Method for preparing ethyl levulinate by microwave-assisted two-phase solvent system

Abstract

The invention discloses a method for preparing ethyl levulinate through a microwave-assisted two-phase solvent system, and belongs to the technical field of ethyl levulinate preparation. The method comprises the following steps: putting a biomass raw material into a two-phase solvent system, and preparing ethyl levulinate by using a microwave-assisted catalyst, the catalyst is any one of Ti (SO4) 2 or a mixture of Ti (SO4) 2 and H2SO4; the solvent is a mixture of ethanol and gamma-valerolactone. Titanium sulfate is selected as a catalyst and is used for converting a biomass raw material solvent and successfully synthesizing ethyl levulinate. The esterification reaction path is not recorded in literatures so far, and the unique application potential of titanium sulfate in the field is shown.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ethyl levulinate preparation, and particularly relates to a method for preparing ethyl levulinate by using a microwave-assisted two-phase solvent system. BACKGROUND

[0002] Cellulose is the most abundant natural organic compound in nature. Among platform compounds prepared from cellulose, ethyl levulinate has great potential value, and relevant research has significantly increased in popularity. At present, there are three paths for preparing ethyl levulinate from cellulose: ① biomass direct alcoholysis, ② levulinic acid esterification, and ③ 5-chloromethylfurfural alcoholysis. Among them, the levulinic acid esterification method has the disadvantages of corroding equipment, being difficult to recycle and use, and high production cost; the 5-chloromethylfurfural alcoholysis method has a long reaction time, which is not conducive to industrial production, and both of the two processes rely on high-concentration liquid acid, which does not conform to the concept of green chemistry. Compared with the first two methods, the cellulose direct alcoholysis method for synthesizing ethyl levulinate has significant advantages: the process is more simple, the reaction period is greatly shortened, and all reaction steps can be continuously completed in a single reactor. This integrated production mode makes the cellulose direct alcoholysis method for preparing ethyl levulinate a more valuable research and application potential technology route.

[0003] The research focus on the preparation of ethyl levulinate from cellulose conversion is concentrated on the optimization of the catalytic system, mainly including three categories: solid acid catalytic materials, inorganic acid catalytic system and ionic liquid catalytic medium. However, to realize the efficient conversion of cellulose to target products, relatively harsh reaction conditions are often required, such as higher reaction temperature (200-220 ℃), longer reaction time (12-24 hours) or increased catalyst dosage. It is found that simply relying on the optimization of catalyst and reaction conditions has limited effect on the regulation of the conversion process, and it is difficult to break through the bottleneck of chemical conversion efficiency.

[0004] At present, there are still some problems in the preparation of ethyl levulinate, such as low conversion efficiency and target product selectivity in a single solvent system; complex preparation process, long time consumption and high cost; limited scale industrial application; selection of high-efficiency, multifunctional, environmentally friendly and economical catalysts, etc. SUMMARY

[0005] One of the technical problems solved by the present application is to provide a method for preparing ethyl levulinate by using a microwave-assisted two-phase solvent system, which selects titanium sulfate as a catalyst for biomass raw material solvent conversion and successfully synthesizes ethyl levulinate. This esterification reaction path has not been reported in the literature so far, and it shows the unique application potential of titanium sulfate in this field.

[0006] Technical scheme: In order to solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0007] A method for preparing ethyl levulinate by microwave-assisted two-phase solvent system, biomass raw material is placed in a two-phase solvent system, and ethyl levulinate is prepared by using microwave-assisted catalyst; the catalyst is any one of Ti(SO4)2 or a mixture of Ti(SO4)2 and H2SO4; the solvent is a mixture of ethanol and gamma-valerolactone.

[0008] The method for preparing ethyl levulinate by microwave-assisted two-phase solvent system, the reaction temperature is 160-190 DEG C, and the reaction time is 1-6 h; preferably, 160-170 DEG C is reacted for 3-5 h; further preferably, 170 DEG C is reacted for 3-4 h; more preferably, 170 DEG C is reacted for 3 h.

[0009] The method for preparing ethyl levulinate by microwave-assisted two-phase solvent system, the biomass raw material is any one of cellulose, poplar, Chinese fir, sugarcane residue, bamboo, wheat straw or corn straw; the amount of the catalyst is 15%-25% of the mass of the raw material, preferably 20%; further preferably, the raw material is 2.0 g, and the amount of the catalyst is 0.4 g.

