An inner and outer surface modified molecular sieve, a preparation method and application thereof

Abstract

The application discloses an inner and outer surface modified molecular sieve and a preparation method and application thereof, and the preparation method of the inner and outer surface modified molecular sieve is as follows: in an organic solvent I, bulk molecular sieve is reacted with a titanate surface modifier under a vacuum state to obtain an outer surface modified molecular sieve; and in an organic solvent II, the outer surface modified molecular sieve is reacted with an inner surface modifier under microwave radiation to obtain the inner and outer surface modified molecular sieve. After the bulk molecular sieve is modified on the inner and outer surfaces in the application, the surface polarity force is increased, and effective adsorption of fluorochlorobutene impurities is realized. The hexafluorobutyne product with a purity greater than 99.999% is prepared through a secondary adsorption and rectification best combined purification process, and the process is simple, the production cost is low, the purification efficiency is high, and the process is suitable for large-scale industrial continuous production.

Description

Technical Field

[0001] This invention relates to the field of fluorochemicals, and in particular to a molecular sieve with modified inner and outer surfaces, its preparation method, and its application in the purification of hexafluorobutyne. Background Technology

[0002] Hexafluorobutyne is an important fluorine-containing compound used as an intermediate or precursor in the preparation of a series of fluorine-containing pharmaceutical and pesticide intermediates in fine fluorine chemicals. Simultaneously, as an isomer of hexafluoro-1,3-butadiene, hexafluorobutyne can be used as an electronic gas for chip etching, exhibiting high selectivity and high aspect ratio in plasma etching. According to literature reports, due to its efficient etching performance, hexafluorobutyne can replace the classic etching gas C3F8 in etching silicon dioxide with comparable performance, reducing PFC emissions by 88.2%, while hexafluoro-1,3-butadiene only reduces emissions by 80%. Hexafluorobutyne has an atmospheric lifetime of 22 days, an ODP of 0, and a GWP of approximately 0. Therefore, hexafluorobutyne can serve as a new generation of green and environmentally friendly fluorine-containing electronic gas.

[0003] The most mature preparation process for hexafluorobutyne currently involves reacting hexachlorobutadiene with a fluorinating agent in a solvent to obtain hexafluorobutyne. The crude hexafluorobutyne obtained by this method contains impurities such as oxygen, nitrogen, hydrogen chloride, hydrogen fluoride, chlorofluorobutadiene (with more than two chlorine atoms), hexachlorobutadiene, octafluoro-2-butene, E-2-chloroheptafluoro-2-butene, Z-2-chloroheptafluoro-2-butene, E-2,3-dichlorohexafluoro-2-butene, and Z-2,3-dichlorohexafluoro-2-butene. These impurities must be purified to achieve a good etching effect. However, the removal of chlorofluorobutene impurities is difficult and significantly affects the purity of hexafluorobutyne. There is limited literature on the purification of hexafluorobutyne; distillation and adsorption techniques are mainly used to remove inorganic impurities. Currently, no adsorbent can effectively remove chlorofluorobutene organic impurities from hexafluorobutyne.

[0004] For removing organic impurities, adsorption is considered the most ideal purification method due to its low cost and simple operation; the key lies in the selection of the adsorbent. Below are some reports on the removal of organic impurities using adsorbents:

[0005] Patent CN114618429A discloses a surface-modified ZSM-5 molecular sieve and its application in removing azeotropic organic impurities from octafluorocyclobutane. ZSM-5 molecular sieves with a silica-to-alumina ratio of 25–100 are added to a non-polar organic solvent, along with a surface modifier. After reaction, the mixture is dried and calcined to obtain the surface-modified ZSM-5 molecular sieve. The surface modifier is methyl orthosilicate and / or silicon tetrachloride. By adjusting the pore size of the surface channels of the surface-modified ZSM-5 molecular sieve, its application in removing azeotropic organic impurities from different products can be achieved.

[0006] Patent CN105327676A discloses a modified adsorbent and its application in the preparation of ultrapure hexafluoroethane. The adsorbent is modified by ion exchange, ball milling, or impregnation methods. The adsorbent is selected from type A molecular sieves, type X molecular sieves, type Y molecular sieves, SiO2, Al2O3, or activated carbon AC. The modified adsorbent is suitable for removing organic impurities from crude hexafluoroethane, yielding ultrapure hexafluoroethane products with a purity ≥99.999%.

[0007] In summary, due to the difficulty in removing chlorofluorobutene impurities from hexafluorobutyne, there is currently no electronic-grade hexafluorobutyne product with a purity greater than 99.999% that can be applied to the etching process in chip manufacturing. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a method for preparing internally and externally surface-modified molecular sieves and their application in the purification of hexafluorobutyne. The internally and externally surface-modified molecular sieves can remove fluorochlorobutene-like organic impurities from hexafluorobutyne. The hexafluorobutyne purification method employs a combination of adsorption and distillation techniques to remove impurities from hexafluorobutyne, obtaining a hexafluorobutyne product with a purity of over 99.999%.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] This invention provides a method for preparing molecular sieves with modified inner and outer surfaces, wherein the molecular sieves with modified inner and outer surfaces are prepared by the following method:

[0011] S1: In organic solvent I, the bulk molecular sieve reacts with a titanate surface modifier under vacuum, and after washing and drying, an outer surface modified molecular sieve is obtained.

