A method for preparing tridecyl trimellitate

Abstract

The present application relates to the technical field of chemical manufacturing, in particular to a preparation method of tridecanol trimellitate; the method comprises the following steps: preparing nano-Fe3O4, coating the nano-Fe3O4, grafting after the coating is completed to obtain a thiol-modified material, sulfonating the thiol-modified material to obtain a second catalyst, mixing the improved carbocyclic compound and tridecanol and adding the second catalyst to obtain an esterification reaction mixture. The first catalyst in the present application realizes the accurate oxidation of aromatic hydrocarbon methyl with high activity and selectivity, and the second catalyst realizes convenient separation and recycling while ensuring the esterification efficiency by virtue of its strong acid sites and magnetic response characteristics, overcomes the technical bottleneck of difficult separation and high residual amount of traditional homogeneous catalysts, introduces molecular distillation technology in the separation and purification link to complete the separation of light and heavy components with extremely short heating time and low temperature conditions, and maximizes the thermal stability and color advantage of the product.

Description

Technical Field

[0001] This invention relates to the field of chemical manufacturing technology, specifically to a method for preparing tridecyl trimellitate. Background Technology

[0002] Tridecyl trimellitate is an organic compound formed by the esterification reaction of tridecyl alcohol and trimellitic acid. It is a colorless to pale yellow transparent oily liquid at room temperature. It has low volatility, high thermal stability and oxidation stability. It is insoluble in water but miscible with most organic solvents. Due to the colorant dispersing ability and sunscreen solubility provided by its benzene ring structure, as well as the lubrication and moisturizing properties provided by its long-chain alkyl group, it is widely used in cosmetics, such as emollients, moisturizers, sunscreens, plastics industry and lubricant additives. It meets safety standards and has multi-field applicability, making it an important functional raw material in the chemical industry.

[0003] Traditional methods for preparing tridecyl alcohol trimellitate have several drawbacks, leading to increasingly serious environmental problems. Traditional catalysts are difficult to recover efficiently after the reaction, and residues may pollute the environment or affect product purity, increasing post-processing costs and environmental pressure. Secondly, the oxidation catalytic system is inefficient, and the esterification reaction requires harsh conditions such as high temperature and high pressure, resulting in high energy consumption, stringent equipment requirements, and the potential for side reactions that reduce the yield and quality stability of the target product. Post-processing processes pose a risk of thermal damage, and high-temperature operation can easily lead to product decomposition or structural destruction, affecting product performance such as color, stability, and biocompatibility. In addition, harsh reaction conditions may also exacerbate equipment corrosion and safety hazards, increasing the difficulty of industrial scale-up.

[0004] Therefore, the present invention provides a method for preparing tridecyl alcohol trimellitate to solve the aforementioned related technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing tridecyl alcohol trimellitate. At the process level, by synergistically combining ionic liquid media and gradient negative pressure esterification technology, a high conversion rate is achieved under temperature and pressure conditions lower than those of traditional processes, effectively avoiding the risk of side reactions of long-chain alcohols at high temperatures. At the same time, a closed-loop system for the staged recovery of catalyst, excess alcohol, and ionic liquid is constructed, significantly improving atom economy and process sustainability. The catalytic system adopts a bifunctional design. The first catalyst achieves precise oxidation of aromatic methyl groups with high activity and selectivity, while the second catalyst, with its strong acidic sites and magnetic response characteristics, ensures esterification efficiency while achieving convenient separation and recycling. This overcomes the technical bottlenecks of difficult separation and high residue of traditional homogeneous catalysts. Molecular distillation technology is introduced in the separation and purification stage to complete the separation of light and heavy components with extremely short heating time and low temperature conditions, maximizing the preservation of the product's thermal stability and color advantages.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing tridecyl trimellitate, the method comprising: A basic catalytic component was prepared by combining cobalt acetate and manganese acetate. The basic catalytic component was then pretreated to obtain the first catalyst. Acetic acid and pseudotrimethylbenzene were mixed to obtain an acetic acid solution containing pseudotrimethylbenzene. A first catalyst was added to the acetic acid solution containing pseudotrimethylbenzene to carry out the reaction. After the reaction was completed, the mixture was separated and dehydrated to obtain the modified carbocyclic compound. Nano-sized iron oxide was prepared, coated, and grafted to obtain a mercapto-modified material. The mercapto-modified material was sulfonated to obtain a second catalyst. The modified carbocyclic compound and tridecyl alcohol were mixed and the second catalyst was added to obtain an esterification reaction mixture. The second catalyst was recovered from the esterification reaction mixture and excess tridecaneol was separated to obtain a substrate mixture. Crude tridecaneol trimellitate was separated from the substrate mixture and purified to obtain tridecaneol trimellitate.

[0007] Furthermore, the specific steps for preparing the basic catalytic component by combining cobalt acetate and manganese acetate are as follows: N,N-dimethylformamide and acetonitrile were mixed and stirred at a mass ratio of 3.5 to 4.5:1 to obtain a basic mixed solvent. Cobalt acetate (8% to 12% by mass of acetonitrile) and manganese acetate (2% to 4% by mass) were added to the basic mixed solvent and stirred at 23 to 27°C for 25 to 35 minutes. After stirring, an organic ligand in the same proportion as cobalt acetate was added and stirring was continued to obtain an organic composite solution. The organic ligand was obtained by mixing 2-aminoterephthalic acid and 2-methylimidazole in equal proportions.

[0008] It should be further noted that the molar ratio of cobalt acetate, manganese acetate, 2-aminoterephthalic acid, and 2-methylimidazole is 1:0.35:1:1.

[0009] The organic composite solution was sealed and heated to 85–95°C, and reacted at a constant temperature for 20–26 h. After the reaction was completed, it was cooled to 23–27°C and filtered. The initial filter cake was collected and washed with anhydrous ethanol and N,N-dimethylformamide. After washing, it was vacuum dried at 65–75°C for 10–14 h to obtain the basic catalytic component.

[0010] Furthermore, the pretreatment of the basic catalytic components specifically involves: The basic catalytic component is mixed with anhydrous ethanol at a mass ratio of 1:28-32 and ultrasonically dispersed for 25-35 min to form a catalytic suspension. Molecular sieves of equal mass to the basic catalytic component are added to the catalytic suspension and stirred at 23-27℃ for 20-25 h. After stirring, the mixture is filtered, and the filtered product is collected. The filtered product is washed 2-4 times with anhydrous methanol and vacuum dried at 65-75℃ for 10-14 h to obtain the first catalyst.

[0011] Furthermore, the acetic acid solution containing pseudotrimethylbenzene is obtained by mixing pseudotrimethylbenzene and acetic acid at a mass ratio of 1:4.5 to 5.5.

