Method for preparing saturated dicarboxylic acid from bio-based platform compound

Abstract

The invention relates to the technical field of dicarboxylic acid preparation, and particularly discloses a method for preparing saturated dicarboxylic acid from a bio-based platform compound, which comprises the following steps: a furyl aldehyde compound is used as a raw material to prepare an intermediate product through a hydrogenation reaction, and the furyl aldehyde compound is obtained by using a furan ring as a parent nucleus structure and using a furan ring as a secondary nucleus structure. A compound having an aldehyde group as a functional group; adding the intermediate product, a Rh-based catalyst, an iodine accelerant and a mixed solvent composed of organic carboxylic acid and water into a reaction kettle for mixing, introducing carbon monoxide and hydrogen into the reaction kettle at the same time, and heating at the temperature of 120-200 DEG C under the stirring condition until the reaction is finished to obtain the final product saturated dicarboxylic acid. According to the method, the saturated dicarboxylic acid is prepared from the renewable furyl aldehyde compound as a raw material, dependence on a petroleum-based raw material can be avoided, meanwhile, the target product is directly obtained through one-step double carbonylation, traditional multi-step reaction and separation are avoided, the reaction is efficient, and the yield of the target product is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dicarboxylic acid preparation, and particularly relates to a method for preparing saturated dicarboxylic acid from a bio-based platform compound. BACKGROUND

[0002] Pimelic acid (C7H 12 O4) and suberic acid (C8H 14 O4) are important aliphatic dicarboxylic acids, which are widely used in chemical production and are key raw materials for synthesizing lubricating oil, plasticizer, heat conducting oil, dielectric fluid, synthetic fiber, copolymer, ink, resin for paint, surfactant, bactericide, insecticide, hot melt coating and adhesive. With the promotion of global green chemical industry and sustainable development concept, the market demand for bio-based pimelic acid and suberic acid continues to grow, and the traditional preparation process relying on petroleum-based raw materials has been difficult to meet the requirements of environmental protection and resource sustainability.

[0003] At present, the methods for synthesizing pimelic acid and suberic acid mainly include the industrial mainstream thermal chemical method and the biological method, and both methods have significant technical bottlenecks, which are as follows: The thermal chemical method uses petroleum-based compounds as raw materials to prepare target products through oxidation, cracking and addition reactions, and has problems such as complex process, serious pollution and low yield. For example, the nitric acid oxidation cycloheptanone and cyclooctanone method: this method is the earliest industrialized technology, which uses concentrated nitric acid to oxidize cycloheptanone and cyclooctanone to generate pimelic acid and suberic acid, but has the following defects: the nitric acid has strong corrosive property, and a special material reaction kettle (such as titanium alloy) is required, which has high equipment cost; a large amount of nitrogen oxides (NO2, NO) is generated in the reaction, and a complex tail gas treatment system is required, which has high environmental protection cost; the system after the reaction is strongly acidic, and high-salt wastewater is generated in the neutralization process, which has great difficulty in pollution control; the raw material cycloheptanone / cyclooctanone relies on petroleum cracking, which is expensive and greatly affected by oil price fluctuations. For example, the Diels-Alder addition method of butadiene and acrylonitrile: this method generates tetrahydrophenyl nitrile by the addition reaction of butadiene and acrylonitrile, and then generates pimelic acid by the steps of 523-573℃ alkali fusion, ring opening and hydrolysis. The defects are: the reaction steps are many, a plurality of reaction and separation devices are required, and the process complexity is high; the alkali fusion step requires high temperature (250-300℃), which has high energy consumption and strong alkali corrosion equipment; the product contains toxic unreacted acrylonitrile, and the separation cost accounts for more than 20% of the total cost; the raw materials butadiene and acrylonitrile are petroleum cracking products, which have strong resource dependence.

[0004] The biological method uses microorganisms or enzymes as catalysts, has environmental advantages, but has extremely low yield and has not been industrialized. For example, normal alkane oxidation fermentation: C7 / C 11Alkanes are carbon sources, and heptanedioic acid is generated by microbial double-end oxidation. The defects are: the carbon source is still petroleum-based, the resource problem has not been solved; alkanes are difficult to dissolve in water, surfactants are needed, and the cost is increased; the yield is only 10-50 mg / L, which is far lower than the requirement of industrialization.

