Ultra-high purity hydrogen fluoride purification method and apparatus

Abstract

The present invention discloses a method and apparatus for purifying ultra-high purity hydrogen fluoride in which crude hydrogen fluoride is directly fed into a multi-stage distillation column instead of hydrogen fluoride, and the crude hydrogen fluoride is purified through a continuous distillation process, and impurities in the hydrogen fluoride are removed by contacting the hydrogen fluoride with fluorine gas, the concentration of which is automatically controlled according to the content of arsenic fluoride as an impurity.

Description

[Technical Field]

[0001] The present invention discloses a purification method and apparatus capable of producing ultra-high purity hydrogen fluoride. [Background technology]

[0002] Hydrogen fluoride (HF) is used in a variety of industrial fields. It is the most commonly produced fluorine compound and is supplied in anhydrous form and as hydrofluoric acid in an aqueous solution containing ultrapure water.

[0003] Hydrofluoric acid is produced by a variety of purification processes, such as distillation using hydrogen fluoride as a raw material, electrolysis, adsorption, and membrane separation (Patent Documents 1 to 3), and among these, the distillation process using a fractional distillation process is widely used.

[0004] Hydrogen fluoride is produced by adding sulfuric acid to fluorite (CaF2) and heating it at the same time. The crude hydrogen fluoride produced by this reaction contains hydrogen fluoride as well as SO2 and trace amounts of various impurities such as AsF3, BF3, PF5, SiF4, FeF3, and SF6. These impurities are removed through various purification processes, including pretreatment, and industrial hydrofluoric acid can be produced using hydrogen fluoride with a purity of typically 99.9%.

[0005] Low-purity hydrofluoric acid, such as industrial-grade hydrofluoric acid, is used in industrial applications, while ultra-high-purity hydrofluoric acid is required for etching and cleaning applications in semiconductors and displays.

[0006] Ultra-high-purity hydrofluoric acid used for etching and cleaning is made by diluting anhydrous hydrofluoric acid with ultra-pure water at a certain ratio. If impurities are present in this hydrofluoric acid for semiconductor manufacturing processes, they will remain on the wafer during etching and cleaning, causing pattern formation defects and reducing semiconductor production yields. Therefore, to reduce the defect rate, ultra-high-purity hydrogen fluoride, especially ultra-high-purity hydrogen fluoride with metal impurity concentrations controlled to a few ppt, is used. However, the higher the purity of hydrogen fluoride, the higher the purification costs, the more care is required to prevent contamination during storage and handling, and there are disadvantages such as low production efficiency and low conversion rate to high-purity hydrogen fluoride.

[0007] Most of the impurities contained in hydrogen fluoride can be removed by distillation purification, but impurities such as arsenic (As) exist as arsenic trifluoride (AsF3) in anhydrous hydrofluoric acid. These impurities have a boiling point of 57.13°C, which is not significantly different from the boiling point of hydrofluoric acid (HF), 19.5°C, forming an azeopropic point, making them difficult to separate by distillation purification.

[0008] Arsenic fluoride not only adversely affects the characteristics of semiconductor devices but also causes equipment corrosion and environmental problems, so it is preferable to remove it during the ultra-high purity hydrogen fluoride production process.

[0009] Previously, a method was proposed to produce high-purity hydrogen fluoride by mixing an aqueous oxidizing agent solution, such as hydrogen peroxide or potassium permanganate, with hydrogen fluoride and removing arsenic fluoride from the hydrogen fluoride. However, this method resulted in production losses and the generation of large amounts of reaction by-products due to partial dissolution of hydrogen fluoride in the water of the oxidizing agent solution used. Furthermore, the water-containing hydrogen fluoride is significantly more corrosive than hydrogen fluoride itself, shortening the preventive maintenance (PM) cycle of production equipment and reducing process productivity. This method also presented process issues and stability problems due to the hydrogen fluoride.

[0010] Furthermore, a pretreatment process to remove impurities such as arsenic is performed before the process of producing hydrofluoric acid from hydrogen fluoride, which requires additional equipment and increases process costs. Furthermore, even after pretreatment, impurities remaining in hydrogen fluoride are not easily removed in the purification process, making it difficult to produce high-purity, especially ultra-high-purity, hydrogen fluoride. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Republic of Korea Patent Publication No. 10-2006-0014138 [Patent Document 2] Republic of Korea Patent Publication No. 10-2013-0141402 [Patent Document 3] Japanese Patent Publication No. 1994-144805 Summary of the Invention [Problem to be solved by the invention]

[0012] With existing technology, hydrogen fluoride is produced from fluorite (CaF2), but this generates a large amount of environmental waste, which can significantly increase production costs. To solve this problem, we have been conducting research into the production of ultra-high purity hydrogen fluoride.

[0013] The process for producing ultra-high purity hydrogen fluoride is carried out in the order of a pretreatment process and a purification process of crude hydrogen fluoride, but the present invention proposes a method for producing ultra-high purity hydrogen fluoride by performing a purification process using crude hydrogen fluoride as a raw material, excluding the pretreatment process. In addition, the present invention is the result of extensive research into producing ultra-high purity hydrogen fluoride without the pretreatment process.

[0014] As a result, by introducing a gas stream that can oxidize and remove impurities from crude hydrogen fluoride, which coexists in both gaseous and liquid forms inside the multi-stage distillation column, and by applying an Advanced Process Control (APC) module as the input process processor, it can be immediately applied to the purification process depending on the quality of the raw material crude hydrogen fluoride, thereby enabling the continuous production of ultra-high purity hydrogen fluoride at a high mass production conversion rate.

