Preparation method of ultra-pure electronic grade ethanolamine reagent

Abstract

The invention relates to a preparation method of an ultra-pure electronic-grade ethanolamine reagent, and belongs to the technical field of purification of electronic chemicals. The preparation method aims at solving the problem that homologous organic impurities in industrial-grade ethanolamine raw materials coexist with metal ion impurities such as sodium and potassium and are difficult to synchronously and efficiently remove. According to the method, a four-step synergistic purification strategy of precise microfiltration, deep ion exchange, vacuum distillation and terminal nanofiltration is adopted. According to the process, metal ions are removed through ion exchange, main body separation of homologous organic impurities is achieved through vacuum rectification, and finally, residual trace impurities are removed through terminal nanofiltration membrane refining. According to the method provided by the invention, homologous organic impurities (such as monoethanolamine, diethanolamine and triethanolamine) and trace metal ion impurities (such as Na < + > and K < + >) which are difficult to separate from the ethanolamine reagent can be effectively removed.

Description

Technical Field

[0001] This invention relates to the field of ultra-high purity electronic chemical preparation technology, and in particular to a method for preparing ultra-high purity electronic-grade ethanolamine reagents. Background Technology

[0002] Electronic-grade ethanolamine reagents are essential key chemicals in semiconductor and display panel manufacturing, widely used in core processes such as cleaning, photoresist development, wafer cleaning and thin film etching, and electroplating. Their purity directly determines the yield, electrical performance, and long-term reliability of integrated circuits.

[0003] Electronic-grade chemicals must meet extremely high standards, which not only require a main content of >99.99% and strict control of particulate matter, but also the control of two key impurities: homologous organic impurities and sodium and potassium ions, both of which must be kept at low levels.

[0004] Existing technical solutions, such as CN103102279A, mainly solve the problems of particulate and ion contamination by combining ion exchange and precision microfiltration. However, how to synergistically and deeply remove homologous organic impurities and sodium and potassium ions in the purification process remains an unsolved problem. Summary of the Invention

[0005] To address the shortcomings of the existing technology, this application provides a method for preparing ultra-high purity electronic-grade ethanolamine reagents, aiming to solve the problem of high content of homologous organic impurities and sodium and potassium ions in ethanolamine reagents.

[0006] To achieve the above objectives, the present invention provides a method for preparing ultra-high purity electronic-grade ethanolamine reagents, wherein the ethanolamine is monoethanolamine or diethanolamine, and the preparation method includes the following steps:

[0007] The raw materials are initially purified using cation exchange resin and anion exchange resin; then vacuum distillation is performed, and finally, a polyamide composite nanofiltration membrane is used for terminal nanofiltration. The permeate is collected as the final product.

[0008] In some embodiments, when the ethanolamine is monoethanolamine, the operating conditions for vacuum distillation are: absolute pressure of 1.0 to 10.0 kPa; reboiler temperature of 80 to 120°C; and reflux ratio of 5:1 to 15:1.

[0009] In some embodiments, when the ethanolamine is diethanolamine, the operating conditions for vacuum distillation are: absolute pressure 1.0–3.0 kPa; reboiler temperature 90–120 °C; reflux ratio 5:1–10:1.

[0010] As a further improvement, the operating conditions for the preliminary purification are: temperature of 25–40°C; flow rate of 2–4 BV / h.

[0011] As a further improvement, the operating conditions for the terminal nanofiltration are: temperature of 30–45°C; and operating pressure of 1.5–2.5 MPa.

[0012] As a further improvement, prior to the preliminary purification, a precision microfiltration step is included, wherein the precision microfiltration employs a polytetrafluoroethylene precision microfiltration membrane module with a pore size of 0.1–0.2 μm, and the filtration is performed under operating conditions of 0.3–0.6 MPa and 50–65 °C.

[0013] As a further improvement, the preliminary purification involves passing the raw material sequentially through one or more cation exchange resin columns in series, followed by one or more anion exchange resin columns in series.

[0014] As a further improvement, the cation exchange resin can be one of carboxyl polystyrene resin and sulfonic acid polystyrene resin, preferably sulfonic acid polystyrene resin; the anion exchange resin can be one of primary amine polystyrene resin and quaternary ammonium polystyrene resin, preferably quaternary ammonium polystyrene resin.

