A [bmim]cl@mcm-41 catalyst and a method for synthesizing methyltrichlorosilane using the same

Abstract

The application discloses a [BMIM]Cl@MCM-41 catalyst and a method for synthesizing methyltrichlorosilane by using the catalyst, and the preparation method of the catalyst comprises the following steps: a) preparing MCM-41 mesoporous molecular sieve by using a hydrothermal synthesis method, wherein the specific method is as follows: taking hexadecyl trimethyl ammonium bromide (CTAB) as a template agent, tetraethyl orthosilicate (TEOS) as a silicon source, and tetramethylammonium hydroxide (TMAOH) as an alkali liquor, stirring the mixture into a gel, carrying out dealcoholization, and then performing crystallization, water washing, drying and calcination to obtain the MCM-41 mesoporous molecular sieve. The [BMIM]Cl@MCM-41 is used as a catalyst for synthesizing methyltrichlorosilane by using a Grignard reagent method, wherein the mesoporous structure of the MCM-41 improves the diffusion efficiency of reactants, the structure is matched with the size of ionic liquid molecules, uniform active centers are formed, and the contact path of reactants is shortened.

Description

Technical Field

[0001] This invention belongs to the field of organosilicon compound synthesis technology, and relates to a [BMIM]Cl@MCM-41 catalyst and a method for synthesizing methyltrichlorosilane. Background Technology

[0002] The rapid development of the organosilicon industry is inseparable from the synthesis of organosilicon monomers and the wide application of their products. More than a thousand organosilicon products are widely used in various sectors of the national economy, making it one of the fastest-growing varieties in new chemical materials. In organosilicon production, the most important and complex part is monomer synthesis. Traditional methods for synthesizing methyltrichlorosilane include the direct method, disproportionation method, and Grignard reagent method. However, the direct method for synthesizing methyltrichlorosilane has a low silicon powder conversion rate (65%) and produces a large amount of dimethyldichlorosilane as a byproduct (accounting for >18%). The disproportionation method requires high temperature and pressure and has high energy consumption. The traditional Grignard reagent method requires a low temperature (-30℃). During industrialization, MeMgX readily reacts with SiCl4, causing rapid exothermic reactions that lead to localized overheating and potential explosion risks. The traditional catalyst CuCl has poor selectivity and cannot suppress excessive substitution of methyl groups.

[0003] To address these issues, a [BMIM]Cl@MCM-41 catalyst and a method for synthesizing methyltrichlorosilane were designed. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a rationally designed [BMIM]Cl@MCM-41 catalyst and a method for synthesizing methyltrichlorosilane, which improves reaction selectivity, reduces reaction energy consumption, and lowers production costs. This invention uses an ionic liquid-modified mesoporous molecular sieve ([BMIM]Cl@MCM-41) as a catalyst to efficiently prepare methyltrichlorosilane (CH3SiCl3) via the reaction of silicon tetrachloride (SiCl4) with a methyl Grignard reagent (CH3MgX). Furthermore, the catalyst production process is green and environmentally friendly, and exhibits good recyclability.

[0005] This invention is achieved through the following technical solution: a [BMIM]Cl@MCM-41 catalyst, the preparation method of which includes the following steps:

[0006] a) Preparation of MCM-41 mesoporous molecular sieve: The preparation of MCM-41 mesoporous molecular sieve adopts a hydrothermal synthesis method, the specific method is as follows: using hexadecyltrimethylammonium bromide (CTAB) as a template agent, tetraethyl orthosilicate (TEOS) as a silicon source, and tetramethylammonium hydroxide (TMAOH) as an alkaline solution, they are mixed and stirred into a gel and then subjected to de-alcoholization, followed by crystallization, water washing, drying and calcination to obtain MCM-41 mesoporous molecular sieve.

[0007] b) Dissolve (1-butyl-3-methylimidazolium chloride) ([BMIM]Cl) in anhydrous ethanol, add calcined MCM-41, sonicate, and vacuum dry to obtain the [BMIM]Cl@MCM-41 catalyst.

