Amino-functionalized mesoporous organosilica composites, methods of making, and use in the production of hydrofluoroethers

Abstract

The application belongs to the field of fluorinated chemicals, and particularly relates to an amino-functionalized mesoporous organosilica composite material, a preparation method and application in preparation of hydrofluoroether. The preparation method comprises the following steps: (1) preparing gold nanoparticles; (2) preparing mesoporous silica-based materials loaded with gold nanoparticles and forming hollow structures and functional modification. The amino-functionalized mesoporous organosilica composite material as a catalyst exhibits excellent catalytic activity. Gold nanoparticles as active centers can effectively activate the double bond in hexafluoropropylene molecules with reduced electron cloud density due to strong electron-withdrawing groups, significantly improving the conversion rate of the reaction and solving the problem of low raw material utilization rate caused by low activity of traditional catalysts.

Description

Technical Field

[0001] This invention belongs to the field of fluorochemicals, specifically relating to an amino-functionalized mesoporous organosilicon composite material, its preparation method, and its application in the preparation of hydrofluoroethers. Background Technology

[0002] Hexafluoropropyl methyl ether (HME), an important hydrofluoroether product, has broad application prospects in pharmaceuticals, pesticides, and electronic chemicals. Its unique fluorine-containing structure endows it with excellent chemical stability, lipophilicity, and biological activity, making it a key intermediate in the synthesis of various high-value-added fluorinated compounds. However, current methods for preparing HME in industrial production still face several unresolved issues. Traditional synthesis processes often suffer from harsh reaction conditions, low catalyst activity, poor selectivity, numerous byproducts, and low yields. For example, some existing catalysts are prone to deactivation during the reaction, resulting in short catalyst lifespans and increased production costs. Other catalysts lack sufficient selectivity for the target product, making product separation and purification more difficult, reducing production efficiency and affecting product purity and quality. Furthermore, most traditional catalysts are homogeneous, making them difficult to separate from the reaction system after the reaction, hindering recovery and reuse, leading to wasted catalyst resources, increased production costs, and potential environmental pollution. These shortcomings of existing technologies limit the large-scale, efficient production of HME and fail to meet the growing market demand. Therefore, developing a catalyst preparation method with high activity, high selectivity, mild reaction conditions, and recyclability is of great significance for promoting the development of the hexafluoropropyl methyl ether industry.

[0003] Mesoporous organosilicon materials have attracted widespread attention in the field of catalysis due to their high specific surface area, regular pore structure, and tunable surface properties. While their large pore size (2-50 nm) facilitates the diffusion of macromolecular reactants and products, their catalytic activity is limited. Loading with noble metals or metal oxides can improve their catalytic performance, but problems such as agglomeration and loss of active components lead to poor catalyst stability and recyclability. Furthermore, amino functionalization is a commonly used modification method. Introducing amino groups into the surface or framework of mesoporous materials can endow them with specific acid-base properties and coordination abilities, thereby improving their catalytic activity and selectivity for specific reactions. The surface of functionalized mesoporous organosilicon contains hydrophilic hydroxyl groups and lipophilic organic functional groups. This characteristic allows the reaction system to operate without the need for large amounts of organic solvents, reducing production costs and operational risks, and effectively reducing the emission of organic pollutants, thus meeting the requirements of green chemistry and sustainable development. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an amino-functionalized mesoporous organosilicon composite material, its preparation method, and its application in the preparation of hydrofluoroethers.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing an amino-functionalized mesoporous organosilicon composite material includes the following steps: (1) preparing gold nanoparticles; the specific steps are: using a chemical reduction method, dissolving a gold source compound in a solvent, adding a reducing agent, and reacting under stirring conditions to obtain gold nanoparticles; (2) preparing a mesoporous silica-based material loaded with gold nanoparticles and forming a hollow structure and functional modification; the specific steps are: using tetraethyl orthosilicate as a precursor to prepare a silica-based material coated with gold nanoparticles as a hard template, and under the conditions of ammonia and surfactant, carrying out a hydrothermal reaction with an organosilicon precursor and an aminosilane coupling agent in a solvent to obtain an amino-functionalized mesoporous organosilicon composite material.