[0015] Therefore, the present invention provides a purification method and apparatus that can produce ultra-high purity hydrogen fluoride using crude hydrogen fluoride as a raw material. [Means for solving the problem]

[0016] In order to achieve the above object, the present invention provides: providing crude hydrogen fluoride from a feed supply; a step of carrying out a continuous distillation process in which the crude hydrogen fluoride is supplied to a multi-stage distillation column and fractionally distilled, and then impurities in the distillation column are extracted and removed, and the distilled hydrogen fluoride is transported to a subsequent multi-stage distillation column; injecting a gas stream containing F gas and an inert gas into the multi-stage distillation column into which the crude hydrogen fluoride has been introduced to remove AsF from the impurities; The present invention provides a method for purifying ultra-high purity hydrogen fluoride, in which the gas stream used has a concentration adjusted depending on the content of AsF3 contained in the hydrogen fluoride that has passed through the multi-stage distillation column.

[0017] Additionally, the gas stream containing the F2 gas and the inert gas is also injected into other multi-stage distillation columns into which crude hydrogen fluoride is not introduced.

[0018] The present invention also provides a raw material supply unit for supplying a crude hydrogen fluoride raw material; A distillation purification unit equipped with a plurality of multi-stage distillation columns for performing a continuous distillation process; a gas supply unit for supplying a gas stream containing F gas and an inert gas into the multi-stage distillation column; a recovery section for recovering ultra-high purity hydrogen fluoride; Equipped with an advanced process control unit for process control that enables continuous processes, The present invention provides an apparatus for purifying ultra-high purity hydrogen fluoride, in which the gas stream, the concentration of which has been adjusted by the advanced process control unit in accordance with the content of AsF contained in the hydrogen fluoride that has passed through the multi-stage distillation column, is supplied to the multi-stage distillation column into which crude hydrogen fluoride has been introduced. [Effects of the Invention]

[0019] The process for purifying ultra-high purity hydrogen fluoride according to the present invention is carried out by continuous supply, and the process can be continuously repeated until it is interrupted due to the need to stop the flow of hydrogen fluoride when inspection of the production equipment or preventive maintenance (PM) is required.

[0020] In addition, by using crude hydrogen fluoride without pre-treating the raw material hydrogen fluoride, the process is simplified and pre-treatment costs are reduced. In particular, impurities can be minimized by introducing a gas stream into the first multi-stage distillation column into which crude hydrogen fluoride is introduced.

[0021] Furthermore, even if the composition or content of impurities in crude hydrogen fluoride is not constant, it is possible to produce ultra-high purity hydrogen fluoride of uniform quality with high efficiency.

[0022] Such a method simplifies the purification process and enables the economical and efficient production of ultra-high purity hydrogen fluoride. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic diagram used for purifying ultra-high purity hydrogen fluoride according to the present invention. [Figure 2] 1 is a schematic diagram illustrating an apparatus for purifying hydrogen fluoride according to one embodiment of the present invention. [Figure 3] The procedure for controlling the F2 gas concentration using the APC module is shown below. [Figure 4]FIG. 2 is a schematic diagram showing an apparatus for purifying hydrogen fluoride according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] The present invention relates to a process for producing a hydrogen fluoride catalyst, the process comprising the steps of: providing crude hydrogen fluoride from a raw material supply; a step of carrying out a continuous distillation process in which the crude hydrogen fluoride is supplied to a multi-stage distillation column and fractionally distilled, and then impurities in the distillation column are extracted and removed, and the distilled hydrogen fluoride is transported to a subsequent multi-stage distillation column; injecting a gas stream containing F gas and an inert gas into the multi-stage distillation column into which the crude hydrogen fluoride has been introduced to remove AsF from the impurities; The present invention relates to a method for purifying ultra-high purity hydrogen fluoride, in which the gas stream used has a concentration adjusted depending on the content of AsF3 contained in the hydrogen fluoride that has passed through the multi-stage distillation column.

[0025] The present invention also provides a method for producing a hydrogen fluoride catalyst using a raw material supply unit for supplying a crude hydrogen fluoride raw material; A distillation purification unit equipped with a plurality of multi-stage distillation columns for performing a continuous distillation process; a gas supply unit for supplying a gas stream containing F gas and an inert gas into the multi-stage distillation column; a recovery section for recovering ultra-high purity hydrogen fluoride; Equipped with an advanced process control unit for process control that enables continuous processes, The present invention relates to an apparatus for purifying ultra-high purity hydrogen fluoride, in which a gas stream whose concentration has been adjusted by the advanced process control unit in accordance with the content of AsF contained in the hydrogen fluoride that has passed through the multi-stage distillation column is supplied to the multi-stage distillation column into which crude hydrogen fluoride has been introduced. [Example]

[0026] As used herein, the term "ultra-high purity hydrogen fluoride" is recognized in the art to mean a gas having a purity of 99.9999% (6N) or greater. The ultra-high purity hydrogen fluoride is a gas having a purity of 99.9999% (6N) or greater. 9) or less, preferably one part per trillion (ppt, part per trillion, 10 12 ), part per quadrillion (ppq, part per quadrillion, 10 15 ) level to remove specific impurities.

[0027] The term "impurities in ultra-high purity hydrogen fluoride" referred to in this invention means all components other than HF, and major impurities include SO2, AsF3, BF3, SiF4, FeF3, SF6, and PF5.

[0028] In this case, since impurities other than AsF3 in hydrogen fluoride can be easily removed by multistage distillation, the impurity to be reduced by this invention is essentially AsF3.