[0015] In some embodiments, the number of theoretical plates during vacuum distillation is not less than 30, preferably 30 to 40.

[0016] As a further improvement, the vacuum distillation includes a first-stage vacuum distillation and a second-stage vacuum distillation performed sequentially.

[0017] The above-described technical solution of the present invention has the following beneficial effects:

[0018] The purified ethanolamine reagents have the following characteristics: for monoethanolamine, the content of diethanolamine and triethanolamine is less than 17 ppm, and the content of sodium and potassium ions is less than 10 ppt; for diethanolamine, the content of monoethanolamine and triethanolamine is less than 25 ppm, and the content of sodium and potassium ions is less than 10 ppt. This method has a good separation and removal effect on homologous organic impurities and sodium and potassium ions in ethanolamine reagents (such as monoethanolamine and diethanolamine). Attached Figure Description

[0019] Figure 1 Process flow diagram for the purification of ethanolamine reagents.

[0020] It should be noted that the accompanying drawings in this application are schematic diagrams, and the specific connection methods are subject to the text description. Detailed Implementation

[0021] The following embodiments further illustrate the content of the present invention, but should not be construed as limiting the present invention. Any modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and essence of the invention are within the scope of the present invention.

[0022] Reagents:

[0023] Monoethanolamine (MEA): Chemical formula C2H7NO, molecular weight 61.083, boiling point 170.9℃, density 1.02 g / cm³ 3 It is a colorless, transparent, viscous liquid that turns into a white crystalline solid upon cooling. It has a faint ammonia odor, is strongly alkaline, hygroscopic, readily soluble in water and alcohols, and slightly soluble in benzene and ether. It is chemically reactive and can react with various acids to form esters, amides, and salts. Its structural formula is:

[0024]

[0025] Diethanolamine (DEA): also known as 2,2'-dihydroxydiethylamine, is an organic compound with the chemical formula C4H. 11 NO2 has a molecular weight of 105.136, a boiling point of 268.8℃, and a density of 1.097 g / cm³. 3 It is readily soluble in water and ethanol, but insoluble in ether and benzene. Its structural formula is:

[0026]

[0027] Terminology Explanation:

[0028] Raw materials: The ethanolamine reagent raw materials used in this application, such as monoethanolamine and diethanolamine, are all industrial grade and have a purity of not less than 85 wt%.

[0029] Ion exchange resins are high-molecular-weight polymers with a network structure, typically spherical particles composed of an insoluble resin matrix and active groups. They can achieve functions such as dehydration, catalysis, and decolorization through exchange reactions with ions in solution. Based on chemical properties, they are classified into four types: strongly acidic, weakly acidic, strongly basic, and weakly basic. Based on pore structure, they are classified into gel-type and macroporous types.

[0030] An ion exchange column is a cylindrical pressure vessel used for ion exchange reactions; it is the exchange equipment for tubular ion exchange. A cylindrical exchange column is used, with the solution introduced from one end of the column, making full contact with the dense, fixed ion exchange resin layer or the flowing ion exchange resin bed inside the column to carry out ion exchange.

[0031] Absolute pressure: refers to the pressure acting directly on the surface of a container or object, that is, the actual pressure exerted on the object. Its zero point is absolute vacuum, and its symbol is P. ABS .

[0032] Reboiler temperature: The reboiler is a device used for material separation in chemical equipment. It belongs to the lower head section of distillation columns and other similar structures, and together with the column body, it forms the separation system. Reboiler temperature specifically refers to the temperature of the reboiler section.

[0033] Reflux ratio: In distillation operations, the reflux liquid flow rate L returning from the top of the distillation column to the product flow rate D is called the reflux ratio R, where R = L / D. The magnitude of the reflux ratio has a significant impact on the separation efficiency and economy of the distillation process.

[0034] Operating pressure refers to the pressure maintained inside a system (such as a container, pipeline, reactor, ion exchange column, etc.) during normal and stable operation.

[0035] BV / h: Bed volume per hour, which is how many times the volume of liquid flowing through a fixed bed per hour is compared to its bed volume.

