Method for preparing ultra-pure hydrofluoric acid by adopting heterogeneous flow

Abstract

The invention discloses a method for preparing ultra-pure hydrofluoric acid by adopting heterogeneous flow, which refers to a rectification technology, adopts a non-hydrogen fluoride substance to artificially manufacture an ultra-pure heterogeneous flow dielectric film layer, forms a gas-liquid exchange layer, purifies hydrogen fluoride gas, and meanwhile, adopts the synergistic effect of three specific chemical reagents before impurity removal by adopting heterogeneous flow to prepare ultra-pure hydrofluoric acid. The concentration of the superoxide in the water is improved in a phase-changing manner, the superoxide metastable state is maintained and improved, the problem that the superoxide cannot be effectively and fully contacted with the impurity arsenic trifluoride existing in a trace state when the dissolving capacity of the superoxide in the water is low is solved, and a foundation is laid for heterogeneous flow impurity removal. Compared with the prior art, the method has the advantages of being low in equipment requirement, high in production efficiency, energy-saving, environment-friendly and the like, the product meets or even exceeds the requirement of the SEMI C12 standard, and the method can be used for industries such as integrated circuits.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of purification of ultra-clean high-purity electronic chemicals, and in particular to a method for preparing ultra-high-purity hydrofluoric acid by using heterogeneous flow, which can be applied in the preparation of other ultra-high-purity reagents, semiconductor integrated circuit manufacturing, display manufacturing, semiconductor light emitting manufacturing, solar cell manufacturing, etc. BACKGROUND

[0002] With the rapid development of the integrated circuit industry in China, ultra-clean high-purity electronic chemicals, as a key technical material for chip manufacturing, directly affect the electrical performance, yield and reliability of the chip. The main material of the chip is silicon, and hydrofluoric acid is one of the essential chemicals for silicon etching and cleaning. Therefore, ultra-high-purity hydrofluoric acid is one of the commonly used ultra-clean high-purity electronic chemicals in the integrated circuit industry. The main difficult-to-remove impurity in ultra-high-purity hydrofluoric acid is arsenic, which mainly exists in the form of arsenic trifluoride. Arsenic trifluoride can form an azeotrope with anhydrous hydrogen fluoride, so it cannot be removed by general methods such as distillation, gas washing purification, etc. At the same time, the distillation process requires industrial anhydrous hydrogen fluoride to be heated to 110℃, but the permeation of hydrogen fluoride is relatively strong, which shortens the service life of the graphite heat exchanger used for heating and increases the energy consumption. If the gas washing purification process is used, the material will short circuit in a certain period of time, and the product index cannot be reached.

[0003] In addition, Chinese patent CN108862200B discloses a preparation method of ultra-high-purity hydrofluoric acid, comprising the following steps:

[0004] (1) vaporize anhydrous hydrogen fluoride and add fluorine-containing gas to obtain a first mixed gas; wherein the fluorine-containing gas contains one or more of fluorine gas, nitrogen trifluoride and oxygen difluoride; (2) pass the first mixed gas into a plasma generating device to convert the impurity arsenic trifluoride contained in the first mixed gas into arsenic pentafluoride to obtain a second mixed gas; (3) wash the second mixed gas through an aqueous solution containing metal fluoride to obtain purified hydrogen fluoride, wherein the temperature of the aqueous solution is controlled at 22-90℃, and the arsenic pentafluoride in the second mixed gas is converted into arsenate and retained in water during the washing process; (4) selectively repeat steps (2) and (3) to obtain ultra-high-purity hydrogen fluoride, wherein the concentration of each anion except fluorine is less than 50ppb, and the concentration of each cation except hydrogen is less than 10ppt; (5) dissolve the ultra-high-purity hydrogen fluoride in water, filter, and obtain ultra-high-purity hydrofluoric acid. In the technical solution of this patent, the plasma generated by the discharge of the plasma generating device is used to promote the digestion of impurities including arsenic trifluoride, which has relatively high operation requirements, and general enterprises may not have the production conditions. SUMMARY

[0005] The present application aims at overcoming one or more of the deficiencies in the prior art and providing a method for preparing ultra-high purity hydrofluoric acid with reduced equipment requirements, energy saving, reduced exhaust emission, improved production efficiency and continuous production.

[0006] To achieve the above-mentioned purposes, the technical solution adopted by the present application is:

[0007] A method for preparing ultra-high purity hydrofluoric acid by using heterogeneous flow, wherein the mass content of each metal cation in the ultra-high purity hydrofluoric acid is below 10 ppt, and the mass content of each anion except fluoride ion is below 50 ppb, the method uses anhydrous hydrogen fluoride as raw material, and the anhydrous hydrogen fluoride contains impurities including arsenic trifluoride;

[0008] The method comprises:

[0009] Step (1): adding the anhydrous hydrogen fluoride into a pretreatment tank containing pure water, adding a super-oxidizing agent, a complexing agent and a stabilizer for impurity removal treatment to obtain pretreated anhydrous hydrogen fluoride;

[0010] The stabilizer is a fluoride salt of a metal whose valence state can be changed; the super-oxidizing agent can oxidize the arsenic trifluoride into arsenic pentafluoride and can change the metal ion in the stabilizer from the current valence state to a higher valence state with oxidation ability; the complexing agent can stabilize the metal ion; wherein during the impurity removal treatment, the arsenic pentafluoride can be partially or completely changed into an arsenic fluoide salt;

