CN113184857A - Preparation method and device of silicon tetrafluoride - Google Patents
Preparation method and device of silicon tetrafluoride Download PDFInfo
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Abstract
The invention relates to a preparation method and a device of silicon tetrafluoride, belonging to the technical field of fluoride preparation. The method and apparatus pass through SiO2And H2Reaction of SiO2Reducing to Si, introducing mixed gas of fluorine gas and nitrogen gas, and mixing Si and F2Obtaining crude SiF by fluorination reaction4Crude SiF4Collecting the product to a low-temperature storage tank, vacuumizing the low-temperature storage tank to remove light component impurities to obtain high-purity SiF4. The device mainly comprises: reaction tower, layering plate, vacuum pipeline, discharge pipeline, dust remover, filter, hydrogen pipeline, gas mixture pipeline, exhaust pipeline, cooling kettle, cooling column, cooling pipeline, analysis pipeline and evacuation pipeline. The preparation method and the device are simple and efficient, the raw material source is wide, the cost is low, and the prepared SiF4The purity is as high as 99.999 percent; and new impurities which are difficult to remove are not introduced, and the problems of high acidity, difficult treatment of products, easy wall hanging and the like in the conventional silicon tetrafluoride preparation method are solved.
Description
Technical Field
The invention relates to a preparation method and a device of silicon tetrafluoride, belonging to the technical field of fluoride preparation.
Background
Silicon tetrafluoride is widely used in the electronic and semiconductor industry, can be used for producing high-purity quartz glass, solar cells, silicon nitride, etchants, P-type dopants and epitaxial deposition diffusion silicon sources, and can also be used for preparing hardening agents, photosensitizers, electronic-grade silanes or polysilicon and the like of cement and marble. Silicon tetrafluoride is also an important component in the ion implantation method adopted in the manufacture of silicon-based semiconductor devices, and has wide application prospect in the microelectronic industry.
Various methods for producing silicon tetrafluoride have been disclosed in the literature or patents at present. CN101973553 of Vanfu (group) Limited liability company adopts a mode of mixing and heating fluosilicic acid and concentrated sulfuric acid to obtain a mixture of hydrogen fluoride and silicon tetrafluoride gas. CN101948114 of Yunnan province chemical research institute adopts a method of acidifying sodium fluosilicate with sulfuric acid to prepare silicon tetrafluoride and anhydrous hydrogen fluoride. CN101544374 of Liu-nine silicon industries, Ltd, NaAlF was used4And mixing the raw material powder and the Si source powder, and introducing concentrated sulfuric acid for heating to prepare the silicon tetrafluoride. CN 10169882 of Simian Sanrui industries, Inc. adopts a method for preparing silicon tetrafluoride by thermally cracking sodium fluosilicate in a reaction furnace. The method is a mixture of a plurality of substances, the components are complex, the produced silicon tetrafluoride has more impurities and large acidity, and the product is difficult to treat and easy to hang on the wall.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention aims to provide a method and a device for preparing silicon tetrafluoride; by means of silicon dioxide (SiO)2) With hydrogen (H)2) Reduction reaction of (2) SiO2Reducing the silicon (Si) into a simple substance, and then introducing mixed gas of fluorine gas and nitrogen gasReacting the simple substance Si with fluorine gas (F)2) Carrying out fluorination reaction to obtain crude silicon tetrafluoride (SiF)4) And collecting the gas and the crude silicon tetrafluoride gas to a low-temperature storage tank through a discharge pipeline, and vacuumizing the low-temperature storage tank to remove light component impurities to obtain the silicon tetrafluoride with the purity of 99.999%.
In order to achieve the purpose of the invention, the following technical scheme is provided.
A preparation method of silicon tetrafluoride comprises the following steps:
firstly, washing the SiO with water2Placing the particles serving as a silicon source on a layering plate in a reaction tower in a layering manner, vacuumizing the reaction tower from the top of the reaction tower, heating the layering plate to 200-400 ℃, and removing water;
SiO2the particles can be prepared by crushing, thermally decomposing, acid washing and water washing rocks and gravels mainly containing silicate and silicon dioxide in nature; the thermal decomposition temperature is 300-500 ℃, and the acid for pickling is dilute hydrochloric acid with the mass fraction of 10-20%.
The water for washing is preferably ultrapure water having a resistivity of 10 M.OMEGA.CM or more.
Preferably the SiO2The particle size of the particles is 5 mm-20 mm.
Preferably, the vacuumizing time of the tower top is 10-15 h.
② introducing 99.9 percent hydrogen by volume into the reaction tower, reacting for 5-10 h at 200-400 ℃ as shown in formula I, and reacting SiO2Is reduced into a simple substance of Si,
H2+SiO2→Si+H2OΙ。
thirdly, the reaction tower is continuously heated and vacuumized, the heating temperature is 200-400 ℃, the vacuumization time is 5-10H, and residual reducing H in the reaction tower is removed2And H2O; then introducing mixed gas of fluorine gas and nitrogen gas, reacting for 3-8 h at 100-200 ℃ as shown in the specification to obtain crude SiF4，
Si+F2→SiF4Ⅱ；
Preferably, the volume fraction of the fluorine gas in the mixed gas of the fluorine gas and the nitrogen gas is 20% to 40%.
Fourthly, the crude product SiF prepared in the third step4The liquid nitrogen is collected to a low-temperature storage tank through a discharge pipeline of the reaction tower, the low-temperature storage tank is composed of a cooling kettle and a cooling column connected above the cooling kettle, and liquid nitrogen jackets are arranged on the outer sides of the cooling kettle and the cooling column; the temperature of the cooling kettle is-90 ℃ to-150 ℃, the temperature of the cooling column is-50 ℃ to-90 ℃, then the low-temperature storage tank is vacuumized to 1KPa to 2KPa, and residual gas light component impurities such as nitrogen or fluorine gas in the low-temperature storage tank are pumped out, so that the high-purity silicon tetrafluoride is obtained.
