Method for preparing anhydrous hydrogen fluoride, anhydrous hydrogen fluoride and application

Abstract

The invention discloses a method for preparing anhydrous hydrogen fluoride, anhydrous hydrogen fluoride and application, and the method comprises the following steps: mixing first fluorine-containing sulfuric acid with water for reaction to obtain a reaction solution containing hydrogen fluoride; evaporating the reaction liquid 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 is low in cost and high in economic benefit, the yield of the by-product sulfuric acid is about 1.5 times lower than that of a fluosilicic acid method, the application channel of the by-product sulfuric acid is wider than that of the by-product sulfuric acid of the fluosilicic acid method, and the environmental protection pressure in the preparation process is low. Meanwhile, anhydrous hydrogen fluoride is prepared from the by-product fluorine-containing sulfuric acid, so that recycling of resources is realized.

Description

Technical Field

[0001] The present application relates to the technical field of hydrogen fluoride preparation, and in particular to a method for preparing anhydrous hydrogen fluoride using fluorine-containing sulfuric acid, anhydrous hydrogen fluoride and uses thereof. Background Art

[0002] At present, the processes for preparing anhydrous hydrogen fluoride mainly include the fluorite method and the fluosilicic acid method. Among them, the fluorite method uses fluorite and sulfuric acid to react to produce anhydrous hydrogen fluoride, which is the mainstream process on the market. However, the fluorite method has the following disadvantages: 1) It needs to consume a large amount of concentrated sulfuric acid as raw material, resulting in high raw material costs; 2) Every ton of hydrogen fluoride produced will produce 3.6 tons of anhydrous fluoridized gypsum as a by-product. This by-product has low utilization value and will pollute the environment when piled up; 3) High-purity fluorite powder (more than 98%) is usually required. This high-purity fluorite is expensive, which increases the cost of raw materials. The technology of the fluosilicic acid method is relatively mature, but the investment cost of the fluosilicic acid method is large, the process flow is complicated, and a large amount of by-product fluorine-containing dilute sulfuric acid needs to rely on phosphorus chemical equipment for nitration, which has certain limitations, and the silicon dioxide produced during the production process is easy to clog the pipeline. Summary of the invention

[0003] The present application aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the purpose of the present application is to propose a method for preparing anhydrous hydrogen fluoride, anhydrous hydrogen fluoride and uses. The method of the present application uses fluorine-containing sulfuric acid to prepare anhydrous hydrogen fluoride, which has low cost and high economic benefits, and the amount of by-product sulfuric acid produced is about 1.5 times lower than that of the fluorosilicic acid method. The application channels of the by-product sulfuric acid are wider than those of the by-product sulfuric acid produced by the fluorosilicic acid method, and the environmental pressure during the preparation process is relatively small. At the same time, the present application uses by-product fluorine-containing sulfuric acid to prepare anhydrous hydrogen fluoride, which realizes the recycling and reuse of resources.

[0004] In one aspect of the present application, the present application proposes a method for preparing anhydrous hydrogen fluoride. According to an embodiment of the present application, the method comprises:

[0005] Mixing the first fluorine-containing sulfuric acid and water to react to obtain a reaction solution containing hydrogen fluoride;

[0006] Evaporating the reaction liquid containing hydrogen fluoride to obtain an evaporated liquid phase and an evaporated gas phase;

[0007] washing the evaporated gas phase to obtain a washed gas phase;

[0008] The washed gas phase is condensed to obtain anhydrous hydrogen fluoride.

[0009] According to the method for preparing anhydrous hydrogen fluoride in the embodiment of the present application, fluorine-containing sulfuric acid is used to prepare anhydrous hydrogen fluoride, which has low cost and high economic benefits, and the amount of byproduct sulfuric acid produced is about 1.5 times lower than that of the fluosilicic acid method, and the application channels of the byproduct sulfuric acid are wider than those of the byproduct sulfuric acid produced by the fluosilicic acid method, and the environmental pressure during the preparation process is relatively small. At the same time, the present application uses byproduct fluorine-containing sulfuric acid to prepare anhydrous hydrogen fluoride, which realizes the recycling and reuse of resources.

[0010] In addition, the method for preparing anhydrous hydrogen fluoride according to the above embodiment of the present application may also have the following additional technical features:

[0011] In some embodiments of the present application, the first fluorine-containing sulfuric acid includes sulfuric acid, fluorosulfonic acid, and hydrogen fluoride.

