A method for preparing phosphorus trifluoride by reacting nitrogen trifluoride with phosphorus under the initiation of ultraviolet light
High-purity phosphorus trifluoride is prepared by initiating the reaction between nitrogen trifluoride and phosphorus with ultraviolet light. This method solves the problems of high raw material hazard, demanding equipment requirements, and complex product separation in existing technologies, and achieves a safe, easy-to-control, and efficient preparation process with high product purity, which is suitable for fields such as semiconductors and organic synthesis.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FUJIAN ELEGANT CREATION ELECTRONIC CHEM CORP
- Filing Date
- 2026-03-16
- Publication Date
- 2026-06-12
AI Technical Summary
Existing methods for preparing phosphorus trifluoride involve highly hazardous raw materials, demanding equipment requirements, and complex product separation, making it difficult to achieve high purity and high efficiency.
Phosphorus trifluoride was prepared by reacting nitrogen trifluoride with elemental phosphorus under ultraviolet light irradiation. The reaction between nitrogen trifluoride and phosphorus was initiated by ultraviolet light with a wavelength of 200-300 nm in a closed, corrosion-resistant reactor. The main products were phosphorus trifluoride and nitrogen gas, with a small amount of phosphorus tetrafluoride as a byproduct. High-purity phosphorus trifluoride was obtained by purifying the product through a solvent-free gas-solid phase reaction system and by condensation and distillation.
It achieves high safety, easy control of reaction conditions, high product selectivity, simple subsequent separation, and high purity of prepared phosphorus trifluoride, which is suitable for semiconductor industry and organic synthesis.
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Figure CN122186969A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of materials preparation technology, specifically to a method for preparing phosphorus trifluoride by initiating the reaction of nitrogen trifluoride with phosphorus using ultraviolet light. Background Technology
[0002] Phosphorus trifluoride (PF3), as an important inorganic fluoride, possesses strong coordination and fluorinating properties. It is widely used in fields such as dry etching in the semiconductor industry, fluorinating agents in organic synthesis, and the preparation of metal coordination compounds, including: 1. Semiconductors and Microelectronics (Core Applications): As a phosphorus source for ion implantation, it precisely alters the conductivity of materials such as silicon, making it a key material for advanced processes; it can also react with metals such as tungsten and molybdenum to generate volatile fluorides, enabling fine etching of wafer metal wiring; in addition, it is used to prepare semiconductor-related intermediates such as high-purity phosphorus oxyfluoride. 2. Organic Synthesis: As a fluorinating agent, it introduces fluorine atoms into organic molecules, and is used to synthesize fine chemicals such as fluorinated pesticides, dyes, and pharmaceuticals; at the same time, it participates in the synthesis of various fluorinated compounds as a key precursor. 3. Metal complexation and catalysis: As a strong π-acceptor ligand, it forms stable complexes with low oxidation state transition metals (such as Ni(PF3)4 and Pd(PF3)4). Some of these complexes are more stable than carbonyl analogs and are used in catalysis and materials research. In coordination chemistry research, it serves as a model ligand to explore metal-ligand interaction mechanisms and support the development of novel catalysts. 4. Precious metal smelting: As a purification reagent, it reacts with impurities in precious metals to form volatile fluorides, thereby separating them from the precious metals and improving the purity of gold, silver, etc. 5. Other applications: used for spectral analysis and quantitative detection of specific elements; involved in the synthesis of lithium-ion battery electrolytes to improve battery performance (such as cycle stability and energy density).
[0003] In existing technologies, phosphorus trifluoride is typically prepared by reacting phosphorus trichloride with anhydrous hydrogen fluoride in the liquid phase via a fluorination reaction (such as the electronic-grade phosphorus trifluoride preparation method disclosed in patent CN117228643A). However, this method requires the use of highly corrosive anhydrous hydrogen fluoride, placing high demands on the corrosion resistance of the reaction equipment. Furthermore, the reaction generates hydrogen chloride as a byproduct, complicating subsequent separation and purification processes and increasing overall production costs.
