Preparation method of high-purity electronic-grade phosphoric acid

Abstract

This invention provides a method for preparing high-purity phosphoric acid, which uses an electrodialysis apparatus to purify the raw material. The electrodialysis apparatus includes an electrodialysis material that provides hydrogen ions, an anion exchange membrane, and an electrodialysis material that provides hydroxide ions. The raw material solution to be purified is subjected to constant-current electrodialysis, ultimately yielding high-purity phosphoric acid in the anode chamber. The anion exchange membrane comprises a polymeric framework and active groups. The polymeric framework is selected from acid-resistant polymeric frameworks, and the active groups are selected from strongly polar nitrogen-containing groups. The real-time detection concentration c of the high-purity phosphoric acid satisfies the following condition with respect to the current density J of the constant-current electrodialysis: 0. <c×J≤3mA·moL / L·cm 2 The preparation method described above monitors product quality by detecting product concentration rather than product purity. The electrodialysis endpoint can be determined solely by detecting product concentration, thereby avoiding problems such as low purification efficiency and excessive product impurities, effectively improving purification efficiency and effect, and avoiding energy and resource waste.

Description

Technical Field

[0001] This invention belongs to the field of chip manufacturing technology, specifically relating to a method for preparing high-purity electronic-grade phosphoric acid. Background Technology

[0002] Electronic-grade phosphoric acid is a high-purity phosphoric acid, an ultra-high-purity chemical reagent widely used in the electronics industry. It is primarily used for wet cleaning and etching of chips, including cleaning before substrate coating, etching during photolithography and final resist removal, as well as cleaning and etching of insulating films, semiconductor films, conductor films, and organic materials during silicon wafer fabrication. Electronic-grade reagents are crucial raw materials in chip manufacturing. As chip manufacturing processes continue to shrink, the quality requirements for phosphoric acid become increasingly stringent, and the production process becomes increasingly challenging.

[0003] After obtaining the product, phosphoric acid needs to undergo quality testing to determine if the final product quality meets electronic grade requirements. In existing electrodialysis purification processes, to ensure product quality meets requirements, continuous purity testing is required to determine the electrodialysis endpoint. This process is cumbersome, cannot achieve continuous industrial production, and has low purification efficiency. Furthermore, the excessive levels of phosphoric acid impurities during electrodialysis are irreversible. Therefore, if electrodialysis is not terminated at an appropriate time, impurities exceeding standard requirements cannot be further processed, resulting in resource waste. Therefore, achieving a simple and efficient balance between purification efficiency and purification effect in electrodialysis purification is crucial. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to provide a method for preparing high-purity phosphoric acid. The method can achieve a simple and efficient balance between purification efficiency and purification effect, and while improving purification efficiency, it ensures that the high-purity phosphoric acid obtained meets the requirements of electronic-grade phosphoric acid, with the metal ion content all below 10 ppb.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] A method for preparing high-purity phosphoric acid includes the following steps: purifying the raw material using an electrodialysis apparatus to obtain high-purity phosphoric acid; the electrodialysis apparatus comprises an electrodialysis material that provides hydrogen ions, an anion exchange membrane, and an electrodialysis material that provides hydroxide ions; the anion exchange membrane divides the electrodialysis apparatus into an anode chamber and a cathode chamber; the electrodialysis material that provides hydrogen ions is inserted into the anode chamber, and the electrodialysis material that provides hydroxide ions is inserted into the cathode chamber; the cathode chamber contains a raw material solution to be purified, and high-purity phosphoric acid is finally obtained in the anode chamber through constant current electrodialysis;

[0007] The anion exchange membrane comprises a polymeric framework and active groups, wherein the polymeric framework is selected from acid-resistant polymeric frameworks and the active groups are selected from strongly polar nitrogen-containing groups;

[0008] The real-time detection concentration c of high-purity phosphoric acid in the anode chamber satisfies the following condition with the current density J set by the constant current electrodialysis: 0 <c×J≤3mA·moL / L·cm 2 .

