Temperature-sensitive capsule catalyst as well as preparation method and application thereof

Abstract

The invention provides a temperature-sensitive capsule catalyst and a preparation method and application thereof, and the preparation method comprises the following steps: (1) preparing an N-isopropylacrylamide solution with a certain concentration, adding N, N '-methylene bisacrylamide, and fully dispersing to obtain a mixed solution A; (2) preparing an initiator solution with a certain concentration to obtain a solution B, slowly adding the solution B into the solution A, reacting under the protection of nitrogen, and freeze-drying after the reaction is finished to obtain a material C; (3) preparing a solution C with a certain concentration from the material C, and adding a proper amount of metal salt into the solution C to obtain a mixed solution D; and (4) under the action of an electric field, dropwise adding the mixed solution D into an anti-solution, and filtering and drying to obtain the temperature-sensitive capsule catalyst. When the temperature-sensitive capsule catalyst is used for catalyzing a hydrosilylation reaction, active metal components are released, and a coating material and a reaction system are in two phases and are convenient to separate.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and in particular relates to a temperature-sensitive capsule catalyst and a preparation method and application thereof. Background Art

[0002] Due to its unique structure, organic silicon materials have excellent properties such as environmental friendliness, insulation and low surface tension, and are widely used in electronic packaging, daily chemical products and construction. The hydrosilylation reaction of olefin molecules and silane molecules is one of the important methods for preparing such materials. However, this reaction has high requirements for conditions and usually uses transition metals as catalysts.

[0003] The platinum-isopropanol complex homogeneous catalyst (Speier catalyst) commonly used in industry not only has strict requirements on storage and transportation conditions, but also has certain challenges in the separation and post-processing of the materials after the reaction. If the homogeneous catalyst can be coated with temperature-sensitive materials to release the active components at a specific reaction temperature, and the separation of the coated material can be achieved by temperature control after the reaction is completed, the process will be greatly simplified. Therefore, the development of a new and efficient temperature-sensitive encapsulated catalyst can not only effectively solve these problems, but also has important significance for promoting the further development of the organosilicon chemical industry. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a temperature-sensitive encapsulated catalyst for hydrosilylation reaction, which has high reactant conversion rate, high target product selectivity, is easy to transport and separate, and a preparation method and application thereof.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A method for preparing a temperature-sensitive encapsulated catalyst comprises the following steps:

[0007] (1) preparing a certain concentration of N-isopropylacrylamide solution, adding N,N'-methylenebisacrylamide and fully dispersing it to obtain a mixed solution A;

[0008] (2) preparing an initiator solution of a certain concentration to obtain solution B, slowly adding solution B to solution A, reacting in a constant temperature water bath under nitrogen protection, and freeze-drying after the reaction to obtain a solid material C;

[0009] (3) preparing a solution C of a certain concentration using material C, and adding an appropriate amount of metal salt to the solution C to obtain a mixed solution D;

[0010] (4) under the action of the electric field, the mixed solution D is added dropwise to the anti-solution, and after filtering and drying, a temperature-sensitive encapsulated catalyst is obtained;

[0011] In step (4), the electric field conditions are: the voltage is 20 to 30 kV, and the dropping speed of the mixed solution D is 2 to 20 mL / h.

[0012] Preferably, in the mixed solution A, the mass ratio of N,N'-methylenebisacrylamide to N-isopropylacrylamide is 0.015 to 0.1; more preferably, it is 0.02 to 0.08.

[0013] Preferably, the solvents of the N-isopropylacrylamide solution and solution B are both selected from at least one of toluene, xylene, dichloromethane, N,N-dimethylacetamide, dimethyl sulfoxide and tetrahydrofuran.

[0014] Preferably, in step (1), the concentration of the N-isopropylacrylamide solution is 5 wt % to 20 wt %.

[0015] Preferably, in step (2), the initiator is selected from potassium persulfate or azobisisobutyronitrile.

[0016] Preferably, the added amount of the initiator is 0.005 to 0.05 times the total mass of N-isopropylacrylamide and N,N'-methylenebisacrylamide; more preferably, it is 0.005 to 0.02 times.

[0017] Preferably, in step (2), the reaction temperature is 40-70° C. and the reaction time is 2-10 h.

