CN117339486A - Energy-saving device and method for preparing and purifying silane by fixed bed - Google Patents

Abstract

The invention relates to an energy-saving device and method for preparing and purifying silane in a fixed bed; the mixed chlorosilane from the cold hydrogenation section passes through the light removal tower, the hydrogen is separated from the top of the tower, the chlorosilane is extracted from the tower still, and after vaporization, it enters the chlorosilane separation step The tower is separated at the beginning, and then enters the second chlorosilane separation tower for separation. The top material enters the DCS fixed bed disproportionation reactor, and the tower bottom material enters the TCS fixed bed disproportionation reactor; the reaction product of the TCS reactor is divided into two streams, and one stream is used for chlorosilane separation. The first tower feeds, and the other feeds the second chlorosilane separation tower; the heavy component silicon tetrachloride is extracted from the tower kettles of the first chlorosilane separation tower and the second chlorosilane separation tower, and the top of the tower is taken out to feed the dichlorotrichloride separation tower. The product of the DCS reactor is fed to the silane separation tower, the chlorosilane extracted from the tower kettle is returned to the dichlorotrichloride separation tower for separation, the liquid phase silane is extracted from the side to feed the silane vaporization tower, and the tail gas is discharged from the top of the tower; the gas phase of the silane vaporization tower Side mining silane products; energy consumption is reduced by more than 30%, and silane purity reaches 99.9%.

Description

Energy-saving device and method for preparing and purifying silane in fixed bed

Technical field

The present invention relates to the technical field of silane production, in particular to an energy-saving device and method for preparing and purifying silane in a fixed-bed disproportionation reactor using chlorosilane as raw material, combined with heat integration technology of distillation towers, and is suitable for industrial synthesis of silane. .

Background technique

Silane, also known as monosilane (SiH ₄ ), is most widely used as an intermediate product in the production of high-purity silicon, generally called the silane method. In recent years, the rapid development of the photovoltaic industry has driven the rapid growth of the market demand for silane, and silicon As a basic material for photovoltaic technology, its development prospects are very promising. High-purity silane is the most important electronic specialty gas used in semiconductor microelectronics processes. Its purity restricts the development of integrated circuits. With the rapid development of electronic information technology, circuit integration is getting higher and higher, and the purity of silane has also been raised. higher requirements. In addition, silanes and chlorosilanes are also necessary chemicals for the production of microscopic slides, oxidation masks and corrosion-resistant coatings. Silicon-containing coatings can greatly improve the physical and chemical properties of materials. Silane vapor deposition technology is used to manufacture various containing The use of silicon thin films in high technology is increasing day by day. Another potential application of silane is to make silicides (SiC, Si ₃ N _4, etc.), which are then used to make ceramics with high temperature resistance, high strength, and high chemical stability.

Currently, there are many methods for preparing silane, including trichlorosilane disproportionation method, aluminum-magnesium alloy method, and silicon tetrafluoride reduction method. The trichlorosilane disproportionation method was first proposed by Union Carbide Corporation (UCC) in the United States. In its patent US4340574, it was proposed to use chlorosilane as raw material, undergo multi-step disproportionation in a fixed-bed reactor, and then purify it through a distillation tower to obtain high-purity silane. , but this method has complex process, high energy consumption and extremely low conversion rate. Since then, patents for improving the preparation method have continued to emerge, but no practical and effective innovation has emerged. The process still has problems of high energy consumption, low productivity and low silane purity. The aluminum-magnesium alloy method is difficult to achieve the production capacity and production level of large enterprises. The silicon tetrafluoride reduction method has complex processes, numerous equipment, huge investment costs, and silicon tetrafluoride is highly corrosive. Comprehensive comparison of the above three processes, combined with the current development status of domestic silane production, the chlorosilane disproportionation method for preparing silane is more promising.

The process of preparing silane through the disproportionation reaction of chlorosilane uses chlorosilane as the raw material. The process flow is: (1) Solar grade silicon, H2, and SiCl ₄ undergo a cold hydrogenation process to prepare SiHCl ₃ ; (2) SiHCl ₃ is disproportionated and hydrogenated to generate SiH ₂ Cl ₂ ; (3) SiH ₂ Cl ₂ is redisproportionated to generate SiH ₃ Cl; (4) SiH ₃ Cl is further catalytically disproportionated to generate SiH ₄ gas. The three-stage continuous reversible reaction of disproportionation of trichlorosilane to silane has very unfavorable reaction kinetics and a thermodynamic conversion rate close to zero. Its components are both reactants and intermediate products. The coupling between substances is very high, resulting in the existing The technology conversion rate is low, energy consumption is high, and equipment investment is high.

Contents of the invention

In view of the above-mentioned deficiencies of the prior art, the problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide an energy-saving device and method for preparing and purifying silane in a fixed bed.

The invention relates to an energy-saving production process for preparing and purifying silane through a fixed-bed disproportionation reactor. The preparation device of the invention includes a distillation tower group, a silane separation tower, a silane vaporization tower, and a trichlorosilane fixed-bed disproportionation reaction. reactor, dichlorosilane fixed-bed disproportionation reactor, heat-integrated reboiler, vaporizer, and condenser; the distillation tower group of the device includes a chlorosilane removal tower, a first chlorosilane separation tower, a second chlorosilane separation tower, and a second chlorosilane separation tower. Chlorine trichloride separation tower; this preparation device adopts the heat integration structure of the distillation tower group and is an energy-saving production process;

The object of the present invention is solved through the following technical solutions:

An energy-saving device for preparing and purifying silane in a fixed bed. The device includes a chlorosilane removal tower, a chlorosilane separation tower, a chlorosilane separation tower, a dichlorotrichloride separation tower, a silane separation tower, a silane vaporization tower, and a TCS fixed bed disproportionation tower. Reactor, DCS fixed bed disproportionation reactor; the top pipeline of the chlorosilane removal tower is used to discharge light components, and the bottom pipeline is connected to the feed pipeline of the first chlorosilane separation tower; the top pipeline of the first chlorosilane separation tower is connected to the chlorosilane Reboiler of the light removal tower and dichlorotrichloride separation tower, and then connect the feed pipeline of the dichlorotrichloride separation tower; the top pipeline of the second chlorosilane separation tower is connected to the feed interface of the dichlorotrichloride separation tower; dichlorotrichloride separation tower The top pipeline of the chlorine separation tower is connected to the feed port of the DCS fixed-bed disproportionation reactor, and the bottom pipeline is connected to the feed port of the TCS fixed-bed disproportionation reactor; the outlet of the TCS fixed-bed disproportionation reactor is divided into two streams, which are connected to chlorine. The feed interface of the first silane separation tower and the second chlorosilane separation tower; the discharge port of the DCS fixed bed disproportionation reactor is connected to the feed port of the silane separation tower; the lateral production pipeline of the silane separation tower is connected to the feed port of the silane vaporization tower. The bottom pipeline is connected to the feed pipeline of the dichlorotrichloride separation tower; the lateral production line of the silane vaporization tower is the product line, and the bottom pipeline is connected to the feed pipeline of the dichlorotrichloride separation tower.

The chlorosilane light removal tower, the first chlorosilane separation tower, the second chlorosilane separation tower, the dichlorotrichloride separation tower, the silane separation tower, and the silane vaporization tower are packed towers or plate towers.

The silane separation tower and silane vaporization tower are made of SS304L stainless steel.

The gas phase side extraction of the silane vaporization tower is connected to the silane storage device.

When the chlorosilane removal tower, distillation tower group, silane separation tower, and silane vaporization tower are packed towers, they are filled with one or more combinations of structured packing, random packing, and separation trays.

The method for preparing and purifying silane using an energy-saving device of the present invention is characterized in that the mixed chlorosilane from cold hydrogenation first passes through the light removal tower, the hydrogen is separated from the top of the tower, the chlorosilane is extracted from the tower still, and passed through the vaporizer After vaporization, it enters the first chlorosilane separation tower; the reaction product of the TCS fixed bed disproportionation reactor is divided into two streams, one stream is fed to the first chlorosilane separation tower, and the other stream is fed to the second chlorosilane separation tower; the first chlorosilane separation tower The tower kettle mainly extracts the heavy component silicon tetrachloride, and the gas phase extracted from the top of the tower simultaneously heats the reboiler of the light removal tower and the reboiler of the dichlorine and trichlorine separation tower to achieve efficient use of energy. The products after heat exchange Feed the dichlorotrichlorine separation tower; the heavy component silicon tetrachloride is extracted from the second chlorosilane separation tower still, and the top of the tower is extracted to feed the dichlorotrichloride separation tower. The tower still is reboiled using the cold hydrogenation section. The heat of the quenching tower is used for heating; the bottom of the dichlorine and trichlorine separation tower is taken out into the TCS fixed bed disproportionation reactor, and the top of the tower is taken out into the DCS fixed bed disproportionation reactor; the product of the DCS fixed bed disproportionation reactor is fed to the silane separation tower. The chlorosilane extracted from the tower kettle is returned to the dichlorotrichloride separation tower for separation, and the liquid phase silane is extracted from the side to feed the silane vaporization tower, and the tail gas is discharged from the top of the tower; the final silane product is obtained from the gas phase side extraction of the silane vaporization tower.

The shells of the TCS fixed bed disproportionation reactor and DCS fixed bed disproportionation reactor are filled with amino resin or sulfonic acid catalysts.

The preparation device adopts a heat-integrated structure of the distillation tower group. The gas phase at the top of the chlorosilane separation tower is extracted while providing heat-integrated heat exchange to the reboiler of the chlorosilane removal light tower and the reboiler of the dichlorotrichlorine separation tower. Achieve efficient use of energy.

The preparation device adopts the heat integration of the cold hydrogenation section and the fixed bed preparation and purification section of silane. The two-column silane separation reactor reboiler uses the heat of the top product of the quenching tower in the cold hydrogenation section for heating and integrated heat exchange to achieve energy efficient utilization.

The silane separation tower and silane vaporization tower control the tower pressure drop to change the tower top temperature, so that the top refrigerant uses one or more combinations of frozen brine, Freon, CO ₂ refrigerant, ethylene, and liquid nitrogen; the silane Entering the silane separation tower or silane vaporization tower, the operating pressure of the tower is 1.5~3MPa, and the condensation temperature of the top condenser is -100°C~-20°C.

The specific instructions are as follows:

When used, first carry out the cold hydrogenation reaction of chlorosilane, using metallurgical grade silicon powder, hydrogen and silicon tetrachloride gas to react at 500~550℃ and 2~3MPa. The reaction formula is:

3SiCl ₄ +2H ₂ +Si→4SiHCl ₃

The obtained mixed chlorosilane product enters the chlorosilane removal tower, hydrogen is separated from the top of the tower, and chlorosilane is extracted from the tower still. After being vaporized by the vaporizer, it enters the first chlorosilane separation tower for distillation and separation. The tower still removes high boiling points. of tetrachlorosilane, and the steam obtained from the top of the tower enters the dichlorotrichloride separation tower for further separation. The reaction product of the TCS fixed-bed disproportionation reactor is divided into two streams, one stream is fed to the first tower of chlorosilane separation, and the other stream is fed to the second tower of chlorosilane separation; the first stream of chlorosilane separation tower still mainly produces the heavy component tetrachlorine Siliconization, the gas phase at the top of the tower is extracted and the reboiler of the chlorosilane removal tower and the reboiler of the dichlorotrichloride separation tower are thermally integrated for heat exchange, achieving efficient use of energy. The heat-exchanged product is supplied to the dichlorotrichloride separation tower. Chlorine separation tower feed, trichlorosilane and dichlorodihydrogen silicon account for the highest proportion in the feed; the heavy component silicon tetrachloride is extracted from the second tower of chlorosilane separation tower, and the top of the tower is extracted for dichlorotrichloride separation To feed the tower, the tower kettle reboiler uses the heat of the top product of the quenching tower in the cold hydrogenation section for heating and integrated heat exchange. Mainly trichlorosilane is extracted from the reactor of the dichlorotrichloride separation tower, and enters the TCS fixed bed disproportionation reactor for catalytic disproportionation reaction to obtain dichlorosilane and silicon tetrachloride; the top of the dichlorotrichloride separation tower Mainly dichlorosilane is extracted and enters the DCS fixed bed disproportionation reactor to obtain silane and trichlorosilane. The reaction formulas are:

The product of the DCS fixed-bed disproportionation reactor is fed to the silane separation tower. The tail gas is discharged from the top of the silane separation tower. The liquid phase silane is taken out from the side to feed the silane vaporization tower. The tail gas is discharged from the top of the silane vaporization tower. The final silane product is obtained through gas phase side collection. ; The liquid phase mixed chlorosilane is obtained from the silane separation tower and the silane vaporization tower still, and is transported to the dichlorotrichloride separation tower to continue separation, realizing the separation cycle of materials and improving the conversion rate of the reaction.

In the method of the present invention, the mixed chlorosilane raw materials coming from the cold hydrogenation section include hydrogen, trichlorosilane, dichlorosilane, and silicon tetrachloride. The largest proportion is silicon tetrachloride, followed by Dichlorosilane, trichlorosilane, and hydrogen; in the method described, the mixture enters the chlorosilane delightening tower for preliminary separation. The top pressure in the chlorosilane delightening tower can be 0.3 to 0.5MPa, which is to ensure that the tower For the heat integration of the bottom reboiler, the tower pressure must be lower than that of the chlorosilane separation tower; the temperature distribution of the whole tower is 60-103°C, and the low-boiling-point hydrogen goes upward from the top of the tower back to the cold hydrogenation section for circulation reaction, and the Trichlorosilane, dichlorodihydrosilicone and silicon tetrachloride are input to the vaporizer through the tower tank pump. After being heated and vaporized by the vaporizer, they are used as feed materials for the first chlorosilane separation tower.

In the method of the present invention, the bottom stream of the chlorosilane removal tower enters the first chlorosilane separation tower for further purification and separation. The top pressure in the first chlorosilane separation tower can be 0.9 to 1.5MPa, and the temperature distribution of the whole tower is 120 to 120 MPa. 160°C, high-concentration tetrachlorosilane, a small amount of trichlorosilane, trace amounts of dichlorosilane, and hydrogen obtained from the top of the chlorosilane delightening tower are extracted from the tower kettle and transported to the cold hydrogenation section together with silicon powder. The reaction produces mixed chlorosilane, which is then transported to a fixed bed to prepare and purify silane. This is an energy-saving process that allows the by-products produced in the process to be recycled throughout the process, maximizing the effectiveness of the materials, reducing costs and increasing efficiency; when chlorine When the top pressure of the first silane separation tower is 1.17MPa, the top material exists in the form of trichlorosilane and dichlorodihydrogen silicon in the vapor phase, the temperature is about 120°C, and the pressure is about 1.17MPa; while chlorosilane is removed from the light The temperature at the bottom of the tower is about 103°C, and the pressure is about 0.48MPa. The temperature at the bottom of the dichlorotrichlorine separation tower is about 105°C, and the pressure is about 0.77MPa. According to the calculation of the heat exchanger, chlorosilane is used to separate a The steam from the tower provides heat integration for the rectification tower group heated by the bottom reboiler of the chlorosilane removal tower and the dichlorotrichlorine separation tower. Therefore, the top material of the chlorosilane separation tower is divided into two streams, and one stream is used for The reboiler at the bottom of the chlorosilane removal tower is heated, and one stream is heated by the reboiler at the bottom of the dichlorotrichloride separation tower. After heat exchange, the stream is gathered into one stream and enters the dichlorotrichloride separation tower for another separation; chlorine The reboiler of the first silane separation column is heated using pressurized steam.

In the method of the present invention, the top pressure of the dichlorotrichloride separation tower is about 0.5-0.75MPa, and the temperature distribution of the whole tower is 60-105°C. There are three streams of feed to the dichlorotrichloride separation tower, each from At the top of the first chlorosilane separation tower, at the top of the second chlorosilane separation tower, there are also mixed feeds of the still liquid of the silane separation tower and the silane vaporization tower. The main function of the dichlorotrichloride separation tower is to separate trichlorosilane and dichlorodihydrosilicone. The top product is mainly dichlorodihydrosilicone, which is transported to the DCS fixed bed disproportionation reactor through a pressurized pump and reacts to generate silane. and trichlorosilane; the column product is mainly trichlorosilane, which is transported to the TCS fixed-bed disproportionation reactor through a pump, and reacts to generate dichlorosilane and silicon tetrachloride.

In the method of the present invention, the pressure of the TCS fixed-bed disproportionation reactor is about 0.4-0.6MPa, and the temperature is about 70°C; the still product of the dichlorotrichlorine separation tower is used as the feed material of the TCS fixed-bed disproportionation reactor, and is passed through the catalyst Catalytic disproportionation generates dichlorosilane and silicon tetrachloride. The outlet stream of the TCS fixed-bed disproportionation reactor is divided into two streams. One stream is transported to the first chlorosilane separation tower for distillation separation, and the other stream is input to the second chlorosilane separation tower. The tower performs distillation separation.