Preferably, the temperature of the cooling kettle is-110 ℃ to-150 ℃, and the temperature of the cooling column is-60 ℃ to-80 ℃.
Preferably, a vacuum is drawn from above the cryogenic tank to 1 KPa.
A silicon tetrafluoride preparation device, which is used in the silicon tetrafluoride preparation method of the invention, comprises the following main components: reaction tower, layered plate, vacuum pipeline, reaction tower vacuum valve, discharge pipeline, dust remover, filter and crude SiF4The system comprises a feed valve, a reaction tower pressure gauge, a hydrogen pipeline, a hydrogen feed valve, a hydrogen one-way valve, a mixed gas pipeline, a mixed gas feed valve, a mixed gas one-way valve, a drain pipeline, a drain valve, a cooling kettle liquid nitrogen jacket, a cooling kettle liquid nitrogen cooling valve, a cooling column liquid nitrogen jacket, a cooling column liquid nitrogen cooling valve, a cooling pipeline, a cooling vacuum valve, a low-temperature storage tank pressure gauge, an analysis pipeline, an analysis valve, an emptying pipeline, a safety relief valve and a thermometer.
The device comprises the following components in specific connection position relationship:
a plurality of layered plates are arranged in the reaction tower, and pore passages are arranged on the layered plates and are smaller than SiO which is a silicon source2The grain diameter of the particles, and the layered plate is provided with a heating device.
The top of the reaction tower is connected with an external vacuumizing device through a vacuum pipeline, and a reaction tower vacuum valve is arranged on the vacuum pipeline; the top of the reaction tower is connected with the top of the cooling kettle through a discharge pipeline, and a dust remover, a filter and a crude product S are sequentially arranged on the discharge pipeline from the reaction tower to the cooling kettleiF4And a feed valve. The top of the reaction tower is also provided with a reaction tower pressure gauge.
The lower part of the tower body of the reaction tower is connected with hydrogen through a hydrogen pipeline, a hydrogen feeding valve is arranged on the hydrogen pipeline and close to the reaction tower, and a hydrogen one-way valve is arranged outside the hydrogen feeding valve; the lower part of the tower body of the reaction tower is connected with mixed gas of fluorine gas and nitrogen gas through a mixed gas pipeline, a mixed gas feeding valve is arranged on the mixed gas pipeline and close to the reaction tower, and a mixed gas one-way valve is arranged on the outer side of the mixed gas feeding valve.
The bottom of the reaction tower is connected with a drain pipeline, and a drain valve is arranged on the drain pipeline.
The low-temperature storage tank consists of a cooling kettle and a cooling column connected above the cooling kettle, wherein a cooling kettle liquid nitrogen jacket is arranged on the outer side of the cooling kettle and is connected with a cooling pipeline through a pipeline provided with a cooling kettle liquid nitrogen cooling valve; and a cooling column liquid nitrogen jacket is arranged on the outer side of the cooling column, the cooling column liquid nitrogen jacket is connected with a cooling pipeline through a pipeline provided with a cooling column liquid nitrogen cooling valve, and the cooling pipeline is connected with liquid nitrogen. The upper part of the cooling column is connected to a vacuum pipeline through a pipeline provided with a cooling vacuum valve. And a low-temperature storage tank pressure gauge is arranged at the top of the cooling column.
The top of the cooling kettle is connected with an analysis detection device through an analysis pipeline, and an analysis valve is arranged on the analysis pipeline; the analytical detection device may be helium ionization gas chromatography.
The top of the cooling kettle is connected with an emptying pipeline, and a safety relief valve is arranged on the emptying pipeline.
The reaction tower body and the cooling kettle top are respectively provided with thermometers, preferably, the upper part of the tower body is provided with a platinum resistor T1 as the thermometer, the lower part of the tower body is provided with a platinum resistor T2 as the thermometer, and the cooling kettle top is provided with a platinum resistor T3 as the thermometer.
Preferably, the reaction tower and the laminated plate are made of stainless steel doped with chromium or molybdenum; the top of the reaction tower is sealed by a flange.
Preferably, the cooling kettle and the cooling column are made of stainless steel.
Preferably, the pipeline is an EP grade stainless steel pipe.
Preference is given to the reactionColumn vacuum valve, crude SiF4The feed valve, the hydrogen feed valve, the mixed gas feed valve, the drain valve, the cooling vacuum valve and the safety relief valve adopt sealed stop valves; a cooling kettle liquid nitrogen cooling valve and a cooling column liquid nitrogen cooling valve adopt low-temperature stop valves; the analysis valve adopts a diaphragm valve with good sealing performance.
The preparation device of the silicon tetrafluoride is suitable for the preparation method of the silicon tetrafluoride, and before the device is started to work, a reaction tower vacuum valve and a crude product SiF4The feed valve, the hydrogen feed valve, the mixed gas feed valve, the drain valve, the cooling kettle liquid nitrogen cooling valve, the cooling column liquid nitrogen cooling valve, the cooling vacuum valve and the analysis valve are all in a closed state.
