Separation and purification method of fluorocarbon gases

Abstract

The present invention relates to the field of electronic special gases, and in particular to a method for separating and purifying carbon fluorine gases, which comprises the following steps: (1) mixing chlorine gas into industrial-grade carbon fluorine gas, and removing hydrocarbon chlorine therein under ultraviolet irradiation and cleaning; (2) subjecting the cleaned industrial-grade carbon fluorine gas to catalytic oxidation by a transition metal oxide; (3) passing the carbon fluorine gas after catalytic oxidation treatment into an ionic liquid containing an impurity gas adsorbent for adsorption; (4) after the adsorption, passing the carbon fluorine gas into a distillation tower for distillation to remove light and heavy gases, thereby obtaining a high-purity carbon fluorine gas. The method of the present invention can fully separate and purify carbon fluorine gases, and the high-purity carbon fluorine gas obtained after purification can be effectively used in the semiconductor industry. At the same time, the purification method of the present invention is simple to operate, can be effective and low-cost, and can be suitable for industrial-grade applications.

Description

Technical Field

[0001] The invention relates to the field of electronic special gases, and in particular to a method for separating and purifying carbon-fluorine gases. Background Art

[0002] In the production process of the entire semiconductor industry, from chip growth to the final device packaging, almost every link is inseparable from electronic special gases, and the gases used are of many varieties and high quality requirements, so electronic gases are also known as the "food" of semiconductor materials. Although the cost of electronic special gases only accounts for 5-6% of the total cost of IC materials, it largely determines the performance of the final product. Therefore, the quality of electronic special gases has become an important factor restricting the development of the electronics industry.

[0003] Currently, fluorine-containing electronic gases account for about 30% of the total global electronic gas market. Fluorine-containing electronic gases are an important component of special electronic gases in the field of electronic information materials. They are mainly used as cleaning agents and etching agents, and can also be used as dopants, film-forming materials, etc.

[0004] Fluorocarbon gases are an important type of fluorine-containing electronic gases. Perfluoroalkanes are widely used in the semiconductor industry. Typical perfluoroalkanes include CF 4 , C 2 F 6 , C 3 F 8 , C 4 F 8 Fluorocarbon gases such as fluorine. Since perfluoroalkanes are obtained by replacing all hydrogen atoms in alkanes with fluorine atoms, perfluoroalkanes have the characteristics of extremely strong chemical stability, surface activity and excellent temperature resistance.

[0005] However, due to the extremely strong chemical reactivity of elemental fluorine, when it is used as a fluorinating agent for fluorination reactions, all carbon-hydrogen bonds in organic compounds can be converted into carbon-fluorine bonds, and a large amount of heat is released during the reaction. Therefore, it is often accompanied by various bond breaking reactions, coupling reactions, and polymerization reactions. Therefore, the products inside the perfluoroalkane obtained in the end are complex and have many by-products, which seriously restricts the development of semiconductor manufacturing processes and technologies.

[0006] For the purification of fluorocarbon gases, the patent with application number CN202111672465.8 discloses a high-purity perfluorocarbon electronic special gas adsorption purification method under inert gas protection, the steps of which are: (1) mixing high-purity inert gas and perfluorocarbon electronic special gas crude raw material gas from high to low concentration at a ratio of high-purity inert gas volume concentration of 100% to 0 to obtain a liquid mixed gas; (2) adsorbing the liquid mixed gas, condensing the purified gas, obtaining a liquid perfluorocarbon electronic special gas intermediate gas, and circulating the non-condensable high-purity inert gas; (3) when the volume proportion of high-purity inert gas in the liquid mixed gas is 0, the liquid perfluorocarbon electronic special gas intermediate gas replaces the liquid mixed gas and is cut into the adsorption tower and passed into the condenser, and cyclically adsorbed to obtain a high-purity perfluorocarbon electronic special gas product gas. This invention deeply removes impurities from the crude raw material gas of perfluorocarbon electronic special gas, and is suitable for the preparation of high-purity and ultra-high-purity electronic-grade perfluorocarbon electronic special gas in continuous production. However, it requires various high-purity inert gases during the purification process, which makes its cost relatively high. At the same time, it requires precise gas distribution many times during the purification process, so the operation process is relatively complicated. Summary of the invention

[0007] The present invention aims to overcome the defects of the prior art in that the carbon fluorine gas has complex operation and high purification cost during the purification process, and provides a method for separating and purifying carbon fluorine gas to overcome the above shortcomings.

[0008] To achieve the above-mentioned purpose, the present invention is implemented by the following technical solutions:

[0009] In a first aspect, the present invention first provides a method for separating and purifying carbon fluorine gases, comprising the following steps:

[0010] (1) Chlorine is mixed into industrial-grade carbon fluoride gas, and hydrocarbons therein are chlorinated under ultraviolet irradiation, and after the reaction is complete, the industrial-grade carbon fluoride gas is cleaned with alkaline solution;

[0011] (2) subjecting the cleaned industrial-grade carbon fluoride gas to catalytic oxidation by a transition metal oxide, so that the reducing impurity gas therein is oxidized;

[0012] (3) passing the carbon fluorine gas after catalytic oxidation treatment into an ionic liquid containing an impurity gas adsorbent for adsorption; (4) after the adsorption is completed, passing the carbon fluorine gas into a distillation tower for distillation to remove light and heavy gases, thereby obtaining a high-purity carbon fluorine gas;

[0013] The impurity gas adsorbent in step (3) includes an oxygen adsorption unit and a carbon dioxide adsorption unit.

[0014] The target gas to be purified in the present invention is an important type of fluorocarbon gas, namely perfluoroalkane. In the prior art, perfluoroalkane usually contains a certain amount of impurity gases such as incompletely substituted fluorinated alkanes (such as trifluoromethane, pentafluoroethane, etc.), fluorinated olefins (such as hexafluorobutadiene), oxygen, carbon dioxide, water and hydrogen fluoride.

