Method for preparing anhydrous hydrogen fluoride, anhydrous hydrogen fluoride and use thereof

Abstract

The present disclosure belongs to the technical field of hydrogen fluoride preparation. Specifically disclosed are a method for preparing anhydrous hydrogen fluoride, anhydrous hydrogen fluoride and the use thereof. The method comprises: mixing first fluorine-containing sulfuric acid with water for reaction to obtain a reaction solution containing hydrogen fluoride; evaporating the reaction solution containing hydrogen fluoride to obtain an evaporated liquid phase and an evaporated gas phase; washing the evaporated gas phase to obtain a washed gas phase; and condensing the washed gas phase to obtain anhydrous hydrogen fluoride. The method of the present disclosure has relatively low costs and high economic benefits, the yield of by-product sulfuric acid is about 1.5 times lower than that of the fluosilicic acid method, the application field of by-product sulfuric acid is wider than that of by-product sulfuric acid of the fluosilicic acid method, and the preparation process involves a reduced environmental burden. Meanwhile, the present disclosure adopts the by-product fluorine-containing sulfuric acid to prepare anhydrous hydrogen fluoride, thus achieving recycling of resources.

Description

Methods for preparing anhydrous hydrogen fluoride, anhydrous hydrogen fluoride and its uses

[0001] Priority information

[0002] This disclosure requests priority to Chinese Patent Application No. 202411742476.2, filed with the China National Intellectual Property Administration on November 29, 2024, entitled “Method for preparing anhydrous hydrogen fluoride, anhydrous hydrogen fluoride and its uses”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of hydrogen fluoride preparation technology, and in particular to a method for preparing anhydrous hydrogen fluoride using fluorinated sulfuric acid, anhydrous hydrogen fluoride, and its uses. Background Technology

[0004] Currently, the main processes for preparing anhydrous hydrogen fluoride include the fluorite method and the fluorosilicic acid method. The fluorite method, which uses the reaction of fluorite with sulfuric acid to produce anhydrous hydrogen fluoride, is the mainstream process in the market. However, the fluorite method has the following disadvantages: 1) It requires a large amount of concentrated sulfuric acid as raw material, resulting in high raw material costs; 2) For every ton of hydrogen fluoride produced, 3.6 tons of anhydrous fluorogypsum are generated as a byproduct. This byproduct has low utilization value and will pollute the environment if stockpiled; 3) It usually requires high-purity fluorite powder (above 98%), which is expensive, increasing raw material costs. The fluorosilicic acid method is relatively mature in technology, but it has high investment costs, a complex process flow, and requires the nitration of a large amount of fluorinated dilute sulfuric acid as a byproduct in a phosphate chemical plant, which has certain limitations. Furthermore, the silica generated during the production process can easily clog pipelines. Summary of the Invention

[0005] This disclosure aims to at least partially address one of the technical problems in related technologies. Therefore, the purpose of this disclosure is to provide a method for preparing anhydrous hydrogen fluoride, the anhydrous hydrogen fluoride itself, and its uses. The method of this disclosure uses fluorinated sulfuric acid to prepare anhydrous hydrogen fluoride, which has lower cost and higher economic benefits. Furthermore, the amount of sulfuric acid produced as a byproduct is approximately 1.5 times lower than that of the fluorosilicic acid method, and the application channels for the byproduct sulfuric acid are wider than those of the fluorosilicic acid method. Moreover, the environmental impact of the preparation process is lower. Simultaneously, this disclosure uses fluorinated sulfuric acid as a byproduct to prepare anhydrous hydrogen fluoride, achieving resource recycling and reuse.

[0006] In one aspect of this disclosure, a method for preparing anhydrous hydrogen fluoride is provided. According to embodiments of this disclosure, the method includes:

[0007] The first fluorinated sulfuric acid was mixed with water and reacted to obtain a reaction solution containing hydrogen fluoride;

[0008] The reaction solution containing hydrogen fluoride is evaporated to obtain an evaporated liquid phase and an evaporated gas phase;

[0009] The evaporated gas phase is washed to obtain a washed gas phase;

[0010] The washed gas phase was condensed to obtain anhydrous hydrogen fluoride.

