A capsule type metal catalyst, a method for preparing the same, and an application thereof

Abstract

The application provides a capsule type metal catalyst and a preparation method and application thereof, and comprises the following steps: (1) preparing a carboxymethyl cellulose sodium aqueous solution with a certain concentration, adding an additive and a metal salt solution, uniformly dispersing, and obtaining a mixed solution A; (2) preparing a gelatin aqueous solution with a certain concentration, then mixing the gelatin aqueous solution with the mixed solution A, uniformly mixing, adjusting the pH of the solution to be acidic, and continuing to react, and obtaining a mixed solution B; (3) placing the obtained mixed solution B in an ice water bath, adding a solidifying agent to perform a cross-linking solidification reaction, and obtaining material C; and (4) washing and drying the material C to obtain the capsule type metal catalyst. The capsule type metal catalyst prepared by the application can be applied to a silicon hydrogen addition reaction, and high reactant conversion and high target product selectivity can be realized under mild reaction conditions.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalyst preparation, and particularly relates to a capsule type metal catalyst and a preparation method and application thereof. BACKGROUND

[0002] The platinum (Pt) catalyzed hydrosilylation of olefins with silanes has important industrial applications in the field of homogeneous catalysis, which converts basic olefins and silanes into high value-added silicon-based materials, which have a wide range of applications in adhesives, coatings, drug development and other fields. For example, the annual output of (n-octyl) Si(OEt)3 is more than 6000 tons. By using multifunctional olefins as reaction substrates, hydrosilylation products containing one or more functional groups can be synthesized, thereby further broadening their application range. However, the traditional Karstedt catalyst often leads to difficult separation of reaction products or produces unnecessary by-products due to the inability to selectively activate substrate molecules, which limits its industrialization process. Although certain catalysts can improve catalytic activity under specific conditions, harsh reaction conditions are usually required, and the selectivity is limited and not widely applicable.

[0003] In view of the above, it is necessary to develop a new type of efficient metal catalyst and a preparation method thereof to overcome the above problems, which is of great significance to the organosilicon chemical industry. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a capsule type metal catalyst for hydrosilylation reaction, which has mild reaction conditions, good catalytic activity, high conversion rate of reactants and high selectivity of target products, as well as a preparation method and application thereof.

[0005] To achieve the above purpose, the technical scheme of the present application is as follows:

[0006] A preparation method of a capsule type metal catalyst, comprising the following steps:

[0007] (1) preparing a carboxymethyl cellulose sodium aqueous solution with a certain concentration, then adding an additive and a metal salt solution to the carboxymethyl cellulose sodium aqueous solution, and uniformly dispersing to obtain a mixed solution A;

[0008] (2) preparing a gelatin solution with a certain concentration, and mixing the gelatin solution and the mixed solution A uniformly, then adjusting the pH of the solution to be acidic and continuing to react to obtain a mixed solution B;

[0009] (3) placing the mixed solution B obtained in step (2) in an ice water bath, and adding a solidifying agent for crosslinking and solidification reaction to obtain material C;

[0010] (4) washing and drying the material C to obtain the capsule type metal catalyst.

[0011] The application further provides that in step (1), the additive is selected from one or more of nano-sized silicon dioxide and nano-sized titanium dioxide; and the metal salt solution is selected from one of a Pt, Pd or Ru metal salt alcohol solution.

[0012] The application further provides that in step (1), 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 dichlorotetrakisamine platinum; and the metal salt of Ru is selected from at least one of ruthenium chloride, ruthenium nitrate or chlorohexamine ruthenium.

[0013] The application further provides that the mass ratio of sodium carboxymethyl cellulose to gelatin is 0.4-3.0; and further preferably 0.75-2.0.

[0014] The application further provides that the additive is added in an amount of 0.2-1.5 times the total mass of sodium carboxymethyl cellulose and gelatin.

[0015] The application further provides that the mass of the additive is 0.006-0.2 times the mass of the metal salt.

[0016] The application further provides that in step (2), the gelatin aqueous solution and the mixed solution A are mixed uniformly, the pH of the solution is adjusted to be acidic, and the reaction is continued to obtain a mixed solution B; wherein the temperature of the reaction system is 40-60℃, the pH of the solution is adjusted to be 3.8-4.7, and the reaction time is 0.5h-3.0h. Preferably, the pH of the solution is adjusted to be 4.0-4.5; and further preferably, the pH of the solution is adjusted to be 4.1.

[0017] The application further provides that the mass concentration of the sodium carboxymethyl cellulose aqueous solution is 1-10wt%; and further preferably 1-5wt%; and the mass concentration of the gelatin aqueous solution is 1-10wt%, and further preferably 1-5wt%.

[0018] The application further provides that in step (3), the solidifying agent is selected from at least one of glycerol and hydroxyethyl cellulose.