[0012] Furthermore, the specific steps of adding the first catalyst to the acetic acid solution containing pseudotrimethylbenzene to carry out the reaction are as follows: Add 0.8%–1% of a first catalyst and 0.2%–0.3% of tetrabromoethane to an acetic acid solution containing pseudotrimethylbenzene. Purge nitrogen to displace oxygen and stir. Heat to 185–195°C and maintain pressure at 1.5–1.7 MPa. Then purge with air and react for 4–5 hours to obtain an oxidation reaction solution. Air is continuously introduced at a flow rate of 0.2–0.6 L / (min·100g pseudotrimethylbenzene), the gauge pressure inside the reactor is controlled at 1.5–1.7 MPa, the stirring speed is 500–800 r / min, and the air supply is stopped when the residual amount of pseudotrimethylbenzene detected by HPLC is ≤0.5 wt%.

[0013] Furthermore, the separation and dehydration process after the reaction is completed includes: The oxidation reaction solution was cooled to 75-85℃ and the pressure was reduced to atmospheric pressure. The cooled reaction solution was then cooled to 20-30℃ at a rate of 10℃ / h to form crystals, which were then filtered out. Deionized water was added to the crystals for washing. This process was repeated 1-3 times to obtain crude trimellitic acid. Crude trimellitic acid was dehydrated in an environment with a temperature of 190–200℃ and a pressure of 2–5 kPa for 1.5–2.5 h to form crude trimellitic anhydride. The crude trimellitic anhydride was then purified to obtain an improved carbocyclic compound.

[0014] It should be noted that the improved carbocyclic compound, namely trimellitic anhydride, has a significantly reduced color compared to trimellitic anhydride prepared by traditional processes, avoiding heavy metal contamination, and has a low content of the impurity phthalic anhydride. The specific purification steps are as follows: Crude trimellitic anhydride was added to ethyl acetate and dissolved by stirring at 75°C. The mixture was filtered while hot, and the filtrate was cooled to 10°C at a rate of 5°C / h to crystallize. The crystals were then filtered and dried under vacuum at 90°C and 4 kPa for 5 h.

[0015] Furthermore, the coating of nano-ferric oxide includes: Nano-iron oxide and anhydrous ethanol are mixed at a mass ratio of 1:4.5-5.5 and ultrasonically dispersed for 25-35 min to obtain a nano-iron oxide solution. Tetraethyl orthosilicate (35%-45% by mass of anhydrous ethanol) and ammonia (8%-12% by mass of 25%) are added to the nano-iron oxide solution and stirred at 23-27℃ for 5-7 h. After stirring, the magnetic material is separated by a magnet, washed with anhydrous ethanol 2-4 times, and dried at 75-85℃ for 1.5-2.5 hours to obtain coated iron(III) oxide.

[0016] It should be noted that the specific steps for preparing nano-ferric oxide are as follows: Deionized water, ferric chloride hexahydrate, and ferrous sulfate heptahydrate were mixed in a mass ratio of 50:2:1, heated to 80°C, and 25% ammonia water was added. The mixture was stirred and reacted for 1 hour. After the reaction was completed, the black solid was separated by a magnet, washed with deionized water until neutral, and dried under vacuum at 60°C for 12 hours to obtain nano-iron tetroxide.

[0017] The amount of ammonia added is 5% of the amount of deionized water.

[0018] Furthermore, after the coating is completed, grafting is performed, and the specific operation is as follows: Coated iron oxide was dispersed in anhydrous toluene at a mass ratio of 1:7-9, and 3-mercaptopropyltrimethoxysilane was added in an equal proportion to the coated iron oxide. The mixture was refluxed under nitrogen at 75-85°C for 10-14 hours. After the reaction was completed, the grafted product was separated by a magnet. The grafted product was washed 1-3 times with toluene and anhydrous ethanol, and dried in a vacuum at 55-65°C for 3.5-4.5 hours to obtain the mercapto-modified material.

[0019] Furthermore, the sulfonation of the mercapto-modified material includes: The mercaptomodified material, 30% hydrogen peroxide, and formic acid were mixed in a mass ratio of 1:1.5 to 2:2 to 3 and stirred at 45 to 55°C for 5.5 to 6.5 hours. After stirring, the sulfonated product was separated by a magnet, washed with deionized water to a pH of 6.8 to 7.2, and then washed 2 to 4 times with anhydrous ethanol. The product was then dried in a vacuum at 55 to 65°C for 5.5 to 6.5 hours to obtain the second catalyst.

[0020] Furthermore, the process of mixing the modified carbocyclic compound and tridecyl alcohol and adding a second catalyst includes: The modified carbocyclic compound, tridecaneol, 1-butyl-3-methylimidazolium hexafluorophosphate and the second catalyst were mixed in a mass ratio of 12-15:38-55:3-5:1 and the mixture was heated to 120-130℃ and stirred for 1-2 hours. During the reaction, samples were taken every 1 hour to measure the acid value. The reaction was stopped when the acid value was ≤0.50mgKOH / g and the residual amount of tridecaneol detected by GC no longer changed significantly.

[0021] Then the pressure is reduced to -0.08 to -0.09 MPa, and the temperature is raised to 160 to 170 °C. The reaction is carried out for 4 to 5 hours to obtain the esterification reaction mixture.

[0022] The second catalyst was recovered from the esterification reaction mixture, and excess tridecyl alcohol was separated to obtain a substrate mixture, specifically: Using a strong magnetic separator, the second catalyst is adsorbed onto the surface of the separator and then removed. Alternatively, a magnetic rod can be directly inserted into the esterification reaction mixture and stirred for adsorption, then removed and the adsorbed second catalyst is collected. It is then washed three times with anhydrous ethanol and dried under vacuum at 60°C for 4 hours.

[0023] The separation of crude tridecane alcohol trimellitate from a substrate mixture includes: placing the substrate mixture into a short-path molecular distillation apparatus (scraped film type), preheating it to 150°C, turning on the vacuum system to reduce the absolute pressure to 0.5 Pa, setting the heating wall temperature to 165°C and the internal condenser temperature to 60°C, turning on the scraper, and feeding the preheated substrate mixture into the molecular distillation apparatus to collect the light and heavy components. The light component is mainly excess tridecane alcohol, which rapidly condenses on the condenser surface and flows down the wall. The heavy component is mainly a base material containing crude tridecane alcohol trimellitate and 1-butyl-3-methylimidazolium hexafluorophosphate. The base material is transferred to a layering tank and allowed to stand for 2 hours to form upper and lower layers. The upper layer is crude tridecane alcohol trimellitate, and the lower layer is 1-butyl-3-methylimidazolium hexafluorophosphate.

[0024] The crude tridecyltriphenyl ester is purified, specifically as follows: The crude tridecyl alcohol trimellitate was washed with deionized water. After washing, anhydrous sodium sulfate was added, and the mixture was stirred and dried for 25-35 minutes and then filtered. After filtration, the mixture was dried under vacuum at 80°C and -0.095 MPa for 1 hour to obtain tridecyl alcohol trimellitate.

