Titanium dioxide supported ionic liquid catalyst as well as preparation method and application thereof

Abstract

The invention discloses a titanium dioxide supported ionic liquid catalyst as well as a preparation method and application thereof, and a method for alcoholysis of 2, 5-furandicarboxylic acid polyester comprises the following step: 2, 5-furandicarboxylic acid polyester and methanol are subjected to alcoholysis reaction under the catalysis of titanium dioxide supported ionic liquid. The titanium dioxide supported ionic liquid is used as a catalyst for alcoholysis of the 2, 5-furandicarboxylic acid polyester, the titanium dioxide supported ionic liquid not only retains the advantages of good thermal stability and chemical stability, non-volatility and high catalytic activity of the ionic liquid, but also enables the catalyst to be easier for product separation, so that the catalyst is more suitable for the alcoholysis of the 2, 5-furandicarboxylic acid polyester. And more importantly, the carrier is titanium dioxide supported ionic liquid in various forms, so that more possibilities are provided for the loading of the ionic liquid.

Description

Technical Field

[0001] The present application relates to a titanium dioxide-supported ionic liquid catalyst, a preparation method and an application thereof, belonging to the field of clean catalytic technology. Background Art

[0002] 2,5-Furandicarboxylic acid-based polyesters are considered to be a kind of bio-based polyester materials with excellent properties and good development prospects. They can be prepared by the bulk polycondensation method, solution polymerization method and interfacial polymerization method from renewable resource 2,5-furandicarboxylic acid and diols. Taking polyethylene 2,5-furandicarboxylate (PEF) as an example, PEF has a similar chemical structure to petroleum-based polyethylene terephthalate (PET), so it is considered to be a durable polymer derived from traditional synthetic resources. The global market sales of bio-based polyethylene 2,5-furandicarboxylate (PEF) reached 842.1 kg in 2023 and are expected to reach 984.8 tons in 2029, with a compound annual growth rate (CAGR) of 224.59% (2023 - 2029).

[0003] Although 2,5-furandicarboxylic acid-based polyesters provide an idea for solving the excessive dependence of the traditional polyester industry on petroleum resources, this polyester is still difficult to degrade under natural conditions, which is not only unfavorable to the development of the ecological environment but also wastes resources. Therefore, the recyclable utilization of 2,5-furandicarboxylic acid-based polyesters has very realistic and important significance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for efficiently alcoholyzing 2,5-furandicarboxylic acid-based polyesters with a titanium dioxide-supported ionic liquid catalyst that has high catalytic activity, high selectivity for target products, mild alcoholysis conditions, is easy to separate products, and can be recycled.

[0005] According to one aspect of the present application, a titanium dioxide-supported ionic liquid catalyst is provided. The titanium dioxide-supported ionic liquid catalyst has the structure shown in Formula I:

[0006]

[0007] m is a positive integer, 1 ≤ m ≤ 16;

[0008] X⁻ is selected from at least one of bis(trifluoromethanesulfonyl)imide, p-toluenesulfonate, lactate, bis(trifluoromethanesulfonyl)imide, bisulfate, acetate, trifluoromethanesulfonate, 2-(2-hydroxyethoxy)acetate, phenolate, 2,2,2-trifluoroethanolate, trifluoroacetate, tetrafluoroborate;

[0009] The titanium dioxide is the carrier.

[0010] Optionally, the morphology of the titanium dioxide is selected from at least one of granular, lamellar, linear, and nanotubular.

[0011] Optionally, the size of the titanium dioxide is 5 - 100 nm.

[0012] According to another aspect of the present application, a preparation method of the titanium dioxide-supported ionic liquid catalyst described above is provided, and the preparation method includes:

[0013] Reacting a mixture containing titanium dioxide, imidazole, propanol, coupling agent, and anionic salt in Reaction I to obtain the titanium dioxide-supported ionic liquid catalyst.

[0014] Optionally, the anionic salt is selected from at least one of strontium bis(trifluoromethanesulfonate), sodium p-toluenesulfonate, sodium lactate, lithium bis(trifluoromethanesulfonimide), sodium bisulfate, sodium acetate, sodium trifluoromethanesulfonate, sodium 2-(2-hydroxyethoxy)acetate, sodium phenoxide, sodium 2-2-2-trifluoroethanolate, sodium trifluoroacetate, and sodium tetrafluoroborate.

