A furan-based polyester catalyst and its preparation method

Abstract

This invention discloses a furan-based polyester catalyst and its preparation method. The furan-based polyester catalyst is a 2,5-furan dicarboxylic acid metal compound with the general formula L-M. n+ L is a furan carboxylic acid ligand, with -COO at positions 2 and 5 of its furan ring, respectively. ‑ -COOH, -COO(CH2) x OH group, -COO(CH2) x It is attached to any one of the (OH)2 groups, and at least one -COO group. ‑ Connected; M n+ The catalyst is one of the following metal ions: calcium, zinc, germanium, antimony, tin, and titanium, where n is an integer from 2 to 5 and x is an integer from 2 to 16. The furan-based polyester catalyst can be used for the polyester synthesis of 2,5-furan dicarboxylic acid and C2-C16 straight-chain and branched diols. The furan-based polyester catalyst provided by this invention has the advantages of being free of non-polymerizable unit impurities and having high catalytic efficiency, making it a novel type of furan-based bio-based polyester catalyst.

Description

Technical Field

[0001] This invention relates to the field of organic chemistry, and in particular to a furan-based polyester catalyst and its preparation method. Background Technology

[0002] 2,5-Furandicarboxylic acid (FDCA), as a bio-based platform compound that is more renewable and biosafety-friendly than petroleum-based benzene ring carboxylic acids, has been listed by the U.S. Department of Energy as one of the twelve most promising bio-based platform compounds and has received widespread attention in the past 20 years. Ester compounds prepared by FDCA and alkyl alcohols have been used in plasticizers (Liu Zhichun et al., Optimization of esterification reaction of bio-based plasticizer 2,5-furandicarboxylate using response surface methodology, 2018) and nucleating agents (Yan Zhuoran et al., Study on synergistic regulation of polylactic acid crystallization behavior by didecyl 2,5-furandicarboxylate and talc, 2021). Poly(2,5-furandicarboxylate) (PEF) synthesized by FDCA and ethylene glycol is currently a hot topic in bio-based ester polyester research. PEF has similar physicochemical properties to traditional polyethylene terephthalate (PET), but it has advantages in terms of barrier properties against water, carbon dioxide, and oxygen. It is an excellent bio-based polyester product with good application prospects in the field of packaging materials such as bottles and films.

[0003] Besides synthesizing polyesters with ethylene glycol, FDCA can also synthesize polyesters or copolyesters with other alcohols such as butanediol and glycerol. Currently, commonly used catalysts for FDCA polyester synthesis include organic and inorganic metal catalysts such as Sb₂O₃, Zn(OAc)₂, ZnCl₂, Ca(OAc)₂, PbO, tetrabutyl phthalate, and stannous oxalate (CN 102453242 B; Jia Shuyong et al., Stannous Oxalate: A New Catalyst for the Synthesis of Polypropylene Terephthalate, 2007). However, dedicated catalysts for furan-based bio-based polyesters have not yet been reported. In the synthesis of furan-based polyesters, the above catalysts, using titanium (Ti), antimony (Sb), and tin (Sn) based polyethylene terephthalate (PET) catalysts, result in furan-based polyesters with deep color and a wide molecular weight distribution, thus affecting their various properties. Therefore, it is necessary to develop a new dedicated catalyst for furan-based polyesters to improve polymerization efficiency and polymer properties. Summary of the Invention

[0004] The main objective of this invention is to provide a furan-based polyester catalyst and its preparation method, which improves the reaction rate of the catalyst when catalyzing the polymerization reaction of furan-based reactive substrates, thereby increasing polymerization efficiency and reducing polyester color.

[0005] To achieve the aforementioned objectives, the present invention provides a furan-based polyester catalyst and its preparation method.

[0006] In a first aspect, the present invention provides a furan-based polyester catalyst, wherein the catalyst is a 2,5-furan dicarboxylic acid metal compound with the general formula LM. n+ Wherein, L is a furan carboxylic acid ligand having the structure shown in formula (I), formula (II) and / or formula (III), and M n+ For metal ions, n is an integer from 2 to 5;

[0007]

[0008] In equation (Ⅰ), R1 is selected from -O(CH2). x OH, -O(CH2) x Any of the (OH)2 groups; x is an integer from 2 to 16.

[0009] Furthermore, the metal ions include ions of metals such as calcium (Ca), zinc (Zn), germanium (Ge), antimony (Sb), tin (Sn), and titanium (Ti).

[0010] Furthermore, the molar ratio of M to oxygen (O) in the catalyst is 1:5 to 1:35.

[0011] Furthermore, the -O(CH2) x The OH group originates from alkyl diols with 2 to 16 carbon atoms, and further from straight-chain or branched alkyl diols such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, decanediol, undecyldiol, dodecyldiol, tetradecyldiol, and hexadecyldiol.

[0012] Furthermore, the -O(CH2) x The (OH)2 group originates from alkyl triols with 3 to 16 carbon atoms, and further from straight-chain or branched alkyl triols such as glycerol, butanetriol, pentatriol, hexanetriol, heptanetriol, octanetriol, nonanetriol, decanetriol, dodecyltriol, and hexadecyltriol.

[0013] Furthermore, the catalyst can be used for the polyester synthesis catalysis of 2,5-furandicarboxylic acid and alkyl diols or alkyl triols, wherein the alkyl group of the alkyl diol or alkyl triol is a C2 to C16 alkyl group.

[0014] Furthermore, the alkyl diols specifically include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, decanediol, undecyldiol, dodecyldiol, tetradecyldiol, hexadecyldiol, etc.

[0015] Furthermore, the alkyltriols specifically include glycerol, butanetriol, pentatriol, hexanetriol, heptanetriol, octanetriol, nonanetriol, decanetriol, dodecyltriol, hexadecyltriol, etc.

[0016] Secondly, the present invention also provides a method for preparing the above-mentioned furan-based polyester catalyst, used to prepare LM synthesized from furan-based carboxylic acid ligands having the structure of formula (Ⅰ) and M metal ions. n+ The catalyst specifically comprises: reacting 5-carboxy-2-furan ester with a basic sodium or potassium compound to dissolve it, generating an alkali metal salt solution of 5-methylcarboxy-2-furan ester, which then undergoes a metal ion substitution reaction with a metal compound M to generate LM. n+ By deriving the coordination structure, a furan-based polyester catalyst with ligand L structure of formula (Ⅰ) was obtained.

[0017] Furthermore, the solvent for the alkali metal salt solution is at least one of water or a protic organic solvent.

[0018] Furthermore, the solvent for the metal ion replacement reaction includes a protic organic solvent containing 0-20 wt% water.

[0019] Furthermore, the protic organic solvents include methanol, ethanol, propanol, n-butanol, ethylene glycol, glycerol, ethyl acetate, ethyl propionate, etc.