[0025] Compared with the prior art, the beneficial effects of the present invention are: This invention utilizes the self-assembly of cobalt acetate and manganese acetate under the action of organic ligands to form a bimetallic organic framework, which is then supported on SBA-15 molecular sieve to obtain the first catalyst. This catalyst selectively activates the three methyl groups of trimellitene in an air atmosphere using the synergistic effect of the bimetallic center, and oxidizes them stepwise to carboxyl groups through a free radical chain reaction to generate trimellitic acid, which is then dehydrated and ring-closed to obtain trimellitic anhydride. Next, a core-shell structure of iron oxide is prepared, and thiol groups are introduced through silanization grafting, followed by oxidative sulfonation to form the second catalyst. In the esterification stage, the sulfonic acid group provides a high-density proton acid site, which first activates the anhydride bond of trimellitic anhydride at low temperature, and then catalyzes the deep esterification reaction of tridecanool and carboxyl groups under negative pressure. Ionic liquid is used as the reaction medium, and its polarity adjustable and high boiling point characteristics promote homogeneous reaction and simplify separation. Finally, the catalyst, excess alcohol, and ionic liquid are recovered in stages by means of magnetic separation, molecular distillation, and liquid-liquid separation, forming a complete green catalytic cycle.

[0026] Furthermore, at the process level, this invention achieves high conversion rates under lower temperature and pressure conditions than traditional processes through the synergy of ionic liquid media and gradient negative pressure esterification technology, effectively avoiding the risk of side reactions of long-chain alcohols at high temperatures. Simultaneously, it constructs a closed-loop system for the graded recovery of catalyst, excess alcohol, and ionic liquid, significantly improving atom economy and process sustainability. The catalytic system employs a dual-function design: the first catalyst achieves precise oxidation of aromatic methyl groups with high activity and selectivity, while the second catalyst, with its strong acidic sites and magnetic response characteristics, ensures esterification efficiency while enabling convenient separation and recycling. This overcomes the technical bottlenecks of difficult separation and high residue levels associated with traditional homogeneous catalysts. Molecular distillation technology is introduced in the separation and purification stage, completing the separation of light and heavy components with extremely short heating times and low-temperature conditions, maximizing the preservation of the product's thermal stability and color advantages. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is an overall flow chart of a method for preparing tridecyl alcohol trimellitate according to the present invention; Figure 2 This is a flowchart illustrating the preparation of the first catalyst in a method for preparing tridecyl alcohol trimellitate according to the present invention; Figure 3 Mind map of a method for preparing tridecyl alcohol trimellitate according to the present invention; Figure 4 This is a scanning electron microscope image of the first catalyst in this invention; Figure 5 This is a graph showing the ICP-OES metal content of the first catalyst in this invention. Figure 6 This is a scanning electron microscope image of the second catalyst in this invention. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] In this embodiment, the molecular sieve is model SBA-15, which is a white powder with a pore size of 6-11 nm and a specific surface area of ​​600-800 m² / g. It was purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd. The modified carbocyclic compound is a low-chroma trimellitic anhydride with an anhydride content ≥99.0%, a phthalic anhydride content ≤0.20%, and a color APHA ≤50. Meanwhile, the cobalt acetate is cobalt acetate tetrahydrate, and the manganese acetate is manganese acetate tetrahydrate. The cobalt content in the first catalyst is 3.0–6.0 wt%, the manganese content is 0.8–2.5 wt%, and the BET specific surface area is 300–600 m². 2 / g, with a pore size of 5-10nm, and tetrabromoethane specifically 1,1,2,2-tetrabromoethane.

[0031] Example 1 like Figure 1 and Figure 3 As shown, a method for preparing tridecyl trimellitate, the method comprising: A basic catalytic component was prepared by combining cobalt acetate and manganese acetate. This basic catalytic component was then pretreated to obtain the first catalyst, such as... Figure 2 As shown; Acetic acid and pseudotrimethylbenzene were mixed to obtain an acetic acid solution containing pseudotrimethylbenzene. A first catalyst was added to the acetic acid solution containing pseudotrimethylbenzene to carry out the reaction. After the reaction was completed, the mixture was separated and dehydrated to obtain the modified carbocyclic compound. Nano-sized iron oxide was prepared, coated, and grafted to obtain a mercapto-modified material. The mercapto-modified material was sulfonated to obtain a second catalyst. The modified carbocyclic compound and tridecyl alcohol were mixed and the second catalyst was added to obtain an esterification reaction mixture. The second catalyst was recovered from the esterification reaction mixture and excess tridecaneol was separated to obtain a substrate mixture. Crude tridecaneol trimellitate was separated from the substrate mixture and purified to obtain tridecaneol trimellitate.

[0032] Furthermore, the specific steps for preparing the basic catalytic component by combining cobalt acetate and manganese acetate are as follows: N,N-dimethylformamide and acetonitrile were mixed and stirred at a mass ratio of 3.5:1 to obtain a basic mixed solvent. Cobalt acetate (8% by mass of acetonitrile) and manganese acetate (2% by mass) were added to the basic mixed solvent and stirred at 23°C for 25 min. After stirring, an organic ligand in the same proportion as cobalt acetate was added and stirring was continued to obtain an organic composite solution. The organic ligand was obtained by mixing 2-aminoterephthalic acid and 2-methylimidazole in equal proportions.

[0033] The organic composite solution was sealed and heated to 85°C, and reacted at a constant temperature for 20 hours. After the reaction was completed, it was cooled to 23°C and filtered. The initial filter cake was collected and washed with anhydrous ethanol and N,N-dimethylformamide. After washing, it was dried under vacuum at 65°C for 10 hours to obtain the basic catalytic component.

[0034] Furthermore, the pretreatment of the basic catalytic components specifically involves: The basic catalytic component was mixed with anhydrous ethanol at a mass ratio of 1:28 and ultrasonically dispersed for 25 min to form a catalytic suspension. Molecular sieves of equal mass to the basic catalytic component were added to the catalytic suspension and stirred at 23°C for 20 h. After stirring, the mixture was filtered, and the filtered product was collected. The filtered product was washed twice with anhydrous methanol and vacuum dried at 65°C for 10 h to obtain the first catalyst.

[0035] Furthermore, the acetic acid solution containing pseudotrimethylbenzene is obtained by mixing pseudotrimethylbenzene and acetic acid at a mass ratio of 1:4.5.

[0036] Furthermore, the specific steps of adding the first catalyst to the acetic acid solution containing pseudotrimethylbenzene to carry out the reaction are as follows: Add 0.8% by mass of a first catalyst and 0.2% by mass of tetrabromoethane to an acetic acid solution containing pseudotrimethylbenzene. Purge with nitrogen to displace oxygen and stir. Heat to 185°C, maintain pressure at 1.5 MPa, and then purge with air for 4 hours to obtain an oxidation reaction solution.

[0037] Furthermore, the separation and dehydration process after the reaction is completed includes: The oxidation reaction solution was cooled to 75°C and the pressure was reduced to atmospheric pressure. The cooled reaction solution was then cooled to 20°C at a rate of 10°C / h to form crystals, which were then filtered out. Deionized water was added to the crystals for washing. This process was repeated once to obtain crude trimellitic acid. Crude trimellitic acid was dehydrated at 190℃ and 2kPa for 1.5h to form crude trimellitic anhydride. The crude trimellitic anhydride was then purified to obtain an improved carbocyclic compound.