[0029] That is, in the removal of impurities using the gas stream of the present invention, the substantial impurity is considered to be AsF3, which is trivalent arsenic fluoride, and its oxidized form, AsF5, is pentavalent arsenic fluoride.

[0030] The present invention provides a purification method and apparatus that can continuously purify crude hydrogen fluoride as a raw material for 24 hours and produce ultra-high purity hydrogen fluoride with impurities removed to ppt or less, preferably ppq level, through automatic control.

[0031] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the description of the embodiments, the same reference numerals will be used to designate the same components, and in some cases, the description of the same reference numerals will be omitted.

[0032] FIG. 1 is a schematic diagram used for purifying ultra-high purity hydrogen fluoride according to the present invention.

[0033] Referring to FIG. 1, the purification of ultra-high purity hydrogen fluoride includes a raw material supply unit 100 for supplying crude hydrogen fluoride raw material, a distillation purification unit 200 equipped with a plurality of multi-stage distillation columns for performing a continuous distillation process, a gas supply unit 300 for supplying a gas stream to the multi-stage distillation columns, a recovery unit 400 for recovering ultra-high purity hydrogen fluoride, and an advanced process control unit 500 for process control to enable a continuous process.

[0034] The raw material supply unit 100 is a device for supplying crude hydrogen fluoride, which is a raw material for ultra-high purity hydrogen fluoride, and includes a storage tank for storing crude hydrogen fluoride produced by the reaction of fluorite with sulfuric acid.

[0035] Conventionally, hydrogen fluoride used as a raw material for hydrogen fluoride purification has been pretreated to remove impurities to the ppm level, but in the present invention, crude hydrogen fluoride is used as the raw material input into raw material supply unit 100 for hydrogen fluoride purification. The crude hydrogen fluoride contains crude hydrogen fluoride obtained by reacting fluorite with sulfuric acid and excess impurities (at the % level), and is a raw material that does not undergo any additional pretreatment. The use of such crude hydrogen fluoride significantly reduces the cost of supplying and receiving raw materials compared to conventional hydrogen fluoride, and by eliminating the pretreatment process, it is possible to simplify the process and reduce production costs.

[0036] The crude hydrogen fluoride from the raw material supply unit 100 is either directly supplied in a liquid state to the subsequent distillation purification unit 200 or vaporized into a gaseous state and then supplied. In this case, supplying the crude hydrogen fluoride in a gaseous state involves only a change in properties, and does not include the term "separate pretreatment step."

[0037] The distillation purification section 200 is a device for removing impurities from the crude hydrogen fluoride by a fractional distillation process to obtain ultra-high purity hydrogen fluoride.

[0038] The fractional distillation process can be a batch distillation process or a continuous distillation process, and is carried out using a continuous distillation process, particularly a continuous distillation process in which the distillate passes through a continuous multi-stage distillation column having two or more distillation stages and capable of continuous distillation.

[0039] The continuous distillation process includes a multi-stage distillation column that vaporizes crude hydrogen fluoride to concentrate and purify it, and a reboiler that heats the crude hydrogen fluoride to generate hydrogen fluoride vapor.

[0040] The multi-stage distillation column has 2 to 50 theoretical stages, and for example, 3 to 40 theoretical stages. When heated by the reboiler, gaseous hydrogen fluoride and impurities coexist within the multi-stage distillation column together with liquid crude hydrogen fluoride, and the gaseous components are separated into the top region, intermediate region, and bottom region of the multi-stage distillation column. Low-boiling-point impurities are transported to the top region and discharged, and high-boiling-point impurities are transported to the bottom region and discharged. Hydrogen fluoride is located in the intermediate region and is continuously transported to the next multi-stage distillation column.

[0041] Distillation purification section 200 is configured by connecting 2 or more, 3 to 40, or 4 to 25 multi-stage distillation columns, and is capable of producing ultra-high purity hydrogen fluoride by continuously passing the gas through the multi-stage distillation columns. The multi-stage distillation columns are connected to each other by piping, and may be arranged in series, parallel, or a mixture thereof, and preferably connected in series.

[0042] The gas supply unit 300 is a device for supplying a gas stream for removing impurities, particularly AsF, from crude hydrogen fluoride. The gas stream contains F gas and an inert gas for carrying and diluting the F gas.

[0043] F2 gas (fluoride gas) is a very expensive gas produced by electrolysis of hydrogen fluoride, and the cost of ultra-high purity hydrogen fluoride varies depending on how effectively it is used.

[0044] Previously, JP2005-281048 proposed a method of purifying hydrogen fluoride after mixing it with F2 gas for 5 minutes or more. However, this method is limited to a batch process and is not suitable for purifying hydrogen fluoride in a continuous process. Even if this method is applied, there is a risk of excessive use of F2 gas.

[0045] The present invention applies F2 gas to a continuous process and designs the most effective feeding method by applying the APC module of the advanced process control unit 500 described below. F2 gas is mixed with an inert gas and the amount of F2 gas fed is determined according to the AsF3 concentration in the crude hydrogen fluoride to be purified.

[0046] The F gas supplied from the gas supply unit 300 undergoes an oxidation reaction with AsF, which has a high boiling point, in the crude hydrogen fluoride, to be converted into AsF, which has a low boiling point, and is removed in gas form at the top of the tower. In addition to this reaction, the F gas also undergoes an ionic reaction with HF, which is present together with AsF, to be converted into HAsF, which has a high boiling point, and can be easily removed at the bottom of the tower.