[0011] The method for preparing anhydrous hydrogen fluoride according to the embodiments of this disclosure uses fluorinated sulfuric acid, which has lower cost and higher economic benefits. Furthermore, the amount of sulfuric acid produced as a byproduct is about 1.5 times lower than that of the fluorosilicic acid method, and the application channels for the byproduct sulfuric acid are wider than those of the fluorosilicic acid method. The environmental impact of the preparation process is also lower. At the same time, this disclosure uses fluorinated sulfuric acid as a byproduct to prepare anhydrous hydrogen fluoride, achieving resource recycling and reuse.

[0012] Additional aspects and advantages of this disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this disclosure. Attached Figure Description

[0013] The above and / or additional aspects and advantages of this disclosure will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0014] Figure 1 is a schematic flowchart of the method for preparing anhydrous hydrogen fluoride according to an embodiment of the present disclosure. Detailed Implementation

[0015] Embodiments of this disclosure are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this disclosure, and should not be construed as limiting this disclosure.

[0016] In one aspect, this disclosure provides a method for preparing anhydrous hydrogen fluoride, as shown in Figure 1. According to an embodiment of this disclosure, the method includes: mixing and reacting a first fluorinated sulfuric acid with water to obtain a reaction solution containing hydrogen fluoride; evaporating the reaction solution containing hydrogen fluoride to obtain an evaporated liquid phase and an evaporated gas phase; washing the evaporated gas phase to obtain a washed gas phase; and condensing the washed gas phase to obtain anhydrous hydrogen fluoride. Therefore, the method of this disclosure can prepare anhydrous hydrogen fluoride using fluorinated sulfuric acid, which is low-cost, economically efficient, and produces approximately 1.5 times less sulfuric acid as a byproduct compared to the fluorosilicic acid method. The byproduct sulfuric acid has a wider range of applications than the byproduct sulfuric acid produced in the fluorosilicic acid method, and the environmental impact of the preparation process is lower. Furthermore, this disclosure uses fluorinated sulfuric acid as a byproduct to prepare anhydrous hydrogen fluoride, achieving resource recycling and reuse.

[0017] The principle behind the method for preparing anhydrous hydrogen fluoride proposed in this disclosure, which enables the above-mentioned beneficial effects, will be explained in detail below:

[0018] This disclosure involves mixing fluorinated sulfuric acid with water. The fluorosulfonic acid in the fluorinated sulfuric acid reacts with the water to produce hydrogen fluoride and sulfuric acid. The hydrogen fluoride in the sulfuric acid is then vaporized through evaporation. After washing, distillation, and degassing, a qualified anhydrous hydrogen fluoride product is obtained. Compared to the fluorite method for preparing anhydrous hydrogen fluoride, this method has lower costs, lower energy consumption, and less environmental impact throughout the entire preparation process. Compared to the fluorosilicic acid method for preparing anhydrous hydrogen fluoride, firstly, the method disclosed herein has lower investment costs; secondly, the amount of sulfuric acid produced as a byproduct of the method disclosed herein is about 1.5 times lower than that of the fluorosilicic acid method, with approximately 10 tons of sulfuric acid produced as a byproduct for preparing 1 ton of anhydrous hydrogen fluoride using the method disclosed herein, while approximately 26 tons of sulfuric acid are produced as a byproduct for the same method; thirdly, the hydrogen fluoride content in the sulfuric acid produced as a byproduct of the method disclosed herein is ≤0.2%, while the hydrogen fluoride content in the sulfuric acid produced as a byproduct of the fluorosilicic acid method is 0.3%–0.4%, thus the application channels for the sulfuric acid produced as a byproduct of the method disclosed herein are wider than those for the sulfuric acid produced as a byproduct of the fluorosilicic acid method; fourthly, the method disclosed herein does not produce silicon dioxide as a byproduct, thus avoiding the risk of system blockage; fifthly, the process flow of the method disclosed herein is simpler, avoiding complex operations; and sixthly, the yield of anhydrous hydrogen fluoride produced by the method disclosed herein reaches over 90%, while the yield of anhydrous hydrogen fluoride produced by the fluorosilicic acid method is only about 80%.

[0019] Meanwhile, this disclosure utilizes the byproduct fluorinated sulfuric acid to prepare anhydrous hydrogen fluoride, achieving resource recovery and reuse. Furthermore, the source of the byproduct fluorinated sulfuric acid is not particularly limited; for example, it can originate from the PF5 preparation process, the fluorite preparation process, or the fluorosilicic acid preparation process.

