A rare earth-titanium bimetallic nanostructure catalyst, a preparation method and application thereof

Abstract

The application relates to the technical field of titanium metal catalysts, in particular to a rare earth-titanium bimetallic nanostructure catalyst and a preparation method and application thereof. The catalyst is obtained by modifying a supported catalyst precursor by using P=O groups in phosphoric acid esters, and coating the supported catalyst precursor by generating a surface coordination structure; the supported catalyst precursor is obtained by anchoring and loading an amino carrier with a Si-O-Si-Y bond through a Ti-O-Si bond, using a mixed oxide sol network as a precursor; the precursor is obtained by using a diketone compound to chelate a carbonate, and then hydrolyzing and condensing with rare earth metal ions to form a mixed oxide sol network with Ti-O-Ti bonds and Ti-O-M bonds, that is, a bonding network is formed by the rare earth metal and titanium, and then a surface hydrophobic layer is constructed by using phosphoric acid esters, so that the hydrolysis half-life of the catalyst in a high-temperature and high-humidity environment is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium metal catalysts, and in particular to a rare earth-titanium bimetallic nanostructured catalyst, a preparation method and an application thereof. Background Art

[0002] Polybutylene adipate / terephthalate (PBAT) exhibits excellent ductility and elongation at break, as well as good heat and impact resistance and biodegradability. It is currently a highly active biodegradable plastic and one of the most readily commercially available biodegradable materials. It is widely used in various fields, including film bags, ground films, textiles, foaming, and injection molding.

[0003] In the article "Research Progress in Catalysts for Synthetic Biodegradable Plastics (PBAT)" published in Volume 44, Issue 10 (October 2024) of the journal Modern Chemical Industry, Li Xinbei et al. point out that the synthesis of PBAT involves two stages: esterification and polycondensation. Catalysts play a crucial role in both processes. Currently, the most widely used catalysts are antimony, germanium, and titanium. Antimony-based catalysts have high catalytic activity, few side reactions, and are inexpensive, making them widely commercialized in the polyester industry. However, antimony compounds, when used as catalysts, are prone to producing "gray fog" and coexist with arsenic in nature, making them toxic and incompatible with the concept of green and healthy environmental protection. Polyesters prepared using germanium-based catalysts have a better hue, but the scarcity of germanium in nature makes them expensive, and the difficulty in controlling catalytic activity during the reaction has prevented their industrial application, primarily in film-forming processes. Titanium-based catalysts, on the other hand, are abundant in nature, non-toxic, and highly active, garnering widespread attention as alternatives to other catalysts.

[0004] However, traditional single titanium catalysts, such as tetrabutyl titanate, are susceptible to hydrolysis during the polycondensation of poly(butylene adipate / terephthalate) (PBAT), leading to loss of active sites and decreased catalytic efficiency. Furthermore, single-metal catalyst systems have limited ability to inhibit thermal degradation and thermal oxidation side reactions, resulting in a wide molecular weight distribution and a high content of terminal carboxyl groups. Metal particles exhibit significant agglomeration and poor dispersion, leading to localized overheating, reddish hue, and low L values. Furthermore, the use of single titanium catalysts requires the use of other auxiliaries or additives, increasing the number of process steps and prolonging the reaction time to produce high-performance PBAT, which is detrimental to the market demand for efficient and rapid PBAT production.

[0005] For example, CN119591848A discloses a PBAT resin production process, comprising the following steps: S10: Esterification: PTA esterification and AA esterification are performed to obtain ester 1 and ester 2, respectively; ester 1 and ester 2 are mixed and co-esterified to obtain ester 3; S20: Pre-polycondensation: Ester 3 and a catalyst are pre-polycondensed to obtain a prepolymer; S30: Final polycondensation: The prepolymer and chain extender 1 are subjected to a final polycondensation to obtain a final polymer; S40: The final polymer and chain extender 2 are subjected to a chain extension reaction and then extruded to obtain the PBAT resin. Using tetrabutyl titanate as a catalyst, epoxy and isocyanate chain extenders are also required, resulting in a complex production process and a reaction time of over 13 hours.

[0006] CN118108934A discloses a composite catalyst composition for polyester and its preparation method. Using nano-silica as a carrier, titanate, a tin compound, an alkali metal, and a phosphate are reacted under certain conditions to prepare a nanoscale solid composite catalyst. This is then mixed with an amino acid ionic liquid to produce the polyester composite catalyst composition. This polyester composite catalyst composition is applied to copolyesters such as PBACT, PBSC, PBSCT, PBCT, PBAT, and PBT. While this technical solution improves the titanate, the ionic liquid catalyst is ultimately degraded into small molecules that are removed by vacuum, resulting in a single-use lifespan for the catalyst and significantly increasing production costs.

[0007] Based on the above-mentioned existing technology, the existing technology has the following technical problems that need to be solved urgently: titanium-based catalysts are prone to hydrolysis during the catalytic process, the preparation process is complex, the cost is high, and the lifespan is short; the prepared polyesters have wide molecular weight distribution, high terminal carboxyl content, poor chromaticity, and other technical problems. Summary of the Invention

[0008] In order to solve the above technical problems, the present invention provides a rare earth-titanium bimetallic nanostructured catalyst, wherein the catalyst is modified by using the P=O group in the phosphate ester to generate a supported catalyst precursor. and The surface coordination structure is coated on the supported catalyst precursor;

[0009] Wherein, the structural formulas of the groups R1, R2, R3, and R4 are independently 、 、 One of, M is a rare earth metal;

[0010] The supported catalyst precursor is obtained by anchoring and loading a mixed oxide sol network as a precursor with an amino support having a Si-O-Si-Y bond through a Ti-O-Si bond;

[0011] The precursor is prepared by chelating carbonate with a diketone compound, which is then hydrolyzed and condensed with rare earth metal ions to form a mixed oxide sol network with Ti-O-Ti bonds and Ti-OM bonds.

