Method for preparing furfural by catalyzing biomass with phenolic hydroxyl functionalized covalent organic framework material

Abstract

The present invention relates to the technical field of biomass catalytic conversion technology and biomass energy chemical engineering, and in particular relates to a method for preparing furfural by catalyzing biomass with a phenol hydroxyl functionalized covalent organic framework material. The present invention synthesizes imine functionalized covalent organic frameworks (COFs using a phenolic hydroxyl-containing monomer as a raw material, and by means of a Schiff base dehydration-condensation reaction; the constructed phenolic hydroxyl functionalized COFs exhibit a large specific surface area, a rich pore structure, high crystallinity and strong thermal stability, and have numerous acidic sites, which may efficiently catalyze biomass raw materials to prepare furfural. The novel phenolic hydroxyl functionalized COFs of the present invention may be applied to a reaction catalyzing biomass to prepare furfural, thus opening up a sustainable new path for high-value utilization of renewable biomass resources producing furfuran chemical products; furfural may be produced with high selectivity by catalyzing biomass under mild conditions; in addition, the high stability solves the problems of low selectivity and difficulties in reusing catalysts during furfural production.

Description

A method for preparing furfural from biomass using phenolic hydroxyl functionalized covalent organic framework materials

[0001] The present invention claims priority to a Chinese patent application filed with the Patent Office of China on June 27, 2023, with application number 202310770415.6 and invention name “A method for preparing furfural from biomass catalyzed by a phenolic hydroxyl functionalized covalent organic framework material”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The invention belongs to the field of biomass catalytic conversion technology and biomass energy chemical technology, and particularly relates to a method for preparing furfural from biomass by catalyzing a phenolic hydroxyl functionalized covalent organic framework material. Background Art

[0003] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0004] As a renewable organic resource, biomass has injected new impetus into the sustainable development of modern society. Pretreated biomass can be converted into platform compounds, which in turn can be used to produce a variety of value-added chemicals. Furfural, among others, is considered a versatile bio-based C5 platform molecule due to its potential for application in biomass energy. The conversion of biomass to furfural primarily involves two steps: hydrolysis and dehydration, with acidic catalysts being key influencing these steps.

[0005] Currently, acidic catalysts used for the conversion of biomass to furfural include homogeneous catalysts and heterogeneous catalysts. Homogeneous catalysts are in the same phase as the reactants and have high catalytic performance, but separation and recovery have always been a key issue restricting their development. Heterogeneous catalysts have a clear phase interface with the reactants, making them easy to recycle and reuse, but they usually require external forces (such as mechanical stirring) to strengthen contact with the reactants, and their catalytic performance is lower than that of homogeneous catalysts. Therefore, the development of new heterogeneous catalysts with excellent catalytic performance is key to achieving rapid development of the furfural industry.

[0006] Covalent organic frameworks (COFs) are the best choice to meet these requirements. COFs are a class of crystalline nanomaterials that integrate organic units into well-defined two- and three-dimensional polymers, offering a high degree of designability. However, there is currently no research in the industry demonstrating the use of COFs to catalyze the highly selective production of furfural from biomass under mild conditions.

[0007] Summary of the Invention

[0008] To address these issues, the present invention provides a method for producing furfural from biomass using phenolic hydroxyl-functionalized covalent organic frameworks (COFs) as catalysts. Specifically, a biomass feedstock, phenolic hydroxyl-functionalized COFs, and a solvent are sequentially added to a reactor, which is then filled with an inert gas. The reaction proceeds at a specific temperature to produce furfural with high selectivity.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] The first aspect of the present invention provides a method for preparing furfural from biomass using a phenolic hydroxyl functionalized covalent organic framework material as catalyst, comprising:

[0011] Using aldehyde or / and amino compounds containing phenolic hydroxyl functional groups as monomers, a solvent thermal, microwave or grinding method is used to produce a Schiff base reaction, followed by dehydration condensation to prepare phenolic hydroxyl functionalized COFs.

[0012] The biomass raw materials and phenolic hydroxyl functionalized COFs are uniformly mixed in a solvent, and catalytic reaction is carried out at 160-210° C. for 0.5-5 hours under an inert atmosphere to prepare furfural.

[0013] This invention proposes a method for catalyzing the production of furfural from biomass using phenolic hydroxyl-functionalized covalent organic frameworks. The covalent organic framework's rich pore structure provides ample diffusion space for the production of furfural. The phenolic hydroxyl-functionalized COFs of the present invention possess numerous and evenly distributed acidic sites, enabling highly selective production of furfural from biomass under mild conditions. This invention opens up a new path for the efficient production of biomass energy, addressing issues such as poor selectivity and difficulty in catalyst reuse during furfural production.