[0012] In some embodiments of the present application, the first fluorine-containing sulfuric acid includes 55 wt % to 80 wt % of sulfuric acid, 15 wt % to 35 wt % of fluorosulfonic acid, and 2 wt % to 6 wt % of hydrogen fluoride.

[0013] In some embodiments of the present application, the mass ratio of the first fluorine-containing sulfuric acid to the water is (1.7-2.65):1; and / or the temperature of the mixed reaction is 130°C-150°C.

[0014] In some embodiments of the present application, the temperature for evaporating the reaction liquid containing hydrogen fluoride is 130° C. to 150° C., and the pressure is -3 kPa to 3 kPa.

[0015] In some embodiments of the present application, the evaporated gas phase is washed with a second fluorine-containing sulfuric acid.

[0016] In some embodiments of the present application, the washing temperature is 40°C to 80°C, and the pressure is -3kPa to 3kPa.

[0017] In some embodiments of the present application, the mass ratio of the second fluorine-containing sulfuric acid to the evaporated gas phase is (7-13):1; and / or the second fluorine-containing sulfuric acid comprises 55wt%-80wt% of sulfuric acid, 15wt%-35wt% of fluorosulfonic acid, and 2wt%-6wt% of hydrogen fluoride.

[0018] In some embodiments of the present application, the liquid phase obtained by washing the evaporated gas phase with the second fluorine-containing sulfuric acid is returned to the step of mixing the first fluorine-containing sulfuric acid with water to be used as the first fluorine-containing sulfuric acid.

[0019] In the second aspect of the present application, the present application provides an anhydrous hydrogen fluoride. According to the embodiment of the present application, the anhydrous hydrogen fluoride is prepared by the method of the above embodiment. Therefore, the purity of the anhydrous hydrogen fluoride is relatively high, which can reach more than 99.99%.

[0020] In the third aspect of the present application, the present application proposes a method for preparing anhydrous hydrogen fluoride according to the above embodiment for use in recycling and reusing fluorosulfuric acid, thereby effectively realizing the recycling and reusing of fluorosulfuric acid and saving costs.

[0021] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0023] Figure 1 Schematic diagram of the process for preparing anhydrous hydrogen fluoride according to an embodiment of the present application. DETAILED DESCRIPTION

[0024] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0025] In one aspect of the present application, the present application proposes a method for preparing anhydrous hydrogen fluoride, see attached Figure 1 . According to an embodiment of the present application, the method includes: mixing a first fluorine-containing sulfuric acid with water to obtain a reaction liquid containing hydrogen fluoride; evaporating the reaction liquid 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; condensing the washed gas phase to obtain anhydrous hydrogen fluoride. Therefore, the method of the present application can use fluorine-containing sulfuric acid to prepare anhydrous hydrogen fluoride, which has low cost and high economic benefits, and the amount of by-product sulfuric acid produced is about 1.5 times lower than that of the fluorosilicic acid method. The application channels of the by-product sulfuric acid are wider than those of the by-product sulfuric acid produced by the fluorosilicic acid method, and the environmental pressure during the preparation process is relatively small. At the same time, the present application uses by-product fluorine-containing sulfuric acid to prepare anhydrous hydrogen fluoride, thereby realizing the recycling and reuse of resources.

[0026] The following is a detailed description of the principle by which the method for preparing anhydrous hydrogen fluoride proposed in the present application can achieve the above beneficial effects:

[0027] The present application uses fluorine-containing sulfuric acid and water to mix, and the fluorosulfonic acid in the fluorine-containing sulfuric acid reacts with water to generate hydrogen fluoride and sulfuric acid, and then the hydrogen fluoride in the sulfuric acid is vaporized by evaporation, and the hydrogen fluoride is washed, distilled, and degassed to obtain a qualified anhydrous hydrogen fluoride product. Compared with the fluorite method for preparing anhydrous hydrogen fluoride, the method of the present application has lower cost, lower energy consumption, and less environmental pressure in the entire preparation process. Compared with the preparation of anhydrous hydrogen fluoride by the fluosilicic acid method, first, the method of the present application has a lower investment cost; second, the amount of by-product sulfuric acid produced by the method of the present application is about 1.5 times lower than that of the fluosilicic acid method. The method of the present application produces about 10 tons of by-product sulfuric acid for preparing 1 ton of anhydrous hydrogen fluoride, while the fluosilicic acid method produces about 26 tons of by-product sulfuric acid for preparing 1 ton of anhydrous hydrogen fluoride; third, the hydrogen fluoride in the by-product sulfuric acid of the method of the present application is ≤0.2%, while the content of hydrogen fluoride in the by-product sulfuric acid of the fluosilicic acid method is 0.3% to 0.4%, therefore, the application channels of the by-product sulfuric acid of the method of the present application are wider than those of the by-product sulfuric acid of the fluosilicic acid method; fourth, the method of the present application does not produce by-product silicon dioxide, thereby avoiding the risk of system blockage; fifth, the process flow of the present application is relatively simple, avoiding complex operations; sixth, the yield of anhydrous hydrogen fluoride of the method of the present application reaches more than 90%, while the yield of anhydrous hydrogen fluoride of the fluosilicic acid method is only about 80%.

[0028] At the same time, the present application uses the byproduct fluorine-containing sulfuric acid to prepare anhydrous hydrogen fluoride, thereby realizing resource recycling and reuse. And the source of the byproduct fluorine-containing sulfuric acid is not particularly limited, for example, it can come from the PF5 preparation process, the fluorite preparation process or the fluorosilicic acid preparation process.

[0029] The method for preparing anhydrous hydrogen fluoride proposed by the present invention is described in detail below:

[0030] Specifically, refer to the attached Figure 1 The above method for preparing anhydrous hydrogen fluoride comprises the following steps:

[0031] S100: mixing a first fluorine-containing sulfuric acid with water to react to obtain a reaction solution containing hydrogen fluoride;

[0032] In this step, the first fluorine-containing sulfuric acid is mixed with water, and the fluorosulfonic acid in the fluorine-containing sulfuric acid reacts with the water to generate hydrogen fluoride and sulfuric acid, thereby obtaining a reaction solution containing hydrogen fluoride. The reaction equation is as follows:

[0033] HSO3F+H2O=H2SO4+HF

[0034] In the embodiment of the present application, the first fluorine-containing sulfuric acid can use byproduct fluorine-containing sulfuric acid, and the present application uses the byproduct to prepare anhydrous hydrogen fluoride, thereby realizing resource recycling and reuse. The first fluorine-containing sulfuric acid includes sulfuric acid, fluorosulfonic acid, hydrogen fluoride and water.

[0035] According to some specific embodiments of the present application, the first fluorine-containing sulfuric acid includes 55wt% to 80wt% of sulfuric acid (as an example, it can be 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, etc.), 15wt% to 35wt% of fluorosulfonic acid (as an example, it can be 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, etc.), 2wt% to 6wt% of hydrogen fluoride (as an example, it can be 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, etc.), and the rest is water. Therefore, the fluorosulfonic acid in the first fluorine-containing sulfuric acid can effectively react with water to generate hydrogen fluoride and sulfuric acid.

[0036] In an embodiment of the present application, a tubular mixer can be used to mix the first fluorine-containing sulfuric acid with water. According to some further specific embodiments of the present application, the mass ratio of the first fluorine-containing sulfuric acid to water is (1.7-2.65):1, and as an example, it can be 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., thereby further ensuring that the fluorosulfonic acid in the first fluorine-containing sulfuric acid can fully react with water to generate hydrogen fluoride and sulfuric acid.

[0037] In the embodiments of the present application, a large amount of heat is released during the reaction of the fluorosulfonic acid in the first fluorine-containing sulfuric acid with water to generate hydrogen fluoride and sulfuric acid, and a portion of heat is also released during the mixing process of the first fluorine-containing sulfuric acid with water, which can increase the temperature of the reaction system to 130°C to 150°C (eg, 130°C, 135°C, 140°C, 145°C, 150°C, etc.), thereby further promoting the reaction of the fluorosulfonic acid with water.