[0036] ppm: parts per million.

[0037] ppb: parts per billion, a few parts per billion, one thousandth of ppm. Used to express an extremely small concentration of a solute in a solution.

[0038] ppt: parts per trillion, a fraction of a trillion, which is one-thousandth of ppb. Used to express the concentration of an extremely small amount of solute in a solution.

[0039] Example 1

[0040] Purification was performed using industrial-grade monoethanolamine with a purity of 87 wt% as the raw material:

[0041] Precision microfiltration: The raw material is heated to 55°C and then enters a precision microfiltration device equipped with a 0.2μm polytetrafluoroethylene filter membrane module. After the temperature drops to 50°C, filtration is carried out under a pressure of 0.3MPa.

[0042] Preliminary purification: The material after precision microfiltration is passed sequentially through carboxyl polystyrene resin and amine polystyrene resin, with the temperature controlled at 30℃ and the flow rate at 3.5 BV / h.

[0043] Reduced pressure distillation: The ion-exchanged material enters a distillation unit with a packed column containing 30 theoretical plates. The distillation is carried out under the conditions of an absolute pressure of 6.0 kPa, a bottom temperature of 105℃, and a reflux ratio of 6:1 to accurately extract the main fraction.

[0044] Terminal nanofiltration: The main distillate fraction is fed into the polyamide nanofiltration membrane system at a pressure of 2.0 MPa by a high-pressure pump, and the operating temperature is controlled at 37°C. The permeate is collected.

[0045] Example 2

[0046] This embodiment uses industrial-grade monoethanolamine with a purity of 85 wt% as raw material. The preparation method is basically the same as that in Example 1, except that the process conditions for vacuum distillation and terminal nanofiltration are different. Specifically:

[0047] Reduced pressure distillation steps: theoretical plate number is 33, absolute pressure is 10 kPa, reboiler temperature is 120℃, and reflux ratio is 5:1;

[0048] Terminal nanofiltration step: temperature 40℃, operating pressure 2.5MPa.

[0049] Example 3

[0050] The preparation method is basically the same as that in Example 1, except that the process conditions for vacuum distillation are different, specifically:

[0051] The theoretical number of trays is 35, the absolute pressure is 4 kPa, the reboiler temperature is 90℃, and the reflux ratio is 10:1.

[0052] Example 4

[0053] The preparation method is basically the same as in Example 1, except that the process conditions for vacuum distillation and terminal nanofiltration are different, specifically:

[0054] Reduced pressure distillation steps: theoretical plate number is 37, absolute pressure is 1 kPa, reboiler temperature is 80℃, and reflux ratio is 15:1;

[0055] Terminal nanofiltration step: temperature 30℃, operating pressure 1.5MPa.

[0056] Example 5

[0057] Purification was performed using industrial-grade diethanolamine with a purity of 88 wt% as the raw material:

[0058] Precision microfiltration: The raw material is heated to 55°C and then enters a precision microfiltration device equipped with a 0.2μm polytetrafluoroethylene filter membrane module. After the raw material temperature drops to 51°C, filtration is carried out at 0.55MPa.

[0059] Preliminary purification: The microfiltered material is passed sequentially through carboxyl polystyrene resin and amine polystyrene resin, with the temperature controlled at 30℃ and the flow rate at 3 BV / h.

[0060] Reduced pressure distillation: After ion exchange, the material enters a distillation unit with a packed column containing 30 theoretical plates. The distillation is carried out under the conditions of absolute pressure of 2.0 kPa, bottom temperature of 97℃, and reflux ratio of 6:1 to accurately extract the main fraction.

[0061] Terminal nanofiltration: The main distillate fraction is fed into the polyamide nanofiltration membrane system at a pressure of 2.0 MPa by a high-pressure pump, and the operating temperature is controlled at 35°C. The permeate is collected.

[0062] Example 6

[0063] This embodiment uses industrial-grade diethanolamine with a purity of 85 wt% as raw material. The preparation method is basically the same as that in Example 5, except that the process conditions for vacuum distillation and terminal nanofiltration are different. Specifically:

[0064] Reduced pressure distillation steps: theoretical plate number is 35, absolute pressure is 3 kPa, reboiler temperature is 120℃, and reflux ratio is 5:1;

[0065] Terminal nanofiltration step: temperature 40℃, operating pressure 2.5MPa.