[0006] The molar ratio of the reducing agent to the gold source compound in step (1) is 1:(0.5-1). The gold source compound is at least one of chloroauric acid, sodium chloroaurate, or potassium gold cyanide. The reducing agent is at least one of sodium citrate, sodium borohydride, or ascorbic acid. The solvent is at least one of water, ethanol, or ethylene glycol.

[0007] In step (2), the volume ratio of tetraethyl orthosilicate to ammonia is 2:(1-2); preferably 2:1.5; the volume ratio of tetraethyl orthosilicate to aminosilane coupling agent is 2000:(10-100); preferably 2000:(25-50); the mass-volume ratio of surfactant to aminosilane coupling agent is 1:(0.5-5) mg / μL; preferably 1:1 mg / μL; and the volume ratio of organosilane precursor to aminosilane coupling agent is 4:(0.5-2), preferably 4:1.

[0008] The organosilane precursor is 1,4-bis(triethoxysilyl)benzene; the surfactant is hexadecyltrimethylammonium bromide; and the aminosilane coupling agent is 3-aminopropyltriethoxysilane.

[0009] The present invention also includes an amino-functionalized mesoporous organosilicon composite material obtained by the preparation method described above.

[0010] This invention also includes the application of the aforementioned amino-functionalized mesoporous organosilicon composite material in the preparation of hydrofluoroethers; The hydrofluoroether is hexafluoropropyl methyl ether; the amino-functionalized mesoporous organosilicon composite material is used as a catalyst in the reaction of hexafluoropropylene and methanol to prepare hexafluoropropyl methyl ether.

[0011] The reaction temperature is 0-20℃, the mass ratio of catalyst to methanol is 1:(6-10), and the molar ratio of hexafluoropropylene to methanol is 1:1-1:1.5.

[0012] This invention addresses the problems of low catalyst activity, poor selectivity, easy deactivation, difficulty in recovery, and harsh reaction conditions in the preparation of hexafluoropropyl methyl ether in existing technologies. It proposes a highly efficient method for preparing hydrofluoroethers based on a composite catalyst. The core of this method lies in the use of a novel composite catalyst, which uses an amino-functionalized mesoporous organosilicon material as a support. A specific loading process is employed to highly disperse and stably load the metal active component (gold) within the support cavity. The design concept of the composite catalyst is to utilize the high specific surface area and regular pore structure of the mesoporous organosilicon material to provide sufficient active sites and good mass transfer channels for the reaction; the amphiphilic surface properties eliminate the need for large amounts of organic solvents in the reaction system; amino functionalization modification endows it with acid-base properties and coordination ability, regulating the adsorption and activation of reaction intermediates, thereby improving the selectivity for the target product; simultaneously, the introduction of the metal active component further enhances the catalyst's activation ability for the reaction substrate, lowers the activation energy of the reaction, and enables the reaction to proceed efficiently under relatively mild conditions. The application of this composite catalyst is expected to significantly improve the shortcomings of existing processes, increase the reaction yield and product purity of hexafluoropropyl methyl ether, simplify the separation and purification process, and achieve efficient recovery and reuse of the catalyst, thereby reducing production costs, reducing environmental pollution, and providing strong technical support for the large-scale and green production of hexafluoropropyl methyl ether.

[0013] Compared with the prior art, the beneficial effects of the present invention are: First, the amino-functionalized mesoporous organosilicon composite material of this invention exhibits excellent catalytic activity as a catalyst. Gold nanoparticles, acting as active centers, effectively activate the double bonds in hexafluoropropylene molecules, where the electron cloud density is reduced due to strong electron-withdrawing groups, significantly improving the reaction conversion rate and solving the problem of low raw material utilization caused by the low activity of traditional catalysts.

[0014] Secondly, this catalyst exhibits excellent selectivity. The modified amino groups in the skeleton can effectively activate and direct the reaction substrate through hydrogen bonding or electrostatic attraction with the reactant molecule methanol, guiding the reaction towards the formation of hexafluoropropyl methyl ether. This significantly reduces side reactions and improves the yield and purity of the target product. This effectively overcomes the shortcomings of traditional catalysts, such as poor selectivity, numerous and difficult-to-separate byproducts.

