Double-acid catalyst and method for preparing furfural by catalyzing hemicellulose or xylose

Abstract

The present invention relates to a double-acid catalyst and a method for preparing furfural by catalyzing hemicellulose or xylose. The double-acid catalyst comprises choline chloride, a Bronsted acid, and a Lewis acid at a molar ratio of 1:1:1-4, and is in a deep eutectic state. The method comprises the following steps: adding into a reaction kettle a hemicellulose or xylose raw material, and the double-acid catalyst as a water phase, then adding an oil phase extraction agent, and carrying out catalytic dehydration and hydrolysis reactions in the reaction kettle to generate furfural, wherein the oil phase extraction agent continuously extracts the furfural from the water phase in the reaction process until the reaction is finished. According to the present invention, the choline chloride is combined with the Lewis acid and the Bronsted acid to form a deep eutectic solvent as the double-acid catalyst, and the deep eutectic solvent is used in the process of preparing furfural by catalyzing hemicellulose or xylose, thereby reducing the activation energy required by the reaction, and increasing the yield of the furfural. In addition, the water phase and the catalyst in the preparation process can both be recycled, thereby reducing the energy consumption and the production cost.

Description

A dual-acid catalyst and a method for catalyzing the preparation of furfural from hemicellulose or xylose Technical Field

[0001] The invention belongs to the technical field of furfural preparation, and particularly relates to a double acidic catalyst and a method for catalyzing hemicellulose or xylose to prepare furfural. Background Art

[0002] Lignocellulosic biomass is a carbon-containing renewable resource found widely in agricultural waste, municipal solid waste, and algae. Lignocellulosic biomass is primarily composed of cellulose, hemicellulose, and lignin. Hemicellulose is primarily composed of highly branched and polymerized pentose sugars (such as xylan and arabinan). Hemicellulose first depolymerizes into monosaccharides (such as xylose and arabinose) under an acidic catalyst, which then further dehydrates to form furfural.

[0003] Furfural is an important renewable platform chemical widely used in the production of various furan derivatives. Furfural can also undergo condensation reactions with aldehydes and ketones to form oxygenated intermediates, which are then hydrodeoxygenated to produce liquid alkanes that can be used directly as liquid fuels. Although furfural has great potential in the chemical industry, current production processes face challenges such as low yields and environmental pollution. To further reduce the cost of furfural production, the development of a sustainable production process is needed.

[0004] Currently, the catalysts used to produce furfural by dehydrating hemicellulose or xylose include zeolites, solid acid catalysts, and ionic liquid catalysts. Zeolites and solid acid catalysts are complex to prepare, have high activation energies, and can corrode chemical equipment, hindering long-term production. Ionic liquid catalysts, on the other hand, operate in a homogeneous reaction system, making it difficult to separate the catalyst from the reaction system after completion, resulting in further resource waste.

[0005] In addition, the existing process of preparing furfural from biomass raw materials uses a low eutectic of choline chloride and Lewis acid as a catalyst. Although the yield of furfural is good, the reaction temperature is very high, basically exceeding 180°C. There are also other processes using choline chloride and Bronsted The low melting point of acid is used as catalyst. The reaction temperature of this process is low, generally not exceeding 150℃, but the yield of furfural is low. Others use Lewis acid and Bronsted acid. The acid mixture is used as a catalyst. The furfural yield of this process is acceptable and the temperature is moderate, but the catalyst is difficult to separate, resulting in more waste of resources.

[0006] In summary, further efforts are needed to design low-cost, catalytically active and sustainable catalysts for the production of furfural from hemicellulose or xylose dehydration.

[0007] Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a dual-acid catalyst and a method for catalyzing the production of furfural from hemicellulose or xylose. The dual-acid catalyst comprises a deep eutectic formed by combining choline chloride with a Lewis acid and a Brønsted acid. This eutectic is used in the process of catalyzing the production of furfural from hemicellulose or xylose, thereby reducing the activation energy required for the reaction and increasing the yield of furfural. Furthermore, the aqueous phase and catalyst in the preparation process can be recycled, reducing energy consumption and production costs.

[0009] The present invention is achieved by providing a dual-acid catalyst comprising choline chloride, Bronsted acid and Lewis acid in a molar ratio of 1:1:1-4, which is in a deep eutectic state.

[0010] Furthermore, the Bronsted acid is any one of oxalic acid, malonic acid, succinic acid and citric acid.

[0011] Furthermore, the Lewis acid is any one of CrCl3·6H2O, AlCl3·6H2O, SnCl4·5H2O and FeCl3·6H2O.