[0066] Example 7

[0067] The preparation method in this embodiment is basically the same as that in Example 5, except that the process conditions for vacuum distillation are different, specifically:

[0068] The theoretical number of trays is 35, the absolute pressure is 1 kPa, the reboiler temperature is 90℃, and the reflux ratio is 8:1.

[0069] Example 8

[0070] The preparation method in this embodiment is basically the same as that in Example 5, except that the process conditions for vacuum distillation and terminal nanofiltration are different. Specifically:

[0071] Reduced pressure distillation steps: theoretical plate number is 40, absolute pressure is 2 kPa, reboiler temperature is 110℃, and reflux ratio is 10:1;

[0072] Terminal nanofiltration step: temperature 30℃, operating pressure 1.5MPa.

[0073] Example 9

[0074] Purification was performed using industrial-grade monoethanolamine with a purity of 87 wt% as the raw material:

[0075] Precision microfiltration: The raw material is heated to 55°C and then enters a precision microfiltration device equipped with a 0.2μm polytetrafluoroethylene filter membrane module. After the raw material temperature drops to 50°C, filtration is carried out at 0.3MPa.

[0076] Preliminary purification: The material after fine microfiltration is sequentially passed through a strongly acidic cation exchange column (Dowex). TM Marathon C) and strong basic anion exchange column (Dowex) TMMarathon A), with temperature controlled at 30℃ and flow rate at 3.5 BV / h.

[0077] Reduced pressure distillation: The ion-exchange material enters a distillation unit with a packed column containing 33 theoretical plates. The distillation is carried out under the conditions of absolute pressure of 4.0 kPa, bottom temperature of 105℃, and reflux ratio of 6:1 to accurately extract the main fraction.

[0078] Terminal nanofiltration: The main distillate fraction is fed into the polyamide nanofiltration membrane system at a pressure of 2.0 MPa by a high-pressure pump, and the operating temperature is controlled at 37°C. The permeate is collected.

[0079] Example 10

[0080] This embodiment uses industrial-grade monoethanolamine with a purity of 85 wt% as raw material. The preparation method is basically the same as that in Example 9, except that the preliminary purification and terminal nanofiltration process conditions are different. Specifically:

[0081] Preliminary purification steps: operating temperature 40℃; flow rate 4 BV / h.

[0082] Terminal nanofiltration step: temperature 40℃, operating pressure 2.5MPa.

[0083] Example 11

[0084] This embodiment uses industrial-grade monoethanolamine with a high total metal ion content (including Na). + ≈500ppb,K + The raw material is approximately 300 ppb), and its preparation method is basically the same as that in Example 9, except that the preliminary purification process is different, specifically:

[0085] The permeate, after precise microfiltration, is passed sequentially through two strongly acidic cation exchange columns (Dowex). TM Marathon C), then sequentially passed through two strongly basic anion exchange columns (Dowex). TM Marathon A), operating temperature 35°C, flow rate 2 BV / h.

[0086] Example 12

[0087] The preparation method in this embodiment is basically the same as that in Example 11, except that the process conditions for preliminary purification and terminal nanofiltration are different, specifically:

[0088] Preliminary purification steps: operating temperature: 25℃, flow rate: 2.5 BV / h;

[0089] Terminal nanofiltration step: temperature 30℃, operating pressure 1.5MPa.

[0090] Example 13

[0091] In this embodiment, industrial-grade diethanolamine with a purity of 88 wt% was used as the raw material for purification:

[0092] Precision microfiltration: The raw material is heated to 55°C and then enters a precision microfiltration device equipped with a 0.2μm polytetrafluoroethylene filter membrane module, which operates at 0.55MPa and 51°C.

[0093] Preliminary purification: The material after fine microfiltration is sequentially passed through a strongly acidic cation exchange column (Dowex). TM Marathon C) and strong basic anion exchange column (Dowex) TM Marathon A), with temperature controlled at 30°C and flow rate at 3 BV / h.

