Preparation method of high-purity ultra-clean hydroxylamine aqueous solution

Abstract

The invention discloses a preparation method of a high-purity ultra-clean hydroxylamine aqueous solution. A four-stage purification process comprises the following steps: 1) low-temperature chelation-ceramic membrane metal removal; 2) molecular sieve membrane rectification decomposition prevention; 3) pulse electrodialysis reversal deep desalination; and 4) gradient filtration terminal refining. According to the preparation method of the high-purity ultra-clean hydroxylamine aqueous solution, a low-temperature molecular sieve membrane rectification technology is adopted, hydroxylamine liquid-phase thermal decomposition is avoided through a vapor phase separation mechanism, and the decomposition rate is reduced to 1t from 15% of a traditional process; the method comprises the following steps of: removing metal through chelation-electrodialysis synergistically, ensuring that Fe and Cu ion residues are less than or equal to 0.05 ppb through a thiosemicarbazide-bipolar membrane system, ensuring the nitrogen environment in the whole process, ensuring that the dissolved oxygen is less than or equal to 5ppb, replacing liquid phase distillation with molecular sieve membrane vapor phase separation, solving hydroxylamine liquid phase thermal decomposition, and breaking through the trace metal removal limit by combining thiosemicarbazide-bipolar membrane synergistically removing impurities. And then through nanoscale terminal filtration, the metal / particle control reaches ppb-level limit which is superior to the SEMI standard, and double spanning of quality and cost is realized.

Description

Technical Field

[0001] The invention relates to the technical field of hydroxylamine aqueous solution preparation, in particular to a method for preparing a high-purity ultra-clean hydroxylamine aqueous solution. Background Art

[0002] High-purity hydroxylamine aqueous solution has a wide range of uses, especially in the electronics industry. It is a key reagent for integrated circuit photoresist stripping and liquid crystal panel cleaning. Its purity directly affects the chip yield. Existing industrial-grade hydroxylamine (purity 98%-99%) contains a large amount of Na + , K + 、Fe 2+ 、Cl - and organic amine by-products, which cannot meet the semiconductor process requirements.

[0003] Currently, hydroxylamine aqueous solutions are prepared using traditional distillation methods. However, since hydroxylamine is easily decomposed by heat, it leads to low yield and impurity enrichment. Conventional ion exchange methods easily lead to residual organic matter in the resin of the ion exchange column and fail to remove nanoscale colloidal particles. In addition, existing methods for preparing hydroxylamine aqueous solutions have difficulty in controlling the removal of metals at the ppb level, all of which affect the purity of the hydroxylamine aqueous solution. Therefore, we have proposed a method for preparing a high-purity, ultra-clean hydroxylamine aqueous solution to address the above-mentioned problems. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing a high-purity, ultra-clean hydroxylamine aqueous solution to solve the problems mentioned in the above background art, namely, that the current method for preparing a hydroxylamine aqueous solution easily causes hydroxylamine to decompose upon heating, that nanoparticles remain in the solution, and that ppb-level metals are difficult to remove.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for preparing a high-purity ultra-clean hydroxylamine aqueous solution, comprising the following steps:

[0006] (a) Raw material treatment: Add a composite chelating agent of EDTA disodium salt and thiosemicarbazide (molar ratio of 1:0.2-0.5) to an aqueous solution of industrial hydroxylamine at 0-10°C under nitrogen protection, and filter through a 0.1 μm ceramic membrane with a transmembrane pressure difference of 0.10-0.25 MPa.

[0007] (b) Molecular sieve membrane distillation: The filtrate is fed into a molecular sieve membrane distillation tower to separate the light and heavy components at an absolute pressure of 5-15 kPa and a tower top temperature of 30-40°C. The hydroxylamine vapor flux is 1.5-2.5 kg / (m 2 h);

[0008] (c) Asymmetric electrodialysis: The distillation product passes through a bipolar membrane-anion membrane combined electrodialysis device at a current density of 100-150A / m 2 , operate under the condition of pulse reversal period of 180-240 seconds;

[0009] (d) Terminal fine filtration: The electrodialysis output liquid passes through a 0.05 μm filter, a mixed bed resin bed, and a 0.02 μm terminal filter membrane in sequence, and is stored in a nitrogen-filled sealed storage tank.