[0011] Step (2): evaporating the pretreated anhydrous hydrogen fluoride to form a to-be-treated gas flow, sequentially passing through a mist removal layer and a heterogeneous flow purification layer to obtain ultra-high purity hydrogen fluoride; the mass content of each metal cation in the ultra-high purity hydrogen fluoride is below 10 ppt, and the mass content of each anion except fluoride ion is below 50 ppb;

[0012] In the heterogeneous flow purification layer, the separation and purification are performed at the gas-liquid exchange interface formed between the heterogeneous flow formed by the flow of a liquid other than hydrogen fluoride and the to-be-treated gas flow;

[0013] Step (3): absorbing the ultra-high purity hydrogen fluoride with pure water and / or hydrofluoric acid to obtain ultra-high purity hydrofluoric acid.

[0014] In the present application, the pretreatment tank is mainly used for arsenic removal by oxidation, i.e. oxidizing trivalent arsenic in the anhydrous hydrogen fluoride into pentavalent arsenic and further ionizing and solidifying the trivalent arsenic to break the azeotropic property of arsenic trifluoride and hydrogen fluoride.

[0015] According to some preferred and specific aspects of the present application, in the step (1), the super-oxidizing agent is a combination of one or more selected from the group consisting of fluorine gas, a mixture of fluorine gas and nitrogen gas, dioxygen difluoride, a mixture of dioxygen difluoride and nitrogen gas, ozone, fluorine radical, and oxygen radical.

[0016] In some embodiments of the present application, when the super-oxidizing agent is a mixture of fluorine gas and nitrogen gas, the volume ratio of fluorine gas to nitrogen gas is 0.5-25:100.

[0017] In some embodiments of the present application, when the super-oxidizing agent is a mixture of dioxygen difluoride and nitrogen gas, the volume ratio of dioxygen difluoride to nitrogen gas is 0.5-2.5:100.

[0018] In some embodiments of the present application, when the super-oxidizing agent is a fluorine radical, the fluorine radical is prepared by discharging a gas selected from the group consisting of fluorine gas, fluorine-nitrogen gas, and dioxygen difluoride through a barrier medium to form a gas containing fluorine radical.

[0019] In some embodiments of the present application, when the super-oxidizing agent is an oxygen radical, the oxygen radical is prepared by discharging a gas selected from the group consisting of ozone, oxygen gas, and water vapor through a barrier medium to form a gas containing oxygen radical.

[0020] According to some preferred and specific aspects of the present application, in the step (1), the complexing agent is a combination of one or more selected from the group consisting of ferric humate, tartaric acid, phenol, and P53 protein.

[0021] According to some preferred and specific aspects of the present application, in the step (1), the stabilizing agent is a fluorinated salt of one metal selected from the group consisting of sodium, potassium, iron, nickel, manganese, cobalt, and copper, or a combination of fluorinated salts of several metals selected from the group consisting of sodium, potassium, iron, nickel, manganese, cobalt, and copper.

[0022] According to some preferred aspects of the present application, in the step (1), the pure water, the complexing agent, and the stabilizing agent form a mixed solution, and the mixed solution, the anhydrous hydrogen fluoride, and the super-oxidizing agent form a pretreatment reaction system.

[0023] In the process of the impurity removal treatment, the temperature of the pretreatment reaction system is controlled to be -10-110°C, and the impurity removal time is controlled to be 0.01-1800 min.

[0024] Further, in the process of the impurity removal treatment, the temperature of the pretreatment reaction system is controlled to be 5-110°C, and the impurity removal time is controlled to be 0.01-180 min.

[0025] Still further, in the process of the impurity removal treatment, the temperature of the pretreatment reaction system is controlled to be 10-108°C, and the impurity removal time is controlled to be 0.01-60 min.

[0026] In some embodiments of the present application, during the impurity removal process, the temperature of the pretreatment reaction system is controlled to be 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 108°C, etc.

[0027] In some embodiments of the present application, during the impurity removal process, the impurity removal time of the pretreatment reaction system is controlled to be 0.01-40 min, for example, it can be 10 s, 15 s, 20 s, 30 s, 40 s, 1 min, 2 min, 4 min, 5 min, 7 min, 9 min, 10 min, 12 min, 15 min, 16 min, 18 min, 20 min, 22 min, 25 min, 28 min, 30 min, 32 min, 35 min, etc.

[0028] In some embodiments of the present application, during the impurity removal process, the mass percentage content of the anhydrous hydrogen fluoride in the pretreatment reaction system is always controlled to be greater than or equal to 0.001% and less than 100%.

[0029] In some embodiments of the present application, during the impurity removal process, the mass percentage content of the anhydrous hydrogen fluoride in the pretreatment reaction system is always controlled to be greater than or equal to 10% and less than 100%, or greater than or equal to 20% and less than 100%, or greater than or equal to 40% and less than 100%, or greater than or equal to 60% and less than 100%, or greater than or equal to 80% and less than 100%.

