A method for removing sulfur dioxide gas from ultrapure sulfuric acid

Abstract

The application provides a method for removing sulfur dioxide gas from ultrapure sulfuric acid, which comprises the following steps: adding ultrapure sulfuric acid containing sulfur dioxide gas, TiO2 / Ce / molecular sieve composite adsorbent into a transparent glass kettle with a stirring device at 5-10 DEG C, and irradiating by using a UV lamp while stirring; then, the material in the transparent glass kettle is discharged and filtered to obtain ultrapure sulfuric acid with sulfur dioxide content lower than 5 ppm; the method can effectively remove the sulfur dioxide gas in the ultrapure sulfuric acid, does not produce new pollution, and basically maintains the original concentration of the ultrapure sulfuric acid; meanwhile, the method is simple, easy to operate, and suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ultra-pure sulfuric acid, in particular to a method for removing sulfur dioxide gas from ultra-pure sulfuric acid. BACKGROUND

[0002] Ultra-pure sulfuric acid is one of the commonly used chemical reagents in the electronic industry, mainly used for cleaning, photoetching, and etching of silicon wafers, printed circuit boards, and electroplating cleaning. The purity and cleanliness of ultra-pure sulfuric acid are highly required in the electronic industry. Therefore, in general, the content of sulfur dioxide in ultra-pure sulfuric acid needs to be controlled below 5ppm.

[0003] A method for removing trace sulfur dioxide from ultra-pure sulfuric acid is disclosed in domestic patent No. 202111650757.1, which includes the following steps: 1000g of ultra-pure concentrated sulfuric acid is accurately weighed and added to 200g of 31% ultra-pure hydrogen peroxide solution, and the concentration is accurately calibrated to about 5%. The content of sulfur dioxide in the ultra-pure sulfuric acid tank is determined, and the required amount of hydrogen peroxide and the required amount of 5% hydrogen peroxide sulfuric acid solution are strictly calculated according to the principle of molar equivalent reaction in chemistry. The above hydrogen peroxide sulfuric acid solution is slowly added to the sulfuric acid tank, and the temperature does not exceed 50 degrees. After the feeding is completed, the circulating pump is used for uniform circulation, and most of the trace sulfur dioxide content in the ultra-pure sulfuric acid can be removed. The above method uses hydrogen peroxide as an oxidizing agent to oxidize a small amount of sulfur dioxide into sulfur trioxide or sulfuric acid under certain conditions. The operation is simple, the cost is low, the operability is strong, and it is suitable for industrial application. However, the above method may increase new pollution on the one hand, and the concentration of ultra-pure sulfuric acid may change on the other hand. Therefore, it is necessary to develop a method for removing sulfur dioxide gas from ultra-pure sulfuric acid containing sulfur dioxide gas without increasing new pollution and basically maintaining the original concentration of ultra-pure sulfuric acid. SUMMARY

[0004] The purpose of the present application is to provide a method for removing sulfur dioxide gas from ultra-pure sulfuric acid, which effectively removes sulfur dioxide gas from ultra-pure sulfuric acid, obtains ultra-pure sulfuric acid with sulfur dioxide content below 5ppm, and does not produce new pollution, and basically maintains the original concentration of ultra-pure sulfuric acid, while the method is simple, easy to operate, and suitable for industrial production.

[0005] To achieve the above purpose, the present application is realized by the following technical scheme:

[0006] A method for removing sulfur dioxide gas from ultra-pure sulfuric acid, comprising the following steps: adding ultra-pure sulfuric acid containing sulfur dioxide gas, TiO2 / Ce / molecular sieve composite adsorbent to a transparent glass kettle with stirring device at 5-10℃, and irradiating with ultraviolet lamp while stirring; then discharging the material in the transparent glass kettle and filtering to obtain ultra-pure sulfuric acid with sulfur dioxide content below 5ppm.

[0007] In the method, the stirring device is a full-glass stirring device; and the transparent glass kettle is irradiated by the ultraviolet lamp.