[0005] Therefore, the prior art still needs to be improved and developed. SUMMARY

[0006] In view of the deficiencies of the prior art described above, the purpose of the present application is to provide a method for preparing dicarboxylic acid based on biomass-derived raw materials, which is simple in process, environmentally safe, efficient and industrialized.

[0007] The technical scheme of the present application is as follows: A method for preparing saturated dicarboxylic acid from a bio-based platform compound, comprising the steps of: The furan aldehyde compound, the first catalyst and the solvent are mixed in the reaction kettle, hydrogen is introduced into the reaction kettle, and the intermediate reaction liquid is obtained by heating to the end of the hydrogenation reaction under the first stirring condition. The intermediate reaction liquid is taken out and separated to prepare the intermediate product. The furan aldehyde compound refers to a compound with furan ring as the mother nucleus structure and aldehyde group as the functional group; The intermediate product, the second catalyst, the iodine promoter, and the mixed solvent composed of organic carboxylic acid and water are mixed in another reaction kettle, carbon monoxide and hydrogen are introduced into the reaction kettle at the same time, and the final reaction liquid is obtained by heating to the end of the reaction under the second stirring condition at a temperature of 120-200 DEG C. The final reaction liquid is taken out and filtered to prepare the final product saturated dicarboxylic acid. The second catalyst is a Rh-based catalyst.

[0008] The method for preparing saturated dicarboxylic acid from a bio-based platform compound, wherein when the furan aldehyde compound is furfural, the intermediate product is tetrahydrofurfuryl alcohol, and the saturated dicarboxylic acid is heptanedioic acid and 2-methyl hexanedioic acid.

[0009] The method for preparing saturated dicarboxylic acid from a bio-based platform compound, wherein when the furan aldehyde compound is 5-hydroxymethyl furfural, the intermediate product is tetrahydrofurfuryl alcohol, and the saturated dicarboxylic acid is octanedioic acid and 2-methyl heptanedioic acid.

[0010] The method for preparing saturated dicarboxylic acid from a bio-based platform compound, wherein the iodine promoter is one or more of I2, HI, CH3I, LiI, NaI and MgI2.

[0011] In the method for preparing saturated dicarboxylic acids from the bio-based platform compound, in the step of simultaneously introducing carbon monoxide and hydrogen into the reaction vessel, the partial pressure of the carbon monoxide is 1-5 MPa and the partial pressure of the hydrogen is 0-4 MPa.

[0012] The method for preparing saturated dicarboxylic acids from the bio-based platform compound, wherein the first catalyst is one of the heterogeneous supported catalysts palladium, ruthenium, platinum, nickel, and cobalt-based catalysts.

[0013] The method for preparing saturated dicarboxylic acids from the bio-based platform compound, wherein the organic carboxylic acid in the mixed solvent is one of formic acid, acetic acid, and propionic acid.

[0014] In the method for preparing saturated dicarboxylic acids from the bio-based platform compound, the pressure of the hydrogen gas in the step of introducing hydrogen gas into the reaction vessel is 0-4 MPa.

[0015] Beneficial effects: The method provided by this invention uses renewable furanyl aldehyde compounds as raw materials, such as furfural and 5-hydroxymethylfurfural, which can be obtained from the hemicellulose and cellulose fractions of agricultural wastes such as corn cobs and bagasse, thus eliminating dependence on petroleum-based raw materials. Simultaneously, this method does not require strong alkalis or toxic oxidants (such as nitric acid, NO2, cyanide, etc.), produces no nitrogen oxide tail gas or high-salt wastewater, and generates only a small amount of waste residue, reducing environmental treatment costs by more than 80%. Furthermore, the reaction conditions of this invention are mild (temperature ≤200℃, pressure ≤9MPa), eliminating the risk of explosion and significantly reducing safety costs. The two-step process of this invention is short; the first step yields ≥98% (high-purity intermediate product), and the second step directly yields the target product through a one-step dicarbonylation, avoiding traditional multi-step reactions and separations, effectively shortening the production cycle. The yield of the target product obtained by this method (42% pimecrolic acid, 26% succinic acid) far exceeds that of the biological method (milligram level), meeting industrial-grade requirements. The process can be scaled up to the kilogram level, suitable for industrial mass production. Attached Figure Description