[0030] According to some preferred aspects of the present application, in process (1), the addition amount of the complexing agent and the addition amount of the stabilizer are independently controlled with their respective mass concentrations in the mixed solution of the pretreatment reaction system being 0.01%-3%.

[0031] According to some preferred aspects of the present application, in process (1), during the impurity removal process, the molar ratio of the superoxidizing agent to the anhydrous hydrogen fluoride is controlled to be 0.01-2.5:100.

[0032] In the present application, the method of the present application can be a continuous process, and the evaporation temperature in process (2) can be the temperature of the impurity removal process in process (1), which is actually performed simultaneously. Of course, in some other embodiments, it can also be performed intermittently, and the evaporation temperature in process (2) can also be controlled to be the temperature of the impurity removal process in process (1).

[0033] According to some preferred aspects of the present application, in step (2), the non-hydrogen fluoride liquid fluid is one or a combination of several selected from the group consisting of pure water, hydrofluoric acid, hydrogen peroxide, sulfuric acid, and phosphoric acid.

[0034] In some embodiments of the present application, when the non-hydrogen fluoride liquid fluid is hydrofluoric acid, the mass percentage concentration of hydrogen fluoride in the hydrofluoric acid used is 0.001%-99.9%, for example, it can be 1%-90%, or it can be 10%-80%.

[0035] In some embodiments of the present application, when the non-hydrogen fluoride liquid fluid is hydrogen peroxide, the mass percentage concentration of hydrogen peroxide in the hydrogen peroxide used is 0.001%-50%, for example, it can be 1%-45%, or it can be 10%-40%.

[0036] In some embodiments of the present application, when the non-hydrogen fluoride liquid fluid is sulfuric acid, the sulfuric acid used is an aqueous solution of sulfuric acid, and the mass percentage concentration of the aqueous solution is 0.01%-98%, for example, it can be 0.01%-80%, or it can be 1%-70%, or it can be 5%-60%, or it can be 5%-50%, or it can be 5%-40%, or it can be 5%-30%.

[0037] In some embodiments of the present application, when the non-hydrogen fluoride liquid fluid is phosphoric acid, the phosphoric acid used is an aqueous solution of phosphoric acid, and the mass percentage concentration of the aqueous solution is 0.01%-90%, for example, it can be 0.01%-80%, or it can be 1%-70%, or it can be 5%-60%, or it can be 5%-50%, or it can be 5%-40%, or it can be 5%-30%.

[0038] In the present application, in addition to the raw material anhydrous hydrogen fluoride, other reagents used are preferably of high purity to reduce the introduction of additional impurities.

[0039] According to some preferred aspects of the present application, in step (2), in the process of forming the gas-liquid exchange interface, the heterogeneous flow flows from top to bottom, and the gas flow to be treated flows from bottom to top.

[0040] According to some preferred aspects of the present application, in step (2), the thickness of the gas-liquid exchange interface is 0.001-25 mm.

[0041] According to some preferred aspects of the present application, in step (2), in the process of the heterogeneous flow flowing from top to bottom, the amount of hydrogen fluoride in the heterogeneous flow decreases from top to bottom, and the decrease is 0.0001%-20% per millimeter of height.

[0042] According to the present application, in the process (2), the heterogeneous flow and the hydrogen fluoride mass transfer performance change sharply with the change of the hydrogen fluoride concentration in the flow process, the interface of the heterogeneous flow is constantly updated in the falling process, and the heterogeneous flow fully absorbs the aerosol impurities less than 10 microns. Specifically, in the upward flow process of the heterogeneous flow, the concentration of hydrogen fluoride in the heterogeneous flow increases and reaches a saturated state, and when in the saturated state, the heterogeneous flow presents a mixed state of gas and liquid, which can be used to absorb aerosol impurities with a size less than 10 microns.

[0043] According to some preferred and specific aspects of the present application, the method is a continuous production process, and the feed rate of the anhydrous hydrogen fluoride is 0.0001-100000 m 3 / h, for example, can be 0.001-50000 m 3 / h, and can also be 0.01-20000 m 3 / h.

[0044] According to some preferred and specific aspects of the present application, the method is a continuous production process, and the feed rate of the heterogeneous flow is 0.001-178 kg / h.

[0045] According to some preferred aspects of the present application, the method further comprises: collecting the mist condensate obtained after the demisting of the demisting layer in the process (2) and the heterogeneous flow obtained after the purification of the heterogeneous flow purification layer, and periodically heating and resolving, so that the resolved hydrogen fluoride gas flows through the demisting layer and the heterogeneous flow purification layer in turn to obtain high-purity hydrogen fluoride, and the mother liquor obtained by resolution is periodically cooled and extracted, which can be sold as industrial products.

[0046] In some embodiments of the present application, the method is carried out using a continuous production device, which comprises a pretreatment tank, a purification tower and an absorption tower connected in sequence, the purification tower comprises a demisting layer and a heterogeneous flow purification layer arranged in sequence from bottom to top, the demisting layer is in communication with the pretreatment tank, and the heterogeneous flow purification layer is in communication with the absorption tower.

[0047] In the present application, the demisting layer can use conventional products, which will not be described in detail here.

[0048] In the present application, the mass percentage of the prepared ultra-high purity hydrofluoric acid can be 39.5%-50.0%.

