TW201313959A - Electrolytic process for the manufacture of fluorine and an apparatus therefor - Google Patents

Abstract

The present invention concerns an electrolytic process for the manufacture of fluorine comprising the electrolysis of an adduct of KF and HF wherein the electrolytic process is monitored by a thermographic camera, and an apparatus therefor. The method of monitoring the electrolytic process of fluorine production using conventional electrolytic cells, provides the possibility to automate the HF addition by reading the electrolyte level continuously. Additionally malfunctions like external fires (H2 + O2 recombination), internal H2 + F2 recombination due to broken partition walls, insufficient cooling, non optimal electrical connections can easily be detected, which leads to enhanced security of the process and less energy consumption.

Description

Electrolysis method for producing fluorine and device thereof Cross-reference to related applications

The present application claims the priority of the European Patent Application No. 1 117 783 4.6 filed on Aug. 17, 2011, the entire content of which is hereby incorporated by reference.

The present invention relates to an electrolysis process for the manufacture of fluorine comprising electrowinning an adduct of KF with HF, wherein the electrolysis process is monitored by a thermal imager and relates to a device for use in the process.

In the fabrication of semiconductors, photovoltaic cells, thin film transistor (TFT) liquid crystal displays, and microelectromechanical systems (MEMS), fluorine (F ₂ ) can be used as an etching gas, as a chamber cleaning gas, for example, with nitrogen and The concentration in the mixture of argon or argon is usually from 1% to 50% by volume.

Such a method is disclosed, for example, in WO 2007/116033 (indicating the use of fluorine and certain mixtures as etchants and chamber cleaners), WO 2009/080615 (description of the manufacture of MEMS), WO 2009/092453 (description of the manufacture of solar cells) And the unpublished WO patent application PCT/EP 2010/066109 (involving the manufacture of TFTs). F ₂ for etching or chamber cleaning is typically produced in situ by electrolysis of HF in the presence of a conductive salt, especially as described above in the presence of KF (which forms an adduct with HF).

One has the chemical formula KF. (1.8-2.3) The KF-containing HF molten adduct of HF is a preferred electrolyte salt. The HF is fed into a reactor containing the molten electrolyte salt, and F ₂ : 2 HF → F _{2 is} electrolytically formed from HF according to the equation (I) by applying a voltage and passing a current through the molten salt. +H ₂ (I)

In practice, this voltage is typically maintained in the range of 8 to 11 volts.

Electrolysis can be carried out in a device comprising a vessel with a bottom, a cover, a side wall, and containing the electrolyte and acting as a cathode. Alternatively, the vessel can comprise at least one cathode extending into the molten electrolyte. The electrolytic cell comprises at least one anode, preferably a plurality of anodes, and one or more anodes extend into the molten electrolyte. The one or more anodes are typically formed of carbon and may be cylindrical, flat, for example they may be square, but in principle they may have any other desired shape. The apparatus also includes a power supply line connected to the anode and the cathode, and a line for supplying HF and for taking out the generated F ₂ and H ₂ . This invention relates to such devices.

In the electrolysis process, HF is consumed (KF is only used to provide conductivity to the electrolyte). The amount consumed may vary depending on the electrolytic cell, depending on the power applied, the conductivity of the electrolytic cell, the temperature of the electrolyte, the viscosity, and the resulting current. As a result, the liquid level of the electrolyte is lowered and the consumed HF must be replenished. When the liquid level reaches a certain lower limit, it can be supplied HF, and this supply can be stopped when an upper limit is reached.

No. 7,531,322 describes a method for controlling the electrolyte level by means of a liquid level sensor which extends into the interior space of the container and which can detect the electrolyte level in five liquid level stages.

It is an object of the present invention to provide a simple and technically feasible method for controlling not only the level of electrolyte in an electrolytic cell for the electrolysis of fluorine (F ₂ ) from a solution of KF in HF, but also for detecting no Normal process conditions such as cover failure, excessive supply line resistance, wall failure in the vessel, cooling failure, and other failures of the unit. Another object of the invention is to provide an apparatus suitable for use in the electrolysis of fluorine according to the invention. These objects are achieved by the invention disclosed in the scope of the patent application.

Summary of invention

Accordingly, there is provided a method for electrolytically producing fluorine from hydrogen fluoride containing a molten electrolyte in a device including an electrolytic cell, the electrolyte comprising HF and potassium fluoride dissolved therein as an electrolyte salt, the electrolytic cell having a bottom, a side wall, a cover, a power supply line for at least one anode, a power supply line for the cathode, a line for supplying hydrogen fluoride, a partition wall, an anode chamber, a cathode chamber, a molten electrolyte containing HF and dissolved KF, wherein current flows through the anode, And F ₂ and H _{2 are} formed by electrolysis of HF, wherein the camera discriminates at least one process condition and provides a thermal image.