[0004] In addition, some studies have attempted to synthesize phosphorus fluorides by directly reacting fluorine gas with elemental phosphorus. However, fluorine gas is chemically highly reactive, the reaction process is violent and difficult to control, posing an explosion risk and poor safety. At the same time, the reaction easily generates highly fluorinated byproducts such as phosphorus pentafluoride, resulting in low selectivity for phosphorus trifluoride and making it difficult to meet the requirements for high-purity preparation.
[0005] To address the shortcomings of the aforementioned methods, researchers are exploring other synthetic routes to achieve safer, more efficient, and higher-purity phosphorus trifluoride preparation. Nitrogen trifluoride (NF3), as a mild fluorinating agent with good stability and low corrosivity, has been widely used in semiconductor etching and fluorination reactions. However, to date, there are no reports on technologies for preparing phosphorus trifluoride by reacting nitrogen trifluoride with elemental phosphorus under ultraviolet irradiation. Summary of the Invention
[0006] The purpose of this invention is to overcome the shortcomings of existing methods for preparing phosphorus trifluoride, such as high raw material hazards, demanding equipment requirements, and complex product separation. This invention provides a method for preparing phosphorus trifluoride by initiating the reaction of nitrogen trifluoride and phosphorus with ultraviolet light. This method uses nitrogen trifluoride and elemental phosphorus as raw materials, and initiates the reaction by ultraviolet light irradiation. It has the advantages of mild raw materials, easy control of reaction conditions, high product selectivity, and good safety.
[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing phosphorus trifluoride by initiating the reaction of nitrogen trifluoride and phosphorus with ultraviolet light, using nitrogen trifluoride (NF3) and elemental phosphorus (P) as raw materials, in a closed corrosion-resistant photochemical reactor, the decomposition reaction of nitrogen trifluoride is initiated by ultraviolet light with a wavelength of 200~300nm, to produce phosphorus trifluoride (PF3) and nitrogen (N2) as the main products, with a small amount of phosphorus tetrafluoride (P2F4) as a byproduct. The reaction equation is as follows: .
[0008] Furthermore, the elemental phosphorus is either red phosphorus or white phosphorus, preferably red phosphorus. Compared to white phosphorus, red phosphorus is more stable, less prone to spontaneous combustion, and has better reaction safety. The particle size of red phosphorus is 50-200 mesh. The smaller particle size can increase the contact area with nitrogen trifluoride gas, thereby improving the reaction rate and conversion rate.
[0009] Furthermore, the molar ratio of nitrogen trifluoride to elemental phosphorus is 1:1 to 2, with a slight excess of elemental phosphorus to ensure that nitrogen trifluoride reacts fully.
[0010] Furthermore, the ultraviolet light source used for ultraviolet irradiation has a wavelength of 200–300 nm. The energy of ultraviolet light in this wavelength range is sufficient to break the NF bond in nitrogen trifluoride (bond energy of approximately 276 kJ / mol), generating fluorine free radicals and initiating a reaction with elemental phosphorus. The power of the ultraviolet light source is 50–500 W, the irradiation distance is 5–30 cm, and the irradiation reaction time is 2–10 h. The power of the light source and the irradiation time can be adjusted according to the reaction scale to ensure that the reaction proceeds fully.
[0011] Furthermore, the gas-solid phase photocatalytic reaction is carried out at atmospheric pressure or slightly positive pressure (0.1–0.3 MPa) and at room temperature, eliminating the need for high-pressure equipment, thus reducing equipment costs and operational risks. The reaction system is a solvent-free gas-solid phase reaction, avoiding solvent contamination of the product and subsequent solvent separation steps.
[0012] Furthermore, it also includes introducing argon or nitrogen gas into the corrosion-resistant photochemical reactor before the reaction to remove oxygen, prevent elemental phosphorus from being oxidized, and ensure the selectivity of the reaction.
[0013] Furthermore, the photocatalytic reaction is carried out in a reactor made of polytetrafluoroethylene or Hastelloy, which is resistant to corrosion by fluorides. The reactor is equipped with a quartz glass ultraviolet light transmission window to ensure that ultraviolet light can pass through and irradiate the reaction system. It is also equipped with a raw material inlet, a product outlet and a temperature monitoring port to facilitate the introduction of raw materials, collection of products and monitoring of reaction temperature.
