Energy-saving high-purity monosilane production system and method

Abstract

The invention relates to an energy-saving high-purity monosilane production system and method, the system comprises four rectifying towers, two rectifying towers are reactive rectifying towers filled with a chlorosilane disproportionation catalyst, and the other two rectifying towers are common rectifying towers; the method comprises the following steps: low-pressure reactive distillation, medium-pressure reactive distillation and high-pressure refining. Compared with the prior art, by means of optimal combination of three-stage pressurization and multi-stage cascade condensation, large-scale production of monosilane is particularly facilitated; low energy consumption and low investment are achieved by a process and method for preparing high-purity silane by catalytic disproportionation from chlorosilane (including trichlorosilane and dichlorosilane), and the process and method are suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, and in particular to an energy-saving high-purity monosilane production system and method. Background Art

[0002] High-purity monosilane can be used to manufacture metal silicides such as polysilicon, monocrystalline silicon, microcrystalline silicon, silicon nitride and silicon carbide. It is also an important electronic specialty gas and is widely used in microelectronics and optoelectronics industries. In recent years, with the rapid development of industries such as photovoltaics and display panels, the demand for monosilane has grown rapidly. Therefore, the development of energy-saving, efficient and large-scale monosilane production technology is of great value.

[0003] There are many methods for preparing monosilane. The methods with practical value and industrialization mainly include magnesium silicide method, lithium hydride reduction of trichlorosilane method, sodium aluminum hydride reduction of silicon tetrafluoride method and trichlorosilane disproportionation method. Among them, trichlorosilane disproportionation method was first proposed by UCC Company. It uses trichlorosilane as raw material to finally produce monosilane and silicon tetrachloride. It is the mainstream method for monosilane production at present.

[0004] 2HSiCl3=H2SiCl2+SiCl4 (1)

[0005] 2H2SiCl2=HSiCl3+H3SiCl (2)

[0006] 2H3SiCl=H2SiCl2+SiH4 (3)

[0007] UCC proposed in its early patent US4340574 that chlorosilane is used as raw material, and high-purity silane is prepared through multi-step fixed bed disproportionation reaction and distillation purification process, but the process is complicated and the production efficiency is low, and the energy consumption is very high. Since then, patents for improving this technology have continued to appear, such as patent US6905576, which simplifies the process. Only by operating a reaction distillation tower and a purification tower together, a high-purity silane product can be obtained, but there are still problems such as low production efficiency and high energy consumption. Patent CN1774397B discloses a device consisting of a distillation tower and a side reactor, and the separation process and the reaction process are carried out in the distillation tower and the side reactor respectively. Since the equilibrium conversion rate of the chlorosilane disproportionation reaction is extremely low, the production efficiency is low. Patent CN103172071 discloses a method of adding tetrachlorosilane absorption to a reaction distillation tower and fixed bed adsorption, which is less efficient, and the adsorbent has a short service life and needs to be replaced periodically. Patent CN104925813 discloses a reaction distillation tower device for preparing silane, comprising a lower stripping section, a middle reaction section and an upper distillation section separated from each other. Due to the large number of total theoretical plates, the height of the whole tower is relatively large. Another patent of the applicant, CN106241813, also discloses a system and method for preparing monosilane by disproportionation of trichlorosilane, including three distillation towers, a reaction distillation tower plus a light removal tower and a product tower, and the top of the reaction distillation tower adopts multi-stage condensation and gas phase extraction, and then uses a compressor to boost pressure. This method is more suitable for small-scale production, and the energy consumption and investment of compressor boosting are high. Patent CN115321540 discloses a method using two distillation towers, a reaction distillation tower and a refining tower. The reaction distillation tower adopts multi-stage condensation, liquid phase extraction, and pump boosting. However, due to liquid phase extraction, it needs to be deep-cooled to an extremely low temperature, with high energy consumption and large investment, which is not suitable for large-scale production. Patent CN110963494 adopts a five-tower process, two reaction distillation towers and three silane refining towers, but the pressure of the five towers is basically at the same level, less than 1.0Mpa, and needs to be operated at extremely low temperatures, with high energy consumption and large investment, and is not suitable for large-scale production.

[0008] Therefore, the existing high-purity silane production technology always has the problems of high energy consumption, large investment, and being unfavorable for large-scale production, and needs to be further improved and perfected. Summary of the invention

[0009] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide an energy-saving high-purity monosilane production system and method, which achieves low energy consumption and low investment and is suitable for large-scale production through a process and method for preparing high-purity silane from chlorosilane (including trichlorosilane and dichlorosilane) through catalytic disproportionation.

[0010] The purpose of the present invention can be achieved by the following technical solutions:

[0011] The first object of the present invention is to provide an energy-saving high-purity monosilane production system, which includes four distillation towers, two of which are reactive distillation towers filled with chlorosilane disproportionation catalysts, and two are ordinary distillation towers.

[0012] Furthermore, the system includes a first reaction distillation tower, a second reaction distillation tower, a first common distillation tower, and a second common distillation tower; the first reaction distillation tower, the second reaction distillation tower, the first common distillation tower, and the second common distillation tower are connected in sequence; the second common distillation tower is connected to the second reaction distillation tower; the first reaction distillation tower and the second reaction distillation tower are both filled with a chlorosilane disproportionation catalyst; the first reaction distillation tower is a low-pressure tower, and its operating pressure is less than 1.0Mpa; the second reaction distillation tower is a medium-pressure tower, and its operating pressure is 1.5-3.0 times that of the first reaction distillation tower; the first common distillation tower and the second common distillation tower are both high-pressure towers, and their operating pressures are 1.5-3.0 times that of the second reaction distillation tower, so that the entire production system realizes two-stage boosting operation and improves energy efficiency.