[0020] The method for preparing anhydrous hydrogen fluoride proposed in this invention will be described in detail below:

[0021] Specifically, referring to Figure 1, the above method for preparing anhydrous hydrogen fluoride includes the following steps:

[0022] S100: The first fluorinated sulfuric acid is mixed with water and reacted to obtain a reaction solution containing hydrogen fluoride;

[0023] In this step, the first fluorinated sulfuric acid is mixed with water. The fluorosulfonic acid in the fluorinated sulfuric acid reacts with water to produce hydrogen fluoride and sulfuric acid, resulting in a reaction solution containing hydrogen fluoride. The reaction equation is as follows: HSO3F + H2O = H2SO4 + HF

[0024] In embodiments of this disclosure, the first fluorinated sulfuric acid can be a byproduct of fluorinated sulfuric acid. This disclosure uses the byproduct to prepare anhydrous hydrogen fluoride, achieving resource recycling and reuse. The first fluorinated sulfuric acid includes sulfuric acid, fluorosulfonic acid, hydrogen fluoride, and water.

[0025] According to some specific embodiments of this disclosure, the aforementioned first fluorinated sulfuric acid comprises 55wt% to 80wt% sulfuric acid (examples include 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, etc.), 15wt% to 35wt% fluorosulfonic acid (examples include 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, etc.), 2wt% to 6wt% hydrogen fluoride (examples include 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, etc.), and the remainder is water. Therefore, the fluorosulfonic acid in the aforementioned first fluorinated sulfuric acid can effectively react with water to produce hydrogen fluoride and sulfuric acid.

[0026] In embodiments of this disclosure, a tubular mixer can be used to mix the first fluorinated sulfuric acid with water. According to further specific embodiments of this disclosure, the mass ratio of the first fluorinated sulfuric acid to water is (1.7–2.65):1, and examples include 1.7:1, 1.8:1, 1.9:1, 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.65:1, etc. This further ensures that the fluorosulfonic acid in the first fluorinated sulfuric acid can fully react with water to generate hydrogen fluoride and sulfuric acid.

[0027] In the embodiments of this disclosure, during the reaction of the fluorosulfonic acid in the first fluorinated sulfuric acid with water to generate hydrogen fluoride and sulfuric acid, a large amount of heat is released, and the mixing process of the first fluorinated sulfuric acid with water also releases some heat, which can raise the temperature of the reaction system to 130°C to 150°C (examples include 130°C, 135°C, 140°C, 145°C, 150°C, etc.), thereby further promoting the reaction of fluorosulfonic acid with water.

[0028] S200: Evaporate the reaction liquid containing hydrogen fluoride to obtain the evaporated liquid phase and the evaporated gas phase;

[0029] In this step, a falling film evaporator can be used to evaporate the above-mentioned reaction solution containing hydrogen fluoride, obtaining a liquid phase and a gas phase after evaporation. The gas phase after evaporation includes 95wt% to 99wt% hydrogen fluoride (examples can be 95wt%, 96wt%, 97wt%, 98wt%, 99wt%, etc.), 1wt% to 5wt% water (examples can be 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, etc.), and 0.5wt% to 2wt% sulfuric acid (examples can be 0.5wt%, 1wt%). The liquid phase after evaporation contains 1.5 wt%, 2 wt%, etc., of 60 wt% to 75 wt% sulfuric acid (examples include 60 wt%, 62 wt%, 64 wt%, 66 wt%, 68 wt%, 70 wt%, 72 wt%, 75 wt%, etc.), 0.5 wt% to 2 wt% hydrogen fluoride (examples include 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, etc.), and 25 wt% to 40 wt% water (examples include 25 wt%, 30 wt%, 35 wt%, 40 wt%, etc.).

[0030] According to some specific embodiments of this disclosure, the temperature for evaporating the reaction solution containing hydrogen fluoride is 130°C to 150°C (examples include 130°C, 135°C, 140°C, 145°C, 150°C, etc.), and the pressure is -3 kPa to 3 kPa (examples include -3 kPa, -2 kPa, -1 kPa, 0 kPa, 1 kPa, 2 kPa, 3 kPa, etc.). That is, the temperature of the falling film evaporator is controlled at 130°C to 150°C and the pressure is controlled at -3 kPa to 3 kPa. By limiting the temperature and pressure of the falling film evaporator within the above ranges, it is possible to further ensure that the hydrogen fluoride in the reaction solution effectively enters the vapor phase after evaporation.

