A method for producing high-purity 2,5-furan dimethanol by catalyzing furfuryl alcohol using a protonic acid catalyst

Abstract

The present invention discloses a method for producing high-purity 2,5-furandimethanol by catalytically reacting furfuryl alcohol with a non-protonic acid catalyst, belonging to the field of furan-based biomass chemicals and materials. In this method, a modified zeolite catalyst, furfuryl alcohol and a hydroxymethylation reagent are added to an aprotic solvent, and nitrogen is introduced for reaction. After the reaction is completed, filtration is carried out to separate the solid and liquid phases. The solvent in the liquid phase is recovered by rotary evaporation and then the temperature is further increased to collect the solid, which is high-purity 2,5-furandimethanol. Among them, the modified zeolite catalyst is obtained by subjecting β-zeolite to dealumination treatment and then introducing transition metal elements as Lewis acid active sites into the zeolite through a solid-solid ion exchange method. The modified zeolite of the present invention, as a non-protonic acid catalyst, is different from the problems of poor selectivity of the target product and separation problems caused by side reactions related to protonic acid catalysts, and can achieve high selectivity for the target product. The synthesis process and the separation and purification process are simple, the raw material cost is low, and it conforms to the development concept of green chemistry.

Description

Technical Field

[0001] The invention belongs to the field of furan-based biomass chemicals and materials, and particularly relates to a method for producing high-purity 2,5-furan dimethanol by catalyzing furfuryl alcohol with a proton-free acid catalyst. Background Art

[0002] 2,5-Furan dimethanol (BHMF) is an aromatic furandiol mainly derived from 5-hydroxymethylfurfural (HMF). It is an important monomer for the synthesis of aromatic polyester materials replacing petroleum-based diols and is widely used in the synthesis of ethers, polymers, resins and adhesives. At present, the main factor limiting the application of BHMF is the high cost of HMF: the industrial production of HMF mainly relies on the dehydration of fructose catalyzed by inorganic acids, while the cheaper glucose process is still in the research stage; in addition, in the reduction and derivatization of HMF, it is necessary to show high selectivity for C=O and C=C bonds, which poses a major challenge to the catalyst and catalytic process. In contrast, the furfural industry has achieved economies of scale, with more than 65% of its production capacity used for furfuryl alcohol-related production applications, which means that the direct production of BHMF through furfuryl alcohol hydroxymethylation is a very cost-effective strategy.

[0003] The earliest production of BHMF from furfuryl alcohol can be traced back to Laszlo-Hedwig et al. (Polymer Science U.SSR, 1983, 25: 228-236), who used formaldehyde as a hydroxymethylation agent to convert furfuryl alcohol into BHMF in an acidic environment by simulating the acidic polymerization process of phenolic resin. However, compared with the hydroxymethylation of phenol, the highly active furfuryl alcohol will undergo severe self-polymerization in an acidic environment, especially in an aqueous environment, resulting in a low selectivity for BHMF; in addition, in a strong acid environment, the side reaction caused by the opening of the furan structure is another important reason for the low selectivity of BHMF. In order to solve these problems, researchers have also conducted relevant studies: high-silicon hydrophobic mordenite can replace inorganic acid to achieve higher BHMF selectivity at low FAl concentrations; polyoxymethylene replaces formaldehyde solution to alleviate the side reaction problem caused by the introduction of formaldehyde into the aqueous phase; the active hydroxyl groups of furfuryl alcohol are protected before the hydroxymethylation reaction to reduce related side reactions. Even so, there are still some problems that need to be solved: the reaction energy barrier of the CH bond on the aromatic ring is too high, the self-polymerization problem after the protonation of free formaldehyde, the product selectivity and the subsequent separation problems caused by by-products such as humic acid.

[0004] Therefore, it is urgent to provide a method for preparing high-purity BHMF with high selectivity, simple separation, reduced side reactions and simple process. Summary of the invention

[0005] In view of the above problems existing in the prior art, the technical problem to be solved by the present invention is to provide a method for producing high-purity 2,5-furan dimethanol by catalyzing furfuryl alcohol using a protonic acid catalyst, which is used to deal with the problems of serious side reactions, poor selectivity, complex separation and high cost in the current preparation of 2,5-furan dimethanol.

