CN103936009B - A kind of thermal decomposition of silane produces the device and method of nano level high-purity silicon powder - Google Patents

Abstract

The invention discloses a device and a method for producing nano-level high-purity silicon powder by thermally decomposing silane. Including silane thermal decomposition system, silica powder filtration and collection system and tail gas recovery treatment system, the silane decomposition system includes reaction gas silane pipeline, reaction gas hydrogen pipeline, proportioning buffer tank, silane tubular reactor, tail gas cooler, silicon Powder filtration and collection system includes hydrogen blowback filter pipeline, primary silicon powder filter, secondary silicon powder filter, primary silicon powder collection chamber, secondary silicon powder collection chamber, vacuum pump, primary silicon powder outlet pipeline, secondary silicon powder Grade silicon powder outlet pipeline, tail gas recovery treatment system includes tail gas cryocooler, compressor, adsorption tower, gas-liquid separation tank, gas-liquid separation tank liquid silane outlet pipeline, gas-liquid separation tank hydrogen outlet pipeline. The invention is suitable for the production of industrial nano-level high-purity silicon powder, can effectively collect silicon powder with a particle diameter of more than 30nm, recycle and use all tail gas, and has no pollution discharge, and has the advantages of less investment and low cost.

Description

A device and method for producing nano-scale high-purity silicon powder by thermal decomposition of silane

technical field

The invention relates to a device and a method for producing nano-level high-purity silicon powder by thermally decomposing silane.

Background technique

Nano-silica fume is a brownish-yellow powder with a wide range of uses. It can be used as a negative electrode material for rechargeable lithium batteries to increase the capacity of lithium batteries and the number of charge and discharge cycles. potential application prospects.

At present, the commonly used nano-silicon powder production processes include electrostatic spray assisted chemical deposition (ES-CVD), hot wire chemical vapor deposition (HWCVD), laser-induced chemical vapor deposition (LICVD), etc., but these methods require high equipment and consume a lot of energy. , and it is difficult to realize industrial production.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the existing nano-scale high-purity silicon powder production process, such as high cost, high energy consumption, and industrialization, and provide a device for producing nano-scale high-purity silicon powder by thermal decomposition of silane with simple equipment and safe operation. The method can realize closed-cycle continuous production with low cost and high productivity.

A device for producing nano-scale high-purity silicon powder by thermal decomposition of silane includes a silane thermal decomposition system, a silicon powder filtration and collection system, and an exhaust gas recovery and treatment system. The silane decomposition system includes a reaction gas silane pipeline, a reaction gas hydrogen pipeline, and a ratio Buffer tank, silane tubular reactor, tail gas cooler, reaction gas silane pipeline, reaction gas hydrogen pipeline are connected to the proportioning buffer tank, proportioning buffer tank, silane tubular reactor, tail gas cooler are connected in sequence, and silicon powder is filtered The collection system includes hydrogen blowback filter pipeline, primary silicon powder filter, secondary silicon powder filter, primary silicon powder collection bin, secondary silicon powder collection bin, vacuum pump, primary silicon powder outlet pipeline, secondary silicon powder The powder outlet pipeline, one end of the hydrogen backflush filter pipeline is connected to the reaction gas hydrogen pipeline, the other end of the hydrogen backflush filter pipeline is connected to the first-level silicon powder filter and the second-level silicon powder filter respectively, the tail gas cooler, the first-level silicon The powder filter and the secondary silicon powder filter are connected in sequence, the primary silicon powder filter, the primary silicon powder collection bin, and the primary silicon powder outlet pipeline are connected in sequence, the secondary silicon powder filter, and the secondary silicon powder collection The first-level silicon powder collection bin and the second-level silicon powder collection bin are connected to the vacuum pump respectively. The exhaust gas recovery and treatment system includes an exhaust gas cryocooler, a compressor, an adsorption tower, and a gas-liquid separation tank. , gas-liquid separation tank liquid silane outlet pipeline, gas-liquid separation tank hydrogen gas outlet pipeline, secondary silicon powder filter, tail gas deep cooler, compressor, adsorption tower, gas-liquid separation tank, gas-liquid separation tank liquid silane outlet pipeline The gas-liquid separation tank is connected to the proportioning buffer tank through the hydrogen outlet pipeline of the gas-liquid separation tank.

