Preparation method of chlorine trifluoride
阅读说明：本技术 一种三氟化氯的制备方法 (Preparation method of chlorine trifluoride ) 是由 冉康德 冀勇 马本辉 于 2021-07-17 设计创作，主要内容包括：本发明提出了一种三氟化氯的制备方法,涉及化学合成技术领域。一种三氟化氯的制备方法,其包括以下步骤：将电解产生的含氟混合气进行一次冷凝、二次冷凝、碱金属吸附和过滤后,得到纯化后的氟气；将纯化后的氟气与高纯氯气加入到含有催化剂的反应器中,反应得到三氟化氯粗品；将三氟化氯粗品经过液化、汽化、吸附和精馏,得到高纯度的三氟化氯。通过本发明的制备方法,可以制备得到高纯度的三氟化氯。(The invention provides a preparation method of chlorine trifluoride, and relates to the technical field of chemical synthesis. A method for preparing chlorine trifluoride, comprising the steps of: carrying out primary condensation, secondary condensation, alkali metal adsorption and filtration on the fluorine-containing mixed gas generated by electrolysis to obtain purified fluorine gas; adding the purified fluorine gas and high-purity chlorine gas into a reactor containing a catalyst, and reacting to obtain a chlorine trifluoride crude product; and liquefying, vaporizing, adsorbing and rectifying the chlorine trifluoride crude product to obtain high-purity chlorine trifluoride. By the production method of the present invention, high-purity chlorine trifluoride can be produced.)
1. A method for preparing chlorine trifluoride is characterized by comprising the following steps:
purification of fluorine gas: carrying out primary condensation, secondary condensation, alkali metal adsorption and filtration on the fluorine-containing mixed gas generated by electrolysis to obtain purified fluorine gas;
preparing chlorine trifluoride: adding the purified fluorine gas and high-purity chlorine gas into a reactor containing a catalyst, and reacting to obtain a chlorine trifluoride crude product;
purifying chlorine trifluoride: and liquefying, vaporizing, adsorbing and rectifying the chlorine trifluoride crude product to obtain high-purity chlorine trifluoride.
2. The method of producing chlorine trifluoride according to claim 1, wherein the temperature of the primary condensation in said step of purifying the fluorine gas is from-80 ℃ to-60 ℃, and the temperature of the secondary condensation is from-180 ℃ to-140 ℃.
3. The method of producing chlorine trifluoride according to claim 1, wherein the alkali metal in said step of purifying the fluorine gas is at least one of potassium fluoride and sodium fluoride.
4. The method of producing chlorine trifluoride according to claim 1, wherein the filtration in the step of purifying the fluorine gas is carried out by passing the fluorine-containing mixed gas through a polymer packing having a pore diameter of 2 to 5 μm at-180 to-150 ℃.
5. The method of claim 4, wherein the polymer filler in the step of purifying the fluorine gas is a hypercrosslinked polymer produced from benzene and aniline as raw materials, 1, 2-dibromoethane and dimethanol formaldehyde as crosslinking agents, and antimony pentachloride as a catalyst.
6. The method for producing chlorine trifluoride according to claim 1, wherein the catalyst used in the step of producing chlorine trifluoride is at least one of nickel fluoride and nitrogen fluoride, and the amount of the catalyst used is 2 to 5% of the total reaction system.
7. The method of producing chlorine trifluoride according to claim 1, wherein the reaction temperature in the step of producing chlorine trifluoride is 100 to 300 ℃, the gauge pressure is 0 ± 0.01Mpa, and the molar ratio of fluorine gas to chlorine gas is (3 to 4): 1.
8. the method of producing chlorine trifluoride according to claim 1, wherein the temperature of liquefaction in the step of purifying chlorine trifluoride is from-50 ℃ to-30 ℃ and the pressure is from 0 to 0.2 MPa.