[0038] S200: evaporating the reaction liquid containing hydrogen fluoride to obtain an evaporated liquid phase and an evaporated gas phase;

[0039] In this step, a falling film evaporator may be used to evaporate the reaction liquid containing hydrogen fluoride to obtain an evaporated liquid phase and an evaporated gas phase, wherein the evaporated gas phase comprises 95 wt% to 99 wt% of hydrogen fluoride (as an example, it may be 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, etc.), 1 wt% to 5 wt% of water (as an example, it may be 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, etc.), 0.5 wt% to 2 wt% of sulfuric acid (as an example, it may be 0.5 wt%, 1 wt%, 1.5wt%, 2wt%, etc.), and after evaporation, the liquid phase includes 60wt% to 75wt% of sulfuric acid (as an example, it can be 60wt%, 62wt%, 64wt%, 66wt%, 68wt%, 70wt%, 72wt%, 75wt%, etc.), 0.5wt% to 2wt% of hydrogen fluoride (as an example, it can be 0.5wt%, 1wt%, 1.5wt%, 2wt%, etc.), and 25wt% to 40wt% of water (as an example, it can be 25wt%, 30wt%, 35wt%, 40wt%, etc.).

[0040] According to some specific embodiments of the present application, the temperature for evaporating the reaction liquid containing hydrogen fluoride is 130°C to 150°C (as an example, it can be 130°C, 135°C, 140°C, 145°C, 150°C, etc.), and the pressure is -3kPa to 3kPa (as an example, it can be -3kPa, -2kPa, -1kPa, 0kPa, 1kPa, 2kPa, 3kPa, etc.), that is, the temperature of the falling film evaporator is controlled at 130°C to 150°C and the pressure is controlled at -3kPa to 3kPa. By limiting the temperature and pressure of the falling film evaporator to the above range, it can be further ensured that the hydrogen fluoride in the reaction liquid effectively enters the gas phase after evaporation.

[0041] S300: washing the evaporated gas phase to obtain a washed gas phase;

[0042] In this step, the evaporated gas phase can be washed in a washing tower using a second fluorine-containing sulfuric acid, so that impurities such as moisture and sulfuric acid in the evaporated gas phase can be washed into the second fluorine-containing sulfuric acid to obtain a washed gas phase and a washed liquid phase.

[0043] According to some specific embodiments of the present application, the temperature in the above-mentioned washing tower is 40°C to 80°C (as an example, it can be 40°C, 50°C, 60°C, 70°C, 80°C, etc.), and the pressure is -3kPa to 3kpa (as an 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-mentioned range, it can be further ensured that impurities such as moisture and sulfuric acid in the gas phase after evaporation are washed into the second fluorine-containing sulfuric acid.

[0044] According to some further specific embodiments of the present application, the mass ratio of the second fluorine-containing sulfuric acid to the evaporated gas phase is (7-13):1, and as an example, it can be 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, etc. By limiting the mass ratio of the second fluorine-containing sulfuric acid to the evaporated gas phase within the above range, it can be further ensured that the impurities such as moisture and sulfuric acid in the evaporated gas phase are washed into the second fluorine-containing sulfuric acid. The present application can calculate the mass ratio of the second fluorine-containing sulfuric acid to the evaporated gas phase by detecting the content of moisture and sulfuric acid in the liquid in the washing tower.

[0045] In the embodiment of the present application, the second fluorine-containing sulfuric acid can be a byproduct fluorine-containing sulfuric acid, and the present application uses the byproduct to wash the vapor phase after evaporation, further realizing the recycling and reuse of resources. The first fluorine-containing sulfuric acid includes sulfuric acid, fluorosulfonic acid, hydrogen fluoride and water.

[0046] According to some other specific embodiments of the present application, the second fluorine-containing sulfuric acid includes 55wt% to 80wt% of sulfuric acid (as an example, it can be 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, etc.), 15wt% to 35wt% of fluorosulfonic acid (as an example, it can be 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, etc.), 2wt% to 6wt% of hydrogen fluoride (as an example, it can be 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, etc.), and the rest is water.

[0047] In the embodiments of the present application, the washed liquid phase includes 60wt% to 80wt% of sulfuric acid, 15wt% to 30wt% of fluorosulfonic acid, 2wt% to 6wt% of hydrogen fluoride and 3wt% to 8wt% of water. The composition is not much different from the composition of the first fluorine-containing sulfuric acid. Therefore, as some preferred embodiments, the washed liquid phase can be returned to step S100 and used as the first fluorine-containing sulfuric acid, thereby further realizing the recycling and reuse of resources.

[0048] S400: condensing the washed gas phase to obtain anhydrous hydrogen fluoride;

[0049] In this step, a condenser can be used to condense the washed gas phase to obtain crude liquid anhydrous hydrogen fluoride. The composition of the crude liquid anhydrous hydrogen fluoride is substantially the same as that of the washed gas phase, except that the gas phase is changed into a liquid phase.