[0008] Preferably, in step a), the molar ratio of CTAB to TEOS is 0.1-0.5:1, and the pH of the added alkaline solution TMAOH is controlled at 9-11 to form a micelle structure.

[0009] Preferably, the crystallization conditions in step a) are 100-120℃ for 48-72 hours; the calcination conditions are 500-800℃ for 4-8 hours.

[0010] Preferably, in step b), the mass ratio of [BMIM]Cl to MCM-41 is 1:5; and the ratio of anhydrous ethanol to [BMIM]Cl is 25 mL / 1 g.

[0011] A method for synthesizing methyltrichlorosilane, comprising: adding SiCl4 and the catalyst described in claim 1 to a dry reaction vessel, adding CH3MgCl dropwise to the reaction system, stirring the reaction for several hours, quenching with hydrochloric acid, separating the liquids, and distilling to obtain the product CH3SiCl3.

[0012] Preferably, the mass ratio of SiCl4 to catalyst is 50-100:1.

[0013] Preferably, the molar ratio of the added CH3MgCl to the added SiCl4 is 1.5-2.0:1.

[0014] Preferably, after adding SiCl4 and the catalyst into the reactor, the reactor needs to be purged with nitrogen at least three times.

[0015] Preferably, the reaction conditions in the reactor are stirring at room temperature for 2 hours.

[0016] Preferably, the concentration of the added dilute hydrochloric acid for quenching is 10%.

[0017] The beneficial effects of this invention are as follows:

[0018] Compared with existing technologies, this invention uses [BMIM]Cl@MCM-41 as a catalyst for the synthesis of methyltrichlorosilane via the Grignard reagent method. The mesoporous structure of MCM-41 enhances the diffusion efficiency of the reactants, and this structure matches the molecular size of the ionic liquid, forming uniformly dispersed active centers, shortening the reactant contact path, and reducing side reactions (such as the formation of (CH3)2SiCl2), thus increasing selectivity to 99.7%. The Cl in [BMIM]Cl... -As a weak Lewis acid site, it polarizes the Si-Cl bond through electrostatic interaction, promoting the nucleophilic substitution reaction of SiCl4. At the same time, the imidazole cation stabilizes the reaction intermediate (such as SiCl3-) through hydrogen bonding, lowering the reaction energy barrier. This synergistic effect allows the reaction to proceed efficiently at room temperature (25℃). The chemical bonding between the hydroxyl groups on the MCM-41 surface and [BMIM]Cl effectively inhibits the loss of ionic liquid during the reaction process, enabling the catalyst to maintain >98% activity after being recycled ≥10 times. The production process of this catalyst system conforms to the direction of green environmental protection, and the catalyst can be recovered by simple magnetic separation after the reaction, reducing production costs. Attached Figure Description

[0019] Figure 1 This is a comparison chart of the catalyst stability of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to more clearly understand the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0021] In the description of this invention, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "inner", "outer", "lateral", and "vertical" is based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing this invention, and is not intended to indicate or imply that the device or component referred to must have a specific orientation, and therefore should not be construed as a limitation of this invention.

[0022] The invention will now be described in detail with reference to the accompanying drawings: Figure 1 As shown, a [BMIM]Cl@MCM-41 catalyst is prepared by means of the following steps:

[0023] a) Preparation of MCM-41 mesoporous molecular sieve: The preparation of MCM-41 mesoporous molecular sieve adopts a hydrothermal synthesis method, the specific method is as follows: using hexadecyltrimethylammonium bromide (CTAB) as a template agent, tetraethyl orthosilicate (TEOS) as a silicon source, and tetramethylammonium hydroxide (TMAOH) as an alkaline solution, they are mixed and stirred into a gel and then subjected to de-alcoholization, followed by crystallization, water washing, drying and calcination to obtain MCM-41 mesoporous molecular sieve.

[0024] b) Dissolve (1-butyl-3-methylimidazolium chloride) ([BMIM]Cl) in anhydrous ethanol, add calcined MCM-41, sonicate, and vacuum dry to obtain the [BMIM]Cl@MCM-41 catalyst.

[0025] In step a), the molar ratio of CTAB to TEOS is 0.1-0.5:1, and the addition of alkaline solution TMAOH controls the pH to 9-11 to form a micelle structure.