[0015] At present, distillation or selective absorption is usually used to remove these impurity gases. However, some impurity gases are difficult to remove by conventional distillation or selective absorption because their physical and chemical properties are close to those of the target products.

[0016] In the process of purifying fluorocarbon gases, the present invention firstly mixes a certain amount of chlorine into industrial-grade fluorocarbon gases, and allows the originally incompletely substituted fluorine-containing alkanes and fluorine-containing olefins to undergo a photochemical reaction with the chlorine under light conditions, thereby causing a substitution reaction or an addition reaction, thereby effectively changing the physicochemical properties of the incompletely substituted fluorine-containing alkanes and fluorine-containing olefins, thereby increasing the degree of differentiation between the physicochemical properties of the impurity gas and the target product, thereby making it easier to separate from the target fluorocarbon gas.

[0017] After the photochemical reaction, the original unsubstituted fluorinated alkanes and fluorinated alkenes in the target fluorinated carbon gas can be converted into fluorochlorocarbons and accompanied by the formation of a certain amount of hydrogen chloride, and a portion of chlorine is also mixed therein. Among them: compared with perfluoroalkanes and unsubstituted fluorinated alkanes, fluorochlorocarbons are more chemically active, and the chlorine atoms therein can undergo hydrolysis reaction with alkali, and hydrogen chloride and chlorine can also be absorbed by alkali solution. Therefore, the present invention also uses alkali solution for cleaning after the photochemical reaction, so that most of the fluorochlorocarbons and chlorine can be effectively absorbed by the alkali solution. Therefore, after step (1), it is also necessary to perform a catalytic oxidation step on the industrial-grade fluorocarbon gas. Since the target fluorocarbon gas (perfluoroalkane) is chemically inert, it can maintain its own integrity even after catalytic oxidation, and fluorochlorocarbons and chlorine can be completely reacted to form carbon dioxide, and the fluorine atoms are fixed by transition metal oxides.

[0018] Therefore, after the treatment of step (2), the carbon fluorine gas will only contain a certain amount of impurity gases such as oxygen, carbon dioxide and nitrogen. A part of this impurity gas can be absorbed by the impurity gas adsorbent in step (3). It should be noted that the adsorption in the ionic liquid in step (3) is because the carbon fluorine gas has excellent solubility for oxygen. Therefore, in the actual process, the outer layer of the oxygen molecule is always covered with a layer of carbon fluorine gas. Therefore, it is difficult to completely absorb the oxygen dissolved in the carbon fluorine gas by conventional adsorption methods. In the ionic liquid, since the carbon fluorine gas has a certain solubility, the oxygen can be exposed after being dissolved in the ionic liquid, thereby increasing the contact surface with the impurity gas adsorbent. At the same time, since the ionic liquid can have a certain gas flow rate with the carbon fluorine gas, it can greatly prolong the contact time between the impurity gas and the impurity gas adsorbent, thereby greatly enhancing the absorption effect of the impurity gas.

[0019] Therefore, after the treatment in step (3), the carbon fluorine gas only contains a certain amount of nitrogen (light gas) and a part of higher perfluoroalkanes (heavy gas). These two types of gases can be completely removed by conventional distillation. Therefore, after step (4), the purity of the carbon fluorine gas can be greatly improved, so that it can be used in the semiconductor industry.

[0020] Preferably, the chlorination step in step (1) is carried out in a photochemical reaction tower, the tower top temperature is 20-100°C, the tower bottom temperature is 20-100°C, the reflux ratio is 1-5, the ultraviolet lamp wavelength is 250-450nm, the ultraviolet lamp power is 0.5-5kw, and the chlorine mixing amount is 100-500ppm.

[0021] The content of impurity gases in industrial-grade carbon fluorine gas is usually around tens of ppm, so the amount of chlorine mixed in the invention is about ten times that of the impurity gases, so that the chlorine gas has a more sufficient chlorination effect on the impurity gases and will not introduce excessive chlorine into the carbon fluorine gas.

[0022] Preferably, the alkali solution is any one of sodium hydroxide, potassium hydroxide and tetramethylammonium hydroxide solution; the mass concentration of alkali in the alkali solution is 10-30wt%, and the temperature of the alkali solution is 50-80°C.

[0023] Preferably, step (2) is as follows: the cleaned industrial-grade carbon fluoride gas is introduced into a catalytic oxidation tower filled with copper oxide, and the filler is heated to a temperature of 350-450° C., so that the reducing impurity gas therein contacts and reacts with the hot copper oxide, thereby completing the catalytic oxidation step.

[0024] In the prior art, a certain amount of oxygen is usually continuously introduced during the catalytic oxidation of reducing gas, so that the oxygen can catalytically oxidize the reducing impurity gas doped in the carbon fluorine gas. However, this method has the following technical difficulties. First, the reducing impurities in each batch of rare gas to be treated need to be measured before catalytic oxidation, so as to reasonably configure the amount of oxygen introduced, which is a relatively cumbersome process. Secondly, since the carbon fluorine gas in the present invention is an industrial-grade rare gas, the content of reducing impurities in it is relatively low, so the preparation of oxygen is more delicate and difficult. Once improperly prepared, it often fails to reduce the content of reducing gas impurities, and will increase the content of oxygen impurities.

[0025] In the present invention, copper oxide is directly used as an oxidant. After the carbon fluorine gas is introduced into the copper oxide, the reducing gas impurities therein can react with the copper oxide at high temperature. For example, chlorofluorocarbon gas will react with the copper oxide to generate carbon dioxide, water, copper chloride, copper fluoride and copper. Therefore, the present invention can effectively treat the reducing gas in the carbon fluorine gas without introducing other impurities, simplifying the composition ratio of internal impurities in the rare gas. At the same time, its oxidizing property is milder, so that it will not react with the target product, effectively improving the stability of the target product.