[0012] Furthermore, the dual-acid catalyst is prepared by mixing 1 mol of choline chloride, 1 mol of oxalic acid and 1 mol of CrCl3·6H2O and heating the mixture at 70°C for 6 hours to obtain a deep eutectic in a eutectic state.

[0013] The present invention is achieved in this way. It also provides a method for catalyzing hemicellulose or xylose to prepare furfural, comprising the following steps: adding the hemicellulose or xylose raw material and the bi-acidic catalyst as described above as the aqueous phase into a reactor, then adding an oil phase extractant capable of extracting furfural, catalytic dehydration and hydrolysis reactions occur in the reactor to generate furfural, and the oil phase extractant continuously extracts furfural from the aqueous phase during the reaction until the reaction is completed.

[0014] Furthermore, the oil phase extractant includes any one of methyl isobutyl ketone (MIBK), toluene, tetrahydrofuran (THF), valerolactone, n-butanol, acetophenone, ethyl acetate and tetralin.

[0015] Furthermore, the mass concentration of the hemicellulose or xylose (based on the mass of water) is 0.05 g / mL to 0.25 g / mL.

[0016] Furthermore, the mass concentration of the dual-acid catalyst (based on the mass of water) is 0.05 g / mL to 0.25 g / mL.

[0017] Furthermore, the amount of the aqueous phase added is 1 / 2 to 1 / 10 of the oil phase extractant.

[0018] Furthermore, the reaction temperature is 140° C. to 160° C., and the reaction time is 30 min to 150 min.

[0019] Compared to the prior art, the present invention discloses a dual-acid catalyst and a method for catalyzing the production of furfural from hemicellulose or xylose. The dual-acid catalyst comprises choline chloride, a Brønsted acid, and a Lewis acid in a molar ratio of 1:1:1 to 4, in a deep eutectic state. The method comprises the following steps: adding the hemicellulose or xylose raw material and the aforementioned dual-acid catalyst as the aqueous phase to a reactor, then adding an oil-phase extractant, catalyzing dehydration and hydrolysis reactions in the reactor to produce furfural, and continuously extracting the furfural from the aqueous phase with the oil-phase extractant until the reaction is complete. The present invention utilizes a dual-acid catalyst, formed by combining choline chloride with a Lewis acid and a Brønsted acid, to form a deep eutectic. This catalyst is used in the process of catalyzing the production of furfural from hemicellulose or xylose, reducing the activation energy required for the reaction and increasing the yield of furfural, while maintaining mild reaction conditions. Furthermore, the aqueous phase and catalyst can be recycled during the preparation process, reducing energy consumption and production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG1 is a schematic diagram showing the effect of reaction temperature and time on furfural yield in Examples 3 and 4 of the present invention;

[0021] FIG2 is a schematic diagram showing the effect of the mass concentration of catalyst B on the furfural yield in Example 5 of the present invention;

[0022] FIG3 is a schematic diagram of a curve showing the effect of xylose mass concentration on furfural yield in Example 6 of the present invention;

[0023] FIG4 is a schematic diagram showing the effect of reaction temperature and time on furfural yield in Examples 9 and 10 of the present invention;

[0024] FIG5 is a schematic diagram of a curve showing the effect of the mass concentration of catalyst B on the furfural yield in Example 12 of the present invention. DETAILED DESCRIPTION

[0025] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0026] The present invention discloses a preferred embodiment of a dual-acid catalyst, which comprises choline chloride, Bronsted acid and Lewis acid in a molar ratio of 1:1:1-4, and is in a deep eutectic state.

[0027] The present invention also discloses a method for catalyzing hemicellulose or xylose to prepare furfural, comprising the following steps: adding hemicellulose or xylose raw materials and the above-mentioned double acid catalyst as the aqueous phase into a reactor, then adding an oil phase extractant, and performing catalytic dehydration and hydrolysis reactions in the reactor to generate furfural, wherein the oil phase extractant continuously extracts furfural from the aqueous phase during the reaction until the reaction is completed.

[0028] Among them, the aqueous phase finally generated after the reaction is completed includes a diacidic catalyst, a small amount of unreacted hemicellulose solution or xylose solution raw material, etc., and the oil phase includes furfural and oil phase extractant, etc.