[0026] In step a), the crystallization conditions are 100-120℃ for 48-72 hours; the calcination conditions are 500-800℃ for 4-8 hours.

[0027] In step b), the mass ratio of [BMIM]Cl to MCM-41 is 1:5; the ratio of anhydrous ethanol to [BMIM]Cl is 25 mL / 1 g. A method for synthesizing methyltrichlorosilane is as follows: In a dry reaction vessel, SiCl4 and the catalyst described in claim 1 are added, CH3MgCl is added dropwise to the reaction system, the reaction is stirred for several hours, hydrochloric acid is added to quench the reaction, and the product CH3SiCl3 is obtained by distillation after separation.

[0028] The mass ratio of SiCl4 to catalyst is 50-100:1.

[0029] The molar ratio of CH3MgCl to SiCl4 added is 1.5-2.0:1.

[0030] After adding SiCl4 and catalyst to the reactor, it needs to be purged with nitrogen at least three times.

[0031] The reaction conditions in the reactor were stirring at room temperature for 2 hours.

[0032] The concentration of the added dilute hydrochloric acid for quenching is 10%.

[0033] 1) Synthesis of catalyst ([BMIM]Cl@MCM-41)

[0034] MCM-41 mesoporous molecular sieve was prepared by hydrothermal synthesis. Hexadecyltrimethylammonium bromide (CTAB) was used as a template agent, tetraethyl orthosilicate (TEOS) as a silicon source, and tetramethylammonium hydroxide (TMAOH) as a base source. The mixture was stirred into a gel and then subjected to alcohol removal. After crystallization at 110℃ for 48 h, water washing, vacuum drying at 60℃ for 12 h, and calcination at 550℃ for 5 h, MCM-41 mesoporous molecular sieve was obtained.

[0035] (1-Butyl-3-methylimidazolium chloride) ([BMIM]Cl) was dissolved in anhydrous ethanol, and calcined MCM-41 was added. The mixture was then sonicated for 2 hours and dried under vacuum to obtain the [BMIM]Cl@MCM-41 catalyst.

[0036] 2) Synthesis of methyltrichlorosilane

[0037] In a dry reaction vessel, SiCl4 and [BMIM]Cl@MCM-41 catalyst were added, and CH3MgCl was added dropwise to the reaction system. The mixture was stirred for several hours, quenched with hydrochloric acid, and the product CH3SiCl3 was obtained by distillation after separation. The molar ratio of deionized water to TEOS was 40-250:1.

[0038] Example

[0039] 14.5784 g of CTAB was dissolved in 100 mL of deionized water and stirred until completely dissolved to form a transparent micelle solution. TMAOH, an alkaline adjuster, was added to adjust the pH of the solution to 9-12. 21 g of tetraethyl orthosilicate (TEOS) was slowly added dropwise under vigorous stirring. A white flocculent precipitate gradually formed in the solution. Stirring was continued for 3 hours to complete the hydrolysis-condensation reaction. The mixture was transferred to a polytetrafluoroethylene-lined high-pressure reactor and crystallized at 110 °C for 48 hours, with a heating rate controlled at 10 °C / min. After the reaction, the mixture was cooled to room temperature, filtered, and repeatedly washed with deionized water and ethanol until the filtrate was neutral to remove residual template agent. The filtrate was then dried at 80 °C for 12 hours. 10 g of MCM-41 was placed in a muffle furnace and calcined in air at 550 °C for 5 hours at a heating rate of 2 °C / min to completely remove the template agent, yielding white MCM-41 powder.

[0040] 2g of [BMIM]Cl was dissolved in 50mL of anhydrous ethanol, added to calcined MCM-41, and ultrasonically treated for 2h; then vacuum dried at 60℃ for 12h to obtain the [BMIM]Cl@MCM-41 catalyst.