[0094] Reduced pressure distillation: After ion exchange, the material enters a distillation unit with a packed column containing 33 theoretical plates. The distillation is carried out under the conditions of absolute pressure of 2.0 kPa, bottom temperature of 97℃, and reflux ratio of 5:1 to accurately extract the main fraction.

[0095] Terminal nanofiltration: The main distillate fraction is fed into the polyamide nanofiltration membrane system at a pressure of 2.0 MPa by a high-pressure pump, and the operating temperature is controlled at 35°C. The permeate is collected.

[0096] Example 14

[0097] This embodiment uses industrial-grade diethanolamine with a purity of 85 wt% as raw material. The preparation method is basically the same as that in Example 13, except that the preliminary purification and terminal nanofiltration process conditions are different. Specifically:

[0098] Preliminary purification steps: operating temperature 40℃, flow rate 4 BV / h;

[0099] Terminal nanofiltration step: temperature 40℃, operating pressure 2.5MPa.

[0100] Example 15

[0101] This embodiment uses industrial-grade diethanolamine with a high total metal ion content (including Na). + ≈500ppb,K + The raw material is approximately 300 ppb), and its preparation method is basically the same as that in Example 9, except that the preliminary purification process is different, specifically:

[0102] The permeate, after precise microfiltration, is passed sequentially through two strongly acidic cation exchange columns (Dowex). TM Marathon C), then sequentially passed through two strongly basic anion exchange columns (Dowex). TM Marathon A), operating temperature 35°C, flow rate 2 BV / h.

[0103] Example 16

[0104] The preparation method in this embodiment is basically the same as that in Example 15, except that the process conditions for preliminary purification and terminal nanofiltration are different, specifically:

[0105] Preliminary purification steps: operating temperature: 25℃, flow rate: 2.5 BV / h;

[0106] Terminal nanofiltration step: temperature 30℃, operating pressure 1.5MPa.

[0107] Compare with Example 1

[0108] No vacuum distillation is performed.

[0109] This comparative example repeats the preparation method of Example 1, but after the preliminary purification step, it does not perform vacuum distillation, but directly performs terminal nanofiltration.

[0110] Compare with Example 2

[0111] No terminal nanofiltration is performed.

[0112] This comparative example repeats the preparation method of Example 1, but does not perform terminal nanofiltration after vacuum distillation, and collects the permeate immediately after vacuum distillation.

[0113] Compare with Example 3

[0114] The theoretical plate number, absolute pressure, reboiler temperature, and reflux ratio of the vacuum distillation step are changed.

[0115] Repeat the steps of Example 1, but during vacuum distillation, the operating conditions are: 20 theoretical plates; 15 kPa absolute pressure; 70°C reboiler temperature; and 3:1 reflux ratio.

[0116] Compare with Example 4

[0117] The theoretical plate number, absolute pressure, reboiler temperature, and reflux ratio of the vacuum distillation step are changed.

[0118] Repeat the steps of Example 1, but during vacuum distillation, the operating conditions are: theoretical plate number of 20; absolute pressure of 20 kPa; reboiler temperature of 130°C; and reflux ratio of 2:1.

[0119] Compare with Example 5

[0120] No vacuum distillation is performed.

[0121] This comparative example uses the same preparation method as Example 5, but after the preliminary purification step, it does not perform vacuum distillation and directly performs terminal nanofiltration.

[0122] Compare with Example 6

[0123] No terminal nanofiltration is performed.

[0124] This comparative example repeats the preparation method of Example 5, but without performing terminal nanofiltration after vacuum distillation; the permeate is collected immediately after vacuum distillation.

[0125] Compare with Example 7

[0126] The theoretical plate number, absolute pressure, reboiler temperature, and reflux ratio of the vacuum distillation step are changed.

[0127] Repeat the steps of Example 5, but during vacuum distillation, the operating conditions are: 20 theoretical plates; 5 kPa absolute pressure; 120°C reboiler temperature; and 3:1 reflux ratio.

[0128] Compare with Example 8

[0129] The theoretical plate number, absolute pressure, reboiler temperature, and reflux ratio of the vacuum distillation step are changed.

