Method for efficiently preparing FDCA precursor from acetic acid system
By using pressure stirring and catalyst in the acetic acid system, the problem of difficulty in efficient preparation of FDCA precursors in high-concentration fructose raw materials was successfully solved, and FDCA preparation with high yield and high purity was achieved, which simplified the separation process and reduced costs. .
Patent Information
- Application Number
- CN202411547660.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-01
- Publication Date
- 2025-02-18
AI Technical Summary
The prior art uses an acetic acid system in high-concentration fructose raw materials to efficiently prepare FDCA precursors, and the separation process is cumbersome and the cost is high.
Add fructose, a small amount of water, acetic acid and catalyst to the closed reaction kettle with pressure stirring. After the reaction, the reaction solution is added to the heating reaction kettle with acetic acid solution and Co/Mn/Br catalyst, and oxygen is applied to the reaction. Filter and dry to obtain highly insoluble FDCA.
The efficient preparation of FDCA precursors was achieved, with the molar yield of FDCA of 82%, the purity was 99.7%, and the separation process was simplified and the cost was reduced.
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Abstract
Description
Technical Field
[0001] The invention relates to the field of bio-based polymer monomer preparation, and in particular to a method for efficiently preparing an FDCA precursor in an acetic acid system. Background Art
[0002] With the development of economy, bio-based new materials have become a hot track in the context of low-carbon economy. Bio-based polyesters based on 2,5-furandicarboxylic acid (FDCA), polyethylene furandicarboxylate (PEF) and its derivative polymers, as new bio-based plastic polyester materials, have significantly reduced carbon emissions compared to traditional PET polyester processes, and have excellent barrier properties, which have attracted the attention of academia and industry.
[0003] As a polymerization monomer of PEF, the production cost of FDCA is one of the key factors affecting the downstream competition with traditional polyester. At present, FDCA is mainly produced by catalyzing the oxidation of 5-hydroxymethylfurfural (HMF), and the production of HMF is mainly achieved by dehydration of fructose as raw material. Since HMF with hydrophilic hydroxyl groups has good solubility in both aqueous phase and organic solvent, it is difficult to achieve a high yield of HMF through extraction operation due to the poor distribution coefficient of HMF. In the literature, there are also many ideal substitutes for HMF, such as 5-methylfurfural (MF), 5-acetoxymethyl-furfural (AMF), 5-chloromethylfurfural (CMF), etc. Compared with the hydroxyl group at one end of HMF, these substitutes are hydrophobic, low boiling point, and more stable chemical properties. They are more likely to be efficiently separated in the subsequent extraction and separation steps, and can be used for large-scale and low-cost FDCA production, thereby increasing the diversity of raw materials. In the process of producing various aromatic dicarboxylic acids (terephthalic acid (PTA), furandicarboxylic acid (FDCA)), the MC method using Co / Mn / Br as catalyst, air as oxidant, and acetic acid (HAc) as solvent is very mature and popular. The oxidation process of the MC method follows the classic free radical chain reaction mechanism. Due to the synergistic effect of Co and Mn, the catalyst has high activity and fast reaction speed, which is conducive to large-scale production. Especially in the FDCA process, FDCA, which is highly insoluble in acetic acid, will precipitate when it is generated in the reaction solution, so FDCA can be easily separated from the solvent and catalyst by operations such as centrifugation or filtration.
[0004] In the pure water phase solvent system, the production process of HMF is accompanied by more black rot and more by-products. In the two-phase system, although the HMF yield and selectivity are improved in some in-situ extraction reactions, the instability and hydrophilicity of HMF inevitably lead to the subsequent HMF separation and purification process being cumbersome and costly. Therefore, it is necessary to find a cheap solvent that is suitable for both sugar dehydration and HMF oxidation to avoid the separation process.