9. The method for producing chlorine trifluoride according to claim 1, wherein the vaporization in the step of purifying chlorine trifluoride comprises a first stage vaporization and a second stage vaporization, the temperature of the first stage vaporization is 15 to 20 ℃, and the temperature of the second stage vaporization is 40 to 50 ℃.
10. The method for preparing chlorine trifluoride according to claim 1, wherein the rectification in the step of purifying chlorine trifluoride comprises a first-stage rectification and a second-stage rectification, the temperature of the first-stage rectification is 10-14 ℃, heavy component impurities are removed, and the overhead gas is subjected to the second-stage rectification at the temperature of 5-9 ℃ to remove light component impurities.
Technical Field
The invention relates to the technical field of chemical synthesis, in particular to a preparation method of chlorine trifluoride.
Background
Chlorine trifluoride is the most active halogen fluoride known in chemistry, and is a very powerful fluorinating agent. Chlorine trifluoride has a boiling point of 11.5 ℃ and is a gas which is easily condensed in a normal case, and the reaction can be carried out in any state of gas or liquid as required, which is not reached by a common fluorinating agent. Many metal oxides and chlorides react with chlorine trifluoride to form corresponding chlorides when heated, and by utilizing the characteristic of chlorine trifluoride, many important metal fluorides can be prepared, especially for separating and purifying rare elements. With the rapid development of semiconductor, liquid crystal, solar and LED industries, chlorine trifluoride is widely applied in the cleaning process of the CVD chamber, and the demand is increasing continuously, and chlorine trifluoride becomes one of the key special gases in the IC industry.
In the prior art, methods for preparing chlorine trifluoride are mainly classified into the following types: firstly, solid metal chloride (NaCl or CaCl)2) The raw material reacts with fluorine gas to generate chlorine gas and chlorine monofluoride, and the chlorine monofluoride further reacts with the fluorine gas to generate chlorine trifluoride. The method has the advantages of easily obtained raw materials and complex process operation, and has the disadvantages of gas-solid reaction, complex reactor structure, low raw material conversion rate, two-step reaction, two-time separation and purification process and complex process operation. And secondly, introducing the fluorine gas into liquid carbon tetrachloride or silicon tetrachloride, reacting to generate chlorine gas, and then further reacting the fluorine gas and the chlorine gas to generate chlorine trifluoride. The method has the disadvantages that raw materials are not easy to obtain, the reaction needs to be carried out in two steps, two reactors for gas-liquid and gas-gas reactions are involved, the process operation is complex, impurities in the crude product are too much, the purification is not favorable, and the industrial large-scale production is difficult. And thirdly, mixing chlorine gas, fluorine gas and diluent gas, introducing the mixture into a reactor filled with a catalyst, and preparing chlorine trifluoride at the temperature of (100-400 ℃) by using nickel fluoride and the like as the catalyst. The method has the advantages that the reaction is one-step catalytic synthesis, and has the disadvantages that the reaction needs to be added with a catalyst and the reaction pressure is higher. In summary, there are a large number of methods for the preparation of chlorine trifluoride, but the methods which are well established for industrial production are essentially only those in which elemental fluorine reacts directly with chlorine. The method can produce chlorine trifluoride with high impurity content, and contains more byproduct impurities ClF and ClO2F、F2And HF, etc. Because HF impurities in fluorine gas are high and the concentration of fluorine gas is low, generated CLF impurities are high, the yield of chlorine trifluoride products is influenced, particularly HF is difficult to deeply process, after chlorine trifluoride gas is rectified, the content of HF is 500-700 PPm at present, the concentration of chlorine trifluoride is only 99.9%, the high-purity quality requirement of the current microelectronic industry development cannot be met, and the technical index of high-purity chlorine trifluoride on HF cannot be met.
Disclosure of Invention
The object of the present invention is to provide a process for producing chlorine trifluoride, which enables chlorine trifluoride having a high purity to be produced.
The technical problem to be solved by the invention is realized by adopting the following technical scheme.
