A method for purifying electronic grade hydrochloric acid

Abstract

The application discloses a method for purifying electronic-grade hydrochloric acid, which uses industrial waste gaseous hydrochloric acid as raw material, removes chlorine through a chlorine removal tower after preliminary filtration, removes reducing substances through a potassium permanganate hydrochloric acid solution, avoids subsequent influences on separation of the hydrochloric acid, is further separated through different resins after preliminary gas separation, low temperature and / or pressurization into liquid state, and removal of metal, organic and other impurities, and each adsorption column can be regenerated through elution; liquid-state hydrochloric acid after adsorption through multiple-stage adsorption columns is added with a small amount of calcium chloride to improve the concentration of the hydrochloric acid and improve gaseous conversion efficiency; the system property is optimized through oxidation treatment to eliminate inhibiting factors of resin adsorption, further improve impurity removal efficiency, and avoid limitations of a single adsorption method; the multiple-stage and multiple adsorption mechanisms are combined to efficiently remove impurities, improve purification efficiency, and improve product quality.

Description

Technical Field

[0001] This invention relates to the field of hydrochloric acid purification technology, specifically a method for purifying electronic-grade hydrochloric acid. Background Technology

[0002] Electronic-grade hydrochloric acid is widely used in chip surface cleaning, etching, and drying processes, and its purity directly affects the yield and electrical performance of integrated circuits. As semiconductor processes evolve towards the nanoscale, the requirements for hydrochloric acid purity are becoming increasingly stringent, necessitating the deep removal of impurities such as metals, particles, and moisture.

[0003] Existing purification technologies mainly include distillation, ion exchange, and extraction, but all have limitations: traditional distillation easily forms azeotropes, resulting in low yields and difficulty in reducing metallic impurities to the ppt level; single ion exchange methods suffer from poor resin selectivity and insufficient stability under strong acid conditions, leading to inadequate purification depth; extraction methods carry the risk of organic phase residues and are complex processes requiring significant equipment investment. Therefore, developing an efficient, stable method for purifying electronic-grade hydrochloric acid with low impurity content has become a pressing technical problem for the industry. Summary of the Invention

[0004] The purpose of this invention is to provide a method for purifying electronic-grade hydrochloric acid to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for purifying electronic-grade hydrochloric acid, comprising the following steps: (1) Under the conditions of temperature 25℃ and pressure 30~50kPa, hydrochloric acid gas was filtered to obtain pretreated hydrochloric acid gas; (2) Under the conditions of temperature 25℃ and pressure 20~50kPa, the pretreated hydrochloric acid gas is passed through the dechlorination tower and then enters the acid rough washing tower. After passing through the acid rough washing tower, the hydrochloric acid gas is subjected to low temperature and / or pressure to obtain liquid hydrochloric acid. (3) Liquid hydrochloric acid flows sequentially through the first-stage adsorption column, the second-stage adsorption column, and the third-stage adsorption column, with the flow rate controlled at 2-5 BV / h and the temperature at 20-25℃. The first-stage adsorption column is filled with dithiocarbamic acid chelating resin, the second-stage adsorption column is filled with carboxylic acid weak acid cation resin, and the third-stage adsorption column is filled with anion exchange resin and macroporous adsorption resin. (4) Calcium chloride (mass ratio of hydrochloric acid solution to calcium chloride is 100-1000:1) is added to the hydrochloric acid solution after passing through the three-stage adsorption column. After mixing evenly, gaseous hydrochloric acid is obtained by evaporation. The gaseous hydrochloric acid is then dehydrated by countercurrent contact with concentrated sulfuric acid to remove water to ≤5ppm. After demisting with a demister, purified gaseous hydrochloric acid is obtained. The liquid-to-gas ratio is controlled at 2-4:1 during dehydration. (5) The purified gaseous hydrochloric acid is sent into the falling film absorption tower and comes into countercurrent contact with ultrapure water. The remaining gas is cooled by circulation and then filtered through a 0.05μm polytetrafluoroethylene microporous membrane terminal to obtain electronic grade hydrochloric acid.

[0006] Furthermore, in step (2), a stannous chloride solution is provided in the dechlorination tower, and a potassium permanganate hydrochloric acid solution is provided in the acid coarse washing tower.