[0019] The application further provides that the solidifying agent is added in an amount of 0.5-10 times the total mass of sodium carboxymethyl cellulose and gelatin; and further preferably 1-6 times.

[0020] The application further provides that in step (3), the time for solidifying cross-linking reaction is 4-10h.

[0021] The application further provides that in step (4), the selected solvent for washing is ethanol or acetone; and the drying conditions are: -20-80 DEG C, freeze drying for 8-20 hours.

[0022] The application also provides a capsule type metal catalyst prepared according to the above preparation method, wherein the loading amount of the metal is 0.05-2.0 wt%.

[0023] The application also provides an application of the capsule type metal catalyst, which is used for a hydrosilylation reaction.

[0024] The application further provides that the capsule type metal catalyst is used for a hydrosilylation reaction of ethylene and trimethoxysilane to prepare ethyl trimethoxysilane.

[0025] The application further provides that the hydrosilylation reaction is carried out under the following conditions: temperature 30-60 DEG C, pressure 0.25-0.5 MPa; and further preferably, reaction temperature 35-55 DEG C, pressure 0.3-0.45 MPa.

[0026] Compared with the prior art, the application has the following beneficial effects:

[0027] (1) The application provides a controllable preparation method of a capsule type metal catalyst with ordered structure and stability, wherein gelatin and sodium carboxymethyl cellulose are used as wall materials of the catalyst, a gelatin and sodium carboxymethyl cellulose aqueous solution is configured, nanoscale titanium dioxide or nanoscale silicon dioxide and a metal salt solution are added, and the capsule type metal catalyst is prepared by a complex gel method; by adjusting the proportion and element of the metal salt, different types of capsule type metal catalyst materials are prepared, and the controllable preparation of different types of capsule type metal materials is realized.

[0028] (2) The capsule type metal catalyst of the application encapsulates a homogeneous metal catalyst in a capsule, which not only facilitates the transportation and storage of the catalyst, but also stably releases a catalytically active component under mild reaction conditions; and the capsule type metal catalyst provides an ideal choice for a hydrosilylation reaction of a silane molecule and an olefin molecule due to its high catalytic activity and good selectivity of a target product.

[0029] (3) The catalyst of the application is applied to a hydrosilylation reaction of ethylene and trimethoxysilane to prepare ethyl trimethoxysilane, which can realize excellent catalytic effect under relatively mild reaction conditions. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 FIG. 2 is a scanning electron microscope image of the capsule type metal catalyst in Example 1. DETAILED DESCRIPTION

[0031] The application will be described in detail below with specific embodiments and in conjunction with the drawings. It should be understood that the described embodiments are only part of the embodiments of the application, but not all. Based on the embodiments of the application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of the application.

[0032] As used herein, "room temperature" refers to 10-30°C, preferably 20-25°C.

[0033] The application provides a preparation method of a capsule type metal catalyst, comprising the following steps:

[0034] (1) preparing a sodium carboxymethyl cellulose aqueous solution with a certain concentration at 40-60°C, then adding an additive and a metal salt solution to the sodium carboxymethyl cellulose aqueous solution, uniformly dispersing, and obtaining a mixed solution A;

[0035] (2) preparing a gelatin solution with a certain concentration at 40-60°C, mixing the gelatin solution and the mixed solution A uniformly, adjusting the pH of the solution to be acidic, and continuing to react, to obtain a mixed solution B;

[0036] (3) placing the mixed solution B obtained in step (2) in an ice water bath, and adding a solidifying agent for crosslinking and solidification reaction to obtain material C;

[0037] (4) washing and drying the material C to obtain the capsule type metal catalyst;

[0038] In step (1), the additive is selected from one or more of nano-sized silicon dioxide and nano-sized titanium dioxide; the metal salt solution is selected from one of Pt, Pd or Ru metal salt alcohol solution; in step (3), the solidifying agent is selected from at least one of glycerol and hydroxyethyl cellulose; the mass ratio of sodium carboxymethyl cellulose and gelatin is 0.4-3.0; the addition amount of the metal salt is 0.2-1.5 times the total mass of sodium carboxymethyl cellulose and gelatin; and the mass of the additive is 0.006-0.2 times the mass of the metal salt.

[0039] In an embodiment of the application, the mass ratio of sodium carboxymethyl cellulose and gelatin is 0.75-2.0, for example, 0.75, 1.0, 1.5 or 2.0.

[0040] In an embodiment of the application, the addition amount of the metal salt is 0.5-1.2 times the total mass of sodium carboxymethyl cellulose and gelatin; further preferably, 0.5-1.0 times.

[0041] In one embodiment of the present application, in step (1), 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 dichlorotetrakisamine platinum; and the metal salt of Ru is selected from at least one of ruthenium chloride, ruthenium nitrate or chlorohexamine ruthenium.