[0013] Furthermore, the system also includes a raw material tank; the raw material tank is connected to the first reaction distillation tower.

[0014] Furthermore, the system also includes three pressure pumps, namely a first pressure pump, a second pressure pump, and a third pressure pump; the first pressure pump is arranged between the raw material tank and the first reaction distillation tower; the second pressure pump is arranged between the first reaction distillation tower and the second reaction distillation tower; the third pressure pump is arranged between the second reaction distillation tower and the first ordinary distillation tower.

[0015] Furthermore, the first pressure pump pressurizes and transports the raw material trichlorosilane from the raw material tank to the first reaction distillation tower; the second pressure pump pressurizes and transports the liquid stream extracted from the top of the first reaction distillation tower to the second reaction distillation tower; the third pressure pump pressurizes and transports the liquid stream extracted from the top of the medium-pressure reaction distillation tower to the first ordinary distillation tower; the liquid stream at the bottom of the first ordinary distillation tower automatically flows into the second ordinary distillation tower by pressure difference; the high-purity monosilane (product) is extracted from the top of the second ordinary distillation tower. In this way, the boosting of the three-stage pump replaces the compressor of the prior art, which is conducive to expanding the scale of large-scale production and reducing investment and energy consumption.

[0016] Furthermore, the raw material trichlorosilane or dichlorosilane is transported from the raw material tank through the first pressure pump into the first reaction distillation tower to obtain a third liquid stream at the bottom of the tower and a second liquid stream at the top of the tower, the second stream at the top of the tower is transported to the second reaction distillation tower through the second pressure pump to obtain a fifth liquid stream at the bottom of the tower and a fourth liquid stream at the top of the tower, the fourth stream at the top of the tower is further transported to the first common distillation tower through the third pressure pump to obtain a seventh liquid stream at the bottom of the tower and a sixth gas stream at the top of the tower, the liquid stream at the bottom of the tower directly enters the second common distillation tower to obtain an eighth stream at the top of the tower and a stream at the bottom of the tower, and the sixth stream is discharged as an impurity into a subsequent environmental protection treatment system, the eighth stream enters a subsequent filling system or storage tank system as a high-purity monosilane product, and the stream enters the second reaction distillation tower as a circulating stream for recycling, so that a high-purity monosilane product can be obtained with low energy consumption and high efficiency.

[0017] Furthermore, the top of the first reaction distillation tower is provided with two-stage condensers, namely a first-stage condenser and a first-stage second-stage condenser; the first-stage condenser is connected to the first-stage second-stage condenser; the first-stage second-stage condenser is connected to the first intermediate tank; the liquid phase logistics of the first-stage condenser are all refluxed into the first reaction distillation tower, and the gas phase logistics enters the first-stage second-stage condenser and is completely condensed into the first intermediate tank, and the cooling medium of the two-stage condensers is circulating cooling water, which can increase the reaction temperature of the low-pressure reaction distillation tower and improve the reaction rate.

[0018] Furthermore, a multi-stage condenser is provided at the top of the second reaction distillation tower, and the multi-stage condenser includes a second first-stage condenser and subsequent condensers connected in sequence; the multi-stage condenser is connected to the second intermediate tank.

[0019] Furthermore, all the liquid phase logistics of the second-stage condenser are refluxed into the second reaction distillation tower, and circulating cooling water is used as the cooling medium. The subsequent condensers of each stage use cooling media with decreasing temperatures in turn, and the liquid phase logistics of each stage are combined and enter the second intermediate tank. This can reduce the capacity of the low-temperature cooling medium required for condensation, improve the energy efficiency of the refrigeration system, and reduce power consumption.

[0020] Furthermore, the first reaction distillation tower is divided into three sections, wherein the lowest section is a mass transfer filler section, which is loaded with mass transfer fillers, and the middle section and the uppermost section are catalyst sections, which are loaded with disproportionation catalysts; the middle section and the uppermost section are two reaction sections; the raw material inlet is located between the two reaction sections, which can improve the coupling efficiency of reaction and distillation, reduce catalyst consumption, reduce the reflux ratio, and reduce steam energy consumption.

[0021] Furthermore, the second reaction distillation tower is divided into two sections, wherein the uppermost section is a catalyst section loaded with a disproportionation catalyst, and the lower section is a mass transfer packing section loaded with a mass transfer packing; the feed position is between the catalyst section and the mass transfer packing section, which can also reduce catalyst consumption and steam consumption.