[0014] The second aspect of the present invention provides a method for preparing a phenolic hydroxyl functionalized covalent organic framework material, comprising:

[0015] Using 4,4-(1,3,5-triazine-2,4,6-triyl)triphenylamine and 2,5-dihydroxyterephthalaldehyde as monomers, a Schiff base reaction was carried out by solvent thermal, microwave or grinding method, and phenolic hydroxyl functionalized COFs were prepared through dehydration condensation.

[0016] The third aspect of the present invention provides the use of the above-mentioned phenolic hydroxyl functionalized COFs in catalyzing the production of furfural from biomass.

[0017] Beneficial effects of the present invention

[0018] (1) The present invention proposes to apply COFs to the catalytic production of furfural, opening up a new path for the efficient production of biomass energy.

[0019] (2) The present invention uses phenolic hydroxyl-containing monomers as raw materials to synthesize COFs, which have a large number of evenly distributed acidic sites and can catalyze the highly selective production of furfural from biomass under mild conditions.

[0020] (3) The COFs prepared by the present invention are highly stable and can be reused multiple times with stable performance.

[0021] (4) The preparation method of the present invention is simple, practical, and easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their description are used to explain the present invention and do not constitute improper limitations on the present invention.

[0023] FIG1 is a process diagram of the present invention.

[0024] FIG2 is the infrared and XRD spectra of COFs prepared in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0026] A method for preparing furfural from biomass using a phenolic hydroxyl functionalized covalent organic framework material as catalyst, comprising:

[0027] Using aldehyde or / and amino compounds containing phenolic hydroxyl functional groups as monomers, a solvent thermal, microwave or grinding method is used to produce a Schiff base reaction, followed by dehydration condensation to prepare phenolic hydroxyl functionalized COFs.

[0028] The biomass raw materials and phenolic hydroxyl functionalized COFs are uniformly mixed in a solvent, and catalytic reaction is carried out at 160-210° C. for 0.5-5 hours under an inert atmosphere to prepare furfural.

[0029] In some embodiments, the biomass raw materials include but are not limited to xylan, xylose, arabinose, and biomass pre-hydrolyzate.

[0030] In some embodiments, the solvent is at least one of water, tetrahydrofuran, toluene, and γ-valerolactone.

[0031] In some embodiments, the inert atmosphere is selected from nitrogen, argon, and helium.

[0032] In some embodiments, the biomass feedstock concentration is 20-40 g / L.

[0033] In some embodiments, the amount of the phenolic hydroxyl functionalized COFs is 0.05-0.5 g.

[0034] In some embodiments, the solvent volume is 30-50 ml.

[0035] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are intended to explain the present invention rather than to limit it.

[0036] Example 1:

[0037] A method for preparing furfural by catalyzing D-xylose with phenolic hydroxyl functionalized covalent organic framework material

[0038] (1) Prepare ingredients

[0039] During the preparation of the phenolic hydroxyl functionalized COF material, the raw material components were mixed according to the following dosage ratios: 170.13 mg of 4,4-(1,3,5-triazine-2,4,6-triyl)triphenylamine, 119.61 mg of 2,5-dihydroxyterephthalaldehyde, 3 ml of n-butanol, 3 ml of o-dichlorobenzene, and 0.6 ml of acetic acid.

[0040] In the catalytic production process of furfural by phenolic hydroxyl functionalized COF material, the raw material components are mixed according to the following dosage ratio: 1.2 g of D-xylose, 30 ml of solvent, and some COF material.

[0041] (2) Preparation of phenolic hydroxyl functionalized COF materials

[0042] The prepared 4,4-(1,3,5-triazine-2,4,6-triyl)triphenylamine, n-butanol, 2,5-dihydroxyterephthalaldehyde, o-dichlorobenzene, and acetic acid were added to a thick-walled pressure-resistant tube in sequence and mixed evenly. According to the solvent thermal method, the reaction was carried out at 120°C for 72 hours. After cooling, the mixture was washed three times with n-butanol, o-dichlorobenzene, and hot water respectively, and dried for 12 hours to obtain the COF-A material.

