A hydrolysis-resistant titanium-based catalyst, its preparation method and application

Abstract

The present invention provides a hydrolysis-resistant titanium catalyst and its preparation method and application, which belongs to the technical field of catalyst preparation. The present invention uses butyl titanate as a raw material, adopts a high-speed and low-temperature reaction system, and uses dihydroxy alcohol as a complexing agent to synthesize a hydrolysis-resistant titanium catalyst. The catalyst has excellent hydrolysis resistance and can stably exist without hydrolysis under high temperature conditions (180-220°C). The catalyst prepared by the present invention has the characteristics of high activity, selectivity, good dispersibility, few side reactions, nanometer size, high catalytic efficiency, wide range of applications, low cost, low energy consumption, strong stability and environmental protection. Compared with the traditional titanium catalyst synthesis process, the titanium content in the hydrolysis-resistant titanium catalyst prepared by the present invention is 0.1-10%, which is more suitable for the preparation of catalysts with relatively high titanium content.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and in particular to a hydrolysis-resistant titanium-based catalyst and a preparation method thereof. Background Art

[0002] In chemical production, catalysts have a very wide range of applications. The use of catalysts plays a key role in production efficiency and product performance, especially in the polyester and polyurethane industries, where catalysts play a decisive role in product performance.

[0003] Antimony-based catalysts are highly favored due to their high catalytic activity, heat resistance and stable processing. However, with the development of science and technology, the upgrading of product performance and the strengthening of people's environmental awareness, heavy metal antimony-based catalysts are gradually being eliminated due to serious environmental pollution, complex preparation process and high cost. Antimony is a heavy metal and poses a serious threat to human health.

[0004] Titanium-based catalysts are also attracting attention for their high activity, low cost, low dosage, pollution-free, readily available, low production of side reactions, energy-saving and cost-reducing properties, and environmental friendliness. Titanium-based catalysts are approximately 10 times more active than antimony-based catalysts. Therefore, they can effectively reduce the consumption of scarce resources and mitigate the irreversible environmental impacts of resource extraction. Furthermore, compared to antimony-based catalysts, titanium-based catalysts offer advantages in terms of raw material availability and manufacturing process, resulting in lower costs. Furthermore, because titanium-based catalysts do not require complex application and preparation systems, the dosage required is only 5-10% of that of antimony-based catalysts, significantly reducing industrialization costs. However, titanium-based catalysts are prone to hydrolysis, producing precipitates or flocs, which can affect subsequent reactions. For example, Chinese patent CN 103772673 A reports the use of a bis(hydroxy)titanium alkoxide catalyst to synthesize PET polyester chips. The resulting polyurethane chips exhibit a non-yellowish color. However, the titanium-based catalyst used in this application readily decomposes upon contact with water, affecting the catalyst's catalytic efficiency.

[0005] Currently, there is an increasing demand for new, highly efficient, and heavy metal-free green and environmentally friendly catalysts. Domestic research on the efficient catalytic degradation of polymers such as polylactic acid, polyester, and polyurethane coatings requires high-efficiency catalysts for polymerization, resulting in high-molecular-weight, high-quality polymer products. In particular, catalysts must exhibit excellent hydrolysis resistance during polymer synthesis. Therefore, improving the hydrolysis resistance of catalysts to protect them from the effects of water, reducing the polymer's influence on the catalyst's moisture content, and improving product quality are urgent issues. The search for new, green and environmentally friendly titanium-based, hydrolysis-resistant catalysts is urgent. Summary of the Invention

[0006] The purpose of the present invention is to provide a hydrolysis-resistant titanium catalyst and a preparation method and application thereof. The titanium catalyst has excellent hydrolysis resistance, does not contain heavy metals, and is green and environmentally friendly.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing a hydrolysis-resistant titanium-based catalyst, comprising the following steps:

[0009] Mixing a titanate compound and a dispersant, adding a small molecule alcohol solution dropwise to the resulting mixture, and performing a first complexation reaction under first stirring conditions to obtain a first crude product; the temperature of the first complexation reaction is 20 to 60° C., and the first stirring rate is 1500 to 10000 r / min;

[0010] subjecting the first crude product to a second complexation reaction under second stirring conditions to obtain a second crude product; the temperature of the second complexation reaction is 60 to 100° C., and the speed of the second stirring is 1500 to 10000 r / min;

[0011] The second crude product is mixed with a dihydroxy alcohol complexing agent, and then subjected to a third complexing reaction. The obtained crude product is vacuum distilled to obtain a hydrolysis-resistant titanium-based catalyst.

[0012] Preferably, the titanate compound includes one or more of tetraisopropyl titanate, n-butyl titanate, tetrabutyl titanate and n-propyl titanate.