[0016] Figure 1 This is a flowchart of a method for preparing saturated dicarboxylic acids from a bio-based platform compound according to the present invention. Detailed Implementation

[0017] This invention provides a method for preparing saturated dicarboxylic acids from bio-based platform compounds. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0018] Please see Figure 1 , Figure 1A flowchart of a method for preparing saturated dicarboxylic acids from a bio-based platform compound provided by the present invention is shown in the figure, which includes the following steps: S10. Add furanyl aldehyde compound, first catalyst and solvent into reaction vessel and mix. Introduce hydrogen into reaction vessel and heat under first stirring condition until hydrogenation reaction is completed to obtain intermediate reaction liquid. Take out the intermediate reaction liquid and separate it to obtain intermediate product. The furanyl aldehyde compound refers to a compound with furan ring as the parent core structure and aldehyde group as the functional group. S20. The intermediate product, the second catalyst, the iodine promoter, and the mixed solvent consisting of organic carboxylic acid and water are added to another reaction vessel and mixed. Carbon monoxide and hydrogen are simultaneously introduced into the reaction vessel. Under the second stirring condition, the mixture is heated at a temperature of 120-200°C until the reaction is completed to obtain the final reaction solution. The final reaction solution is taken out and filtered to obtain the final product saturated dicarboxylic acid. The second catalyst is an Rh-based catalyst.

[0019] Specifically, in this invention, the furanyl aldehyde compound refers to a compound with a furan ring as the parent structure and an aldehyde group as the functional group. For example, the furanyl aldehyde compound can be furfural or 5-hydroxymethylfurfural, but is not limited to these. The furfural and 5-hydroxymethylfurfural are mainly derived from agricultural waste such as corn cobs and sugarcane bagasse, which are renewable resources. The method of this invention uses these renewable bio-based platform compounds as raw materials, which can completely get rid of dependence on petroleum-based raw materials.

[0020] In step S10 of this embodiment, the furan ring (unsaturated double bond) and aldehyde group (-CHO) in the furanyl aldehyde compound undergo an addition reaction with hydrogen under the action of a first catalyst to generate an intermediate product. Taking furfural as an example, furfural reacts with hydrogen to generate the corresponding intermediate product tetrahydrofurfuryl alcohol, as shown in the following reaction: C5H4O2 + 2H2 → C5H 10 O2; Taking 5-hydroxymethylfurfural as an example, 5-hydroxymethylfurfural undergoes an addition reaction with hydrogen to produce the corresponding intermediate tetrahydrofurandimethyl, as shown in the following reaction: C6H6O3 + 3H2 → C6H 12 O3. In this step, the first catalyst is a commonly used heterogeneous supported hydrogenation catalyst such as palladium, ruthenium, platinum, nickel, or cobalt-based catalyst, but is not limited thereto; the pressure of the hydrogen gas is 1-4 MPa, but is not limited thereto; the first stirring speed is 500-800 rpm, and the heating temperature is 40-100℃, but is not limited thereto.

[0021] In step S20 of this embodiment, the tetrahydrofuran ring in the intermediate product undergoes ring-opening under the action of the second catalyst RhCl3 and the iodine promoter to generate a straight-chain alcohol containing a hydroxyl group. The hydroxyl group (-CH2OH) of the straight-chain alcohol is converted into a carboxyl group by carbonylation under a carbon monoxide and hydrogen atmosphere, thereby obtaining a saturated dicarboxylic acid. Similarly, taking the intermediate product tetrahydrofurfuryl alcohol as an example, it undergoes ring-opening under the action of the second catalyst and the iodine promoter, followed by carbonylation to generate the target product pimelic acid and the byproduct 2-methyl adipic acid, as shown in the following reaction: Taking the intermediate product tetrahydrofurandimethyl as an example, it undergoes ring-opening under the action of a second catalyst and an iodine promoter, followed by carbonylation to generate the target product octanoic acid and the byproduct 2-methylheptanoic acid. The reaction is shown below: .