[0020] Furthermore, the concentration of ligand L in the alkali metal salt solution is 0.01–2.5 mol / L.

[0021] Furthermore, the alkaline compound of sodium or potassium is preferably selected from sodium or potassium hydroxides, carbonates, bicarbonates, etc.

[0022] Furthermore, the M metal compound used for the metal ion replacement reaction is preferably selected from calcium chloride, zinc chloride, antimony trichloride, germanium tetrachloride, tin tetrachloride, titanium tetrachloride, antimony pentachloride, etc.

[0023] Furthermore, the method for preparing the catalyst includes:

[0024] Optionally, when the metal ion M is selected from divalent ions, the molar ratio of the alkali metal salt of 5-carboxy-2-furan carboxylate to the metal compound M is 4:1 to 1:1, the reaction temperature of the metal ion replacement reaction is 4 to 70 °C, and the reaction time is 0.1 to 6 h.

[0025] Optionally, when the metal ion M is selected from trivalent ions, the molar ratio of the alkali metal salt of 5-carboxy-2-furan carboxylate to the metal compound M is 5:1 to 2:1, the reaction temperature of the metal ion replacement reaction is 10 to 75 °C, and the reaction time is 0.1 to 8 h.

[0026] Optionally, when the metal ion M is selected from tetravalent ions, the molar ratio of the alkali metal salt of 5-carboxy-2-furan carboxylate to the metal compound M is 6:1 to 3:1, the reaction temperature of the metal ion replacement reaction is 15 to 80 °C, and the reaction time is 0.1 to 10 h.

[0027] Optionally, when the metal ion M is selected from pentavalent ions, the molar ratio of the alkali metal salt of 5-carboxy-2-furan carboxylate to the metal compound M is 7:1 to 4:1, the reaction temperature of the metal ion replacement reaction is 20 to 90 °C, and the reaction time is 0.1 to 12 h.

[0028] Thirdly, the present invention also provides a method for preparing the above-mentioned furan-based polyester catalyst, used to prepare LM synthesized from furan-based carboxylic acid ligands having the structure of formula (II) and / or formula (III) and M metal ions. n+ The catalyst specifically comprises: reacting 2,5-furandicarboxylic acid with an alkali metal compound such as sodium or potassium to dissolve it, generating an alkali metal salt solution of 2,5-furandicarboxylic acid, which then undergoes a metal ion substitution reaction with a metal compound M to generate LM. n+ Precipitation yields furan-based polyester catalysts with L-structures of formula (II) and / or formula (III).

[0029] Furthermore, the alkali metal compound is preferably selected from sodium or potassium hydroxides, carbonates, bicarbonates, etc.

[0030] Furthermore, the M metal compound used for the substitution reaction is preferably selected from calcium chloride, zinc chloride, antimony trichloride, germanium tetrachloride, tin tetrachloride, titanium tetrachloride, antimony pentachloride, etc.

[0031] Furthermore, the solvent of the alkali metal salt solution includes at least one of water or a protic organic solvent.

[0032] Furthermore, the solvent for the metal ion replacement reaction is a protic organic solvent containing 0-20 wt% water.

[0033] Furthermore, the protic organic solvent includes methanol, ethanol, propanol, n-butanol, isoamyl alcohol, ethylene glycol, glycerol, etc.

[0034] Furthermore, the concentration of the ligand L in the alkali metal salt solution is 0.01–2.5 mol / L.

[0035] Furthermore, the method for preparing the catalyst includes:

[0036] Optionally, when the metal ion M is selected from divalent ions, the molar ratio of the alkali metal salt of 5-carboxy-2-furan carboxylate to the metal compound M is 3:1 to 1:2, the reaction temperature of the metal ion replacement reaction is 10 to 70°C, and the reaction time is 0.1 to 6 h.

[0037] Optionally, when the metal ion M is selected from trivalent ions, the molar ratio of the alkali metal salt of 5-carboxy-2-furan carboxylate to the metal compound M is 4:1 to 1:1, the reaction temperature of the metal ion replacement reaction is 15 to 75°C, and the reaction time is 0.1 to 8 h.

[0038] Optionally, when the metal ion M is selected from tetravalent ions, the molar ratio of the alkali metal salt of 5-carboxy-2-furan carboxylate to the metal compound M is 5:1 to 2:1, the reaction temperature of the metal ion replacement reaction is 20 to 80°C, and the reaction time is 0.1 to 20 h.

[0039] Optionally, when the metal ion M is selected from pentavalent ions, the molar ratio of the alkali metal salt of 5-carboxy-2-furan carboxylate to the metal compound M is 6:1 to 3:1, the reaction temperature of the metal ion replacement reaction is 25 to 90°C, and the reaction time is 0.1 to 24 h.

[0040] Fourthly, the present invention also provides a method for preparing the above-mentioned furan-based polyester catalyst, used to prepare LM synthesized from furan-based carboxylic acid ligands having the structures of formula (I) and (II), or formula (I) and (III), or formula (I), (II) and (III) and M metal ions. n+ The catalyst specifically comprises: reacting and dissolving 5-carboxy-2-furan carboxylate and 2,5-furandicarboxylic acid with a basic compound of sodium or potassium to generate an alkali metal salt solution of 5-carboxy-2-furan carboxylate and 2,5-furandicarboxylic acid, which then undergoes a metal ion substitution reaction with metal ions in a metal compound M to generate LM. n+ Precipitation yields furan-based polyester catalysts with ligand L structures of formula (I) and (II), or formula (I) and (III), or formula (I), (II) and (III).

[0041] Furthermore, the basic sodium or potassium compound is preferably selected from sodium or potassium hydroxides, carbonates, bicarbonates, etc.

[0042] Furthermore, the M metal compound used for the metal ion replacement reaction is preferably selected from calcium chloride, zinc chloride, antimony trichloride, germanium tetrachloride, tin tetrachloride, titanium tetrachloride, antimony pentachloride, etc.

[0043] Furthermore, the molar ratio of the 5-carboxy-2-furan carboxylate to the 2,5-furan dicarboxylic acid is 6:1 to 1:2;

[0044] Furthermore, the solvent for the alkali metal salt solution is at least one of water or a protic organic solvent.

[0045] Furthermore, the solvent for the metal ion replacement reaction is a protic organic solvent containing 0-20 wt% water.

[0046] Furthermore, the protic organic solvents include methanol, ethanol, propanol, n-butanol, isoamyl alcohol, ethylene glycol, glycerol, etc.

[0047] Furthermore, the concentration of the ligand L in the solution is 0.01–2.5 mol / L.

[0048] Furthermore, the method for preparing the catalyst includes:

[0049] Optionally, when the metal ion M is selected from divalent ions, the molar ratio of the alkali metal salts of 5-carboxy-2-furan carboxylate and 2,5-furan dicarboxylic acid to the metal compound M is 3:1 to 1:2, the reaction temperature of the metal ion replacement reaction is 10 to 70°C, and the reaction time is 0.1 to 6 h.