[0047] Most of the impurities contained in crude hydrogen fluoride are divided into those with lower and higher boiling points than hydrogen fluoride, and as such, most can be removed during the distillation process using a multi-stage distillation column, but trivalent arsenic fluoride (AsF3) is particularly difficult to remove. AsF3 (bp = 62.8°C), which is contained in extremely small amounts in high-purity hydrogen fluoride, has a high boiling point of its own, but forms a complex with hydrogen fluoride, lowering its boiling point and making it similar to hydrogen fluoride or forming an azeopropic point with it, making separation extremely difficult.

[0048] When F2 gas is injected to remove trivalent arsenic fluoride, which is the most problematic impurity contained in hydrogen fluoride, an oxidation reaction occurs as shown in the following reaction formula.

[0049] [Reaction Scheme 1] AsF3+F2→AsF5 [Reaction Scheme 2] AsF5+HF→HAsF6 Through the oxidation reaction, trivalent arsenic fluoride AsF3 reacts with F2 gas to be converted to pentavalent arsenic fluoride AsF5. This pentavalent arsenic fluoride has a boiling point difference of -52.8°C from that of hydrogen fluoride (19.5°C), making it possible to separate it through a distillation process. It also reacts with HF to form a high-boiling point complex, making separation even easier.

[0050] In practice, the AsF content in the crude hydrogen fluoride fed into the first multi-stage distillation column is at the ppm level, and if pure 100% F gas is used, the difference in boiling point between F gas and hydrogen fluoride is so great that it is difficult to achieve sufficient reaction conditions, which significantly increases process costs. Therefore, in the present invention, a mixed gas in which F gas is diluted with an inert gas is used to achieve low cost and high efficiency.

[0051] When crude hydrogen fluoride in a liquid or gaseous state is introduced into the first multi-stage distillation column, it is converted to a gaseous state by a reboiler. At this time, the crude hydrogen fluoride in a gaseous state comes into contact with F2 gas, i.e., an oxidation reaction occurs due to gas-gas contact. Also, the crude hydrogen fluoride in a liquid state comes into contact with F2 gas, i.e., an oxidation reaction occurs due to liquid-gas contact. These two reactions occur simultaneously, maximizing the oxidation reaction shown in Reaction 1 above.

[0052] F2 gas is fed into the multi-stage distillation column into which crude hydrogen fluoride is fed, or additionally into all remaining multi-stage distillation columns. Since the arsenic fluoride content in each multi-stage distillation column is different, in order to ensure the best effect with a small amount, F2 gas is diluted to a predetermined concentration according to the content of the remaining arsenic fluoride and fed into the multi-stage distillation column.

[0053] The inert gas in the gas stream of the present invention is one or more of He, N2, and Ar, and preferably N2 is used.

[0054] The F2 gas:inert gas ratio in the gas stream can be adjusted to various concentrations within a range of 10:90 to 90:10 wt. As the F2 gas content increases, the possibility of AsF3 participating in the oxidation reaction to AsF5 increases. However, considering the residence time of crude hydrogen fluoride in the multi-stage distillation column, there is a limit to the contact between AsF3 and F2 gas. Therefore, from a cost perspective, it is preferable to adjust the F2 gas content according to the concentration of impurities in the crude hydrogen fluoride.

[0055] The F2 gas and the inert gas in the gas stream are either fed simultaneously into the multi-stage distillation column or mixed together beforehand and fed in the form of a mixed gas.

[0056] In one embodiment, when the AsF content in the hydrogen fluoride that has passed through the first multi-stage distillation column is 100 ppm or more, the concentration of the F gas to be introduced is set to 0.1 to 0.2%, and when the AsF content is 10 to 100 ppb, the concentration is set to 0.005 to 0.01%.

[0057] The recovery unit 400 is a device for recovering the ultra-high purity hydrogen fluoride purified by passing through the distillation purification unit 200. After passing through the final multi-stage distillation column, the ultra-high purity hydrogen fluoride is recovered in a gaseous state or in a liquid state liquefied through a condenser.

[0058] The purification of crude hydrogen fluoride into ultra-high purity hydrogen fluoride by the raw material supply unit 100, distillation purification unit 200, gas supply unit 300, and recovery unit 400 is automatically controlled by an advanced process control unit 500 to enable continuous process control.

[0059] The advanced process control unit 500 is a device including an advanced process control (hereinafter referred to as "APC") module.

[0060] The APC module is a multivariable predictive control technology that is composed of a mathematical model that simultaneously considers the dynamic relationships between many process operation variables and controls to maintain stable, economical, and optimal operating conditions.The APC module is not a factory equipment reinforcement, but a technology that uses software to improve the efficiency and operational convenience of the entire factory.

[0061] By controlling the refining process from crude hydrogen fluoride to ultra-high purity hydrogen fluoride with the APC module, product yield can be improved and upgraded, reducing operating costs and giveaways. In addition, even if the quality of crude hydrogen fluoride used as a raw material varies, the quality of the final ultra-high purity hydrogen fluoride can be made uniform, improving operational flexibility. At the same time, by increasing process efficiency, it is possible to increase production and processing volume while also generating benefits such as reduced energy consumption.

[0062] Due to the nature of chemical processes, when manipulating a control variable, multiple conditions must be considered simultaneously, rather than just one objective variable. This requires knowledge of the correlation between the control variables and objective variables required for operation. A dynamic model expressing this correlation is included within the APC module, enabling computer-based multi-variable predictive control (MPC) technology to control the process more stably and economically. MPC simultaneously considers the effects of various control variables on other control variables and controls them to achieve their respective target values. Operational data is used to create a dynamic model that expresses the relationship between the process's manipulated variables (input variables, control variables, and disturbance variables) and the control variables (output variables). This dynamic model can then be used to predict and control the future behavior of the manipulated variables and control variables.