[0007] Furthermore, step (3) also includes the following steps: oxidizing the effluent from the secondary adsorption column, wherein the oxidation treatment method is: adding 30% hydrogen peroxide solution by mass and stirring for 10-20 min; the volume ratio of the effluent from the secondary adsorption column to the hydrogen peroxide solution is 1:800-1:1000.

[0008] Furthermore, the filling volume ratio of the primary adsorption column, the secondary adsorption column, and the tertiary adsorption column in step (3) is 2-3:3-4:4-6.

[0009] Furthermore, in step (3), multiple primary, secondary, and tertiary adsorption columns are provided and connected in parallel. This avoids production interruptions due to adsorption saturation and enables continuous purification.

[0010] Furthermore, in step (5), the liquid-to-gas ratio in the countercurrent contact is 1:0.5-1.2.

[0011] Furthermore, the electronic-grade hydrochloric acid meets the following specifications: concentration 36.5-37.0 wt%, total metal impurities ≤100 ppt, particle size (≥0.5 μm) ≤3 pcs / mL, and color ≤5.

[0012] Compared with the prior art, the beneficial effects of the present invention are: This invention discloses a method for purifying electronic-grade hydrochloric acid. The method uses industrial waste gaseous hydrochloric acid as raw material. After preliminary filtration, the acid is removed by a dechlorination tower. Then, it is passed through a potassium permanganate hydrochloric acid solution to remove reducing substances (sulfur-containing gases, carbon dioxide, nitrogen oxides, arsenic chloride, etc.) to avoid affecting the subsequent separation of hydrochloric acid.

[0013] This invention involves initial gas separation followed by low-temperature and / or pressurized liquidization for further efficient separation using different resins to remove impurities such as metals and organic compounds. First, the primary adsorption column is filled with a dithiocarbamate-type chelating resin, preferentially adsorbing heavy metal ions such as iron and copper. The secondary adsorption column is filled with a carboxylic acid-type weak acid cation resin to further remove residual metal cations. The tertiary adsorption column is filled with anion exchange resin and macroporous adsorption resin for deep adsorption of chloride ions and organic impurities. Each adsorption column can be eluted and regenerated for reuse.

[0014] In this invention, a small amount of calcium chloride is added to the liquid hydrochloric acid after adsorption by a multi-stage adsorption column. Due to its hygroscopicity, the concentration of hydrochloric acid is increased, thereby improving the gaseous conversion efficiency.

[0015] This invention optimizes the system properties through oxidation treatment, eliminates inhibitory factors on resin adsorption, further improves impurity removal efficiency, and avoids the limitations of a single adsorption method.

[0016] This invention combines multiple adsorption mechanisms at various stages to efficiently remove impurities, thereby improving purification efficiency and product quality. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1

[0018] A method for purifying electronic-grade hydrochloric acid includes the following steps: (1) Under the conditions of temperature 25℃ and pressure 35kPa, hydrochloric acid gas was filtered to obtain pretreated hydrochloric acid gas; (2) Under the conditions of temperature 25℃ and pressure 35kPa, the pretreated hydrochloric acid gas is passed through the dechlorination tower and then enters the acid rough washing tower. The hydrochloric acid gas after passing through the acid rough washing tower is compressed at low temperature to obtain liquid hydrochloric acid. The dechlorination tower is equipped with stannous chloride solution and the acid rough washing tower is equipped with potassium permanganate hydrochloric acid solution. When the stannous chloride content is below 2% or the product fails to meet chlorine standards, replace the reactor solution and replenish with fresh stannous chloride solution. When the potassium permanganate content is below 1% or the product exceeds the arsenic standard, replace the reactor solution and replenish with potassium permanganate solution.

[0019] The equation for chlorine removal is: Cl₂ + SnCl₂ = SnCl₄ Equation for arsenic removal using potassium permanganate: 10AsCL3+4KMnO4+38HCl=10KAsCl6+4MnCl2+19H2O 2MnO 4- +5AsO3 3- +6H + =5AsO4 3- +2Mn 2+ +3H2O (As 3+ →As 5+ ) (3) The pretreated hydrochloric acid solution was flowed sequentially through a three-stage adsorption column at a flow rate of 3 BV / h and a temperature of 20°C. The volume ratio of the first-stage adsorption column, the second-stage adsorption column, and the third-stage adsorption column was 2:3:5. The third-stage adsorption column was filled with anion exchange resin and macroporous adsorption resin at a volume ratio of 1:2.