[0012] Furthermore, the hydrolysis half-life of the catalyst measured under accelerated aging conditions of 70° C. and 85% relative humidity is 32-35 days.

[0013] Furthermore, the equipment used in the hydrolysis half-life test is a constant temperature and humidity aging box.

[0014] Furthermore, the phosphate ester is one or more of bis(2-ethylhexyl) phosphate, triisooctyl phosphate, and triphenyl phosphate.

[0015] Furthermore, the rare earth metal is one or more of lanthanum, cerium, and neodymium.

[0016] Furthermore, Y in the Si-O-Si-Y bond is an alkyl group containing an amino group, wherein the number of C atoms in the alkyl group is any integer between 2 and 6.

[0017] Furthermore, the amino group-containing alkyl group is -C3H6NH2.

[0018] Furthermore, the diketone compound is acetylacetone.

[0019] Furthermore, the titanate is tetrabutyl titanate (TBT).

[0020] The present invention also provides a method for preparing the rare earth-titanium bimetallic nanostructured catalyst, comprising the following steps:

[0021] Step 1, precursor synthesis: titanate and rare earth metal salt are dissolved in an organic solvent, diketone compound solution is added, and stirring is carried out under the protection of inert gas. After stirring, an inorganic acid aqueous solution is added dropwise to react to form a sol, and then aged and dried to obtain a precursor;

[0022] Among them, the diketone compound chelates titanate to slow down the hydrolysis rate, and the titanium ions and rare earth metal ions undergo coordinated hydrolysis-condensation under acidic conditions to form a mixed oxide sol network with Ti-O-Ti bonds and Ti-OM bonds, i.e., the precursor;

[0023] Step 2, preparing an amino carrier: vacuum-activating the nano-dispersed carrier, and then refluxing it with a silane coupling agent in a first organic benzene solvent to obtain an amino carrier;

[0024] wherein the silane coupling agent and the silanol groups on the surface of the nano-dispersed carrier condense to form a Si-O-Si-Y bond, wherein Y in the Si-O-Si-Y bond is an alkyl group containing an amino group, wherein the number of C atoms in the alkyl group is any integer between 2 and 6;

[0025] Step 3, preparation of supported catalyst precursor: mixing the precursor and the amino support, performing vacuum impregnation, and then calcining to obtain the supported catalyst precursor;

[0026] The precursor is anchored and loaded on an amino support having a Si-O-Si-Y bond via a Ti-O-Si bond to obtain a supported catalyst precursor;

[0027] Step 4, preparation of a rare earth-titanium bimetallic nanostructured catalyst: dispersing a supported catalyst precursor in a second organic benzene solvent, adding a phosphate ester to perform surface modification, then centrifuging and washing, and vacuum drying to obtain the rare earth-titanium bimetallic nanostructured catalyst;

[0028] Wherein, the P=O group in the phosphate ester modifies the supported catalyst precursor by generating and The surface coordination structure coats the supported catalyst precursor;

[0029] Wherein, the structural formulas of the groups R1, R2, R3, and R4 are independently 、 、 M is a rare earth metal.

[0030] Furthermore, the mass ratio of the titanate to the rare earth metal salt in step 1 is 100:(6-7).

[0031] Furthermore, the rare earth metal salt in step 1 is one or more of nitrates or chlorides.

[0032] Furthermore, the rare earth metal element in the rare earth metal salt in step 1 is one or more of lanthanum, cerium, and neodymium.

[0033] Furthermore, the rare earth metal salt in step 1 is one or more of lanthanum nitrate (La(NO3)3), cerium nitrate (Ce(NO3)3), and neodymium chloride (NdCl3).

[0034] Furthermore, the organic solvent in step 1 is anhydrous ethanol.

[0035] Furthermore, the volume of the organic solvent used in step 1 is based on the ability to completely dissolve the titanate and the rare earth metal salt.

[0036] Furthermore, the mass concentration of the diketone compound in the diketone compound solution in step 1 is 7%, and the solvent is ethanol.

[0037] Furthermore, the diketone compound in step 1 is acetylacetone.

[0038] Furthermore, in step 1, the volume ratio of the organic solvent to the diketone compound solution is 6:1.

[0039] Furthermore, the inert gas in step 1 is nitrogen.

[0040] Furthermore, in step 1, the stirring temperature after the inert gas is introduced is 5° C. and the stirring time is 4 hours.

[0041] Furthermore, the inorganic acid in the inorganic acid aqueous solution in step 1 is nitric acid.

[0042] Furthermore, the molar ratio of hydrogen atoms contained in the inorganic acid in the inorganic acid aqueous solution in step 1 to titanium atoms in the titanate is 1.3:1.

[0043] Furthermore, the pH of the inorganic acid aqueous solution in step 1 is 3.2.

[0044] Furthermore, the aging temperature in step 1 is 40° C. and the aging time is 24 hours.