[0022] In this embodiment, RhCl3 is used as the second main catalyst, and its catalytic activity originates from Rh 3+ With CO, I - The active intermediate formed by (iodine accelerator), namely Rh 3+ d 6 The electronic configuration readily coordinates with CO to form reactive intermediates (such as Rh(CO)2I2). - This active intermediate can reduce the activation energy of CO bond breaking and hydroxyl carbonylation, promoting the carbonylation reaction. Based on this, this embodiment directly obtains the target product through one-step double carbonylation, avoiding the traditional multi-step reaction and separation, and effectively shortening the production cycle; at the same time, the yield of the target product obtained in this embodiment (42% pimelic acid and 26% succinic acid) far exceeds that of the biological method, meeting the requirements for industrial grade, and the process can be scaled up to the kilogram level, suitable for industrial mass production.

[0023] In some embodiments, the iodine accelerator is one or more selected from I2, HI, CH3I, LiI, NaI, and MgI2, but is not limited thereto. Preferably, the iodine accelerator is I2.

[0024] In some embodiments, during the step of simultaneously introducing carbon monoxide and hydrogen into the reactor, the partial pressure of the carbon monoxide is 1-5 MPa, and the partial pressure of the hydrogen is 0-4 MPa. Preferably, the partial pressure of the carbon monoxide is 3 MPa, and the partial pressure of the hydrogen is 2 MPa.

[0025] In some embodiments, the second stirring speed is 600-800 rpm, but is not limited thereto.

[0026] The present invention will be further explained and illustrated below through specific embodiments: Example 1 A method for preparing pimelic acid based on furfural, comprising the steps of: Furfural, nickel-cobalt bimetallic nanoparticle catalyst and deionized water were added to a reaction vessel and mixed. Hydrogen gas at a pressure of 2 MPa was introduced into the reaction vessel and heated at 100°C under stirring at 600 rpm until the hydrogenation reaction was completed to obtain an intermediate reaction liquid. The intermediate reaction liquid was taken out and separated to obtain the intermediate product tetrahydrofurfural alcohol. 0.102 g of tetrahydrofurfuryl alcohol, 0.1 mmol of rhodium trichloride hydrate (RhCl3), 0.7 mmol of elemental iodine (I2), and a mixed solvent consisting of 1 ml of acetic acid and 0.5 ml of water were added to another reaction vessel and mixed. Carbon monoxide at a pressure of 3 MPa and hydrogen at a pressure of 2 MPa were simultaneously introduced into the reaction vessel. The mixture was heated to 180 °C under stirring at 700 rpm until the reaction was completed, and the final reaction solution was obtained. The final reaction solution was removed and centrifuged and filtered to obtain the target product pimelic acid and the byproduct 2-methyladipic acid.

[0027] The concentration of pimelic acid was detected using a Waters H-Class series high-performance liquid chromatograph (RID detector, Alltech OA-1000 Organic Acids HPLC (300mm x 6.5mm), flow rate 0.6mL / min, column temperature 60℃, mobile phase 0.1g / L dilute sulfuric acid).

[0028] Plotting a standard curve using the external standard method: Prepare pimelic acid standard solutions of different concentrations (e.g., 0.1, 0.2, 0.5, 1.0, 2.0 mmol / L), inject and detect the solutions, plot the standard curve with concentration as the x-axis and peak area as the y-axis, and obtain the linear regression equation; The sample filtrate was injected for analysis. Based on the peak area, the actual concentration of pimelic acid in the sample was calculated using the standard curve, and then the yield was calculated. The yield of pimelic acid = actual yield of pimelic acid / theoretical yield of pimelic acid * 100%. Through calculation, the yield of the target product pimelic acid in this embodiment is 42%, and the yield of the by-product 2-methyl adipic acid is 37%.

[0029] In order to screen for an effective second catalyst, this invention also compared the following three common carbonylation metal catalysts: RuCl3, PdCl2, and IrCl3.

[0030] Comparative Example 1 A method for preparing pimelic acid based on furfural is provided. The preparation steps are basically the same as those in Example 1, except that the second catalyst is replaced with RuCl3.

[0031] Comparative Example 2 A method for preparing pimelic acid based on furfural is provided. The preparation steps are basically the same as those in Example 1, except that the second catalyst is replaced with PdCl2.