[0012] S2: The outer surface modified molecular sieve and the inner surface modifier are stirred and reacted under microwave radiation in organic solvent II, and then washed and dried to obtain the inner and outer surface modified molecular sieve.

[0013] The bulk molecular screening in step S1 is performed using FAU molecular sieves and / or MFI molecular sieves. The FAU molecular sieves are selected from NaX molecular sieves and / or NaY molecular sieves; the MFI molecular sieves are selected from at least one of ZSM-5 molecular sieves, TS-1 molecular sieves, and silicalite-1 molecular sieves.

[0014] In industrial-grade hexafluorobutyne feedstock, chlorofluorobutadiene, hexachlorobutadiene, octafluoro-2-butene, and other fluorochlorobutene-like organic impurities have molecular dynamic diameters ranging from 0.5 to 0.8 nm. Selecting molecular sieves with uniform pore structures, such as FAU or MFI sieves, whose main pores are between 0.5 and 0.8 nm, can significantly increase the diffusion resistance of fluorine-containing organic impurities, confining them within the pores of the molecular sieve. These impurities are then adsorbed into the pores due to electrostatic forces on the pore surfaces. Simultaneously, since hexafluorobutyne is a nonpolar molecule while fluorine-containing organic impurities are polar molecules, modifying the types and structures of functional groups on the inner and outer surfaces of the molecular sieve increases the polar forces exerted by the sieve on the organic impurities, thereby achieving effective separation of the organic impurities.

[0015] When fluorinated organic impurity molecules diffuse on the surface of a molecular sieve, they first come into contact with the surface modified by titanate-based surface modifiers. Since the diameter of the titanate coupling agent molecules is 1–2 nm, which is larger than the diameter of the main pores in the molecular sieve, they react with the silanol groups at the pore openings, grafting functionalized titanate surface modifier groups. The charge of the fluorinated organic impurity molecules is attracted by the strong electrostatic potential energy of the modified molecular sieve surface and is adsorbed. The silanol groups on the outer surface of the molecular sieve are passivated, and the added inner surface modifier enters the pores and reacts with the silanol groups on the inner surface of the pores in the bulk molecular sieve, increasing the polar functional groups such as carboxyl and amino groups on the inner surface. Some of the escaped fluorinated organic impurity molecules enter the molecular sieve pores, further increasing the polar forces on the inner surface, thus adsorbing the impurity molecules within the pores due to the strong forces formed between them and the inner surface of the pores. Through the modification of the molecular sieve with both inner and outer surfaces, deep removal of fluorinated organic impurities is ultimately achieved.

[0016] Organic solvent I and organic solvent II are each selected from at least one of toluene, cyclohexane, ethanol, acetonitrile, xylene, and ethyl acetate. Preferably, organic solvent I and organic solvent II are each selected from at least one of toluene, cyclohexane, and ethanol.

[0017] In step S1, the mass ratio of the bulk molecular sieve to organic solvent I is 1:5 to 1:50. Preferably, the mass ratio of the bulk molecular sieve to organic solvent I is 1:5 to 1:20.

[0018] The titanate surface modifier mentioned in step S1 is selected from at least one of isopropyl tris(isostearoyl) titanate, isopropyl tris(dioctylpyrophosphoryl) titanate, and di(dioctylpyrophosphoryl)oxyacetate.

[0019] In step S1, the concentration of the titanate surface modifier in organic solvent I is 0.1–5.0 mol / L. Preferably, the concentration of the titanate surface modifier in organic solvent I is 0.1–3.0 mol / L.

[0020] The vacuum level mentioned in step S1 is 10. -5 ~10 -3 The reaction is carried out under vacuum at a temperature of 20–150°C for a time of 10–48 hours. Preferably, the vacuum level is 10 Pa. -5 ~10 -4 Pa, under vacuum, reacts at temperatures of 20–110°C for 10–24 hours.

[0021] Under vacuum conditions, the boiling point of titanate surface modifiers is effectively reduced, and the evaporation of titanate surface modifier liquid is promoted, thereby driving the surface modification reaction of molecular sieves and improving the reaction efficiency. At the same time, the closed vacuum conditions help to improve the accuracy of grafting functional groups onto the surface of molecular sieves, resulting in high-quality surface-modified molecular sieves.

[0022] In step S2, the mass ratio of the externally modified molecular sieve to organic solvent II is 1:5 to 1:50. Preferably, the mass ratio of the externally modified molecular sieve to organic solvent II is 1:5 to 1:20.

[0023] The internal surface modifier in step S2 is selected from carboxylic acid compounds and / or amine compounds, wherein the carboxylic acid compound is selected from at least one of acetic acid, oxalic acid, and acetic acid; and the amine compound is selected from at least one of triethylamine, ethylenediamine, and xyleneamine.

[0024] In step S2, the concentration of the internal surface modifier in organic solvent II is 0.1–2.0 mol / L. Preferably, the concentration of the internal surface modifier in organic solvent II is 0.1–1.0 mol / L.

[0025] The microwave radiation power in step S2 is 300–1500 W. Preferably, the microwave radiation power is 300–1000 W.

