A method for producing high-purity 2,5-frangimethanol by catalytically reacting furfuryl alcohol with an aprotic acid catalyst.

Abstract

This invention discloses a method for producing high-purity 2,5-frangimethanol by catalytically reacting furfuryl alcohol using an aprotic acid catalyst, and belongs to the field of furyl group biomass chemicals and materials. In this method, a modified zeolite catalyst, furfuryl alcohol, and a hydroxymethylating reagent are added to an aprotic solvent, nitrogen gas is introduced to carry out the reaction, and after the reaction is complete, the solid and liquid phases are separated by filtration, the liquid phase is rotated and evaporated to recover the solvent, and then the temperature is raised to recover the solid, which is high-purity 2,5-frangimethanol. Here, the modified zeolite catalyst is obtained by dealuminizing β-zeolite and then introducing a transition metal element as a Lewis acid active site into the β-zeolite by solid-solid ion exchange. The modified zeolite of this invention, as an aprotic acid catalyst, can achieve high selectivity for the target product, unlike the problems of reduced selectivity and separation of the target product caused by side reactions with protic acid catalysts. The synthesis process and separation and purification process are simple, the raw material cost is low, and it is in line with the development of green chemistry.

Description

Technical Field

[0001] The present invention belongs to the field of biomass chemicals and materials having a furan skeleton, and particularly relates to a method for catalytically reacting furfuryl alcohol using a non-protic acid catalyst to produce high-purity 2,5-furandimethanol.

Background Art

[0002] 2,5-Furandimethanol (BHMF) is an aromatic furan diol mainly derived from 5-hydroxymethylfurfural (HMF), and is an important monomer for synthesizing aromatic polyester materials to replace petroleum-based diols. BHMF is widely used in the synthesis of ethers, polymers, resins and adhesives. Currently, the main factor restricting the application of BHMF is the high cost of HMF. The industrial production of HMF mainly relies on the dehydration of fructose by inorganic acid catalysts, but the process using cheaper glucose as a raw material is still in the research stage. Furthermore, in the reduction and derivatization processes of HMF, high selectivity for C=O bonds and C=C bonds is required, which poses a major challenge to the catalyst and the catalytic process. In contrast, the furfural industry has already established a scale advantage, and more than 65% of its production capacity is used for manufacturing applications related to furfuryl alcohol. This means that directly producing BHMF by hydroxymethylation of furfuryl alcohol is a highly cost-effective strategy.

[0003] The earliest methods for producing BHMF from furfuryl alcohol can be traced back to Laszlo-Hedwig et al. (Polymer Science USSR, 1983, 25:228-236). By mimicking the acidic polymerization process of phenolic resins, they converted furfuryl alcohol to BHMF using formaldehyde as a hydroxymethylating agent in an acidic environment. However, compared to hydroxymethylation of phenol, highly active furfuryl alcohol undergoes vigorous self-polymerization in acidic environments, especially aqueous environments, resulting in relatively low selectivity for BHMF. Furthermore, in strongly acidic environments, side reactions caused by ring-opening of the furan structure are another significant reason for the relatively low selectivity of BHMF. To address these issues, researchers have conducted the following related studies: Highly silica hydrophobic mordenite can replace inorganic acids, achieving high selectivity for BHMF at low FAl concentrations. Paraformaldehyde can replace formaldehyde solution, mitigating the problem of side reactions caused by the introduction of formaldehyde into the aqueous phase. The hydroxymethylation reaction is carried out after protecting the active hydroxyl group of furfuryl alcohol, reducing the associated side reactions. Nevertheless, problems still need to be solved. These include the high reaction energy barrier of the CH bond on the aromatic ring, the problem of self-polymerization after protonation of free formaldehyde, and subsequent separation problems due to product selectivity and by-products such as humic acid.

[0004] Therefore, there is an urgent need to provide a method for producing high-purity BHMF that is highly selective, easy to separate, reduces side reactions, and has a simple process. [Overview of the project]

[0005] In view of the aforementioned problems in the prior art, the technical problem that the present invention aims to solve is to provide a method for producing high-purity 2,5-frangimethanol by catalytically reacting furfuryl alcohol using an aprotic acid catalyst. This method is used to solve problems that currently exist in the production of 2,5-frangimethanol, such as severe side reactions, low selectivity, complex separation, and high costs.