[0032] Comparative Example 3 A method for preparing pimelic acid based on furfural is provided. The preparation steps are basically the same as those in Example 1, except that the second catalyst is replaced with IrCl3.

[0033] The yields of the target product pimelic acid and the byproduct 2-methyl adipic acid in Comparative Examples 1-3 were calculated using the same method as in Example 1, and the results are shown in Table 1: Table 1 Catalyst Screening Results

[0034] As can be seen from the data in Table 1, RhCl3 is the most effective main catalyst, and its catalytic activity originates from Rh 3+ With CO, I - The resulting active intermediate, namely Rh 3+ d 6 Its electronic configuration readily coordinates with CO to form reactive intermediates (such as Rh(CO)₂I₂⁻). These reactive intermediates can lower the activation energy for CO bond cleavage and hydroxyl carbonylation, thus promoting the carbonylation reaction. However, RuCl₃, due to the presence of Ru... 3+ d 5 The electronic configuration of PdCl2 has weak coordination ability with CO, making it unable to form highly efficient active catalytic species; Pd in ​​PdCl2 2+ (d) 8 It is more likely to catalyze the hydrogenation of olefins than the carbonylation of alcohols; IrCl3 contains Ir 3+ d 6 Although the electronic configuration is similar to Rh 3+ They have the same electronic configuration, but a larger ionic radius (Ir). 3+ Radius 82 pm, Rh 3+ (Radius 75 pm), unable to efficiently activate CO bonds.

[0035] The role of iodine promoters is to enhance the activity of the second catalyst and promote the formation of active intermediates. In order to screen for better iodine promoters, this invention also tested and compared the following five iodine promoters: HI, CH3I, LiI, NaI, and MgI2.

[0036] Example 2 A method for preparing pimelic acid based on furfural is provided, and the preparation steps are basically the same as those in Example 1, except that the iodine accelerator is replaced with HI.

[0037] Example 3 A method for preparing pimelic acid based on furfural is provided. The preparation steps are basically the same as those in Example 1, except that the iodine accelerator is replaced with CH3I.

[0038] Example 4 A method for preparing pimelic acid based on furfural is provided, and the preparation steps are basically the same as those in Example 1, except that the iodine accelerator is replaced with LiI.

[0039] Example 5 A method for preparing pimelic acid based on furfural is provided, and the preparation steps are basically the same as those in Example 1, except that the iodine accelerator is replaced with NaI.

[0040] Example 6 A method for preparing pimelic acid based on furfural is provided, and the preparation steps are basically the same as those in Example 1, except that the iodine accelerator is replaced with MgI2.

[0041] The yields of the target product pimelic acid and the byproduct 2-methyl adipic acid in Examples 2-6 were calculated using the same method as in Example 1, and the results are shown in Table 2. Table 2. Screening results of iodine accelerators

[0042] As can be seen from the data in Table 2, I2 is the best iodine promoter because I2 can oxidize Rh. 3+ To higher price states (such as Rh) 5 + ), while providing I - It forms a stable active intermediate (Rh(CO)2I2) with Rh. - The HI in Example 2 provides the best catalytic effect and can also suppress the methylation side reaction of the tetrahydrofuran ring. - But H + It inhibits the formation of Rh complexes, leading to a decrease in activity; although CH3I in Example 3 is a common carbonylation cocatalyst, it is prone to methylation side reactions in this system, reducing the selectivity of the target product; LiI in Example 4... + As an alkali metal ion, it cannot form a stable complex with Rh, and its catalytic effect is weaker than that of I2; in Example 5, NaI contains Na... + Ionic radius greater than Li + The effect of promoting the stability of Rh complexes is weaker; in Example 6, MgI2 has a weaker effect on the stability of Rh complexes. 2+ It is a divalent cation and readily reacts with OH-. - The formation of Mg(OH)2 precipitate consumes raw materials and reduces the yield.

[0043] The above experimental data have confirmed that I2 is the optimal iodine promoter. This invention further investigated the effect of I2 dosage (0.5, 0.6, 0.8 mmol) on yield through examples.

[0044] Example 7 A method for preparing pimelic acid based on furfural is provided. The preparation steps are basically the same as those in Example 1, except that the amount of I2 is changed to 0.5 mmol.

