Copper catalyst for organosilicon monomer synthesis reaction and its preparation method

Abstract

This invention discloses a method for preparing a copper catalyst for the synthesis of organosilicon monomers. Copper and zinc are smelted and atomized to obtain powder A; copper oxide powder is incompletely calcined to obtain powder B; powder A and powder B are mixed and reacted at 450–600°C; after the reaction, the resulting material is ball-milled and sieved to obtain the copper catalyst. The catalyst prepared by this method can effectively form an active catalyst with silicon powder in the synthesis of organosilicon monomers, enabling the synthesis reaction to maintain high reactivity over a long period. It reduces the formation of side reactions such as high-boiling-point substances and improves the selectivity for dimethyldichlorosilane. Simultaneously, the catalyst has a longer service life, effectively reducing production costs and improving economic efficiency.

Description

Technical Field

[0001] This application relates to the field of catalyst technology, specifically to a copper catalyst for the synthesis of organosilicon monomers and its preparation method. Background Technology

[0002] Organosilicon refers to compounds containing Si-C bonds, with at least one organic group directly bonded to a silicon atom. Conventionally, compounds in which organic groups are bonded to silicon atoms via oxygen, sulfur, nitrogen, or other means are also considered organosilicon compounds. Due to their unique structure, organosilicon combines the properties of both inorganic and organic materials.

[0003] Organosilicon monomer synthesis is an important research area in organic chemistry, referring to the process of synthesizing organosilicon compounds through chemical reactions. The synthesis of organosilicon monomers has evolved through methods such as organometallic compound methods, hydrosilylation addition methods, redistribution methods, thermal condensation methods, and direct synthesis methods. Because the direct method is the simplest and does not require solvents, it is the lowest cost and was ultimately chosen for industrial production. The so-called direct synthesis method uses chloromethane and industrial silicon powder to synthesize organosilicon monomers (dimethyldichlorosilane) in the presence of a catalyst. However, due to the varying effects of material structure and reaction conditions on different atoms in organic reactions, numerous side reactions occur during the direct synthesis of organosilicon monomers.

[0004] Copper-based catalysts are classic catalysts for the direct synthesis of methylchlorosilanes. Initially, electrolytic copper powder was used industrially, but its small specific surface area resulted in poor catalytic activity. Later-developed cuprous chloride catalysts also suffered from poor stability and were gradually phased out. Currently, the most widely used ternary copper catalyst is Cu-Cu₂O-CuO. This catalyst, first proposed by SCM in the US, is prepared using a two-step method involving air oxidation and high-energy ball milling of copper powder. Its performance is superior to conventional copper powder catalysts. However, during high-temperature oxidation, the raw copper powder is prone to caking and uneven oxidation, making the oxidation process difficult to operate and control. Furthermore, this catalyst is prone to agglomeration and sintering during monomer synthesis reactions, further severely impacting its lifespan.

[0005] Therefore, developing a highly selective catalyst suitable for the synthesis of organosilicon monomers and improving the catalyst lifetime is a worthy research topic. Summary of the Invention

[0006] Purpose of the invention: To address the shortcomings of the prior art, this application provides a copper catalyst for the synthesis of organosilicon monomers and its preparation method.

[0007] Technical solution: The preparation method of the copper catalyst for the synthesis reaction of organosilicon monomers according to the present invention includes the following steps:

[0008] Pure copper and pure zinc are selected and alloyed at a ratio of 100:0.5 to form a copper-zinc molten metal. The molten metal is then atomized by high-pressure air jet. After the molten metal solidifies and settles, powder A is obtained.

[0009] Copper oxide powder was partially calcined to obtain powder B; powder A and powder B were mixed and placed in a reaction furnace, nitrogen gas was introduced and the mixture was heated to 450-600°C. Heating was stopped after 4-8 hours and the mixture was cooled to room temperature.

[0010] The obtained material and grinding balls were sealed in a ball mill jar and ball milled. The ball milling conditions were: a ball-to-material ratio of 1:1, a ball milling speed of 40-50 rpm, and a ball milling time of 20-30 min. The material was then passed through a 100-mesh sieve to obtain the copper catalyst.

[0011] Specifically, powder A is Cu-0.5Zn master alloy powder.

[0012] Specifically, the incomplete calcination involves placing copper oxide powder into a calcining vessel, spreading it to a thickness of 20 mm, and calcining it. The temperature is then increased to 700-900℃ and held for 1-4 hours, followed by cooling to room temperature to obtain powder B. Powder B is primarily a mixture of copper oxide and cuprous oxide.