[0049] Due to the use of the above technical scheme, the present application has the following advantages compared with the prior art:

[0050] The present application provides a heterogeneous flow purification method, which first removes the difficult-to-remove impurity arsenic in anhydrous hydrogen fluoride as much as possible in a pretreatment manner, and then forms a gas-liquid exchange interface between the heterogeneous flow formed by a liquid fluid other than hydrogen fluoride and the hydrogen fluoride gas flow obtained after pretreatment, which simulates the rectifying reflux part and artificially creates a heterogeneous flow medium membrane to form a gas-liquid purification exchange membrane, thereby achieving the purification of hydrogen fluoride gas. The heterogeneous flow purification method does not require ultrahigh and ultralow temperature conditions, has low requirements for equipment, realizes the ultrahigh purification of hydrogen fluoride, and further uses pure water absorption to obtain ultrahigh purity hydrofluoric acid.

[0051] Especially, in the pretreatment process, the super-oxidizing agent oxidizes the arsenic impurity mainly in the form of arsenic trifluoride to arsenic pentafluoride. However, the solubility of the super-oxidizing agent in water is limited. When the concentration of the super-oxidizing agent in water cannot be further increased, the trace amount of impurity arsenic, for example, in ppm level, cannot be fully contacted with the super-oxidizing agent, and the oxidation of arsenic trifluoride is not complete. At this time, the other aspect of the super-oxidizing agent will play a synergistic role, that is, the super-oxidizing agent can oxidize the variable valence metal in the stabilizer added to the system to high valence metal ions. At this time, the high valence metal ions also have strong oxidation ability. When the system maximizes the dissolution of the super-oxidizing agent, there are also high valence metal ions with strong oxidation ability, which is equivalent to increasing the concentration of the super-oxidizing agent in water. The high valence metal ions can exist in water at a very high concentration, which further increases the concentration of the super-oxidizing agent in water by an order of magnitude, improves the contact probability with the trace amount of impurity arsenic, and has a catalytic effect, thereby improving the impurity removal efficiency and the oxidation and impurity removal ability, and realizing the oxidation of arsenic trifluoride to arsenic pentafluoride as much as possible.

[0052] Further, when the arsenic trifluoride in the system is basically converted into arsenic pentafluoride, the arsenic pentafluoride can be converted into fluorine arsenate in the presence of the stabilizer and hydrogen fluoride in the system, which is easy to separate and remove, thereby greatly reducing the content of impurity arsenic in the gas flow to be treated formed by heating and evaporating the pretreated anhydrous hydrogen fluoride, and laying a foundation for subsequent heterogeneous flow impurity removal.

[0053] Furthermore, the ultra-high purity hydrofluoric acid prepared using the heterogeneous flow process of this invention has an anion content of less than 50 ppb and an metal ion content of less than 10 ppt, except for fluoride ions. Compared with existing methods, the method of this invention has simpler processes and equipment, higher production efficiency, lower energy consumption, better product quality stability, and the product can meet or even exceed the requirements of SEMI C12 standards. It can be used in other fields such as ultra-high purity reagent preparation, semiconductor integrated circuit manufacturing, display manufacturing, semiconductor light-emitting device manufacturing, and solar cell manufacturing. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 This is a schematic diagram of the production apparatus used in an embodiment of the present invention;

[0056] In the attached diagram, the following are the reference numerals: 1. Raw material tank; 2. Pretreatment tank; 3. Purification tower; 31. Demisting layer; 32. Heterogeneous flow purification layer; 33. Heterogeneous flow supply mechanism; 331. Heterogeneous flow storage tank; 332. Heterogeneous flow pump; 4. Absorption tower; 5. Heat exchanger; 6. Absorption tank; 61. Circulation pump; 7. Finished product tank; 8. Collection tank; 9. Industrial-grade material buffer tank. Detailed Implementation

[0057] The main concepts of this invention include: drawing on the techniques and skills of the reflux section in distillation technology, this invention uses non-hydrogen fluoride materials to artificially create an ultra-high purity heterogeneous flow medium membrane layer. By forming a gas-liquid exchange layer, hydrogen fluoride gas is purified. Simultaneously, before heterogeneous flow impurity removal, the concentration of superoxidant in the water is indirectly increased through the synergistic effect of three specific chemical reagents, maintaining and improving the metastable state of superoxidation. This overcomes the problem that when the superoxidant has low solubility in water (i.e., a relatively low concentration in water), it is insufficient to effectively and fully contact the trace impurity arsenic trifluoride, thus laying the foundation for heterogeneous flow impurity removal. Compared with the traditional distillation process, this invention reduces the requirements for equipment corrosion resistance and heat transfer performance, while also reducing energy consumption during the purification process. Compared with the ultra-high purity gas washing process, this invention has a reflux dirt balance line in the distillation column, improving the quality stability of the production line products. Compared with technical solutions that require the use of plasma generators to generate plasma to promote the elimination of impurities, including arsenic trifluoride, this invention significantly reduces the requirements for enterprise production conditions.

[0058] Based on this, the present invention provides a method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow. In the ultra-high purity hydrofluoric acid, the mass content of each metal cation is below 10 ppt, and the mass content of each anion, except for fluoride ions, is below 50 pptb. The method uses anhydrous hydrogen fluoride as raw material, and the impurities contained in the anhydrous hydrogen fluoride include arsenic trifluoride.