[0006] In order to solve the above problems, the technical solution adopted in the present invention is as follows:

[0007] A method for producing high-purity 2,5-furan dimethanol by catalyzing furfuryl alcohol with a protonic acid catalyst comprises the following steps: adding a modified zeolite catalyst, furfuryl alcohol and a hydroxymethylation agent into a non-protonic solvent, introducing nitrogen gas for reaction, filtering after the reaction is completed, separating the solid and liquid phases, rotary evaporating the liquid phase to recover the solvent, and then continuing to heat the liquid phase to collect the solid, thus obtaining the high-purity 2,5-furan dimethanol; wherein the modified zeolite catalyst is obtained by introducing a transition metal element into the β-zeolite through a solid-solid ion exchange method after dealuminizing β-zeolite with concentrated nitric acid.

[0008] Furthermore, the transition metal element is one or more of manganese, cobalt and tin.

[0009] Furthermore, the transition metal is manganese.

[0010] Furthermore, the hydroxymethylation agent is one or a mixture of formaldehyde, trioxymethylene and polyformaldehyde.

[0011] Furthermore, the aprotic solvent is one or a mixture of tetrahydrofuran, 1,4-dioxane and methyl acetate.

[0012] Furthermore, the molar ratio of furfuryl alcohol to the hydroxymethylation agent is 1:1-9.

[0013] Furthermore, the amount of furfuryl alcohol added is 1-10% of the volume of the aprotic solvent, and the amount of the modified zeolite catalyst added is 1-20% of the total solvent mass.

[0014] Furthermore, the reaction temperature is 80-140° C., and the reaction time is 1-12 hours.

[0015] Further, the specific steps are as follows:

[0016] 1) The β-zeolite is placed in concentrated nitric acid for dealumination under boiling conditions for 8 hours, then washed with water until neutral, dried, and then mechanically ground to introduce exogenous ions, i.e., transition metal elements, and then calcined at high temperature and cooled to finally obtain a modified zeolite catalyst; wherein, SiO in the β-zeolite 2 and Al 2 O 3 The molar ratio is 30:1;

[0017] 2) adding furfuryl alcohol and a hydroxymethylation agent into an aprotic solvent at a molar ratio of 1:1 to 9, and adding a catalyst in an amount of 1 to 20% of the total mass of the solvent, and reacting for 1 to 12 hours under the conditions of nitrogen as a protective gas and a temperature of 80 to 140° C.; wherein the amount of furfuryl alcohol added is 1 to 10% of the volume of the aprotic solvent;

[0018] 3) After the reaction is completed, the solid and liquid in the reaction system are separated by filtering, the solid, i.e., the catalyst, is washed with a washing solution and dried before regeneration, the liquid is subjected to rotary evaporation to separate the solvent at 40 to 80° C., and the temperature is continued to rise to 100° C. to remove trace amounts of furfuryl alcohol substrate, and the collected solid is high-purity 2,5-furan dimethanol.

[0019] Furthermore, in step 3), the washing liquid is one or a mixture of methanol, ethanol and acetone.

[0020] The schematic diagram of the conversion of furfuryl alcohol into high-purity 2,5-furan dimethanol under the catalysis of a proton-free acid catalyst is shown in FIG. Figure 1 shown.

[0021] Beneficial effects: Compared with the prior art, the advantages of the present invention are:

[0022] (1) The catalyst used in the present invention is a non-protonic acid catalyst, which is characterized by relying on Lewis acid active sites to complete the hydroxymethylation process, thereby reducing protonic acid-related side reactions.

[0023] (2) The catalytic pathway of the present invention is different from that of proton acid forming hydroxymethyl cations and then attacking furfuryl alcohol in a disordered manner to complete hydroxymethylation. The proton-free acid catalyst of the present invention not only promotes the hydroxymethyl cations but also assists them in anchoring the reaction position of furfuryl alcohol, thereby achieving targeted completion of the hydroxymethylation reaction and reducing side reactions associated with electrophilic reagents.

[0024] (3) The low by-product content and high selectivity for BHMF of the present invention allow the reaction solution and catalyst to be recovered by simple distillation, thus simplifying the product separation and reagent recovery process.

[0025] (4) The synthesis process and separation and purification process of the present invention are simple, the catalyst can be recycled and reused, and the cost of raw materials is reduced, which is in line with the concept of green chemistry development. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of converting furfuryl alcohol into high-purity 2,5-furan dimethanol under the catalysis of a protonic acid catalyst of the present invention;

[0027] Figure 2 A gas chromatography-mass spectrometry time diagram of the reaction solution prepared in the present invention;

[0028] Figure 3 For the present invention Figure 1 Mass spectrum corresponding to the BHMF product peak;

[0029] Figure 4 This is a gas chromatography-mass spectrometry time chart of the product prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with specific embodiments.

