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

Abstract

The present invention belongs to the fields of biomass catalytic conversion technology and biomass energy chemical technology, and specifically relates to a method for preparing furfural from biomass using a phenolic hydroxyl functionalized covalent organic framework material. The present invention uses a phenolic hydroxyl-containing monomer as a raw material, and synthesizes an imine-functionalized covalent organic framework material (COFs) through dehydration condensation of a Schiff base reaction. The constructed phenolic hydroxyl functionalized COFs have a large specific surface area, rich pore structure, high crystallinity, strong thermal stability, and a large number of acidic sites, and can efficiently catalyze biomass raw materials to prepare furfural. The present invention innovatively applies phenolic hydroxyl functionalized COFs to the reaction of catalyzing biomass to prepare furfural, opening up a new sustainable path for the high-value utilization of renewable biomass resources to produce furfural chemicals; it can catalyze biomass to produce furfural with high selectivity under mild conditions; at the same time, it has high stability, which solves the problems of poor selectivity and difficulty in reusing catalysts in the production process of furfural.

Description

Technical Field

[0001] 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

[0002] The information disclosed in this background technology section is only intended to enhance the 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 a person skilled in the art.

[0003] As a renewable organic resource, biomass has injected new impetus into the sustainable development of modern society. Pretreated biomass can be transformed into platform compounds, which can then be used to derive a variety of value-added chemicals. Among them, furfural is considered to be a multifunctional bio-based C5 platform molecule due to its potential application in biomass energy. The conversion of biomass to furfural mainly includes two steps: hydrolysis and dehydration, and acidic catalysts are the key points affecting the above steps.

[0004] At present, 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 and are easy to recycle and reuse, but usually require external force (such as mechanical stirring) to strengthen the contact with the reactants, and the catalytic performance is lower than that of homogeneous catalysts. Therefore, the development of new heterogeneous catalysts with excellent catalytic performance is the key to achieving rapid development of the furfural industry.

[0005] Covalent organic frameworks (COFs) are the best choice to meet the above requirements. COFs are a class of crystalline nanomaterials that can integrate organic units into well-defined two-dimensional and three-dimensional polymers and are highly designable. However, there is currently no research in the industry that uses covalent organic frameworks to catalyze the highly selective production of furfural from biomass under mild conditions. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a method for preparing furfural from biomass by catalyzing phenolic hydroxyl functionalized covalent organic framework materials. Specifically, biomass raw materials, phenolic hydroxyl functionalized COFs materials and solvents are sequentially added to a reactor, inert gas is filled in, and the reaction is carried out at a certain temperature to prepare furfural with high selectivity.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] 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:

[0009] Using aldehyde or / and amine 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;

[0010] 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.

[0011] The present invention proposes a method for preparing furfural from biomass using a phenolic hydroxyl functionalized covalent organic framework material as catalyst. The rich pore structure of the covalent organic framework provides sufficient diffusion space for the preparation of furfural. The phenolic hydroxyl functionalized COFs of the present invention have a large number of evenly distributed acid sites, and can catalyze the production of furfural from biomass with high selectivity under mild conditions. The present invention opens up a new path for the efficient production of biomass energy, and solves the problems of poor selectivity and difficulty in reusing catalysts in the production of furfural.

[0012] The second aspect of the present invention provides a method for preparing a phenolic hydroxyl functionalized covalent organic framework material, comprising:

[0013] 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.

[0014] The third aspect of the present invention provides the use of the above-mentioned phenolic hydroxyl functionalized COFs in catalyzing the preparation of furfural from biomass.

[0015] Beneficial effects of the present invention

[0016] (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.

[0017] (2) The present invention uses phenolic hydroxyl-containing monomers as raw materials to synthesize COFs, which have a large number of evenly distributed acid sites and can catalyze biomass to produce furfural with high selectivity under mild conditions.

[0018] (3) The COFs prepared by the present invention have high stability, can be reused multiple times and have stable performance.