The method for producing nano-scale high-purity silicon powder by thermal decomposition of the device comprises the following steps:

1) High-purity silane and high-purity hydrogen enter the proportioning buffer tank for mixing and proportioning to obtain a mixed gas;

2) The mixed gas enters the silane tubular reactor. In the silane tubular reactor, the silane is heated and decomposed into granular silicon powder and hydrogen gas, and the gas-powder mixed gas is obtained at the outlet of the silane tubular reactor;

3) After the reacted gas-powder mixture is cooled by the tail gas cooler, the temperature drops below 100°C, and enters the primary silicon powder filter, where the silicon powder is filtered out and collected at the bottom of the primary silicon powder filter;

4) The silicon powder adsorbed on the outside of the filter membrane is backflushed with high-purity hydrogen provided by the hydrogen backflush filter pipeline;

5) When the first-level silicon powder filter reaches the specified amount of silicon powder, close the first-level silicon powder filter, open the second-level silicon powder filter, and let the gas-powder mixture cooled by the exhaust gas cooler enter the second-level silicon powder filter The device continues to be produced;

6) Replace the first-level silicon powder filter: use a vacuum pump to vacuumize the first-level silicon powder collection silo, connect the first-level silicon powder filter and the first-level silicon powder collection silo, and put the silicon powder into the first-level silicon powder collection silos,

7) When the secondary silicon powder filter reaches the specified amount of silicon powder, enable the replaced primary silicon powder filter, and replace the secondary silicon powder filter to realize the primary silicon powder filter and the secondary silicon powder filter. The silicon powder filter is switched and used to make the reaction continuous; the replacement operation of the secondary silicon powder filter is to use a vacuum pump to vacuumize the secondary silicon powder filter, and connect the secondary silicon powder filter with the secondary silicon powder filter. Put the silicon powder into the secondary silicon powder collection silo;

8) The tail gas filtered by the first-level silicon powder filter or the second-level silicon powder filter enters the tail gas recovery and treatment system, and after being cooled by the tail gas cryocooler, compressed by the compressor, and adsorbed by the adsorption tower, the silane and Hydrogen separation, the separated hydrogen is fed into the proportioning buffer tank through the hydrogen outlet pipeline of the gas-liquid separation tank, and the separated silane is purified.

The purity of the high-purity silane and high-purity hydrogen is greater than 99.9999%.

The molar concentration of silane in the mixed gas is 5%-20%, the pressure of the mixed gas is maintained at 0.3Mpa, and the flow rate of silane and hydrogen into the reactor is controlled at 80-100kg/h.

The thermal decomposition temperature of the silane is controlled at 500°C to 900°C. Further, the thermal decomposition temperature of the silane is controlled at 500°C to 600°C.

The silane tubular reactor is provided with a constant temperature heating zone, which can keep the heating temperature constant at 0-1200°C.

The tail gas cooler is cooled by circulating cooling water, which can reduce the temperature of the reacted gas-powder mixture to below 100°C.

The hydrogen blowback filter pipeline goes deep into the center of the first-level silicon powder filter and the second-level silicon powder filter, and the silicon powder adsorbed outside the filter is reversely purged.

The tail gas recovery and treatment system adopts cryogenic liquid cooling to separate silane and hydrogen, and the cryogenic liquid is liquid nitrogen.

The invention is suitable for the production of industrial nano-level high-purity silicon powder, all tail gas is recycled and utilized, no pollution is discharged, and the invention has the advantages of less investment, low cost and the like.

Description of drawings

Fig. 1 is the structural representation of the device for producing nano-scale high-purity silicon powder by thermal decomposition of silane;

Figure 2 is a SEM photo of silicon powder produced at a reaction temperature of 880°C;

Fig. 3 is the SEM photo of the silicon powder produced at a reaction temperature of 500°C;

Fig. 4 is the SEM photograph of the silicon powder that reaction temperature produces at 750 ℃;

Figure 5 is a SEM photo of silicon powder produced at a reaction temperature of 600°C;

In the figure, reaction gas silane pipeline 1, reaction gas hydrogen pipeline 2, proportioning buffer tank 3, silane tubular reactor 4, tail gas cooler 5, hydrogen blowback filter pipeline 6, primary silicon powder filter 7, two Grade 1 silicon powder filter 8, Grade 1 silicon powder collection bin 9, Grade 2 silicon powder collection bin 10, Vacuum pump 11, Grade 1 silicon powder outlet pipeline 12, Grade 2 silicon powder outlet pipeline 13, Exhaust gas deep cooler 14, Compressor 15. Adsorption tower 16, gas-liquid separation tank 17, gas-liquid separation tank liquid silane outlet pipeline 18, gas-liquid separation tank hydrogen gas outlet pipeline 19.