[0013] Preferably, the dispersant is ethanol, polyacrylamide or polyvinyl alcohol; the mass ratio of the phthalate compound to the dispersant is (30-50): (200-300).

[0014] Preferably, the small molecule alcohol in the small molecule alcohol solution includes monohydric alcohol and / or dihydric alcohol; the monohydric alcohol includes n-butanol and / or allyl alcohol, and the dihydric alcohol includes one or more of propylene glycol, 1,4-butanediol and 1,3-propylene glycol; the molar ratio of the titanate compound to the small molecule alcohol is 1:(3.5~5.5).

[0015] Preferably, the dihydroxy alcohol complexing agent is one or more of ethylene glycol, propylene glycol, 2,3-butanediol and 1,3-propylene glycol; and the mass ratio of the second crude product to the dihydroxy alcohol complexing agent is 1:(3.1-4.0).

[0016] Preferably, the first complex reaction lasts for 3 to 10 hours; the second complex reaction lasts for 2 to 5 hours; the second complex reaction is carried out under reflux conditions; the third complex reaction is carried out under static conditions, and the third complex reaction lasts for 8 to 96 hours.

[0017] Preferably, the vacuum degree of the vacuum distillation is less than -0.09 MPa, the temperature of the vacuum distillation is 100-150° C., and the time is 3-5 hours.

[0018] The present invention provides a hydrolysis-resistant titanium-based catalyst prepared by the preparation method described in the above technical solution, comprising a titanate compound-small molecule alcohol-dihydroxy alcohol complex.

[0019] Preferably, the titanium content in the hydrolysis-resistant titanium-based catalyst is 0.1 to 10% by mass.

[0020] The present invention provides the use of the hydrolysis-resistant titanium catalyst described in the above technical solution in catalytic synthesis of polyethylene terephthalate, or in catalytic degradation of polyurethane, polycaprolactone or polylactic acid.

[0021] The present invention provides a preparation method of a hydrolysis-resistant titanium-based catalyst, comprising the following steps: mixing a titanate compound and a dispersant, dripping a small molecule alcohol solution into the obtained mixture, performing a first complexation reaction under a first stirring condition to obtain a first crude product; the temperature of the first complexation reaction is 20-60°C, and the first stirring rate is 1500-10000 r / min; performing a second complexation reaction on the first crude product under a second stirring condition to obtain a second crude product; the temperature of the second complexation reaction is 60-100°C, and the second stirring rate is 1500-10000 r / min; mixing the second crude product with a dihydroxy alcohol complexing agent, performing a third complexation reaction, and vacuum distilling the obtained crude product to obtain the hydrolysis-resistant titanium-based catalyst. The present invention uses titanate compounds as raw materials, adopts a high-speed and low-temperature reaction system, and uses small molecule alcohols and dihydroxy alcohols as complexing agents to synthesize a hydrolysis-resistant titanium-based catalyst. The synthesized catalyst contains Ti-O and C-C bonds. The Ti-O and C-C bonds are extremely strong and have large bond energy. They can exist stably in the system and are not easy to break. Therefore, they have good hydrolysis resistance and can exist stably under experimental high temperature conditions (180-220°C).

[0022] The hydrolysis-resistant titanium catalyst prepared by the present invention has a core-shell structure and is nanometer-sized (about 100 nm), which can increase the surface particles, improve the reaction activity, and thus improve the catalytic efficiency.

[0023] The catalyst prepared by the present invention contains many methylene groups (mainly provided by dihydroxy alcohols), which can have good solubility with the alcoholic hydroxyl groups in the alcoholysis agent during the degradation process, thereby achieving excellent dispersibility. At the same time, it also has good compatibility with water to avoid catalyst hydrolysis.

[0024] The catalyst prepared by the present invention has a wide range of applications: it can be applied to polyethylene terephthalate, polyurethane, polycaprolactone or polylactic acid. These substances all contain C=O or CO bonds, which generally break during degradation. Therefore, the catalyst can accelerate degradation and has excellent catalyst selectivity.

