Method for directly producing electronic-grade hydrochloric acid from hydrogen chloride

Abstract

The invention discloses a production method for directly producing electronic-grade hydrochloric acid from hydrogen chloride, which comprises the following steps: (S1) spraying concentrated sulfuric acid on industrial hydrogen chloride prepared in a chlor-alkali synthesis furnace for countercurrent gas washing to remove moisture and metal ions; (S2) removing chlorine impurities from the gas obtained in the step (S1) through an adsorption column; (S3) gas obtained from the gas obtained in the step (S2) is subjected to gas washing with a two-stage hydrochloric acid saturated solution to further remove metal ions; and (S5) circularly absorbing and filtering the gas obtained in the step (S4) through ultrapure water to prepare the electronic-grade hydrochloric acid with the metal ion content within 10ppt. Compared with a traditional method for preparing electronic-grade hydrochloric acid from industrial hydrochloric acid, hydrogen chloride gas is directly utilized, so that the problems of high energy consumption, long flow, high cost and multiple operation points of a rectification process are solved, and the method is worthy of industrial popularization.

Description

Technical Field

[0001] The invention relates to a method for directly producing electronic-grade hydrochloric acid from hydrogen chloride, and belongs to the field of electronic chemicals. Background Art

[0002] Electronic grade hydrochloric acid is a high-purity hydrochloric acid used for cleaning and etching of electronic products such as semiconductor manufacturing, flat panel displays, photovoltaic cells, etc. Compared with ordinary industrial grade hydrochloric acid, electronic grade hydrochloric acid has more stringent requirements on the content of impurities, especially for metal ions and organic impurities.

[0003] In the current electronic grade hydrochloric acid purification method on the market, industrial hydrochloric acid is used as raw material, and activated carbon or resin is used to remove free chlorine. However, these methods are not ideal for removing free chlorine, and other metal impurities are easily introduced. In order to reduce metal impurities, special coal-based activated carbon with extremely low iron content and high-quality coconut shell activated carbon with low iron content are selected, which are expensive and still have a small amount of residual free chlorine. Industrial hydrochloric acid from which free chlorine has been removed mostly uses distillation to remove metal ions. It is difficult to remove metal ions in hydrochloric acid azeotropes, and the process control requirements are high. The process is complex and the process is long.

[0004] In summary, the existing process for electronic-grade hydrochloric acid is complex and long, and the ability to remove metal ions and free chlorine in electronic-grade hydrochloric acid is weak, and it is impossible to prepare ultra-high-purity electronic-grade hydrochloric acid required by integrated circuits. Therefore, it is necessary to develop a stable and low-cost method for directly producing electronic-grade hydrochloric acid from hydrogen chloride. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a method for directly producing electronic grade hydrochloric acid from hydrogen chloride to achieve continuous large-scale production.

[0006] The method of drying with concentrated sulfuric acid and washing with liquid can partially remove metal impurities and free chlorine in gaseous hydrogen chloride. However, since free chlorine is easily soluble in water, it is impossible to completely remove it. It is easy to corrode equipment and cause defects in the semiconductor process. Therefore, chlorine in hydrogen chloride is removed in the gaseous state to solve the problem that chlorine is dissolved in water in the subsequent process to form free chlorine that is difficult to remove. By modifying silica gel and loading stannous ions, due to the coordination bond energy and metal ion impurities to form coordination compounds, metal impurities are effectively retained in the liquid phase, and stannous ions can also react with chlorine to produce tin tetrachloride to effectively remove free chlorine impurities. By chemical grafting, the function of oxidizing stannous ions is introduced into the inorganic skeleton structure of silica gel, that is, a silica gel-loaded stannous adsorbent is obtained. When silica gel adsorbs water molecule impurities, it also reacts and adsorbs free chlorine in water molecules to achieve the function of effectively removing free chlorine. Ultrapure water washing can further treat the metal impurities in hydrogen chloride gas. Water can coordinate with metal ions, and ultrapure water can wash the liquid brought out by hydrogen chloride gas, which can effectively remove metal ions. This solves the problem of complex distillation process, difficult operation, high energy consumption, and product purity.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a production method for directly producing electronic grade hydrochloric acid from hydrogen chloride, the method comprising the following steps in sequence: (S1) Industrial hydrogen chloride prepared from a chlor-alkali synthesis furnace is scrubbed with concentrated sulfuric acid to remove moisture and metal ions; The concentration of concentrated sulfuric acid is 85%-98%; During the countercurrent spraying and scrubbing process, the valve between the sulfuric acid storage tank and the concentrated sulfuric acid buffer tank is interlocked with the concentration meter. The concentration meter is used to adjust the opening between the sulfuric acid storage tank and the concentrated sulfuric acid buffer tank to maintain the concentration of concentrated sulfuric acid during the countercurrent spraying process.

