阅读说明：本技术 一种糠醛渣联产乙酰丙酸乙酯和乙酰丙酸的方法 (Method for co-producing ethyl levulinate and levulinic acid from furfural residues ) 是由 张素平 陈文兵 鄢博超 丁文彬 于 2021-07-06 设计创作，主要内容包括：本发明公开了一种糠醛渣联产乙酰丙酸乙酯和乙酰丙酸的方法,包括以下步骤：将液固比为(2～8):1的溶剂与糠醛渣混合,所述溶剂为乙醇与水的混合物,所述溶剂的含水量为0％～10％,加入硫酸作为B酸催化剂,所述硫酸在溶剂中的浓度为1％～5％,在温度为140～180℃的条件下,反应时间为90～165min,固液混合物过滤分离,使用气相色谱进行产物分析,获得乙酰丙酸乙酯和乙酰丙酸。本发明使用糠醛渣为原料,来源广泛；以硫酸作为B酸催化剂可联产乙酰丙酸乙酯和乙酰丙酸,提高产率和原料利用率。(The invention discloses a method for co-producing ethyl levulinate and levulinic acid from furfural residues, which comprises the following steps: mixing a solvent with a liquid-solid ratio of (2-8): 1 with furfural residues, wherein the solvent is a mixture of ethanol and water, the water content of the solvent is 0-10%, adding sulfuric acid as an acid B catalyst, the concentration of the sulfuric acid in the solvent is 1-5%, reacting for 90-165 min at the temperature of 140-180 ℃, filtering and separating the solid-liquid mixture, and analyzing products by using gas chromatography to obtain ethyl levulinate and levulinic acid. The invention uses furfural residue as raw material, and has wide source; the sulfuric acid is used as the acid B catalyst, and the ethyl levulinate and the levulinic acid can be co-produced, so that the yield and the utilization rate of raw materials are improved.)

1. A method for co-producing ethyl levulinate and levulinic acid from furfural residues is characterized by comprising the following steps:

mixing a solvent with a liquid-solid ratio of (2-8): 1 with furfural residues, wherein the solvent is a mixture of ethanol and water, the water content of the solvent is 0-10%, adding concentrated sulfuric acid as an acid B catalyst, the concentration of the concentrated sulfuric acid in the solvent is 1-5%, reacting for 90-165 min at the temperature of 140-180 ℃, filtering and separating the solid-liquid mixture, and analyzing products by using gas chromatography to obtain ethyl levulinate and levulinic acid.

2. The method for co-producing ethyl levulinate and levulinic acid from furfural residue as claimed in claim 1, wherein the particle size of the furfural residue is <0.4 mm.

3. The method for coproducing ethyl levulinate and levulinic acid from furfural residue as claimed in claim 1, wherein the furfural residue is dried in advance under the following conditions: drying for 1-4 h at 105-115 ℃.

4. The method for coproducing ethyl levulinate and levulinic acid from furfural residue as claimed in claim 1, wherein the liquid-solid ratio of the solvent to furfural residue is (4-8): 1.

5. The method for co-producing ethyl levulinate and levulinic acid from furfural residue as claimed in claim 1, wherein the water content of the solvent is 0%, 5%, 10%.

6. The method for co-producing ethyl levulinate and levulinic acid from furfural residue as claimed in claim 1, wherein the concentration of the concentrated sulfuric acid in the solvent is 1%, 3%, 5%.

7. The method for co-producing ethyl levulinate and levulinic acid from furfural residue as claimed in claim 1, wherein the temperature is preferably 160 ℃.

8. The method for coproducing ethyl levulinate and levulinic acid from furfural residue according to claim 1, wherein the reaction time is 90-150 min.

9. The method for co-producing ethyl levulinate and levulinic acid from furfural residue according to claim 1, wherein the yield of ethyl levulinate is 8-60% and the yield of levulinic acid is 7-18%.

Technical Field

The invention belongs to the technical field of biomass energy conversion, and particularly relates to a method for co-producing ethyl levulinate and levulinic acid from furfural residues.

Background

With the continuous development of current economy, the consumption of traditional fossil energy is increasing day by day, and people gradually look to renewable energy. Furfural is an important chemical raw material, and is produced mainly from biomass raw materials such as corncobs, corn straws and the like in China. The production of furfural is often accompanied with the generation of a large amount of furfural waste residues, and the stacking problem of the furfural waste residues also causes certain environmental pollution. Therefore, the upgrading and recycling of furfural residue resources are particularly important, and the furfural residue can be used for preparing various platform compounds, wherein ethyl levulinate and levulinic acid are important products.