[0043] (3) Application of phenolic hydroxyl functionalized COF materials in the preparation of furfural from D-xylose

[0044] The prepared D-xylose, solvent, and COF material were sequentially added to a reactor. The air in the reactor was replaced with nitrogen three to four times, and the stirring rate was set to 500 rpm. The solvent selection, reaction temperature, reaction time, and catalyst dosage are shown in Table 1. After the reaction, the reactor was cooled to room temperature, and the liquid product was collected for qualitative and quantitative analysis. The results are shown in Table 1.

[0045] Table 1. Data table of different reaction conditions and reaction results in Example 1 ※: In the two-phase system consisting of water and organic solvent, the ratio of water to organic solvent is 1:1.

[0046] Example 2:

[0047] A method for preparing furfural by catalyzing xylan with phenolic hydroxyl functionalized covalent organic framework material

[0048] (1) Prepare ingredients

[0049] During the preparation of phenolic hydroxyl functionalized COF materials, the raw material components were mixed according to the following dosage ratios: 170.13 mg of 4,4-(1,3,5-triazine-2,4,6-triyl)triphenylamine, 119.61 mg of 2,5-dihydroxyterephthalaldehyde, 3 ml of mesitylene, 3 ml of 1,4-dioxane, and 0.6 ml of acetic acid.

[0050] In the catalytic production process of furfural by phenolic hydroxyl functionalized COF material, the raw material components are mixed according to the following dosage ratio: 1.2g xylan, 30ml solvent, and some COF material.

[0051] (2) Preparation of phenolic hydroxyl functionalized COF materials

[0052] The prepared 4,4-(1,3,5-triazine-2,4,6-triyl)triphenylamine, mesitylene, 2,5-dihydroxyterephthalaldehyde, 1,4-dioxane, and acetic acid were added to a thick-walled pressure-resistant tube in sequence and mixed evenly. According to the solvent thermal method, the reaction was carried out at 120°C for 72 hours. After cooling, the mixture was washed three times with mesitylene, 1,4-dioxane, and hot water respectively, and dried for 12 hours to obtain the COF-B material.

[0053] (3) Application of phenolic hydroxyl functionalized COF materials in catalyzing the preparation of furfural from xylan

[0054] The prepared xylan, solvent, and COF material were sequentially added to a reactor. The air in the reactor was replaced with argon three to four times, and the stirring rate was set to 500 rpm. The solvent selection, reaction temperature, reaction time, and catalyst dosage are shown in Table 2. After the reaction, the reactor was cooled to room temperature, and the liquid product was collected for qualitative and quantitative analysis. The results are shown in Table 2.

[0055] Table 2. Data table of different reaction conditions and reaction results in Example 2 ※ : In the two-phase system consisting of water and organic solvent, the ratio of water to organic solvent is 1:1.

[0056] Example 3:

[0057] A method for preparing furfural by catalyzing arabinose using a phenolic hydroxyl functionalized covalent organic framework material

[0058] (1) Prepare ingredients

[0059] During the preparation of phenolic hydroxyl functionalized COF materials, the raw material components were mixed according to the following dosage ratios: 170.13 mg of 4,4-(1,3,5-triazine-2,4,6-triyl)triphenylamine, 119.61 mg of 2,5-dihydroxyterephthalaldehyde, 0.06 mg of scandium trifluoromethanesulfonate, 3 ml of mesitylene, 12 ml of 1,4-dioxane, and 150 ml of methanol.

[0060] In the catalytic production process of furfural by phenolic hydroxyl functionalized COF material, the raw material components are mixed according to the following dosage ratio: 1.2 g of arabinose, 30 ml of solvent, and some COF material.

[0061] (2) Preparation of phenolic hydroxyl functionalized COF materials

[0062] The prepared 4,4-(1,3,5-triazine-2,4,6-triyl)triphenylamine, 2,5-dihydroxyterephthalaldehyde, scandium trifluoromethanesulfonate, mesitylene, and 1,4-dioxane were added to a glass bottle in sequence, mixed thoroughly, and allowed to stand for 30 minutes. The product was then Soxhlet extracted with methanol for 12 hours. After cooling, the product was washed three times with mesitylene, 1,4-dioxane, and hot water, respectively, and dried for 12 hours to obtain the COF-C material.

[0063] (3) Application of phenolic hydroxyl functionalized COF materials in catalyzing the preparation of furfural from arabinose

[0064] The prepared arabinose, solvent, and COF material were sequentially added to a reactor. The air in the reactor was replaced with helium three to four times, and the stirring rate was set to 500 rpm. The solvent selection, reaction temperature, reaction time, and catalyst dosage are shown in Table 3. After the reaction, the reactor was cooled to room temperature, and the liquid product was collected for qualitative and quantitative analysis. The results are shown in Table 3.