[0006] To solve the above problems, the technical solutions adopted by the present invention are as follows. A method for producing high-purity 2,5-frangimethanol by catalytically reacting furfuryl alcohol with an aprotic acid catalyst is provided, in which a modified zeolite catalyst, furfuryl alcohol, and a hydroxymethylating reagent are added to an aprotic solvent, and the reaction is carried out by introducing nitrogen gas. After the reaction is complete, the solid and liquid phases are separated by filtration, the liquid phase is rotated and evaporated to recover the solvent, and then the temperature is raised to recover the solid. This solid is high-purity 2,5-frangimethanol. The modified zeolite catalyst is obtained by dealuminizing β-zeolite with concentrated nitric acid, and then introducing a transition metal element into the β-zeolite by solid-solid ion exchange.

[0007] Furthermore, the transition metal element is one or more of manganese, cobalt, and tin.

[0008] Furthermore, the transition metal is manganese.

[0009] Furthermore, the hydroxymethylation reagent is a mixture of one or more of the following: formaldehyde, trioxane, and paraformaldehyde.

[0010] Furthermore, the aprotic solvent is a mixture of one or more of tetrahydrofuran, 1,4-dioxane, and methyl acetate.

[0011] Furthermore, the molar ratio of furfuryl alcohol to the hydroxymethylating agent is 1:1 to 9.

[0012] Furthermore, the amount of furfuryl alcohol added is 1-10% of the volume of the aprotic solvent, and the amount of modified zeolite catalyst added is 1-20% of the total solvent mass.

[0013] Furthermore, the reaction temperature is 80-140°C, and the reaction time is 1-12 hours.

[0014] Furthermore, the specific steps are as follows: 1) β-zeolite is placed in concentrated nitric acid and dealuminized for 8 hours at a boiling state, then washed with water to neutralize, dried, and then exogenous ions, i.e., transition metal elements, are added by mechanical grinding. After high-temperature calcination and cooling, a modified zeolite catalyst is finally obtained. Here, the molar ratio of SiO2 to Al2O3 in the β-zeolite is 30:1. 2) Add furfuryl alcohol and the hydroxymethylating reagent to the aprotic solvent in a molar ratio of 1:1 to 9, and simultaneously add 1 to 20% of the total solvent mass of catalyst. Use nitrogen gas as a protective gas and react for 1 to 12 hours under conditions of 80 to 140°C. Here, the amount of furfuryl alcohol added is 1 to 10% of the volume of the aprotic solvent. 3) After the reaction is complete, the solid and liquid in the reaction system are separated by filtration. Here, the solid, i.e., the catalyst, is washed with a washing solution, dried, and then regenerated. The liquid is separated from the solvent by rotary evaporation under conditions of 40-80°C, and the temperature is further raised to 100°C to remove trace amounts of furfuryl alcohol substrate. The recovered solid is high-purity 2,5-frangimethanol. Furthermore, in step 3), the washing solution is a mixture of one or more of methanol, ethanol, and acetone.

[0015] Figure 1 shows a schematic diagram illustrating the conversion of the furfuryl alcohol of the present invention to high-purity 2,5-frangimethanol in the presence of an aprotic acid catalyst.

[0016] Beneficial effects: Compared to the prior art, the advantages of the present invention are as follows: (1) The catalyst used in the present invention is an aprotic acid catalyst, which is characterized by completing the hydroxymethylation process depending on the Lewis acid active site and reducing side reactions related to protic acids. (2) Different from the catalytic pathway of the present invention, where a protic acid forms a hydroxymethyl cation and then randomly attacks furfuryl alcohol to complete hydroxymethylation, the aprotic acid catalyst of the present invention promotes the generation of hydroxymethyl cations while assisting in anchoring furfuryl alcohol to the reaction position, thereby achieving the completion of the hydroxymethylation reaction objective and reducing side reactions related to electrophilic reagents. (3) In the present invention, since there are few by-products and the selectivity for BHMF is high, the reaction solution and the catalyst can be recovered by simple distillation, simplifying the product separation and reagent recovery process. (4) The synthesis process and separation and purification process of the present invention are simple, the catalyst can be recovered and reused, reducing raw material costs, and conforming to the development concept of green chemistry.

Brief Description of the Drawings

[0017] [Figure 1] It is a schematic diagram of the conversion of furfuryl alcohol of the present invention to high-purity 2,5-furandimethanol in the presence of an aprotic acid catalyst. [Figure 2] It is a gas chromatograph-mass spectrometry chromatogram of the reaction solution prepared in the present invention. [Figure 3] It is a mass spectrum corresponding to the BHMF product peak in FIG. 1 of the present invention. [Figure 4] It is a gas chromatograph-mass spectrometry chromatogram of the product prepared in Comparative Example 1 of the present invention.

