Composite titanium-based catalyst, its preparation method and application

Abstract

The application discloses a composite titanium catalyst and a preparation method and application thereof, and relates to the technical field of chemical materials.The method comprises the following steps: S1: dissolving a titanate, a group IIIA compound, a group IVA compound and a rare earth organic salt in an organic solvent, and obtaining an intermediate product through reaction I; and S2: mixing the intermediate product with an organic phosphate, and obtaining the composite titanium catalyst through reaction II.The titanium catalyst prepared by the application has better stability, is resistant to hydrolysis, has high activity, and has a simple preparation process, and can be stored for a long time; the polyester product prepared by the application has good color and transparency, can reduce heavy metal pollution, has a lower production cost than the conventional antimony catalyst, and has a good industrial application prospect and value.

Description

Technical Field

[0001] This invention belongs to the field of chemical materials technology, and particularly relates to a composite titanium catalyst, its preparation method, and its application. Background Technology

[0002] Polyesters are a general term for polymers obtained by the condensation polymerization of polyols and polyacids. They primarily refer to polyethylene terephthalate (PET), but also conventionally include linear thermoplastic resins such as polybutylene terephthalate (PBT) and polyarylates. They are a class of polymers with excellent properties and wide applications. Currently, they are widely used in fibers, plastics, films, and other fields. With the rapid depletion of petroleum resources, polymers formed using renewable bio-based monomers from nature represent a major direction for future development.

[0003] The structural schematics of bio-based furanyl dicarboxylic acid (2,5-FDCA) and polyethylene furanyl dicarboxylate are shown below:

[0004]

[0005] Catalysts are a crucial component in the synthesis of polyfuran dicarboxylate (PFD). Currently, antimony, germanium, and titanium catalysts are the main types used in the industrialization and research of PFD. Antimony-based catalysts (including antimony trioxide, antimony acetate, and antimony glycolate) are the most common. However, because antimony is a heavy metal, antimony-based catalysts are toxic, posing health risks and environmental pollution, thus limiting the application of PFD and consequently restricting the use of antimony-based catalysts. Germanium-based catalysts exhibit moderate reactivity, fewer side reactions, and produce polyesters with good color, but their scarcity and high price limit their use. Titanium is not a heavy metal and does not pose health or environmental risks. It is abundant, inexpensive, and its catalysts are highly active. However, polyesters produced using titanium catalysts suffer from poor stability and yellowing or turbidity, further limiting their application.

[0006] Among known metal catalysts suitable for polyester synthesis, titanium is the best choice due to its non-heavy metal composition, high catalytic activity, low cost, and environmental friendliness. Titanium-based catalysts are also a research hotspot in the polyester industry. Currently, in the actual production of conventional polyesters (including PET, PTT, and PBT), tetrabutyl titanate is mostly used as a catalyst, exhibiting good catalytic performance and readily yielding high molecular weight polymers. However, it suffers from drawbacks, such as easy hydrolysis leading to partial deactivation, resulting in poor polymer thermal stability, increased terminal carboxyl group values, darker color, and turbidity.

[0007] The aforementioned drawbacks of titanate catalysts were also discovered during the research on polyfuran dicarboxylate. Therefore, how to avoid the drawbacks of titanate catalysts and improve the quality of polymers during the synthesis of polyfuran dicarboxylate has become the key to the application of titanate catalysts in the synthesis of polyfuran dicarboxylate. Summary of the Invention

[0008] This invention provides a composite titanium catalyst, its preparation method, and its application. The main purpose is to solve the technical problems of high activity, difficulty in control, easy deactivation, and yellowing or blackening, turbidity, and opacity of polymers synthesized by titanium catalysts.

[0009] On one hand, the present invention provides a method for preparing a composite titanium-based catalyst, the method comprising the following steps:

[0010] S1: Titanate, Group IIIA compounds, Group IVA compounds and rare earth organic salts are dissolved in an organic solvent and reacted in reaction I to obtain an intermediate product;

[0011] S2: The intermediate product and the organophosphate ester are reacted in reaction II to obtain the composite titanium catalyst.

[0012] Optionally, the reaction temperature of reaction I in step S1 is 70℃~90℃; the reaction temperature of reaction II in step S2 is 150℃~250℃.

[0013] Optionally, the temperature of reaction I is selected from any value of 70°C, 75°C, 80°C, 85°C, 90°C, or any range between two of them.

[0014] Optionally, the temperature of reaction II is selected from any value or a range between any two of 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C, 240°C, 245°C, and 250°C.

[0015] Optionally, the titanate ester is selected from at least one of tetramethyl titanate, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, and tetraisobutyl titanate. Tetrabutyl titanate or tetraisopropyl titanate is preferred.

[0016] Optionally, the group IIIA compound is selected from at least one of boron compounds, aluminum compounds, gallium compounds, and indium compounds. Aluminum compounds are preferred.

[0017] Optionally, the molar ratio of the titanate to the aluminum compound is 20:1 to 5.