detailed description

As shown in Figure 1, a device for producing nano-scale high-purity silicon powder by silane thermal decomposition includes a silane thermal decomposition system, a silicon powder filtration and collection system, and an exhaust gas recovery treatment system. The silane decomposition system includes a reaction gas silane pipeline 1, Reaction gas hydrogen pipeline 2, proportioning buffer tank 3, silane tubular reactor 4, tail gas cooler 5, reaction gas silane pipeline 1, reaction gas hydrogen pipeline 2 are connected with proportioning buffer tank 3, proportioning buffer tank 3, silane Tubular reactor 4 and tail gas cooler 5 are connected in sequence, and the silicon powder filtration and collection system includes hydrogen backflush filter pipeline 6, primary silicon powder filter 7, secondary silicon powder filter 8, and primary silicon powder collection bin 9. Secondary silicon powder collection bin 10, vacuum pump 11, primary silicon powder outlet pipeline 12, secondary silicon powder outlet pipeline 13, one end of hydrogen backflush filter pipeline 6 is connected to reaction gas hydrogen pipeline 2, hydrogen backflush filter The other end of the pipeline 6 is connected to the primary silicon powder filter 7 and the secondary silicon powder filter 8 respectively, the exhaust gas cooler 5, the primary silicon powder filter 7 and the secondary silicon powder filter 8 are connected in sequence, and the primary silicon powder filter The powder filter 7, the first-level silicon powder collection bin 9, and the first-level silicon powder outlet pipeline 12 are connected in sequence, and the second-level silicon powder filter 8, the second-level silicon powder collection bin 10, and the second-level silicon powder outlet pipeline 13 are connected in sequence , the first-level silicon powder collection bin 9 and the second-level silicon powder collection bin 10 are respectively connected to the vacuum pump 11, and the exhaust gas recovery treatment system includes an exhaust gas deep cooler 14, a compressor 15, an adsorption tower 16, a gas-liquid separation tank 17, and a gas-liquid separation Tank liquid silane outlet pipeline 18, gas-liquid separation tank hydrogen outlet pipeline 19, secondary silicon powder filter 8, tail gas deep cooler 14, compressor 15, adsorption tower 16, gas-liquid separation tank 17, gas-liquid separation tank liquid silane The outlet pipeline 18 is connected in sequence, and the gas-liquid separation tank 17 is connected with the proportioning buffer tank 3 through the hydrogen gas outlet pipeline 19 of the gas-liquid separation tank.

The silane tubular reactor 4 has a constant temperature heating zone, which can keep the heating temperature constant at any temperature between 0 and 1200°C.

The tail gas cooler 5 is cooled by circulating cooling water, which can reduce the temperature of the reacted gas-powder mixture to below 100°C.

The hydrogen blowback filter pipeline 6 goes deep into the center of the first-level silicon powder filter 7 and the second-level silicon powder filter 8, and reversely purges the silicon powder adsorbed outside the filter.

The tail gas recovery and treatment system adopts cryogenic liquid cooling to separate silane and hydrogen, and the cryogenic liquid is liquid nitrogen.

The silicon powder stored in the first-level silicon powder collection bin 9 and the second-level silicon powder collection bin 10 can be discharged from the first-level silicon powder outlet pipeline 12 and the second-level silicon powder outlet pipeline 13 respectively.

Implementation example 1:

Mix 500kg of high-purity silane with a purity of 6N and high-purity hydrogen with a molar concentration of 20% uniformly, and enter the silane tube at 880°C with a pressure of 0.30Mpa according to the total amount of 100kg/h after mixing. The reactor is heated and decomposed, and the generated particulate silicon powder and unreacted tail gas enter the silicon powder filter after cooling. After filtration, the tail gas enters the tail gas recovery treatment system. After cooling, compression and adsorption, the silane and hydrogen are separated. , the separated hydrogen is added to the proportioning buffer tank, and the separated silane is returned to the silane purification tower for purification for reuse. After the produced silicon powder is collected by the first-level silicon powder collection bin and the second-level silicon powder collection bin, 314kg of silicon powder with a thickness of 150nm to 350nm is obtained, and the primary conversion rate of silane is 71.78%. The obtained SEM photo is shown in Figure 2.