The embodiment of the application provides a preparation method of chlorine trifluoride, which comprises the following steps:
purification of fluorine gas: carrying out primary condensation, secondary condensation, alkali metal adsorption and filtration on the fluorine-containing mixed gas generated by electrolysis to obtain purified fluorine gas;
preparing chlorine trifluoride: adding the purified fluorine gas and high-purity chlorine gas into a reactor containing a catalyst, and reacting to obtain a chlorine trifluoride crude product;
purifying chlorine trifluoride: and liquefying, vaporizing, adsorbing and rectifying the chlorine trifluoride crude product to obtain high-purity chlorine trifluoride.
Compared with the prior art, the embodiment of the invention has at least the following advantages or beneficial effects:
according to the invention, the fluorine gas purification step can remove impurity gases such as hydrogen fluoride and carbon tetrafluoride generated by electrolysis, so that the fluorine gas with the purity of over 99.9% is obtained, the high-purity fluorine gas and the high-purity chlorine gas can be used for preparing chlorine tetrafluoride gas with higher content, the catalyst is added in the reaction process, so that the activation energy of the fluorine gas and the chlorine gas for generating chlorine monofluoride can be reduced, the generation temperature of the chlorine monofluoride is reduced, the generation rate of the chlorine monofluoride is accelerated, and the reaction of the chlorine monofluoride and the fluorine gas for generating chlorine trifluoride is taken as a rate control step, so that the rate of the fluorine gas and the chlorine gas for generating chlorine trifluoride is accelerated, the product yield is greatly improved, and the production capacity of the chlorine trifluoride and the safety in the production process can be improved. And liquefying the crude chlorine trifluoride product obtained by production to remove trace unreacted fluorine gas and non-condensable gas, vaporizing and adsorbing to remove trace acidic substances such as hydrogen fluoride impurities, and rectifying to obtain chlorine trifluoride with purity of more than 99.99%.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to specific examples.
A method for preparing chlorine trifluoride, comprising the steps of:
purification of fluorine gas: carrying out primary condensation, secondary condensation, alkali metal adsorption and filtration on the fluorine-containing mixed gas generated by electrolysis to obtain purified fluorine gas;
preparing chlorine trifluoride: adding the purified fluorine gas and high-purity chlorine gas into a reactor containing a catalyst, and reacting to obtain a chlorine trifluoride crude product;
purifying chlorine trifluoride: the chlorine trifluoride is liquefied, vaporized, adsorbed and rectified to obtain high-purity chlorine trifluoride.
The method comprises the steps of purifying fluorine gas to remove impurity gases such as hydrogen fluoride and carbon tetrafluoride generated by electrolysis so as to obtain the fluorine gas with the purity of more than 99.9 percent, preparing chlorine tetrafluoride gas with higher content from the fluorine gas with high purity and the chlorine gas with high purity, adding a catalyst in the reaction process to reduce the activation energy of the fluorine gas and the chlorine gas for generating chlorine monofluoride, further reducing the generation temperature of the chlorine monofluoride and quickening the generation rate of the chlorine monofluoride, and taking the reaction of the chlorine monofluoride and the fluorine gas for generating chlorine trifluoride as a rate control step, so that the rate of the chlorine trifluoride generated by the reaction of the chlorine monofluoride and the chlorine gas is quickened, the product yield is greatly improved, and the production capacity of the chlorine trifluoride and the safety in the production process can be improved. And liquefying the crude chlorine trifluoride product obtained by production to remove trace unreacted fluorine gas and non-condensable gas, vaporizing and adsorbing to remove trace acidic substances such as hydrogen fluoride impurities, and rectifying to obtain chlorine trifluoride with purity of more than 99.99%.
In some embodiments of the present invention, the temperature of the primary condensation in the step of purifying the fluorine gas is-80 to-60 ℃ and the temperature of the secondary condensation is-180 to-140 ℃. The liquid of primary condensation is liquid hydrogen fluoride, can carry out recycle after collecting, and the liquid behind the secondary condensation is carbon tetrafluoride, evacuates the back and carries out the vaporization, carries out evacuation processing after absorbing its inside hydrogen fluoride that mingles.