[0018] Optionally, the molar ratio of the titanate to the aluminum compound is selected from any value of 20:1, 20:2, 20:3, 20:4, 20:5 or any range between both.

[0019] Optionally, the aluminum compound is selected from at least one of aluminum acetate, basic aluminum acetate, aluminum hypoacetate, aluminum lactate, aluminum chloride, aluminum hydroxide, hydrated hydroxylated aluminum chloride, aluminum acetylacetone, and aluminum oxalate. Basic aluminum acetate is preferred.

[0020] Optionally, the IVA group compound is selected from at least one of carbon compounds, silicon compounds, germanium compounds, tin compounds, and lead compounds. Silicon compounds and tin compounds are preferred.

[0021] Optionally, the molar ratio of the titanate to the silicon compound is 25:1 to 5.

[0022] Optionally, the molar ratio of the titanate to the silicon compound is selected from any value of 25:1, 25:2, 25:3, 25:4, 25:5 or any range between the two.

[0023] Optionally, the silicon compound is selected from at least one of tetramethyl silicate, tetraethyl silicate, tetrapropyl silicate, tetrabutyl silicate, crystalline silica, and fumed silica. Fumed silica is preferred.

[0024] Optionally, the molar ratio of the titanate to the tin compound is 20:1 to 1:5.

[0025] Optionally, the molar ratio of the titanate to the tin compound is selected from any value or a range between any two of the following: 0.2, 0.5, 1.0, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20.

[0026] Optionally, the tin compound may be a tetravalent tin compound containing tin (IV) or a divalent tin compound containing tin (II).

[0027] Optionally, the tin compound is selected from at least one of alkyltin(IV) salts, alkyltin(II) salts, dialkyltin(IV) salts, dialkyltin(II), trialkyltin(IV) salts, trialkyltin(II), aryltin(IV) and their salts, aryltin(II) and their salts, stannous oxalate, stannous octoate, and alkyltin oxide(IV). Stannous oxalate and stannous octoate are preferred.

[0028] Optionally, the molar ratio of the titanate to the rare earth organic salt is 100:1 to 5.

[0029] Optionally, the molar ratio of the titanate ester to the rare earth organic salt is selected from any value of 100:1, 100:2, 100:3, 100:4, 100:5 or any range between the two.

[0030] Optionally, the rare earth organic salt is selected from neodymium salts; the neodymium salt is selected from at least one of neodymium neodecanoate, neodymium octanoate, neodymium isooctanoate, and neodymium naphthenate. Neodymium neodecanoate is preferred.

[0031] Optionally, the molar ratio of the titanate to the organophosphate is 1:1 to 20;

[0032] Optionally, the molar ratio of the titanate to the organophosphate is selected from any value or a range between 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, and 1:20.

[0033] The organophosphate ester is selected from at least one of phenylphosphonic acid, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, tripropyl phosphite, tributyl phosphite, and triphenyl phosphite. Triethyl phosphate or trimethyl phosphate is preferred.

[0034] Optionally, the organic solvent in step S1 is an alcohol solvent, selected from at least one of methanol, ethanol, propanol, isopropanol, butanol, isobutanol, ethylene glycol, propylene glycol, and butanediol; the mass of the alcohol solvent used is 2 to 5 times the total mass of the four types of raw materials (titanium ester, group IIIA compound, group IVA compound, and rare earth organic salt) in step S1. Ethanol is preferred.

[0035] Optionally, the ratio of the alcohol solvent to the total mass of the four raw materials is selected from any value of 2, 2.5, 3, 3.5, 4, 4.5, 5 or a range between any two.

[0036] Optionally, reaction I is carried out under alkaline conditions (weakly alkaline), and the pH of the reaction system is adjusted to 7-9 using a pH adjuster; the pH adjuster is selected from at least one of ammonia water, sodium hydroxide solution, and potassium hydroxide solution. Preferably, the pH is 7-8. A 2M sodium hydroxide solution is preferably used. Adjusting the pH as described above allows for the aggregation and adsorption of elements.

[0037] Optionally, after reaction I in step S1, the intermediate product is obtained by cooling, filtering, washing, and drying; after reaction II in step S2, excess organic phosphate is removed by vacuum, the product is cooled and solidified, and then pulverized and ground to obtain the composite titanium catalyst.

[0038] The present invention performs vacuum removal of excess organic phosphate esters after reaction II to facilitate cooling and curing.

[0039] Optionally, the washing process after reaction I in step S1 includes: washing the intermediate with an ethanol-water solution with a volume ratio of 1:1, wherein the amount of ethanol-water solution used is 2 to 3 times the total mass of the four raw materials: titanate, group IIIA compound, group IVA compound, and rare earth organic salt.

[0040] The drying process following reaction I in step S1 includes: drying in a vacuum oven at 55℃~65℃ for more than 12 hours.

