A cocatalyst for synthesizing methyl chlorosilane and a preparation method thereof

Abstract

The application belongs to the technical field of organic synthesis catalysts, and discloses a cocatalyst for synthesizing methyl chlorosilane and a preparation method thereof. The cocatalyst is obtained by mixing and ball milling chelated tin powder and copper-aluminum-tin alloy powder, and the element ratio is as follows: copper 20-22 parts, aluminum 29-31 parts, tin 11-14 parts, and phosphorus 0.8-1 part. In the reaction of synthesizing methyl chlorosilane, the cocatalyst can play a synergistic role with the main catalyst, and can improve the reaction rate and yield. By using the cocatalyst, specific reactions can be selectively catalyzed, the occurrence of side reactions can be reduced, and the selectivity of dimethyl can be effectively improved.

Description

Technical Field

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

[0002] Dimethyldichlorosilane is the most important and widely used organosilicon monomer in the preparation of organosilicon materials, forming the foundation and pillar of the entire organosilicon industry. The main production process for this monomer is the direct method (Rochow process), which is the most economical route for synthesizing M2. The reaction process involves uniformly mixing Si powder, a Cu-based main catalyst, and a co-catalyst, followed by the introduction of MeCl to undergo a direct substitution reaction. However, the reaction may also be accompanied by side reactions such as thermal decomposition, disproportionation, and hydrolysis of chlorosilanes, resulting in complex reaction products and low selectivity for the target product.

[0003] The direct preparation of dimethyldichlorosilane generates a significant amount of byproducts, including monomethyltrichlorosilane (approximately 10-15%) and trimethylchlorosilane (approximately 2%). However, these byproducts have limited applications, and direct emission easily leads to their reaction with moisture in the air to produce hydrogen chloride, polluting the environment. Long-term storage also presents numerous inconveniences, and their large-scale accumulation has now caused environmental and safety problems. The accumulation of these byproducts has significantly hindered the development of the organosilicon industry.

[0004] Catalysts play a particularly important role in the direct synthesis of organochlorosilanes, with copper catalysts being the most effective. Currently, both domestically produced and imported copper catalysts suffer from low selectivity or activity. Catalyst activity is often significantly improved by adding small amounts of co-catalysts, and the appropriate addition of co-catalysts helps reduce byproduct content, thereby improving the selectivity and yield of M2. Therefore, the research and innovation of co-catalysts are especially important in the direct synthesis of organochlorosilanes. Summary of the Invention

[0005] Purpose of the invention: To address the shortcomings of the prior art, this application provides a co-catalyst for the synthesis of methylchlorosilane and a method for its preparation.

[0006] Technical solution: The present invention provides a co-catalyst for the synthesis of methylchlorosilane. The co-catalyst is formed by ball milling a mixture of chelated tin powder and copper-aluminum-tin alloy powder, with the following elemental ratio: 20-22 parts copper, 29-31 parts aluminum, 11-14 parts tin, and 0.8-1 parts phosphorus.

[0007] This invention also provides a method for preparing a co-catalyst for the synthesis of methylchlorosilanes, comprising the following steps:

[0008] Add 8-10 parts of ethylenediaminetetramethylene phosphoric acid to water and stir until homogeneous. Then add 4-5 parts of ammonium carbonate and 2-3 parts of tin oxide. Stir at 40-50℃ for about 40-60 minutes. After the solution becomes clear, add 2-3 parts of triethanolamine and stir at 40-50℃ for about 30-40 minutes. Finally, spray dry at 90-95℃ to obtain chelated tin powder.

[0009] Metallic copper, metallic aluminum, and metallic tin are placed in a calcining vessel and then placed in a vacuum induction furnace of an atomization device. The furnace is evacuated and heated until completely melted. At the instant the molten alloy liquid flows into the atomization chamber, it is sprayed with an argon gas stream. Copper-aluminum-tin alloy powder is collected in the atomization chamber.