[0019] (4) The preparation method of the present invention is simple, practical and easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and 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.

[0021] Figure 1 It is the process route diagram of the present invention.

[0022] Figure 2 Infrared and XRD spectra of COFs prepared in the examples of the present invention. DETAILED DESCRIPTION

[0023] It should be noted that the following detailed descriptions are exemplary and are 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.

[0024] A method for preparing furfural from biomass using a phenolic hydroxyl functionalized covalent organic framework material as catalyst, comprising:

[0025] Using aldehyde or / and amine 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;

[0026] 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.

[0027] In some embodiments, the biomass raw materials include but are not limited to xylan, xylose, arabinose, and biomass pre-hydrolyzate.

[0028] In some embodiments, the solvent is at least one of water, tetrahydrofuran, toluene, and γ-valerolactone.

[0029] In some embodiments, the inert atmosphere is selected from nitrogen, argon, and helium.

[0030] In some embodiments, the biomass feedstock concentration is 20-40 g / L.

[0031] In some embodiments, the phenolic hydroxyl functionalized COFs are used in an amount of 0.05-0.5 g.

[0032] In some embodiments, the solvent volume is 30-50 ml.

[0033] The present invention will be further described in detail below in conjunction with specific embodiments. It should be noted that the specific embodiments are intended to explain the present invention rather than to limit it.

[0034] Embodiment 1:

[0035] A method for preparing furfural by catalyzing D-xylose with phenolic hydroxyl functionalized covalent organic framework material

[0036] (1) Preparation

[0037] 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.

[0038] In the catalytic production process of furfural by phenolic hydroxyl functionalized COF material, each raw material component is mixed according to the following dosage ratio: 1.2 g of D-xylose, 30 ml of solvent, and some COF material.

[0039] (2) Preparation of phenolic hydroxyl functionalized COF materials

[0040] 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 the thick-walled pressure-resistant tube in sequence and mixed evenly. According to the solvent thermal method, the mixture was reacted at 120°C for 72 hours. After cooling, the mixture was washed three times with n-butanol, o-dichlorobenzene and hot water respectively. After drying for 12 hours, the COF-A material was obtained.

[0041] (3) Application of phenolic hydroxyl functionalized COF materials in the preparation of furfural from D-xylose

[0042] The prepared D-xylose, solvent and COF material were added to the reactor in sequence, the air in the reactor was replaced with nitrogen 3-4 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 was completed, the reactor was cooled to room temperature, the liquid product was collected, and the product was qualitatively and quantitatively analyzed. The results are shown in Table 1.

[0043] Table 1. Data table of different reaction conditions and reaction results in Example 1

[0044]

[0045]

[0046] ※ : In the two-phase system consisting of water and organic solvent, the ratio of water to organic solvent is 1:1.

[0047] Embodiment 2:

[0048] A method for preparing furfural by catalyzing xylan with phenolic hydroxyl functionalized covalent organic framework material

[0049] (1) Preparation

[0050] 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.

[0051] In the catalytic production process of furfural by phenolic hydroxyl functionalized COF material, each raw material component is mixed according to the following dosage ratio: 1.2g xylan, 30ml solvent, and some COF material.

[0052] (2) Preparation of phenolic hydroxyl functionalized COF materials

[0053] 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 the thick-walled pressure-resistant tube in sequence and mixed evenly. According to the solvent thermal 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. After drying for 12 hours, the COF-B material was obtained.

[0054] (3) Application of phenolic hydroxyl functionalized COF materials in the preparation of furfural from xylan

[0055] The prepared xylan, solvent and COF material were added to the reactor in sequence, the air in the reactor was replaced with argon for 3-4 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 was completed, the reactor was cooled to room temperature, the liquid product was collected, and the product was qualitatively and quantitatively analyzed. The results are shown in Table 2.

[0056] Table 2. Data table of different reaction conditions and reaction results in Example 2

[0057]

[0058]

[0059] ※ : In the two-phase system consisting of water and organic solvent, the ratio of water to organic solvent is 1:1.