Modes for Carrying Out the Invention

[0018] Hereinafter, the present invention will be further described with specific examples.

[0019] The selectivity, yield, and purity of BHMF produced in the following examples are calculated according to the following formulas. Selectivity (S BHMF ) of BHMF is calculated as follows. JPEG2026517922000002.jpg15170Here, m0 is the mass of the furfuryl alcohol substrate, m1 is the mass of the remaining furfuryl alcohol substrate, m3 is the mass of BHMF with chromatographic purity, and M フルフリルアルコール is the molar mass of furfuryl alcohol, and M BHMF is the molar mass of BHMF.

[0020] Yield (Y BHMF ) of BHMF is calculated as follows. JPEG2026517922000003.jpg13170Here, m2 is the mass of the absolutely dry product, m0 is the mass of the furfuryl alcohol substrate, and M フルフリルアルコール is the molar mass of furfuryl alcohol, and M BHMF is the molar mass of BHMF.

[0021] Purity (P BHMF ) of BHMF is calculated as follows. JPEG2026517922000004.jpg12170Here, m3 is the mass of BHMF measured by chromatography, and m2 is the mass of the absolutely dry product.

[0022] The purity of BHMF prepared in the following examples was determined by adopting chromatographic purity and tested according to the following procedure. 0.1 g (on an oven-dry basis) of the product was placed in a beaker, dissolved in an appropriate amount of tetrahydrofuran, and then cooled to room temperature to a final volume of 100 mL. After filtration through a 0.22 μm organic syringe filter, the sample was used to measure the BHMF concentration. Analysis was performed using a gas chromatograph (Shimadzu, GC-2010 Plus) equipped with a highly polar column (DB-WAXetr). Chromatographically pure n-dodecane was used as the internal standard, and the test conditions were as follows: The temperature range was 40 to 280°C, with a heating rate of 5°C / min from 40 to 150°C and 2°C / min from 150 to 280°C. The accurate BHMF content in the product was determined from the internal standard and a prepared BHMF standard curve, and the chromatographic purity of the sample was obtained by further calculation.

[0023] The formaldehyde (37 wt% aqueous solution), trioxane (AR), paraformaldehyde (95%), tetrahydrofuran (AR), 1,4-dioxane (99.5%), and methyl acetate (99%) used in the following examples were all purchased from Shanghai Maclin.

[0024] Example 1 1. Preparation of modified zeolite catalyst β-zeolite (molar ratio of SiO2 to Al2O3:30:1) was placed in concentrated nitric acid (mass fraction 68%) and dealuminized at a boiling point for 8 hours. After washing with water to neutralize and drying at 105°C, the dealuminized aluminum element molar equivalent of cobalt nitrate was added and the mixture was mechanically pulverized. The mixture was then placed in a tubular furnace and treated at 600°C under nitrogen protection for 4 hours, followed by heating in a muffle furnace at 600°C for 4 hours. The product after cooling is the prepared modified zeolite catalyst.

[0025] 2. Manufacturing of BHMF Furfuryl alcohol and a formaldehyde solution (in molar equivalents of formaldehyde monomer) were added to tetrahydrofuran in a molar ratio of 1:3. Here, furfuryl alcohol comprised 2% of the volume of tetrahydrofuran, and a modified zeolite catalyst equivalent to 5% of the total solvent mass was added simultaneously. The air in the apparatus was removed using nitrogen gas, and the reaction was stirred at 100°C for 4 hours. After the reaction was complete, the solid and liquid phases were separated using a filtration device. The solid was washed three times consecutively with ethanol, and then dried to recover the catalyst. The drying temperature was 105°C. The liquid was collected at 60°C using a rotary evaporator to recover the solvent, and then heated to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals were recovered. The recovered solid is BHMF.