[0042] The concentration of the metal salt alcohol solution can be routinely prepared by those skilled in the art as needed. In one embodiment of the present application, the concentration of the metal salt solution ranges from 0.5 mmol / L to 2 mmol / L.

[0043] In one embodiment of the present application, in step (2), the gelatin solution and the mixed solution A are mixed uniformly, and then the pH of the solution is adjusted to be acidic, and the reaction is continued to obtain a mixed solution B; wherein the temperature of the reaction system is 40-60℃, the pH of the solution is adjusted to 3.8-4.7, and the reaction time is 0.5h-3.0h.

[0044] In one embodiment of the present application, the pH of the solution is adjusted to 4.0-4.5, for example, the pH of the solution is adjusted to 4.0, 4.1, 4.2, 4.3, 4.4 or 4.5.

[0045] In one embodiment of the present application, in step (3), the amount of the added solidifying agent is 0.5-10 times, and further preferably 1-6 times, the total mass of sodium carboxymethyl cellulose and gelatin.

[0046] In one embodiment of the present application, in step (3), the time for solidification and cross-linking reaction is 4-10h.

[0047] In one embodiment of the present application, in step (4), the solvent used for washing is ethanol or acetone; and the drying conditions are: -20℃-80℃, and freeze-drying for 8-20h.

[0048] The present application also provides a capsule type metal catalyst prepared according to the above preparation method, wherein the loading amount of the metal is 0.05-2.0wt%, and further preferably 0.1-1.5wt%.

[0049] The present application also provides an application of the capsule type metal catalyst, which is used for a hydrosilylation reaction.

[0050] In one embodiment of the present application, the capsule type metal catalyst is used for the catalytic performance of the hydrosilylation reaction of ethylene and trimethoxysilane to prepare ethyl trimethoxysilane.

[0051] In one embodiment of the present application, the conditions for the hydrosilylation reaction are: temperature 30-50°C, pressure: 0.25-0.5 MPa; further preferably, temperature 35-50°C, such as 35°C, 40°C, 45°C and 50°C; and pressure preferably 0.3-0.45 MPa.

[0052] The technical solutions of the present application are described in detail below in combination with more specific embodiments.

[0053] Example 1

[0054] A method for preparing a capsule type metal catalyst, comprising the following steps:

[0055] (1) 50 mL of a 2 wt% carboxymethyl cellulose sodium aqueous solution is prepared, heated and stirred at 45°C until completely dissolved, then 0.02 g of nano-sized silicon dioxide and 1.328 g of chloroplatinic acid hexahydrate isopropyl alcohol solution containing chloroplatinic acid hexahydrate are added to the carboxymethyl cellulose sodium aqueous solution, and a homogenizer is used for dispersion for 5 minutes to obtain a mixed solution A;

[0056] (2) 50 mL of a 2 wt% gelatin aqueous solution is prepared, heated and stirred at 45°C until completely dissolved, then the gelatin aqueous solution and the mixed solution B are mixed, and uniform stirring is continued at 45°C, then the pH of the solution is adjusted to 4.1, and stirring is continued for 75 minutes to obtain a mixed solution B;

[0057] (3) After the reaction is completed, the mixed solution B obtained in step (2) is placed in an ice water bath, and 6 g of glycerol is added for crosslinking and solidification reaction for 10 h to obtain a material C;

[0058] (4) The material C is washed with an ethanol solution, and then freeze-dried at -60°C for 12 h to prepare the capsule type metal catalyst. The scanning electron microscope (SEM) image of the capsule type metal catalyst is shown in Figure 1 The inductively coupled plasma (ICP) test is performed on the prepared capsule type metal catalyst, and the Pt loading of the catalyst is 0.51 wt%.

[0059] Example 2

[0060] A method for preparing a capsule type metal catalyst, comprising the following steps:

[0061] (1) 50 mL of a 1 wt% carboxymethyl cellulose sodium aqueous solution is prepared, heated and stirred at 45°C until completely dissolved, then 0.005 g of nano-sized silicon dioxide and 0.856 g of dichlorotetraamine platinum isopropyl alcohol solution containing dichlorotetraamine platinum are added to the carboxymethyl cellulose sodium aqueous solution, and a homogenizer is used for dispersion for 5 minutes to obtain a mixed solution A;

[0062] (2) Prepare 50 mL of 1 wt% gelatin aqueous solution, heat and stir at 45°C until completely dissolved, then mix the gelatin aqueous solution with the mixed solution B, continue to stir at 45°C, adjust the pH of the solution to 4.1 within 30 minutes, continue to stir for 75 minutes after the reaction, and obtain the mixed solution B;

[0063] (3) After the reaction is completed, place the mixed solution B obtained in step (2) in an ice water bath, and add 3 g of glycerol for cross-linking and solidification reaction for 7 h to obtain material C;

[0064] (4) Wash the material C with an ethanol solution, and freeze dry at -60°C for 12 h to obtain the capsule type metal catalyst. The Pt loading of the catalyst is 0.47 wt% by ICP test.