[0038] Furthermore, the coating of nano-ferric oxide includes: Nano-Fe3O4 and anhydrous ethanol were mixed at a mass ratio of 1:4.5 and ultrasonically dispersed for 25 min to obtain a nano-Fe3O4 solution. Tetraethyl orthosilicate (35% by mass of anhydrous ethanol) and ammonia (8% by mass of 25%) were added to the nano-Fe3O4 solution and stirred at 23°C for 5 h. After stirring, the magnetic material was separated by a magnet, washed twice with anhydrous ethanol, and dried at 75°C for 1.5 hours to obtain coated iron(III) oxide.

[0039] It should be noted that the specific steps for preparing nano-ferric oxide are as follows: Deionized water, ferric chloride hexahydrate, and ferrous sulfate heptahydrate were mixed in a mass ratio of 50:2:1, heated to 80°C, and 25% ammonia water was added. The mixture was stirred and reacted for 1 hour. After the reaction was completed, the black solid was separated by a magnet, washed with deionized water until neutral, and dried under vacuum at 60°C for 12 hours to obtain nano-iron tetroxide.

[0040] Furthermore, after the coating is completed, grafting is performed, and the specific operation is as follows: The coated iron oxide was dispersed in anhydrous toluene at a mass ratio of 1:7, and 3-mercaptopropyltrimethoxysilane was added in an equal proportion to the coated iron oxide. The mixture was refluxed under nitrogen at 75°C for 10 h. After the reaction was completed, the grafted product was separated by a magnet. The grafted product was washed once with toluene and once with anhydrous ethanol. It was then dried in a vacuum at 55°C for 3.5 h to obtain the mercapto-modified material.

[0041] Furthermore, the sulfonation of the mercapto-modified material includes: The mercaptomodified material, 30% hydrogen peroxide, and formic acid were mixed at a mass ratio of 1:1.5:2 and stirred at 45°C for 5.5 h. After stirring, the sulfonated product was separated by a magnet, washed with deionized water to 6.8, washed twice with anhydrous ethanol, and dried in a vacuum at 55°C for 5.5 h to obtain the second catalyst.

[0042] Furthermore, the process of mixing the modified carbocyclic compound and tridecyl alcohol and adding a second catalyst includes: The modified carbocyclic compound, tridecaneol, 1-butyl-3-methylimidazolium hexafluorophosphate and the second catalyst were mixed in a mass ratio of 12:38:3:1 and the mixture was heated to 120°C and stirred for 1 hour. Then the pressure was reduced to -0.08 MPa, and the temperature was increased to 160 °C. The reaction was carried out for 4 hours to obtain the esterification reaction mixture.

[0043] The second catalyst was recovered from the esterification reaction mixture, and excess tridecyl alcohol was separated to obtain a substrate mixture, specifically: Using a strong magnetic separator, the second catalyst is adsorbed onto the surface of the separator and then removed. Alternatively, a magnetic rod can be directly inserted into the esterification reaction mixture and stirred for adsorption, then removed and the adsorbed second catalyst is collected. It is then washed three times with anhydrous ethanol and dried under vacuum at 60°C for 4 hours.

[0044] The separation of crude tridecane alcohol trimellitate from a substrate mixture includes: placing the substrate mixture into a short-path molecular distillation apparatus (scraped film type), preheating it to 150°C, turning on the vacuum system to reduce the absolute pressure to 0.5 Pa, setting the heating wall temperature to 165°C and the internal condenser temperature to 60°C, turning on the scraper, and feeding the preheated substrate mixture into the molecular distillation apparatus to collect the light and heavy components. The light component is mainly excess tridecane alcohol, which rapidly condenses on the condenser surface and flows down the wall. The heavy component is mainly a base material containing crude tridecane alcohol trimellitate and 1-butyl-3-methylimidazolium hexafluorophosphate. The base material is transferred to a layering tank and allowed to stand for 2 hours to form upper and lower layers. The upper layer is crude tridecane alcohol trimellitate, and the lower layer is 1-butyl-3-methylimidazolium hexafluorophosphate.

[0045] The crude tridecyltriphenyl ester is purified, specifically as follows: The crude tridecyl alcohol trimellitate was washed with deionized water. After washing, anhydrous sodium sulfate was added, and the mixture was stirred and dried for 25 minutes and then filtered. After filtration, the mixture was dried under vacuum at 80°C and –0.095 MPa for 1 hour to obtain tridecyl alcohol trimellitate.

[0046] Example 2 The preparation method of tridecyl trimellitate provided in this embodiment is basically the same as that in Example 1. The main difference between the two lies in the specific composition and ratio of the raw materials used. The preparation method of tridecyl trimellitate in this embodiment includes: A basic catalytic component was prepared by combining cobalt acetate and manganese acetate. The basic catalytic component was then pretreated to obtain the first catalyst. Acetic acid and pseudotrimethylbenzene were mixed to obtain an acetic acid solution containing pseudotrimethylbenzene. A first catalyst was added to the acetic acid solution containing pseudotrimethylbenzene to carry out the reaction. After the reaction was completed, the mixture was separated and dehydrated to obtain the modified carbocyclic compound. Nano-sized iron oxide was prepared, coated, and grafted to obtain a mercapto-modified material. The mercapto-modified material was sulfonated to obtain a second catalyst. The modified carbocyclic compound and tridecyl alcohol were mixed and the second catalyst was added to obtain an esterification reaction mixture. The second catalyst was recovered from the esterification reaction mixture and excess tridecaneol was separated to obtain a substrate mixture. Crude tridecaneol trimellitate was separated from the substrate mixture and purified to obtain tridecaneol trimellitate.

[0047] Furthermore, the specific steps for preparing the basic catalytic component by combining cobalt acetate and manganese acetate are as follows: N,N-dimethylformamide and acetonitrile were mixed and stirred at a mass ratio of 4.5:1 to obtain a basic mixed solvent. Cobalt acetate (12% by mass of acetonitrile) and manganese acetate (4% by mass) were added to the basic mixed solvent and stirred at 27°C for 35 min. After stirring, an organic ligand in the same proportion as cobalt acetate was added and stirring was continued to obtain an organic composite solution. The organic ligand was obtained by mixing 2-aminoterephthalic acid and 2-methylimidazole in equal proportions.

[0048] The organic composite solution was sealed and heated to 95°C, and reacted at a constant temperature for 26 hours. After the reaction was completed, it was cooled to 27°C and filtered. The initial filter cake was collected and washed with anhydrous ethanol and N,N-dimethylformamide. After washing, it was dried under vacuum at 75°C for 14 hours to obtain the basic catalytic component.