[0031] The selectivity, yield and purity of BHMF prepared in the following examples were calculated according to the following formula:

[0032] The selectivity of BHMF (S BHMF ) is calculated as follows:

[0033]

[0034] Among them, m 0 is the mass of furfuryl alcohol substrate; m 1 Remaining furfuryl alcohol substrate mass; m 3 is the mass of chromatographically pure BHMF; M 糠醇 M is the molar molecular weight of furfuryl alcohol; BHMF is the molar molecular mass of BHMF.

[0035] Yield of BHMF Y BHMF The calculation formula is as follows:

[0036]

[0037] Among them, m 2 is the mass of the absolute dry product; m 0 is the mass of furfuryl alcohol substrate; M 糠醇 M is the molar molecular weight of furfuryl alcohol; BHMF is the molar molecular mass of BHMF.

[0038] Purity of BHMF (P BHMF ) is calculated as follows:

[0039]

[0040] Among them, m 3 is the chromatographic measurement mass of BHMF; m 2 The quality of the absolutely dry product.

[0041] The purity of BHMF prepared in the following examples was tested by chromatographic purity according to the following steps:

[0042] 0.1 g (absolute dry equivalent) of the product was placed in a beaker and an appropriate amount of tetrahydrofuran was added to dissolve it. After cooling to room temperature, the volume was adjusted to 100 mL, and filtered through a 0.22 μm organic syringe filter for detecting the BHMF concentration. A gas chromatograph (Shimadzu, GC-2010 Plus) equipped with a strong polar column (DB-WAXetr) was used for analysis, and chromatographically pure n-dodecane was used as an internal reference. The test conditions were: a temperature range of 40 to 280°C, a heating rate of 5°C / min before 40 to 150°C and 2°C / min before 150°C to 280°C. The precise content of BHMF in the product was obtained through the internal reference and the drawn BHMF standard curve, and the chromatographic purity of the sample was further calculated.

[0043] Formaldehyde (37 wt % aqueous solution), trioxymethylene (AR), paraformaldehyde (95%), tetrahydrofuran (AR), 1,4-dioxane (99.5%) and methyl acetate (99%) used in the following examples were purchased from Shanghai Macklin.

[0044] Example 1

[0045] 1. Preparation of modified zeolite catalyst

[0046] Take β-zeolite (SiO 2 With Al 2 O 3 The molar ratio of the catalyst is 30:1) and placed in concentrated nitric acid (mass fraction is 68%) for dealumination under boiling state for 8 hours, washed with water to neutrality, dried at 105°C, and then cobalt nitrate in an amount equivalent to the molar amount of the removed aluminum element is added for mechanical grinding, then placed in a tubular furnace for treatment at 600°C under nitrogen protection for 4 hours, and then placed in a muffle furnace for insulation at 600°C for 4 hours. The product after cooling is the prepared modified zeolite catalyst.

[0047] 2. Preparation of BHMF

[0048] Furfuryl alcohol and formaldehyde solution (based on the molar equivalent of formaldehyde monomer) are added to tetrahydrofuran in a molar ratio of 1:3, wherein the volume of furfuryl alcohol is 2% of the volume of tetrahydrofuran, and a modified zeolite catalyst equivalent to 5% of the total solvent mass is added at the same time, and the air in the device is exhausted by nitrogen, and the reaction is stirred at 100°C for 4 hours; after the reaction is completed, a filtering device is used to separate the solid and liquid phases, wherein the solid is washed three times continuously with ethanol and then dried to recover the catalyst, and the drying temperature is 105°C, and the liquid is used to recover the solvent at 60°C using a rotary evaporator, and the temperature is continued to rise to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals are collected to obtain BHMF.