[0050] Optionally, when the metal ion M is selected from trivalent ions, the molar ratio of the alkali metal salts of 5-carboxy-2-furan carboxylate and 2,5-furan dicarboxylic acid to the metal compound M is 4:1 to 1:1, the reaction temperature of the metal ion replacement reaction is 15 to 75°C, and the reaction time is 0.1 to 8 h.

[0051] Optionally, when the metal ion M is selected from tetravalent ions, the molar ratio of the alkali metal salts of 5-carboxy-2-furan carboxylate and 2,5-furan dicarboxylic acid to the metal compound M is 5:1 to 2:1, the reaction temperature of the metal ion replacement reaction is 20 to 80°C, and the reaction time is 0.1 to 20 h.

[0052] Optionally, when the metal ion M is selected from pentavalent ions, the molar ratio of the alkali metal salts of 5-carboxy-2-furan carboxylate and 2,5-furan dicarboxylic acid to the metal compound M is 6:1 to 3:1, the reaction temperature of the metal ion replacement reaction is 25 to 90°C, and the reaction time is 0.1 to 24 h.

[0053] Based on the above technical solution, the beneficial effects of the present invention are at least as follows:

[0054] (1) This invention provides a novel synthetic catalyst for furan carboxylic acid polyesters, which is very suitable for catalyzing the synthesis reaction of furan polyesters.

[0055] (2) The catalyst provided by the present invention has no non-polymer unit impurities and can effectively avoid the problem of color increase caused by the addition of other groups.

[0056] (3) The catalyst provided by the present invention has the advantages of fast catalytic rate and high catalytic efficiency. Attached Figure Description

[0057] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0058] Figure 1 This is the Fourier infrared spectrum of the polymer generated in Example 36 of this invention. Detailed Implementation

[0059] Given the lack of reports on dedicated catalysts for furan-based bio-based polyesters, and the problems of furan-based polyesters with deep color and wide molecular weight distribution obtained by commonly used catalysts for polyester polymerization, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention: a furan-based polyester catalyst and its preparation method. The catalyst is a 2,5-furan dicarboxylic acid metal compound with the general formula LM. n+ L is a furan carboxylic acid ligand, with its furan ring having -COO- groups at positions 2 and 5, respectively. - -COOH, -COO(CH2) x OH group, -COO(CH2) x It is attached to any one of the (OH)2 groups, and at least one of the -COO groups. - Connected; M n+ It consists of ions from metals such as calcium, zinc, germanium, antimony, tin, and titanium. The catalyst can be used for the polyester synthesis of 2,5-furandicarboxylic acid and C2-C16 straight-chain and branched diols.

[0060] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is further illustrated below in conjunction with specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. It should be understood that the specific embodiments described herein are merely illustrative of the invention, and the experimental conditions and setting parameters therein should not be considered as limitations on the basic technical solution of this invention. Furthermore, the scope of protection of this invention is not limited to the embodiments described below. In addition, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0061] Unless otherwise specified, the raw materials and reagents used in the embodiments of this application were all purchased commercially.

[0062] It is understood that the 5-carboxy-2-furan carboxylate used in this invention may also be named 2-carboxy-5-furan carboxylate. The compounds referred to by each naming scheme are all known compounds, and the technical concept and protection scope of this invention are not affected by the naming schemes of each raw material and compound.

[0063] The technical solution of the present invention will be further described in detail below through several embodiments. However, the selected embodiments are only used to illustrate the present invention and do not limit the scope of the present invention.

[0064] Example 1

[0065] 0.1 mol of 5-((2-hydroxyethoxy)carbonyl)furan-2-carboxylic acid was reacted with 0.1 mol of sodium hydroxide in 100 mL of water until completely dissolved, with an L-ligand concentration of 1 mol / L. Then, 0.025 mol of calcium chloride (CaCl2) was added, and the reaction was carried out at 4 °C for 2 hours. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 96.52%. The catalyst was analyzed by transmission electron microscopy (TEM, with EDS function), inductively coupled plasma optical emission spectrometry (ICP-OES), and elemental analysis. EDS determined the Ca / O molar ratio to be 1:12.03, which is a semi-quantitative method. ICP-OES determined the Ca concentration, calculating its mass percentage in the catalyst to be 9.13%. Elemental analysis showed that the carbon (C) content was 43.84%, the hydrogen (H) content was 3.22%, and the oxygen (O) content was 43.81%, which translates to a Ca / O molar ratio of 1:12.02.

[0066] Example 2

[0067] The operation and testing methods in this embodiment are basically the same as those in embodiment 1, except that:

[0068] In this embodiment, the preparation method of the furan-based polyester catalyst was modified by changing the amount of calcium chloride added to 0.05 mol and the reaction temperature to 30℃. The catalyst yield was 95.67%, the Ca / O molar ratio measured by EDS was 1:12.01, and the calcium (Ca) and oxygen (O) contents measured by ICP-OES and elemental analyzer were 9.13% and 43.80%, respectively, which are converted to a Ca / O molar ratio of 1:12.02.

[0069] Example 3

[0070] The operation and testing methods in this embodiment are basically the same as those in embodiment 2, except that:

[0071] In this embodiment, the preparation method of the furan-based polyester catalyst was modified by replacing sodium hydroxide with 0.05 mol potassium carbonate and changing the reaction time to 0.1 hours. The catalyst yield was 90.35%, the Ca / O molar ratio was measured to be 1:12.2 by EDS, and the calcium (Ca) and oxygen (O) contents were measured to be 9.14% and 43.80% by ICP-OES and elemental analyzer, respectively, which are converted to a Ca / O molar ratio of 1:12.00.

[0072] Example 4

[0073] The operation and testing methods in this embodiment are basically the same as those in embodiment 2, except that:

[0074] In this embodiment, the preparation method of the furan-based polyester catalyst was modified by replacing 5-((2-hydroxyethoxy)carbonyl)furan-2-carboxylic acid with 0.25 mol, sodium hydroxide with 0.1 mol sodium bicarbonate, and the reaction solvent with 100 mL of 9:1 ethanol:water (v:v) solution. The reaction time was also changed to 6 hours. The catalyst yield was 97.21%. The Ca / O molar ratio was 1:12.04 as determined by EDS. The calcium (Ca) and oxygen (O) contents were 9.11% and 43.82% as determined by ICP-OES and elemental analysis, respectively, which translates to a Ca / O molar ratio of 1:12.05.