[0026] At the same time, after copper oxide catalytic oxidation for a certain period of time, the newly formed copper element can also react with oxygen to continue to form copper oxide. The newly formed copper oxide can further participate in the reaction with the reducing gas, thereby effectively reducing the content of impurity gases in the carbon fluorine gas.

[0027] Preferably, the preparation method of the impurity gas adsorbent in step (3) is as follows:

[0028] The preparation method of the impurity gas adsorbent in step (3) is as follows:

[0029] (S.1) reacting a compound containing a hydroxyl group and an oxygen adsorption unit with a silane containing an alkoxy group to obtain a monomer I containing an oxygen adsorption unit;

[0030] (S.2) reacting a monomer containing a carbon dioxide adsorption unit and a vinyl group with a silane containing both silicon hydrogen and an alkoxy group to undergo a silylation reaction to obtain a monomer II containing a carbon dioxide adsorption unit;

[0031] (S.3) Monomer I and monomer II are mixed and hydrolyzed to obtain an impurity gas adsorbent having an oxygen adsorption unit and a carbon dioxide adsorption unit.

[0032] Preferably, the compound containing hydroxyl group and oxygen adsorption unit in step (S.1) includes any one or more combinations of retinol, vitamin C, vitamin E and dopamine.

[0033] Preferably, the monomer containing the carbon dioxide adsorption unit and the vinyl monomer in step (S.2) includes any one of acrylamide, methacrylamide, and acrylic acid-modified amino acid.

[0034] Preferably, the acrylic acid-modified amino acid includes at least two amino groups.

[0035] Preferably, the ionic liquid includes one or more combinations of imidazole ionic liquids, quaternary ammonium ionic liquids, quaternary phosphonium ionic liquids, pyrrolidine ionic liquids, and piperidine ionic liquids.

[0036] Preferably, the cation of the ionic liquid is N-hexylpyridine, N-butylpyridine, N-octylpyridine, N-butyl-N-methylpyrrolidine, 1-butyl-3-methylimidazole, 1-propyl-3-methylimidazole, 1-ethyl-3-methylimidazole, 1-hexyl-3-methylimidazole, 1-octyl-3-methylimidazole, 1-allyl-3-methylimidazole, 1-butyl-2,3-dimethylimidazole, 1-butyl-3-methylimidazole, tributylmethylphosphine, tributylethylphosphine, Any one of tetrabutylphosphine, tributylhexylphosphine, tributyloctylphosphine, tributyldecylphosphine, tributyldodecylphosphine, tributyltetradecylphosphine, triphenylethylphosphine, triphenylbutylphosphine, triphenylmethylphosphine, triphenylpropylphosphine, triphenylpentylphosphine, triphenylacetonylphosphine, triphenylbenzylphosphine, triphenyl(3-bromopropyl)phosphine, triphenylbromomethylphosphine, triphenylmethoxyphosphine, triphenylethoxycarbonylmethylphosphine, triphenyl((3-bromopropyl)phosphine, triphenylvinylphosphine, and tetraphenylphosphine.

[0037] Preferably, the anion of the ionic liquid is BF 4 - PF 6 - CF 3 SO 3 - ,(CF 3 SO 2 ) 2 N-、C 3 F 7 COO - , C 4 F 9 SO 3 CF 3 COO - ,(CF 3 SO 2 ) 3 C - , (C 2 F 5 SO2 ) 3 C - , (C 2 F 5 SO 2 ) 2 N - , SbF 6 - , any one of the following.

[0038] Preferably, the ionic liquid includes 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium dicyanamide, 1-ethyl-3-methylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium chloroaluminate, 1-ethyl-2,3-dimethylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium bis-trifluoromethanesulfonyl imide, 1-allyl-3-methylimidazolium bis-trifluoromethanesulfonyl imide, 1-ethyl-3-methylimidazolium chloride, 1-ethyl -3-Methylimidazolium bistrifluoromethanesulfonyl imide salt, 1-sulfonic acid butyl-2-methyl-3-hexadecyl imidazolium hydrogen sulfate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium carbonate, 1-ethyl-3-methylimidazolium L-lactate, 1,3-dimethylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-propyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-hexyl- 3-Methylimidazolium hexafluorophosphate, 1-octyl-3-methylimidazolium hexafluorophosphate, 1-decyl-3-methylimidazolium hexafluorophosphate, 1-tetradecyl-3-methylimidazolium hexafluorophosphate, 1-benzyl-3-methylimidazolium hexafluorophosphate, 1-allyl-3-methylimidazolium hexafluorophosphate, 1-vinyl-3-ethylimidazolium hexafluorophosphate, 1-vinyl-3-butylimidazolium hexafluorophosphate, 1-hexadecyl-2,3-dimethylimidazolium hexafluorophosphate, 1-octyl -2,3-dimethylimidazolium hexafluorophosphate, 1,3-dimethylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-decyl-3-methylimidazolium tetrafluoroborate, 1-benzyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-2,3-dimethylimidazolium tetrafluoroborate, 1-propyl-2,3-dimethylimidazolium tetrafluoroborate, 1-octyl-2,3-dimethylimidazolium tetrafluoroborate, 1-octyl-2,3-dimethylimidazolium tetrafluoroborate.

[0039] Preferably, in step (3), the pressure of the adsorption tower is 0.1-0.5 MPa, and the adsorption temperature is 0-150°C.

[0040] Preferably, the number of theoretical plates of the distillation tower in the light-removal step is 30 to 50, the reflux ratio is 50 to 200, and the operating pressure is 1.5 MPa to 2.5 MPa.