In some embodiments of the present invention, the alkali metal in the step of purifying the fluorine gas is at least one of potassium fluoride and sodium fluoride, and the alkali metal in the present invention is used for further removing hydrogen fluoride; in a preferred embodiment, the alkali metal in the present invention is specifically an alkali metal adsorption sphere having an internal skeleton structure, which can enhance the adsorption efficiency of the alkali metal, and can reduce the powdering rate of the alkali metal adsorption sphere after adsorbing hydrogen fluoride, thereby prolonging the service life of the alkali metal adsorption sphere. In addition, before the alkali metal is adsorbed, the alkali metal needs to be heated to 100-200 ℃ for activation so as to have certain porosity.
In some embodiments of the present invention, the filtering in the step of purifying the fluorine gas is performed by passing the fluorine-containing mixed gas through a polymer filler having a pore diameter of 2 to 5 μm at-180 to-150 ℃. The step is used for further removing carbon tetrafluoride in fluorine gas, and a cold source in the step is supplied by liquid nitrogen.
In some embodiments of the present invention, the polymer filler in the step of purifying the fluorine gas is a hypercrosslinked polymer produced by using benzene and aniline as raw materials, 1, 2-dibromoethane and dimethanol formaldehyde as crosslinking agents, and antimony pentachloride as a catalyst. The method comprises the following specific steps: mixing a mixture of 1: mixing 2-3 benzene and aniline as raw materials, adding 1, 2-dibromoethane, dimethanol formal and antimony pentachloride under the protection of nitrogen, uniformly mixing, heating to 80-100 ℃, and preserving heat for 18-20 hours; filtering to obtain a crude product, washing, purifying and drying to obtain the polymer filler. More specifically: in the preparation method of the high molecular filler, the ratio of the 1, 2-dibromoethane to the mole number of benzene rings in the raw materials is 1:1, the molar ratio of dimethyl formal to benzene ring in the raw material is 2:1, the ratio of antimony pentachloride to the mole number of benzene rings in the raw material is 1: 1. the dosage of the cross-linking agent and the catalyst in the preparation process of the high molecular filler has certain influence on the pore size. The invention utilizes the difference of the molecular particle sizes of fluorine gas and carbon tetrafluoride to prepare the polymer filler which can be separated from the fluorine gas, and the polymer filler is not corroded by the fluorine gas. The solid particles intercepted in the step can be returned to the electrolytic cell for recycling after being collected.
In some embodiments of the present invention, the catalyst used in the step of preparing chlorine trifluoride is at least one of nickel fluoride and nitrogen fluoride, and the amount of the catalyst is 2 to 5% of the total reaction system. The addition of small amounts of nickel fluoride and nitrogen fluoride may facilitate the overall reaction.
In some embodiments of the present invention, the reaction temperature in the step of preparing chlorine trifluoride is 100 to 300 ℃, the gauge pressure is 0 ± 0.01Mpa, and the molar ratio of fluorine gas to chlorine gas is (3 to 4): 1, the concentration of the chlorine gas is more than 99.99 percent.
In some embodiments of the present invention, the liquefaction temperature in the step of purifying chlorine trifluoride is-50 ℃ to-30 ℃ and the pressure is 0 to 0.2 MPa. If the liquefaction temperature is higher than-30 c, other impurity gases are not easily removed, and if the temperature is lower than-50 c, too low a temperature causes the fluidity of chlorine trifluoride to be lowered, which is disadvantageous to the operation of the entire production system.