[0010] The method for preparing ethyl levulinate by microwave-assisted two-phase solvent system, the catalyst is a mixture of Ti(SO4)2 and H2SO4, the mass ratio of Ti(SO4)2 to H2SO4 is 1:1, and the mass concentration of H2SO4 is 72%; further preferably, the raw material is 2.0 g, the amount of Ti(SO4)2 is 0.2 g, and the amount of H2SO4 with a mass concentration of 72% is 0.2 g.

[0011] The method for preparing ethyl levulinate by microwave-assisted two-phase solvent system, the mass ratio of ethanol to gamma-valerolactone is 3:1-5:1; preferably, the mass ratio is 4:1; further preferably, the mass of ethanol is 16 g, and the mass of gamma-valerolactone is 4 g.

[0012] The method for preparing ethyl levulinate by the microwave-assisted two-phase solvent system adopts gradient heating mode, and the specific heating mode is as follows: the first temperature section is room temperature~100 ℃, the heating rate is 18~22 ℃ / min, and the temperature is kept for 1~3 min; the second temperature section is 100~120 ℃, the heating rate is 18~22 ℃ / min, and the temperature is kept for 1~3 min; the third temperature section is 120 ℃~set temperature, the heating rate is 18~22 ℃ / min, the temperature of 160~190 ℃ is reached to start timing, and the temperature is kept for 1~6 h at the temperature, and the maximum output power of each section is set to 300 W; preferably, the first temperature section is room temperature~100 ℃, the heating rate is 20 ℃ / min, the temperature is kept for 2 min; the second temperature section is 100~120 ℃, the heating rate is 20 ℃ / min, the temperature is kept for 2 min; the third temperature section is 120~set temperature, the heating rate is 20 ℃ / min, the temperature of 160~170 ℃ is reached to start timing, and the temperature is kept for 3~4 h at the temperature, and the maximum output power of each section is set to 300 W; further preferably, the set temperature is 170 ℃, and the temperature is kept for 3~4 h; still further preferably, the set temperature is 170 ℃, and the temperature is kept for 3 h.

[0013] The method for preparing ethyl levulinate by the microwave-assisted two-phase solvent system comprises the following steps:

[0014] (1) The cellulose is taken into a microwave reaction kettle, Ti(SO4)2, H2SO4, ethanol and γ-valerolactone are added, the reaction kettle is closed, the stirrer is started, and the reaction is carried out at a rotation speed of 400 r / min;

[0015] (2) During the reaction, the microwave reactor is controlled by a microcomputer to realize gradient rising of the reaction temperature, the first temperature section is room temperature~100 ℃, the heating rate is 20 ℃ / min, the temperature is kept for 2 min; the second temperature section is 100~120 ℃, the heating rate is 20 ℃ / min, the temperature is kept for 2 min; the third temperature section is 120 ℃~set temperature, the heating rate is 20 ℃ / min, the temperature is reached to start timing, and the temperature is kept at the temperature, and the maximum output power of each section is set to 300 W;

[0016] (3) After the reaction is completed, the temperature in the kettle is cooled to room temperature, the reaction kettle is opened, the reaction liquid is poured out and weighed, and the filter residue and the filtrate containing ethyl levulinate are obtained by filtration.

[0017] The method for preparing ethyl levulinate by the microwave-assisted two-phase solvent system, the catalyst is a mixture of Ti(SO4)2 and H2SO4, the amount is 20% of the mass of cellulose, the mass ratio of Ti(SO4)2 to H2SO4 is 1:1, the mass concentration of H2SO4 is 72%, and the mass ratio of ethanol to gamma-valerolactone is 4:1.

[0018] The method for preparing ethyl levulinate by the microwave-assisted two-phase solvent system, the setting temperature is 160-170 DEG C, and the time is kept at the temperature for 3-4 h.

[0019] The method for preparing ethyl levulinate by the microwave-assisted two-phase solvent system, the amount of cellulose is 2.0 g, the amount of Ti(SO4)2 is 0.2 g, the amount of H2SO4 with a mass concentration of 72% is 0.2 g, the mass of ethanol is 16 g, the mass of gamma-valerolactone is 4 g, the setting temperature is 170 DEG C, and the time is kept at the temperature for 3 h.