[0045] Furthermore, the drying in step 1 is supercritical CO2 drying, that is, after heating to 40°C, pressurizing to 25 MPa, and finally maintaining at constant temperature and pressure for 4 hours.

[0046] Furthermore, the nano-dispersed carrier in step 2 is mesoporous silica.

[0047] Furthermore, the average particle size of the mesoporous silica in step 2 is 6 nm, the pore volume is 0.8 mL / g, and the specific surface area is 620 m 2 / g.

[0048] Furthermore, the vacuum degree of the vacuum activation in step 2 is 0.1 Pa, the time is 6 hours, and the temperature is 180°C.

[0049] Furthermore, in step 2, the mass ratio of the nano-dispersed carrier to the silane coupling agent is 4:1.

[0050] Furthermore, the silane coupling agent in step 2 is 3-aminopropyltrimethoxysilane.

[0051] Furthermore, in step 2, the first organic benzene solvent is toluene.

[0052] Furthermore, in step 2, the volume of the first organic benzene solvent is based on the ability to completely dissolve the silane coupling agent.

[0053] Furthermore, the reflux temperature in step 2 is 80° C. and the reflux time is 6 h.

[0054] Furthermore, in step 3, the mass ratio of the precursor to the amino carrier is 3:1.

[0055] Furthermore, the vacuum degree of the vacuum impregnation in step 3 is -0.09 MPa, and the time is 2 hours.

[0056] Furthermore, the calcination temperature in step 3 is 350° C. and the calcination time is 3 h.

[0057] Furthermore, in step 4, the second organic benzene solvent is toluene.

[0058] Furthermore, in step 4, the volume of the second organic benzene solvent is based on the ability to completely dissolve the phosphate ester.

[0059] Furthermore, the molar ratio of the phosphate in step 4 to the titanium atom in the titanate in step 1 is 1:1.5.

[0060] Furthermore, the reaction temperature of the surface modification in step 4 is 60° C. and the reaction time is 4 h.

[0061] Furthermore, in the centrifugal washing in step 4, the centrifugal speed is 10000 rpm, the centrifugal time is 15 min, the detergent used is toluene and / or ethanol, and the number of centrifugal washings is at least 3 times.

[0062] Furthermore, the vacuum drying in step 4 is carried out at a temperature of 60° C., a vacuum degree of 0.05 MPa, and a time of 12 h.

[0063] The present invention also provides polybutylene adipate / terephthalate, wherein the raw materials for preparing polybutylene adipate / terephthalate (PBAT) include adipic acid, terephthalic acid, and 1,4-butanediol, and the PBAT is prepared by a one-pot process using the above-mentioned rare earth-titanium bimetallic nanostructured catalyst for catalysis;

[0064] The polybutylene adipate / terephthalate (PBAT) has a terminal carboxyl content of 11.7-12.9 mol / t, a molecular weight of 99,500-103,300 g / mol, a molecular weight distribution index of 1.68-1.74, and an L value in color value of 83.0-85.7.

[0065] Furthermore, the test method for the terminal carboxyl group content is GB / T 14190-2017;

[0066] The molecular weight is tested by gel permeation chromatography.

[0067] The testing method for the color value is GB / T 2409-2020.

[0068] The present invention also provides a method for preparing polybutylene adipate / terephthalate, comprising the following steps:

[0069] Weighing adipic acid, terephthalic acid, and 1,4-butanediol, mixing them evenly, then adding the rare earth-titanium bimetallic nanostructured catalyst, and carrying out an esterification reaction under the protection of an inert gas;

[0070] Then, the temperature is gradually increased and the vacuum degree is reduced to complete the polycondensation reaction and obtain the polybutylene adipate / terephthalate.

[0071] Furthermore, the molar ratio of adipic acid, terephthalic acid and 1,4-butanediol is 1:1:2.5.

[0072] Furthermore, the mass of the rare earth-titanium bimetallic nanostructured catalyst is 0.05% of the total mass of adipic acid, terephthalic acid, and 1,4-butanediol.

[0073] Furthermore, the inert gas is nitrogen.

[0074] Furthermore, the esterification temperature is 160° C. and the time is 2.5-3 hours.

[0075] Furthermore, the temperature of the gradient heating is 200-210° C., and the heating rate is 10° C. / h.

[0076] Furthermore, the vacuum degree is reduced from 1000Pa to 10Pa.

[0077] Furthermore, the polycondensation reaction time is 4-5h.

[0078] Furthermore, the preparation place also includes pelletizing and drying the product after polycondensation.

[0079] The present invention also provides a film plastic product, which is prepared by using the above-mentioned polybutylene adipate / terephthalate.

[0080] The beneficial effects of the present invention are:

[0081] 1. The present invention provides a rare earth-titanium bimetallic nanostructured catalyst, wherein the catalyst is obtained by modifying a supported catalyst precursor using a P=O group in a phosphate and coating the supported catalyst precursor by generating a surface coordination structure; the supported catalyst precursor is obtained by anchoring a mixed oxide sol network with an amino carrier having a Si-O-Si-Y bond via a Ti-O-Si bond; the precursor is obtained by chelating a carbonate using a diketone compound, which is then hydrolyzed and condensed with a rare earth metal ion to form a mixed oxide sol network having Ti-O-Ti bonds and Ti-OM bonds, i.e., a bonding network is formed by rare earth metal and titanium, and then a surface hydrophobic layer is constructed by combining the phosphate, thereby improving the hydrolysis half-life of the catalyst in a high temperature and high humidity environment;