When the device works, the working mode is as follows;
firstly, washing the SiO with water2Placing particles as a silicon source on a layered plate in a reaction tower, starting the device, firstly opening a vacuum valve of the reaction tower, vacuumizing the reaction tower from the top of the reaction tower through a vacuum pipeline, heating the layered plate to 200-400 ℃ by using a heating device, and removing water in the silicon source;
secondly, opening a hydrogen feeding valve, introducing hydrogen with the volume fraction of 99.9 percent into the reaction tower through a hydrogen pipeline, reacting for 5 to 10 hours at 200 to 400 ℃ as shown in the formula I, and reacting SiO2Reducing the silicon into a simple substance Si, closing a hydrogen feeding valve, and stopping introducing hydrogen;
H2+SiO2→Si+H2OΙ。
thirdly, the reaction tower is continuously heated and vacuumized, the heating temperature is 200-400 ℃, the vacuumization time is 5-10H, and residual reducing H in the reaction tower is removed2And H2O, arranging a tail gas outlet on the vacuum pipeline for combustible gas detection, and closing a vacuum valve of the reaction tower when the concentration of the combustible gas is detected to be 0 ppm;
opening a liquid nitrogen cooling valve of the cooling kettle and a liquid nitrogen cooling valve of a cooling column, and injecting liquid nitrogen into a liquid nitrogen jacket of the cooling kettle and a liquid nitrogen jacket of the cooling column through cooling pipelines to reduce the temperature, so that the temperature of the cooling kettle is-90 ℃ to-150 ℃, and the temperature of the cooling column is-50 ℃ to-90 ℃;
opening a mixed gas feed valve, introducing mixed gas of fluorine and nitrogen into the reaction tower through a mixed gas pipeline, and adding the crude SiF4The feeding valve is opened, the reaction shown as II is carried out in the reaction tower at the temperature of 100-200 ℃, the reaction lasts for 3-8 h, and crude SiF is obtained4；
Si+F2→SiF4Ⅱ。
Fourthly, the crude product SiF prepared in the third step4Enters a discharge pipeline, sequentially passes through a dust remover and a filter, enters a cooling kettle, and is subjected to SiF4After condensation, the solid is formed and sinks to the bottom of the cooling kettle, light component impurities of residual gas such as nitrogen, fluorine gas and the like float to the cooling column, when the pressure of a low-temperature storage tank pressure gauge is greater than that of a reaction tower pressure gauge, a cooling vacuum valve is opened, the upper part of the cooling column is vacuumized to 1 KPa-2 KPa through a vacuum pipeline, the light component impurities are removed, and high-purity SiF is obtained4。
For the prepared high-purity SiF4The purity of (b) was determined as follows:
crude SiF is turned off4A feed valve, a mixed gas feed valve and a cooling vacuum valve; the liquid nitrogen is introduced into the cooling kettle at a temperature of-80 to-90 ℃, and the SiF4Vaporizing, opening the analysis valve, SiF4Introducing into an analytical instrument via an analytical pipeline for detection to obtain the SiF4The purity reaches 99.999 percent. In the process of adjusting the liquid nitrogen input amount to enable the temperature in the cooling kettle to be-80 ℃ to-90 ℃, if the pressure of the cooling kettle is too high, the safety relief valve is opened, gas is released through the emptying pipeline, and the pressure is reduced.
When the device works, the temperature in the reaction process is detected through thermometers arranged on the tower body of the reaction tower and the top of the cooling kettle.
Advantageous effects
1. The invention provides a preparation method and a device of silicon tetrafluoride, and the preparation method and the device have the advantages of simple and efficient process, wide raw material source and low cost.
2. The invention provides a preparation method and a device of silicon tetrafluoride, which do not adopt concentrated sulfuric acid or hydrogen fluoride, do not introduce new impurities which are difficult to remove, and solve the problems of high acidity, difficult treatment of products, easy wall hanging and the like in the existing preparation method of the silicon tetrafluoride.
3. The invention provides a preparation method and a device of silicon tetrafluoride, and the preparation method and the device can produce the silicon tetrafluoride with the purity of 99.999 percent.
Drawings
Fig. 1 is a schematic view of a silicon tetrafluoride production apparatus according to example 1.
Wherein, 1-reaction tower, 2-layered plate, 3-silicon source, 4-vacuum pipeline, 5-reaction tower vacuum valve, 6-discharge pipeline, 7-dust remover, 8-filter, 9-crude SiF4A feed valve, 10-a reaction tower pressure gauge, 11-a hydrogen pipeline, 12-a hydrogen feed valve, 13-a hydrogen check valve, 14-a mixed gas pipeline, 15-a mixed gas feed valve, 16-a mixed gas check valve, 17-a drain pipeline, 18-a drain valve, 19-a cooling kettle, 20-a cooling kettle liquid nitrogen jacket, 21-a cooling kettle liquid nitrogen cooling valve, 22-a cooling column, 23-a cooling column liquid nitrogen jacket, 24-a cooling column liquid nitrogen cooling valve, 25-a cooling pipeline, 26-a cooling vacuum valve, 27-a low-temperature storage tank pressure gauge, 28-an analysis pipeline, 29-an analysis valve, 30-a vent pipeline, 31-a safety relief valve, 32-a platinum resistor T1, 33-a platinum resistor T2, 34-a platinum resistor T3
Detailed Description
The invention is described in detail below with reference to the drawings and specific examples, but the invention is not limited thereto.
The structure of a silicon tetrafluoride production apparatus used in the following examples is shown in fig. 1, and the main components of the apparatus include: reaction tower 1, layered plate 2, vacuum pipeline 4, reaction tower vacuum valve 5, discharge pipeline 6, dust remover 7, filter 8, crude SiF4 A feed valve 9, a reaction tower pressure gauge 10, a hydrogen pipeline 11, a hydrogen feed valve 12, a hydrogen one-way valve 13, a mixed gas pipeline 14, a mixed gas feed valve 15, a mixed gas one-way valve 16, a drain pipeline 17, a drain valve 18, a cooling kettle 19, a cooling kettle liquid nitrogen jacket 20, a cooling kettle liquid nitrogen cooling valve 21, a cooling column 22, a cooling column liquid nitrogenThe system comprises a jacket 23, a cooling column liquid nitrogen cooling valve 24, a cooling pipeline 25, a cooling vacuum valve 26, a low-temperature storage tank pressure gauge 27, an analysis pipeline 28, an analysis valve 29, a vent pipeline 30, a safety relief valve 31 and a thermometer.