[0041] Optionally, the temperature of the vacuum oven is selected from any value of 55°C, 60°C, 65°C, or a range between any two.

[0042] Preferably, the ethanol aqueous solution is prepared by mixing an alcohol solvent and water in a volume ratio of 1:1.

[0043] Secondly, the present invention uses the above method to prepare a composite titanium catalyst.

[0044] Thirdly, the present invention provides the application of the above-mentioned composite titanium catalyst in the synthesis of polyfuran dicarboxylate.

[0045] Fourthly, the present invention provides a method for preparing polyfuran dicarboxylate, the method comprising the following steps: reacting reaction raw materials including furan dicarboxylic acid or its diester derivative and a diol under the presence of a catalyst to obtain polyfuran dicarboxylate, wherein the polyfuran dicarboxylate includes polyethylene furan dicarboxylate; wherein the catalyst is a composite titanium-based catalyst prepared by the above method.

[0046] In this invention, the polymerization product is polyfuran dicarboxylate, which includes polyethylene furan dicarboxylate.

[0047] Optionally, the reaction specifically includes the following steps:

[0048] S1: The furan dicarboxylic acid or its diester derivative and the diol are subjected to esterification or transesterification under reaction conditions I to obtain the esterified product;

[0049] The reaction conditions I include: a reaction temperature of 190℃~200℃, a pressure not exceeding 0.3MPa, and a reaction time of 2~4h;

[0050] S2: The esterification product in step S1 is subjected to pre-condensation under reaction condition II to obtain a pre-condensation product; the pre-condensation product is subjected to condensation reaction under reaction condition III to obtain polyfuran dicarboxylate, wherein the polyfuran dicarboxylate includes polyethylene polyfuran dicarboxylate.

[0051] The reaction conditions II include: low vacuum, reaction temperature of 210℃~220℃, and reaction time of 1h; the low vacuum is a vacuum condition of 4000~5000Pa.

[0052] The reaction conditions III include: high vacuum, reaction temperature of 230℃~240℃, and reaction time of 3~5h; the high vacuum is a vacuum condition below 300Pa.

[0053] Optionally, the reaction temperature of reaction condition I is selected from any value of 190°C, 195°C, 200°C, or any range between two of them.

[0054] Optionally, the reaction temperature of reaction condition II is selected from any value of 210°C, 215°C, 220°C, or any range between two of them.

[0055] Optionally, the reaction temperature of reaction condition III is selected from any value of 230°C, 235°C, 240°C, or any range between two of them.

[0056] Optionally, the amount of the catalyst is 0.1 to 0.5 wt% of the total mass of the polyfuran dicarboxylate.

[0057] Optionally, the amount of catalyst used is 0.2 to 0.3 wt% of the total mass of the polyfuran dicarboxylate.

[0058] Optionally, the amount of catalyst used as a percentage of the total mass of the polyfuran dicarboxylate is selected from any value of 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, or a range between any two.

[0059] Optionally, the catalyst, in powder form or in alcoholic solution form, is added to the reactants to carry out the esterification reaction.

[0060] The composite titanium catalyst prepared by the method of the present invention has excellent hydrolysis resistance. Therefore, unlike conventional catalysts, it can be added before the esterification reaction, which provides convenience for polyester synthesis.

[0061] Optionally, the reaction raw materials include a heat stabilizer, the amount of which is 0.1 to 0.5 wt% of the total mass of the polyfuran dicarboxylate; the stabilizer is added to the reaction raw materials for esterification reaction.

[0062] Preferably, the amount of heat stabilizer is 0.2 to 0.3 wt% of the total mass of the polyfuran dicarboxylate.

[0063] Optionally, the amount of heat stabilizer in the total mass of the polyfuran dicarboxylate is selected from any value of 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, or any range between both.

[0064] Optionally, the heat stabilizer includes a phosphate ester or a phosphite ester; the heat stabilizer is selected from at least one of trimethyl phosphate, triethyl phosphate, triphenyl phosphate, and triphenyl phosphite.

[0065] The furan dicarboxylate derivative is selected from dimethyl furan dicarboxylate and / or diethylene furan dicarboxylate; the diol is selected from at least one of ethylene glycol, propylene glycol, butanediol or hexanediol.

[0066] Fifthly, the present invention uses the above method to prepare a polyfuran dicarboxylate.

[0067] Compared with the prior art, the present invention has the following beneficial effects:

[0068] 1) This invention uses the agglomeration adsorption of titanium with metal elements of Group IIIA aluminum and Group IVA tin and the subsequent coordination activation of organophosphate esters at 200°C to obtain a composite catalyst, which enables the catalytic performance of different metal elements to complement and synergize with each other, effectively improves the shortcomings of titanium catalysts, and obtains high-quality polymers.

