A method for preparing hexamethyldisiloxane

Abstract

This application relates to the field of siloxane preparation, specifically disclosing a method for preparing hexamethyldisiloxane, comprising the following steps: A) Concentrated hydrochloric acid and trimethylchlorosilane are sequentially fed into a hydrolysis reactor for hydrolysis to obtain hydrolysis products; the hydrolysis reactor includes a stirred tank, the bottom wall of which is provided with elastic hollow spheres; B) The obtained hydrolysis products are fed into a heat exchanger, then into a gas-liquid separation tower, and finally into a purification condenser; C) The mixture of hexamethyldisiloxane and concentrated hydrochloric acid obtained from the bottom of the gas-liquid separation tower and the mixture of hydrochloric acid and hexamethyldisiloxane obtained from the bottom of the condenser are fed into a separator for separation; the upper oily liquid is separated into a hexamethyldisiloxane washing tank, and after washing, crude hexamethyldisiloxane is obtained and fed into a hexamethyldisiloxane intermediate tank. The preparation method of this application has the advantage of improving the production efficiency and yield of hexamethyldisiloxane.

Description

Technical Field

[0001] This application relates to the field of siloxanes, and more specifically, to a method for preparing hexamethyldisiloxane. Background Technology

[0002] Organosilicon products have mature applications and are gradually expanding from high-end products to everyday necessities, leading to a surge in demand. Hexamethyldisiloxane (MM) is an important organosilicon product, primarily used in the organic chemical and pharmaceutical industries. It is used as a capping agent for silicone oils, a raw material for silazanes, as an additive for silicone rubber, a defoamer and lubricant in pharmaceuticals, a stationary phase in gas chromatography, an analytical reagent, and a hydrophobic agent. High-quality MM can also serve as a substitute for cleaning agents in precision equipment used in the electronics, defense, and aerospace industries. For example, Dow Corning, a giant in the organosilicon industry, already sells such products, but they are currently not available in China.

[0003] Currently, patent CN111004267A discloses a method for preparing hexamethyldisiloxane, including: A) sequentially feeding concentrated hydrochloric acid and trimethylchlorosilane into a hydrolysis reactor to hydrolyze and obtain hydrolysis products; the pressure of the hydrolysis reaction is 0.05-0.2 MPa; B) feeding the obtained hydrolysis products into a heat exchanger for heating, and then into a gas-liquid separation tower, where hydrogen chloride gas is separated from the hydrolysis products and enters a condenser, where hydrogen chloride gas is collected from the top of the condenser; C) feeding the mixture obtained from the bottom of the gas-liquid separation tower and the mixture obtained from the bottom of the condenser into a separator for separation; the upper oily liquid is separated into a hexamethyldisiloxane washing tank, and after washing, crude hexamethyldisiloxane is obtained; the lower hydrochloric acid water layer is fed into a hydrochloric acid intermediate tank for recycling; D) feeding the obtained crude hexamethyldisiloxane into a distillation tower for separation, where hexamethyldisiloxane is obtained from the top of the tower.

[0004] However, regarding the reaction efficiency of trimethylchlorosilane during hydrolysis, using a traditional stirred reactor requires a certain amount of time for the trimethylchlorosilane to react fully. This is because the position of the trimethylchlorosilane added to the stirred reactor remains essentially unchanged within the reactor, and the stirring process ensures that the trimethylchlorosilane diffuses evenly and reacts completely. Therefore, the efficiency is still not high. Summary of the Invention

[0005] In order to improve the durability of asphalt, this application provides a method for preparing hexamethyldisiloxane.

[0006] A method for preparing hexamethyldisiloxane includes the following steps:

[0007] A) Concentrated hydrochloric acid and trimethylchlorosilane are sequentially fed into a hydrolysis reactor to carry out a hydrolysis reaction and obtain hydrolysis products;

[0008] The hydrolysis reactor includes a stirred tank, on the bottom wall of which is an elastic hollow sphere connected to the bottom wall of the stirred tank. A one-way feed pipe is provided on the bottom wall of the stirred tank, penetrating the bottom wall of the stirred tank and the side wall of the elastic hollow sphere. The side wall of the elastic hollow sphere is also provided with a liquid distribution hole that allows only one-way flow from the inside of the elastic hollow sphere to the outside.

[0009] The mixing vessel is equipped with a pressure plate with multiple through holes, which abuts against or is connected to an elastic hollow sphere; the mixing vessel is equipped with a lifting device for driving the pressure plate to move up and down; a stirring device is provided on the side of the pressure plate away from the elastic hollow sphere.

[0010] The stirred tank is equipped with a trimethylchlorosilane storage tank, which is connected to a one-way feed pipe; the stirred tank is also equipped with a feed port for replenishing concentrated hydrochloric acid and a discharge port for discharging reaction products.

[0011] The pressure of the hydrolysis reaction is 0–0.2 MPa;

[0012] B) The obtained hydrolysis products are fed to a heat exchanger for heating, and then enter a gas-liquid separation tower. Hydrogen chloride gas is separated from the hydrolysis products and enters a purification condenser. Hydrogen chloride gas is collected from the top of the purification condenser, and a mixture of hydrochloric acid and hexamethyldisiloxane is obtained from the bottom of the purification condenser.

[0013] A mixture of hexamethyldisiloxane and concentrated hydrochloric acid is obtained at the bottom of the gas-liquid separation tower;

[0014] C) The mixture of hexamethyldisiloxane and concentrated hydrochloric acid obtained from the bottom of the gas-liquid separator and the mixture of hydrochloric acid and hexamethyldisiloxane obtained from the bottom of the condenser are transported to the separator for separation; the upper oily liquid is separated to the hexamethyldisiloxane washing tank, and after washing, crude hexamethyldisiloxane is obtained and enters the hexamethyldisiloxane intermediate tank.

[0015] The lower layer of hydrochloric acid water is transported to the intermediate hydrochloric acid tank for recycling.

[0016] D) The obtained crude hexamethyldisiloxane is fed to a distillation column for separation. Gas-phase hexamethyldisiloxane is obtained from the top of the column and then condensed to obtain hexamethyldisiloxane.

[0017] By adopting the above technical solution, the raw material trimethylchlorosilane in this invention is fed from a trimethylchlorosilane reservoir into an elastic hollow sphere through a one-way feed pipe. Then, the pressure plate descends, squeezing the elastic hollow sphere, causing the trimethylchlorosilane raw material to enter the reaction vessel through a one-way flow separator and react with concentrated hydrochloric acid to generate hexamethyldisiloxane. When the pressure plate rises, the elastic hollow sphere returns to its original shape, and due to the one-way flow path, trimethylchlorosilane continues to flow from the trimethylchlorosilane reservoir into the elastic hollow sphere, thus continuously and uniformly dispersing the trimethylchlorosilane throughout the stirred vessel.