[0050] According to some further specific embodiments of the present application, the above method may further include:

[0051] S500: The anhydrous hydrogen fluoride obtained in S400 is distilled and degassed in sequence to obtain fine anhydrous hydrogen fluoride.

[0052] In this step, a distillation tower can be used to sequentially distill the crude liquid anhydrous hydrogen fluoride to obtain liquid anhydrous hydrogen fluoride, and then a degassing tower is used to degas the liquid anhydrous hydrogen fluoride to obtain fine anhydrous hydrogen fluoride gas. It is calculated that the yield of anhydrous hydrogen fluoride in the method of the present application reaches more than 90%.

[0053] According to some further specific embodiments of the present application, the above method may further include:

[0054] S600: stripping the evaporated liquid phase in a stripping tower using air to obtain a stripped gas phase and a stripped liquid phase;

[0055] In this step, air is used to strip the evaporated liquid phase in a stripping tower so that the hydrogen fluoride in the evaporated liquid phase is separated from the evaporated liquid phase to obtain a stripped gas phase and a stripped liquid phase. The stripped gas phase passes through an absorption tower to form hydrofluoric acid, which can be used as a commercial product.

[0056] According to some further specific embodiments of the present application, the temperature of the air is 40°C to 100°C (eg, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, etc.), and the temperature in the stripping tower is 100°C to 120°C (eg, 100°C, 105°C, 110°C, 115°C, 120°C, etc.). By limiting the temperature of the air and the temperature in 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 a stripped gas phase.

[0057] In the embodiments of the present application, the above-mentioned liquid phase after stripping is the only by-product in the method of the present application, and the amount of by-products produced in the method of the present application is about 1.5 times lower than that of the fluorosilicic acid method. The method of the present application produces about 10 tons of by-product sulfuric acid for preparing 1 ton of anhydrous hydrogen fluoride, while the fluorosilicic acid method produces about 26 tons of by-product sulfuric acid for preparing 1 ton of anhydrous hydrogen fluoride.

[0058] In the embodiments of the present application, the liquid phase after stripping (i.e., the by-product) includes 60wt% to 75wt% of sulfuric acid and ≤0.2wt% of hydrogen fluoride, that is, the hydrogen fluoride in the by-product sulfuric acid of the method of the present application is ≤0.2%, while the content of hydrogen fluoride in the by-product sulfuric acid of the fluosilicic acid method is 0.3% to 0.4%. Therefore, the application channels of the by-product sulfuric acid of the method of the present application are wider than those of the by-product sulfuric acid of the fluosilicic acid method.

[0059] In the second aspect of the present application, the present application provides an anhydrous hydrogen fluoride. According to the embodiment of the present application, the anhydrous hydrogen fluoride is prepared by the method of the above embodiment. Therefore, the purity of the anhydrous hydrogen fluoride is relatively high, which can reach more than 99.99%.

[0060] According to some specific embodiments of the present application, the anhydrous hydrogen fluoride includes 0.5 to 3 ppm of phosphate impurities and 8 to 12 ppm of sulfate impurities.

[0061] The anhydrous hydrogen fluoride prepared by the fluorite method mainly includes impurities such as fluorosilicic acid, calcium sulfate, heavy metal ions, silicon compounds, phosphates, etc. The anhydrous hydrogen fluoride prepared by the fluorosilicic acid method mainly includes anionic and cationic impurities formed by silicon, phosphorus, nitrogen, chlorine, sulfur, arsenic, boron and metal elements.

[0062] Anhydrous hydrogen fluoride is an important chemical raw material, widely used in many fields, such as refrigerant production, fluorine-containing polymer materials, chemical and inorganic fluoride production, integrated circuit manufacturing, metal surface treatment, etc.

[0063] In the third aspect of the present application, the present application proposes a method for preparing anhydrous hydrogen fluoride according to the above embodiment for use in recycling and reusing fluorosulfuric acid, thereby effectively realizing the recycling and reusing of fluorosulfuric acid and saving costs.

[0064] The present application can use the by-product fluorine-containing sulfuric acid to prepare anhydrous hydrogen fluoride, thereby realizing the recycling and reuse of resources and saving costs.

[0065] The embodiments of the present application are described in detail below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. In addition, unless otherwise explicitly stated, all reagents used in the following embodiments are commercially available or can be synthesized according to this article or known methods, and the reaction conditions not listed are also easily available to those skilled in the art.

