A method for adsorptive purification of nitrogen trifluoride gas

Abstract

The application discloses a method for adsorbing and purifying nitrogen trifluoride gas and relates to the technical field of nitrogen trifluoride adsorption and purification. The method comprises the following steps: uniformly mixing 3A molecular sieve, a modifier and anhydrous ethanol, and performing a temperature rising reaction to obtain an adsorbent; the adsorbent is filled into an adsorption device, activated under a nitrogen atmosphere, and then cooled to room temperature; crude nitrogen trifluoride is subjected to adsorption in the adsorption device filled with the adsorbent under the conditions that the temperature is-25-10 DEG C, the pressure is 0.1-0.5 MPa, and the flow rate is 0.25-0.70 m 3 / h, and nitrogen trifluoride from which HF is removed is obtained. The method can effectively reduce the acidity of HF, and the adsorbent used has excellent compressive strength.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nitrogen trifluoride adsorption purification, and particularly relates to a method for adsorbing and purifying nitrogen trifluoride gas. BACKGROUND

[0002] With the rapid development of the global semiconductor industry, especially the development of technologies such as 5G, artificial intelligence, and the Internet of Things, the demand for high-purity nitrogen trifluoride continues to grow. Nitrogen trifluoride is mainly used in the plasma etching and cleaning processes in semiconductor manufacturing to remove oxides and impurities on the surface of silicon wafers. The presence of HF in these processes can cause corrosion or other adverse reactions on the surface of the silicon wafer, affecting the quality and performance of the product. The acidity control of nitrogen trifluoride is not only related to the safety and effectiveness of the product, but also directly affects the yield of semiconductor products. Therefore, it is extremely important to reduce the HF acidity in nitrogen trifluoride and improve the quality of nitrogen trifluoride products. For the HF in nitrogen trifluoride, using adsorption to remove it is a simple and efficient way, so it is crucial to explore a method that can effectively adsorb and purify nitrogen trifluoride gas.

[0003] Chinese invention patent with publication number CN106276828A discloses a method for adsorbing and purifying nitrogen trifluoride. It uses 5A molecular sieve and tetradecyl phosphoric acid cerium as carrier raw materials, then loads zinc dialkyldithiophosphate and 3-fluoro-n-methyl aniline on the carrier by liquid phase deposition method to prepare an adsorbent. The crude nitrogen trifluoride is adsorbed in an adsorption column filled with the adsorbent. This method effectively improves the purity of nitrogen trifluoride gas, but still has deficiencies in reducing HF acidity. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a method for adsorbing and purifying nitrogen trifluoride gas.

[0005] To achieve the above-mentioned purpose, the present application realizes the following technical solutions:

[0006] A method for adsorbing and purifying nitrogen trifluoride gas, comprising the following steps:

[0007] (1) mixing 3A molecular sieve, a modifier, and anhydrous ethanol, and reacting under heating to obtain an adsorbent;

[0008] (2) filling the adsorbent in an adsorption device, activating under heating in a nitrogen atmosphere, and reducing to room temperature. The crude nitrogen trifluoride is adsorbed in the adsorption device filled with the adsorbent under the conditions of a temperature of -25-10℃, a pressure of 0.1-0.5 MPa, and a flow rate of 0.25-0.70 m 3 / h to obtain HF-removed nitrogen trifluoride;

[0009] The modifier is prepared by the following method:

[0010] S1: Oxidized bis(4-phenyl isocyanate) reacts with 3-chloropropylamine to generate intermediate 1, and the reaction equation is as follows:

[0011]

[0012] S2: (Pentafluorophenyl) methylamine reacts with 3-chloropropyl trimethoxysilane to generate intermediate 2, and the reaction equation is as follows:

[0013]

[0014] S3: Intermediate 1 reacts with intermediate 2 to generate a modifier, and the reaction equation is as follows:

[0015]

[0016] In step S1, the molar ratio of the oxidized bis(4-phenyl isocyanate) to 3-chloropropylamine is 1:(2.05-2.1).