[0041] Preferably, the number of theoretical plates of the distillation tower in the deweighting step is 30 to 50, the reflux ratio is 10 to 30, and the operating pressure is 1.5 MPa to 2.5 MPa.

[0042] Therefore, the present invention has the following beneficial effects:

[0043] (1) The method of the present invention can fully separate and purify carbon fluorine gases, and the high-purity carbon fluorine gases obtained after purification can be effectively used in the semiconductor industry;

[0044] (2) The purification method of the present invention is simple to operate, effective and low-cost, and can be suitable for industrial-grade applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a photograph of a silicon dioxide aerogel block obtained by preliminary crushing during the preparation of the impurity gas adsorbent I of the present invention.

[0046] Figure 2 This is an electron microscope photograph of impurity gas adsorbent Ⅰ. DETAILED DESCRIPTION

[0047] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments of the specification. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[0048]

Preparation of Monomer Ⅰ

[0049] Preparation of monomer (I-I): Under nitrogen protection, 2.86 g (10 mmol) of retinol was dissolved in 50 ml of dichloromethane, and then a mixed solution of 1.57 g (10 mmol) of trimethoxysilyl chloride and 20 ml of dichloromethane was added dropwise thereto at -10°C. After reacting for 3 hours, the solvent was evaporated to obtain a crude monomer (I-I). After column purification, monomer (I-I) was obtained. The reaction formula is shown in the following formula (1):

[0050]

[0051] Preparation of monomer (I-II): Under nitrogen protection, 4.24 g (10 mmol) of α-tocotrienol was dissolved in 50 ml of dichloromethane, and then a mixed solution of 1.57 g (10 mmol) of trimethoxysilyl chloride and 20 ml of dichloromethane was added dropwise thereto at -10°C. After reacting for 3 hours, the solvent was evaporated to obtain a crude monomer (I-II). After column purification, a monomer (I-II) was obtained, and its reaction formula is shown in the following formula (2):

[0052]

[0053] Preparation of monomers (I-III): Under nitrogen protection, 1.76 g (10 mmol) of vitamin C was dispersed in 50 ml of dichloromethane, and then a mixed solution of 1.57 g (10 mmol) of trimethoxysilyl chloride and 20 ml of dichloromethane was added dropwise thereto at -10°C. After reacting for 3 hours, the solvent was evaporated to obtain crude monomers (I-III). After column purification, monomers (I-III) were obtained. The reaction formula is shown in the following formula (3):

[0054]

[0055]

Preparation of Monomer II

[0056] Preparation of monomer (II-I):

[0057] (1) Protection of amino group: Under nitrogen protection, ethyl trifluoroacetate (11 mmol) was dissolved in 10 ml of anhydrous ether and stirred at 0° C. for 10 minutes. Lysine (5 mmol) was added and the reaction mixture was stirred at the same temperature for 1 hour. After removing the solvent, the residue was purified by flash column chromatography to obtain lysine protected by amino group. The reaction formula is shown in the following formula (5):

[0058] (2) Under nitrogen protection, amino-protected lysine (3.38 g 10 mmol) was dissolved in 20 ml of dichloromethane, oxalyl chloride (4.25 mL, 48.40 mmol) was added, and the resulting mixture was stirred at room temperature for 30 minutes, and then the mixture was slowly heated under reflux for 30 minutes. After the mixture was concentrated in vacuo, the residue was dissolved in THF, and the solution was concentrated in vacuo again to obtain amino-protected and chlorinated lysine, the reaction formula of which is shown in the following formula (6):

[0059]

[0060] (3) Under nitrogen protection, hydroxyethyl acrylate (1.16 g 10 mmol) was dissolved in 30 ml of dichloromethane, and then a mixed solution containing amino-protected and chlorinated lysine (3.56 g 10 mmol) and 20 ml of dichloromethane was added dropwise thereto at -10°C. After reacting for 3 hours, the solvent was evaporated to obtain a crude intermediate (II-I). After column purification, an intermediate (II-I) was obtained, and its reaction formula is shown in the following formula (7):

[0061]

[0062] (4) Under nitrogen protection, the intermediate (II-I) (4.36 g 10 mmol) was dissolved in 5% K 2 CO 3 MeOH / H 2 O (50 mL) and the solution was stirred at 23 °C for 4 h. 2 O (3 mL), saturated with NaCl, and then with CH 2 Cl 2 (5 × 15 mL) extraction. The combined organic extracts were dried (Na 2 SO 4 ) and concentrated under reduced pressure to obtain intermediate (II-II), the reaction formula of which is shown in the following formula (8):

[0063]

[0064] (5) Under nitrogen protection, the intermediate (II-II) (2.44 g 10 mmol) and trimethoxysilane (1.46 g 12 mmol) were dissolved in 20 ml of toluene, 0.1 g of Custer catalyst (platinum catalyst) was added thereto, and after reflux reaction for 5 h, 1 g of activated carbon was added to the reaction solution, and the mixture was stirred and adsorbed at room temperature for 1 h, and then the filtrate was filtered to obtain the filtrate, and the solvent in the filtrate was evaporated to obtain the monomer (II-I), and the reaction formula thereof is shown in the following formula (8):

[0065]

[0066] Preparation of monomer (II-II): The preparation method of monomer (II-II) is similar to that of monomer (II-I), except that lysine is replaced by alanine. The structure of monomer (II-II) is shown in the following formula (9):

[0067]

[0068] Preparation of monomer (II-III):

