Zero-valent nickel catalyst, its preparation method and application

Abstract

The application discloses a zero-valent nickel catalyst and a preparation method and application thereof, and belongs to the field of catalysts. The zero-valent nickel catalyst comprises zero-valent nickel particles, a stable layer coated on the outer surface of the zero-valent nickel particles, and a protective layer coated on the outer surface of the stable layer. The stable layer comprises any one or both of a reducing metal and a zero-valent nickel reducing agent, and the protective layer comprises any one or more of carbon materials, inorganic oxides and organic materials. The catalyst has the advantages of structural stability in air, high catalytic activity, long service life and good application value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts for promoting the dechlorination of silicon compounds, in particular to a zero-valent nickel catalyst, a preparation method and application thereof. BACKGROUND

[0002] The dechlorination of silicon compounds is an important reaction that can convert chlorinated silicon compounds into corresponding dechlorinated products, which can be used to prepare silicon compounds with specific functions and can reduce or avoid the generation of toxic chlorides, thus being more environmentally friendly. The dechlorination of silicon compounds is widely used in organic synthetic chemistry, materials science and pharmaceutical fields, and has important significance in the field of semiconductors and chip materials. In the semiconductor industry, the dechlorination of silicon compounds can be used to remove impurities in silicon compounds, improve the purity and crystal quality of silicon materials, and thus provide high-purity raw materials for chip manufacturing.

[0003] There are various catalysts for promoting the dechlorination of silicon-based compounds, including noble metal catalysts (such as palladium and platinum), transition metal catalysts (such as nickel, iron and cobalt), and organic catalysts. Among them, zero-valent nickel catalysts have the advantages of easy access to raw materials, low cost, high catalytic activity, and easy adjustment of structure and properties, but the service life of zero-valent nickel catalysts is short and the stability is poor, and it is easy to be deactivated due to oxidation and other factors.

[0004] Chinese patent application with publication number CN117384210A uses a divalent nickel complex compound containing phosphine ligand P(R3)3 mixed with halogenated hydrocarbyl magnesium compound to prepare zero-valent nickel complex compound, wherein R3 is selected from alkyl, cycloalkyl, alkenyl, cycloalkenyl, heterocyclic group, aryl and heteroaryl. The complex compound can replace noble metal catalysts to catalyze silicon hydrogen addition reaction, and has high catalytic activity and product selectivity, but the effective structure of the catalyst is not protected.

[0005] Chinese patent application with publication number CN108854951A uses woody biomass to adsorb water-soluble iron salt and nickel salt, and uses pyrolysis gas as a reducing agent to reduce iron and nickel ions to zero-valent, thereby synthesizing a biochar nano zero-valent iron-nickel composite. The composite has low manufacturing cost, strong adsorption performance and reduction degradation capacity, and obvious adsorption passivation effect on heavy metals, and can be used for environmental purification, but air and water can destroy the valence state of iron and nickel. SUMMARY

[0006] The main purpose of the present application is to provide a zero-valent nickel catalyst and a preparation method thereof, which can efficiently catalyze the dechlorination of silicon compounds.

[0007] The present application also provides a zero-valent nickel catalyst for use in catalyzing the dechlorination of silicon compounds.

[0008] In order to achieve the above object, according to one aspect of the present application, a zero-valent nickel catalyst is provided, comprising zero-valent nickel particles, a stabilizing layer coated on the outer surface of the zero-valent nickel particles, and a protective layer coated on the outer surface of the stabilizing layer.

[0009] The stabilizing layer comprises any one or both of a reducing metal and a zero-valent nickel reducing agent, and the protective layer comprises any one or more of carbon material, inorganic oxide, organic material, etc.

[0010] The stabilizing layer is composed of a zero-valent nickel reducing agent with strong reducing property, which can avoid deactivation of the zero-valent nickel during preparation and use; the zero-valent nickel reducing agent refers to a reducing agent capable of reducing a nickel-containing salt into zero-valent nickel. The protective layer has stable structure and porous structure, which can maintain the activity and structure of the catalyst.

[0011] In one preferred embodiment, the stabilizing layer comprises any one or both of borohydride, zinc and manganese.