In the method of the present invention, the top pressure of the second chlorosilane separation tower is about 0.2-0.4MPa, and the temperature distribution of the whole tower is 67-104°C. It is continuously heated and evaporated through the tower still reboiler, and separated in the stripping section. The temperature of the tower still is controlled to be 100-110°C. The high-concentration tetrachlorosilane, a small amount of trichlorosilane and trace dichlorosilane extracted from the final tower still are separated from the chlorosilane stream from the tower still, as well as chlorine The hydrogen obtained from the top of the silane delight tower is transported to the cold hydrogenation section, reacts with silicon powder to obtain mixed chlorosilane, and the mixed silane is then transported to the energy-saving process of fixed bed preparation and purification of silane, so that the by-products generated in the process are recycled throughout the process. It is recycled in the process flow to maximize the effectiveness of the materials, reduce costs and increase efficiency; the bottom reboiler of the second chlorosilane separation tower uses the heat of the top product of the quenching tower in the cold hydrogenation section for heating and integrated heat exchange.

In the method of the present invention, the pressure of the DCS fixed-bed disproportionation reactor is about 2 to 3MPa, and the temperature is about 55°C; the top product of the dichlorotrichlorine separation tower is used as the feed material of the DCS fixed-bed disproportionation reactor and is catalyzed by the catalyst. Disproportionation produces silane and trichlorosilane, and the outlet stream from the DCS fixed-bed disproportionation reactor is transported to the silane separation tower for purification.

In the method of the present invention, the top pressure of the silane separation tower is about 1.7~3MPa, and the temperature distribution of the whole tower is -34.5~114°C; the reaction product in the DCS fixed bed disproportionation reactor is used as the feed of the silane separation tower, and the top of the tower is -34.5~114°C. The tail gas is removed, and the tower still product is mixed with the tower still product of the silane vaporization tower and used as the feed for the dichlorotrichloride separation tower. The silane separation tower adopts a side extraction method, and the liquid phase silane is extracted sideways to feed the silane vaporization tower.

In the method of the present invention, the top pressure of the silane vaporization tower is about 1.7~3MPa, and the temperature distribution of the whole tower is -34.3~-34.5°C; the liquid phase silane is extracted from the side of the silane separation tower as the feed of the silane vaporization tower. After excluding the tail gas, the tower still product is mixed with the tower still product of the silane separation tower and used as the feed for the dichlorine and trichloride separation tower. The silane vaporization tower adopts a side-line extraction method, and the final high-purity silane product is obtained through gas-phase side extraction.

The energy-saving device for preparing and purifying silane in a fixed bed, the chlorosilane light removal tower, the second chlorosilane separation tower, the dichlorotrichloride separation tower top products are cooled by air condensers, the silane separation tower and the silane vaporization tower The top temperature reaches about minus 35°C, and Freon is preferably used as the refrigerant.

In the energy-saving device for preparing and purifying silane in a fixed bed, the bottom of the first chlorosilane separation tower, the silane separation tower and the silane vaporization tower adopts a steam reboiler, and the bottom of the second chlorosilane separation tower adopts the quenching tower in the cold hydrogenation section. The heat of the top product is used for heat integrated heat exchange. The bottom reboiler of the chlorosilane light removal tower and the dichlorotrichlorine separation tower uses the top steam of the second chlorosilane separation tower for heat integrated heat exchange.

The energy-saving device for preparing and purifying silane in a fixed bed has a total of three distillation towers, including a first chlorosilane separation tower, a second chlorosilane separation tower, and a dichloro-trichloride separation tower.

The energy-saving device for preparing and purifying silane in a fixed bed according to the present invention is characterized in that the preparation device includes a chlorosilane removal tower (3), a first chlorosilane separation tower (5), a second chlorosilane separation tower (7), Dichlorotrichloride separation tower (8), silane separation tower (10), silane vaporization tower (11), trichlorosilane fixed bed disproportionation reactor (6), dichlorodihydrosilane fixed bed disproportionation reactor (9) , reboiler (12), vaporizer (4), air condenser (1); the preparation device adopts a heat integration structure of a distillation tower group, as shown in Figure 1.

The energy-saving method for preparing and purifying silane in a fixed bed according to the present invention is characterized in that the method uses solar-grade silicon powder processed in a cold hydrogenation section to obtain mixed chlorosilanes as reaction raw materials, and uses a tower separation and purification device to analyze different boiling points. The chlorosilanes are separated, and the high-boiling silicon tetrachloride is returned to the cold hydrogenation section to continue the reaction. Trichlorosilane enters the TCS fixed-bed disproportionation reactor, and dichlorodihydrosilane enters the DCS fixed-bed disproportionation reactor to prepare and purify silane; mix Chlorosilane enters the chlorosilane delightening tower through the feed port (2).

The mixed chlorosilanes entering the chlorosilane delightening tower according to the present invention include dichlorosilane, trichlorosilane, silicon tetrachloride and hydrogen; the hydrogen obtained from the top of the chlorosilane delightening tower is returned to the cold hydrogenation section to continue reaction. .

The cold source of the silane separation tower and silane vaporization tower of the present invention can be one or more combinations of Freon, _CO2 refrigerant, ethylene, and liquid nitrogen.

The invention has the following advantages:

[1] Compared with the traditional chlorosilane fixed bed disproportionation process, the device process is reasonable and easy to control. Through the continuous extraction of silane in the silane vaporization tower and the circulation of unreacted chlorosilane in the system, the disproportionation reaction is more thorough and the reaction is transformed. The rate can reach more than 95%, and the purity of silane can reach 99.9%. It is an ideal process for industrial production of silane.

[2] The present invention adopts the heat integration of its own distillation tower group and the heat integration of the quench tower in the cold hydrogenation section, which can reduce energy consumption by more than 30%, achieving energy saving and cost reduction.

[3] The hydrogen produced at the top of the chlorosilane removal tower of the present invention and the silicon tetrachloride produced in the first chlorosilane separation tower and the second chlorosilane separation tower are transported together to the cold hydrogenation section and react with silicon powder to obtain mixed chlorosilane , the energy-saving process of mixing silane and then transporting it to a fixed bed to prepare and purify silane allows the by-products produced in the process to be recycled throughout the process, which is energy-saving and environmentally friendly.