[0082] 2. The present invention controls the particle size of the rare earth-titanium bimetallic clusters generated during the catalyst preparation process to 5-20 nm through the confinement effect of specific mesoporous silica, thereby increasing the specific surface area and the exposure rate of the catalytic active sites, effectively shortening the polycondensation reaction time when preparing polyadipate / butylene terephthalate. At the same time, while ensuring a short polycondensation time, the L value of the product polyadipate / butylene terephthalate is higher than the color value of the product prepared by the catalyst used in the prior art;

[0083] 3. Due to the stable structure and uniform activity distribution of the rare earth-titanium bimetallic nanostructured catalyst prepared by the present invention, the molecular weight distribution index of poly(butylene adipate / terephthalate) is reduced, further improving the quality of film plastic products prepared with poly(butylene adipate / terephthalate) as raw materials;

[0084] 4. The terminal carboxyl content of the poly(butylene adipate / terephthalate) prepared by the present invention is lower than that of the poly(butylene adipate / terephthalate) in the prior art. The terminal carboxyl content has an impact on aging properties. The lower the terminal carboxyl content, the better the aging properties. DETAILED DESCRIPTION

[0085] In the following examples, Examples 1-3 are rare earth-titanium bimetallic nanostructured catalysts and preparation methods thereof, Examples 4-6 are polybutylene adipate / terephthalate (PBAT) prepared using the catalysts in Examples 1-3 and preparation methods thereof; Comparative Examples 1-2 are existing catalysts, and Comparative Examples 3-4 are polybutylene adipate / terephthalate (PBAT) prepared using existing catalysts and preparation methods thereof.

[0086] Example 1

[0087] This embodiment provides a rare earth-titanium bimetallic nanostructured catalyst, wherein the catalyst is modified by using the P=O group in bis(2-ethylhexyl) phosphate to form a supported catalyst precursor. and The surface coordination structure is coated on the supported catalyst precursor;

[0088] Wherein, the structural formula of groups R1, R2, R3, and R4 is , M is a rare earth metal La;

[0089] The supported catalyst precursor is obtained by using a mixed oxide sol network as a precursor and anchoring and loading the amino carrier having a Si-O-Si-C3H6NH2 bond through a Ti-O-Si bond.

[0090] The precursor is prepared by chelating tetrabutyl titanate with acetylacetone and then reacting with rare earth metal ions La 3+ Hydrolysis-condensation occurs to form a mixed oxide sol network with Ti-O-Ti bonds and Ti-O-La bonds.

[0091] The preparation method of the rare earth-titanium bimetallic nanostructured catalyst comprises the following steps:

[0092] Step 1, precursor synthesis: 10g of tetrabutyl titanate (TBT) and 0.64g of rare earth metal salt lanthanum nitrate (La(NO3)3) were dissolved in 300mL of anhydrous ethanol, and 50mL of 7% acetylacetone solution was added, and stirred under the protection of nitrogen at a stirring temperature of 5°C for 4h. After the stirring, a nitric acid aqueous solution with a pH of 3.2 was added dropwise, wherein the molar ratio of the hydrogen atoms contained in the inorganic acid in the nitric acid aqueous solution to the titanium atoms in the titanate was 1.3:1, and the reaction generated a light blue sol. After aging at 40°C for 24 hours, supercritical CO2 drying was performed, that is, after heating to 40°C, pressurizing to 25MPa, and finally drying for 4h under constant temperature and pressure conditions to obtain a precursor;

[0093] Among them, acetylacetone chelated titanate is used to slow down the hydrolysis rate, and the coordinated hydrolysis-condensation of titanium ions and lanthanum ions occurs under acidic conditions to form a mixed oxide sol network with Ti-O-Ti bonds and Ti-O-La bonds, i.e., the precursor;

[0094] Step 2: Preparation of amino carrier: 80g of the carrier has an average particle size of 6nm, a pore volume of 0.8mL / g, and a specific surface area of ​​620m 2 / g of mesoporous silica was vacuum activated at a vacuum degree of 0.1 Pa and a temperature of 180°C for 6 h, and then refluxed with 20 g of 3-aminopropyltrimethoxysilane in toluene at a reflux temperature of 80°C for 6 h to obtain an amino support;

[0095] Wherein, the 3-aminopropyltrimethoxysilane condenses with the silanol groups on the surface of the mesoporous silica to form a Si-O-Si-C3H6NH2 bond;

[0096] Step 3, preparation of supported catalyst precursor: 24 g of the precursor and 8 g of the amino support were mixed and vacuum impregnated at a vacuum degree of -0.09 MPa for 2 h, and then calcined at a temperature of 350° C. for 3 h to obtain a supported catalyst precursor;

[0097] The precursor is anchored and loaded on an amino support having a Si-O-Si-C3H6NH2 bond via a Ti-O-Si bond to obtain a supported catalyst precursor;

[0098] Step 4, preparation of a rare earth-titanium bimetallic nanostructured catalyst: 10 g of a supported catalyst precursor was dispersed in toluene, and surface modified after adding bis(2-ethylhexyl) phosphate, wherein the molar ratio of bis(2-ethylhexyl) phosphate to the titanium atom in the titanate in step 1 was 1:1.5, the reaction temperature was 60° C., the time was 4 hours, and then centrifuged at a speed of 10,000 rpm for 15 minutes. The detergent used thereafter was toluene, and the number of washes was 3. After completion, vacuum drying was performed at a temperature of 60° C., a vacuum degree of 0.05 MPa, and a time of 12 hours to obtain the rare earth-titanium bimetallic nanostructured catalyst;

[0099] Wherein, the P=O group in the phosphate ester modifies the supported catalyst precursor by generating and The surface coordination structure coats the supported catalyst precursor;

[0100] Wherein, the structural formula of groups R1, R2, R3, and R4 is , M is a rare earth metal La.