[0041] 1) Synthesis of methyltrichlorosilane

[0042] In a dry reaction vessel, 100 g of SiCl4 and 1.5 g of catalyst were added, and the mixture was purged with nitrogen three times. CH3MgCl (1.05 mol) was added dropwise to the reaction system, and the mixture was stirred at 25 °C for 2 h. The mixture was quenched with 10% dilute hydrochloric acid, and the fraction distilled at 62-70 °C was collected after separation to obtain the product CH3SiCl3. The product was analyzed by gas chromatography (GC), and the results are shown in the table below.

[0043] Table 1. GC detection results of methyltrichlorosilane

[0044] Mass fraction of methyltrichlorosilane / % ≥ 99.5 The mass fraction of trimethylchlorosilane / % ≤ 0.03 The mass fraction of silicon tetrachloride / % ≤ 0.02 The mass fraction of trichlorosilane / % ≤ 0.01 Dimethyldichlorosilane mass fraction / % ≤ 0.3

[0045] Compared with traditional processes using catalysts (CuCl, ZnCl / ZSM-5), the experimental data are as follows. As shown in the table below, the [BMIM]Cl@MCM-41 catalyst improves reaction selectivity, reduces reaction energy consumption, and lowers production costs. Furthermore, the catalyst's production process is green and environmentally friendly, and it exhibits excellent recyclability.

[0046] Table 2 Comparison of Traditional Processes

[0047]

[0048]

[0049] The specific embodiments described herein are merely illustrative of the principles and effects of the invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this invention should still be covered by the claims of this invention.

Claims

1. A [BMIM]Cl@MCM-41 catalyst, characterized in that: The preparation method of the catalyst includes the following steps: a) Preparation of MCM-41 mesoporous molecular sieve: The preparation of MCM-41 mesoporous molecular sieve adopts a hydrothermal synthesis method, the specific method is as follows: using hexadecyltrimethylammonium bromide as a template agent, tetraethyl orthosilicate as a silicon source, and tetramethylammonium hydroxide as an alkaline solution, they are mixed and stirred into a gel and then subjected to alcohol removal, followed by crystallization, water washing, drying and calcination to obtain MCM-41 mesoporous molecular sieve; b) Dissolve [BMIM]Cl in anhydrous ethanol, add calcined MCM-41, sonicate, and vacuum dry to obtain the [BMIM]Cl@MCM-41 catalyst.

2. The [BMIM]Cl@MCM-41 catalyst according to claim 1, characterized in that: In step a), the molar ratio of CTAB to TEOS is 0.1-0.5:1, and alkaline solution TMAOH is added to control the pH to 9-11 in order to form a micelle structure.

3. The [BMIM]Cl@MCM-41 catalyst according to claim 1, characterized in that: In step a), the crystallization conditions are 100-120℃ for 48-72 hours; the calcination conditions are 500-800℃ for 4-8 hours.

4. The [BMIM]Cl@MCM-41 catalyst according to claim 1, characterized in that: In step b), the mass ratio of [BMIM]Cl to MCM-41 is 1:5; the ratio of anhydrous ethanol to [BMIM]Cl is 25 mL / 1 g.

5. A method for synthesizing methyltrichlorosilane, characterized in that: The method is as follows: SiCl4 and the catalyst described in claim 1 are added to a dry reaction vessel, CH3MgCl is added dropwise to the reaction system, the reaction is stirred for several hours, hydrochloric acid is added to quench the reaction, and the product CH3SiCl3 is obtained by distillation after separation.

6. The method for synthesizing methyltrichlorosilane according to claim 5, characterized in that: The mass ratio of SiCl4 to catalyst is 50-100:

1.

7. The method for synthesizing methyltrichlorosilane according to claim 5, characterized in that: The molar ratio of CH3MgCl to SiCl4 added is 1.5-2.0:

1.

8. The method for synthesizing methyltrichlorosilane according to claim 5, characterized in that: After adding SiCl4 and catalyst to the reactor, it needs to be purged with nitrogen at least three times.

9. The method for synthesizing methyltrichlorosilane according to claim 5, characterized in that: The reaction conditions in the reactor were stirring at room temperature for 2 hours.

10. The method for synthesizing methyltrichlorosilane according to claim 5, characterized in that: The concentration of the added dilute hydrochloric acid for quenching is 10%.

Images