[0008] Preferably, the preparation method of the TiO2 / Ce / molecular sieve composite adsorbent comprises the following steps:

[0009] (1) first, the molecular sieve is soaked in water for 5-7 hours, then freeze-dried, and then baked at 420-450 DEG C for 4-5 hours, and then cooled to room temperature to obtain a pretreated molecular sieve;

[0010] (2) butyl titanate and the pretreated molecular sieve are added to anhydrous ethanol, stirred, and then the cerium nitrate aqueous solution with a pH value of 2-3 is added dropwise while stirring, stirred for 5-9 hours, centrifuged, and then the obtained molecular sieve is vacuum dried, and then baked at 470-520 DEG C for 5-7 hours under the protection of nitrogen atmosphere, and then cooled to room temperature to obtain the TiO2 / Ce / molecular sieve composite adsorbent.

[0011] Preferably, the mass ratio of the pretreated molecular sieve, the anhydrous ethanol, the butyl titanate and the cerium nitrate aqueous solution is 1:(7-9):(1-1.5):(1.6-2.2); and the concentration of the cerium nitrate aqueous solution is 0.05-0.15 mol / L.

[0012] Preferably, the preparation method of the cerium nitrate aqueous solution is that cerium nitrate is added to water, stirred uniformly, and then dilute nitric acid is added to adjust the pH value to 2-3 to obtain the cerium nitrate aqueous solution.

[0013] Preferably, the particle size of the molecular sieve is 3-5 mm.

[0014] Preferably, the inner diameter of the transparent glass kettle is less than 1 meter.

[0015] Preferably, the mass ratio of the sulfur dioxide-containing ultrapure sulfuric acid and the TiO2 / Ce / molecular sieve composite adsorbent is 1:(0.01-0.03).

[0016] Preferably, the power of the ultraviolet lamp irradiation is 20-30 W.

[0017] Preferably, in the method, the ultraviolet lamp irradiation is performed while stirring for 5-6 hours.

[0018] Preferably, the content of sulfur dioxide in the sulfur dioxide-containing ultrapure sulfuric acid is below 100 ppm.

[0019] The present application has the following beneficial effects:

[0020] 1. The TiO2 / Ce / molecular sieve composite adsorbent is combined with ultraviolet lamp irradiation to remove sulfur dioxide gas in the ultrapure sulfuric acid, wherein the molecular sieve in the TiO2 / Ce / molecular sieve composite adsorbent has good adsorption effect on sulfur dioxide, and can adsorb a certain amount of water. After the sulfur dioxide is adsorbed by the molecular sieve, under the combined action of 5-10 DEG C, TiO2, Ce and ultraviolet lamp irradiation, the adsorbed sulfur dioxide can be efficiently oxidized to convert it into sulfur trioxide, and further react with the adsorbed water to generate sulfuric acid, so that the sulfur dioxide gas in the ultrapure sulfuric acid is effectively removed, the content of sulfur dioxide in the obtained ultrapure sulfuric acid is less than 5 ppm, and no new pollution is generated, and the original concentration of the ultrapure sulfuric acid is basically maintained.

[0021] 2. In the preparation of the TiO2 / Ce / molecular sieve composite adsorbent, the molecular sieve is pretreated first, so that the porosity of the molecular sieve can be improved, thereby effectively improving the loading rate of TiO2 and Ce on the molecular sieve. In addition, by simultaneously loading TiO2 and Ce on the molecular sieve, the adsorption and oxidation performance of TiO2 on sulfur dioxide gas can be promoted, so that the TiO2 / Ce / molecular sieve composite adsorbent has excellent adsorption performance and catalytic oxidation performance on sulfur dioxide gas.

[0022] 3. The method is simple, easy to operate, and suitable for industrial production. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0024] Embodiment 1: Preparation of TiO2 / Ce / molecular sieve composite adsorbent

[0025] A preparation method of a TiO2 / Ce / molecular sieve composite adsorbent comprises the following steps:

[0026] (1) First, the molecular sieve with a particle size of 3-5 mm is soaked in water for 7 h, then freeze-dried, and then placed in a muffle furnace at 450 DEG C for calcination for 4 h, and then cooled to room temperature to obtain a pretreated molecular sieve.

