Equipment and method for purifying boron trifluoride

Abstract

The invention relates to equipment for purifying boron trifluoride and a purification method. The purification equipment comprises a cold and hot all-in-one machine, an adsorption purifier, a recovery gas tank, a product gas tank and a regeneration recovery gas tank, according to the purification method, H2, N2, O2 + Ar, CH4, CO2, HF, SO2, SO3, SiF4 and other impurities in 99.9% boron trifluoride are efficiently removed by utilizing a temperature swing and pressure swing adsorption process, analysis and detection of the impurities are completed by combining gas chromatography assembled with a PDD detector and in-situ infrared spectroscopy of a 5m optical path pool, the content of key impurities CO2 and SiF4 can be respectively reduced to below 1ppm and below 2ppm by adopting the process, and preparation of 5N-grade or above high-purity boron trifluoride is realized. In addition, through regulation and control of technological parameters, the content of impurities SiF4 and CO2 can be further reduced, and the content of the impurities SiF4 and CO2 can be reduced to 0.5 ppm or below. The process is simple, low in energy consumption and environment-friendly. The equipment and the process have the advantage of easiness in large-scale production.

Description

TECHNICAL FIELD

[0001] The present application relates to a boron trifluoride production process and is applied to the field of semiconductors. BACKGROUND

[0002] Boron trifluoride is a key material in the field of semiconductors, which is mainly used for silicon and germanium epitaxy, diffusion and ion implantation process in this field, and is an important P-type doping source. The purity of boron trifluoride directly affects the performance of semiconductors.

[0003] 5N electronic grade high-purity boron trifluoride superior product strictly limits the content of impurities SiF4 and CO2. Domestic high-purity boron trifluoride manufacturers all use low-temperature rectification process to produce electronic grade boron trifluoride. Chinese patent CN106629758B discloses a method for purifying boron trifluoride gas by low-temperature rectification process, which refines the purity of 98% raw material to 99.9%~99.99% under the rectification operation condition of 3.0~4.0MPa. Patent document CN113819715A discloses a low-temperature rectification device and process for producing high-purity boron trifluoride, which purifies 99.5% boron trifluoride raw material to 99.999% by low-temperature rectification process, and SiF4 and CO2 can be reduced to 0.45ppm and 0.17ppm respectively. Patent documents CN117509658A and CN117446816A disclose adsorption and rectification process technology to prepare 99.999% electronic grade boron trifluoride. CN117509658A realizes the removal of CO2 by modified ZSM-5 molecular sieve, and the content of CO2 is reduced to 0.1ppm, but the content of SiF4 after rectification process is still 2.7ppm; CN117446816A discloses a production system and method of electronic grade boron trifluoride, which realizes the purity of 99.999% by adsorption and rectification technology, and the content of CO2 is reduced to 0.03ppm, and the content of SiF4 is reduced to 0.1ppm. In addition, patent document CN117550619A discloses a purification method of boron trifluoride, which adopts complexation-cleavage-separation process to purify boron trifluoride gas, and the purity can reach 99.9995% and above, and the abundance of boron trifluoride (11) can reach 99.9%, but the impurity distribution is not reported.

[0004] From the results of the above distillation, adsorption rectification and complexation-cracking-separation process, it can be seen that CO2 in the key impurities can be effectively removed by the adsorption process, and SiF4 cannot be better removed, and can only be removed by distillation. Because the boiling point of silicon tetrafluoride and boron trifluoride is close, sufficient column height is needed to ensure the distillation efficiency, so that the main component is separated from it. The significant increase in the height of the distillation column will result in a significant increase in energy consumption and a decrease in speed. The threshold of high-quality boron trifluoride is that the carbon dioxide content is less than 1 ppm and the silicon tetrafluoride content is less than 2 ppm, and the existing technology cannot meet this requirement. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a device and method for purifying boron trifluoride, which realizes effective deep removal of H2, N2, O2+Ar, CH4, HF, SO2, SO3, CO2 and SiF4 through the temperature swing adsorption process, and reduces the key impurities carbon dioxide to below 1 ppm and silicon tetrafluoride to below 2 ppm, and realizes the preparation of high-purity boron trifluoride with a purity of more than 99.999%.