[0065] Table 3. Data table of different reaction conditions and reaction results in Example 3 ※ : In the two-phase system consisting of water and organic solvent, the ratio of water to organic solvent is 1:1.

[0066] Example 4:

[0067] A method for preparing furfural by catalyzing xylan with phenolic hydroxyl functionalized covalent organic framework material

[0068] (1) Prepare ingredients

[0069] During the preparation of phenolic hydroxyl functionalized COF materials, the raw material components were mixed according to the following dosage ratios: 159.60 mg of 4,4-(1,3,5-triazine-2,4,6-triyl)triphenylamine, 80.40 mg of 2-hydroxy-1,3,5-benzenetricarboxaldehyde, 9 ml of mesitylene, 9 ml of 1,4-dioxane, and 1.8 ml of acetic acid.

[0070] In the catalytic production process of furfural by phenolic hydroxyl functionalized COF material, the raw material components are mixed according to the following dosage ratio: 1.2 g of D-xylose, 30 ml of solvent, and some COF material.

[0071] (2) Preparation of phenolic hydroxyl functionalized COF materials

[0072] The prepared 4,4-(1,3,5-triazine-2,4,6-triyl)triphenylamine, mesitylene, 2-hydroxy-1,3,5-benzenetricarboxaldehyde and 1,4-dioxane were added to a thick-walled pressure-resistant tube in sequence and mixed evenly. According to the solvothermal method, the mixture was reacted at 120°C for 72 hours. After cooling, the mixture was washed three times with mesitylene, 1,4-dioxane and hot water respectively, and dried for 12 hours to obtain the COF-D material.

[0073] (3) Application of phenolic hydroxyl functionalized COF materials in the preparation of furfural from D-xylose

[0074] The prepared D-xylose, solvent, and COF material were sequentially added to a reactor. The air in the reactor was replaced with nitrogen three to four times, and the stirring rate was set to 500 rpm. The reaction temperature, reaction time, and catalyst dosage are shown in Table 4. After the reaction, the reactor was cooled to room temperature, and the liquid product was collected for qualitative and quantitative analysis. The results are shown in Table 4.

[0075] Table 4. Data table of different reaction conditions and reaction results in Example 4 ※ : In the two-phase system consisting of water and organic solvent, the ratio of water to organic solvent is 1:1.

[0076] Example 5:

[0077] A method for preparing furfural by catalyzing xylan with phenolic hydroxyl functionalized covalent organic framework material

[0078] (1) Prepare ingredients

[0079] During the preparation of phenolic hydroxyl functionalized COF materials, the raw material components were mixed according to the following dosage ratios: 159.60 mg of 4,4-(1,3,5-triazine-2,4,6-triyl)triphenylamine, 94.50 mg of 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde, 9 ml of mesitylene, 9 ml of 1,4-dioxane, and 1.8 ml of acetic acid.

[0080] In the catalytic production process of furfural by phenolic hydroxyl functionalized COF material, the raw material components are mixed according to the following dosage ratio: 1.2 g of D-xylose, 30 ml of solvent, and some COF material.

[0081] (2) Preparation of phenolic hydroxyl functionalized COF materials

[0082] The prepared 4,4-(1,3,5-triazine-2,4,6-triyl)triphenylamine, mesitylene, 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde and 1,4-dioxane were added to a thick-walled pressure-resistant tube in sequence and mixed evenly. According to the solvent thermal method, the reaction was carried out at 120°C for 72 hours. After cooling, the mixture was washed three times with mesitylene, 1,4-dioxane and hot water respectively, and dried for 12 hours to obtain the COF-E material.

[0083] (3) Application of phenolic hydroxyl functionalized COF materials in the preparation of furfural from D-xylose

[0084] The prepared D-xylose, solvent, and COF material were sequentially added to a reactor. The air in the reactor was replaced with nitrogen three to four times, and the stirring rate was set to 500 rpm. The reaction temperature, reaction time, and catalyst dosage are shown in Table 5. After the reaction, the reactor was cooled to room temperature, and the liquid product was collected for qualitative and quantitative analysis. The results are shown in Table 5.

[0085] Table 5. Data table of different reaction conditions and reaction results in Example 5 ※ : In the two-phase system consisting of water and organic solvent, the ratio of water to organic solvent is 1:1.

[0086] As shown in FIG2 , the present invention successfully prepared phenolic hydroxyl functionalized COFs materials.

