A method for the synthesis of FDCA by the co-catalytic carbonylation of furfuryl alcohol using rhodium and iodide ligands.
By optimizing the reaction conditions and process flow through a synergistic catalytic system of rhodium and iodide ligands, the problems of byproduct formation and catalyst deactivation in the synthesis of FDCA by furfuryl alcohol carbonylation were solved, and efficient and low-cost FDCA production was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- PUYANG HONGYE ENVIRONMENTAL TECH RES INST CO LTD
- Filing Date
- 2026-02-09
- Publication Date
- 2026-05-26
AI Technical Summary
The existing reaction route for synthesizing FDCA by furfuryl alcohol carbonylation is complex, prone to generating byproducts, and the catalyst is easily deactivated. Separation and recovery are difficult, and the high temperature and pressure result in high energy consumption and high cost, which limits its industrial application.
By employing a synergistic catalytic system of rhodium and iodide ligands, optimizing reaction solvents and process conditions, and combining a simple acid precipitation and DMF decolorization and recrystallization method, a highly efficient and selective synthesis of FDCA is achieved, and an efficient catalyst recovery and regeneration method is provided.
It achieves efficient conversion of furfuryl alcohol to FDCA, with high catalyst recovery rate, reduced by-product generation, reduced production costs and energy consumption, and is suitable for the refined production of mid-to-high-end FDCA.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of FDCA synthesis technology, and more specifically to a method for the synergistic catalytic carbonylation of furfuryl alcohol to synthesize FDCA using rhodium and iodide ligands. Background Technology
[0002] 2,5-Furfurandicarboxylic acid (FDCA), as a highly promising bio-based platform compound, is considered an ideal alternative to petroleum-based terephthalic acid (PTA) due to its unique furan ring structure and dicarboxyl functional group. FDCA can be used to synthesize a series of high-performance bio-based polymers, such as polyethylene furandicarboxylate (PEF), a substitute for polyethylene terephthalate (PET), as well as polyamides, plasticizers, coatings, etc., showing broad application prospects in materials science, pharmaceutical intermediates, and fine chemicals.
[0003] Currently, the main synthetic routes for FDCA include: 1. Oxidation method using 5-hydroxymethylfurfural (HMF) as a raw material; 2. One-pot method using hexose or its derivatives as raw materials; 3. Conversion method using other furan derivatives (such as furoic acid and furfuryl alcohol) as raw materials. Among these, the furfuryl alcohol carbonylation method has attracted much attention from industry and academia because furfuryl alcohol, as a raw material, can be prepared on a large scale from hemicellulose in agricultural waste (such as corn cobs and straw), and has advantages such as wide availability of raw materials, low cost, and short reaction path.
[0004] In studies on the carbonylation synthesis of FDCA from furfuryl alcohol, noble metal catalysts, especially rhodium-based catalysts, are typically used, supplemented by iodides as co-catalysts. However, the following problems exist in practical applications: 1. The carbonylation process involves complex reaction pathways and easily generates various byproducts, such as the monocarbonylation product 2-furanic acid, the intermediate 5-hydroxymethyl-2-furanic acid, and even deep oxidation or degradation reactions such as furan ring opening. These side reactions not only reduce the yield and selectivity of the target product FDCA, but also increase the difficulty and cost of subsequent separation and purification.
[0005] 2. To improve catalyst performance, organophosphorus ligands are often introduced. However, many commonly used phosphorus ligands are prone to decomposition, oxidation (e.g., forming phosphine oxide) or dissociation from the catalytic center under high temperature, high pressure, and acidic or oxidizing environments, leading to rapid catalyst deactivation and making it difficult for the reaction to proceed stably for a long time.
[0006] 3. This reaction system is usually a homogeneous catalysis. After the reaction, the precious metal rhodium catalyst dissolved in the reaction medium is mixed with the product, solvent, etc. The separation and recovery process is complicated, often involving multiple steps such as precipitation, extraction, and adsorption. This is not only cumbersome to operate, but also prone to loss of precious metals, which significantly increases production costs and limits its large-scale industrial application.
[0007] 4. In order to obtain a high conversion rate, existing methods often require a high reaction temperature and carbon monoxide pressure, which not only puts higher demands on the materials and safety of the reaction equipment (autoclave), but also leads to huge energy consumption.