[0069] 2) The aluminum and tin used in this invention have stronger electronegativity than titanium. During compounding, the electron cloud migrates from titanium to aluminum and tin, giving aluminum and tin stronger coordination ability and making it easier for them to coordinate with esters. Therefore, they have higher activity than single aluminum or tin compound catalysts. Phosphate esters can coordinate titanium atoms, changing their electronic environment under the combined action of aluminum and tin, thus reducing the coordination ability of titanium to a certain extent. Since titanium itself has extremely high catalytic activity, reducing its coordination ability can suppress the occurrence of side reactions to a certain extent, thus resulting in better stability.

[0070] 3) The catalyst prepared by this invention has the advantages of being resistant to hydrolysis, having high activity, being simple to prepare, and being able to be stored for a long time.

[0071] 4) The present invention uses a catalyst to polymerize polyfuran dicarboxylate, which can improve the polymerization rate, reduce the amount of catalyst used, and produce polyfuran dicarboxylate products with good color and transparency, which can reduce heavy metal pollution problems. The production cost is lower than that of conventional antimony-based catalysts, and it has good industrial application prospects and value. Detailed Implementation

[0072] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0073] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0074] This invention provides a method for preparing a composite titanium-based catalyst:

[0075] 1) At room temperature, titanate, silicon compound, tin compound, aluminum compound, and rare earth organic salt are added to alcohol solvent, heated to 80°C and refluxed to dissolve the raw materials. Then, alkaline solution is added dropwise to adjust the pH value and control the pH value of the synthesis solution. After the addition is completed, the reaction continues for 1 hour. The intermediate product is obtained by filtration, washing, and drying.

[0076] The titanate ester is one or a mixture of several of tetramethyl titanate, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, and tetraisobutyl titanate. Tetrabutyl titanate or tetraisopropyl titanate is preferred.

[0077] Silicon compounds include tetramethyl silicate, tetraethyl silicate, tetrapropyl silicate, tetrabutyl silicate, silicon dioxide, and fumed silica, with fumed silica being preferred.

[0078] The molar ratio of titanate to silicon compound is 25:1 to 5.

[0079] Tin compounds include tetravalent tin compounds containing tin (IV) or divalent tin compounds containing tin (II). Examples include alkyl tin (IV) salts, alkyl tin (II) salts, dialkyl tin (IV) salts, dialkyl tin (II), trialkyl tin (IV) salts, trialkyl tin (II), aryl tin (IV) and its salts, aryl tin (II) and its salts, stannous oxalate, stannous octoate, alkyl tin oxide (IV), or one or more mixtures thereof.

[0080] The molar ratio of titanate to tin compound is 20:1 to 1:5.

[0081] Aluminum compounds include aluminum acetate, basic aluminum acetate, aluminum hypoacetate, aluminum lactate, aluminum chloride, aluminum hydroxide, hydrated hydroxylated aluminum chloride, aluminum acetylacetone, aluminum oxalate, with basic aluminum acetate being preferred.

[0082] The molar ratio of titanate to aluminum compound is 20:1 to 5.

[0083] The rare earth organic salt is preferably a neodymium salt, including neodymium neodecanoate, neodymium octanoate, neodymium isooctanoate, neodymium naphthenate, etc., with neodymium neodecanoate being the most preferred.

[0084] The molar ratio of titanate to organoravenous compound is 100:1 to 5.

[0085] The alcohol solvent includes one or a mixture of several of methanol, ethanol, propanol, isopropanol, butanol, isobutanol, ethylene glycol, propylene glycol, and butanediol. Ethanol is preferred.

[0086] The amount of alcohol solvent used is 2 to 5 times the total amount of compound fed.

[0087] The corresponding elemental compounds react under alkaline conditions, with a pH value of 7 to 9, preferably 7 to 8.

[0088] The pH adjuster includes ammonia, sodium hydroxide solution, or potassium hydroxide solution, with a 2M sodium hydroxide solution being used.

[0089] The intermediate product is required to be washed three times with a 1:1 mixture of alcohol solvent and aqueous solution, with each wash using an amount 2 to 3 times the total amount of the compound.

[0090] The drying conditions for the intermediate product are preferably drying in a vacuum oven at 55-65°C for more than 12 hours.

[0091] 2) Add the dried intermediate to the organophosphate, heat to 200℃ and reflux for 2 hours. Remove excess organophosphate under vacuum, cool, solidify, and grind to obtain the composite titanium catalyst.

[0092] The organophosphate phenylphosphonic acid, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, tripropyl phosphite, tributyl phosphite, and triphenyl phosphite are selected from at least one of the following: preferably triethyl phosphate or trimethyl phosphate.

[0093] The molar ratio of titanate to organophosphate is 1:1 to 20.

[0094] This invention provides a method for preparing polyethylene furanate: First, furanate or its diester derivative and ethylene glycol are subjected to esterification or transesterification reaction at 190-200°C, with a pressure not exceeding 0.3 MPa, for 2-4 hours to obtain the esterified product; then, pre-polymerization is carried out under low vacuum at 210-220°C for 1 hour; then, a polycondensation reaction is carried out under high vacuum at a reaction temperature of 230-240°C for 3-5 hours to obtain polyethylene furanate.