[0130] Repeat the steps of Example 5, but during vacuum distillation, the operating conditions are: 20 theoretical plates; 3 kPa absolute pressure; 80°C reboiler temperature; and 2:1 reflux ratio.

[0131] Compare with Example 9

[0132] No preliminary purification is performed.

[0133] This comparative example repeats the preparation method of Example 9, but without preliminary purification after precision microfiltration, it directly undergoes vacuum distillation.

[0134] Compare with Example 10

[0135] No terminal nanofiltration is performed.

[0136] This comparative example repeats the preparation method of Example 9, but without performing terminal nanofiltration after vacuum distillation; the permeate is collected immediately after vacuum distillation.

[0137] Compare with Example 11

[0138] Change the operating temperature and flow rate of the initial purification step.

[0139] Repeat the steps of Example 9, but during the initial purification, the operating conditions are as follows:

[0140] The operating temperature is 50℃ and the flow rate is 5 BV / h.

[0141] Compare with Example 12

[0142] Change the operating temperature and flow rate of the initial purification step.

[0143] Repeat the steps of Example 9, but during the initial purification, the operating conditions are as follows:

[0144] The operating temperature is 20℃ and the flow rate is 6 BV / h.

[0145] Compare with Example 13

[0146] No preliminary purification is performed.

[0147] This comparative example repeats the preparation method of Example 13, but without preliminary purification after precision microfiltration, it directly undergoes vacuum distillation.

[0148] Compare with Example 14

[0149] No terminal nanofiltration is performed.

[0150] This comparative example repeats the preparation method of Example 13, but without performing terminal nanofiltration after vacuum distillation, and the permeate is collected immediately after vacuum distillation.

[0151] Compare with Example 15

[0152] Change the operating temperature and flow rate of the initial purification step.

[0153] Repeat the steps of Example 13, but during the initial purification, the operating conditions are as follows:

[0154] The operating temperature is 50℃ and the flow rate is 5 BV / h.

[0155] Compare with Example 16

[0156] Change the operating temperature and flow rate of the initial purification step.

[0157] Repeat the steps of Example 9, but during the initial purification, the operating conditions are as follows:

[0158] The operating temperature is 20℃ and the flow rate is 6 BV / h.

[0159] Experimental Example 1: Screening Test of Impurities in Homologues of Ethanolamine Reagents

[0160] Experimental objective: To detect homologue impurities in monoethanolamine and diethanolamine respectively, and to optimize the process conditions for removing organic homologue impurities.

[0161] Test method:

[0162] 1. The content of homologous organic impurities after purification in Examples 1-4 and Control Examples 1-4 was determined by gas chromatography-mass spectrometry (GC-MS).

[0163] 2. The content of homologous organic impurities after purification in Examples 5-8 and Control Examples 5-8 was determined by gas chromatography-mass spectrometry (GC-MS).

[0164] Table 1. Detection results of homologues of monoethanolamine after purification.

[0165]

[0166]

[0167] Note: The data shown in the table represents the range of multiple test results, expressed as the maximum value among the measured values.

[0168] Table 2. Results of impurity detection in homologues after diethanolamine purification.

[0169]

[0170] Note: The data shown in the table represents the range of multiple test results, expressed as the maximum value among the measured values.

[0171] Experimental conclusion:

[0172] As shown in Table 1, comparing Examples 1-4 with Control Examples 1-4, the distillation parameters (reflux ratio 5:1-15:1, theoretical plate number 30-37, temperature 80-120℃, absolute pressure 1.0-6.0 kPa) of Examples 1-4 resulted in lower levels of homologue impurities (diethanolamine and triethanolamine). Among these, Examples 3-4 showed better performance than Examples 1-2, indicating that the optimal distillation parameters are: reflux ratio 10:1-15:1; theoretical plate number 35-37; absolute pressure 1.0-4.0 kPa; and reboiler temperature 80-90℃.