[0026] The reaction temperature in step S2 is 20–200°C, and the reaction time is 2–24 h. Preferably, the reaction temperature is 20–150°C, and the reaction time is 2–12 h. More preferably, the reaction temperature is 20–100°C, and the reaction time is 2–10 h.

[0027] When heated by microwave radiation, microwave energy is directly transferred to the molecular sieve, efficiently converting energy into heat, thereby significantly increasing the rate of molecular sieve modification by internal surface modifiers. Microwave radiation heating can achieve more precise temperature control, improve the selectivity and specificity of hydroxylation reaction on the inner surface of the molecular sieve, thereby reducing the occurrence of side reactions and increasing the yield of modified molecular sieves.

[0028] In the preparation method of the modified molecular sieve, the drying temperature is 50–250°C, and the drying atmosphere is selected from at least one of air, oxygen, and nitrogen. Preferably, the drying temperature is 100–150°C, and the calcination atmosphere is selected from air and / or nitrogen.

[0029] The present invention also provides a molecular sieve with modified inner and outer surfaces prepared by the preparation method described above.

[0030] This invention also provides an application of the aforementioned inner and outer surface modified molecular sieve in the purification of hexafluorobutyne, wherein the purification method includes:

[0031] Industrial-grade hexafluorobutyne feedstock is subjected to primary adsorption by the aforementioned inner and outer surface modified molecular sieve, secondary adsorption by composite metal compounds, and distillation to obtain electronic-grade hexafluorobutyne.

[0032] The purity of the industrial-grade hexafluorobutyne raw material described in this invention is 90-99.9%. The industrial-grade hexafluorobutyne raw material contains impurities, including at least one selected from oxygen, nitrogen, carbon dioxide, carbon monoxide, water, hydrogen chloride, hydrogen fluoride, chlorofluorobutadiene, hexachlorobutadiene, octafluoro-2-butene, E-2-chloroheptafluoro-2-butene, Z-2-chloroheptafluoro-2-butene, E-2,3-dichlorohexafluoro-2-butene, and Z-2,3-dichlorohexafluoro-2-butene.

[0033] The inner and outer surface modified molecular sieve removes organic impurities from industrial-grade hexafluorobutyne raw materials. The organic impurities are chlorofluorobutene impurities, which include at least one selected from chlorofluorobutadiene, hexachlorobutadiene, octafluoro-2-butene, E-2-chloroheptafluoro-2-butene, Z-2-chloroheptafluoro-2-butene, E-2,3-dichlorohexafluoro-2-butene, and Z-2,3-dichlorohexafluoro-2-butene.

[0034] The primary adsorption method described in this invention is gas-solid phase adsorption.

[0035] During the primary adsorption process of the modified molecular sieve on the inner and outer surfaces, the flow rate of industrial-grade hexafluorobutyne feedstock is 1–100 L / h, the adsorption temperature is 20–80 °C, and the adsorption pressure is 0.01–0.2 MPa; preferably, the flow rate of industrial-grade hexafluorobutyne feedstock is 1–50 L / h, the adsorption temperature is 20–60 °C, and the adsorption pressure is 0.01–0.1 MPa.

[0036] The secondary adsorption method described in this invention is liquid-solid adsorption.

[0037] The composite metal compound includes metal fluoride and metal oxide, and the mass ratio of metal fluoride to metal oxide is 1:100 to 50:100; preferably, the mass ratio of metal fluoride to metal oxide is 1:100 to 30:100.

[0038] In the secondary adsorption process of the composite metal compound, the flow rate of the crude hexafluorobutyne after primary adsorption is 1-50 L / h, the adsorption temperature is -60 to -20℃, and the adsorption pressure is 0.01-0.1 MPa; preferably, the feed flow rate of the crude hexafluorobutyne after primary adsorption is 1-20 L / h, the adsorption temperature is -40 to -20℃, and the adsorption pressure is 0.01-0.05 MPa.

[0039] The preparation method of the composite metal compound is as follows: at 30-90℃, metal fluoride is dissolved in water, metal oxide is added, and after stirring for 5-24 hours, it is dried at 50-250℃ and calcined at 200-800℃ to obtain the composite metal compound.

[0040] The metal fluoride is selected from at least one of NaF, KF, and CaF2; the metal oxide is selected from at least one of SiO2, Al2O3, and CaO.

[0041] Preferably, the composite metal compound is prepared by dissolving a metal fluoride in water at 30–80°C, adding a metal oxide, stirring for 5–12 hours, drying at 100–180°C, and calcining at 200–500°C.

[0042] Composite metal compounds prepared by loading metal fluorides onto metal oxides utilize the large specific surface area and porosity of the metal oxides to achieve effective adsorption of hydrogen fluoride and water molecules. At the same time, the metal fluorides distributed on the surface and in the pores of the metal oxides further reduce the content of hydrogen fluoride and water molecules through chemical reactions or their own physical properties, thereby achieving deep removal.

[0043] During the distillation process, the distillation temperature is 20–100℃ and the distillation pressure is 0.2–0.8 MPa; preferably, the distillation temperature is 20–80℃ and the distillation pressure is 0.2–0.6 MPa.