[0031] S300: Wash the evaporated gas phase to obtain a washed gas phase;

[0032] In this step, a second fluorinated sulfuric acid can be used in a washing tower to wash the evaporated gas phase, so as to wash the water, sulfuric acid and other impurities in the evaporated gas phase into the second fluorinated sulfuric acid, and obtain a washed gas phase and a washed liquid phase.

[0033] According to some specific embodiments of this disclosure, the temperature in the washing tower is 40°C to 80°C (for example, it can be 40°C, 50°C, 60°C, 70°C, 80°C, etc.), and the pressure is -3kPa to 3kPa (for example, it can be -3kPa, -2kPa, -1kPa, 0kPa, 1kPa, 2kPa, 3kPa, etc.). By limiting the temperature and pressure in the washing tower to the above range, it is possible to further ensure that impurities such as water and sulfuric acid in the evaporated gas phase are washed into the second fluorinated sulfuric acid.

[0034] According to some specific embodiments of this disclosure, the mass ratio of the second fluorinated sulfuric acid to the evaporated gas phase is (7-13):1. Examples include 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, and 13:1. By limiting the mass ratio of the second fluorinated sulfuric acid to the evaporated gas phase to the above range, it is possible to further ensure that impurities such as water and sulfuric acid in the evaporated gas phase are washed into the second fluorinated sulfuric acid. This disclosure allows the calculation of the mass ratio of the second fluorinated sulfuric acid to the evaporated gas phase by detecting the water and sulfuric acid content in the liquid in the washing tower.

[0035] In embodiments of this disclosure, the second fluorinated sulfuric acid can be a byproduct of fluorinated sulfuric acid. This disclosure uses the byproduct to wash the vapor phase after evaporation, further realizing resource recovery and reuse. The first fluorinated sulfuric acid includes sulfuric acid, fluorosulfonic acid, hydrogen fluoride, and water.

[0036] According to some specific embodiments of this disclosure, the second fluorinated sulfuric acid comprises 55wt% to 80wt% sulfuric acid (for example, it may be 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, etc.), 15wt% to 35wt% fluorosulfonic acid (for example, it may be 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, etc.), 2wt% to 6wt% hydrogen fluoride (for example, it may be 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, etc.), and the remainder is water.

[0037] In embodiments of this disclosure, the washed liquid phase comprises 60wt% to 80wt% sulfuric acid, 15wt% to 30wt% fluorosulfonic acid, 2wt% to 6wt% hydrogen fluoride, and 3wt% to 8wt% water. This composition is not significantly different from that of the first fluorinated sulfuric acid. Therefore, as some preferred embodiments, the washed liquid phase can be returned to step S100 and used as the first fluorinated sulfuric acid, further realizing the recycling and reuse of resources.

[0038] S400: Condenses the washed gas phase to obtain anhydrous hydrogen fluoride;

[0039] In this step, a condenser can be used to condense the washed gas phase to obtain a liquid crude anhydrous hydrogen fluoride. The composition of the liquid crude anhydrous hydrogen fluoride is basically the same as that of the washed gas phase, except that it has changed from a gaseous state to a liquid state.

[0040] According to some further specific embodiments of this disclosure, the above method may also include:

[0041] S500: The anhydrous hydrogen fluoride obtained from S400 is sequentially distilled and degassed to obtain high-quality anhydrous hydrogen fluoride.

[0042] In this step, the liquid crude anhydrous hydrogen fluoride can be sequentially distilled using a distillation column to obtain liquid anhydrous hydrogen fluoride. Then, the liquid anhydrous hydrogen fluoride is degassed using a degassing column to obtain refined anhydrous hydrogen fluoride gas. Calculations show that the yield of anhydrous hydrogen fluoride using the method disclosed in this invention reaches over 90%.

[0043] According to some further specific embodiments of this disclosure, the above method may also include:

[0044] S600: Air is used to strip the evaporated liquid phase in the stripping tower to obtain stripped gas phase and stripped liquid phase;

[0045] In this step, air is used to strip the evaporated liquid phase in a stripping tower so that hydrogen fluoride in the evaporated liquid phase is separated from the evaporated liquid phase, resulting in a stripped gas phase and a stripped liquid phase. The stripped gas phase is then passed through an absorption tower to form hydrofluoric acid, which can be sold as a commercial product.