The device comprises the following components in specific connection position relationship:
a plurality of layered plates 2 are arranged in the reaction tower 1, and pore passages smaller than SiO are arranged on the layered plates 22The grain diameter of the particles, and a heating device is arranged on the layered plate 2.
The top of the reaction tower 1 is connected with an external vacuumizing device through a vacuum pipeline 4, and a reaction tower vacuum valve 5 is arranged on the vacuum pipeline 4; the top of the reaction tower 1 is connected with the top of the cooling kettle 19 through a discharge pipeline 6, and a dust remover 7, a filter 8 and a crude product SiF are sequentially arranged on the discharge pipeline 6 from the reaction tower 1 to the cooling kettle 194 A feed valve 9; one end of the vacuum pipeline 4 and one end of the discharge pipeline 6 are converged into a pipeline and then connected with the top of the reaction tower 1. The top of the reaction tower 1 is also provided with a reaction tower pressure gauge 10.
The lower part of the tower body of the reaction tower 1 is connected with hydrogen through a hydrogen pipeline 11, a hydrogen feeding valve 12 is arranged on the hydrogen pipeline 11 and close to the reaction tower 1, and a hydrogen one-way valve 13 is arranged on the outer side of the hydrogen feeding valve 12; the lower part of the tower body of the reaction tower 1 is connected with the mixed gas of fluorine gas and nitrogen gas through a mixed gas pipeline 14, a mixed gas feeding valve 15 is arranged on the mixed gas pipeline 14 and close to the reaction tower 1, and a mixed gas one-way valve 16 is arranged on the outer side of the mixed gas feeding valve 15.
The bottom of the reaction tower 1 is connected with a drain pipeline 17, and a drain valve 18 is arranged on the drain pipeline 17.
The low-temperature storage tank is composed of a cooling kettle 19 and a cooling column 22 connected above the cooling kettle 19, a cooling kettle liquid nitrogen jacket 20 is arranged on the outer side of the cooling kettle 19, and the cooling kettle liquid nitrogen jacket 20 is connected with a cooling pipeline 25 through a pipeline provided with a cooling kettle liquid nitrogen cooling valve 21; and a cooling column liquid nitrogen jacket 23 is arranged on the outer side of the cooling column 22, the cooling column liquid nitrogen jacket 23 is connected with a cooling pipeline 25 through a pipeline provided with a cooling column liquid nitrogen cooling valve 24, and the cooling pipeline 25 is connected with liquid nitrogen. The upper part of the cooling column 22 is connected to the vacuum line 4 through a line provided with a cooling vacuum valve 26. The top of the cooling column 22 is provided with a cryogenic tank pressure gauge 27.
The top of the cooling kettle 19 is connected with an analysis detection device through an analysis pipeline 28, and an analysis valve 29 is arranged on the analysis pipeline 28; the analysis and detection device is helium ionization gas chromatography.
The top of the cooling kettle 19 is connected with an emptying pipeline 30, and a safety relief valve 31 is arranged on the emptying pipeline 30.
Thermometers are respectively arranged on the tower body of the reaction tower 1 and the top of the cooling kettle 19, a platinum resistor T132 is arranged on the upper part of the tower body and is used as the thermometer, a platinum resistor T233 is arranged on the lower part of the tower body and is used as the thermometer, and a platinum resistor T334 is arranged on the top of the cooling kettle 19 and is used as the thermometer.
The reaction tower 1 and the layered plate 2 are made of stainless steel doped with chromium or molybdenum; the top of the reaction tower 1 is sealed by a flange.
The cooling kettle 19 and the cooling column 22 are made of stainless steel.
The pipeline adopts an EP-grade stainless steel pipe.
Vacuum valve 5 of reaction tower, crude SiF4The feed valve 9, the hydrogen feed valve 12, the mixed gas feed valve 15, the drain valve 18, the cooling vacuum valve 26 and the safety relief valve 31 adopt sealed stop valves; the cooling kettle liquid nitrogen cooling valve 21 and the cooling column liquid nitrogen cooling valve 24 adopt low-temperature stop valves; the analysis valve 29 is a diaphragm valve having good sealing performance.
Before the device starts to work, the vacuum valve 5 of the reaction tower and the crude product SiF4The feed valve 9, hydrogen feed valve 12, mixed gas feed valve 15, purge valve 18, chilled kettle liquid nitrogen cooling valve 21, chilled column liquid nitrogen cooling valve 24, chilled vacuum valve 26, and analysis valve 29 are all in a closed state.
In the following examples, the purity of silicon tetrafluoride was measured by a deduction method.
Example 1
A preparation method of silicon tetrafluoride, which is carried out by adopting a preparation device of silicon tetrafluoride shown in figure 1, and comprises the following steps:
crushing rock and gravel mainly containing silicate and silicon dioxide in nature into particles with the particle size of 5mm, performing thermal decomposition at 300 ℃, and performing thermal decomposition by using 10% of dilute hydrochloric acidAcid washing, then washing with ultrapure water with the resistivity of 10M omega & CM to obtain relatively pure SiO2And (3) granules.
