Equipment and method for preparing electronic-grade salicylic acid solution

Abstract

The invention discloses equipment and a method for preparing an electronic-grade salicylic acid solution. The equipment comprises an acidification tank, an alkali tank, a micron filter, an anion filter, a cation adsorption column and a nano filter. The acidification tank is used for loading a salicylic acid solution and an acidic substance, and the alkali tank is used for loading an eluent. The method comprises the following steps: firstly, removing large impurities from a salicylic acid solution and acidic substances through a micron filter, then conveying the salicylic acid solution and acidic substances to an anion filter, adsorbing salicylic acid through anion adsorption resin to obtain phenol, removing the phenol, then introducing an eluent, washing off the salicylic acid solution, conveying the salicylic acid solution to a cation adsorption column to remove metal ions, and finally conveying the salicylic acid solution and the acidic substances to a nano filter to obtain the purified salicylic acid. And reducing the granularity of the salicylic acid solution to obtain the electronic-grade salicylic acid solution. The electronic-grade salicylic acid solution has the advantage of strong selective complexing ability to metals, and has a good wet etching effect in the integrated circuit manufacturing process.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of salicylic acid, and in particular to a device and a method for preparing an electronic-grade salicylic acid solution. Background Art

[0002] Salicylic acid, also known as o-hydroxybenzoic acid, is a widely used industrial product with important applications in medicine, fragrances, cosmetics, and dyes. Recently, salicylic acid and its derivatives have found new value in the integrated circuit field. Due to their selective metal complexing ability, they are often used in advanced wet etching processes. Advanced processes place high demands on the metal ion content and purity of the raw materials.

[0003] However, salicylic acid is currently purified using a sublimation process. A dedicated sublimation reactor is located at the bottom, where the salicylic acid feedstock is placed and heated until the salicylic acid reaches its boiling point. Atop the sublimation reactor is a condensation crystallization device, where salicylic acid vapor gathers and condenses into crystals. The purity of the salicylic acid in the sublimated crystals is higher than before sublimation. The boiling point of salicylic acid is 158-161°C. To achieve high-quality sublimation purification, a 165°C / 20 mmHg vacuum sublimation process is required. Such high temperatures inevitably increase energy consumption and, in fact, do not reduce the relative content of phenol. Due to the low boiling point of phenol and the color change caused by the conversion of the solution to quinones, the sublimated crystals will have a slight color, and the color may darken with each sublimation cycle. While the sublimation process improves purity, it does not reduce the content of metallic impurities in the product.

[0004] Therefore, there is an urgent need to design an apparatus and method for preparing an electronic-grade salicylic acid solution that can remove phenol and metal impurity ions in the generated salicylic acid. Summary of the Invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art and to propose an apparatus and method for preparing an electronic grade salicylic acid solution.

[0006] To achieve the above-mentioned object, the present invention adopts the following technical scheme: an apparatus for preparing an electronic-grade salicylic acid solution, comprising an acidification tank, an alkali tank, a micron filter and an anion filter, wherein the inlet of the micron filter is connected to the pipelines of the acidification tank and the alkali tank respectively, the outlet of the micron filter is connected to the inlet pipeline of the anion filter, the anion filter is provided with a first outlet and a second outlet, the first outlet is connected to a first check valve, the second outlet is sequentially connected to a cation adsorption column and a nanofilter, a first solenoid valve is provided on the pipeline between the cation adsorption column and the nanofilter, the outlet of the cation adsorption column is further provided with a bypass pipe, the outlet end of the bypass pipe is connected to the inlet of the cation adsorption column to form a circulation, and the bypass pipe is provided with a second solenoid valve and a second check valve.

[0007] Furthermore, the anion filter includes a heat-insulating layer and a plurality of anion adsorption columns arranged in the heat-insulating layer, wherein the anion adsorption columns are filled with anion adsorption resin, and the anion adsorption resin is composed of a quaternary ammonium salt with a polystyrene skeleton. The quaternary ammonium salt contains a strong base functional group -N + (CH3)3, under a specific acidic environment, can selectively adsorb salicylic acid, thereby achieving the purpose of separating salicylic acid solution from phenol, and further achieving the purpose of removing phenol.

