Method for preparing MoF.SUB.6 .based on plasma activation of SF.SUB.6

Abstract

A method and a device for preparing MoF.sub.6 based on plasma activation of SF.sub.6. The method includes the following steps: S1, filling a discharge area of a plasma reactor with molybdenum powder; S2, introducing an inert gas and an SF.sub.6 gas into the discharge area of the plasma reactor, where the inert gas is ionized into plasma, and the SF.sub.6 gas is ionized into fluorine atoms and low-fluorine sulfides after being activated by the plasma; and S3, generating an MoF.sub.6 gas and sulfur elements through reaction of the fluorine atoms and the low-fluorine sulfides with the molybdenum powder.

Claims

1. A method for preparing molybdenum hexafluoride (MoF.sub.6), comprising the following steps: S1, filling a discharge area of a plasma reactor with molybdenum powder, and filling the discharge area of the plasma reactor with a catalyst that catalyzes activation and ionization of sulfur hexafluoride (SF.sub.6), wherein the catalyst is selected from at least one of aluminium oxide (Al.sub.2O.sub.3) and silicon dioxide (SiO.sub.2); S2, introducing an inert gas and an SF.sub.6 gas into the discharge area of the plasma reactor, wherein the inert gas is ionized into plasma, and the SF.sub.6 gas is ionized into fluorine atoms and low-fluorine sulfides after being activated by the plasma; and S3, generating an MoF.sub.6 gas and sulfur elements through reaction of the fluorine atoms and the low-fluorine sulfides with the molybdenum powder.

2. The method for preparing MoF.sub.6 according to claim 1, wherein in the S1, the molybdenum powder is loaded on quartz wool and then filled into the discharge area of the plasma reactor.

3. The method for preparing MoF.sub.6 according to claim 1, wherein the generated MoF.sub.6 gas is condensed into a liquid state, and then is collected.

4. The method for preparing MoF.sub.6 according to claim 1, wherein in the S3, a reaction temperature is controlled to be 120-140 C., so that the sulfur elements become liquid for collection.

5. The method for preparing MoF.sub.6 according to claim 1, wherein an unreacted low-fluorine sulfide gas is absorbed by alkali liquid.

6. The method for preparing MoF.sub.6 according to claim 1, wherein a device for implementing the method for preparing MoF.sub.6 based on plasma activation of SF.sub.6, comprises an SF.sub.6 gas supply unit, an inert gas supply unit, a mixing unit and a plasma reactor, wherein the SF.sub.6 gas supply unit and the inert gas supply unit are respectively connected to the mixing unit, the SF.sub.6 gas supply unit provides SF.sub.6 gas to the mixing unit, the inert gas supply unit provides inert gas to the mixing unit, the mixing unit is connected to the plasma reactor, and the mixing unit mixes the SF.sub.6 gas and the inert gas and provides a mixture of the inert gas and the SF.sub.6 gas to the plasma reactor.

7. The method for preparing MoF.sub.6 according to claim 6, wherein the plasma reactor is placed vertically or aslant, a gas inlet and a gas outlet of the plasma reactor are located at two ends of the discharge area of the plasma reactor, and the gas inlet of the plasma reactor is located above the gas outlet of the plasma reactor; and a sedimentation pool is arranged at a bottom of the plasma reactor, the sedimentation pool is located below the plasma reactor, and the sedimentation pool is communicated with the bottom of the plasma reactor.

8. The method for preparing MoF.sub.6 according to claim 7, wherein a condensation unit is further comprised, and the condensation unit comprises a condenser and a gas outlet pipe, wherein a liquid collecting tank is arranged at a bottom of the condenser, one end of the gas outlet pipe is communicated with the gas outlet of the plasma reactor, and the other end of the gas outlet pipe is connected to an inlet of the condenser.