Washing the SiO2Placing the particles as a silicon source 3 on a layered plate 2 in a reaction tower 1, starting the device, firstly opening a vacuum valve 5 of the reaction tower, vacuumizing for 10 hours from the top of the reaction tower 1 through a vacuum pipeline 4, heating the layered plate 2 to 200 ℃ by using a heating device, removing moisture in the silicon source 3, and obtaining dry SiO2。
Secondly, opening a hydrogen feeding valve 12, introducing hydrogen with the volume fraction of 99.9 percent into the reaction tower 1 through a hydrogen pipeline 11, heating the laminated plate 2 to 200 ℃ to generate a reaction shown as the formula I, reacting for 5 hours, and reacting SiO2Reducing the silicon into a simple substance Si, closing the hydrogen feeding valve 12 and stopping feeding hydrogen;
H2+SiO2→Si+H2OΙ。
thirdly, the reaction tower 1 is continuously heated and vacuumized, the temperature of the heating laminated plate 2 is 200 ℃, the vacuumizing time is 5 hours, and residual reducing H in the reaction tower 1 is removed2And H2O, a tail gas outlet is arranged on the vacuum pipeline 4 for combustible gas detection, and when the concentration of the combustible gas is detected to be 0ppm, the vacuum valve 5 of the reaction tower is closed;
opening a cooling kettle liquid nitrogen cooling valve 21 and a cooling column liquid nitrogen cooling valve 24, and injecting liquid nitrogen into a cooling kettle liquid nitrogen jacket 20 and a cooling column liquid nitrogen jacket 23 through a cooling pipeline 25 to reduce the temperature, so that the temperature of the cooling kettle 19 is-110 ℃ and the temperature of a cooling column 22 is-60 ℃;
opening a mixed gas feed valve 15, introducing a fluorine gas and nitrogen gas mixed gas into the reaction tower 1 through a mixed gas pipeline 14, wherein the volume fraction of the fluorine gas in the mixed gas is 20%, and adding the crude SiF4The feed valve 9 is opened, the temperature of the laminated plate 2 is heated to 100 ℃ in the reaction tower 1, the reaction shown as II is carried out, the reaction lasts for 3 hours, and crude SiF is obtained4；
Si+F2→SiF4Ⅱ。
Fourthly, the crude product SiF prepared in the third step4Enters a discharge pipeline 6, sequentially passes through a dust remover 7 and a filter 8, enters a cooling kettle 19, and is subjected to SiF4Condensing to form solid and sinking to the bottom of a cooling kettle 19, floating residual gas light component impurities such as nitrogen, fluorine and the like to a cooling column 22, opening a cooling vacuum valve 26 when the pressure of a low-temperature storage tank pressure gauge 27 is greater than the pressure of a reaction tower pressure gauge 10, vacuumizing the low-temperature storage tank to 1KPa from the upper part of the cooling column 22 through a vacuum pipeline 4, and removing the light component impurities to obtain high-purity SiF4。
For the prepared high-purity SiF4The purity of (b) was determined as follows:
crude SiF is turned off4 Feed valve 9, mixed gas feed valve 15, and cooling vacuum valve 26; the liquid nitrogen is introduced into the cooling kettle 19 and the temperature is slowly and naturally raised to-80 ℃ by adjusting the introduction amount of the liquid nitrogen, and the SiF4Vaporizing, opening the analysis valve 29, SiF4Helium ionized gas chromatography is introduced into an analytical instrument through an analytical pipeline 28 for detection, and the high-purity SiF is detected4The purity was 99.999%. In the process of adjusting the liquid nitrogen input amount to heat the cooling kettle 19, if the pressure of the cooling kettle 19 is too high, the safety relief valve 31 is opened, the gas is released through the vent pipeline 30, and the pressure is reduced.
When the device works, the temperature in the reaction process is detected through thermometers arranged on the tower body of the reaction tower 1 and the top of the cooling kettle 19.
Example 2
A preparation method of silicon tetrafluoride, which is carried out by adopting a preparation device of silicon tetrafluoride shown in figure 1, and comprises the following steps:
crushing rocks and gravels mainly comprising silicate and silicon dioxide in nature into particles with the particle size of 20mm, performing thermal decomposition at 500 ℃, washing with 20% dilute hydrochloric acid, and washing with ultrapure water with the resistivity of 14M omega & CM to obtain pure SiO2And (3) granules.
