of ultrapure water, and add them sequentially to the lining of a 25 mL reaction vessel, mixing thoroughly. After sealing the reaction vessel, first purge with nitrogen for 10 min to replace the air inside the reaction vessel, then adjust the nitrogen pressure to 1 MPa. Place the reaction vessel in a heating mantle and heat to 160 °C, starting the timer. After 1 h of reaction, gas chromatography analysis showed that the conversion rate of furfuryl alcohol was 100%, and the selectivity for the target product, methyl levulinate, was 28%.

[0050] Example 17

[0051] Example 17 differs from Example 1 in that the amount of water added in the reaction is changed to 1.5 mL, while other operations are the same as in Example 1. Gas chromatography analysis showed that the conversion rate of furfuryl alcohol was 100%, and the selectivity of the target product methyl levulinate was 83%.

[0052] Table 1: Furfuryl alcohol conversion and alkyl levulinate selectivity

[0053] It should be noted that the above description is only a part of the embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing alkyl levulinic acid esters from furfuryl alcohol using molecular sieve catalysis, characterized in that, The method includes the following steps: in an inert atmosphere, furfuryl alcohol is added to an alcohol / water mixture, and a molecular sieve catalyst is used to react the mixture for a certain time at a certain temperature and pressure to prepare alkyl levulinic acid compounds in a one-pot process.

2. The method for preparing alkyl levulinic acid esters from furfuryl alcohol using molecular sieve catalysis as described in claim 1, characterized in that, The alcohol in the alcohol / water mixture is an alkyl alcohol solvent; the alkyl alcohol is selected from one or more of methanol, ethanol, propanol, butanol, ethylene glycol, and propylene glycol, including but not limited to.

3. The method for preparing alkyl levulinic acid esters from furfuryl alcohol using molecular sieve catalysis as described in claim 1, characterized in that, The volume ratio of alcohol to water in the alcohol / water mixed solution is 10:

1.

4. The method for preparing alkyl levulinic acid esters from furfuryl alcohol using molecular sieve catalysis as described in claim 1, characterized in that, The silicon-aluminum molar ratio in the molecular sieve catalyst is between 0 and 100.

5. The method for preparing alkyl levulinic acid esters from furfuryl alcohol using molecular sieve catalysis as described in claim 1, characterized in that, The molecular sieve catalyst includes one or more of the following: Hβ molecular sieve, ZSM-5 molecular sieve, Y-type molecular sieve, A-type molecular sieve, mordenite, SAPO-34 molecular sieve, MCM-41 molecular sieve, and SBA-15 molecular sieve.

6. The method for preparing alkyl levulinic acid esters from furfuryl alcohol using molecular sieve catalysis as described in claim 1, characterized in that, The reaction temperature is 50-300 ℃.

7. The method for preparing alkyl levulinic acid esters from furfuryl alcohol using molecular sieve catalysis as described in claim 1, characterized in that, The pressure is 0.1-10 MPa.

8. The method for preparing alkyl levulinic acid esters from furfuryl alcohol using molecular sieve catalysis as described in claim 1, characterized in that, The time is 0.5-10 hours.

9. The method for preparing alkyl levulinic acid esters from furfuryl alcohol using molecular sieve catalysis as described in claim 1, characterized in that, The required inert atmosphere includes one or more of nitrogen, argon, helium, and carbon dioxide.

10. The method for preparing alkyl levulinic acid esters from furfuryl alcohol via molecular sieve catalysis as described in claim 1, characterized in that, In the reaction, the volume ratio of furfuryl alcohol to alcohol in the alcohol / water mixed solution is between 1:2 and 50.

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