[0006] To solve the above technical problems, the present application provides a device for purifying boron trifluoride, comprising a cold and hot all-in-one machine 3, an adsorption purifier 2, a recovery gas tank 14-1, a product gas tank 14-2 and a regeneration recovery gas tank 14-3; the cold and hot all-in-one machine 3 and the adsorption purifier 2 are connected to form a loop; the adsorption purifier 2 is provided with a temperature sensor 4 and a heating rod 5; the outermost shell layer of the adsorption purifier 2 is connected to a vacuum system; the bottom of the adsorption purifier 2 is connected to a vacuum system, a high-purity helium source, a high-purity nitrogen source and a raw material boron trifluoride through a first flow meter 1; the top of the adsorption purifier 2 is connected to a resistance gauge 6, a second flow meter 7, a vacuum system and a vent through a filter; the second flow meter 7 is divided into two paths, one of which is connected to the top of the recovery gas tank 14-1, the product gas tank 14-2 and the regeneration recovery gas tank 14-3, and the other of which is connected to an analysis instrument 9 through a pressure reducing valve 8; the analysis instrument 9 is provided with a high-purity helium gas and an analysis sample collector 10 placed in a cold trap 11; the recovery gas tank 14-1 is provided with a liquid level meter, a pressure sensor and an embedded coil pipe, the lower end of the coil pipe is connected to liquid nitrogen, the upper end of the coil pipe is vented, and the bottom of the tank is connected to a filling pump through a filter; the product gas tank 14-2 is provided with a liquid level meter, a pressure sensor and an embedded coil pipe, the lower end of the coil pipe is connected to liquid nitrogen, the upper end of the coil pipe is vented, and the bottom of the tank is connected to a filling pump through a filter; the regeneration recovery gas tank 14-3 is provided with a liquid level meter, a pressure sensor and an embedded coil pipe, the lower end of the coil pipe is connected to liquid nitrogen, the upper end of the coil pipe is vented, and the bottom of the tank is connected to a filling pump through a filter; the components are connected through pipes and valves.

[0007] In the above technical solution, the adsorption purifier has a jacket, the jacket flows heat medium and refrigerant to realize temperature regulation of the container interior, and the flowing heat medium needs to be subjected to evacuation treatment when the adsorption material is regenerated; the jacket has a vacuum heat insulation layer outside.

[0008] Further, the adsorption purifier 2 is provided with an adsorbent loading port and an adsorbent unloading port.

[0009] Further, the filter precision of the filter arranged at the top of the adsorption purifier is preferably 1 µm.

[0010] Further, the filter precision of the filters arranged at the bottoms of the recovery gas tank, the product gas tank, and the regeneration recovery gas tank is preferably 3 nm.

[0011] In the above technical solution, the range of the flow meter is preferably 0-100 L / min.

[0012] In the above technical solution, the diameter of the adsorption purifier is preferably 250 mm-1000 mm, the height is preferably 1000-20000 mm, the material is preferably 316 L, and the design pressure of the main body of the adsorption purifier is 4 MPa.

[0013] In the above technical solution, the power of the cold and hot all-in-one machine is preferably 30-200 KW, and the temperature control range is preferably -80-50 ℃.

[0014] In the above technical solution, the power of a single heating rod is preferably 1-10 kw, and preferably 3-8 rods, and the temperature of the adsorption bed in the adsorption purifier is controllable at 50-400 ℃.

[0015] In the above technical solution, the temperature monitoring range of the temperature sensor is preferably -180-450 ℃.

[0016] In the above technical solution, the gas chromatograph comprising a PDD detector and the infrared spectrum equipped with an optical path cell are included in the analysis instrument.

[0017] In the above technical solution, the diameters of the recovery gas tank, the product gas tank, and the regeneration recovery gas tank are preferably 300 mm-1000 mm, the heights are preferably 1000-5000 mm, and the material is preferably 316 L.

[0018] In the above technical solution, the filling amount of the filling pump is preferably 20-100 L / h, and the upper limit of the filling pressure is 16 MPa.

[0019] In the above technical solution, the evacuation speed of the vacuum system is preferably 20-100 m 3 / h, and the limit vacuum degree absolute pressure can reach 1*10 -5 Pa.

[0020] In the above technical solution, the adsorbent filled in the adsorption purifier is an activated carbon material, preferably a resin-based activated carbon or a pitch-based activated carbon. The activated carbon adsorbent can be spherical, columnar or prismatic, and the content of the adsorbent pore size distribution in the range of 1-2 nm is preferably 50%-80%, and the bulk density is preferably 0.4-0.8 g / cm 3 .