[0015] Optionally, the mass ratio of the titanium dioxide to the imidazole is 1:0.01 - 20%.

[0016] Optionally, the mass ratio of the titanium dioxide to the coupling agent is 1:0.01 - 20%.

[0017] Optionally, the mass ratio of the imidazole to the propanol is 1:0.01 - 20%.

[0018] Optionally, the mass ratio of the imidazole to the anionic salt is 1:0.01 - 20%.

[0019] Optionally, the coupling agent is selected from at least one of silane coupling agents, titanate coupling agents, aluminate coupling agents, metal composite coupling agents, phosphate coupling agents, and borate coupling agents.

[0020] Optionally, the temperature of Reaction I is 40 - 100 °C, and the time of Reaction I is 6 - 24 h.

[0021] According to yet another aspect of the present application, an application of the titanium dioxide-supported ionic liquid catalyst described above in the alcoholysis of 2,5-furandicarboxylic acid-based polyester is provided.

[0022] Optionally, the method for alcoholyzing the 2,5-furandicarboxylic acid-based polyester includes:

[0023] In a closed reactor, reacting a mixture containing 2,5-furandicarboxylic acid-based polyester, alcohol compound, and titanium dioxide-supported ionic liquid catalyst in Reaction II to obtain a product containing 2,5-furandicarboxylic acid diol ester.

[0024] Optionally, the 2,5-furandicarboxylic acid diol ester product includes ethylene 2,5-furandicarboxylate, propylene 2,5-furandicarboxylate, and butylene 2,5-furandicarboxylate.

[0025] Optionally, the alcohol compound is selected from at least one of 1-butanol, dodecane diol, 2-butanol, methanol, ethanol, 2-propanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 3-methyl-1-butanol, 2,2-dimethyl-1-propanol, ethylene glycol, 2-methyl-2-butanol, pentane diol, hexane diol, heptane diol, 1-propanol, 3-methyl-2-butanol, propylene glycol, 2-methyl-1-butanol, butane diol, octane diol, nonane diol, decane diol, undecane diol, tridecane diol, and tetradecane diol.

[0026] Optionally, the 2,5-furandicarboxylic acid-based polyester is selected from at least one of polybutylene 2,5-furandicarboxylate, poly(pentylene 2,5-furandicarboxylate), poly(isosorbide 2,5-furandicarboxylate), polyethylene 2,5-furandicarboxylate, polypropylene 2,5-furandicarboxylate, poly(octylene 2,5-furandicarboxylate), poly(hexylene 2,5-furandicarboxylate), poly(heptylene 2,5-furandicarboxylate), poly(ethylene glycol 2,5-furandicarboxylate-co-terephthalate), poly(1,4-cyclohexanedimethanol 2,5-furandicarboxylate), and poly(2,2,4,4-tetramethyl-1,3-cyclobutanediol 2,5-furandicarboxylate).

[0027] Optionally, the mass ratio of the 2,5-furandicarboxylic acid-based polyester to the alcohol compound is 1:0.5 to 10.

[0028] Optionally, the mass ratio of the 2,5-furandicarboxylic acid-based polyester to the alcohol compound is independently selected from any ratio or the range value between any two ratios of 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, and 1:10.

[0029] Optionally, the mass ratio of the 2,5-furandicarboxylic acid-based polyester to the alcohol compound is 1:1 to 6.

[0030] Optionally, the dosage of the titanium dioxide-supported ionic liquid catalyst is 0.1 to 10% of the mass of the 2,5-furandicarboxylic acid-based polyester.

[0031] Optionally, the dosage of the titanium dioxide supported ionic liquid catalyst is independently selected from any value among 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or the range value between any two of these values based on the mass of the 2,5-furandicarboxylic acid-based polyester.

[0032] Optionally, the dosage of the titanium dioxide supported ionic liquid catalyst is 0.2 - 8% based on the mass of the 2,5-furandicarboxylic acid-based polyester.