9. The method for preparing MoF.sub.6 according to claim 8, wherein a tail gas treatment unit is further comprised, and the tail gas treatment unit comprises an alkali liquid treatment pool, a tail gas inlet pipe and a tail gas outlet pipe, wherein two ends of the tail gas inlet pipe are connected to an outlet of the condenser and the alkali liquid treatment pool respectively, and the tail gas outlet pipe is connected to the alkali liquid treatment pool.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The FIGURE is a structural schematic diagram of a device for aluminum preparing molybdenum hexafluoride (MoF.sub.6) based on plasma activation of sulfur hexafluoride (SF.sub.6).

(2) In the figures: 1SF6 gas cylinder, 2first gas supply branch pipe, 3first pressure reducing valve, 4argon gas cylinder, 5second gas supply branch pipe, 6second pressure reducing valve, 7gas distribution instrument, 8main gas supply pipe, 9electromagnetic flowmeter, 10solenoid valve, 11plasma reactor, 12sedimentation pool, 13condenser, 14liquid collecting tank, 15gas outlet pipe, 16alkali liquid treatment pool, 17tail gas inlet pipe, 18tail gas outlet pipe, 19quartz wool (loaded Mo powder), and 20catalyst.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(3) A device for aluminum preparing molybdenum hexafluoride (MoF.sub.6) based on plasma activation of sulfur hexafluoride (SF.sub.6) of the present disclosure will be described in detail below with reference to the accompanying drawings.

Embodiment 1

(4) The structure of a device for aluminum preparing molybdenum hexafluoride (MoF.sub.6) based on plasma activation of sulfur hexafluoride (SF.sub.6) provided in this embodiment is shown in the FIGURE, and the device includes an SF.sub.6 gas supply unit, an inert gas supply unit, a mixing unit, a plasma reactor 11, a condensation unit and a tail gas treatment unit, where the plasma reactor 11 is a dielectric barrier plasma reactor.

(5) The SF.sub.6 gas supply unit includes an SF.sub.6 gas cylinder 1, a first gas supply branch pipe 2 and a first pressure reducing valve 3, where one end of the first gas supply branch pipe 2 is connected to the SF.sub.6 gas cylinder 1, and the first pressure reducing valve 3 is installed on the first gas supply branch pipe 2. The inert gas supply unit includes an argon gas cylinder 4, a second gas supply branch pipe 5 and a second pressure reducing valve 6, where one end of the second gas supply branch pipe 5 is connected to the argon gas cylinder 4, and the second pressure reducing valve 6 is installed on the second gas supply branch pipe 5. The SF.sub.6 in the SF.sub.6 gas cylinder 1 and the argon gas in the argon gas cylinder 4 are decompressed through the pressure reducing valve and then enter the gas distribution instrument.

(6) The mixing unit includes a gas distribution instrument 7, a main gas supply pipe 8, an electromagnetic flowmeter 9 and a solenoid valve 10, where the other ends of the first gas supply branch pipe 2 and the second gas supply branch pipe 5 are respectively connected to two inlets of the gas distribution instrument 7, and one end of the main gas supply pipe 8 is connected to an outlet of the gas distribution instrument 7. The electromagnetic flowmeter 9 and the solenoid valve 10 are respectively installed on the main gas supply pipe 8, and the electromagnetic flowmeter 9 and the solenoid valve 10 are configured to control the flow rate of a mixed gas of SF.sub.6 and argon.

(7) The plasma reactor 11 is placed vertically, a gas inlet of the plasma reactor 11 is arranged on the top of the plasma reactor 11, and the other end of the main gas supply pipe 8 is connected to the gas inlet of the plasma reactor 11. A sedimentation pool 12 is arranged at the bottom of the plasma reactor 11, the sedimentation pool 12 is located below the plasma reactor 11, the sedimentation pool 12 is communicated with the bottom of the plasma reactor 11, and a gas interface is arranged at an upper part of the sedimentation pool 12.

(8) The condensation unit includes a condenser 13 and a gas outlet pipe 15, where one end of the gas outlet pipe 15 is communicated with the gas outlet of the plasma reactor, and the other end of the gas outlet pipe 15 is connected to an inlet of the condenser 13. A liquid collecting tank 14 is arranged at the bottom of the condenser 13, and the condensed MoF.sub.6 in the liquid state flows into the liquid collecting tank 14 for collection.