[0063] In constructing the purification method and apparatus of the present invention, the most significant variable in process control by the APC module is the concentration of impurities.

[0064] The raw material supply unit 100 receives an open / close signal from the advanced process control unit 500, and supplies crude hydrogen fluoride to the multi-stage distillation column when the distillation purification unit 200 is in the open state. The hydrogen fluoride purified by the multi-stage distillation column is continuously transported to the next multi-stage distillation column via a transfer line. A gas stream is supplied from the gas supply unit 300 to the multi-stage distillation column to remove impurities.

[0065] In this step, whether or not the gas stream is treated, the concentration of the gas stream to be treated, the injection amount of the gas stream, etc. vary depending on the contents of impurities in the crude hydrogen fluoride and hydrogen fluoride present in the multi-stage distillation column. The contents of the impurities can be obtained by measuring the concentrations of the impurities present in the multi-stage distillation column.

[0066] For concentration analysis, each of these is equipped with a sensor for measuring concentration, which is displayed on a display connected to the advanced process control unit 500 via an analysis device.

[0067] The concentration analysis method is classified according to the type of impurity and is measured by one or more analytical instruments, and is not particularly limited in the present invention.

[0068] Metallic impurities are analyzed using special equipment that can be pre-treated to a uniform concentration without impurity contamination, taking into consideration the equipment damage caused by inductively coupled plasma mass spectrometry. Water and ionic impurities are analyzed precisely using FT-IR, and gaseous impurities are analyzed using GC.

[0069] A gas stream appropriate for the impurity concentration is designed, the measured impurity concentration is sent to the APC module, and the composition of the gas streams when the primary gas stream, secondary gas stream, and n-th gas stream are input, as well as the injection amount during treatment, are changed according to the set value of the impurity concentration. By using such a change method, even if the quality of the crude hydrogen fluoride used as a raw material varies, the final hydrogen fluoride can be obtained as an ultra-high purity substance of uniform quality.

[0070] In particular, the purification method and apparatus according to the present invention are capable of continuous processing, and by controlling the process with an APC module, 24-hour operation under automatic control is possible, which has the advantage of improving the production and processing volume of ultra-high purity hydrogen fluoride at low cost.

[0071] Using the above-described configuration, the process for producing ultra-high purity hydrogen fluoride according to the present invention will be described in detail with reference to the drawings.

[0072] Although not shown, each of the above devices may additionally include a flow regulator, pressure controller, compressor, cooler, condenser, storage tank, supply amount control valve, gas-liquid separator, flow meter, analyzer, analytical sample collection device, leak preventer, liquid or gas transfer pump, exhaust device, overpressure prevention device, automation device, various sensors, thermometer, mass meter, pressure meter, volume measuring device, etc.

[0073] 2 is a schematic diagram showing an apparatus for producing ultra-high purity hydrogen fluoride according to one embodiment of the present invention. Although three multi-stage distillation columns are shown, this is merely an example for the purpose of explanation, and the number and arrangement of the multi-stage distillation columns for application to an actual process can be variously modified.

[0074] The process will be explained below.

[0075] The crude hydrogen fluoride as a raw material is transferred from the crude hydrogen fluoride storage tank 110 to the bottom of the first distillation column 210 via a transfer line 122 by pumping with a transfer pump (not shown) or by pressurizing with an inert gas.

[0076] The crude hydrogen fluoride in the crude hydrogen fluoride storage tank 110 is introduced into the first distillation column 210 in a liquid state, or in a gaseous state after passing through an evaporator 600 and introduced into the first distillation column 210. The introduction of gaseous crude hydrogen fluoride using the evaporator 600 has the effect of removing impurities, since high concentrations of impurities remain in the lower part of the evaporator 600.

[0077] The crude hydrogen fluoride fed into first distillation column 210 undergoes fractional distillation, and low-boiling and high-boiling impurities are discharged along discharge lines 218 and 219 at the top and bottom regions, respectively. The gas discharged from first distillation column 210 passes through cooler C1 and recovery vessel R1, and the hydrogen fluoride from which the impurities have been primarily removed is transported to second distillation column 220 along transfer line 212. At this time, the impurities supplied from first distillation column 210 pass through cooler C1 and recovery vessel R1 and are then discharged via discharge line 218 at the top of the column.

[0078] In the first distillation column 210, most of the impurities in the crude hydrogen fluoride, such as SO2, AsF3, BF3, PF5, SiF4, FeF3, and SF6, are removed by fractional distillation.

[0079] Among these, in order to remove AsF3 which is difficult to separate, a mixed gas of F2 gas / inert gas, that is, a gas stream, is injected from the gas stream storage tank 310 to carry out an oxidation reaction.

[0080] The gas stream can be injected either downwards, from the top to the bottom, or upwards, from the bottom to the top. These methods vary depending on the equipment process, and are chosen in a way that maximizes the contact opportunity between the crude hydrogen fluoride and F2 gas. For convenience, Figure 2 shows the downward injection method.

[0081] The introduction of F2 gas / inert gas into the gas stream is carried out by measuring the removal concentration of AsF3 contained in the crude hydrogen fluoride in the first distillation column using the APC module.

[0082] That is, the concentration of AsF3 contained in the hydrogen fluoride that has passed through the first distillation column 210 is measured, and the concentration of F2 gas introduced into the first distillation column is controlled to minimize this concentration.