[0021] A method for purifying boron trifluoride, comprising the following steps: (1) The outermost shell layer of the adsorption purifier is evacuated to an absolute pressure of 1-10 Pa; (2) Turn on the heating rod and set the temperature program to 200°C for 3h, 300°C for 3h, 400°C for 3h, and finally to 450°C for 150h; (3) Adjust the flow rate of the first flowmeter to 5-50 L / min, and first activate the adsorbent with nitrogen at 300-450°C for 48-200h, preferably for 120-200h; (4) Adjust the flow rate of the first flowmeter to 5-50 L / min, and activate the adsorbent with helium for 10-30h; (5) Evacuate the adsorption purifier for 10-30h, turn off the heating rod, cool to room temperature, turn on the cold and hot all-in-one machine, and control the adsorption purifier at a temperature of -65 to -75°C; (6) Evacuate the recovery gas tank, product gas tank, and regeneration recovery gas tank for 0.1-3h, then fill high-purity helium, and repeat the evacuation-filling operation 10-30 times for standby; (7) Adjust the flow rate of the first flowmeter to 20-40 L / min; when the absolute pressure of the resistance gauge reaches 1*10 5 Pa, close the adsorption purifier vacuum valve and stabilize for 4h; when the absolute pressure of the resistance gauge decreases to 8.5*10 4 Pa, open the adsorption purifier vacuum valve, and continue until the absolute pressure of the adsorption purifier is not less than 9*10 4 Pa after closing the vacuum valve, and turn off the vacuum system; (8) Pre-cool the recovery gas tank with liquid nitrogen at a flow rate of 3-5 KG / h; (9) Adjust the temperature of the adsorption purifier to -60 to -40°C using the cold and hot all-in-one machine, open the recovery gas tank inlet pipeline, and adjust the flow rate of the second flowmeter to 1-10 L / min; discharge the weakly adsorbed components H2, N2, O2+Ar, etc. for a cumulative time of 10-100h, and take samples for analysis at intervals of 2-4h; (10) When the impurity contents of H2, N2, O2+Ar are lower than 1 ppm, 5 ppm, and 1 ppm respectively, liquid nitrogen is introduced into the coil in the product gas tank at a flow rate of 5~10 KG / h for pre-cooling; the air inlet valve of the recovery gas tank is closed, and the air inlet valve of the product gas tank is opened to extract the product. The second flow meter controls the extraction speed to 10~50L / min, the extraction temperature is -50~30℃, and the sampling and analysis interval is 2~4 hours; at the same time, the recovery gas filling pump is used to fill the material in the recovery gas tank into the gas cylinder with recovery gas. When there is no liquid phase in the recovery gas tank, the filling is stopped and the liquid nitrogen in the recovery gas tank is closed; (11) The impurity content requirements of the strongly adsorbed components CH4, CO2, HF, SO2, SO3, and SiF4 are 1 ppm, 1 ppm, 1 ppm, 1 ppm, 1 ppm, and 2 ppm, respectively. When the content of any impurity in the strongly adsorbed component impurities exceeds the index requirement, the production of products shall be stopped; (12) The product output pipeline was vacuumed and re-pressurized with high-purity helium, and the above operation was repeated 10 times; at the same time, liquid nitrogen was used to pre-cool the analytical sample collection tank for 10 minutes, and the analytical sample was collected for 2 minutes. The cold trap was removed, and when the total pressure of the pressure reducing valve was higher than 0.5 MPa, the partial pressure was adjusted to 0.2 MPa for product sample analysis; (13) Use the product filling pump to fill the material in the product gas tank into the gas cylinder. When there is no liquid phase in the product gas tank, stop filling and turn off the liquid nitrogen; (14) Adjust the flow rate of the second flow meter to 20 L / min, and the flow rate of the liquid nitrogen in the regeneration recovery tank to 5~10 KG / h. Desorb the residual raw materials in the adsorption purifier. Turn on the heating rod and stabilize it at 100℃ for 4h and then increase it to 250℃. When the flow rate reading of the second flow meter is lower than 1L / min, stop collecting the residual adsorbed gas; then use the regeneration recovery gas filling pump to fill the material in the regeneration recovery tank into the gas cylinder. Stop filling when there is no liquid phase in the regeneration recovery tank, and turn off the liquid nitrogen in the regeneration recovery tank.

[0022] In the above technical solution, the purity of nitrogen and helium used is greater than 5N, the purity of the raw material boron trifluoride is 99.9%, the nitrogen is transported through a liquid nitrogen tank, and the helium and boron trifluoride raw materials are transported through containers.

[0023] The activated carbon adsorbent used above is treated with 0.01~0.5 mol / L electronic grade HF aqueous solution at a solid-liquid mass ratio of 1:(5~20) at 30~80℃ for 3~24 hours, and then calcined at 400~500℃ for 10~50 hours under the protection of inert gas after drying; after acid washing and calcination, the adsorbent is loaded.

[0024] The adsorbent filled in the adsorption purifier is activated by nitrogen at 300-450 ℃ for 48-200 h, preferably for 120-200 h.

[0025] After the above nitrogen activation process is completed, helium is used for activation at 300-450 ℃ for 2-24 h, preferably for 15-24 h.

[0026] After the above helium activation is completed, the adsorption purifier is subjected to vacuum treatment using a vacuum system, at a temperature of 300-500 ℃ for 4-24 h, preferably for 15-24 h; the absolute pressure during the vacuum treatment is 0-2 Pa, preferably 0-1*10 -2 Pa.

[0027] In the above technical solution, the recovery gas tank, the product gas tank, the regeneration recovery gas tank, and the filling pipeline are subjected to helium purging and vacuum replacement, and the vacuum replacement is performed 5-20 times, preferably 15-20 times.

[0028] In the above helium replacement process, the single vacuum treatment time is 10 min-120 min.

[0029] In the above technical solution, the flow rate of the introduced boron trifluoride during the absorption process is 10-100 L / min, the outlet temperature of the refrigerant of the cold and hot all-in-one machine is -80--50 ℃, the temperature of the adsorption bed is -90--30 ℃, and the absolute pressure of the adsorption bed is kept at 8.5*10 4 ~1*10 5 Pa.

[0030] In the above technical solution, the outlet temperature of the refrigerant of the cold and hot all-in-one machine is -80--50 ℃ during the process of releasing BF3 from the adsorbent.

[0031] In the above technical solution, the temperature of the adsorption bed is -70--50 ℃.

[0032] In the above technical solution, the flow rate of the weakly adsorbed components H2, N2, O2+Ar, and other impurities discharged in step (9) is 1-10 L / min, preferably 2-5 L / min, and the release temperature is -60--40 ℃.