[0029] After the reaction is completed, the entire reaction system in the reactor exhibits a biphasic separation of an aqueous phase and an oil phase. The aqueous phase (containing the bi-acidic catalyst) and the oil phase are separated using a separatory funnel. The separated aqueous phase is recycled, and the loss of the bi-acidic catalyst is minimized. The recovered bi-acidic catalyst and the fresh oil phase are then combined to form a new biphasic reaction system, and the catalytic reaction is repeated according to the above steps to produce furfural. Therefore, both the aqueous phase and the catalyst in the preparation process of the present invention can be recycled, reducing energy consumption and production costs.

[0030] The following specific examples further illustrate the dual-acid catalyst and the method for catalyzing the preparation of furfural from hemicellulose or xylose of the present invention.

[0031] Example 1

[0032] Preparation of di-acidic catalysts in different proportions includes the following steps:

[0033] 11. Weigh 1.39 g of choline chloride (ChCl), 0.9 g of oxalic acid (Ea), and 2.66 g of CrCl3·6H2O in a molar ratio of 1:1:1, place them separately into a screw-cap bottle, and heat them at 70°C for 6 h to obtain a di-acidic ion deep eutectic, recorded as catalyst B.

[0034] 12. The molar ratio of CrCl3·6H2O in step 11 was changed to synthesize di-acidic ion deep eutectics according to the molar ratios of 1:1:0.5, 1:1:2, 1:1:3 and 1:1:4, which were recorded as catalysts A, C, D and E.

[0035] 13. Use malonic acid, succinic acid and citric acid to replace the oxalic acid in step 11 respectively, and synthesize double-acid catalysts in a molar ratio of 1:1:1, which are recorded as catalysts F, G and H.

[0036] 14. Choline chloride (ChCl) was mixed with oxalic acid (Ea) and CrCl3·6H2O in a molar ratio of 1:1, and acidic eutectic catalysts were synthesized according to the method of step 11. The catalysts were designated as catalysts M and N, respectively.

[0037] Example 2

[0038] The first method of the present invention for preparing furfural by catalyzing hemicellulose or xylose comprises the following steps:

[0039] 21. Catalysts A, B, C, D, E, F, G, H, I, J, K, M and N prepared in Example 1 were added to a 25 ml reactor in an amount of 20% of the mass of the aqueous phase (the same below). The volume ratio of the oil phase to the aqueous phase was 8:1, and the mass concentration of xylose added was 0.15 g / mL (based on the mass of water, the same below).

[0040] 22. Place the reactor in an oil bath, heat to 140°C under magnetic stirring, and react for 90 minutes until the reaction is complete.

[0041] 23. After the reactor cools to room temperature, take the upper oil phase and the lower water phase to detect the furfural content and calculate the yield.

[0042] It was determined that when the amount of catalyst added was 20% of the mass of the water phase, the yield of furfural was Y FF As shown in Table 1 below:

[0043] Table 1 Effect of catalysts with different raw material ratios on furfural yield (xylose as substrate)

[0044] As can be seen from Table 1, when catalyst B is used, the yield of furfural is FF The highest is 87.0%.

[0045] Example 3

[0046] The second method of the present invention for preparing furfural by catalyzing hemicellulose or xylose comprises the following steps:

[0047] 31. Catalyst B prepared in Example 1 was placed in a reactor. The amount of catalyst B added was 20% of the mass of the aqueous phase. The volume ratio of MIBK to water was 8:1. The mass concentration of xylose added was 0.15 g / mL.

[0048] 32. Place the reactor in an oil bath and heat to 140-160°C under magnetic stirring. React for 90 minutes until the reaction is complete.

[0049] 33. After the reactor is cooled to room temperature, the same method as in Example 2 is used to take the upper oil phase and the lower water phase to detect the furfural content and calculate the yield.

[0050] The results are shown in Figure 1. When the reaction temperature is 140°C, 150°C and 160°C, the yields of furfural are 73.9%, 87.0% and 86.0%, respectively. When the reaction temperature is 150°C, the yield of furfural is the highest, at 87.0%.

[0051] Example 4

[0052] The third method of the present invention for preparing furfural by catalyzing hemicellulose or xylose comprises the following steps:

[0053] 41. Catalyst B prepared in Example 1 was placed in a reactor. The amount of catalyst B added was 20% of the mass of the aqueous phase. The volume ratio of MIBK to water was 8:1. The mass concentration of xylose added was 0.15 g / mL.

[0054] 42. Place the reactor in the system of step 41 in an oil bath, heat to 150°C under magnetic stirring, and react for 30 min, 60 min, 90 min, 120 min and 150 min respectively. After the reactor is cooled to room temperature, the upper oil phase and the lower aqueous phase are taken in the same manner as in Example 2 to detect the furfural content and calculate the yield.