[0075] Example 5

[0076] 0.001 mol of 5-((2-hydroxyethoxy)carbonyl)furan-2-carboxylic acid and 0.001 mol of potassium hydroxide were reacted in 100 mL of an 8:2 ethanol:water (v:v) solution for 1 h, with an L-ligand concentration of 0.01 mol / L. Then, 0.001 mol of zinc chloride (ZnCl2) was added, and the reaction was carried out at 70 °C for 2 h. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 97.28%. The testing method was the same as in Example 1. EDS determined the Zn / O molar ratio to be 1:11.997. ICP-OES and elemental analysis showed that the zinc (Zn) and oxygen (O) contents were 14.11% and 41.41%, respectively, which were converted to a Zn / O molar ratio of 1:11.99.

[0077] Example 6

[0078] The operation and testing methods in this embodiment are basically the same as those in embodiment 5, except that:

[0079] In this embodiment, the preparation method of the furan-based polyester catalyst was modified by replacing the L ligand raw material with 0.1 mol of 5-((8-hydroxyoctyloxy)carbonyl)furan-2-carboxylic acid, changing the reaction solvent to ethylene glycol, changing the reaction temperature to 40℃, and changing the reaction time to 4 hours. The catalyst yield was 98.53%, the Zn / O molar ratio was 1:12.00 as determined by EDS, and the Zn and O contents were 10.33% and 30.39% as determined by ICP-OES and elemental analysis, respectively, which translates to a Zn / O molar ratio of 1:12.02.

[0080] Example 7

[0081] The operation and testing methods in this embodiment are basically the same as those in embodiment 6, except that:

[0082] In this embodiment, the preparation method of the furan-based polyester catalyst was modified by replacing the L ligand raw material with 0.1 mol of 5-((16-hydroxyhexadecyloxy)carbonyl)furan-2-carboxylic acid, replacing zinc chloride with calcium chloride, and changing the initial reaction solvent to a 9:1 ethylene glycol:water (v:v) solution. When adding calcium chloride, water was added to the solvent to make the ethylene glycol:water volume ratio 8:2. The catalyst yield was 99.20%, the Ca / O molar ratio measured by EDS was 1:12.05, and the Ca and O contents measured by ICP-OES and elemental analysis were 4.81% and 23.10%, respectively, which were converted to a Ca / O molar ratio of 1:12.03.

[0083] Table 1. Experimental Data of Examples 1-7

[0084]

[0085] Note: Solvent 1 is the reaction solution of furan compounds with alkaline substances of sodium or potassium; Solvent 2 is the reaction solution when compounds containing L ligands undergo metal ion displacement reactions with M metal compounds;

[0086] Among them, raw material 1: 5-((2-hydroxyethoxy)carbonyl)furan-2-carboxylic acid, raw material 2: 5-((8-hydroxyoctoxy)carbonyl)furan-2-carboxylic acid, and raw material 3: 5-((16-hydroxyhexadecoxy)carbonyl)furan-2-carboxylic acid.

[0087] Example 8

[0088] The operation and testing methods in this embodiment are basically the same as those in embodiment 1, except that:

[0089] In this embodiment, the preparation method of the furan-based polyester catalyst was modified by replacing sodium hydroxide with potassium hydroxide, M metal compound with 0.02 mol antimony chloride (SbCl3), reaction solvent with ethanol, and reaction temperature with 10℃. The catalyst yield was 98.33%, the Sb / O molar ratio was 1:12.01 as determined by EDS, and the Sb / O molar ratio was 1:12.02 as determined by ICP-OES and elemental analysis.

[0090] Example 9

[0091] The operation and testing methods in this embodiment are basically the same as those in embodiment 8, except that:

[0092] In this embodiment, the preparation method of the furan-based polyester catalyst was modified by changing the L ligand raw material to 0.12 mol 5-((6-hydroxyhexyloxy)carbonyl)furan-2-carboxylic acid, SbCl3 to 0.04 mol, the reaction solvent for adding antimony chloride to a 99:1 ethanol:water (v:v) solution, and the reaction temperature to 30℃. The catalyst yield was 98.82%, the Sb / O molar ratio was 1:12.02 as determined by EDS, and the Sb / O molar ratio was 1:12.01 as determined by ICP-OES and elemental analysis.

[0093] Example 10

[0094] The operation and testing methods in this embodiment are basically the same as those in embodiment 8, except that:

[0095] In this embodiment, the preparation method of the furan-based polyester catalyst was modified by changing the L ligand raw material to 0.1 mol 5-((14-hydroxytetradecoxy)carbonyl)furan-2-carboxylic acid, SbCl3 to 0.05 mol, the solution for adding potassium hydroxide to the reaction to be ethanol, the reaction solvent for adding antimony chloride to be ethylene glycol, the reaction temperature to be 75℃, and the reaction time to be 0.1 hours. The catalyst yield was 93.12%, the Sb / O molar ratio was 1:12.05 as determined by EDS, and the Sb / O molar ratio was 1:12.07 as determined by ICP-OES and elemental analysis.

[0096] Example 11

[0097] 0.1 mol of 5-((2,3-dihydroxypropoxy)carbonyl)furan-2-carboxylic acid and 0.1 mol of sodium bicarbonate were reacted in 100 mL of a 9:1 ethanol:water (v:v) solvent until the sodium bicarbonate was completely dissolved. The L ligand concentration was 1 mol / L. Then 0.05 mol of SbCl3 was added, and the reaction was carried out at 30 °C for 8 hours. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 98.46%. The sample was analyzed according to the method in Example 1. EDS showed that the Sb / O molar ratio was 1:21.02. ICP-OES showed that the mass percentage of Sb in the catalyst was 14.99%. Elemental analysis showed that the carbon (C) content was 39.92%, the hydrogen (H) content was 3.72%, and the oxygen (O) content was 41.37%, which translates to an Sb / O molar ratio of 1:21.01.

[0098] Example 12

[0099] 0.25 mol of 5-((3,4-dihydroxybutoxy)carbonyl)furan-2-carboxylic acid was reacted with 0.12 mol of potassium hydroxide in 100 mL of water (v:v) until the potassium hydroxide was completely dissolved, resulting in an L-ligand concentration of 2.5 mol / L. The generated potassium salt containing the L-ligand was separated from the solution and added to 20 mL of water. 0.0357 mol of antimony pentachloride (SbCl5) was dissolved in methanol and added to the above aqueous solution of the potassium salt containing the L-ligand. The reaction was carried out at 20°C for 2 hours. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 94.57%. Sample analysis was performed according to the method in Example 1. EDS showed an Sb / O molar ratio of 1:34.99, while ICP-OES and elemental analysis showed an Sb / O molar ratio of 1:35.00.

[0100] Example 13

[0101] 0.15 mol of 5-((6-hydroxyhexyloxy)carbonyl)furan-2-carboxylic acid was reacted with 0.75 mol of sodium carbonate in 70 mL of methanol. 0.03 mol of antimony pentachloride (SbCl5) was dissolved in 50 mL of methanol. The two solutions were mixed and reacted at 40 °C for 12 hours. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 96.85%. The sample was analyzed according to the method in Example 1. The Sb / O molar ratio was determined to be 1:35.00 by EDS and 1:34.98 by ICP-OES and elemental analysis.