[0013] Specifically, the roasting process is as follows: from room temperature to 500℃ for 2 hours, hold at 500℃ for 0.5 hours, raise to 700℃ for 1 hour, hold at 700℃ for 1 hour, raise to 900℃ for 2 hours, hold at 900℃ for 1 hour, and then cool to room temperature.

[0014] Specifically, powder A and powder B are mixed in a mass ratio of 20:80.

[0015] Specifically, the nitrogen gas flow rate is 300-600 ml / h, and the heating temperature is 450-600℃. In the reactor, cuprous oxide decomposes and releases active oxygen. The oxygen dissolves into the metallographic phase and diffuses into the alloy phase. The more reactive components in the alloy react with the oxygen. Since zinc is more likely to form oxides than copper, zinc is preferentially oxidized to zinc oxide. In the reactor, if the oxygen partial pressure of the medium equals the maximum oxygen partial pressure required for oxidation and is maintained in a natural matching relationship with the temperature, the oxygen supply capacity of cuprous oxide can be maximized, shortening the zinc oxide formation time. Therefore, the optimal conditions are a nitrogen gas flow rate of 600 ml / h and a reaction temperature of 500℃.

[0016] Specifically, the ball-to-material ratio is 1:1, the ball milling speed is 40 rpm, and the ball milling time is 20 min.

[0017] The present invention also provides a catalyst, which is the catalyst obtained by the above preparation method, and the catalyst contains copper, copper oxide, cuprous oxide, and dispersed zinc oxide. In the final catalyst, the zinc oxide content is controlled to be 0.9-1%, the copper content is greater than or equal to 19.9%, and the copper oxide content is less than or equal to 79.9%.

[0018] This invention also provides the application of the above-mentioned catalyst. Specifically, the reaction conditions for the synthesis of organosilicon monomers are: pressure 0.15 MPa, temperature 300℃. The amount of catalyst used is 8-10% of the mass of silicon powder.

[0019] Beneficial effects: In the preparation process, this invention solves the problems of easy caking of copper powder in high-temperature oxidation and uneven distribution of various components. The method described in this invention can obtain a uniform mixed powder of copper oxide, cuprous oxide and copper, and form a dispersed zinc oxide. The resulting catalyst can effectively avoid catalyst aggregation and sintering in the synthesis reaction of organosilicon monomers, and improve the service life of the catalyst.

[0020] In the prior art, copper powder catalysts have a relatively dense surface and a small specific surface area. Compared with the prior art, the catalyst prepared by the method described in this invention has a porous surface and a larger specific surface area, which can promote the formation of the induced phase in the early stage of the reaction, shorten the reaction induction period, and has the advantages of fast catalytic reaction start-up, high reaction activity and selectivity. Attached Figure Description

[0021] Figure 1 The image shows the SEM microstructure (20 μm) of the catalyst obtained in Example 1.

[0022] Figure 2 The image shows the SEM microstructure (10 μm) of the catalyst obtained in Example 1.

[0023] Figure 3 The image shows the SEM microstructure (5 μm) of the catalyst obtained in Example 1.

[0024] Figure 4 The image shows the SEM microstructure (20 μm) of the catalyst obtained in Comparative Example 2. Detailed Implementation

[0025] The technical solution of this application will be described in detail below through embodiments, but the protection scope of this application is not limited to the embodiments described.

[0026] Example 1

[0027] Pure copper and pure zinc are selected and smelted into an alloy with a copper-zinc ratio of 100:0.5 to form a copper-zinc molten metal. The molten metal is then atomized by high-pressure air jet. After the molten metal solidifies and settles, powder A is obtained.

[0028] Copper oxide powder was placed in a calcining vessel, with a powder thickness of 20 mm, and calcined according to the following procedure: from room temperature to 500℃ for 2 hours, held at 500℃ for 0.5 hours, increased to 700℃ for 1 hour, held at 700℃ for 1 hour, increased to 900℃ for 2 hours, and held at 900℃ for 1 hour. Then it was cooled to room temperature to obtain powder B.

[0029] Powder A and powder B were loaded into a double cone mixer and mixed for 2 hours. The mass ratio of powder A to powder B was 20:80. The resulting mixed powder was placed in a reactor, nitrogen gas was introduced and heated at a rate of 600 ml / h and a heating temperature of 500°C. Heating was stopped after 4 hours and the mixture was cooled to room temperature.