Levulinic acid is one of the 12 most valuable platform compounds identified by the U.S. department of energy, has the property of reactive bifunctionality, and has wide potential in the aspect of synthesizing and producing various high-energy chemicals or products. In addition, levulinic acid is an important synthetic precursor for pharmaceutical, food flavor, polymer plastic, resin, textile, agrochemical, fuel, solvent and organic synthesis industries. Moreover, the esterification of levulinic acid under certain conditions can also obtain ethyl levulinate, which is one of the important ways for producing ethyl levulinate.

Ethyl levulinate, also known as ethyl pentosanoate or ethyl 4-ketovalerate, is a short-chain fatty ester in common levulinate, has strong polar bonds, so that the ethyl levulinate has good reaction activity, can perform hydrolysis, ester exchange, redox and other reactions, can be directly used as a food additive, a biological liquid fuel and the like, is a new energy chemical with great potential, and has wide industrial application value.

The furfural residue can be directly degraded in an ethanol reaction system under the action of an acid catalyst to generate levulinic acid and ethyl levulinate. At present, solid acid catalysts are rapidly emerging due to the advantages of easy separation and no corrosion, but reported solid acid catalysts often have the problems of easy inactivation, low yield and the like. Hederan et al (patent application with publication number CN 103360255A) discloses a method for producing ethyl levulinate by using furfural residue as a raw material and using molecular sieve solid acid and liquid acid as composite catalysts, wherein the yield is 16.10%. Penglin et al (patent application with publication number CN 107266312A) discloses a method for preparing ethyl levulinate by taking lignocellulose biomass as a raw material and utilizing a mixed acid system of aluminum trifluoromethanesulfonate and sulfuric acid as a synergistic catalyst to perform high-temperature high-pressure reaction in an ethanol solvent, wherein the theoretical molar yield reaches 64.90%. At present, research reports of co-producing levulinic acid and ethyl levulinate by using real biomass furfural residues as raw materials and reports of producing ethyl levulinate by alcoholysis with liquid acid as a catalyst under mild conditions are lacked.

Disclosure of Invention

The invention aims to provide a method for co-producing ethyl levulinate and levulinic acid from furfural residues.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the first aspect of the invention provides a method for co-producing ethyl levulinate and levulinic acid from furfural residues, which comprises the following steps:

mixing a solvent with a liquid-solid ratio of (2-8): 1 with furfural residues, wherein the solvent is a mixture of ethanol and water, the water content of the solvent is 0-10%, adding concentrated sulfuric acid as an acid B catalyst, the concentration of the concentrated sulfuric acid in the solvent is 1-5%, reacting for 90-165 min at the temperature of 140-180 ℃, filtering and separating the solid-liquid mixture, and analyzing products by using gas chromatography to obtain ethyl levulinate and levulinic acid.

The grain size of the furfural residue is less than 0.4 mm.

The furfural residues need to be dried in advance, and the drying conditions are as follows: drying for 1-4 h at 105-115 ℃.

The liquid-solid ratio of the solvent to the furfural residue is (4-8): 1, and more preferably 6:1, and the content of the solvent is increased, so that the reaction is completely carried out.

The water content of the solvent is 0%, 5% and 10%, and increasing the water content of the solvent is favorable for improving the yield of the levulinic acid but unfavorable for improving the ethyl levulinate and the total yield, and the water content is preferably 0% in view of the total yield.

The concentration of the concentrated sulfuric acid in the solvent is 1%, 3% and 5%, the concentration of the sulfuric acid in the solvent is increased to be beneficial to the complete alcohol (water) hydrolysis reaction, but the excessive sulfuric acid content can reduce the yield of the product.

The temperature is preferably 160 ℃, the alcohol (water) hydrolysis of the furfural residue is incomplete at low temperature, and the ethyl levulinate is mainly consumed by other side reactions when the temperature is too high, so that the ethyl levulinate and the total yield are reduced.

The reaction time is 90-150 min, preferably 120min, and proper extension of the reaction time is beneficial to complete reaction, but too long reaction time can increase the generated byproducts, and the required products are additionally consumed, so that the yield of the ethyl levulinate and the levulinic acid is reduced.

The yield of the ethyl levulinate is 8-60%, and the yield of the levulinic acid is 7-18%.