[0018] Preferably, in step (2), the reaction temperature is 45-60° C. and the reaction time is 4-10 h.

[0019] Preferably, in step (2), the freeze-drying conditions are: -20°C to -80°C, freeze-drying for 24 to 48 hours. Preferably, in step (3), the solvent of the C solution is selected from one or more of water, methanol, ethanol, propanol or acetone;

[0020] Preferably, the metal salt is selected from at least one of Pt, Pd or Ru metal salts.

[0021] Preferably, the metal salt of Pd is selected from at least one of sodium chloropalladate, palladium chloride or palladium nitrate dihydrate; the metal salt of Pt is selected from at least one of chloroplatinic acid hexahydrate, potassium tetrachloroplatinate or tetraammineplatinum dichloride; the metal salt of Ru is selected from at least one of ruthenium chloride, ruthenium nitrate or hexaammineruthenium chloride.

[0022] Preferably, in step (3), the amount of metal added is 0.05wt% to 1.2wt% of the total mass of material C, and more preferably 0.1wt% to 1.0wt%. The amount of metal added here refers to the mass of the metal contained in the metal salt.

[0023] Preferably, in step (4), the antisolvent is selected from one or more of n-hexane, cyclohexane or heptane;

[0024] Preferably, in step (4), the electric field conditions are: the voltage is 25 to 30 kV, and the dropping speed of the mixed solution D is 2 to 15 mL / h; the dropping speed of the mixed solution D is further preferably 2 to 10 mL / h.

[0025] Preferably, in the prepared temperature-sensitive capsule catalyst, the metal loading is 0.05wt% to 1.2wt%; more preferably, the metal loading is 0.1wt% to 1.0wt%.

[0026] The present invention provides a temperature-sensitive capsule catalyst prepared according to the preparation method.

[0027] The present invention also provides an application of the temperature-sensitive capsule catalyst for hydrosilylation reaction.

[0028] Preferably, the temperature-sensitive capsule catalyst is used for the hydrosilylation reaction of ethylene and trimethoxysilane to prepare ethyltrimethoxysilane.

[0029] Preferably, the conditions for the hydrosilylation reaction are: temperature 30-60° C., pressure: 0.25-0.5 MPa; more preferably, the reaction temperature is 35-55° C., and the pressure is 0.3-0.45 MPa.

[0030] The technical solution of the present invention is to use N-isopropylacrylamide as a polymerization monomer and N,N'-methylenebisacrylamide as a crosslinking agent, and obtain a mixed solution A after homogeneous dispersion; then, the mixed solution A is subjected to a polymerization reaction in the presence of an initiator to prepare a material C, i.e., a polymer poly(N-isopropylacrylamide); and then, different temperature-sensitive capsule catalysts are prepared by selecting different metals and adjusting the ratio of metal salts and polymers. The temperature-sensitive capsule catalyst is a metal active component encapsulated in a polymer capsule, and the polymer poly(N-isopropylacrylamide) is a temperature-sensitive polymer material with unique phase change characteristics: below the critical temperature, its molecular chain is in a relaxed state and has a large volume; and above the critical temperature, its molecular chain shrinks rapidly, resulting in its aggregation or precipitation. When the temperature-sensitive capsule catalyst is used to catalyze the hydrosilylation reaction, when the temperature is lower than the critical temperature, the active metal component is coated in poly(N-isopropylacrylamide); when the temperature is higher than the critical temperature, the molecular chain of poly(N-isopropylacrylamide) shrinks, the active metal component is released, and the coating material poly(N-isopropylacrylamide) and the reaction system are in two phases, which are easy to separate.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) When the temperature-sensitive encapsulated catalyst prepared by the present invention is used to catalyze the hydrosilylation reaction, when the temperature is lower than the critical temperature, the active metal component is encapsulated in the material C poly(N-isopropylacrylamide); when the temperature is higher than the critical temperature, the poly(N-isopropylacrylamide) molecular chain shrinks, the active metal component is released, and the encapsulated material poly(N-isopropylacrylamide) and the reaction system are in two phases, which are easy to separate; the temperature-sensitive encapsulated catalyst effectively simplifies the material separation and post-treatment process after the reaction is completed, and has excellent catalytic activity and selectivity.