[0049] Example 2

[0050] Preparation of BHMF

[0051] Furfuryl alcohol and formaldehyde solution (based on the molar equivalent of formaldehyde monomer) are added to tetrahydrofuran in a molar ratio of 1:9, wherein the volume of furfuryl alcohol is 5% of the volume of tetrahydrofuran, and a modified zeolite catalyst (modified zeolite catalyst prepared by the method of Example 1) equivalent to 10% of the total solvent mass is added, and nitrogen is used to exhaust the air in the device, and the reaction is stirred at 80°C for 8h; after the reaction is completed, a filtering device is used to separate the solid and liquid phases, wherein the solid is washed three times with ethanol continuously and then dried to recover the catalyst, and the drying temperature is 105°C, and the liquid is used to recover the solvent at 60°C using a rotary evaporator, and the temperature is continued to be raised to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals are collected to obtain BHMF.

[0052] Example 3

[0053] Preparation of BHMF

[0054] Furfuryl alcohol and trioxymethylene (based on the molar equivalent of formaldehyde monomer) are added to tetrahydrofuran in a molar ratio of 1:9, wherein the volume of furfuryl alcohol is 5% of the volume of tetrahydrofuran, and a modified zeolite catalyst (modified zeolite catalyst prepared by the method of Example 1) equivalent to 10% of the total solvent mass is added, and nitrogen is used to exhaust the air in the device, and the reaction is stirred at 100° C. for 4 hours; after the reaction is completed, a filtering device is used to separate the solid and liquid phases, wherein the solid is washed three times with acetone continuously and then dried to recover the catalyst, and the drying temperature is 105° C. The liquid is used to recover the solvent at 60° C. using a rotary evaporator, and the temperature is continued to be raised to 100° C. to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals are collected to obtain BHMF.

[0055] Example 4

[0056] Preparation of BHMF

[0057] Furfuryl alcohol and paraformaldehyde (based on the molar equivalent of formaldehyde monomer) are added to methyl acetate in a molar ratio of 1:3, wherein the volume of furfuryl alcohol is 5% of the volume of tetrahydrofuran, and a modified zeolite catalyst (modified zeolite catalyst prepared by the method of Example 1) equivalent to 10% of the total solvent mass is added, and nitrogen is used to exhaust the air in the device, and the reaction is stirred at 100° C. for 8 hours; after the reaction is completed, a filtering device is used to separate the solid and liquid phases, wherein the solid is washed three times continuously with methanol and then dried to recover the catalyst, and the drying temperature is 105° C. The liquid is used to recover the solvent at 60° C. using a rotary evaporator, and the temperature is continued to be raised to 100° C. to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals are collected to obtain BHMF.

[0058] Example 5

[0059] 1. Preparation of modified zeolite catalyst

[0060] Take β-zeolite (SiO 2 With Al 2 O3 The molar ratio of is 30:1) is placed in concentrated nitric acid (mass fraction is 68%) for dealumination under boiling state for 8 hours, washed with water to neutrality, dried at 105°C, added with manganese nitrate in an amount equivalent to the molar amount of the aluminum element to be removed, mechanically ground, then placed in a muffle furnace at 600°C for 4 hours, and the product after cooling is the prepared modified zeolite catalyst.

[0061] 2. Preparation of BHMF

[0062] Furfuryl alcohol and paraformaldehyde (based on the molar equivalent of formaldehyde monomer) are added to methyl acetate in a molar ratio of 1:9, wherein the volume of furfuryl alcohol is 5% of the volume of tetrahydrofuran, and a modified zeolite catalyst equivalent to 10% of the total solvent mass is added at the same time, and the air in the device is exhausted by nitrogen, and the reaction is stirred at 120°C for 8 hours; after the reaction is completed, a filtration device is used to separate the solid and liquid phases, wherein the solid is washed three times continuously with ethanol and then dried to recover the catalyst, and the drying temperature is 105°C, and the liquid is used to recover the solvent at 60°C using a rotary evaporator, and the temperature is continued to rise to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals are collected to obtain BHMF.

[0063] Example 6

[0064] Preparation of BHMF

[0065] Furfuryl alcohol and paraformaldehyde (based on the molar equivalent of formaldehyde monomer) are added to methyl acetate in a molar ratio of 1:6, wherein the volume of furfuryl alcohol is 10% of the volume of tetrahydrofuran, and a modified zeolite catalyst (modified zeolite catalyst prepared by the method of Example 5) equivalent to 20% of the total solvent mass is added, and nitrogen is used to exhaust the air in the device, and the reaction is stirred at 120°C for 8 hours; after the reaction is completed, a filtering device is used to separate the solid and liquid phases, wherein the solid is washed three times with ethanol continuously and then dried to recover the catalyst, and the drying temperature is 105°C, and the liquid is used to recover the solvent at 60°C using a rotary evaporator, and the temperature is continued to be raised to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals are collected to obtain BHMF.