[0030] The obtained material was sealed with grinding balls in a ball mill jar and ball-milled under the following conditions: a ball-to-material ratio of 1:1, a milling speed of 40 rpm, and a milling time of 20 min. The mixture was then passed through a 100-mesh sieve to obtain the copper catalyst. The specific surface area of ​​the catalyst, measured according to GB / T13390-2008 standard, was 2.8 m². 2 / g. The SEM image of the obtained catalyst is shown below. Figures 1-3 As shown, the catalyst has a special morphology with many pores and a large specific surface area, which increases the contact area between the catalyst and the silicon powder and improves the catalytic activity of the catalyst.

[0031] Comparative Example 1

[0032] Pure copper and pure zinc are selected and smelted into an alloy with a copper-zinc ratio of 100:0.5 to form a copper-zinc molten metal. The molten metal is then atomized by high-pressure air jet. After the molten metal solidifies and settles, powder A is obtained.

[0033] Powder A and copper oxide powder were mixed in a double cone mixer for 2 hours. The mass ratio of powder A to copper oxide powder was 20:80. The resulting mixed powder was placed in a reactor, nitrogen gas was introduced and heated at a rate of 600 ml / h and a heating temperature of 450°C. Heating was stopped after 4 hours and the mixture was cooled to room temperature.

[0034] The obtained material and grinding balls were sealed in a ball mill jar and ball milled under the following conditions: ball-to-material ratio of 1:1, ball milling speed of 40 rpm, and ball milling time of 20 min. The material was then passed through a 100-mesh sieve to obtain the copper catalyst.

[0035] Comparative Example 2

[0036] Pure copper and pure zinc are selected and smelted into an alloy with a copper-zinc ratio of 100:0.5 to form a copper-zinc molten metal. The molten metal is then atomized by high-pressure air jet. After the molten metal solidifies and settles, powder A is obtained.

[0037] Powder A and copper oxide powder were mixed in a double cone mixer for 2 hours. The mass ratio of powder A to copper oxide powder was 20:80. The resulting mixed powder was placed in a reactor, nitrogen gas was introduced and heated at a rate of 600 ml / h and a heating temperature of 900°C. Heating was stopped after 8 hours and the mixture was cooled to room temperature.

[0038] The obtained material was sealed with grinding balls in a ball mill jar and ball-milled under the following conditions: a ball-to-material ratio of 1:1, a ball milling speed of 40 rpm, and a ball milling time of 20 min. The mixture was then passed through a 100-mesh sieve to obtain the copper catalyst. The SEM image of the obtained catalyst is shown below. Figure 4 As shown, by comparison, it can be found that the catalyst is more dense than that of Example 1. Example 1 has more pores and a larger specific surface area, which is conducive to the full contact of reactants.

[0039] Example 3

[0040] Silicon powder is mixed with the catalyst described in this invention, with the catalyst accounting for 8-10% of the total mass of silicon powder. The mixture is then packed into a reactor to form a mixed catalyst. The reactor is a micro fixed-bed reactor (Φ20×50). A nitrogen purging system is used, with the pressure adjusted to 0.15 MPa, and then switched to MeCl gas to contact the mixed catalyst. The reaction temperature is controlled at 300°C. The products after the reaction are collected and subjected to chromatographic analysis to calculate the silicon powder conversion rate and M2 selectivity.

[0041] Silicon conversion rate = (W 反应前 -W 反应后 ) / W 反应前 *100%

[0042] M1 selectivity = W M1 / (W M1 +W M2 +W M3 )*100%

[0043] M2 selectivity = W M2 / (W M1 +W M2 +W M3 )*100%

[0044] M3 selectivity = W M3 / (W M1 +W M2 +W M3 )*100%

[0045] Wherein, M1: monomethyltrichlorosilane, M2: dimethyldichlorosilane, M3: trimethylmonochlorosilane, and W is the weight of the substance.

[0046] The results are shown in the table below.

[0047]

[0048] The experimental results show that the catalyst prepared by the method described in this invention can greatly reduce the occurrence of side reactions that generate M1 and improve the selectivity of M2.

[0049] The comparison shows that if copper oxide is not completely calcined, it cannot provide an oxygen source in the reaction after mixing, and the resulting catalyst performance is only slightly higher than that of conventional ternary copper powder catalysts. If the temperature is raised to 900℃ in the reaction after mixing, copper oxide can theoretically be decomposed, but in practice, the effect is not ideal. The reasons may be that the decomposition is too slow, resulting in a long reaction time, and the reaction temperature is too high, resulting in an irrational microstructure of the powder.