[0095] The composite titanium catalyst is added before the esterification reaction, and the amount is 0.1-0.5% based on polyfuran dicarboxylate; the phosphate ester or phosphite heat stabilizer is added before the esterification reaction, and the amount is 0.1-0.5% based on polyfuran dicarboxylate.

[0096] The furan dicarboxylate derivatives include one or two of dimethyl furan dicarboxylate and ethylene furan dicarboxylate.

[0097] The diol is at least one of ethylene glycol, propylene glycol, butanediol, or hexanediol.

[0098] The phosphate or phosphite heat stabilizer added to the reaction system includes one or more of trimethyl phosphate, triethyl phosphate, triphenyl phosphate, and triphenyl phosphite, and the total amount of phosphate is 0.1 to 0.5% of the total polymer mass, preferably 0.2 to 0.3%.

[0099] The composite catalyst can be added to the FDCA / EG mixture or the MFDCA / EG mixture in powder form or ethylene glycol solution form; or the composite catalyst can be added to the polyester to be shrunk or the low polyester in powder form or ethylene glycol solution form, with the amount of catalyst being 0.1 to 0.5% of the total mass of polyfuran dicarboxylate, preferably 0.2 to 0.3%.

[0100] Example 1

[0101] Add 200 mL of ethanol to a 500 mL four-necked flask equipped with a mechanical stirrer, condenser, and pH meter. While stirring, add 34 g (0.1 mol) of tetrabutyl titanate, 1.148 g (0.0056 mol) of stannous oxalate, 0.3333 g (0.0056 mol) of fumed silica, 2.1168 g (0.0056 mol) of basic aluminum acetate, and 0.658 g (0.001 mol) of neodymium neodecanoate. Heat to 80 °C and reflux to dissolve the raw materials. Add 2 M sodium hydroxide solution dropwise to the reaction solution. After the pH stabilizes, continue the reaction for 60 minutes. Cool and filter. Wash three times with 100 mL of 1:1 ethanol-water solution, and then dry in a vacuum oven at 55 °C for 12 hours to obtain the intermediate product.

[0102] The dried intermediate product was placed into a three-necked flask equipped with a mechanical stirrer and condenser, and 200 g of trimethyl phosphate was added. The mixture was heated to 200 °C and refluxed for 2 hours. Then, excess trimethyl phosphate was removed under vacuum to obtain a paste. The paste was cooled and solidified, then pulverized and ground to obtain the composite titanium catalyst CT-1. The performance results of the poly(ethylene furanate) product prepared using this catalyst are shown in Table 1.

[0103] Example 2

[0104] Add 200 ml of ethanol to a 500 ml four-necked flask equipped with a mechanical stirrer, condenser, and pH meter. While stirring, add 34 g (0.1 mol) of tetrabutyl titanate, 3.445 g (0.0167 mol) of stannous oxalate, 0.48 g (0.008 mol) of fumed silica, 3.78 g (0.01 mol) of basic aluminum acetate, and 1.316 g (0.002 mol) of neodymium neodecanoate. Heat to 80 °C and reflux to dissolve the raw materials. Add 2 M sodium hydroxide solution dropwise to the reaction solution. After the pH stabilizes, continue the reaction for 60 minutes. Cool and filter. Wash three times with 100 ml of 1:1 ethanol-water solution, and then dry in a vacuum oven at 55 °C for 12 hours to obtain the intermediate product.

[0105] The dried intermediate product was placed into a three-necked flask equipped with a mechanical stirrer and condenser, and 200 g of trimethyl phosphate was added. The mixture was heated to 200 °C and refluxed for 2 hours. Then, excess trimethyl phosphate was removed under vacuum to obtain a paste. The paste was cooled and solidified, then pulverized and ground to obtain the composite titanium catalyst CT-2. The performance results of the poly(ethylene furanate) product prepared using this catalyst are shown in Table 1.

[0106] Example 3

[0107] Add 250 ml of ethanol to a 500 ml four-necked flask equipped with a mechanical stirrer, condenser, and pH meter. While stirring, add 34 g (0.1 mol) of tetrabutyl titanate, 14.469 g (0.07 mol) of stannous oxalate, 0.6 g (0.01 mol) of fumed silica, 3.78 g (0.01 mol) of basic aluminum acetate, and 1.316 g (0.002 mol) of neodymium neodecanoate. Heat to 80 °C and reflux to dissolve the raw materials. Add 2 M sodium hydroxide solution dropwise to the reaction solution. After the pH stabilizes, continue the reaction for 60 minutes. Cool and filter. Wash three times with 100 ml of 1:1 ethanol-water solution, and then dry in a vacuum oven at 55 °C for 12 hours to obtain the intermediate product.