[0014] Furthermore, the reaction product is purified by condensation and distillation to obtain high-purity phosphorus trifluoride. The condensation temperature is -80 to -40°C, which can condense and separate easily condensable impurities such as phosphorus tetrafluoride in the product. The distillation is carried out in a packed column with a distillation temperature of -60 to -20°C and a vacuum degree of 0.08 to 0.098 MPa to further remove light component impurities such as nitrogen, so as to obtain electronic-grade phosphorus trifluoride with a purity of ≥99.9%, which can meet the application requirements of the semiconductor industry.
[0015] After the reaction was completed, GC-MS analysis showed that the selectivity of phosphorus trifluoride was ≥90% and the conversion rate of nitrogen trifluoride was ≥85%, indicating high reaction efficiency, few byproducts, and simple subsequent separation and purification.
[0016] Compared with the prior art, the technical solution of this application has the following beneficial effects: 1. Regarding the selection of raw materials, this invention uses nitrogen trifluoride and elemental phosphorus as raw materials, avoiding the use of highly corrosive and hazardous raw materials commonly found in traditional processes, such as anhydrous hydrogen fluoride and fluorine gas. Because nitrogen trifluoride itself is mild and has low corrosivity, it not only significantly improves the safety of the operation process but also greatly reduces the corrosion resistance requirements of the reaction equipment, thereby effectively reducing equipment investment and subsequent maintenance costs. 2. Regarding reaction conditions, this invention utilizes ultraviolet light to initiate a gas-solid phase reaction, which can be carried out smoothly at room temperature and under normal or slightly positive pressure conditions, without the need for high-temperature and high-pressure reaction equipment. The reaction conditions are mild and the process is easy to control, which not only reduces energy consumption but also provides convenient conditions for large-scale industrial production. 3. Regarding product separation and purification, this invention employs a solvent-free gas-solid phase reaction system, effectively avoiding solvent contamination and subsequent solvent separation processes. The main product is phosphorus trifluoride, and the byproducts are mainly nitrogen and a small amount of phosphorus tetrafluoride, exhibiting high product selectivity. Subsequent steps only require condensation to remove phosphorus tetrafluoride, followed by distillation to remove nitrogen and other light components, yielding high-purity phosphorus trifluoride. The separation process is simple and cost-effective. 4. The phosphorus trifluoride product prepared by this invention has high purity and low impurity content, which can meet the requirements of electronic-grade applications. It can be widely used in ion implantation and low-temperature etching in the semiconductor industry, preparation of fluorinating agents in organic synthesis, and synthesis of transition metal coordination compounds, and has excellent promotion and application value. Attached Figure Description
[0017] Figure 1 This is the fluorine spectrum of phosphorus trifluoride in Example 1 of the present invention. Detailed Implementation
[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.
[0019] Example 1 A method for preparing phosphorus trifluoride by initiating the reaction of nitrogen trifluoride and phosphorus with ultraviolet light, using nitrogen trifluoride (NF3) and elemental phosphorus (P) as raw materials, involves initiating the decomposition reaction of nitrogen trifluoride by irradiation with ultraviolet light at a wavelength of 200-300 nm in a closed, corrosion-resistant photochemical reactor, producing phosphorus trifluoride (PF3) and nitrogen (N2) as the main products, with a small amount of phosphorus tetrafluoride (P2F4) as a byproduct. The reaction equation is as follows: ; The specific steps are as follows: S1. Reactor preparation: A corrosion-resistant photochemical reactor made of polytetrafluoroethylene is used. The reactor is equipped with a quartz glass transmission window. The reactor is purged with argon gas three times to remove all oxygen. S2. Raw material addition: Add 8.4g (0.27mol) of red phosphorus with a particle size of 100 mesh to the reactor and seal the reactor; S3. Raw material introduction: Nitrogen trifluoride gas is introduced into the reactor through the raw material inlet, and the molar ratio of nitrogen trifluoride to red phosphorus is controlled at 1:1.2, and the pressure inside the reactor is maintained at 0.1MPa; S4. Ultraviolet light irradiation: Turn on the 254nm wavelength ultraviolet light source, the light source power is 200W, the light irradiation distance is 15cm, the light reaction is carried out for 6h, the temperature inside the reactor is monitored during the reaction, and the temperature is kept at room temperature. S5. Product collection: After the reaction is completed, the reaction product is collected from the product outlet and condensed in a condenser at -60℃ to remove a small amount of easily condensable impurities such as phosphorus tetrafluoride. S6. Distillation and purification: The condensed product is passed into a packed tower for distillation at a temperature of -40℃ and a vacuum of 0.09MPa to remove light component impurities such as nitrogen and obtain phosphorus trifluoride. According to GC-MS analysis, the conversion rate of nitrogen trifluoride in this example was 88%, the selectivity of phosphorus trifluoride was 92%, and the purity of phosphorus trifluoride was 99.92%. The obtained phosphorus trifluoride was subjected to fluorine spectrum analysis, and the results are as follows: Figure 1 As shown, specifically 19 F-NMR: -35 (s, 3F).