[0102] Example 14

[0103] 0.001 mol of 5-((10-hydroxydecoxy)carbonyl)furan-2-carboxylic acid and 0.001 mol of sodium hydroxide were reacted in 100 mL of a 9:1 methanol:water (v:v) solvent to generate a sodium-containing compound with an L-ligand concentration of 0.01 mol / L. The generated sodium-containing compound with the L-ligand was separated from the solution and added to 100 mL of n-butanol. 0.25 mmol of SbCl5 was added, and the reaction was carried out at 90 °C for 0.1 h. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 96.38%. Sample analysis was performed according to the method in Example 1. EDS showed an Sb / O molar ratio of 1:34.98, while ICP-OES and elemental analysis showed an Sb / O molar ratio of 1:35.00.

[0104] Table 2. Experimental data for Examples 8-14

[0105]

[0106]

[0107] Note: Solvent 1 is the reaction solution of furan compounds with alkaline substances of sodium or potassium; Solvent 2 is the reaction solution when compounds containing L ligands undergo metal ion displacement reactions with M metal compounds;

[0108] Among them, raw material 4: 5-((6-hydroxyhexyloxy)carbonyl)furan-2-carboxylic acid, raw material 5: 5-((14-hydroxytetradecoxy)carbonyl)furan-2-carboxylic acid, raw material 6: 5-((2,3-dihydroxypropoxy)carbonyl)furan-2-carboxylic acid, raw material 7: 5-((3,4-dihydroxybutoxy)carbonyl)furan-2-carboxylic acid, raw material 8: 5-((10-hydroxydecoxy)carbonyl)furan-2-carboxylic acid, and the compounds corresponding to the other raw material designations are the same as those in Table 1 above.

[0109] Example 15

[0110] 0.012 mol of 5-((2-hydroxyethoxy)carbonyl)furan-2-carboxylic acid was reacted with 0.012 mol of sodium hydroxide in 100 mL of water to generate a sodium-containing compound with an L-ligand concentration of 0.12 mol / L. The generated sodium-containing compound with the L-ligand was separated from the solution and added to 100 mL of ethanol. 0.002 mol of titanium tetrachloride (TiCl4) was added, and the reaction was carried out at 15 °C for 2 hours. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 98.59%. Sample analysis was performed according to the method in Example 1. EDS showed a Ti / O molar ratio of 1:24.06, while ICP-OES and elemental analysis showed a Ti / O molar ratio of 1:24.02.

[0111] Example 16

[0112] 0.12 mol of 5-((3-hydroxypropoxy)carbonyl)furan-2-carboxylic acid was reacted with 0.06 mol of potassium carbonate in 100 mL of water to generate a potassium-containing compound with an L-ligand. The generated potassium-containing compound with the L-ligand was separated from the solution and added to 100 mL of a 99:1 ethanol:water (v:v) solution. 0.024 mol of titanium tetrachloride (TiCl4) was added, and the reaction was carried out at 50 °C for 2 hours. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 98.13%. Sample analysis was performed according to the method in Example 1. EDS determined the Ti / O molar ratio to be 1:24.03, while ICP-OES and elemental analysis showed a Ti / O molar ratio of 1:24.01.

[0113] Example 17

[0114] 0.12 mol of 5-((16-hydroxyhexadecyloxy)carbonyl)furan-2-carboxylic acid was reacted with 0.12 mol of potassium hydroxide in 100 mL of ethanol to generate a potassium-containing compound with an L-ligand. The generated potassium-containing compound with the L-ligand was separated from the solution and added to 100 mL of ethylene glycol. 0.04 mol of germanium tetrachloride (GeCl4) was added, and the reaction was carried out at 80 °C for 0.1 h. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 96.88%. Sample analysis was performed according to the method in Example 1. EDS showed a Ge / O molar ratio of 1:24.05, while ICP-OES and elemental analysis showed a Ge / O molar ratio of 1:24.02.

[0115] Example 18

[0116] 0.1 mol of 5-((2,3-dihydroxypropoxy)carbonyl)furan-2-carboxylic acid was reacted with 0.12 mol of sodium bicarbonate in 100 mL of a 4:5:1 methanol:ethanol:water (v:v:v) solution to generate a sodium-containing compound containing an L ligand. Then, 0.02 mol of germanium tetrachloride (GeCl4) was added, and the reaction was carried out at 40 °C for 10 hours. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 98.81%. The sample was analyzed according to the method in Example 1. The Ge / O molar ratio was determined to be 1:28.01 by EDS and 1:27.98 by ICP-OES and elemental analysis.

[0117] Example 19

[0118] 0.1 mol of 5-((3,4-dihydroxybutoxy)carbonyl)furan-2-carboxylic acid was reacted with 0.1 mol of potassium hydroxide in 100 mL of water to generate a potassium-containing compound containing an L-ligand. After separating the potassium-containing compound containing the L-ligand, it was added to 80 mL of an 8:2 methanol:water (v:v) solution, and 0.02 mol of titanium tetrachloride (TiCl4) was added. The reaction was carried out at 20 °C for 4 hours. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 97.54%. The sample was analyzed according to the method in Example 1. The Ti / O molar ratio was determined to be 1:28.05 by EDS and 1:28.03 by ICP-OES and elemental analysis.

[0119] Example 20

[0120] 0.1 mol of 5-((6-hydroxyhexyloxy)carbonyl)furan-2-carboxylic acid was reacted with 0.05 mol of sodium carbonate in 100 mL of methanol to generate a sodium-containing compound containing an L ligand. A suitable amount of water was then added to make a solvent ratio of 8:2 methanol:water (v:v). 0.02 mol of tin tetrachloride (SnCl4) was added, and the reaction was carried out at 40 °C for 4 hours. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 97.98%. Sample analysis was performed according to the method in Example 1. EDS showed a Sn / O molar ratio of 1:23.97, while ICP-OES and elemental analysis showed a Sn / O molar ratio of 1:23.98.

[0121] Example 21

[0122] 0.1 mol of 5-((10-hydroxydecoxy)carbonyl)furan-2-carboxylic acid and 0.1 mol of sodium hydroxide were reacted in 100 mL of a 4:1 ethylene glycol:water (v:v) solution to generate a sodium-containing compound with an L-ligand. After separating the sodium-containing compound with the L-ligand, it was added to 80 mL of n-butanol, and 0.02 mol of titanium tetrachloride (TiCl4) was added. The reaction was carried out at 80 °C for 4 hours. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 96.62%. The sample was analyzed according to the method in Example 1. The Sn / O molar ratio was determined to be 1:23.99 by EDS and 1:23.96 by ICP-OES and elemental analysis.