[0060] Embodiment 3:

[0061] A method for preparing furfural by catalyzing arabinose with phenolic hydroxyl functionalized covalent organic framework material

[0062] (1) Preparation

[0063] 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.

[0064] In the catalytic production process of furfural by phenolic hydroxyl functionalized COF material, each raw material component is mixed according to the following dosage ratio: 1.2 g arabinose, 30 ml solvent, and some COF material.

[0065] (2) Preparation of phenolic hydroxyl functionalized COF materials

[0066] 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 evenly and left for 30 minutes. Then, methanol Soxhlet extraction was used for 12 hours, and after cooling, the mixture was washed three times with mesitylene, 1,4-dioxane and hot water, and dried for 12 hours to obtain the COF-C material.

[0067] (3) Application of phenolic hydroxyl functionalized COF materials to catalyze the preparation of furfural from arabinose

[0068] The prepared arabinose, solvent and COF material were added to the reactor in sequence, the air in the reactor was replaced with helium 3-4 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 was completed, the reactor was cooled to room temperature, the liquid product was collected, and the product was qualitatively and quantitatively analyzed. The results are shown in Table 3.

[0069] Table 3. Data table of different reaction conditions and reaction results in Example 3

[0070]

[0071]

[0072] ※ : In the two-phase system consisting of water and organic solvent, the ratio of water to organic solvent is 1:1.

[0073] Embodiment 4:

[0074] A method for preparing furfural by catalyzing xylan with phenolic hydroxyl functionalized covalent organic framework material

[0075] (1) Preparation

[0076] 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.

[0077] In the catalytic production process of furfural by phenolic hydroxyl functionalized COF material, each raw material component is mixed according to the following dosage ratio: 1.2 g of D-xylose, 30 ml of solvent, and some COF material.

[0078] (2) Preparation of phenolic hydroxyl functionalized COF materials

[0079] The prepared 4,4-(1,3,5-triazine-2,4,6-triyl)triphenylamine, mesitylene, 2-hydroxy-1,3,5-benzenetricarboxaldehyde and 1,4-dioxane are sequentially added to a thick-walled pressure-resistant tube and mixed evenly. The mixture is reacted at 120°C for 72 hours according to the solvent thermal method. After cooling, the mixture is washed three times with mesitylene, 1,4-dioxane and hot water respectively. After drying for 12 hours, the COF-D material is obtained.

[0080] (3) Application of phenolic hydroxyl functionalized COF materials in the preparation of furfural from D-xylose

[0081] The prepared D-xylose, solvent and COF material were added to the reactor in sequence, the air in the reactor was replaced with nitrogen 3-4 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 was completed, the reactor was cooled to room temperature, the liquid product was collected, and the product was qualitatively and quantitatively analyzed. The results are shown in Table 4.

[0082] Table 4. Data table of different reaction conditions and reaction results in Example 4

[0083]

[0084]

[0085] ※ : In the two-phase system consisting of water and organic solvent, the ratio of water to organic solvent is 1:1.

[0086] Embodiment 5:

[0087] A method for preparing furfural by catalyzing xylan with phenolic hydroxyl functionalized covalent organic framework material

[0088] (1) Preparation

[0089] 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.

[0090] In the catalytic production process of furfural by phenolic hydroxyl functionalized COF material, each raw material component is mixed according to the following dosage ratio: 1.2 g of D-xylose, 30 ml of solvent, and some COF material.

[0091] (2) Preparation of phenolic hydroxyl functionalized COF materials

[0092] 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 are sequentially added to a thick-walled pressure-resistant tube and mixed evenly. The mixture is reacted at 120°C for 72 hours according to the solvent thermal method. After cooling, the mixture is washed three times with mesitylene, 1,4-dioxane and hot water respectively. The COF-E material is obtained after drying for 12 hours.