[0049] Furthermore, the pretreatment of the basic catalytic components specifically involves: The basic catalytic component was mixed with anhydrous ethanol at a mass ratio of 1:32 and ultrasonically dispersed for 35 min to form a catalytic suspension. Molecular sieves of equal mass to the basic catalytic component were added to the catalytic suspension and stirred at 27°C for 25 h. After stirring, the mixture was filtered, and the filtered product was collected. The filtered product was washed four times with anhydrous methanol and vacuum dried at 75°C for 14 h to obtain the first catalyst.

[0050] Furthermore, the acetic acid solution containing pseudotrimethylbenzene is obtained by mixing pseudotrimethylbenzene and acetic acid at a mass ratio of 1:5.5.

[0051] Furthermore, the specific steps of adding the first catalyst to the acetic acid solution containing pseudotrimethylbenzene to carry out the reaction are as follows: A first catalyst of 1% by mass of pseudotrimethylbenzene and 0.3% tetrabromoethane were added to an acetic acid solution containing pseudotrimethylbenzene. Nitrogen gas was introduced to displace oxygen and the mixture was stirred. The temperature was raised to 195°C, the pressure was maintained at 1.7 MPa, and air was introduced to react for 5 hours to obtain an oxidation reaction solution.

[0052] Furthermore, the separation and dehydration process after the reaction is completed includes: The oxidation reaction solution was cooled to 85°C and the pressure was reduced to atmospheric pressure. The cooled reaction solution was then cooled to 30°C at a rate of 10°C / h to form crystals, which were then filtered out. Deionized water was added to the crystals for washing. This process was repeated three times to obtain crude trimellitic acid. Crude trimellitic acid was dehydrated at 200℃ and 5kPa for 2.5h to form crude trimellitic anhydride. The crude trimellitic anhydride was then purified to obtain an improved carbocyclic compound.

[0053] Furthermore, the coating of nano-ferric oxide includes: Nano-Fe3O4 and anhydrous ethanol were mixed at a mass ratio of 1:5.5 and ultrasonically dispersed for 35 min to obtain a nano-Fe3O4 solution. Tetraethyl orthosilicate (45% by mass of anhydrous ethanol) and ammonia (12% by mass of 25%) were added to the nano-Fe3O4 solution and stirred at 27°C for 7 h. After stirring, the magnetic material was separated by a magnet, washed four times with anhydrous ethanol, and dried at 85°C for 2.5 hours to obtain coated iron(III) oxide.

[0054] It should be noted that the specific steps for preparing nano-ferric oxide are as follows: Deionized water, ferric chloride hexahydrate, and ferrous sulfate heptahydrate were mixed in a mass ratio of 50:2:1, heated to 80°C, and 25% ammonia water was added. The mixture was stirred and reacted for 1 hour. After the reaction was completed, the black solid was separated by a magnet, washed with deionized water until neutral, and dried under vacuum at 60°C for 12 hours to obtain nano-iron tetroxide.

[0055] Furthermore, after the coating is completed, grafting is performed, and the specific operation is as follows: The coated iron oxide was dispersed in anhydrous toluene at a mass ratio of 1:9, and 3-mercaptopropyltrimethoxysilane was added in an equal proportion to the coated iron oxide. The mixture was refluxed under nitrogen at 85°C for 14 h. After the reaction was completed, the grafted product was separated by a magnet. The grafted product was washed three times with toluene and anhydrous ethanol, and dried in a vacuum at 65°C for 4.5 h to obtain the mercapto-modified material.

[0056] Furthermore, the sulfonation of the mercapto-modified material includes: The mercaptomodified material, 30% hydrogen peroxide, and formic acid were mixed in a mass ratio of 1:2:3 and stirred at 55°C for 6.5 h. After stirring, the sulfonated product was separated by a magnet, washed with deionized water to 7.2, washed four times with anhydrous ethanol, and dried in a vacuum at 65°C for 6.5 h to obtain the second catalyst.

[0057] Furthermore, the process of mixing the modified carbocyclic compound and tridecyl alcohol and adding a second catalyst includes: The modified carbocyclic compound, tridecaneol, 1-butyl-3-methylimidazolium hexafluorophosphate and the second catalyst were mixed in a mass ratio of 15:55:5:1 and the mixture was heated to 130°C and stirred for 2 hours. Then the pressure was reduced to -0.09 MPa, and the temperature was increased to 170 °C. The reaction was carried out for 5 hours to obtain the esterification reaction mixture.

[0058] The second catalyst was recovered from the esterification reaction mixture, and excess tridecyl alcohol was separated to obtain a substrate mixture, specifically: Using a strong magnetic separator, the second catalyst is adsorbed onto the surface of the separator and then removed. Alternatively, a magnetic rod can be directly inserted into the esterification reaction mixture and stirred for adsorption, then removed and the adsorbed second catalyst is collected. It is then washed three times with anhydrous ethanol and dried under vacuum at 60°C for 4 hours.

[0059] The separation of crude tridecane alcohol trimellitate from a substrate mixture includes: placing the substrate mixture into a short-path molecular distillation apparatus (scraped film type), preheating it to 150°C, turning on the vacuum system to reduce the absolute pressure to 0.5 Pa, setting the heating wall temperature to 165°C and the internal condenser temperature to 60°C, turning on the scraper, and feeding the preheated substrate mixture into the molecular distillation apparatus to collect the light and heavy components. The light component is mainly excess tridecane alcohol, which rapidly condenses on the condenser surface and flows down the wall. The heavy component is mainly a base material containing crude tridecane alcohol trimellitate and 1-butyl-3-methylimidazolium hexafluorophosphate. The base material is transferred to a layering tank and allowed to stand for 2 hours to form upper and lower layers. The upper layer is crude tridecane alcohol trimellitate, and the lower layer is 1-butyl-3-methylimidazolium hexafluorophosphate.

[0060] The crude tridecyltriphenyl ester is purified, specifically as follows: The crude tridecyl alcohol trimellitate was washed with deionized water. After washing, anhydrous sodium sulfate was added, and the mixture was stirred and dried for 35 minutes and then filtered. After filtration, the mixture was dried under vacuum at 80°C and –0.095 MPa for 1 hour to obtain tridecyl alcohol trimellitate.

[0061] Example 3 The preparation method of tridecyl trimellitate provided in this embodiment is basically the same as that in Example 1. The main difference between the two lies in the specific composition and ratio of the raw materials used. The preparation method of tridecyl trimellitate in this embodiment includes: A basic catalytic component was prepared by combining cobalt acetate and manganese acetate. The basic catalytic component was then pretreated to obtain the first catalyst. Acetic acid and pseudotrimethylbenzene were mixed to obtain an acetic acid solution containing pseudotrimethylbenzene. A first catalyst was added to the acetic acid solution containing pseudotrimethylbenzene to carry out the reaction. After the reaction was completed, the mixture was separated and dehydrated to obtain the modified carbocyclic compound. Nano-sized iron oxide was prepared, coated, and grafted to obtain a mercapto-modified material. The mercapto-modified material was sulfonated to obtain a second catalyst. The modified carbocyclic compound and tridecyl alcohol were mixed and the second catalyst was added to obtain an esterification reaction mixture. The second catalyst was recovered from the esterification reaction mixture and excess tridecaneol was separated to obtain a substrate mixture. Crude tridecaneol trimellitate was separated from the substrate mixture and purified to obtain tridecaneol trimellitate.