[0065] Example 3

[0066] (1) Prepare 50 mL of 1.5 wt% sodium carboxymethyl cellulose aqueous solution, heat and stir at 45°C until completely dissolved, then add 0.02 g of nano-sized silicon dioxide and 1.064 g of potassium tetrachloroplatinate in potassium tetrachloroplatinate isopropanol solution to the sodium carboxymethyl cellulose aqueous solution, and disperse using a homogenizer for 5 minutes to obtain a mixed solution A;

[0067] (2) Prepare 50 mL of 2 wt% gelatin aqueous solution, heat and stir at 45°C until completely dissolved, then mix the gelatin aqueous solution with the mixed solution B, continue to stir at 45°C, adjust the pH of the solution to 4.1 within 30 minutes, continue to stir for 75 minutes after the reaction, and obtain the mixed solution B;

[0068] (3) After the reaction is completed, place the mixed solution B obtained in step (2) in an ice water bath, and add 6 g of glycerol for cross-linking and solidification reaction for 10 h to obtain material C;

[0069] (4) Wash the material C with an ethanol solution, and freeze dry at -60°C for 12 h to obtain the capsule type metal catalyst. The Pt loading of the catalyst is 0.46 wt% by ICP test.

[0070] Example 4

[0071] (1) Prepare 50 mL of 2 wt% sodium carboxymethyl cellulose aqueous solution, heat and stir at 45°C until completely dissolved, then add 0.02 g of nano-sized silicon dioxide and 1.064 g of potassium tetrachloroplatinate in potassium tetrachloroplatinate isopropanol solution to the sodium carboxymethyl cellulose aqueous solution, and disperse using a homogenizer for 5 minutes to obtain a mixed solution A;

[0072] (2) Prepare 50 mL of 2 wt% gelatin aqueous solution, heat and stir at 45°C until completely dissolved, then mix the gelatin aqueous solution with the mixed solution B, continue to stir at 45°C, adjust the pH of the solution to 3.8 within 30 minutes, and continue to stir for 75 minutes after the reaction to obtain the mixed solution B.

[0073] (3) After the reaction is completed, place the mixed solution B obtained in step (2) in an ice water bath, and add 6 g of glycerol for cross-linking and solidification reaction for 10 h to obtain material C;

[0074] (4) Wash the material C with an ethanol solution, and freeze dry at -60°C for 12 h to obtain the capsule type metal catalyst. The Pt loading of the catalyst is 0.48 wt% by ICP test.

[0075] Example 5

[0076] (1) Prepare 50 mL of 2 wt% sodium carboxymethyl cellulose aqueous solution, heat and stir at 45°C until completely dissolved, then add 0.02 g of nano-sized silicon dioxide and 1.064 g of potassium tetrachloroplatinate in potassium tetrachloroplatinate isopropanol solution to the sodium carboxymethyl cellulose aqueous solution, and disperse using a homogenizer for 5 minutes to obtain the mixed solution A;

[0077] (2) Prepare 50 mL of 2 wt% gelatin aqueous solution, heat and stir at 45°C until completely dissolved, then mix the gelatin aqueous solution with the mixed solution B, continue to stir at 45°C, adjust the pH of the solution to 4.7 within 30 minutes, and continue to stir for 75 minutes after the reaction to obtain the mixed solution B;

[0078] (3) After the reaction is completed, place the mixed solution B obtained in step (2) in an ice water bath, and add 6 g of glycerol for cross-linking and solidification reaction for 10 h to obtain material C;

[0079] (4) Wash the material C with an ethanol solution, and freeze dry at -60°C for 12 h to obtain the capsule type metal catalyst. The Pt loading of the catalyst is 0.48 wt% by ICP test.

[0080] Example 6

[0081] (1) Prepare 50 mL of 2 wt% sodium carboxymethyl cellulose aqueous solution, heat and stir at 45°C until completely dissolved, then add 0.02 g of nano-sized silicon dioxide and 0.532 g of potassium tetrachloroplatinate in potassium tetrachloroplatinate isopropanol solution to the sodium carboxymethyl cellulose aqueous solution, and disperse using a homogenizer for 5 minutes to obtain the mixed solution A;

[0082] (2) Prepare 50 mL of 2 wt% gelatin aqueous solution, heat and stir at 45°C until completely dissolved, then mix the gelatin aqueous solution with the mixed solution B, continue to stir at 45°C, adjust the pH of the solution to 3.8 within 30 minutes, continue to stir for 75 minutes after the reaction, and obtain the mixed solution B;

[0083] (3) After the reaction is completed, place the mixed solution B obtained in step (2) in an ice water bath, and add 6 g of glycerol for cross-linking and solidification reaction for 10 h to obtain material C;

[0084] (4) Wash the material C with an ethanol solution, and freeze dry at -60°C for 12 h to obtain the capsule type metal catalyst. The Pt loading of the catalyst is 0.26 wt% by ICP test.