[0066] Example 7

[0067] Preparation of BHMF

[0068] Furfuryl alcohol and paraformaldehyde (based on the molar equivalent of formaldehyde monomer) are added to 1,4-dioxane in a molar ratio of 1:9, wherein the volume of furfuryl alcohol is 1% of the volume of tetrahydrofuran, and a modified zeolite catalyst (modified zeolite catalyst prepared by the method of Example 5) equivalent to 5% of the total solvent mass is added, and the mixture is stirred and reacted at 110° C. for 4 hours; after the reaction is completed, a filtering device is used to separate the solid and liquid phases, wherein the solid is washed three times with ethanol continuously and then dried to recover the catalyst, and the drying temperature is 105° C. The liquid is used to recover the solvent at 60° C. using a rotary evaporator, and the temperature is continued to be raised to 100° C. to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals are collected to obtain BHMF.

[0069] Example 8

[0070] 1. Preparation of modified zeolite catalyst

[0071] Take β-zeolite (SiO 2 With Al 2 O 3 The molar ratio of the catalyst is 30:1) and placed in concentrated nitric acid (mass fraction is 68%) for dealumination under boiling state for 8 hours, washed with water to neutrality, dried at 105°C, and then manganese nitrate in an amount equivalent to the molar amount of the removed aluminum element is added for mechanical grinding, then placed in a tubular furnace for treatment at 600°C under nitrogen protection for 4 hours, and then placed in a muffle furnace for insulation at 600°C for 4 hours. The product after cooling is the prepared modified zeolite catalyst.

[0072] 2. Preparation of BHMF

[0073] Furfuryl alcohol and polyformaldehyde (calculated as formaldehyde monomer molar equivalent) are added to 1,4-dioxane in a molar ratio of 1:9, wherein furfuryl alcohol is 1% of the volume of tetrahydrofuran, and a modified zeolite catalyst equivalent to 5% of the total solvent mass is added at the same time, and nitrogen is used to exhaust the air in the device, and the reaction is stirred at 110°C for 12 hours; after the reaction is completed, a filtration device is used to separate the solid and liquid phases, wherein the solid is washed three times with ethanol continuously and then dried to recover the catalyst, and the drying temperature is 105°C, and the liquid is used to recover the solvent at 80°C using a rotary evaporator, and the temperature is continued to rise to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals are collected to obtain BHMF.

[0074] Example 9

[0075] 1. Preparation of modified zeolite catalyst

[0076] Take β-zeolite (SiO 2 With Al 2 O 3The molar ratio of the catalyst is 30:1) and placed in concentrated nitric acid (mass fraction is 68%) for dealumination under boiling state for 8 hours, washed with water to neutrality, dried at 105°C, and then mechanically ground with tin nitrate in an amount equivalent to the molar ratio of the aluminum element to be removed. The catalyst is then placed in a tubular furnace for treatment at 600°C under nitrogen protection for 4 hours, and then placed in a muffle furnace for insulation at 600°C for 4 hours. The product after cooling is the prepared modified zeolite catalyst.

[0077] 2. Preparation of BHMF

[0078] Furfuryl alcohol and polyformaldehyde (calculated as formaldehyde monomer molar equivalent) are added to 1,4-dioxane in a molar ratio of 1:9, wherein furfuryl alcohol is 1% of the volume of tetrahydrofuran, and a modified zeolite catalyst equivalent to 5% of the total solvent mass is added at the same time, and nitrogen is used to exhaust the air in the device, and the reaction is stirred at 80°C for 12 hours; after the reaction is completed, a filtration device is used to separate the solid and liquid phases, wherein the solid is washed three times with acetone and then dried to recover the catalyst, and the drying temperature is 105°C, and the liquid is used to recover the solvent at 60°C using a rotary evaporator, and the temperature is continued to rise to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals are collected to obtain BHMF.

[0079] Comparative Example 1

[0080] Furfuryl alcohol and polyformaldehyde (calculated as formaldehyde monomer molar equivalent) are added to 1,4-dioxane in a molar ratio of 1:9, wherein furfuryl alcohol is 5% of the volume of tetrahydrofuran, and acetic acid equivalent to 5% of the total solvent volume is added as a catalyst, and nitrogen is used to exhaust the air in the device, and the reaction is stirred at 110°C for 6 hours; after the reaction is completed, a rotary evaporator is used to recover the solvent and acetic acid at 80°C, and the temperature is continued to rise to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals are collected, which are BHMF.