[0026] Example 2 BHMF Manufacturing Furfuryl alcohol and a formaldehyde solution (in molar equivalents of formaldehyde monomer) were added to tetrahydrofuran in a molar ratio of 1:9. Here, furfuryl alcohol comprised 5% of the volume of tetrahydrofuran, and at the same time, a modified zeolite catalyst (modified zeolite catalyst prepared by the method of Example 1) equivalent to 10% of the total solvent mass was added. The air in the apparatus was removed using nitrogen gas, and the reaction was stirred at 80°C for 8 hours. After the reaction was complete, the solid and liquid phases were separated using a filtration device. The solid was washed three times consecutively with ethanol, and then dried to recover the catalyst. The drying temperature was 105°C. The liquid was collected at 60°C using a rotary evaporator to recover the solvent, and then heated to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals were recovered. The recovered solid is BHMF.

[0027] Example 3 BHMF Manufacturing Furfuryl alcohol and trioxane (in molar equivalents of formaldehyde monomer) were added to tetrahydrofuran in a molar ratio of 1:9. Here, furfuryl alcohol comprised 5% of the volume of tetrahydrofuran, and at the same time, a modified zeolite catalyst (modified zeolite catalyst prepared by the method of Example 1) equivalent to 10% of the total solvent mass was added. The air in the apparatus was removed using nitrogen gas, and the reaction was stirred at 100°C for 4 hours. After the reaction was complete, the solid and liquid phases were separated using a filtration device. The solid was washed three times consecutively with acetone, and then dried to recover the catalyst. The drying temperature was 105°C. The liquid was collected at 60°C using a rotary evaporator to recover the solvent, and then heated to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals were recovered. The recovered solid is BHMF.

[0028] Example 4 BHMF Manufacturing Furfuryl alcohol and paraformaldehyde (in molar equivalents of formaldehyde monomer) were added to methyl acetate in a molar ratio of 1:3. Here, furfuryl alcohol was 5% of the volume of tetrahydrofuran, and at the same time, a modified zeolite catalyst (modified zeolite catalyst prepared by the method of Example 1) equivalent to 10% of the total solvent mass was added. The air in the apparatus was removed using nitrogen gas, and the reaction was stirred at 100°C for 8 hours. After the reaction was complete, the solid and liquid phases were separated using a filtration device. The solid was washed three times consecutively with methanol, and then dried to recover the catalyst. The drying temperature was 105°C. The liquid was collected at 60°C using a rotary evaporator to recover the solvent, and then heated to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals were recovered. The recovered solid is BHMF.

[0029] Example 5 1. Preparation of modified zeolite catalyst β-zeolite (molar ratio of SiO2 to Al2O3:30:1) was placed in concentrated nitric acid (mass fraction 68%) and dealuminized at a boiling point for 8 hours. After washing with water to neutralize and drying at 105°C, manganese nitrate equivalent to the removed aluminum element was added and the mixture was mechanically pulverized. The mixture was then placed in a muffle furnace and kept at 600°C for 4 hours. The product after cooling is the prepared modified zeolite catalyst.

[0030] 2. Manufacturing of BHMF Furfuryl alcohol and paraformaldehyde (in molar equivalents of formaldehyde monomer) were added to methyl acetate in a molar ratio of 1:9. Here, furfuryl alcohol was 5% of the volume of tetrahydrofuran, and a modified zeolite catalyst equivalent to 10% of the total solvent mass was added simultaneously. The air in the apparatus was removed using nitrogen gas, and the reaction was stirred at 120°C for 8 hours. After the reaction was complete, the solid and liquid phases were separated using a filtration device. The solid was washed three times consecutively with ethanol, and then dried to recover the catalyst. The drying temperature was 105°C. The liquid was collected at 60°C using a rotary evaporator to recover the solvent, and then heated to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals were recovered. The recovered solid is BHMF.

[0031] Example 6 BHMF Manufacturing Furfuryl alcohol and paraformaldehyde (in molar equivalents of formaldehyde monomer) were added to methyl acetate in a molar ratio of 1:6. Here, furfuryl alcohol was 10% of the volume of tetrahydrofuran, and at the same time, a modified zeolite catalyst (modified zeolite catalyst prepared by the method of Example 5) equivalent to 20% of the total solvent mass was added. The air in the apparatus was removed using nitrogen gas, and the reaction was stirred at 120°C for 8 hours. After the reaction was complete, the solid and liquid phases were separated using a filtration device. The solid was washed three times consecutively with ethanol, and then dried to recover the catalyst. The drying temperature was 105°C. The liquid was collected at 60°C using a rotary evaporator to recover the solvent, and then heated to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals were recovered. The recovered solid is BHMF.