[0083] Figure 3 shows the procedure for controlling the F2 gas concentration by the APC module.

[0084] Referring to FIG. 3, crude hydrogen fluoride and F2 gas are introduced into a first distillation column 210.

[0085] In setting up the APC module in this process, the manipulated variable is the concentration of F2 gas fed into the first distillation column 210, and the controlled variable is set to the content of AsF3 passing through the first distillation column 210, and a set of optimized steady state values ​​for these two is calculated by simulation or the like.

[0086] Next, the content of AsF3 in the hydrogen fluoride that has passed through the first distillation column 210 is measured. The content of AsF3 is measured at either an outlet located at the connection point between the first distillation column 210 and the transfer line 212 or at a point on the transfer line 212. At this time, the measurement can be performed using an inductively coupled plasma mass spectrometer or the like after pre-treatment for analysis.

[0087] The measured AsF3 content is returned to the APC module, and if it is below the set value (YES), the process continues.

[0088] If the measured value is higher than the set value (NO), the APC module adjusts the concentration of F2 gas fed to first distillation column 210. In response to a signal from the APC module, a flow controller (not shown) adjusts the flow rates of F2 gas storage tank 301 and inert gas storage tank 302 connected to gas stream mixer 310 fed to first distillation column 210, and feeds the gas to gas stream mixer 310. At this time, the APC module may previously store a data table obtained through experiments or simulations, an algorithm for calculating a flow control value, etc., before the concentration value is transmitted and input as a flow control value.

[0089] In this manner, the APC module optimizes the manipulated variables to be compatible with the set of steady-state values, taking into account parameters including the setpoints of the control variables, hi / lo limits, and system disturbances, to perform the distillation process in the first distillation column.

[0090] As a result, the APC module allows for immediate, active, and rapid response to continuous changes in the concentration of AsF3 in the hydrogen fluoride during the process, relative to the concentration of the injected F2 gas.

[0091] The first distillation column 210 is operated under the following conditions: a pressure of 0.1 to 3 bar, a temperature of 10 to 60°C, and a residence time of 1 to 30 minutes. In the present invention, crude hydrogen fluoride is directly introduced into the distillation column without pretreatment, and therefore the process conditions in the first distillation column 210 are different from those in the other distillation columns.

[0092] The introduction of F2 gas causes oxidation reactions between crude hydrogen fluoride and F2 gas through gas-gas contact and liquid-gas contact in first distillation column 210, maximizing the effect of introducing F2 gas. This technology has the advantage of allowing liquid-gas contact to occur simultaneously, maximizing the oxidation reaction, unlike when F2 gas is introduced to remove AsF3 from gaseous hydrogen fluoride, which only undergoes oxidation reactions through gas-gas contact.

[0093] Meanwhile, although not shown in Figure 3, when a top injection method is used, an injection nozzle (not shown) is arranged so that the gas stream can be injected from bottom to top. The gas stream injected from the injection nozzle (not shown) has the advantage that the injection pressure increases as it increases from bottom to top. The F2 gas in the gas stream injected from the injection nozzle (not shown) increases its contact opportunity with the liquid crude hydrogen fluoride that falls from top to bottom due to gravity as it is injected from bottom to top, further enhancing the purification effect of the injection of the F2 gas.

[0094] Next, the hydrogen fluoride that has completed the primary distillation and oxidation steps is fed into the second distillation column 220 for secondary distillation.

[0095] The hydrogen fluoride fed into second distillation column 220 undergoes fractional distillation, and high-boiling-point impurities are discharged from the bottom of the column along discharge line 229. After passing through cooler C2 and recovery vessel R2, the purified hydrogen fluoride is fed into third distillation column 230, and low-boiling-point impurities are discharged from the top of the column via discharge line 228. At this time, a portion of the hydrogen fluoride is recovered and circulated in second distillation column 220.

[0096] Next, the hydrogen fluoride that has completed the secondary distillation step is introduced into the middle region of the third distillation column 230 for tertiary distillation.

[0097] The hydrogen fluoride introduced into third distillation column 230 undergoes fractional distillation, with high-boiling-point impurities being discharged along discharge line 239 in the column bottom region. After hydrogen fluoride and low-boiling-point impurities pass through cooler C3 and recovery vessel R3, the hydrogen fluoride is finally transported to ultra-high purity hydrogen fluoride storage tank 410 via storage line 422, and the low-boiling-point impurities are discharged via discharge line 238 at the column top. At this time, a portion of the hydrogen fluoride is recovered and circulated in third distillation column 230.

[0098] The ultra-high purity hydrogen fluoride from which the impurities have been removed in the third distillation column 230 is transported to the ultra-high purity hydrogen fluoride storage tank 410 along a storage line 422 by gravity due to a difference in height.

[0099] The ultra-high purity hydrogen fluoride storage tank 410 is filled with ultra-high purity hydrogen fluoride containing impurities at a ppq level, and the ultra-high purity hydrogen fluoride is stored in a liquid state at a storage temperature below the boiling point.

[0100] As explained above, F2 gas can be injected not only into the first multi-stage distillation column into which crude hydrogen fluoride is introduced, but also into the remaining multi-stage distillation columns, thereby further enhancing the purification effect of hydrogen fluoride.

[0101] According to another embodiment of the present invention, a method and apparatus for purifying ultra-high purity hydrogen fluoride are presented.

[0102] FIG. 4 is a schematic diagram showing an apparatus for producing ultra-high purity hydrogen fluoride according to another embodiment of the present invention.