Washing the SiO2Placing the particles as a silicon source 3 on a layered plate 2 in a reaction tower 1, starting the device, firstly opening a vacuum valve 5 of the reaction tower, vacuumizing for 15h from the top of the reaction tower 1 through a vacuum pipeline 4, heating the layered plate 2 to 400 ℃ by using a heating device, removing moisture in the silicon source 3, and obtaining dry SiO2。
Secondly, opening a hydrogen feeding valve 12, introducing hydrogen with the volume fraction of 99.9 percent into the reaction tower 1 through a hydrogen pipeline 11, heating the laminated plate 2 to 400 ℃ to generate a reaction shown as the formula I, reacting for 10 hours, and reacting SiO2Reducing the silicon into a simple substance Si, closing the hydrogen feeding valve 12 and stopping feeding hydrogen;
H2+SiO2→Si+H2OΙ。
thirdly, the reaction tower 1 is continuously heated and vacuumized, the temperature of the heating laminated plate 2 is 400 ℃, the vacuumizing time is 10 hours, and residual reducing H in the reaction tower 1 is removed2And H2O, a tail gas outlet is arranged on the vacuum pipeline 4 for combustible gas detection, and when the concentration of the combustible gas is detected to be 0ppm, the vacuum valve 5 of the reaction tower is closed;
opening a cooling kettle liquid nitrogen cooling valve 21 and a cooling column liquid nitrogen cooling valve 24, and injecting liquid nitrogen into a cooling kettle liquid nitrogen jacket 20 and a cooling column liquid nitrogen jacket 23 through a cooling pipeline 25 to reduce the temperature, so that the temperature of the cooling kettle 19 is-150 ℃ and the temperature of a cooling column 22 is-80 ℃;
opening a mixed gas feed valve 15, introducing a fluorine gas and nitrogen gas mixed gas into the reaction tower 1 through a mixed gas pipeline 14, wherein the volume fraction of the fluorine gas in the mixed gas is 40%, and adding the crude SiF4The feeding valve 9 is opened, the temperature of the laminated plate 2 is heated to 200 ℃ in the reaction tower 1, the reaction shown as II is carried out, the reaction lasts for 8 hours, and crude SiF is obtained4；
Si+F2→SiF4Ⅱ。
Fourthly, the crude product SiF prepared in the third step4Enters a discharge pipeline 6, sequentially passes through a dust remover 7 and a filter 8, enters a cooling kettle 19, and is subjected to SiF4Condensing to form solid and sinking to the bottom of a cooling kettle 19, floating residual gas light component impurities such as nitrogen, fluorine and the like to a cooling column 22, opening a cooling vacuum valve 26 when the pressure of a low-temperature storage tank pressure gauge 27 is greater than the pressure of a reaction tower pressure gauge 10, vacuumizing the low-temperature storage tank to 1KPa from the upper part of the cooling column 22 through a vacuum pipeline 4, and removing the light component impurities to obtain high-purity SiF4。
For the prepared high-purity SiF4The purity of (b) was determined as follows:
crude SiF is turned off4 Feed valve 9, mixed gas feed valve 15, and cooling vacuum valve 26; the liquid nitrogen is introduced into the cooling kettle 19 and the temperature is slowly and naturally raised to-90 ℃ by adjusting the introduction amount of the liquid nitrogen, and the SiF4Vaporizing, opening the analysis valve 29, SiF4Helium ionized gas chromatography is introduced into an analytical instrument through an analytical pipeline 28 for detection, and the high-purity SiF is detected4The purity was 99.999%. In the process of adjusting the liquid nitrogen input amount to heat the cooling kettle 19, if the pressure of the cooling kettle 19 is too high, the safety relief valve 31 is opened, the gas is released through the vent pipeline 30, and the pressure is reduced.
When the device works, the temperature in the reaction process is detected through thermometers arranged on the tower body of the reaction tower 1 and the top of the cooling kettle 19.
Example 3
A preparation method of silicon tetrafluoride, which is carried out by adopting a preparation device of silicon tetrafluoride shown in figure 1, and comprises the following steps:
crushing rocks and gravels mainly comprising silicate and silicon dioxide in nature into particles with the particle size of 15mm, performing thermal decomposition at 400 ℃, washing with 15% dilute hydrochloric acid, and washing with ultrapure water with the resistivity of 18M omega & CM to obtain pure SiO2And (3) granules.
Washing the SiO2Placing the particles as a silicon source 3 on a layered plate 2 in a reaction tower 1, starting the device, firstly opening a vacuum valve 5 of the reaction tower, vacuumizing for 12h from the top of the reaction tower 1 through a vacuum pipeline 4, heating the layered plate 2 to 300 ℃ by using a heating device, removing moisture in the silicon source 3, and obtaining dry SiO2。
Secondly, opening a hydrogen feeding valve 12, introducing hydrogen with the volume fraction of 99.9 percent into the reaction tower 1 through a hydrogen pipeline 11, heating the laminated plate 2 to 300 ℃ to generate a reaction shown as the formula I, reacting for 8 hours, and reacting SiO2Reducing the silicon into a simple substance Si, closing the hydrogen feeding valve 12 and stopping feeding hydrogen;
H2+SiO2→Si+H2OΙ。
thirdly, the reaction tower 1 is continuously heated and vacuumized, the temperature of the heating laminated plate 2 is up to 300 ℃, the vacuumizing time is 8 hours, and residual reducing H in the reaction tower 1 is removed2And H2O, a tail gas outlet is arranged on the vacuum pipeline 4 for combustible gas detection, and when the concentration of the combustible gas is detected to be 0ppm, the vacuum valve 5 of the reaction tower is closed;
opening a cooling kettle liquid nitrogen cooling valve 21 and a cooling column liquid nitrogen cooling valve 24, and injecting liquid nitrogen into a cooling kettle liquid nitrogen jacket 20 and a cooling column liquid nitrogen jacket 23 through a cooling pipeline 25 to reduce the temperature, so that the temperature of the cooling kettle 19 is-130 ℃ and the temperature of a cooling column 22 is-70 ℃;
opening a mixed gas feed valve 15, introducing a fluorine gas and nitrogen gas mixed gas into the reaction tower 1 through a mixed gas pipeline 14, wherein the volume fraction of the fluorine gas in the mixed gas is 30%, and adding the crude SiF4The feed valve 9 is opened, the temperature of the laminated plate 2 is heated to 150 ℃ in the reaction tower 1, the reaction shown as II is carried out, the reaction is carried out for 5 hours, and crude SiF is obtained4；
Si+F2→SiF4Ⅱ。
Fourthly, the crude product SiF prepared in the third step4Enters a discharge pipeline 6, sequentially passes through a dust remover 7 and a filter 8, enters a cooling kettle 19, and is subjected to SiF4Condensing to form solid and sinking to the bottom of a cooling kettle 19, floating residual gas light component impurities such as nitrogen, fluorine and the like to a cooling column 22, opening a cooling vacuum valve 26 when the pressure of a low-temperature storage tank pressure gauge 27 is greater than the pressure of a reaction tower pressure gauge 10, vacuumizing the low-temperature storage tank to 1KPa from the upper part of the cooling column 22 through a vacuum pipeline 4, and removing the light component impurities to obtain high-purity SiF4。
For the prepared high-purity SiF4The purity of (b) was determined as follows:
crude SiF is turned off4 Feed valve 9, mixed gas feed valve 15, and cooling vacuum valve 26; the liquid nitrogen is introduced into the cooling kettle 19 and the temperature is slowly and naturally raised to-85 ℃ by adjusting the introduction amount of the liquid nitrogen, and the SiF4Vaporizing, opening the analysis valve 29, SiF4Helium ionized gas chromatography is introduced into an analytical instrument through an analytical pipeline 28 for detection, and the high-purity SiF is detected4The purity was 99.999%. In the fluidIn the process of heating the cooling kettle 19 by adjusting the nitrogen introduction amount, if the pressure of the cooling kettle 19 is too high, the safety relief valve 31 is opened, gas is released through the vent pipeline 30, and the pressure is reduced.