In some embodiments of the present invention, the vaporization in the step of purifying chlorine trifluoride comprises a first stage vaporization and a second stage vaporization, wherein the temperature of the first stage vaporization is 15-20 ℃, and the temperature of the second stage vaporization is 40-50 ℃. The first-stage vaporization in the invention is rapid vaporization, and at the temperature rise, the chlorine trifluoride crude product not only has relatively faster vaporization speed, but also has reasonable saturated vapor pressure, and also ensures that the energy consumption for maintaining the temperature rise is lower, namely the vaporization speed, the saturated vapor pressure and the energy consumption of the chlorine trifluoride crude product reach good balance; the two-stage vaporization is used for equilibrium, wherein if the temperature of the two-stage vaporization is less than 40 ℃, the pressure of the chlorine trifluoride gas is not high enough to efficiently complete the subsequent process or even cannot complete the subsequent process, while if the temperature is more than 50 ℃, on the one hand, the energy consumption is increased, and on the other hand, the flow condition of the chlorine trifluoride gas in the subsequent process can be difficult to control, thereby affecting the purification process of the chlorine trifluoride gas.
In some embodiments of the invention, the adsorption step described above is used to remove trace amounts of other acidic impurities.
In some embodiments of the invention, the rectification in the step of purifying chlorine trifluoride comprises a first-stage rectification and a second-stage rectification, wherein the temperature of the first-stage rectification is 10-14 ℃, heavy component impurities are removed, and the overhead gas of the tower is subjected to the second-stage rectification, the temperature is 5-9 ℃, and light component impurities are removed.
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
A preparation method of chlorine trifluoride comprises the following steps of purifying chlorine, preparing chlorine trifluoride and purifying chlorine trifluoride, and specifically comprises the following steps of:
purification of fluorine gas: carrying out primary condensation on fluorine-containing mixed gas generated by electrolysis in a condenser at the temperature of-70 ℃, removing liquid hydrogen fluoride, then reducing the temperature to-160 ℃ for secondary condensation, removing liquid carbon tetrafluoride, then sending the gas into a reaction tower filled with alkali metal for adsorption, further removing hydrogen fluoride, and filtering the gas in a filter tower filled with polymer filler to obtain purified fluorine gas; in this example, the purity of the fluorine gas after purification was more than 99.99%. The alkali metal in this example was potassium fluoride and was activated at a high temperature of 150 ℃ for 10min before loading. The preparation method of the polymer filler in this embodiment is as follows: mixing a mixture of 1: 2, mixing benzene and aniline as raw materials, adding a crosslinking agent 1, 2-dibromoethane, dimethanol formal and a catalyst antimony pentachloride under the protection of nitrogen, uniformly mixing, heating to 80-100 ℃, preserving heat for 20 hours, generating a super-crosslinked polymer by a Friedel-crafts alkylation reaction, and filtering to obtain a crude product. Washing the crude product with ethanol until the filtrate is clear, and then drying in vacuum for 18 hours to obtain the polymer filler. Wherein the ratio of the mole number of the 1, 2-dibromoethane to the mole number of the benzene ring in the raw material is 1:1, the ratio of the mole number of the dimethanol formal to the mole number of the benzene ring in the raw material is 2:1, the ratio of the mole number of the antimony pentachloride to the mole number of the benzene ring in the raw material is 1:1, and the aperture of the polymer filler is 5 mu m.
Preparing chlorine trifluoride: adding the purified fluorine gas and high-purity chlorine gas with the purity of 99.99% into a reactor containing a catalyst, wherein the reaction temperature is 200 ℃, the surface pressure is 0.01MPa, and the molar ratio of the fluorine gas to the chlorine gas is 3: 1, obtaining a crude product of chlorine trifluoride by reaction, wherein the catalyst in the embodiment is nickel fluoride, and the using amount of the catalyst is 2 percent of the whole reaction system;
purifying chlorine trifluoride: the method comprises the steps of feeding a chlorine trifluoride crude product into a condenser to be liquefied at the temperature of minus 40 ℃ and the pressure of 0.1Mpa, removing other impurity gases, feeding the gas into a vaporizing device, rapidly heating to 18 ℃, slowly heating to 45 ℃ to be vaporized, feeding the vaporized chlorine trifluoride gas into an adsorbing device to be adsorbed, feeding the gas into a first-stage rectifying tower, feeding the gas into a second-stage rectifying tower from the top of the tower, removing heavy component impurities, feeding the gas into the first-stage rectifying tower at the temperature of 12 ℃, removing light component impurities, and obtaining chlorine trifluoride with the purity of more than 99.999%.