[0008] (S2) removing chlorine impurities from the gas obtained in step (S1) through an adsorption column; (S3) The gas obtained in step (S2) is further subjected to a two-stage hydrochloric acid saturated solution gas scrubbing to remove metal ions; (S4) The gas obtained in step (S3) is circulated and absorbed by ultrapure water and filtered to prepare electronic grade hydrochloric acid with a metal ion content within 10 ppt.

[0009] The adsorption material in the adsorption column is modified silica gel, and the modified silica gel comprises the following steps: (a) Disperse aminoethylaminopropyltrimethoxysilane in a toluene solution, add stannous chloride in an equimolar ratio, continue stirring and mix well, and react at room temperature for 0.5 to 5 hours. The reaction solution quickly turns from clear to turbid; (b) adding a certain proportion of tetramethyl orthosilicate and then triethylamine to the above turbid liquid under continuous stirring at room temperature, adjusting the pH value of the reaction system to 8-9; and continuing stirring for 2-18 hours; (c) allowing the turbid liquid to stand until a gel is formed, filtering, washing and drying to obtain a modified silica gel adsorbent.

[0010] The molar ratio of aminoethylaminopropyltrimethoxysilane to tetramethyl orthosilicate is 1-15.

[0011] The two-stage hydrochloric acid saturated solution in step S3 is a hydrochloric acid saturated solution prepared by countercurrent contact of ultrapure water to absorb hydrogen chloride from S2 until the hydrochloric acid is saturated. A concentration meter is provided on the hydrochloric acid pipeline, and the pipeline is connected to a hydrochloric acid buffer tank, a washing tower, a circulating pump, and a condenser.

[0012] In step S4, ultrapure water is sprayed down from the top of the absorption tower to react with the hydrogen chloride gas (S3) to prepare electronic grade hydrochloric acid. In the step S4, a concentration meter is provided on the hydrochloric acid pipeline, and the pipeline is connected to an absorption tower, a buffer tank, a circulation pump, a condenser, a three-stage filtration device and a hydrochloric acid finished product tank. Ultrapure water is introduced into the bottom of the absorption tower, and the buffer tank is connected to the upper inlet of the absorption tower through a circulation pump. Ultrapure water is sprayed down from the top of the absorption tower to react with the hydrogen chloride gas in S3 to prepare electronic grade hydrochloric acid.

[0013] In the steps S1-S4, the washing tower and the absorption tower are made of borosilicate glass or stainless steel lined with fluorine material.

[0014] The ultrapure water used in the steps S3-S4 has a resistivity of 16-19 MΩ*cm at 25° C. and a metal content of less than 1 ng / kg.

[0015] Beneficial effects of the present invention: The present invention adopts the production method of directly producing electronic-grade hydrochloric acid by industrial hydrogen chloride, adopts the method of concentrated drying and liquid washing, can effectively achieve the removal of metal impurities and free chlorine in gas phase hydrogen chloride, stannous chloride can combine with metal ion impurities to form coordination compounds due to its coordination bond, effectively leaving metal impurities in liquid phase, and can also react with free chlorine to produce tin tetrachloride to achieve effective removal of free chlorine impurities, ultrapure water washing can treat metal impurities in hydrogen chloride gas again, water can coordinate with metal ions, and ultrapure water can wash the liquid brought out by hydrogen chloride gas, can effectively remove metal ions. The process solves the problems of complex distillation process, high difficulty in operation, high energy consumption and product purity. The chlorine content in the obtained electronic-grade hydrochloric acid is less than 50ppb, more preferably less than 10ppb, and the metal ions are less than 10ppt. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Production flow chart for direct production of electronic grade hydrochloric acid from hydrogen chloride. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0018] Figure 1 Flow chart of the production method for directly producing electronic grade hydrochloric acid from hydrogen chloride.