[0173] As shown in Table 2, comparing Examples 5-8 with Control Examples 5-8, the distillation parameters used in Examples 5-8 (reflux ratio 5:1-10:1; theoretical plate number: 30-40; absolute pressure: 1.0-3.0 kPa; reboiler temperature: 90-120℃) resulted in lower levels of homologue impurities (monoethanolamine and triethanolamine). Examples 7-8 showed better performance than Examples 5-6, indicating that the optimal distillation parameters are: reflux ratio 8:1-10:1; theoretical plate number: 35-40; absolute pressure: 1.0-2.0 kPa; reboiler temperature: 90-110℃.

[0174] In summary, the operating conditions for removing homologous organic impurities using ethanolamine reagents (including monoethanolamine and diethanolamine) are: reflux ratio 5:1 to 15:1; theoretical plate number 30 to 40; absolute pressure 1.0 to 10.0 kPa; and reboiler temperature 90 to 120 °C.

[0175] Experimental Example 2: Screening Test for Monovalent Metal Impurities Using Ethanolamine Reagents

[0176] Experimental objective: To detect monovalent metal impurities (sodium and potassium ions) in monoethanolamine and diethanolamine respectively, and to optimize the process conditions for removing monovalent metal impurities (sodium and potassium ions).

[0177] Test method:

[0178] 1. The sodium and potassium ion contents of monoethanolamine after purification in Examples 3-4, Examples 9-12, and Control Examples 3-4 and Control Examples 9-12 were determined by inductively coupled plasma mass spectrometry (ICP-MS / MS).

[0179] 2. The sodium and potassium ion contents of diethanolamine after purification were determined by inductively coupled plasma mass spectrometry (ICP-MS / MS) in Examples 7-8, 13-16, and Control Examples 7-8 and 13-16, respectively.

[0180] Table 3. Detection results of sodium and potassium ions after purification of monoethanolamine.

[0181]

[0182] Note: The data shown in the table represents the range of results from multiple independent tests, expressed as the maximum or average value among the measured values.

[0183] Table 4. Detection results of sodium and potassium ions after purification of diethanolamine.

[0184]

[0185] Note: The data shown in the table represents the range of results from multiple independent tests, expressed as the maximum or average value among the measured values.

[0186] Experimental conclusion:

[0187] As shown in Table 3, the test results of sodium and potassium monoethanolamine ions indicate that, compared with Control Examples 3-4 and 9-12, the preliminary purification conditions (operating temperature 25-45℃, flow rate 2-4 BV / h) and nanofiltration conditions (temperature 30-45℃, operating pressure 1.5-2.5 MPa) of Examples 3-4 and 9-12 all meet the electronic grade standards for sodium and potassium ions and homologue impurities (diethanolamine and triethanolamine). Among them, Examples 11-12 are more effective than Examples 9-10, indicating that the optimal conditions for removing sodium and potassium ions are the combined use of two tandem cation exchange columns and two tandem anion exchange columns, with an operating temperature of 25-35℃ and a flow rate of 2-2.5 BV / h. Furthermore, comparing Examples 11-12 with Examples 3-4, it can be seen that although the latter has fewer homologue impurities (diethanolamine, triethanolamine) than the former, its sodium and potassium ion content is higher. This shows that if only vacuum distillation is used without preliminary purification, sodium and potassium ions cannot be effectively removed.

[0188] As shown in Table 4, the test results of sodium and potassium ions in diethanolamine indicate that, comparing Examples 7-8 and 13-16 with Control Examples 7-8 and 13-16, the preliminary purification conditions (operating temperature 25-45℃, flow rate 2-4 BV / h) and nanofiltration conditions (temperature 30-45℃, operating pressure 1.5-2.5 MPa) of Examples 7-8 and 13-16 all meet the electronic grade standard requirements for sodium and potassium ions and homologue impurities (monoethanolamine and triethanolamine). Among them, Examples 15-16 are more effective than Examples 13-14, indicating that the optimal conditions for removing sodium and potassium ions are the combined use of two tandem cation exchange columns and two tandem anion exchange columns, with an operating temperature of 25-35℃ and a flow rate of 2-2.5 BV / h. Furthermore, comparing Examples 13-14 with Examples 7-8, it can be seen that although the latter has fewer homologue impurities (monoethanolamine, triethanolamine) than the former, it has higher sodium and potassium ion content. This shows that preliminary purification and terminal nanofiltration can effectively remove sodium and potassium ions from the raw materials, and preliminary purification is the key step.