[0032] Example 7 BHMF Manufacturing Furfuryl alcohol and paraformaldehyde (in molar equivalents of formaldehyde monomer) were added to 1,4-dioxane in a molar ratio of 1:9. Here, furfuryl alcohol was 1% of the volume of tetrahydrofuran, and at the same time, a modified zeolite catalyst (modified zeolite catalyst prepared by the method of Example 5) equivalent to 5% of the total solvent mass was added, and the reaction was stirred at 110°C for 4 hours. After the reaction was complete, the solid and liquid phases were separated using a filtration device. The solid was washed three times consecutively with ethanol, and then dried to recover the catalyst. The drying temperature was 105°C. The liquid was collected at 60°C using a rotary evaporator to recover the solvent, and then heated to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals were recovered. The recovered solid is BHMF.

[0033] Example 8 1. Preparation of modified zeolite catalyst β-zeolite (molar ratio of SiO2 to Al2O3:30:1) was placed in concentrated nitric acid (mass fraction 68%) and dealuminized at a boiling point for 8 hours. After washing with water to neutralize and drying at 105°C, manganese nitrate equivalent to the removed aluminum element was added and the mixture was mechanically pulverized. Subsequently, it was placed in a tubular furnace and treated at 600°C under nitrogen protection for 4 hours, and then transferred to a muffle furnace and kept warm at 600°C for 4 hours. The product after cooling is the prepared modified zeolite catalyst.

[0034] 2. Manufacturing of BHMF Furfuryl alcohol and paraformaldehyde (in molar equivalents of formaldehyde monomer) were added to 1,4-dioxane in a molar ratio of 1:9. Here, furfuryl alcohol was 1% of the volume of tetrahydrofuran, and a modified zeolite catalyst equivalent to 5% of the total solvent mass was added simultaneously. The air in the apparatus was removed using nitrogen gas, and the reaction was stirred at 110°C for 12 hours. After the reaction was complete, the solid and liquid phases were separated using a filtration device. The solid was washed three times consecutively with ethanol, and then dried to recover the catalyst. The drying temperature was 105°C. The liquid was collected at 80°C using a rotary evaporator to recover the solvent, and then heated to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals were recovered. The recovered solid is BHMF.

[0035] Example 9 1. Preparation of modified zeolite catalyst β-zeolite (molar ratio of SiO2 to Al2O3:30:1) was placed in concentrated nitric acid (mass fraction 68%) and dealuminized at a boiling point for 8 hours. After washing with water to neutralize and drying at 105°C, the dealuminized aluminum element molar equivalent of tin nitrate was added and the mixture was mechanically pulverized. Subsequently, it was placed in a tubular furnace and treated at 600°C under nitrogen protection for 4 hours, and then transferred to a muffle furnace and kept warm at 600°C for 4 hours. The product after cooling is the prepared modified zeolite catalyst.

[0036] 2. Manufacturing of BHMF Furfuryl alcohol and paraformaldehyde (in molar equivalents of formaldehyde monomer) were added to 1,4-dioxane in a molar ratio of 1:9. Here, furfuryl alcohol was 1% of the volume of tetrahydrofuran, and a modified zeolite catalyst equivalent to 5% of the total solvent mass was added simultaneously. The air in the apparatus was removed using nitrogen gas, and the reaction was stirred at 80°C for 12 hours. After the reaction was complete, the solid and liquid phases were separated using a filtration device. The solid was washed three times consecutively with acetone, and then dried to recover the catalyst. The drying temperature was 105°C. The liquid was collected at 60°C using a rotary evaporator to recover the solvent, and then heated to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals were recovered. The recovered solid is BHMF.

[0037] Comparative Example 1 Furfuryl alcohol and paraformaldehyde (in molar equivalents of formaldehyde monomer) were added to 1,4-dioxane in a molar ratio of 1:9. Here, furfuryl alcohol was 5% of the volume of tetrahydrofuran, and acetic acid equivalent to 5% of the total solvent volume was added as a catalyst. The air in the apparatus was removed using nitrogen gas, and the reaction was stirred at 110°C for 6 hours. After the reaction was complete, the solvent and acetic acid were recovered at 80°C using a rotary evaporator, and the temperature was further raised to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals were recovered. The recovered solid is BHMF.