Description of drawings

Figure 1 is an energy-saving device for preparing and purifying silane in a fixed bed;

Figure 2 An energy-saving device using trichlorosilane as raw material to feed into the TCS fixed bed disproportionation reactor

Among them: 1-air condenser; 2-mixed chlorosilane feed port, 3-chlorosilane light removal tower, 4-vaporizer; 5-chlorosilane separation tower; 6-trichlorosilane fixed bed disproportionation reactor; 7 -Second chlorosilane separation tower; 8-Dichlorotrichloro separation tower; 9-Dichlorodihydrosilane fixed bed disproportionation reactor; 10-Silane separation tower; 11-Silane vaporization tower; 12-Reboiler; 13-TCS Fixed bed disproportionation reactor feed port.

Detailed ways

In order to explain the present invention in more detail, further explanations are given below with reference to the drawings and examples. Detailed examples and specific operating processes are given below. Obviously, the embodiments described below are only some of the embodiments of the present invention. Not all embodiments are included. The protection scope of the present invention is not limited to the following embodiments. Other embodiments obtained by other persons skilled in the art without making creative changes are within the protection scope of the present invention. .

As shown in Figure 1, it includes a chlorosilane delightening tower (3), a first chlorosilane separation tower (5), a second chlorosilane separation tower (7), a dichlorotrichloride separation tower (8), and a silane separation tower (10). , silane vaporization tower (11), trichlorosilane fixed bed disproportionation reactor (6) (hereinafter referred to as TCS fixed bed disproportionation reactor), dichlorodihydrosilicone fixed bed disproportionation reactor (9) (hereinafter referred to as DCS fixed bed Disproportionation reactor), reboiler, vaporizer, condenser; the bottom pipeline of the chlorosilane removal tower (3) is connected to the feed pipeline of the first chlorosilane separation tower (5); the top pipeline of the first chlorosilane separation tower (5) Connect the reboiler of the chlorosilane removal tower (3) and the dichlorotrichloride separation tower (8), and then connect the feed line of the dichlorotrichloride separation tower (8); the top of the second chlorosilane separation tower (7) The pipeline is connected to the feed interface of the dichlorine and trichloride separation tower (8); the top pipeline of the dichlorotrichloride separation tower (8) is connected to the feed port of the DCS fixed bed disproportionation reactor (9), and the bottom pipeline is connected to the TCS fixed bed disproportionation reactor. The feed port of the reactor (6); the outlet of the TCS fixed bed disproportionation reactor (6) is divided into two branches, which are respectively connected to the feed interfaces of the first chlorosilane separation tower (5) and the second chlorosilane separation tower (7) ; The discharge port of the DCS fixed bed disproportionation reactor (9) is connected to the feed port of the silane separation tower (10); the lateral production pipeline of the silane separation tower (10) is connected to the feed interface of the silane vaporization tower (11) and the bottom pipeline The feed pipeline is connected to the dichlorotrichloride separation tower (8); the lateral production pipeline of the silane vaporization tower (11) is the product line, and the bottom pipeline is connected to the feed pipeline of the dichlorotrichloride separation tower (8); the preparation The device adopts the heat integration structure of the distillation tower group; at the same time, the direction from the tower still to the top of the tower is stipulated to be bottom-up.

Specific application examples are as follows:

Example 1:

Specifically, in this exemplary embodiment, as shown in Figure 1, the chlorosilane delight tower (3) is externally connected to the mixed chlorosilane raw material input pipeline (2) from the cold hydrogenation section, wherein the mixed chlorosilane raw material includes hydrogen, Trichlorosilane, dichlorosilane, and silicon tetrachloride, with the largest proportion being silicon tetrachloride, followed by dichlorosilane, trichlorosilane, and hydrogen; the mixture enters the chlorosilane to remove light Tower (3) performs preliminary separation, and the low-boiling-point hydrogen goes upwards from the top of the tower and returns to the cold hydrogenation section for circulation reaction. The high-boiling-point trichlorosilane, dichlorodihydrogen silicon, and silicon tetrachloride obtained from the tower still are discharged from the tower still. The pump is input to the vaporizer, and after being heated and vaporized by the vaporizer, it is used as the feed for the first chlorosilane separation tower; in this example, the top pressure in the chlorosilane removal tower (3) is about 0.48MPa, and the temperature distribution of the whole tower is 60 to 103°C.

After that, the stream from the column still of the chlorosilane removal tower (3) enters the first chlorosilane separation tower for further separation and purification. The column still extracts high-concentration tetrachlorosilane, a small amount of trichlorosilane, and trace amounts of dichlorosilane. Together with the hydrogen obtained from the top of the chlorosilane delightening tower (3), it is transported to the cold hydrogenation section to participate in the cold hydrogenation reaction. The obtained mixed chlorosilanes are then transported to an energy-saving process of fixed bed preparation and purification of silane; in this example, chlorosilanes are separated The top pressure in one tower is about 1.2MPa, the temperature distribution of the whole tower is about 120~160℃, and the bottom reboiler is heated by pressurized steam.

The top materials of the first chlorosilane separation tower (5) are mainly trichlorosilane and dichlorodihydrosilicon, which exist in the form of vapor phase. When the temperature of the first chlorosilane separation tower (5) is about 120°C, the pressure When it is about 1.17MPa, the bottom temperature of the chlorosilane delightening tower (3) is about 103°C and the pressure is about 0.48MPa. The bottom temperature of the dichlorotrichlorine separation tower (8) is about 105°C and the pressure is about 0.77MPa. , according to the calculation of the heat exchanger, it is feasible to use the steam from the chlorosilane separation tower to heat the rectification tower group heated by the bottom reboiler of the chlorosilane removal tower and the dichlorotrichlorine separation tower, so the chlorine The top material of the silane separation tower is divided into two streams, one stream is heated by the bottom reboiler of the chlorosilane removal tower, and the other stream is heated by the bottom reboiler of the dichlorotrichlorine separation tower. The streams after heat exchange are gathered into one stream. The strands enter the dichlorotrichlorine separation tower for another separation; the reboiler of the first chlorosilane separation tower is heated with pressurized steam. Therefore, the top material of the first chlorosilane separation tower (5) is divided into two streams, one stream is heated by the reboiler at the bottom of the chlorosilane delight tower (3), and the other stream is reboiled by the bottom of the dichlorosilane separation tower (8). The heat exchanger is heated, and the stream after heat exchange is gathered into one stream and enters the dichlorine and trichloride separation tower (8) for separation and purification.