(9) The tail gas treatment unit includes an alkali liquid treatment pool 16, a tail gas inlet pipe 17 and a tail gas outlet pipe 18, where both ends of the tail gas inlet pipe 17 are connected to the outlet of the condenser 13 and the alkali liquid treatment pool 16 respectively, and the tail gas outlet pipe 18 is connected to the alkali liquid treatment pool 16. In the alkali liquid treatment pool, the decomposition products (unreacted) of SF.sub.6 such as SO.sub.2, SOF.sub.2 and SOF.sub.4, etc. are absorbed and treated to prevent them from being discharged into the atmosphere and causing damage to the atmosphere and the environment.

(10) A method for aluminum preparing MoF.sub.6 based on plasma activation of SF.sub.6 of the present disclosure will be described in detail below with reference to the above device.

Example 2

(11) S1, an upper half part of a discharge area of a plasma reactor is filled with a catalyst aluminium oxide (Al.sub.2O.sub.3), Mo powder is evenly sprinkled on quartz wool, so that the quartz wool is loaded with the Mo powder, and then the quartz wool loaded with the Mo powder is filled into a lower half part of the discharge area of the plasma reactor; S2, A device for preparing molybdenum hexafluoride (MoF.sub.6) based on plasma activation of sulfur hexafluoride (SF.sub.6) is assembled and connected according to the connection relationship of the above device (as shown in the FIGURE); S3, a second pressure reducing valve 6 is opened, air tightness of the device is detected through an argon gas to prevent harm to the staff caused by toxic gas leakage during a reaction and ensure the stable and orderly reaction, and the second pressure reducing valve 6 is closed after the detection; S4, a first pressure reducing valve 3 and the second pressure reducing valve 6 are opened, and the SF.sub.6 gas in an SF.sub.6 cylinder 1 and the argon gas in an argon gas cylinder 4 are decompressed and then enter a gas distribution device 7 for mixing evenly; and in this case, a condenser 13 is opened until the liquefaction temperature of MoF.sub.6 gas reaches 17.5 C.; S5, a plasma reactor 11 is turned on, and the input voltage and input power are set to 55 V and 90 W respectively, where the temperature in the plasma reactor 11 will rise at the beginning, but after 15 minutes, the temperature in the plasma reactor 11 will stabilize at 130 C.; S6, an electromagnetic flowmeter 9 and a solenoid valve 10 are opened, and the flow rate of a mixed gas of SF.sub.6 and argon is controlled to be 150 ml/min, where the argon gas is ionized into plasma, the SF.sub.6 gas, under the synergistic action of the plasma and a catalyst 20 Al.sub.2O.sub.3, is decomposed into fluorine atoms and low-fluorine sulfides (such as SO.sub.2, SOF.sub.2, SOF.sub.4, etc.), the fluorine atoms and the low-fluorine sulfides react with the Mo powder loaded on quartz wool 19 to generate the MoF.sub.6 gas and a small amount of liquid S elements, the liquid S elements flow downward into a sedimentation tank 12 for collection, the MoF.sub.6 gas enters the condenser 13 for liquefaction and then flows into a liquid collecting tank 14 after the liquefaction, subsequently tail gas is treated through an alkali liquid treatment pool 16, and unreacted decomposition products of SF.sub.6 (such as F.sub.2, SO.sub.2, SOF.sub.2, SOF.sub.4 and other gases) are absorbed; and S7, when no liquid flows out of the condenser, the first pressure reducing valve 3 is closed, after ten minutes, the plasma reactor 11 is closed and argon gas is continuously filled, so that the gas in the plasma reactor 11 is driven to sequentially pass through the condenser 13 and the alkali liquid treatment pool 16, after ten minutes, the condenser 13 and the second pressure reducing valve 6 are closed, and the MoF.sub.6 liquid in the liquid collecting tank is taken out and frozen for storage.