Modified nanocatalyst for esterification reaction and preparation method and application thereof

Abstract

The present application relates to the technical field of catalyst, in particular to a modified nano catalyst for esterification reaction and its preparation method and application. Concentrated sulfuric acid is used as the catalyst for synthesizing pentaerythritol isostearate by esterification reaction, but it has strong corrosion and poor selectivity. In view of the above problems, the present application provides a modified nano catalyst for esterification reaction, which is sequentially modified by chlorosilane coupling agent and phosphite silane coupling agent on the surface of hydrophilic nano silicon dioxide. The obtained modified nano catalyst has good catalytic effect on esterification reaction, especially for the esterification reaction between pentaerythritol and isostearic acid, which can significantly reduce the reaction temperature and time, greatly improve the selectivity of the reaction, and the obtained pentaerythritol isostearate has lower acid value and better quality.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a modified nanocatalyst for esterification reactions, its preparation method, and its applications. Background Technology

[0002] Pentaerythritol isostearate is a synthetic ester compound that not only performs well as a lubricant but also has wide applications in the cosmetics industry. Due to its excellent oxidative and thermal stability, pentaerythritol isostearate ensures a long shelf life for cosmetics, maintaining their original appearance, color, and texture, and enhancing their overall feel. Furthermore, on the skin's surface, the isomeric acid can form an ester film, keeping the skin smooth and hydrated. However, the synthesis process suffers from problems such as equipment corrosion from traditional catalysts, low catalytic efficiency, and low recovery rates. Additionally, excessively high reaction temperatures and long reaction times lead to high costs and low returns.

[0003] Commonly used catalysts for the synthesis of pentaerythritol isostearate include p-toluenesulfonic acid, concentrated sulfuric acid, and tin oxide. Among these catalysts, p-toluenesulfonic acid, when used as a catalyst, results in an excessively dark product color. Concentrated sulfuric acid possesses both high acidity and catalytic activity. However, the use of concentrated sulfuric acid also has some drawbacks, including:

[0004] (1) Highly corrosive: Concentrated sulfuric acid is highly corrosive. If it comes into contact with the skin or eyes, it can cause burns. Care must be taken when handling it.

[0005] (2) The vapor is toxic: The vapor emitted by concentrated sulfuric acid is toxic and harmful to human health. It needs to be operated in a well-ventilated environment.

[0006] (3) Strong acidity: Concentrated sulfuric acid is a strong acid that easily reacts with many organic compounds, which may lead to side reactions or decomposition.

[0007] (4) Moisture contamination: During operation, concentrated sulfuric acid easily absorbs moisture from the air, leading to dilution and affecting the catalytic effect.

[0008] Tin oxide (SnO2) is also widely used as a catalyst in esterification reactions due to its advantages, such as being environmentally friendly to exhaust emissions and easy to recycle. However, using tin oxide as a catalyst also has some disadvantages, including:

[0009] (1) Higher price: Compared with some traditional acid catalysts (such as concentrated sulfuric acid), tin oxide is relatively expensive, which may increase the reaction cost.

[0010] (2) Lower activity: Tin oxide catalysts may not be as catalytically active as other acid catalysts in certain esterification reactions, resulting in a slower reaction rate.

[0011] (3) Side reactions may occur: Tin oxide catalysts may cause side reactions in some cases, resulting in poor product selectivity.

[0012] (4) High temperature required: In some cases, the use of tin oxide as a catalyst requires a high reaction temperature, which may increase energy consumption and reduce environmental performance.

[0013] Nano-silica possesses a high specific surface area and large volume, providing more active surface area, which helps to uniformly disperse and immobilize the catalyst, improving its activity and stability. Nano-silica supports, with their high specific surface area and mild surface activity, can increase the catalyst loading and improve its activity and selectivity, thereby enhancing catalytic performance. The functional groups such as hydroxyl groups on the surface of nano-silica can provide additional affinity, promoting the adsorption of catalytic substances and the occurrence of reactions. Nano-silica supports exhibit high mechanical and chemical stability, which can improve the catalyst's heat resistance, poisoning resistance, and durability, extending its lifespan. Therefore, using nano-silica as a catalyst support in esterification reactions has the potential to improve the catalyst's catalytic performance and stability, and enhance the efficiency and selectivity of the catalytic reaction. Summary of the Invention

[0014] The existing technology has the problem that using concentrated sulfuric acid as a catalyst for the esterification reaction to synthesize pentaerythritol isostearate results in strong corrosivity and poor selectivity. To address these problems, this invention provides a modified nanocatalyst for esterification reactions, comprising the following preparation steps:

[0015] (1) Chlorosilane coupling agent reacts with hydrophilic nano silica in an organic solvent. Chlorine atoms in the molecular structure undergo a substitution reaction with hydrogen atoms on the surface of nano silica to generate Si-O-Si bonds, thus obtaining primary modified nano silica.