[0103] Referring to Figure 4, additional gas stream mixers 310, 320, and 330 are connected to the first distillation column 210, the second distillation column 220, and the third distillation column 230, respectively. These are connected to an F gas storage tank (not shown) and an inert gas storage tank (not shown), respectively, as in Figure 2. The F gas / inert gas storage tanks are connected to the APC module along with respective flow valves and flow controllers for flow control. Although not separately shown, the F gas and inert gas may be supplied independently or connected to a single storage tank, and the inert gas is supplied via respective supply lines L1, L2, and L3, and the F gas is supplied via respective supply lines M1, M2, and M3.

[0104] In FIG. 4, hydrogen fluoride passed through the first distillation column 210 is transported via a transfer line 212 to a second distillation column 220 where it undergoes a distillation process, and is then transported via a transfer line 222 to a third distillation column 230 where it undergoes a continuous distillation process.

[0105] At this time, the first distillation column 210 measures the AsF content in the crude hydrogen fluoride supplied from the transfer line 212 and applies a signal to the APC module. If the AsF content exceeds a set value, the APC module controls the flow valves of the F gas supply line M1 and the inert gas supply line L1 to adjust the concentration of the F gas in the first gas stream mixer 310. The gas stream having the adjusted concentration is introduced into the first distillation column 210 to carry out a reaction process.

[0106] This process is similarly carried out in the second distillation column 220 and the third distillation column 230.

[0107] When F2 gas is introduced into the first distillation column 210, the second distillation column 220, and the third distillation column 230, an oxidation reaction occurs through a gas-gas contact reaction with gaseous hydrogen fluoride gas. To enhance the oxidation reaction, vortex generators (not shown) capable of forming vortices are installed inside the first distillation column 210, the second distillation column 220, and the third distillation column 230, or the gas stream injection method is changed to maximize the oxidation reaction.

[0108] The process for purifying ultra-high purity hydrogen fluoride according to the present invention is carried out with a continuous supply of raw materials and gas streams, and the process can be continuously repeated until it is interrupted due to the need to stop the flow of hydrogen fluoride when inspection of the production equipment or PM is required.

[0109] Furthermore, by using crude hydrogen fluoride produced by the reaction of fluorite with sulfuric acid without pre-treating the hydrogen fluoride conventionally used as a raw material, the process is simplified and the pre-treatment costs are reduced.

[0110] In addition, even if the composition or content of impurities in crude hydrogen fluoride is not constant, ultra-high purity hydrogen fluoride can be produced with high efficiency.The moisture concentration of the ultra-high purity hydrogen fluoride produced in this way is minimized, which has the advantage of being very stable.

[0111] The ultra-high purity hydrogen fluoride recovered by the present invention has a hydrogen fluoride impurity (especially arsenic fluoride) content at the ppq level, and is suitable for use in fields requiring high-purity hydrogen fluoride and hydrofluoric acid, such as etching and cleaning of semiconductors and displays.

[0112] [Example] Examples of the present invention will be described in detail below, but the present invention is not limited to these examples.

[0113] Example 1 As the continuous multi-stage distillation column, an apparatus in which three multi-stage distillation columns were connected in series, as shown in Figure 1, was used.

[0114] Crude hydrogen fluoride was purchased as a raw material from Company A in China and continuously supplied to the first distillation column at a rate of 2.19 tons / hour, where fractional distillation was carried out.

[0115] The temperature at the bottom of the column was set to 32°C, the temperature at the top to 30°C, and continuous distillation was carried out under the conditions of a pressure at the top of the column of 0.5 bar and a reflux ratio of 1:3. At this time, a 90:10% F2 / N2 mixed gas was continuously supplied to the bottom of the first distillation column at 1 kg / hour to carry out the oxidation reaction, and low-boiling and high-boiling impurities were continuously extracted at 0.066 ton / hour.

[0116] The hydrogen fluoride that had been oxidized and purified at the top of the column and then cooled was transferred to the second distillation column side via a transfer line at a rate of 2.124 tons / hour.

[0117] At this time, the operating conditions of the second distillation column were the same as those of the first distillation column, and low-boiling and high-boiling impurities were continuously extracted at 0.044 ton / hour.

[0118] The hydrogen fluoride that passed through the second distillation column was supplied to the third distillation column at a rate of 2.08 tons / hour for fractional distillation. The operating conditions of the distillation column were the same as those of the first distillation column, and low-boiling and high-boiling impurities were continuously extracted at a rate of 0.043 tons / hour.

[0119] The hydrogen fluoride that passed through the third distillation column was continuously stored in a storage tank via a transfer line at a rate of 2.037 tons / hour.

[0120] Under these conditions, continuous operation was carried out over an extended period of time, and the amount of ultra-high purity hydrogen fluoride produced per hour was extremely stable at 2.037 tons, 2.037 tons, 2.037 tons, 2.037 tons, 2.037 tons, and 2.037 tons after 500 hours, 2000 hours, 4000 hours, 5000 hours, and 6000 hours.

[0121] Example 2 The same steps as in Example 1 were carried out, and the crude hydrogen fluoride was passed through an evaporator before being introduced into the first distillation column, and was introduced into the first distillation column in a gaseous state.

[0122] Example 3 The same process as in Example 1 was carried out, and mixed gases of F2 / N2 gas with a ratio of 4:6% and 2:8% were supplied to the second and third distillation columns at 1 kg / hour, respectively.

[0123] Comparative Example 1 Hydrogen fluoride was purified in the same manner as in Example 1, without injecting F2 / N2 gas.