[0022] A second object of the present invention is to provide an energy-saving high-purity monosilane production method, which is carried out using the energy-saving high-purity monosilane production system as described above, and comprises the following steps:

[0023] S1, low-pressure reactive distillation: the raw material trichlorosilane or dichlorosilane is conveyed from atmospheric pressure to the first reactive distillation tower, and a low-pressure disproportionation reaction is carried out by the action of a catalyst, so that a disproportionation reaction of trichlorosilane occurs, and a third stream of tetrachlorosilane is obtained at the bottom of the tower, and the remaining products enter the top of the tower, and the liquid reflux stream is condensed to enter the top of the first reactive distillation tower to provide a liquid phase stream in the tower, and the condensed gas phase stream is subsequently condensed in full;

[0024] S2, medium-pressure reactive distillation: the top product obtained by the first-stage pressurized reactive distillation is liquefied and then pressurized, and then transported to the second reactive distillation tower for medium-pressure reaction, and a disproportionation reaction of dichlorosilane and monochlorosilane occurs to obtain a bottom liquid fifth stream and a top gas stream, and the bottom fifth stream is directly returned to the first reactive distillation tower for recycling, and the top gas stream is step-condensed by a step cooling medium to obtain a liquid fourth stream;

[0025] S3, high-pressure refining: the top product obtained by the secondary pressure reaction distillation is liquefied and then pressurized, and then transported to the first common distillation tower to remove light components with a boiling point lower than that of monosilane, and the sixth stream is discharged from the top of the first common distillation tower through condensation;

[0026] The seventh liquid stream at the bottom of the tower enters the subsequent second ordinary distillation tower, and the high-purity eighth stream obtained from the top of the tower is the monosilane product. The ninth liquid stream obtained at the bottom of the tower directly enters the second reactive distillation tower for recycling.

[0027] Furthermore, the method comprises the following steps:

[0028] S1, low-pressure reactive distillation: the raw material trichlorosilane or dichlorosilane is conveyed from the raw material tank by the first booster pump from the normal pressure to the first reactive distillation tower, and a low-pressure disproportionation reaction is carried out by the action of the catalyst, mainly the disproportionation reaction of trichlorosilane occurs, trichlorosilane is converted into tetrachlorosilane and dichlorosilane, a small amount of monochlorosilane and a very small amount of monosilane, a third stream of tetrachlorosilane is obtained at the bottom of the tower, and the rest enters the top of the tower, passes through the first primary condenser to obtain a liquid reflux stream, enters the top of the first reactive distillation tower to provide a liquid phase stream in the tower, and the gas phase stream of the first primary condenser enters the subsequent first and second secondary condensers to be completely condensed and enters the first intermediate tank;

[0029] The operating pressure of the first reaction distillation tower does not exceed 1.0 MPa, preferably, between 0.4-0.7 MPa, ensuring that the temperature of the lowest part of the intermediate reaction section does not exceed the heat resistance temperature of the catalyst, generally between 80-100°C;

[0030] S2, medium-pressure reactive distillation: the top product obtained from the first-stage pressurized reactive distillation mainly contains dichlorosilane, unconverted trichlorosilane, a small amount of monochlorosilane and a very small amount of monosilane, which is stored in the first intermediate tank after liquefaction, and is pressurized by the second booster pump and transported to the second reactive distillation tower for medium-pressure reaction, mainly undergoing disproportionation reaction of dichlorosilane and monochlorosilane, to obtain a bottom liquid fifth stream and a top gas stream, and the bottom fifth stream is directly returned to the first reactive distillation tower for recycling, and the top gas stream is step-condensed by a step cooling medium to obtain a liquid fourth stream, which enters the second intermediate tank;

[0031] The operating pressure of the second reaction distillation tower is 1.5-3.0 times the operating pressure of the first distillation tower, ensuring that the temperature of the lowest part of the reaction section does not exceed the heat resistance temperature of the catalyst, generally at 80-100°C;

[0032] S3, high-pressure refining: the top product obtained from the secondary pressure reaction distillation mainly contains monosilane, monochlorosilane, and a small amount of unconverted dichlorosilane, which is stored in the second intermediate tank after liquefaction, and is transported to the first ordinary distillation tower after being pressurized by the third pressure pump to remove light components with a lower boiling point than monosilane, including N2, O2 and CO, and the sixth stream is discharged from the top of the first ordinary distillation tower;

[0033] The top of the first common distillation tower also includes multi-stage condensation to reduce the loss of product monosilane;

[0034] The seventh stream of the liquid at the bottom of the tower enters the subsequent second ordinary distillation tower, and the eighth stream obtained from the top of the tower is a high-purity monosilane product. The ninth stream of the liquid obtained at the bottom of the tower includes unconverted monochlorosilane and dichlorosilane, and directly enters the second reactive distillation tower for recycling;

[0035] The operating pressure of the first ordinary distillation tower is 1.5-3.0 times the operating pressure of the second reactive distillation tower.

[0036] Furthermore, the operating pressure of the first reaction distillation tower is between 0.4-0.8 MPa; the operating pressure of the second reaction distillation tower is between 1.2-1.5 MPa; the operating pressure of the first ordinary distillation tower and the second ordinary distillation tower are between 2.0-3.0 MPa.

[0037] Furthermore, a multi-stage condenser is provided on the top of the second reaction distillation tower; the cooling medium of the multi-stage condenser is circulating cooling water in the first stage, and the temperature of each subsequent cooling medium decreases by 20-30°C in sequence.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1) The energy-saving high-purity monosilane production system and method provided by the technical solution adopts three-stage cascade pressurization, which not only meets the heat-resistant temperature requirements of the catalyst, but also maximizes the reaction rate, reduces the use and consumption of the catalyst, and significantly saves investment; at the same time, through the complete condensation of the top streams of the two reaction distillation towers, the liquid is pressurized, reducing equipment investment and power consumption; through the multi-stage condensation of the top streams of the three distillation towers, the energy efficiency of the refrigeration system is improved and the power consumption is reduced. In short, the optimized combination of three-stage pressurization and multi-stage cascade condensation is particularly conducive to the large-scale production of monosilane.