[0081] Comparative Example 2

[0082] Furfuryl alcohol and paraformaldehyde (based on the molar equivalent of formaldehyde monomer) were added to 1,4-dioxane at a molar ratio of 1:9, wherein the volume of furfuryl alcohol was 1% of the volume of tetrahydrofuran, and an unmodified β-zeolite catalyst (SiO 2 With Al 2 O 3 The molar ratio is 30:1), the air in the device is exhausted by nitrogen, and the reaction is stirred at 110°C for 6 hours; after the reaction is completed, it is filtered, and the solid is washed three times with acetone and then dried to recover the catalyst, the drying temperature is 105°C, the liquid is used to recover the solvent at 60°C using a rotary evaporator, and the temperature is continued to rise to 100°C to remove trace amounts of furfuryl alcohol substrate, and the remaining crystals are collected to obtain BHMF.

[0083] Comparative Example 3

[0084] Furfuryl alcohol and paraformaldehyde (based on the molar equivalent of formaldehyde monomer) were added to 1,4-dioxane at a molar ratio of 1:9, wherein the volume of furfuryl alcohol was 1% of the volume of tetrahydrofuran, and zeolite (H-ZSM-5, SiO 2 With Al 2 O 3 The molar ratio is 18:1) catalyst, nitrogen is used to exhaust the air in the device, and the reaction is stirred at 110°C for 6 hours; after the reaction is completed, it is filtered, and the solid is washed three times with acetone and then dried to recover the catalyst, the drying temperature is 105°C, the liquid is used to recover the solvent at 60°C using a rotary evaporator, and the temperature is continued to rise to 100°C to remove trace furfuryl alcohol substrate, and the remaining crystals are collected as BHMF.

[0085] Comparative Example 4

[0086] Furfuryl alcohol and paraformaldehyde (based on the molar equivalent of formaldehyde monomer) were added to 1,4-dioxane at a molar ratio of 1:9, wherein the volume of furfuryl alcohol was 1% of the volume of tetrahydrofuran, and zeolite (H-SAPO-11, SiO 2 、Al 2 O 3 and P 2 O 5 The catalyst is added with a molar ratio of 0.63:1:0.82), and the air in the device is exhausted by nitrogen. The reaction is stirred at 110°C for 6 hours. After the reaction is completed, the catalyst is filtered, and the solid is washed three times with acetone and then dried to recover the catalyst. The drying temperature is 105°C. The liquid is subjected to a rotary evaporator at 60°C to recover the solvent, and the temperature is continuously raised to 100°C to remove trace amounts of furfuryl alcohol substrate. The remaining crystals are collected to obtain BHMF.

[0087] The yields and conversion rates of the BHMF products prepared in Examples 1 to 9 of the present invention and Comparative Examples 1 to 4 are shown in Table 1 below.

[0088] Table 1 BHMF product yield and product conversion rate prepared in Examples 1 to 9 and Comparative Examples 1 to 4

[0089]

[0090] Table 1 shows the yield and conversion rate of BHMF products prepared by Examples 1 to 9 and Comparative Examples 1 to 4. It can be seen from the table that the temperature and time of the catalytic reaction affect the progress and selectivity of the hydroxymethylation reaction. Generally, increasing the concentration of the substrate is not conducive to improving the selectivity of the reaction, while increasing the amount of catalyst used can accelerate the reaction process; compared with protonic acid catalysts such as Comparative Example 1, the BHMF produced by the protonic acid-free catalyst has a higher purity and is more conducive to the recovery of the catalyst, thereby ensuring the purity of the target product and the high efficiency of separation and recovery. And the high and low silicon-aluminum ratio will affect the number of ion exchanges. The active sites of the high silicon-aluminum ratio will be relatively small, but the catalyst is usually excessive during use, so it actually shows obvious differences in catalytic performance. Among the zeolite catalysts modified by different single metals, the zeolite catalyst modified by metal manganese has the best effect; in Comparative Examples 1 to 4, although the furfuryl alcohol conversion rate is high, the BHMF yield and purity are low, and both cannot meet the use requirements.