[0005] In the production process of these aromatic dicarboxylic acids MC process, acetic acid as the only solvent is not only low-priced but also recyclable. If acetic acid can also be used as a dehydration solvent for fructose, the entire process from fructose to FDCA can be achieved in the same solvent system. In addition, although the solvent acetic acid easily reacts with HMF to form the ester derivative 5-acetoxymethyl-furfural (AMF), which reduces the yield of HMF, according to the MC oxidation process, they can all be oxidized to form FDCA. However, fructose dehydration requires a certain acidity. Due to the weak acidity of acetic acid, it is rarely used for fructose dehydration to prepare HMF. At the same time, the concentration of the sample raw material reported in the literature is low.
[0006] Therefore, how to efficiently prepare FDCA precursors (such as AMF, HMF) from high-concentration fructose raw materials in a cheap acetic acid system is the key to preparing FDCA in a single acetic acid solvent system. Summary of the invention
[0007] In view of the problems existing in the prior art, the object of the present invention is to provide a method for efficiently preparing a FDCA precursor from an acetic acid system using a relatively high concentration of fructose raw material in a green and inexpensive manner.
[0008] To achieve the above object, the technical solution of the present invention is as follows:
[0009] A method for efficiently preparing a FDCA precursor from an acetic acid system comprises the following steps:
[0010] 1) Add fructose, a small amount of water, acetic acid and a catalyst into a closed reactor with pressure stirring, react at the reaction temperature, and obtain a FDCA precursor reaction solution after the reaction is completed;
[0011] 2) The FDCA precursor reaction liquid obtained in step 1) is added to a heated reactor with pressure stirring and containing acetic acid solution and Co / Mn / Br catalyst, the reactor is heated to the reaction temperature, and then oxygen or air is introduced to reach a selected pressure to react. After the reaction is completed, water is passed to cool to room temperature, and FDCA crystals are separated by filtering with a Buchner funnel. After the FDCA crystals are dried, FDCA that is highly insoluble in acetic acid can be obtained.
[0012] Furthermore, in step 1), the mass ratio of fructose, acetic acid, water and catalyst is 1:3-10:0.1-1:0.05-0.3.
[0013] Furthermore, the catalyst in step 1) comprises a solid acid or a liquid acid.
[0014] Furthermore, in step 1), the solid acid is Amber-15, HND-587, HND-580 or HND-582; and the liquid acid is HCl or a mixed acid of HCl and HBr.
[0015] Furthermore, the mass proportion of HBr in the mixed acid of HCl and HBr is 0.2-5%.
[0016] Furthermore, the reaction temperature of step 1) is 100-140° C., and the reaction time is 10 min-90 min.
[0017] Furthermore, in step 2), the FDCA precursor includes AMF and HMF, and the equivalent molar ratio of HMF:Co:Mn:Br:acetic acid is calculated based on the mass reaction of the equivalent pure HMF, and is 100-700:3-10:1-2:1:1000.
[0018] Furthermore, in step 2), the reaction temperature is 140°C to 160°C, the selected pressure is 1 to 2.5 MPa, and the reaction time is 0.5 h to 2 h.
[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0020] 1) The present invention first adds fructose, a small amount of water, acetic acid and a catalyst into a container with stirring, reacts at a reaction temperature, and obtains a FDCA precursor reaction liquid after the reaction is completed. Then, the obtained FDCA precursor reaction liquid is added into a heating reactor with pressure stirring and containing an acetic acid solution and a Co / Mn / Br catalyst. The reactor is heated to the reaction temperature, and then oxygen or air is introduced to reach a selected pressure to react. After the reaction is completed, FDCA that is highly insoluble in acetic acid can be obtained, and the FDCA molar yield is 82% and the purity is 99.7%;
[0021] 2) The single acetic acid system developed in the present invention can achieve high-efficiency conversion of fructose concentration into FDCA precursors in the selected and optimized specific catalyst system. At the same time, by using the MC process, the FDCA precursors (AMF and HMF) are directly oxidized into highly insoluble FDCA in the acetic acid system, and the oxidation result is close to the air oxidation result of the HMF crystal raw material. DETAILED DESCRIPTION
[0022] The present invention will be further described below in conjunction with embodiments, but the scope of protection of the present invention is not limited to the described scope.
[0023] Both AMF and HMF were analyzed using an Agilent 1260 HPLC, with a methanol / water solution as the mobile phase, a C18 column, a flow rate of 1 mL / min, a detector temperature of 40 °C, and quantification by the external standard method.