Due to the adoption of the technical scheme, the invention has the following advantages and beneficial effects:

the invention uses furfural residue as raw material, and has wide source; the sulfuric acid is used as the acid B catalyst, and the ethyl levulinate and the levulinic acid can be co-produced, so that the yield and the utilization rate of raw materials are improved. Compared with the prior art in which a mixed acid system of aluminum trifluoromethanesulfonate and sulfuric acid is used as a synergistic catalyst, the method has the advantages that the furfural residue is used as a raw material, so that the method is wide in source and has more practical significance; the invention has mild reaction conditions, and can react at normal pressure and lower temperature.

Detailed Description

In order to more clearly illustrate the invention, the invention is further described below in connection with preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.

The furfural residue raw material used in the embodiment of the invention is ground by a high-speed rotary cutting machine, and is sieved by a 40-mesh sieve to obtain a sample with required granularity, and the sample is dried for 2 hours at the temperature of 110 ℃. The grain size of the furfural residue is less than 0.4 mm.

The furfural residue is residue after furfural is produced by hydrolyzing biomass such as corncobs and the like, belongs to biomass waste, mainly comprises cellulose, lignin and a small amount of hemicellulose and ash, can be used as a raw material for producing levulinic acid and ethyl levulinate by hydrolyzing cellulose, and has good recycling value.

Levulinic acid and ethyl levulinate in the hydrolysate were analyzed by gas chromatography (Agilent 6820, column: DB-Innowax, 30 m.times.0.32 μm.times.0.5 m) using a hydrogen ion flame detector (FID) at a sample injection temperature of 280 ℃. The carrier gas is high-purity nitrogen, the flow rate is 1.5mL/min, and the temperature rise program of the column oven is as follows: maintaining at 120 deg.C for 3min, heating to 250 deg.C at 50 deg.C/min, and maintaining for 10 min.

Example 1

Mixing 15g of furfural residue with 90mL of absolute ethanol (the water content of the solvent is 0%), wherein the liquid-solid ratio is 6:1, adding 1160 mu L of concentrated sulfuric acid serving as an acid catalyst B, reacting for 120min at the temperature of 160 ℃ when the concentration of sulfuric acid serving as the acid catalyst B in a solvent is 3%, filtering and separating a solid-liquid mixture, and analyzing a product by using a gas chromatograph, wherein the yield of ethyl levulinate is 56.90%, the yield of levulinic acid is 10.00% and the total yield is 66.90%.

Example 2

Mixing 15g of furfural residue with 90mL of absolute ethanol (the water content of the solvent is 0%), wherein the liquid-solid ratio is 6: adding 390 mu L of concentrated sulfuric acid serving as an acid catalyst B, reacting the mixture for 120min at the temperature of 160 ℃ with the sulfuric acid serving as the acid catalyst B at the concentration of 1% in a solvent, filtering and separating a solid-liquid mixture, and analyzing a product by using a gas chromatograph, wherein the yield of the ethyl levulinate is 8.23%, the yield of the levulinic acid is 7.60% and the total yield is 15.83%.

Example 3

Mixing 15g of furfural residue with 90mL of absolute ethanol (the water content of the solvent is 0%), wherein the liquid-solid ratio is 6: 1930 mu L of concentrated sulfuric acid as an acid catalyst B is added, the concentration of sulfuric acid as the acid catalyst B in a solvent is 5%, the mixture is reacted for 120min at the temperature of 160 ℃, a solid-liquid mixture is filtered and separated, and product analysis is carried out by using a gas chromatograph, so that the yield of ethyl levulinate is 46.30%, the yield of levulinic acid is 8.10% and the total yield is 54.40%.

Example 4

Mixing 15g of furfural residue with 90mL of absolute ethanol (the water content of the solvent is 0%), wherein the liquid-solid ratio is 6:1, adding 1160 mu L of concentrated sulfuric acid serving as an acid catalyst B, reacting for 120min at the temperature of 180 ℃ with the concentration of 3% of sulfuric acid serving as the acid catalyst B, filtering and separating a solid-liquid mixture, and performing product analysis by using a gas chromatograph, wherein the yield of ethyl levulinate is 39.20%, the yield of levulinic acid is 13.76% and the total yield is 52.96%.

Example 5

Mixing 15g of furfural residue with 90mL of absolute ethanol (the water content of the solvent is 0%), wherein the liquid-solid ratio is 6:1, adding 1160 mu L of concentrated sulfuric acid serving as an acid catalyst B, reacting for 120min at 140 ℃ with the concentration of 3% of sulfuric acid serving as an acid catalyst B in a solvent, filtering and separating a solid-liquid mixture, and analyzing a product by using a gas chromatograph, wherein the yield of the ethyl levulinate is 11.10%, the yield of the levulinic acid is 13.37% and the total yield is 24.47%.