[0016] (2) The modified nano-silica reacts with the phosphite coupling agent in an organic solvent. The alkoxy group in the phosphite coupling agent molecule undergoes a hydrolysis reaction with the hydroxyl group on the surface of the modified nano-silica to generate Si-O-Si bonds, thus obtaining a modified nano-catalyst. The structural formula of the phosphite coupling agent is as follows:

[0017]

[0018] Preferably, the mass ratio of the chlorosilane coupling agent to nano-silica is 2-3:2.

[0019] Preferably, the chlorosilane coupling agent is 3-(p-methoxyphenyl)propyltrichlorosilane.

[0020] Preferably, the mass ratio between the phosphite coupling agent and the primary modified nano-silica is 3-5:3.

[0021] Preferably, step (1) includes the following preparation steps: hydrophilic nano-silica, chlorosilane coupling agent, and organic solvent are mixed evenly at a mass ratio of 2:2-3:10, and stirred at 25-45℃ for 3 hours. After the reaction is completed, the reaction solution is filtered and dried to obtain primary modified nano-silica.

[0022] Preferably, the organic solvent includes at least one of anhydrous ethanol, tetrahydrofuran, xylene, and acetone.

[0023] Preferably, the preparation method of the phosphite coupling agent includes the following steps:

[0024] 3-Aminopropyltriethoxysilane and phosphoric acid were reacted in anhydrous ethanol under stirring at a temperature of 50-80℃ for 3-5 hours. The mass ratio of 3-aminopropyltriethoxysilane to phosphoric acid was 1:2-3. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the phosphite coupling agent.

[0025] Preferably, the average particle size of the hydrophilic nano-silica is 10-100 nm.

[0026] The present invention has the following beneficial effects:

[0027] The modified nanocatalyst obtained by this invention has a good catalytic effect on esterification reaction. In particular, for the esterification reaction between pentaerythritol and isomeric acid, it can significantly reduce the reaction temperature and time, greatly improve the selectivity of the reaction, and the obtained pentaerythritol isostearate has a lower acid value and better quality. Detailed implementation method:

[0028] The present invention will be described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely illustrative examples of implementation of the present invention and are not intended to limit the scope of the present invention.

[0029] The structural formula of the phosphite coupling agent used in the following embodiments of the present invention is as follows:

[0030]

[0031] Its preparation method is as follows:

[0032] 3-Aminopropyltriethoxysilane and phosphoric acid were reacted in anhydrous ethanol under stirring at a temperature of 50-80℃ for 3-5 hours. The mass ratio of 3-aminopropyltriethoxysilane to phosphoric acid was 1:2-3. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the phosphite coupling agent.

[0033] The chlorosilane coupling agent used in the following embodiments of the present invention is 3-(p-methoxyphenyl)propyltrichlorosilane.

[0034] The hydrophilic nano silica used in the following embodiments of the present invention was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product number: S104588-500g.

[0035] Example 1

[0036] A modified nanocatalyst for esterification reaction is prepared as follows:

[0037] (1) The chlorosilane coupling agent and hydrophilic nano silica were stirred and reacted in anhydrous ethanol at a reaction temperature of 25°C for 3 hours. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the modified nano silica. The mass ratio of the chlorosilane coupling agent to the hydrophilic nano silica and the organic solvent was 2:2:10.

[0038] (2) The modified nano silica and the phosphite coupling agent were ultrasonically reacted in anhydrous ethanol at a temperature of 55°C for 3 hours. The ultrasonic power was 45% and the frequency was 35 kHz. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the modified nano catalyst. The mass ratio of the modified nano silica to the phosphite coupling agent and the organic solvent was 3:3:10.

[0039] 12.35 kg of pentaerythritol and 112.8 kg of isomeric acid were added to a reaction vessel, stirred, and then a modified nano-catalyst was added. The amount of modified nano-catalyst added was 0.5% of the total weight of pentaerythritol and isomeric acid. Under nitrogen protection, the reaction was stirred at 175 °C for 6 hours. After the reaction was completed, the catalyst was filtered off to obtain crude pentaerythritol isostearate with an esterification rate of 96.8% and an acid value of 1.02.