Example 2
A preparation method of chlorine trifluoride comprises the following steps of purifying chlorine, preparing chlorine trifluoride and purifying chlorine trifluoride, and specifically comprises the following steps of:
purification of fluorine gas: carrying out primary condensation on fluorine-containing mixed gas generated by electrolysis in a condenser at the temperature of minus 80 ℃, removing liquid hydrogen fluoride, then reducing the temperature to minus 180 ℃ for secondary condensation, removing liquid carbon tetrafluoride, then sending the gas into a reaction tower filled with alkali metal for adsorption, further removing the hydrogen fluoride, and filtering the gas in a filter tower filled with polymer filler to obtain purified fluorine gas; in this example, the purity of the fluorine gas after purification was more than 99.99%. The alkali metal in this example was potassium fluoride and was activated at a high temperature of 100 ℃ for 12min before loading. The preparation method of the polymer filler in this embodiment is as follows: mixing a mixture of 1: 3, mixing benzene and aniline as raw materials, adding a crosslinking agent 1, 2-dibromoethane, dimethanol formal and a catalyst antimony pentachloride under the protection of nitrogen, uniformly mixing, heating to 80-100 ℃, preserving heat for 18 hours, generating a super-crosslinked polymer by a Friedel-crafts alkylation reaction, and filtering to obtain a crude product. Washing the crude product with ethanol until the filtrate is clear, and then drying in vacuum for 18h to obtain the polymer filler. Wherein the ratio of the 1, 2-dibromoethane to the mole number of benzene rings in the raw material is 1:1, the molar ratio of dimethyl formal to benzene ring in the raw material is 2:1, the ratio of antimony pentachloride to the mole number of benzene rings in the raw material is 1:1, the pore diameter of the macromolecular filler is measured to be 5 mu m.
Preparing chlorine trifluoride: adding the purified fluorine gas and high-purity chlorine gas with the purity of 99.99% into a reactor containing a catalyst, wherein the reaction temperature is 300 ℃, the surface pressure is 0.005Mpa, and the molar ratio of the fluorine gas to the chlorine gas is 4: 1, obtaining a crude product of chlorine trifluoride by reaction, wherein the catalyst in the embodiment is nickel fluoride, and the using amount of the nickel fluoride is 3% of that of the whole reaction system;
purifying chlorine trifluoride: the method comprises the steps of feeding a chlorine trifluoride crude product into a condenser, liquefying at-50 ℃ and under the pressure of 0.2Mpa, removing other impurity gases, feeding the gas into a vaporizing device, rapidly heating to 15 ℃, slowly heating to 40 ℃ for vaporization, feeding the vaporized chlorine trifluoride gas into an adsorption device for adsorption, feeding the gas into a first-stage rectifying tower, wherein the temperature of the first-stage rectifying tower is 10 ℃, removing heavy component impurities, feeding the gas into a second-stage rectifying tower from the top of the tower, and removing light component impurities to obtain chlorine trifluoride with the purity of more than 99.999 percent, wherein the temperature of the second-stage rectifying tower is 8 ℃.