[0101] In this embodiment, the hydrolysis half-life of the rare earth-titanium bimetallic nanostructured catalyst is 35 days.

[0102] Example 2

[0103] This embodiment provides a rare earth-titanium bimetallic nanostructured catalyst, wherein the catalyst is modified by using the P=O group in triisooctyl phosphate to form a supported catalyst precursor. and The surface coordination structure is coated on the supported catalyst precursor;

[0104] Wherein, the structural formula of groups R1, R2, R3, and R4 is M is a rare earth metal Ce;

[0105] The supported catalyst precursor is obtained by anchoring and loading a mixed oxide sol network as a precursor and an amino carrier with Si-O-Si-C3H6NH2 bonds through Ti-O-Si bonds.

[0106] The precursor is titanium tetrabutoxide chelated with acetylacetone, and then rare earth metal ions Ce 3+ Hydrolysis-condensation occurs to form a mixed oxide sol network with Ti-O-Ti bonds and Ti-O-Ce bonds.

[0107] The preparation method of the rare earth-titanium bimetallic nanostructure catalyst comprises the following steps:

[0108] Step 1, precursor synthesis: 10 g of titanium tetrabutoxide (TBT) and 0.64 g of rare earth metal salt cerium nitrate (Ce(NO3)3) are dissolved in 300 mL of anhydrous ethanol, 50 mL of a 7% acetylacetone solution is added, and stirring is performed under the protection of nitrogen, the stirring temperature is 5°C, the stirring time is 4 h, after stirring is completed, a pH of 3.2 nitric acid aqueous solution is added dropwise, wherein the molar ratio of hydrogen atoms contained in the inorganic acid in the nitric acid aqueous solution to titanium atoms in the titanate is 1.3:1, a light blue sol is generated, after aging at 40°C for 24 hours, supercritical CO2 drying is performed, i.e. the temperature is increased to 40°C, the pressure is increased to 25 MPa, and finally the precursor is obtained after drying under the conditions of constant temperature and constant pressure for 4 h;

[0109] The acetylacetone chelated titanate is used to slow down the hydrolysis rate, and the synergistic hydrolysis-condensation of titanium ions and cerium ions occurs under acidic conditions to form a mixed oxide sol network with Ti-O-Ti bonds and Ti-O-Ce bonds, i.e. a precursor;

[0110] Step 2, preparation of an amino carrier: 80 g of mesoporous silica with an average particle size of 6 nm, a pore volume of 0.8 mL / g, and a specific surface area of 620 m 2 / g is vacuum activated at a vacuum degree of 0.1 Pa and a temperature of 180°C for 6 h, and then refluxed with 20 g of 3-aminopropyltrimethoxysilane in toluene, the refluxing temperature is 80°C, and the refluxing time is 6 h to obtain an amino carrier;

[0111] The 3-aminopropyltrimethoxysilane and the silicon hydroxyl groups on the surface of the mesoporous silica are condensed to form Si-O-Si-C3H6NH2 bonds;

[0112] Step 3, preparation of supported catalyst precursor: 24 g of the precursor and 8 g of the amino support were mixed and vacuum impregnated at a vacuum degree of -0.09 MPa for 2 h, and then calcined at a temperature of 350° C. for 3 h to obtain a supported catalyst precursor;

[0113] The precursor is anchored and loaded on an amino support having a Si-O-Si-C3H6NH2 bond via a Ti-O-Si bond to obtain a supported catalyst precursor;

[0114] Step 4, preparation of rare earth-titanium bimetallic nanostructured catalyst: 10g of supported catalyst precursor was dispersed in toluene, and triisooctyl phosphate was added for surface modification, wherein the molar ratio of triisooctyl phosphate to the titanium atom in the titanate in step 1 was 1:1.5, the reaction temperature was 60°C, the time was 4h, and then centrifuged at a speed of 10000rpm for 15min. The detergent used was toluene, and the number of washings was 3. After completion, vacuum drying was performed at a temperature of 60°C, a vacuum degree of 0.05MPa, and a time of 12h to obtain the rare earth-titanium bimetallic nanostructured catalyst;

[0115] Wherein, the P=O group in the phosphate ester modifies the supported catalyst precursor by generating and The surface coordination structure coats the supported catalyst precursor;

[0116] Wherein, the structural formula of groups R1, R2, R3, and R4 is , M is rare earth metal Ce.

[0117] In this embodiment, the hydrolysis half-life of the rare earth-titanium bimetallic nanostructured catalyst is 32 days.

[0118] Example 3

[0119] This embodiment provides a rare earth-titanium bimetallic nanostructured catalyst, wherein the catalyst is modified by using the P=O group in triphenyl phosphate to form a supported catalyst precursor. and The surface coordination structure is coated on the supported catalyst precursor;

[0120] Wherein, the structural formula of groups R1, R2, R3, and R4 is , M is rare earth metal Nd;

[0121] The supported catalyst precursor is obtained by using a mixed oxide sol network as a precursor and anchoring and loading the amino carrier having a Si-O-Si-C3H6NH2 bond through a Ti-O-Si bond.