[0033] (2) The preparation method of the present invention can prepare different types of temperature-sensitive encapsulated catalytic materials by selecting the type of metal salt and adjusting the ratio of the metal salt and the polymer material, and has a wide range of applications.

[0034] (3) The catalyst preparation method provided by the present invention is simple, easy, low-cost and environmentally friendly. At the same time, the catalyst has good stability due to its capsule shell. Its application conditions in the hydrosilylation reaction are mild and environmentally friendly, showing broad prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a scanning electron microscope image of the capsule-type metal catalyst in Example 1.

[0036] Figure 2 This is a scanning electron microscope image of the capsule-type metal catalyst in Example 2.

[0037] Figure 3 This is a scanning electron microscope image of the capsule-type metal catalyst in Example 3.

[0038] Figure 4 This is a scanning electron microscope image of the capsule-type metal catalyst in Example 4. DETAILED DESCRIPTION

[0039] The present invention is described in detail and completely with specific embodiments and in conjunction with the accompanying drawings. It should be understood that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of the present invention.

[0040] As used herein, "room temperature" refers to 20-30°C.

[0041] The present invention provides a method for preparing a temperature-sensitive encapsulated catalyst, comprising the following steps:

[0042] (1) preparing a certain concentration of N-isopropylacrylamide solution, adding N,N'-methylenebisacrylamide and fully dispersing it to obtain a mixed solution A;

[0043] (2) preparing an initiator solution of a certain concentration to obtain solution B, slowly adding solution B to solution A, reacting in a constant temperature water bath under nitrogen protection, and freeze-drying after the reaction to obtain a solid material C;

[0044] (3) preparing a solution C of a certain concentration using material C, and adding an appropriate amount of metal salt to the solution C to obtain a mixed solution D;

[0045] (4) under the action of the electric field, the mixed solution D is added dropwise to the anti-solution, and after filtering and drying, a temperature-sensitive encapsulated catalyst is obtained;

[0046] In step (4), the electric field conditions are: the voltage is 20 to 30 kV, and the dropping speed of the mixed solution D is 2 to 20 mL / h.

[0047] In one embodiment of the present invention, in the mixed solution A, the mass ratio of N,N'-methylenebisacrylamide to N-isopropylacrylamide is 0.015-0.1; preferably, the mass ratio of N,N'-methylenebisacrylamide to N-isopropylacrylamide is 0.02-0.08, for example, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07 or 0.08.

[0048] In one embodiment of the present invention, the solvents of the N-isopropylacrylamide solution and solution B are both selected from at least one of toluene, xylene, dichloromethane, N,N-dimethylacetamide, dimethyl sulfoxide and tetrahydrofuran.

[0049] In one embodiment of the present invention, in step (1), the concentration of the N-isopropylacrylamide solution is 5 wt % to 20 wt %.

[0050] In one embodiment of the present invention, in step (2), the initiator is selected from potassium persulfate or azobisisobutyronitrile.

[0051] In one embodiment of the present invention, the added amount of the initiator is 0.005 to 0.05 times the total mass of N-isopropylacrylamide and N,N'-methylenebisacrylamide; more preferably 0.005 to 0.02 times.

[0052] In one embodiment of the present invention, in step (2), the reaction temperature is 40-70°C, and the reaction time is 2-10 hours; preferably, in step (2), the reaction temperature is 45-60°C, and the reaction time is 4-10 hours.

[0053] In one embodiment of the present invention, in step (2), the freeze-drying conditions are: -20°C to -80°C, and freeze-drying for 24 to 48 hours.

[0054] In one embodiment of the present invention, in step (3), the solvent of the C solution is selected from one or more of water, methanol, ethanol, propanol or acetone;

[0055] In one embodiment of the present invention, the metal salt is selected from at least one of Pt, Pd or Ru metal salts.

[0056] In one embodiment of the present invention, the metal salt of Pd is selected from at least one of sodium chloropalladate, palladium chloride or palladium nitrate dihydrate; the metal salt of Pt is selected from at least one of chloroplatinic acid hexahydrate, potassium tetrachloroplatinate or tetraammineplatinum dichloride; the metal salt of Ru is selected from at least one of ruthenium chloride, ruthenium nitrate or hexaammineruthenium chloride.