Implementation example 2:

Mix 500kg of high-purity silane with a purity of 6N and high-purity hydrogen with a molar concentration of 5% uniformly, and enter the silane tube at 500°C with a pressure of 0.30Mpa according to the total amount of 80kg/h after mixing. The reactor is heated and decomposed, and the generated particulate silicon powder and unreacted tail gas enter the silicon powder filter after cooling. After filtration, the tail gas enters the tail gas recovery treatment system. After cooling, compression and adsorption, the silane and hydrogen are separated. , the separated hydrogen is added to the proportioning buffer tank, and the separated silane is returned to the silane purification tower for purification for reuse. After the silicon powder produced is collected by the first-level silicon powder collection bin and the second-level silicon powder collection bin, 178kg of silicon powder with a thickness of 30nm to 90nm is obtained, and the primary conversion rate of silane is 40.69%. The obtained SEM photo is shown in Figure 3.

Implementation example 3:

Mix 500kg of high-purity silane with a purity of 6N and high-purity hydrogen with a molar concentration of 15% uniformly, and enter the silane tube at 750°C with a pressure of 0.30Mpa according to the total amount of 80kg/h after mixing. The reactor is heated and decomposed, and the generated particulate silicon powder and unreacted tail gas enter the silicon powder filter after cooling. After filtration, the tail gas enters the tail gas recovery treatment system. After cooling, compression and adsorption, the silane and hydrogen are separated. , the separated hydrogen is added to the proportioning buffer tank, and the separated silane is returned to the silane purification tower for purification for reuse. After the produced silicon powder is collected by the first-level silicon powder collection bin and the second-level silicon powder collection bin, 262kg of silicon powder with a thickness of 50nm to 250nm is obtained, and the primary conversion rate of silane is 59.89%. The obtained SEM photo is shown in Figure 4.

Implementation example 4:

Mix 500kg of high-purity silane with a purity of 6N and high-purity hydrogen with a molar concentration of 10% uniformly, and enter the silane tube at 600°C with a pressure of 0.30Mpa according to the total amount of 90kg/h after mixing. The reactor is heated and decomposed, and the generated particulate silicon powder and unreacted tail gas enter the silicon powder filter after cooling. After filtration, the tail gas enters the tail gas recovery treatment system. After cooling, compression and adsorption, the silane and hydrogen are separated. , the separated hydrogen is added to the proportioning buffer tank, and the separated silane is returned to the silane purification tower for purification for reuse. After the produced silicon powder is collected by the first-level silicon powder collection bin and the second-level silicon powder collection bin, 231kg of silicon powder with a thickness of 30nm to 120nm is obtained, and the primary conversion rate of silane is 52.80%. The obtained SEM photo is shown in Figure 5.

Claims (9)

1. a method for nano level high-purity silicon powder is produced in device for carrying out said thermolysis, it is characterized in that comprising the steps:

1) high purity silane and high-purity hydrogen enter proportioning surge tank (3) and carry out mixing match, obtain gas mixture;

2) gas mixture enters silane tubular reactor (4), and in silane tubular reactor (4), silane thermal degradation granulates silica flour and hydrogen, and the outlet of silane tubular reactor (4) obtains gas powder gas mixture;

3) reacted gas powder gas mixture is after exhaust gas cooler (5) cooling, and temperature is down to less than 100 DEG C, enters one-level silica flour strainer (7), is leached by silica flour, is collected in one-level silica flour strainer (7) bottom;

4) high-purity hydrogen that the silica flour being adsorbed on filter membrane outside uses hydrogen power back-blowing filter pipeline (6) to provide carries out reverse blowing disposal;

5) after one-level silica flour strainer (7) reaches the silica flour of specified quantity, close one-level silica flour strainer (7), open secondary silica flour strainer (8), allow exhaust gas cooler (5) cooled gas powder gas mixture enter secondary silica flour strainer (8) and continue to produce;

6) one-level silica flour strainer (7) is replaced: with vacuum pump (11), feed bin (9) is collected to one-level silica flour and vacuumize process, be communicated with one-level silica flour strainer (7) and collect feed bin (9) with one-level silica flour, silica flour is put into one-level silica flour and collect feed bin (9);

7) after secondary silica flour strainer (8) reaches the silica flour of specified quantity, enable the one-level silica flour strainer (7) after displacement, and replacement operator is carried out to secondary silica flour strainer (8), realize one-level silica flour strainer (7) and secondary silica flour strainer (8) switching use, make reaction have continuity; Described carries out replacement operator for vacuumize process with vacuum pump (11) to secondary silica flour strainer (8) to secondary silica flour strainer (8), be communicated with secondary silica flour strainer (8) and collect feed bin (10) with secondary silica flour, silica flour is put into secondary silica flour and collect feed bin (10);