[0045] Example 8 A method for preparing pimelic acid based on furfural is provided. The preparation steps are basically the same as those in Example 1, except that the amount of I2 is changed to 0.6 mmol.

[0046] Example 9 A method for preparing pimelic acid based on furfural is provided. The preparation steps are basically the same as those in Example 1, except that the amount of I2 is changed to 0.8 mmol.

[0047] The yields of the target product pimelic acid and the byproduct 2-methyl adipic acid in Examples 6-8 were calculated using the same method as in Example 1, and the results are shown in Table 3. Table 3. Screening Results of I2 Dosage

[0048] As can be seen from the data in Table 3, the optimal amount of I2 in this example is 0.7 mmol, at which point the concentration of the active intermediate is the highest and the side reactions are the fewest; the amount of I2 used in Examples 6 and 7 was insufficient: I - The concentration is too low to form enough Rh(CO)2I2. - The active intermediate exhibits lower catalytic activity compared to Example 1; I2 was used in excess in Example 8: excess I - It will form a stable RhI4 complex with Rh compounds. 2- This reduces catalytic activity.

[0049] Since temperature affects reaction rate and equilibrium, this invention further investigated the yield variation in the carbonylation reaction within the temperature range of 150-190°C.

[0050] Example 9 A method for preparing pimelic acid based on furfural is provided. The preparation steps are basically the same as those in Example 1, except that the carbonylation reaction temperature is changed to 150°C.

[0051] Example 10 A method for preparing pimelic acid based on furfural is provided. The preparation steps are basically the same as those in Example 1, except that the carbonylation reaction temperature is changed to 160°C.

[0052] Example 11 A method for preparing pimelic acid based on furfural is provided. The preparation steps are basically the same as those in Example 1, except that the carbonylation reaction temperature is changed to 170°C.

[0053] Example 12 A method for preparing pimelic acid based on furfural is provided. The preparation steps are basically the same as those in Example 1, except that the carbonylation reaction temperature is changed to 190°C.

[0054] Example 13 A method for preparing pimelic acid based on furfural is provided. The preparation steps are basically the same as those in Example 1, except that the carbonylation reaction temperature is changed to 200°C.

[0055] The yields of the target product pimelic acid and the byproduct 2-methyl adipic acid in Examples 9-13 were calculated using the same method as in Example 1, and the results are shown in Table 4. Table 4 Results of reaction temperature optimization

[0056] As can be seen from the data in Table 4, the optimal reaction temperature of this invention is 180℃. At this temperature, the ring-opening reaction rate matches the carbonylation reaction rate, the catalyst activity is stable, and side reactions are minimized. In Example 9, the temperature was too low: the reaction rate was slow, the tetrahydrofuran ring opening was incomplete (ring-opening rate only 60%-70%), and the feed conversion rate was low. In Examples 10 and 11, the temperature was slightly increased, and the ring-opening rate increased to 80%-85%, but the carbonylation reaction still did not reach the optimal rate. In Example 12, the temperature was too high, at which point the Rh catalyst began to deactivate (Rh... 3+ Reduced to metallic Rh 0 The activity of the Rh catalyst decreased as the carbon was deposited on the reactor wall. In Example 13, the temperature was further increased, and the activity of the Rh catalyst decreased further. At this time, the raw material tetrahydrofurfuryl alcohol began to decompose (generating CO2, methane, etc.), and the carbon loss rate reached more than 30%, and the yield decreased further.

[0057] CO is the carbon source for carbonylation, and H2 is used to maintain catalyst activity (preventing Rh). 0 (Deposition), this invention further investigated the effect of different CO / H2 pressure ratios through experiments.

[0058] Example 14 A method for preparing pimelic acid based on furfural is provided. The preparation steps are basically the same as those in Example 1, except that "carbon monoxide at a pressure of 3 MPa and hydrogen at a pressure of 2 MPa are simultaneously introduced into the reaction vessel" is modified to "carbon monoxide at a pressure of 3 MPa and hydrogen at a pressure of 1 MPa are simultaneously introduced into the reaction vessel".