[0010] Preferably, the molar ratio of EDTA disodium salt to thiosemicarbazide in the composite chelating agent is 1:0.3±0.05, and the added amount is 2.0-3.0 times the total molar amount of metal ions.

[0011] Preferably, the molecular sieve membrane is an MFI type hydrophobic zeolite membrane (SiO2 / Al2O3≥200), the membrane surface has a perfluoroalkylsilane self-assembled layer (FAS-17), and the water contact angle is ≥150°.

[0012] Preferably, a vapor recompression system (VRC) is provided in step (b) to compress the overhead steam to 45-55° C. as a reboiler heat source, thereby reducing energy consumption by 35-40%.

[0013] Preferably, the electrodialysis uses a perfluorosulfonic acid / carboxylic acid double-layer anion membrane (thickness 150-200 μm), and the Cl- migration number t - ≥0.98, operating temperature 20±2℃.

[0014] Preferably, in the pulse inversion mode, the forward current density is 110-130 A / m 2 , the reverse current density is 1.05-1.2 times that of the forward current, and the reverse time accounts for 10-15% of the cycle.

[0015] Preferably, the mixed bed resin is H + The OH-type strong acid cation resin and the OH-type strong base anion resin are loaded in a volume ratio of 1.1:1-1.3:1, with a linear speed of 10-15m / h.

[0016] Preferably, the cationic resin is a gel-type styrene-divinylbenzene copolymer (cross-linking degree 8%), and the anionic resin is a macroporous quaternized polyacrylate.

[0017] Preferably, the terminal filtration adopts a three-layer gradient structure: the first layer: 0.05 μm nylon 66 filter element; the middle layer: nuclear grade mixed bed resin (filling height-diameter ratio 2.5:1-3.5:1); the last layer: 0.02 μm PTFE pleated filter membrane.

[0018] Preferably, the nitrogen-filled sealed storage tank is a double-layer vacuum insulation structure, the vacuum degree of the interlayer is ≤0.01Pa, and the inner wall is electrolytically polished (Ra ≤0.2μm).

[0019] Compared with the prior art, the present invention has the following beneficial effects: the method for preparing a high-purity, ultra-clean hydroxylamine aqueous solution adopts low-temperature molecular sieve membrane distillation technology, avoids the liquid-phase thermal decomposition of hydroxylamine through a vapor phase separation mechanism, and reduces the decomposition rate from 15% in the traditional process to <0.5%. Through chelation-electrodialysis synergistic metal removal, through a thiosemicarbazide-bipolar membrane system, the residual Fe and Cu ions are reduced to ≤0.05 ppb. A nitrogen environment is guaranteed throughout the entire process, and dissolved oxygen is ≤5 ppb. Molecular sieve membrane vapor phase separation replaces liquid-phase distillation to solve the problem of liquid-phase thermal decomposition of hydroxylamine. Combined with thiosemicarbazide-bipolar membrane synergistic impurity removal, the trace metal removal limit is broken. After nano-scale terminal filtration, metal / particle control reaches the ppb-level limit, which is better than the SEMI standard, achieving a double breakthrough in quality and cost. DETAILED DESCRIPTION

[0020] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0021] Example 1

[0022] The present invention provides a technical solution: a method for preparing a high-purity ultra-clean hydroxylamine aqueous solution, comprising the following steps:

[0023] At 0-10°C and under nitrogen protection, a composite chelating agent of EDTA disodium salt and thiosemicarbazide (molar ratio 1:0.2-0.5) was added to the industrial hydroxylamine aqueous solution in an amount of 2.0-3.0 times the total molar amount of metal ions, and the mixture was cross-flow filtered through a 0.1 μm ceramic membrane with a transmembrane pressure difference of 0.10-0.25 MPa;

[0024] The filtrate is sent to a molecular sieve membrane distillation tower. The molecular sieve membrane is an MFI type hydrophobic zeolite membrane (SiO2 / Al2O3≥200). The membrane surface has a perfluoroalkylsilane self-assembled layer (FAS-17). The water contact angle is ≥150°. The light and heavy components are separated at an absolute pressure of 5-15kPa and a tower top temperature of 30-40°C. The hydroxylamine vapor flux is 1.5-2.5kg / (m 2 h) Install a vapor recompression system (VRC) to compress the overhead steam to 45-55°C as a reboiler heat source, reducing energy consumption by 35-40%;