[0024]
[0025]
[0026] Example 1-12: Effect of different types of catalysts on the total yield of FDCA precursor
[0027] 1) 0.75 g of fructose, 3 g of acetic acid and 0.075 g of different catalysts were placed in a closed reactor with pressure stirring, and reacted and stirred at 100° C. for 30 min to form a black solution. After standing and cooling, a small amount of liquid was taken out for liquid phase detection. The yields of HMF and AMF are shown in Table 1.
[0028] Table 1: Effect of different types of catalysts on total yield
[0029]
[0030] It can be seen from Table 1 that under the conditions of fructose concentration of 20% and 100°C / 30min, different types of catalysts have a great influence on the total yield.
[0031] 6M HCl and hydrochloric acid hydrogen bromide catalysts are effective in the acetic acid system. A total yield of 43.58% of AMF+HMF was achieved in 6M HCl. After adding hydrogen bromide, it was found that the introduction of a small amount of Br ions can increase the yield of AMF. Finally, after adding 5% hydrobromic acid, a total yield of 46.55% of AMF+HMF was achieved.
[0032] Since solid acid catalysts have the advantage of better separation after reaction, we tried to increase the concentration of solid acid catalysts, but the experimental results showed that increasing the concentration of solid acid catalysts had little effect on the total yield. Therefore, subsequent optimization experiments were conducted using a combination of hydrochloric acid and hydrobromic acid catalysts.
[0033] Examples 13-21
[0034] 0.75 g of fructose, 3 g of acetic acid, and a certain mass of 6M hydrochloric acid + hydrogen bromide catalyst were placed in a closed reactor with pressure stirring, and reacted and stirred at 100°C for 30 minutes to form a black solution. After standing and cooling, a small amount of liquid was taken out for liquid phase detection. The yields of HMF and AMF are shown in Table 2.
[0035] Table 2. Effect of different acid amounts and reaction times on total yield
[0036]
[0037] As shown in Table 2, under the conditions of fructose concentration of 20% and 100℃ / 30min, the influence of different catalyst masses on the total yield is different. Before the catalyst mass reaches 10% fructose mass, increasing the catalyst mass significantly improves the total yield. After the catalyst mass exceeds 10% fructose mass, continuing to increase the catalyst mass will slowly increase the total yield or even decrease. Therefore, it is more reasonable to control the catalyst mass around 10% fructose. At the same time, under the condition of 10% fructose mass, continuing to increase the reaction time to 60min, the yield of HMF is significantly improved, and continuing to increase the time, the total yield is relatively slow. Therefore, under the reaction condition of 100℃, it is more reasonable to control the reaction time at 60min.
[0038] Examples 22-26
[0039] 0.75 g of fructose, 3 g of acetic acid, 0.075 g of 6M hydrochloric acid + hydrogen bromide catalyst were placed in a closed reactor with pressure stirring, and reacted at different temperatures for a certain time to form a black solution. After standing and cooling, a small amount of liquid was taken out for liquid phase detection. The yields of HMF and AMF are shown in Table 3.
[0040] Table 3: Yield at different temperatures and at different times
[0041]
[0042] As shown in Table 3, increasing the reaction temperature can increase the reaction rate. In order to reduce the reaction time, we tried to compare the total yield between 100 and 140 °C in a fixed 30 min reaction. The results showed that the total yield increased significantly from 100 to 120 °C. However, the total yield did not increase significantly when the temperature was further increased, indicating that 120 °C / 30 min is an appropriate reaction temperature and reaction time.
[0043] Examples 27-32
[0044] Water addition optimization experiment: 0.75g fructose, 0.075g 6M hydrochloric acid + hydrogen bromide catalyst, a certain mass of water and acetic acid were put into a closed reactor with pressure stirring, and reacted and stirred for 30 minutes at a specific reaction temperature to form a black solution. After standing and cooling, a small amount of liquid was taken out for liquid phase detection. The yields of HMF and AMF are shown in Table 4.