[0033] Optionally, the temperature of Reaction II is 40 - 180 °C, and the time of Reaction II is 0.2 - 10 h.

[0034] Optionally, the temperature of Reaction II is independently selected from any value among 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C or the range value between any two of the above.

[0035] Optionally, the time of Reaction II is independently selected from any value among 0.2 h, 0.3 h, 0.4 h, 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h or the range value between any two of the above.

[0036] Optionally, the temperature of Reaction II is 50 - 150 °C, and the time of Reaction II is 0.3 - 8 h.

[0037] Optionally, the time of Reaction II is 0.5 - 6 h.

[0038] As an optional implementation manner, the present application is achieved through the following technical solutions:

[0039] In the present invention, the titanium dioxide supported ionic liquid is prepared according to the following preparation method: In the first step, various forms of nano-titanium dioxide are grafted with a coupling agent; in the second step, imidazole is further grafted on the basis of the coupling agent; in the third step, In the fourth step, the target anion is used to replace the original anion by the ion exchange method to obtain the target titanium dioxide supported ionic liquid.

[0040] The preparation process is as follows: various forms of titanium dioxide and coupling agent are added into a flask equipped with a reflux pipe and a stirring device, heated, cooled after the reaction is completed, and the primary product (1) is obtained by centrifugation; the product (1) and imidazole are added into a flask equipped with a reflux pipe and a stirring device, heated, cooled after the reaction is completed, and the product (2) is obtained by centrifugation; the product (2) and a raw material containing a hydroxyl group are added into a flask equipped with a reflux pipe and a stirring device, heated, cooled after the reaction is completed, and the product (3) is obtained by centrifugation; the product (3) and a salt containing a target anion are added into a flask equipped with a stirring device, stirred, and the titanium dioxide-supported ionic liquid described in this patent is obtained by centrifugation after the reaction is completed.

[0041] Optionally, the 2,5-furandicarboxylic acid-based polyester has the structure shown in formula (2):

[0042]

[0043] In formula (2), m is any positive integer greater than or equal to 2, and n is any positive integer greater than or equal to 2.

[0044] Optionally, m is 2, 3, 4, 5 or 6.

[0045] Optionally, when m = 2, the polyester is ethylene glycol 2,5-furandicarboxylate (PEF).

[0046] Optionally, at least one of methyl, butyl, pentyl, hexyl, tetradecyl, pentadecyl, heptyl, octyl, ethyl, undecyl, dodecyl, propyl, nonyl, decyl, tridecyl, hexadecyl is included between the titanium dioxide support and the imidazole ionic liquid.

[0047] The present invention provides a method for highly efficient alcoholysis of 2,5-furandicarboxylic acid-based polyester with a titanium dioxide-supported ionic liquid catalyst having high catalytic activity, high selectivity for the target product, mild alcoholysis conditions, easy product separation, and recyclability, including the following steps:

[0048] (1) Add the 2,5-furandicarboxylic acid-based polyester, alcohol, and titanium dioxide-supported ionic liquid catalyst into a closed reaction vessel to obtain a mixed solution;

[0049] (2) Heat the mixed solution to 40 - 180 °C, and the depolymerization time is 0.2 - 10 h;

[0050] (3) After the reaction is completed, wait for the whole system to cool to room temperature, separate to obtain the 2,5-furandicarboxylic acid diol ester product, and calculate the degradation rate of the 2,5-furandicarboxylic acid-based polyester.

[0051] As a specific implementation manner, the reaction general formula (1) of the present invention is:

[0052]

[0053] The present invention uses a titanium dioxide-supported ionic liquid as a catalyst for the alcoholysis of 2,5-furandicarboxylic acid-based polyesters. The titanium dioxide-supported ionic liquid not only retains the advantages of good thermal stability, chemical stability, non-volatility, and high catalytic activity of the ionic liquid, but also makes the catalyst easier to separate from the product, so that it can be recycled. Importantly, the carrier is a titanium dioxide-supported ionic liquid in various forms, providing more possibilities for the loading of ionic liquids.