[0018] Trimethylchlorosilane is uniformly dispersed in the reactor from the beginning, which can greatly improve the reaction efficiency, the degree of reaction completion, and the reaction efficiency and yield of hexamethyldisiloxane.

[0019] Furthermore, the material of the elastic hollow sphere is one of nitrile rubber, chloroprene rubber, and styrene-butadiene rubber.

[0020] Furthermore, the hydrolysis reaction is carried out at a temperature of 25–35°C.

[0021] Furthermore, the temperature difference between the inside and outside of the elastic hollow sphere is 5-10°C, and the temperature inside the elastic hollow sphere is higher than the temperature outside the elastic hollow sphere.

[0022] Furthermore, the temperature inside the elastic hollow sphere is 40-45°C, and the temperature inside the elastic hollow sphere is 35-38°C.

[0023] Furthermore, the temperature inside the elastic hollow sphere is 45°C, and the temperature inside the elastic hollow sphere is 35°C.

[0024] By employing the above technical solution, the temperature inside the elastic hollow sphere is higher than the temperature outside the sphere, resulting in a higher temperature for trimethylchlorosilane than for concentrated hydrochloric acid. When trimethylchlorosilane disperses from the elastic hollow sphere into the concentrated hydrochloric acid solution, the temperature convection caused by the temperature difference drives the trimethylchlorosilane to disperse more rapidly within the reactor. Furthermore, within the temperature range described in this invention, a higher reaction temperature can improve the reaction efficiency of trimethylchlorosilane. The temperature inside the elastic hollow sphere can be controlled by preheating the trimethylchlorosilane injected into the sphere.

[0025] Furthermore, the temperature of the hydrolysis product after heat exchange in step B) is 30–80°C.

[0026] Furthermore, the washing solution used in step C) is water or a weak alkaline aqueous solution;

[0027] The weak base is one or more of sodium carbonate, sodium bicarbonate, and potassium carbonate.

[0028] Furthermore, the mass concentration of the concentrated hydrochloric acid is >10%.

[0029] Furthermore, the mass ratio of the hydrochloric acid to trimethylchlorosilane is 1:(2-4).

[0030] Furthermore, the trimethylchlorosilane contains 0.1 to 1 wt% of powder additives, which include ultrafine calcium hydroxide and ultrafine sodium bicarbonate powders in a mass ratio of 1:2 to 6.

[0031] The powdered additives are composed of ultrafine powders and are present at a very low concentration in trimethylchlorosilane, thus preventing clogging in the distribution holes of the elastic hollow spheres. Secondly, when the ultrafine calcium hydroxide and ultrafine sodium bicarbonate powders are dispersed from the elastic hollow spheres into concentrated hydrochloric acid along with the trimethylchlorosilane, they react with the hydrochloric acid. This reaction generates heat and bubbles, allowing the trimethylchlorosilane dispersed in the concentrated hydrochloric acid to be dispersed more quickly and evenly through the stirring action of the bubbles. Furthermore, it generates higher local reaction temperatures and consumes some of the hydrochloric acid produced in the reaction, further improving reaction efficiency. Moreover, the generated gas helps increase the pressure in the reactor, resulting in a greater pressure drop when the hydrolysis products are transported to the gas-liquid separation tower, facilitating the overflow of hydrogen chloride and further increasing production efficiency.

[0032] In summary, this application has the following beneficial effects:

[0033] By employing the elastic hollow sphere feeding method described above, the uniformity of trimethylchlorosilane's addition to the stirred reactor is ensured from the moment of addition, thereby improving the reaction efficiency of trimethylchlorosilane to a certain extent. Secondly, the added powdered additive is sprayed into the concentrated hydrochloric acid along with the trimethylchlorosilane within the stirred reactor, reacting with the hydrochloric acid to generate heat and bubbles, thus improving the mixing uniformity between trimethylchlorosilane and concentrated hydrochloric acid and enhancing reaction efficiency. Attached Figure Description

[0034] Figure 1 This is a cross-sectional view of the hydrolysis reactor in Example 1.

[0035] Reference numerals in the attached drawings: 1. Stirring vessel body; 2. Elastic hollow sphere; 3. One-way feed pipe; 4. Separating hole; 5. Pressure plate; 6. Stirring device; 7. Lifting device; 8. Trimethylchlorosilane storage container. Detailed Implementation

[0036] The present application will be further described in detail below with reference to the embodiments.

[0037] Example 1

[0038] A method for preparing hexamethyldisiloxane includes the following steps:

[0039] A) 36.5% concentrated hydrochloric acid and 99% pure trimethylchlorosilane are sequentially fed into a hydrolysis reactor, wherein the mass ratio of concentrated hydrochloric acid to trimethylchlorosilane is 1:3, and a hydrolysis reaction is carried out to obtain a mixture of hexamethyldisiloxane, concentrated hydrochloric acid, and hydrogen chloride gas generated by hydrolysis.

[0040] The hydrolysis reaction occurs at a temperature of 35℃. The hydrolysis products after heat exchange are at a temperature of 45℃.

[0041] Among them, reference Figure 1 The hydrolysis reactor includes a stirred tank 1. An elastic hollow sphere 2 is mounted on the bottom wall of the stirred tank 1, and the elastic hollow sphere 2 is connected to the bottom wall of the stirred tank 1. A one-way feed pipe 3 is provided on the bottom wall of the stirred tank 1, penetrating both the bottom wall of the stirred tank 1 and the side wall of the elastic hollow sphere 2. A liquid distribution hole 4 is also provided on the side wall of the elastic hollow sphere 2, allowing only one-way flow from the inside of the elastic hollow sphere 2 to the outside. In this embodiment, the one-way flow liquid distribution hole 4 can be obtained by installing a one-way flow nozzle. In another embodiment, the one-way flow liquid distribution hole 4 can be obtained by setting a blocking block inside the liquid distribution hole 4 that can only be opened by flipping it outwards; the blocking block can also be a rubber block.

[0042] The mixing vessel body 1 is equipped with a pressure plate 5 having multiple through holes, which abuts against or is connected to the elastic hollow sphere 2. A lifting device 7 is provided on the mixing vessel body 1 to drive the pressure plate 5 to move up and down. A stirring device 6 is provided on the side of the pressure plate 5 away from the elastic hollow sphere 2. In this embodiment, the lifting device 7 is a drive cylinder mounted on the mixing vessel body 1. The stirring device 6 is a stirring paddle driven by a motor.

[0043] A trimethylchlorosilane reservoir 8 is provided outside the stirred tank body 1, and the trimethylchlorosilane reservoir 8 is connected to the one-way feed pipe 3; the stirred tank body 1 is also provided with a feed port for replenishing concentrated hydrochloric acid and a discharge port for discharging reaction products.

[0044] The material of the elastic hollow sphere 2 is nitrile rubber.

[0045] The temperature inside the elastic hollow sphere 2 is 40℃, and the temperature inside the elastic hollow sphere 2 is 35℃.