[0055] The results are shown in Figure 1. When the reaction time is 30 min, 60 min, 90 min, 120 min and 150 min, the yields of furfural are 51.4%, 80.8%, 87.0%, 83.2% and 85.2% respectively. When the reaction time is 90 min, the yield of furfural is the highest, at 87.0%.

[0056] Example 5

[0057] A fourth method of the present invention for preparing furfural by catalyzing hemicellulose or xylose comprises the following steps:

[0058] 51. Catalyst B prepared in Example 1 was weighed at concentrations of 0.05 g / mL, 0.10 g / mL, 0.15 g / mL, 0.20 g / mL, and 0.25 g / mL, respectively, and added to a 25 mL reactor. The volume ratio of MIBK to water was 8:1, and the mass concentration of xylose added was 0.15 g / mL.

[0059] 52. Place the reactor in an oil bath, heat to 150°C under magnetic stirring, and react for 90 minutes until the reaction is complete.

[0060] 53. After the reactor is cooled to room temperature, the same method as in Example 2 is used to take the upper oil phase and the lower water phase to detect the furfural content and calculate the yield.

[0061] The results are shown in Figure 2. When the mass concentrations of Catalyst B were 0.05 g / mL, 0.10 g / mL, 0.15 g / mL, 0.20 g / mL, and 0.25 g / mL, the furfural yields were 75.8%, 82.9%, 83.0%, 87.0%, and 87.1%, respectively. After comprehensive consideration, the most suitable furfural yield was 87.0% when the mass concentration of Catalyst B was 0.20 g / mL.

[0062] Example 6

[0063] A fifth method of the present invention for preparing furfural by catalyzing hemicellulose or xylose comprises the following steps:

[0064] 61. Catalyst B prepared in Example 1 was placed in a reactor. The mass concentration of catalyst B was 0.20 g / mL, and the volume ratio of MIBK to water was 8:1.

[0065] 62. Weigh 0.05 g / mL, 0.10 g / mL, 0.15 g / mL, 0.20 g / mL and 0.25 g / mL of xylose respectively and add them to the reactor of step (61). Place the reactor in an oil bath and heat to 150°C under magnetic stirring. React for 90 minutes and the reaction is completed.

[0066] 63. After the reactor is cooled to room temperature, the same method as in Example 2 is used to take the upper oil phase and the lower water phase to detect the furfural content and calculate the yield.

[0067] The results are shown in Figure 3. When the xylose concentrations were 0.05 g / mL, 0.10 g / mL, 0.15 g / mL, 0.20 g / mL, and 0.25 g / mL, the furfural yields were 80.9%, 83.7%, 87%, 80%, and 79%, respectively. When the xylose concentration was 0.15 g / mL, the furfural yield reached a maximum of 87.0%.

[0068] Example 7

[0069] A sixth method of the present invention for preparing furfural by catalyzing hemicellulose or xylose comprises the following steps:

[0070] 71. Take the catalyst B prepared in Example 1 into the reaction kettle. The mass concentration of catalyst B is 0.20 g / mL, and the mass concentration of xylose is 0.15 g / mL.

[0071] 72. MIBK and water were measured at volume ratios of 2:1, 4:1, 6:1, 8:1 and 10:1 respectively and added to the reactor. The reactor was placed in an oil bath and heated to 150°C under magnetic stirring for 90 minutes. The reaction was completed.

[0072] 73. After the reactor is cooled to room temperature, the same method as in Example 2 is used to take the upper oil phase and the lower water phase to detect the furfural content and calculate the yield.

[0073] The yields of furfural were determined to be 81.8%, 83.3%, 85.5%, 87%, and 85.9% when the volume ratio of MIBK to water was 2:1, 4:1, 6:1, 8:1, and 10:1, respectively. The highest yield of furfural was 87.0% when the volume ratio of the oil phase to the water phase was 8:1.

[0074] Example 8

[0075] A seventh method of the present invention for preparing furfural by catalyzing hemicellulose or xylose comprises the following steps:

[0076] 81. Catalyst B prepared in Example 1 was placed in a reactor. The mass concentration of catalyst B was 0.20 g / mL, the mass concentration of xylose added was 0.15 g / mL, the volume ratio of the oil phase to the aqueous phase was 8:1, and the types of the oil phase were MIBK, toluene, tetrahydrofuran, acetophenone, valerolactone, n-butanol, tetralin and ethyl acetate.