[0017] In step S2, the molar ratio of the (pentafluorophenyl) methylamine to 3-chloropropyl trimethoxysilane is 1:(1.05-1.1).

[0018] In step S3, the molar ratio of the intermediate 1 to the intermediate 2 is 1:(2.01-2.05).

[0019] The reaction solvent of step S1 is anhydrous DMF; the reaction solvent of step S2 is anhydrous acetonitrile; and the reaction solvent of step S3 is anhydrous acetonitrile.

[0020] In step (1), the mass ratio of the 3A molecular sieve, the modifier, and anhydrous ethanol is (1-2):(0.15-0.3):(5-10).

[0021] In step (1), the reaction temperature is 70-80℃.

[0022] In step (1), the reaction time is 16-18h.

[0023] In step (2), the activation temperature is 100-110℃.

[0024] In step (2), the activation time is 3-4h.

[0025] By adopting the above technical solutions, the present application has the following beneficial effects:

[0026] The method provided by the application can effectively reduce the acidity of HF, and the adsorbent used has excellent compressive strength. The added modifier improves the compressive performance of the adsorbent through anchoring and providing rigid support; and the hydrogen bond effect of the urea group and the strong electron-withdrawing effect of the fluorine atom in the pentafluorobenzyl structure cooperatively reduce the acidity of the nitrogen trifluoride gas. BRIEF DESCRIPTION OF DRAWINGS

[0027] The application will be further described below in combination with the drawings.

[0028] Figure 1 It is a structural diagram of the adsorption device. DETAILED DESCRIPTION

[0029] The application will be further described below in combination with the drawings.

[0030] Example 1: Preparation of a modifier

[0031] S1: Under nitrogen protection, 200ml of anhydrous DMF and 0.1mol of bis(4-phenyl isocyanate) oxide were sequentially added into a reactor, stirred and uniformly mixed, 0.205mol of 3-chloropropylamine was added in batches under ice bath (5 batches, 10min interval), the temperature was raised to 50℃, 0.1g of dibutyl tin dilaurate was added, the reaction was carried out for 6h, and the mixture was cooled to room temperature, then the mixture was added into 500ml of cold n-hexane to stir and precipitate, filtered, the filter cake was washed with cold n-hexane (3x150ml), and vacuum drying was carried out at 60℃ for 12h to obtain intermediate 1; the nuclear magnetic hydrogen spectrum data is as follows: 1 H NMR (400 MHz, Chloroform- d ) δ 7.56 (s, 2H), 7.46-7.38 (m,4H), 6.97-6.89 (m, 4H), 6.14 (d, J = 0.5 Hz, 2H), 3.73 (q, J = 12.4 Hz, 4H),3.23 (d, J = 0.5 Hz, 4H), 1.93 (s, 4H);

[0032] S2: 200ml of anhydrous acetonitrile, 0.1mol of (pentafluorophenyl) methylamine and 0.105mol of 3-chloropropyl trimethoxysilane were uniformly mixed, 0.1mol of N,N-diisopropyl ethylamine was added, the reaction was carried out at 50℃ for 6h, and the mixture was cooled to room temperature, filtered, concentrated at 50℃ under reduced pressure for 2h, the residue was redissolved in 150ml of anhydrous acetonitrile, slowly added dropwise into 300ml of cold n-hexane to stir and precipitate, filtered, the filter cake was washed with cold n-hexane (3x100ml), and vacuum drying was carried out at 50℃ for 12h to obtain intermediate 2; the nuclear magnetic hydrogen spectrum data is as follows: 1HNMR (400 MHz, Chloroform- d ) δ 3.92 (d, J = 0.6 Hz, 2H), 3.57 (s, 9H), 2.89-2.74 (m, 2H), 2.71 (t, J = 0.5 Hz, 1H), 1.77-1.60 (m, 2H), 1.07 (s, 2H);