[0025] The hydrolysis-resistant titanium catalyst prepared by the present invention is applied to the downstream polymerization of PET or in the catalytic degradation process of polymers such as PU, PCL, and PLA. Due to its characteristics of small dosage, high catalytic efficiency, hydrolysis resistance, nanometer size, small residue in the product after catalysis, and no pollution, the product is endowed with excellent properties such as narrow distribution, few metal ions and low odor, which can increase the production catalytic efficiency of downstream industrial products and better meet the development trend of the production industry using this catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the infrared spectrum of the hydrolysis-resistant titanium catalyst prepared in Example 1;

[0027] Figure 2 This is a transmission electron micrograph of the hydrolysis-resistant titanium-based catalyst prepared in Example 1;

[0028] Figure 3 This is a SEM image of the polyurethane thermal insulation material prepared in Application Example 1;

[0029] Figure 4 This is the infrared spectrum of the polyurethane thermal insulation material prepared in Application Example 1. DETAILED DESCRIPTION

[0030] The present invention provides a method for preparing a hydrolysis-resistant titanium-based catalyst, comprising the following steps:

[0031] Mixing a titanate compound and a dispersant, adding a small molecule alcohol solution dropwise to the resulting mixture, and performing a first complexation reaction under first stirring conditions to obtain a first crude product; the temperature of the first complexation reaction is 20 to 60° C., and the first stirring rate is 1500 to 10000 r / min;

[0032] subjecting the first crude product to a second complexation reaction under second stirring conditions to obtain a second crude product; the temperature of the second complexation reaction is 60 to 100° C., and the speed of the second stirring is 1500 to 10000 r / min;

[0033] The second crude product is mixed with a dihydroxy alcohol complexing agent, and then subjected to a third complexing reaction. The obtained crude product is vacuum distilled to obtain a hydrolysis-resistant titanium-based catalyst.

[0034] In the present invention, unless otherwise specified, the raw materials required for preparation are all commercially available products well known to those skilled in the art.

[0035] The present invention comprises mixing a titanate compound and a dispersant, adding a small molecule alcohol solution dropwise to the resulting mixture, and performing a first complexation reaction under first stirring conditions to obtain a first crude product. In the present invention, the titanate compound preferably comprises one or more of tetraisopropyl titanate, n-butyl titanate, tetrabutyl titanate, and n-propyl titanate. When the titanate compound comprises more than one of the aforementioned compounds, the present invention does not specifically limit the ratio of the different types of titanate compounds, and any ratio may be used.

[0036] In the present invention, the dispersant is preferably ethanol, polyacrylamide, or polyvinyl alcohol; the mass ratio of the phthalate compound to the dispersant is preferably (30-50):(200-300), more preferably (35-43.2):(220-260). The present invention utilizes the dispersant to fully disperse the titanate compound during the reaction, rapidly and uniformly forming nanoscale particles.

[0037] The present invention has no particular limitation on the process of mixing the titanate compound and the dispersant. The materials can be uniformly mixed according to a process well known in the art.

[0038] In the present invention, the small molecule alcohol in the small molecule alcohol solution preferably includes monohydric alcohol and / or dihydric alcohol; the monohydric alcohol preferably includes n-butanol and / or allyl alcohol, and the dihydric alcohol preferably includes one or more of propylene glycol, 1,4-butanediol and 1,3-propylene glycol; when the small molecule alcohol is several of the above, the present invention has no special limitation on the ratio of different types of small molecule alcohols, and any ratio is acceptable.

[0039] In the present invention, the solvent of the small molecule alcohol solution is preferably anhydrous ethanol; the mass ratio of the small molecule alcohol to the solvent in the small molecule alcohol solution is preferably 1:(2.5-4.5), more preferably 1:(3.1-3.5).

[0040] In the present invention, the molar ratio of the titanate compound to the small molecule alcohol is preferably 1:(3.5-5.5), more preferably 1:(4.0-5.0).

[0041] In the present invention, the first complexation reaction is preferably carried out in a pressure-resistant reactor. The present invention preferably uses nitrogen to replace the air in the pressure-resistant reactor until the oxygen content in the pressure-resistant reactor is less than 50 ppm, and then adds a small molecule alcohol solution dropwise to the obtained mixed material to avoid rapid reaction of the titanate compound with moisture in the air, which may lead to impure raw materials.

[0042] In the present invention, the dropwise addition rate of the small molecule alcohol solution to the obtained mixed material is preferably 6 to 18 s / drop, more preferably 12 s / drop; the first stirring rate is 1500 to 10000 r / min, preferably 3000 to 8000 r / min; the present invention adopts a slow dropwise accelerated stirring method to help the titanate compound and the small molecule alcohol solution to fully react, and it is easier to form a nanometer-level size, thereby greatly increasing the specific surface area of the catalyst particles, so that the catalyst has more active sites and activity, and improves the catalytic efficiency.

[0043] In the present invention, the first complexation reaction is preferably carried out under oil bath conditions; the temperature of the first complexation reaction is 20-60°C, preferably 30-50°C; the time of the first complexation reaction is preferably 3-10 hours, more preferably 4-8 hours.