Detailed description of preferred embodiments

The thermal image provides an actual view of the device, one or more regions of the device, or the temperature of various components of the device. Thermal images are used to evaluate if the method is working correctly. The actual thermal image can be compared to one or more thermal images taken while the method is operating correctly.

The term "process condition" refers to any process condition that affects the thermal image provided by the camera. Corresponding process conditions may be any desired or undesirable events or changes in the process of the working component or electrolysis process, and the impact of these events or changes causes the temperature profile of the thermal image to be indicative of a predetermined temperature range. Temperature deviation at lower or higher temperatures.

The term "process condition" preferably means:

● The change in electrolyte level exceeds the predetermined upper or lower level

• The temperature of the electrolyte is higher than the predetermined temperature, indicating that the electrolytic cell may be short-circuited due to a faulty or broken anode, or that the partition wall of the space above the isolated anode is broken to prevent the dangerous exothermicity of the F ₂ and H ₂ gases. Recombination reaction

• The supply line is overheated, which indicates contact between the supply line and the anode (or one or more anodes if there are several anodes) or between the supply line and the cathode (or multiple cathodes if there are several cathodes) Poor cause high resistance

● hot side of the cover cap, the display cover broken, and H ₂ are reacted with air or fluoro and leaves the reactor (i.e., combustion, respectively).

The actual image of the camera can be performed by an operator or monitoring station. Evaluation. Preferably, both the operator and the monitoring station are remote from the electrolytic cell. The actual image can be provided via a cable or via electromagnetic waves.

The operator can compare the actual image of the device to one or more images taken under operable conditions. For example, the wall area of the container that is not in contact with the electrolyte but in contact with the space above the electrolyte may be orange, while the area of the wall of the container that is in contact with the electrolyte may be white (depending on the color assigned by the camera for a particular temperature). The operator can immediately recognize whether the electrolyte level indicated by the white and orange boundaries is within a predetermined range. If the liquid level is too low, the operator will start the HF supply until the desired electrolyte level is reached.

If a high ohmic resistance is generated between the power supply line and the anode tip or between the power supply line and the one or more cathodes, the operator will recognize the corresponding red or white color on the power supply line. If the hot spot can be identified above the cover, the cover may be broken or not completely closed.

If the temperature of the electrolyte is too high, a malfunction or misalignment of the cooling system may be the cause. Correspondingly, if there is a hot spot, then the broken anode may cause an electrical short, or the reaction between H ₂ and F ₂ may be caused by breakage of the partition around the one or more anodes.

Depending on the observations, the operator can draw conclusions and stop the process to repair the anode, the cover, or the dividing wall, increase or decrease the cooling capacity, add HF, improve electrical contact between the current conducting components, or increase Or reduce the current / voltage.

If desired, thermal images can be automatically monitored by the monitoring station. The best is monitored by a remote monitoring station.

In the monitoring station, the actual image provided by the thermal imager is evaluated electronically by an automated monitoring station, for example by comparing it to one or several images, which images provide representative of the electrolysis process. One or more thermal images of accepted or customary conditions are for reference. Such automatic monitoring is described in US 2010/0044567 (now US Patent 7,989,769), wherein the reference image is referred to as a "mask."

In a preferred embodiment, the at least one process condition evaluated is selected from the group consisting of electrolyte level, electrolyte temperature, electrical resistance in the power supply line, or from H ₂ and oxygen or fluorine. The heat caused by the reaction between the two, and if the evaluation of the thermal image shows a temperature deviation exceeding a predetermined threshold, the monitoring station reacts by issuing an alarm, such as an audible or visual alarm.

In another preferred embodiment, the at least one process condition is selected from the group consisting of: electrolyte level, electrolyte temperature, power supply line for one or more anodes or one or more cathodes a resistance in, or a heat caused by a reaction between H ₂ and oxygen or fluorine, and if the evaluation of the thermal image shows a temperature deviation exceeding a predetermined threshold, the monitoring station adjusts the cooling capacity to initiate the shutdown of the fluorine-making electrolysis The action of the process, or it may even initiate the action of introducing a gas or liquid to extinguish any flame, such as a hydrogen flame.

According to a preferred embodiment, the monitoring station initiates the supply of HF to the electrolytic cell, if desired.