[0020] Beneficial effects: compared with the prior art, the present application has the following advantages:

[0021] The present application selects titanium sulfate as a catalyst, which is used for solvent conversion of biomass raw materials and successfully synthesizes ethyl levulinate. The esterification reaction path has not been reported in the literature so far, and the unique application potential of titanium sulfate in this field is exhibited.

[0022] The present application uses a mixture of titanium sulfate and sulfuric acid as a catalyst, which has better effect than single titanium sulfate catalysis, the test results show that the EL yield is 41.24% and the cellulose conversion rate is 72.00% when kept at 170 DEG C for 3 h. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The process flow chart of the present application is shown in the figure;

[0024] Figure 2 The gas chromatogram of ethyl levulinate obtained by testing group No. 3 in Example 1 is shown in the figure. DETAILED DESCRIPTION

[0025] The present application will be further illustrated in combination with specific examples, the examples are implemented on the premise of the technical scheme of the present application, and it should be understood that the examples are only used for illustrating the present application and are not used for limiting the scope of the present application.

[0026] The yield of ethyl levulinate (EL) and the conversion rate of cellulose are calculated, and the calculation formula is as follows:

[0027] ;

[0028] .

[0029] Example 1

[0030] A method for preparing ethyl levulinate by microwave-assisted two-phase solvent system, the process flow chart is shown as Figure 1 The method comprises the following steps:

[0031] (1) 2.0 g of cellulose is placed in a microwave reactor, 0.4 g of Ti(SO4)2 and 16 g of ethanol, 4 g of γ-valerolactone are added, the reactor is closed, the stirrer is started, and the rotation speed is maintained at 400 r / min for reaction;

[0032] (2) During the reaction, the microwave reactor is controlled by a microcomputer to realize the gradient rise of the reaction temperature. The first temperature section is room temperature~100 ℃, the heating rate is 20 ℃ / min, and the temperature is maintained for 2 min; the second temperature section is 100~120 ℃, the heating rate is 20 ℃ / min, and the temperature is maintained for 2 min; the third temperature section is 120~170 ℃, the heating rate is 20 ℃ / min, the set temperature 170 ℃ is reached, and the time is started to be counted, the temperature is maintained for 1 h, 2 h, and 3 h, and the maximum output power is set to 300 W for each section;

[0033] (3) After the reaction is completed, the temperature in the reactor is cooled to room temperature, the reactor is opened, the reaction liquid is poured out and weighed, and the filtrate and the residue are obtained by filtration. The residue is washed with ethanol, dried at 100 ℃ to a constant weight, and the conversion rate is calculated; a small amount of the filtrate is filtered through a 0.45 μm filter membrane, and GC detection is performed to calculate the yield of ethyl levulinate and the conversion rate of cellulose. The results are shown in Table 1 (the pressure value in Table 1 is the instrument reading data under different reaction conditions).

[0034] Table 1 Test results of different reaction times in Example 1

[0035]

[0036] Example 2

[0037] A method for preparing ethyl levulinate by microwave-assisted two-phase solvent system, comprising the following steps:

[0038] (1) 2.0 g of cellulose is placed in a microwave reactor, 0.2 g of Ti(SO4)2, 0.2 g of 72% H2SO4, and 16 g of ethanol, 4 g of γ-valerolactone are added, the reactor is closed, the stirrer is started, and the rotation speed is maintained at 400 r / min for reaction;

[0039] (2) During the reaction, the microwave reactor is controlled by a microcomputer to realize the gradient rise of the reaction temperature. The first temperature section is room temperature ~ 100 ℃, the heating rate is 20 ℃ / min, and the temperature is maintained for 2 min; the second temperature section is 100 ~ 120 ℃, the heating rate is 20 ℃ / min, and the temperature is maintained for 2 min; the third temperature section is 120 ~ 170 ℃, the heating rate is 20 ℃ / min, the set temperature 170 ℃ is reached to start timing, and the temperature is maintained for 1 h, 2 h, 3 h at the temperature, and the maximum output power of each section is set to 300 W;

[0040] (3) After the reaction is completed, the temperature in the kettle is cooled to room temperature, the reaction kettle is opened, the reaction liquid is poured out and weighed, and the filtrate and the residue are obtained by filtration. The residue is washed with ethanol, dried at 100 ℃ to constant weight, and the conversion rate is calculated; a small amount of filtrate is filtered through a 0.45 μm filter membrane, and GC detection is performed to calculate the yield of ethyl levulinate and the conversion rate of cellulose. The results are shown in Table 2.