[0008] To address the aforementioned issues, this invention designs a method for the synergistic catalytic carbonylation of furfuryl alcohol to synthesize FDCA using rhodium and iodide ligands. By optimizing the reaction solvent and process conditions, this method achieves efficient and highly selective conversion of furfuryl alcohol to FDCA. Furthermore, it establishes an efficient catalyst recovery and regeneration method, providing a feasible path for the refined and large-scale production of FDCA. Summary of the Invention
[0009] The purpose of this invention is to address the problems mentioned in the background section by providing a method for the synergistic catalytic carbonylation of furfuryl alcohol to synthesize FDCA using rhodium and iodide ligands.
[0010] To achieve the above objectives, the present invention specifically adopts the following technical solution: A method for the synthesis of FDCA by the co-catalytic carbonylation of furfuryl alcohol using rhodium and iodide ligands, comprising the following steps: S1. Ingredients: Add furfuryl alcohol, main catalyst dicarbonyl rhodium chloride dimer, co-catalyst iodomethane, ligand triphenylphosphine and acetic acid water mixed solvent to the high pressure vessel in sequence; S2. Reaction preparation: Replace the air in the autoclave with nitrogen at least 3 times, then introduce carbon monoxide gas into the autoclave until the initial pressure reaches 4-6 MPa, and stir at a stirring speed of 500-600 rpm. S3, Carbonylation reaction: Heat the reaction system in the autoclave to 180-200℃ and carry out the reaction for 6-8 hours while maintaining a stable carbon monoxide pressure. When the furfuryl alcohol conversion rate reaches or exceeds 95%, terminate the reaction. S4. Product Separation and Catalyst Recovery: After cooling the reaction solution in the reactor to room temperature, add 10% sodium carbonate aqueous solution to the reaction solution to adjust the pH value to 8-9, so that the generated FDCA is converted into water-soluble sodium FDCA salt. Then, extract the reaction solution with ethyl acetate to separate the organic phase containing the catalyst and ligands and the aqueous phase containing sodium FDCA salt. After concentrating the organic phase, add concentrated hydrochloric acid at a volume of 5%-10% of the concentrated organic phase under a carbon monoxide atmosphere of 0.5-1 MPa to regenerate the dicarbonyl rhodium chloride dimer catalyst. S5. Product Refining: The obtained aqueous phase is acidified to pH=2 with concentrated hydrochloric acid, causing FDCA to precipitate in solid form. After filtration and washing with water, the crude product is dissolved in hot N,N-dimethylformamide, activated carbon is added for decolorization and recrystallization, and finally dried under vacuum conditions of 80℃ and 10mmHg to obtain high-purity FDCA.
[0011] Preferably, in step S1, the purity of the dicarbonyl rhodium chloride dimer is higher than 98%, and the purity of iodomethane is higher than 99%.
[0012] Preferably, in step S1, the molar ratio of furfuryl alcohol, the main catalyst (calculated as rhodium), iodomethane, and triphenylphosphine is 1000:1:50-100:5.
[0013] Preferably, in step S1, the water volume content in the acetic acid-water mixed solvent is 5%-10%, and the total amount of solvent used is 5-8 times the mass of furfuryl alcohol.
[0014] Preferably, in step S3, the carbonylation reaction, the temperature of the carbonylation reaction is 190°C, the carbon monoxide pressure is 5 MPa, and the reaction time is 7 hours.
[0015] Preferably, in step S4, product separation and catalyst recovery, the catalytic activity retention rate of the regenerated catalyst is not less than 95%.
[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Through the synergistic design of the catalytic system and the optimization of process conditions, the efficient conversion of furfuryl alcohol and the highly selective generation of FDCA were achieved. The conversion rate of furfuryl alcohol can reach more than 95%, and the selectivity of FDCA can reach more than 93%, which is significantly better than the traditional rhodium catalytic system, reducing the generation of by-products and the burden of subsequent purification.
[0017] 2. The PPh3 ligand exhibits higher stability in the solvent system of this invention, which slows down the deactivation of the catalyst. At the same time, this invention provides a simple and efficient catalyst recovery and regeneration process with a catalyst recovery rate of not less than 90%. After being recycled 5 times, its catalytic activity retention rate is still above 95%, which greatly reduces the production cost and solves the main bottleneck in the application of noble metal catalysts in homogeneous reactions.