[0025] The distillation product passes through a bipolar membrane-anion membrane combined electrodialysis device, and the electrodialysis uses a perfluorosulfonic acid / carboxylic acid double-layer anion membrane (thickness 150-200μm). - Migration number t - ≥0.98, operating temperature 20±2℃, current density 100-150A / m2 , operate under the condition of pulse reversal cycle 180-240 seconds, in pulse reversal mode, the forward current density is 110-130A / m 2 , the reverse current density is 1.05-1.2 times that of the forward current, and the reverse time accounts for 10-15% of the cycle;

[0026] The electrodialysis output liquid is sequentially filtered through a 0.05 μm filter, a mixed bed resin bed, and a 0.02 μm terminal filter membrane, and stored in a nitrogen-filled sealed tank. + Type strong acid cationic resin and OH - The strong base anion resin is filled in a volume ratio of 1.1:1-1.3:1, with a linear speed of 10-15 m / h. The cation resin is a gel-type styrene-divinylbenzene copolymer (cross-linking degree 8%), and the anion resin is a macroporous quaternized polyacrylate.

[0027] The terminal filtration adopts a three-layer gradient structure: the first layer: 0.05μm nylon 66 filter element; the middle layer: nuclear-grade mixed bed resin (filling height-to-diameter ratio 2.5:1-3.5:1); the last layer: 0.02μm PTFE pleated filter membrane.

[0028] The nitrogen-filled sealed storage tank has a double-layer vacuum insulation structure, the interlayer vacuum degree is ≤0.01Pa, and the inner wall is electrolytically polished (Ra≤0.2μm).

[0029] 1000L of industrial hydroxylamine aqueous solution was treated with impurities according to the above process. The results of each stage are shown in the following table:

[0030] Processing stage Fe content (ppb) <![CDATA[Na + (ppb)]]> Particles (pieces / m) raw material 48.7 185.3 <![CDATA[>10 6 ]]> After ceramic membrane filtration 1.2 32.5 <![CDATA[5.2×10 2 ]]> After membrane distillation 0.8 28.1 <![CDATA[3.1×10 2 ]]> After electrodialysis 0.3 0.9 87 After terminal purification ＜0.05 ＜0.05 3

[0031] Example 2

[0032] According to the method of Example 1, 500 kg of industrial hydroxylamine (50 wt%, containing Fe50 ppb, Na + The impurity removal treatment was carried out at a temperature of 5°C, a chelating agent of 0.8 kg / t, a molecular sieve membrane distillation tower vacuum of 8 kPa, a reflux ratio of 0.8:1, an electrodialysis voltage of 18 V, a reversal cycle of 200 / 20 s, and a terminal filter element pressure difference of ≤0.3 bar.

[0033] The results of industrial hydroxylamine treatment are shown in the following table:

[0034] index result Test standards purity 99.9992％ HPLC-ELSD Fe <0.01ppb ICP-MS Particles (0.1 μm) 2 cells / mL SEMIP32 TOC 1.8ppb ASTM D7573

[0035] Example 3

[0036] Industrial hydroxylamine containing 500 ppm of Na2SO4 was treated with impurities according to the method of Example 1, with a chelating agent increment of 30%, ceramic membrane filtration for 3 times, and electrodialysis using a three-stage membrane stack in series. The rest was the same as in Example 2.

[0037] The processing results are shown in the following table:

[0038] impurities Before treatment After processing <![CDATA[Na + ]]> 185ppm 0.07ppb <![CDATA[SO4 2- ]]> 320ppm <0.1ppb Conductivity 450μS / cm 0.055μS / cm

[0039] Example 4

[0040] The industrial hydroxylamine aqueous solution was treated with impurities according to the method of Example 1, except that the impurities exceeding the standard were added to the raw material, and the additives were: FeCl3 (200 ppb), nano-SiO2 (10 6 / mL), methylamine (500ppm).

[0041] The impurity removal treatment was carried out according to the method of Example 1, and the treatment results are shown in the following table:

[0042] Impurity type Residual amount Removal rate <![CDATA[Fe 3+ ]]> <0.01ppb ＞99.995％ <![CDATA[Nanometer SiO2]]> 1 cell / mL (0.1 μm) 99.9999％ Methylamine ND*(GC-MS) ＞99.99％

[0043] *Detection limit: 0.05ppm for methylamine

[0044] It can be seen from the above examples that the method of the present invention achieves superior quality through the triple technological breakthrough of "low-temperature steam phase separation + chelation-electrodialysis synergy + nano-scale terminal filtration", with metal / particle control reaching the ppb level limit, which is better than the SEMI standard, and green manufacturing, zero solvent in the entire process, and 90% reduction in hazardous waste emissions.