[0044] During the first complexation reaction, the dispersant exerts a dispersing effect, and small molecule alcohol is introduced as a monomer to supplement hydroxyl groups, thereby forming a hydrogen bond complex between alcohol hydroxyl groups and titanate molecules.

[0045] After obtaining the first crude product, the present invention performs no further treatment and subjects the first crude product to a second complexation reaction under second stirring conditions to obtain a second crude product. In the present invention, the air in the reactor is preferably replaced with nitrogen before the second complexation reaction is performed; the second stirring rate is 1500 to 10000 r / min, preferably 3000 to 8000 r / min; the use of high-speed stirring in the present invention facilitates rapid dispersion of the raw materials for the complexation reaction, resulting in saturation of the product.

[0046] In the present invention, the temperature of the second complexation reaction is 60-100°C, preferably 70-90°C; the duration of the second complexation reaction is preferably 2-5 hours, more preferably 3-4 hours; the second complexation reaction is preferably carried out under reflux conditions; the present invention has no particular limitation on the reflux process, which can be carried out according to processes well known in the art. The present invention has no particular limitation on the heating rate from the temperature of the first complexation reaction to the temperature of the second complexation reaction, which can be carried out according to processes well known in the art.

[0047] The present invention utilizes the second complexation reaction to promote the titanate compound that has not participated in the reaction during the first complexation reaction to continue complexing with the hydroxyl group.

[0048] In the second complexation reaction process of the present invention, no drugs need to be added to the system. If the product is in a jelly-like state after the first complexation reaction, a small amount of ethanol can be appropriately added to make the system in a flowable liquid state.

[0049] After obtaining the second crude product, the present invention mixes the second crude product with a dihydroxy alcohol complexing agent, performs a third complexing reaction, and vacuum distills the resulting crude product to obtain a hydrolysis-resistant titanium-based catalyst. In the present invention, the dihydroxy alcohol complexing agent is preferably one or more of ethylene glycol, propylene glycol, 2,3-butanediol, and 1,3-propylene glycol. When the dihydroxy alcohol complexing agent is more than one of the above, the present invention does not specifically limit the ratio of the different types of dihydroxy alcohol complexing agents, and any ratio can be used.

[0050] In the present invention, the mass ratio of the second crude product to the dihydroxy alcohol complexing agent is preferably 1:(3.1-4.0), more preferably 1:(3.2-3.6).

[0051] In the present invention, the second crude product is preferably not subjected to any treatment and is directly mixed with the dihydroxy alcohol complexing agent. The present invention has no special limitation on the process of mixing the second crude product with the dihydroxy alcohol complexing agent, and the materials can be uniformly mixed according to the process well known in the art.

[0052] In the present invention, the third complexation reaction is preferably carried out under static conditions, and the time of the third complexation reaction is preferably 8 to 96 hours, more preferably 15 to 80 hours, and further preferably 30 to 60 hours; the third complexation reaction is preferably carried out at room temperature; the present invention has no special limitation on the process of lowering the temperature from the second complexation reaction to room temperature, and can be carried out according to the process well known in the art.

[0053] The present invention utilizes the third complexation to make the titanate compound not involved in the complexation react with the dihydroxy alcohol complexing agent to form a complex body, so that the complex body no longer has the ability to react with other hydroxyl products.

[0054] After the third complexation reaction process is completed, the uncomplexed small molecule alcohol and dihydroxy alcohol in the system are removed by vacuum distillation. This process can further purify the product, making the complexation stronger and allowing it to exist stably in later use.

[0055] After the third complexation reaction is completed, the crude product is subjected to vacuum distillation. The vacuum degree of the vacuum distillation is preferably less than -0.09 MPa, the temperature of the vacuum distillation is preferably 100-150°C, more preferably 120-130°C, and the time is preferably 3-5 hours, more preferably 3.5-4.5 hours. The vacuum distillation is preferably performed in an oil bath. The present invention removes residual dispersant and small molecule alcohol solution through vacuum distillation.

[0056] The present invention provides a hydrolysis-resistant titanium-based catalyst prepared by the preparation method described in the above technical solution, comprising a titanate compound-small molecule alcohol-dihydroxy alcohol complex; the hydrolysis-resistant titanium-based catalyst is a liquid catalyst.

[0057] In the present invention, the titanium content in the hydrolysis-resistant titanium-based catalyst is preferably 0.1 to 10% by mass, more preferably 1 to 8%, and even more preferably 3 to 6%.

[0058] The present invention provides the use of the hydrolysis-resistant titanium-based catalyst described in the above technical solution in the catalytic synthesis of polyethylene terephthalate, or in the catalytic degradation of polyurethane, polycaprolactone, or polylactic acid. The present invention does not particularly limit the method of application, and the application can be carried out according to methods well known in the art.