[0122] The precursor is acetylacetone chelated tetrabutyl titanate, which is then reacted with rare earth metal ions Nd 3+ Hydrolysis-condensation occurs to form a mixed oxide sol network with Ti-O-Ti bonds and Ti-O-Nd bonds.

[0123] The preparation method of the rare earth-titanium bimetallic nanostructure catalyst comprises the following steps:

[0124] Step 1, precursor synthesis: 10 g of tetrabutyl titanate (TBT) and 0.64 g of rare earth metal salt neodymium chloride (NdCl3) are dissolved in 300 mL of anhydrous ethanol, 50 mL of a 7% acetylacetone solution is added, and stirring is performed under the protection of nitrogen, with a stirring temperature of 5°C and a stirring time of 4 h. After stirring is completed, a nitric acid aqueous solution with a pH of 3.2 is added dropwise, wherein the molar ratio of hydrogen atoms in the inorganic acid in the nitric acid aqueous solution to titanium atoms in the titanate is 1.3:1. A light blue sol is generated by the reaction. After aging at 40°C for 24 h, supercritical CO2 drying is performed, i.e., the temperature is increased to 40°C, the pressure is increased to 25 MPa, and finally the temperature and pressure are kept constant for 4 h to dry the precursor.

[0125] The acetylacetone chelated titanate is used to slow down the hydrolysis rate. Under acidic conditions, the titanium ions and cerium ions undergo synergistic hydrolysis-condensation to form a mixed oxide sol network with Ti-O-Ti bonds and Ti-O-Nd bonds, i.e., the precursor.

[0126] Step 2, preparation of an aminated carrier: 80 g of mesoporous silica with an average particle size of 6 nm, a pore volume of 0.8 mL / g, and a specific surface area of 620 m 2 / g is vacuum activated at a vacuum degree of 0.1 Pa and a temperature of 180°C for 6 h, and then refluxed with 20 g of 3-aminopropyltrimethoxysilane in toluene at a reflux temperature of 80°C for 6 h to obtain an aminated carrier.

[0127] The 3-aminopropyltrimethoxysilane and the silicon hydroxyl groups on the surface of the mesoporous silica are condensed to form Si-O-Si-C3H6NH2 bonds.

[0128] Step 3, preparation of a supported catalyst precursor: 24 g of the precursor and 8 g of the aminated carrier are mixed and vacuum impregnated at a vacuum degree of -0.09 MPa for 2 h, and then calcined at a temperature of 350°C for 3 h to obtain a supported catalyst precursor.

[0129] The precursor and the aminated carrier with Si-O-Si-C3H6NH2 bonds are anchored and loaded through Ti-O-Si bonds to obtain a supported catalyst precursor.

[0130] Step 4, preparation of rare earth-titanium bimetallic nanostructured catalyst: 10 g of supported catalyst precursor was dispersed in toluene, and triphenyl phosphate was added for surface modification, wherein the molar ratio of triphenyl phosphate to the titanium atom in the titanate in step 1 was 1:1.5, the reaction temperature was 60°C, the time was 4 hours, and then centrifuged at a speed of 10,000 rpm for 15 minutes. The detergent used thereafter was toluene, and the number of washes was 3. After completion, vacuum drying was performed at a temperature of 60°C, a vacuum degree of 0.05 MPa, and a time of 12 hours to obtain the rare earth-titanium bimetallic nanostructured catalyst;

[0131] Wherein, the P=O group in the phosphate ester modifies the supported catalyst precursor by generating and The surface coordination structure coats the supported catalyst precursor;

[0132] Wherein, the structural formula of groups R1, R2, R3, and R4 is , M is rare earth metal Nd.

[0133] In this embodiment, the hydrolysis half-life of the rare earth-titanium bimetallic nanostructured catalyst is 34 days.

[0134] Example 4

[0135] This embodiment provides polybutylene adipate / terephthalate and a preparation method thereof. The polybutylene adipate / terephthalate (PBAT) is prepared from raw materials including adipic acid, terephthalic acid, and 1,4-butanediol, and is catalyzed by the rare earth-titanium bimetallic nanostructured catalyst of Example 1 through a one-pot process.

[0136] The polybutylene adipate / terephthalate (PBAT) has a terminal carboxyl content of 11.7 mol / t, a molecular weight of 101,000 g / mol, a molecular weight distribution index of 1.71, and an L value in color value of 85.7.

[0137] The preparation method specifically comprises:

[0138] Adipic acid, terephthalic acid, and 1,4-butanediol were weighed in a molar ratio of 1:1:2.5, mixed evenly, and then added with the rare earth-titanium bimetallic nanostructured catalyst, wherein the mass of the rare earth-titanium bimetallic nanostructured catalyst was 0.05% of the total mass of the adipic acid, terephthalic acid, and 1,4-butanediol. An esterification reaction was carried out under nitrogen protection; the esterification temperature was 160°C, and the reaction time was 3 hours;

[0139] Then, the temperature was gradually increased to 200°C at a heating rate of 10°C / h, and the vacuum degree was reduced from 1000Pa to 10Pa. The polycondensation reaction was completed for 4.5h, and finally, the polybutylene adipate / terephthalate was obtained after pelletizing and drying.