[0123] Table 3. Experimental Data Tables for Examples 15-21

[0124]

[0125] Note: Solvent 1 is the reaction solution of furan compounds with alkaline substances of sodium or potassium; Solvent 2 is the reaction solution when compounds containing L ligands undergo metal ion displacement reactions with M metal compounds;

[0126] Among them, raw material 9 is 5-((3-hydroxypropoxy)carbonyl)furan-2-carboxylic acid, and the compounds corresponding to the other raw material labels are the same as those in Table 1-2 above.

[0127] Example 22

[0128] 0.1 mol of 2,5-furandicarboxylic acid (FDCA) was reacted with 0.22 mol of sodium hydroxide in 100 mL of water to generate a sodium-containing compound containing an L ligand. 0.033 mol of calcium chloride (CaCl2) was added, and the reaction was carried out at 4 °C for 2 hours. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 99.34%. The sample was analyzed according to the method in Example 1. The Ca / O molar ratio was determined to be 1:5.02 by EDS and 1:5.00 by ICP-OES and elemental analysis.

[0129] Example 23

[0130] 0.1 mol of 2,5-furandicarboxylic acid was reacted with 0.1 mol of sodium hydroxide in 100 mL of water to generate a sodium-containing compound containing an L ligand. 0.05 mol of calcium chloride (CaCl2) was added, and the reaction was carried out at 30 °C for 0.1 hours. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 91.53%. The sample was analyzed according to the method in Example 1. The Ca / O molar ratio was determined to be 1:10.06 by EDS and 1:10.04 by ICP-OES and elemental analysis.

[0131] Example 24

[0132] The operation and testing methods of this embodiment are basically the same as those of embodiment 23, except that:

[0133] In this embodiment, the preparation method of the furan-based polyester catalyst was modified by replacing sodium hydroxide with 0.13 mol, the M metal compound with ZnCl2, and the reaction time with 6 hours. The catalyst yield was 99.82%, the Sb / O molar ratio was 1:6.27 as determined by EDS, and the Sb / O molar ratio was 1:6.26 as determined by ICP-OES and elemental analysis.

[0134] Example 25

[0135] The operation and testing methods of this embodiment are basically the same as those of embodiment 23, except that:

[0136] In this embodiment, the preparation method of the furan-based polyester catalyst was modified by replacing sodium hydride with 0.12 sodium bicarbonate, the solvent with 100 mL of 9:1 methanol:water (v:v) solution, CaCl2 with 0.05 mol, and the reaction time with 6 hours. The catalyst yield was 97.84%. The Sb / O molar ratio was 1:6.60 as determined by EDS, and 1:6.56 as determined by ICP-OES and elemental analysis.

[0137] Example 26

[0138] 0.1 mol FDCA and 0.16 mol potassium hydroxide were reacted in 100 mL ethanol to generate a potassium-containing compound containing an L ligand. A small amount of water was then added to make the solution an 8:2 ethanol:water (v:v) solution. 0.05 mol SnCl4 was added, and the reaction was carried out at 70 °C for 2 hours. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 98.35%. The sample was analyzed according to the method in Example 1. The Sn / O molar ratio was determined to be 1:19.26 by EDS and 1:19.23 by ICP-OES and elemental analysis.

[0139] Example 27

[0140] 0.12 mol FDCA and 0.14 mol potassium hydroxide were reacted in 100 mL of an 8:2 ethanol:water (v:v) solution to generate a potassium-containing compound containing an L ligand. 0.04 mol SbCl3 was added, and the reaction was carried out at 40 °C for 4 hours. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 99.15%. The sample was analyzed according to the method in Example 1. The Sb / O molar ratio was determined to be 1:10.99 by EDS and 1:10.96 by ICP-OES and elemental analysis.

[0141] Example 28

[0142] 0.12 mol FDCA and 0.12 mol potassium hydroxide were reacted in 100 mL of 8:2 ethylene glycol:water (v:v) to generate a potassium-containing compound containing L ligands. 0.02 mol SbCl5 was added, and the reaction was carried out at 40 °C for 4 hours. The reaction product was collected, washed, dried, and weighed. The yield of the prepared catalyst was 97.08%. The sample was analyzed according to the method in Example 1. The Sb / O molar ratio was 1:25.01 determined by EDS and 1:24.99 determined by ICP-OES and elemental analysis.

[0143] Table 4. Experimental data for Examples 22-28

[0144]

[0145] Note: Solvent 1 is a reaction solution of furan compounds with sodium or potassium as an alkaline substance; Solvent 2 is a reaction solution of compounds containing L ligands undergoing a metal ion displacement reaction with M metal compounds.

[0146] Examples 29-35

[0147] 0.03 mol of FDCA was mixed with different 5-carboxy-2-furan carboxylate esters to achieve a molar ratio of 6:1 to 1:2 for 5-carboxy-2-furan carboxylate esters to FDCA. Then, 0.04 mol of different basic sodium or potassium compounds were added, and the mixtures were reacted in 100 mL of different solutions. The molar ratio of the L-ligand-containing compound to the M-metal compound was 6:1 to 1:1. The reaction temperature, time, catalyst yield, and catalyst analysis results are shown in Table 5. The analytical procedures were performed according to Example 1. The experimental data for Examples 29-35 are shown in Table 5. In Example 33, potassium carbonate was added to generate a compound containing L-ligand and potassium, and then appropriate amounts of water were added to achieve a volume ratio of ethanol to water of 8:2. In Example 34, potassium hydroxide was added to generate a compound containing L-ligand and potassium, and then appropriate amounts of water were added to achieve a volume ratio of ethylene glycol to water of 9:1.

[0148] Table 5. Experimental data for Examples 29–35

[0149]

[0150] Note: Solvent 1 is the reaction solution of furan compounds with alkaline substances of sodium or potassium; Solvent 2 is the reaction solution when compounds containing L ligands undergo metal ion displacement reactions with M metal compounds;

[0151] Among them, raw material 10 is 5-((4-hydroxybutoxy)carbonyl)furan-2-carboxylic acid, and the compounds corresponding to the other raw material labels are the same as those in Tables 1-3 above.

[0152] Comparative Example 1

[0153] Using 10g FDCA and 9.9g ethylene glycol as substrates, 0.1g Sb2O3 was added as a catalyst. The reaction was carried out at 120℃ under nitrogen protection for 2h, then at 180℃ under nitrogen protection for 2h, and then under reduced pressure for 2h (150Pa) to remove excess ethylene glycol. The temperature was raised to 230℃ and under reduced pressure for 1h (100Pa). After cooling, yellow polyethylene 2,5-furan dicarboxylate (PEF) was obtained. Fourier transform infrared spectroscopy (FTIR) was performed. The intrinsic viscosity was tested using an Ubbelohde viscometer at 30±0.05℃. The copolyester was dissolved in a mixed solvent of phenol and tetrachloroethane. The intrinsic viscosity [η] of the copolyester was calculated according to formulas (1) and (2).