[0045] Table 4: Water addition optimization experiment
[0046]
[0047]
[0048] As shown in Table 4, keeping the fructose concentration unchanged, compared with the case of no water, adding a small amount of water can greatly improve the total yield, exceeding 60%. It can be seen from the table that adding water mainly improves the yield contribution of HMF, but with the gradual introduction of water, the subsequent improvement of HMF is limited, so adding 0.3g of water is more appropriate.
[0049] Examples 33-35
[0050] FDCA Precursor Oxidation Example:
[0051] 2) Weigh 10g of HMF crystals, or weigh a certain mass of the precursor reaction solution obtained under the above conditions (same HMF equivalent), 0.3g of cobalt acetate, 0.02g of manganese acetate, 0.02g of 40% hydrobromic acid, and add 200g of acetic acid to a 500mL reactor, close the autoclave and check the air tightness. Turn on the stirring, set the reaction temperature to 150°C, connect the air after the temperature reaches the temperature, and the pressure is 2.0Mpa; set the reaction time to 0.5h. After the reaction is completed, cool to room temperature with water. Use a Buchner funnel to filter and separate the FDCA crystals, and collect the filtrate. The FDCA crystals are dried at 60°C for 6h, and the filtrate and FDCA dry product are taken for HPLC analysis. The results are shown in Table 5.
[0052] Table 5: FDCA precursor oxidation experiment
[0053]
[0054] As shown in Table 5, the FDCA precursor can be directly oxidized by air in the acetic acid system to become highly insoluble FDCA, and the FDCA precursor (AMF and HMF) obtained under the optimal reaction conditions is directly oxidized by air in the acetic acid system, and the oxidation results are close to the air oxidation results of the HMF crystal raw material, which has good industrial application prospects.
Claims
1. A method for efficiently preparing a FDCA precursor from an acetic acid system, characterized in that The steps include: 1) Add fructose, a small amount of water, acetic acid and a catalyst into a closed reactor with pressure stirring, react at the reaction temperature, and obtain a FDCA precursor reaction solution after the reaction is completed; 2) The FDCA precursor reaction liquid obtained in step 1) is added to a heated reactor with pressure stirring and containing acetic acid solution and Co / Mn / Br catalyst, the reactor is heated to the reaction temperature, and then oxygen or air is introduced to reach a selected pressure to react. After the reaction is completed, water is passed to cool to room temperature, and FDCA crystals are separated by filtering with a Buchner funnel. After the FDCA crystals are dried, FDCA that is highly insoluble in acetic acid can be obtained.
2. A method for efficiently preparing a FDCA precursor from an acetic acid system according to claim 1, characterized in that In step 1), the mass ratio of fructose, acetic acid, water and catalyst is 1:3-10:0.1-1:0.05-0.
3.
3. A method for efficiently preparing a FDCA precursor from an acetic acid system according to claim 1, characterized in that Step 1) The catalyst includes a solid acid or a liquid acid.
4. A method for efficiently preparing a FDCA precursor from an acetic acid system according to claim 3, characterized in that Step 1) The solid acid is Amber-15, HND-587, HND-580 or HND-582; the liquid acid is HCl or a mixed acid of HCl and HBr.
5. A method for efficiently preparing a FDCA precursor from an acetic acid system according to claim 4, characterized in that The mass proportion of HBr in the HCl and HBr mixed acid is 0.2-5%.
6. The method for efficiently preparing a FDCA precursor from an acetic acid system according to claim 1, characterized in that The reaction temperature of step 1) is 100-140°C, and the reaction time is 10-90 minutes.
7. The method for efficiently preparing a FDCA precursor from an acetic acid system according to claim 1, characterized in that In step 2), the FDCA precursor includes AMF and HMF. The equivalent molar ratio of HMF:Co:Mn:Br:acetic acid is calculated based on the mass reaction of the equivalent pure HMF, and is 100-700:3-10:1-2:1:1000.
8. The method for efficiently preparing a FDCA precursor from an acetic acid system according to claim 1, characterized in that Step 2) The reaction temperature is 140°C to 160°C, the selected pressure is 1 to 2.5 MPa, and the reaction time is 0.5 h to 2 h.