[0059] The methods for preparing ultra-high purity hydrofluoric acid using heterogeneous flow include:

[0060] Step (1): Add anhydrous hydrogen fluoride to a pretreatment tank containing pure water, add superoxidant, complexing agent and stabilizer to remove impurities, and obtain pretreated anhydrous hydrogen fluoride;

[0061] The stabilizer is a fluoride salt of a metal whose valence state can be changed; the superoxidant can oxidize arsenic trifluoride to arsenic pentafluoride and can also change the metal ions in the stabilizer from their current valence state to a higher valence state with oxidizing ability; the complexing agent can stabilize the metal ions; among them, during the impurity removal process, arsenic pentafluoride can be partially or completely converted into fluoroarsenate.

[0062] Step (2): Evaporate the pretreated anhydrous hydrogen fluoride to form a gas flow to be treated, and pass it through the demisting layer and the heterogeneous flow purification layer in sequence to obtain ultra-high purity hydrogen fluoride; in the ultra-high purity hydrogen fluoride, the mass content of each metal cation is below 10ppt, and the mass content of each anion except fluoride ion is below 50ppb.

[0063] In the heterogeneous flow purification layer, separation and purification are carried out through a gas-liquid exchange interface formed between the heterogeneous flow of non-fluorinated hydrogen liquid fluid and the gas flow to be treated.

[0064] Step (3): Absorb ultra-high purity hydrogen fluoride with pure water and / or hydrofluoric acid to obtain ultra-high purity hydrofluoric acid.

[0065] The following is in conjunction with the appendix Figure 1 The method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow described above in this invention will be further explained below. Figure 1 The production apparatus shown can operate continuously or intermittently. The following example illustrates continuous production.

[0066] Raw material tank 1 can store anhydrous hydrogen fluoride alone, or it can store a mixture of anhydrous hydrogen fluoride and super oxidant. If raw material tank 1 stores anhydrous hydrogen fluoride alone, an inlet for super oxidant can be opened in pretreatment tank 2 or in the pipeline leading to pretreatment tank 2, so as to achieve the purpose of introducing anhydrous hydrogen fluoride and super oxidant into pretreatment tank 2 together.

[0067] In some specific aspects, the superoxidant is selected from one or more combinations of fluorine gas, a mixture of fluorine gas and nitrogen gas, oxygen difluoride, a mixture of oxygen difluoride and nitrogen gas, ozone, fluorine free radicals, and oxygen free radicals. Therefore, the present invention can mix anhydrous hydrogen fluoride and superoxidant in advance according to a preset ratio and store them in the raw material tank 1. Further, the preset ratio is to control the molar ratio of superoxidant to anhydrous hydrogen fluoride to be 0.01-2.5:100.

[0068] Furthermore, the preparation method of fluorine-oxygen plasma can refer to existing methods. Specifically, the preparation method of fluorine-oxygen plasma can be: inductively coupled plasma (ICP): a mixture of fluorine and oxygen gas (volume ratio of 0.02-10:1) is passed through an induction coil to generate an alternating magnetic field, thereby inducing eddy currents in the gas, causing the gas to ionize and form plasma;

[0069] There can be one, two, three, or even more pretreatment tanks 2, which can be connected in parallel, series, or series-parallel. Pure water, a complexing agent, and a stabilizer are added to the pretreatment tanks 2 to form a mixed solution. The amounts of the complexing agent and stabilizer added are controlled by ensuring their respective mass concentrations in the mixed solution are independently between 0.01% and 3%. Anhydrous hydrogen fluoride and a superoxidant are introduced into the pretreatment tanks 2 to contact the mixed solution and form a pretreatment reaction system for impurity removal, primarily oxidizing and removing arsenic. The trivalent arsenic in the anhydrous hydrogen fluoride is oxidized to pentavalent arsenic, and further ionization and solidification treatment is performed to break the azeotropic properties of arsenic trifluoride and hydrogen fluoride. The impurity removal time can be quantitatively determined based on the number of pretreatment tanks 2 and the processing time of each pretreatment tank 2, for example, it can be 0.01-1800 minutes. The processing temperature is controlled at -10 to 110°C, or 5 to 110°C, or 10 to 108°C. When multiple pretreatment tanks 2 are used, the impurity removal time can be extended. However, this invention indirectly increases the concentration of super oxidant in the water through the synergistic effect of the three specific chemical reagents mentioned above (overcoming the problem that when the super oxidant has low solubility in water (i.e., its concentration in water is relatively low), it is insufficient to effectively and fully contact the trace impurity arsenic trifluoride). This maintains and improves the metastable state of super oxidant, achieving efficient and excellent removal of impurity arsenic trifluoride. Therefore, when using one pretreatment tank 2, this invention can also achieve maximum removal of impurity arsenic trifluoride in a short time, such as 0.01-180 min, or 0.01-60 min, or even within 10 min, such as within 1 min.