[0091] Figure 2 This is a gas phase-mass spectrometry time diagram of the reaction solution prepared in the present invention. As can be seen from the figure, 3.185 min, 19.289 min and 20.805 min represent the solvent peak, the internal reference peak and the BHMF product peak, respectively, and no obvious other by-product peaks are found.

[0092] Figure 3 For the present invention Figure 1 The mass spectrum corresponding to the BHMF product peak in the figure shows that the product at this position is identified as BHMF based on comparison with the standard spectrum library.

[0093] Figure 4 This is a gas phase-mass spectrometry time diagram of the product prepared in Comparative Example 1 of the present invention. As can be seen from the figure, excluding the solvent, substrate and product peaks, the time spectrum under the experimental conditions shows more impurity peaks within the time range. These impurity peaks usually correspond to by-products such as acid polymerization and hydrolysis of the furfuryl alcohol substrate, which bring difficulties to the subsequent separation and purification.

Claims

1. A method for producing high-purity 2,5-furan dimethanol by catalyzing furfuryl alcohol with a protonic acid catalyst, characterized in that: A modified zeolite catalyst, furfuryl alcohol and polyformaldehyde are added to an aprotic solvent, and nitrogen is introduced to react. After the reaction is completed, the reaction is filtered to separate the solid and liquid phases, the liquid phase is rotary evaporated to recover the solvent, and then the temperature is continued to rise to collect the solid, which is high-purity 2,5-furan dimethanol; wherein the modified zeolite catalyst is obtained by introducing a transition metal element into the β-zeolite through a solid-solid ion exchange method after β-zeolite is dealuminated with concentrated nitric acid; the transition metal element is one or more of manganese, cobalt and tin; the reaction temperature is 100-140°C, and the reaction time is 8-12h.

2. The method for producing high-purity 2,5-furan dimethanol by catalyzing furfuryl alcohol with a protonic acid catalyst according to claim 1, characterized in that: The transition metal is manganese.

3. The method for producing high-purity 2,5-furan dimethanol by catalyzing furfuryl alcohol with a protonic acid catalyst according to claim 1, characterized in that: The aprotic solvent is one of tetrahydrofuran, 1,4-dioxane and methyl acetate or a mixture of several of them.

4. The method for producing high-purity 2,5-furan dimethanol by catalyzing furfuryl alcohol with a protonic acid catalyst according to claim 1, characterized in that: The molar ratio of furfuryl alcohol to paraformaldehyde is 1:1-9.

5. The method for producing high-purity 2,5-furan dimethanol by catalyzing furfuryl alcohol with a protonic acid catalyst according to claim 1, characterized in that: The amount of furfuryl alcohol added is 1-10% of the volume of the aprotic solvent, and the amount of the modified zeolite catalyst added is 1-20% of the total solvent mass.

6. The method for producing high-purity 2,5-furan dimethanol by catalyzing furfuryl alcohol with a protonic acid catalyst according to claim 1, characterized in that: The specific steps are as follows: 1) The β-zeolite is placed in concentrated nitric acid for dealumination under boiling conditions for 8 hours, then washed with water until neutral, dried, and then mechanically ground to introduce exogenous ions, i.e., transition metal elements, and then calcined at high temperature and cooled to finally obtain a modified zeolite catalyst; wherein the molar ratio of SiO2 to Al2O3 in the β-zeolite is 30:1; 2) Furfuryl alcohol and paraformaldehyde are added to an aprotic solvent in a molar ratio of 1:1-9, and a catalyst is added in an amount of 1-20% of the total mass of the solvent, and the reaction is carried out for 8-12 hours under nitrogen as a protective gas and a temperature of 100-140 °C; wherein the amount of furfuryl alcohol added is 1-10% of the volume of the aprotic solvent; 3) After the reaction is completed, the solid and liquid in the reaction system are separated by filtration. The solid, i.e., the catalyst, is washed and dried with a washing solution and then regenerated. The liquid is subjected to rotary evaporation to separate the solvent at 40-80°C and the temperature is continued to rise to 100°C to remove trace amounts of furfuryl alcohol substrate. The collected solid is high-purity 2,5-furan dimethanol.

7. The method for producing high-purity 2,5-furan dimethanol by catalyzing furfuryl alcohol with a protonic acid catalyst according to claim 6, characterized in that: In step 3), the washing liquid is one or a mixture of methanol, ethanol and acetone.

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