[0010] The chelated tin powder and copper-aluminum-tin alloy powder were premixed at a mass ratio of 1:4-6 and ground for 10-20 min. The mixed powder was then transferred to a ball mill jar, milling beads and ethanol were added, and the mixture was first ball milled at 800-1000 rpm for 10-20 min, then reduced to 200-250 rpm and continued for 20-30 h. Finally, the mixture was sieved, separated and dried to obtain the co-catalyst described in this invention.

[0011] Specifically, the composition ratio of copper, aluminum, and tin is: 35-45 parts copper, 50-60 parts aluminum, and 10-15 parts tin. Preferably, the composition ratio of copper, aluminum, and tin is: 35 parts copper, 50 parts aluminum, and 15 parts tin.

[0012] Specifically, the vacuuming process is carried out until the vacuum level inside the vacuum induction furnace is 1×10⁻⁶. -3 Pa.

[0013] Specifically, the smelting process conditions are as follows: power supply voltage: 110V / 220V AC; power supply frequency: 50~60Hz; operating frequency: 150~250KHz.

[0014] Specifically, the mass ratio of chelated tin powder to copper-aluminum-tin alloy powder is 1:4-6. Preferably, the mass ratio of chelated tin powder to copper-aluminum-tin alloy powder is 1:5.

[0015] Specifically, the mass ratio of mixed powder, zirconium beads, and ethanol is 20:60:30. The grinding beads are 2mm in diameter zirconium beads. The grinding process involves first grinding at 800 rpm for 10-20 minutes, then reducing the speed to 200 rpm and continuing for 20-30 hours.

[0016] The present invention also provides a method for synthesizing methylchlorosilane, wherein the main catalyst is a ternary copper catalyst or a copper catalyst, the co-catalyst is the co-catalyst described in the present invention, and the amount of the co-catalyst is 1-2% of the mass of the reactant silicon powder.

[0017] Beneficial effects: In the preparation of chelated tin powder, the method employed in this invention avoids the difficulties of large-scale precipitation or gel formation that makes stirring difficult during conventional chelation processes. In the preparation of copper alloy powder, the method employed in this invention can effectively obtain uniformly dispersed metal alloys. During ball milling, the co-catalyst can form a surface morphology favorable to the synthesis reaction, increasing the contact area.

[0018] In the synthesis of methylchlorosilanes, the co-catalyst described in this invention can synergistically work with a copper catalyst (or a ternary copper catalyst) to improve the reaction rate and yield. Using the co-catalyst described in this invention, specific reactions can be selectively catalyzed, side reactions can be reduced, and the selectivity of dimethylchlorosilane can be effectively improved.

[0019] For reactions using ternary copper catalysts as the main catalyst, the co-catalyst described in this invention can effectively improve conversion and selectivity. For reactions using copper catalysts as the main catalyst, the improvement in conversion and selectivity is even greater. If the co-catalyst described in this invention is used in combination with a copper catalyst, costs can be saved and catalyst post-processing can be made more convenient. Attached Figure Description

[0020] Figure 1 This is a SEM image (10 μm) of the co-catalyst obtained in Example 1 of the present invention.

[0021] Figure 2 This is a SEM image (5 μm) of the co-catalyst obtained in Example 1 of the present invention.

[0022] Figure 3 This is a SEM image (2 μm) of the co-catalyst obtained in Example 1 of the present invention.

[0023] Figure 4 This is a SEM image (10 μm) of the co-catalyst obtained in Comparative Example 1 of this invention.

[0024] Figure 5 This is a SEM image (5 μm) of the co-catalyst obtained in Comparative Example 1 of the present invention.

[0025] Figure 6 This is a SEM image (2 μm) of the co-catalyst obtained in Comparative Example 1 of the present invention. Detailed Implementation

[0026] The technical solution of this application will be described in detail below through embodiments, but the scope of protection of this application is not limited to the embodiments described. The number of parts mentioned in this invention refers to parts by weight.