[0054] The beneficial effects that can be produced by this application include:

[0055] 1) In the method for the alcoholysis of 2,5-furandicarboxylic acid-based polyesters provided by this application, the catalyst used is a titanium dioxide-supported ionic liquid catalyst without metal ions. This catalyst has good thermal stability and is simple and easy to obtain.

[0056] 2) The carrier provided by this application is nano-titanium dioxide in various forms, and the cation is an imidazole cation. This catalyst is used in the reaction of alcoholyzing 2,5-furandicarboxylic acid-based polyesters. It has a small dosage, good catalytic activity and catalytic efficiency. After the reaction is completed, the immobilized ionic liquid can be easily recovered, which is beneficial to the recycling of ionic liquids.

[0057] 3) Compared with the method of alcoholyzing polyesters with conventional catalysts, the immobilized catalyst provided by this application selects a titanium dioxide-supported ionic liquid catalyst, which has a small dosage, significantly improved catalytic activity and catalytic efficiency, makes the reaction conditions milder, and reduces energy consumption; this titanium dioxide-supported ionic liquid catalyst has good recyclability and is an environmentally friendly production process with good industrial application prospects. Description of the Drawings

[0058] Figure 1 It is a morphology diagram of the nano-structured titanium dioxide of this application. Detailed Embodiments

[0059] The following describes this application in detail with reference to the embodiments, but this application is not limited to these embodiments.

[0060] Unless otherwise specified, the raw materials in the embodiments of this application are all purchased through commercial channels.

[0061] The degradation rate of 2,5-furandicarboxylic acid-based polyesters is calculated according to formula (1), where m0 is the initial mass of 2,5-furandicarboxylic acid-based polyesters and m1 is the mass of undegraded 2,5-furandicarboxylic acid-based polyesters:

[0062]

[0063] The yield of the alcoholysis product is calculated according to formula (2):

[0064]

[0065] In the present invention, "room temperature" refers to 25 °C.

[0066] In the present application, a method for highly efficient alcoholysis of 2,5-furandicarboxylic acid-based polyester with a titanium dioxide-supported ionic liquid catalyst having high catalytic activity, high selectivity for target products, mild alcoholysis conditions, easy product separation, and recyclability is proposed. The titanium dioxide-supported ionic liquid is composed of imidazole cations and various anions, and the carrier is various nanostructured titanium dioxides. The structural general formula (II) is as follows:

[0067]

[0068] As Figure 1 shown, the morphologies of the nanostructured titanium dioxides include nanotubular, nanosheet-like, nanowire-like, and nanoparticle-like.

[0069] In the present application, taking the immobilization of 3-hydroxypropylimidazolium bis(trifluoromethanesulfonate) on nanosheet titanium dioxide as an example, it is prepared according to the following preparation method:

[0070] (1) Disperse 1 g of nanosheet titanium dioxide in a toluene solution, add 0.5 ml of 3-chloropropyltriethoxysilane, stir at 150 rpm, react at 100 °C for 6 h, and reflux under N2 protection.

[0071] (2) After centrifuging the reaction product, disperse it in a toluene solution, add 0.5 g of imidazole, stir at 150 rpm, react at 100 °C for 24 h, and reflux under N2 protection.

[0072] (3) After centrifuging the reaction product, disperse it in a toluene solution, add 0.5 g of propanol, stir at 150 rpm, react at 100 °C for 18 h, and reflux under N2 protection.

[0073] (4) After centrifuging the reaction product, disperse it in an anhydrous ethanol solution, add 0.5 g of strontium bis(trifluoromethanesulfonate), stir at 150 rpm, and react at room temperature for 18 h.

[0074] (5) Finally, the product is washed with anhydrous ethanol, first dried in a common oven at 70 °C for 4 h, and then dried in a vacuum drying oven at 100 °C for 24 h to obtain nanosheet titanium dioxide immobilized with 3-hydroxypropylimidazolium bis(trifluoromethanesulfonate), where the size of titanium dioxide in the raw material is 5 - 100 nm.