Depending on the result of the comparison, if the evaluation of the actual thermal image shows that The process can be performed as desired, and the monitoring station can even provide no response, although the monitoring station can formulate the result.

Sensitive thermal imaging cameras in the range encompassed in the 3 to 15 μm region are commercially available. Preferably, they include a non-cooled sensor. For example, thermal imaging cameras sold by Testo AG, Germany, especially thermal imagers sold under testo 880-1, testo 880-2, and testo 880-3 are very suitable. These cameras have a spectral range of 8 to 14 μm. Other providers of thermal imaging systems suitable for use in the method of the present invention are Fluke Corporation, Sierra Pacific Innovations, from FLIR Systems, Inc., and many others.

The advantages of the method of the invention are simple monitoring methods and, if desired, can be reacted manually or automatically when changes in process conditions or failures are detected.

Another aspect of the invention relates to a device for electrolytically producing fluorine from HF containing dissolved KF as an electrolyte salt, the device comprising an electrolytic cell (1) having a bottom (2), a side wall (3), a cover Cover (4), power supply line/anode (5), power supply line/cathode (13), line (6) for supplying hydrogen fluoride, partition wall (7), cathode chamber (8), anode chamber (9), heat The imager (10), optionally, a remote monitoring station (11), and optionally a line (12) for connecting the thermal imager (10) to the remote monitoring station (11). When present in the device, the molten electrolyte is indicated by reference symbol (E).

Preferably, the device comprises a remote monitoring station (11). The monitoring station (11) can be connected by a cable (12) or by an electromagnetic wave transceiver (for example, transmitting and receiving The line signal) is connected to the camera (10).

As mentioned above, there are several types of electrolytic cells. This container can be used as a cathode; this embodiment is shown in FIG. In other alternatives, one or more cathodes are immersed in the liquid electrolyte.

This device is very useful for carrying out the method of the invention therein. For example, the process of the invention can be carried out in the apparatus as follows: KF and HF are charged into the electrolytic cell (1) such that the molar ratio of KF to HF is approximately in the range of 1:1.8 to 1:2.3. Inside. For example, a corresponding solid adduct of KF and HF can be applied. The electrolyte, labeled (E) in Figure 1, is heated until it melts. Its melting point is about 72 ° C. It can even be heated to 100 ° C or higher. Current is passed through the current line (5) and the anode connected thereto, and through the current line (13) and the cathode connected thereto. Sometimes the side walls (3) and bottom (2) of the electrolytic cell (1) serve as a cathode. In another type of cell, neither the bottom nor the sidewalls are used, but a cathode surrounding each anode is used, and thus the cathodes are incorporated in the cell. F _{2 is} formed and collected in the anode chamber (9), and H _{2 is} formed and collected in the cathode chamber (8). In order to prevent recombination of F ₂ and H ₂ , several partition walls (7) were used. The thermal imager (10) is activated and provides the actual thermal image of the electrolytic cell (1). The actual image can be compared with the thermal image taken when the electrolytic cell (1) was correctly operated earlier as a reference image of the electrolytic cell (1). In order to evaluate whether the process is operating correctly, the operator should focus on the difference between the reference image and the actual thermal image, paying particular attention to the temperature of the current lines (5) and (13), and the temperature of the electrolyte (E) (electrolyte (E) The liquid level is represented by a line separating the hot zone of the electrolyte (E) from the colder zone of the anode compartment (9) and the cathode compartment (8), and any hot spots near the cover (4) ( May indicate a hydrogen flame). If the current line (5) and/or the current line (13) are overheated, a poor electrical contact between the anode and the current line or current line and the cathode may be a corresponding cause. The flow of current should be stopped and the connection between the current line and the anode or current line to the cathode should be tightened, cleaned, and/or the non-conductive layer/material should be removed, and/or optionally reconnected Add conductive material before. If the level of electrolyte (E) is below the desired level, HF can be fed via line (6). If the electrolyte (E) is overheated, the broken cathode, insufficient cooling or broken partition wall (7) may be the cause. Incorrect operation of the process and other causes of changes generated on the actual thermal image can be identified by an experienced operator.

In an alternate embodiment, the monitoring station evaluates one or more actual thermal images as compared to one or more images taken during the correct presentation of the device. The monitoring station can be the distal end where the device is placed. The actual image from the camera (10) can be sent to the remote monitoring station (11) via cable (12) or other means (e.g., wireless signals). The remote monitoring station receives the actual thermal image from the thermal imager as described in U.S. Patent 7,989,769. The monitoring station provides at least one template corresponding to one thermal image, and the template provides temperature thresholds for different template regions, such as for electrolytes, current lines, or spaces around the cover. The monitoring station automatically compares the temperature of one or more actual thermal images of different template regions to the temperature threshold associated with the template region. Alarms can be generated, or other actions can be initiated, such as supplying HF to the electrolyte, turning off the current, turning off the electrolytic cell, or providing an extinguishing agent. The monitoring station can also detect dust on the camera lens Related deteriorating effects.