[0027] Example 1

[0028] Ten parts of ethylenediaminetetramethylene phosphoric acid were added to deionized water and stirred until homogeneous. Five parts of ammonium carbonate were slowly added, followed by two parts of tin oxide. The mixture was stirred at 50°C for about 60 minutes. After the solution became clear, two parts of triethanolamine were added. The mixture was stirred at 50°C for about 40 minutes. Finally, the solution was spray-dried at 95°C to obtain chelated tin powder.

[0029] Place 35 parts pure copper, 50 parts pure aluminum, and 15 parts pure tin in a calcining vessel, then place it inside the vacuum induction furnace of an atomization device (power supply voltage: 110V / 220V AC; power supply frequency: 50~60Hz; operating frequency: 150~250KHz). Evacuate the furnace until the vacuum level reaches 1×10⁻⁶. -3 Pa, increase the current until the three metals mentioned above are completely melted into liquid. At the moment the liquid flows into the atomization chamber, it is sprayed with argon gas, and copper-aluminum-tin alloy powder is obtained at the bottom of the atomization chamber.

[0030] Weigh the chelated tin powder and copper-aluminum-tin alloy powder obtained above, premix them at a mass ratio of 1:5, grind for 10 min, then transfer the mixed powder to a ball mill jar, add zirconium beads with a diameter of 2 mm, and add ethanol at the same time, so that the mass ratio of mixed powder: zirconium beads: ethanol is 20:60:30; first pre-treat the mixture at 800 rpm for 10 min in a ball mill, then immediately reduce to 200 rpm and continue for 24 h, finally separate by sieving, dry, and obtain the co-catalyst of the present invention.

[0031] The SEM image of the co-catalyst obtained in Example 1 is shown below. Figures 1-3 As shown in the figure, the microstructure reveals the presence of doped atoms and numerous pores, which create highly diffused channels, reducing electron diffusion energy and facilitating electron migration.

[0032] Example 2

[0033] Eight parts of ethylenediaminetetramethylene phosphoric acid were added to deionized water and stirred until homogeneous. Four parts of ammonium carbonate were slowly added, followed by two parts of tin oxide to the filtrate. The mixture was stirred at 40°C for about 40 minutes. After the solution became clear, two parts of triethanolamine were added and the mixture was stirred at 40°C for about 30 minutes. Finally, the mixture was spray-dried at 90°C to obtain chelated tin powder.

[0034] Place 35 parts copper, 50 parts aluminum, and 10 parts tin in a calcining vessel and place it inside the vacuum induction furnace of an atomization device (power supply voltage: 110V / 220V AC; power supply frequency: 50~60Hz; operating frequency: 150~250KHz). Evacuate the furnace until the vacuum level reaches 1×10⁻⁶. -3 Pa, increase the current to raise the temperature until the three metals are completely melted into liquid. At the moment the liquid flows into the atomization chamber, it is sprayed with argon gas to obtain copper-aluminum-tin alloy powder at the bottom of the atomization chamber.

[0035] Weigh the chelated tin powder and copper-aluminum-tin alloy powder obtained above, premix them at a mass ratio of 1:4, grind for 10 min, then transfer the mixed powder to a ball mill jar, add zirconium beads with a diameter of 2 mm, and add anhydrous ethanol at the same time, so that the mass ratio of mixed powder: zirconium beads: ethanol is 20:60:30; first pretreat the mixture at 800 rpm for 10 min in a ball mill, then immediately reduce to 200 rpm and continue for 20 h, finally separate by sieving, dry, and obtain the co-catalyst of the present invention.

[0036] Example 3

[0037] Ten parts of ethylenediaminetetramethylene phosphoric acid were added to deionized water and stirred until homogeneous. Five parts of ammonium carbonate were slowly added, followed by three parts of tin oxide to the filtrate. The mixture was stirred at 50°C for about 60 minutes. After the solution became clear, three parts of triethanolamine were added and the mixture was stirred at 50°C for about 40 minutes. Finally, the mixture was spray-dried at 95°C to obtain chelated tin powder.