[0012] In one preferred embodiment, the protective layer comprises any one or more of activated carbon, SiO2, Al2O3, polysaccharide and cellulose; preferably, the protective layer is activated carbon, and the thickness of the protective layer is 0.5-20 nm, preferably 2-10 nm.

[0013] In one preferred embodiment, the particle size of the zero-valent nickel particles is 1-100 nm, preferably 5-50 nm.

[0014] The present application also provides a preparation method of the zero-valent nickel catalyst, comprising the following steps:

[0015] S1, preparing zero-valent nickel particles;

[0016] S2, immersing the zero-valent nickel particles in S1 in a solution containing a nickel valence state stabilizer, filtering and drying to obtain zero-valent nickel particles coated with a stabilizing layer, the nickel valence state stabilizer being any one or more of a reducing metal and a zero-valent nickel reducing agent;

[0017] S3, coating a protective agent on the surface of the zero-valent nickel particles coated with the stabilizing layer in S2 and drying, wherein the protective agent is any one or more of carbon material, inorganic oxide and organic material.

[0018] The catalyst prepared by the present application has a core-shell structure of "zero-valent nickel particles-stabilizing layer-protective layer", and can be used to promote the dechlorination reaction of silicon-based compounds.

[0019] In one preferred embodiment, the coating method of the protective agent in S3 is any one or more of immersion, coating and adsorption; preferably, the coating method of the protective agent in S3 is immersion, and the zero-valent nickel particles coated with the stabilizing layer in S2 are immersed in a solvent containing the protective agent.

[0020] The impregnation makes the protective layer coat more uniformly, and the catalyst prepared has higher catalytic efficiency.

[0021] In one preferred embodiment, the impregnation times, temperature and time in S3 are 1-10 times, 10-90℃, 2-48h, preferably 2-5 times, 40-80℃, 6-14h.

[0022] The impregnation parameters above can ensure that the catalyst prepared has higher activity.

[0023] In one preferred embodiment, the preparation method of the zero-valent nickel particles in S1 is to add a zero-valent nickel reducing agent into a solution containing a nickel-containing salt and a surfactant, and then separate the zero-valent nickel particles from the solution, and then wash and dry them.

[0024] The zero-valent nickel particles can effectively avoid excessive agglomeration and oxidation in air or water under the action of the surfactant, thereby increasing the activity of the catalyst prepared.

[0025] In one preferred embodiment, the surfactant is any one or more of an acid, ascorbic acid and oleic acid.

[0026] Further, in the preparation method of the zero-valent nickel particles in S1, the stirring temperature and time are 5-80℃ and 0.1-24h, preferably 15-35℃ and 0.2-2h.

[0027] Further, the nickel-containing salt in S1 is any one or more of nickel chloride, nickel sulfate, nickel nitrate, nickel bromide, etc., preferably with a concentration of 0.1-2000g / L, more preferably 10-1500g / L, and further preferably 10-500g / L.

[0028] Further, the concentration of the surfactant in S1 is 5-15g / L. The solution is a DMF solution, and an ethanol solution is used for washing.

[0029] Further, the zero-valent nickel reducing agent in S1 is preferably sodium borohydride, and the mass concentration of the sodium borohydride is 30-70g / L.

[0030] Further, the drying temperature, atmosphere and time are 100-300℃, an inert atmosphere and 0.5-6h, preferably 100-150℃, N2 atmosphere and 1-3h.

[0031] Further, the solvent in S2 is any one or more of water, ethanol, N-methyl pyrrolidone (NMP), N,N-dimethylformamide (DMF), etc.

[0032] Further, the dipping times, temperature and time in S2 are 1-10 times, 10-90℃, preferably 2-5 times, 40-80℃, respectively.

[0033] Further, the molar mass of the nickel valence state stabilizer in S2 is 0.5-10 times, preferably 1-5 times, the molar mass of the zero-valent nickel particles.

[0034] Further, the protective agent in S3 is one or more of activated carbon, SiO2, Al2O3, polysaccharide, cellulose. Preferably, the catalyst is dipped in a solvent comprising activated carbon in S3, the concentration of activated carbon is 80-120g / L, and the solvent is ethanol.