[0069] (5) Under nitrogen protection, acrylamide (3.55 g 50 mmol) and trimethoxysilane (7.3 g 60 mmol) were dissolved in 50 ml of toluene, 0.1 g of Custer catalyst (platinum catalyst) was added thereto, and refluxed for 5 h. Then, 1 g of activated carbon was added to the reaction solution. After stirring and adsorbing at room temperature for 1 h, the filtrate was filtered to obtain the filtrate. The solvent in the filtrate was evaporated to obtain monomer (II-III). The reaction formula is shown in the following formula (10):

[0070]

[0071]

Preparation of impurity gas adsorbent

[0072] Preparation of impurity gas adsorbent Ⅰ:

[0073] Under nitrogen protection, monomer (Ⅰ-Ⅰ), monomer (Ⅱ-Ⅰ) and tetraethyl orthosilicate were uniformly mixed in a mass ratio of 3:3:4 to obtain a mixed monomer;

[0074] Weigh the raw materials according to the mass ratio: ethanol: mixed monomer: deionized water: ammonia water = 4:1:1:0.16.

[0075] Add ethanol, tetraethyl orthosilicate and deionized water to the beaker in proportion and mix and stir for 90 minutes. After mixing evenly, let it stand for 24 hours to allow the mixed monomers to be fully hydrolyzed, and then start stirring for 60. Adjust the pH value to 6-7 with ammonia water, and then pour it into a closed container to form a wet gel. After aging, take it out of the mold and soak it in n-hexane to replace the water and ethanol in the wet gel. Then, dry the wet gel at room temperature and pressure for two days and place it in a vacuum drying oven. The initial temperature is 30°C, and the temperature is increased by 5°C per hour until it reaches 70°C. Keep drying at 70°C for 24 hours, and initially crush it to obtain silica aerogel blocks (such as Figure 1 ), which was crushed again and passed through a 500-mesh sieve to obtain the impurity gas adsorbent I (electron microscope image as shown in Figure 2 shown).

[0076] Preparation of impurity gas adsorbent II:

[0077] The preparation method of impurity gas adsorbent II is the same as that of impurity gas adsorbent I, except that the mixed monomer is obtained by mixing monomer II), monomer (II-I) and tetraethyl orthosilicate.

[0078] Preparation of impurity gas adsorbent III:

[0079] The preparation method of the impurity gas adsorbent III is the same as that of the impurity gas adsorbent I, except that the mixed monomer is obtained by mixing monomer (I-III), monomer (II-I) and tetraethyl orthosilicate.

[0080] Preparation of impurity gas adsorbent IV:

[0081] The preparation method of impurity gas adsorbent IV is the same as that of impurity gas adsorbent I, except that the mixed monomer is obtained by mixing monomer (I-I), monomer (II-II) and tetraethyl orthosilicate.

[0082] Preparation of impurity gas adsorbent V:

[0083] The preparation method of impurity gas adsorbent V is the same as that of impurity gas adsorbent I, except that the mixed monomer is obtained by mixing monomer (I-I), monomer (II-III) and tetraethyl orthosilicate.

[0084] Example 1

[0085] The method for separating and purifying tetrafluoromethane comprises the following steps:

[0086] (1) introducing industrial-grade tetrafluoromethane into a photochemical reaction tower, and mixing 300 ppm of chlorine therein, setting the tower top temperature to 30° C., the tower bottom temperature to 30° C., the reflux ratio to 3, the ultraviolet lamp wavelength to 365 nm, and the ultraviolet lamp power to 3 kW, so that hydrocarbon impurities in the industrial-grade carbon fluoride gas are chlorinated under ultraviolet irradiation, and after the reaction is complete, introducing the gas into a sodium hydroxide solution with a temperature of 70° C. and a mass concentration of 20 wt % for cleaning;

[0087] (2) introducing the cleaned industrial-grade tetrafluoromethane into a catalytic oxidation tower filled with copper oxide, and heating the filler to a temperature of 400° C., setting the flow rate of the industrial-grade tetrafluoromethane to 4 kg / h, and the pressure of the catalytic oxidation tower to 0.3 MPa, so that the reducing impurity gas therein contacts and reacts with the hot copper oxide, completing the catalytic oxidation step, so that the reducing impurity gas therein is oxidized;

[0088] (3) introducing the tetrafluoromethane after catalytic oxidation treatment into a mixed liquid containing impurity gas adsorbent I and 1-butyl-3-methylimidazolium trifluoromethanesulfonate in a mass ratio of 10:1 for adsorption, the pressure of the adsorption tower is 0.3 MPa, and the adsorption temperature is 50° C.;

[0089] (4) After the adsorption is completed, tetrafluoromethane is introduced into a distillation tower for distillation, and the distillation includes light removal and heavy removal steps to obtain high-purity tetrafluoromethane gas and collect it.

[0090] Example 2

[0091] The method for separating and purifying tetrafluoromethane comprises the following steps:

[0092] (1) introducing industrial-grade tetrafluoromethane into a photochemical reaction tower, and mixing 300 ppm of chlorine therein, setting the tower top temperature to 30° C., the tower bottom temperature to 30° C., the reflux ratio to 3, the ultraviolet lamp wavelength to 365 nm, and the ultraviolet lamp power to 3 kW, so that hydrocarbon impurities in the industrial-grade carbon fluoride gas are chlorinated under ultraviolet irradiation, and after the reaction is complete, introducing the gas into a sodium hydroxide solution with a temperature of 70° C. and a mass concentration of 20 wt % for cleaning;

[0093] (2) introducing the cleaned industrial-grade tetrafluoromethane into a catalytic oxidation tower filled with copper oxide, and heating the filler to a temperature of 400° C., setting the flow rate of the industrial-grade tetrafluoromethane to 4 kg / h, and the pressure of the catalytic oxidation tower to 0.3 MPa, so that the reducing impurity gas therein contacts and reacts with the hot copper oxide, completing the catalytic oxidation step, so that the reducing impurity gas therein is oxidized;

[0094] (3) introducing the tetrafluoromethane after catalytic oxidation treatment into a mixed liquid containing an impurity gas adsorbent II and 1-butyl-3-methylimidazolium trifluoromethanesulfonate in a mass ratio of 10:1 for adsorption, the pressure of the adsorption tower being 0.3 MPa and the adsorption temperature being 50° C.;

[0095] (4) After the adsorption is completed, tetrafluoromethane is introduced into a distillation tower for distillation, and the distillation includes light removal and heavy removal steps to obtain high-purity tetrafluoromethane gas and collect it.