[0008] Furthermore, the nanofilter includes a nanofiltration membrane, the pressure value of the nanofiltration membrane is 0.8-1.0 MPa, the pore size of the nanofiltration membrane is 0.5-1.5 nm, and the ultra-clean index of the purified environment is 100.

[0009] Furthermore, the acidification tank is provided with two inlets for the acidic solution and the salicylic acid solution to enter respectively.

[0010] A method for preparing an electronic-grade salicylic acid solution, characterized in that it comprises the following steps:

[0011] Step 1: Adjust the pH value of the solution: add an acidic substance to the salicylic acid solution generated by the chemical reaction and let it stand until the salicylic acid solution becomes acidic;

[0012] Step 2: Filter phenol: The salicylic acid solution of step 1 is sent to an anion adsorption column. The anion adsorption column includes an anion adsorption resin containing a quaternary ammonium salt. + Under the action of (CH3)3, salicylic acid solution and phenol are separated, salicylic acid is selectively adsorbed, and phenol is left behind. The phenol is removed, leaving the adsorbed salicylic acid solution.

[0013] Step 3: Filtering Metal Ions: The salicylic acid adsorbed in step 2 is eluted with an alkaline eluent and circulated into a cationic adsorption column to remove metal ions. When the metal ion content is lower than 0.1 ppb as detected by an instrument, the circulation is stopped and the solution is then sent to a nanofilter to reduce the particulate matter content in the salicylic acid solution to obtain an electronic grade salicylic acid solution.

[0014] Furthermore, in step 1, the acidic substance is dilute sulfuric acid, and the acid content of the salicylic acid solution after adding the dilute sulfuric acid is 0.2%-0.5%.

[0015] Furthermore, the eluent is an aqueous ammonia solution or a TMAH aqueous solution containing an alkali content greater than 0.1% (molar percentage).

[0016] Furthermore, the salicylic acid in step one needs to pass through a micron filter before entering step two to remove large impurities in the water and prevent it from flowing into the anion adsorption column and clogging the anion adsorption column.

[0017] Furthermore, the anion adsorption column is prepared by soaking the anion adsorption resin in distilled water for 24 hours, draining the water, soaking it in 1 mol / L sulfuric acid for 12 hours, washing it with distilled water until it is neutral, and then drying it.

[0018] Beneficial effects:

[0019] 1. The present invention adjusts a salicylic acid solution to be acidic, uses an anion adsorption column to adsorb the salicylic acid solution, extracts phenol mixed in the salicylic acid solution, removes it through a first outlet, and then washes the salicylic acid solution on the anion adsorption column with an eluent and sends it to the next process. This method has a high removal rate for phenol and will not decompose to produce new phenol.

[0020] 2. The present invention circulates the salicylic acid solution into a cation adsorption column, and the cation adsorption column adsorbs the metal ions in the salicylic acid solution, thereby reducing the metal ion content in the salicylic acid solution and meeting the production needs of the factory.

[0021] 3. The electronic-grade salicylic acid solution obtained by the present invention has the advantage of strong selective complexing ability for metals, and has a good wet etching effect in the integrated circuit manufacturing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of an apparatus for preparing electronic-grade salicylic acid solution proposed in the present invention;

[0023] Legend: 1. Acidification tank; 2. Alkali tank; 3. Micron filter; 40. Anion filter; 41. Anion adsorption column; 42. Insulation layer; 5. Cation adsorption column; 6. Nanofilter; 7. First solenoid valve; 8. Second solenoid valve; 9. Bypass pipe; 10. First check valve; 11. Second check valve. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0025] like Figure 1As shown, an apparatus for preparing an electronic-grade salicylic acid solution includes an acidification tank 1, an alkali tank 2, a micron filter 3, and an anion filter 40. The inlet of the micron filter 3 is connected to the pipelines of the acidification tank 1 and the alkali tank 2, respectively, and the outlet of the micron filter 3 is connected to the inlet pipeline of the anion filter 40. The anion filter 40 is provided with a first outlet and a second outlet. The first outlet is connected to a first check valve 10, and the second outlet is connected to a cation adsorption column 5 and a nanofilter 6 in sequence. A first solenoid valve 7 is provided on the pipeline between the cation adsorption column 5 and the nanofilter 6.