[0033] During the process of discharging the weakly adsorbed components H2, N2, O2+Ar, and other impurities, the H2, N2, O2+Ar, and other impurities can be removed in a continuous manner or an intermittent manner; in the intermittent manner, the control time of discharging the weakly adsorbed components H2, N2, O2+Ar, and other impurities is 10 min-30 min, the interval time is 30-120 min, and the discharge frequency is 10-50 times.

[0034] The discharged light components are collected by the recovery gas tank.

[0035] In the step (9) of the technical solution, the weakly adsorbed components H2, N2, O2+Ar and other impurities are collected by using a product collection tank after passing the gas chromatography analysis, the collection flow is 10-50 L / min, and the bed temperature is-50-30 DEG C.

[0036] During the product collection process, the impurity content changes of the strongly adsorbed components CH4, CO2, HF, SO2, SO3 and SiF4 are monitored by gas chromatography and infrared spectroscopy, and the sampling interval is 2-4 h.

[0037] In the technical solution, if the contents of the strongly adsorbed components CH4, CO2, HF, SO2, SO3 and SiF4 exceed the standard, the cold and hot integrated machine is closed, the heating rod is opened, and the residual concentrated boron trifluoride is collected by using a regeneration recovery tank, and the heating is stabilized at 200-300 DEG C.

[0038] In the technical solution, during the absorption process, the pressure of the recovery gas tank, the product gas tank and the regeneration recovery gas tank is maintained at-0.1--0.09 MPa, and the refrigerant liquid nitrogen is supplied at 5-10 KG / h.

[0039] The materials in the recovery gas tank, the product gas tank and the regeneration recovery gas tank are collected by using a filling pump, and the filling speed is 20-50 L / h.

[0040] The filling gas discharge is connected to 1-8 product collection steel cylinders, preferably 4-8 product collection steel cylinders, and the volume of the collection steel cylinder is 1-50 L.

[0041] The above-mentioned equipment and method are also applicable to high-purity 5N or above 10 BF3 is purified by 11 BF3 purification production process.

[0042] The equipment and method for purifying boron trifluoride provided by the application realize effective separation of different impurity molecules by using the adsorption material to bind the gas at different temperatures and pressures, the key impurity carbon dioxide is reduced to below 1 ppm, and the silicon tetrafluoride is reduced to below 2 ppm, the online analysis instrument is used to monitor the impurities such as weakly adsorbed components and strongly adsorbed components, the impurity content of high-purity electronic-grade boron trifluoride is accurately controlled, and the preparation of high-purity boron trifluoride with a purity greater than 99.999% is realized. The variable-temperature adsorption process can further control the contents of the impurities SiF4 and CO2 to be below 0.5 ppm by adjusting the process parameters. The process is simple, the energy consumption is low, and the environment is friendly. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 It is a boron trifluoride purification process flow diagram.

[0044] In the figure: 1. First flow meter; 2. Adsorption purifier; 3. Cooling and heating integrated machine; 4. Temperature sensor; 5. Heating rod; 6. Resistance gauge; 7. Second flow meter; 8. Pressure reducing valve; 9. Analytical instrument; 10. Analytical sample collector; 11. Cold trap; 12-1, 12-2, 12-3 are pressure sensors; 13-1, 13-2, 13-3 are liquid level gauges; 14-1. Recovery gas tank; 14-2. Product gas tank; 14-3. Regeneration recovery gas tank; 15-1, 15-2, 15-3, 15-4 is a filter; 16-1, 16-2, and 16-3 are charging pumps; 17-1, 17-2, and 17-3 are liquid nitrogen; 18-1, 18-2, 18-3, 18-4, and 18-5 are venting; F-1 is high-purity nitrogen; F-2 and F-4 are high-purity helium; F-3 is the raw material boron trifluoride; A-1 is the adsorbent filling port; D-1 is the adsorbent unloading port; V-1, V-2, V-3, and V-4 are the vacuum system; K1~K19 are valves. DETAILED DESCRIPTION

[0045] like Figure 1 As shown, a device for purifying boron trifluoride includes a cooling and heating integrated machine 3, an adsorption purifier 2, a recovery gas tank 14-1, a product gas tank 14-2 and a regeneration recovery gas tank 14-3; the cooling and heating integrated machine 3 is connected to the adsorption purifier 2 to form a loop; a temperature sensor 4 and a heating rod 5 are provided in the adsorption purifier; the outermost shell of the adsorption purifier 2 is connected to the vacuum system; the bottom of the adsorption purifier is connected to the vacuum system, a high-purity helium source, a high-purity nitrogen source, and the raw material boron trifluoride through a first flowmeter 1; the top of the adsorption purifier is connected through a filter The devices are respectively connected to the resistance gauge 6, the second flowmeter 7, the vacuum system, and the vent; the second flowmeter 7 is divided into two paths, one of which is connected to the recovery gas tank 14-1, the product gas tank 14-2, and the top of the regeneration recovery gas tank 14-3, and the other is connected to the analysis instrument 9 through the pressure reducing valve 8; the analysis instrument 9 is equipped with high-purity helium and an analysis sample collector 10 placed in a cold trap 11; the recovery gas tank 14-1 is equipped with a liquid level gauge, a pressure sensor, and a built-in coil. The lower end of the coil is connected to liquid nitrogen, the upper end of the coil is vented, and the bottom of the tank is connected to the filling pump through a filter; The product gas tank 14-2 is provided with a liquid level gauge, a pressure sensor, and a built-in coil. The lower end of the coil is connected to liquid nitrogen, the upper end of the coil is vented, and the bottom of the tank is connected to a filling pump through a filter; the regeneration recovery gas tank 14-3 is provided with a liquid level gauge, a pressure sensor, and a built-in coil. The lower end of the coil is connected to liquid nitrogen, the upper end of the coil is vented, and the bottom of the tank is connected to a filling pump through a filter; the various components are connected by pipes and valves; the adsorption purifier is provided with an adsorbent filling port and an adsorbent unloading port; the adsorption purifier has a jacket, and the flowing heat medium and refrigerant in the jacket realize the temperature regulation inside the container. The flowing heat and refrigerant need to be evacuated when the adsorption material is regenerated; there is a vacuum insulation layer on the outside of the jacket.