[0059] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0060] Example 1

[0061] 43.2 g of n-butyl titanate and 260 g of ethanol were uniformly mixed, placed in a 2 L three-necked flask, placed in a pressure-resistant reactor, and placed in an oil bath and heated to 30° C.; after the air in the pressure-resistant reactor was replaced with nitrogen until the oxygen content in the pressure reactor was less than 50 ppm, 13.5 g of an ethanol solution of a small molecule alcohol (allyl alcohol) (the mass ratio of the two was 1:3) was dropwise added to the three-necked flask at a rate of 12 s / drop, and a first complexation reaction was carried out at 30° C. and 1500 r / min for 4 h to obtain a first crude product;

[0062] The temperature was raised to 70° C., the first crude product was refluxed for 3 h, and a second complexation reaction was carried out at 1500 r / min for 2 h to obtain a second crude product;

[0063] 1200 g of ethylene glycol was added to the second crude product (300 g), the resulting material was cooled to room temperature, allowed to stand for 12 h, and a third complex reaction was carried out for 8 h. The turbid material after standing was distilled at a vacuum degree of <-0.09 MPa and an oil bath of 110°C for 5 h to obtain a colorless, clear, hydrolysis-resistant titanium catalyst.

[0064] Example 2

[0065] 43.2 g of tetrabutyl titanate and 260 g of ethanol were uniformly mixed, placed in a 2 L three-necked flask, placed in a pressure-resistant reactor, and placed in an oil bath and heated to 30° C.; after the air in the pressure-resistant reactor was replaced with nitrogen until the oxygen content in the pressure reactor was less than 50 ppm, 13.5 g of an ethanol solution of a small molecule alcohol (1,3-propylene glycol) (the mass ratio of the two was 1:3.1) was dropwise added to the three-necked flask at a rate of 8 s / d, and a first complexation reaction was carried out at 30° C. and 2000 r / min for 5 h to obtain a first crude product;

[0066] The temperature was raised to 70° C., the first crude product was refluxed for 3 h, and a second complexation reaction was carried out at 2000 r / min for 3 h to obtain a second crude product;

[0067] 1200g of dihydroxy alcohol (ethylene glycol) was added to the second crude product (300g), the resulting material was cooled to room temperature, allowed to stand for 24h, and the third complex reaction was carried out for 16h. The turbid material after standing was distilled at a vacuum degree of <-0.09MPa and an oil bath of 110°C for 5h to obtain a colorless, clear, hydrolysis-resistant titanium catalyst.

[0068] Example 3

[0069] 43.2 g of n-propyl titanate and 260 g of ethanol were uniformly mixed, placed in a 2 L three-necked flask, placed in a pressure-resistant reactor, and placed in an oil bath and heated to 30° C.; after the air in the pressure-resistant reactor was replaced with nitrogen until the oxygen content in the pressure reactor was less than 50 ppm, 13.5 g of an ethanol solution of a small molecule alcohol (allyl alcohol) (the mass ratio of the two was 1:3.2) was dropwise added to the three-necked flask at a rate of 6 s / d, and a first complexation reaction was carried out at 30° C. and 2500 r / min for 6 h to obtain a first crude product;

[0070] The temperature was raised to 70° C., the first crude product was refluxed for 3 h, and a second complexation reaction was carried out at 2000 r / min for 4 h to obtain a second crude product;

[0071] 1200g of dihydroxy alcohol (ethylene glycol) was added to the second crude product (300g), the resulting material was cooled to room temperature, allowed to stand for 36h, and the third complex reaction was carried out for 24h. The turbid material after standing was distilled at a vacuum degree of <-0.09MPa and an oil bath of 120°C for 4.5h to obtain a colorless, clear, hydrolysis-resistant titanium catalyst.

[0072] Example 4

[0073] Mix 43.2 g of n-butyl titanate and 260 g of ethanol, put them into a 2 L three-necked flask, place it in a pressure-resistant reactor, and heat it to 30 ° C in an oil bath;

[0074] After nitrogen was used to replace the air in the pressure reactor until the oxygen content in the pressure reactor was less than 50 ppm, 13.5 g of an ethanol solution of a small molecular alcohol (allyl alcohol) (the mass ratio of the two was 1:3.3) was added dropwise into the three-necked flask at a rate of 8 s / d, and a first complexation reaction was carried out at 30°C and 2500 r / min for 7 h to obtain a first crude product;

[0075] The temperature was raised to 70° C., the first crude product was refluxed for 3 h, and a second complexation reaction was carried out at 3000 r / min for 5 h to obtain a second crude product;

[0076] 1200g of dihydroxy alcohol (ethylene glycol) was added to the second crude product (300g), the resulting material was cooled to room temperature, allowed to stand for 48h, and the third complex reaction was carried out for 32h. The turbid material after standing was distilled at a vacuum degree of <-0.09MPa and an oil bath of 100°C for 6h to obtain a colorless, clear, hydrolysis-resistant titanium catalyst.