[0046] B) The obtained hydrolysis products are fed to a heat exchanger for heating, and then enter a gas-liquid separation tower. Hydrogen chloride gas is separated from the hydrolysis products and enters a purification condenser. Hydrogen chloride gas is collected from the top of the purification condenser, and a mixture of hydrochloric acid and hexamethyldisiloxane is obtained from the bottom of the purification condenser.

[0047] A mixture of hexamethyldisiloxane and concentrated hydrochloric acid is obtained at the bottom of the gas-liquid separation tower;

[0048] C) The mixture of hexamethyldisiloxane and concentrated hydrochloric acid obtained from the bottom of the gas-liquid separator and the mixture of hydrochloric acid and hexamethyldisiloxane obtained from the bottom of the condenser are transported to the separator for separation; the upper oily liquid is separated to the hexamethyldisiloxane washing tank, and after washing, crude hexamethyldisiloxane is obtained and enters the hexamethyldisiloxane intermediate tank.

[0049] The lower layer of hydrochloric acid water is transported to the intermediate hydrochloric acid tank for recycling.

[0050] D) The obtained crude hexamethyldisiloxane is fed to a distillation column for separation. Gas-phase hexamethyldisiloxane is obtained from the top of the column and then condensed to obtain hexamethyldisiloxane.

[0051] The number of portions mentioned in this embodiment refers to the mass flow rate per unit time by weight.

[0052] Example 2

[0053] A method for preparing hexamethyldisiloxane includes the following steps:

[0054] A) 36.5% concentrated hydrochloric acid and 99% pure trimethylchlorosilane are sequentially fed into a hydrolysis reactor, wherein the mass ratio of concentrated hydrochloric acid to trimethylchlorosilane is 1:3, and a hydrolysis reaction is carried out to obtain a mixture of hexamethyldisiloxane, concentrated hydrochloric acid, and hydrogen chloride gas generated by hydrolysis.

[0055] The hydrolysis reaction occurs at a temperature of 35℃. The hydrolysis products after heat exchange are at a temperature of 45℃.

[0056] The hydrolysis reactor includes a stirred tank 1, on which an elastic hollow sphere 2 is provided on the bottom wall of the stirred tank 1 and is connected to the bottom wall of the stirred tank 1; a one-way feed pipe 3 is provided on the bottom wall of the stirred tank 1, penetrating the bottom wall of the stirred tank 1 and the side wall of the elastic hollow sphere 2; and a liquid distribution hole 4 is provided on the side wall of the elastic hollow sphere 2, which allows only one-way flow from the inside of the elastic hollow sphere 2 to the outside.

[0057] The mixing vessel body 1 is provided with a pressure plate 5 with multiple through holes, and the pressure plate 5 abuts against or is connected to the elastic hollow ball 2; the mixing vessel body 1 is provided with a lifting device 7 for driving the pressure plate 5 to move up and down; a stirring device 6 is provided on the side of the pressure plate 5 away from the elastic hollow ball 2.

[0058] A trimethylchlorosilane reservoir 8 is provided outside the stirred tank body 1, and the trimethylchlorosilane reservoir 8 is connected to the one-way feed pipe 3; the stirred tank body 1 is also provided with a feed port for replenishing concentrated hydrochloric acid and a discharge port for discharging reaction products.

[0059] The material of the elastic hollow sphere 2 is nitrile rubber.

[0060] The temperature inside the elastic hollow sphere 2 is 45℃, and the temperature inside the elastic hollow sphere 2 is 35℃.

[0061] B) The obtained hydrolysis products are fed to a heat exchanger for heating, and then enter a gas-liquid separation tower. Hydrogen chloride gas is separated from the hydrolysis products and enters a purification condenser. Hydrogen chloride gas is collected from the top of the purification condenser, and a mixture of hydrochloric acid and hexamethyldisiloxane is obtained from the bottom of the purification condenser.

[0062] A mixture of hexamethyldisiloxane and concentrated hydrochloric acid is obtained at the bottom of the gas-liquid separation tower;

[0063] C) The mixture of hexamethyldisiloxane and concentrated hydrochloric acid obtained from the bottom of the gas-liquid separator and the mixture of hydrochloric acid and hexamethyldisiloxane obtained from the bottom of the condenser are transported to the separator for separation; the upper oily liquid is separated to the hexamethyldisiloxane washing tank, and after washing, crude hexamethyldisiloxane is obtained and enters the hexamethyldisiloxane intermediate tank.

[0064] The lower layer of hydrochloric acid water is transported to the intermediate hydrochloric acid tank for recycling.

[0065] D) The obtained crude hexamethyldisiloxane is fed to a distillation column for separation. Gas-phase hexamethyldisiloxane is obtained from the top of the column and then condensed to obtain hexamethyldisiloxane.

[0066] The number of portions mentioned in this embodiment refers to the mass flow rate per unit time by weight.

[0067] Example 3

[0068] A method for preparing hexamethyldisiloxane includes the following steps:

[0069] A) 36.5% concentrated hydrochloric acid and 99% pure trimethylchlorosilane are sequentially fed into a hydrolysis reactor, wherein the mass ratio of concentrated hydrochloric acid to trimethylchlorosilane is 1:3, and a hydrolysis reaction is carried out to obtain a mixture of hexamethyldisiloxane, concentrated hydrochloric acid, and hydrogen chloride gas generated by hydrolysis.

[0070] The hydrolysis reaction occurs at a temperature of 35℃. The hydrolysis products after heat exchange are at a temperature of 45℃.

[0071] The hydrolysis reactor includes a stirred tank 1, on which an elastic hollow sphere 2 is provided on the bottom wall of the stirred tank 1 and is connected to the bottom wall of the stirred tank 1; a one-way feed pipe 3 is provided on the bottom wall of the stirred tank 1, penetrating the bottom wall of the stirred tank 1 and the side wall of the elastic hollow sphere 2; and a liquid distribution hole 4 is provided on the side wall of the elastic hollow sphere 2, which allows only one-way flow from the inside of the elastic hollow sphere 2 to the outside.

[0072] The mixing vessel body 1 is provided with a pressure plate 5 with multiple through holes, and the pressure plate 5 abuts against or is connected to the elastic hollow ball 2; the mixing vessel body 1 is provided with a lifting device 7 for driving the pressure plate 5 to move up and down; a stirring device 6 is provided on the side of the pressure plate 5 away from the elastic hollow ball 2.

[0073] A trimethylchlorosilane reservoir 8 is provided outside the stirred tank body 1, and the trimethylchlorosilane reservoir 8 is connected to the one-way feed pipe 3; the stirred tank body 1 is also provided with a feed port for replenishing concentrated hydrochloric acid and a discharge port for discharging reaction products.

[0074] The material of the elastic hollow sphere 2 is nitrile rubber.

[0075] The temperature inside the elastic hollow sphere 2 is 40℃, and the temperature inside the elastic hollow sphere 2 is 35℃.