[0015] Furthermore, the catalyst framework contains both hydrophilic hydroxyl groups and lipophilic organic groups. This design allows the catalyst to simultaneously achieve good contact with both the polar aqueous phase and the non-polar organic phase in the reaction system, thereby significantly improving the mass transfer efficiency of the reaction. Specifically, the hydrophilic hydroxyl groups can form hydrogen bonds with water molecules, giving the catalyst good dispersibility in aqueous solvents and preventing catalyst aggregation; while the lipophilic organic groups can interact with organic reactants such as hexafluoropropylene and methanol, adsorbing them near the active site of the catalyst, providing favorable conditions for the smooth progress of the reaction. In addition, using water as a solvent is not only inexpensive and environmentally friendly, but it can also effectively dissolve polar byproducts that may be generated during the reaction, reducing the occurrence of side reactions and further improving the selectivity and yield of the target product.

[0016] Furthermore, the catalyst exhibits high stability and is recyclable and reusable. The hollow porous structure of the mesoporous silica-based material provides a stable confined environment for the gold nanoparticles, effectively preventing their aggregation and loss during the reaction process, thus ensuring the long-term stability of the catalyst. Simultaneously, this composite catalyst is a solid heterogeneous catalyst, easily separated from the reaction system, and can be recovered through simple physical methods such as filtration and centrifugation. After simple processing, it can be reused multiple times without significant decrease in catalytic activity and selectivity. This not only reduces catalyst consumption and lowers production costs but also helps reduce potential environmental pollution, aligning with the requirements of green chemistry and sustainable development. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the preparation method of the amino-functionalized mesoporous organosilicon composite material of the present invention; Figure 2 This is a TEM image of the amino-functionalized mesoporous organosilicon composite material of Example 1; Figure 3 This is a TEM image of the amino-functionalized mesoporous organosilicon composite material of Example 3; Figure 4 TEM image of the amino-functionalized mesoporous organosilicon composite material of Comparative Example 1; Figure 5 The XRD pattern of the amino-functionalized mesoporous organosilicon composite material of Example 1 is shown below. Figure 6 The infrared spectrum of the amino-functionalized mesoporous organosilicon composite material of Example 1; Figure 7 The F-spectrum of the product hexafluoropropylene methyl ether from the example is shown. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments.

[0019] Example 1: Synthesis method of composite catalyst for preparing hexafluoropropyl methyl ether (schematic diagram shown) Figure 1 The process, as shown, includes the following steps: 4 ml of 0.05 M sodium borohydride solution was rapidly added to a chloroauric acid solution (sodium borohydride to chloroauric acid molar ratio 1:1) under vigorous stirring. The mixture was magnetically stirred for a certain period to ensure the reduction reaction proceeded fully. Gold nanoparticles were collected by high-speed centrifugation and, after multiple water washings, dispersed in a mixture of water and ethanol. Subsequently, 2 ml of tetraethyl orthosilicate was rapidly added, and after stirring for 2 hours, 1.5 ml of ammonia and 200 mg of the surfactant cetyltrimethylammonium bromide were added, and stirring continued for 3 hours. Finally, (200 μL) of 1,4-bis(triethoxysilyl)benzene and (50 μL) of 3-aminopropyltriethoxysilane were added, and after stirring for 5 hours, the mixture was placed in a hydrothermal reactor and reacted for 12 hours. After the reaction was terminated, a pink powder catalyst-1 was collected by centrifugation and dried under vacuum at 60 °C for 6 hours. Hollow structures were obtained by solvent extraction to remove the silica-based template while retaining gold particles. Specifically, the obtained powder was added to an acidic ethanol solution, stirred under reflux for 24 hours, and the target product was obtained by centrifugation. Figure 2 For TEM images, Figure 5 For XRD patterns, Figure 6 The infrared image confirms the presence of an NH2 group.