[0046] The filter at the top of the adsorption purifier has a precision of 1 pm; the filters at the bottom of the recovery gas tank, the product gas tank, and the regeneration recovery gas tank have a precision of 3 nm.

[0047] The main parameters of the device process are as follows: the diameter of the adsorption purifier is 400 mm, and the height is 8000 mm; the power of the cold and hot all-in-one machine is 50 KW, and the working temperature interval is -70-50℃; there are 3 heating rods, the length is 8000 mm, and the power is 7.5 KW; the adsorption purifier is internally provided with resin-based activated carbon treated by 0.05 mol / L HF; the diameters of the recovery gas tank 14-1, the product gas tank 14-2, and the regeneration recovery gas tank 14-3 are 500 mm, and the heights are 2000 mm; the filling speeds of 16-1, 16-2, and 16-3 are 20-50 L / h. The range of the flow meter is 0-100 L / min; the temperature sensor can monitor the temperature range of -180-450℃. The analytical instrument includes a gas chromatograph with a PDD detector and an infrared spectrum with an optical path pool. The filling amount of the filling pump is 20-100 L / h, and the upper limit of the filling pressure is 16 MPa. The pumping speed of the vacuum system is 20-100 m 3 / h, and the limit vacuum degree absolute pressure reaches 1*10 -5 Pa.

[0048] The impurities in the raw material boron trifluoride are H2, N2, O2+Ar, CH4, CO2, HF, SO2, SO3, and SiF4, and the impurity contents are 50 ppm, 760 ppm, 40 ppm, 10 ppm, 15 ppm, 25 ppm, 12 ppm, 19 ppm, and 13 ppm, respectively.

[0049] The purification steps include: Turn on the nitrogen, set the first flow meter 1 to 50 L / min, and open K3, K5, K6, and K21; Turn on K20, and evacuate the outermost shell layer of the adsorption purifier 2 to 1 Pa absolute pressure, and then close K20; Turn on the heating rod 5, and set the temperature rising program to 200℃ for 3 h, 300℃ for 3 h, 400℃ for 3 h, and finally to 450℃ for 150 h; Close K2, open K3, and set the first flow meter 1 to 20 L / min, and activate it with helium for 18 h; Close K3, K21, and K5, open K4 and K22, and perform vacuum pumping, the front-end system of K5 is pumped for 2 h, the adsorption purifier 2 is pumped for 20 h, K22 is closed, the heating rod 5 is turned off, and the cold and hot all-in-one machine 3 is turned on, and the temperature of the adsorption purifier 2 is -70℃; Open K24, K13, K14, K12, K16, K10, K15, K17, K18, K16, K19, evacuate 0.5 h; close K24, open K23, when the system pressure is equal to the atmospheric pressure, close K23, repeat the evacuation step operation 20 times, close K13, K14, K12, K16, K10, K15, K17, K18, K16, K19 standby; Open K1, the first flow meter 1 flow is adjusted to 30 L / min; when the resistance gauge 6 absolute pressure reaches 1*10 5 Pa, close K1 and stabilize for 4 h, when the resistance gauge 6 absolute pressure decreases to 8.5*10 4 Pa, open K1 again until the absolute pressure cannot decrease to 9*10 4 Pa after closing K1, K1 is no longer opened; Liquid nitrogen 17-1 is introduced at a flow rate of 3 ~ 5 KG / h for pre-cooling; The outlet temperature of the cold and hot integrated machine 3 is increased to adjust the adsorption purifier temperature to -55 ~ -40℃, K9, K10, K6 are opened, and the mass flow meter 7 flow is 1 ~ 10 L / min; the weak adsorption components H2, N2, O2+Ar and other impurities are discharged for a cumulative time of 10 ~ 100 h, and the sampling analysis interval is 2 ~ 4 h; When the impurity contents of H2, N2, O2+Ar and other impurities are lower than 1 ppm, 5 ppm, 1 ppm respectively, the coil in the product gas tank 14-2 is introduced with liquid nitrogen 17-2 at a flow rate of 5 ~ 10 KG / h for pre-cooling; K10 is closed and K15 is opened to start product extraction, the mass flow meter 7 extraction speed is 10 ~ 50 L / min, the extraction temperature is -50 ~ 30℃, and the sampling analysis interval is 2 ~ 4 h; at the same time, the recovery gas charging pump 16-1 is used to charge the material in the tank into the gas cylinder, the liquid phase in the recovery gas tank 14-1 is stopped, and the liquid nitrogen 17-1 is closed.