[0093] (3) Application of phenolic hydroxyl functionalized COF materials in the preparation of furfural from D-xylose

[0094] The prepared D-xylose, solvent and COF material were added to the reactor in sequence, the air in the reactor was replaced with nitrogen 3-4 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 was completed, the reactor was cooled to room temperature, the liquid product was collected, and the product was qualitatively and quantitatively analyzed. The results are shown in Table 5.

[0095] Table 5. Data table of different reaction conditions and reaction results in Example 5

[0096]

[0097]

[0098] ※ : In the two-phase system consisting of water and organic solvent, the ratio of water to organic solvent is 1:1.

[0099] Depend on Figure 2 It can be seen that the present invention successfully prepared phenolic hydroxyl functionalized COFs materials.

[0100] It can be seen from Tables 1-5 that the phenolic hydroxyl functionalized covalent organic framework material exhibits high catalytic activity in the process of catalyzing the preparation of furfural from biomass, especially in a bidirectional solvent system of water and organic solvent. In addition, the furfural yield shows a trend of first increasing and then decreasing with the increase of reaction temperature, reaction time, and catalyst dosage. This is because too high temperature, too long time, and too much dosage will lead to the re-decomposition of furfural, forming a variety of by-products, and reducing the furfural yield.

[0101] Embodiment 6:

[0102] This example tests the reusability of the phenolic hydroxyl functionalized COFs materials described in Examples 1 to 5. The COF materials involved 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.

[0103] 0.1g COF material dried to constant weight was mixed with 1.2g D-xylose and 30ml water-tetrahydrofuran solution, and added to the reactor. The air in the reactor was replaced with nitrogen 3-4 times. The reaction temperature was set to 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, the liquid product was collected, and the product was qualitatively and quantitatively analyzed. The above process was carried out 3 times respectively. The results are shown in Table 6.

[0104] Table 6. Data table of different reaction conditions and reaction results in Example 6

[0105]

[0106]

[0107]

[0108] ※ : In the two-phase system consisting of water and organic solvent, the ratio of water to organic solvent is 1:1.

[0109] Note: No. 1-3 is the reusability experiment of COF-A material in Example 1; No. 4-6 is the reusability experiment of COF-B material in Example 2; No. 7-9 is the reusability experiment of COF-C material in Example 3; No. 10-12 is the reusability experiment of COF-D material in Example 4; No. 13-15 is the reusability experiment of COF-E material in Example 5.

[0110] It can be seen from Table 6 that the phenolic hydroxyl functionalized COFs material exhibits excellent recyclability and reusability in the process of catalyzing the preparation of furfural from biomass. After three uses, the xylose degradation rate, furfural yield, and furfural selectivity did not change significantly.

[0111] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope 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: Phenolic hydroxyl functionalized COFs were prepared by using 4,4-(1,3,5-triazine-2,4,6-triyl)triphenylamine and 2,5-dihydroxyterephthalaldehyde / 2-hydroxy-1,3,5-benzenetricarboxaldehyde / 2,4,6-trihydroxybenzene-1,3,5-tricarboxaldehyde as monomers and undergoing a Schiff base reaction by solvent thermal, microwave or grinding methods, followed by dehydration condensation. The biomass raw material and phenolic hydroxyl functionalized COFs are uniformly mixed in a two-phase system solvent with a composition ratio of 1:1 between water and tetrahydrofuran / toluene / γ-valerolactone, and catalytically reacted at 160-210°C for 0.5-5h under an inert atmosphere to obtain furfural; The amount of the phenolic hydroxyl functionalized COFs is 0.05-0.5 g.

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 inert atmosphere is selected from one of nitrogen, argon and helium.

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 biomass raw material concentration is 20-40 g / L.

5. The method for preparing furfural from biomass using phenolic hydroxyl functionalized covalent organic framework material catalyzed by claim 1, characterized in that: The volume of the solvent is 30-50 ml.

6. Use of phenolic hydroxyl functionalized COFs prepared by the method according to claim 1 in catalyzing the production of furfural from biomass.

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