[0035] Further, the silicon compound has the structure of SiR1R2R3Cl, wherein R1, R2 and R3 are independently selected from hydrogen radical, halogen radical, organic radical and the like.

[0036] The application also provides the use of the zero-valent nickel catalyst in catalyzing the dechlorination reaction of silicon compounds.

[0037] Compared with the prior art, the application has at least the following beneficial effects:

[0038] The application provides a zero-valent nickel catalyst and a preparation method thereof. The catalyst can be used to promote the dechlorination of silicon compounds. Compared with the prior art, the catalyst of the application has a core-shell structure of "zero-valent nickel particles-stabilizing layer-protective layer". The zero-valent nickel particles can effectively avoid excessive aggregation and oxidation in air or water under the action of a surfactant; the stabilizing layer is composed of a nickel valence state stabilizer with strong reducing property, which can avoid the deactivation of zero-valent nickel during preparation and use; and the protective layer has a stable structure and a porous structure, which can maintain the activity and structure of the catalyst. Therefore, the catalyst involved in the application can maintain structural stability in air, has high catalytic activity, long service life and good application value. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The yield of the dechlorination reaction of brominated benzene and monochlorosilane to generate phenylsilane catalyzed by the catalysts in Examples 1-17 and Comparative Examples 1-4. DETAILED DESCRIPTION

[0040] The technical solutions of the application will be further described in detail below through specific examples. It should be understood that the implementation of the application is not limited to the following examples, and any form of modification and / or change of the application will fall within the scope of the application.

[0041] In the application, all the parts and percentages are weight units, and all the devices and raw materials can be purchased from the market or commonly used in the industry, unless otherwise specified.

[0042] Example 1

[0043] At 25°C, 10 g of sodium borohydride was slowly added to a 200 mL DMF solution containing 18 g of nickel nitrate and 2.5 g of ascorbic acid, and stirred vigorously for 1 h. Zero-valent nickel particles were separated from the solution, washed with an ethanol solution, and then dried at 120°C under N2atmosphere for 2 h. Next, the zero-valent nickel particles were immersed in a 200 mL DMF solution containing 5 g of sodium borohydride at 60°C for 3 times, and then dried at 120°C under N2atmosphere for 2 h to form a stable layer on the particles. Then, the zero-valent nickel particles were immersed in a 100 mL ethanol suspension containing 10 g of activated carbon powder at 60°C for 10 h, and the immersion was repeated 3 times to form a protective layer on the particles, and then dried at 120°C under N2atmosphere for 2 h to obtain a stable catalyst containing a core-shell structure of "zero-valent nickel particles-stable layer-protective layer". Finally, bromobenzene was reacted with monochlorosilane under the action of the catalyst at 40°C under N2atmosphere for 2 h, and the same catalyst was repeatedly used for the reaction 10 times. The components of the product after 10 reactions were analyzed by liquid chromatography.

[0044] Example 2

[0045] The difference from Example 1 is that the mass of nickel nitrate is 2 g.

[0046] Example 3

[0047] The difference from Example 1 is that the mass of nickel nitrate is 100 g.

[0048] Example 4

[0049] The difference from Example 1 is that no surfactant ascorbic acid is added.

[0050] Example 5

[0051] The difference from Example 1 is that the addition method of the zero-valent nickel reducing agent is changed from slowly adding 10 g of sodium borohydride to slowly passing 5 g of NH3gas.

[0052] Example 6

[0053] The difference from Example 1 is that the nickel valence state stabilizer is changed from 5 g of sodium borohydride to 8 g of manganese powder.

[0054] Example 7

[0055] The difference from Example 1 is that the nickel valence state stabilizer is changed from 5 g of sodium borohydride to 10 g of zinc powder.

[0056] Example 8

[0057] The difference from Example 1 is that the method of coating the protective layer is changed to coating the zero-valent nickel particles with a 100 mL ethanol suspension containing 10 g of activated carbon powder 3 times.

[0058] Example 9

[0059] The difference from Example 1 is that the method of coating the protective layer is changed to adsorbing the zero-valent nickel particles in 10 g of activated carbon powder 3 times.