[0009] In some embodiments, the real-time detection concentration c of high-purity phosphoric acid in the anode chamber satisfies the following condition with respect to the current density J set by the constant current electrodialysis: 0.5 ≤ c × J ≤ 1.5 mA·mol / L·cm 2 .

[0010] In some embodiments, the current density J set for the constant current electrodialysis satisfies: 0 <J≤50mA / cm 2 .

[0011] In some embodiments, the current density J set for the constant current electrodialysis satisfies: 1 ≤ J ≤ 30 mA / cm² 2 .

[0012] In some embodiments, the active group is selected from at least one of primary amine groups, secondary amine groups, tertiary amine groups, quaternary ammonium groups, and imidazole groups.

[0013] In some preferred embodiments, the active group is selected from at least one of quaternary ammonium groups and imidazole groups.

[0014] In some embodiments, the polymeric backbone is selected from at least one of chitosan, polyphenylene ether, polyvinyl fluoride, polyaryletherketone, polyimide, and polysulfone; preferably, the polymeric backbone is selected from at least one of polyvinyl fluoride and polyimide.

[0015] In some embodiments, the electrodialysis material capable of providing hydrogen ions is selected from at least one of an electrode and a bipolar membrane; and / or, the electrodialysis material capable of providing hydroxide ions is selected from at least one of an electrode and a bipolar membrane.

[0016] In some embodiments, the electrode is selected from at least one of a platinum electrode, a titanium electrode, a ruthenium electrode, and an iridium electrode; preferably, the electrode is selected from a platinum electrode.

[0017] In some embodiments, the anode chamber contains pure water or a high-purity phosphoric acid solution.

[0018] This invention provides a method for preparing high-purity phosphoric acid. The method employs constant current electrodialysis technology, which can effectively improve purification efficiency while ensuring product quality, and simply and efficiently prepare electronic-grade phosphoric acid. This invention optimizes the anion exchange membrane and controls the real-time detection concentration c of high-purity phosphoric acid in the anode chamber and the current density J set by the constant current electrodialysis, so that c × J meets specific conditions (0 < ... <c×J≤3mA·moL / L·cm 2 This method effectively avoids the problem of excessive metal ion content caused by proton leakage during electrodialysis, ensuring that the metal ion content in the prepared high-purity phosphoric acid is within 10 ppb, thus guaranteeing the controllability of phosphoric acid quality. The preparation method allows for monitoring product quality by detecting product concentration rather than product purity. Therefore, in industrial production, once the current density is fixed, the electrodialysis endpoint can be determined solely by detecting the product concentration, thereby avoiding the problems of low purification efficiency due to premature termination of electrodialysis and excessive product impurities due to failure to terminate electrodialysis in a timely manner. This effectively improves purification efficiency and effect, avoiding energy and resource waste. The anion exchange membrane optimized by this invention has a positive effect on phosphoric acid purification and is more stable, ensuring that the product quality meets the requirements of electronic-grade phosphoric acid within a large c×J range, thereby further improving purification efficiency.

[0019] The method of this invention has advantages such as high impurity removal rate, simple process steps, and low solid and liquid waste. Furthermore, it can use low-purity phosphoric acid, phosphates, etc., greatly expanding the sources of raw materials. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the preparation method of the present invention. Detailed Implementation

[0021] Unless otherwise specified, the experimental methods described in the following embodiments of the present invention are generally performed under conventional conditions or as recommended by the manufacturer. All commonly used chemical reagents used in the embodiments are commercially available products.

[0022] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0023] The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or device that includes a series of steps is not limited to the steps or modules listed, but may optionally include steps not listed, or may optionally include other steps inherent to such process, method, product, or device.