[0057] In one embodiment of the present invention, in step (3), the amount of metal added is 0.05wt% to 1.2wt% of the total mass of material C; more preferably 0.1wt% to 1.0wt%.

[0058] In one embodiment of the present invention, in step (4), the antisolvent is selected from one or more of n-hexane, cyclohexane or heptane;

[0059] In one embodiment of the present invention, in step (4), the electric field conditions are: the voltage is 25 to 30 kV, the dripping speed of the mixed solution D is 2 to 15 mL / h; the dripping speed of the mixed solution D is further preferably 2 to 10 mL / h, for example 2 mL / h, 4 mL / h, 6 mL / h, 7 mL / h, 8 mL / h, 9 mL / h or 10 mL / h

[0060] In one embodiment of the present invention, the metal loading in the prepared temperature-sensitive capsule catalyst is 0.05wt% to 1.2wt%; preferably 0.1wt% to 1.0wt%, for example 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt% or 0.9wt%.

[0061] The present invention provides a temperature-sensitive capsule catalyst prepared according to the preparation method.

[0062] The present invention also provides an application of the temperature-sensitive capsule catalyst, which is used for preparing ethyltrimethoxysilane by a hydrosilylation reaction of ethylene and trimethoxysilane.

[0063] In one embodiment of the present invention, the conditions for the hydrosilylation reaction are: temperature 30-60° C., pressure: 0.25-0.5 MPa; more preferably, the reaction temperature is 35-55° C., and the pressure is 0.3-0.45 MPa.

[0064] The technical solution of the present invention is described in detail below in conjunction with more specific embodiments.

[0065] Example 1

[0066] A method for preparing a temperature-sensitive encapsulated catalyst comprises the following steps:

[0067] (1) preparing 50 mL of a 10 wt % N-isopropylacrylamide toluene solution, stirring until completely dissolved, adding 0.1 g of N,N'-methylenebisacrylamide, and dispersing the mixture using a homogenizer for 5 minutes to obtain a uniform mixed solution A;

[0068] (2) preparing 50 mL of a 0.1 wt % azobisisobutyronitrile toluene solution to obtain solution B;

[0069] (3) Solution B was slowly added to Solution A, and then the reaction bottle was purged with nitrogen for about 15 minutes to remove oxygen, and then the reaction system was placed in a 50° C. constant temperature water bath for 10 hours under nitrogen protection; after the reaction, it was cooled to room temperature, and the reaction product was freeze-dried for 24 hours to obtain material C;

[0070] (4) Prepare 50 mL of 2 wt% acetone solution of material C, and add 0.0105 g of chloroplatinic acid hexahydrate to form a mixed solution D; then, under the action of a 30 kV electric field, add the mixed solution D dropwise into n-hexane at a rate of 2 mL / h through a micro constant speed injection pump, and then filter and dry to obtain the desired temperature-sensitive capsule catalyst. The scanning electron microscope image of the prepared temperature-sensitive capsule catalyst is shown in FIG. Figure 1 As shown, the Pt loading of the catalyst was measured to be 0.49 wt % by inductively coupled plasma (ICP) test.

[0071] Example 2

[0072] Compared with Example 1, the difference of the method for preparing the temperature-sensitive encapsulated catalyst provided in this example is that in step (4), the flow rate of the micro-constant injection pump is set differently. In this example, the mixed solution D is added dropwise to n-hexane at a rate of 10 mL / h by a micro-constant injection pump, and the other conditions are the same. The scanning electron microscope image of the prepared temperature-sensitive encapsulated catalyst is as follows: Figure 2 The Pt loading of the catalyst was measured by ICP test to be 0.45 wt%.

[0073] Example 3

[0074] Compared with Example 1, the difference of the method for preparing the temperature-sensitive capsule catalyst provided in this example is that in step (4), the flow rate of the micro-constant injection pump is set differently. In this example, the mixed solution D is added dropwise to n-hexane at a rate of 20 mL / h by a micro-constant injection pump, and the other conditions are the same. The scanning electron microscope image of the prepared temperature-sensitive capsule catalyst is as follows: Figure 3 The Pt loading of the catalyst was measured by ICP test to be 0.46 wt%.