[0050] The catalyst prepared by the method described in this invention does not require the addition of zinc as a co-catalyst in the synthesis reaction of organosilicon monomers.

[0051] Example 4

[0052] The catalyst deactivation test followed the same steps as in Example 3. The reactor was a stirred bed reactor with an inner diameter of 60 mm. The pressure was increased to 0.2 MPa, and the reaction temperature was controlled at 325 °C for continuous reaction. Samples were taken and analyzed according to different reaction times, as shown in the table below.

[0053]

[0054] Example 5

[0055] The catalyst deactivation test followed the same steps as in Example 3. The reactor was a stirred bed reactor with an inner diameter of 60 mm. The pressure was increased to 0.3 MPa, and the reaction temperature was controlled at 350 °C for continuous reaction. Samples were taken and analyzed according to different reaction times, as shown in the table below.

[0056]

[0057] The deactivation test of the catalyst showed that the catalyst prepared by the method described in this invention did not exhibit a significant decrease in activity, and both its conversion rate and selectivity remained relatively stable. In contrast, conventional copper powder catalysts, while showing little change in selectivity, exhibited a decreasing trend in conversion rate.

[0058] The catalyst prepared by the method described in this invention can effectively form an active catalyst with silicon powder in the synthesis of organosilicon monomers, enabling the synthesis reaction to maintain high reactivity over a long period. It can improve the space-time yield of organosilicon monomers, achieve a high silicon powder conversion rate (above 66%), reduce the formation of high-boiling-point side reactions, increase the yield of dimethyldichlorosilane, and exhibit high M2 selectivity (above 92%). Simultaneously, the catalyst has a longer service life, effectively reducing production costs and improving economic efficiency.

[0059] The above description is merely a preferred embodiment of this application and is not intended to limit this application.

Claims

1. A method for preparing a copper catalyst for the synthesis of organosilicon monomers, characterized in that, Includes the following steps: Pure copper and pure zinc are selected and alloyed at a ratio of 100:0.5 to form a copper-zinc molten metal. The molten metal is then atomized by high-pressure air jet. After the molten metal solidifies and settles, powder A is obtained. Copper oxide powder was partially calcined to obtain powder B; powder A and powder B were mixed and placed in a reaction furnace, nitrogen gas was introduced and the mixture was heated to 450~600℃. Heating was stopped after 4~8 hours and the mixture was cooled to room temperature. The obtained material and grinding balls were sealed in a ball mill jar and ball milled. The ball milling conditions were: ball-to-material ratio of 1:1, ball milling speed of 40-50 rpm, ball milling time of 20-30 min, and then passed through a 100-mesh sieve to obtain the copper catalyst. The incomplete calcination process involves placing copper oxide powder into a calcining vessel, spreading it to a thickness of 20 mm, and calcining it. The calcination process is as follows: from room temperature to 500°C for 2 hours, holding at 500°C for 0.5 hours, raising the temperature to 700°C for 1 hour, holding at 700°C for 1 hour, raising the temperature to 900°C for 2 hours, holding at 900°C for 1 hour, and then cooling to room temperature to obtain powder B.

2. The method for preparing the copper catalyst for the synthesis reaction of organosilicon monomers according to claim 1, characterized in that, The powder A is a Cu-0.5Zn master alloy powder.

3. The method for preparing the copper catalyst for the organosilicon monomer synthesis reaction according to claim 1, characterized in that, Powder A and powder B are mixed in a mass ratio of 20:

80.

4. The method for preparing the copper catalyst for the organosilicon monomer synthesis reaction according to claim 1, characterized in that, The nitrogen gas flow rate is 300-600 ml / h.

5. The method for preparing the copper catalyst for the synthesis reaction of organosilicon monomers according to claim 1, characterized in that, The ball-to-material ratio was 1:1, the ball milling speed was 40 rpm, and the ball milling time was 20 min.

6. The catalyst obtained by the preparation method according to any one of claims 1 to 5, characterized in that, The catalyst contains copper, copper oxide, cuprous oxide, and dispersed zinc oxide; the zinc oxide content is 0.9-1%, the copper content is greater than or equal to 19.9%, and the copper oxide content is less than or equal to 79.9%.

7. The application of the catalyst according to claim 6, characterized in that, The application is an organosilicon monomer synthesis reaction, and the organosilicon monomer synthesis reaction conditions are: pressure 0.15 MPa, temperature 300℃.

8. The application according to claim 7, characterized in that, The amount of catalyst used is 8-10% of the mass of silicon powder.

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