Tantalum oxide-polytetrafluoroethylene ceramic membrane, method for preparing same, and use thereof

Abstract

The application relates to the technical field of ceramic membrane preparation, and discloses a tantalum oxide-polytetrafluoroethylene ceramic membrane and a preparation method and application thereof, wherein the method comprises the following steps: (1) mixing a tantalum compound, an alcohol solvent, a chelating agent, a polytetrafluoroethylene concentrated dispersion liquid and a hydrogen peroxide aqueous solution to obtain mixed slurry, and aging the mixed slurry to obtain a tantalum sol; (2) coating the tantalum sol on a porous ceramic membrane support, and drying and calcining to obtain a tantalum oxide-polytetrafluoroethylene ceramic membrane. The tantalum oxide-polytetrafluoroethylene ceramic membrane comprises a porous ceramic membrane support and a tantalum oxide-polytetrafluoroethylene membrane loaded on the porous ceramic membrane support, wherein the average pore diameter of the tantalum oxide-polytetrafluoroethylene membrane is 2-10 nm, and the thickness is 100-400 nm. The tantalum oxide-polytetrafluoroethylene ceramic membrane provided by the application can resist acid corrosion and filter out metal ions and other impurities in sulfuric acid, and electronic-grade sulfuric acid is prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic membrane preparation, and in particular to a tantalum oxide-polytetrafluoroethylene ceramic membrane and a preparation method and application thereof. Background Art

[0002] Electronic-grade sulfuric acid is an ultra-clean, high-purity reagent that plays a vital role in the development of microelectronics technology. It is widely used in the assembly and processing of semiconductors and ultra-large-scale integrated circuits. It is mainly used for cleaning and etching silicon wafers, and can remove impurity particles, inorganic residues, and carbon deposits on the wafers.

[0003] Currently, sulfuric acid refining mainly involves distillation and gas absorption. Distillation, however, places high demands on equipment and suffers from severe corrosion at high temperatures, making it difficult to produce electronic-grade sulfuric acid. The primary method for producing electronic-grade sulfuric acid abroad is gas absorption. After sulfur trioxide is purified, it is absorbed by sulfuric acid and then filtered and purified to produce electronic-grade sulfuric acid. The core technology behind filtration lies in the selection of membrane materials.

[0004] CN211753305U discloses a filtration system for a microelectronic-grade refined sulfuric acid production device, comprising a cylindrical sulfuric acid filter and a cylindrical SO3 gas filter, which are sequentially connected to the sulfuric acid production pipeline. A flow equalizer is installed below the feed pipe mouth, and filter device A is installed below the flow equalizer. The SO3 gas filter is provided with an SO3 gas outlet at the top, and filter device B is installed near the top of the filter. A gas distributor is installed below filter device B. The side wall of the SO3 gas filter is wrapped with a heating jacket, and the inner wall of the heating jacket is fixed with smooth bumps at intervals along the circumference from top to bottom. This patent mainly improves the filtration effect through the filtration process, but does not specify the materials and composition of the specific filtration device.

[0005] CN110743384A discloses a method for preparing a ceramic nanofiltration membrane, in which a complete and defect-free titanium oxide nanoceramic nanofiltration membrane is prepared by a modified sol-gel method combined with a hydrothermal method. However, the ceramic membrane is not acid-resistant for a long time and is difficult to use as a filter membrane in the preparation of electronic-grade sulfuric acid.

[0006] Therefore, it is urgent to provide a filter membrane that can resist acid corrosion and can be used as electronic grade sulfuric acid preparation. Summary of the Invention

[0007] The present invention aims to overcome the problems of the prior art in the complex preparation process of electronic-grade sulfuric acid and the lack of a filter membrane suitable for use in the preparation of electronic-grade sulfuric acid. The present invention provides a tantalum oxide-polytetrafluoroethylene ceramic membrane, its preparation method, and its application. The tantalum oxide-polytetrafluoroethylene ceramic membrane is resistant to acid corrosion and filters out impurities such as metal ions in sulfuric acid, thereby producing electronic-grade sulfuric acid.