The feed to the dichlorotrichloride separation tower (8) is divided into three streams, which come from the top of the first chlorosilane separation tower (5), the top of the second chlorosilane separation tower (7), and the silane separation tower. (10) and the kettle liquid of the silane vaporization tower (11) are mixed and fed. Its main function is to separate trichlorosilane and dichlorosilane. The top product is mainly dichlorosilane and is transported through a pressurized pump. Go to the DCS fixed bed disproportionation reactor (9) for reaction. The column product is mainly trichlorosilane, which is transported to the TCS fixed bed disproportionation reactor (6) for reaction through a pump; in this example, the dichlorotrichlorine separation tower (8) The pressure at the top of the middle tower is about 0.65MPa, and the temperature distribution of the whole tower is about 60~105℃.

The separated and purified column still product from the dichlorotrichloride separation tower (8) enters the feed of the TCS fixed bed disproportionation reactor (9), and is catalytically disproportionated by the catalyst to generate dichlorosilane and silicon tetrachloride. The TCS fixed bed The outlet stream of the disproportionation reactor (9) is divided into two streams. 80% of the total amount of outlet materials is transported to the first chlorosilane separation tower (5) for distillation separation, and 20% of the total amount of outlet materials is input to the second chlorosilane separation tower. (7) Carry out distillation separation; in this example, the pressure of the TCS fixed-bed disproportionation reactor is about 0.52MPa, and the temperature is about 70°C.

The material entering the second chlorosilane separation tower (7) from the TCS fixed-bed disproportionation reactor (9) is continuously heated and evaporated through the tower still reboiler, and separated in the stripping section. The temperature of the tower still is controlled to be 100~110°C, and the final tower The high-concentration tetrachlorosilane, a small amount of trichlorosilane and a trace amount of dichlorosilane extracted from the kettle are mixed with the kettle stream of the chlorosilane separation tower (5), as well as the top of the chlorosilane removal tower (3). The obtained hydrogen is transported to the cold hydrogenation section and reacts with silicon powder to obtain mixed chlorosilane. The mixed silane is then transported to an energy-saving process of fixed bed preparation and purification of silane, so that the by-products generated in the process are recycled throughout the entire process. The top material enters the dichlorotrichloride separation tower (8) for separation and purification; the bottom reboiler of the second chlorosilane separation tower (7) uses the heat of the top product of the quenching tower in the cold hydrogenation section for heating and integrated heat exchange; In the example, the top pressure of the second chlorosilane separation tower (7) is 0.35MPa, and the temperature distribution of the entire tower is 67 to 104°C.

The material from the top of the dichlorotrichloride separation tower (8) enters the DCS fixed bed disproportionation reactor (9), and is catalytically disproportionated to generate silane and trichlorosilane. The outlet stream of the DCS fixed bed disproportionation reactor is transported to Silane separation tower (10) for purification. In this example, the pressure of the DCS fixed-bed disproportionation reactor (9) is about 2.7MPa, and the temperature is about 55°C.

The reaction product in the DCS fixed bed disproportionation reactor (9) is used as the feed of the silane separation tower (10), the tail gas is removed from the top of the tower, and the tower still product is mixed with the tower still product of the silane vaporization tower, and used as a dichlorotrichloride separation tower (8 ), the silane separation tower (10) adopts a side extraction method, and the liquid phase silane is extracted sideways to feed the silane vaporization tower (11). In this example, the top pressure of the silane separation tower (10) is about 2.21MPa, and the temperature distribution of the whole tower is -34.5~114°C.

Liquid phase silane is extracted from the side of the silane separation tower (10) as the feed of the silane vaporization tower (11). The tail gas is discharged from the top of the tower, and the tower still product is mixed with the tower still product of the silane separation tower (10) to be separated as dichlorine and trichlorine. The feed to the tower (8) and the silane vaporization tower (11) adopt a side line extraction method, and the gas phase side extraction is used to obtain the final high-purity silane product, the purity of which can reach 100%, and the conversion rate of the reaction can reach more than 95%. In this example, the top pressure of the silane vaporization tower (11) is about 1.9MPa, and the temperature distribution of the whole tower is -34.3~-34.5°C. In this example, compared with an energy-saving process that does not use heat integration of the distillation column group, 10,000 to 12,000 KW of energy can be saved for each ton of silane produced.

In this exemplary implementation, by rationally utilizing the heat integration of the distillation column group, energy consumption can be saved by more than 30%.

In this exemplary implementation, air condensers are used at the top of the chlorosilane removal tower, the second chlorosilane separation tower, and the dichlorotrichloride separation tower for condensation. The temperature at the top of the silane separation tower and silane vaporization tower reaches about minus 35°C. , it is preferred to use Freon as the condensing agent.

In this exemplary implementation, the chlorosilane delight tower and distillation tower group are made of Q345R, the silane separation tower and silane vaporization tower are made of SS304L, and the TCS fixed bed disproportionation reactor and DCS fixed bed disproportionation reactor are made of carbon steel. Material.

In this exemplary implementation, the TCS fixed-bed disproportionation reactor and the DCS fixed-bed disproportionation reactor are filled with sulfonic acid-based catalysts for catalytic disproportionation of trichlorosilane and dichlorodihydrosilane to generate silane products.

In this exemplary implementation, the chlorosilane delightening tower, the first chlorosilane separation tower, the second chlorosilane separation tower, the dichlorotrichloride separation tower, the silane separation tower, and the silane vaporization tower are all packed towers, and the fillers are all packed with 452Y filler.