[0076] B) The obtained hydrolysis products are fed to a heat exchanger for heating, and then enter a gas-liquid separation tower. Hydrogen chloride gas is separated from the hydrolysis products and enters a purification condenser. Hydrogen chloride gas is collected from the top of the purification condenser, and a mixture of hydrochloric acid and hexamethyldisiloxane is obtained from the bottom of the purification condenser.

[0077] A mixture of hexamethyldisiloxane and concentrated hydrochloric acid is obtained at the bottom of the gas-liquid separation tower;

[0078] C) The mixture of hexamethyldisiloxane and concentrated hydrochloric acid obtained from the bottom of the gas-liquid separator and the mixture of hydrochloric acid and hexamethyldisiloxane obtained from the bottom of the condenser are transported to the separator for separation; the upper oily liquid is separated to the hexamethyldisiloxane washing tank, and after washing, crude hexamethyldisiloxane is obtained and enters the hexamethyldisiloxane intermediate tank.

[0079] The lower layer of hydrochloric acid water is transported to the intermediate hydrochloric acid tank for recycling.

[0080] D) The obtained crude hexamethyldisiloxane is fed to a distillation column for separation. Gas-phase hexamethyldisiloxane is obtained from the top of the column and then condensed to obtain hexamethyldisiloxane.

[0081] The number of portions mentioned in this embodiment refers to the mass flow rate per unit time by weight.

[0082] Example 4

[0083] A method for preparing hexamethyldisiloxane includes the following steps:

[0084] A) 36.5% concentrated hydrochloric acid and 99% pure trimethylchlorosilane are sequentially fed into a hydrolysis reactor, wherein the mass ratio of concentrated hydrochloric acid to trimethylchlorosilane is 1:3, and a hydrolysis reaction is carried out to obtain a mixture of hexamethyldisiloxane, concentrated hydrochloric acid, and hydrogen chloride gas generated by hydrolysis.

[0085] The hydrolysis reaction occurs at a temperature of 35℃. The hydrolysis products after heat exchange are at a temperature of 45℃.

[0086] The hydrolysis reactor includes a stirred tank 1, on which an elastic hollow sphere 2 is provided on the bottom wall of the stirred tank 1 and is connected to the bottom wall of the stirred tank 1; a one-way feed pipe 3 is provided on the bottom wall of the stirred tank 1, penetrating the bottom wall of the stirred tank 1 and the side wall of the elastic hollow sphere 2; and a liquid distribution hole 4 is provided on the side wall of the elastic hollow sphere 2, which allows only one-way flow from the inside of the elastic hollow sphere 2 to the outside.

[0087] The mixing vessel body 1 is provided with a pressure plate 5 with multiple through holes, and the pressure plate 5 abuts against or is connected to the elastic hollow ball 2; the mixing vessel body 1 is provided with a lifting device 7 for driving the pressure plate 5 to move up and down; a stirring device 6 is provided on the side of the pressure plate 5 away from the elastic hollow ball 2.

[0088] A trimethylchlorosilane reservoir 8 is provided outside the stirred tank body 1, and the trimethylchlorosilane reservoir 8 is connected to the one-way feed pipe 3; the stirred tank body 1 is also provided with a feed port for replenishing concentrated hydrochloric acid and a discharge port for discharging reaction products.

[0089] The material of the elastic hollow sphere 2 is neoprene rubber.

[0090] The temperature inside the elastic hollow sphere 2 is 40℃, and the temperature inside the elastic hollow sphere 2 is 38℃.

[0091] B) The obtained hydrolysis products are fed to a heat exchanger for heating, and then enter a gas-liquid separation tower. Hydrogen chloride gas is separated from the hydrolysis products and enters a purification condenser. Hydrogen chloride gas is collected from the top of the purification condenser, and a mixture of hydrochloric acid and hexamethyldisiloxane is obtained from the bottom of the purification condenser.

[0092] A mixture of hexamethyldisiloxane and concentrated hydrochloric acid is obtained at the bottom of the gas-liquid separation tower;

[0093] C) The mixture of hexamethyldisiloxane and concentrated hydrochloric acid obtained from the bottom of the gas-liquid separator and the mixture of hydrochloric acid and hexamethyldisiloxane obtained from the bottom of the condenser are transported to the separator for separation; the upper oily liquid is separated to the hexamethyldisiloxane washing tank, and after washing, crude hexamethyldisiloxane is obtained and enters the hexamethyldisiloxane intermediate tank.

[0094] The lower layer of hydrochloric acid water is transported to the intermediate hydrochloric acid tank for recycling.

[0095] D) The obtained crude hexamethyldisiloxane is fed to a distillation column for separation. Gas-phase hexamethyldisiloxane is obtained from the top of the column and then condensed to obtain hexamethyldisiloxane.

[0096] The number of portions mentioned in this embodiment refers to the mass flow rate per unit time by weight.

[0097] Example 5

[0098] A method for preparing hexamethyldisiloxane includes the following steps:

[0099] A) 36.5% concentrated hydrochloric acid and 99% pure trimethylchlorosilane are sequentially fed into a hydrolysis reactor, wherein the mass ratio of concentrated hydrochloric acid to trimethylchlorosilane is 1:3, and a hydrolysis reaction is carried out to obtain a mixture of hexamethyldisiloxane, concentrated hydrochloric acid, and hydrogen chloride gas generated by hydrolysis.

[0100] The hydrolysis reaction occurs at a temperature of 35℃. The hydrolysis products after heat exchange are at a temperature of 45℃.

[0101] The hydrolysis reactor includes a stirred tank 1, on the bottom wall of which is a hollow elastic sphere 2 connected to the bottom wall of the stirred tank 1. A one-way feed pipe 3 is provided on the bottom wall of the stirred tank 1, penetrating the bottom wall of the stirred tank 1 and the side wall of the hollow elastic sphere 2. The side wall of the hollow elastic sphere 2 is also provided with a liquid distribution hole 4 that allows only one-way flow from the inside of the hollow elastic sphere 2 to the outside. In this embodiment, there is one hollow elastic sphere 2. In other embodiments, there may be multiple hollow elastic spheres 2.

[0102] The mixing vessel body 1 is provided with a pressure plate 5 with multiple through holes, and the pressure plate 5 abuts against or is connected to the elastic hollow ball 2; the mixing vessel body 1 is provided with a lifting device 7 for driving the pressure plate 5 to move up and down; a stirring device 6 is provided on the side of the pressure plate 5 away from the elastic hollow ball 2.

[0103] A trimethylchlorosilane reservoir 8 is provided outside the stirred tank body 1, and the trimethylchlorosilane reservoir 8 is connected to the one-way feed pipe 3; the stirred tank body 1 is also provided with a feed port for replenishing concentrated hydrochloric acid and a discharge port for discharging reaction products.

[0104] The material of the elastic hollow sphere 2 is nitrile rubber.