[0008] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a tantalum oxide-polytetrafluoroethylene ceramic membrane, which comprises the following steps:

[0009] (1) mixing a tantalum compound, an alcohol solvent, a chelating agent, a concentrated polytetrafluoroethylene dispersion, and an aqueous hydrogen peroxide solution to obtain a mixed slurry, and aging the mixed slurry to obtain a tantalum sol;

[0010] (2) The tantalum sol is coated on a porous ceramic membrane support, and dried and calcined to obtain a tantalum oxide-polytetrafluoroethylene ceramic membrane.

[0011] A second aspect of the present invention provides a tantalum oxide-polytetrafluoroethylene ceramic membrane prepared by the method described above, wherein the tantalum oxide-polytetrafluoroethylene ceramic membrane comprises a porous ceramic membrane support and a tantalum oxide-polytetrafluoroethylene membrane supported on the porous ceramic membrane support, the average pore size of the tantalum oxide-polytetrafluoroethylene membrane is 2-10 nm, and the thickness of the tantalum oxide-polytetrafluoroethylene membrane is 100-400 nm.

[0012] A third aspect of the present invention provides a use of the tantalum oxide-polytetrafluoroethylene ceramic membrane described in the second aspect in refined sulfuric acid. Preferably, the refined sulfuric acid meets the standards of electronic grade sulfuric acid.

[0013] Through the above technical solution, the present invention can achieve the following beneficial effects:

[0014] The tantalum oxide-polytetrafluoroethylene ceramic membrane prepared by the method provided by the present invention is resistant to acid corrosion and can block impurities such as metal ions in sulfuric acid, and is more suitable for the preparation of electronic-grade sulfuric acid. Moreover, the preparation method of the ceramic membrane is simple and convenient for large-scale production. DETAILED DESCRIPTION

[0015] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0016] In the present invention, the “first”, “second” and “third” do not limit the present invention, but are only used to distinguish materials and operations at different stages.

[0017] A first aspect of the present invention provides a method for preparing a tantalum oxide-polytetrafluoroethylene ceramic membrane, comprising the following steps:

[0018] (1) mixing a tantalum compound, an alcohol solvent, a chelating agent, a concentrated polytetrafluoroethylene dispersion, and an aqueous hydrogen peroxide solution to obtain a mixed slurry, and aging the mixed slurry to obtain a tantalum sol;

[0019] (2) The tantalum sol is coated on a porous ceramic membrane support, and dried and calcined to obtain a tantalum oxide-polytetrafluoroethylene ceramic membrane.

[0020] In the present invention, a concentrated polytetrafluoroethylene dispersion is added during the preparation of a tantalum sol, and the prepared tantalum sol is used to modify a porous ceramic membrane to form a loaded porous tantalum oxide-polytetrafluoroethylene membrane on the porous ceramic membrane. Thus, a tantalum oxide-polytetrafluoroethylene ceramic membrane is obtained. The ceramic membrane is resistant to acid corrosion and can block impurities such as metal ions in sulfuric acid, and is used for the preparation of electronic-grade sulfuric acid.

[0021] In some embodiments of the present invention, in step (1), the mixing process preferably includes: first mixing the tantalum compound and an alcohol solvent to obtain a first mixed solution; second mixing the first mixed solution with a chelating agent and a concentrated polytetrafluoroethylene dispersion to obtain a second mixed solution; and third mixing the second mixed solution with an aqueous hydrogen peroxide solution to obtain a third mixed solution. In this manner, the tantalum sol obtained through the above-mentioned multi-step mixing process can provide a ceramic membrane that meets the requirements of the concentrated sulfuric acid refining process.

[0022] In some embodiments of the present invention, in order to fully dissolve the tantalum compound in the alcohol solvent, the first mixing process includes: slowly adding the tantalum compound to the alcohol solvent, stirring at 20-40°C for 0.5-2h, and a stirring speed of 100-700r / min.