[0096] Example 3

[0097] The method for separating and purifying tetrafluoromethane comprises the following steps:

[0098] (1) introducing industrial-grade tetrafluoromethane into a photochemical reaction tower, and mixing 300 ppm of chlorine therein, setting the tower top temperature to 30° C., the tower bottom temperature to 30° C., the reflux ratio to 3, the ultraviolet lamp wavelength to 365 nm, and the ultraviolet lamp power to 3 kW, so that hydrocarbon impurities in the industrial-grade carbon fluoride gas are chlorinated under ultraviolet irradiation, and after the reaction is complete, introducing the gas into a sodium hydroxide solution with a temperature of 70° C. and a mass concentration of 20 wt % for cleaning;

[0099] (2) introducing the cleaned industrial-grade tetrafluoromethane into a catalytic oxidation tower filled with copper oxide, and heating the filler to a temperature of 400° C., setting the flow rate of the industrial-grade tetrafluoromethane to 4 kg / h, and the pressure of the catalytic oxidation tower to 0.3 MPa, so that the reducing impurity gas therein contacts and reacts with the hot copper oxide, completing the catalytic oxidation step, so that the reducing impurity gas therein is oxidized;

[0100] (3) introducing the tetrafluoromethane after catalytic oxidation treatment into a mixed liquid containing impurity gas adsorbent III and 1-butyl-3-methylimidazolium trifluoromethanesulfonate in a mass ratio of 10:1 for adsorption, the pressure of the adsorption tower is 0.3 MPa, and the adsorption temperature is 50° C.;

[0101] (4) After the adsorption is completed, tetrafluoromethane is introduced into a distillation tower for distillation, and the distillation includes light removal and heavy removal steps to obtain high-purity tetrafluoromethane gas and collect it.

[0102] Example 4

[0103] The method for separating and purifying tetrafluoromethane comprises the following steps:

[0104] (1) introducing industrial-grade tetrafluoromethane into a photochemical reaction tower, and mixing 300 ppm of chlorine therein, setting the tower top temperature to 30° C., the tower bottom temperature to 30° C., the reflux ratio to 3, the ultraviolet lamp wavelength to 365 nm, and the ultraviolet lamp power to 3 kW, so that hydrocarbon impurities in the industrial-grade carbon fluoride gas are chlorinated under ultraviolet irradiation, and after the reaction is complete, introducing the gas into a sodium hydroxide solution with a temperature of 70° C. and a mass concentration of 20 wt % for cleaning;

[0105] (2) introducing the cleaned industrial-grade tetrafluoromethane into a catalytic oxidation tower filled with copper oxide, and heating the filler to a temperature of 400° C., setting the flow rate of the industrial-grade tetrafluoromethane to 4 kg / h, and the pressure of the catalytic oxidation tower to 0.3 MPa, so that the reducing impurity gas therein contacts and reacts with the hot copper oxide, completing the catalytic oxidation step, so that the reducing impurity gas therein is oxidized;

[0106] (3) introducing the tetrafluoromethane after catalytic oxidation treatment into a mixed liquid containing an impurity gas adsorbent IV and 1-butyl-3-methylimidazolium trifluoromethanesulfonate in a mass ratio of 10:1 for adsorption, the pressure of the adsorption tower is 0.3 MPa, and the adsorption temperature is 50° C.;

[0107] (4) After the adsorption is completed, tetrafluoromethane is introduced into a distillation tower for distillation, and the distillation includes light removal and heavy removal steps to obtain high-purity tetrafluoromethane gas and collect it.

[0108] Example 5

[0109] The method for separating and purifying tetrafluoromethane comprises the following steps:

[0110] (1) introducing industrial-grade tetrafluoromethane into a photochemical reaction tower, and mixing 300 ppm of chlorine therein, setting the tower top temperature to 30° C., the tower bottom temperature to 30° C., the reflux ratio to 3, the ultraviolet lamp wavelength to 365 nm, and the ultraviolet lamp power to 3 kW, so that hydrocarbon impurities in the industrial-grade carbon fluoride gas are chlorinated under ultraviolet irradiation, and after the reaction is complete, introducing the gas into a sodium hydroxide solution with a temperature of 70° C. and a mass concentration of 20 wt % for cleaning;

[0111] (2) introducing the cleaned industrial-grade tetrafluoromethane into a catalytic oxidation tower filled with copper oxide, and heating the filler to a temperature of 400° C., setting the flow rate of the industrial-grade tetrafluoromethane to 4 kg / h, and the pressure of the catalytic oxidation tower to 0.3 MPa, so that the reducing impurity gas therein contacts and reacts with the hot copper oxide, completing the catalytic oxidation step, so that the reducing impurity gas therein is oxidized;

[0112] (3) introducing the tetrafluoromethane after catalytic oxidation treatment into a mixed liquid containing an impurity gas adsorbent V and 1-butyl-3-methylimidazolium trifluoromethanesulfonate in a mass ratio of 10:1 for adsorption, the pressure of the adsorption tower being 0.3 MPa and the adsorption temperature being 50° C.;

[0113] (4) After the adsorption is completed, tetrafluoromethane is introduced into a distillation tower for distillation, and the distillation includes light removal and heavy removal steps to obtain high-purity tetrafluoromethane gas and collect it.