[0033] S3: Mix 500 ml anhydrous acetonitrile, 0.1 mol intermediate 1, 0.201 mol intermediate 2, add 0.1 mol N,N-diisopropyl ethylamine, react at 55°C for 8h, cool to room temperature, filter, concentrate at 50°C under reduced pressure for 2h, dissolve the residue in 250 ml anhydrous acetonitrile, slowly drop into 750 ml cold n-hexane to stir to precipitate, filter, wash the filter cake with cold n-hexane (3x200 ml), dry at 50°C under vacuum for 12h to obtain the modifier; its nuclear magnetic resonance hydrogen spectrum data are as follows: 1 H NMR (400 MHz, Chloroform- d ) δ 7.56 (s, 2H), 7.46-7.38 (m, 4H), 6.97-6.89 (m, 4H), 6.01 (d, J = 0.5 Hz, 2H), 3.79 (s, 4H), 3.57 (s, 18H), 3.19 (d, J = 0.5 Hz, 4H), 2.70 (s, 4H), 2.51 (s, 4H), 1.82-1.54 (m, 8H), 1.06-0.93 (m, 4H).

[0034] Example 2 Preparation of modifier:

[0035] S1: Under nitrogen protection, add 200 ml anhydrous DMF, 0.1 mol bis(4-phenyl isocyanate) oxide into the reactor in turn, stir and mix uniformly, add 0.208 mol 3-chloropropylamine in batches (5 batches in total, interval 10 min), warm up to 50°C, add 0.1 g dibutyl tin dilaurate, react for 5h, cool to room temperature, add the mixture into 500 ml cold n-hexane to stir to precipitate, filter, wash the filter cake with cold n-hexane (3x150 ml), dry at 60°C under vacuum for 12h to obtain intermediate 1;

[0036] S2: 200 ml of anhydrous acetonitrile, 0.1 mol of (pentafluorophenyl) methylamine, 0.108 mol of 3-chloropropyltrimethoxysilane were mixed, 0.1 mol of N,N-diisopropylethylamine was added, and the mixture was reacted at 50°C for 5 h. After cooling to room temperature, the mixture was filtered, concentrated under reduced pressure at 50°C for 2 h, and the residue was dissolved again in 150 ml of anhydrous acetonitrile. The solution was slowly added dropwise to 300 ml of cold n-hexane with stirring to precipitate the product. The precipitate was filtered, the filter cake was washed with cold n-hexane (3 x 100 ml), and the product was dried under vacuum at 50°C for 12 h to obtain intermediate 2.

[0037] S3: 500 ml of anhydrous acetonitrile, 0.1 mol of intermediate 1, and 0.203 mol of intermediate 2 were mixed, 0.1 mol of N,N-diisopropylethylamine was added, and the mixture was reacted at 55°C for 7 h. After cooling to room temperature, the mixture was filtered, concentrated under reduced pressure at 50°C for 2 h, and the residue was dissolved again in 250 ml of anhydrous acetonitrile. The solution was slowly added dropwise to 750 ml of cold n-hexane with stirring to precipitate the product. The precipitate was filtered, the filter cake was washed with cold n-hexane (3 x 200 ml), and the product was dried under vacuum at 50°C for 12 h to obtain the modifier.

[0038] Example 3: Preparation of the modifier

[0039] S1: 200 ml of anhydrous DMF, and 0.1 mol of bis(4-phenyl isocyanate) oxide were sequentially added to a reactor under nitrogen protection, and the mixture was stirred and mixed. Under ice bath, 0.21 mol of 3-chloropropylamine was added in batches (5 batches, with an interval of 10 min between each batch), and the temperature was increased to 55°C. 0.1 g of dibutyltin dilaurate was added, and the mixture was reacted at 55°C for 4 h. After cooling to room temperature, the mixture was added to 500 ml of cold n-hexane with stirring to precipitate the product. The precipitate was filtered, the filter cake was washed with cold n-hexane (3 x 150 ml), and the product was dried under vacuum at 60°C for 12 h to obtain intermediate 1.