[0044] Distillation is mainly used to remove inorganic impurities such as oxygen, nitrogen, carbon dioxide, and carbon monoxide. Hexafluorobutyne has a boiling point of -25℃, which is significantly different from the boiling points of all inorganic impurities. The effective separation of inorganic impurities can be achieved by adjusting the temperature of the distillation column.

[0045] This invention combines adsorption and distillation. Through two-stage adsorption, organic impurities such as chlorofluorobutadiene, hexachlorobutadiene, and octafluoro-2-butene, as well as water and hydrogen fluoride impurities, are removed from hexafluorobutyne. Distillation removes inorganic impurities such as oxygen, nitrogen, carbon dioxide, and carbon monoxide. The final product is an electronic-grade hexafluorobutyne with a purity of 99.999%, containing less than 5 ppm of organic impurities, less than 2 ppm of moisture, less than 2 ppm of hydrogen fluoride, less than 2 ppm of oxygen, less than 5 ppm of nitrogen, less than 1 ppm of carbon dioxide, and less than 1 ppm of carbon monoxide.

[0046] Compared with the prior art, the beneficial effects of the present invention include:

[0047] 1. This invention improves the surface physical adsorption force of molecular sieves by performing multiple modifications on the inner and outer surfaces, thereby increasing the polar interaction force between the molecular sieves and impurity molecules, and ultimately achieving deep removal of organic impurities from hexafluorobutyne.

[0048] 2. Purification of hexafluorobutyne using molecular sieves with modified inner and outer surfaces is characterized by mild adsorption conditions, low requirements for adsorption equipment, and low cost, making it suitable for industrial applications.

[0049] 3. This invention removes impurities from hexafluorobutyne through an optimal combination of adsorption and distillation purification process, obtaining hexafluorobutyne products with a purity of over 99.999%. The process is simple, has low production costs, and high purification efficiency, making it suitable for large-scale continuous industrial production. Detailed Implementation

[0050] The present invention will be further described below with reference to specific embodiments, but the invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all alternatives, improvements and equivalents that may be included within the scope of the claims.

[0051] The industrial-grade hexafluorobutyne feedstock used in the following examples has the following composition: Table 1 below:

[0052] Table 1 Purity and Impurity Composition of Industrial Grade Hexafluorobutyne Raw Material

[0053]

[0054]

[0055] The measurement or calculation method used in this invention specifically includes:

[0056] (1) Total impurity content

[0057] The total impurity content is calculated as follows:

[0058] Φ8=Φ1+Φ2+Φ3+Φ4+Φ5+Φ6+Φ7, in the formula:

[0059] Φ1: Oxygen content / ppm

[0060] Φ2: Nitrogen content / ppm

[0061] Φ3: Carbon dioxide content / ppm

[0062] Φ4: Carbon monoxide content / ppm

[0063] Φ5: Organic impurities content / ppm

[0064] Φ6: Water content / ppm

[0065] Φ7: Acidity / ppm

[0066] Φ8: Total impurities content / ppm

[0067] (2) Purity of hexafluorobutyne

[0068] The purity of hexafluorobutyne is calculated as follows:

[0069] Φ = 100 - Φ8 * 10 4 In the formula, Φ represents the purity or mass fraction of hexafluorobutyne / 10. -2

[0070] (3) Determination of organic impurity content:

[0071] The area normalization method of FID gas chromatography was used to determine the organic impurity content of hexafluorobutyne. The chromatographic column was a capillary column with a length of about 60m, an inner diameter of 0.32mm, and an inner coating of bonded silica gel.

[0072] Methods for calculating the saturated adsorption capacity of an adsorbent:

[0073]

[0074] S: Saturated adsorption capacity of impurities, ml / g; Q: Gas flow rate through the reaction tube, g / h;

[0075] C0: Concentration of impurities in the feed gas, mg / kg; C t : Concentration of impurities in the gas after adsorption, mg / kg;

[0076] t: saturation adsorption time, h; M: relative molecular mass of impurities in the feed gas, g / mol;

[0077] Vm: Molar volume under standard conditions, L / mol; m: Mass of adsorbent, g;

[0078] (4) Determination of inorganic impurity content:

[0079] Helium-ion gas chromatography was used to determine the inorganic impurities in hexafluorobutyne. Column I consisted of a 2m long, 2mm inner diameter stainless steel tube packed with 5A molecular sieve particles of 0.18mm-0.25mm. This column was used to determine oxygen and nitrogen content. Column II consisted of a 4m long, 2mm inner diameter stainless steel tube packed with Hayesep Q (a polymer) particles of 0.18mm-0.25mm. This column was used to determine carbon dioxide and carbon monoxide content.

[0080] (5) Moisture content determination:

[0081] The moisture content of hexafluorobutyne was determined using a piezoelectric moisture analyzer. First, the sampling system was purged with high-purity nitrogen until the moisture content was less than 0.1 ppm. Then, the hexafluorobutyne sample gas was passed through the sampling system and the piezoelectric moisture analyzer until the reading of the piezoelectric moisture analyzer stabilized. This value is the moisture content of hexafluorobutyne.

[0082] (6) Acidity content determination:

[0083] The acidity content of hexafluorobutyne was determined by chemical titration. The sample was vaporized and then bubbled into a porous gas washing bottle filled with water to absorb the acidic substances in the sample. Bromocresol green was used as an indicator, and finally, the acidity was calculated by titration with a standard sodium hydroxide solution.