[0020] Example 2: The difference between Example 2 and Example 1 lies in the mass ratio of sodium borohydride solution to chloroauric acid solution. 4 ml of 0.05 M sodium borohydride solution was rapidly added to the chloroauric acid solution (sodium borohydride to chloroauric acid molar ratio 1:0.8) under vigorous stirring, and the mixture was magnetically stirred for a certain period to ensure the reduction reaction proceeded fully. Other conditions remained unchanged, yielding catalyst-2.

[0021] Example 3: The difference between Example 3 and Example 1 lies in the mass ratio of sodium borohydride solution to chloroauric acid solution. Under vigorous stirring, 4 ml of 0.05 M sodium borohydride solution was rapidly added to the chloroauric acid solution (sodium borohydride to chloroauric acid molar ratio 1:0.5), and the mixture was magnetically stirred for a certain period to ensure the reduction reaction proceeded fully. Other conditions remained unchanged, yielding catalyst-3. Figure 3 The TEM image is shown.

[0022] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the composite catalyst was not loaded with gold nanoparticles. 2 ml of tetraethyl orthosilicate was rapidly added to a mixture of water and ethanol, and after stirring for 2 hours, 1.5 ml of ammonia and 200 mg of the surfactant hexadecyltrimethylammonium bromide were added, and stirring continued for 3 hours. Finally, (200 μL) of 1,4-bis(triethoxysilyl)benzene and (50 μL) of 3-aminopropyltriethoxysilane were added, and after stirring for 5 hours, the mixture was placed in a hydrothermal reactor and reacted for 12 hours. After the reaction was terminated, the catalyst was collected by centrifugation, dried under vacuum at -40°C for 6 hours, and the template was removed by solvent extraction. Figure 4 The TEM image is shown.

[0023] Example 4: The difference between Example 4 and Example 1 is that the mass ratio of the silicon-based material loaded with gold nanoparticles to the organosilane precursor is different. Under vigorous stirring, 4 ml of 0.05 M sodium borohydride solution was rapidly added to a chloroauric acid solution (sodium borohydride to chloroauric acid molar ratio 1:1), and the mixture was magnetically stirred for a certain period to promote a complete reduction reaction. The gold nanoparticles were collected by high-speed centrifugation, and after multiple water washings, the obtained gold nanoparticles were dispersed in a mixed solution of water and ethanol. Subsequently, 2 ml of tetraethyl orthosilicate was rapidly added, and after stirring for 2 hours, 1.5 ml of ammonia and 200 mg of surfactant were added, and stirring continued for 3 hours. Finally, (100 μL) of 1,4-bis(triethoxysilyl) and (25 μL) of 3-aminopropyltriethoxysilane were added, and after stirring for 5 hours, the mixture was placed in a hydrothermal reactor and reacted for 12 hours. After the reaction was terminated, a pink powder catalyst was collected by centrifugation, dried under vacuum at 60°C for 6 hours, and the template was removed by solvent extraction.

[0024] Example 5: The catalysts obtained in Examples 1-4 and Comparative Example 1 were used to prepare hexafluoropropyl methyl ether. The specific steps included: First, methanol, water, and the prepared catalyst were added to a three-necked flask, with a catalyst-to-methanol mass ratio of 1:8. The mixture was stirred thoroughly to ensure homogeneity. Hexafluoropropylene was introduced at 0-20°C, with a hexafluoropropylene-to-methanol molar ratio of 1:1. After the reaction was complete, the mixture was stirred continuously for 3 hours. After the reaction was finished, the catalyst was separated by filtration to obtain crude hexafluoropropyl methyl ether. The crude hexafluoropropyl methyl ether was then distilled to obtain hexafluoropropyl methyl ether (…). Figure 7 The F spectrum of hexafluoropropyl methyl ether prepared by catalyst-1 in Example 1 is shown.