[0040] S2: 200 ml of anhydrous acetonitrile, 0.1 mol of (pentafluorophenyl) methylamine, 0.11 mol of 3-chloropropyltrimethoxysilane were mixed, 0.1 mol of N,N-diisopropylethylamine was added, and the mixture was reacted at 55°C for 4 h. After cooling to room temperature, the mixture was filtered, concentrated under reduced pressure at 50°C for 2 h, and the residue was dissolved again in 150 ml of anhydrous acetonitrile. The solution was slowly added dropwise to 300 ml of cold n-hexane with stirring to precipitate the product. The precipitate was filtered, the filter cake was washed with cold n-hexane (3 x 150 ml), and the product was dried under vacuum at 60°C for 12 h to obtain intermediate 2.

[0041] S3: Mix 500 ml of anhydrous acetonitrile, 0.1 mol of intermediate 1, and 0.205 mol of intermediate 2, add 0.1 mol of N,N-diisopropyl ethylamine, react at 60°C for 6 h, cool to room temperature, filter, concentrate at 50°C under reduced pressure for 2 h, dissolve the residue in 250 ml of anhydrous acetonitrile, slowly add to 750 ml of cold n-hexane under stirring to precipitate, filter, wash the filter cake with cold n-hexane (3 x 200 ml), and dry at 50°C under vacuum for 12 h to obtain the modifier.

[0042] Example 4: Method for adsorptive purification of nitrogen trifluoride gas:

[0043] (1) Mix 500 g of 3A molecular sieve, 75 g of the modifier (prepared in Example 1), and 2500 g of anhydrous ethanol, heat to 70°C for 18 h, cool to room temperature naturally, filter, wash successively with 2500 ml of anhydrous ethanol and 2500 ml of ether, and dry at 60°C under vacuum for 12 h to obtain the adsorbent;

[0044] (2) Fill 325 g of the adsorbent into an adsorption device, activate at 100°C under nitrogen atmosphere for 4 h, cool to room temperature, and adsorb the crude nitrogen trifluoride gas under the conditions of a temperature of -25°C, a pressure of 0.1 MPa, and a flow rate of 0.25 m 3 / h to obtain HF-removed nitrogen trifluoride.

[0045] Example 5: Method for adsorptive purification of nitrogen trifluoride gas:

[0046] (1) Mix 750 g of 3A molecular sieve, 100 g of the modifier (prepared in Example 2), and 4000 g of anhydrous ethanol, heat to 75°C for 17 h, cool to room temperature naturally, filter, wash successively with 2500 ml of anhydrous ethanol and 2500 ml of ether, and dry at 60°C under vacuum for 12 h to obtain the adsorbent;

[0047] (2) Fill 325 g of the adsorbent into an adsorption device, activate at 105°C under nitrogen atmosphere for 3.5 h, cool to room temperature, and adsorb the crude nitrogen trifluoride gas under the conditions of a temperature of -5°C, a pressure of 0.3 MPa, and a flow rate of 0.45 m 3 / h to obtain HF-removed nitrogen trifluoride.

[0048] Example 6: Method for adsorptive purification of nitrogen trifluoride gas:

[0049] (1) Mix 1000g of 3A molecular sieve, 150g of modifier (prepared in Example 3) and 5000g of anhydrous ethanol, heat to 80℃ and react for 16h, cool naturally to room temperature, filter, wash with 2500ml of anhydrous ethanol and 2500ml of diethyl ether in sequence, and vacuum dry at 60℃ for 12h to obtain the adsorbent.

[0050] (2) 325g of adsorbent was packed into the adsorption device, and activated at 110℃ for 3 hours under a nitrogen atmosphere. After cooling to room temperature, the crude nitrogen trifluoride was passed through the adsorption device containing the adsorbent at a temperature of 10℃, a pressure of 0.5MPa, and a flow rate of 0.70m³. 3 Adsorption was carried out under conditions of / h to obtain nitrogen trifluoride with HF removed.