[0040] 2) The technical solution provides an energy-saving high-purity monosilane production system and method, which achieves low energy consumption and low investment through the process and method of preparing high-purity silane from chlorosilane (including trichlorosilane and dichlorosilane) through catalytic disproportionation, and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of the structure of the energy-saving high-purity monosilane production system in this technical solution.

[0042] The numbers in the figure show:

[0043] 100, first reaction distillation tower, 101, raw material tank, 102, first booster pump, 103, first primary condenser, 104, first secondary condenser, 200, second reaction distillation tower, 201, first intermediate tank, 202, second booster pump, 203, second primary condenser, 204, second secondary condenser, 205, second third-stage condenser, 206, second fourth-stage condenser, 300, first common distillation tower, 301, second intermediate tank, 302, third booster pump, 400, second common distillation tower,

[0044] 1. First logistics, 2. Second logistics, 3. Third logistics, 4. Fourth logistics, 5. Fifth logistics, 6. Sixth logistics, 7. Seventh logistics, 8. Eighth logistics, 9. Ninth logistics,

[0045] 10. Mass transfer packing section, 11. Catalyst section. DETAILED DESCRIPTION

[0046] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The features such as component models, material names, connection structures, control methods, etc. that are not clearly described in this technical solution are all regarded as common technical features disclosed in the prior art.

[0047] Example 1

[0048] like Figure 1 As shown, this embodiment provides an energy-saving high-purity silane production system and method.

[0049] The system includes four distillation towers, two of which are a first reaction distillation tower 100 and a second reaction distillation tower 200 filled with a chlorosilane disproportionation catalyst, and two are a first ordinary distillation tower 300 and a second ordinary distillation tower 400. The first reaction distillation tower 100 is a low-pressure tower, and its operating pressure is less than 1.0 MPa, specifically 0.5 MPa. The second reaction distillation tower 200 is a medium-pressure tower, and its operating pressure is 1.5-3.0 times that of the low-pressure first reaction distillation tower 100, specifically 1.30 MPa. The two ordinary distillation towers are both high-pressure towers, and their operating pressures are 1.5-3.0 times that of the medium-pressure second reaction distillation tower 200, specifically 2.45 and 2.40 MPa, respectively.

[0050] The present embodiment also includes three pressure pumps, a first pressure pump 102, a second pressure pump 202 and a third pressure pump 302. The first pressure pump 102 pressurizes and transports the raw material trichlorosilane from the raw material tank 101 to the low-pressure first reaction distillation tower 100. The second pressure pump 202 pressurizes and transports the liquid stream extracted from the top of the low-pressure first reaction distillation tower 100 to the medium-pressure second reaction distillation tower 200. The third pressure pump 302 pressurizes and transports the liquid stream extracted from the top of the medium-pressure second reaction distillation tower 200 to the first common distillation tower 300. The liquid stream at the bottom of the first common distillation tower 300 automatically flows into the second common distillation tower 400 by pressure difference, and high-purity monosilane is extracted from the top of the second common distillation tower 400.

[0051] In this embodiment, the raw material trichlorosilane is transported from the raw material tank 101 through the first booster pump 102 into the low-pressure first reaction distillation tower 100, and undergoes low-pressure catalytic disproportionation to obtain a third bottom liquid stream 3 and a second top liquid stream 2, and the second top stream 2 is transported to the medium-pressure second reaction distillation tower 200 through the second booster pump 202, and undergoes medium-pressure catalytic disproportionation to obtain a fifth bottom liquid stream 5 and a fourth top liquid stream 4, and the fourth top stream 4 is then transported to the first common distillation tower 300 through the third booster pump 302 to obtain a seventh bottom liquid stream 7 and a sixth top gas stream 6, and the seventh bottom liquid stream 7 directly enters the second common distillation tower 400 to obtain an eighth top stream 8 and a ninth bottom stream 9, and the sixth stream 6 enters the subsequent environmental protection treatment system as a light component impurity, the eighth stream 8 enters the subsequent filling system or storage tank system as a high-purity monosilane product, and the ninth stream 9 enters the medium-pressure second reaction distillation tower 200 as a circulating stream for recycling.

[0052] In addition, the top of the low-pressure first reaction distillation tower 100 includes two-stage condensers, a first stage condenser 103 and a first stage second condenser 104. The liquid phase logistics of the first stage condenser 103 are all refluxed into the first reaction distillation tower 100, and the gas phase logistics enter the first stage second condenser 104 and are all condensed into the first intermediate tank 201, and the cooling medium of the two-stage condensers is circulating cooling water.

[0053] Moreover, the top of the medium-pressure second reaction distillation tower 200 includes multiple condensers, a second first-stage condenser 203, a second second-stage condenser 204, a second third-stage condenser 205 and a second fourth-stage condenser 206. The liquid logistics of the second first-stage condenser 203 and the second second-stage condenser 204 are all refluxed into the medium-pressure second reaction distillation tower 200. The first-stage condenser, that is, the second first-stage condenser 203 uses circulating cooling water as the cooling medium, and the subsequent condensers of each stage use cooling media with decreasing temperature in turn. The liquid logistics of the third and fourth second third-stage condensers 205 and the second fourth-stage condenser 206 are combined and enter the second intermediate tank 301.

