A method for preparing 2,5-furandiethanol

Abstract

This invention discloses a method for preparing 2,5-furandiethanol, comprising the following steps: 1) preparing a copper salt solution, an alkaline solution, and a substrate HMF solution for later use; 2) slowly adding the alkaline solution to the copper salt solution while stirring, sonicating the uniformly stirred solution, filtering and washing to remove soluble inorganic salts after sonication, and then drying to obtain a solid copper-based oxide catalyst for later use; 3) placing the solid copper-based oxide catalyst in a tube furnace and activating it in a mixed atmosphere of H2 and Ar, and granulating the obtained powder catalyst to 1-2 mm after activation to obtain a copper-based fixed-bed catalyst; 4) loading the fixed-bed catalyst into the catalyst tube of a fixed-bed reactor, and catalytically hydrogenating the pumped substrate HMF solution under a hydrogen atmosphere to obtain 2,5-furandiethanol. This method is safe, stable, and efficient in production, with good catalyst stability and simple reaction operation.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, specifically to a method for preparing 2,5-furandiethanol. Background Technology

[0002] 5-Hydroxymethylfurfural (HMF) is an important bio-based platform compound that can be obtained from renewable resources such as carbohydrates and lignocellulose. Selective hydrogenation of HMF can yield products such as 2,5-furandiethanol (BHMF), tetrahydrofurandiethanol, and 1,2,6-hexanetriol. Among these, BHMF is a high-value derivative with diol properties and is a potential substitute for petroleum-based terephthalic acid, with a very broad market prospect. BHMF can be used to synthesize pharmaceutical and fragrance intermediates, and can also be used as a monomer to synthesize polyesters, polyurethanes, and other polymeric materials.

[0003] Traditional chemical methods require the use of precious metal catalysts and involve some organic solvents and toxic chemical systems to prepare 2,5-furandiethanol through high-temperature and high-pressure hydrogenation in a batch reactor.

[0004] For example, Chinese patent CN 115960060 A discloses a method for preparing 2,5-furandimethylethanol using a non-precious metal catalyst. However, the Cu / SiO2 catalyst requires a long preparation time, exceeding 12 hours, and the reaction system is tetrahydrofuran, resulting in high production costs and a long reaction heating time. Chinese patent CN115779896A discloses a catalyst and its preparation method for the selective hydrogenation of 5-hydroxymethylfurfural to 2,5-furandimethylethanol. It uses a Pt-Ir / TiO2 catalyst and HMF as a raw material to prepare BHMF. The use of a precious metal catalyst and a catalyst preparation time exceeding 12 hours make it complex, leading to a long time for the HMF to BHMF preparation. Chinese patent CN 115992191 A discloses a method for the reduction synthesis of 2,5-furandimethylethanol from 5-hydroxymethylfurfural using a dual-enzyme coupled catalytic process. This method uses a dual-enzyme coupled process with HMF as a raw material to catalyze the preparation of BHMF. However, the reuse of biomass enzymes is difficult, and the long production time makes it unsuitable for industrial production. In patent WO2023077822A1, the hydrogen pressure required for the preparation of BHMF from HMF is 2-5 MPa, and the reaction time is 2-5 hours. Higher hydrogen pressure and longer reaction time result in relatively higher production costs. In patent CN114105914A, the preparation of HMFCA from HMF not only uses a precious metal catalyst but also requires a higher hydrogen pressure.

[0005] Therefore, this invention proposes a method for preparing 2,5-furandiethanol under mild conditions in a fixed-bed reactor, which has high selectivity and high yield. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for preparing 2,5-furandiethanol by hydrogenation with high efficiency and low cost.

[0007] The technical solution of the present invention is as follows:

[0008] A method for preparing 2,5-furandiethanol includes the following steps:

[0009] 1) Prepare copper salt solution, alkaline solution and substrate HMF solution for later use;

[0010] 2) Slowly add the alkaline solution prepared in step 1) to the copper salt solution while stirring. Then, put the well-stirred solution into an ultrasonic cleaner for ultrasonic cleaning. After ultrasonic cleaning, filter and wash to remove soluble inorganic salts. Then dry to obtain a solid copper-based oxide catalyst for later use.

