A preparation process and device for methyltrimethoxysilane

Abstract

The present invention relates to the field of chemical production, and discloses a preparation process of methyltrimethoxysilane, wherein methanol vaporized from a vaporizer and monomethyltrichlorosilane are introduced into an esterification tower in proportion to generate an esterification reaction, methanol is introduced into the esterification tower from the lower part of the esterification tower, monomethyltrichlorosilane is sprayed downward from the upper part of the esterification tower, and the reaction product of the esterification reaction liquid is introduced into a cyclone gas-water separator for gas-liquid separation, a part of the liquid separated by the cyclone gas-water separator is refluxed to the bottom of the esterification tower, and the other part enters a neutralization reactor containing a sodium methoxide solution from the lower end of the cyclone gas-water separator for neutralization, the reaction liquid is filtered and desalted to obtain a MTMS crude product, the crude product enters a distillation tower for intermittent distillation, and when the MTMS at the top of the tower reaches a certain content, the distillation product at the top of the tower passes through a glass tube containing a dechlorination desiccant, and is cooled and collected to obtain a neutral MTMS finished product. The present invention has the advantages and effects of high purity of methyltrimethoxysilane and good effect when used.

Description

Technical Field

[0001] The invention relates to the technical field of chemical production, and in particular to a preparation process and a device for methyltrimethoxysilane. Background Art

[0002] Methyltrimethoxysilane ([CH 3 Si(OCH 3 ) 3 ], referred to as MTMS) is an important silane coupling agent among methyl alkoxysilanes, mainly used as a crosslinking agent for dealcoholized silicone sealants, as well as a surface treatment agent for glass fibers and an external treatment agent for reinforced plastic laminates, and synthesized methylcyclohexyldimethoxysilane. Due to its unique properties, methyltrimethoxysilane is widely used in various fields such as aviation, aerospace, military, medicine and health, and civil use. In the prior art, methylchlorosilane and methanol are often used as raw materials for esterification reaction to produce MTMS. In the production process, hydrogen chloride impurities are inevitably generated and need to be removed.

[0003] Patent application No. 202111256763.9 discloses a process and device for preparing methyltrimethoxysilane. In the technology, the crude MTMS is prepared by a stripping tower, a condenser, a heat exchanger and a gas-liquid separation tank. However, the preparation of MTMS by the above patented technology has the following problems: First, the esterification and neutralization are not thorough, and the product MTMS contains hydrogen chloride, which is mainly caused by the MTMS liquid carrying part of the hydrogen chloride gas during the separation process, resulting in a low purity of MTMS; second, monomethyltrichlorosilane inevitably contains olefins, which react with hydrogen chloride to form tertiary chloroalkanes (C 6 H 13 Cl), which may cause the product to crosslink prematurely or too quickly when used as a crosslinking agent. Summary of the invention

[0004] The invention aims to provide a preparation process and device of methyltrimethoxysilane, which has the effects of high purity of methyltrimethoxysilane and good effect when used.

[0005] The above technical purpose of the present invention is achieved through the following technical scheme: A preparation process of methyltrimethoxysilane comprises the following steps:

[0006] (1) Esterification: Methanol vaporized from a vaporizer and monomethyltrichlorosilane are introduced into an esterification tower in a certain proportion to cause an esterification reaction. Methanol is fed into the esterification tower from the bottom, and monomethyltrichlorosilane is sprayed downward from the top of the esterification tower.

[0007] (2) Separation: The liquid reaction product after the esterification reaction is passed into a cyclone gas-water separator for gas-liquid separation.

[0008] (3) Neutralization: A portion of the liquid separated by the cyclone gas-water separator is refluxed to the bottom of the esterification tower, and the other portion is neutralized in a neutralization reactor containing sodium methoxide solution from the lower end of the cyclone gas-water separator. The reaction liquid is filtered and desalted to obtain a crude MTMS product.

[0009] (4) Distillation and drying: The crude MTMS product is passed from the trimethoxy intermediate tank into the distillation tower for intermittent distillation. When the MTMS content at the top of the tower reaches a certain level, the top distillation product passes through a glass tube containing a dechlorination desiccant, is cooled and collected to obtain a neutral MTMS finished product.

[0010] (5) Acid production: The hydrogen chloride gas separated by the cyclone gas-water separator and the hydrogen chloride escaped from the top of the esterification tower are passed through a two-stage washing tower and then introduced into a hydrochloric acid recovery tank, where water is added to prepare hydrochloric acid.