[0084] Preparation Example 1

[0085] Step S1: Mix NaX molecular sieve and toluene at a mass ratio of 1:10, then add isopropyl tris(isostearoyl) titanate to achieve a concentration of 1 mol / L in toluene. -3 After reacting at 20°C for 24 hours, the surface-modified molecular sieve was prepared by washing and drying at 120°C under a nitrogen atmosphere.

[0086] Step S2: Mix the outer surface modified molecular sieve with toluene at a mass ratio of 1:10, then add the inner surface modifier acetic acid to make the concentration of acetic acid in toluene 0.2 mol / L. React under microwave radiation with a power of 500W for 5 hours. Finally, after washing and drying at 120℃ under a nitrogen atmosphere, the molecular sieve with modified inner and outer surfaces is obtained and is designated as No. 1 modified molecular sieve.

[0087] Preparation Example 2

[0088] The procedure for preparation example 2 is the same as that for preparation example 1, except that the modified molecular sieve used is prepared from NaY molecular sieve. All other procedures remain the same, and a molecular sieve with modified inner and outer surfaces is obtained, which is designated as modified molecular sieve #2.

[0089] Preparation Example 3

[0090] The procedure for Preparation Example 3 is the same as that for Preparation Example 1, except that the modified molecular sieve used is prepared using ZSM-5 molecular sieve. All other procedures remain the same, and a molecular sieve with modified inner and outer surfaces is obtained, which is designated as Modified Molecular Sieve #3.

[0091] Preparation Example 4

[0092] The procedure for preparation example 4 is the same as that for preparation example 1, except that the modified molecular sieve used is prepared using TS-1 molecular sieve. All other procedures remain the same, and a molecular sieve with modified inner and outer surfaces is obtained, which is designated as 4# modified molecular sieve.

[0093] Preparation Example 5

[0094] The procedure for Preparation Example 5 is the same as that for Preparation Example 1, except that the modified molecular sieve used is prepared by using ethanol as organic solvent I and organic solvent II. Other procedures remain unchanged, and a molecular sieve with modified inner and outer surfaces is obtained, which is designated as 5# modified molecular sieve.

[0095] Preparation Example 6

[0096] The procedure for Preparation Example 6 is the same as that for Preparation Example 1, except that the mass ratio of the bulk molecular sieve to toluene in the modified molecular sieve is 1:5, and the mass ratio of the outer surface modified molecular sieve to toluene is 1:5. Other procedures remain unchanged, and a molecular sieve modified with both inner and outer surfaces is obtained, which is designated as Modified Molecular Sieve No. 6.

[0097] Preparation Example 7

[0098] The procedure for Preparation Example 7 is the same as that for Preparation Example 1, except that the mass ratio of the bulk molecular sieve to toluene in the modified molecular sieve is 1:20, and the mass ratio of the outer surface modified molecular sieve to toluene is 1:20. Other procedures remain unchanged, and a molecular sieve modified with both inner and outer surfaces is obtained, which is designated as Modified Molecular Sieve #7.

[0099] Preparation Example 8

[0100] The procedure for Preparation Example 8 is the same as that for Preparation Example 1, except that the modified molecular sieve used is prepared by isopropyl tris(dioctylpyrophosphoryl) titanate surface modifier. Other procedures remain unchanged, and a molecular sieve with modified inner and outer surfaces is obtained, which is designated as 8# modified molecular sieve.

[0101] Preparation Example 9

[0102] The preparation of Example 9 was performed in the same manner as that of Example 1, except that the modified molecular sieve used was prepared by using di(dioctylpyrophosphoryl)oxyacetate as a surface modifier. Other operations remained unchanged, and a molecular sieve with modified inner and outer surfaces was obtained, which was designated as 9# modified molecular sieve.

[0103] Preparation Example 10

[0104] Preparation Example 10 was performed in the same manner as Preparation Example 1, except that the concentration of the titanate modifier in toluene was 1 mol / L. All other operations remained unchanged. This yielded a molecular sieve with modified inner and outer surfaces, which was designated as 10# modified molecular sieve.

[0105] Preparation Example 11

[0106] Preparation Example 11 was performed in the same manner as Preparation Example 1, except that the modified molecular sieve used was prepared under a vacuum of 10... -5 Prepared under Pa conditions, with other operations remaining unchanged, a molecular sieve with modified inner and outer surfaces was obtained, denoted as 11# modified molecular sieve.

[0107] Preparation Example 12

[0108] The procedure for Preparation Example 12 is the same as that for Preparation Example 1, except that the modified molecular sieve used is prepared by oxalic acid as an internal surface modifier. Other procedures remain unchanged, and a molecular sieve modified with both internal and external surfaces is obtained, which is designated as 12# modified molecular sieve.

[0109] Preparation Example 13

[0110] The procedure for Preparation Example 13 is the same as that for Preparation Example 1, except that the modified molecular sieve used is prepared by using triethylamine as an internal surface modifier. All other procedures remain the same, and a molecular sieve modified with both internal and external surfaces is obtained, which is designated as 13# modified molecular sieve.