[0075] Example 1

[0076] The reactants PEF, methanol, and nanosheet titanium dioxide supported 3-hydroxypropylimidazolium bis(trifluoromethanesulfonate) were successively added to a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirrer and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and the nanosheet titanium dioxide supported 3-hydroxypropylimidazolium bis(trifluoromethanesulfonate) accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 70 °C for 3 h. After the reaction, the reactor was quickly cooled to room temperature in an ice bath. The reaction solution was filtered, washed, and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 100%, and the yield of dimethyl 2,5-furandicarboxylate was 98%.

[0077] Example 2

[0078] The reactants PEF, methanol, and nanosheet titanium dioxide supported 3-hydroxypropylimidazolium bis(trifluoromethanesulfonate) were successively added to a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirrer and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and the nanosheet titanium dioxide supported 3-hydroxypropylimidazolium bis(trifluoromethanesulfonate) accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 100 °C for 3 h. After the reaction, the reactor was quickly cooled to room temperature in an ice bath. The reaction solution was filtered, washed, and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 98%, and the yield of dimethyl 2,5-furandicarboxylate was 97%.

[0079] Example 3

[0080] The reactants PEF, methanol, and nanosheet titanium dioxide supported 3-hydroxypropylimidazolium bis(trifluoromethanesulfonate) were successively added to a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirrer and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and the nanosheet titanium dioxide supported 3-hydroxypropylimidazolium bis(trifluoromethanesulfonate) accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 130 °C for 3 h. After the reaction, the reactor was quickly cooled to room temperature in an ice bath. The reaction solution was filtered, washed, and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 96%, and the yield of dimethyl 2,5-furandicarboxylate was 95%.

[0081] Example 4

[0082] The reactants PEF, methanol, and 3-hydroxypropylimidazolium tosylate supported on nanosheet titanium dioxide were successively added to a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirring paddle and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and 3-hydroxypropylimidazolium tosylate supported on nanosheet titanium dioxide accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 70 °C for 3 h. After the reaction, the reactor was rapidly cooled to room temperature in an ice bath. The reaction solution was filtered, washed, and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 99%, and the yield of dimethyl 2,5-furandicarboxylate was 98%.

[0083] Example 5

[0084] The reactants PEF, methanol, and 3-hydroxypropylimidazolium acetate supported on nanosheet titanium dioxide were successively added to a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirring paddle and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and 3-hydroxypropylimidazolium acetate supported on nanosheet titanium dioxide accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 70 °C for 3 h. After the reaction, the reactor was rapidly cooled to room temperature in an ice bath. The reaction solution was filtered, washed, and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 100%, and the yield of dimethyl 2,5-furandicarboxylate was 98%.

[0085] Example 6

[0086] The reactants PEF, methanol, and 3-hydroxypropylimidazolium bis(trifluoromethanesulfonate) supported on nanoparticle titanium dioxide were successively added to a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirring paddle and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and 3-hydroxypropylimidazolium bis(trifluoromethanesulfonate) supported on nanoparticle titanium dioxide accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 70 °C for 3 h. After the reaction, the reactor was rapidly cooled to room temperature in an ice bath. The reaction solution was filtered, washed, and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 99%, and the yield of dimethyl 2,5-furandicarboxylate was 98%.

[0087] Example 7

[0088] The reactants PEF, methanol, and titanium dioxide nanoparticles immobilized with 3-hydroxypropylimidazolium lactate were successively added to a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirrer and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and the titanium dioxide nanoparticles immobilized with 3-hydroxypropylimidazolium lactate accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 70 °C and maintained for 3 h. After the reaction, the reactor was quickly cooled to room temperature in an ice-water bath. The reaction solution was filtered, washed, and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 98%, and the yield of dimethyl 2,5-furandicarboxylate was 95%.

[0089] Example 8

[0090] The reactants PEF, methanol, and titanium dioxide nanoparticles immobilized with 3-hydroxypropylimidazolium bis(trifluoromethanesulfonyl)imide were successively added to a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirrer and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and the titanium dioxide nanoparticles immobilized with 3-hydroxypropylimidazolium bis(trifluoromethanesulfonyl)imide accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 70 °C and maintained for 3 h. After the reaction, the reactor was quickly cooled to room temperature in an ice-water bath. The reaction solution was filtered, washed, and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 97%, and the yield of dimethyl 2,5-furandicarboxylate was 94%.