[0075] Example 4

[0076] Compared with Example 1, the difference of the method for preparing the temperature-sensitive encapsulated catalyst is that in step (4), the flow rate of the micro-constant injection pump is set differently. In this embodiment, the mixed solution D is added dropwise to n-hexane at a rate of 50 mL / h by a micro-constant injection pump, and the other conditions are the same. The scanning electron microscope image of the prepared temperature-sensitive encapsulated catalyst is as follows: Figure 4 The Pt loading of the catalyst was measured by ICP test to be 0.47 wt%.

[0077] Example 5

[0078] Compared with Example 1, the difference of the method for preparing the temperature-sensitive encapsulated catalyst is that in step (1), the mass ratio of N,N'-methylenebisacrylamide and N-isopropylacrylamide is different. In this embodiment, 50mL of N-isopropylacrylamide toluene solution with a mass concentration of 10wt% is prepared, stirred until completely dissolved, and then 0.5g of N,N'-methylenebisacrylamide is added, and the other conditions are the same. The Pt loading of the catalyst measured by ICP test is 0.45wt%.

[0079] Example 6

[0080] Compared with Example 1, the difference of the method for preparing the temperature-sensitive encapsulated catalyst is that in step (2), the amount of the initiator added is different. In this embodiment, 50 mL of azobisisobutyronitrile toluene solution with a mass concentration of 0.2 wt% is prepared to obtain solution B, and the other conditions are the same. The Pt loading of the catalyst measured by ICP test is 0.46 wt%.

[0081] Example 7

[0082] Compared with Example 1, the difference of the method for preparing the temperature-sensitive encapsulated catalyst is that in step (2), the type of initiator is different. In this embodiment, 50 mL of a 0.1 wt% potassium persulfate toluene solution is prepared to obtain solution B, and the other conditions are the same. The Pt loading of the catalyst is measured by ICP test to be 0.47 wt%.

[0083] Example 8

[0084] Compared with Example 1, the difference of the method for preparing the temperature-sensitive encapsulated catalyst is only that in step (2), the polymerization reaction temperature is different. In this embodiment, solution B is slowly added to solution A, and then the reaction bottle is purged with nitrogen for about 15 minutes to remove oxygen, and then the reaction system is placed in a 45°C constant temperature water bath for 10 hours, and the other conditions are the same. The Pt loading of the catalyst measured by ICP test is 0.46wt%.

[0085] Example 9

[0086] Compared with Example 1, the difference of the method for preparing the temperature-sensitive encapsulated catalyst is only that in step (2), the polymerization reaction temperature is different. In this embodiment, solution B is slowly added to solution A, and then the reaction bottle is purged with nitrogen for about 15 minutes to remove oxygen, and then the reaction system is placed in a 65°C constant temperature water bath for 10 hours, and the other conditions are the same. The Pt loading of the catalyst measured by ICP test is 0.46wt%.

[0087] Example 10

[0088] Compared with Example 1, the difference of the method for preparing the temperature-sensitive encapsulated catalyst is that in step (2), the polymerization reaction time is different. In this embodiment, solution B is slowly added to solution A, and then the reaction bottle is purged with nitrogen for about 15 minutes to remove oxygen, and then the reaction system is placed in a 50°C constant temperature water bath for 2 hours, and the other conditions are the same. The Pt loading of the catalyst measured by ICP test is 0.47wt%.

[0089] Embodiment 11

[0090] Compared with Example 1, the difference of the method for preparing the temperature-sensitive encapsulated catalyst is only that in step (2), the polymerization reaction time is different. In this embodiment, solution B is slowly added to solution A, and then the reaction bottle is purged with nitrogen for about 15 minutes to remove oxygen, and then the reaction system is placed in a 50°C constant temperature water bath for 5 hours, and the other conditions are the same. The Pt loading of the catalyst measured by ICP test is 0.45wt%.

[0091] Example 12

[0092] Compared with Example 1, the difference of the method for preparing the temperature-sensitive encapsulated catalyst is that in step (2), the polymerization reaction time is different. In this embodiment, solution B is slowly added to solution A, and then the reaction bottle is purged with nitrogen for about 15 minutes to remove oxygen, and then the reaction system is placed in a 50°C constant temperature water bath for 12 hours, and the other conditions are the same. The Pt loading of the catalyst measured by ICP test is 0.47wt%.