[0060] Example 10

[0061] The difference from Example 1 is that the protective layer is nano-silica.

[0062] Example 11

[0063] The difference from Example 1 is that the protective layer is ethyl cellulose.

[0064] Example 12

[0065] The difference from Example 1 is that the protective layer is nano-Al2O3.

[0066] Example 13

[0067] The difference from Example 1 is that the protective layer is glucose.

[0068] Example 14

[0069] The difference from Example 1 is that the number of times of impregnating the protective layer is 1.

[0070] Example 15

[0071] The difference from Example 1 is that the number of times of impregnating the protective layer is 10.

[0072] Example 16

[0073] The difference from Example 1 is that the impregnation time of the protective layer is 2 h.

[0074] Example 17

[0075] The difference from Example 1 is that the impregnation time of the protective layer is 48 h.

[0076] Comparative Example 1

[0077] The difference from Example 1 is that, in the preparation of the zero-valent nickel particles, the zero-valent nickel particles are not washed after being separated from the solution, and no stabilizing layer is coated.

[0078] Comparative Example 2

[0079] The difference from Example 1 is that anhydrous nickel nitrate is used as the catalyst.

[0080] Comparative Example 3

[0081] The difference from Example 1 is that a commercial zero-valent nickel compound Ni(cod)2is used as the catalyst, which has the following chemical structure.

[0082]

[0083] Comparative Example 4

[0084] The difference from Example 1 is that a bis(tri-n-butylphosphine)nickel(0) complex is used as the catalyst, which has the following chemical structure.

[0085]

[0086] The yield of phenylsilane generated by the dechlorination reaction of bromobenzene with monochlorosilane in the above examples is detected by liquid chromatography, and the yield of phenylsilane is used as the performance index of the catalyst for comparison. The yield of the reaction product of Examples 1-17 and Comparative Examples 1-4 is compared as shown in Table 1. Figure 1

[0087] ​From the reaction product yield, the catalyst stability of the examples is better than that of the comparative examples, so the "zero-valent nickel particle-stable layer-protective layer" core-shell structure provided by the present application can effectively maintain catalyst activity and prolong service life. Among them, the catalyst activity of examples 1, 3 and 17 is higher and the yield within 10 times of reaction is close, but example 3 uses more nickel nitrate, which will cause waste, and example 17 has a longer impregnation time, which is not conducive to the efficient preparation of the catalyst, so the preparation conditions in example 1 are more appropriate. By comparing comparative examples 1 and 4, it is found that the yield corresponding to the catalyst without surfactant is only about 62 mol%, because the lack of surfactant will cause the agglomeration of zero-valent nickel particles, affecting the catalyst activity. By comparing comparative examples 1 and 5, it is found that the yield corresponding to the catalyst prepared by using NH3 gas as a zero-valent nickel reducing agent is only about 71 mol%, because NH3 is volatile and generates a weak base, and the reduction effect is not as good as sodium borohydride. By comparing comparative examples 1, 6 and 7, it is found that the yield corresponding to the catalyst prepared by using manganese or zinc as a nickel valence state stabilizer is lower than that of sodium borohydride, and sodium borohydride has stronger protection ability for the valence state of zero-valent nickel. By comparing comparative examples 1, 8 and 9, it is found that the impregnation method is better among the methods of coating the protective layer, because impregnation makes the protective layer coating more uniform, and coating leads to a too thick and uneven protective layer, and adsorption can cause the protective layer to be not firmly coated. By comparing comparative examples 1 and 10-13, it is found that the protective layer of activated carbon is better, because activated carbon has a well-developed pore structure, good adsorbability and high specific surface area, so the prepared catalyst has higher activity. By comparing comparative examples 1, 14 and 15, it is found that too few or too many impregnation times for preparing the protective layer will affect the catalyst activity. By comparing comparative examples 1, 16 and 17, it is found that the longer the impregnation time, the better the preparation effect of the protective layer, but considering that the preparation time will also increase the catalyst preparation cost, so the impregnation time is preferably controlled within the range of 6-14 h.