[0023] The present invention does not particularly limit the type and amount of the alcohol solvent, as long as it can fully dissolve the tantalum compound. Preferably, the alcohol solvent is selected from at least one of methanol, ethanol, and isopropanol; the amount of the alcohol solvent used is 20-50 mL per 1 g of the tantalum compound.

[0024] In some embodiments of the present invention, in order to ensure uniform mixing of the first mixed liquid with the chelating agent and the polytetrafluoroethylene concentrated dispersion, the second mixing conditions include: time of 0.5-2h, stirring speed of 100-700r / min, and temperature of 20-40°C.

[0025] In some embodiments of the present invention, preferably, the mass ratio of the tantalum compound to the chelating agent is 1:0.3-0.7.

[0026] In some embodiments of the present invention, the amount of the concentrated polytetrafluoroethylene dispersion is preferably 5-10 mL per gram of the tantalum compound, wherein the concentration of the concentrated polytetrafluoroethylene dispersion is 20-60 wt%. When the amounts of the tantalum compound, chelating agent, and concentrated polytetrafluoroethylene dispersion meet the aforementioned conditions, the resulting tantalum sol particles can be uniform in size, evenly dispersed, and less prone to agglomeration.

[0027] In some embodiments of the present invention, in order to ensure uniform mixing of the second mixed liquid and the aqueous hydrogen peroxide solution, the third mixing conditions include: time of 1-2 hours, stirring speed of 100-700 r / min, and temperature of 20-40°C.

[0028] In some embodiments of the present invention, preferably, the amount of the aqueous hydrogen peroxide solution is 1-3 mL relative to 1 g of the tantalum compound, wherein the concentration of the aqueous hydrogen peroxide solution is 25-35 wt %.

[0029] In some embodiments of the present invention, preferably, the tantalum compound is selected from at least one of tantalum pentachloride, tantalum ethoxide and tantalum methanol.

[0030] In some embodiments of the present invention, preferably, the chelating agent is selected from triethanolamine and / or acetylacetone.

[0031] In some embodiments of the present invention, in order to promote the formation of the tantalum sol, the aging conditions include: a temperature of 0-40° C., preferably 0-10° C.; and a time of 3-7 days.

[0032] In some embodiments of the present invention, the porous ceramic membrane is selected from a porous alumina ceramic membrane, a porous zirconia ceramic membrane or a porous silicon carbide ceramic membrane, preferably a porous alumina ceramic membrane.

[0033] In some embodiments of the present invention, the average pore size of the porous ceramic membrane is 0.1-10 μm, preferably 0.1-5 μm.

[0034] In some embodiments of the present invention, in order to uniformly load the tantalum sol on the porous ceramic membrane, in step (2), the drying conditions include: a temperature of 80-120° C., a heating rate of 1-5° C. / min, and a drying time of 2-4 h;

[0035] Preferably, the calcination conditions include: temperature of 400-600° C., heating rate of 1-5° C. / min, and time of 2-4 h.

[0036] A second aspect of the present invention provides a tantalum oxide-polytetrafluoroethylene ceramic membrane prepared by the method described above, wherein the tantalum oxide-polytetrafluoroethylene ceramic membrane comprises a porous ceramic membrane support and a tantalum oxide-polytetrafluoroethylene membrane supported on the porous ceramic membrane support, the average pore size of the tantalum oxide-polytetrafluoroethylene membrane is 2-10 nm, and the thickness of the tantalum oxide-polytetrafluoroethylene membrane is 100-400 nm.

[0037] The tantalum oxide-polytetrafluoroethylene membrane produced by the method provided herein has small, uniformly distributed pores and high filtration efficiency, and can be used to filter particles, metal ion impurities, and non-metallic impurities in sulfuric acid. The average pore size and thickness of the tantalum oxide-polytetrafluoroethylene membrane can be determined by scanning electron microscopy.