[0091] Example 9

[0092] The reactants PEF, methanol, and titanium dioxide nanoparticles immobilized with 3-hydroxypropylimidazolium lactate were successively added to a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirrer and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and the titanium dioxide nanoparticles immobilized with 3-hydroxypropylimidazolium lactate accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 70 °C and maintained for 5 h. After the reaction, the reactor was quickly cooled to room temperature in an ice-water bath. The reaction solution was filtered, washed, and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 96%, and the yield of dimethyl 2,5-furandicarboxylate was 93%.

[0093] Example 10

[0094] The reactants PEF, methanol, and titanium dioxide nanoparticles immobilized with 3-hydroxypropylimidazolium lactate were successively added to a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirrer and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and the titanium dioxide nanoparticles immobilized with 3-hydroxypropylimidazolium lactate accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 100 °C for 5 h. After the reaction, the reactor was rapidly cooled to room temperature in an ice bath. The reaction solution was filtered, washed, and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 97%, and the yield of dimethyl 2,5-furandicarboxylate was 95%.

[0095] Example 11

[0096] The reactants PEF, methanol, and titanium dioxide nanotubes immobilized with 3-hydroxypropylimidazolium acetate were successively added to a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirrer and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and the titanium dioxide nanotubes immobilized with 3-hydroxypropylimidazolium acetate accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 80 °C for 5 h. After the reaction, the reactor was rapidly cooled to room temperature in an ice bath. The reaction solution was filtered, washed, and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 96%, and the yield of dimethyl 2,5-furandicarboxylate was 93%.

[0097] Example 12

[0098] The reactants PEF, methanol, and titanium dioxide nanotubes immobilized with 3-hydroxypropylimidazolium trifluoroacetate were successively added to a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirrer and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and the titanium dioxide nanotubes immobilized with 3-hydroxypropylimidazolium trifluoroacetate accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 70 °C for 3 h. After the reaction, the reactor was rapidly cooled to room temperature in an ice bath. The reaction solution was filtered, washed, and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 98%, and the yield of dimethyl 2,5-furandicarboxylate was 97%.

[0099] Example 13

[0100] The reactants PEF, methanol, and nanotube titanium dioxide supported 3-hydroxypropylimidazolium tetrafluoroborate were successively added into a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirring paddle and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and the nanotube titanium dioxide supported 3-hydroxypropylimidazolium tetrafluoroborate accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 70 °C for 3 h. After the reaction ended, the reactor was quickly cooled to room temperature in an ice-water bath. The reaction solution was filtered, washed, and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 99%, and the yield of dimethyl 2,5-furandicarboxylate was 96%.

[0101] Example 14

[0102] The reactants PEF, methanol, and nanotube titanium dioxide supported 3-hydroxypropylimidazolium tetrafluoroborate were successively added into a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirring paddle and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and the nanotube titanium dioxide supported 3-hydroxypropylimidazolium tetrafluoroborate accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 100 °C for 3 h. After the reaction ended, the reactor was quickly cooled to room temperature in an ice-water bath. The reaction solution was filtered, washed, and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 98%, and the yield of dimethyl 2,5-furandicarboxylate was 94%.

[0103] Example 15

[0104] The reactants PEF, methanol, and nanotube titanium dioxide supported 3-hydroxypropylimidazolium hydrogen sulfate were successively added into a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirring paddle and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and the nanotube titanium dioxide supported 3-hydroxypropylimidazolium hydrogen sulfate accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 70 °C for 3 h. After the reaction ended, the reactor was quickly cooled to room temperature in an ice-water bath. The reaction solution was filtered, washed, and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 97%, and the yield of dimethyl 2,5-furandicarboxylate was 95%.

[0105] Example 16

[0106] The reactants PEF, methanol, and nanotube titanium dioxide supported 3-hydroxypropylimidazolium hydrogen sulfate were successively added to a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirring paddle and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and the nanotube titanium dioxide supported 3-hydroxypropylimidazolium hydrogen sulfate accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 70 °C and maintained for 6 h. After the reaction, the reactor was quickly cooled to room temperature in an ice-water bath. The reaction solution was filtered, washed, and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 93%, and the yield of dimethyl 2,5-furandicarboxylate was 92%.