[0024] In this invention, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0025] This embodiment provides a method for preparing high-purity phosphoric acid, comprising the following steps: purifying the raw material using an electrodialysis apparatus to obtain high-purity phosphoric acid; the electrodialysis apparatus includes an electrodialysis material that provides hydrogen ions, an anion exchange membrane, and an electrodialysis material that provides hydroxide ions; the anion exchange membrane divides the electrodialysis apparatus into an anode chamber and a cathode chamber; the electrodialysis material that provides hydrogen ions is inserted into the anode chamber, and the electrodialysis material that provides hydroxide ions is inserted into the cathode chamber; the cathode chamber contains a raw material solution to be purified, and high-purity phosphoric acid is finally obtained in the anode chamber through constant current electrodialysis;

[0026] The anion exchange membrane comprises a polymeric framework and active groups, wherein the polymeric framework is selected from acid-resistant polymeric frameworks and the active groups are selected from strongly polar nitrogen-containing groups;

[0027] The real-time detection concentration c of high-purity phosphoric acid in the anode chamber satisfies the following condition with the current density J set by the constant current electrodialysis: 0 <c×J≤3mA·moL / L·cm 2 .

[0028] By optimizing the anion exchange membrane and controlling the real-time detection concentration c of high-purity phosphoric acid in the anode chamber and the current density J set by constant current electrodialysis, product quality can be monitored by detecting product concentration rather than product purity, thereby effectively improving purification efficiency while ensuring product quality.

[0029] In some embodiments, the real-time detection concentration c of high-purity phosphoric acid in the anode chamber and the current density J set by the constant current electrodialysis satisfy the following condition: 0.5 ≤ c × J ≤ 1.5 mA·mol / L·cm 2 .

[0030] Specifically, the real-time detection concentration c of high-purity phosphoric acid in the anode chamber satisfies the current density J set by the constant current electrodialysis: c × J equals 0.1 mA·mol / L·cm. 2 0.3 mA·mol / L·cm 2 0.5 mA·mol / L·cm 2 0.8 mA·mol / L·cm 2 1 mA·mol / L·cm 2 1.2 mA·mol / L·cm 2 1.5 mA·mol / L·cm2 1.8 mA·mol / L·cm 2 2mA·mol / L·cm 2 2.3 mA·mol / L·cm 2 2.5 mA·mol / L·cm 2 2.75 mA·mol / L·cm 2 3mA·mol / L·cm 2 .

[0031] In the preparation method of this invention, the method for real-time detection of the concentration of high-purity phosphoric acid in the anode chamber includes, but is not limited to, pH, refractive index, conductivity or equivalent methods (all of the above parameters can be converted into phosphoric acid concentration through theoretical or empirical formulas), and the phosphoric acid concentration on the high-purity side of the electrodialysis unit is monitored in real time.

[0032] In some embodiments, the current density J set for the constant current electrodialysis satisfies: 0 <J≤50mA / cm 2 .

[0033] In some preferred embodiments, the constant current electrodialysis is set to a current density J that satisfies: 1 ≤ J ≤ 30 mA / cm² 2 .

[0034] In some embodiments, the active group is selected from at least one of primary amine groups, secondary amine groups, tertiary amine groups, quaternary ammonium groups, and imidazole groups; preferably, the active group is selected from at least one of quaternary ammonium groups and imidazole groups. Anion exchange membranes having the above-mentioned active groups have relatively better compatibility with phosphate ions.

[0035] In some embodiments, the polymeric backbone is selected from at least one of chitosan, polyphenylene ether, polyvinyl fluoride, polyaryletherketone, polyimide, and polysulfone; preferably, the polymeric backbone is selected from at least one of polyvinyl fluoride and polyimide. The aforementioned polymeric backbones are more stable when used in the preparation of phosphoric acid.

[0036] The anion exchange membrane optimized by this invention has a positive effect on the purification of phosphoric acid and is more stable. It can ensure that the product quality meets the requirements of electronic-grade phosphoric acid within a large c×J range, thereby further improving the purification efficiency.

[0037] In some embodiments, the electrodialysis apparatus may be connected in series or parallel to improve efficiency.