[0054] The low-pressure first reaction distillation tower 100 is divided into three sections, wherein the lowest section (mass transfer filler section 10) is filled with mass transfer filler, the middle section and the uppermost section (catalyst section 11) are filled with disproportionation catalyst, and the raw material inlet is located between the two reaction sections (catalyst sections 11).

[0055] The medium-pressure second reaction distillation tower 200 is divided into two sections, wherein the uppermost section (catalyst section 11) is loaded with disproportionation catalyst, and the lower section (mass transfer packing section 10) is loaded with mass transfer packing, and the feed position is between the catalyst section 11 and the mass transfer packing section 10.

[0056] The first common distillation tower 300 and the second common distillation tower 400 are both divided into two sections, and both sections are mass transfer packing sections 10 filled with mass transfer packing.

[0057] The present embodiment provides an energy-saving high-purity monosilane production method, comprising the following steps:

[0058] S1. Low-pressure reactive distillation:

[0059] The raw material trichlorosilane is conveyed from the raw material tank 101 through the first pressure pump 102 from the normal pressure to the first stream 1 and enters the first low-pressure first reaction distillation tower 100. Through the action of the catalyst, a low-pressure disproportionation reaction is carried out, mainly the disproportionation reaction of trichlorosilane occurs, and trichlorosilane is converted into tetrachlorosilane and dichlorosilane, a small amount of monochlorosilane and a very small amount of monosilane. The third stream 3 of tetrachlorosilane is obtained at the bottom of the tower, and the rest enters the top of the tower, and the liquid reflux stream is obtained through the first primary condenser 103 at the top of the tower to enter the top of the low-pressure first reaction distillation tower 100 to provide the liquid phase stream in the tower. The gas phase stream of the first primary condenser 103 enters the subsequent first and second secondary condensers 104 and is completely condensed and enters the first intermediate tank 201.

[0060] Furthermore, the operating pressure of the low-pressure first reaction distillation tower 100 does not exceed 1.0 MPa, but is between 0.4-0.8 MPa, specifically 0.55 MPa, to ensure that the temperature of the lowest part of the intermediate reaction section does not exceed the heat-resistant temperature of the catalyst of 100°C.

[0061] S2, medium pressure reactive distillation:

[0062] The top product obtained from the low-pressure pressurized first reaction distillation tower 100 mainly contains dichlorosilane, unconverted trichlorosilane, a small amount of monochlorosilane and a very small amount of monosilane, which is stored in the first intermediate tank 201 after liquefaction, and is transported to the medium-pressure second reaction distillation tower 200 for medium-pressure disproportionation reaction after being pressurized by the second pressure pump 202, mainly disproportionation reaction of dichlorosilane and monochlorosilane occurs, to obtain the bottom liquid fifth stream 5 and the top gas stream, and the bottom fifth stream 5 is directly returned to the low-pressure first reaction distillation tower 100 for recycling, and the top gas stream is condensed by step cooling medium, and is cooled by 32°C circulating cooling water, 7°C low-temperature water, -20°C freezing medium and -50°C freezing medium in four stages, and all condensed to obtain the liquid fourth stream 4, which enters the second intermediate tank 301;

[0063] Furthermore, the operating pressure of the medium-pressure second reaction distillation tower 200 is 1.5-3.0 times that of the low-pressure distillation tower 100, specifically 1.3 MPa, to ensure that the temperature at the bottom of the reaction section does not exceed the heat-resistant temperature of the catalyst of 100°C.

[0064] S3, high pressure refining:

[0065] The top product obtained from the (secondary) medium-pressure reactive distillation mainly contains monosilane, monochlorosilane, and a small amount of unconverted dichlorosilane, which is stored in the second intermediate tank 301 after liquefaction, and is transported to the first common distillation tower 300 after being pressurized by the third pressure pump 302, and light components with a lower boiling point than monosilane, including N2, O2 and CO, are removed, and then discharged from the top of the first common distillation tower 3006;

[0066] Furthermore, the top of the first common distillation tower 300 also includes two-stage condensation, the first stage uses -50°C refrigeration medium, and the second stage uses -170°C liquid nitrogen to reduce the loss of product monosilane;

[0067] The seventh stream 7 of the bottom liquid of the first high-pressure distillation tower enters the subsequent second common distillation tower 400, and the eighth stream 8 is obtained from the top of the tower as a high-purity monosilane product. The ninth stream 9 of the liquid obtained at the bottom of the tower includes unconverted monochlorosilane and dichlorosilane, and directly enters the second medium-pressure reactive distillation tower 200 for recycling, thereby achieving a high monosilane yield;

[0068] Furthermore, the operating pressure of the first ordinary distillation tower 300 is 1.5-3.0 times the operating pressure of the medium-pressure second reactive distillation tower 200, specifically 2.45 MPa.