[0154] ηsp =(t1-t0) / t0 (1)

[0155] [η]=[(1+1.4η sp ) 1 / 2 -1] / 0.7c (2)

[0156] In the formula: t0 is the flow time of the solvent (s); t1 is the flow time of the polyester solution (s); c is the concentration of the copolyester solution, which is 5 g / L.

[0157] Furthermore, in the esterification reaction, the esterification rate (DE) of PTA was calculated based on the amount of water generated to characterize the catalyst activity. DE = V / 2.3 × 100%, where V (mL) is the amount of water generated, and 2.3 mL is the amount of water generated after the entire FDCA reaction. The test results are as follows:

[0158] The intrinsic viscosity of the generated polymer was 0.82 dL / g. The dielectric constant (DE) was 72.5% after reaction at 180℃ under reduced pressure for 0.1 h, and 98.3% after reaction at 180℃ under reduced pressure for 2 h. FTIR analysis of the generated polymer showed that the main characteristic peak was similar to that reported in previous literature, namely PEF.

[0159] Example 36

[0160] Using 10g FDCA and 9.9g ethylene glycol as substrates, 0.08g of the Sb-containing catalyst prepared in Example 8 was added. The reaction was carried out at 120°C under nitrogen protection for 2h, followed by 180°C under nitrogen protection for 2h, and then under reduced pressure for 2h (150Pa) to remove excess ethylene glycol. The temperature was then raised to 230°C and under reduced pressure for 1h (100Pa). After cooling, nearly colorless polyethylene 2,5-furandicarboxylate (PEF) was obtained. The intrinsic viscosity, DE, and other test methods were the same as those in Comparative Example 1. The intrinsic viscosity was 1.02 dL / g, the DE was 89.6% after 0.1h under reduced pressure at 180°C, and 99.8% after 2h under reduced pressure at 180°C. The resulting polymer was subjected to FTIR testing, as shown in the figure. Figure 1 As shown, the main characteristic peak is similar to that reported in existing literature, and is PEF.

[0161] Example 37

[0162] Using 10g FDCA and 9.9g ethylene glycol as substrates, 0.08g of the Sb-containing catalyst prepared in Example 34 was added. The reaction was carried out at 120℃ under nitrogen protection for 2h, followed by 180℃ under nitrogen protection for 2h, and then under reduced pressure for 2h (150Pa) to remove excess ethylene glycol. The temperature was then raised to 230℃ and under reduced pressure for 1h (100Pa). After cooling, nearly colorless polyethylene 2,5-furandicarboxylate (PEF) was obtained. The intrinsic viscosity, DE, and other test methods were the same as those for Comparative Example 1. Its intrinsic viscosity was 1.07 dL / g, and the DE was 90.7% after 0.1h under reduced pressure at 180℃ and 99.9% after 2h under reduced pressure at 180℃. The generated polymer was subjected to FTIR testing, and the main characteristic peaks were similar to those of the original polymer. Figure 1 Consistent, PEF.

[0163] By comparing Comparative Example 1 with Examples 36 and 37, it is clear that the catalyst provided by the present invention effectively avoids the problem of color increase caused by the addition of other groups, and its catalytic efficiency for the polymerization reaction of furan carboxylic acids is significantly higher than that of commonly used traditional catalysts.

[0164] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0165] All aspects, embodiments, features, and examples of this invention are to be regarded as illustrative in all respects and are not intended to limit the invention, the scope of which is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0166] The use of headings and sections in this invention is not intended to limit the invention; each section can be applied to any aspect, embodiment or feature of the invention.

[0167] Throughout this invention, wherever a composition is described as having, containing, or including specific components, or wherever a process is described as having, containing, or including specific process steps, it is contemplated that the compositions taught in this invention are also substantially composed of or comprised of the described components, and that the processes taught in this invention are also substantially composed of or comprised of the described process steps.

[0168] It should be understood that the order of the steps or the order in which specific actions are performed is not particularly important, as long as the teachings of this invention remain operable. Furthermore, two or more steps or actions can be performed simultaneously.

[0169] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements of the embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed for carrying out the invention, but rather is intended to encompass all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated otherwise, any use of the terms first, second, etc., does not indicate any order or importance, but is used to distinguish one element from another.

Claims

1. A method for synthesizing furan-based polyesters, characterized in that, The synthesis method employs a furan-based polyester catalyst to catalyze the polyester synthesis of 2,5-furandicarboxylic acid with an alkyl diol or alkyl triol. The alkyl group of the alkyl diol or alkyl triol is a C2-C16 alkyl group. The furan-based polyester catalyst is a 2,5-furandicarboxylic acid metal compound with the general formula LM. n+ Wherein, L is a furan carboxylic acid ligand having the structure shown in at least one of formulas (I), (II), and (III), and M n+ The metal ions are, where n is an integer from 2 to 5, and the metal ions include at least one of calcium ions, zinc ions, germanium ions, antimony ions, tin ions, and titanium ions. In the furan-based polyester catalyst, the molar ratio of the metal element to the oxygen element is 1:5 to 1:

35. ； （Ⅰ）； ； （Ⅱ）； ； （Ⅲ）； In equation (Ⅰ), R1 is selected from -O(CH2). x OH, -O(CH2) x Any of the (OH)2 groups, wherein the -O(CH2) group... x The (OH)2 group is derived from alkyltriols with 3 to 16 carbon atoms, where x is an integer from 2 to 16.

2. The synthesis method according to claim 1, characterized in that, The -O(CH2) x The OH group is derived from alkyl diols with 2 to 16 carbon atoms.

3. The synthesis method according to claim 2, characterized in that, The -O(CH2) x The OH group is derived from at least one of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptahydrol, octanediol, decanediol, undecyldiol, dodecyldiol, tetradecyldiol, and hexadecyldiol.

4. The synthesis method according to claim 1, characterized in that, The -O(CH2) x The (OH)2 group is derived from at least one of glycerol, butanetriol, pentatriol, hexanetriol, heptatriol, octanetriol, nonanetriol, decanetriol, dodecyltriol, and hexadecyltriol.

5. The synthesis method according to claim 1, characterized in that, The preparation method of furan-based polyester catalysts having ligands with the structure shown in formula (I) includes: 5-Carboxy-2-furanose ester is dissolved by reacting it with a basic sodium or potassium compound to form an alkali metal salt solution of 5-methylcarboxy-2-furanose ester. This solution is then reacted with a metal compound M via a metal ion substitution reaction to produce LM. n+ By determining the coordination structure, a furan-based polyester catalyst with ligand L structure of formula (Ⅰ) was obtained; Where n is an integer from 2 to 5; ； （Ⅰ）。 6. The synthesis method according to claim 5, characterized in that, The solvent for the alkali metal salt solution includes at least one of water or a protic organic solvent; And / or, the solvent for the metal ion replacement reaction includes a protic organic solvent containing 0-20 wt% water; The protic organic solvent includes one or more of methanol, ethanol, propanol, n-butanol, isoamyl alcohol, ethylene glycol, and glycerol. The concentration of ligand L in the alkali metal salt solution is 0.01~2.5 mol / L.