[0066] Example 1

[0067] This embodiment provides a method for preparing anhydrous hydrogen fluoride, comprising:

[0068] 1) A first fluorine-containing 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 reacting, and after mixing, the temperature in the tubular mixer reaches 145° C. to obtain a reaction liquid containing hydrogen fluoride. It should be noted that the rate ratio of the first fluorine-containing sulfuric acid to water is equal to the mass ratio of the first fluorine-containing sulfuric acid to water.

[0069] 2) The reaction liquid is sent to a falling film evaporator for evaporation. The temperature is controlled at 145° C. and the pressure of the falling film evaporator is 1 kPa to obtain a liquid phase and a gas phase after evaporation.

[0070] 3) The evaporated gas phase is washed in a washing tower using a second fluorine-containing sulfuric acid (comprising 63 wt% sulfuric acid, 28.5 wt% fluorosulfonic acid, 3.5 wt% hydrogen fluoride, and the remainder being water), the temperature of the washing tower being 60° C., the pressure of the washing tower being 0 kPa, so as to wash away impurities such as moisture and sulfuric acid in the evaporated gas phase, wherein the weight ratio of the second fluorine-containing sulfuric acid to the evaporated gas phase is 10:1. The washed liquid phase is returned to step 1) and used as the first fluorine-containing sulfuric acid.

[0071] 4) Using a condenser to condense the washed gas phase to obtain liquid crude anhydrous hydrogen fluoride.

[0072] 5) Using a distillation tower and a degassing tower in sequence to distill and degas the above-mentioned crude liquid anhydrous hydrogen fluoride to obtain an anhydrous hydrogen fluoride product.

[0073] 6) Using hot air (temperature of 80° C.) to strip the above-mentioned evaporated liquid phase in a stripping tower to obtain a stripped gas phase and a stripped liquid phase, wherein 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° C., the gas phase passes through the absorption tower to form hydrofluoric acid, and the liquid phase is dilute sulfuric acid (i.e., a by-product).

[0074] Embodiments 2 to 20

[0075] The preparation methods of this embodiment are basically the same as those of embodiment 1, with the only difference being as shown in Table 1 and Table 1 continuation.

[0076] Comparative Example 1

[0077] This comparative example adopts the fluorite method to prepare anhydrous hydrogen fluoride, comprising the following steps:

[0078] The steam-preheated and dried fluorite powder is sent to the rotary reactor.

[0079] The fuming sulfuric acid and the sulfuric acid from the sulfuric acid absorption tower that has absorbed HF in the tail gas are sent to the mixed acid tank, where they are mixed with the dilute acid from the scrubbing tower. The mixed acid enters the rotary reactor.

[0080] The rotary reactor is heated by a gasifier, and water gas is used for indirect heating through the jacket to meet the heat required for the reaction. In the rotary reactor, the temperature of the jacket is 550°C, the temperature of the material is 320°C, and the slag discharged from the tail of the reactor is neutralized with slaked lime to remove excess acid and then sent to the slag storage hopper through the slag elevator. The gas product of the reaction is mainly hydrogen fluoride. This gas first enters the scrubber for dust removal and cooling. The gas temperature before entering the scrubber is about 200°C, and the temperature after scrubbing is 120°C. The scrubbing liquid is sulfuric acid. At this time, a small amount of water in the gas is still mixed with HF gas in the state of water vapor, and then enters the primary cooler, HF primary condenser and HF secondary condenser in turn.

[0081] The condensate obtained in the primary cooler returns to the scrubber, and the gas temperature is 60°C. The main component is HF. The condensate obtained in the primary HF condenser enters the distillation tower through the crude HF groove to remove heavy components such as H2SO4. The bottom temperature is 30°C. The main components are H2SO4 and H2O. It returns to the scrubber, and the top temperature is 19.5°C. It enters the degassing tower to remove light components such as SO2 and SiF4. In the degassing tower, the top temperature is below 10°C, the bottom temperature is 19°C, the top of the tower is SO2 and SiF4 gas, and the bottom is the product anhydrous HF. Anhydrous HF is transported to the tank area for storage.

[0082] Comparative Example 2

[0083] This comparative example adopts the fluorosilicic acid method to prepare anhydrous hydrogen fluoride, and its steps are the same as the preparation method of Example 2 in CN107601434A to prepare hydrogen fluoride.