[0038] Comparative Example 2 Furfuryl alcohol and paraformaldehyde (in molar equivalents of formaldehyde monomer) were added to 1,4-dioxane in a molar ratio of 1:9. Here, furfuryl alcohol constituted 1% of the volume of tetrahydrofuran, and simultaneously, unmodified β-zeolite catalyst (molar ratio of SiO2 to Al2O3 was 30:1), equivalent to 20% of the total solvent mass, was added. The air in the apparatus was removed using nitrogen gas, and the reaction was stirred at 110°C for 6 hours. After the reaction was complete, the mixture was filtered. The solid was washed three times consecutively with acetone, and then dried to recover the catalyst. The drying temperature was 105°C. The liquid was collected at 60°C using a rotary evaporator, and the solvent was recovered. The temperature was then raised to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals were recovered. The recovered solid is BHMF.

[0039] Comparative Example 3 Furfuryl alcohol and paraformaldehyde (in molar equivalents of formaldehyde monomer) were added to 1,4-dioxane in a molar ratio of 1:9. Here, furfuryl alcohol constituted 1% of the volume of tetrahydrofuran, and at the same time, a zeolite catalyst (H-ZSM-5, with a molar ratio of SiO2 to Al2O3 of 18:1) equivalent to 20% of the total solvent mass was added. The air in the apparatus was removed using nitrogen gas, and the reaction was stirred at 110°C for 6 hours. After the reaction was complete, the mixture was filtered. The solid was washed three times consecutively with acetone, and then dried to recover the catalyst. The drying temperature was 105°C. The liquid was collected at 60°C using a rotary evaporator, and the solvent was recovered. The temperature was then raised to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals were recovered. The recovered solid is BHMF.

[0040] Comparative Example 4 Furfuryl alcohol and paraformaldehyde (in molar equivalents of formaldehyde monomer) were added to 1,4-dioxane in a molar ratio of 1:9. Here, furfuryl alcohol constituted 1% of the volume of tetrahydrofuran, and at the same time, a zeolite catalyst (H-SAPO-11, with a molar ratio of SiO2, Al2O3, and P2O5 of 0.63:1:0.82) equivalent to 20% of the total solvent mass was added. The air in the apparatus was removed using nitrogen gas, and the reaction was stirred at 110°C for 6 hours. After the reaction was complete, the mixture was filtered. The solid was washed three times consecutively with acetone, and then dried to recover the catalyst. The drying temperature was 105°C. The liquid was collected at 60°C using a rotary evaporator, and the solvent was recovered. The temperature was then raised to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals were recovered. The recovered solid is BHMF.

[0041] The yield and product conversion rate of the BHMF products produced in Examples 1-9 and Comparative Examples 1-4 of the present invention are shown in Table 1 below.

[0042] Table 1: Yield and product conversion rate of BHMF products produced in Examples 1-9 and Comparative Examples 1-4 JPEG2026517922000005.jpg101170

[0043] Table 1 shows the yield and conversion rate of BHMF products produced in Examples 1-9 and Comparative Examples 1-4. As is clear from the table, the temperature and time of the catalytic reaction affect the progress and selectivity of the hydroxymethylation reaction. Generally, increasing the substrate concentration is detrimental to improving reaction selectivity, but increasing the amount of catalyst used can accelerate the reaction. Compared with protonic acid catalysts such as Comparative Example 1, BHMF produced with aprotic acid catalysts has higher purity and is also more advantageous for catalyst recovery, thus guaranteeing the purity of the target product and the efficiency of separation and recovery. In addition, the silicon-aluminum ratio affects the amount of ion exchange, and the higher the silicon-aluminum ratio, the relatively fewer the active sites. However, since catalysts are usually used in excess during the process, there is no clear difference in catalytic performance in practice. Among zeolite catalysts modified with different single metals, the zeolite catalyst modified with metallic manganese shows the best effect. In Comparative Examples 1-4, although the conversion rate of furfuryl alcohol was high, the yield and purity of BHMF were low, and none of them met the requirements for use.

[0044] Figure 2 shows the gas chromatograph-mass spectrometry chromatogram of the reaction solution prepared according to the present invention. As is clear from the figure, solvent peaks, internal standard peaks, and BHMF product peaks were observed at 3.185 min, 19.289 min, and 20.805 min, respectively, and no other significant by-product peaks were observed.

[0045] Figure 3 shows the mass spectrum corresponding to the BHMF product peak in Figure 1 of the present invention. As is clear from the figure, the product at this position was identified as BHMF by comparison with a standard spectral library.