[0108] The dried intermediate product was placed into a three-necked flask equipped with a mechanical stirrer and condenser, and 200 g of trimethyl phosphate was added. The mixture was heated to 200 °C and refluxed for 2 hours. Then, excess trimethyl phosphate was removed under vacuum to obtain a paste. The paste was cooled and solidified, then pulverized and ground to obtain the composite titanium catalyst CT-3. The performance results of the poly(ethylene furanate) product prepared using this catalyst are shown in Table 1.

[0109] Example 4

[0110] Add 300 ml of ethanol to a 1000 ml four-necked flask equipped with a mechanical stirrer, condenser, and pH meter. While stirring, add 34 g (0.1 mol) of tetrabutyl titanate, 39.0922 g (0.0965 mol) of stannous octoate, 0.6 g (0.01 mol) of fumed silica, 4.536 g (0.012 mol) of basic aluminum acetate, and 1.645 g (0.0025 mol) of neodymium neodecanoate. Heat to 80 °C and reflux to dissolve the raw materials. Add 2 M sodium hydroxide solution dropwise to the reaction solution. After the pH stabilizes, continue the reaction for 60 minutes. Cool and filter. Wash three times with 100 ml of 1:1 ethanol-water solution, and then dry in a vacuum oven at 55 °C for 12 hours to obtain the intermediate product.

[0111] The dried intermediate product was placed into a three-necked flask equipped with a mechanical stirrer and condenser, and 250 g of trimethyl phosphate was added. The mixture was heated to 200 °C and refluxed for 2 hours. Then, excess trimethyl phosphate was removed under vacuum to obtain a paste. The paste was cooled and solidified, then pulverized and ground to obtain the composite titanium catalyst CT-4. The performance results of the poly(ethylene furanate) product prepared using this catalyst are shown in Table 1.

[0112] Example 5

[0113] Add 400 ml of ethanol to a 1000 ml four-necked flask equipped with a mechanical stirrer, condenser, and pH meter. While stirring, add 34 g (0.1 mol) of tetrabutyl titanate, 81.02 g (0.2 mol) of stannous octoate, 0.6 g (0.01 mol) of fumed silica, 7.56 g (0.02 mol) of basic aluminum acetate, and 1.97 g (0.003 mol) of neodymium neodecanoate. Heat to 80 °C and reflux to dissolve the raw materials. Add 2 M sodium hydroxide solution dropwise to the reaction solution. After the pH stabilizes, continue the reaction for 60 minutes. Cool and filter. Wash three times with 100 ml of 1:1 ethanol-water solution, and then dry in a vacuum oven at 55 °C for 12 hours to obtain the intermediate product.

[0114] The dried intermediate product was placed into a three-necked flask equipped with a mechanical stirrer and condenser, and 250 g of trimethyl phosphate was added. The mixture was heated to 200 °C and refluxed for 2 hours. Then, excess trimethyl phosphate was removed under vacuum to obtain a paste. The paste was cooled, solidified, pulverized, and ground to obtain the composite titanium catalyst CT-5. The performance results of the polyethylene furanate product prepared using this catalyst are shown in Table 1.

[0115] Example 6

[0116] Add 600 ml of ethanol to a 2000 ml four-necked flask equipped with a mechanical stirrer, condenser, and pH meter. While stirring, add 34 g (0.1 mol) of tetrabutyl titanate, 133.68 g (0.33 mol) of stannous octoate, 0.9 g (0.015 mol) of fumed silica, 9.45 g (0.025 mol) of basic aluminum acetate, and 2.63 g (0.004 mol) of neodymium neodecanoate. Heat to 80 °C and reflux to dissolve the raw materials. Add 2 M sodium hydroxide solution dropwise to the reaction solution. After the pH stabilizes, continue the reaction for 60 minutes. Cool and filter. Wash three times with 100 ml of 1:1 ethanol-water solution, and then dry in a vacuum oven at 55 °C for 12 hours to obtain the intermediate product.

[0117] The dried intermediate product was placed into a three-necked flask equipped with a mechanical stirrer and condenser, and 300g of trimethyl phosphate was added. The mixture was heated to 200℃ and refluxed for 2 hours. Then, excess trimethyl phosphate was removed under vacuum to obtain a paste. The paste was cooled and solidified, then pulverized and ground to obtain the composite titanium catalyst CT-6. The performance results of the poly(ethylene furanate) product prepared using this catalyst are shown in Table 1.

[0118] Examples 7-12

[0119] Examples 7-12 show the synthesis of six different poly(ethylene furanate) esters using the catalysts of Examples 1-6 and furanate dicarboxylic acid and ethylene glycol as reactants.