[0046] According to some specific embodiments of this disclosure, the temperature of the air is 40°C to 100°C (for example, it can be 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, etc.), and the temperature inside the stripping tower is 100°C to 120°C (for example, it can be 100°C, 105°C, 110°C, 115°C, 120°C, etc.). By limiting the temperature of the air and the temperature inside the stripping tower to the above ranges, it is further beneficial to separate the hydrogen fluoride in the evaporated liquid phase from the evaporated liquid phase to obtain the stripped gas phase.

[0047] In the embodiments of this disclosure, the liquid phase after stripping is the only byproduct in the method of this disclosure, and the amount of byproduct generated by the method of this disclosure is about 1.5 times lower than that of the fluorosilicic acid method. The method of this disclosure produces about 10 tons of sulfuric acid byproduct for the preparation of 1 ton of anhydrous hydrogen fluoride, while the fluorosilicic acid method produces about 26 tons of sulfuric acid byproduct for the preparation of 1 ton of anhydrous hydrogen fluoride.

[0048] In the embodiments of this disclosure, the liquid phase after stripping (i.e., byproduct) includes 60wt% to 75wt% sulfuric acid and ≤0.2wt% hydrogen fluoride. That is, the hydrogen fluoride content in the sulfuric acid byproduct of the method of this disclosure is ≤0.2%, while the hydrogen fluoride content in the sulfuric acid byproduct of the fluorosilicic acid method is 0.3% to 0.4%. Therefore, the application channels of the sulfuric acid byproduct of the method of this disclosure are wider than those of the sulfuric acid byproduct of the fluorosilicic acid method.

[0049] In a second aspect, this disclosure provides anhydrous hydrogen fluoride. According to embodiments of this disclosure, anhydrous hydrogen fluoride is prepared by the method described above. Therefore, the anhydrous hydrogen fluoride has a high purity, reaching 99.99% or higher.

[0050] According to some specific embodiments of this disclosure, the anhydrous hydrogen fluoride contains 0.5 to 3 ppm of phosphate impurities and 8 to 12 ppm of sulfate impurities.

[0051] Anhydrous hydrogen fluoride prepared by the fluorite method mainly contains impurities such as fluorosilicic acid, calcium sulfate, heavy metal ions, silicon compounds, and phosphate. Anhydrous hydrogen fluoride prepared by the fluorosilicic acid method mainly contains anions and cations formed by silicon, phosphorus, nitrogen, chlorine, sulfur, arsenic, boron, and metal elements.

[0052] Anhydrous hydrogen fluoride is an important chemical raw material with wide applications in many fields, such as refrigerant production, fluorinated polymer materials, chemical and inorganic fluoride production, integrated circuit manufacturing, and metal surface treatment.

[0053] In a third aspect, this disclosure proposes the use of the method for preparing anhydrous hydrogen fluoride according to the above embodiments in the recycling and reuse of fluorosulfuric acid. This effectively achieves the recycling and reuse of fluorosulfuric acid, saving costs.

[0054] This disclosure allows for the preparation of anhydrous hydrogen fluoride using fluorinated sulfuric acid as a byproduct, achieving resource recycling and saving costs.

[0055] The embodiments of this disclosure are described in detail below. It should be noted that the embodiments described below are exemplary and are only used to explain this disclosure, and should not be construed as limiting this disclosure. In addition, unless otherwise specified, all reagents used in the following embodiments are commercially available or can be synthesized according to the methods described herein or known to others. For reaction conditions not listed, they are also readily available to those skilled in the art.

[0056] Example 1

[0057] This embodiment provides a method for preparing anhydrous hydrogen fluoride, including:

[0058] 1) A first fluorinated sulfuric acid (comprising 63 wt% sulfuric acid, 28.5 wt% fluorosulfonic acid, 3.5 wt% hydrogen fluoride, and the remainder being water) is introduced into a tubular mixer at a rate of 1 kg / h, and water at a rate of 0.5 kg / h for mixing and reaction. After mixing, the temperature inside the tubular mixer reaches 145°C, yielding a reaction solution containing hydrogen fluoride. It should be noted that the rate ratio of the first fluorinated sulfuric acid to water is equal to the mass ratio of the first fluorinated sulfuric acid to water.