[0140] Example 5

[0141] This embodiment provides polybutylene adipate / terephthalate and a preparation method thereof. The polybutylene adipate / terephthalate (PBAT) is prepared from raw materials including adipic acid, terephthalic acid, and 1,4-butanediol, and is catalyzed by the rare earth-titanium bimetallic nanostructured catalyst of Example 2 through a one-pot process.

[0142] The polybutylene adipate / terephthalate (PBAT) has a terminal carboxyl content of 12.4 mol / t, a molecular weight of 99,500 g / mol, a molecular weight distribution index of 1.68, and an L value in color value of 83.5.

[0143] The preparation method specifically comprises:

[0144] Adipic acid, terephthalic acid, and 1,4-butanediol were weighed in a molar ratio of 1:1:2.5, mixed evenly, and then added with the rare earth-titanium bimetallic nanostructured catalyst, wherein the mass of the rare earth-titanium bimetallic nanostructured catalyst was 0.05% of the total mass of the adipic acid, terephthalic acid, and 1,4-butanediol. An esterification reaction was carried out under nitrogen protection; the esterification temperature was 160°C, and the reaction time was 3 hours;

[0145] Then, the temperature was gradually increased to 200°C at a heating rate of 10°C / h, and the vacuum degree was reduced from 1000Pa to 10Pa. The polycondensation reaction time was 5h to complete the polycondensation reaction. Finally, the polybutylene adipate / terephthalate was obtained after pelletizing and drying.

[0146] Example 6

[0147] This embodiment provides polybutylene adipate / terephthalate and a preparation method thereof. The polybutylene adipate / terephthalate (PBAT) is prepared from raw materials including adipic acid, terephthalic acid, and 1,4-butanediol, and is catalyzed by the rare earth-titanium bimetallic nanostructured catalyst of Example 3 through a one-pot process.

[0148] The polybutylene adipate / terephthalate (PBAT) has a terminal carboxyl content of 12.9 mol / t, a molecular weight of 103,300 g / mol, a molecular weight distribution index of 1.74, and an L value in color value of 83.0.

[0149] The preparation method specifically comprises:

[0150] Adopting the molar ratio of 1:1:2.5 of adipic acid, terephthalic acid and 1,4-butanediol, mixing uniformly, then adding the above rare earth-titanium bimetallic nano-structured catalyst, the mass of the rare earth-titanium bimetallic nano-structured catalyst is 0.05% of the total mass of adipic acid, terephthalic acid and 1,4-butanediol, and esterification occurs under the protection of nitrogen; the esterification temperature is 160℃, and the time is 2.5h;

[0151] Then gradient heating to 200℃ at a rate of 10℃ / h, then reducing the vacuum degree from 1000Pa to 10Pa, the polycondensation reaction time is 4h, and the polycondensation reaction is completed, finally through the line cutting and drying, the polybutylene adipate / terephthalate is obtained.

[0152] Comparative Example 1

[0153] Commercially available tetrabutyl titanate is used as the catalyst.

[0154] In the present comparative example, the hydrolysis half-life of the tetrabutyl titanate is 30 days.

[0155] Comparative Example 2

[0156] The catalyst prepared in Comparative Example 3 is used in the application with the application number 202410400269.2 and the invention name of: a new type of high-efficiency catalyst and its preparation method and application in PBAT synthesis.

[0157] In the present comparative example, the hydrolysis half-life of the catalyst is 26 days.

[0158] Comparative Example 3

[0159] The present comparative example is a polybutylene adipate / terephthalate and its preparation method, the preparation raw materials of the polybutylene adipate / terephthalate (PBAT) include adipic acid, terephthalic acid and 1,4-butanediol, and the commercially available tetrabutyl titanate in Comparative Example 1 is catalyzed to obtain by one-pot method.

[0160] The carboxyl end group content of the polybutylene adipate / terephthalate (PBAT) is 25.6mol / t, the molecular weight is 75000g / mol, the molecular weight distribution index is 2.7, and the L value in the color value is 75.3.

[0161] The preparation method specifically includes:

[0162] Adipic acid, terephthalic acid, and 1,4-butanediol were weighed in a molar ratio of 1:1:2.5, mixed evenly, and then commercially available tetrabutyl titanate was added, with the mass of the commercially available tetrabutyl titanate being 0.05% of the total mass of the adipic acid, terephthalic acid, and 1,4-butanediol. An esterification reaction was carried out under nitrogen protection at a temperature of 160°C for 3 hours.

[0163] Then, the temperature was gradually increased to 200°C at a heating rate of 10°C / h, and the vacuum degree was reduced from 1000Pa to 10Pa. The polycondensation reaction time was 7h to complete the polycondensation reaction. Finally, the polybutylene adipate / terephthalate was obtained after pelletizing and drying.

[0164] Comparative Example 4

[0165] This comparative example is a polybutylene adipate / terephthalate and a preparation method thereof. The raw materials for preparing the polybutylene adipate / terephthalate (PBAT) include adipic acid, terephthalic acid, and 1,4-butanediol. The catalyst in comparative example 2 is catalyzed to prepare the PBAT by a one-pot process.

[0166] The polybutylene adipate / terephthalate (PBAT) has a terminal carboxyl content of 23.6 mol / t, a molecular weight of 87,000 g / mol, a molecular weight distribution index of 1.89, and an L value in color value of 80.3.