[0038] The raw materials for preparing high-purity phosphoric acid according to this invention are widely available, including low-purity phosphoric acid and phosphates.

[0039] The high-purity phosphoric acid described in this invention uses the SEMI standard, with G1 and above considered as high-purity phosphoric acid, and the standard is a metal ion content ≤10ppb.

[0040] The following description is based on specific embodiments.

[0041] Examples 1-5

[0042] Examples 1-5 each provide a method for preparing high-purity phosphoric acid, wherein the preparation method utilizes an electrodialysis apparatus to purify a low-purity phosphoric acid raw material solution. The electrodialysis apparatus comprises an electrodialysis material providing hydrogen ions, an anion exchange membrane, and an electrodialysis material providing hydroxide ions. The anion exchange membrane divides the electrodialysis apparatus into an anode chamber and a cathode chamber. The electrodialysis material providing hydrogen ions is inserted into the anode chamber, and the electrodialysis material providing hydroxide ions is inserted into the cathode chamber. A high-purity phosphoric acid solution and a low-purity phosphoric acid raw material solution are respectively introduced into the anode and cathode chambers of the electrodialysis apparatus. Electrodialysis is initiated by setting an electrodialysis current density. During the process, the concentration of the high-purity phosphoric acid solution in the anode chamber is monitored in real time, ensuring that the relationship between the real-time detected concentration c of the high-purity phosphoric acid and the current density J set for constant current electrodialysis meets the requirements of this invention. The composition of the electrodialysis apparatus and electrodialysis conditions of each example are shown in Table 1, where the concentration of phosphoric acid in the anode chamber in Table 1 is the concentration of phosphoric acid in the anode chamber when electrodialysis is stopped.

[0043] Comparative Examples 1-5

[0044] Comparative Examples 1 to 5 each provide a method for preparing high-purity phosphoric acid. Except for the electrodialysis parameters or anion exchange membrane, all other methods are the same as those in the above examples, as shown in Table 1.

[0045] Table 1 Preparation Information

[0046]

[0047] The metal ion content of the products prepared in the above examples and comparative examples was detected.

[0048] The methods for detecting metal ion content are as follows:

[0049] The content of 13 metal ions (Ba / Ca / Cd / Co / Cr / Cu / Fe / Mg / Mn / Na / Ni / Pb / Zn) can be detected by ICP-OES or ICP-MS, and the highest metal ion content can be directly compared.

[0050] The test results are shown in Table 2:

[0051] Table 2 Detection Results / ppb

[0052]

[0053]

[0054] Note: The results in Table 2 are converted to 8.67 mol / L concentrated phosphoric acid, i.e., 85% mass fraction phosphoric acid.

[0055] The above results show that the metal ion content in the high-purity phosphoric acid prepared by the method of the present invention (Examples 1-5) is all below 10 ppb, which meets the quality requirements of high-purity electronic-grade phosphoric acid. This indicates that the method of the present invention can control the product quality simply by monitoring the product concentration, and is simple and efficient.

[0056] In the preparation methods of Comparative Examples 1-3, the product of the real-time detected concentration c of phosphoric acid in the anode chamber and the current density J set by constant current electrodialysis does not satisfy 0. <c×J≤3mA·moL / L·cm 2 This leads to proton leakage during the purification process, resulting in a metal ion content in the product exceeding 10 ppb, which does not meet the quality requirements for electronic-grade phosphoric acid.