7. The preparation method according to claim 6, characterized in that: When the metal ion M is selected from divalent ions, the molar ratio of the alkali metal salt of the 5-carboxy-2-furan carboxylate to the metal compound M is 4:1 to 1:1, the reaction temperature of the metal ion replacement reaction is 4 to 70°C, and the reaction time is 0.1 to 6 h. When the metal ion M is selected from trivalent ions, the molar ratio of the alkali metal salt of the 5-carboxy-2-furan carboxylate to the metal compound M is 5:1 to 2:1, the reaction temperature of the metal ion replacement reaction is 10 to 75°C, and the reaction time is 0.1 to 8 h. When the metal ion M is selected from tetravalent ions, the molar ratio of the alkali metal salt of the 5-carboxy-2-furan carboxylate to the metal compound M is 6:1 to 3:1, the reaction temperature of the metal ion replacement reaction is 15 to 80°C, and the reaction time is 0.1 to 10 h. When the metal ion M is selected from pentavalent ions, the molar ratio of the alkali metal salt of the 5-carboxy-2-furan carboxylate to the metal compound M is 7:1 to 4:1, the reaction temperature of the metal ion replacement reaction is 20 to 90°C, and the reaction time is 0.1 to 12 h.

8. The synthesis method according to claim 1, characterized in that, Methods for preparing furan-based polyester catalysts having ligands of formula (II) and / or formula (III) include: 2,5-furandicarboxylic acid is dissolved by reacting it with a basic sodium or potassium compound to form an alkali metal salt solution of 2,5-furandicarboxylic acid. This solution is then reacted with a metal compound M via a metal ion substitution reaction to produce LM. n+ Coordination structures were formed and precipitated to obtain furan-based polyester catalysts with ligand L structures of formula (II) and / or formula (III). Where n is an integer from 2 to 5; ； （Ⅱ）； ； （Ⅲ）。 9. The synthesis method according to claim 8, characterized in that: The solvent for the alkali metal salt solution is at least one of water or a protic organic solvent; And / or, the solvent for the metal ion replacement reaction is a protic organic solvent containing 0-20 wt% water; The protic organic solvents include one or more combinations of methanol, ethanol, propanol, n-butanol, isoamyl alcohol, ethylene glycol, and glycerol; The concentration of ligand L in the alkali metal salt solution is 0.01~2.5 mol / L.

10. The synthesis method according to claim 9, characterized in that: When the metal ion M is selected from divalent ions, the molar ratio of the alkali metal salt of the 5-carboxy-2-furan carboxylate to the metal compound M is 3:1 to 1:2, the reaction temperature of the metal ion replacement reaction is 10 to 70°C, and the reaction time is 0.1 to 6 h. When the metal ion M is selected from trivalent ions, the molar ratio of the alkali metal salt of the 5-carboxy-2-furan carboxylate to the metal compound M is 4:1 to 1:1, the reaction temperature of the metal ion replacement reaction is 15 to 75°C, and the reaction time is 0.1 to 8 h. When the metal ion M is selected from tetravalent ions, the molar ratio of the alkali metal salt of the 5-carboxy-2-furan carboxylate to the metal compound M is 5:1 to 2:1, the reaction temperature of the metal ion replacement reaction is 20 to 80°C, and the reaction time is 0.1 to 20 h. When the metal ion M is selected from pentavalent ions, the molar ratio of the alkali metal salt of the 5-carboxy-2-furan carboxylate to the metal compound M is 6:1 to 3:1, the reaction temperature of the metal ion replacement reaction is 25 to 90°C, and the reaction time is 0.1 to 24 h.

11. The synthesis method according to claim 1, characterized in that: The preparation method of furan-based polyester catalysts having ligands with the structures shown in formula (I) and (II), or formula (I) and (III), or formula (I), (II) and (III) includes: 5-Carboxy-2-furan carboxylate and 2,5-furandicarboxylic acid are dissolved by reacting with a basic sodium or potassium compound to form an alkali metal salt solution of 5-carboxy-2-furan carboxylate and 2,5-furandicarboxylic acid. This solution is then reacted with a metal compound M via a metal ion substitution reaction to produce LM. n+ The ligand structure was precipitated to obtain a furan-based polyester catalyst with the structure of ligand L as shown in formula (I) and (II), or formula (I) and (III), or formula (I), (II) and (III); Where n is an integer from 2 to 5; ； （Ⅰ）； ； （Ⅱ）； ； （Ⅲ）。 12. The synthesis method according to claim 11, characterized in that: The molar ratio of 5-carboxy-2-furan carboxylate to 2,5-furan dicarboxylic acid is 6:1 to 1:2; The solvent for the alkali metal salt solution is at least one of water or a protic organic solvent; And / or, the solvent for the metal ion replacement reaction includes a protic organic solvent containing 0-20 wt% water; The protic organic solvent includes one or more of methanol, ethanol, propanol, n-butanol, isoamyl alcohol, ethylene glycol, and glycerol. The concentration of ligand L in the alkali metal salt solution is 0.01~2.5 mol / L.

13. The synthesis method according to claim 12, characterized in that: When the metal ion M is selected from divalent ions, the molar ratio of the alkali metal salt of the 5-carboxy-2-furan carboxylate and 2,5-furan dicarboxylic acid to the metal compound M is 3:1 to 1:2, the reaction temperature of the metal ion replacement reaction is 10 to 70°C, and the reaction time is 0.1 to 6 h. When the metal ion M is selected from trivalent ions, the molar ratio of the alkali metal salt of the 5-carboxy-2-furan carboxylate and 2,5-furan dicarboxylic acid to the metal compound M is 4:1 to 1:1, the reaction temperature of the metal ion replacement reaction is 15 to 75°C, and the reaction time is 0.1 to 8 h. When the metal ion M is selected from tetravalent ions, the molar ratio of the alkali metal salt of the 5-carboxy-2-furan carboxylate and 2,5-furan dicarboxylic acid to the metal compound M is 5:1 to 2:1, the reaction temperature is 20 to 80°C, and the reaction time is 0.1 to 20 h. When the metal ion M is selected from pentavalent ions, the molar ratio of the alkali metal salts of the 5-carboxy-2-furan carboxylate and 2,5-furan dicarboxylic acid to the metal compound M is 6:1 to 3:1, the reaction temperature of the metal ion replacement reaction is 25 to 90°C, and the reaction time is 0.1 to 24 h.

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