[0120] The specific preparation process of polyethylene furanate dicarboxylate is as follows: 300g (1.92mol) of furanate dicarboxylic acid and 214.8g (3.46mol) of ethylene glycol were added to a reactor, along with a polymerization catalyst, 0.27g (0.00192mol) of trimethyl phosphate, and 0.62g (0.00096mol) of antioxidant 168FCB. The reactor was purged with nitrogen gas three times under vacuum. Then, the nitrogen flow rate was maintained at 2L / min, and the esterification reaction was carried out at 190–200℃ for 4 hours. Pre-polymerization was then carried out at 4000–5000Pa / 210–220℃ for 1 hour. Finally, polycondensation was carried out at below 300Pa / 230–240℃ for 5 hours to obtain polyethylene furanate dicarboxylate. The product performance results are shown in Table 1.

[0121] Comparative Example 1

[0122] The difference between Comparative Example 1 and Example 7 is that the catalyst used is tetrabutyl titanate, and the product performance results are shown in Table 1.

[0123] Comparative Example 2

[0124] The difference between Comparative Example 2 and Example 7 is that antimony trioxide was used as the catalyst, and the product performance results are shown in Table 1.

[0125] Comparative Example 3

[0126] The difference between Comparative Example 3 and Example 7 is that the catalyst used is stannous octoate. The product performance results are shown in Table 1.

[0127] Comparative Example 4

[0128] The difference between Comparative Example 4 and Example 7 is that the catalyst used is basic aluminum acetate. The product performance results are shown in Table 1.

[0129] Table 1. Performance test data of polyethylene furanate dicarboxylate

[0130]

[0131] Note: The normal range for intrinsic viscosity is 0.63~0.70 dl / g;

[0132] Normal range for terminal carboxyl group content: 8~25 mol / t;

[0133] Diethylene glycol content normal range: ≤2.5wt%;

[0134] Normal range for color values: ≤8.

[0135] As shown in Table 1, the intrinsic viscosity, diethylene glycol content, and terminal carboxyl group content of the poly(ethylene furanate) synthesized by the composite titanium catalysts obtained in the six examples are all normal, and the b-value (color value) is also normal, ranging from 4.8 to 6.8.

[0136] Although the intrinsic viscosity and terminal carboxyl group content of Comparative Example 1 are normal, the diethylene glycol content and b value are significantly higher. This is likely because the titanate catalyst alone has high activity, a fast reaction rate, and obvious side reactions, resulting in a higher b value and diethylene glycol content.

[0137] Comparative Example 2 had normal terminal carboxyl group content and b-value, but its intrinsic viscosity was low and its diethylene glycol content was high. This may be because antimony trioxide used alone has insufficient activity in catalyzing the polymerization reaction of furanyl dicarboxylic acid and ethylene glycol, resulting in a low reaction rate and thus low intrinsic viscosity and good b-value.

[0138] Comparative Example 3 is closer to normal levels, but the terminal carboxyl group content is low, which will affect subsequent viscosity enhancement. Compared to the composite titanium catalyst invented in this patent, its catalytic activity is lower.

[0139] Comparative Example 4 also showed obvious insufficient catalytic activity and low intrinsic viscosity in the basic aluminum acetate.

[0140] Therefore, by selecting and fusing several metal elements, this invention greatly improves the drawbacks of the synthesis of polyfuran dicarboxylate by titanate catalysis, while maintaining the high activity of the composite catalytic system, and greatly improves the quality of the synthesized polyester product.

[0141] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0142] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a composite titanium-based catalyst, characterized in that, The method includes the following steps: S1: At room temperature, titanate, aluminum compound, silicon compound, tin compound and rare earth organic salt are dissolved in alcohol solvent, heated to 70℃~90℃ and refluxed to dissolve the raw material, then an alkaline solution is added to adjust the pH value to 7~9, and the reaction continues after the addition is complete. After filtration, the filtered solid is washed with an ethanol aqueous solution with a volume ratio of 1:1 and dried in a vacuum oven at 55℃~65℃ for more than 12 hours to obtain the intermediate product. The alcohol solvent is selected from at least one of methanol, ethanol, propanol, isopropanol, butanol, isobutanol, ethylene glycol, propylene glycol, and butanediol; the amount of alcohol solvent used is 2 to 5 times the total mass of the five types of raw materials (titanium ester, aluminum compound, silicon compound, tin compound, and rare earth organic salt) in step S1. The amount of the ethanol-water solution used is 2 to 3 times the total mass of the five types of raw materials: titanate, aluminum compound, silicon compound, tin compound, and rare earth organic salt. The molar ratio of the titanate to the aluminum compound is 20:1 to 5; the aluminum compound is selected from at least one of aluminum acetate, basic aluminum acetate, aluminum hypoacetate, aluminum lactate, aluminum chloride, aluminum hydroxide, hydrated hydroxylated aluminum chloride, aluminum acetylacetone, and aluminum oxalate. The molar ratio of the titanate to the silicon compound is 25:1 to 5; the silicon compound is selected from at least one of tetramethyl silicate, tetraethyl silicate, tetrapropyl silicate, tetrabutyl silicate, crystalline silica, and fumed silica. The molar ratio of the titanate to the tin compound is 20:1 to 1:5; the tin compound is a tetravalent tin compound containing tin (IV) or a divalent tin compound containing tin (II); the tin compound is selected from at least one of alkyltin (IV) salts, alkyltin (II) salts, dialkyltin (IV) salts, dialkyltin (II), trialkyltin (IV) salts, trialkyltin (II), aryltin (IV) and its salts, aryltin (II) and its salts, stannous oxalate, stannous octoate, and alkyltin oxide (IV); The molar ratio of the titanate to the rare earth organic salt is 100:1 to 5; the rare earth organic salt is selected from neodymium salts; the neodymium salt is selected from at least one of neodymium neodecanoate, neodymium octanoate, neodymium isooctanoate, and neodymium naphthenate. S2: The intermediate product and the organophosphate ester are reacted at 150~250℃, excess organophosphate ester is removed under vacuum, cooled and solidified, and then crushed and ground to obtain the composite titanium catalyst.