[0050] The impurity content requirements of the strong adsorption components CH4, CO2, HF, SO2, SO3, SiF4 are 1 ppm, 1 ppm, 1 ppm, 1 ppm, 1 ppm, 2 ppm respectively, when the impurity content of any of the strong adsorption components is higher than the index requirement, K6 is closed, K15, K9 is stopped to extract; K24, K14 are opened to evacuate the pipeline, K24 is closed, K23 is opened to pressurize the pipeline, the above operation is repeated 10 times, K23 is closed, liquid nitrogen is used to pre-cool the analysis sample collection tank 10 for 10 min, K15, K12 are opened to analyze and collect the analysis sample in the collection tank for 2 min, K15, K14 are closed, the pressure reducing valve is closed, and the cold trap is removed, when the total pressure of the pressure reducing valve 8 is higher than 0.5 MPa, the partial pressure is adjusted to 0.2 MPa to analyze the product sample.

[0051] The product in the product gas tank 14-2 is filled into the cylinder using the product filling pump 16-2, and the filling is stopped when there is no liquid phase in the product gas tank 14-2, and the liquid nitrogen 17-2 is closed.

[0052] K15 is closed, K17 is opened, the flow rate of the second flow meter 7 is adjusted to 20 L / min, the flow rate of the liquid nitrogen 17-3 is 5-10 KG / h, the residual raw material in the adsorption purifier 2 is desorbed, the heating rod is opened at 100°C for 4 h and then increased to 250°C, and when the flow rate is lower than 1 L / min, the collection of the residual adsorption gas is stopped; then the product in the regeneration and recovery gas tank 14-3 is filled into the cylinder using the filling pump 16-3, and the filling is stopped when there is no liquid phase in the regeneration and recovery gas tank 14-3, and the liquid nitrogen 17-3 is closed.

[0053] Example 1

[0054] On the basis of the above-mentioned embodiment, the weakly adsorbed impurity removal is performed in a continuous manner for 20 h at a flow rate of 2 L / min and a release temperature of -60°C, the flow rate of the second flow meter 7 is 30 L / min, the temperature is -45°C for 4 h, -30°C for 4 h, -10°C for 4 h, 10°C for 4 h, and 20°C until the end.

[0055] Example 2 Different from Example 1, the weakly adsorbed impurity removal is performed in a batch manner for 25 times at a flow rate of 4 L / min, and each time is 20 min.

[0056] Example 3 Different from Example 1, the weakly adsorbed impurity removal is performed at a flow rate of 4 L / min and a release temperature of -50°C.

[0057] Example 4 Different from Example 1, the weakly adsorbed impurity removal is performed in a batch manner for 30 times at a flow rate of 3 L / min, a release temperature of -50°C, and each time is 20 min, the flow rate of the second flow meter 7 is 15 L / min, and the temperature is increased in a stepwise manner, -30°C for 6 h, -20°C for 6 h, -10°C for 6 h, 0°C for 6 h, 10°C for 4 h, and 20°C until the end.

[0058] The analysis results and yields of the products obtained in each example are shown in Table 1.

[0059]

[0060] In summary, the present application provides a new process for producing high-purity boron trifluoride, which uses a carbon material adsorbent with developed pores and high specific surface area to complete the purification of boron trifluoride in a low-pressure environment, and produces 5N5 electronic grade boron trifluoride with a purity of 5N5, and a single cycle yield of up to 60%, which is suitable for industrial production.

[0061] The above embodiments are not restrictive embodiments of the present application, and any modification, improvement or equivalent transformation made within the spirit and principle of the present application shall be within the technical scope of the present application.

Claims

1. A device for purifying boron trifluoride, comprising a cooling and heating integrated machine (3), an adsorption purifier (2), a recovery gas (14-1), a product gas tank (14-2) and a regeneration recovery gas tank (14-3); the cooling and heating integrated machine (3) and the adsorption purifier (2) are connected to form a loop; a temperature sensor (4) and a heating rod (5) are provided in the adsorption purifier (2); the outermost shell of the adsorption purifier (2) is connected to a vacuum system; the bottom of the adsorption purifier (2) is respectively connected to the vacuum system, a high-purity helium source, a high-purity nitrogen source, and a raw material boron trifluoride through a first flow meter (1); the top of the adsorption purifier (2) is respectively connected to a resistance gauge (6), a second flow meter (7), a vacuum system, and venting through a filter; the second flow meter (7) is divided into two paths, one path is connected to the recovery gas tank (14-1) and the product gas tank (14-2) , the top of the regeneration recovery gas tank (14-3), and the other is connected to the analysis instrument (9) through a pressure reducing valve (8); the analysis instrument (9) is equipped with high-purity helium and an analysis sample collector (10) placed in a cold trap (11); the recovery gas tank (14-1) is provided with a liquid level gauge, a pressure sensor, and a built-in coil, the lower end of the coil is connected to liquid nitrogen, the upper end of the coil is vented, and the bottom of the tank is connected to a filling pump through a filter; the product gas tank (14-2) is provided with a liquid level gauge, a pressure sensor, and a built-in coil, the lower end of the coil is connected to liquid nitrogen, the upper end of the coil is vented, and the bottom of the tank is connected to a filling pump through a filter; the regeneration recovery gas tank (14-3) is provided with a liquid level gauge, a pressure sensor, and a built-in coil, the lower end of the coil is connected to liquid nitrogen, the upper end of the coil is vented, and the bottom of the tank is connected to a filling pump through a filter; each component is connected through pipes and valves.