[0088] It should be noted that in this application, activated carbon as a protective layer is different from the role of activated carbon as a catalyst carrier or matrix in other inventions, and the role of activated carbon as a protective layer is mainly to protect the catalytic activity of zero-valent nickel valence state.

[0089] The applicant declares that the above examples illustrate the detailed method features of the present application, but the present application is not limited to the above detailed method features, i.e. it does not mean that the present application must rely on the above detailed method features to be implemented. It should be understood by those skilled in the art that any improvement on the present application, equivalent replacement of the components selected by the present application, addition of auxiliary components, selection of specific methods, etc. all fall within the protection scope and disclosure scope of the present application.

[0090] It should be further noted that the various technical features described in the above detailed description can be combined in any suitable manner without departing from the scope of the application. To avoid not necessary repetition regarding various combinations, no further combinations will be described.

[0091] Moreover, the various embodiments described herein can be combined in any suitable manner, as long as such combinations do not depart from the scope of the present application.

Claims

1. A zero-valent nickel catalyst characterized in that, It includes zero-valent nickel particles, a stabilizing layer covering the outer surface of the zero-valent nickel particles, and a protective layer covering the outer surface of the stabilizing layer; The stabilizing layer includes any one or two of borohydride, zinc, and manganese; The protective layer includes any one or more of activated carbon, SiO2, Al2O3, polysaccharides, and cellulose.

2. The zero-valent nickel catalyst according to claim 1, characterized in that, The protective layer is activated carbon, and the thickness of the protective layer is 0.5~20 nm.

3. The zero-valent nickel catalyst of claim 2, wherein, The thickness of the protective layer is 2~10 nm.

4. The zero-valent nickel catalyst of claim 1, wherein, The particle size of zero-valent nickel particles ranges from 1 to 100 nm.

5. The zero-valent nickel catalyst of claim 4, wherein the zero-valent nickel catalyst is characterized by, The particle size of zero-valent nickel particles is 5~50 nm.

6. A method for producing the zero-valent nickel catalyst according to any one of claims 1 to 5, characterized by Includes the following steps: S1. Prepare zero-valent nickel granules; S2. The zero-valent nickel particles from S1 are immersed in a solution containing a nickel valence stabilizer, filtered, and dried to obtain zero-valent nickel particles coated with a stabilizing layer. The nickel valence stabilizer is any one or more of a reducing metal and a zero-valent nickel reducing agent. S3. Coat the surface of the zero-valent nickel particles coated with the stabilizing layer in S2 with a protective agent and dry them to obtain the product; the protective agent can be any one or more of carbon materials, inorganic oxides, and organic materials.

7. The method for preparing the zero-valent nickel catalyst according to claim 6, characterized in that, The protective agent in S3 can be coated by any one or more of the following methods: impregnation, coating, and adsorption.

8. The method of claim 7, wherein the zero-valent nickel catalyst is prepared by, The protective agent in S3 is applied by immersion, in which the zero-valent nickel particles coated with the stabilizing layer in S2 are immersed in a solvent containing the protective agent.

9. The method of claim 8, wherein the zero-valent nickel catalyst is prepared by, The number of immersions, temperature, and time in S3 are 1~10 times, 10~90 ℃, and 2~48 h, respectively.

10. The method for preparing the zero-valent nickel catalyst according to claim 9, characterized in that, The number of immersions, temperature, and time in S3 are 2-5 times, 40-80 ℃, and 6-14 h, respectively.

11. The method for preparing the zero-valent nickel catalyst according to claim 6, characterized in that, The preparation method of zero-valent nickel particles in S1 is to add a zero-valent nickel reducing agent to a solution containing nickel salt and surfactant and stir vigorously, then separate the zero-valent nickel particles from the solution, wash and dry them.

12. The method for preparing the zero-valent nickel catalyst according to claim 11, characterized in that, The surfactant is any one or both of ascorbic acid and oleic acid.

13. The use of a zero-valent nickel catalyst according to any one of claims 1-5 or a zero-valent nickel catalyst prepared by the preparation method according to any one of claims 6-12 in the catalytic dechlorination reaction of silicon compounds.

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