[0045] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a high-purity, ultra-clean hydroxylamine aqueous solution, characterized in that: The steps include: (a) Raw material treatment: Add a composite chelating agent of EDTA disodium salt and thiosemicarbazide (molar ratio of 1:0.2-0.5) to an aqueous solution of industrial hydroxylamine at 0-10°C under nitrogen protection, and filter through a 0.1 μm ceramic membrane with a transmembrane pressure difference of 0.10-0.25 MPa. (b) Molecular sieve membrane distillation: The filtrate is fed into a molecular sieve membrane distillation tower to separate the light and heavy components at an absolute pressure of 5-15 kPa and a tower top temperature of 30-40°C. The hydroxylamine vapor flux is 1.5-2.5 kg / (m 2 h); (c) Asymmetric electrodialysis: The distillation product passes through a bipolar membrane-anion membrane combined electrodialysis device at a current density of 100-150A / m 2 , operate under the condition of pulse reversal period of 180-240 seconds; (d) Terminal fine filtration: The electrodialysis output liquid passes through a 0.05 μm filter, a mixed bed resin bed, and a 0.02 μm terminal filter membrane in sequence, and is stored in a nitrogen-filled sealed storage tank.

2. The method for preparing a high-purity ultra-clean hydroxylamine aqueous solution according to claim 1, wherein: The molar ratio of EDTA disodium salt to thiosemicarbazide in the composite chelating agent is 1:0.3±0.05, and the added amount is 2.0-3.0 times the total molar amount of metal ions.

3. The method for preparing a high-purity ultra-clean hydroxylamine aqueous solution according to claim 1, wherein: The molecular sieve membrane is an MFI type hydrophobic zeolite membrane (SiO2 / Al2O3≥200), the membrane surface has a perfluoroalkylsilane self-assembled layer (FAS-17), and the water contact angle is ≥150°.

4. The method for preparing a high-purity ultra-clean hydroxylamine aqueous solution according to claim 1, wherein: In step (b), a vapor recompression system (VRC) is provided to compress the overhead steam to 45-55° C. as a reboiler heat source, thereby reducing energy consumption by 35-40%.

5. The method for preparing a high-purity ultra-clean hydroxylamine aqueous solution according to claim 1, wherein: The electrodialysis uses a perfluorosulfonic acid / carboxylic acid double-layer anion membrane (thickness 150-200 μm), and the Cl- migration number t - ≥0.98, operating temperature 20±2℃.

6. The method for preparing a high-purity ultra-clean hydroxylamine aqueous solution according to claim 1, wherein: In the pulse reversal mode, the forward current density is 110-130A / m 2 , the reverse current density is 1.05-1.2 times that of the forward current, and the reverse time accounts for 10-15% of the cycle.

7. The method for preparing a high-purity ultra-clean hydroxylamine aqueous solution according to claim 1, wherein: The mixed bed resin is H + The OH-type strong acid cation resin and the OH-type strong base anion resin are loaded in a volume ratio of 1.1:1-1.3:1, with a linear speed of 10-15m / h.

8. The method for preparing a high-purity ultra-clean hydroxylamine aqueous solution according to claim 7, characterized in that: The cationic resin is a gel-type styrene-divinylbenzene copolymer (cross-linking degree 8%), and the anionic resin is a macroporous quaternary ammonium polyacrylate.

9. The method for preparing a high-purity ultra-clean hydroxylamine aqueous solution according to claim 1, wherein: The terminal filtration adopts a three-layer gradient structure: the first layer: 0.05μm nylon 66 filter element; Middle layer: nuclear grade mixed bed resin (filling height-to-diameter ratio 2.5:1-3.5:1); last layer: 0.02μm PTFE pleated filter membrane.

10. The method for preparing a high-purity ultra-clean hydroxylamine aqueous solution according to claim 1, characterized in that: The nitrogen-filled sealed storage tank is a double-layer vacuum insulation structure, the vacuum degree of the interlayer is ≤0.01Pa, and the inner wall is electrolytically polished (Ra ≤0.2μm).