阅读说明：本技术 一种制备三氟化氯的方法 (Method for preparing chlorine trifluoride ) 是由 丁勇 张堃 梁战军 汤鲲彪 陈功俊 赵彬 于 2020-12-29 设计创作，主要内容包括：本发明属于无机氟化工技术领域,具体涉及一种制备三氟化氯的方法,包括：将氟气和氯气分别预热后,充分混合后,常压下进行反应,得到三氟化氯混合气体；将三氟化氯混合气体进行冷凝,得到三氟化氯粗品；将三氟化氯粗品进行精馏提纯、冷凝,得到三氟化氯产品。本发明方法能够在无催化剂常压条件下一步制备获得三氟化氯,工艺操作简单,反应时间短,温度和压力易于控制、反应过程安全,可实现工业化生产。(The invention belongs to the technical field of inorganic fluorine chemical industry, and particularly relates to a method for preparing chlorine trifluoride, which comprises the following steps: respectively preheating fluorine gas and chlorine gas, fully mixing, and reacting at normal pressure to obtain chlorine trifluoride mixed gas; condensing the chlorine trifluoride mixed gas to obtain a chlorine trifluoride crude product; and (3) rectifying, purifying and condensing the chlorine trifluoride crude product to obtain a chlorine trifluoride product. The method can prepare chlorine trifluoride at normal pressure without a catalyst by one step, has the advantages of simple process operation, short reaction time, easy control of temperature and pressure, safe reaction process and realization of industrial production.)

1. A process for preparing chlorine trifluoride, comprising:

respectively preheating fluorine gas and chlorine gas, fully mixing, and reacting at normal pressure to obtain chlorine trifluoride mixed gas;

condensing the chlorine trifluoride mixed gas to obtain a chlorine trifluoride crude product;

and (3) rectifying, purifying and condensing the chlorine trifluoride crude product to obtain a chlorine trifluoride product.

2. The method of claim 1, wherein the purity of fluorine gas in step (1) is more than 98% and the purity of chlorine gas in step (1) is more than 99.9%.

3. The method of claim 1, wherein the molar ratio of fluorine gas to chlorine gas in the step (1) is not less than 3: 1.

4. The method of claim 1, wherein the preheating temperature of fluorine gas in step (1) is 100 to 200 ℃ and the preheating temperature of chlorine gas is 100 to 200 ℃.

5. The method for preparing chlorine trifluoride according to claim 1, wherein the reaction temperature in step (1) is 250 to 350 ℃ and the gauge pressure is 0 ± 0.01 MPa.

6. The method for preparing chlorine trifluoride according to claim 1, wherein the step (2) is specifically: and condensing the chlorine trifluoride mixed gas, wherein the liquid obtained by condensation is a crude product of chlorine trifluoride, and the non-condensable gas is discharged after being treated by a tail gas purification system.

7. The method for preparing chlorine trifluoride according to claim 1, wherein the condensation temperature in the step (2) is-35 to-20 ℃.

8. The method for preparing chlorine trifluoride according to claim 1, wherein the temperature of the bottom of the rectifying tower in the rectifying and purifying process in step (3) is 12-15 ℃, the temperature of the top of the rectifying tower is 6-9 ℃, and the reflux ratio is 25-50.

Technical Field

The invention belongs to the technical field of inorganic fluorine chemical industry, and particularly relates to a method for preparing chlorine trifluoride.

Background

Chlorine trifluoride is colorless corrosive gas or light yellow liquid with density of 1.825g/cm³Melting point-76.34, boiling point 11.75 ℃. Easily dissolved in anhydrous hydrogen fluoride, carbon tetrachloride and the like. Chlorine trifluoride is a strong oxidant, has high chemical reaction activity and flammable characteristic, can perform explosive reaction with water and organic compounds, and belongs to dangerous chemicals.

In recent years, with the rapid development of semiconductor, liquid crystal, solar and LED industries, chlorine trifluoride has been widely used in the CVD (chemical vapor deposition) cleaning process, and the demand is on the rise, and chlorine trifluoride has become one of the key special gases in the IC industry. High-purity chlorine trifluoride is used as an electron gas, has a chemical activity which is inclined toward fluorine gas, but is milder than fluorine gas, is more environmentally friendly than fluorocarbon electron gas, has a GWP (global warming potential) of zero, and is considered as an LPCVD (low pressure chemical vapor deposition) cleaning gas. In the semiconductor industry, LPCVD processes are used to form polysilicon films and SiN films, and high purity chlorine trifluoride is mainly used as a CVD cleaning gas, which has significant advantages in cleaning quality, efficiency, and reduction of greenhouse effect.