[0027] (2) adding butyl titanate and the pretreated molecular sieve into anhydrous ethanol, stirring, then adding cerium nitrate aqueous solution with pH value of 2 and concentration of 0.1 mol / L dropwise while stirring, the mass ratio of the pretreated molecular sieve, anhydrous ethanol, butyl titanate and cerium nitrate aqueous solution being 1:8:1.2:2.2; after stirring for 7 h, centrifugal separation is conducted, the obtained molecular sieve is vacuum dried, then the vacuum dried molecular sieve is calcined at 520℃ under nitrogen atmosphere for 5 h, and then cooled to room temperature, thus obtaining the TiO2 / Ce / molecular sieve composite adsorbent.

[0028] The preparation method of the cerium nitrate aqueous solution is as follows: adding cerium nitrate into water, stirring, then adding dilute nitric acid, and adjusting the pH value to 2, thus obtaining the cerium nitrate aqueous solution.

[0029] Example 2: Preparation of TiO2 / Ce / molecular sieve composite adsorbent

[0030] A preparation method of a TiO2 / Ce / molecular sieve composite adsorbent, comprising the following steps:

[0031] (1) first immersing molecular sieve with particle size of 3-5 mm in water for 7 h, then conducting freeze drying, then placing the freeze dried molecular sieve in a muffle furnace and calcining at 420℃ for 5 h, and then cooling to room temperature, thus obtaining pretreated molecular sieve.

[0032] (2) adding butyl titanate and the pretreated molecular sieve into anhydrous ethanol, stirring, then adding cerium nitrate aqueous solution with pH value of 3 and concentration of 0.05 mol / L dropwise while stirring, the mass ratio of the pretreated molecular sieve, anhydrous ethanol, butyl titanate and cerium nitrate aqueous solution being 1:9:1:2; after stirring for 9 h, centrifugal separation is conducted, the obtained molecular sieve is vacuum dried, then the vacuum dried molecular sieve is calcined at 500℃ under nitrogen atmosphere for 7 h, and then cooled to room temperature, thus obtaining the TiO2 / Ce / molecular sieve composite adsorbent.

[0033] The preparation method of the cerium nitrate aqueous solution is as follows: adding cerium nitrate into water, stirring, then adding dilute nitric acid, and adjusting the pH value to 3, thus obtaining the cerium nitrate aqueous solution.

[0034] Example 3: Preparation of TiO2 / Ce / molecular sieve composite adsorbent

[0035] A preparation method of a TiO2 / Ce / molecular sieve composite adsorbent, comprising the following steps:

[0036] (1) first immersing molecular sieve with particle size of 3-5 mm in water for 7 h, then conducting freeze drying, then placing the freeze dried molecular sieve in a muffle furnace and calcining at 420℃ for 5 h, and then cooling to room temperature, thus obtaining pretreated molecular sieve.

[0037] (2) adding butyl titanate and the pretreated molecular sieve into anhydrous ethanol, stirring, then adding cerium nitrate aqueous solution with pH value of 2.5 and concentration of 0.15 mol / L dropwise while stirring, the mass ratio of the pretreated molecular sieve, anhydrous ethanol, butyl titanate and cerium nitrate aqueous solution being 1:7:1.5:1.6; after stirring for 9 h, centrifugal separation is conducted, the obtained molecular sieve is vacuum dried, then the vacuum dried molecular sieve is calcined at 470℃ for 6 h under nitrogen atmosphere, and then cooled to room temperature, thus TiO2 / Ce / molecular sieve composite adsorbent is obtained.

[0038] The preparation method of the above-mentioned cerium nitrate aqueous solution is as follows: adding cerium nitrate into water, stirring, then adding dilute nitric acid, and adjusting the pH value to 2, thus cerium nitrate aqueous solution is obtained.

[0039] Preparation of TiO2 / molecular sieve composite adsorbent

[0040] A preparation method of TiO2 / molecular sieve composite adsorbent, comprising the following steps:

[0041] (1) first, molecular sieve with particle size of 3-5 mm is soaked in water for 5 h, then freeze-dried, and then calcined at 430℃ for 5 h, and then cooled to room temperature, thus pretreated molecular sieve is obtained.