[0018] 3. Through simple acid precipitation, combined with the refining steps of DMF decolorization and recrystallization, high-quality FDCA products with a purity higher than 99% can be stably obtained, which can meet the needs of high-end polymer synthesis such as PEF.
[0019] 4. The reaction pressure and temperature of this invention are relatively mild, the equipment requirements are low, and the energy consumption is less. At the same time, the solvent and catalyst can be recycled throughout the entire process, and the amount of "three wastes" generated is small, which meets the requirements of green chemistry and sustainable development and is suitable for the refined and continuous production of mid-to-high-end FDCA. Detailed Implementation
[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0021] The materials and instruments used in the following examples are all commercially available.
[0022] Example 1: S1. Ingredients: In a 100mL high-pressure reactor equipped with magnetic stirring, temperature control, and gas inlet / outlet lines, add 9.6g (100mmol) of furfuryl alcohol, 19.5mg (0.05mmol, 0.1mmol as Rh) of dicarbonyl rhodium chloride dimer ([Rh(CO)₂Cl]₂, 98% purity), 0.71g (5mmol) of iodomethane (CH₃I, 99% purity), and 65.5mg (0.25mmol) of triphenylphosphine (PPh₃). Then add 48g of acetic acid-water mixed solvent (water content 5% by volume). At this point, the molar ratio of furfuryl alcohol:Rh:CH₃I:PPh₃ is 1000:1:50:5 (the original text states 5mmol of CH₃I, corresponding to a molar ratio of 1000:1:50:5; for consistency, it is calculated as 5mmol here).
[0023] S2. Reaction Preparation: After sealing the reactor, replace the air inside the reactor three times with high-purity nitrogen. Then, introduce carbon monoxide (CO) gas into the reactor until the initial pressure is 5.0 MPa, start stirring, and set the speed to 550 rpm.
[0024] S3, Carbonylation reaction: The reactor was heated to 190°C using an external heating mantle and maintained at this temperature and CO pressure for the reaction. Heating was stopped after 7 hours of reaction. Online GC analysis showed that the conversion rate of furfuryl alcohol was 97.5%, and the selectivity of the target product 2,5-furandicarboxylic acid (FDCA) was 94.2%.
[0025] S4. Product Separation and Catalyst Recovery: After the reaction, the reactor was cooled to room temperature and the pressure was slowly released. A 10% sodium carbonate aqueous solution was added dropwise to the reaction solution to adjust the pH to 8.5, and the mixture was stirred for 30 minutes. Then, it was extracted twice with 100 mL of ethyl acetate. The organic phases were combined, and the aqueous phase was retained. The organic phase was concentrated by vacuum distillation and transferred to another small reactor. CO was introduced to 0.8 MPa, and 1 mL of concentrated hydrochloric acid was slowly added dropwise. The reaction was carried out at 60 °C for 2 hours to obtain the regenerated catalyst solution. The catalyst recovery rate was calculated to be 92%. This regenerated catalyst was used in a cycle experiment, and its activity retention rate was 96%.
[0026] S5. Product Refining: The retained aqueous phase was acidified with concentrated hydrochloric acid to pH=2, resulting in the precipitation of a large amount of white precipitate. The precipitate was filtered and washed three times with deionized water to obtain crude FDCA. The crude product was dissolved in 100 mL of hot DMF, and 1 g of activated carbon was added. The mixture was stirred at 120 °C for 30 minutes to decolorize. The activated carbon was removed by hot filtration, and the filtrate was allowed to cool naturally to crystallize. The crystals were collected by filtration and dried at 80 °C under a vacuum of 10 mmHg for 6 hours, finally yielding 14.2 g of white needle-like FDCA product, with a yield of 91.0%. HPLC analysis showed that the product purity was 99.3%.
[0027] Example 2: Except for the following changes, the remaining operating steps and material amounts were the same as in Example 1: the amount of iodomethane (CH3I) was changed to 1.42 g (10 mmol), i.e., the molar ratio of furfuryl alcohol:Rh:CH3I:PPh3 was 1000:1:100:5; the volume content of water in the acetic acid-water mixed solvent was increased to 10%; the reaction temperature was set to 180 °C, the initial CO pressure was 4.0 MPa, and the reaction time was extended to 8 hours.
[0028] After the reaction was completed, the analysis results showed that the furfuryl alcohol conversion rate was 95.8% and the FDCA selectivity was 93.0%. Post-processing was performed according to the method in Example 1, with a catalyst recovery rate of 90.5%, ultimately yielding an FDCA product with a purity of 99.1%.