[0085] Example 7

[0086] (1) Prepare 50 mL of 2 wt% sodium carboxymethyl cellulose aqueous solution, heat and stir at 45°C until completely dissolved, then add 0.02 g of nano-sized silicon dioxide and 1.252 g of palladium nitrate dihydrate isopropanol solution containing palladium nitrate dihydrate to the sodium carboxymethyl cellulose aqueous solution, and disperse using a homogenizer for 5 minutes to obtain a mixed solution A;

[0087] (2) Prepare 50 mL of 2 wt% gelatin aqueous solution, heat and stir at 45°C until completely dissolved, then mix the gelatin aqueous solution with the mixed solution B, continue to stir at 45°C, adjust the pH of the solution to 4.1 within 30 minutes, continue to stir for 75 minutes after the reaction, and obtain the mixed solution B;

[0088] (3) After the reaction is completed, place the mixed solution B obtained in step (2) in an ice water bath, and add 6 g of glycerol for cross-linking and solidification reaction for 4 h to obtain material C;

[0089] (4) Wash the material C with an ethanol solution, and freeze dry at -60°C for 12 h to obtain the capsule type metal catalyst. The Pd loading of the catalyst is 0.52 wt% by ICP test.

[0090] Example 8

[0091] (1) Prepare 50 mL of 1 wt% sodium carboxymethyl cellulose aqueous solution, heat and stir at 45°C until completely dissolved, then add 0.02 g of nano-sized silicon dioxide and 0.833 g of palladium chloride isopropanol solution containing palladium chloride to the sodium carboxymethyl cellulose aqueous solution, and disperse using a homogenizer for 5 minutes to obtain a mixed solution A;

[0092] (2) Prepare 50 mL of 2wt% gelatin aqueous solution, heat and stir at 45°C until completely dissolved, then mix the gelatin aqueous solution with mixed solution B, continue to stir at 45°C, adjust the pH of the solution to 4.1 within 30 minutes, continue to stir for 75 minutes after the reaction, and obtain mixed solution B;

[0093] (3) After the reaction is completed, place the mixed solution B obtained in step (2) in an ice water bath, and add 3 g of hydroxyethyl cellulose for cross-linking and solidification reaction for 5 h to obtain material C;

[0094] (4) Wash the material C with an ethanol solution, and freeze dry at -60°C for 12 h to obtain the capsule type metal catalyst. The Pd loading of the catalyst is 0.49wt% by ICP test.

[0095] Example 9

[0096] (1) Prepare 50 mL of 1wt% sodium carboxymethyl cellulose aqueous solution, heat and stir at 45°C until completely dissolved, then add 0.04 g of nano-sized silicon dioxide and 1.388 g of sodium chloropalladate in sodium chloropalladate isopropanol solution to the sodium carboxymethyl cellulose aqueous solution, and disperse using a homogenizer for 5 minutes to obtain mixed solution A;

[0097] (2) Prepare 50 mL of 1wt% gelatin aqueous solution, heat and stir at 45°C until completely dissolved, then mix the gelatin aqueous solution with mixed solution B, continue to stir at 45°C, adjust the pH of the solution to 4.1 within 30 minutes, continue to stir for 75 minutes after the reaction, and obtain mixed solution B.

[0098] (3) After the reaction is completed, place the mixed solution B obtained in step (2) in an ice water bath, and add 10 g of glycerol for cross-linking and solidification reaction for 10 h to obtain material C;

[0099] (4) Wash the material C with an ethanol solution, and freeze dry at -60°C for 12 h to obtain the capsule type metal catalyst. The Pd loading of the catalyst is 0.48wt% by ICP test.

[0100] Example 10

[0101] (1) Prepare 50 mL of 2wt% sodium carboxymethyl cellulose aqueous solution, heat and stir at 45°C until completely dissolved, then add 0.03 g of nano-sized silicon dioxide and 1.532 g of hexaammineruthenium chloride in hexaammineruthenium chloride isopropanol solution to the sodium carboxymethyl cellulose aqueous solution, and disperse using a homogenizer for 5 minutes to obtain mixed solution A;

[0102] (2) Prepare 50 mL of 2wt% gelatin aqueous solution, heat and stir at 45°C until completely dissolved, then mix the gelatin aqueous solution with mixed solution B, continue to stir at 45°C, adjust the pH of the solution to 4.1 within 30 minutes, continue to stir for 75 minutes after the reaction, and obtain mixed solution B.