[0077] Example 5

[0078] 43.2 g of tetraisopropyl titanate and 260 g of ethanol were uniformly mixed, placed in a 2 L three-necked flask, placed in a pressure-resistant reactor, and placed in an oil bath and heated to 30° C.; after the air in the pressure-resistant reactor was replaced with nitrogen until the oxygen content in the pressure reactor was less than 50 ppm, 13.5 g of an ethanol solution of a small molecule alcohol (1,3-propylene glycol) (the mass ratio of the two was 1:3.4) was dropwise added to the three-necked flask at a rate of 12 s / d, and a first complexation reaction was carried out at 30° C. and 3000 r / min for 8 h to obtain a first crude product;

[0079] The temperature was raised to 70° C., the first crude product was refluxed for 3 h, and a second complexation reaction was carried out at 3000 r / min for 5 h to obtain a second crude product;

[0080] 1200g of dihydroxy alcohol (ethylene glycol) was added to the second crude product (300g), the resulting material was cooled to room temperature, allowed to stand for 60h, and the third complex reaction was carried out for 40h. The turbid material after standing was distilled at a vacuum degree of <-0.09MPa and an oil bath of 120°C for 4h to obtain a colorless, clear, hydrolysis-resistant titanium catalyst.

[0081] Example 6

[0082] Mix 43.2 g of n-propyl titanate and 260 g of ethanol, put them into a 2 L three-necked flask, place it in a pressure-resistant reactor, and heat it to 30 ° C in an oil bath;

[0083] After nitrogen was used to replace the air in the pressure reactor until the oxygen content in the pressure reactor was less than 50 ppm, 13.5 g of an ethanol solution of a small molecular alcohol (1,3-propylene glycol) (the mass ratio of the two was 1:3.5) was added dropwise into the three-necked flask at a rate of 16 s / d, and a first complexation reaction was carried out at 30°C and 3000 r / min for 9 h to obtain a first crude product;

[0084] The temperature was raised to 70° C., the first crude product was refluxed for 3 h, and a second complexation reaction was carried out at 3000 r / min for 5 h to obtain a second crude product;

[0085] 1200g of dihydroxy alcohol (ethylene glycol) was added to the second crude product (300g), the resulting material was cooled to room temperature, allowed to stand for 72h, and the third complex reaction was carried out for 48h. The turbid material after standing was distilled at a vacuum degree of <-0.09MPa and an oil bath of 110°C for 5h to obtain a colorless, clear, hydrolysis-resistant titanium catalyst.

[0086] Application Example 1

[0087] 80 g of waste polyurethane elastomer was mixed with 20 g of 1,3-propylene glycol, 60 g of triethanolamine, and 0.08 g of the hydrolysis-resistant titanium catalyst prepared in Example 1, stirred at 180° C. for 3 h, and cooled to room temperature to obtain a polyether polyol.

[0088] 10 g of the polyether polyol was mixed with 15 g of polyether 4110, 0.5 g of glucose, 4.5 g of monofluorodichloroethane HCFC-141b, 0.1 g of silicone oil L-600, 0.1 g of tris(dimethylaminopropyl)hexahydrotriazine (PC-41) and 0.3 g of water to form a white material, and then stirred with 10 g of polymethylene polyphenyl isocyanate (PAPI-27) for 12 seconds to foam, and cooled to obtain a polyurethane thermal insulation material.

[0089] Application Example 2

[0090] 80 g of waste polyurethane elastomer was mixed with 40 g of 1,3-butanediol, 40 g of diethylene glycol, and 0.08 g of the hydrolysis-resistant titanium catalyst prepared in Example 2, stirred at 190° C. for 5 h, and cooled to room temperature to obtain a polyether polyol.

[0091] 10g of the polyether polyol was mixed with 0.8g of sorbitol, 4.8g of HCFC-141b, 0.2g of silicone oil CGY-5, 0.2g of PC-41 and 0.4g of water to obtain a white material, which was then stirred with 11g of PAPI-27 for 11s to foam and then cooled to obtain a polyurethane thermal insulation material.

[0092] Application Example 3

[0093] 80 g of waste polyurethane elastomer was mixed with 60 g of 1,2-propylene glycol, 20 g of diethylene glycol, and 0.12 g of the hydrolysis-resistant titanium catalyst prepared in Example 2, stirred at 200° C. for 2.5 h, and cooled to room temperature to obtain a polyether polyol.