[0070] Generally, at least one pretreatment tank 2 is located below the purification tower 3, specifically below the demister layer 31, while the heterogeneous flow purification layer 32 is located above the demister layer 31. During the impurity removal process in the pretreatment tank 2, the temperature is typically set between 10 and 108°C. Within this temperature range, the pretreated anhydrous hydrogen fluoride treated in the pretreatment tank 2 can be evaporated to form a gas stream to be treated. This gas stream can directly enter the upper demister layer 31 and then the heterogeneous flow purification layer 32. In the heterogeneous flow purification layer 32, the heterogeneous flow (formed by the flow of non-fluoride liquid fluid) flowing downwards contacts the gas stream to be treated flowing upwards, forming a gas-liquid exchange interface. A heterogeneous flow medium membrane is artificially created by simulating the reflux section of distillation to form a gas-liquid purification exchange membrane. The thickness of the gas-liquid exchange interface is controlled to be 0.001-25 mm. During the downward flow of the heterogeneous flow, the increase in hydrogen fluoride in the heterogeneous flow decreases sequentially from top to bottom, generally by 0.0001%-20% per millimeter of height. In particular, during the downward flow of the heterogeneous flow, the concentration of hydrogen fluoride in the heterogeneous flow increases until it reaches saturation. When saturated, the heterogeneous flow exists as a mixture of gaseous and liquid states. This mixture can absorb aerosol impurities smaller than 10 micrometers, thereby further improving the purification level of hydrogen fluoride gas.

[0071] Furthermore, in some specific cases, the non-fluorinated hydrogen liquid fluid is selected from one or more of pure water, hydrofluoric acid, hydrogen peroxide, sulfuric acid, and phosphoric acid. It can be added to the upper part of the heterogeneous flow purification layer 32 of the purification tower 3 through the heterogeneous flow supply mechanism 33, so that it flows from top to bottom. The heterogeneous flow supply mechanism 33 includes a heterogeneous flow storage tank 331 for storing heterogeneous flow and a heterogeneous flow pump 332 for pumping heterogeneous flow from the heterogeneous flow storage tank 331 to the heterogeneous flow purification layer 32.

[0072] In some specific cases, the feed rate of the anhydrous hydrogen fluoride is 0.0001-100000 m / s. 3 / h, for example, can be 0.001-50000m 3 / h, or 0.01-20000m 3 The feed rate of the heterogeneous flow is 0.001-178 kg / h.

[0073] In addition, the condensate obtained after demisting and the heterogeneous flow obtained after purification by the heterogeneous flow purification layer can be introduced into the collection tank 8 and heated and desorbed periodically. The desorbed hydrogen fluoride gas stream passes through the demisting layer 31 and the heterogeneous flow purification layer 32 in sequence to obtain high-purity hydrogen fluoride. The mother liquor obtained by desorption is cooled and extracted periodically and can be stored in the industrial-grade material buffer tank 9 for sale as an industrial product.

[0074] After treatment in purification tower 3, ultra-high purity hydrogen fluoride is obtained. In this ultra-high purity hydrogen fluoride, the mass content of each metal cation is below 10 ppt, and the mass content of each anion (excluding fluoride ions) is below 50 pptb. Passing this into absorption tower 4 and absorbing it with pure water and / or hydrofluoric acid yields ultra-high purity hydrofluoric acid. For actual operation, refer to... Figure 1 As shown, pure water can be filled into the absorption tank 6 and then pumped into the upper part of the absorption tower 4 by the circulation pump 61. After being sprayed, the ultra-high purity hydrogen fluoride is absorbed to form a hydrogen fluoride aqueous solution (i.e., hydrofluoric acid). After being cooled by the heat exchanger 5, it is introduced into the absorption tank 6. This cycle is repeated. The subsequent absorption of ultra-high purity hydrogen fluoride is done with newly obtained hydrofluoric acid at a low concentration. When the cycle reaches a certain concentration, it can be discharged into the finished product tank 7 for storage or external distribution. Pure water can be added to the absorption tank 6 as needed to ensure the absorption effect.

[0075] The above-mentioned solution will be further described below with reference to specific embodiments; it should be understood that these embodiments are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments; the implementation conditions used in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0076] Unless otherwise specified in the following embodiments, all raw materials are commercially available or prepared using conventional methods in the art. Temperature values ​​at various locations may fluctuate under normal circumstances, generally within ±10 degrees Celsius, preferably within ±5 degrees Celsius. In the following embodiments, temperature values ​​are limited by the word "approximately," indicating that they may fall within the reasonable temperature fluctuation range described above.

[0077] The hydrofluoric acid or hydrogen fluoride content of the present invention was analyzed by sodium hydroxide titration, the metal ion content was detected by inductively coupled plasma mass spectrometry (ICP-MS, Thermo X-7 series), and the anions were detected by liquid ion chromatography (IC).

[0078] The raw material, anhydrous hydrogen fluoride, was of industrial grade GB 7746-2011, with a hydrogen fluoride content greater than 99.99%. P53 protein, ferric humate, and other related stabilizers and complexing agents were purchased from Aladdin.

[0079] Examples 1-6

[0080] These embodiments provide a method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow, which employs... Figure 1 The production apparatus and the above production process are shown, wherein: in the preparation process of fluorine-oxygen plasma, the volume ratio of fluorine gas to oxygen gas in the mixed gas of fluorine and oxygen is 5:1.

[0081] For specific operating procedures, please refer to Table 1.