[0093] Example 13

[0094] Compared with Example 1, the difference of the method for preparing the temperature-sensitive encapsulated catalyst is that in step (4), the amount of metal salt added is different. In this embodiment, 50 mL of 2 wt% acetone solution of material C is prepared, and 0.0052 g of chloroplatinic acid hexahydrate is added to form a mixed solution D, and the other conditions are the same. The Pt loading of the catalyst measured by ICP test is 0.23 wt%.

[0095] Embodiment 14

[0096] Compared with Example 1, the difference of the method for preparing the temperature-sensitive encapsulated catalyst is that in step (4), the amount of metal salt added is different. In this embodiment, 50 mL of acetone solution of material C with a mass concentration of 2 wt% is prepared, and 0.0210 g of chloroplatinic acid hexahydrate is added to form a mixed solution D, and the other conditions are the same. The Pt loading of the catalyst measured by ICP test is 1.02 wt%.

[0097] Embodiment 15

[0098] Compared with Example 1, the difference of the method for preparing the temperature-sensitive encapsulated catalyst is that in step (4), the type of metal salt added is different. In this embodiment, 50 mL of 2 wt% acetone solution of material C is prepared, and 0.0066 g of palladium chloride is added to form a mixed solution D. The other conditions are the same. The Pd loading of the catalyst is measured by ICP test to be 0.48 wt%.

[0099] Example 16

[0100] Compared with Example 1, the difference of the method for preparing the temperature-sensitive encapsulated catalyst is that in step (4), the type of metal salt added is different. In this embodiment, 50 mL of 2 wt% acetone solution of material C is prepared, and 0.0124 g of ruthenium nitrate is added to form a mixed solution D. The other conditions are the same. The Ru loading of the catalyst is measured by ICP test to be 0.47 wt%.

[0101] Embodiment 17

[0102] Compared with Example 1, the difference of the method for preparing the temperature-sensitive encapsulated catalyst is that in step (1), the mass ratio of N,N'-methylenebisacrylamide and N-isopropylacrylamide is different. In this embodiment, 50mL of a 10wt% N-isopropylacrylamide toluene solution is prepared, stirred until completely dissolved, and then 0.2g of N,N'-methylenebisacrylamide is added, and the other conditions are the same. The Pt loading of the catalyst measured by ICP test is 0.47wt%.

[0103] Comparative Example 1

[0104] 1g of carbon nanotubes was used as a carrier and as a mass reference. H2PtCl4 was weighed at a loading rate of 1wt%, and ultrasonically dissolved in 1mL of ultrapure water to obtain a Pt metal salt solution. 1g of carbon nanotubes was added to the metal Pt salt solution, and stirred with a glass rod to fully mix the carrier and the solution. The impregnated catalyst precursor was aged at room temperature for 12 hours, and then dried in a 120°C oven for 12 hours. In a reducing atmosphere of pure hydrogen, the catalyst was reduced at 400°C for 4 hours to obtain a 1% Pt / CNT catalyst. According to ICP detection, the Pt loading of the catalyst was 0.96wt%.

[0105] Comparative Example 2

[0106] 100 mL of 0.4 mol / L Na2CO3 aqueous solution was added to a three-necked flask, and then three metal salts H2PtCl4, Mg(NO3)2·6H2O and Al(NO3)3·9H2O were dissolved in 100 mL of ultrapure water (referred to as solution E). In the ternary metal salt solution, the content of Pt is 1 wt%, and the content of Mg is 1 wt%. 2+ :Al 3+ The molar ratio is 3:1. At the same time, 250mL of a NaOH solution with a concentration of 0.4mol / L (referred to as solution F) was also prepared. During the mixing process, the temperature was maintained at 65°C, the pH of the solution was maintained at 10±0.5, and solution E and solution F were slowly added to the three-necked flask at the same time and stirred vigorously. After the addition was completed, the temperature of the reaction solution was maintained at 65°C for 16 hours, and then filtered and washed with ultrapure water several times until the pH value of the washing solution was 7. Finally, the sample was dried in still air at 100°C for 12 hours, and then immersed in a 2mol / L Na2CO3 solution for 16 hours under stirring at room temperature. The sample obtained after filtration and drying was then reduced at 850°C for 4 hours under pure hydrogen conditions to obtain a Pt-LDH catalyst. According to ICP detection, the Pt loading of the catalyst was 0.98wt%.