[0069] Further, the operating pressure of the low-pressure first reaction distillation tower 100 is less than 1.0 MPa, specifically 0.55 MPa, the operating pressure of the medium-pressure distillation tower 200 is between 1.2-1.5 MPa, specifically 1.3 MPa, and the operating pressures of the two high-pressure distillation towers, the first common distillation tower 300 and the second common distillation tower 400, are between 2.0-3.0 MPa, specifically 2.45 MPa;

[0070] The cooling medium of the multi-stage condenser at the top of the medium-pressure second reaction distillation tower 200 is circulating cooling water in the first stage, and the temperature of subsequent cooling media decreases by 20-30°C, namely 7°C low-temperature water, -20°C and -50°C freezing medium.

[0071] The production scale of this embodiment is 5000 tons / year of monosilane, and the raw material flow rate, that is, the flow rate of the first booster pump is 8.37m 3 / hr (10.922 tons / hr), the flow rate of the second booster pump is 5.32m 3 / hr, the flow rate of the third booster pump is 3.6m 3 / hr, the output of monosilane is 645kg / hr, and the purity reaches 99.99999999%.

[0072] Example 2

[0073] This embodiment provides an energy-saving high-purity silane production process and method. Except for the production scale, other major systems and conditions are the same as those in Example 1. The production scale of this embodiment is 10,000 tons / year of monosilane, and the raw material flow rate, that is, the flow rate of the first booster pump 102 is 16.75m 3 / hr (21.85 tons / hr), the flow rate of the second booster pump 202 is 10.65m 3 / hr, the flow rate of the third booster pump 302 is 7.36m 3 / hr, the output of monosilane is 1290kg / hr, and the purity reaches 99.9999999%.

[0074] Example 3

[0075] This embodiment uses dichlorosilane as a raw material to provide an energy-saving high-purity silane production process and method, with a production scale of 5,000 tons / year of monosilane. Other major systems and conditions are the same as those in Example 1. The operating pressure of the low-pressure first reaction distillation tower 100 is less than 1.0 MPa, specifically 0.75 MPa. The dichlorosilane raw material flow rate of this embodiment, that is, the flow rate of the first booster pump 102 is 4.0 tons / hr, and the flow rate of the second booster pump 202 is 2.75 m / hr. 3 / hr, the flow rate of the third booster pump 302 is 1.66m 3 / hr, the output of monosilane is 633kg / hr, and the purity reaches 99.99999999%.

[0076] Example 4

[0077] like Figure 1 As shown, this embodiment provides an energy-saving high-purity monosilane production system, including four distillation towers, characterized in that two of the distillation towers are reaction distillation towers filled with chlorosilane disproportionation catalysts, and two are ordinary distillation towers, and the first reaction distillation tower is a low-pressure tower, and its operating pressure is less than 1.0Mpa, and the second reaction distillation tower is a medium-pressure tower, and its operating pressure is 1.5-3.0 times that of the reaction distillation tower, and the two ordinary distillation towers are high-pressure towers, and their operating pressure is 1.5-3.0 times that of the second reaction distillation tower, so that the entire production system realizes two-stage boosting operation, thereby improving energy efficiency.

[0078] Furthermore, the invention also comprises three pressure pumps, wherein the first pressure pump pressurizes and transports the raw material trichlorosilane from the raw material tank to the first (low-pressure) reaction distillation tower, the second pressure pump pressurizes and transports the liquid flow extracted from the top of the low-pressure reaction distillation tower to the second (medium-pressure) reaction distillation tower, the third pressure pump pressurizes and transports the liquid flow extracted from the top of the second (medium-pressure) reaction distillation tower to the first high-pressure ordinary distillation tower, and the liquid flow at the bottom of the first high-pressure distillation tower automatically flows into the second high-pressure distillation tower by pressure difference, and the product high-purity monosilane is extracted from the top of the second high-pressure distillation tower. In this way, the compressor of the prior art is replaced by the pressure boosting of the three-stage pump, which is conducive to expanding the scale of large-scale production and reducing investment and energy consumption.

[0079] Furthermore, the raw material trichlorosilane or dichlorosilane is transported from the raw material tank through the first pressure pump into the first (low-pressure) reaction distillation tower to obtain a bottom liquid logistics and a top liquid logistics, the top logistics is transported to the second (medium-pressure) reaction distillation tower through the second pressure pump to obtain a bottom liquid logistics and a top liquid logistics, the top logistics is then transported to the first high-pressure distillation tower through the third pressure pump to obtain a bottom liquid logistics and a top gas logistics, the bottom liquid logistics directly enters the second high-pressure distillation tower to obtain a top logistics and a bottom logistics, and the top logistics of the first high-pressure distillation tower enters the subsequent environmental protection treatment system as an impurity, the top logistics of the second high-pressure distillation tower enters the subsequent filling system or storage tank system as a high-purity monosilane product, and the bottom logistics of the second high-pressure distillation tower enters the second (medium-pressure) reaction distillation tower as a circulating logistics for recycling, so that a high-purity monosilane product can be obtained with low energy consumption and high efficiency.

[0080] Further optimized, the top of the low-pressure reaction distillation tower includes a two-stage condenser, the liquid phase logistics of the first-stage condenser are all refluxed into the low-pressure reaction distillation tower, and the gas phase logistics enters the second-stage condenser and is completely condensed into the intermediate tank, and the cooling medium of the two-stage condenser is circulating cooling water, which can increase the reaction temperature of the low-pressure reaction distillation tower and improve the reaction rate.