The chlorine trifluoride has active chemical property, strong oxidability and high chemical reaction activity, and has strict requirements on production process condition control and equipment materials, so that the large-scale production and application of the chlorine trifluoride are limited. The preparation method of chlorine trifluoride is firstly proposed in 1930 by Ruff (Ruff) and kruk (Krug), fluorine gas and chlorine gas react to generate chlorine monofluoride firstly, the chlorine monofluoride further reacts with the fluorine gas to generate chlorine trifluoride, and the reaction is carried out in two steps and needs to be subjected to two purification and separation processes. When the method is used for synthesizing the chlorine trifluoride, the reaction efficiency is low, and the method is not suitable for industrial production.

In the prior art, methods for preparing chlorine trifluoride are mainly classified into the following types:

(1) with 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.

(2) And 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.

(3) And 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, the currently known chlorine trifluoride preparation methods are mainly gas-solid reaction, gas-liquid reaction, gas-gas catalytic synthesis reaction and the like, and have the advantages of high reaction temperature and reaction pressure, complex process, high requirements on corrosion resistance and high temperature resistance of equipment, difficulty in controlling the process, influence on the safety and yield of chlorine trifluoride preparation, and difficulty in industrial large-scale production.

Therefore, it is urgently needed to develop a new method for preparing chlorine trifluoride, which can effectively overcome various defects in the prior art, and can realize industrial large-scale production on the premise of ensuring the safety and yield of the preparation of chlorine trifluoride.

Disclosure of Invention

The invention aims to overcome the defects of the chlorine trifluoride preparation method in the prior art, and provides a method for preparing chlorine trifluoride, which can prepare chlorine trifluoride in one step under the condition of no catalyst and normal pressure, has the advantages of simple process operation, short reaction time, easy control of temperature and pressure, safe reaction process and capability of realizing industrial production.

The technical scheme for realizing the purpose of the invention is as follows: a process for preparing chlorine trifluoride, the process comprising:

respectively preheating fluorine gas and chlorine gas, fully mixing, and reacting at normal pressure to obtain chlorine trifluoride mixed gas;

condensing the chlorine trifluoride mixed gas to obtain a chlorine trifluoride crude product;

and (3) rectifying, purifying and condensing the chlorine trifluoride crude product to obtain a chlorine trifluoride product.

Further, in the step (1), the purity of the fluorine gas is more than 98%, and the purity of the chlorine gas is more than 99.9%.

Further, the molar ratio of fluorine gas to chlorine gas in the step (1) is not less than 3: 1.

Further, the preheating temperature of the fluorine gas in the step (1) is 100 to 200 ℃ and the preheating temperature of the chlorine gas is 100 to 200 ℃.

Further, the reaction temperature in the step (1) is 250-350 ℃, and the surface pressure is 0-0.01 MPa.

Further, the step (2) is specifically: and condensing the chlorine trifluoride mixed gas, wherein the liquid obtained by condensation is a crude product of chlorine trifluoride, and the non-condensable gas is discharged after being treated by a tail gas purification system.

Further, the condensation temperature in the step (2) is-35 to-20 ℃.

Further, in the step (3), the temperature of a tower kettle of the rectifying tower is 12-15 ℃, the temperature of a tower top is 6-9 ℃ and the reflux ratio is 25-50 in the rectifying and purifying process.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the method for preparing chlorine trifluoride provided by the invention, fluorine gas and chlorine gas are preheated before entering the reactor, so that the reaction activity is enhanced; the fluorine gas and the chlorine gas enter the reactor, are mixed in the mixing chamber and then react, so that the fluorine gas and the chlorine gas are fully contacted, and the contact time of the fluorine gas and the chlorine gas in the reactor is prolonged, so that the method does not need to add a catalyst, can prepare chlorine trifluoride by one step under the normal pressure condition, and is simple in process operation;

2. the method for preparing chlorine trifluoride provided by the invention simplifies the production process of chlorine trifluoride, and has few byproducts; the purity of the crude chlorine trifluoride is more than 93 percent, and the yield is more than 80 percent; the purity of the chlorine trifluoride product is more than 99 percent. The yield is more than 85%.

3. The method for preparing chlorine trifluoride provided by the invention has the advantages of short reaction time, easy control of temperature and pressure, continuous and safe reaction process and suitability for large-scale industrial production.

Detailed Description

The present invention will be described in further detail with reference to specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

The method for preparing chlorine trifluoride at normal pressure by one step without catalyst comprises the following specific steps:

purging a system by using nitrogen, adopting fluorine gas with the purity of 98.5% and chlorine gas with the purity of 99.9%, wherein the molar ratio of the fluorine gas to the chlorine gas is 3:1, preheating the fluorine gas to 100 ℃ and preheating the chlorine gas to 100 ℃; and (3) the preheated fluorine gas and chlorine gas enter a mixing chamber of the reactor to be mixed, and then enter the reactor to react at the temperature of 250 ℃ and the pressure of 0MPa (gauge pressure) to obtain chlorine trifluoride mixed gas.