[0019] See also Figure 1 The present invention provides a method for directly producing electronic-grade hydrochloric acid from hydrogen chloride, which comprises the following steps in sequence: Step S1: The industrial hydrogen chloride prepared from the chlor-alkali synthesis furnace has a pressure of 1.8Mpa and a gas flow rate of 110-130m 3 / h, air is taken in from the bottom of the drying tower, and concentrated sulfuric acid with a mass concentration of 98% is sprayed from the top of the drying tower for countercurrent washing to remove moisture and metal ions; the concentrated sulfuric acid with a mass concentration of 98% passes through a concentrated sulfuric acid buffer tank and a concentrated sulfuric acid storage tank in turn and enters the drying tower, and a circulating pump and a condenser are provided at the same time. The concentrated sulfuric acid buffer tank, the concentrated sulfuric acid storage tank, the drying tower, the circulating pump and the condenser are all made of stainless steel lined with fluorine. The valve between the sulfuric acid storage tank and the concentrated sulfuric acid buffer tank is interlocked with a concentration meter, and the opening between the sulfuric acid storage tank and the concentrated sulfuric acid buffer tank is adjusted by the concentration meter to maintain the sulfuric acid concentration in the concentrated sulfuric acid buffer tank at 95%-98%; Step S2: The gas obtained in step S1 enters the modified silica gel resin tower, and the gas pressure is 0.9Mpa-1.5Mpa; The adsorption material in the adsorption column is modified silica gel, and the modified silica gel comprises the following steps: (a) Disperse aminoethylaminopropyltrimethoxysilane in a toluene solution, add stannous chloride in an equimolar ratio, continue stirring and mix well, and react at room temperature for 1 hour. The reaction solution quickly turns from clear to turbid; (b) under continuous stirring at room temperature, a certain proportion of tetramethyl orthosilicate was added to the above turbid liquid, and then triethylamine was added, and the molar ratio of aminoethylaminopropyltrimethoxysilane to tetramethyl orthosilicate was 10:1, and the pH value of the reaction system was adjusted to 8.3; stirring was continued for 5 hours; (c) allowing the turbid liquid to stand until a gel is formed, filtering, washing and drying to obtain a modified silica gel adsorbent.

[0020] Step S3: The gas obtained in step S2 is further washed with a saturated hydrochloric acid solution to remove metal ions. The gas pressure is 0.5Mpa-1.1Mpa. The gas is introduced from the bottom of the washing tower, and the hydrochloric acid solution is sprayed from the top of the tower for countercurrent washing. The saturated hydrochloric acid solution is a saturated hydrochloric acid solution prepared by countercurrent contact with ultrapure water to absorb hydrogen chloride from S2 until the hydrochloric acid is saturated. A concentration meter is provided on the hydrochloric acid pipeline. The ultrapure water and the concentration meter are linked to ensure uniform concentration in the hydrochloric acid buffer tank through a circulation pump.

[0021] Step S4: The gas obtained in step S3 is absorbed and filtered through ultrapure water circulation, and the hydrochloric acid pipeline is connected to the absorption tower, buffer tank, circulation pump, condenser, three-stage filtration device and hydrochloric acid finished product tank. Ultrapure water is introduced into the bottom of the absorption tower, and the buffer tank is connected to the upper inlet of the absorption tower through the circulation pump. Ultrapure water is sprayed down from the top of the absorption tower to react with the hydrogen chloride gas in S3 to prepare electronic grade hydrochloric acid.

[0022] Example 2 The method and steps are the same as those in Example 1, except that in step S2, the molar ratio of aminoethylaminopropyltrimethoxysilane to tetramethyl orthosilicate is 15:1.

[0023] Example 3 The method and steps are the same as those in Example 1, except that step S2 is not performed.

[0024] Example 4 The method and steps are the same as those in Example 1, except that step S3 is not performed.