[0081] Also further optimized, the top of the medium-pressure reaction distillation tower includes a multi-stage condenser, and the liquid phase logistics of the first-stage condenser are all refluxed into the medium-pressure reaction distillation tower, and circulating cooling water is used as the cooling medium. The subsequent condensers of each stage use cooling media with decreasing temperature in turn, and the liquid phase logistics of each stage are combined and enter the intermediate tank. This can reduce the capacity of the low-temperature cooling medium required for condensation, improve the energy efficiency of the refrigeration system, and reduce power consumption.

[0082] Further optimized, the low-pressure reaction distillation tower is divided into three sections, wherein the lowest section is filled with mass transfer filler, the middle section and the uppermost section are filled with disproportionation catalyst, and the inlet of the raw material trichlorosilane is located between the two reaction sections, which can improve the coupling efficiency of reaction and distillation, reduce catalyst consumption, reduce reflux ratio, and reduce steam energy consumption.

[0083] Further optimized, the medium-pressure reaction distillation tower is divided into two sections, wherein the uppermost section is loaded with a disproportionation catalyst, and the lower section is loaded with a mass transfer filler, and the feed position is between the catalyst section and the mass transfer filler section, which can also reduce catalyst consumption and steam consumption.

[0084] A method for utilizing the above energy-saving high-purity monosilane production system comprises the following steps:

[0085] (1) Low-pressure reactive distillation:

[0086] The raw material trichlorosilane or dichlorosilane is conveyed from the raw material storage tank by a primary pressure pump from normal pressure to a low-pressure reaction distillation tower, and a low-pressure disproportionation reaction is carried out by the action of a catalyst, mainly a disproportionation reaction of trichlorosilane occurs, trichlorosilane is converted into tetrachlorosilane and dichlorosilane, a small amount of monochlorosilane and a very small amount of monosilane, a tetrachlorosilane stream is obtained at the bottom of the tower, and the rest enters the top of the tower, and a liquid reflux stream is obtained through a top condenser to enter the top of the low-pressure reaction distillation tower to provide a liquid phase stream in the tower, and the gas phase stream of the primary condenser enters a subsequent secondary condenser and is completely condensed and enters a first intermediate tank;

[0087] The operating pressure of the low-pressure reaction distillation tower does not exceed 1.0 MPa, preferably, between 0.4-0.7 MPa, ensuring that the temperature of the lowest part of the intermediate reaction section does not exceed the heat resistance temperature of the catalyst, generally between 80-100°C;

[0088] (2) Medium pressure reactive distillation:

[0089] The top product obtained from the low-pressure reaction distillation tower mainly contains dichlorosilane, unconverted trichlorosilane, a small amount of monochlorosilane and a very small amount of monosilane, which is stored in the first intermediate tank after liquefaction, and is transported to the medium-pressure reaction distillation tower after being pressurized by the secondary pressure pump for medium-pressure reaction, mainly undergoing disproportionation reaction of dichlorosilane and monochlorosilane, to obtain a bottom liquid stream and a top gas stream, and the bottom stream is directly returned to the low-pressure reaction distillation tower for recycling, and the top gas stream is step-condensed by a step cooling medium to obtain a liquid stream, which enters the second intermediate tank;

[0090] The operating pressure of the medium-pressure reaction distillation tower is 1.5-3.0 times the operating pressure of the low-pressure distillation tower, ensuring that the temperature of the lowest part of the reaction section does not exceed the heat resistance temperature of the catalyst, generally at 80-100°C;

[0091] (3) High pressure refining:

[0092] The top product obtained from the medium-pressure reactive distillation tower mainly contains monosilane, monochlorosilane, and a small amount of unconverted dichlorosilane, which is stored in the second intermediate tank after liquefaction, and is transported to the first high-pressure distillation tower after being pressurized by the three-stage pressure pump, and light components with a lower boiling point than monosilane, including N2, O2 and CO, are removed, and discharged from the top gas phase of the first high-pressure distillation tower;

[0093] The top of the high-pressure distillation tower also includes multi-stage condensation to reduce the loss of product monosilane;

[0094] The liquid stream at the bottom of the first high-pressure distillation tower enters the subsequent second high-pressure distillation tower, and a high-purity monosilane product is obtained from the top of the tower. The liquid stream obtained at the bottom of the tower includes unconverted monochlorosilane and dichlorosilane, which directly enter the medium-pressure reactive distillation tower for recycling through the pressure difference;

[0095] The operating pressure of the first high-pressure distillation tower is 1.5-3.0 times the operating pressure of the medium-pressure reaction distillation tower.

[0096] Optimally, the operating pressure of the low-pressure reaction distillation tower is between 0.4-0.8 MPa, the operating pressure of the medium-pressure reaction distillation tower is between 1.2-1.5 MPa, and the operating pressure of the first and second high-pressure distillation towers is between 2.0-3.0 MPa.

[0097] Further optimized, the cooling medium of the multi-stage condenser at the top of the medium-pressure reactive distillation tower is circulating cooling water in the first stage, and the temperature of each subsequent cooling medium decreases by 20-30°C in sequence.