[0077] 82. Place the reactor in an oil bath, heat to 150°C under magnetic stirring, and react for 90 minutes until the reaction is complete.

[0078] After the reactor was cooled to room temperature, the same method as in Example 2 was used to take the upper oil phase and the lower water phase to detect the furfural content and calculate the yield.

[0079] The yields of furfural were determined to be 87.0%, 78.1%, 76%, 66%, 53.2%, 49.9%, 69.4% and 60.2% when the oil phase was MIBK, toluene, tetrahydrofuran, acetophenone, valerolactone, n-butanol, tetralin and ethyl acetate, respectively. The highest yield of furfural was 87.0% when MIBK was used as the oil phase.

[0080] Example 9

[0081] An eighth method of the present invention for preparing furfural by catalyzing hemicellulose or xylose comprises the following steps:

[0082] 91. Catalyst B prepared in Example 1 was placed in a reaction vessel at a concentration of 0.20 g / mL. Hemicellulose was added at a concentration of 0.15 g / mL. The volume ratio of the oil phase to the aqueous phase was 8:1.

[0083] 92. Place the reactor in an oil bath, heat to 140°C to 160°C under magnetic stirring, and react for 90 minutes until the reaction is complete.

[0084] After the reactor was cooled to room temperature, the same method as in Example 2 was used to take the upper oil phase and the lower water phase to detect the furfural content and calculate the yield.

[0085] The results are shown in Figure 4. When the reaction temperature is 140°C, 150°C, and 160°C, the yields of furfural are 60.4%, 79.8%, and 78.2%, respectively. When the reaction temperature is 150°C, the yield of furfural is the highest at 79.8%.

[0086] Example 10

[0087] A ninth method of the present invention for preparing furfural by catalyzing hemicellulose or xylose comprises the following steps:

[0088] 101. Catalyst B prepared in Example 1 was placed in a reactor at a concentration of 0.20 g / mL. Hemicellulose was added at a concentration of 0.15 g / mL. The volume ratio of the oil phase to the aqueous phase was 8:1.

[0089] 102. Place the reactor in an oil bath and heat to 150°C under magnetic stirring. The reaction time is 30 minutes to 150 minutes, and the reaction is complete.

[0090] 103. Using the same method as Example 2, take the upper oil phase and the lower water phase to detect the furfural content and calculate the yield.

[0091] The results are shown in Figure 4. When the reaction time is 30 minutes, 60 minutes, 90 minutes, 120 minutes and 150 minutes, the yields of furfural are 35.4%, 60.7%, 79.8%, 78.2% and 77%, respectively. When the reaction time is 90 minutes, the yield of furfural is the highest, at 79.8%.

[0092] Example 11

[0093] A tenth method of the present invention for preparing furfural by catalyzing hemicellulose or xylose comprises the following steps:

[0094] 111. Weigh 0.10 kg / L, 0.15 kg / L, 0.2 kg / L, 0.25 kg / L, 0.3 kg / L, 0.35 kg / L and 0.4 kg / L of hemicellulose respectively and add them to the reactor. The volume ratio of oil phase to water phase is 8:1. The mass concentration of catalyst B prepared in Example 1 is 0.20 g / mL.

[0095] 112. Place the reactor in an oil bath, heat to 150°C under magnetic stirring, and react for 90 minutes until the reaction is complete.

[0096] 113. Using the same method as Example 2, take the upper oil phase and the lower water phase to detect the furfural content and calculate the yield.

[0097] The yields of furfural prepared by dehydration of hemicellulose at different mass concentrations are shown in Table 2.

[0098] Table 2 Effect of different mass concentrations of hemicellulose on furfural yield (hemicellulose as substrate)

[0099] As shown in Table 2, when hemicellulose with different mass concentrations is dehydrated to prepare furfural, the yield of furfural is Y when the mass concentration is 0.15 g / mL. FF The highest is 79.8%.

[0100] Example 12

[0101] The eleventh method of the present invention for preparing furfural by catalyzing hemicellulose or xylose comprises the following steps:

[0102] 121. The catalyst B prepared in Example 1 was weighed at mass concentrations of 0.05 g / mL, 0.10 g / mL, 0.15 g / mL, 0.20 g / mL and 0.25 g / mL respectively and added into a 25 mL reactor. The volume ratio of MIBK to water was 8:1, and the mass concentration of hemicellulose added was 0.15 g / mL.