[0111] Preparation Example 14

[0112] The procedure for Preparation Example 14 is the same as that for Preparation Example 1, except that the modified molecular sieve used is prepared by using ethylenediamine as an internal surface modifier. All other procedures remain the same, and a molecular sieve modified with both internal and external surfaces is obtained, which is designated as 14# modified molecular sieve.

[0113] Preparation Example 15

[0114] The procedure for Preparation Example 15 was the same as that for Preparation Example 1, except that the concentration of the internal surface modifier acetic acid in toluene was 0.5 mol / L. All other procedures remained unchanged, and a molecular sieve modified with both internal and external surfaces was obtained, which was designated as 15# modified molecular sieve.

[0115] Preparation Example 16

[0116] The procedure for Preparation Example 16 is the same as that for Preparation Example 1, except that the modified molecular sieve used was prepared under a radiation power of 1000W. All other procedures remain the same, and a molecular sieve with modified inner and outer surfaces is obtained, which is designated as 16# modified molecular sieve.

[0117] Comparative Example 1

[0118] The operation of Comparative Example 1 is the same as that of Preparation Example 1, except that the modified molecular sieve used is prepared under normal pressure. Other operations remain unchanged, and a molecular sieve with modified inner and outer surfaces is obtained, which is denoted as 17# modified molecular sieve.

[0119] Comparative Example 2

[0120] The operation of Comparative Example 2 is the same as that of Preparation Example 1, except that the modified molecular sieve used is prepared under conditions without microwave radiation. Other operations remain unchanged, and a molecular sieve with modified inner and outer surfaces is obtained, which is denoted as 18# modified molecular sieve.

[0121] Example 1

[0122] 1) A primary adsorption purification operation was carried out. Industrial-grade hexafluorobutyne raw material was introduced into an adsorption tower filled with the modified molecular sieve No. 1 prepared in Preparation Example 1 at a gas phase flow rate of 10 L / h. The adsorption temperature was 20℃ and the adsorption pressure was 0.01 MPa.

[0123] 2) Conduct a two-stage adsorption purification operation. The crude hexafluorobutyne purified by the first-stage adsorption is continuously fed into the adsorption tower filled with composite metal compounds at a liquid flow rate of 5 L / h for adsorption. The adsorption temperature is -40℃ and the adsorption pressure is 0.01 MPa.

[0124] The preparation method of the composite metal compound is as follows: CaF2 is dissolved in water at 30℃, and then Al2O3 is added, wherein the mass ratio of CaF2 to Al2O3 is 10:100. After stirring for 10 hours, the composite metal compound is prepared by drying at 100℃ and calcining at 300℃.

[0125] 3) Finally, carry out the distillation purification operation. The crude hexafluorobutyne product after secondary adsorption is further distilled at a temperature of 20°C and a pressure of 0.2 MPa.

[0126] The adsorption depth and saturated adsorption capacity for chlorofluorobutylene impurities of the No. 1 modified molecular sieve were obtained using the above measurement and calculation methods, as shown in Table 1.

[0127] The modified molecular sieves 2# and 18# prepared in Preparation Examples 2-16 and Comparative Examples 1-2, respectively, were used as adsorbents for adsorption. Other operations were the same as in Example 1. The adsorption depth and saturated adsorption capacity for fluorochloroprene impurities of the modified molecular sieves 2# and 18# were obtained, as shown in Table 1 below.

[0128] Table 1. Adsorption performance of modified molecular sieves #1 to #18

[0129]

[0130]

[0131] As can be seen from Table 1, the molecular sieve modified with internal and external surface modifiers described in this invention can effectively remove chlorofluorocarbon impurities from hexafluorobutyne. The content of chlorofluorocarbon impurities after adsorption is less than 1 ppm, and the adsorption capacity is large.

[0132] Comparative Example 3

[0133] The operation of Comparative Example 3 is the same as that of Example 1, except that NaY molecular sieve is used as the adsorption material for adsorption, and other operations remain unchanged.

[0134] Using the above measurement and calculation methods, the adsorption depth of NaY molecular sieve and its saturated adsorption capacity for chlorofluorobutylene impurities were obtained, as shown in Table 2.

[0135] Comparative Example 4

[0136] The operation of Comparative Example 4 is the same as that of Example 1, except that ZSM-5 molecular sieve is used as the adsorption material for adsorption, and other operations remain unchanged.

[0137] The adsorption depth and saturated adsorption capacity of ZSM-5 molecular sieve for chlorofluorobutylene impurities were obtained using the above measurement and calculation methods, as shown in Table 2.

[0138] Comparative Example 5

[0139] The operation of Comparative Example 5 is the same as that of Example 1, except that TS-1 molecular sieve is used as the adsorption material for adsorption, and other operations remain unchanged.

[0140] The adsorption depth and saturated adsorption capacity of TS-1 molecular sieve for chlorofluorobutylene impurities were obtained using the above measurement and calculation methods, as shown in Table 2.

[0141] Comparative Example 6

[0142] The operation of Comparative Example 6 is the same as that of Example 1, except that NaX molecular sieves modified with isopropyl tris(isostearoyl) titanate surface modifier in one step are used as adsorption materials for adsorption, and other operations remain unchanged.