Example 2:

What is different from Example 1 is that the distribution ratio of the logistics flow rate at the outlet of the TCS fixed-bed disproportionation reactor in this example is changed from 2:8 to 4:6, that is, 60% of the total amount of materials at the outlet of the TCS fixed-bed disproportionation reactor is transported Go to the first chlorosilane separation tower (5) for distillation and separation, and 40% of the total amount of materials at the outlet of the TCS fixed-bed disproportionation reactor is input to the second chlorosilane separation tower (7) for distillation and separation; the silane vaporization tower (11) gas phase The silane product obtained through side mining has a purity of up to 99.9% and a reaction conversion rate of over 95%.

Example 3:

What is different from Example 1 is that the disproportionation reaction catalyst used in the TCS fixed bed disproportionation reactor and DCS fixed bed disproportionation reactor of this example is replaced by a sulfonic acid-based catalyst with an amino resin catalyst. Due to the permissible use of this type of catalyst The temperature is lower than that of the sulfonic acid-based catalyst, so the operating temperatures of the TCS fixed-bed disproportionation reactor and DCS fixed-bed disproportionation reactor are controlled within the range of 20 to 80°C to ensure the thermal stability of the catalyst.

Example 4: Different from Example 1, this example is not connected to the cold hydrogenation process, and a separate production method is selected. The specific process is shown in Figure 2. The outlet of the TCS fixed bed disproportionation reactor (6) is connected to the chlorine The feed interface of the silane separation tower (5); the top pipeline of the chlorosilane separation tower (5) is connected to the reboiler of the dichlorotrichloride separation tower (8), and then connected to the feed port of the dichlorotrichloride separation tower (8). feed pipeline; the top pipeline of the dichlorotrichlorine separation tower (8) is connected to the feed port of the DCS fixed bed disproportionation reactor (9), and the bottom pipeline is connected to the feed port of the TCS fixed bed disproportionation reactor (6); the DCS is fixed The discharge port of the bed disproportionation reactor (9) is connected to the feed port of the silane separation tower (10); the lateral production pipeline of the silane separation tower (10) is connected to the feed interface of the silane vaporization tower (11), and the bottom pipeline is connected to the dichloride The feed line of the trichlorine separation tower (8); the lateral production line of the silane vaporization tower (11) is the product line, and the bottom pipeline is connected to the feed line of the dichlorotrichloride separation tower (8). Example 4 directly uses trichlorosilane as raw material to input into the TCS fixed bed disproportionation reactor (6), and the reaction product chlorosilane separation tower (5) is fed; the chlorosilane separation tower (5) still mainly produces heavy component tetrachloride Silicon is extracted from the gas phase at the top of the tower for integrated heat exchange in the reboiler of the dichlorine and trichloride separation tower (8) to achieve efficient energy utilization. The heat-exchanged product is fed to the dichloride and trichloride separation tower (8); Mainly trichlorosilane is extracted from the still of the dichlorotrichloride separation tower (8), and enters the TCS fixed bed disproportionation reactor (6) to undergo a catalytic disproportionation reaction to obtain dichlorosilane and silicon tetrachloride; dichlorosilane Mainly dichlorodihydrosilicon is extracted from the top of the trichlorine separation tower (8) and enters the DCS fixed bed disproportionation reactor (9) to obtain silane and trichlorosilane; the product of the DCS fixed bed disproportionation reactor (9) is given to The silane separation tower (10) feeds the feed, and the tail gas is discharged from the top of the silane separation tower (10). The liquid phase silane is taken out from the side to feed the silane vaporization tower (11). The tail gas is discharged from the top of the silane vaporization tower (11), and the gas phase side is taken. The final silane product is obtained; the liquid phase mixed chlorosilane is obtained from the silane separation tower (10) and the silane vaporization tower (11), and is transported to the dichlorotrichloride separation tower (8) to continue separation, realizing the separation cycle of materials and improving the reaction efficiency Conversion rate, reaction conversion rate can reach more than 95%.

Example 5: Different from Example 1, this example is not connected to the cold hydrogenation process, and a separate production method is selected. The specific process is as shown in Figure 2, and dichlorosilane is directly used as the raw material to enter the DCS fixed bed disproportionation reaction. Reactor (9), enters the DCS fixed bed disproportionation reactor (9), obtains silane and trichlorosilane and inputs it into the silane separation tower (10). The tail gas is discharged from the top of the silane separation tower (10), and liquid phase silane is taken out from the side to feed silane. The vaporization tower (11) is fed, and the trichlorosilane and unreacted dichlorodihydrogen obtained at the bottom of the tower are transported to the dichlorotrichloride separation tower (8) for separation and purification; the dichlorotrichloride separation tower (8) is still The main product is trichlorosilane, which enters the TCS fixed-bed disproportionation reactor (6) for catalytic disproportionation reaction to obtain dichlorosilane and silicon tetrachloride; it is extracted from the top of the dichlorotrichloride separation tower (8) Mainly dichlorosilane enters the DCS fixed bed disproportionation reactor (9) to obtain silane and trichlorosilane; the TCS fixed bed disproportionation reactor (6) feeds the reaction product chlorosilane separation tower (10); The tower still of the chlorosilane separation tower (10) mainly produces heavy component silicon tetrachloride, and the gas phase at the top of the tower is produced for heat integrated heat exchange of the reboiler of the dichlorotrichlorine separation tower (8) to achieve efficient use of energy. The heated product feeds the dichlorotrichloride separation tower (8); the liquid phase silane is extracted from the side of the silane separation tower (10) and feeds the silane vaporization tower (11), and the tail gas is discharged from the top of the silane vaporization tower (11). The final silane product is obtained through gas phase side mining, and its purity can reach 99.9%; in this embodiment, the reaction conversion rate can reach more than 95%.