[0084] Table 1

[0085]

[0086] Table 1 continued

[0087]

[0088]

[0089] The purity of the anhydrous hydrogen fluoride products prepared in Examples 1 to 20 and Comparative Examples 1 to 2 was tested, and the yield of anhydrous hydrogen fluoride was calculated, and the results are shown in Table 2. The costs of the anhydrous hydrogen fluoride products prepared in Examples 1 to 20 and Comparative Examples 1 to 2 were statistically analyzed, and the results are shown in Table 2. The types of by-products produced by the methods of Examples 1 to 20 and Comparative Examples 1 to 2 were statistically analyzed, and the results are shown in Table 2. The mass of sulfuric acid, a by-product produced by the methods of Examples 1 to 20 and Comparative Examples 1 to 2, was statistically analyzed, and the concentration of sulfuric acid and the concentration of hydrogen fluoride in the by-product dilute sulfuric acid were tested, and the results are shown in Table 2.

[0090] Table 2

[0091]

[0092]

[0093] It can be seen from Table 2 that the purity of the anhydrous hydrogen fluoride products prepared in Examples 1 to 20 of the present application is above 99.91%, reaching the requirements of premium products, and the yields of the anhydrous hydrogen fluoride products prepared in Examples 1 to 20 are all above 83%.

[0094] As can be seen from Table 2, the main by-product of Comparative Example 1 (fluorite method) is anhydrous fluoridized gypsum, which has low utilization value and will pollute the environment when piled up. In addition, compared with the preparation of anhydrous hydrogen fluoride by the fluorite method of Comparative Example 1, the methods of Examples 1 to 20 of the present application have lower costs, lower energy consumption, and less environmental pressure in the entire preparation process.

[0095] As can be seen from Table 2, the main by-products of Comparative Example 2 (fluorosilicic acid method) are dilute sulfuric acid and silicon dioxide. Silicon dioxide is easy to clog the pipeline, and the content of hydrogen fluoride in the by-product dilute sulfuric acid is high, which requires nitration by a phosphorus chemical plant. The main by-products of Examples 1 to 20 of the present application are dilute sulfuric acid, and the content of hydrogen fluoride in the by-product sulfuric acid is ≤0.2%, and its application channels are wider than those of the by-product sulfuric acid in Comparative Example 2.

[0096] In addition, it can be seen from Table 2 that, compared with Comparative Example 2, the amount of by-product dilute sulfuric acid produced in Examples 1 to 20 of the present application is significantly reduced.

[0097] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0098] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for preparing anhydrous hydrogen fluoride, characterized in that: include: Mixing the first fluorine-containing sulfuric acid and water to react to obtain a reaction solution containing hydrogen fluoride; Evaporating the reaction liquid 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; The washed gas phase is condensed to obtain anhydrous hydrogen fluoride.

2. The method according to claim 1, characterized in that The first fluorine-containing sulfuric acid includes sulfuric acid, fluorosulfonic acid, and hydrogen fluoride.

3. The method according to claim 2, characterized in that The first fluorine-containing sulfuric acid comprises 55 wt % to 80 wt % of sulfuric acid, 15 wt % to 35 wt % of fluorosulfonic acid, and 2 wt % to 6 wt % of hydrogen fluoride.

4. The method according to claim 1, characterized in that The mass ratio of the first fluorine-containing sulfuric acid to the water is (1.7-2.65):1; And / or, the mixed reaction temperature is 130°C to 150°C.

5. The method according to claim 1, characterized in that: The temperature for evaporating the reaction liquid containing hydrogen fluoride is 130° C. to 150° C., and the pressure is -3 kPa to 3 kPa.

6. The method according to claim 1, characterized in that The evaporated gas phase is washed with a second fluorine-containing sulfuric acid.

7. The method according to claim 6, characterized in that The washing temperature is 40°C to 80°C, and the pressure is -3kPa to 3kPa.

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

9. The method according to claim 6, characterized in that The liquid phase obtained by washing the evaporated gas phase with the second fluorine-containing sulfuric acid is returned to the step of mixing the first fluorine-containing sulfuric acid with water and used as the first fluorine-containing sulfuric acid.

10. Anhydrous hydrogen fluoride, characterized in that: The method according to any one of claims 1 to 9 is used to prepare the present invention.

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

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