[0124] Comparative Example 2 The same procedure as in Example 3 was carried out, except that F2 / N2 gas was injected only into the second and third distillation columns, excluding the first distillation column, to purify hydrogen fluoride.

[0125] Test Example 1 The impurity contents of the hydrogen fluoride purified in the Examples and Comparative Examples were measured, and the results are shown in Table 1. After pretreatment, the impurities were diluted with ultrapure water to a 49% hydrofluoric acid state, and then measured using ion chromatography mass spectrometry and inductively coupled plasma mass spectrometry.

[0126] [Table 1] Referring to the table above, it can be seen that when a gas stream of F gas / inert gas is injected into a multi-stage distillation column into which crude hydrogen fluoride has been introduced and treated according to the present invention, the final hydrogen fluoride contains F at a level of less than ppt, i.e., at a ppq level.

[0127] Furthermore, in the case of Comparative Examples 1 and 2, the results after purification using the third distillation column showed that the contents of B, Ti, Ca, and Fe could be reduced to some extent, but the As content was very high, and it was found that in order to remove As, it was preferable to proceed with the steps of Examples 1 to 3.

[0128] In particular, in Examples 1 to 3, by injecting F2 gas / inert gas into the first multi-stage distillation column, the As content was found to be significantly reduced compared to Comparative Examples 1 and 2. In addition, the best test results were obtained when gas streams were injected into the second and third distillation columns, as in Example 3. [Explanation of symbols]

[0129] 100: Raw material supply department 200: Distillation and purification department 300: Gas supply unit 400: Recovery Department 500: Advanced Process Control Department 600: Evaporator 110: Crude hydrogen fluoride storage tank 122: Raw material conveying line 210: First distillation tower 220: Second distillation column 230: Third distillation column 218, 219, 228, 229, 238, 239: Discharge lines 301: F2 gas storage tank 302: Inert gas storage tank 310: First gas stream mixer 320: Second gas stream mixer 330: Third gas stream mixer 410: Ultra-high purity hydrogen fluoride storage tank 422: Storage line C1, C2, C3: Cooler R1, R2, R3: Recoverer L1, L2, L3: Inert gas supply lines M1, M2, M3: F2 gas supply lines [Industrial Applicability]

[0130] According to the present invention, the recovered hydrogen fluoride is ultra-high purity hydrogen fluoride having an impurity content (particularly arsenic fluoride) at the ppq level, and is preferably applicable to fields requiring high-purity hydrogen fluoride and hydrofluoric acid, such as etching and cleaning of semiconductors and displays.

Claims

1. providing crude hydrogen fluoride from a raw material supply unit, the crude hydrogen fluoride being produced by a reaction between fluorite and sulfuric acid and not subjected to a pretreatment step; a step of carrying out a continuous distillation step in which the crude hydrogen fluoride in a liquid state or a gaseous state is supplied to a multi-stage distillation column, fractional distillation is carried out in the distillation column, impurities other than hydrogen fluoride are removed from the top or bottom of the column based on the difference in boiling point, and the distilled hydrogen fluoride is transported to a subsequent multi-stage distillation column; AsF in the impurities is introduced into the multi-stage distillation column into which the crude hydrogen fluoride is introduced. ３ F for removal of ２ injecting a gas stream comprising a gas and an inert gas; The concentration of F 2 gas in the gas stream is determined by the concentration of AsF contained in the hydrogen fluoride gas that has passed through the multi-stage distillation column. ３ is adjusted according to the analytical value of the concentration of Additionally, the F ２ a gas stream containing the gas and the inert gas is also injected into another multi-stage distillation column into which the crude hydrogen fluoride is not introduced.

2. 2. The method for purifying ultra-high purity hydrogen fluoride according to claim 1, wherein the crude hydrogen fluoride is introduced in a liquid state or in a gaseous state after passing through an evaporator.

3. The gas stream may comprise F ２ 2. The method for purifying ultra-high purity hydrogen fluoride according to claim 1, wherein the gas:inert gas is contained in a ratio of 10:90 to 90:10 by weight.

4. The inert gas is He, N ２ 2. The method for purifying ultra-high purity hydrogen fluoride according to claim 1, wherein the hydrogen atom is one or more elements selected from the group consisting of:

5. AsF in the ultra-high purity hydrogen fluoride ３ The method for purifying ultra-high purity hydrogen fluoride according to claim 1, wherein

6. The method for purifying ultra-high purity hydrogen fluoride according to claim 1, wherein the gas stream is additionally injected into the remaining multi-stage distillation column.

7. A raw material supply unit for supplying crude hydrogen fluoride raw material, wherein the crude hydrogen fluoride is produced by reacting fluorite with sulfuric acid and is not subjected to a pretreatment process; A distillation purification unit equipped with a plurality of multi-stage distillation columns for performing a continuous distillation process; F in the multi-stage distillation column ２ a gas supply for supplying a gas stream comprising the gas and an inert gas; a recovery section for recovering ultra-high purity hydrogen fluoride; Equipped with an advanced process control unit for process control that enables continuous processes, The advanced process control unit detects AsF contained in the hydrogen fluoride gas that has passed through the multi-stage distillation column. ３ adjusting the concentration of F 2 gas in the gas stream to be supplied to a multi-stage distillation column into which crude hydrogen fluoride has been introduced, in accordance with the concentration measured using the analytical instrument of Additionally, the F ２ The gas stream containing the gas and the inert gas is also injected into other multi-stage distillation columns into which the crude hydrogen fluoride is not introduced.

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