[0143] Using the above-mentioned measurement and calculation methods, the adsorption depth and saturated adsorption capacity for chlorofluorobutylene impurities of NaX molecular sieve modified with isopropyl tris(isostearoyl) titanate surface modifier were obtained, as shown in Table 2.

[0144] Comparative Example 7

[0145] The operation of Comparative Example 7 is the same as that of Example 1, except that NaX molecular sieves modified with acetic acid as an internal surface modifier are used as adsorbents for adsorption, and other operations remain unchanged.

[0146] Using the above measurement and calculation methods, the adsorption depth and saturated adsorption capacity for chlorofluorobutylene impurities of the molecular sieve modified with the internal surface modifier acetic acid were obtained, as shown in Table 2.

[0147] Table 2 Adsorption properties of Comparative Examples 3–7

[0148] Comparative Example Adsorption depth / ppm Saturated adsorption capacity / mL / g 3 ≤34 5.8 4 ≤65 3.6 5 ≤45 4.9 6 ≤1 10.9 7 ≤1 12.1

[0149] As can be seen from Table 2, the adsorption depth or adsorption capacity of molecular sieves such as NaY, ZSM-5, and TS-1 without modification of internal and external surface modifiers is difficult to meet the requirements of industrial applications for chlorofluorocarbon impurities. Although molecular sieves modified with titanate esters / internal surface modifiers can also effectively remove chlorofluorocarbon impurities and have a large adsorption depth, their adsorption capacity is small and does not meet the requirements of industrial applications.

[0150] Example 2

[0151] The operation of Example 2 is the same as that of Example 1, except that the gas flow rate of industrial-grade hexafluorobutyne feedstock in the first-stage adsorption purification operation is 20 L / h, and other operations remain unchanged.

[0152] The adsorption depth of each type of impurity was obtained using the aforementioned testing and calculation methods, and the specific results are shown in Table 3.

[0153] Example 3

[0154] The operation of Example 3 is the same as that of Example 1, except that the gas flow rate of industrial-grade hexafluorobutyne feedstock in the first-stage adsorption purification operation is 40 L / h, and other operations remain unchanged.

[0155] The adsorption depth of each type of impurity was obtained using the aforementioned testing and calculation methods, and the specific results are shown in Table 3.

[0156] Example 4

[0157] The operation of Example 4 is the same as that of Example 1, except that the adsorption temperature in the first-stage adsorption purification operation is 40°C, and the other operations remain unchanged.

[0158] The adsorption depth of each type of impurity was obtained using the aforementioned testing and calculation methods, and the specific results are shown in Table 3.

[0159] Example 5

[0160] The operation of Example 5 is the same as that of Example 1, except that the adsorption temperature in the first-stage adsorption purification operation is 60°C, while the other operations remain unchanged.

[0161] The adsorption depth of each type of impurity was obtained using the aforementioned testing and calculation methods, and the specific results are shown in Table 3.

[0162] Example 6

[0163] The operation of Example 6 is the same as that of Example 1, except that the adsorption pressure in the first-stage adsorption purification operation is 0.05 MPa, and the other operations remain unchanged.

[0164] The adsorption depth of each type of impurity was obtained using the aforementioned testing and calculation methods, and the specific results are shown in Table 3.

[0165] Example 7

[0166] The operation of Example 7 is the same as that of Example 1, except that the adsorption pressure in the first-stage adsorption purification operation is 0.1 MPa, and the other operations remain unchanged.

[0167] The adsorption depth of each type of impurity was obtained using the aforementioned testing and calculation methods, and the specific results are shown in Table 3.

[0168] Table 3 Adsorption depth of Examples 1-7

[0169]

[0170] As shown in Table 3, the purification method for electronic-grade hexafluorobutyne described in this invention can effectively remove inorganic, organic, moisture, hydrogen fluoride, and other impurities from hexafluorobutyne, and the purity of the purified hexafluorobutyne product is greater than 99.999%. However, excessive feed flow rate, adsorption temperature, and adsorption pressure during the first-stage adsorption process can affect the adsorption depth of organic impurities, thereby affecting the purity of the hexafluorobutyne product.

[0171] Example 8

[0172] The operation of Example 8 is the same as that of Example 1, except that the feed flow rate of hexafluorobutyne in the secondary adsorption purification operation is 10 L / h, and other operations remain unchanged.

[0173] The adsorption depth of each type of impurity was obtained using the aforementioned testing and calculation methods, and the specific results are shown in Table 4.

[0174] Example 9

[0175] The operation of Example 9 is the same as that of Example 1, except that the liquid phase flow rate of crude hexafluorobutyne in the secondary adsorption purification operation is 20 L / h, and other operations remain unchanged.

[0176] The adsorption depth of each type of impurity was obtained using the aforementioned testing and calculation methods, and the specific results are shown in Table 4.

[0177] Example 10

[0178] The operation of Example 10 is the same as that of Example 1, except that the adsorption temperature in the secondary adsorption purification operation is -30℃, and other operations remain unchanged.

[0179] The adsorption depth of each type of impurity was obtained using the aforementioned testing and calculation methods, and the specific results are shown in Table 4.

[0180] Example 11

[0181] The operation of Example 11 is the same as that of Example 1, except that the adsorption temperature in the secondary adsorption purification operation is -20℃, and other operations remain unchanged.