[0040] Example 2

[0041] A modified nanocatalyst for esterification reaction is prepared as follows:

[0042] (1) The chlorosilane coupling agent and hydrophilic nano silica were stirred and reacted in anhydrous ethanol at a reaction temperature of 35°C for 3 hours. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the modified nano silica. The mass ratio of the chlorosilane coupling agent to the hydrophilic nano silica and the organic solvent was 2:2.5:10.

[0043] (2) The modified nano silica and the phosphite coupling agent were ultrasonically reacted in anhydrous ethanol at a temperature of 55°C for 4 hours. The ultrasonic power was 45% and the frequency was 35kHz. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the modified nano catalyst. The mass ratio of the modified nano silica to the phosphite coupling agent and the organic solvent was 3:4:10.

[0044] 12.35 kg of pentaerythritol and 117.8 kg of isomeric acid were added to a reaction vessel, stirred, and then a modified nano-catalyst was added. The amount of modified nano-catalyst added was 0.5% of the total weight of pentaerythritol and isomeric acid. Under nitrogen protection, the reaction was stirred at 185 °C for 6 hours. After the reaction was completed, the catalyst was filtered off to obtain crude pentaerythritol isostearate with an esterification rate of 97.2% and an acid value of 0.98.

[0045] Example 3

[0046] A modified nanocatalyst for esterification reaction is prepared as follows:

[0047] (1) The chlorosilane coupling agent and hydrophilic nano silica were stirred and reacted in anhydrous ethanol at a reaction temperature of 45°C for 3 hours. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the modified nano silica. The mass ratio of the chlorosilane coupling agent to the hydrophilic nano silica and the organic solvent was 2:3:10.

[0048] (2) The modified nano silica and the phosphite coupling agent were ultrasonically reacted in anhydrous ethanol at a temperature of 55°C for 4 hours. The ultrasonic power was 45% and the frequency was 35 kHz. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the modified nano catalyst. The mass ratio of the modified nano silica to the phosphite coupling agent and the organic solvent was 3:5:10.

[0049] 12.35 kg of pentaerythritol and 122.8 kg of isomeric acid were added to a reaction vessel, and stirring was started. Then, a modified nano-catalyst was added, with the amount of modified nano-catalyst being 0.5% of the total weight of pentaerythritol and isomeric acid. Under nitrogen protection, the reaction was stirred at 195 °C for 6 hours. After the reaction was completed, the catalyst was filtered off to obtain crude pentaerythritol isostearate with an esterification rate of 98.8% and an acid value of 0.56.

[0050] Example 4

[0051] A modified nanocatalyst for esterification reaction is prepared as follows:

[0052] (1) The chlorosilane coupling agent and hydrophilic nano silica were stirred and reacted in anhydrous ethanol at a reaction temperature of 45°C for 3 hours. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the modified nano silica. The mass ratio of the chlorosilane coupling agent to the hydrophilic nano silica and the organic solvent was 2:3:10.

[0053] (2) The modified nano silica and the phosphite coupling agent were ultrasonically reacted in anhydrous ethanol at a temperature of 55°C for 3 hours. The ultrasonic power was 45% and the frequency was 35 kHz. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the modified nano catalyst. The mass ratio of the modified nano silica to the phosphite coupling agent and the organic solvent was 3:5:10.

[0054] 158 kg of isooctanol (CAS No.: 26952-21-6) and 250 kg of stearic acid were added to a reaction vessel, stirred, and then a modified nano-catalyst was added. The amount of modified nano-catalyst added was 0.2% of the total weight of isooctanol and stearic acid. Under nitrogen protection, the reaction was stirred at 145°C for 4 hours. After the reaction was completed, the catalyst was filtered off to obtain crude isooctanol isostearate with an esterification rate of 97.5% and an acid value of 0.1888.

[0055] Example 5

[0056] A modified nanocatalyst for esterification reaction is prepared as follows:

[0057] (1) The chlorosilane coupling agent and hydrophilic nano silica were stirred and reacted in anhydrous ethanol at a reaction temperature of 45°C for 3 hours. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the modified nano silica. The mass ratio of the chlorosilane coupling agent to the hydrophilic nano silica and the organic solvent was 2:3:10.

[0058] (2) The modified nano silica and the phosphite coupling agent were ultrasonically reacted in anhydrous ethanol at a temperature of 55°C for 5 hours. The ultrasonic power was 45% and the frequency was 35 kHz. After the reaction, the solvent was removed by vacuum distillation to obtain the modified nano catalyst. The mass ratio of the modified nano silica to the phosphite coupling agent and the organic solvent was 3:5:10.