[0025] The technical indicators of the obtained hydrochloric acid product are shown in the following table: project unit Example 1 Example 2 Example 3 Example 4 Color APHA <10 <10 <10 <10 Assay (as HCL) % 37.1 37.4 36.5 37.5 (Cl) ppb 10 8 98 68 <![CDATA[(NO 3 )]]> ppb ≤100 ≤80 ≤100 ≤120 <![CDATA[(PO 4 )]]> ppb ≤50 ≤45 ≤50 ≤70 <![CDATA[(SO 4 )]]> ppb ≤100 ≤70 ≤100 ≤100 (Al) ppb ≤0.01 ≤0.01 ≤0.01 ≤0.01 (B) ppb ≤0.04 ≤0.06 ≤0.04 ≤0.24 (Ca) ppb ≤0.01 ≤0.02 ≤0.01 ≤0.01 (Cr) ppb ≤0.01 ≤0.01 ≤0.08 ≤0.01 (Cu) ppb ≤0.01 ≤0.01 ≤0.01 ≤0.63 (Au) ppb ≤0.01 ≤0.01 ≤0.01 ≤0.01 (Fe) ppb ≤0.01 ≤0.03 ≤0.01 ≤0.01 (Pb) ppb ≤0.01 ≤0.01 ≤0.04 ≤0.55 (Mg) ppb ≤0.01 ≤0.01 ≤0.01 ≤0.01 (Mn) ppb ≤0.01 ≤0.01 ≤0.02 ≤0.01 (Ni) ppb ≤0.01 ≤0.01 ≤0.01 ≤1.21 (K) ppb ≤0.01 ≤0.05 ≤0.01 ≤0.01 (Na) ppb ≤0.01 ≤0.01 ≤0.02 ≤0.01 (Sn) ppb ≤0.01 ≤0.01 ≤0.01 ≤1.83 (Ti) ppb ≤0.01 ≤0.01 ≤0.01 ≤0.01 (Zn) ppb ≤0.01 ≤0.01 ≤0.01 ≤5.79 The above-mentioned embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The embodiments and features in the embodiments of the present application can be arbitrarily combined with each other without conflict. The protection scope of the present invention shall be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A method for directly producing electronic grade hydrochloric acid from hydrogen chloride, characterized in that: The method comprises the following steps in sequence: (S1) Industrial hydrogen chloride prepared from a chlor-alkali synthesis furnace is scrubbed with concentrated sulfuric acid in countercurrent spraying to remove moisture and metal ions; (S2) removing moisture, metal ions and chlorine impurities from the gas obtained in step (S1) through an adsorption column; (S3) the obtained gas is further scrubbed with a two-stage saturated hydrochloric acid solution to remove metal ions; (S4) The gas obtained in step (S3) is absorbed and filtered through ultrapure water circulation to prepare electronic grade hydrochloric acid with a metal ion content within 10 ppt.

2. The method for directly producing electronic grade hydrochloric acid from hydrogen chloride according to claim 1, characterized in that: The concentration of concentrated sulfuric acid is 85%-98%; During the countercurrent spraying and scrubbing process, the valve between the sulfuric acid storage tank and the concentrated sulfuric acid buffer tank is interlocked with the concentration meter. The concentration meter is used to adjust the opening between the sulfuric acid storage tank and the concentrated sulfuric acid buffer tank to maintain the concentration of concentrated sulfuric acid during the countercurrent spraying process.

3. The method for producing electronic grade hydrochloric acid directly from hydrogen chloride according to claim 1, characterized in that the adsorption material in the adsorption column is modified silica gel, and the modified silica gel comprises the following steps: (a) Disperse aminoethylaminopropyltrimethoxysilane in toluene solution, add stannous chloride in an equimolar ratio, continue stirring and mix well, react at room temperature for 0.5-5h, and the reaction solution quickly turns from clear to turbid; (b) adding a certain proportion of tetramethyl orthosilicate and then triethylamine to the above turbid liquid under continuous stirring at room temperature, adjusting the pH value of the reaction system to 8-9; and continuing stirring for 2-18 hours; (c) allowing the turbid liquid to stand until a gel is formed, filtering, washing and drying to obtain a modified silica gel adsorbent.

4. The method for directly producing electronic-grade hydrochloric acid from hydrogen chloride according to claim 3, characterized in that the molar ratio of aminoethylaminopropyltrimethoxysilane to tetramethyl orthosilicate is 1 to 15.

5. The method for directly producing electronic grade hydrochloric acid from hydrogen chloride according to claim 1, characterized in that: The two-stage saturated hydrochloric acid solution in step S3 is a saturated hydrochloric acid solution prepared by countercurrently contacting ultrapure water to absorb hydrogen chloride from S2 until the hydrochloric acid is saturated.

6. The method for directly producing electronic grade hydrochloric acid from hydrogen chloride according to claim 1, characterized in that: In step S4, ultrapure water is sprayed down from the top of the absorption tower to react with the hydrogen chloride gas (S3) to prepare electronic grade hydrochloric acid.

7. The method for directly producing electronic grade hydrochloric acid from hydrogen chloride according to claims 1 to 6, characterized in that: In the steps S1-S4, the washing tower and the absorption tower are made of borosilicate glass or stainless steel lined with fluorine material.

8. The method for directly producing electronic grade hydrochloric acid from hydrogen chloride according to claims 1 to 6, characterized in that: The ultrapure water used in the steps S3-S4 has a resistivity of 16-19 MΩ*cm at 25° C. and a metal content of less than 1 ng / kg.

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