[0038] A third aspect of the present invention provides a use of the tantalum oxide-polytetrafluoroethylene ceramic membrane described in the second aspect in refined sulfuric acid. Preferably, the refined sulfuric acid meets the standards of electronic grade sulfuric acid.

[0039] The present invention will be described in detail below through examples. In the following examples and comparative examples, all raw materials involved are commercially available unless otherwise specified;

[0040] The polytetrafluoroethylene concentrated dispersion is a commercial product with the trademark PTFE TE3970 from DuPont Company, USA.

[0041] In the following test example,

[0042] Inductively coupled plasma-mass spectrometry (ICP-MS) was used to test the content of metal ion impurities in sulfuric acid solution;

[0043] The average pore size of the tantalum oxide-polytetrafluoroethylene membranes prepared in the examples and comparative examples was obtained using a scanning electron microscope;

[0044] The thickness of the tantalum oxide-polytetrafluoroethylene films prepared in the examples and comparative examples was measured using a scanning electron microscope.

[0045] Example 1

[0046] (1) 2 g of tantalum pentachloride was slowly added to 60 mL of isopropanol solvent and stirred at 200 r / min for 0.5 h; then 1 mL of acetylacetone, 0.4 g of triethanolamine, and 10 mL of a 30 wt% polytetrafluoroethylene concentrated dispersion were added to the above solution and the mixture was stirred at 200 r / min for 1 h; 3 mL of a 25 wt% aqueous hydrogen peroxide solution was added and the mixture was stirred at 200 r / min for 2 h. The resulting sol was sealed and aged at 5°C for 5 days to obtain a tantalum sol;

[0047] (2) A porous alumina ceramic membrane support with an average pore size of 0.1 μm was immersed in tantalum sol for 5 minutes. After being taken out, the temperature was raised to 100°C at a rate of 2°C / min at a humidity of 40%, and the membrane was kept warm and dried for 3 hours. Then, the temperature was raised to 500°C at a rate of 2°C / min, and the membrane was kept warm and calcined for 3 hours. The membrane was cooled to obtain a tantalum oxide-polytetrafluoroethylene ceramic membrane; wherein the tantalum oxide-polytetrafluoroethylene ceramic membrane includes a porous alumina ceramic membrane support and a tantalum oxide-polytetrafluoroethylene membrane supported on the porous alumina ceramic membrane support.

[0048] Example 2

[0049] (1) 1 g of tantalum ethoxide was slowly added to 40 mL of ethanol solvent and stirred at 200 r / min for 1 h; then 0.2 mL of acetylacetone, 0.4 g of triethanolamine, and 5 mL of a 60 wt% polytetrafluoroethylene concentrated dispersion were added to the above solution and the mixture was stirred at 200 r / min for 1 h; 2 mL of a 25 wt% aqueous hydrogen peroxide solution was added and the mixture was stirred at 200 r / min for 1 h. The obtained sol was sealed and aged at 0°C for 3 days to obtain a tantalum sol;

[0050] (2) A porous alumina ceramic membrane support with an average pore size of 0.1 μm is immersed in tantalum sol for 2 minutes. After being taken out, the temperature is raised to 100°C at a rate of 3°C / min at a humidity of 40%, and the membrane is kept warm and dried for 3 hours. The temperature is then raised to 600°C at a rate of 5°C / min, and the membrane is kept warm and calcined for 2 hours. The membrane is cooled to obtain a tantalum oxide-polytetrafluoroethylene ceramic membrane; wherein the tantalum oxide-polytetrafluoroethylene ceramic membrane includes a porous alumina ceramic membrane support and a tantalum oxide-polytetrafluoroethylene membrane supported on the porous alumina ceramic membrane support.