2. The apparatus for purifying boron trifluoride according to claim 1, characterized in that The adsorption purifier has a jacket, in which heat medium and refrigerant flow, and a vacuum insulation layer is provided on the outside of the jacket.

3. The apparatus for purifying boron trifluoride according to claim 1, characterized in that: The filter installed on the top of the adsorption purifier has a precision of 1 μm.

4. The apparatus for purifying boron trifluoride according to claim 1, wherein: The filter accuracy configured at the bottom of the recovery gas tank, product gas tank, and regenerated recovery gas tank is 3nm.

5. The apparatus for purifying boron trifluoride according to claim 1, characterized in that: The adsorption purifier is provided with an adsorbent filling port and an adsorbent unloading port.

6. The apparatus for purifying boron trifluoride according to claim 1, wherein The flowmeter has a range of 0 to 100 L / min. The adsorption purifier has a diameter of 250 mm to 1000 mm, a height of 1000 to 20000 mm, and is made of 316L. The design pressure of the adsorption purifier body is 4 MPa. The power of the integrated cooling and heating unit is 30 to 200 KW, and the temperature control range is -80 to 50 °C. The power of a single heating rod is 1 to 10 kW, and there are 3 to 8 heating rods. The adsorption bed temperature in the adsorption purifier is 50 to 400 °C. The temperature sensor can monitor the temperature range of -180 to 450 °C. The analytical instruments include a gas chromatograph with a PDD detector and an infrared spectrometer equipped with an optical path cell. The recovery gas tank, product gas tank, and regeneration recovery gas tank have a diameter of 300 mm to 1000 mm, a height of 1000 to 5000 mm, and are made of 316L. The filling capacity of the filling pump is 20 to 100 L / h, and the upper limit of the filling pressure is 16 MPa; vacuum system pumping speed is 20~100m 3 / h, the ultimate vacuum absolute pressure is 1*10 -5 Pa; The adsorbent filled in the adsorption purifier is an activated carbon material in the form of spheres, columns or prisms. The pore size of the adsorbent is distributed in the range of 1-2 nm, with a content of 50%-80%, and a bulk density of 0.4-0.8 g / cm 3 .

7. A method for purifying boron trifluoride, comprising the following steps: (1) Evacuate the outermost shell of the adsorption purifier to an absolute pressure of 1 ~ 10Pa; (2) Turn on the heating rod and set the temperature program to 200℃ for 3 hours, 300℃ for 3 hours, 400℃ for 3 hours, and finally increase to 450℃ for 150 hours; (3) Adjust the flow rate of the first flow meter to 5-50 L / min, and activate the adsorbent with nitrogen at 300-450 °C for 48-200 h; (4) Adjust the flow rate of the first flow meter to 5~50 L / min and use helium to activate the adsorbent for 10~30 hours; (5) Evacuate the adsorption purifier for 10 to 30 hours, turn off the heating rod, cool to room temperature, turn on the cooling and heating integrated machine, and control the temperature of the adsorption purifier at -65 to -75 °C; (6) Evacuate the recovery gas tank, product gas tank, and regeneration recovery gas tank for 0.1 to 3 hours, then fill them with high-purity helium. Repeat the evacuation-filling operation 10 to 30 times for standby use. (7) Adjust the flow rate of the first flow meter to 20~40 L / min; when the absolute pressure of the resistance gauge reaches 1*10 5 Pa, close the vacuum valve of the adsorption purifier and stabilize for 4 hours; when the absolute pressure of the resistance gauge drops to 8.5*10 4 Pa, open the vacuum valve of the adsorption purifier until the absolute pressure of the adsorption purifier is not less than 9*10 4 Pa, close the vacuum system; (8) Pre-cool the recovery gas tank by introducing liquid nitrogen at a flow rate of 3 to 5 kg / h; (9) Use a cooling and heating integrated machine to adjust the temperature of the adsorption purifier to -60~-40℃, open the recovery gas tank inlet pipeline, and adjust the flow rate of the second flow meter to 1~10 L / min; discharge the weakly adsorbed components H2, N2, O2+Ar and other impurities for a cumulative time of 10~100 hours, and take samples for analysis at intervals of 2~4 hours; (10) When the impurity contents of H2, N2, O2+Ar are lower than 1 ppm, 5 ppm, and 1 ppm respectively, liquid nitrogen is introduced into the coil in the product gas tank at a flow rate of 5~10 KG / h for pre-cooling; the air inlet valve of the recovery gas tank is closed, and the air inlet valve of the product gas tank is opened to extract the product. The second flow meter controls the extraction speed to 10~50L / min, the extraction temperature is -50~30℃, and the sampling and analysis interval is 2~4 hours; at the same time, the recovery gas filling pump is used to fill the material in the recovery gas tank into the gas cylinder with recovery gas. When there is no liquid phase in the recovery gas tank, the filling is stopped and the liquid nitrogen in the recovery gas tank is closed; (11) The impurity content requirements of the strongly adsorbed components CH4, CO2, HF, SO2, SO3, and SiF4 are 1 ppm, 1 ppm, 1 ppm, 1 ppm, 1 ppm, and 2 ppm, respectively. When the content of any impurity in the strongly adsorbed component impurities exceeds the index requirement, the production of products shall be stopped; (12) The product output pipeline was vacuumed and re-pressurized with high-purity helium, and the above operation was repeated 10 times; at the same time, liquid nitrogen was used to pre-cool the analytical sample collection tank for 10 minutes, and the analytical sample was collected for 2 minutes. The cold trap was removed, and when the total pressure of the pressure reducing valve was higher than 0.5 MPa, the partial pressure was adjusted to 0.2 MPa for product sample analysis; (13) Use the product filling pump to fill the material in the product gas tank into the gas cylinder. When there is no liquid phase in the product gas tank, stop filling and turn off the liquid nitrogen; (14) Adjust the flow rate of the second flow meter to 20 L / min, and the flow rate of the liquid nitrogen in the regeneration recovery tank to 5~10 KG / h. Desorb the residual raw materials in the adsorption purifier. Turn on the heating rod and stabilize it at 100℃ for 4h and then increase it to 250℃. When the flow rate reading of the second flow meter is lower than 1L / min, stop collecting the residual adsorbed gas; then use the regeneration recovery gas filling pump to fill the material in the regeneration recovery tank into the gas cylinder. Stop filling when there is no liquid phase in the regeneration recovery tank, and turn off the liquid nitrogen in the regeneration recovery tank.