[0105] The temperature inside the elastic hollow sphere 2 is 45℃, and the temperature inside the elastic hollow sphere 2 is 38℃.

[0106] B) The obtained hydrolysis products are fed to a heat exchanger for heating, and then enter a gas-liquid separation tower. Hydrogen chloride gas is separated from the hydrolysis products and enters a purification condenser. Hydrogen chloride gas is collected from the top of the purification condenser, and a mixture of hydrochloric acid and hexamethyldisiloxane is obtained from the bottom of the purification condenser.

[0107] A mixture of hexamethyldisiloxane and concentrated hydrochloric acid is obtained at the bottom of the gas-liquid separation tower;

[0108] C) The mixture of hexamethyldisiloxane and concentrated hydrochloric acid obtained from the bottom of the gas-liquid separator and the mixture of hydrochloric acid and hexamethyldisiloxane obtained from the bottom of the condenser are transported to the separator for separation; the upper oily liquid is separated to the hexamethyldisiloxane washing tank, and after washing, crude hexamethyldisiloxane is obtained and enters the hexamethyldisiloxane intermediate tank.

[0109] The lower layer of hydrochloric acid water is transported to the intermediate hydrochloric acid tank for recycling.

[0110] D) The obtained crude hexamethyldisiloxane is fed to a distillation column for separation. Gas-phase hexamethyldisiloxane is obtained from the top of the column and then condensed to obtain hexamethyldisiloxane.

[0111] The number of portions mentioned in this embodiment refers to the mass flow rate per unit time by weight.

[0112] Example 6

[0113] A method for preparing hexamethyldisiloxane includes the following steps:

[0114] A) 36.5% concentrated hydrochloric acid and 99% pure trimethylchlorosilane are sequentially fed into a hydrolysis reactor, wherein the mass ratio of concentrated hydrochloric acid to trimethylchlorosilane is 1:4, and a hydrolysis reaction is carried out to obtain a mixture of hexamethyldisiloxane, concentrated hydrochloric acid, and hydrogen chloride gas generated by hydrolysis.

[0115] Trimethylchlorosilane contains 0.5 wt% powder additives, which include ultrafine calcium hydroxide and ultrafine sodium bicarbonate powders in a mass ratio of 1:5.

[0116] The hydrolysis reaction occurs at a temperature of 35℃. The hydrolysis products after heat exchange are at a temperature of 45℃.

[0117] The hydrolysis reactor includes a stirred tank 1, on which an elastic hollow sphere 2 is provided on the bottom wall of the stirred tank 1 and is connected to the bottom wall of the stirred tank 1; a one-way feed pipe 3 is provided on the bottom wall of the stirred tank 1, penetrating the bottom wall of the stirred tank 1 and the side wall of the elastic hollow sphere 2; and a liquid distribution hole 4 is provided on the side wall of the elastic hollow sphere 2, which allows only one-way flow from the inside of the elastic hollow sphere 2 to the outside.

[0118] The mixing vessel body 1 is provided with a pressure plate 5 with multiple through holes, and the pressure plate 5 abuts against or is connected to the elastic hollow ball 2; the mixing vessel body 1 is provided with a lifting device 7 for driving the pressure plate 5 to move up and down; a stirring device 6 is provided on the side of the pressure plate 5 away from the elastic hollow ball 2.

[0119] A trimethylchlorosilane reservoir 8 is provided outside the stirred tank body 1, and the trimethylchlorosilane reservoir 8 is connected to the one-way feed pipe 3; the stirred tank body 1 is also provided with a feed port for replenishing concentrated hydrochloric acid and a discharge port for discharging reaction products.

[0120] The material of the elastic hollow sphere 2 is nitrile rubber.

[0121] The temperature inside the elastic hollow sphere 2 is 40℃, and the temperature inside the elastic hollow sphere 2 is 35℃.

[0122] B) The obtained hydrolysis products are fed to a heat exchanger for heating, and then enter a gas-liquid separation tower. Hydrogen chloride gas is separated from the hydrolysis products and enters a purification condenser. Hydrogen chloride gas is collected from the top of the purification condenser, and a mixture of hydrochloric acid and hexamethyldisiloxane is obtained from the bottom of the purification condenser.

[0123] A mixture of hexamethyldisiloxane and concentrated hydrochloric acid is obtained at the bottom of the gas-liquid separation tower;

[0124] C) The mixture of hexamethyldisiloxane and concentrated hydrochloric acid obtained from the bottom of the gas-liquid separator and the mixture of hydrochloric acid and hexamethyldisiloxane obtained from the bottom of the condenser are transported to the separator for separation; the upper oily liquid is separated to the hexamethyldisiloxane washing tank, and after washing, crude hexamethyldisiloxane is obtained and enters the hexamethyldisiloxane intermediate tank.

[0125] The lower layer of hydrochloric acid water is transported to the intermediate hydrochloric acid tank for recycling.

[0126] D) The obtained crude hexamethyldisiloxane is fed to a distillation column for separation. Gas-phase hexamethyldisiloxane is obtained from the top of the column and then condensed to obtain hexamethyldisiloxane.

[0127] The number of portions mentioned in this embodiment refers to the mass flow rate per unit time by weight.

[0128] Example 7

[0129] A method for preparing hexamethyldisiloxane includes the following steps:

[0130] A) 36.5% concentrated hydrochloric acid and 99% pure trimethylchlorosilane are sequentially fed into a hydrolysis reactor, wherein the mass ratio of concentrated hydrochloric acid to trimethylchlorosilane is 1:3, and a hydrolysis reaction is carried out to obtain a mixture of hexamethyldisiloxane, concentrated hydrochloric acid, and hydrogen chloride gas generated by hydrolysis.

[0131] Trimethylchlorosilane contains 1 wt% powder additives, which include ultrafine calcium hydroxide and ultrafine sodium bicarbonate powders in a mass ratio of 1:5.

[0132] The hydrolysis reaction occurs at a temperature of 35℃. The hydrolysis products after heat exchange are at a temperature of 45℃.

[0133] The hydrolysis reactor includes a stirred tank 1, on which an elastic hollow sphere 2 is provided on the bottom wall of the stirred tank 1 and is connected to the bottom wall of the stirred tank 1; a one-way feed pipe 3 is provided on the bottom wall of the stirred tank 1, penetrating the bottom wall of the stirred tank 1 and the side wall of the elastic hollow sphere 2; and a liquid distribution hole 4 is provided on the side wall of the elastic hollow sphere 2, which allows only one-way flow from the inside of the elastic hollow sphere 2 to the outside.

[0134] The mixing vessel body 1 is provided with a pressure plate 5 with multiple through holes, and the pressure plate 5 abuts against or is connected to the elastic hollow ball 2; the mixing vessel body 1 is provided with a lifting device 7 for driving the pressure plate 5 to move up and down; a stirring device 6 is provided on the side of the pressure plate 5 away from the elastic hollow ball 2.