8) tail gas after one-level silica flour strainer (7) or secondary silica flour strainer (8) filter enters tail gas recycle treatment system, after tail gas cryogenic device (14) cooling, compressor (15) compression, adsorption tower (16) absorption, at knockout drum (17) by silane and Hydrogen Separation, separating obtained hydrogen fills into proportioning surge tank (3) by knockout drum hydrogen outlet pipeline (19), and separating obtained silane is purified;

Described device comprises thermal decomposition of silane system, silica flour collecting by filtration system and tail gas recycle treatment system, described silane decomposes system comprises reaction gas silane pipeline (1), reaction gas hydrogen gas lines (2), proportioning surge tank (3), silane tubular reactor (4), exhaust gas cooler (5), reaction gas silane pipeline (1), reaction gas hydrogen gas lines (2) is connected with proportioning surge tank (3), proportioning surge tank (3), silane tubular reactor (4), exhaust gas cooler (5) is connected in turn, and silica flour collecting by filtration system comprises hydrogen power back-blowing filter pipeline (6), one-level silica flour strainer (7), secondary silica flour strainer (8), one-level silica flour collecting bin (9), secondary silica flour collecting bin (10), vacuum pump (11), one-level silica flour outlet line (12), secondary silica flour outlet line (13), hydrogen power back-blowing filter pipeline (6) one end is connected with reaction gas hydrogen gas lines (2), hydrogen power back-blowing filter pipeline (6) the other end respectively with one-level silica flour strainer (7), secondary silica flour strainer (8) is connected, exhaust gas cooler (5), one-level silica flour strainer (7), secondary silica flour strainer (8) is connected in turn, one-level silica flour strainer (7), one-level silica flour collecting bin (9), one-level silica flour outlet line (12) is connected in turn, secondary silica flour strainer (8), secondary silica flour collecting bin (10), secondary silica flour outlet line (13) is connected in turn, one-level silica flour collecting bin (9), secondary silica flour collecting bin (10) is connected with vacuum pump (11) respectively, and tail gas recycle treatment system comprises tail gas cryogenic device (14), compressor (15), adsorption tower (16), knockout drum (17), liquid silane outlet line (18) of knockout drum, knockout drum hydrogen outlet pipeline (19), secondary silica flour strainer (8), tail gas cryogenic device (14), compressor (15), adsorption tower (16), knockout drum (17), liquid silane outlet line (18) of knockout drum is connected in turn, and knockout drum (17) is connected with proportioning surge tank (3) by knockout drum hydrogen outlet pipeline (19).

2. the thermal decomposition of silane according to right 1 produces the method for nano level high-purity silicon powder, it is characterized in that the purity of described high purity silane and high-purity hydrogen is greater than 99.9999%.

3. the thermal decomposition of silane according to right 1 produces the method for nano level high-purity silicon powder, it is characterized in that the volumetric molar concentration of silane in described gas mixture is 5% ~ 20%, the pressure of gas mixture maintains 0.3Mpa, enters the flow control of reactor at 80-100kg/h after silane and hydrogen proportioning.

4. the thermal decomposition of silane according to right 1 produces the method for nano level high-purity silicon powder, it is characterized in that the thermal degradation temperature of described silane controls at 500 DEG C ~ 900 DEG C.

5. the thermal decomposition of silane according to right 1 produces the method for nano level high-purity silicon powder, it is characterized in that the thermal degradation temperature of described silane controls at 500 DEG C ~ 600 DEG C.

6. the thermal decomposition of silane according to right 1 produces the method for nano level high-purity silicon powder, it is characterized in that described silane tubular reactor (4) is provided with one section of constant temperature hot-zone, Heating temperature can be made constant in 0 ~ 1200 DEG C.

7. the thermal decomposition of silane according to right 1 produces the method for nano level high-purity silicon powder, it is characterized in that described exhaust gas cooler (5) uses circulating cooling water cooling, reacted gas powder mixture temperature can be made to be down to less than 100 DEG C.

8. the thermal decomposition of silane according to right 1 produces the method for nano level high-purity silicon powder, it is characterized in that described hydrogen power back-blowing filter pipeline (6) gos deep into one-level silica flour strainer (7) and secondary silica flour strainer (8) center, the silica flour that reverse blow strainer adsorbs outward.

9. the thermal decomposition of silane according to right 1 produces the method for nano level high-purity silicon powder, and it is characterized in that described tail gas recycle treatment system adopts cryogenic liquid refrigerated separation silane and hydrogen, described cryogenic liquid is liquid nitrogen.