[0189] In summary, the process conditions for removing monovalent metal impurities (sodium and potassium ions) using ethanolamine reagents (including monoethanolamine and diethanolamine) are as follows: Preliminary purification step: operating temperature 25–45℃, flow rate 2–4 BV / h; Terminal nanofiltration step: operating temperature 30–45℃, operating pressure 1.5–2.5 MPa. When the sodium and potassium ion impurities in the raw material are high, purification can be achieved using two sets of tandem ion exchange columns: first, two tandem cation exchange columns, followed by two tandem anion exchange columns, thus more effectively removing sodium and potassium ions.

[0190] Experimental Example 3

[0191] Experimental objective: To detect the content of purified components and various impurities in Examples 9 and 13, respectively.

[0192] Test method:

[0193] 1. Monoethanolamine was used to perform a full analysis of Example 9.

[0194] 2. Diethanolamine was used to perform a full analysis of Example 13.

[0195] The results are shown in Tables 5 and 6:

[0196] Table 5. Full analysis results of Example 9

[0197]

[0198] Note: The data shown in the table represents the range of results from multiple independent tests, expressed as the maximum or average value among the measured values.

[0199] Table 6. Full analysis results of Example 13

[0200]

[0201]

[0202] Note: The data shown in the table represents the range of results from multiple independent tests, expressed as the maximum or average value among the measured values.

[0203] Results analysis: The ethanolamine reagents proposed in this application have high purity (main content > 99.99%), and the content of various impurities is controlled at a low level. Moreover, the preparation method of this application is universal and can be adapted to monoethanolamine and diethanolamine.

[0204] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing ultra-high purity electronic-grade ethanolamine reagents, characterized in that, The ethanolamine is monoethanolamine or diethanolamine, and the preparation method includes the following steps: The raw materials are initially purified using cation exchange resin and anion exchange resin; then vacuum distillation is performed, and finally, a polyamide composite nanofiltration membrane is used for terminal nanofiltration. The permeate is collected as the final product.

2. The preparation method according to claim 1, characterized in that, When the ethanolamine is monoethanolamine, the operating conditions for the vacuum distillation are: absolute pressure of 1.0–10.0 kPa; The temperature of the column bottom is 80-120℃; the reflux ratio is 5:1-15:

1.

3. The preparation method according to claim 1, characterized in that, When the ethanolamine is diethanolamine, the operating conditions for the vacuum distillation are: absolute pressure 1.0–3.0 kPa; bottom temperature 90–120 °C; reflux ratio 5:1–10:

1.

4. The preparation method according to claim 1, characterized in that, The preliminary purification operation conditions are: temperature 25-40℃; flow rate 2-4 BV / h.

5. The preparation method according to claim 1, characterized in that, The operating conditions for the terminal nanofiltration are: temperature of 30–45°C and operating pressure of 1.5–2.5 MPa.

6. The preparation method according to claim 1, characterized in that, Before the preliminary purification, the raw material is subjected to a precision microfiltration step. The precision microfiltration uses a polytetrafluoroethylene precision microfiltration membrane module with a pore size of 0.1 to 0.2 μm and is carried out under the conditions of operating pressure of 0.3 to 0.6 MPa and temperature of 50 to 65 °C.

7. The preparation method according to claim 1, characterized in that, The preliminary purification involves passing the raw material sequentially through one or more cation exchange resin columns connected in series, followed by one or more anion exchange resin columns connected in series.

8. The preparation method according to claim 1, characterized in that, The cation exchange resin can be one of carboxyl polystyrene resin and sulfonic acid polystyrene resin, preferably sulfonic acid polystyrene resin; the anion exchange resin can be one of primary amine polystyrene resin and quaternary ammonium polystyrene resin, preferably quaternary ammonium polystyrene resin.

9. The preparation method according to claim 1, characterized in that, The number of theoretical plates in the vacuum distillation is not less than 30, and preferably 30 to 40.

10. The preparation method according to claim 1, characterized in that, The vacuum distillation includes a first-stage vacuum distillation and a second-stage vacuum distillation performed sequentially.

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