[0011] 3) Place the solid copper-based oxide catalyst obtained in step 2) in a tube furnace and activate it in a mixed atmosphere of H2 and Ar. After activation, granulate the obtained powder catalyst to 1-2 mm to obtain a copper-based fixed bed catalyst.

[0012] 4) The copper-based fixed-bed catalyst prepared in step 3) is loaded into the catalyst tube of the fixed-bed reactor. Under a hydrogen atmosphere, the substrate HMF solution pumped into the fixed-bed reactor is subjected to catalytic hydrogenation to obtain 2,5-furandiethanol.

[0013] Furthermore, in step 4), the hydrogen pressure is 0.5-3 MPa.

[0014] Furthermore, in step 4), the temperature of the catalytic hydrogenation reaction is 80-150℃.

[0015] Furthermore, in step 4), the hydrogen flow rate is 40-100 ml / min.

[0016] Furthermore, in step 4), the flow rate of the substrate HMF solution pumped in is 0.1-10 ml / min.

[0017] Furthermore, in step 3), the activation time is 1-4 hours.

[0018] Furthermore, in step 3), the activation temperature is 300℃-700℃.

[0019] Furthermore, in step 2), the molar ratio of copper salt to alkali is 1:1.5-4.

[0020] Further, 1) the concentration of the substrate HMF solution in step 1) is 3-20 wt%; wherein the solvent for preparing the substrate HMF is ethanol, methanol, isopropanol, acetonitrile, tetrahydrofuran or ethyl acetate.

[0021] Furthermore, the preparation time of the copper-based fixed-bed catalyst is 2.5-3.5 h.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1) This invention prepares 2,5-furandiethanol under mild conditions in a fixed-bed reactor, achieving a high HMF conversion rate of 99.89% and a high BHMF yield of 95%.

[0024] 2) This invention prepares 2,5-furandiethanol in a fixed-bed reactor. The application of continuous process makes the production of furandiethanol safer, more stable and efficient. The catalyst has good stability, which simplifies the entire reaction operation and is conducive to large-scale production.

[0025] 3) Compared with the prior art, the hydrogen pressure required by the present invention is relatively low (0.5-3 MPa), the reaction is relatively safe, and it is suitable for industrial production;

[0026] 4) Compared with the prior art, the catalyst of the present invention is a non-precious metal, the preparation process is simple, and the preparation time is short, which is 2.5-3.5h. Attached Figure Description

[0027] Figure 1 Here is the gas chromatogram of the sample from Example 16;

[0028] Figure 2 This is a gas chromatography-mass spectrometry (GC) image of the sample from Example 11. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to the scope described.

[0030] Example 1 Preparation of Catalyst 1

[0031] Take 25g of copper sulfate pentahydrate in a beaker, dissolve it in water and stir thoroughly. Take 8g of sodium hydroxide in a beaker, dissolve it in water and stir thoroughly. Add the prepared sodium hydroxide solution to the copper sulfate solution while stirring. After stirring thoroughly, put the solution into an ultrasonic cleaner and sonicate for 20 minutes. Then filter to wash away soluble inorganic salts to obtain solid copper oxide. Dry it at 100℃ for 2 hours. Granulate the obtained solid into 1-2 mm particles to obtain the copper-based catalyst CuOx.

[0032] Example 2 Preparation of Catalyst 2

[0033] Catalyst 1 from Example 1 was placed in a tube furnace and activated in a 10% H2 / Ar mixed atmosphere for 2 hours at an activation temperature of 300°C. After activation, the obtained powdered catalyst was granulated to 1-2 mm to obtain Cu-300.

[0034] Examples 3-6: Preparation of Catalyst 3-6

[0035] Four portions of catalyst 1 from Example 1 were placed in a tube furnace and activated for 2 hours in a 10% H2 / Ar mixed atmosphere at activation temperatures of 400℃, 500℃, 600℃, and 700℃, respectively. After activation, the obtained powdered catalyst was granulated to 1-2 mm to obtain Cu-400, Cu-500, Cu-600, and Cu-700.

[0036] Examples 7-12 Preparation of 2,5-furandiethanol

[0037] 3.2 g each of catalysts 1-6 prepared above were loaded into catalyst tubes. A 5% HMF ethanol solution was prepared using a system hydrogen back pressure of 1 MPa and a hydrogen flow rate of 60 ml / min, and pumped into a fixed-bed reactor at a flow rate of 1 ml / min. The preheating temperature was set at 50℃, and the reaction temperature of the fixed bed was 120℃. After the system stabilized, samples were collected every 1 hour for gas chromatography analysis. The average value was taken after the three sets of data stabilized. The results of the HMF hydrogenation reaction are shown in Table 1 below:

[0038] Table 1 shows the yields of 2,5-furandiethanol prepared in Examples 7-12.