[0182] The adsorption depth of each type of impurity was obtained using the aforementioned testing and calculation methods, and the specific results are shown in Table 4.

[0183] Example 12

[0184] The operation of Example 12 is the same as that of Example 1, except that the adsorption pressure in the secondary adsorption purification operation is 0.02 MPa, and the other operations remain unchanged.

[0185] The adsorption depth of each type of impurity was obtained using the aforementioned testing and calculation methods, and the specific results are shown in Table 4.

[0186] Example 13

[0187] The operation of Example 13 is the same as that of Example 1, except that the adsorption pressure in the secondary adsorption purification operation is 0.04 MPa, and the other operations remain unchanged.

[0188] The adsorption depth of each type of impurity was obtained using the aforementioned testing and calculation methods, and the specific results are shown in Table 4.

[0189] Table 4 Adsorption depth of Examples 8-13

[0190]

[0191] Excessive adsorption temperature and pressure during the secondary adsorption process can affect the adsorption depth of moisture and hydrogen fluoride, thus impacting the purity of the hexafluorobutyne product.

Claims

1. A method for preparing molecular sieves with modified inner and outer surfaces, characterized in that: Includes the following steps: S1: In organic solvent I, the bulk molecular sieve reacts with a titanate surface modifier under vacuum to obtain an outer surface modified molecular sieve; S2: The outer surface modified molecular sieve and the inner surface modifier are reacted under microwave irradiation in organic solvent II to obtain the inner and outer surface modified molecular sieve.

2. The method for preparing the inner and outer surface modified molecular sieve according to claim 1, characterized in that: The bulk molecular sieve mentioned in step S1 is an FAU molecular sieve and / or an MFI molecular sieve.

3. The method for preparing the inner and outer surface modified molecular sieve according to claim 2, characterized in that: The FAU molecular sieve is selected from NaX molecular sieve and / or NaY molecular sieve; the MFI molecular sieve is selected from at least one of ZSM-5 molecular sieve, TS-1 molecular sieve, and silicalite-1 molecular sieve.

4. The method for preparing the inner and outer surface modified molecular sieve according to claim 1, characterized in that: The organic solvent I and organic solvent II are selected from at least one of toluene, cyclohexane, ethanol, acetonitrile, xylene, and ethyl acetate, respectively; the mass ratio of the bulk molecular sieve to the organic solvent in step S1 is 1:5 to 1:50; the mass ratio of the external surface modified molecular sieve to the organic solvent in step S2 is 1:5 to 1:

50.

5. The method for preparing the inner and outer surface modified molecular sieve according to claim 1, characterized in that: The titanate surface modifier mentioned in step S1 is selected from at least one of isopropyl tris(isostearoyl) titanate, isopropyl tris(dioctylpyrophosphoryl) titanate, and di(dioctylpyrophosphoryl)oxyacetate.

6. The method for preparing the inner and outer surface modified molecular sieve according to claim 5, characterized in that: The concentration of the titanate surface modifier in organic solvent I is 0.1–5.0 mol / L.

7. The method for preparing the inner and outer surface modified molecular sieve according to claim 1, characterized in that: The vacuum level in step S1 is 10. -5 ~10 -3 Pa, under vacuum, the reaction temperature is 20–150℃, and the reaction time is 10–48h.

8. The method for preparing the inner and outer surface modified molecular sieve according to claim 1, characterized in that: The internal surface modifier mentioned in step S2 is selected from carboxylic acid compounds and / or amine compounds.

9. The method for preparing the inner and outer surface modified molecular sieve according to claim 8, characterized in that: The carboxylic acid compound is selected from at least one of acetic acid, oxalic acid, and acetic acid; the amine compound is selected from at least one of triethylamine, ethylenediamine, and xyleneamine.

10. The method for preparing the inner and outer surface modified molecular sieve according to claim 8, characterized in that: The concentration of the internal surface modifier in organic solvent II is 0.1–2.0 mol / L.

11. The method for preparing the inner and outer surface modified molecular sieve according to claim 1, characterized in that: The microwave radiation power in step S2 is 300–1500W, the reaction temperature is 20–200℃, and the reaction time is 2–24h.

12. A molecular sieve with modified inner and outer surfaces prepared by any one of the preparation methods described in claims 1-11.

13. The application of the inner and outer surface modified molecular sieve according to claim 12 in the purification of hexafluorobutyne, characterized in that: Industrial-grade hexafluorobutyne is obtained by primary adsorption via the aforementioned inner and outer surface modified molecular sieve, secondary adsorption via composite metal compound, and distillation.

14. The application of the inner and outer surface modified molecular sieve according to claim 13 in the purification of hexafluorobutyne, characterized in that: In the primary adsorption process, the flow rate of industrial-grade hexafluorobutyne feedstock is 1–100 L / h, the adsorption temperature is 20–80 °C, and the adsorption pressure is 0.01–0.2 MPa.

15. The application of the inner and outer surface modified molecular sieve according to claim 13 in the purification of hexafluorobutyne, characterized in that: In the secondary adsorption process, the flow rate of crude hexafluorobutyne after primary adsorption is 1-50 L / h, the adsorption temperature is -60 to -20℃, and the adsorption pressure is 0.01-0.1 MPa.

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