[0051] Comparative Example 1

[0052] The method for adsorbing and purifying nitrogen trifluoride gas is basically the same as in Example 5, except that the modifier is replaced with an equal weight of a modifier prepared by the following method:

[0053] The preparation method of the modifier is basically the same as that in Example 2, except that the bis(4-phenyl isocyanate) oxide in step S1 is replaced with an equimolar amount of 4,4-diisocyanate dicyclohexylmethane.

[0054] Comparative Example 2

[0055] The method for adsorbing and purifying nitrogen trifluoride gas is basically the same as in Example 5, except that the modifier is replaced with an equal weight of a modifier prepared by the following method:

[0056] The preparation method of the modifier is basically the same as that in Example 2, except that bis(4-phenyl isocyanate) oxide in step S1 is replaced with an equimolar amount of 4,4'-methylenebis(phenyl isocyanate).

[0057] Comparative Example 3

[0058] The method for adsorbing and purifying nitrogen trifluoride gas is basically the same as in Example 5, except that the modifier is replaced with an equal weight of a modifier prepared by the following method:

[0059] The preparation method of the modifier is basically the same as that in Example 2, except that the (pentafluorophenyl)methylamine in step S2 is replaced with an equimolar amount of 2,4,6-trifluoroaniline.

[0060] Comparative Example 4

[0061] The method for adsorbing and purifying nitrogen trifluoride gas is basically the same as in Example 5, except that the modifier is replaced with an equal weight of a modifier prepared by the following method:

[0062] The preparation method of the modifier is basically the same as that in Embodiment 2, except that the (pentafluorophenyl)methylamine in step S2 is replaced with an equimolar amount of 2,3,5,6-tetrafluoroaniline.

[0063] The 3A molecular sieve used in the examples and comparative examples of the present application has a model number of JZ-ZMS3, a diameter of 2 mm, and is produced by Shanghai Jiuzhou Chemical Co., Ltd.; the adsorption device is modified from a DN65 stainless steel pipeline, has a height of 14 cm, and is connected to a DN25 stainless steel pipeline at both ends after being reduced to DN25 (see Figure 1 ).

[0064] The adsorbents used in Examples 4-6 and Comparative Examples 1-4 were subjected to compressive strength tests, and the HF acidity of the nitrogen trifluoride gas before and after adsorption was tested, and the results are shown in Table 1.

[0065] Compressive strength test: The compressive strength of the adsorbent particles used in Examples 4-6 and Comparative Examples 1-4 was measured using a precision pressure testing machine. The adsorbent particles (2 mm in diameter) were placed on the loading platform of the pressure testing machine, and the pressure plate was controlled to slowly descend and extrude the adsorbent particles until they were crushed. The maximum pressure F max The compressive strength was calculated according to the following formula based on the display of the sensor:

[0066]

[0067] wherein R is the compressive strength, MPa; F max is the maximum pressure, N; d is the particle size, mm, and the compressive strength is obtained by repeating the test 15 times and taking the average value.

[0068] HF acidity test: The HF acidity of the nitrogen trifluoride gas before and after purification in Examples 4-6 and Comparative Examples 1-4 was tested according to the standard T / CCGA 30003-2019, Appendix B, Method for Determining Acidity.

[0069] Table 1

[0070]

[0071] As can be seen from Table 1, the method for adsorbing and purifying nitrogen trifluoride gas in Examples 4-6 of the present application can effectively reduce the HF acidity, and the adsorbents used have excellent compressive properties.