If desired, the device can be integrated into a device constructed in accordance with the "slider" concept. Such devices are particularly suitable for battery F for use in semiconductor manufacture, TFT, photovoltaics, and microelectromechanical apparatus used in the production of _2, and preferably the apparatus comprises a slide member is selected from the group consisting of Mounted module: - a slide mounted module comprising at least one HF storage tank, designated as slide 1 - a slide mounted module comprising at least one electrolytic cell for manufacturing F ₂ according to the present invention , labeled as slide 2, - a slide-mounted module comprising a purification device for purifying F ₂ , designated as slide 3, - a slide-mounted mold comprising means for delivering fluorine gas to the point of use a set, labeled as a slide 4, - a slide-mounted module comprising a cooling water circuit, designated as a slide 5, - a slide-mounted module comprising a treatment of the exhaust device, designated as a slide 6, - means for analyzing module ₂ F slide member is mounted, the slide member 7 is indicated, and - a module of the slide means comprises an operating electrolytic cell mounted in the member, the slide member 8 is marked.

Such a device constructed in accordance with the concept of a slider is disclosed in the unpublished U.S. Provisional Patent Application Nos. 61/383,204 and 61/383,533, and the present disclosures. The entire contents of the International Patent Application Publication No. WO 2012/034978, the entire contents of each of which is incorporated herein by reference.

In such an apparatus according to the slider concept, the electrolytic cell for manufacturing F ₂ of the present invention is incorporated in the slider 2.

In the event that any of the patents, patent applications, and disclosures disclosed herein are inconsistent with the description of the present application to the extent that the term is unclear, the present specification is preferred.

The following examples are intended to illustrate the methods of the invention in detail, but are not intended to limit the scope of the invention.

Example 1: Manufacturing F in an electrolytic cell ₂

The electrolysis system is carried out in an electrolyzer unit in which several electrolytic cells can be assembled in one electrolytic cell chamber. The cathode of each electrolytic cell is represented by an electrolytic cell container (also referred to as an electrolytic cell) which is made of stainless steel or nickel. The cell container is connected to the (-) pole of the rectifier or, in the case of a series connection, it is further joined to the next anode bus bar. Each electrolytic cell includes a number of anodes that are made of carbon. The (+) pole side of a single rectifier (or cathode in the case of a series connection) is connected to the (+) pole of the bus bar, and the bus bar is mounted on the electrolytic cell for supplying different anodes in parallel.

The electrolytic cells are connected in series from (+) to (-), thereby connecting the (+) pole of the main bus bar to the anode of the first electrolytic cell and connecting the (-) pole of the main bus bar to On the cathode of the last electrolytic cell; between them, each The other cathodes are connected to the respective anodes via a short bus bar. In such a series connection, each electrolytic cell can be split via a short circuit switch.

When a direct current of 10 to 11 V is applied, F ₂ formed on the surface of the anode is collected in the corresponding anode chamber.

The camera periodically captures an image of the electrolytic cell and transmits each image to a remote monitoring station via a wireless signal. At the monitoring station, the actual image is compared to the template to identify an abnormal behavior or to indicate a deviation of the electrolyte level in the electrolytic cell to a lower limit. If such a numerical deviation is recognized in the template, the monitoring station automatically sends an alarm; if the HF level is too low, it initiates the HF feed to the electrolytic cell; if the electrolyte reaches the desired upper level, then it stops HF Feeding to the electrolytic cell; or under abnormal conditions, such as multiple hot spots indicating poor electrical connection resulting in a correspondingly higher resistance, or multiple hot spots showing a reaction between H ₂ and F ₂ in the electrolytic cell or in an electrolytic cell The reaction between the external H ₂ and the air, the monitoring station initiates the action of stopping the feeding of the HF into the electrolytic cell, the action of starting the stopping of the current, completely shutting down the electrolytic cell for manufacturing the F ₂ or even the entire device, and/or the fire extinguishing agent Provided to the vicinity of the electrolytic cell. The monitoring station can also send a signal to, for example, the control panel to indicate which abnormal condition is causing the corresponding action.