[0087] Tables 1-5 show that phenolic hydroxyl-functionalized covalent organic frameworks exhibit high catalytic activity in the production of furfural from biomass, particularly in a bidirectional solvent system containing a mixture of water and an organic solvent. Furthermore, the furfural yield initially increases and then decreases with increasing reaction temperature, reaction time, and catalyst dosage. This is because excessive temperatures, prolonged reaction times, and excessive catalyst dosage all lead to the re-decomposition of furfural, forming various byproducts and reducing the yield.

[0088] Example 6:

[0089] This example tests the reusability of the phenolic hydroxyl functionalized COFs materials described in Examples 1 to 5. The COF materials used in catalyzing the production of furfural from biomass in Examples 1 to 5 were filtered and recovered, washed, and then dried in an oven for 12 hours.

[0090] 0.1g of COF material, dried to constant weight, was mixed with 1.2g of D-xylose and 30ml of a water-tetrahydrofuran solution. The mixture was then added to a reactor. The air in the reactor was replaced with nitrogen three to four times. The reaction temperature was set at 200°C, the reaction time was 1h, and the stirring rate was 500rpm. After the reaction was completed, the reactor was cooled to room temperature, and the liquid product was collected for qualitative and quantitative analysis. This process was repeated three times. The results are shown in Table 6.

[0091] Table 6. Data table of different reaction conditions and reaction results in Example 6 ※ : In the two-phase system consisting of water and organic solvent, the ratio of water to organic solvent is 1:1.

[0092] Note: Numbers 1-3 are the reusability experiments of COF-A materials in Example 1; numbers 4-6 are the reusability experiments of COF-B materials in Example 2; numbers 7-9 are the reusability experiments of COF-C materials in Example 3; numbers 10-12 are the reusability experiments of COF-D materials in Example 4; numbers 13-15 are the reusability experiments of COF-E materials in Example 5.

[0093] Table 6 shows that the phenolic hydroxyl-functionalized COFs exhibit excellent recyclability and reusability in the catalytic production of furfural from biomass. After three uses, the xylose degradation rate, furfural yield, and furfural selectivity remained unchanged.

[0094] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing furfural from biomass using phenolic hydroxyl functionalized covalent organic framework materials as catalysts, characterized in that: include: Using aldehyde or / and amino compounds containing phenolic hydroxyl functional groups as monomers, a solvent thermal, microwave or grinding method is used to produce a Schiff base reaction, and then dehydration condensation is performed to prepare phenolic hydroxyl functionalized COFs. The biomass raw material and phenolic hydroxyl functionalized COFs are uniformly mixed in a solvent, and catalytically reacted at 160-210° C. for 0.5-5 hours under an inert atmosphere to obtain furfural.

2. The method for preparing furfural from biomass using phenolic hydroxyl functionalized covalent organic framework materials as claimed in claim 1, characterized in that: The biomass raw materials include but are not limited to xylan, xylose, arabinose, and biomass pre-hydrolyzate.

3. The method for preparing furfural from biomass using phenolic hydroxyl functionalized covalent organic framework materials as claimed in claim 1, characterized in that: The solvent is at least one of water, tetrahydrofuran, toluene and γ-valerolactone.

4. The method for preparing furfural from biomass using phenolic hydroxyl functionalized covalent organic framework materials as claimed in claim 1, characterized in that: The inert atmosphere is selected from one of nitrogen, argon and helium.

5. The method for preparing furfural from biomass using phenolic hydroxyl functionalized covalent organic framework material catalyzed by claim 1, characterized in that: The biomass raw material concentration is 20-40 g / L.

6. The method for preparing furfural from biomass using phenolic hydroxyl functionalized covalent organic framework materials as claimed in claim 1, characterized in that: The amount of the phenolic hydroxyl functionalized COFs is 0.05-0.5 g.

7. The method for preparing furfural from biomass using phenolic hydroxyl functionalized covalent organic framework materials as claimed in claim 1, characterized in that: The volume of the solvent is 30-50 ml.

8. A method for preparing a phenolic hydroxyl functionalized covalent organic framework material, characterized in that: include: With 4,4-(1,3,5-triazine-2,4,6-triyl)triphenylamine and 2,5-dihydroxyterephthalaldehyde as monomers, a solvent thermal, microwave or grinding method was used to produce a Schiff base reaction, and then a dehydration condensation reaction was carried out to prepare phenolic hydroxyl functionalized COFs.

9. Phenolic hydroxyl functionalized COFs prepared by the method of claim 8.

10. Use of the phenolic hydroxyl functionalized COFs according to claim 9 in catalyzing the preparation of furfural from biomass.

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