[0011] The present invention is further configured as follows: the mass ratio of the methanol to monomethyltrichlorosilane is (1.35-1.5):1.

[0012] The present invention is further configured as follows: in step (1), the temperature at the top of the esterification tower is controlled at 65-72°C, the temperature in the esterification tower is 72-76°C, the temperature in the esterification tower is 90-95°C, and the pressure in the esterification tower is controlled at 0.55-0.6MPa.

[0013] The present invention is further configured as follows: in the step (2), the rotation speed of the cyclone gas-water separator is 2500-3000 rpm, the pressure is 0.15-0.30 MPa, the flow rate is 0.4-1 m / s, the temperature is controlled at 70-80° C., and the hydrogen chloride gas separation efficiency reaches 99.9%.

[0014] The present invention is further configured as follows: the reflux ratio of the reaction liquid in step (3) is 0.5-1:1, and the pH of the reaction liquid after neutralization is 8-9.

[0015] The present invention is further configured as follows: in the step (4), the dechlorination desiccant is composed of silicon slag, activated carbon, calcium carbonate powder, and carbide slag, and the ratio thereof is 1:(0.5-1.5):0.5:(2-4).

[0016] The present invention is further configured as follows: the mass ratio of the methyltrimethoxysilane prepared in the step (4) to the dechlorination desiccant is (1-2):1.

[0017] A preparation device for methyltrimethoxysilane, wherein a mixer is connected to an esterification tower, the esterification tower is connected to a cyclone gas-water separator, the bottom of the cyclone gas-water separator is connected to a neutralization reactor and the top is connected to a washing tower, the neutralization reactor is connected to a distillation tower, the outlet end of the distillation tower is connected to a glass tube, and the outlet of the washing tower is connected to a hydrochloric acid recovery tank.

[0018] The beneficial effects of the present invention are:

[0019] 1. In the MTMS preparation process of the present invention, since MTMS is a liquid and hydrogen chloride is a gas under the esterification conditions, the distance between liquid molecules is much smaller than that between gas molecules, and there is a strong interaction force between molecules. Under the mechanical rotation in the cyclone gas-water separator, the kinetic energy of the gas and the liquid increases, and the rate of increase of the kinetic energy of the gas is greater than that of the liquid. The kinetic energy difference increases significantly under the action of mechanical power. Therefore, the use of a cyclone gas-water separator can increase the kinetic energy difference between hydrogen chloride gas and MTMS per unit volume. Under the action of high-speed rotation, the kinetic energy of hydrogen chloride gas is higher than that of MTMS. Under the action of a large kinetic energy difference, the hydrogen chloride gas quickly separates from the MTMS liquid, thereby improving the effect of removing hydrogen chloride from the MTMS liquid.

[0020] 2. Since monomethyltrichlorosilane is volatile, the reaction liquid is refluxed to a part of the esterification tower after neutralization. The refluxed reaction liquid can be used as a solvent, and monomethyltrichlorosilane is dissolved in the solvent, which effectively reduces the loss of raw materials caused by the outflow of hydrogen chloride gas from the reaction system and improves the efficiency of MTMS product generation.

[0021] 3. The cyclone gas-water separator used in this application can improve the separation effect of hydrogen chloride gas and MTMS, further recover the hydrogen chloride in MTMS, improve the hydrogen chloride recovery efficiency, and the recovered hydrochloric acid can be processed and recycled to reduce material costs.

[0022] 4. The present application uses a mixture of silicon slag, activated carbon, calcium carbonate powder, and carbide slag in a certain proportion as a dechlorination desiccant to dechlorinate MTMS, which can not only further remove hydrogen chloride from the MTMS product, but also reduce the content of hydrogen chloride gas in MTMS, and reduce the generation of tertiary chlorinated alkanes (C 6 H 13 Cl) impurities; it can also remove water vapor in the MTMS product, reduce the hydrolysis reaction between water vapor and MTMS, and avoid the reduction of the purity of the MTMS product. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 It is a schematic diagram of a preparation device of methyltrimethoxysilane according to the present invention.