1‧‧‧ Electrolytic cell

2‧‧‧ bottom

3‧‧‧ side wall

4‧‧‧ Cover

5‧‧‧Power supply line / anode

6‧‧‧Pipeline for the supply of hydrogen fluoride

7‧‧‧ partition wall

8‧‧‧Cathode chamber

9‧‧‧Anode chamber

10‧‧‧ Thermal Imager

11‧‧‧Remote monitoring station

12‧‧‧ lines

13‧‧‧Power supply line / cathode

E‧‧‧ Electrolytes

Figure 1 shows an apparatus in which the method of the invention can be carried out. The device comprises an electrolytic cell (1) in which a container formed by the side walls (3) and the bottom (2) serves as a cathode. The device comprises a thermal imager (10) and a remote monitoring station (11).

1‧‧‧ Electrolytic cell

2‧‧‧ bottom

3‧‧‧ side wall

4‧‧‧ Cover

5‧‧‧Power supply line / anode

6‧‧‧Pipeline for the supply of hydrogen fluoride

7‧‧‧ partition wall

8‧‧‧Cathode chamber

9‧‧‧Anode chamber

10‧‧‧ Thermal Imager

11‧‧‧Remote monitoring station

12‧‧‧ lines

13‧‧‧Power supply line / cathode

E‧‧‧ Electrolytes

Claims (15)

A method for electrolytically producing fluorine from hydrogen fluoride containing a molten electrolyte in a device including an electrolytic cell, the electrolyte comprising HF and potassium fluoride dissolved therein as an electrolyte salt, the electrolytic cell having a bottom, a side wall, a cover, a power supply line for at least one anode, a power supply line for a cathode, a line for supplying hydrogen fluoride, a partition wall, an anode chamber, a cathode chamber, a molten electrolyte containing HF and dissolved KF, wherein current flows through the anode and the cathode, and F ₂ and H _{2 are} formed by electrolysis of the HF, wherein the camera discriminates at least one process condition and provides a thermal image. The method of claim 1, wherein the at least one process condition is selected from the group consisting of: the electrolyte level, the electrolyte temperature, and the electrical resistance in the power supply line. The method of claim 1, wherein the at least one process condition is selected from the group consisting of heat caused by a reaction between H ₂ and oxygen or fluorine. The method of claim 1, wherein the thermal image is monitored by an operator. The method of claim 1, wherein the thermal image is automatically monitored by a monitoring station. The method of claim 5, wherein the thermal image is remotely monitored by a monitoring station. The method of claim 5, wherein the monitoring station evaluates the thermal image based on a predetermined schedule to provide an automatic response when a predetermined temperature threshold is exceeded. The method of claim 7, wherein the monitoring station provides at least one mask corresponding to a thermal image from the thermal imager, wherein the stencil provides a temperature threshold for different stencil regions. The method of claim 1, wherein the process condition is the electrolyte level. The method of claim 9, wherein if the evaluation of the thermal image indicates that the electrolyte level has decreased below a predetermined minimum level, the monitoring station initiates supply of HF to the electrolytic cell, or If the evaluation of the thermal image indicates that the electrolyte level has exceeded a predetermined maximum level, the monitoring station stops supplying HF to the electrolytic cell. The method of claim 5, wherein the at least one process condition is selected from the group consisting of: the electrolyte level, the electrolyte temperature, the electrical resistance in the power supply line, or from H ₂ with oxygen or fluorine. The heat between the reactions, wherein if the evaluation of the thermal image shows that the temperature deviation exceeds a predetermined threshold, the monitoring station issues an alarm. The method of claim 5, wherein the at least one process condition is selected from the group consisting of: the electrolyte level, the electrolyte temperature, electrical resistance in the power supply line, or H ₂ and oxygen or The heat caused by the reaction between fluorine, wherein if the evaluation of the thermal image shows that the temperature deviation exceeds a predetermined threshold, the monitoring station initiates the action of shutting down the electrolysis process for producing fluorine. The method of claim 1, wherein the camera is sensitive in the region of 3 to 15 μm and includes a non-cooled sensor. An apparatus for producing fluorine from HF electrolysis containing dissolved KF as an electrolyte salt, wherein the apparatus comprises an electrolytic cell (1), and the electrolytic cell has a bottom (2), a side wall (3), a cover (4), Power supply line / anode (5), power supply line / cathode (13), line (6) for supplying hydrogen fluoride, partition wall (7), cathode chamber (8), anode chamber (9), thermal imager (10) Optionally, a remote monitoring station (11), and optionally a line (12) for connecting the thermal imager (10) to the remote monitoring station (11). The device of claim 14 of the patent application additionally includes a remote monitoring station (11).