[0135] A trimethylchlorosilane reservoir 8 is provided outside the stirred tank body 1, and the trimethylchlorosilane reservoir 8 is connected to the one-way feed pipe 3; the stirred tank body 1 is also provided with a feed port for replenishing concentrated hydrochloric acid and a discharge port for discharging reaction products.

[0136] The material of the elastic hollow sphere 2 is styrene-butadiene rubber.

[0137] The temperature inside the elastic hollow sphere 2 is 40℃, and the temperature inside the elastic hollow sphere 2 is 35℃.

[0138] B) The obtained hydrolysis products are fed to a heat exchanger for heating, and then enter a gas-liquid separation tower. Hydrogen chloride gas is separated from the hydrolysis products and enters a purification condenser. Hydrogen chloride gas is collected from the top of the purification condenser, and a mixture of hydrochloric acid and hexamethyldisiloxane is obtained from the bottom of the purification condenser.

[0139] A mixture of hexamethyldisiloxane and concentrated hydrochloric acid is obtained at the bottom of the gas-liquid separation tower;

[0140] C) The mixture of hexamethyldisiloxane and concentrated hydrochloric acid obtained from the bottom of the gas-liquid separator and the mixture of hydrochloric acid and hexamethyldisiloxane obtained from the bottom of the condenser are transported to the separator for separation; the upper oily liquid is separated to the hexamethyldisiloxane washing tank, and after washing, crude hexamethyldisiloxane is obtained and enters the hexamethyldisiloxane intermediate tank.

[0141] The lower layer of hydrochloric acid water is transported to the intermediate hydrochloric acid tank for recycling.

[0142] D) The obtained crude hexamethyldisiloxane is fed to a distillation column for separation. Gas-phase hexamethyldisiloxane is obtained from the top of the column and then condensed to obtain hexamethyldisiloxane.

[0143] The number of portions mentioned in this embodiment refers to the mass flow rate per unit time by weight.

[0144] Example 8

[0145] A method for preparing hexamethyldisiloxane includes the following steps:

[0146] A) 36.5% concentrated hydrochloric acid and 99% pure trimethylchlorosilane are sequentially fed into a hydrolysis reactor, wherein the mass ratio of concentrated hydrochloric acid to trimethylchlorosilane is 1:3, and a hydrolysis reaction is carried out to obtain a mixture of hexamethyldisiloxane, concentrated hydrochloric acid, and hydrogen chloride gas generated by hydrolysis.

[0147] Trimethylchlorosilane contains 0.5 wt% powder additives, which include ultrafine calcium hydroxide and ultrafine sodium bicarbonate powders in a mass ratio of 1:4.

[0148] The hydrolysis reaction occurs at a temperature of 35℃. The hydrolysis products after heat exchange are at a temperature of 45℃.

[0149] The hydrolysis reactor includes a stirred tank 1, on which an elastic hollow sphere 2 is provided on the bottom wall of the stirred tank 1 and is connected to the bottom wall of the stirred tank 1; a one-way feed pipe 3 is provided on the bottom wall of the stirred tank 1, penetrating the bottom wall of the stirred tank 1 and the side wall of the elastic hollow sphere 2; and a liquid distribution hole 4 is provided on the side wall of the elastic hollow sphere 2, which allows only one-way flow from the inside of the elastic hollow sphere 2 to the outside.

[0150] The mixing vessel body 1 is provided with a pressure plate 5 with multiple through holes, and the pressure plate 5 abuts against or is connected to the elastic hollow ball 2; the mixing vessel body 1 is provided with a lifting device 7 for driving the pressure plate 5 to move up and down; a stirring device 6 is provided on the side of the pressure plate 5 away from the elastic hollow ball 2.

[0151] A trimethylchlorosilane reservoir 8 is provided outside the stirred tank body 1, and the trimethylchlorosilane reservoir 8 is connected to the one-way feed pipe 3; the stirred tank body 1 is also provided with a feed port for replenishing concentrated hydrochloric acid and a discharge port for discharging reaction products.

[0152] The material of the elastic hollow sphere 2 is nitrile rubber.

[0153] The temperature inside the elastic hollow sphere 2 is 40℃, and the temperature inside the elastic hollow sphere 2 is 35℃.

[0154] B) The obtained hydrolysis products are fed to a heat exchanger for heating, and then enter a gas-liquid separation tower. Hydrogen chloride gas is separated from the hydrolysis products and enters a purification condenser. Hydrogen chloride gas is collected from the top of the purification condenser, and a mixture of hydrochloric acid and hexamethyldisiloxane is obtained from the bottom of the purification condenser.

[0155] A mixture of hexamethyldisiloxane and concentrated hydrochloric acid is obtained at the bottom of the gas-liquid separation tower;

[0156] C) The mixture of hexamethyldisiloxane and concentrated hydrochloric acid obtained from the bottom of the gas-liquid separator and the mixture of hydrochloric acid and hexamethyldisiloxane obtained from the bottom of the condenser are transported to the separator for separation; the upper oily liquid is separated to the hexamethyldisiloxane washing tank, and after washing, crude hexamethyldisiloxane is obtained and enters the hexamethyldisiloxane intermediate tank.

[0157] The lower layer of hydrochloric acid water is transported to the intermediate hydrochloric acid tank for recycling.

[0158] D) The obtained crude hexamethyldisiloxane is fed to a distillation column for separation. Gas-phase hexamethyldisiloxane is obtained from the top of the column and then condensed to obtain hexamethyldisiloxane.

[0159] The number of portions mentioned in this embodiment refers to the mass flow rate per unit time by weight.

[0160] Example 9

[0161] A method for preparing hexamethyldisiloxane includes the following steps:

[0162] A) 36.5% concentrated hydrochloric acid and 99% pure trimethylchlorosilane are sequentially fed into a hydrolysis reactor, wherein the mass ratio of concentrated hydrochloric acid to trimethylchlorosilane is 1:3, and a hydrolysis reaction is carried out to obtain a mixture of hexamethyldisiloxane, concentrated hydrochloric acid, and hydrogen chloride gas generated by hydrolysis.

[0163] Trimethylchlorosilane contains 1 wt% powder additives, which include ultrafine calcium hydroxide and ultrafine sodium bicarbonate powders in a mass ratio of 1:3.

[0164] The hydrolysis reaction occurs at a temperature of 35℃. The hydrolysis products after heat exchange are at a temperature of 45℃.

[0165] The hydrolysis reactor includes a stirred tank 1, on which an elastic hollow sphere 2 is provided on the bottom wall of the stirred tank 1 and is connected to the bottom wall of the stirred tank 1; a one-way feed pipe 3 is provided on the bottom wall of the stirred tank 1, penetrating the bottom wall of the stirred tank 1 and the side wall of the elastic hollow sphere 2; and a liquid distribution hole 4 is provided on the side wall of the elastic hollow sphere 2, which allows only one-way flow from the inside of the elastic hollow sphere 2 to the outside.