Example 6

Mixing 15g of furfural residue with 90mL of absolute ethanol (the water content of the solvent is 0%), wherein the liquid-solid ratio is 6:1, adding 1160 mu L of concentrated sulfuric acid serving as an acid catalyst B, reacting for 90min at the temperature of 160 ℃ with the concentration of 3% of sulfuric acid serving as the acid catalyst B in a solvent, filtering and separating a solid-liquid mixture, and performing product analysis by using a gas chromatograph to obtain the ethyl levulinate with the yield of 46.50%, the levulinic acid with the yield of 9.10% and the total yield of 55.60%.

Example 7

Mixing 15g of furfural residue with 90mL of absolute ethanol (the water content of the solvent is 0%), wherein the liquid-solid ratio is 6:1, adding 1160 mu L of concentrated sulfuric acid serving as an acid catalyst B, reacting for 150min at the temperature of 160 ℃ with the concentration of 3% of sulfuric acid serving as the acid catalyst B in a solvent, filtering and separating a solid-liquid mixture, and analyzing a product by using a gas chromatograph, wherein the yield of ethyl levulinate is 46.00%, the yield of levulinic acid is 18.00% and the total yield is 64.00%.

Example 8

Mixing 15g of furfural residue with 85.5mL of anhydrous ethanol and 4.5mL of H₂O, mixing, wherein the water content of the solvent is 5%, and the liquid-solid ratio is 6: adding 1170 mu L of concentrated sulfuric acid serving as an acid catalyst B, reacting the mixture for 120min at the temperature of 160 ℃ with sulfuric acid serving as an acid catalyst B at the concentration of 3% in a solvent, filtering and separating a solid-liquid mixture, performing product analysis by using a gas chromatography, and obtaining the ethyl levulinate with the yield of 53.40%,the yield of levulinic acid is 12.60 percent, and the total yield is 66.00 percent.

Example 9

Mixing 15g of furfural residue with 81mL of absolute ethyl alcohol and 9mL of H₂O, mixing, wherein the water content of the solvent is 10%, and the liquid-solid ratio is 6:1, adding 1190 mu L of concentrated sulfuric acid serving as an acid catalyst B, reacting the mixture at the temperature of 160 ℃ for 120min, filtering and separating a solid-liquid mixture, and analyzing a product by using a gas chromatograph, wherein the yield of the ethyl levulinate is 50.00 percent, the yield of the levulinic acid is 14.76 percent, and the total yield is 64.76 percent.

Example 10

Mixing 15g of furfural residues with 60mL of absolute ethanol, wherein the water content of a solvent is 0%, and the liquid-solid ratio is 4: adding 770 mu L of concentrated sulfuric acid serving as an acid catalyst B, reacting the acid catalyst B with sulfuric acid at a concentration of 3% in a solvent at 160 ℃ for 120min, filtering and separating a solid-liquid mixture, and analyzing a product by using a gas chromatograph, wherein the yield of ethyl levulinate is 43.70%, the yield of levulinic acid is 9.30% and the total yield is 53.00%.

Example 11

Mixing 15g of furfural residues with 120mL of absolute ethyl alcohol, wherein the water content of a solvent is 0%, and the liquid-solid ratio is 8: adding 1550 mu L of concentrated sulfuric acid serving as an acid catalyst B, reacting the solution with sulfuric acid serving as an acid catalyst B at a concentration of 3% in a solvent at 160 ℃ for 120min, filtering and separating a solid-liquid mixture, and performing product analysis by using a gas chromatograph to obtain the ethyl levulinate with the yield of 48.40%, the levulinic acid with the yield of 9.50% and the total yield of 57.90%.

According to the embodiment, the furfural residues are used as the raw materials, so that the source is wide; the sulfuric acid is used as the acid B catalyst, and the ethyl levulinate and the levulinic acid can be co-produced, so that the yield and the raw material utilization are improved.

Comparative example 1

In the prior method for preparing ethyl levulinate from furfural residues, the patent application with the publication number of CN 103360255A discloses the use of S₂O₈ ^2-/ZrO₂Reacting solid acid and concentrated hydrochloric acid (37%) at 210 deg.C for 3 hr, separating and purifying to obtain levulinic acidEthyl ester, yield 16.10%.

The present invention improves the yield of ethyl levulinate by nearly forty percent over comparative example 1.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.