[0059] 170 kg of isooctanol and 250 kg of stearic acid were added to a reaction vessel and stirred. Then, a modified nano-catalyst was added. The amount of modified nano-catalyst added was 0.2% of the total weight of isooctanol (CAS No.: 26952-21-6) and stearic acid. Under nitrogen protection, the reaction was stirred at 145 °C for 4 hours. After the reaction was completed, the catalyst was filtered off to obtain crude isooctanol isostearate with an esterification rate of 99.2% and an acid value of 0.1089.

[0060] Comparative Example 1 is the same as Example 1, except that the preparation method of the phosphite coupling agent in Comparative Example 1 is as follows:

[0061] N-(β-aminoethyl)-γ-aminopropyltriethoxysilane was reacted with phosphoric acid in xylene under stirring at a temperature of 50-80℃ for 3-5 hours. The mass ratio of 3-aminopropyltriethoxysilane to phosphoric acid was 1:2. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the phosphite coupling agent, the structural formula of which is as follows:

[0062]

[0063] The crude pentaerythritol isostearate obtained in Comparative Example 1 had an esterification rate of 90.5% and an acid value of 6.3.

[0064] Comparative Example 2 is the same as Example 1, except that the mass ratio of chlorosilane coupling agent to hydrophilic nano-silica in Comparative Example 2 is 1:2; the crude pentaerythritol isostearate obtained in Comparative Example 2 has an esterification rate of 91.78% and an acid value of 5.55.

[0065] Comparative Example 3 is the same as Example 1, except that the mass ratio of chlorosilane coupling agent to hydrophilic nano-silica in Comparative Example 3 is 2:1; the crude pentaerythritol isostearate obtained in Comparative Example 3 has an esterification rate of 89.2% and an acid value of 8.99.

[0066] Comparative Example 4 is the same as Example 1, except that the mass ratio of the primary modified nano-silica to the phosphite coupling agent in Comparative Example 4 is 4:3. The crude pentaerythritol isostearate obtained in Comparative Example 4 has an esterification rate of 91.3% and an acid value of 5.51.

[0067] Comparative Example 5 is the same as Example 1, except that the mass ratio of the primary modified nano-silica to the phosphite coupling agent in Comparative Example 5 is 3:4. The crude pentaerythritol isostearate obtained in Comparative Example 5 has an esterification rate of 93.5% and an acid value of 2.25.

[0068] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A modified nanocatalyst for esterification reactions, characterized in that, The preparation steps include the following: (1) Chlorosilane coupling agent reacts with hydrophilic nano silica in an organic solvent. Chlorine atoms in the molecular structure undergo a substitution reaction with hydrogen atoms on the surface of nano silica to generate Si-O-Si bonds, thus obtaining primary modified nano silica. (2) The modified nano-silica reacts with the phosphite coupling agent in an organic solvent. The alkoxy group in the phosphite coupling agent molecule undergoes a hydrolysis reaction with the hydroxyl group on the surface of the modified nano-silica to generate Si-O-Si bonds, thus obtaining a modified nano-catalyst. The structural formula of the phosphite coupling agent is as follows: ； The mass ratio of the chlorosilane coupling agent to nano-silica is 2-3:2; The chlorosilane coupling agent is 3-(p-methoxyphenyl)propyltrichlorosilane; The mass ratio of the phosphite coupling agent to the primary modified nano-silica is 3-5:3; The preparation method of the phosphite coupling agent includes the following steps: 3-Aminopropyltriethoxysilane and phosphoric acid were reacted in anhydrous ethanol under stirring at a temperature of 50-80℃ for 3-5 hours. The mass ratio of 3-aminopropyltriethoxysilane to phosphoric acid was 1:2-3. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the phosphite coupling agent.

2. The modified nanocatalyst for esterification reaction according to claim 1, characterized in that, Step (1) includes the following preparation steps: Hydrophilic nano-silica, chlorosilane coupling agent, and organic solvent are mixed evenly at a mass ratio of 2:2-3:10 and stirred at 25-45℃ for 3 hours. After the reaction is completed, the reaction solution is filtered and dried to obtain primary modified nano-silica.

3. The modified nanocatalyst for esterification reaction according to claim 1, characterized in that, The organic solvent includes at least one of anhydrous ethanol, tetrahydrofuran, xylene, and acetone.

4. The modified nanocatalyst for esterification reaction according to claim 1, characterized in that, The average particle size of the hydrophilic nano-silica is 10-100 nm.

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