[0025] In the figure, 1. esterification tower; 2. cyclone gas-water separator; 3. neutralization reactor; 4. distillation tower; 5. glass tube; 6. hydrochloric acid recovery tank. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Embodiment 1:

[0028] The methanol vaporized from the vaporizer and monomethyltrichlorosilane are introduced into the esterification tower in a ratio of 1.35:1 to carry out esterification reaction, the methanol is introduced into the esterification tower from the lower part of the esterification tower, and the monomethyltrichlorosilane is sprayed downward from the upper part of the esterification tower; the reaction product after the esterification reaction is introduced into a cyclone gas-water separator, the rotation speed of the cyclone gas-water separator is 2500 rpm, the pressure is 0.15 MPa, the flow rate is 0.4 m / s, and the temperature is controlled at 70-80°C; the liquid reaction product after the esterification reaction is introduced into the cyclone gas-water separator for gas-liquid separation, a part of the liquid separated by the cyclone gas-water separator is refluxed to the bottom of the esterification tower, and the other part enters the neutralization reactor containing sodium methoxide solution from the lower end of the cyclone gas-water separator for neutralization, and the pH value of the reaction liquid is adjusted to 8-9, wherein the reflux ratio is 0.5:1, the reaction liquid is filtered and desalted to obtain a crude MTMS product, the pH of the reaction liquid is adjusted to 8-9, the reaction liquid is filtered and desalted to obtain a crude MTMS product, the crude MTMS product is passed from the trimethoxy intermediate tank into the distillation tower for intermittent distillation, when the MTMS at the top of the tower reaches a certain content, the top distillation product passes through a glass tube with a dechlorination desiccant whose ratio is 1:0.5:0.5:2 of silicon slag, activated carbon: calcium carbonate powder: carbide slag, wherein the mass ratio of methyltrimethoxysilane to the dechlorination desiccant is (1-2):1, and is collected after cooling to obtain a neutral MTMS finished product, the hydrogen chloride gas separated by a cyclone gas-water separator and the hydrogen chloride emitted from the top of the esterification tower are passed through a two-stage washing tower and then introduced into a hydrochloric acid recovery tank, and water is added to the hydrochloric acid recovery tank to prepare hydrochloric acid.

[0029] The pH of the MTMS product was detected to be 4.5, the content of methyltrimethoxysilane was ≥99.9%, and the content of chloride ion was ≤5ppm.

[0030] Embodiment 2:

[0031] The methanol vaporized from the vaporizer and monomethyltrichlorosilane are introduced into the esterification tower in a ratio of 1.5:1 to carry out esterification reaction, the methanol is introduced into the esterification tower from the lower part of the esterification tower, and the monomethyltrichlorosilane is sprayed downward from the upper part of the esterification tower; the reaction product after the esterification reaction is introduced into a cyclone gas-water separator, the rotation speed of the cyclone gas-water separator is 3000 rpm, the pressure is 0.30 MPa, the flow rate is 1 m / s, and the temperature is controlled at 70-80°C; the liquid reaction product after the esterification reaction is introduced into the cyclone gas-water separator for gas-liquid separation, a part of the liquid separated by the cyclone gas-water separator is refluxed to the bottom of the esterification tower, and the other part enters the neutralization reactor containing sodium methoxide solution from the lower end of the cyclone gas-water separator for neutralization, and the reaction is adjusted. The pH value of the liquid is increased to 8-9, wherein the reflux ratio is 1:1, the reaction liquid is filtered and desalted to obtain a crude MTMS product, the crude MTMS product is introduced from the trimethoxy intermediate tank into a distillation tower for intermittent distillation, when the MTMS content at the top of the tower reaches a certain level, the top distillation product passes through a glass tube with a dechlorination desiccant containing silicon slag, activated carbon: calcium carbonate powder: carbide slag in a ratio of 1:1.5:0.5:4, wherein the mass ratio of methyltrimethoxysilane to the dechlorination desiccant is (1-2):1, and is collected after cooling to obtain a neutral MTMS finished product, the hydrogen chloride gas separated by a cyclone gas-water separator and the hydrogen chloride emitted from the top of the esterification tower are passed through a two-stage washing tower and then introduced into a hydrochloric acid recovery tank, and water is added to the hydrochloric acid recovery tank to prepare hydrochloric acid.

[0032] The pH of the MTMS product was detected to be 5.0, the content of methyltrimethoxysilane was ≥99.9%, and the content of chloride ion was ≤5ppm.