[0042] (2) adding butyl titanate and the pretreated molecular sieve into anhydrous ethanol, stirring, then adding water with pH value of 2.5 dropwise while stirring, the mass ratio of the pretreated molecular sieve, anhydrous ethanol, butyl titanate and water being 1:7:1.5:1.6; after stirring for 9 h, centrifugal separation is conducted, the obtained molecular sieve is vacuum dried, then the vacuum dried molecular sieve is calcined at 470℃ for 6 h under nitrogen atmosphere, and then cooled to room temperature, thus TiO2 / molecular sieve composite adsorbent is obtained.

[0043] The preparation method of the above-mentioned water with pH value of 2.5 is as follows: adding dilute nitric acid into water, and adjusting the pH value to 2, thus water with pH value of 2.5 is obtained.

[0044] Preparation of TiO2 / Ce / molecular sieve composite adsorbent

[0045] A preparation method of TiO2 / Ce / molecular sieve composite adsorbent, comprising the following steps:

[0046] (2) adding butyl titanate and the pretreated molecular sieve into anhydrous ethanol, stirring, then adding cerium nitrate aqueous solution with pH value of 2.5 and concentration of 0.15 mol / L dropwise while stirring, the mass ratio of the pretreated molecular sieve, anhydrous ethanol, butyl titanate and cerium nitrate aqueous solution being 1:7:1.5:1.6; after stirring for 9 h, centrifugal separation is conducted, the obtained molecular sieve is vacuum dried, then the vacuum dried molecular sieve is calcined at 470℃ for 6 h under nitrogen atmosphere, and then cooled to room temperature, thus TiO2 / Ce / molecular sieve composite adsorbent is obtained.

[0047] The preparation method of the above cerium nitrate aqueous solution is as follows: cerium nitrate is added to water, dilute nitric acid is added after stirring, and the pH value is adjusted to 2 to obtain the cerium nitrate aqueous solution.

[0048] Example 4:

[0049] A method for removing sulfur dioxide gas from ultrapure sulfuric acid, comprising the following steps: at 8℃, adding sulfur dioxide gas-containing ultrapure sulfuric acid and the TiO2 / Ce / molecular sieve composite adsorbent in Example 1 into a transparent glass kettle with a stirring device, and irradiating with a UV lamp for 5h while stirring; the power of the UV lamp is 25W; then the material in the transparent glass kettle is discharged and filtered to obtain sulfur dioxide gas-containing ultrapure sulfuric acid with a sulfur dioxide content of 0.5ppm.

[0050] The inner diameter of the above transparent glass kettle is 0.7m, and the content of sulfur dioxide in the sulfur dioxide gas-containing ultrapure sulfuric acid is 90ppm; the mass ratio of the sulfur dioxide gas-containing ultrapure sulfuric acid to the TiO2 / Ce / molecular sieve composite adsorbent is 1:0.03.

[0051] Example 5:

[0052] A method for removing sulfur dioxide gas from ultrapure sulfuric acid, comprising the following steps: at 5℃, adding sulfur dioxide gas-containing ultrapure sulfuric acid and the TiO2 / Ce / molecular sieve composite adsorbent in Example 2 into a transparent glass kettle with a stirring device, and irradiating with a UV lamp for 6h while stirring; the power of the UV lamp is 30W; then the material in the transparent glass kettle is discharged and filtered to obtain sulfur dioxide gas-containing ultrapure sulfuric acid with a sulfur dioxide content of 4ppm.

[0053] The inner diameter of the above transparent glass kettle is 0.7m, and the content of sulfur dioxide in the sulfur dioxide gas-containing ultrapure sulfuric acid is 90ppm; the mass ratio of the sulfur dioxide gas-containing ultrapure sulfuric acid to the TiO2 / Ce / molecular sieve composite adsorbent is 1:0.01.