[0103] (3) After the reaction is completed, place the mixed solution B obtained in step (2) in an ice water bath, and add 10 g of hydroxyethyl cellulose for cross-linking and solidification reaction for 10 h to obtain material C;

[0104] (4) Wash the material C with acetone solution, and freeze dry at -60°C for 12 h to obtain the capsule type metal catalyst. The Ru loading of the catalyst is 0.47wt% by ICP test.

[0105] Example 11

[0106] (1) Prepare 50 mL of 2wt% sodium carboxymethyl cellulose aqueous solution, heat and stir at 45°C until completely dissolved, then add 0.01 g of nano-sized silicon dioxide and 1.569 g of ruthenium nitrate isopropanol solution containing ruthenium nitrate to the sodium carboxymethyl cellulose aqueous solution, and disperse using a homogenizer for 5 minutes to obtain mixed solution A;

[0107] (2) Prepare 50 mL of 1wt% gelatin aqueous solution, heat and stir at 45°C until completely dissolved, then mix the gelatin aqueous solution with mixed solution B, continue to stir at 45°C, adjust the pH of the solution to 4.1 within 30 minutes, continue to stir for 120 minutes after the reaction, and obtain mixed solution B;

[0108] (3) After the reaction is completed, place the mixed solution B obtained in step (2) in an ice water bath, and add 6 g of glycerol for cross-linking and solidification reaction for 10 h to obtain material C;

[0109] (4) Wash the material C with acetone solution, and freeze dry at -60°C for 12 h to obtain the capsule type metal catalyst. The Ru loading of the catalyst is 0.51wt% by ICP test.

[0110] Example 12

[0111] (1) Prepare 50 mL of 1wt% sodium carboxymethyl cellulose aqueous solution, heat and stir at 45°C until completely dissolved, then add 0.02 g of nano-sized titanium dioxide and 1.024 g of ruthenium chloride isopropanol solution containing ruthenium chloride trihydrate to the sodium carboxymethyl cellulose aqueous solution, and disperse using a homogenizer for 5 minutes to obtain mixed solution A;

[0112] (2) 50 mL of 2 wt% gelatin aqueous solution was prepared, heated and stirred at 45°C until completely dissolved, then the gelatin aqueous solution was mixed with the mixed solution B, continued to be stirred at 45°C, and the pH of the solution was adjusted to 4.1 within 30 minutes, then the stirring was continued for 120 minutes to obtain the mixed solution B;

[0113] (3) After the reaction was completed, the mixed solution B obtained in step (2) was placed in an ice water bath, and 2 g of hydroxyethyl cellulose was added for crosslinking and solidification reaction for 10 h to obtain the material C;

[0114] (4) The material C was washed with acetone solution, and then freeze-dried at -60°C for 12 h to obtain the capsule type metal catalyst. The Ru loading of the catalyst was 0.49 wt% by ICP test.

[0115] Example 13

[0116] Compared with Example 1, the difference of the preparation method of the capsule type metal catalyst is only that the amounts of sodium carboxymethyl cellulose and gelatin are different. In this example, 50 mL of 3 wt% sodium carboxymethyl cellulose aqueous solution was used in step (1), and 50 mL of 1 wt% gelatin aqueous solution was used in step (2), and the rest of the conditions were the same. The Pt loading of the capsule type metal catalyst prepared was 0.48 wt%.

[0117] Example 14

[0118] Compared with Example 1, the difference of the preparation method of the capsule type metal catalyst is only that the amount of Pt metal salt is different. In this example, 0.105 g of chloroplatinic acid hexahydrate was added in the form of chloroplatinic acid hexahydrate isopropyl alcohol solution, and the rest of the conditions were the same. The Pt loading of the capsule type metal catalyst prepared was 0.04 wt%.

[0119] Example 15

[0120] Compared with Example 1, the difference of the preparation method of the capsule type metal catalyst is only that the pH of the solution in step (2) is different. In this example, after the gelatin aqueous solution was mixed with the mixed solution B, the pH of the solution was adjusted to 3.8, and the rest of the conditions were the same. The Pt loading of the capsule type metal catalyst prepared was 0.41 wt%.

[0121] Example 16

[0122] Compared with Example 1, the difference of the preparation method of the capsule type metal catalyst is only that the pH of the solution in step (2) is different. In this example, after the gelatin aqueous solution was mixed with the mixed solution B, the pH of the solution was adjusted to 4.7, and the rest of the conditions were the same. The Pt loading of the capsule type metal catalyst prepared was 0.37 wt%.