[0038] Place 45 parts copper, 60 parts aluminum, and 15 parts tin in a calcining vessel and place it inside the vacuum induction furnace of an atomization device (power supply voltage: 110V / 220V AC; power supply frequency: 50~60Hz; operating frequency: 150~250KHz). Evacuate the furnace until the vacuum level reaches 1×10⁻⁶. -3 Pa, increase the current to raise the temperature until the three metals are completely melted into liquid. At the moment the liquid flows into the atomization chamber, it is sprayed with argon gas to obtain copper-aluminum-tin alloy powder at the bottom of the atomization chamber.

[0039] Weigh the chelated tin powder and copper-aluminum-tin alloy powder obtained above, premix them at a mass ratio of 1:6, grind for 20 min, then transfer the mixed powder to a ball mill jar, add zirconium beads with a diameter of 2 mm, and add anhydrous ethanol at the same time, so that the mass ratio of mixed powder: zirconium beads: ethanol is 20:60:30; first pretreat the mixture at 1000 rpm for 20 min in a ball mill, then immediately reduce to 250 rpm and continue for 30 h, finally separate by sieving, dry, and obtain the co-catalyst of the present invention.

[0040] Comparative Example 1

[0041] Place 35 parts copper, 50 parts aluminum, and 10 parts tin in a calcining vessel and place it inside the vacuum induction furnace of an atomization device (power supply voltage: 110V / 220V AC; power supply frequency: 50~60Hz; operating frequency: 150~250KHz). Evacuate the furnace until the vacuum level reaches 1×10⁻⁶. -3Pa, increase the current to raise the temperature until the three metals are completely melted into liquid. At the moment the liquid flows into the atomization chamber, it is sprayed with argon gas to obtain copper-aluminum-tin alloy powder at the bottom of the atomization chamber.

[0042] Weigh commercially available tin powder and the copper-aluminum-tin alloy powder obtained above, premix them at a mass ratio of 1:5, grind for 10 minutes, then transfer the mixed powder to a ball mill jar, add zirconium beads with a diameter of 2 mm, and add anhydrous ethanol at the same time, so that the mass ratio of mixed powder: zirconium beads: ethanol is 20:60:30; first pretreat the mixture at 800 rpm for 10 minutes in a ball mill, then immediately reduce to 200 rpm and continue for 20 hours, finally separate by sieving, dry, and obtain the co-catalyst of the present invention.

[0043] The SEM image of the co-catalyst obtained in Comparative Example 1 is shown below. Figures 4-6 As shown.

[0044] Example 4

[0045] Silicon powder was mixed with a ternary copper catalyst (copper, copper oxide, cuprous oxide) and the co-catalyst obtained in Example 1. The catalyst accounted for 8% of the total mass of silicon powder, and the co-catalyst accounted for 2% of the total mass of silicon powder. The mixture was then packed into a reactor to form a mixed catalyst. The reactor was a micro fixed-bed reactor (Φ20×50). A nitrogen purging system was used, and the pressure was adjusted to 0.15 MPa. Then, chloromethane gas was switched to contact the mixed catalyst, and the reaction temperature was controlled at 300°C. The products after the reaction were collected and subjected to chromatographic analysis to calculate the silicon powder conversion rate and M2 selectivity.

[0046] Silicon conversion rate = (W 反应前 -W 反应后 ) / W 反应前 *100%

[0047] M1 selectivity = W M1 / (W M1 +W M2 +W M3 )*100%

[0048] M2 selectivity = W M2 / (W M1 +W M2 +W M3 )*100%

[0049] M3 selectivity = W M3 / (W M1 +W M2 +W M3 )*100%

[0050] Wherein, M1: monomethyltrichlorosilane, M2: dimethyldichlorosilane, M3: trimethylmonochlorosilane, and W is the weight of the substance.

[0051] Example 5

[0052] The basic steps are largely the same as in Example 4, except that the co-catalyst obtained in Comparative Example 1 is used.

[0053] Example 6

[0054] The basic steps are largely the same as in Example 4, except that no co-catalyst is used.