[0041] Table 2 Test results of different reaction times in Example 2

[0042]

[0043] As can be seen from Tables 1 and 2, the catalytic effect of the mixed acid system (L acid + B acid) is greatly improved compared with Ti(SO4)2 alone.

[0044] Example 3

[0045] A method for preparing ethyl levulinate by microwave-assisted two-phase solvent system, comprising the following steps:

[0046] (1) 2.0 g of cellulose is placed in a microwave reaction kettle, 0.2 g of Ti(SO4)2, 0.2 g of 72% mass concentration H2SO4 and 16 g of ethanol, and 4 g of γ-valerolactone are added, the reaction kettle is closed, the stirrer is started, and the reaction is carried out at a rotation speed of 400 r / min;

[0047] (2) During the reaction, the microwave reactor is controlled by a microcomputer to realize the gradient rise of the reaction temperature. The first temperature section is room temperature ~ 100 ℃, the heating rate is 20 ℃ / min, and the temperature is maintained for 2 min; the second temperature section is 100 ~ 120 ℃, the heating rate is 20 ℃ / min, and the temperature is maintained for 2 min; the third temperature section is 120 ~ 160 ℃, the heating rate is 20 ℃ / min, the set temperature 160 ℃ is reached to start timing, and the temperature is maintained for 3 h, 4 h, 5 h at the temperature, and the maximum output power of each section is set to 300 W;

[0048] (3) After the reaction is completed, the temperature in the kettle is cooled to room temperature, the reaction kettle is opened, the reaction liquid is poured out and weighed, and the filtrate and residue are obtained by filtration. The residue is washed with ethanol, dried at 100°C to constant weight, and the conversion rate is calculated; a small amount of filtrate is filtered through a 0.45 μm filter membrane, and GC detection is performed, and the yield of ethyl acetylpromate and the conversion rate of cellulose are calculated.

[0049] Table 3 Test results of different reaction times in Example 3

[0050]

[0051] Example 4

[0052] A method for preparing ethyl acetylpromate by microwave-assisted two-phase solvent system, comprising the following steps:

[0053] (1) 2.0 g of cellulose is placed in a microwave reaction kettle, 0.2 g of Ti(SO4)2, 0.2 g of 72% mass concentration H2SO4 and 16 g of ethanol, and 4 g of γ-valerolactone are added, the reaction kettle is closed, the stirrer is started, and the rotation speed is maintained at 400 r / min for reaction;

[0054] (2) During the reaction, the microwave reactor is controlled by a microcomputer to realize gradient rising of the reaction temperature, the first temperature section is room temperature~100 ℃, the heating rate is 20 ℃ / min, and the temperature is maintained for 2 min; the second temperature section is 100~120 ℃, the heating rate is 20 ℃ / min, and the temperature is maintained for 2 min; the third temperature section is 120~170 ℃, the heating rate is 20 ℃ / min, the set temperature 170 ℃ is reached, and the timing is started, and the temperature is maintained at 170 ℃ for 4 h, the maximum output power is set to 300 W for each section, and the reaction pressure is 2.1 MPa;

[0055] (3) After the reaction is completed, the temperature in the kettle is cooled to room temperature, the reaction kettle is opened, the reaction liquid is poured out and weighed, and the filtrate and residue are obtained by filtration. The residue is washed with ethanol, dried at 100°C to constant weight, and the conversion rate is calculated; a small amount of filtrate is filtered through a 0.45 μm filter membrane, and GC detection is performed, and the yield of ethyl acetylpromate and the conversion rate of cellulose are calculated.