[0123] Example 17

[0124] Compared with Example 1, the difference of the preparation method of the encapsulated metal catalyst is only that the pH of the solution in step (2) is different. In this example, after mixing the gelatin aqueous solution and the mixed solution B, the pH of the solution is adjusted to 3.6, and the other conditions are the same. The Pt loading of the encapsulated metal catalyst prepared is 0.07wt%.

[0125] Example 18

[0126] Compared with Example 1, the difference of the preparation method of the encapsulated metal catalyst is only that the pH of the solution in step (2) is different. In this example, after mixing the gelatin aqueous solution and the mixed solution B, the pH of the solution is adjusted to 5.0, and the other conditions are the same. The Pt loading of the encapsulated metal catalyst prepared is 0.08wt%.

[0127] Example 19

[0128] Compared with Example 1, the difference of the preparation method of the encapsulated metal catalyst is only that the amount of the solidifying agent in step (3) is different. In this example, 1g of glycerol is added, and the other conditions are the same. The Pt loading of the encapsulated metal catalyst prepared is 0.35wt%.

[0129] Comparative Example 1

[0130] 1g of carbon nanotubes was used as a carrier and as a mass reference, and H2PtCl4 was weighed according to a loading of 1wt%, and was 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 a glass rod was used for stirring to fully mix the carrier and the solution. The impregnated catalyst precursor was aged at room temperature for 12 hours, and then was transferred into a 120°C oven for drying for 12 hours. In a pure hydrogen reduction atmosphere, the reduction was carried out at a temperature of 400°C for 4 hours to obtain a 1%Pt / CNT catalyst. The Pt loading of the catalyst was 0.96wt% as detected by ICP.

[0131] Comparative Example 2

[0132] 100mL of a 0.4mol / L Na2CO3 aqueous solution was added to a three-necked flask, and then four metal salts H2PtCl4, Mg(NO3)2·6H2O and Al(NO3)3·9H2O were dissolved in 100mL of ultrapure water (referred to as solution E). In the ternary metal salt solution, the content of Pt was 1wt%, and the contents of Mg 2+ :Al 3+The molar ratio of the two solutions was 3:1. At the same time, 250 mL of a 0.4 mol / L NaOH solution (referred to as solution F) was prepared. During the mixing process, the temperature was maintained at 65°C, the pH of the solution was maintained at 10±0.5, and solutions E and F were simultaneously slowly added to the three-necked flask while stirring vigorously. After the addition was completed, the temperature of the reaction solution was maintained at 65°C for 16 hours, and then the solution was filtered and washed with ultrapure water several times until the pH of the washing liquid was 7. Finally, the sample was dried at 100°C in still air for 12 hours, and then immersed in a 2 mol / L Na2CO3 solution at room temperature for 16 hours under stirring conditions. Subsequently, the sample obtained after filtration and drying was reduced at 850°C under pure hydrogen for 4 hours to obtain a Pt-LDH catalyst, and the Pt loading of the catalyst was 0.98 wt% as detected by ICP.

[0133] Example 20

[0134] Evaluation of catalyst performance

[0135] 30 mg of the catalyst prepared in Examples 1-19 and Comparative Examples 1-2 above and 3.5 mol of trimethoxysilane were added to a reaction kettle, the reaction kettle was closed, and air was purged with argon for several times. When the reaction temperature was stable at the set value, ethylene was charged into the reaction kettle, at which time stirring was started and timing was initiated. The stirring rate was 800 rpm, and after the reaction was carried out at a reaction temperature of 30-50°C and a pressure of 0.3-0.5 MPa for 18 hours, sampling was performed, and the sample was immediately analyzed by gas chromatography.

[0136] It should be noted that the product after the reaction was analyzed by Agilent 6890N gas chromatography, the chromatographic column used was HP-50 (15 m x 320 um x 0.25 um), the carrier gas was nitrogen, and the detector was a flame ionization detector.

[0137] The conversion of trimethoxysilane and the selectivity and yield of ethyltrimethoxysilane were tested for the catalysts prepared in Examples 1-19 and the Pt / CNT and Pt-LDH catalysts to evaluate the catalytic performance of the catalysts of the present application for the hydrosilylation reaction of ethylene and trimethoxysilane to prepare ethyltrimethoxysilane.

[0138] In the hydrosilylation reaction of ethylene and trimethoxysilane, the conversion of trimethoxysilane and the selectivity and yield of ethyltrimethoxysilane were calculated according to the following formula:

[0139] 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 x 100%

[0140] S i(%) = (n 组分i x A i ) / n 初始三甲氧基硅烷 x 100%

[0141] Y i (%) = X x S i x 100%

[0142] wherein X represents the conversion rate of trimethoxysilane, in %;

[0143] n 初始三甲氧基硅烷 , n 反应后三甲氧基硅烷 represent the amount of substance of trimethoxysilane before and after the reaction, respectively, in mol;

[0144] S i represents the selectivity of component i, in %;

[0145] n 组分i represents the amount of substance of component i after the reaction, in mol;

[0146] A i represents the number of carbon atoms contained in the molecule of component i;

[0147] Y i represents the yield of component i, in %.