[0057] Compared to Example 1, the preparation method of Comparative Example 4 used an anion exchange membrane with polyvinyl chloride as the polymer backbone, which resulted in insufficient acid resistance of the membrane and increased proton leakage, leading to a metal ion content in the product exceeding 200 ppm, failing to meet the quality requirements of electronic-grade phosphoric acid. The preparation method of Comparative Example 5 used a pyridine (six-membered ring) active group in the anion exchange membrane, resulting in lower polarity compared to imidazole (five-membered ring), thus causing insufficient ion repulsion and increased proton leakage, also failing to meet the quality requirements of electronic-grade phosphoric acid. This demonstrates that the choice of anion exchange membrane material not only affects the purification effect but also the c×J range that meets the quality requirements. When the anion exchange membrane material is not selected within the scope of this invention, even if the c×J meets the requirements of this invention, electronic-grade phosphoric acid cannot be prepared. This may be because other anion exchange membrane materials result in a smaller range of c×J options that meet the quality requirements of electronic-grade phosphoric acid. The anion exchange membrane optimized in this invention has a positive effect on phosphoric acid purification and is more stable, ensuring that the product quality meets the requirements of electronic-grade phosphoric acid within a wider c×J range, thereby further improving purification efficiency.

[0058] In summary, by optimizing the anion exchange membrane and controlling the real-time detection concentration c of high-purity phosphoric acid in the anode chamber and the current density J set by constant current electrodialysis, this invention can monitor product quality by detecting product concentration rather than product purity, thereby effectively improving purification efficiency while ensuring product quality.

[0059] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0060] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing high-purity phosphoric acid, comprising the following steps: High-purity phosphoric acid is obtained by purifying raw materials using an electrodialysis apparatus. The electrodialysis apparatus comprises an electrodialysis material that provides hydrogen ions, an anion exchange membrane, and an electrodialysis material that provides hydroxide ions. The anion exchange membrane divides the electrodialysis apparatus into an anode chamber and a cathode chamber. The electrodialysis material that provides hydrogen ions is inserted into the anode chamber, and the electrodialysis material that provides hydroxide ions is inserted into the cathode chamber. The cathode chamber contains the raw material solution to be purified. Through constant-current electrodialysis, high-purity phosphoric acid is finally obtained in the anode chamber. The anion exchange membrane comprises a polymer matrix and active groups, wherein the polymer matrix is ​​selected from an acid-resistant polymer framework, and the active groups are selected from highly polar nitrogen-containing groups; The constant current electrodialysis was set to a current density of J mA / cm². 2 The real-time detection concentration of high-purity phosphoric acid in the anode chamber is c mol / L, and the electrodialysis process satisfies: 0 <c×J≤3mA·moL / L·cm 2 ; The current density J set for the constant current electrodialysis satisfies: 1 ≤ J ≤ 30 mA / cm² 2 ; The active group is selected from at least one of primary amine group, secondary amine group, tertiary amine group, quaternary ammonium group and imidazole group; The polymer backbone is selected from at least one of chitosan, polyphenylene ether, polyvinyl fluoride, polyaryletherketone, polyimide and polysulfone; The electrodialysis material capable of providing hydrogen ions is selected from at least one of an electrode and a bipolar membrane, and the electrodialysis material capable of providing hydroxide ions is selected from at least one of an electrode and a bipolar membrane.

2. The method for preparing high-purity phosphoric acid as described in claim 1, characterized in that, The real-time detection concentration c of high-purity phosphoric acid in the anode chamber satisfies the following condition with respect to the current density J set by the constant current electrodialysis: 0.5 ≤ c × J ≤ 1.5 mA·mol / L·cm 2 .

3. The method for preparing high-purity phosphoric acid as described in claim 1, characterized in that, The active group is selected from at least one of quaternary ammonium groups and imidazole groups.

4. The method for preparing high-purity phosphoric acid as described in claim 1, characterized in that, The polymer backbone is selected from at least one of polyvinyl fluoride and polyimide.

5. The method for preparing high-purity phosphoric acid as described in claim 1, characterized in that, The electrode is selected from at least one of platinum electrode, titanium electrode, ruthenium electrode, and iridium electrode.

6. The method for preparing high-purity phosphoric acid as described in claim 5, characterized in that, The electrode is selected from platinum electrodes.

7. The method for preparing high-purity phosphoric acid as described in claim 1, characterized in that, The anode chamber contains pure water or a high-purity phosphoric acid solution.

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