[0056] Example 5

[0057] A method for preparing ethyl acetylpromate by microwave-assisted two-phase solvent system, comprising the following steps:

[0058] (1) Take 2.0 g of cellulose and place it in a microwave reactor, add 0.2 g of Ti(SO4)2, 0.2 g of H2SO4 with a mass concentration of 72%, 16 g of ethanol, and 4 g of γ-valerolactone, close the reactor, start the stirrer, and maintain the rotation speed at 400 r / min for the reaction;

[0059] (2) During the reaction, the microwave reactor is controlled by a microcomputer to realize gradient rising of the reaction temperature. The first temperature section is room temperature~100 ℃, the heating rate is 20 ℃ / min, and the temperature is maintained for 2 min. The second temperature section is 100~120 ℃, the heating rate is 20 ℃ / min, and the temperature is maintained for 2 min. The third temperature section is 120~180 ℃, the heating rate is 20 ℃ / min, the set temperature 180 ℃ is reached, and the timing is started, and the temperature is maintained at 180 ℃ for 60 min. The maximum output power is set to 300 W for each section, and the reaction pressure is 2.3 MPa;

[0060] (3) After the reaction is completed, the temperature in the reactor is cooled to room temperature, the reactor is opened, the reaction liquid is poured out and weighed, and the filtrate and residue are obtained by filtration. The residue is washed with ethanol, dried at 100 ℃ to a constant weight, and the conversion rate is calculated. A small amount of filtrate is filtered through a 0.45 μm filter membrane, and GC detection is performed to calculate the yield of ethyl levulinate 31.48% and the conversion rate of cellulose 81.60%.

[0061] Example 6

[0062] A method for preparing ethyl levulinate by microwave-assisted two-phase solvent system, comprising the following steps:

[0063] (1) Take 2.0 g of cellulose and place it in a microwave reactor, add 0.2 g of Ti(SO4)2, 0.2 g of H2SO4 with a mass concentration of 72%, 16 g of ethanol, and 4 g of γ-valerolactone, close the reactor, start the stirrer, and maintain the rotation speed at 400 r / min for the reaction;

[0064] (2) During the reaction, the microwave reactor is controlled by a microcomputer to realize gradient rising of the reaction temperature. The first temperature section is room temperature~100 ℃, the heating rate is 20 ℃ / min, and the temperature is maintained for 2 min. The second temperature section is 100~120 ℃, the heating rate is 20 ℃ / min, and the temperature is maintained for 2 min. The third temperature section is 120~190 ℃, the heating rate is 20 ℃ / min, the set temperature 190 ℃ is reached, and the timing is started, and the temperature is maintained at 190 ℃ for 60 min. The maximum output power is set to 300 W for each section, and the reaction pressure is 2.7 MPa;

[0065] (3) After the reaction is completed, the temperature in the kettle is cooled to room temperature, the reaction kettle is opened, the reaction liquid is poured out and weighed, and the filtrate and residue are obtained by filtration. The residue is washed with ethanol, dried at 100 ℃ to constant weight, and the conversion rate is calculated; a small amount of filtrate is filtered through a 0.45 μm filter membrane, and GC detection is performed to calculate the yield of ethyl levulinate 37.51% and the conversion rate of cellulose 77.20%.

[0066] Example 7

[0067] A method for preparing ethyl levulinate by microwave-assisted two-phase solvent system, comprising the following steps:

[0068] (1) 2.0 poplar powder (<20 μm) is taken into a microwave reaction kettle, 0.2 g Ti(SO4)2, 0.2 g H2SO4 with a mass concentration of 72% and 16 g ethanol, and γ-valerolactone 4 g are added, the reaction kettle is closed, the stirrer is started, and the rotation speed is maintained at 400 r / min for reaction;

[0069] (2) During the reaction, the microwave reactor is controlled by microcomputer to realize the gradient rise of the reaction temperature, the first temperature section is room temperature~100 ℃, the heating rate is 20 ℃ / min, and it is maintained for 2 min; the second temperature section is 100~120 ℃, the heating rate is 20 ℃ / min, and it is maintained for 2 min; the third temperature section is 120~170 ℃, the heating rate is 20 ℃ / min, the set temperature 170 ℃ is reached to start timing, and it is maintained at this temperature for 3 h, and the maximum output power is set to 300 W for each section mode, and the reaction pressure is 2.6 MPa;

[0070] (3) After the reaction is completed, the temperature in the kettle is cooled to room temperature, the reaction kettle is opened, the reaction liquid is poured out and weighed, and the filtrate and residue are obtained by filtration. The residue is washed with ethanol, dried at 100 ℃ to constant weight, and the conversion rate is calculated; a small amount of filtrate is filtered through a 0.45 μm filter membrane, and GC detection is performed to calculate the yield of ethyl levulinate 37.51% and the conversion rate of cellulose 77.20%.