[0029] This embodiment investigated the feasibility of maintaining high efficiency at lower temperatures (180°C) and pressures (4.0 MPa) by increasing the amount of co-catalyst and reaction time. The results showed that even under milder conditions, the method of this invention still achieved a furfuryl alcohol conversion of over 95% and FDCA selectivity of 93%, demonstrating the good operational flexibility and adaptability to different reaction conditions of the process, which can further reduce energy consumption while ensuring high yield.
[0030] Example 3: Except for the following changes, the remaining operating steps and material usage are the same as in Example 1: the reaction temperature is increased to 200°C, the initial CO pressure is increased to 6.0 MPa, and the reaction time is shortened to 6 hours.
[0031] After the reaction, the analysis results showed that the furfuryl alcohol conversion rate was 98.1% and the FDCA selectivity was 92.5% (at which point a trace increase in furanyl acid byproducts was detected). Post-processing was performed according to the method in Example 1, with a catalyst recovery rate of 89.8%, ultimately yielding an FDCA product with a purity of 99.0%.
[0032] This embodiment explores the possibility of improving production efficiency by shortening the reaction time under higher temperatures (200°C) and pressures (6.0 MPa). The results show that the reaction time can be shortened to 6 hours, while the furfuryl alcohol conversion rate increases to 98.1%, although the selectivity decreases slightly but remains at a high level of 92.5%. This demonstrates that the method of the present invention has the potential to accelerate the reaction rate and shorten the production cycle by appropriately intensifying reaction conditions, making it suitable for industrial scenarios with higher requirements for production efficiency.
[0033] Example 4 (Catalyst Cyclic Stability Experiment): The initial reaction was conducted based on the reaction conditions of Example 1. After the reaction, the catalyst was recovered and regenerated according to step 4 of Example 1. The regenerated catalyst solution was directly used in the next batch of reaction, only replenishing trace amounts of solvent and CH3I lost due to sampling and transfer. This cycle was repeated 5 times. After each reaction, the furfuryl alcohol conversion and FDCA selectivity were measured, and the catalyst recovery rate was calculated. The results are summarized in the table below: As shown in the table above, after five consecutive cycles, the catalytic activity (characterized by furfuryl alcohol conversion) and selectivity of the catalytic system described in this invention show only a very slight decrease. The conversion and selectivity in the fifth cycle are still as high as 96.2% and 93.3%, respectively. This fully demonstrates the effectiveness of the catalyst recovery and regeneration method provided by this invention, as well as the excellent cycle stability of the catalytic system.
[0034] This embodiment, through five consecutive catalyst cycling experiments, comprehensively verifies the stability and reliability of the catalyst recovery and regeneration strategy of this invention. The experimental results clearly demonstrate that after multiple cycles, the catalyst's activity and selectivity remain at extremely high levels without significant degradation. This strongly proves that the closed-loop catalyst cycling system established in this invention is highly efficient and robust, successfully solving the key technical bottleneck of high cost and difficulty in recovery of precious metal catalysts in homogeneous catalysis, and showcasing significant industrial application value.
[0035] Comparative example (traditional rhodium catalytic system): To highlight the advantages of the synergistic catalytic system of this invention, a ratio was set up. A conventional catalytic system was used, specifically as follows: In the same reaction vessel as in Example 1, 9.6 g (100 mmol) of furfuryl alcohol, 26.3 mg (0.1 mmol) of RhCl3·3H2O were added as the main catalyst, and 1.66 g (10 mmol) of KI was added as a co-catalyst, but no organophosphorus ligands were added. 50 g of pure acetic acid was used as the solvent. All other reaction conditions (nitrogen purging, CO pressure 5.0 MPa, stirring speed 550 rpm, reaction temperature 190 °C, and reaction time 7 hours) were kept consistent with those in Example 1.
[0036] Seven hours after the reaction, samples were taken for analysis. The results showed that the conversion rate of furfuryl alcohol was only 85.2%, and the selectivity of FDCA was as low as 78.5%. The product composition was complex, containing not only FDCA but also a significant amount of 2-furanoic acid and other unknown byproducts. Furthermore, after the reaction, due to the lack of an effective phase separation strategy, the rhodium catalyst dissolved in acetic acid was difficult to separate from the product effectively, resulting in a complex recovery process with significant losses.