[0062] Furthermore, the specific steps for preparing the basic catalytic component by combining cobalt acetate and manganese acetate are as follows: N,N-dimethylformamide and acetonitrile were mixed and stirred at a mass ratio of 4:1 to obtain a basic mixed solvent. Cobalt acetate (10% by mass of acetonitrile) and manganese acetate (3% by mass) were added to the basic mixed solvent and stirred at 25°C for 30 min. After stirring, an organic ligand in the same proportion as cobalt acetate was added and stirring was continued to obtain an organic composite solution. The organic ligand was obtained by mixing 2-aminoterephthalic acid and 2-methylimidazole in equal proportions.

[0063] The organic composite solution was sealed and heated to 90°C, and reacted at a constant temperature for 24 hours. After the reaction was completed, it was cooled to 25°C and filtered. The initial filter cake was collected and washed with anhydrous ethanol and N,N-dimethylformamide. After washing, it was dried under vacuum at 70°C for 12 hours to obtain the basic catalytic component.

[0064] Furthermore, the pretreatment of the basic catalytic components specifically involves: The basic catalytic component was mixed with anhydrous ethanol at a mass ratio of 1:30 and ultrasonically dispersed for 30 min to form a catalytic suspension. Molecular sieves of equal mass to the basic catalytic component were added to the catalytic suspension and stirred at 25°C for 24 h. After stirring, the mixture was filtered, and the filtered product was collected. The filtered product was washed three times with anhydrous methanol and vacuum dried at 70°C for 12 h to obtain the first catalyst.

[0065] Furthermore, the acetic acid solution containing pseudotrimethylbenzene is obtained by mixing pseudotrimethylbenzene and acetic acid at a mass ratio of 1:4.

[0066] Furthermore, the specific steps of adding the first catalyst to the acetic acid solution containing pseudotrimethylbenzene to carry out the reaction are as follows: Add 0.9% of a first catalyst and 0.25% of tetrabromoethane to an acetic acid solution containing pseudotrimethylbenzene. Purge with nitrogen to displace oxygen and stir. Heat to 190°C, maintain pressure at 1.6 MPa, and then purge with air for 4.5 h to obtain an oxidation reaction solution.

[0067] Furthermore, the separation and dehydration process after the reaction is completed includes: The oxidation reaction solution was cooled to 80°C and the pressure was reduced to atmospheric pressure. The cooled reaction solution was then cooled to 25°C at a rate of 10°C / h to form crystals, which were then filtered out. Deionized water was added to the crystals for washing. This process was repeated twice to obtain crude trimellitic acid. Crude trimellitic acid was dehydrated for 2 hours at 195°C and 3 kPa to form crude trimellitic anhydride. The crude trimellitic anhydride was then purified to obtain an improved carbocyclic compound.

[0068] Furthermore, the coating of nano-ferric oxide includes: Nano-iron oxide and anhydrous ethanol were mixed at a mass ratio of 1:5 and ultrasonically dispersed for 30 min to obtain a nano-iron oxide solution. Tetraethyl orthosilicate with a mass of 40% anhydrous ethanol and 10% ammonia solution with a concentration of 25% were added to the nano-iron oxide solution and stirred at 25°C for 6 h. After stirring, the magnetic material was separated by a magnet, washed three times with anhydrous ethanol, and dried at 80°C for 2 hours to obtain coated iron(III) oxide.

[0069] It should be noted that the specific steps for preparing nano-ferric oxide are as follows: Deionized water, ferric chloride hexahydrate, and ferrous sulfate heptahydrate were mixed in a mass ratio of 50:2:1, heated to 80°C, and 25% ammonia water was added. The mixture was stirred and reacted for 1 hour. After the reaction was completed, the black solid was separated by a magnet, washed with deionized water until neutral, and dried under vacuum at 60°C for 12 hours to obtain nano-iron tetroxide.

[0070] Furthermore, after the coating is completed, grafting is performed, and the specific operation is as follows: The coated iron oxide was dispersed in anhydrous toluene at a mass ratio of 1:8, and 3-mercaptopropyltrimethoxysilane was added in an equal proportion to the coated iron oxide. The mixture was refluxed under nitrogen at 80°C for 12 hours. After the reaction was completed, the grafted product was separated by a magnet. The grafted product was washed twice with toluene and anhydrous ethanol, and dried in a vacuum at 60°C for 4 hours to obtain the mercapto-modified material.

[0071] Furthermore, the sulfonation of the mercapto-modified material includes: The mercaptomodified material, 30% hydrogen peroxide, and formic acid were mixed at a mass ratio of 1:1.8:2.5 and stirred at 50°C for 6 hours. After stirring, the sulfonated product was separated by a magnet, washed with deionized water to 7.0, washed three times with anhydrous ethanol, and dried in a vacuum at 60°C for 6 hours to obtain the second catalyst.

[0072] Furthermore, the process of mixing the modified carbocyclic compound and tridecyl alcohol and adding a second catalyst includes: The modified carbocyclic compound, tridecanool, 1-butyl-3-methylimidazolium hexafluorophosphate and the second catalyst were mixed in a mass ratio of 13:45:4:1 and the mixture was heated to 125°C and stirred for 1.5 h. Then the pressure was reduced to -0.085 MPa, and the temperature was increased to 165 °C. The reaction was carried out for 4.5 h to obtain the esterification reaction mixture.

[0073] The second catalyst was recovered from the esterification reaction mixture, and excess tridecyl alcohol was separated to obtain a substrate mixture, specifically: Using a strong magnetic separator, the second catalyst is adsorbed onto the surface of the separator and then removed. Alternatively, a magnetic rod can be directly inserted into the esterification reaction mixture and stirred for adsorption, then removed and the adsorbed second catalyst is collected. It is then washed three times with anhydrous ethanol and dried under vacuum at 60°C for 4 hours.

[0074] The separation of crude tridecane alcohol trimellitate from a substrate mixture includes: placing the substrate mixture into a short-path molecular distillation apparatus (scraped film type), preheating it to 150°C, turning on the vacuum system to reduce the absolute pressure to 0.5 Pa, setting the heating wall temperature to 165°C and the internal condenser temperature to 60°C, turning on the scraper, and feeding the preheated substrate mixture into the molecular distillation apparatus to collect the light and heavy components. The light component is mainly excess tridecane alcohol, which rapidly condenses on the condenser surface and flows down the wall. The heavy component is mainly a base material containing crude tridecane alcohol trimellitate and 1-butyl-3-methylimidazolium hexafluorophosphate. The base material is transferred to a layering tank and allowed to stand for 2 hours to form upper and lower layers. The upper layer is crude tridecane alcohol trimellitate, and the lower layer is 1-butyl-3-methylimidazolium hexafluorophosphate.