[0020] Add 30% hydrogen peroxide solution (by mass) to the effluent from the second adsorption column at a volume ratio of 1:800, stir for 15 min to complete the chemical environment reconstruction; (4) Calcium chloride (the mass ratio of hydrochloric acid solution to calcium chloride is 500:1, calcium chloride) is added to the hydrochloric acid solution after passing through the three-stage adsorption column. After mixing evenly, gaseous hydrochloric acid is obtained by evaporation. The gaseous hydrochloric acid is then dehydrated by countercurrent contact with 98% concentrated sulfuric acid. The water content is removed to below 3 ppm by countercurrent contact at a mass ratio of 1:10 for 45 min. The solution is then filtered through a 0.05 μm polytetrafluoroethylene microporous membrane to obtain electronic grade hydrochloric acid product. (5) Resin regeneration: After use, the adsorption column is eluted with a 6wt% dilute hydrochloric acid solution. The eluent is concentrated and recycled for raw material preparation.

[0021] The electronic-grade hydrochloric acid prepared in this embodiment has the following specifications: concentration 36.4 wt%, total metal impurities 10 ppt, particles (≥0.5 μm) 3 / mL, and color (APHA) 3, which fully meets the application standards of the semiconductor industry. Example 2

[0022] A method for purifying electronic-grade hydrochloric acid includes the following steps: Steps (1) and (2) are the same as in Example 1. (3) The pretreated hydrochloric acid solution was flowed sequentially through a three-stage adsorption column at a flow rate of 5 BV / h and a temperature of 25°C. The volume ratio of the first-stage adsorption column, the second-stage adsorption column, and the third-stage adsorption column was 3:4:5. The third-stage adsorption column was filled with anion exchange resin and macroporous adsorption resin at a volume ratio of 1:2.

[0023] Add 30% hydrogen peroxide solution (by mass) to the effluent from the second adsorption column at a volume ratio of 1:500, stir for 15 min, and complete the chemical environment reconstruction. (4) Calcium chloride (mass ratio of hydrochloric acid solution to calcium chloride is 500:1) is added to the hydrochloric acid solution after passing through the three-stage adsorption column. After mixing evenly, gaseous hydrochloric acid is obtained by evaporation. The gaseous hydrochloric acid is then dehydrated by countercurrent contact with 98% concentrated sulfuric acid. The water content is removed to below 3 ppm by countercurrent contact at a mass ratio of 1:10 for 45 min. The solution is then filtered through a 0.05 μm polytetrafluoroethylene microporous membrane to obtain electronic grade hydrochloric acid product. (5) Resin regeneration: After use, the adsorption column is eluted with a 6wt% dilute hydrochloric acid solution. The eluent is concentrated and recycled for raw material preparation.

[0024] The electronic-grade hydrochloric acid product prepared in this embodiment has the following specifications: concentration 37wt%, total metal impurities 25ppt, particles (≥0.5μm) 4 / mL, and color (APHA) 3, which fully meets the application standards of the semiconductor industry. Example 3

[0025] A method for purifying electronic-grade hydrochloric acid includes the following steps: Steps (1) and (2) are the same as in Example 1. (3) The pretreated hydrochloric acid solution was flowed sequentially through a three-stage adsorption column at a flow rate of 4 BV / h and a temperature of 25°C. The volume ratio of the first-stage adsorption column, the second-stage adsorption column, and the third-stage adsorption column was 2:3:5. The third-stage adsorption column was filled with anion exchange resin and macroporous adsorption resin at a volume ratio of 1:2.

[0026] Add 30% hydrogen peroxide solution (by mass) to the effluent from the second adsorption column at a volume ratio of 1:1000, stir for 15 min to complete the chemical environment reconstruction; (4) Calcium chloride (mass ratio of hydrochloric acid solution to calcium chloride is 1000:1) is added to the hydrochloric acid solution after passing through the three-stage adsorption column. After mixing evenly, gaseous hydrochloric acid is obtained by evaporation. The gaseous hydrochloric acid is then dehydrated by countercurrent contact with 98% concentrated sulfuric acid. The water content is removed to below 3 ppm by countercurrent contact at a mass ratio of 1:10 for 45 min. The solution is then filtered through a 0.05 μm polytetrafluoroethylene microporous membrane to obtain electronic grade hydrochloric acid product. (5) Resin regeneration: After use, the adsorption column is eluted with a 6wt% dilute hydrochloric acid solution. The eluent is concentrated and recycled for raw material preparation.