[0026] The outlet of the cation adsorption column 5 is further provided with a bypass pipe 9 , the outlet end of the bypass pipe 9 is connected to the inlet of the cation adsorption column to form a circulation, and the bypass pipe is provided with a second solenoid valve 8 and a check valve 11 .

[0027] In actual use, the bypass pipe is connected through two three-way valves, one of which is located between the anion filter 40 and the inlet of the cation adsorption column 5, and the other is located between the outlet of the cation adsorption column 5 and the inlet of the first solenoid valve 10. The two three-way valves are then connected to form a bypass pipe 9.

[0028] The anion filter 40 includes a heat-insulating layer 42 and a plurality of anion adsorption columns 41 disposed in the heat-insulating layer 42 . The anion adsorption columns 41 are filled with anion adsorption resin, which is composed of a quaternary ammonium salt with a polystyrene skeleton.

[0029] The reference principle is that salicylic acid reaches adsorption equilibrium at medium-strong acidity, and phenol reaches adsorption equilibrium at low acidity. Strong alkaline anion adsorption resin is a quaternary ammonium salt of polystyrene skeleton, and its strong base functional group is -N + (CH3)3. The principle of adsorption depends on the state of the substance; the highest adsorption capacity is achieved when the monovalent anionic form is present. Adjusting the acidity can achieve resin adsorption for salicylic acid that is far superior to phenol, resulting in high adsorption selectivity and facilitating the selective adsorption separation of salicylic acid and phenol. Static adsorption tests showed that the resin's adsorption of both salicylic acid and phenol conformed to the Freundlich isotherm.

[0030] The pretreatment of the strong base anion exchange resin is to soak it in distilled water for 24 hours, drain the water, soak it in 1 mol / L sulfuric acid for 12 hours, wash it with distilled water until it is neutral, dry it, and set it aside.

[0031] The nanofilter 6 comprises a nanofiltration membrane with a pressure rating of 0.8-1.0 MPa and a pore size of 0.5-1.5 nm, achieving a cleanliness rating of 100. The micron filter 3 comprises a microfiltration membrane with a pore size of 0.2-0.8 μm, made of high-density polyethylene. The acidification tank 1 has two inlets, one for the acidic solution and the other for the salicylic acid solution. The alkali tank is used to load the eluent.

[0032] A method for preparing an electronic-grade salicylic acid solution, characterized in that it comprises the following steps:

[0033] Step 1: Adjust the acidity of the solution: add an acidic substance to the salicylic acid solution generated by the chemical reaction and let it stand until the salicylic acid solution becomes acidic.

[0034] Step 2: Filter phenol: The salicylic acid solution of step 1 is sent to an anion adsorption column 41. The anion adsorption column includes an anion adsorption resin containing a quaternary ammonium salt. + Under the action of (CH3)3, salicylic acid is adsorbed, thereby separating salicylic acid from phenol, removing phenol and leaving the adsorbed salicylic acid solution;

[0035] Step 3: Filtering Metal Ions: The salicylic acid adsorbed in step 2 is eluted with an alkaline eluent and circulated into a cation adsorption column 5 to remove metal ions. When the metal ion content is lower than 0.1 ppb as detected by a metal ion instrument, the circulation is stopped and the salicylic acid solution is then sent to a nanofilter 6 to reduce the particulate matter content in the salicylic acid solution to obtain an electronic-grade salicylic acid solution.

[0036] The acidic substance is dilute sulfuric acid with an acid content of 0.2%-0.5%.

[0037] The eluent is ammonia water or TMAH aqueous solution containing an alkali molar percentage greater than 0.1%.

[0038] Before entering step 2, the salicylic acid in step 1 needs to pass through a micron filter 3 to remove large impurities in the water and prevent it from flowing into the anion adsorption column 41 and clogging the anion adsorption column 41.