[0107] Example 17

[0108] Titanium dioxide supported 3-methylsulfonylimidazolium bis(trifluoromethanesulfonyl)imide has very good stability in the reaction system and can be easily recovered from the filtrate. After six repeated recycling uses, there is no obvious loss of activity, which indicates that titanium dioxide supported 3-methylsulfonylimidazolium bis(trifluoromethanesulfonyl)imide has persistent high catalytic activity for the methanolysis reaction of PEF. Through the calculation of the recovery, the molar ratio of titanium dioxide supported 3-methylsulfonylimidazolium bis(trifluoromethanesulfonyl)imide to EG is about 2.41, and the mass ratio is about 7.70. In order to reduce the interference of EG, according to the calculated amount of titanium dioxide supported 3-methylsulfonylimidazolium bis(trifluoromethanesulfonyl)imide in the recovered catalyst until the mass of titanium dioxide supported 3-methylsulfonylimidazolium bis(trifluoromethanesulfonyl)imide is equal to the initial weight of pure titanium dioxide supported 3-methylsulfonylimidazolium bis(trifluoromethanesulfonyl)imide (0.15 mol% of the methanol molar amount). The experimental results show that the residues of furan oligomers and EG have no obvious effect on the catalytic activity of the recovered ionic liquid. Therefore, titanium dioxide supported 3-methylsulfonylimidazolium bis(trifluoromethanesulfonyl)imide catalyzes the alcoholysis of PEF and shows excellent catalytic activity and reusability under mild conditions, which conforms to the concept of modern green and sustainable chemistry.

[0109] Comparative Example 1

[0110] The reactants PEF, methanol, and tetrabutyl titanate were successively added to a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirring paddle and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and the tetrabutyl titanate salt accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 100 °C and maintained for 3 h. After the reaction, the reactor was quickly cooled to room temperature in an ice-water bath. The reaction solution was filtered, washed, and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 86%, and the yield of dimethyl 2,5-furandicarboxylate was 73%.

[0111] Comparative Example 2

[0112] The reactants PEF, methanol and tetrabutyl titanate were successively added into a stainless-steel sealed high-temperature and high-pressure reactor equipped with a stirring paddle and a thermometer. Among them, the mass of PEF was 3 g, the mass ratio of PEF to methanol was 1:1, and the tetrabutyl titanate salt accounted for 0.5% of the mass of PEF. The reaction system was heated in a water bath at 80 °C for 5 h. After the reaction was completed, the reactor was quickly cooled to room temperature in an ice-water bath. The reaction solution was filtered, washed and rotary evaporated to obtain pure dimethyl 2,5-furandicarboxylate. The degradation rate of PEF was calculated to be 91%, and the yield of dimethyl 2,5-furandicarboxylate was 87%.

[0113] As described above, these are only several embodiments of the present application and do not impose any form of limitation on the present application. Although the present application is disclosed above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art, without departing from the scope of the technical solution of the present application, making some changes or modifications using the disclosed technical content is equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A titanium dioxide-supported ionic liquid catalyst, characterized in that, The titanium dioxide-supported ionic liquid catalyst has the structure shown in Formula I: m is a positive integer, 1 ≤ m ≤ 16; X− is selected from at least one of bis(trifluoromethanesulfonate), p-toluenesulfonate, lactate, bis(trifluoromethanesulfonimide), bisulfate, acetate, trifluoromethanesulfonate, 2-(2-hydroxyethoxy)acetate, phenolate, 2,2,2-trifluoroethoxide, trifluoroacetate, tetrafluoroborate; The titanium dioxide is the carrier.

2. The titanium dioxide-supported ionic liquid catalyst according to claim 1, characterized in that, The morphology of the titanium dioxide is selected from at least one of granular, lamellar, linear, and nanotubular; Preferably, the size of the titanium dioxide is 5 - 100 nm.

3. A method for preparing the titanium dioxide-supported ionic liquid catalyst according to any one of claims 1 to 2, characterized in that, The preparation method includes: Reacting a mixture containing titanium dioxide, imidazole, propanol, a coupling agent, and an anion salt in Reaction I to obtain the titanium dioxide-supported ionic liquid catalyst.