[0094] 10 g of the polyether polyol was mixed with 10 g of polyether 4110, 4 g of HCFC-141b, 0.5 g of silicone oil CGY-5, 0.2 g of TMPDA and 0.1 g of water to obtain a white material, which was then stirred with 8.5 g of PAPI-27 for 16 seconds to foam and cooled to obtain a polyurethane thermal insulation material.

[0095] Comparative Application Example 1

[0096] The only difference from Application Example 1 is that 0.6 g of potassium hydroxide is used as the alkali metal catalyst to replace 0.08 g of the hydrolysis-resistant titanium catalyst prepared in Example 1 in Application Example 1, and the rest is the same as Application Example 1.

[0097] Comparative Application Example 2

[0098] The only difference from Application Example 2 is that 0.6 g of potassium hydroxide is used as the alkali metal catalyst to replace 0.08 g of the hydrolysis-resistant titanium catalyst prepared in Example 2 in Application Example 2, and the rest is the same as Application Example 2.

[0099] Comparative Application Example 3

[0100] The only difference from Application Example 3 is that 1.0 g of potassium hydroxide is used as the alkali metal catalyst to replace 0.12 g of the hydrolysis-resistant titanium catalyst prepared in Example 2 in Application Example 3, and the rest is the same as Application Example 3.

[0101] Performance testing and characterization

[0102] 1) The hydrolysis-resistant titanium catalyst prepared in Example 1 was subjected to infrared testing, and the results are shown in FIG. Figure 1 ;Depend on Figure 1 It can be seen that 400-700cm -1 The peaks that appear are mainly the stretching vibrations of Ti-O bonds; 2930 cm -1 and 2850cm -1 The peak that appears is the -CH2- stretching vibration peak; 1475-1000cm -1 The peaks appearing in the region are the CH in-plane bending vibration peak and the CO stretching vibration peak, respectively. The infrared spectrum shows that the structure of the self-made titanium catalyst is consistent with that of the self-made titanium catalyst. Therefore, it can be seen that the titanium catalyst was successfully prepared.

[0103] 2) The hydrolysis-resistant titanium catalyst prepared in Example 1 was subjected to TEM test. The results are shown in Figure 2 ;Depend on Figure 2The catalyst particles are approximately 100 nm in size, spherical, and exhibit a distinct core-shell structure. This demonstrates the surface effects unique to nanomaterials. The catalyst's small particle size increases the number of titanium atoms on its surface, resulting in greater surface area and surface tension, leading to higher chemical activity.

[0104] 3) The titanium catalysts prepared in Examples 1 to 6 were placed in water respectively. The products were soluble in water without generating flocculent precipitation, indicating that the catalysts did not undergo hydrolysis.

[0105] 4) The polyurethane thermal insulation material prepared in Example 1 was subjected to SEM testing, and the results are shown in Figure 3 ;Depend on Figure 3 It can be seen that the bubbles are evenly distributed, the foam skeleton is thick and complete, and there are no broken cracks or fractures, which shows that its microstructure is good and the compressive strength is relatively good; the bubbles are closely arranged, which shows that the foam has good thermal insulation performance.

[0106] 5) The catalytic degradation material prepared according to Example 1 was subjected to infrared testing, and the results were shown in Figure 4 ;Depend on Figure 4 It can be seen that at 3500-3300cm -1 A strong absorption band appears in the range of 1732-1708cm, which is the stretching vibration peak of alcohol hydroxyl group; -1 A strong absorption band appears near the benzene overtone peak; at 1054cm -1 A clear strong absorption band appears near , which is the absorption band of polyether polyurethane ether group. It can be concluded that the degradation product is a mixture of polyether polyol and aromatic polyol.

[0107] 6) The polyether polyols and polyurethane thermal insulation materials prepared in Examples 1 to 3 and Comparative Application Examples 1 to 3 were subjected to performance tests. The hydroxyl value of the degradation material and the density, compressive strength, and thermal conductivity of the foam after foaming were determined according to GB / T 12008.3-2009, GB / T 6343-2009, GB / T 8813-2008, and GB / T 10294-2008, respectively. The specific results are shown in Table 1.