[0059] 2) The above reaction solution is fed into a falling film evaporator for evaporation. The temperature is controlled at 145℃ and the pressure of the falling film evaporator is 1 kPa to obtain the evaporated liquid phase and the evaporated gas phase.

[0060] 3) The evaporated gas phase is washed in a scrubbing tower using a second fluorinated sulfuric acid (comprising 63 wt% sulfuric acid, 28.5 wt% fluorosulfonic acid, 3.5 wt% hydrogen fluoride, and the remainder being water). The scrubbing tower is set at 60°C and 0 kPa to remove impurities such as water and sulfuric acid from the evaporated gas phase. The weight ratio of the second fluorinated sulfuric acid to the evaporated gas phase is 10:1. The washed liquid phase is returned to step 1) and used as the first fluorinated sulfuric acid.

[0061] 4) The washed gas phase is condensed using a condenser to obtain liquid crude anhydrous hydrogen fluoride.

[0062] 5) The above-mentioned liquid crude anhydrous hydrogen fluoride is distilled and degassed in sequence using a distillation column and a degassing column to obtain anhydrous hydrogen fluoride product.

[0063] 6) The above-mentioned evaporated liquid phase is stripped in a stripping tower using hot air (temperature 80℃) to obtain a stripped gas phase and a stripped liquid phase. The liquid phase dilute sulfuric acid enters the stripping tower at a rate of 1.4 kg / h, the air flow rate is 8 L / min, the stripping tower temperature is 110℃, the gas phase forms hydrofluoric acid after passing through the absorption tower, and the liquid phase is dilute sulfuric acid (i.e., a byproduct).

[0064] Examples 2-20

[0065] The preparation method of this embodiment is basically the same as that of Example 1, with the only difference being as shown in Table 1 and Table 1 Continued.

[0066] Comparative Example 1

[0067] This comparative example uses the fluorite method to prepare anhydrous hydrogen fluoride, including the following steps:

[0068] The fluorite powder, preheated and dried by steam, is sent to a rotary reactor.

[0069] Fuming sulfuric acid and sulfuric acid from which HF in the tail gas has been absorbed by the sulfuric acid absorption tower are sent to a mixed acid tank, where they are mixed with dilute acid from a scrubbing tower. The mixed acid then enters a rotary reactor.

[0070] The rotary reactor is heated by a gasifier, using water gas indirectly heated via a jacket to meet the heat requirements of the reaction. In the rotary reactor, the jacket temperature is 550℃, and the material temperature is 320℃. The slag discharged from the reactor tail is neutralized with slaked lime to remove excess acid and then sent to a slag storage hopper via a slag elevator. The main gaseous product of the reaction is hydrogen fluoride. This gas first enters a scrubbing tower for dust removal and cooling. The gas temperature before entering the scrubbing tower is around 200℃, and the temperature after scrubbing is 120℃. The scrubbing liquid is sulfuric acid. At this point, a small amount of water in the gas is still in the form of water vapor mixed with the HF gas. The gas then sequentially enters the primary cooler, the first-stage HF condenser, and the second-stage HF condenser.

[0071] The condensate from the primary cooler is returned to the scrubbing tower at a gas temperature of 60°C. Its main component is HF. The condensate from the first-stage HF condenser passes through the coarse HF channel into a distillation column to remove heavy components such as H2SO4. The bottom temperature of the column is 30°C, and the main components are still H2SO4 and H2O. It is then returned to the scrubbing tower, where the top temperature is 19.5°C. The condensate then enters a degassing tower to remove light components such as SO2 and SiF4. In the degassing tower, the top temperature is below 10°C, and the bottom temperature is 19°C. The top product is SO2 and SiF4 gas, and the bottom product is anhydrous HF. Anhydrous HF is then transported to the tank farm for storage.

[0072] Comparative Example 2

[0073] This comparative example uses the fluorosilicic acid method to prepare anhydrous hydrogen fluoride. The steps are the same as those in Example 2 of CN107601434A for preparing hydrogen fluoride.