[0025] Table 1

[0026] Example 6: The difference between Example 6 and Example 5 lies in the mass ratio of catalyst-1 to methanol. Specifically, the steps are as follows: First, methanol, water, and the prepared catalyst are added to a three-necked flask, with a catalyst-to-methanol mass ratio of 1:10. The mixture is stirred thoroughly to ensure homogeneity. Hexafluoropropylene is introduced at 0-20°C, with a hexafluoropropylene-to-methanol molar ratio of 1:1. After the reaction is complete, stirring is continued for 3 hours. After the reaction is finished, the catalyst is separated by filtration to obtain a crude product. The crude hexafluoropropyl methyl ether is then distilled to obtain hexafluoropropyl methyl ether. The conversion rate of this reaction is 68.3%, and the yield of hexafluoropropyl methyl ether is 93.1%.

[0027] Example 7: The difference between Example 7 and Example 6 lies in the mass ratio of catalyst-1 to methanol. Specifically, the steps are as follows: First, methanol, water, and the prepared catalyst are added to a three-necked flask, with a catalyst-to-methanol mass ratio of 1:6. The mixture is stirred thoroughly to ensure homogeneity. Hexafluoropropylene is introduced at 0-20°C, with a hexafluoropropylene-to-methanol molar ratio of 1:1. After the reaction is complete, stirring is continued for 3 hours. After the reaction is finished, the catalyst is separated by filtration to obtain a crude product. The crude hexafluoropropyl methyl ether is then distilled to obtain hexafluoropropyl methyl ether. The conversion rate of this reaction is 72.3%, and the yield of hexafluoropropyl methyl ether is 93.4%.

[0028] Example 8: The catalyst repeat experiment was carried out by washing the catalyst-1 obtained from Example 6 three times with deionized water and adding it back into the reaction system. After five cycles with other conditions unchanged, the conversion rate of the reaction was 76.5% and the yield of hexafluoropropyl methyl ether was 93.1%.

[0029] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of an amino-functionalized mesoporous organosilicon composite material in the preparation of hydrofluoroethers, characterized in that, The hydrofluoroether is hexafluoropropyl methyl ether; the amino-functionalized mesoporous organosilicon composite material is used as a catalyst in the reaction of hexafluoropropylene and methanol to prepare hexafluoropropyl methyl ether; A method for preparing amino-functionalized mesoporous organosilicon composite materials includes the following steps: (1) preparing gold nanoparticles; specifically including the following steps: using a chemical reduction method, dissolving a gold source compound in a solvent, adding a reducing agent, reacting under stirring conditions to obtain gold nanoparticles; the molar ratio of the reducing agent to the gold source compound is 1:(0.5-1). (2) Prepare mesoporous silica-based materials loaded with gold nanoparticles and form hollow structures and functional modifications; specifically including the following steps: using tetraethyl orthosilicate as a precursor to prepare silica-based materials coated with gold nanoparticles as hard templates, and then, under the conditions of ammonia and surfactant, carry out hydrothermal reactions with organosilane precursors and aminosilane coupling agents in a solvent to form hollow structures and obtain amino-functionalized mesoporous organosilicone composite materials. The volume ratio of tetraethyl orthosilicate to ammonia is 2:(1-2); the volume ratio of tetraethyl orthosilicate to aminosilane coupling agent is 2000:(10-100); the mass-to-volume ratio of surfactant to aminosilane coupling agent is 1:(0.5-5) mg / μL; the volume ratio of organosilane precursor to aminosilane coupling agent is 4:(0.5-2). The organosilane precursor is 1,4-bis(triethoxysilyl)benzene; the surfactant is hexadecyltrimethylammonium bromide; and the aminosilane coupling agent is 3-aminopropyltriethoxysilane.

2. The application of the amino-functionalized mesoporous organosilicon composite material according to claim 1 in the preparation of hydrofluoroethers, characterized in that, In step (1) The gold source compound is at least one of chloroauric acid, sodium chloroaurate, or potassium gold cyanide. The reducing agent is at least one of sodium citrate, sodium borohydride, or ascorbic acid. The solvent is at least one of water, ethanol, or ethylene glycol.

3. The application of the amino-functionalized mesoporous organosilicon composite material according to claim 1 in the preparation of hydrofluoroethers, characterized in that, The reaction temperature is 0-20℃, the catalyst dosage to methanol mass ratio is 1:(6-10), and the molar ratio of hexafluoropropylene to methanol is 1:1-1:1.5.

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