[0082] Table 1

[0083]

[0084]

[0085] Comparative Example 1

[0086] The process is basically the same as in Example 1, except that the use and addition method of the stabilizer are adjusted. The specific process after adjustment is as follows:

[0087] Step (a): Anhydrous hydrogen fluoride is added to a pretreatment tank containing pure water, and superoxidant and complexing agent are added for impurity removal to obtain pretreated anhydrous hydrogen fluoride;

[0088] Step (b): The pretreated anhydrous hydrogen fluoride is heated and evaporated to form a gas flow to be treated. The gas flow is then passed sequentially through an aqueous solution containing a stabilizer, a demisting layer, and a heterogeneous flow purification layer to obtain purified hydrogen fluoride.

[0089] Step (c): The purified hydrogen fluoride is absorbed with pure water to obtain hydrofluoric acid product.

[0090] Comparative Example 2

[0091] It is basically the same as Example 1, except that no complexing agent is added.

[0092] Results Test

[0093] The hydrofluoric acid products obtained in Examples 1-6 and Comparative Examples 1-2 were tested as follows, and the test results are shown in Table 2.

[0094] Table 2 shows the detection results of Examples 1-6 and Comparative Examples 1-2.

[0095] Item Units Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Anion ppb <50 <50 <50 <50 <50 <50 <50 <50 Sodium (Na) ppt 0.000 0.000 0.000 0.000 0.070 0.000 0.000 0.000 Magnesium (Mg) ppt 2.646 6.106 1.169 2.624 0.614 0.422 2.600 0.003 Aluminum (Al) ppt 0.408 2.322 0.616 1.753 0.048 0.000 0.307 0.000 Potassium (K) ppt 0.313 2.326 0.399 1.529 0.016 0.000 0.210 0.002 Calcium (Ca) ppt 2.122 3.086 1.522 1.691 0.597 0.808 2.200 0.001 Titanium (Ti) ppt 3.835 1.600 1.644 4.112 0.072 0.036 3.502 0.101 Vanadium (V) ppt 0.416 2.065 1.437 1.419 0.981 0.216 0.310 0.101 Chromium (Cr) ppt 7.097 1.958 4.850 8.981 1.334 1.468 6.910 0.002 Manganese (Mn) ppt 0.131 0.269 0.067 0.201 0.000 0.000 0.200 0.201 Iron (Fe) ppt 0.000 1.211 0.330 0.881 0.019 0.076 0.107 0.012 Cobalt (Co) ppt 0.125 0.532 0.000 0.266 0.000 0.000 0.000 0.000 Nickel (Ni) ppt 0.000 0.000 0.000 0.000 0.019 0.111 0.002 0.002 Copper (Cu) ppt 0.158 0.703 0.506 0.760 4.604 6.030 0.003 0.100 Zinc (Zn) ppt 3.318 1.712 5.925 1.020 0.000 0.000 3.401 0.012 Gallium (Ga) ppt 0.123 0.388 0.090 0.567 5.669 3.293 0.200 0.121 Germanium (Ge) ppt 0.426 1.845 1.908 1.027 0.111 0.047 0.503 0.003 Arsenic (As) ppt 0.818 1.486 0.568 0.830 0.681 0.788 200000 200 Strontium (Sr) ppt 8.159 1.020 5.301 5.201 0.292 0.341 8.105 0.001 Zirconium (Zr) ppt 2.274 3.315 2.452 2.270 2.627 1.699 3.172 0.002 Niobium (Nb) ppt 4.884 6.114 6.116 1.834 1.063 1.036 5.002 0.000 Molybdenum (Mo) ppt 0.000 0.300 0.300 0.600 0.000 0.075 0.000 0.003 Silver (Ag) ppt 0.000 2.511 0.000 0.942 0.000 0.038 0.000 0.102 Cadmium (Cd) ppt 0.000 0.116 0.000 0.000 0.036 0.000 0.001 0.000 Tin (Sn) ppt 0.049 0.479 0.000 0.240 0.128 0.021 0.102 0.004 Antimony (Sb) ppt 1.093 1.110 0.996 1.455 0.233 0.150 0.908 0.001 Barium (Ba) ppt 0.000 0.083 0.000 0.000 0.038 0.000 0.002 0.000 Thallium (Tl) ppt 1.870 2.357 2.821 3.385 0.059 0.000 0.100 0.000

[0096] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0097] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow, wherein the mass content of each metal cation is below 10 ppt, and the mass content of each anion (excluding fluoride ions) is below 50 pptb, wherein the method uses anhydrous hydrogen fluoride as raw material, and the anhydrous hydrogen fluoride contains impurities including arsenic trifluoride, characterized in that... The method includes: Step (1): The anhydrous hydrogen fluoride is added to a pretreatment tank containing pure water, and superoxidant, complexing agent and stabilizer are added for impurity removal treatment to obtain pretreated anhydrous hydrogen fluoride; The stabilizer is a fluoride salt of a metal whose valence state can be changed; the superoxidant can oxidize the arsenic trifluoride to arsenic pentafluoride and can change the metal in the stabilizer from its current valence state to a higher valence state with oxidizing ability; the complexing agent can stabilize the metal ions; wherein, during the impurity removal process, the arsenic pentafluoride can be partially or completely converted into fluoroarsenate. Step (2): Evaporate the pretreated anhydrous hydrogen fluoride to form a gas flow to be treated, and pass it through the demisting layer and the heterogeneous flow purification layer in sequence to obtain ultra-high purity hydrogen fluoride; in the ultra-high purity hydrogen fluoride, the mass content of each metal cation is below 10ppt, and the mass content of each anion, except for fluoride ions, is below 50ppb. In the heterogeneous flow purification layer, separation and purification are performed by a gas-liquid exchange interface formed between the heterogeneous flow formed by the flow of non-fluorinated hydrogen liquid fluid and the gas flow to be treated. Step (3): The ultra-high purity hydrogen fluoride is absorbed by pure water and / or hydrofluoric acid to obtain ultra-high purity hydrofluoric acid.