[0055] Example 7

[0056] Silicon powder was mixed with a copper catalyst and the co-catalyst obtained in Example 1. The catalyst accounted for 8% of the total mass of silicon powder, and the co-catalyst accounted for 2% of the total mass of silicon powder. The mixture was then packed into a reactor to form a mixed catalyst. The reactor was a micro fixed-bed reactor (Φ20×50). A nitrogen purging system was used, and the pressure was adjusted to 0.15 MPa. Then, chloromethane gas was switched to contact the mixed catalyst, and the reaction temperature was controlled at 300°C. The products after the reaction were collected and subjected to chromatographic analysis to calculate the silicon powder conversion rate and M2 selectivity.

[0057] Example 8

[0058] The basic steps are largely the same as in Example 7, except that the co-catalyst obtained in Comparative Example 1 is used.

[0059] Example 9

[0060] The basic steps are largely the same as in Example 7, except that no co-catalyst is used.

[0061] The results obtained in Examples 4-9 are shown in the table below:

[0062]

[0063]

[0064] The results above show that for reactions using a ternary copper catalyst as the main catalyst, the co-catalyst described in this invention can effectively improve the conversion rate and selectivity. For reactions using a copper catalyst as the main catalyst, the improvement in conversion rate and selectivity is even greater. Using the co-catalyst described in this invention in combination with a copper catalyst can save costs and facilitate catalyst post-processing. Furthermore, the comparative example shows that if conventional tin powder is used instead of chelated tin powder during preparation, the selectivity and conversion rate decrease slightly.

[0065] The above description is merely a preferred embodiment of this application and is not intended to limit this application.

Claims

1. A co-catalyst for the synthesis of methylchlorosilanes, characterized in that, The co-catalyst is prepared by ball milling a mixture of chelated tin powder and copper-aluminum-tin alloy powder, and is obtained by the following steps, by mass fraction: Add 8-10 parts of ethylenediaminetetramethylene phosphoric acid to water and stir until homogeneous. Then add 4-5 parts of ammonium carbonate and 2-3 parts of tin oxide. Stir at 40-50℃ for 40-60 minutes. After the solution becomes clear, add 2-3 parts of triethanolamine and stir at 40-50℃ for 30-40 minutes. Finally, spray dry at 90-95℃ to obtain chelated tin powder. Place 35-45 parts copper, 50-60 parts aluminum, and 10-15 parts tin in a calcining vessel, place it in a vacuum induction furnace of an atomization device, evacuate the vacuum, heat it to complete melting, and spray it with argon gas at the instant the molten alloy liquid flows into the atomization chamber. Collect copper-aluminum-tin alloy powder in the atomization chamber. The chelated tin powder and copper-aluminum-tin alloy powder were premixed at a mass ratio of 1:4-6 and ground for 10-20 min. The mixed powder was then transferred to a ball mill jar, milling beads and ethanol were added, and the mixture was first ball milled at 800-1000 rpm for 10-20 min, then reduced to 200-250 rpm and continued for 20-30 h. Finally, the mixture was sieved, separated and dried to obtain the co-catalyst.

2. The co-catalyst for synthesizing methyl chlorosilane according to claim 1, characterized in that, The vacuum degree in the vacuum induction furnace is 1x10 -3 Pa.

3. The co-catalyst for synthesizing methyl chlorosilane according to claim 1, characterized in that, The mass ratio of chelated tin powder to copper-aluminum-tin alloy powder is 1:

5.

4. The co-catalyst for synthesizing methyl chlorosilane according to claim 1, characterized in that, The grinding beads are zirconium beads with a diameter of 2 mm; during grinding, the mass ratio of mixed powder: zirconium beads: ethanol is 20:60:

30.

5. The co-catalyst for synthesizing methyl chlorosilane according to claim 1, characterized in that, The ball milling process involves first milling at 800 rpm for 10-20 minutes, then reducing the speed to 200 rpm and continuing for 20-30 hours.

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