Example 3
A preparation method of chlorine trifluoride comprises the following steps of purifying chlorine, preparing chlorine trifluoride and purifying chlorine trifluoride, and specifically comprises the following steps of:
purification of fluorine gas: carrying out primary condensation on fluorine-containing mixed gas generated by electrolysis in a condenser at minus 60 ℃, removing liquid hydrogen fluoride, then reducing the temperature to minus 160 ℃ for secondary condensation, removing liquid carbon tetrafluoride, then sending the gas into a reaction tower filled with alkali metal for adsorption, further removing the hydrogen fluoride, and filtering the gas in a filter tower filled with polymer filler to obtain purified fluorine gas; in this example, the purity of the fluorine gas after purification was more than 99.99%. The alkali metal in this example was potassium fluoride and was activated at a high temperature of 200 ℃ for 10min before loading. The preparation method of the polymer filler in this embodiment is as follows: mixing a mixture of 1: 2, mixing benzene and aniline as raw materials, adding a crosslinking agent 1, 2-dibromoethane, dimethanol formal and a catalyst antimony pentachloride under the protection of nitrogen, uniformly mixing, heating to 80-100 ℃, preserving heat for 19 hours, generating a super-crosslinked polymer by a Friedel-crafts alkylation reaction, and filtering to obtain a crude product. Washing the crude product with ethanol until the filtrate is clear, and then drying in vacuum for 18 hours to obtain the polymer filler. Wherein the ratio of the mole number of the 1, 2-dibromoethane to the mole number of the benzene ring in the raw material is 1:1, the ratio of the mole number of the dimethanol formal to the mole number of the benzene ring in the raw material is 2:1, the ratio of the mole number of the antimony pentachloride to the mole number of the benzene ring in the raw material is 1:1, and the aperture of the polymer filler is 5 mu m.
Preparing chlorine trifluoride: adding the purified fluorine gas and high-purity chlorine gas with the purity of 99.99% into a reactor containing a catalyst, wherein the reaction temperature is 100 ℃, the surface pressure is 0.01MPa, and the molar ratio of the fluorine gas to the chlorine gas is 4: 1, obtaining a crude product of chlorine trifluoride by reaction, wherein the catalyst in the embodiment is nickel fluoride, and the using amount of the catalyst is 2 percent of the whole reaction system;
purifying chlorine trifluoride: the method comprises the steps of feeding a chlorine trifluoride crude product into a condenser, liquefying at-40 ℃ and under the pressure of 0.1Mpa, removing other impurity gases, feeding the gas into a vaporizing device, rapidly heating to 18 ℃, slowly heating to 45 ℃ for vaporization, feeding the vaporized chlorine trifluoride gas into an adsorption device for adsorption, feeding the gas into a first-stage rectifying tower, wherein the temperature of the first-stage rectifying tower is 14 ℃, removing heavy component impurities, feeding the gas into a second-stage rectifying tower from the top of the tower, and removing light component impurities to obtain chlorine trifluoride with the purity of more than 99.99%.
Example 4
A preparation method of chlorine trifluoride comprises the following steps of purifying chlorine, preparing chlorine trifluoride and purifying chlorine trifluoride, and specifically comprises the following steps of:
purification of fluorine gas: carrying out primary condensation on fluorine-containing mixed gas generated by electrolysis in a condenser at the temperature of-75 ℃, removing liquid hydrogen fluoride, then reducing the temperature to-140 ℃ for secondary condensation, removing liquid carbon tetrafluoride, then sending the gas into a reaction tower filled with alkali metal for adsorption, further removing hydrogen fluoride, and filtering the gas in a filter tower filled with polymer filler to obtain purified fluorine gas; in this example, the purity of the fluorine gas after purification was more than 99.99%. The alkali metal in this example was potassium fluoride and was activated at a high temperature of 150 ℃ for 10min before loading. The preparation method of the polymer filler in this embodiment is as follows: mixing a mixture of 1: 2, mixing benzene and aniline as raw materials, adding a crosslinking agent 1, 2-dibromoethane, dimethanol formal and a catalyst antimony pentachloride under the protection of nitrogen, uniformly mixing, heating to 80-100 ℃, preserving heat for 20 hours, generating a super-crosslinked polymer by a Friedel-crafts alkylation reaction, and filtering to obtain a crude product. Washing the crude product with ethanol until the filtrate is clear, and then drying in vacuum for 18h to obtain the polymer filler. Wherein the ratio of the mole number of the 1, 2-dibromoethane to the mole number of the benzene ring in the raw material is 1:1, the ratio of the mole number of the dimethanol formal to the mole number of the benzene ring in the raw material is 2:1, the ratio of the mole number of the antimony pentachloride to the mole number of the benzene ring in the raw material is 1:1, and the aperture of the polymer filler is 3 mu m.