[0098] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. An energy-saving high-purity monosilane production system, characterized in that: The system comprises a first reaction distillation tower (100), a second reaction distillation tower (200), a first common distillation tower (300), and a second common distillation tower (400); The first reaction distillation tower (100), the second reaction distillation tower (200), the first common distillation tower (300), and the second common distillation tower (400) are connected in sequence; The second common distillation tower (400) is connected to the second reactive distillation tower (200); The first reaction distillation tower (100) and the second reaction distillation tower (200) are both filled with a chlorosilane disproportionation catalyst; The first reactive distillation tower (100) is a low-pressure tower, and its operating pressure is less than 1.0 MPa; The second reaction distillation tower (200) is a medium-pressure tower, and its operating pressure is 1.5-3.0 times that of the first reaction distillation tower (100); The first common distillation tower (300) and the second common distillation tower (400) are both high-pressure towers, and their operating pressures are 1.5-3.0 times that of the second reactive distillation tower (200).

2. An energy-saving high-purity monosilane production system according to claim 1, characterized in that: The system further comprises a raw material tank (101); The raw material tank (101) is connected to the first reactive distillation tower (100).

3. An energy-saving high-purity monosilane production system according to claim 2, characterized in that: The system further comprises a first boosting pump (102), a second boosting pump (202), and a third boosting pump (302); The first pressure pump (102) is disposed between the raw material tank (101) and the first reactive distillation tower (100); The second pressure pump (202) is disposed between the first reaction distillation tower (100) and the second reaction distillation tower (200); The third pressure pump (302) is arranged between the second reactive distillation tower (200) and the first common distillation tower (300).

4. The energy-saving high-purity monosilane production system according to claim 1, characterized in that: The top of the first reaction distillation tower (100) is provided with two-stage condensers, namely a first-stage condenser (103) and a first-stage second-stage condenser (104); The first primary condenser (103) is connected to the first secondary condenser (104); The first and second level condensers (104) are connected to the first intermediate tank (201).

5. The energy-saving high-purity monosilane production system according to claim 1, characterized in that: The top of the second reaction distillation tower (200) is provided with a multi-stage condenser. The multi-stage condenser comprises a second first-stage condenser (203) and subsequent condensers of various stages connected in sequence; The multi-stage condenser is connected to the second intermediate tank (301).

6. The energy-saving high-purity monosilane production system according to claim 1, characterized in that: The first reactive distillation tower (100) is divided into three sections, wherein the lowest section is a mass transfer filler section (10) filled with a mass transfer filler, and the middle section and the uppermost section are catalyst sections (10) filled with a disproportionation catalyst; The middle section and the uppermost section are two reaction sections; The feed inlet is located between the two reaction stages.

7. The energy-saving high-purity monosilane production system according to claim 1, characterized in that: The second reaction distillation tower (200) is divided into two sections, wherein the uppermost section is a catalyst section (10) loaded with a disproportionation catalyst, and the lower section is a mass transfer filler section (10) loaded with a mass transfer filler; The feed point is between the catalyst section (11) and the mass transfer packing section (10).

8. An energy-saving high-purity monosilane production method using the energy-saving high-purity monosilane production system according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: S1, low-pressure reactive distillation: the raw material trichlorosilane or dichlorosilane is conveyed from atmospheric pressure to a first reactive distillation tower (100), and a low-pressure disproportionation reaction is carried out by the action of a catalyst, so that a disproportionation reaction of trichlorosilane occurs, and a third tetrachlorosilane stream (3) is obtained at the bottom of the tower. The remaining products enter the top of the tower, and are condensed to obtain a liquid reflux stream, which enters the top of the first reactive distillation tower (100) to provide a liquid phase stream in the tower, and the condensed gas phase stream is subsequently condensed in its entirety; S2, medium-pressure reactive distillation: the top product obtained by the first-stage pressurized reactive distillation is liquefied and then pressurized, and then transported to the second reactive distillation tower (200) for medium-pressure reaction, so that dichlorosilane and monochlorosilane undergo a disproportionation reaction to obtain a bottom liquid fifth stream (5) and a top gas stream, and the bottom fifth stream (5) is directly returned to the first reactive distillation tower (100) for recycling, and the top gas stream is step-condensed by a step-cooling medium to obtain a liquid fourth stream (4); S3, high-pressure refining: the top product obtained by the secondary pressure reaction distillation is liquefied and then pressurized, and then transported to the first common distillation tower (300) to remove light components with a boiling point lower than that of monosilane, and a sixth stream (6) is discharged from the top of the first common distillation tower (300) through condensation; The seventh liquid stream (7) at the bottom of the tower enters the subsequent second ordinary distillation tower (400), and the high-purity eighth stream (8) as the monosilane product is obtained from the top of the tower. The ninth liquid stream (9) obtained at the bottom of the tower directly enters the second reactive distillation tower (200) for recycling.

9. The energy-saving high-purity monosilane production method according to claim 8, characterized in that: The operating pressure of the first reaction distillation tower (100) is between 0.4-0.8Mpa; The operating pressure of the second reaction distillation tower (200) is between 1.2-1.5 MPa; The operating pressure of the first ordinary distillation tower (300) and the second ordinary distillation tower (400) is between 2.0 and 3.0 MPa.

10. The energy-saving high-purity monosilane production method according to claim 8, characterized in that: The top of the second reaction distillation tower (200) is provided with a multi-stage condenser; In the cooling medium of the multi-stage condenser, the first stage is circulating cooling water, and the temperature of each subsequent cooling medium drops by 20-30℃ in turn.

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