[0027] The electronic-grade hydrochloric acid prepared in this embodiment has the following specifications: concentration 36.9 wt%, total metal impurities 30 ppt, particles (≥0.5 μm) 4 / mL, and color (APHA) 2, which fully meets the application standards of the semiconductor industry.

[0028] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0029] It should be noted that the above content merely illustrates the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, various improvements and modifications can be made without departing from the principle of the present invention, and all such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. A method for purifying electronic-grade hydrochloric acid, characterized in that, Includes the following steps: (1) Under the conditions of temperature 25℃ and pressure 30~50kPa, hydrochloric acid gas was filtered to obtain pretreated hydrochloric acid gas; (2) Under the conditions of temperature 25℃ and pressure 20~50kPa, the pretreated hydrochloric acid gas is passed through the dechlorination tower and then enters the acid rough washing tower. After passing through the acid rough washing tower, the hydrochloric acid gas is subjected to low temperature and / or pressure to obtain liquid hydrochloric acid. (3) Liquid hydrochloric acid flows sequentially through the first-stage adsorption column, the second-stage adsorption column, and the third-stage adsorption column, with the flow rate controlled at 2-5 BV / h and the temperature at 20-25℃. The first-stage adsorption column is filled with dithiocarbamic acid chelating resin, the second-stage adsorption column is filled with carboxylic acid weak acid cation resin, and the third-stage adsorption column is filled with anion exchange resin and macroporous adsorption resin. (4) Calcium chloride is added to the hydrochloric acid solution after passing through the three-stage adsorption column. After mixing evenly, gaseous hydrochloric acid is obtained by evaporation. The gaseous hydrochloric acid is then dehydrated by countercurrent contact with concentrated sulfuric acid to remove water to ≤5ppm. After demisting with a demister, purified gaseous hydrochloric acid is obtained. The liquid-to-gas ratio is controlled at 2-4:1 during dehydration. (5) The purified gaseous hydrochloric acid is sent into the falling film absorption tower and comes into countercurrent contact with ultrapure water. The remaining gas is cooled by circulation and then filtered through a 0.05μm polytetrafluoroethylene microporous membrane terminal to obtain electronic grade hydrochloric acid.

2. The method for purifying electronic-grade hydrochloric acid according to claim 1, characterized in that, In step (2), a stannous chloride solution is provided in the dechlorination tower, and a potassium permanganate hydrochloric acid solution is provided in the acid coarse washing tower.

3. The method for purifying electronic-grade hydrochloric acid according to claim 1, characterized in that, Step (3) also includes the following steps: oxidizing the effluent from the secondary adsorption column. The oxidation treatment method is: adding 30% hydrogen peroxide solution by mass and stirring for 10-20 min; the volume ratio of the effluent from the secondary adsorption column to the hydrogen peroxide solution is 1:800-1:1000.

4. The method for purifying electronic-grade hydrochloric acid according to claim 1, characterized in that, The filling volume ratio of the primary adsorption column, secondary adsorption column and tertiary adsorption column in step (3) is 2-3:3-4:4-6.

5. The method for purifying electronic-grade hydrochloric acid according to claim 1, characterized in that, In step (3), multiple primary adsorption columns, secondary adsorption columns, and tertiary adsorption columns are provided and connected in parallel.

6. The method for purifying electronic-grade hydrochloric acid according to claim 1, characterized in that, In step (5), the liquid-to-gas ratio in the countercurrent contact is 1:0.5-1.

2.

7. A method for purifying electronic-grade hydrochloric acid according to any one of claims 1-6, characterized in that, The electronic-grade hydrochloric acid meets the following specifications: concentration 36.5-37.0 wt%, total metal impurities ≤100 ppt, particle size (≥0.5 μm) ≤3 pcs / mL, and color ≤5.