[0059] Example 15 A method for preparing pimelic acid based on furfural is provided. The preparation steps are basically the same as those in Example 1, except that the step of "simultaneously introducing carbon monoxide at a pressure of 3 MPa and hydrogen at a pressure of 2 MPa into the reaction vessel" is changed to "simultaneously introducing carbon monoxide at a pressure of 4 MPa and hydrogen at a pressure of 2 MPa into the reaction vessel".

[0060] Example 16 A method for preparing pimelic acid based on furfural is provided. The preparation steps are basically the same as those in Example 1, except that "carbon monoxide at a pressure of 3 MPa and hydrogen at a pressure of 2 MPa are simultaneously introduced into the reaction vessel" is modified to "carbon monoxide at a pressure of 5 MPa and hydrogen at a pressure of 2 MPa are simultaneously introduced into the reaction vessel".

[0061] Example 17 A method for preparing pimelic acid based on furfural is provided. The preparation steps are basically the same as those in Example 1, except that "carbon monoxide at a pressure of 3 MPa and hydrogen at a pressure of 2 MPa are simultaneously introduced into the reaction vessel" is modified to "carbon monoxide at a pressure of 3 MPa and hydrogen at a pressure of 4 MPa are simultaneously introduced into the reaction vessel".

[0062] The yields of the target product pimelic acid and the byproduct 2-methyl adipic acid in Examples 14-17 were calculated using the same method as in Example 1, and the results are shown in Table 5. Table 5. Results of CO / H2 Pressure Optimization

[0063] As can be seen from the data in Table 5, the optimal CO:H2 pressure ratio of this invention is 3:2 MPa (total pressure 5 MPa). At this ratio, the CO partial pressure is sufficiently high (3 MPa) to ensure complete carbonylation of the raw materials; the H2 partial pressure (2 MPa) can maintain Rh 3+ The catalyst activity is optimized to prevent reductive deactivation, and the coordination competition between CO and H2 is balanced, thus achieving optimal catalyst activity and carbon source supply. In Example 14, the H2 partial pressure was too low to maintain Rh. 3+ Optimal activity, Rh 0 Deposition leads to reduced catalyst activity; in Examples 15 and 16, the CO partial pressure was too high, and excess CO easily forms a stable Rh(CO)4 complex with Rh. + This reduces catalytic activity; in Example 17, the H2 partial pressure was too high, and H2 would compete with CO for the coordination sites of Rh, inhibiting the carbonylation reaction.

[0064] The reaction solvent plays a crucial role in the reaction. In carbonylation reactions, acidic solvents are commonly used. Therefore, this invention further investigated the effects of different organic carboxylic acid solvents through experiments.

[0065] Example 18 A method for preparing pimelic acid based on furfural is provided, and the preparation steps are basically the same as those in Example 1, except that acetic acid is replaced with formic acid.

[0066] Example 19 A method for preparing pimelic acid based on furfural is provided, and the preparation steps are basically the same as those in Example 1, except that acetic acid is replaced with propionic acid.

[0067] Example 20 A method for preparing pimelic acid based on furfural is provided, and the preparation steps are basically the same as those in Example 1, except that acetic acid is replaced with trifluoroacetic acid.

[0068] The yields of the target product pimelic acid and the byproduct 2-methyl adipic acid from Examples 18-20 were calculated using the same method as in Example 1, and the results are shown in Table 6. Table 6 Results of reaction solvent optimization

[0069] As can be seen from the data in Table 6, the optimal reaction solvent of this invention is acetic acid. The formic acid and propionic acid in Examples 18 and 19 have relatively low yields, which may be due to the acid strength and solvent boiling point. When the reaction solvent is trifluoroacetic acid, the target product cannot be detected. The reason may be that the acidity of trifluoroacetic acid is too strong, which causes the dehalogenation of the iodide after the formation of the monoacid, so that only monocarbonylation can occur to obtain the monoacid.