[0166] The mixing vessel body 1 is provided with a pressure plate 5 with multiple through holes, and the pressure plate 5 abuts against or is connected to the elastic hollow ball 2; the mixing vessel body 1 is provided with a lifting device 7 for driving the pressure plate 5 to move up and down; a stirring device 6 is provided on the side of the pressure plate 5 away from the elastic hollow ball 2.

[0167] A trimethylchlorosilane reservoir 8 is provided outside the stirred tank body 1, and the trimethylchlorosilane reservoir 8 is connected to the one-way feed pipe 3; the stirred tank body 1 is also provided with a feed port for replenishing concentrated hydrochloric acid and a discharge port for discharging reaction products.

[0168] The material of the elastic hollow sphere 2 is nitrile rubber.

[0169] The temperature inside the elastic hollow sphere 2 is 40℃, and the temperature inside the elastic hollow sphere 2 is 35℃.

[0170] B) The obtained hydrolysis products are fed to a heat exchanger for heating, and then enter a gas-liquid separation tower. Hydrogen chloride gas is separated from the hydrolysis products and enters a purification condenser. Hydrogen chloride gas is collected from the top of the purification condenser, and a mixture of hydrochloric acid and hexamethyldisiloxane is obtained from the bottom of the purification condenser.

[0171] A mixture of hexamethyldisiloxane and concentrated hydrochloric acid is obtained at the bottom of the gas-liquid separation tower;

[0172] C) The mixture of hexamethyldisiloxane and concentrated hydrochloric acid obtained from the bottom of the gas-liquid separator and the mixture of hydrochloric acid and hexamethyldisiloxane obtained from the bottom of the condenser are transported to the separator for separation; the upper oily liquid is separated to the hexamethyldisiloxane washing tank, and after washing, crude hexamethyldisiloxane is obtained and enters the hexamethyldisiloxane intermediate tank.

[0173] The lower layer of hydrochloric acid water is transported to the intermediate hydrochloric acid tank for recycling.

[0174] D) The obtained crude hexamethyldisiloxane is fed to a distillation column for separation. Gas-phase hexamethyldisiloxane is obtained from the top of the column and then condensed to obtain hexamethyldisiloxane.

[0175] The number of portions mentioned in this embodiment refers to the mass flow rate per unit time by weight.

[0176] Example 10

[0177] A method for preparing hexamethyldisiloxane includes the following steps:

[0178] A) 36.5% concentrated hydrochloric acid and 99% pure trimethylchlorosilane are sequentially fed into a hydrolysis reactor, wherein the mass ratio of concentrated hydrochloric acid to trimethylchlorosilane is 1:3, and a hydrolysis reaction is carried out to obtain a mixture of hexamethyldisiloxane, concentrated hydrochloric acid, and hydrogen chloride gas generated by hydrolysis.

[0179] Trimethylchlorosilane contains 0.5 wt% powder additives, which include ultrafine calcium hydroxide and ultrafine sodium bicarbonate powders in a mass ratio of 1:6.

[0180] The hydrolysis reaction occurs at a temperature of 35℃. The hydrolysis products after heat exchange are at a temperature of 45℃.

[0181] The hydrolysis reactor includes a stirred tank 1, on which an elastic hollow sphere 2 is provided on the bottom wall of the stirred tank 1 and is connected to the bottom wall of the stirred tank 1; a one-way feed pipe 3 is provided on the bottom wall of the stirred tank 1, penetrating the bottom wall of the stirred tank 1 and the side wall of the elastic hollow sphere 2; and a liquid distribution hole 4 is provided on the side wall of the elastic hollow sphere 2, which allows only one-way flow from the inside of the elastic hollow sphere 2 to the outside.

[0182] The mixing vessel body 1 is provided with a pressure plate 5 with multiple through holes, and the pressure plate 5 abuts against or is connected to the elastic hollow ball 2; the mixing vessel body 1 is provided with a lifting device 7 for driving the pressure plate 5 to move up and down; a stirring device 6 is provided on the side of the pressure plate 5 away from the elastic hollow ball 2.

[0183] A trimethylchlorosilane reservoir 8 is provided outside the stirred tank body 1, and the trimethylchlorosilane reservoir 8 is connected to the one-way feed pipe 3; the stirred tank body 1 is also provided with a feed port for replenishing concentrated hydrochloric acid and a discharge port for discharging reaction products.

[0184] The material of the elastic hollow sphere 2 is nitrile rubber.

[0185] The temperature inside the elastic hollow sphere 2 is 40℃, and the temperature inside the elastic hollow sphere 2 is 35℃.

[0186] B) The obtained hydrolysis products are fed to a heat exchanger for heating, and then enter a gas-liquid separation tower. Hydrogen chloride gas is separated from the hydrolysis products and enters a purification condenser. Hydrogen chloride gas is collected from the top of the purification condenser, and a mixture of hydrochloric acid and hexamethyldisiloxane is obtained from the bottom of the purification condenser.

[0187] A mixture of hexamethyldisiloxane and concentrated hydrochloric acid is obtained at the bottom of the gas-liquid separation tower;

[0188] C) The mixture of hexamethyldisiloxane and concentrated hydrochloric acid obtained from the bottom of the gas-liquid separator and the mixture of hydrochloric acid and hexamethyldisiloxane obtained from the bottom of the condenser are transported to the separator for separation; the upper oily liquid is separated to the hexamethyldisiloxane washing tank, and after washing, crude hexamethyldisiloxane is obtained and enters the hexamethyldisiloxane intermediate tank.

[0189] The lower layer of hydrochloric acid water is transported to the intermediate hydrochloric acid tank for recycling.

[0190] D) The obtained crude hexamethyldisiloxane is fed to a distillation column for separation. Gas-phase hexamethyldisiloxane is obtained from the top of the column and then condensed to obtain hexamethyldisiloxane.

[0191] The number of portions mentioned in this embodiment refers to the mass flow rate per unit time by weight.

[0192] Comparative Example 1

[0193] A method for preparing hexamethyldisiloxane includes the following steps:

[0194] B) 36.5% concentrated hydrochloric acid and 99% pure trimethylchlorosilane are sequentially fed into a hydrolysis reactor, wherein the mass ratio of concentrated hydrochloric acid to trimethylchlorosilane is 1:3, and a hydrolysis reaction is carried out to obtain a mixture of hexamethyldisiloxane, concentrated hydrochloric acid, and hydrogen chloride gas generated by hydrolysis.

[0195] The hydrolysis reaction occurs at a temperature of 35℃. The hydrolysis products after heat exchange are at a temperature of 45℃.

[0196] B) The obtained hydrolysis products are fed to a heat exchanger for heating, and then enter a gas-liquid separation tower. Hydrogen chloride gas is separated from the hydrolysis products and enters a purification condenser. Hydrogen chloride gas is collected from the top of the purification condenser, and a mixture of hydrochloric acid and hexamethyldisiloxane is obtained from the bottom of the purification condenser.