The energy-saving production process for preparing and purifying silane in a fixed-bed disproportionation reactor proposed by the present invention has been described through examples. The technical solutions disclosed and proposed by the present invention can be realized by relevant technical personnel by referring to the contents of this article and appropriately changing the conditional route and other links. Although the method and preparation technology of the present invention have been described through preferred implementation examples, relevant technical personnel can obviously The methods and technical routes described herein can be modified or recombined without departing from the content, spirit and scope of the present invention to achieve the final preparation technology. It should be noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are deemed to be included in the spirit, scope and content of the present invention.

Claims (10)

1. An energy-saving device for preparing and purifying silane in a fixed bed, characterized by: the device includes a chlorosilane removal tower, a first chlorosilane separation tower, a second chlorosilane separation tower, a dichlorotrichloride separation tower, a silane separation tower, and silane vaporization tower, TCS fixed bed disproportionation reactor, DCS fixed bed disproportionation reactor; the top pipeline of the chlorosilane removal tower is used to discharge light components, and the bottom pipeline is connected to the feed pipeline of the first chlorosilane separation tower; the first chlorosilane separation tower The top pipeline of the tower is connected to the reboiler of the chlorosilane removal tower and the dichlorotrichlorine separation tower, and then connected to the feed pipeline of the dichlorotrichloride separation tower; the top pipeline of the second chlorosilane separation tower is connected to the feed line of the dichlorotrichloride separation tower. material interface; the top pipeline of the dichlorotrichlorine separation tower is connected to the feed port of the DCS fixed bed disproportionation reactor, and the bottom pipeline is connected to the feed port of the TCS fixed bed disproportionation reactor; the outlet of the TCS fixed bed disproportionation reactor is divided into The two streams are respectively connected to the feed interfaces of the first chlorosilane separation tower and the second chlorosilane separation tower; the outlet of the DCS fixed bed disproportionation reactor is connected to the feed port of the silane separation tower; the lateral production pipeline of the silane separation tower is connected to the silane vaporization The tower feed interface, the bottom pipeline of the tower is connected to the feed pipeline of the dichlorotrichloride separation tower; the lateral production line of the silane vaporization tower is the product line, and the bottom pipeline of the tower is connected to the feed pipeline of the dichlorotrichloride separation tower. 2. The energy-saving device for preparing and purifying silane with a fixed bed as claimed in claim 1, characterized in that: the chlorosilane light removal tower, the first chlorosilane separation tower, the second chlorosilane separation tower, and the dichlorosilane separation tower. The tower, silane separation tower and silane vaporization tower are packed towers or plate towers. 3. The energy-saving device for preparing and purifying silane in a fixed bed as claimed in claim 1, characterized in that: the silane separation tower and the silane vaporization tower are made of SS304L stainless steel. 4. The energy-saving device for preparing and purifying silane in a fixed bed as claimed in claim 1, characterized in that: the gas phase side extraction of the silane vaporization tower is connected to a silane storage device. 5. The energy-saving device for preparing and purifying silane with a fixed bed as claimed in claim 1, characterized in that when the chlorosilane delight tower, distillation tower group, silane separation tower, and silane vaporization tower are packed towers, Fill one or more combinations of structured packing, random packing, and separation trays. 6. A method for preparing and purifying silane using the energy-saving device of claim 1, characterized in that the mixed chlorosilane from cold hydrogenation first passes through the light removal tower, the hydrogen is separated from the top of the tower, and the chlorosilane is extracted from the tower still. , after being vaporized by the vaporizer, it enters the first chlorosilane separation tower; the reaction product of the TCS fixed bed disproportionation reactor is divided into two streams, one stream is fed to the first chlorosilane separation tower, and the other stream is fed to the second chlorosilane separation tower; chlorosilane The first separation tower still mainly produces the heavy component silicon tetrachloride. The gas phase produced at the top of the tower simultaneously heats the reboiler of the light removal tower and the reboiler of the dichlorine and trichlorine separation tower, achieving efficient use of energy and heat exchange. The final product is fed to the dichlorotrichloride separation tower; the heavy component silicon tetrachloride is extracted from the second tower of chlorosilane separation tower, and the top of the tower is extracted to feed the dichlorotrichloride separation tower. The reboiler of the tower kettle adopts a cold In the hydrogenation section, the heat of the quenching tower is used for heating; the bottom of the dichlorine and trichlorine separation tower is taken out into the TCS fixed bed disproportionation reactor, and the top of the tower is taken out into the DCS fixed bed disproportionation reactor; the product of the DCS fixed bed disproportionation reactor is fed to the silane separation tower Feed, the chlorosilane extracted from the tower kettle is returned to the dichlorotrichloride separation tower for separation, the liquid phase silane is extracted from the side to feed the silane vaporization tower, and the tail gas is discharged from the top of the tower; the final silane product is obtained from the gas phase side extraction of the silane vaporization tower. 7. The method according to claim 6, characterized in that: the shells of the TCS fixed bed disproportionation reactor and the DCS fixed bed disproportionation reactor are filled with amino resin or sulfonic acid catalysts. 8. The method according to claim 6, characterized in that: the preparation device adopts a heat-integrated structure of the distillation tower group, and the gas phase at the top of the chlorosilane separation tower is extracted while simultaneously feeding the reboiler and the chlorosilane removal light tower. The reboiler heat of the dichlorine and trichlorine separation tower is integrated for heat exchange to achieve efficient use of energy. 9. The method according to claim 6, characterized in that: the preparation device adopts the thermal integration of the cold hydrogenation section and the fixed bed preparation and purification silane section, and the chlorosilane separation two-column still reboiler adopts the cold hydrogenation section. The heat of the top product of the quench tower is heated and integrated for heat exchange to achieve efficient use of energy. 10. The method of claim 6, wherein the silane separation tower and silane vaporization tower control the tower pressure drop to change the tower top temperature, so that the tower top refrigerant uses frozen brine, Freon, CO ₂ refrigerant, ethylene , one or more combinations of liquid nitrogen; the silane enters the silane separation tower or the silane vaporization tower, the operating pressure of the tower is 1.5~3MPa, and the condensation temperature of the top condenser is -100℃~-20℃ .