[0046] Figure 4 shows the gas chromatograph-mass spectrometry chromatogram of the product prepared in Comparative Example 1 of the present invention. As is clear from the figure, excluding the solvent, substrate, and product peaks, numerous impurity peaks appear within the time range in the chromatogram under experimental conditions. These impurity peaks usually correspond to by-products from acid polymerization, hydrolysis, etc., of the furfuryl alcohol substrate, making subsequent separation and purification difficult.

Claims

1. A method for producing high-purity 2,5-frangimethanol by catalytically reacting furfuryl alcohol with an aprotic acid catalyst, characterized in that a modified zeolite catalyst, furfuryl alcohol, and a hydroxymethylating reagent are added to an aprotic solvent, nitrogen gas is introduced to carry out the reaction, and after the reaction is complete, the solid phase is separated by filtration, the liquid phase is rotated and evaporated to recover the solvent, and then the temperature is raised to recover the solid, which is high-purity 2,5-frangimethanol, wherein the modified zeolite catalyst is obtained by dealuminizing β-zeolite with concentrated nitric acid and then introducing a transition metal element into the β-zeolite by solid-solid ion exchange.

2. A method for producing high-purity 2,5-flange methanol by catalytically reacting furfuryl alcohol using the aprotic acid catalyst described in claim 1, characterized in that the transition metal element is one or more of manganese, cobalt, and tin.

3. A method for producing high-purity 2,5-flange methanol, comprising catalytically reacting furfuryl alcohol with the aprotic acid catalyst described in claim 2, characterized in that the transition metal is manganese.

4. A method for producing high-purity 2,5-flange methanol by catalytically reacting furfuryl alcohol using the aprotic acid catalyst according to claim 1, characterized in that the hydroxymethylation reagent is a mixture of one or more of formaldehyde, trioxane, and paraformaldehyde.

5. A method for producing high-purity 2,5-frangimethanol by catalytically reacting furfuryl alcohol using the aprotic acid catalyst according to claim 1, characterized in that the aprotic solvent is a mixture of one or more of tetrahydrofuran, 1,4-dioxane, and methyl acetate.

6. A method for producing high-purity 2,5-frangimethanol by catalytically reacting furfuryl alcohol with the aprotic acid catalyst described in claim 1, characterized in that the molar ratio of furfuryl alcohol to the hydroxymethylating reagent is 1:1 to 9.

7. A method for producing high-purity 2,5-frangimethanol by catalytically reacting furfuryl alcohol with the aprotic acid catalyst according to claim 1, characterized in that the amount of furfuryl alcohol added is 1 to 10% of the volume of the aprotic solvent, and the amount of modified zeolite catalyst added is 1 to 20% of the total solvent mass.

8. A method for producing high-purity 2,5-frangimethanol by catalytically reacting furfuryl alcohol using the aprotic acid catalyst described in claim 1, characterized in that the reaction temperature is 80 to 140°C and the reaction time is 1 to 12 hours.

9. A method for producing high-purity 2,5-frangimethanol by catalytically reacting furfuryl alcohol with the aprotic acid catalyst described in claim 1, characterized in that the specific steps are as follows: 1) Place the β-zeolite in concentrated nitric acid and dealuminize it at a boiling temperature for 8 hours. After washing with water to neutralize, dry, introduce exogenous ions, i.e., transition metal elements, by mechanical grinding, and then calcine at high temperature and cool to finally obtain a modified zeolite catalyst. Here, the SiO in the β-zeolite ２ and Al ２ O ３ The molar ratio is 30:

1. 2) Add furfuryl alcohol and hydroxymethylation reagent to an aprotic solvent in a molar ratio of 1:1 to 9, simultaneously adding 1 to 20% of the total solvent mass of catalyst, using nitrogen gas as a protective gas, and reacting for 1 to 12 hours under conditions of 80 to 140°C, where the amount of furfuryl alcohol added is 1 to 10% of the volume of the aprotic solvent. 3) After the reaction is complete, the solid and liquid in the reaction system are separated by filtration. The solid, i.e., the catalyst, is washed with a washing solution, dried, and then regenerated. The liquid is separated from the solvent by rotary evaporation under conditions of 40-80°C, and the temperature is further raised to 100°C to remove trace amounts of furfuryl alcohol substrate. The recovered solid is high-purity 2,5-frangimethanol.

10. A method for producing high-purity 2,5-flange methanol, comprising catalytically reacting furfuryl alcohol using the aprotic acid catalyst described in claim 9, characterized in that in step 3) the washing solution is a mixture of one or more of methanol, ethanol, and acetone.

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