[0054] Example 6:

[0055] A method for removing sulfur dioxide gas from ultrapure sulfuric acid, comprising the following steps: at 5℃, adding sulfur dioxide gas-containing ultrapure sulfuric acid and the TiO2 / Ce / molecular sieve composite adsorbent in Example 2 into a transparent glass kettle with a stirring device, and irradiating with a UV lamp for 6h while stirring; the power of the UV lamp is 30W; then the material in the transparent glass kettle is discharged and filtered to obtain sulfur dioxide gas-containing ultrapure sulfuric acid with a sulfur dioxide content of 1ppm.

[0056] The inner diameter of the transparent glass kettle is 0.7 meters, and the content of sulfur dioxide in the sulfur dioxide gas-containing ultrapure sulfuric acid is 75 ppm; the mass ratio of the sulfur dioxide gas-containing ultrapure sulfuric acid to the TiO2 / Ce / molecular sieve composite adsorbent is 1:0.03.

[0057] Example 7:

[0058] A method for removing sulfur dioxide gas from ultrapure sulfuric acid, comprising the following steps: at 10℃, adding sulfur dioxide gas-containing ultrapure sulfuric acid and the TiO2 / Ce / molecular sieve composite adsorbent in Example 1 into a transparent glass kettle with stirring device, and then irradiating with a ultraviolet lamp for 5.5h while stirring, the power of the ultraviolet lamp is 20W; then the material in the transparent glass kettle is discharged and filtered, and ultrapure sulfuric acid with a sulfur dioxide content of 2.5ppm is obtained.

[0059] The inner diameter of the transparent glass kettle is 0.7 meters, and the content of sulfur dioxide in the sulfur dioxide gas-containing ultrapure sulfuric acid is 75 ppm; the mass ratio of the sulfur dioxide gas-containing ultrapure sulfuric acid to the TiO2 / Ce / molecular sieve composite adsorbent is 1:0.02.

[0060] Example 8:

[0061] A method for removing sulfur dioxide gas from ultrapure sulfuric acid, comprising the following steps: at 8℃, adding sulfur dioxide gas-containing ultrapure sulfuric acid and the TiO2 / Ce / molecular sieve composite adsorbent in Example 3 into a transparent glass kettle with stirring device, and then irradiating with a ultraviolet lamp for 5h while stirring, the power of the ultraviolet lamp is 30W; then the material in the transparent glass kettle is discharged and filtered, and ultrapure sulfuric acid with a sulfur dioxide content of 1.5ppm is obtained.

[0062] The inner diameter of the transparent glass kettle is 0.7 meters, and the content of sulfur dioxide in the sulfur dioxide gas-containing ultrapure sulfuric acid is 75 ppm; the mass ratio of the sulfur dioxide gas-containing ultrapure sulfuric acid to the TiO2 / Ce / molecular sieve composite adsorbent is 1:0.03.

[0063] Example 9:

[0064] A method for removing sulfur dioxide gas from ultrapure sulfuric acid, comprising the following steps: at 8℃, adding sulfur dioxide gas-containing ultrapure sulfuric acid and the TiO2 / Ce / molecular sieve composite adsorbent in Example 3 into a transparent glass kettle with stirring device, and then irradiating with a ultraviolet lamp for 5.5h min while stirring, the power of the ultraviolet lamp is 25W; then the material in the transparent glass kettle is discharged and filtered, and ultrapure sulfuric acid with a sulfur dioxide content of 3ppm is obtained.

[0065] The inner diameter of the transparent glass kettle is 0.7 meters, and the content of sulfur dioxide in the ultra-pure sulfuric acid containing sulfur dioxide gas is 80 ppm; the mass ratio of the ultra-pure sulfuric acid containing sulfur dioxide gas to the TiO2 / Ce / molecular sieve composite adsorbent is 1:0.02.

[0066] Comparative Example 3:

[0067] A method for removing sulfur dioxide gas from ultra-pure sulfuric acid, which is different from Example 9 in that the TiO2 / Ce / molecular sieve composite adsorbent in Example 1 is replaced by the TiO2 / molecular sieve composite adsorbent in Comparative Example 1, and the other steps are consistent with Example 9. Finally, the content of sulfur dioxide in the ultra-pure sulfuric acid is 13 ppm.