Claims

1. A process for the microwave assisted biphasic solvent system preparation of ethyl levulinate, characterized by, The biomass raw material is placed in a two-phase solvent system, and ethyl levulinate is prepared by using a microwave-assisted catalyst; the catalyst is any one of Ti(SO4)2 or a mixture of Ti(SO4)2 and H2SO4; and the solvent is a mixture of ethanol and gamma-valerolactone.

2. The process for the microwave assisted biphasic solvent system for the preparation of ethyl levulinate as claimed in claim 1 wherein, The reaction temperature is 160-190 DEG C, and the reaction time is 1-6 h.

3. The process for the microwave assisted biphasic solvent system for the preparation of ethyl levulinate as claimed in claim 2 wherein, The biomass raw material is any one of cellulose, poplar, Chinese fir, sugarcane residue, bamboo, wheat straw or corn straw; and the catalyst is used in an amount of 15-25% of the mass of the biomass raw material.

4. The process for the microwave assisted biphasic solvent system for the preparation of ethyl levulinate as claimed in claim 1 wherein, The catalyst is a mixture of Ti(SO4)2 and H2SO4, the mass ratio of Ti(SO4)2 to H2SO4 is 1:1, and the mass concentration of H2SO4 is 72%.

5. The process for the microwave assisted biphasic solvent system for the preparation of ethyl levulinate as claimed in claim 1 wherein, The mass ratio of ethanol to gamma-valerolactone is 3:1-5:

1.

6. The process for the microwave assisted biphasic solvent system for the preparation of ethyl levulinate as claimed in claim 1 wherein, The microwave-assisted heating is performed in a gradient heating mode, specifically: the first temperature section is room temperature-100 DEG C, the heating rate is 18-22 DEG C / min, and the temperature is maintained for 1-3 min; the second temperature section is 100-120 DEG C, the heating rate is 18-22 DEG C / min, and the temperature is maintained for 1-3 min; the third temperature section is 120 DEG C-set temperature, the heating rate is 18-22 DEG C / min, the set temperature is 160-190 DEG C, and the temperature is maintained for 1-6 h; and the maximum output power is set to 300 W in each section.

7. The process for the microwave assisted biphasic solvent system for the preparation of ethyl levulinate as claimed in claim 1 wherein, The method comprises the following steps: (1) cellulose is placed in a microwave reactor, Ti(SO4)2, H2SO4, ethanol and gamma-valerolactone are added, the microwave reactor is closed, a stirrer is started, and the rotation speed is maintained at 400 r / min; (2) during the reaction, the microwave reactor is controlled by a microcomputer to realize gradient rising of the reaction temperature, the first temperature section is room temperature-100 DEG C, the heating rate is 20 DEG C / min, and the temperature is maintained for 2 min; the second temperature section is 100-120 DEG C, the heating rate is 20 DEG C / min, and the temperature is maintained for 2 min; the third temperature section is 120 DEG C-set temperature, the heating rate is 20 DEG C / min, the set temperature is reached, and the temperature is maintained, and the maximum output power is set to 300 W in each section; (3) after the reaction is completed, the temperature in the reactor is cooled to room temperature, the reactor is opened, the reaction liquid is poured out and weighed, and the filter residue and the filtrate containing ethyl levulinate are obtained by filtration.

8. The process for the microwave assisted biphasic solvent system for the preparation of ethyl levulinate as claimed in claim 7 wherein, The catalyst is a mixture of Ti(SO4)2 and H2SO4, the amount of the catalyst is 20% of the mass of the cellulose, the mass ratio of Ti(SO4)2 to H2SO4 is 1:1, the mass concentration of H2SO4 is 72%, and the mass ratio of ethanol to gamma-valerolactone is 4:

1.

9. The process for the microwave assisted biphasic solvent system for the preparation of ethyl levulinate as claimed in claim 7 wherein. The set temperature is 160-170 DEG C, and the temperature is maintained for 3-4 h.

10. The process for the microwave assisted biphasic solvent system for the preparation of ethyl levulinate as claimed in claim 7 wherein, The amount of the cellulose is 2.0 g, the amount of Ti(SO4)2 is 0.2 g, the amount of H2SO4 with a mass concentration of 72% is 0.2 g, the mass of ethanol is 16 g, the mass of gamma-valerolactone is 4 g, the set temperature is 170 DEG C, and the temperature is maintained for 3 h.

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