[0051] Example 3

[0052] (1) 5 g of tantalum methoxide was slowly added to 100 mL of methanol solvent and stirred at 500 r / min for 2 h; then 1 mL of acetylacetone, 2 g of triethanolamine, and 30 mL of a 60 wt% polytetrafluoroethylene concentrated dispersion were added to the above solution and the mixture was stirred at 500 r / min for 1 h; 5 mL of a 25 wt% aqueous hydrogen peroxide solution was added and the mixture was stirred at 500 r / min for 2 h. The resulting sol was sealed and aged at 10° C. for 7 days to obtain a tantalum sol;

[0053] (2) A porous alumina ceramic membrane support with an average pore size of 0.1 μm was immersed in tantalum sol for 3 minutes. After being taken out, the temperature was raised to 120°C at a rate of 1°C / min at a humidity of 40%, and the temperature was kept dry for 2.5 hours. Then, the temperature was raised to 500°C at a rate of 1°C / min, and the temperature was kept calcined for 3 hours. The tantalum oxide-polytetrafluoroethylene ceramic membrane was cooled to obtain a tantalum oxide-polytetrafluoroethylene ceramic membrane; wherein the tantalum oxide-polytetrafluoroethylene ceramic membrane includes a porous alumina ceramic membrane support and a tantalum oxide-polytetrafluoroethylene membrane supported on the porous alumina ceramic membrane support.

[0054] Example 4

[0055] A ceramic membrane was prepared according to the method of Example 1, except that triethanolamine was not added during the preparation of the tantalum sol.

[0056] Comparative Example 1

[0057] A ceramic membrane was prepared according to the method of Example 1, except that no polytetrafluoroethylene concentrated dispersion was added during the preparation of the tantalum sol, thereby obtaining a tantalum oxide ceramic membrane; wherein the tantalum oxide ceramic membrane included a porous alumina ceramic membrane support and a tantalum oxide membrane supported on the porous alumina ceramic membrane support.

[0058] Comparative Example 2

[0059] A porous alumina ceramic membrane support with an average pore size of 0.1 μm was directly immersed in 10 mL of a 30 wt% concentrated polytetrafluoroethylene dispersion for 5 minutes. After being taken out, the temperature was raised to 100°C at a rate of 2°C / min at a humidity of 40%, and the mixture was kept warm and dried for 3 hours. Then, the temperature was raised to 500°C at a rate of 2°C / min, and the mixture was kept warm and calcined for 3 hours. The mixture was cooled to obtain a polytetrafluoroethylene ceramic membrane, wherein the polytetrafluoroethylene ceramic membrane included a porous alumina ceramic membrane support and a polytetrafluoroethylene membrane loaded on the porous alumina ceramic membrane support.

[0060] Test Example 1

[0061] The pore size and thickness of the tantalum oxide-polytetrafluoroethylene membranes prepared in Examples 1-4 and the tantalum oxide membranes and polytetrafluoroethylene membranes prepared in Comparative Examples 1-2 were tested, and the results are shown in Table 1.

[0062] Table 1

[0063] Average pore size (nm) Thickness (nm) Example 1 4 203 Example 2 7 340 Example 3 6 323 Example 4 9 154 Comparative Example 1 10 198 Comparative Example 2 90 498

[0064] As can be seen from Table 1, the average pore size of the tantalum oxide-polytetrafluoroethylene membrane prepared by the method provided by the present invention is 2-10 nm, and the thickness is 100-400 nm, which is smaller than the pore size of the tantalum oxide membrane and polytetrafluoroethylene membrane prepared in Comparative Examples 1-2.

[0065] Test Example 2

[0066] The ceramic membranes and porous alumina ceramic membranes prepared in Examples 1-4 and Comparative Examples 1-2 were used to filter sulfuric acid, respectively. The metal ion content in the sulfuric acid was tested before and after filtration. The test results are shown in Table 2.

[0067] Table 2

[0068]

[0069] The results in Table 2 show that only when the tantalum oxide-polytetrafluoroethylene ceramic membrane provided by the present invention is used to filter sulfuric acid, the metal ion impurities in the sulfuric acid are significantly reduced compared with those before filtration. Moreover, the content of each metal ion impurity after filtration is lower than that of Comparative Examples 1-2 and the porous alumina ceramic membrane, reaching the standard of electronic-grade sulfuric acid.