[0068] Comparative Example 4:

[0069] A method for removing sulfur dioxide gas from ultra-pure sulfuric acid, which is different from Example 9 in that the TiO2 / Ce / molecular sieve composite adsorbent in Example 1 is replaced by the TTiO2 / Ce / molecular sieve composite adsorbent in Comparative Example 2, and the other steps are consistent with Example 9. Finally, the content of sulfur dioxide in the ultra-pure sulfuric acid is 10.5 ppm.

[0070] Comparative Example 5:

[0071] A method for removing sulfur dioxide gas from ultra-pure sulfuric acid, which is different from Example 9 in that the ultraviolet lamp is not used for irradiation, and the other steps are consistent with Example 9. Finally, the content of sulfur dioxide in the ultra-pure sulfuric acid is 20 ppm.

[0072] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacements for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for removing sulfur dioxide gas from ultrapure sulfuric acid, characterized by, The method comprises the following steps: The transparent glass kettle with stirring device is added with sulfur dioxide gas containing ultrapure sulfuric acid, TiO2 / Ce / molecular sieve composite adsorbent, and then the material in the transparent glass kettle is discharged and filtered to obtain ultrapure sulfuric acid with sulfur dioxide content less than 5 ppm under the condition of stirring and ultraviolet lamp irradiation.

2. The method of removing sulfur dioxide gas from ultrapure sulfuric acid according to claim 1, wherein The preparation method of the TiO2 / Ce / molecular sieve composite adsorbent comprises the following steps: (1) The molecular sieve is soaked in water for 5-7 h, then freeze-dried, and then baked at 420-450 DEG C for 4-5 h, and then cooled to room temperature to obtain pretreated molecular sieve; (2) Butyl titanate and pretreated molecular sieve are added into anhydrous ethanol, stirred, then the pH value of 2-3 cerium nitrate aqueous solution is added dropwise under stirring, stirred for 5-9 h, then centrifuged, the obtained molecular sieve is vacuum dried, then baked at 470-520 DEG C under nitrogen protection atmosphere for 5-7 h, and then cooled to room temperature to obtain the TiO2 / Ce / molecular sieve composite adsorbent.

3. The method of removing sulfur dioxide gas from ultrapure sulfuric acid according to claim 2, wherein The mass ratio of the pretreated molecular sieve, anhydrous ethanol, butyl titanate and cerium nitrate aqueous solution is 1:(7-9):(1-1.5):(1.6-2.2); the concentration of the cerium nitrate aqueous solution is 0.05-0.15 mol / L.

4. The method of removing sulfur dioxide gas from ultrapure sulfuric acid according to claim 2, wherein The preparation method of the cerium nitrate aqueous solution is as follows: cerium nitrate is added into water, stirred uniformly, then dilute nitric acid is added, and the pH value is adjusted to 2-3 to obtain the cerium nitrate aqueous solution.

5. The method of removing sulfur dioxide gas from ultrapure sulfuric acid according to claim 2, wherein The particle size of the molecular sieve is 3-5 mm.

6. The method of removing sulfur dioxide gas from ultrapure sulfuric acid according to claim 1, wherein The inner diameter of the transparent glass kettle is less than 1 m.

7. The method of removing sulfur dioxide gas from ultrapure sulfuric acid according to any one of claims 1-6, wherein, The mass ratio of the sulfur dioxide gas containing ultrapure sulfuric acid and TiO2 / Ce / molecular sieve composite adsorbent is 1:(0.01-0.03).

8. The method of removing sulfur dioxide gas from ultrapure sulfuric acid according to any one of claims 1-6, wherein, The power of the ultraviolet lamp irradiation is 20-30 W.

9. The method of removing sulfur dioxide gas from ultrapure sulfuric acid according to any one of claims 1-6, wherein, In the method, the ultraviolet lamp irradiation is performed under stirring for 5-6 h.

10. The method of removing sulfur dioxide gas from ultrapure sulfuric acid according to any one of claims 1-6, wherein, The content of sulfur dioxide in the sulfur dioxide gas containing ultrapure sulfuric acid is less than 100 ppm.