[0033] Embodiment 3:

[0034] The methanol vaporized from the vaporizer and monomethyltrichlorosilane are introduced into the esterification tower in a ratio of 1.45:1 to carry out esterification reaction, the methanol is introduced into the esterification tower from the lower part of the esterification tower, and the monomethyltrichlorosilane is sprayed downward from the upper part of the esterification tower; the reaction product after the esterification reaction is introduced into a cyclone gas-water separator, the rotation speed of the cyclone gas-water separator is 2800 rpm, the pressure is 0.30 MPa, the flow rate is 0.8 m / s, and the temperature is controlled at 70-80°C; the liquid reaction product after the esterification reaction is introduced into the cyclone gas-water separator for gas-liquid separation, a part of the liquid separated by the cyclone gas-water separator is refluxed to the bottom of the esterification tower, and the other part enters the neutralization reactor containing sodium methoxide solution from the lower end of the cyclone gas-water separator for neutralization, and the reaction is adjusted. The pH value of the liquid is increased to 8-9, wherein the reflux ratio is 0.75:1, the reaction liquid is filtered and desalted to obtain a crude MTMS product, the crude MTMS product is introduced from the trimethoxy intermediate tank into a distillation tower for intermittent distillation, when the MTMS content at the top of the tower reaches a certain level, the top distillation product passes through a glass tube with a dechlorination desiccant containing silicon slag, activated carbon: calcium carbonate powder: carbide slag in a ratio of 1:1.25:0.5:3, wherein the mass ratio of methyltrimethoxysilane to the dechlorination desiccant is (1-2):1, and is collected after cooling to obtain a neutral MTMS finished product, the hydrogen chloride gas separated by a cyclone gas-water separator and the hydrogen chloride emitted from the top of the esterification tower are passed through a two-stage washing tower and then introduced into a hydrochloric acid recovery tank, and water is added to the hydrochloric acid recovery tank to prepare hydrochloric acid.

[0035] The pH of the MTMS product was detected to be 4.5, the content of methyltrimethoxysilane was ≥99.9%, and the content of chloride ion was ≤5ppm.

[0036] Comparative Example 1:

[0037] The methanol vaporized from the vaporizer and monomethyltrichlorosilane are introduced into the esterification tower in a ratio of 1.45:1 to carry out esterification reaction, the methanol is introduced into the esterification tower from the lower part of the esterification tower, and the monomethyltrichlorosilane is sprayed downward from the upper part of the esterification tower; the reaction product after the esterification reaction is introduced into the gas-liquid separation tank, the separated liquid enters the neutralization reactor, a part of the reaction liquid is refluxed to the bottom of the esterification tower, and the other part enters the neutralization reactor containing sodium methoxide solution for neutralization, and the pH value of the reaction liquid is adjusted to 8-9, wherein the reflux ratio is 0.75:1, the reaction liquid is filtered and desalted to obtain a crude MTMS product, the crude MTMS product is introduced into the distillation tower from the trimethylol intermediate tank for intermittent distillation, when the MTMS content at the top of the tower reaches a certain level, the distillation product at the top of the tower passes through a glass tube, is cooled and collected to obtain a finished MTMS product, the hydrogen chloride emitted from the top of the esterification tower is introduced into a hydrochloric acid recovery tank after passing through a two-stage washing tower, and water is added to the hydrochloric acid recovery tank to prepare hydrochloric acid.

[0038] The pH of the MTMS product was detected to be 3.0, and the content was 94.8%, wherein the chloride ion content was 35 ppm.

[0039] Comparative Example 2:

[0040] The methanol vaporized from the vaporizer and monomethyltrichlorosilane are introduced into the esterification tower in a ratio of 1.45:1 to carry out esterification reaction, methanol is introduced into the esterification tower from the lower part of the esterification tower, and monomethyltrichlorosilane is sprayed downward from the upper part of the esterification tower; the reaction product after the esterification reaction is introduced into the gas-liquid separation tank, and the separated liquid enters the neutralization reactor, sodium methoxide is added to the neutralization reactor for neutralization reaction, the pH of the reaction liquid is adjusted to 8-9, the reaction liquid is filtered and desalted to obtain the MTMS crude product, and the MTMS crude product is introduced into the distillation tower from the trimethoxy intermediate tank for intermittent distillation, When the MTMS content at the top of the tower reaches a certain level, the distilled product from the top of the tower passes through a glass tube containing a dechlorinating desiccant with a ratio of silicon slag, activated carbon, calcium carbonate powder, and carbide slag of 1:1.25:0.5:3, wherein the mass ratio of methyltrimethoxysilane to the dechlorinating desiccant is (1-2):1, and is collected after cooling to obtain a neutral MTMS finished product. The hydrogen chloride gas separated by a cyclone-type gas-water separator and the hydrogen chloride emitted from the top of the esterification tower are passed through a two-stage washing tower and then introduced into a hydrochloric acid recovery tank, and water is added to the hydrochloric acid recovery tank to prepare hydrochloric acid.