Step (2), the chlorine trifluoride mixed gas enters a condenser, and is condensed at the temperature of minus 35 ℃ to obtain a condensed liquid, namely a chlorine trifluoride crude product; after condensation, non-condensable low-boiling gaseous impurities, e.g. ClF, ClO₂F、F₂And (5) conveying the gas to a tail gas purification system through a gas phase outlet pipeline, and emptying the gas after purification treatment. The crude chlorine trifluoride freed of most of the low-boiling gaseous impurities had a purity of 94.2% and a yield of 84.6%.

Step (3), introducing the crude chlorine trifluoride product into a rectifying tower for rectification and purification, heating a tower kettle to 12 ℃, carrying out total reflux for 2 hours, controlling the reflux ratio to be 25 when the temperature of the tower kettle is stabilized at 12-13 ℃ and the temperature of the tower top is stabilized at 7-8 ℃, taking a product at the tower top when the gas phase purity at the tower top is more than 99.0%, carrying out condensation at-20 ℃, and filling and storing after condensation to obtain a chlorine trifluoride product; when the temperature of the tower kettle is higher than 15 ℃, the rectification is stopped. The final chlorine trifluoride product was obtained in 99% purity and 85.5% yield.

Example 2

The method for preparing chlorine trifluoride at normal pressure by one step without catalyst comprises the following specific steps:

purging the system by using nitrogen, adopting fluorine gas with the purity of 98.8% and chlorine gas with the purity of 99.95%, wherein the molar ratio of the fluorine gas to the chlorine gas is 3.2:1, preheating the fluorine gas to 160 ℃, and preheating the chlorine gas to 160 ℃; and (3) the preheated fluorine gas and chlorine gas enter a mixing chamber of the reactor to be mixed, and then enter the reactor to react at the temperature of 320 ℃ and the pressure of 0.008MPa (gauge pressure) to obtain chlorine trifluoride mixed gas.

Step (2), the chlorine trifluoride mixed gas enters a condenser, and is condensed at the temperature of minus 25 ℃, so that condensed liquid, namely a chlorine trifluoride crude product, is obtained; after condensation, low-boiling gaseous impurities, e.g. ClF, ClO₂F、F₂And (5) conveying the gas to a tail gas purification system through a gas phase outlet pipeline, and emptying the gas after purification treatment. The crude chlorine trifluoride freed of most of the low-boiling gaseous impurities had a purity of 93.5% and a yield of 85.0%.

Step (3), introducing the crude chlorine trifluoride product into a rectifying tower for rectification and purification, heating a tower kettle to 13 ℃, carrying out total reflux for 2.5 hours, controlling the reflux ratio to be 40 when the temperature of the tower kettle is stabilized at 13-14 ℃ and the temperature of the tower top is stabilized at 8-9 ℃, taking a product at the tower top when the purity of a gas phase at the tower top is more than 99%, carrying out condensation at-20 ℃, and filling and storing after condensation to obtain a chlorine trifluoride product; when the temperature of the tower kettle is higher than 15 ℃, the rectification is stopped. The final chlorine trifluoride product was obtained in 99.2% purity and 88% yield.

Example 3

The method for preparing chlorine trifluoride at normal pressure by one step without catalyst comprises the following specific steps:

purging a system by using nitrogen, adopting fluorine gas with the purity of 99% and chlorine gas with the purity of 99.99%, wherein the molar ratio of the fluorine gas to the chlorine gas is 3.5:1, preheating the fluorine gas to 200 ℃ and preheating the chlorine gas to 200 ℃; and (3) the preheated fluorine gas and chlorine gas enter a mixing chamber of the reactor to be mixed, and then enter the reactor to react at the temperature of 350 ℃ and the pressure of 0.01MPa (gauge pressure) to obtain chlorine trifluoride mixed gas.

Step (2), the chlorine trifluoride mixed gas enters a condenser, and is condensed at the temperature of minus 20 ℃ to obtain a condensed liquid, namely a chlorine trifluoride crude product; after condensation, low-boiling gaseous impurities, e.g. ClF, ClO₂F、F₂And (5) conveying the gas to a tail gas purification system through a gas phase outlet pipeline, and emptying the gas after purification treatment. The crude chlorine trifluoride freed of most of the low-boiling gaseous impurities had a purity of 93% and a yield of 86%.

Step (3), introducing the crude chlorine trifluoride product into a rectifying tower for rectification and purification, heating a tower kettle to 14 ℃, carrying out total reflux for 3 hours, controlling the reflux ratio to be 50 when the temperature of the tower kettle is stabilized at 14-15 ℃ and the temperature of the tower top is stabilized at 9-10 ℃, taking a product at the tower top when the gas phase purity at the tower top is more than 99%, carrying out condensation at-20 ℃, and filling and storing after condensation to obtain a chlorine trifluoride product; when the temperature of the tower kettle is higher than 15 ℃, the rectification is stopped. The final chlorine trifluoride product was obtained in a purity of 99.1% and a yield of 86%.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.