Preparing chlorine trifluoride: adding the purified fluorine gas and high-purity chlorine gas with the purity of 99.99% into a reactor containing a catalyst, wherein the reaction temperature is 200 ℃, the surface pressure is 0.01MPa, and the molar ratio of the fluorine gas to the chlorine gas is 3: 1, obtaining a crude product of chlorine trifluoride by reaction, wherein the catalyst in the embodiment is nickel fluoride, and the using amount of the catalyst is 2 percent of the whole reaction system;
purifying chlorine trifluoride: the method comprises the steps of feeding a chlorine trifluoride crude product into a condenser, liquefying at-40 ℃ and under the pressure of 0.1Mpa, removing other impurity gases, feeding the gas into a vaporizing device, rapidly heating to 18 ℃, slowly heating to 45 ℃ for vaporization, feeding the vaporized chlorine trifluoride gas into an adsorption device for adsorption, feeding the gas into a first-stage rectifying tower, wherein the temperature of the first-stage rectifying tower is 12 ℃, removing heavy component impurities, feeding the gas into a second-stage rectifying tower from the top of the tower, and removing light component impurities to obtain chlorine trifluoride with the purity of more than 99.99%.
Comparative example 1
In the comparative example, the fluorine gas purification step was omitted, that is, the fluorine-containing mixed gas generated by electrolysis was directly reacted with a high-purity chlorine gas to obtain a chlorine trifluoride mixed gas, and the chlorine trifluoride mixed gas was purified, wherein the steps and processes for preparing chlorine trifluoride and purifying chlorine trifluoride were the same as in example 1, and the final yield of chlorine trifluoride was 85.9% and the purity was 98.2%.
Comparative example 2
In the step of purifying fluorine gas in the comparative example, the step of adsorbing no alkali metal, that is, directly reacting the electrolyzed fluorine gas mixture with high-purity chlorine gas after primary condensation, secondary condensation and filtration in sequence, and then purifying, wherein the steps and processes of preparing chlorine trifluoride and purifying chlorine trifluoride are the same as those of example 1, and the yield of chlorine trifluoride is 89.3% and the purity is 99.4%.
Comparative example 3
This comparative example differs from example 1 in that the fluorine gas purification step of this comparative example employs filtration through ordinary filtration pores, and only the fixed matters and impurities are filtered, and the purity of the final chlorine trifluoride is 99.53%.
In summary, the embodiments of the present invention provide a method for preparing chlorine trifluoride, in which the step of purifying fluorine gas can remove impurity gases such as hydrogen fluoride and carbon tetrafluoride generated by electrolysis, thereby obtaining fluorine gas with the purity of more than 99.9 percent, preparing chlorine tetrafluoride gas with higher content by using the fluorine gas with high purity and chlorine gas with high purity, the activation energy for generating the chlorine monofluoride by the reaction of the fluorine gas and the chlorine gas can be reduced by adding the catalyst in the reaction process, further, the temperature for generating chlorine monofluoride is lowered, the rate of generating chlorine monofluoride is increased, and the reaction of chlorine monofluoride with fluorine gas to generate chlorine trifluoride is used as a rate control step, therefore, the speed of the reaction of the fluorine gas and the chlorine gas to generate the chlorine trifluoride is accelerated, the product yield is greatly improved, and the production capacity and the safety in the production process of the chlorine trifluoride can be improved. And liquefying the crude chlorine trifluoride product obtained by production to remove trace unreacted fluorine gas and non-condensable gas, vaporizing and adsorbing to remove trace acidic substances such as hydrogen fluoride impurities, and rectifying to obtain chlorine trifluoride with purity of more than 99.99%.
The embodiments described above are some, but not all embodiments of the invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.