[0114] Example 6

[0115] The method for separating and purifying tetrafluoromethane comprises the following steps:

[0116] (1) introducing industrial-grade tetrafluoromethane into a photochemical reaction tower, and mixing 100 ppm of chlorine therein, setting the tower top temperature to 20° C., the tower bottom temperature to 20° C., the reflux ratio to 4, the ultraviolet lamp wavelength to 253.7 nm, and the ultraviolet lamp power to 0.5 kW, so that hydrocarbon impurities in the industrial-grade carbon fluoride gas are chlorinated under ultraviolet irradiation, and after the reaction is complete, introducing the gas into a sodium hydroxide solution having a temperature of 50° C. and a mass concentration of 30 wt % for cleaning;

[0117] (2) introducing the cleaned industrial-grade tetrafluoromethane into a catalytic oxidation tower filled with copper oxide, and heating the filler to a temperature of 350° C., setting the flow rate of the industrial-grade tetrafluoromethane to 1 kg / h, and the pressure of the catalytic oxidation tower to 0.1 MPa, so that the reducing impurity gas therein contacts and reacts with the hot copper oxide, completing the catalytic oxidation step, so that the reducing impurity gas therein is oxidized;

[0118] (3) introducing the tetrafluoromethane after catalytic oxidation treatment into a mixed liquid containing an impurity gas adsorbent I and 1-butyl-3-methylimidazolium trifluoromethanesulfonate in a mass ratio of 10:1 for adsorption, the pressure of the adsorption tower being 0.3 MPa and the adsorption temperature being 40° C.;

[0119] (4) After the adsorption is completed, tetrafluoromethane is introduced into a distillation tower for distillation, and the distillation includes light removal and heavy removal steps to obtain high-purity tetrafluoromethane gas and collect it.

[0120] Example 7

[0121] The method for separating and purifying hexafluoroethane comprises the following steps:

[0122] (1) introducing industrial-grade hexafluoroethane into a photochemical reaction tower, and mixing 300 ppm of chlorine therein, setting the tower top temperature to 70° C., the tower bottom temperature to 80° C., the reflux ratio to 4, the ultraviolet lamp wavelength to 253.7 nm, and the ultraviolet lamp power to 5 kW, so that hydrocarbon impurities in the industrial-grade hexafluoroethane are chlorinated under ultraviolet irradiation, and after the reaction is complete, introducing the gas into a sodium hydroxide solution with a temperature of 50° C. and a mass concentration of 30 wt% for cleaning;

[0123] (2) introducing the cleaned industrial-grade hexafluoroethane into a catalytic oxidation tower filled with copper oxide, and heating the filler to a temperature of 350° C., setting the flow rate of the industrial-grade hexafluoroethane to 1 kg / h, and the pressure of the catalytic oxidation tower to 0.1 MPa, so that the reducing impurity gas therein contacts and reacts with the hot copper oxide, completing the catalytic oxidation step, so that the reducing impurity gas therein is oxidized;

[0124] (3) passing the hexafluoroethane after catalytic oxidation treatment into a mixed liquid containing an impurity gas adsorbent I and 1-butyl-3-methylimidazolium trifluoromethanesulfonate in a mass ratio of 10:1 for adsorption, the pressure of the adsorption tower is 0.3 MPa, and the adsorption temperature is 80° C.;

[0125] (4) After the adsorption is completed, the hexafluoroethane is passed into a distillation tower for distillation. The distillation includes light removal and heavy removal steps to obtain high-purity hexafluoroethane gas and collect it.

[0126] Example 8

[0127] The method for separating and purifying octafluoropropane comprises the following steps:

[0128] (1) introducing industrial-grade octafluoropropane into a photochemical reaction tower, and mixing 300 ppm of chlorine therein, setting the tower top temperature to 100° C., the tower bottom temperature to 100° C., the reflux ratio to 5, the ultraviolet lamp wavelength to 253.7 nm, and the ultraviolet lamp power to 5 kW, so that hydrocarbon impurities in the industrial-grade octafluoropropane are chlorinated under ultraviolet irradiation, and after the reaction is complete, introducing the gas into a sodium hydroxide solution having a temperature of 75° C. and a mass concentration of 15 wt % for cleaning;

[0129] (2) introducing the cleaned industrial-grade octafluoropropane into a catalytic oxidation tower filled with copper oxide, and heating the filler to a temperature of 350° C., setting the flow rate of the industrial-grade octafluoropropane to 5 kg / h, and the pressure of the catalytic oxidation tower to 0.5 MPa, so that the reducing impurity gas therein contacts and reacts with the hot copper oxide, completing the catalytic oxidation step, so that the reducing impurity gas therein is oxidized;

[0130] (3) passing the octafluoropropane after catalytic oxidation treatment into a mixed liquid containing an impurity gas adsorbent I and 1-butyl-3-methylimidazolium trifluoromethanesulfonate in a mass ratio of 10:1 for adsorption, the pressure of the adsorption tower is 0.5 MPa, and the adsorption temperature is 150° C.;

[0131] (4) After the adsorption is completed, the octafluoropropane is passed into a distillation tower for distillation. The distillation includes light removal and heavy removal steps to obtain high-purity octafluoropropane gas and collect it.