When the device works, the temperature in the reaction process is detected through thermometers arranged on the tower body of the reaction tower 1 and the top of the cooling kettle 19.
The present invention includes, but is not limited to, the above embodiments, and any equivalent substitutions or partial modifications made under the principle of the spirit of the present invention are considered to be within the scope of the present invention.
Claims (10)
1. A preparation method of silicon tetrafluoride is characterized by comprising the following steps: the method comprises the following steps:
firstly, SiO2The particles are taken as a silicon source and are layered on a layered plate in a reaction tower, the tower top is vacuumized, and the temperature of the layered plate is heated to 200-400 ℃;
secondly, introducing 99.9 percent hydrogen by volume into the reaction tower, reacting for 5-10 h at 200-400 ℃ as shown in the formula I,
H2+SiO2→Si+H2O Ι；
thirdly, continuously heating the reaction tower and vacuumizing, wherein the heating temperature is 200-400 ℃, and the vacuumizing time is 5-10 hours; then introducing mixed gas of fluorine gas and nitrogen gas, reacting for 3-8 h at 100-200 ℃ as shown in the specification to obtain crude SiF4，
Si+F2→SiF4 Ⅱ；
Fourthly, the crude product SiF4The liquid nitrogen is collected to a low-temperature storage tank through a discharge pipeline of the reaction tower, the low-temperature storage tank is composed of a cooling kettle and a cooling column connected above the cooling kettle, and liquid nitrogen jackets are arranged on the outer sides of the cooling kettle and the cooling column; the temperature of the cooling kettle is-90 ℃ to-150 ℃, the temperature of the cooling column is-50 ℃ to-90 ℃, and then the high-purity silicon tetrafluoride is obtained by vacuumizing from the upper part of the low-temperature storage tank to 1KPa to 2 KPa.
2. The method for preparing silicon tetrafluoride according to claim 1The method is characterized in that: the SiO2The particle size of the particles is 5 mm-20 mm.
3. The method according to claim 1, wherein the silicon tetrafluoride comprises: in the step I, the tower top is vacuumized for 10 to 15 hours.
4. The method according to claim 1, wherein the silicon tetrafluoride comprises: the volume fraction of fluorine gas in the mixed gas of fluorine gas and nitrogen gas is 20-40%.
5. The method according to claim 1, wherein the silicon tetrafluoride comprises: the temperature of the cooling kettle is-110 ℃ to-150 ℃, and the temperature of the cooling column is-60 ℃ to-80 ℃.
6. The method according to claim 1, wherein the silicon tetrafluoride comprises: the SiO2The particle size of the particles is 5 mm-20 mm;
firstly, vacuumizing the tower top for 10-15 hours;
the volume fraction of the fluorine gas in the mixed gas of the fluorine gas and the nitrogen gas is 20 to 40 percent;
the temperature of the cooling kettle is-110 ℃ to-150 ℃, and the temperature of the cooling column is-60 ℃ to-80 ℃.
7. A silicon tetrafluoride production apparatus used in the silicon tetrafluoride production method according to any one of claims 1 to 6, wherein: the device mainly comprises the following components: reaction tower (1), layered plate (2), vacuum pipeline (4), reaction tower vacuum valve (5), discharge pipeline (6), dust remover (7), filter (8), crude SiF4The device comprises a feed valve (9), a reaction tower pressure gauge (10), a hydrogen pipeline (11), a hydrogen feed valve (12), a hydrogen one-way valve (13), a mixed gas pipeline (14), a mixed gas feed valve (15), a mixed gas one-way valve (16), a drain pipeline (17), a drain valve (18), a cooling kettle (19), a cooling kettle liquid nitrogen jacket (20), a cooling kettle liquid nitrogen cooling valve (21), a cooling column (22), and a cooling column liquidThe device comprises a nitrogen jacket (23), a cooling column liquid nitrogen cooling valve (24), a cooling pipeline (25), a cooling vacuum valve (26), a low-temperature storage tank pressure gauge (27), an analysis pipeline (28), an analysis valve (29), an emptying pipeline (30), a safety relief valve (31) and a thermometer;
the device comprises the following components in specific connection position relationship:
a plurality of layered plates (2) are arranged in the reaction tower (1), and pore canals are arranged on the layered plates (2), and are smaller than SiO (silicon dioxide) source (3)2The grain diameter of the particles, and a heating device is arranged on the layered plate (2);
the top of the reaction tower (1) is connected with an external vacuum-pumping device through a vacuum pipeline (4), and a reaction tower vacuum valve (5) is arranged on the vacuum pipeline (4); the top of the reaction tower (1) is connected with the top of the cooling kettle (19) through a discharge pipeline (6), and a dust remover (7), a filter (8) and a crude product SiF are sequentially arranged on the discharge pipeline (6) from the reaction tower (1) to the cooling kettle (19)4A feed valve (9); the top of the reaction tower (1) is also provided with a reaction tower pressure gauge (10);