[0039]

[0040] The results showed that the HMF conversion and BHMF yield of the hydrogen-activated copper-based catalyst were significantly higher than those of CuOx. The catalyst Cu-600, prepared at an activation temperature of 600℃, exhibited higher selectivity for BHMF, with a BHMF yield reaching 95%.

[0041] Example 13-22 Preparation of 2,5-furandiethanol

[0042] Take 3.2g of Cu-600 fixed-bed catalyst (10 parts) and fix it in the catalyst tube. The reaction steps are the same as in Example 7.

[0043] By changing the reaction conditions such as hydrogen flow rate, reaction temperature, liquid flow rate, and substrate concentration, the experimental results are shown in Table 2 below.

[0044] Table 2 shows the yields of 2,5-furandiethanol prepared in Examples 13-22.

[0045]

[0046] Gas chromatography analysis was performed on the sample from Example 16. Figure 1 It can be seen that 18.652 min is the peak of HMF and 19.442 min is the peak of BHMF.

[0047] Figure 2 This is a gas chromatography-mass spectrometry (GC) image taken after the reaction in Example 11 had stabilized.

[0048] As can be seen from the comparison of the above embodiments:

[0049] Comparative studies of Examples 13, 14, 15, 16, 11, 21, and 22 conclude that increasing the temperature within a certain range is beneficial for improving the conversion rate of HMF and the yield of BHMF. However, excessively high temperatures will reduce the yield of BHMF.

[0050] Comparing Examples 14, 15, 11, and 19, it is concluded that increasing the pressure is beneficial to improving the conversion rate of HMF and the yield of BHMF. Excessive pressure reduces the yield of BHMF, possibly due to over-hydrogenation resulting in some byproducts.

[0051] Comparative studies of Examples 11, 16, and 17 conclude that increasing the hydrogen flow rate is beneficial for improving the conversion rate of HMF and the yield of BHMF. When the hydrogen flow rate is increased to a certain value, the HMF conversion rate and the BHMF yield become comparable.

[0052] Comparing Examples 18 and 11, it was concluded that increasing the substrate liquid flow rate reduces the residence time of the substrate in the reactor, resulting in a decrease in HMF conversion.

[0053] Comparing Examples 11 and 20, it was concluded that as the substrate concentration increased, the conversion rate of HMF decreased slightly and the yield of BHMF decreased. This may be because the increased substrate concentration and incomplete hydrogenation produced some byproducts.

Claims

1. A method for preparing 2,5-furandiethanol, characterized in that... Includes the following steps: 1) Take 25g of copper sulfate pentahydrate in a beaker, dissolve it in water and stir thoroughly; take 8g of sodium hydroxide in a beaker, dissolve it in water and stir thoroughly. 2) Add the sodium hydroxide solution obtained in step 1) to the copper sulfate solution while stirring. After stirring thoroughly, put the solution into an ultrasonic cleaner and sonicate for 20 minutes. Then filter to wash away the soluble inorganic salts to obtain solid copper oxide. Dry it at 100℃ for 2 hours. Granulate the obtained solid into 1-2 mm particles to obtain the copper-based catalyst CuOx for later use. 3) Place the copper-based catalyst CuOx obtained in step 2) in a tube furnace and activate it in a 10% H2 / Ar mixed atmosphere for 2 hours at an activation temperature of 600℃. After activation, granulate the obtained powder catalyst to 1-2 mm to obtain Cu-600. 4) The Cu-600 catalyst prepared in step 3) is loaded into the catalyst tube of the fixed-bed reactor. Under a hydrogen atmosphere, the substrate HMF solution pumped into the fixed-bed reactor is subjected to catalytic hydrogenation. The conditions for the catalytic reaction are: the temperature of the catalytic hydrogenation reaction is 120℃ and the hydrogen pressure is 1-3MPa; or the temperature of the catalytic hydrogenation reaction is 130℃ and the hydrogen pressure is 1MPa, to obtain 2,5-furandiethanol.

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