[0103] 122. Place the reactor in an oil bath, heat to 150°C under magnetic stirring, and react for 90 minutes until the reaction is complete.

[0104] 123. Using the same method as in Example 2, take the upper oil phase and the lower water phase to detect the furfural content and calculate the yield.

[0105] The results are shown in Figure 5. When the mass concentrations of Catalyst B were 0.05 g / mL, 0.10 g / mL, 0.15 g / mL, 0.20 g / mL, and 0.25 g / mL, the furfural yields were 50.6%, 64.4%, 75.6%, 79.8%, and 76.8%, respectively. After comprehensive consideration, the optimum furfural yield was 87.0% at a concentration of 0.20 g / mL.

[0106] Example 13

[0107] The twelfth method of the present invention for preparing furfural by catalyzing hemicellulose or xylose comprises the following steps:

[0108] 131. Catalyst B prepared in Example 1 was placed in a reactor. The mass concentration of catalyst B was 0.20 g / mL, the concentration of xylose was 0.15 g / mL, and the volume ratio of MIBK to water was 8:1.

[0109] 132. Place the reactor in an oil bath, heat to 150°C under magnetic stirring, and react for 90 minutes.

[0110] 133. After the reactor is cooled to room temperature, the same method as in Example 2 is used to take the upper oil phase and the lower water phase to detect the furfural content and calculate the yield.

[0111] After the reaction is completed, the entire reaction system in the reactor shows a phenomenon of two-phase separation of water phase and oil phase. The water phase (containing the catalyst) and the oil phase are separated by a separatory funnel. The separated water phase is recycled and re-formed into a new two-phase reaction system with the fresh oil phase. The catalytic reaction is repeated according to the above steps 131 to 133 to prepare furfural, and the furfural yield of each cycle is measured.

[0112] It was determined that the furfural yields were 87.0%, 88.7%, 88.5%, 87.6%, 85.2%, 86.8%, 85.3%, 86.5% and 85.7% when the deep eutectic catalyst was cycled 0, 1, 2, 3, 4, 5, 6, 7 and 8, respectively. It was found that there was almost no significant activity loss after the deep eutectic catalyst was cycled 8 times.

[0113] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A dual-acid catalyst, characterized in that The invention comprises choline chloride, Bronsted acid and Lewis acid in a molar ratio of 1:1:1 to 4, and is in a deep eutectic state.

2. The dual-acid catalyst according to claim 1, wherein The Bronsted acid is any one of oxalic acid, malonic acid, succinic acid and citric acid.

3. The dual-acid catalyst according to claim 1, wherein The Lewis acid is any one of CrCl3·6H2O, AlCl3·6H2O, SnCl4·5H2O and FeCl3·6H2O.

4. The dual-acid catalyst according to claim 1, wherein The dual-acid catalyst is prepared by mixing 1 mol of choline chloride, 1 mol of oxalic acid and 1 mol of CrCl3·6H2O and heating the mixture at 70°C for 6 hours to obtain a deep eutectic in a eutectic state.

5. A method for catalyzing the production of furfural from hemicellulose or xylose, characterized in that: The method comprises the following steps: adding hemicellulose or xylose raw material and the dual-acid catalyst as described in any one of claims 1 to 4 as an aqueous phase into a reactor, then adding an oil phase extractant, and performing catalytic dehydration and hydrolysis reactions in the reactor to generate furfural, wherein the oil phase extractant continuously extracts furfural from the aqueous phase during the reaction until the reaction is completed.

6. The method for preparing furfural by catalyzing hemicellulose or xylose according to claim 5, characterized in that: The oil phase extractant includes any one of methyl isobutyl ketone, toluene, tetrahydrofuran, valerolactone, n-butanol, acetophenone, ethyl acetate and tetralin.

7. The method for preparing furfural by catalyzing hemicellulose or xylose according to claim 5, characterized in that: The mass concentration of the hemicellulose or xylose is 0.05 g / mL to 0.25 g / mL.

8. The method for preparing furfural by catalyzing hemicellulose or xylose according to claim 5, wherein: The mass concentration of the dual-acid catalyst is 0.05 g / mL to 0.25 g / mL.

9. The method for preparing furfural by catalyzing hemicellulose or xylose according to claim 5, characterized in that: The amount of the aqueous phase added is 1 / 2 to 1 / 10 of the oil phase extractant.

10. The method for preparing furfural by catalyzing hemicellulose or xylose according to claim 5, characterized in that: The reaction temperature is 140° C. to 160° C., and the reaction time is 30 min to 150 min.

Images