[0074] Table 1

[0075] Table 1 (continued)

[0076] The purity of the anhydrous hydrogen fluoride products prepared in Examples 1-20 and Comparative Examples 1-2 were tested, and the yield of anhydrous hydrogen fluoride was calculated. The results are shown in Table 2. The costs of the anhydrous hydrogen fluoride products prepared in Examples 1-20 and Comparative Examples 1-2 were statistically analyzed, and the results are shown in Table 2. The types of byproducts generated by the methods in Examples 1-20 and Comparative Examples 1-2 were statistically analyzed, and the concentrations of sulfuric acid and hydrogen fluoride in the dilute sulfuric acid byproduct were tested. The results are shown in Table 2.

[0077] Table 2

[0078] As can be seen from Table 2, the purity of the anhydrous hydrogen fluoride products prepared in Examples 1 to 20 of this disclosure is all above 99.91%, meeting the requirements for superior grade products, and the yield of the anhydrous hydrogen fluoride products prepared in Examples 1 to 20 is all above 83%.

[0079] As can be seen from Table 2, the main byproduct of Comparative Example 1 (fluorite method) is anhydrous fluoride gypsum, which has low utilization value and will pollute the environment if piled up. Moreover, compared with the preparation of anhydrous hydrogen fluoride by the fluorite method of Comparative Example 1, the methods of Examples 1-20 of this disclosure have lower costs, lower energy consumption, and less environmental pressure on the entire preparation process.

[0080] As can be seen from Table 2, the main byproducts of Comparative Example 2 (fluorosilicic acid method) are dilute sulfuric acid and silicon dioxide. Silicon dioxide easily clogs pipes, and the dilute sulfuric acid byproduct has a high hydrogen fluoride content, requiring nitration in a phosphate chemical plant. In contrast, the main byproduct of Examples 1-20 of this disclosure is dilute sulfuric acid, and the hydrogen fluoride content in the sulfuric acid byproduct is ≤0.2%, allowing for a wider range of applications than the sulfuric acid byproduct of Comparative Example 2.

[0081] Furthermore, as can be seen from Table 2, the amount of dilute sulfuric acid produced as a byproduct in Examples 1 to 20 of this disclosure is significantly reduced compared to Comparative Example 2.

[0082] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0083] Although embodiments of the present disclosure have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A method for preparing anhydrous hydrogen fluoride, wherein, include: The first fluorinated sulfuric acid was mixed with water and reacted to obtain a reaction solution containing hydrogen fluoride; The reaction solution containing hydrogen fluoride is evaporated to obtain an evaporated liquid phase and an evaporated gas phase; The evaporated gas phase is washed to obtain a washed gas phase; The washed gas phase was condensed to obtain anhydrous hydrogen fluoride.

2. The method according to claim 1, wherein, The first fluorinated sulfuric acid includes sulfuric acid, fluorosulfonic acid, and hydrogen fluoride.

3. The method according to claim 2, wherein, The first fluorinated sulfuric acid comprises 55wt% to 80wt% sulfuric acid, 15wt% to 35wt% fluorosulfonic acid, and 2wt% to 6wt% hydrogen fluoride.

4. The method according to any one of claims 1 to 3, wherein, The mass ratio of the first fluorinated sulfuric acid to the water is (1.7–2.65):1; And / or, the mixing reaction temperature is 130℃~150℃.

5. The method according to any one of claims 1 to 4, wherein, The temperature for evaporating the reaction solution containing hydrogen fluoride is 130℃~150℃, and the pressure is -3kPa~3kPa.

6. The method according to any one of claims 1 to 5, wherein, The evaporated gas phase was washed with a second fluorinated sulfuric acid.

7. The method according to claim 6, wherein, The washing temperature is 40℃~80℃, and the pressure is -3kPa~3kPa.

8. The method according to claim 6 or 7, wherein, The mass ratio of the second fluorinated sulfuric acid to the evaporated gas phase is (7-13):1; And / or, the second fluorinated sulfuric acid comprises 55wt% to 80wt% sulfuric acid, 15wt% to 35wt% fluorosulfonic acid, and 2wt% to 6wt% hydrogen fluoride.

9. The method according to any one of claims 6 to 8, wherein, The liquid phase after washing the evaporated gas phase with the second fluorinated sulfuric acid is returned to the step of mixing the first fluorinated sulfuric acid with water and used as the first fluorinated sulfuric acid.

10. An anhydrous hydrogen fluoride, wherein, It is prepared by any one of claims 1 to 9.

11. Use of a method for preparing anhydrous hydrogen fluoride according to any one of claims 1 to 9 in the recycling and reuse of fluorosulfuric acid.

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