2. The method for preparing a composite titanium catalyst according to claim 1, characterized in that, The titanate is selected from at least one of tetramethyl titanate, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, and tetraisobutyl titanate.

3. The method for preparing a composite titanium catalyst according to claim 1, characterized in that, The molar ratio of the titanate to the organophosphate is 1:1 to 20; The organophosphate is selected from at least one of phenylphosphonic acid, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, tripropyl phosphite, tributyl phosphite, and triphenyl phosphite.

4. The method for preparing a composite titanium catalyst according to claim 1, characterized in that, In step S1, the subsequent reaction is added dropwise under alkaline conditions, and a pH adjuster is used to adjust the pH of the reaction system to 7-9; the pH adjuster is selected from at least one of ammonia water, sodium hydroxide solution, and potassium hydroxide solution.

5. The composite titanium catalyst prepared by the method according to any one of claims 1-4.

6. The application of the composite titanium catalyst according to claim 5 in the synthesis of polyfuran dicarboxylate.

7. A method for preparing polyfuran dicarboxylate, characterized in that, The method includes the following steps: reacting reaction raw materials comprising furan dicarboxylic acid or its diester derivative and a diol in the presence of a catalyst to obtain polyfuran dicarboxylic acid ester; wherein the catalyst is a composite titanium catalyst prepared by the method of any one of claims 1-4.

8. The method for preparing polyfuran dicarboxylate according to claim 7, characterized in that, The reaction specifically includes the following steps: S1: The furan dicarboxylic acid or its diester derivative and the diol are subjected to esterification or transesterification under reaction conditions I to obtain the esterified product; The reaction conditions I include: a reaction temperature of 190℃~200℃, a pressure not exceeding 0.3MPa, and a reaction time of 2~4h; S2: The esterification product in step S1 is subjected to pre-condensation under reaction condition II to obtain a pre-condensation product; the pre-condensation product is subjected to condensation reaction under reaction condition III to obtain polyfuran dicarboxylate, wherein the polyfuran dicarboxylate includes polyethylene polyfuran dicarboxylate. The reaction conditions II include: low vacuum, reaction temperature of 210℃~220℃, and reaction time of 1h; the low vacuum is a vacuum condition of 4000~5000Pa. The reaction conditions III include: high vacuum, reaction temperature of 230℃~240℃, and reaction time of 3~5h; the high vacuum is a vacuum condition below 300Pa.

9. The method for preparing polyfuran dicarboxylate according to claim 7, characterized in that, The amount of catalyst used is 0.1 to 0.5 wt% of the total mass of the polyfuran dicarboxylate.

10. The method for preparing a polyfuran dicarboxylate according to claim 7, characterized in that, The amount of catalyst used is 0.2 to 0.3 wt% of the total mass of the polyfuran dicarboxylate.

11. The method for preparing polyfuran dicarboxylate according to claim 7, characterized in that, The catalyst, in powder form or in alcoholic solution form, is added to the reaction raw materials to carry out the esterification reaction.

12. The method for preparing polyfuran dicarboxylate according to claim 7, characterized in that, The reaction raw materials include a heat stabilizer, and the amount of the heat stabilizer is 0.1 to 0.5 wt% of the total mass of the polyfuran dicarboxylate; the heat stabilizer is added to the raw materials to carry out the esterification reaction.

13. The method for preparing a polyfuran dicarboxylate according to claim 12, characterized in that, The amount of heat stabilizer used is 0.2 to 0.3 wt% of the total mass of the polyfuran dicarboxylate.

14. The method for preparing polyfuran dicarboxylate according to claim 12, characterized in that, The heat stabilizer includes a phosphate ester or a phosphite ester; the heat stabilizer is selected from at least one of trimethyl phosphate, triethyl phosphate, triphenyl phosphate, and triphenyl phosphite. The furan dicarboxylate derivative is selected from dimethyl furan dicarboxylate and / or diethylene furan dicarboxylate; the diol is selected from at least one of ethylene glycol, propylene glycol, butanediol or hexanediol.

15. The polyfuran dicarboxylate prepared by the method of claim 7 or 12.

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