[0108] Table 1 Performance data of polyether polyol and polyurethane insulation materials prepared in Application Examples 1 to 3 and Comparative Application Examples 1 to 3

[0109]

[0110]

[0111] As shown in Table 1, the hydrolysis-resistant titanium catalyst prepared in the present invention exhibits significantly better catalytic degradation performance than alkali metal catalysts within a certain dosage range. A comparison of Application Examples 1-2 with Comparative Application Examples 1-2 reveals that, under identical experimental conditions, when different catalysts were used to degrade waste polyurethane foam, the product degraded using a lower dosage of the hydrolysis-resistant titanium catalyst of the present invention outperformed the product degraded using a higher dosage of the alkali metal catalyst in terms of hydroxyl value, viscosity, density, compressive strength, and thermal conductivity. This demonstrates that the hydrolysis-resistant titanium catalyst prepared in the present invention exhibits superior catalytic efficiency to that of alkali metal catalysts and remains stable at temperatures between 180°C and 220°C without undergoing hydrolysis. However, a comparison of Application Example 3 with Comparative Application Example 3 clearly demonstrates that the catalytic performance of the alkali metal catalyst is superior to that of the titanium catalyst. This is due to the high efficiency of the titanium catalyst. Excessive addition can shorten the degradation segments of the waste polyurethane, leading to agglomeration of the small molecular segments, reducing the hydroxyl value of the degradation product and increasing its viscosity, thereby affecting the performance and structure of the recycled polyurethane material. The titanium catalyst prepared by the present invention has many methyl groups around it, which can have good compatibility with the alcoholic hydroxyl groups in the alcoholysis agent of the waste polyurethane in the reactor during the degradation process, thereby achieving excellent dispersibility and being more conducive to the degradation reaction. Therefore, the present invention only requires a low amount of titanium catalyst to achieve the preparation of recycled polyurethane materials.

[0112] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a hydrolysis-resistant titanium-based catalyst, characterized in that: The following steps are involved: A titanate compound and a dispersant are mixed, a small molecule alcohol solution is added dropwise to the resulting mixture, and a first complexation reaction is performed under first stirring conditions to obtain a first crude product; the temperature of the first complexation reaction is 20 to 60° C., and the first stirring rate is 1500 to 10000 r / min; the small molecule alcohol in the small molecule alcohol solution includes a monohydric alcohol and / or a dihydric alcohol, and the solvent is anhydrous ethanol; the monohydric alcohol includes n-butanol and / or allyl alcohol, and the dihydric alcohol includes one or more of propylene glycol, 1,4-butanediol, and 1,3-propylene glycol; the first complexation reaction is performed under a nitrogen atmosphere; and the oxygen content of the nitrogen atmosphere is less than 50 ppm; subjecting the first crude product to a second complexation reaction under second stirring conditions to obtain a second crude product; the temperature of the second complexation reaction is 60 to 100° C., and the speed of the second stirring is 1500 to 10000 r / min; The second crude product is mixed with a dihydroxy alcohol complexing agent, and then subjected to a third complexing reaction. The obtained crude product is vacuum distilled to obtain a hydrolysis-resistant titanium-based catalyst; The titanium content in the hydrolysis-resistant titanium catalyst is 3 to 10%; The hydrolysis-resistant titanium-based catalyst has a core-shell structure.

2. The preparation method according to claim 1, characterized in that The titanate compound includes one or more of tetraisopropyl titanate, n-butyl titanate, tetrabutyl titanate and n-propyl titanate.

3. The preparation method according to claim 1 or 2, characterized in that The dispersant is ethanol, polyacrylamide or polyvinyl alcohol; the mass ratio of the titanate compound to the dispersant is (30-50):(200-300).

4. The preparation method according to claim 1 or 2, characterized in that The molar ratio of the titanate compound to the small molecule alcohol is 1:(3.5-5.5).

5. The preparation method according to claim 1, characterized in that The dihydroxy alcohol complexing agent is one or more of ethylene glycol, propylene glycol, 2,3-butanediol and 1,3-propylene glycol; the mass ratio of the second crude product to the dihydroxy alcohol complexing agent is 1:(3.1-4.0).

6. The preparation method according to claim 1, characterized in that The time of the first complexation reaction is 3 to 10 hours; The second complex reaction lasts for 2 to 5 hours; the second complex reaction is carried out under reflux conditions; the third complex reaction is carried out under static conditions, and the third complex reaction lasts for 8 to 96 hours.

7. The preparation method according to claim 1, characterized in that The vacuum degree of the vacuum distillation is less than -0.09 MPa, the temperature of the vacuum distillation is 100-150° C., and the time is 3-5 hours.

8. The hydrolysis-resistant titanium-based catalyst prepared by the preparation method according to any one of claims 1 to 7, comprising a titanate compound-small molecule alcohol-dihydroxy alcohol complex.

9. Use of the hydrolysis-resistant titanium-based catalyst according to claim 8 in the catalytic synthesis of polyethylene terephthalate, or in the catalytic degradation of polyurethane, polycaprolactone or polylactic acid.

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