[0148] Table 1 Evaluation results of ethylene and trimethoxysilane hydrosilylation reaction of encapsulated metal catalyst

[0149]

[0150]

[0151] Since the silicon-hydrogen addition reaction will produce side reactions in the process of heating, the capsule catalyst wall material to be prepared should be able to break in the reaction temperature range to quickly release the active component. Table 1 shows that the results of Example 1 are better than Examples 15-18, which is mainly because the combination of gelatin and carboxymethyl cellulose requires a specific pH value, and beyond this range, it is not easy to form capsules, which makes it difficult to load active metals, thereby affecting the catalytic performance. Compared with Example 1 and Example 13, Example 1 performs better, which is related to the optimal ratio of gelatin and carboxymethyl cellulose. Different ratios will cause differences in the mechanical properties of the capsule wall material, thereby affecting the process of releasing the catalytic activity. Compared with Example 1 and Example 19, the results of Example 1 are also better, because the amount of curing agent is less, and it is more difficult to form stable microcapsule catalysts, and too much amount may cause the catalyst to adhere, making it difficult to separate during freeze-drying. The capsule metal catalyst prepared by Example 1 in the catalytic ethylene and trimethoxysilane silicon-hydrogen addition reaction, the conversion rate of trimethoxysilane is more than 95%, and the selectivity of ethyl trimethoxysilane is greater than 92%, which is significantly better than Pt / CNT and Pt-LDH catalysts.

[0152] The above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent transformation or modification made according to the spirit and essence of the present application should be covered within the protection scope of the present application.

Claims

1. A process for the preparation of an encapsulated metal catalyst for the production of ethyltrimethoxysilane by the hydrosilylation of ethylene and trimethoxysilane, characterized in that, It comprises the following steps: (1) preparing a sodium carboxymethyl cellulose aqueous solution with a certain concentration, then adding an additive and a metal salt solution into the sodium carboxymethyl cellulose aqueous solution, and obtaining a mixed solution A after uniform dispersion; the additive is selected from one or more of nano-sized silicon dioxide and nano-sized titanium dioxide, and the mass of the additive is 0.006-0.2 times the mass of the metal salt; the metal salt solution is selected from one of Pt, Pd or Ru metal salt alcohol solutions; (2) preparing a gelatin solution with a certain concentration, mixing the gelatin solution and the mixed solution A uniformly, adjusting the pH of the solution to be acidic, and then continuing the reaction to obtain a mixed solution B; the pH is 3.8-4.7, the reaction temperature is 40-60℃, and the reaction time is 0.5h-3.0h; (3) placing the mixed solution B obtained in step (2) in an ice water bath, and adding a solidifying agent to perform a cross-linking solidification reaction to obtain a material C; the solidifying agent is selected from at least one of glycerol and hydroxyethyl cellulose, and the addition amount of the solidifying agent is 1.0-6.0 times the total mass of the sodium carboxymethyl cellulose and the gelatin; (4) washing and drying the material C to obtain the capsule type metal catalyst; the mass ratio of the sodium carboxymethyl cellulose and the gelatin is 0.75-2.0, the addition amount of the metal salt is 0.2-1.5 times the total mass of the sodium carboxymethyl cellulose and the gelatin, the loading amount of the metal in the capsule type metal catalyst prepared is 0.1-1.5wt%, and the reaction conditions of the silicon-hydrogen addition reaction are: temperature 30-60℃, pressure: 0.25-0.5MPa.

2. The method of claim 1, wherein the capsule type metal catalyst is prepared by the steps of: In step (1), 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 dichlorotetrakisamine platinum; and the metal salt of Ru is selected from at least one of ruthenium chloride, ruthenium nitrate or chlorohexamine ruthenium.

3. The method of claim 1, wherein the metal catalyst is prepared in the form of a capsule. In step (3), the time of the cross-linking solidification reaction is 4-10h.

4. The method of claim 1, wherein the capsule-type metal catalyst is prepared by the steps of: In step (4), the solvent for washing is selected from ethanol or acetone.

5. The encapsulated metal catalyst produced according to the method of any one of claims 1 to 4, wherein the encapsulated metal catalyst is characterized by: The loading amount of the metal is 0.1-1.5wt%.

6. Use of a capsule metal catalyst according to claim 5, characterized in that, The silicon-hydrogen addition reaction is used for preparing ethyl trimethoxysilane from ethylene and trimethoxysilane, and the reaction conditions of the silicon-hydrogen addition reaction are: temperature 30-60℃, pressure: 0.25-0.5MPa.

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