4. The preparation method according to claim 3, characterized in that, The anion salt is selected from at least one of strontium bis(trifluoromethanesulfonate), sodium p-toluenesulfonate, sodium lactate, lithium bis(trifluoromethanesulfonimide), sodium bisulfate, sodium acetate, sodium trifluoromethanesulfonate, sodium 2-(2-hydroxyethoxy)acetate, sodium phenolate, sodium 2,2,2-trifluoroethoxide, sodium trifluoroacetate, sodium tetrafluoroborate; Preferably, the mass ratio of the titanium dioxide to the imidazole is 1:0.01 - 20%; Preferably, the mass ratio of the titanium dioxide to the coupling agent is 1:0.01 - 20%; Preferably, the mass ratio of the imidazole to the propanol is 1:0.01 - 20%; Preferably, the mass ratio of the imidazole to the anion salt is 1:0.01 - 20%.

5. The preparation method according to claim 3, characterized in that, The coupling agent is selected from at least one of silane coupling agents, titanate coupling agents, aluminate coupling agents, metal composite coupling agents, phosphate coupling agents, and borate coupling agents; Preferably, the temperature of Reaction I is 40 - 100 °C, and the time of Reaction I is 6 - 24 h.

6. Use of the titanium dioxide-supported ionic liquid catalyst according to any one of claims 1 to 2 in the alcoholysis of 2,5-furandicarboxylic acid-based polyesters.

7. The use according to claim 6, characterized in that, The method for alcoholyzing 2,5-furandicarboxylic acid-based polyester includes: In a closed reactor, reacting a mixture containing 2,5-furandicarboxylic acid-based polyester, an alcohol compound, and the titanium dioxide-supported ionic liquid catalyst in Reaction II to obtain a product containing 2,5-furandicarboxylic acid diol ester.

8. The use according to claim 7, characterized in that, The alcohol compound is selected from at least one of 1-butanol, dodecanediol, 2-butanol, methanol, ethanol, 2-propanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 3-methyl-1-butanol, 2,2-dimethyl-1-propanol, ethylene glycol, 2-methyl-2-butanol, pentanediol, hexanediol, heptanediol, 1-propanol, 3-methyl-2-butanol, propanediol, 2-methyl-1-butanol, butanediol, octanediol, nonanediol, decanediol, undecanediol, tridecanediol, tetradecanediol; Preferably, the 2,5-furandicarboxylic acid-based polyester is selected from at least one of polybutylene 2,5-furandicarboxylate, poly(1,5-pentanediol 2,5-furandicarboxylate), poly(isosorbide 2,5-furandicarboxylate), polyethylene 2,5-furandicarboxylate, polypropylene 2,5-furandicarboxylate, poly(octylene glycol 2,5-furandicarboxylate), poly(hexylene glycol 2,5-furandicarboxylate), poly(heptylene glycol 2,5-furandicarboxylate), ethylene glycol 2,5-furandicarboxylate-terephthalate, 1,4-cyclohexanedimethanol 2,5-furandicarboxylate, 2,2,4,4-tetramethyl-1,3-cyclobutanediol 2,5-furandicarboxylate.

9. The use according to claim 7, characterized in that, The mass ratio of the 2,5-furandicarboxylic acid-based polyester to the alcohol compound is 1:0.5 to 10; Preferably, the mass ratio of the 2,5-furandicarboxylic acid-based polyester to the alcohol compound is 1:1 to 6; Preferably, the dosage of the titanium dioxide-supported ionic liquid catalyst is 0.1 to 10% of the mass of the 2,5-furandicarboxylic acid-based polyester; Preferably, the dosage of the titanium dioxide-supported ionic liquid catalyst is 0.2 to 8% of the mass of the 2,5-furandicarboxylic acid-based polyester.

10. The use according to claim 7, characterized in that, The temperature of the reaction II is 40 to 180 °C, and the time of the reaction II is 0.2 to 10 h; Preferably, the temperature of the reaction II is 50 to 150 °C, and the time of the reaction II is 0.3 to 8 h.

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