[0039] Implementation Case 1

[0040] 200 L of a 30% salicylic acid-acetone solution was placed in an acidification tank 1, and dilute sulfuric acid was added to reduce the acid content of the salicylic acid solution to 0.3%. After standing for 30 minutes, the solution was passed to a micron filter 3 at a flow rate of 10 L / min to remove large impurities. The solution was then passed to several anion adsorption columns 41 for 60 minutes to remove phenol from the salicylic acid-acetone solution. Ammonia was then added to elute the salicylic acid-acetone solution from the anion adsorption columns. The solution was then circulated to a cation adsorption column 5 for 30 minutes to remove metal ions. Finally, the solution was passed to a nanofilter 6 to reduce the particulate matter content in the salicylic acid-acetone solution. A sample was taken from the product output pipe for analysis, and the solvent was removed by vacuum distillation. The component content was tested, and the phenol content in the product was 0.02 ppm, meeting the SEMIC8 standard. After treatment, a total of 177.8 L of a 32.25% salicylic acid-acetone solution was obtained, with a treatment yield of 95.56%.

[0041] Implementation Case 2

[0042] 20L of 20% salicylic acid ethanol solution was placed in an acidification tank 1 and diluted sulfuric acid was added to reduce the acid content of the salicylic acid solution to 0.3%. After standing for 30 minutes, the solution was passed through a micron filter 3 at a flow rate of 800ml / min to remove large impurities in the solution. The solution was then passed through several anion adsorption columns 41 and processed for 60 minutes to remove phenol from the salicylic acid ethanol solution. Ammonia was then added to elute the salicylic acid from the anion adsorption columns. The solution was then circulated into a cation adsorption column 5 with a cycle time of 30 minutes to remove metal ions. The solution was then passed through a nanofilter 6 to reduce the particulate matter content in the salicylic acid ethanol solution. Sampling was performed from the product output pipe for analysis. The solvent was removed by underpressure distillation. The component content was tested and the phenol content in the product was 0.001ppm. The test results met the SEMIC8 standard. After treatment, a total of 17.32L of 21.79% ethanol solution was obtained, with a treatment yield of 94.36%.

[0043] The effects of the above embodiments are compared in Table 1:

[0044] ITEM UNIT SPEC Example 1 Example 2 phenol ppm ≤5 0.002 0.001 <![CDATA[Free acid (calculated as H2SO4)]]> ppm ≤5 ＜2 ＜2 Chloride (C1) ppm ≤0.5 ＜0.5 ＜0.5 <![CDATA[Nitrate (NO3)]]> ppm ≤2 ＜2 ＜2 <![CDATA[Phosphate (PO4)]]> ppm ≤1 ＜1 ＜1 <![CDATA[Sulfate (SO4)]]> ppm ≤2 ＜2 ＜2 A1 ppb ≤20 0.20 0.09 Sb ppb ≤20 0.00 0.00 As ppb ≤20 0.05 0.07 Ba ppb ≤50 0.21 0.23 B ppb ≤20 0.04 0.03 Cd ppb ≤50 0 0 Ca ppb ≤100 2.5 2.0 Cr ppb ≤20 0.12 0.07 Cu ppb ≤20 0.01 0.01 Fe ppb ≤100 1.53 3.65 Pb ppb ≤20 0.52 0.13 Li ppb ≤20 0.00 0.00 Mg ppb ≤50 0.25 0.13 Mn ppb ≤20 0.01 0.03 Ni ppb ≤50 0.15 0.13 K ppb ≤100 3.65 4.53 Na ppb ≤100 7.56 12.66 Sn ppb ≤20 1.56 0.98 Ti ppb ≤20 0.45 0.53 Zn ppb ≤50 0.24 0.13 Particles (≥0.2μm) ea / ml ≤100 52 46

[0045] This shows that the metal ion content of the electronic-grade salicylic acid obtained by the present invention is far lower than that of existing products on the market. The method of the present invention first dissolves salicylic acid in a medium- to strong-polarity solvent such as ethanol or acetone to form a salicylic acid solution, and then removes the metal ions. The above-mentioned implementation case distilled the solvent from the salicylic acid solution to obtain experimental data. However, in actual production, the obtained salicylic acid solution does not require distillation to remove the solvent. The salicylic acid solution can be concentrated as needed or directly put into production.

[0046] The advantages of this production method are its safety and ease of operation. Although the entire constant temperature system utilizes electrical heating, the well-designed safety and automatic control system, alarm system, and backup power supply ensure safe and efficient operation of the entire adsorption and filtration process. Maintenance is also easy. Due to its small footprint, compact design, and high disassembly capabilities, maintenance and servicing are extremely convenient. Cleaning the heater, replacing the adsorption column assembly, or repairing the delivery pump can all be resolved quickly.