[0197] A mixture of hexamethyldisiloxane and concentrated hydrochloric acid is obtained at the bottom of the gas-liquid separation tower;

[0198] C) The mixture of hexamethyldisiloxane and concentrated hydrochloric acid obtained from the bottom of the gas-liquid separator and the mixture of hydrochloric acid and hexamethyldisiloxane obtained from the bottom of the condenser are transported to the separator for separation; the upper oily liquid is separated to the hexamethyldisiloxane washing tank, and after washing, crude hexamethyldisiloxane is obtained and enters the hexamethyldisiloxane intermediate tank.

[0199] The lower layer of hydrochloric acid water is transported to the intermediate hydrochloric acid tank for recycling.

[0200] D) The obtained crude hexamethyldisiloxane is fed to a distillation column for separation. Gas-phase hexamethyldisiloxane is obtained from the top of the column and then condensed to obtain hexamethyldisiloxane.

[0201] The number of portions mentioned in this embodiment refers to the mass flow rate per unit time by weight.

[0202] Performance testing

[0203] Detection method: The actual yield of hexamethyldisiloxane prepared in Examples 1-10 and Comparative Example 1 was compared with the theoretical actual yield of complete reaction of added trimethylchlorosilane to obtain the yield, and the actual yield of hexamethyldisiloxane per unit time was compared.

[0204] The results are shown in the table below:

[0205] Table 1

[0206] Example Yield Example 1 85％ Example 2 86％ Example 3 86％ Example 4 87％ Example 5 86％ Example 6 92％ Example 7 93％ Example 8 93％ Example 9 94％ Example 10 93％ Comparative Example 1 79.6％

[0207] Furthermore, the production efficiency of Examples 6-10 is higher than that of Examples 1-5, and much higher than that of Comparative Example 1.

[0208] Conclusion: As can be seen from Table 1 above, the feeding structure added in this invention, together with some powdered additives mixed into the raw materials, greatly improves the production efficiency and yield of hexamethyldisiloxane.

[0209] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing hexamethyldisiloxane, comprising the following steps: A) Concentrated hydrochloric acid and trimethylchlorosilane are sequentially fed into a hydrolysis reactor to carry out a hydrolysis reaction and obtain hydrolysis products; The hydrolysis reactor includes a stirred tank, on the bottom wall of which is an elastic hollow sphere connected to the bottom wall of the stirred tank. A one-way feed pipe is provided on the bottom wall of the stirred tank, penetrating the bottom wall of the stirred tank and the side wall of the elastic hollow sphere. The side wall of the elastic hollow sphere is also provided with a liquid distribution hole that allows only one-way flow from the inside of the elastic hollow sphere to the outside. The mixing vessel is equipped with a pressure plate with multiple through holes, which abuts against or is connected to an elastic hollow sphere; the mixing vessel is equipped with a lifting device for driving the pressure plate to move up and down; a stirring device is provided on the side of the pressure plate away from the elastic hollow sphere. The stirred tank is equipped with a trimethylchlorosilane storage tank, which is connected to a one-way feed pipe; the stirred tank is also equipped with a feed port for replenishing concentrated hydrochloric acid and a discharge port for discharging reaction products. Trimethylchlorosilane is fed from a trimethylchlorosilane reservoir into an elastic hollow sphere through a one-way feed pipe. A descending pressure plate then compresses the hollow sphere, causing the trimethylchlorosilane feedstock to enter the reactor body through a one-way flow-through separator and react with concentrated hydrochloric acid to produce hexamethyldisiloxane. When the pressure plate rises, the hollow sphere returns to its original shape, and due to the one-way flow path, trimethylchlorosilane continues to flow from the reservoir into the hollow sphere, thus continuously and evenly dispersing the trimethylchlorosilane throughout the stirred tank. The pressure of the hydrolysis reaction is 0–0.2 MPa; B) The obtained hydrolysis products are fed to a heat exchanger for heating, and then enter a gas-liquid separation tower. Hydrogen chloride gas is separated from the hydrolysis products and enters a purification condenser. Hydrogen chloride gas is collected from the top of the purification condenser, and a mixture of hydrochloric acid and hexamethyldisiloxane is obtained from the bottom of the purification condenser. A mixture of hexamethyldisiloxane and concentrated hydrochloric acid is obtained at the bottom of the gas-liquid separation tower; C) The mixture of hexamethyldisiloxane and concentrated hydrochloric acid obtained from the bottom of the gas-liquid separator and the mixture of hydrochloric acid and hexamethyldisiloxane obtained from the bottom of the condenser are transported to the separator for separation; the upper oily liquid is separated to the hexamethyldisiloxane washing tank, and after washing, crude hexamethyldisiloxane is obtained and enters the hexamethyldisiloxane intermediate tank. The lower layer of hydrochloric acid water is transported to the intermediate hydrochloric acid tank for recycling. D) The obtained crude hexamethyldisiloxane is fed to a distillation column for separation. Gas-phase hexamethyldisiloxane is obtained from the top of the column and then condensed to obtain hexamethyldisiloxane.

2. The method for preparing hexamethyldisiloxane according to claim 1, characterized in that, The material of the elastic hollow sphere is one of nitrile rubber, chloroprene rubber, and styrene-butadiene rubber.

3. The method for preparing hexamethyldisiloxane according to claim 1, characterized in that, The temperature difference between the inside and outside of the elastic hollow sphere is 5-10°C, and the temperature inside the elastic hollow sphere is higher than the temperature outside the elastic hollow sphere.

4. The method for preparing hexamethyldisiloxane according to claim 3, characterized in that, The temperature inside the elastic hollow sphere is 40-45°C, and the temperature outside the elastic hollow sphere is 35-38°C.

5. The method for preparing hexamethyldisiloxane according to claim 3, characterized in that, The temperature inside the elastic hollow sphere is 45°C, and the temperature outside the elastic hollow sphere is 35°C.

6. The method for preparing hexamethyldisiloxane according to claim 1, characterized in that, The temperature of the hydrolysis product after heat exchange in step B) is 30–80°C.

7. The method for preparing hexamethyldisiloxane according to claim 1, characterized in that, The washing solution used in step C) is water or a weak alkaline aqueous solution; The weak base is one or more of sodium carbonate, sodium bicarbonate, and potassium carbonate.

8. The method for preparing hexamethyldisiloxane according to claim 1, characterized in that, The mass concentration of the concentrated hydrochloric acid is >10%.

9. The method for preparing hexamethyldisiloxane according to claim 8, characterized in that, The mass ratio of hydrochloric acid to trimethylchlorosilane is 1:(2-4).

10. The method for preparing hexamethyldisiloxane according to claim 1, characterized in that, The trimethylchlorosilane contains 0.1-1 wt% of powder additives, which include ultrafine calcium hydroxide and ultrafine sodium bicarbonate powders in a mass ratio of 1:2-6.

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