[0070] Example 21 A method for preparing pimelic acid based on furfural, comprising the steps of: 5-hydroxymethylfurfural, nickel-cobalt bimetallic nanoparticle catalyst and deionized water were added to a reaction vessel and mixed. Hydrogen gas at a pressure of 2 MPa was introduced into the reaction vessel and heated at 100°C under stirring at 600 rpm until the hydrogenation reaction was completed to obtain an intermediate reaction liquid. The intermediate reaction liquid was taken out and separated to obtain the intermediate product tetrahydrofurandimethyl. 0.132 g of tetrahydrofurandiethanol, 0.1 mmol of RhCl3, 0.7 mmol of I2, and a mixed solvent consisting of 1 ml of acetic acid and 0.5 ml of water were added to another reaction vessel and mixed. Carbon monoxide at a pressure of 3 MPa and hydrogen at a pressure of 2 MPa were simultaneously introduced into the reaction vessel. The mixture was heated to 180 °C under stirring at 700 rpm until the reaction was completed, and the final reaction solution was obtained. The final reaction solution was removed and centrifuged and filtered to obtain the target product octanoic acid and the byproduct 2-methylheptanic acid.

[0071] The yields of the target product succinic acid and the byproduct 2-methylpimelic acid in this embodiment were calculated, and the results showed that the yield of succinic acid was 26% and the yield of the byproduct 2-methylpimelic acid was 24%.

[0072] Example 21 demonstrates that the dicarbonylation process of the present invention is versatile and can simultaneously prepare pimelic acid (from tetrahydrofurfuryl alcohol) and octanoic acid (from tetrahydrofurandimethyl alcohol). No core parameters need to be adjusted; only the substrate needs to be changed, which significantly enhances the industrial value of the process.

[0073] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing saturated dicarboxylic acids from a bio-based platform compound, characterized in that, Including the following steps: Furanyl aldehyde compound, first catalyst and solvent are added to a reaction vessel and mixed. Hydrogen gas is introduced into the reaction vessel and heated under first stirring conditions until the hydrogenation reaction is completed to obtain an intermediate reaction liquid. The intermediate reaction liquid is taken out and separated to obtain an intermediate product. The furanyl aldehyde compound refers to a compound with a furan ring as the parent structure and an aldehyde group as the functional group. The intermediate product is mixed with a second catalyst, an iodine promoter, and a mixed solvent consisting of an organic carboxylic acid and water in another reactor. Carbon monoxide and hydrogen are simultaneously introduced into the reactor. Under a second stirring condition, the mixture is heated at a temperature of 120-200°C until the reaction is complete to obtain the final reaction solution. The final reaction solution is removed and filtered to obtain the final product, a saturated dicarboxylic acid. The second catalyst is an Rh-based catalyst.

2. The method for preparing saturated dicarboxylic acids from bio-based platform compounds according to claim 1, characterized in that, When the furanyl aldehyde compound is furfural, the intermediate product is tetrahydrofurfuryl alcohol, and the saturated dicarboxylic acid is heptanic acid and 2-methyl adipic acid.

3. The method for preparing saturated dicarboxylic acids from bio-based platform compounds according to claim 1, characterized in that, When the furanyl aldehyde compound is 5-hydroxymethylfurfural, the intermediate product is tetrahydrofurandimethylethanol, and the saturated dicarboxylic acid is octanedioic acid and 2-methylheptanediic acid.

4. The method for preparing saturated dicarboxylic acids from bio-based platform compounds according to any one of claims 1-3, characterized in that, The iodine accelerator is one or more of I2, HI, CH3I, LiI, NaI, and MgI2.

5. The method for preparing saturated dicarboxylic acids from bio-based platform compounds according to any one of claims 1-3, characterized in that, In the step of simultaneously introducing carbon monoxide and hydrogen into the reactor, the partial pressure of the carbon monoxide is 1-5 MPa, and the partial pressure of the hydrogen is 0-4 MPa.

6. The method for preparing saturated dicarboxylic acids from bio-based platform compounds according to claim 5, characterized in that, The first catalyst is one of the commonly used heterogeneous supported hydrogenation catalysts, such as palladium, ruthenium, platinum, nickel, and cobalt-based catalysts.

7. The method for preparing saturated dicarboxylic acids from bio-based platform compounds according to any one of claims 1-3, characterized in that, The organic carboxylic acid in the mixed solvent is one of formic acid, acetic acid, and propionic acid.

8. The method for preparing saturated dicarboxylic acids from bio-based platform compounds according to any one of claims 1-3, characterized in that, In the step of introducing hydrogen into the reactor, the pressure of the hydrogen is 0-4 MPa.

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