[0072] The method provided by the present application 4-6 can effectively reduce the acidity of HF, and the adsorbent used has excellent compression resistance, mainly because the added modifier has siloxane, benzene ring, urea group and pentafluorobenzyl structure. Among them, the siloxane in the modifier can form a covalent bond with the silicon hydroxyl group on the surface of the 3A molecular sieve, firmly anchoring the modifier on the molecular sieve, and at the same time the benzene ring provides rigid support for the molecule, synergistically improving the compression resistance of the adsorbent; the urea group in the modifier acts as a strong hydrogen bond donor, which can capture HF molecules through hydrogen bond interaction, and under the action of hydrogen bond, HF molecules will dissociate into fluoride ions; the pentafluorobenzyl structure contains multiple fluorine atoms, and the strong electron-withdrawing effect of the fluorine atoms makes the carbon on the aromatic ring present a partial positive charge, which can form a carbon-fluorine bond with the dissociated fluoride ions, further capturing HF molecules, and synergistically reducing the acidity of HF in the nitrogen trifluoride gas. The modifier used in Comparative Example 3 and Comparative Example 4 replaces (pentafluorophenyl) methylamine with 2,4,6-trifluoroaniline and 2,3,5,6-tetrafluoroaniline, respectively, reducing the number of fluorine atoms on the benzene ring and weakening the strong electron-withdrawing effect, resulting in the inability to effectively capture HF molecules, making the HF acidity reduction effect worse than the embodiments.

[0073] The above is only the preferred embodiment of the present application and is not used to limit the present application; but for ordinary skilled in the art without departing from the scope of the present application technical solutions, can use the above disclosed technical content and make some changes, modifications and equivalent changes of evolution, are equivalent embodiments of the present application; at the same time, any equivalent changes, modifications and evolution of the above embodiments according to the essential technology of the present application, all still belong to the protection scope of the technical solutions of the present application.

Claims

1. A method of adsorptive purification of nitrogen trifluoride gas, characterized by, The method comprises the following steps: (1) mixing 3A molecular sieve, modifier and anhydrous ethanol, and reacting at elevated temperature to obtain an adsorbent; (2) The adsorbent is filled into the adsorption device, activated by heating under nitrogen atmosphere, and cooled to room temperature. The crude nitrogen trifluoride is adsorbed by the adsorption device filled with the adsorbent under the conditions of temperature of -25-10℃, pressure of 0.1-0.5 MPa, and flow rate of 0.25-0.70 m 3 / h, to obtain the nitrogen trifluoride from which HF is removed. (3) The nitrogen trifluoride obtained in step (2) is cooled to -30-0℃, and then the pressure is reduced to 0.01-0.05 MPa, to obtain the product. The modifier is prepared by the following method: S1: oxidized bis(4-phenyl isocyanate) reacts with 3-chloropropylamine to form intermediate 1, and its chemical structural formula is as follows: S2: (pentafluorophenyl)methanamine is reacted with 3-chloropropyltrimethoxysilane to form intermediate 2, which has the chemical structure as follows: S3: intermediate 1 reacts with intermediate 2 to form a modifier, which has the chemical structure as follows: 。 2. The method of claim 1, wherein the method further comprises, In step S1, the molar ratio of the oxidized bis(4-phenyl isocyanate) to 3-chloropropylamine is 1:(2.05-2.1).

3. The method of claim 1, wherein the method further comprises, In step S2, the molar ratio of the (pentafluorophenyl) methylamine to 3-chloropropyltrimethoxysilane is 1:(1.05-1.1).

4. The method of claim 1, wherein the method further comprises, In step S3, the molar ratio of the intermediate 1 to intermediate 2 is 1:(2.01-2.05).

5. The method of claim 1, wherein the method further comprises, The reaction solvent of step S1 is anhydrous DMF; the reaction solvent of step S2 is anhydrous acetonitrile; and the reaction solvent of step S3 is anhydrous acetonitrile.

6. The method of claim 1, wherein the method further comprises, In step (1), the mass ratio of the 3A molecular sieve, the modifier and the anhydrous ethanol is (1-2):(0.15-0.3):(5-10).

7. The method of claim 1, wherein the method further comprises, In step (1), the reaction temperature is 70-80℃.

8. The method of claim 1, wherein the method further comprises, In step (1), the reaction time is 16-18h.

9. The method of claim 1, wherein the method further comprises, In step (2), the activation temperature is 100-110℃.

10. The method of claim 1, wherein the method further comprises, In step (2), the activation time is 3-4h.

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