the lower part of the tower body of the reaction tower (1) is connected with hydrogen through a hydrogen pipeline (11), a hydrogen feeding valve (12) is arranged on the hydrogen pipeline (11) and close to the reaction tower (1), and a hydrogen one-way valve (13) is arranged on the outer side of the hydrogen feeding valve (12); the lower part of the tower body of the reaction tower (1) is connected with the mixed gas of fluorine gas and nitrogen gas through a mixed gas pipeline (14), a mixed gas feeding valve (15) is arranged on the mixed gas pipeline (14) and close to the reaction tower (1), and a mixed gas one-way valve (16) is arranged on the outer side of the mixed gas feeding valve (15);
the bottom of the reaction tower (1) is connected with a drain pipeline (17), and a drain valve (18) is arranged on the drain pipeline (17);
the low-temperature storage tank is composed of a cooling kettle (19) and a cooling column (22) connected above the cooling kettle (19), a cooling kettle liquid nitrogen jacket (20) is arranged on the outer side of the cooling kettle (19), and the cooling kettle liquid nitrogen jacket (20) is connected with a cooling pipeline (25) through a pipeline provided with a cooling kettle liquid nitrogen cooling valve (21); a cooling column liquid nitrogen jacket (23) is arranged on the outer side of the cooling column (22), the cooling column liquid nitrogen jacket (23) is connected with a cooling pipeline (25) through a pipeline provided with a cooling column liquid nitrogen cooling valve (24), and the cooling pipeline (25) is connected with liquid nitrogen; the upper part of the cooling column (22) is connected to the vacuum pipeline (4) through a pipeline provided with a cooling vacuum valve (26); the top of the cooling column (22) is provided with a low-temperature storage tank pressure gauge (27);
the top of the cooling kettle (19) is connected with an analysis detection device through an analysis pipeline (28), and an analysis valve (29) is arranged on the analysis pipeline (28);
the top of the cooling kettle (19) is connected with an emptying pipeline (30), and a safety relief valve (31) is arranged on the emptying pipeline (30);
thermometers are respectively arranged on the tower body of the reaction tower (1) and the top of the cooling kettle (19).
8. The apparatus according to claim 7, wherein: a platinum resistor T1(32) is arranged at the upper part of the tower body to be used as a thermometer, a platinum resistor T2(33) is arranged at the lower part of the tower body to be used as a thermometer, and a platinum resistor T3(34) is arranged at the top part of the cooling kettle (19) to be used as a thermometer.
9. The apparatus according to claim 7, wherein: the analysis and detection device is helium ionization gas chromatography;
the reaction tower (1) and the layered plate (2) are made of stainless steel doped with chromium or molybdenum;
the top of the reaction tower (1) is sealed by a flange;
the cooling kettle (19) and the cooling column (22) are made of stainless steel;
the pipeline adopts an EP-grade stainless steel pipe;
vacuum valve (5) of reaction tower and crude SiF4The feed valve (9), the hydrogen feed valve (12), the mixed gas feed valve (15), the drain valve (18), the cooling vacuum valve (26) and the safety relief valve (31) adopt sealed stop valves; a liquid nitrogen cooling valve (21) of the cooling kettle and a liquid nitrogen cooling valve (24) of the cooling column adopt low-temperature stop valves; the analysis valve (29) is a sealing diaphragm valve.
10. The apparatus according to claim 7, wherein: a platinum resistor T1(32) is arranged at the upper part of the tower body to be used as a thermometer, a platinum resistor T2(33) is arranged at the lower part of the tower body to be used as a thermometer, and a platinum resistor T3(34) is arranged at the top of the cooling kettle (19) to be used as a thermometer;
the analysis and detection device is helium ionization gas chromatography;
the reaction tower (1) and the layered plate (2) are made of stainless steel doped with chromium or molybdenum;
the top of the reaction tower (1) is sealed by a flange;
the cooling kettle (19) and the cooling column (22) are made of stainless steel;
the pipeline adopts an EP-grade stainless steel pipe;
vacuum valve (5) of reaction tower and crude SiF4The feed valve (9), the hydrogen feed valve (12), the mixed gas feed valve (15), the drain valve (18), the cooling vacuum valve (26) and the safety relief valve (31) adopt sealed stop valves; a liquid nitrogen cooling valve (21) of the cooling kettle and a liquid nitrogen cooling valve (24) of the cooling column adopt low-temperature stop valves; the analysis valve (29) is a sealing diaphragm valve.
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| US20100061911A1 (en) * | 2008-08-04 | 2010-03-11 | Hariharan Alleppey V | METHOD TO CONVERT SILICON POWDER TO HIGH PURITY POLYSILICON THROUGH INTERMEDIATE SiF4 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US20100061911A1 (en) * | 2008-08-04 | 2010-03-11 | Hariharan Alleppey V | METHOD TO CONVERT SILICON POWDER TO HIGH PURITY POLYSILICON THROUGH INTERMEDIATE SiF4 |
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| 李勇辉等: "以二氧化硅为硅源制备纯硅的方法", 《化工生产与技术》 * |
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Address after: 057550 No. five Weir Road, chemical industry gathering area, Feixiang District, Handan, Hebei, 1 Applicant after: China shipbuilding (Handan) Perry Special Gas Co.,Ltd. Address before: No.1 Weiwu Road, chemical industry gathering area, Feixiang County, Handan City, Hebei Province Applicant before: PERIC SPECIAL GASES Co.,Ltd. |
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Application publication date: 20210730 |