[0107] Example 18 Catalyst Performance Evaluation

[0108] Catalyst performance evaluation

[0109] Take 30 mg of the catalyst obtained in the above examples 1 to 17 respectively, dissolve it in 1 mL of isopropanol, stir it thoroughly and add it to the reactor with 3.5 mol of trimethoxysilane. As a comparison, take 30 mg of the catalyst obtained in comparative examples 1 to 2 and 3.5 mol of trimethoxysilane and add them to the reactor, seal the reactor, and purge the air with argon for several times. When the reaction temperature stabilizes to the set value, fill ethylene into the reactor, then start stirring and timing. The stirring rate is 800 rpm, and the reaction temperature is 20 to 60 ° C and the pressure is 0.3 to 0.5 MPa. After 18 hours of reaction, take a sample, and the sample is immediately analyzed by gas chromatography.

[0110] It should be noted that the product after the reaction was analyzed using an Agilent 6890N gas chromatograph, the chromatographic column used was HP-50 (15m×320um×0.25um), the carrier gas was nitrogen, and the detector was a flame ionization detector.

[0111] The catalytic performance of the catalyst of the present invention for preparing ethyltrimethoxysilane by the hydrosilylation reaction of ethylene and trimethoxysilane was evaluated by testing the trimethoxysilane conversion rate and ethyltrimethoxysilane selectivity and yield of the catalysts prepared in Examples 1 to 17 and the Pt / CNT and Pt-LDH catalysts. The reaction conditions and results are shown in Table 1.

[0112] Wherein: In the hydrosilylation reaction of ethylene and trimethoxysilane, the calculation formulas for the conversion rate of trimethoxysilane and the selectivity and yield of ethyltrimethoxysilane are as follows:

[0113] X(%)=(n 初始三甲氧基硅烷 -n 反应后三甲氧基硅烷 ) / n 初始三甲氧基硅烷 ×100%

[0114] S i (%)=(n 组分i ×A i ) / n 初始三甲氧基硅烷 ×100%

[0115] Y i (%) = X × S i ×100%

[0116] Wherein, X represents the conversion rate of trimethoxysilane, in %;

[0117] n 初始三甲氧基硅烷 、n 反应后三甲氧基硅烷 Respectively represent the amount of trimethoxysilane at the beginning and after the reaction, in mol;

[0118] S i It represents the selectivity of component i, in %;

[0119] n 组分i It represents the amount of substance of component i after the reaction, in mol;

[0120] A i Indicates the number of carbon atoms contained in the molecule of component i;

[0121] Y i It represents the yield of component i in %.

[0122] Table 1. Evaluation results of hydrosilylation reaction of ethylene and trimethoxysilane using temperature-sensitive capsule catalyst

[0123]

[0124]

[0125] Since the hydrosilylation reaction will produce side reactions during the heating process, the temperature-sensitive capsule catalyst wall material to be prepared can shrink rapidly within the reaction temperature range, so that the metal components with catalytic activity are quickly released. After the reaction is completed, the catalyst wall material is easy to separate and easy to recover. Table 1 shows that compared with Examples 1-2 and Examples 3-4, Example 1-2 has better performance; combined with Figures 1 to 4 It can be seen that there are significant differences in the morphology of the catalysts of Examples 1-2 and Examples 3-4, resulting in differences in catalytic performance. The catalysts prepared in Examples 1-2 have a spherical morphology, while the morphology of Example 3 is a sphere and a silk thread coexisting, and the morphology of Example 4 is a membrane structure. It can be seen that under the action of the electric field, the rate of entry into the antisolvent significantly affects the morphology of the temperature-sensitive capsule-type catalyst, and when the catalyst structure is a sphere, a more excellent catalytic result is exhibited. Comparing the results of Examples 5, 11 and other examples, it is found that the mass ratio of N,N'-methylenebisacrylamide and N-isopropylacrylamide and the time of the polymerization reaction have a certain effect on the catalytic performance of the catalyst. The two mainly affect the release of the active components of the catalyst by affecting the performance of the capsule catalyst wall material. It can be seen from the evaluation results of the catalyst prepared in Example 1 under different temperature and pressure conditions that when the reaction is carried out at 25°C, the experimental results are significantly poor. This is because the temperature-sensitive encapsulated catalyst of the present invention releases limited metal active components at lower temperatures, but when the temperature rises to above 35°C, the metal active components can be released quickly, thereby fully demonstrating the temperature-sensitive characteristics of the catalyst of the present invention.