[0047] It should be noted that the terms "part", "other", "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way are interchangeable under appropriate circumstances, so that the embodiments of the present invention described herein can be implemented in orders other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or are inherent to these processes, methods, products or apparatus.

[0048] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or 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. An apparatus for preparing electronic grade salicylic acid solution, characterized in that: The invention comprises an acidification tank (1), an alkali tank (2), a micron filter (3) and an anion filter (40), wherein the inlet of the micron filter (3) is connected to the pipelines of the acidification tank (1) and the alkali tank (2), respectively, and the outlet of the micron filter (3) is connected to the inlet pipeline of the anion filter (40). The anion filter (40) is provided with a first outlet and a second outlet, wherein the first outlet is connected to a first check valve (10), and the second outlet is connected to a cation adsorption column (5) and a nano filter (6) in sequence. A first electromagnetic valve (7) is provided on the pipeline between the cation adsorption column (5) and the nano filter (6). A bypass pipe (9) is further provided at the outlet of the cation adsorption column (5), wherein the outlet end of the bypass pipe (9) is connected to the inlet of the cation adsorption column (5) to form a circulation, and a second electromagnetic valve (8) and a second check valve (11) are provided on the bypass pipe (9).

2. The device for preparing electronic grade salicylic acid solution according to claim 1, characterized in that: The anion filter (40) comprises a heat-insulating layer (42) and a plurality of anion adsorption columns (41) disposed in the heat-insulating layer (42). The anion adsorption columns (41) are filled with an anion adsorption resin, and the anion adsorption resin is composed of a quaternary ammonium salt with a polystyrene skeleton.

3. The device for preparing electronic grade salicylic acid solution according to claim 1, characterized in that: The nanofilter (6) includes a nanofiltration membrane, the pressure value of the nanofiltration membrane is 0.8-1.0 MPa, the pore size of the nanofiltration membrane is 0.5-1.5 nm, and the ultra-clean index of the purified environment is 100.

4. The device for preparing electronic grade salicylic acid solution according to claim 1, characterized in that: The acidification tank (1) is provided with two inlets for the entry of the acidic solution and the salicylic acid solution respectively.

5. A method for preparing an electronic grade salicylic acid solution, characterized in that: The steps include: Step 1: Adjust the pH value of the solution: add an acidic substance to the salicylic acid solution generated by the chemical reaction and let it stand until the salicylic acid solution becomes acidic; Step 2: Filter phenol: The salicylic acid solution of step 1 is sent to an anion adsorption column. The anion adsorption column includes an anion adsorption resin containing a quaternary ammonium salt. + Under the action of (CH3)3, salicylic acid solution and phenol are separated, salicylic acid is selectively adsorbed, and phenol is left behind. The phenol is removed, leaving the adsorbed salicylic acid solution. Step 3: Filtering Metal Ions: The salicylic acid adsorbed in step 2 is eluted with an alkaline eluent and circulated into a cationic adsorption column to remove metal ions. When the metal ion content is lower than 0.1 ppb by detection, the circulation is stopped and the solution is sent to a nanofilter to reduce the particulate matter content in the salicylic acid solution to obtain an electronic grade salicylic acid solution.

6. The method for preparing an electronic-grade salicylic acid solution according to claim 5, wherein: In the step 1, the acidic substance is dilute sulfuric acid, and the acid content of the salicylic acid solution after adding the dilute sulfuric acid is 0.2%-0.5%.

7. The method for preparing an electronic grade salicylic acid solution according to claim 5, wherein: The eluent is ammonia water or TMAH aqueous solution containing an alkali content greater than 0.1% (molar percentage).

8. The method for preparing an electronic-grade salicylic acid solution according to claim 5, wherein: Before entering step 2, the salicylic acid solution in step 1 needs to pass through a micron filter to remove large impurities in the water to prevent it from flowing into the anion adsorption column and clogging the anion adsorption column.

9. The method for preparing an electronic grade salicylic acid solution according to claim 5, wherein: The anion adsorption column is prepared by soaking the anion adsorption resin in distilled water for 24 hours, draining the water, soaking it in 1 mol / L sulfuric acid for 12 hours, washing it with distilled water until it is neutral, and then drying it.

Images