[0070] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing a tantalum oxide-polytetrafluoroethylene ceramic membrane, characterized in that: The following steps are involved: (1) mixing a tantalum compound, an alcohol solvent, a chelating agent, a concentrated polytetrafluoroethylene dispersion, and an aqueous hydrogen peroxide solution to obtain a mixed slurry, and aging the mixed slurry to obtain a tantalum sol; (2) The tantalum sol is coated on a porous ceramic membrane support, and then dried and calcined to obtain a tantalum oxide-polytetrafluoroethylene ceramic membrane.

2. The method according to claim 1, wherein The mixing process includes: first mixing the tantalum compound and the alcohol solvent to obtain a first mixed liquid; second mixing the first mixed liquid with the chelating agent and the polytetrafluoroethylene concentrated dispersion to obtain a second mixed liquid; and third mixing the second mixed liquid with the hydrogen peroxide aqueous solution to obtain a third mixed liquid.

3. The method according to claim 2, wherein: The first mixing conditions include: a mixing time of 0.5-2 hours and a stirring speed of 100-700 r / min.

4. The method according to claim 2, wherein: The second mixing conditions include: a mixing time of 0.5-2 hours and a stirring speed of 100-700 r / min.

5. The method according to claim 2, wherein: The conditions for the third mixing include: a time of 1-2 hours and a stirring speed of 100-700 r / min.

6. The method according to any one of claims 2 to 5, wherein: The temperature during the first mixing, the second mixing and the third mixing is 20-40°C.

7. The method according to claim 1, wherein The mass ratio of the tantalum compound to the chelating agent is 1:0.3-0.

7.

8. The method according to claim 1, wherein Relative to 1g of the tantalum compound, the amount of the concentrated polytetrafluoroethylene dispersion is 5-10mL, and the amount of the hydrogen peroxide aqueous solution is 1-3mL; wherein the concentration of the concentrated polytetrafluoroethylene dispersion is 20-60wt%, and the concentration of the hydrogen peroxide aqueous solution is 25-35wt%.

9. The method according to claim 1, wherein The tantalum compound is selected from at least one of tantalum pentachloride, tantalum ethoxide and tantalum methanol.

10. The method according to claim 1, wherein The alcohol solvent is selected from at least one of methanol, ethanol and isopropanol.

11. The method according to claim 1, wherein The chelating agent is selected from triethanolamine and / or acetylacetone.

12. The method according to claim 1, wherein The aging conditions include: temperature of 0-40° C. and time of 3-7 days.

13. The method according to claim 12, wherein: The aging conditions include: a temperature of 0-10°C.

14. The method according to claim 1, wherein The porous ceramic membrane is selected from a porous alumina ceramic membrane, a porous zirconia ceramic membrane or a porous silicon carbide ceramic membrane.

15. The method according to claim 1 or 14, wherein: The average pore size of the porous ceramic membrane is 0.1-10 μm.

16. The method according to claim 1, wherein The drying conditions include: temperature of 80-120° C., heating rate of 1-5° C. / min, and time of 2-4 hours.

17. The method according to claim 1, wherein The calcination conditions include: temperature of 400-600° C., heating rate of 1-5° C. / min, and time of 2-4 hours.

18. A tantalum oxide-polytetrafluoroethylene ceramic membrane prepared by the method according to any one of claims 1 to 17, characterized in that: The tantalum oxide-polytetrafluoroethylene ceramic membrane includes a porous ceramic membrane support and a tantalum oxide-polytetrafluoroethylene membrane supported on the porous ceramic membrane support, wherein the average pore size of the tantalum oxide-polytetrafluoroethylene membrane is 2-10 nm, and the thickness of the tantalum oxide-polytetrafluoroethylene membrane is 100-400 nm.

19. Use of the tantalum oxide-polytetrafluoroethylene ceramic membrane according to claim 18 in refined sulfuric acid.

20. The use according to claim 19, wherein: The refined sulfuric acid meets the standards of electronic grade sulfuric acid.

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