[0167] The preparation method specifically comprises:

[0168] Adipic acid, terephthalic acid, and 1,4-butanediol were weighed in a molar ratio of 1:1:2.5, mixed evenly, and then commercially available tetrabutyl titanate was added, with the mass of the commercially available tetrabutyl titanate being 0.05% of the total mass of the adipic acid, terephthalic acid, and 1,4-butanediol. An esterification reaction was carried out under nitrogen protection at a temperature of 160°C for 3 hours.

[0169] Then, the temperature was gradually increased to 200°C at a heating rate of 10°C / h, and the vacuum degree was reduced from 1000Pa to 10Pa. The polycondensation reaction time was 5h to complete the polycondensation reaction. Finally, the polybutylene adipate / terephthalate was obtained after pelletizing and drying.

[0170] The performance of the PBAT prepared in the examples and comparative examples and the catalysts used were compared. The comparative example results are shown in Table 1:

[0171] Table 1 Test data of embodiments and comparative examples

[0172]

[0173] The test method for the terminal carboxyl group content is GB / T 14190-2017; the test method for the molecular weight is performed using gel permeation chromatography; and the test method for the color value is GB / T 2409-2020.

[0174] The hydrolysis half-life of the catalyst is measured under accelerated aging conditions of 70° C. and 85% relative humidity. The equipment used in the hydrolysis half-life test is a constant temperature and humidity aging box.

[0175] In summary, the present invention forms a bonding network by rare earth metal and titanium, and then combines the surface hydrophobic layer constructed by phosphate to improve the hydrolysis half-life of the catalyst in a high temperature and high humidity environment, and through the confinement effect of specific mesoporous silica, the particle size of the rare earth-titanium bimetallic clusters generated during the preparation of the catalyst is controlled to be 5-20nm, the specific surface area is improved, the exposure rate of the catalytic active sites is increased, and the polycondensation reaction time when preparing polyadipate / butylene terephthalate is effectively shortened. At the same time, while ensuring a short polycondensation time, the L value in the color value of the product polyadipate / butylene terephthalate is higher than the color value of the product prepared by the catalyst used in the prior art; due to the stable structure and uniform activity distribution of the rare earth-titanium bimetallic nanostructured catalyst prepared by the present invention, the molecular weight distribution index of polyadipate / butylene terephthalate is reduced, further improving the quality of thin film plastic products prepared with polyadipate / butylene terephthalate as raw material.

[0176] It should be understood that the present invention is not limited to the above description and that various modifications and changes can be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A rare earth-titanium bimetallic nanostructured catalyst, characterized in that: The catalyst is prepared by modifying a supported catalyst precursor using a P=O group in a phosphate ester and coating the supported catalyst precursor. and Surface coordination structure; Wherein, the structural formulas of the groups R1, R2, R3, and R4 are independently 、 、 One of, M is a rare earth metal; The supported catalyst precursor is obtained by anchoring and loading a mixed oxide sol network as a precursor with an amino support having a Si-O-Si-Y bond through a Ti-O-Si bond; The precursor is a diketone compound chelated with titanate, which is then hydrolyzed and condensed with rare earth metal ions to form a mixed oxide sol network with Ti-O-Ti bonds and Ti-OM bonds; The preparation method of the rare earth-titanium bimetallic nanostructured catalyst comprises the following steps: Step 1, precursor synthesis: titanate and rare earth metal salt are dissolved in an organic solvent, diketone compound solution is added, and stirring is carried out under the protection of inert gas. After stirring, an inorganic acid aqueous solution is added dropwise to react to form a sol, and then aged and dried to obtain a precursor; Step 2, preparing an amino carrier: vacuum-activating the nano-dispersed carrier, and then refluxing it with a silane coupling agent in a first organic benzene solvent to obtain an amino carrier; Step 3, preparation of supported catalyst precursor: mixing the precursor and the amino support, performing vacuum impregnation, and then calcining to obtain the supported catalyst precursor; Step 4, preparation of a rare earth-titanium bimetallic nanostructured catalyst: dispersing a supported catalyst precursor in a second organic benzene solvent, adding a phosphate ester to perform surface modification, then centrifuging and washing, and vacuum drying to obtain the rare earth-titanium bimetallic nanostructured catalyst; The nano-dispersed carrier in step 2 is mesoporous silica.

2. The rare earth-titanium bimetallic nanostructured catalyst according to claim 1, characterized in that: The phosphate ester is one or more of bis(2-ethylhexyl) phosphate, triisooctyl phosphate, and triphenyl phosphate.

3. The rare earth-titanium bimetallic nanostructured catalyst according to claim 1, characterized in that: The rare earth metal is one or more of lanthanum, cerium and neodymium.

4. The rare earth-titanium bimetallic nanostructured catalyst according to claim 1, characterized in that: The Y in the Si-O-Si-Y bond is an alkyl group containing an amino group, wherein the number of C atoms in the alkyl group is any integer between 2 and 6.

5. The rare earth-titanium bimetallic nanostructured catalyst according to claim 1, characterized in that: The diketone compound in step 1 is acetylacetone.

6. A method for preparing polybutylene adipate / terephthalate, characterized in that: The steps include: Weigh adipic acid, terephthalic acid, and 1,4-butanediol, mix them evenly, then add the rare earth-titanium bimetallic nanostructured catalyst according to any one of claims 1 to 5, and carry out an esterification reaction under the protection of an inert gas; Then, the temperature is gradually increased and the vacuum degree is reduced to complete the polycondensation reaction and obtain the polybutylene adipate / terephthalate.

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