8. The method for purifying boron trifluoride according to claim 7, wherein The adsorption purifier is filled with activated carbon adsorbent. The activated carbon adsorbent is treated with 0.01~0.5 mol / L electronic grade HF aqueous solution at a solid-liquid mass ratio of 1:(5~20) at 30~80℃ for 3~24 hours, and then dried and calcined at 400~500℃ for 10~50 hours under inert gas protection; after acid washing and calcination, the adsorbent is loaded.

9. The method for purifying boron trifluoride according to claim 7, wherein The adsorbent loaded in the adsorption purifier is protected by nitrogen and activated at 300-450°C for 48-200 hours; then it is activated with helium at 300-450°C for 2-24 hours; then the adsorption purifier is evacuated using a vacuum system at 300-500°C for 4-24 hours; the absolute pressure of the vacuum treatment is 0-2 Pa.

10. The method for purifying boron trifluoride according to claim 7, wherein The recovery gas tank, product gas tank, regeneration recovery gas tank and filling pipeline are purged with helium and vacuumed for 5 to 20 times. The single vacuuming treatment time during the helium replacement process is 10 to 120 minutes. The flow rate of boron trifluoride is 10 to 100 L / min. The refrigerant outlet temperature of the hot and cold integrated machine is -80 to -50 °C, the temperature of the adsorption bed is -90 to -30 °C, and the absolute pressure of the adsorption bed is maintained at 8.5*10 4 ~1*10 5 Pa; during the release of BF3 by the adsorbent, the refrigerant outlet temperature of the hot and cold integrated machine is -80~50℃; the temperature of the adsorption bed is -70~50℃; the discharge flow rate of weakly adsorbed components such as H2, N2, O2+Ar is 1~10 L / min, and the release temperature is -60~-40℃; during the discharge of weakly adsorbed components, impurities such as H2, N2, O2+Ar can be removed by continuous or intermittent methods; the control time for intermittent discharge of weakly adsorbed components such as H2, N2, O2+Ar is 10 min~30 min, the interval is 30~120 min, and the number of discharges is 10~50 times; after the weakly adsorbed components such as H2, N2, O2+Ar are qualified by gas chromatography analysis, they are collected using a product collection tank with a collection flow rate of 10~50 L / min and a bed temperature of -50~30℃; the impurity content changes of strongly adsorbed components such as CH4, CO2, HF, SO2, SO3, and SiF4 are monitored by gas chromatography infrared spectroscopy, with a sampling interval of 2~4 h; if the contents of strongly adsorbed components CH4, CO2, HF, SO2, SO3, and SiF4 exceed the standard through gas chromatography and infrared spectroscopy, the hot and cold integrated machine is turned off, the heating rod is turned on, and the residual concentrated boron trifluoride is collected using the regeneration gas recovery tank, and heated to a stable temperature of 200~300℃; during the absorption process, the pressure of the recovery gas tank, product gas tank, and regeneration recovery gas tank is maintained at -0.1~-0.09MPa, and the refrigeration liquid nitrogen injection rate is 5~10 KG / h; the materials in the recovery gas tank, product gas tank, and regeneration recovery gas tank are collected by a filling pump at a filling speed of 20~50 L / h; the filling gas manifold is connected to 1 to 8 product collection cylinders at a time.

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