[0075] The crude tridecyltriphenyl ester is purified, specifically as follows: The crude tridecyl alcohol trimellitate was washed with deionized water. After washing, anhydrous sodium sulfate was added, and the mixture was stirred and dried for 30 minutes and then filtered. After filtration, the mixture was dried under vacuum at 80°C and –0.095 MPa for 1 hour to obtain tridecyl alcohol trimellitate.

[0076] Comparative Example 1: The preparation method and specific ratio of raw materials of the tridecyl alcohol trimellitate provided in this example are roughly the same as those in Example 1. The main difference is that in this example, an equal amount of trimellitic anhydride is used instead of the modified carbocyclic compound. The trimellitic anhydride was purchased from Jiangsu Yuntong New Material Technology Co., Ltd.

[0077] Comparative Example 2: The preparation method and specific ratio of raw materials of the tridecyl alcohol trimellitate provided in this example are roughly the same as those in Example 1. The main difference is that a first catalyst with a mass of 0.2% trimellitene is added in this example.

[0078] Comparative Example 3: The preparation method and specific ratio of raw materials of the tridecyl alcohol trimellitate provided in this example are roughly the same as those in Example 1. The main difference is that an equal amount of stannous oxide is used to replace the second catalyst in this example.

[0079] Comparative Example 4: The preparation method and specific ratio of raw materials of the tridecyl alcohol trimellitate provided in this example are roughly the same as those in Example 1. The main difference is that this example does not contain 1-butyl-3-methylimidazolium hexafluorophosphate.

[0080] Effect test The tridecyl alcohol trimellitates prepared by Examples 1 to 3 of the present invention are referred to as Experimental Examples 1 to 3; the tridecyl alcohol trimellitates prepared by Comparative Examples 1 to 4 are referred to as Comparative Examples 1 to 4; and then the performance of each group of tridecyl alcohol trimellitates in equal amounts was tested.

[0081] Experimental setup: This control experiment used three examples and four comparative examples as research subjects to test the environmental protection effect, product purity and impurity content, and thermal stability of each scheme. Each test item was performed in triplicate, and the average value was taken. Specific test results and analysis are as follows. Environmental testing: Test method: Detection of heavy metal ions (Co) in the reaction waste liquid. 2+ Mn 2+ Sn 2+ The environmental protection effect was evaluated according to GB 8978-1996 "Integrated Wastewater Discharge Standard" for the content of heavy metal ions and the COD value of organic wastewater. The standard was compliant with heavy metal ion content ≤0.5 mg / L and COD ≤500 mg / L. The experimental results are detailed in Table 1. Table 1: Environmental Testing Table Examples 1 - 3 have high catalyst recovery efficiency, extremely low heavy metal ion content in the waste liquid, qualified COD value, and no harmful by-products; in Comparative Example 3, stannous oxide recovery is difficult, Sn²⁺ in the waste liquid exceeds the standard, and the COD value is on the high side; in Comparative Examples 2 and 4, although the heavy metal content is qualified, in Comparative Example 4, there is no ionic liquid-assisted reaction, the reaction is incomplete, and the COD is slightly high.

[0082] Product purity and impurity content testing: Testing method: The purity of tridecyl trimellitate was determined by high performance liquid chromatography (HPLC), and a purity of ≥ 99.0% was considered qualified; the content of impurities (trimellitic anhydride, tridecyl alcohol, by-product ester) was determined by gas chromatography, and the data results are shown in Table 2: Table 2: Product purity and impurity content table Examples 1 - 3 use improved carbocyclic compounds, special catalysts and ionic liquids, with sufficient reaction, relatively high product purity and extremely low impurity content; in Comparative Example 1, ordinary trimellitic anhydride was used, and the purity was slightly lower; in Comparative Example 2, the content of the first catalyst was low, the oxidation reaction was incomplete, and the impurity content was on the high side; in Comparative Example 3, the catalyst activity was insufficient and there were many side reactions; in Comparative Example 4, there was no ionic liquid, the reaction efficiency was low, and the impurities were high.

[0083] Thermal stability testing: Testing method: Thermogravimetric analysis was used. Under a nitrogen atmosphere, with a heating rate of 10 °C / min, the mass retention rate of the test sample at 200 °C, 250 °C, and 300 °C was tested. The higher the mass retention rate, the better the thermal stability. According to the industry standard, a mass retention rate of ≥ 98.0% at 250 °C was considered qualified. See Table 3 for details: Table 3: Thermal stability table The products of Examples 1 - 3 have high purity, few impurities, and excellent thermal stability, and the mass retention rate at 250 °C is all above 98.5%; due to the relatively high impurity content in each comparative example, the thermal stability has decreased. Among them, Comparative Example 3 has the most impurities and the worst thermal stability, and there is an obvious mass loss at 300 °C.

[0084] Please refer to Figure 4The results showed that the first catalyst was irregularly aggregated into particles with a rough surface and a certain porous structure, consistent with the morphology of the powder catalyst formed after the SBA-15 molecular sieve supported the bimetallic organic framework catalytic components. C and N elements were distributed in the particle region, indicating that the organic ligand components were retained in the catalyst framework. O and Si elements showed strong signals and their distribution range was basically consistent with the particle outline, indicating that the SBA-15 molecular sieve participated in the formation of the composite structure as a support. Co and Mn elements did not show obvious local large-area enrichment, but were relatively uniformly distributed with the particle region, indicating that the cobalt and manganese bimetallic active components were well supported in the first catalyst.

[0085] and Figure 5 This is used to quantitatively illustrate the actual loading levels of cobalt and manganese metal active components in the first catalyst. The figure shows a Co content of 1.42 ± 0.04 wt% and a Mn content of 0.36 ± 0.02 wt%. The Co content is significantly higher than the Mn content, and the Co / Mn mass ratio is approximately 3.94:1, which is basically consistent with the approximately 4:1 feeding ratio of cobalt acetate and manganese acetate precursors in Example 1. This indicates that the bimetallic components were effectively introduced into the first catalyst during the preparation process without significant imbalance. The small error range indicates good test repeatability. This metal content level is also suitable for use as a supported catalyst, providing Co / Mn bimetallic synergistic active centers without causing significant agglomeration or precipitation of metal salt phases due to excessive metal loading.

[0086] like Figure 6 As shown in the figure, the particles exhibit a near-spherical or agglomerated morphology, consistent with the basic morphology of magnetic composite particles formed after nano-Fe3O4 is coated, grafted, and sulfonated. In the elemental distribution of the energy-dispersive X-ray spectroscopy, the Fe signal corresponds to the magnetic core of the nano-Fe3O4, the O signal originates from the Fe3O4 and SiO2 coating layers and the oxygen-containing structures in the sulfonic acid groups, the Si signal corresponds to the siloxane coating layer formed by the hydrolysis of tetraethyl orthosilicate and the 3-mercaptopropyltrimethoxysilane graft structure, and the S signal corresponds to the sulfuric acid-containing groups introduced after the sulfonation of the mercapto-modified material.