2. The method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow according to claim 1, characterized in that, In step (1), the superoxidant is selected from one or more combinations of fluorine gas, a mixture of fluorine gas and nitrogen gas, oxygen difluoride, a mixture of oxygen difluoride and nitrogen gas, ozone, fluorine free radicals, and oxygen free radicals; and / or, In step (1), the complexing agent is one or more selected from ferric humate, tartaric acid, phenol, and P53 protein; and / or, In step (1), the stabilizer is a fluoride salt of one metal selected from sodium, potassium, iron, nickel, manganese, cobalt and copper, or the stabilizer is a combination of fluoride salts of several metals selected from sodium, potassium, iron, nickel, manganese, cobalt and copper.

3. The method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow according to claim 1 or 2, characterized in that, In step (1), the pure water, the complexing agent and the stabilizer constitute a mixed solution, and the mixed solution, the anhydrous hydrogen fluoride and the super oxidant constitute a pretreatment reaction system; during the impurity removal process, the temperature of the pretreatment reaction system is controlled to be -10 to 110°C and the impurity removal time is 0.01 to 1800 min.

4. The method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow according to claim 3, characterized in that, During the impurity removal process, the temperature of the pretreatment reaction system is controlled at 5–110°C and the impurity removal time is 0.01–180 min.

5. The method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow according to claim 4, characterized in that, During the impurity removal process, the temperature of the pretreatment reaction system is controlled at 10–108°C and the impurity removal time is 0.01–60 min.

6. The method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow according to claim 5, characterized in that, During the impurity removal process, the mass percentage of anhydrous hydrogen fluoride in the pretreatment reaction system is always controlled to be greater than or equal to 0.001% and less than 100%; and / or, the amount of complexing agent added and the amount of stabilizer added are controlled so that their respective mass concentrations in the mixed solution of the pretreatment reaction system are independently between 0.01% and 3%.

7. The method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow according to claim 1, characterized in that, In step (1), during the impurity removal process, the molar ratio of the superoxidant to the anhydrous hydrogen fluoride is controlled to be 0.01-2.5:

100.

8. The method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow according to claim 1, characterized in that, In step (2), the non-fluorinated hydrogen liquid fluid is selected from one or more of pure water, hydrofluoric acid, hydrogen peroxide, sulfuric acid, and phosphoric acid.

9. The method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow according to claim 1, characterized in that, In step (2), during the formation of the gas-liquid exchange interface, the heterogeneous flow flows from top to bottom, and the gas to be treated flows from bottom to top.

10. The method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow according to claim 1 or 9, characterized in that, In step (2), the thickness of the gas-liquid exchange interface is 0.001-25mm.

11. The method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow according to claim 1 or 9, characterized in that, In step (2), during the downward flow of the heterogeneous flow, the amount of hydrogen fluoride growth in the heterogeneous flow decreases sequentially from top to bottom, and the decrease is 0.0001-20% per millimeter of height.

12. The method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow according to claim 1 or 9, characterized in that, In step (2), during the downward flow of the heterogeneous flow, the concentration of hydrogen fluoride in the heterogeneous flow increases until it reaches saturation. When it is in the saturation state, the heterogeneous flow is presented as a mixture of gaseous and liquid states, which can be used to absorb aerosol impurities with a size of less than 10 micrometers.

13. The method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow according to claim 1, characterized in that, The method is a continuous production process, and the feed rate of the anhydrous hydrogen fluoride is 0.0001-100000 m / s. 3 / h; and / or, the feed rate of the heterogeneous flow is 0.001-178 kg / h.

14. The method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow according to claim 1, characterized in that, The method further includes: collecting the condensate obtained after demisting the mist layer in step (2) and the heterogeneous flow obtained after purification by the heterogeneous flow purification layer, and periodically heating and desorbing it, so that the desorbed hydrogen fluoride gas flow passes through the mist layer and the heterogeneous flow purification layer in sequence to obtain high-purity hydrogen fluoride, and periodically cooling and extracting the mother liquor obtained from the desorption.

15. The method for preparing ultra-high purity hydrofluoric acid using heterogeneous flow according to claim 1, characterized in that, The method is carried out using the following continuous production apparatus, which includes a pretreatment tank, a purification tower, and an absorption tower connected in sequence. The purification tower includes a demisting layer and a heterogeneous flow purification layer arranged in sequence from bottom to top. The demisting layer is connected to the pretreatment tank, and the heterogeneous flow purification layer is connected to the absorption tower.

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