[0132] Example 9

[0133] The separation and purification method of octafluorocyclobutane comprises the following steps:

[0134] (1) introducing industrial-grade octafluorocyclobutane into a photochemical reaction tower, and mixing 300 ppm of chlorine therein, setting the tower top temperature to 100° C., the tower bottom temperature to 100° C., the reflux ratio to 5, the ultraviolet lamp wavelength to 253.7 nm, and the ultraviolet lamp power to 5 kW, so that hydrocarbon impurities in the industrial-grade octafluorocyclobutane are chlorinated under ultraviolet irradiation, and after the reaction is complete, introducing the gas into a sodium hydroxide solution having a temperature of 75° C. and a mass concentration of 15 wt % for cleaning;

[0135] (2) introducing the cleaned industrial-grade octafluorocyclobutane into a catalytic oxidation tower filled with copper oxide, and heating the filler to a temperature of 350° C., setting the flow rate of the industrial-grade octafluorocyclobutane to 5 kg / h, and the pressure of the catalytic oxidation tower to 0.5 MPa, so that the reducing impurity gas therein contacts and reacts with the hot copper oxide, completing the catalytic oxidation step, so that the reducing impurity gas therein is oxidized;

[0136] (3) passing the octafluorocyclobutane after catalytic oxidation treatment into a mixed liquid containing an impurity gas adsorbent I and 1-butyl-3-methylimidazolium trifluoromethanesulfonate in a mass ratio of 10:1 for adsorption, the pressure of the adsorption tower is 0.5 MPa, and the adsorption temperature is 150° C.;

[0137] (4) After the adsorption is completed, the octafluorocyclobutane is introduced into a distillation tower for distillation, and the distillation includes light removal and heavy removal steps to obtain high-purity hexafluoroethane gas and collect it.

[0138] The impurity gas contents in the rare gases purified in Examples 1 to 9 are shown in Table 1 below.

[0139] Table 1

[0140]

[0141]

[0142] It can be seen from the data in the above table that the method of the present invention can play a good role in separating and purifying various industrial-grade carbon fluorine gases. After the impurity removal treatment of the present invention, the impurity content in the carbon fluorine gas is greatly reduced, which can meet the requirements of the electronic semiconductor field (such as application in cleaning agents and etching agents) for the purity and quality stability of electronic-grade carbon fluorine gases.

Claims

1. A method for separating and purifying carbon-fluorine gases, characterized in that: The following steps are involved: (1) Chlorine is mixed into industrial-grade carbon-fluorine gas, and hydrocarbons therein are chlorinated under ultraviolet irradiation. After the reaction is complete, the industrial-grade carbon-fluorine gas is cleaned with alkaline solution; (2) The cleaned industrial-grade carbon-fluorine gas is catalytically oxidized by a transition metal oxide, so that the reducing impurity gas therein is oxidized; (3) Passing the carbon-fluorine gas after catalytic oxidation treatment into an ionic liquid containing an impurity gas adsorbent for adsorption; (4) After the adsorption is completed, the carbon-fluorine gas is passed into a distillation tower for distillation to remove light and heavy gases, thereby obtaining a high-purity carbon-fluorine gas; The step (2) is as follows: introducing the cleaned industrial-grade fluorocarbon gas into a catalytic oxidation tower filled with copper oxide, and heating the filler to a temperature of 350-450° C. so that the reducing impurity gas therein contacts and reacts with the hot copper oxide, thereby completing the catalytic oxidation step; The impurity gas adsorbent in step (3) comprises an oxygen adsorption unit and a carbon dioxide adsorption unit; The preparation method of the impurity gas adsorbent in step (3) is as follows: (S.1) reacting a compound containing a hydroxyl group and an oxygen adsorption unit with a silane containing an alkoxy group to obtain a monomer I containing an oxygen adsorption unit; (S.2) reacting a monomer containing a carbon dioxide adsorption unit and a vinyl group with a silane containing both silicon hydrogen and an alkoxy group to undergo a silylation reaction to obtain a monomer II containing a carbon dioxide adsorption unit; (S.3) mixing monomer I and monomer II and hydrolyzing them to obtain an impurity gas adsorbent having an oxygen adsorption unit and a carbon dioxide adsorption unit; The compound containing hydroxyl group and oxygen adsorption unit in step (S.1) includes any one or more combinations of retinol, vitamin C, vitamin E, and dopamine; The monomer containing the carbon dioxide adsorption unit and the vinyl monomer in step (S.2) includes any one of acrylamide, methacrylamide, and acrylic acid-modified amino acid; The ionic liquid includes one or more of an imidazole ionic liquid, a quaternary ammonium ionic liquid, a quaternary phosphonium ionic liquid, a pyrrolidine ionic liquid, and a piperidine ionic liquid; The fluorocarbon gas is perfluoroalkane.

2. The method for separating and purifying fluorocarbon gases according to claim 1, characterized in that: The chlorination step in step (1) is carried out in a photochemical reaction tower, the tower top temperature is 20-100°C, the tower bottom temperature is 20-100°C, the reflux ratio is 1-5, the ultraviolet lamp wavelength is 250-450nm, the ultraviolet lamp power is 0.5-5kw, and the mixing amount of chlorine is 100-500ppm.

3. The method for separating and purifying fluorocarbon gases according to claim 1 or 2, characterized in that: The alkali solution is any one of sodium hydroxide, potassium hydroxide, and tetramethylammonium hydroxide solution; The mass concentration of alkali in the alkali solution is 10-30wt%, and the temperature of the alkali solution is 50-80°C.

4. The method for separating and purifying fluorocarbon gases according to claim 1, characterized in that: The flow rate of carbon fluorine gas is 1kg / h~5kg / h, and the pressure of the catalytic oxidation tower is 0.1MPa~0.5MPa.

5. The method for separating and purifying fluorocarbon gases according to claim 1, characterized in that: The acrylic acid-modified amino acid includes at least two amino groups.

6. The method for separating and purifying fluorocarbon gases according to any one of claims 1 or 5, characterized in that: In step (3), the pressure of the adsorption tower is 0.1-0.5 MPa, and the adsorption temperature is 40-150°C.

Images