[0037] This comparative example, by removing the key triphenylphosphine ligand and employing a conventional catalyst and solvent system, clearly highlights the technical advantages of this invention. The results show that, in the absence of ligand synergy, even under the same reaction conditions, both furfuryl alcohol conversion and FDCA selectivity are significantly reduced, and byproducts increase significantly. Simultaneously, catalyst recovery becomes exceptionally difficult. This comparison strongly demonstrates that the originality and superiority of the rhodium iodide ligand synergistic catalytic system in this invention are key to achieving high-efficiency, high-selectivity FDCA synthesis.
[0038] Through direct comparison of the above examples and comparative examples, it can be clearly seen that the rhodium iodide ligand synergistic catalytic system provided by the present invention, combined with an optimized solvent system and post-processing technology, exhibits significant advantages in terms of catalytic efficiency, product selectivity, and catalyst recycling performance in the reaction of furfuryl alcohol carbonylation to FDCA.
Claims
1. A method for the synthesis of FDCA by the co-catalytic carbonylation of furfuryl alcohol using rhodium and iodide ligands, characterized in that, Includes the following steps: S1. Ingredients: Add furfuryl alcohol, main catalyst dicarbonyl rhodium chloride dimer, co-catalyst iodomethane, ligand triphenylphosphine and acetic acid water mixed solvent to the high pressure vessel in sequence; S2. Reaction preparation: Replace the air in the autoclave with nitrogen at least 3 times, then introduce carbon monoxide gas into the autoclave until the initial pressure reaches 4-6 MPa, and stir at a stirring speed of 500-600 rpm. S3, Carbonylation reaction: Heat the reaction system in the autoclave to 180-200℃ and carry out the reaction for 6-8 hours while maintaining a stable carbon monoxide pressure. When the furfuryl alcohol conversion rate reaches or exceeds 95%, terminate the reaction. S4. Product Separation and Catalyst Recovery: After cooling the reaction solution in the reactor to room temperature, add 10% sodium carbonate aqueous solution to the reaction solution to adjust the pH value to 8-9, so that the generated FDCA is converted into water-soluble sodium FDCA salt. Then, extract the reaction solution with ethyl acetate to separate the organic phase containing the catalyst and ligands and the aqueous phase containing sodium FDCA salt. After concentrating the organic phase, add concentrated hydrochloric acid at a volume of 5%-10% of the concentrated organic phase under a carbon monoxide atmosphere of 0.5-1 MPa to regenerate the dicarbonyl rhodium chloride dimer catalyst. S5. Product Refining: The obtained aqueous phase is acidified to pH=2 with concentrated hydrochloric acid, causing FDCA to precipitate in solid form. After filtration and washing with water, the crude product is dissolved in hot N,N-dimethylformamide, activated carbon is added for decolorization and recrystallization, and finally dried under vacuum conditions of 80℃ and 10mmHg to obtain high-purity FDCA.
2. The method for synthesizing FDCA by the co-catalytic carbonylation of furfuryl alcohol according to claim 1, characterized in that, In step S1, the purity of the dicarbonyl rhodium chloride dimer is higher than 98%, and the purity of iodomethane is higher than 99%.
3. The method for synthesizing FDCA by the co-catalytic carbonylation of furfuryl alcohol according to claim 1, characterized in that, In step S1, the molar ratio of furfuryl alcohol, the main catalyst (calculated as rhodium), iodomethane, and triphenylphosphine in the batch is 1000:1:50-100:
5.
4. The method for synthesizing FDCA by the co-catalytic carbonylation of furfuryl alcohol according to claim 1, characterized in that, In step S1, the water volume content in the acetic acid-water mixed solvent is 5%-10%, and the total amount of solvent used is 5-8 times the mass of furfuryl alcohol.
5. The method for synthesizing FDCA by the co-catalytic carbonylation of furfuryl alcohol according to claim 1, characterized in that, In step S3, the carbonylation reaction, the temperature is 190°C, the carbon monoxide pressure is 5 MPa, and the reaction time is 7 hours.
6. The method for synthesizing FDCA by the co-catalytic carbonylation of furfuryl alcohol according to claim 1, characterized in that, In step S4, product separation and catalyst recovery, the catalytic activity retention rate of the regenerated catalyst shall not be less than 95%.