[0126] In addition, it can be seen from the experimental data in Table 1 that in the hydrosilylation reaction of ethylene and trimethoxysilane catalyzed by the capsule-type metal catalyst prepared by the present invention, the conversion rate of trimethoxysilane exceeds 90%, and the selectivity of ethyltrimethoxysilane is greater than 90%, which is significantly better than the Pt / CNT and Pt-LDH catalysts in the prior art.

[0127] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a temperature-sensitive encapsulated catalyst, characterized in that: The steps include: (1) preparing a certain concentration of N-isopropylacrylamide solution, adding N,N'-methylenebisacrylamide and fully dispersing it to obtain a mixed solution A; (2) preparing an initiator solution of a certain concentration to obtain solution B, slowly adding solution B to solution A, reacting in a constant temperature water bath under nitrogen protection, and freeze-drying after the reaction to obtain a solid material C; (3) preparing a solution C of a certain concentration using material C, and adding an appropriate amount of metal salt to the solution C to obtain a mixed solution D; (4) under the action of the electric field, the mixed solution D is added dropwise to the anti-solution, and after filtering and drying, a temperature-sensitive encapsulated catalyst is obtained; In step (4), the electric field conditions are: the voltage is 20 to 30 kV, and the dropping speed of the mixed solution D is 2 to 20 mL / h.

2. The method for preparing a temperature-sensitive encapsulated catalyst according to claim 1, characterized in that: In step (1), in the mixed solution A, the mass ratio of N,N'-methylenebisacrylamide to N-isopropylacrylamide is 0.015 to 0.

1.

3. The method for preparing a temperature-sensitive encapsulated catalyst according to claim 1, characterized in that: In step (1), the concentration of the N-isopropylacrylamide solution is 5wt% to 20wt%; the solvents of the N-isopropylacrylamide solution and solution B are both selected from at least one of toluene, xylene, dichloromethane, N,N-dimethylacetamide, dimethyl sulfoxide and tetrahydrofuran.

4. The method for preparing a temperature-sensitive encapsulated catalyst according to claim 1, characterized in that: In step (2), the initiator is selected from potassium persulfate or azobisisobutyronitrile, and the added amount of the initiator is 0.005 to 0.05 times the total mass of N-isopropylacrylamide and N,N'-methylenebisacrylamide; in step (2), the reaction temperature is 40 to 70°C, and the reaction time is 2 to 10 hours.

5. The method for preparing a temperature-sensitive encapsulated catalyst according to claim 1, characterized in that: In step (3), the solvent of the C solution is selected from one or more of water, methanol, ethanol, propanol or acetone; the metal salt is selected from at least one of Pt, Pd or Ru metal salts, wherein the metal salt of Pd is selected from at least one of sodium chloropalladate, palladium chloride or palladium nitrate dihydrate; the metal salt of Pt is selected from at least one of chloroplatinic acid hexahydrate, potassium tetrachloroplatinate or tetraammineplatinum dichloride; the metal salt of Ru is selected from at least one of ruthenium chloride, ruthenium nitrate or hexaammineruthenium chloride.

6. The method for preparing a temperature-sensitive encapsulated catalyst according to claim 1, characterized in that: In step (3), the amount of metal added is 0.05wt% to 1.2wt% of the total mass of material C.

7. The method for preparing a temperature-sensitive encapsulated catalyst according to claim 1, characterized in that: In step (4), the antisolvent is selected from one or more of n-hexane, cyclohexane or heptane; the electric field voltage is 25 to 30 kV; and the dripping speed is 2 to 15 mL / h.

8. The method for preparing a temperature-sensitive encapsulated catalyst according to claim 1, characterized in that: In the prepared temperature-sensitive capsule catalyst, the metal loading amount is 0.05wt% to 1.2wt%.

9. A temperature-sensitive encapsulated catalyst prepared according to the preparation method according to any one of claims 1 to 8.

10. A use of the temperature-sensitive encapsulated catalyst as claimed in claim 9, characterized in that: Used in hydrosilylation reactions.

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