[0087] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0088] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing tridecyl trimellitate, characterized in that: The method includes: A basic catalytic component was prepared by combining cobalt acetate and manganese acetate. The basic catalytic component was then pretreated to obtain the first catalyst. Acetic acid and pseudotrimethylbenzene were mixed to obtain an acetic acid solution containing pseudotrimethylbenzene. A first catalyst was added to the acetic acid solution containing pseudotrimethylbenzene to carry out the reaction. After the reaction was completed, the mixture was separated and dehydrated to obtain the modified carbocyclic compound. Nano-sized iron oxide was prepared, coated, and grafted to obtain a mercapto-modified material. The mercapto-modified material was sulfonated to obtain a second catalyst. The modified carbocyclic compound and tridecyl alcohol were mixed and the second catalyst was added to obtain an esterification reaction mixture. The second catalyst was recovered from the esterification reaction mixture and excess tridecaneol was separated to obtain a substrate mixture. Crude tridecaneol trimellitate was separated from the substrate mixture and purified to obtain tridecaneol trimellitate.

2. The method for preparing tridecyl trimellitate according to claim 1, characterized in that: The specific steps for preparing the basic catalytic component by combining cobalt acetate and manganese acetate are as follows: N,N-dimethylformamide and acetonitrile were mixed and stirred at a mass ratio of 3.5 to 4.5:1 to obtain a basic mixed solvent. Cobalt acetate (8% to 12% by mass of acetonitrile) and manganese acetate (2% to 4% by mass) were added to the basic mixed solvent and stirred at 23 to 27°C for 25 to 35 minutes. After stirring, an organic ligand in the same proportion as cobalt acetate was added and stirring was continued to obtain an organic composite solution. The organic composite solution was sealed and heated to 85–95°C, and reacted at a constant temperature for 20–26 h. After the reaction was completed, it was cooled to 23–27°C and filtered. The initial filter cake was collected and washed with anhydrous ethanol and N,N-dimethylformamide. After washing, it was vacuum dried at 65–75°C for 10–14 h to obtain the basic catalytic component.

3. The method for preparing tridecyl trimellitate according to claim 2, characterized in that: The pretreatment of the basic catalytic components specifically involves: The basic catalytic component is mixed with anhydrous ethanol at a mass ratio of 1:28-32 and ultrasonically dispersed for 25-35 min to form a catalytic suspension. Molecular sieves of equal mass to the basic catalytic component are added to the catalytic suspension and stirred at 23-27℃ for 20-25 h. After stirring, the mixture is filtered, and the filtered product is collected. The filtered product is washed 2-4 times with anhydrous methanol and vacuum dried at 65-75℃ for 10-14 h to obtain the first catalyst.

4. The method for preparing tridecyl trimellitate according to claim 1, characterized in that: The acetic acid solution containing pseudotrimethylbenzene was obtained by mixing pseudotrimethylbenzene and acetic acid at a mass ratio of 1:4.5 to 5.

5.

5. The method for preparing tridecyl trimellitate according to claim 4, characterized in that: The specific steps of adding the first catalyst to the acetic acid solution containing pseudotrimethylbenzene for the reaction are as follows: Add 0.8%–1% of a first catalyst and 0.2%–0.3% of tetrabromoethane to an acetic acid solution containing pseudotrimethylbenzene. Purge nitrogen gas to displace oxygen and stir. Heat to 185–195°C and maintain pressure at 1.5–1.7 MPa. Then purge with air and react for 4–5 hours to obtain an oxidation reaction solution.

6. The method for preparing tridecyl trimellitate according to claim 5, characterized in that: The separation and dehydration process after the reaction includes: The oxidation reaction solution was cooled to 75-85℃ and the pressure was reduced to atmospheric pressure. The cooled reaction solution was then cooled to 20-30℃ at a rate of 10℃ / h to form crystals, which were then filtered out. Deionized water was added to the crystals for washing. This process was repeated 1-3 times to obtain crude trimellitic acid. Crude trimellitic acid was dehydrated in an environment with a temperature of 190–200℃ and a pressure of 2–5 kPa for 1.5–2.5 h to form crude trimellitic anhydride. The crude trimellitic anhydride was then purified to obtain an improved carbocyclic compound.

7. The method for preparing tridecyl trimellitate according to claim 1, characterized in that: The coating of nano-ferric oxide includes: Nano-iron oxide and anhydrous ethanol are mixed at a mass ratio of 1:4.5-5.5 and ultrasonically dispersed for 25-35 min to obtain a nano-iron oxide solution. Tetraethyl orthosilicate (35%-45% by mass of anhydrous ethanol) and ammonia (8%-12% by mass of 25%) are added to the nano-iron oxide solution and stirred at 23-27℃ for 5-7 h. After stirring, the magnetic material is separated by a magnet, washed with anhydrous ethanol 2-4 times, and dried at 75-85℃ for 1.5-2.5 hours to obtain coated iron(III) oxide.

8. The method for preparing tridecyl trimellitate according to claim 1, characterized in that: After the coating process is completed, grafting is performed, and the specific steps are as follows: Coated iron oxide was dispersed in anhydrous toluene at a mass ratio of 1:7-9, and 3-mercaptopropyltrimethoxysilane was added in an equal proportion to the coated iron oxide. The mixture was refluxed under nitrogen at 75-85°C for 10-14 hours. After the reaction was completed, the grafted product was separated by a magnet. The grafted product was washed 1-3 times with toluene and anhydrous ethanol, and dried in a vacuum at 55-65°C for 3.5-4.5 hours to obtain the mercapto-modified material.

9. The method for preparing tridecyl trimellitate according to claim 8, characterized in that: The sulfonation of the mercapto-modified material includes: The mercaptomodified material, 30% hydrogen peroxide, and formic acid were mixed in a mass ratio of 1:1.5 to 2:2 to 3 and stirred at 45 to 55°C for 5.5 to 6.5 hours. After stirring, the sulfonated product was separated by a magnet, washed with deionized water to a pH of 6.8 to 7.2, and then washed 2 to 4 times with anhydrous ethanol. The product was then dried in a vacuum at 55 to 65°C for 5.5 to 6.5 hours to obtain the second catalyst.

10. The method for preparing tridecyl alcohol trimellitate according to claim 9, characterized in that: The process of mixing the modified carbocyclic compound and tridecyl alcohol and adding a second catalyst includes: The modified carbocyclic compound, tridecaneol, 1-butyl-3-methylimidazolium hexafluorophosphate and the second catalyst were mixed in a mass ratio of 12-15:38-55:3-5:1 and the mixture was heated to 120-130℃ and stirred for 1-2 hours. Then the pressure is reduced to -0.08 to -0.09 MPa, and the temperature is raised to 160 to 170 °C. The reaction is carried out for 4 to 5 hours to obtain the esterification reaction mixture.

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