[0041] The pH value of the MTMS product was detected to be 3.5, and the content was 91.3%, wherein the chloride ion content was 22 ppm.

Claims

1. A process for preparing methyltrimethoxysilane, characterized in that: The following steps are involved: (1) Esterification: Methanol vaporized from a vaporizer and monomethyltrichlorosilane are introduced into an esterification tower in a certain proportion to cause an esterification reaction. Methanol is fed into the esterification tower from the bottom, and monomethyltrichlorosilane is sprayed downward from the top of the esterification tower. (2) Separation: The liquid reaction product after the esterification reaction is passed into a cyclone gas-water separator for gas-liquid separation. (3) Neutralization: A portion of the liquid separated by the cyclone gas-water separator is refluxed to the bottom of the esterification tower, and the other portion is neutralized in a neutralization reactor containing sodium methoxide solution from the lower end of the cyclone gas-water separator. The reaction liquid is filtered and desalted to obtain a crude MTMS product. (4) Distillation and drying: The crude MTMS product is passed from the trimethoxy intermediate tank into the distillation tower for intermittent distillation. When the MTMS content at the top of the tower reaches a certain level, the top distillation product passes through a glass tube containing a dechlorination desiccant, is cooled and collected to obtain a neutral MTMS finished product. (5) Acid production: The hydrogen chloride gas separated by the cyclone gas-water separator and the hydrogen chloride escaped from the top of the esterification tower are passed through a two-stage washing tower and then introduced into a hydrochloric acid recovery tank, where water is added to prepare hydrochloric acid.

2. A process and device for preparing methyltrimethoxysilane according to claim 1, characterized in that: The mass ratio of the methanol to monomethyltrichlorosilane is (1.35-1.5):

1.

3. A process for preparing methyltrimethoxysilane according to claim 1, characterized in that: In step (1), the temperature at the top of the esterification tower is controlled at 65-72° C., the temperature in the esterification tower is 72-76° C., the temperature in the esterification tower is 90-95° C., and the pressure in the esterification tower is controlled at 0.55-0.6 MPa.

4. A process for preparing methyltrimethoxysilane according to claim 1, characterized in that: In the step (2), the rotation speed of the cyclone gas-water separator is 2500-3000 rpm, the pressure is 0.15-0.30 MPa, the flow rate is 0.4-1 m / s, the temperature is controlled at 70-80° C., and the hydrogen chloride gas separation efficiency reaches 99.9%.

5. A process for preparing methyltrimethoxysilane according to claim 1, characterized in that: The reflux ratio of the reaction liquid in step (3) is 0.5-1:1, and the pH of the reaction liquid after neutralization is 8-9.

6. A process for preparing methyltrimethoxysilane according to claim 1, characterized in that: In the step (4), the dechlorination desiccant is composed of silicon slag, activated carbon, calcium carbonate powder and carbide slag, and the ratio thereof is 1:(0.5-1.5):0.5:(2-4).

7. A process for preparing methyltrimethoxysilane according to claim 1, characterized in that: The mass ratio of methyltrimethoxysilane prepared in the step (4) to the dechlorination desiccant is (1-2):

1.

8. A device for preparing methyltrimethoxysilane, characterized in that: The esterification tower (1) is connected to a cyclone-type gas-water separator (2), the bottom of the cyclone-type gas-water separator (2) is connected to a neutralization reaction kettle (3) and the top is connected to a hydrochloric acid recovery tank, the neutralization reaction kettle (3) is connected to a distillation tower (4), the outlet end of the distillation tower (4) is connected to a glass tube (5), and the top of the esterification tower (1) is connected to a hydrochloric acid recovery tank (6), wherein a reflux pipe is provided between the cyclone-type gas-water separator (2) and the esterification tower (1).

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