[0020] Example 2 A method for preparing phosphorus trifluoride by initiating a reaction between nitrogen trifluoride and phosphorus using ultraviolet light, the specific steps of which are as follows: S1. Reactor preparation: A corrosion-resistant photochemical reactor made of Hastelloy alloy is used. The reactor is equipped with a quartz glass transmission window. The reactor is replaced with nitrogen three times to remove all oxygen. S2. Raw material addition: Add 7.0g (0.23mol) of red phosphorus with a particle size of 50 mesh to the reactor and seal the reactor; S3. Raw material introduction: Nitrogen trifluoride gas is introduced into the reactor through the raw material inlet, and the molar ratio of nitrogen trifluoride to red phosphorus is controlled at 1:1. The pressure inside the reactor is maintained at 0.2MPa. S4. Ultraviolet light irradiation: Turn on the 200nm wavelength ultraviolet light source, the light source power is 500W, the light irradiation distance is 10cm, the light reaction is carried out for 4h, the temperature inside the reactor is monitored during the reaction, and the temperature is kept at room temperature. S5. Product collection: After the reaction is completed, the reaction product is collected from the product outlet and condensed in a condenser at -80℃ to remove a small amount of easily condensable impurities such as phosphorus tetrafluoride. S6. Distillation and purification: The condensed product is passed into a packed tower for distillation at a temperature of -60℃ and a vacuum of 0.098MPa to remove light component impurities such as nitrogen and obtain phosphorus trifluoride product. According to GC-MS analysis, the conversion rate of nitrogen trifluoride in this example was 90%, the selectivity of phosphorus trifluoride was 93%, and the purity of phosphorus trifluoride was 99.95%.
[0021] Example 3 A method for preparing phosphorus trifluoride by initiating a reaction between nitrogen trifluoride and phosphorus using ultraviolet light, the specific steps of which are as follows: S1. Reactor preparation: A corrosion-resistant photochemical reactor made of polytetrafluoroethylene is used. The reactor is equipped with a quartz glass transmission window. The reactor is purged with argon gas three times to remove all oxygen. S2. Raw material addition: Add 14.0g (0.45mol) of red phosphorus with a particle size of 200 mesh to the reactor and seal the reactor; S3. Raw material introduction: Nitrogen trifluoride gas is introduced into the reactor through the raw material inlet, and the molar ratio of nitrogen trifluoride to red phosphorus is controlled at 1:2. The pressure inside the reactor is maintained at 0.3MPa. S4. Ultraviolet light irradiation: Turn on the ultraviolet light source with a wavelength of 300nm, the light source power is 50W, the light irradiation distance is 30cm, the light reaction is carried out for 10h, and the temperature inside the reactor is monitored during the reaction and kept at room temperature. S5. Product collection: After the reaction is completed, the reaction product is collected from the product outlet and condensed in a condenser at -40℃ to remove a small amount of easily condensable impurities such as phosphorus tetrafluoride. S6. Distillation and purification: The condensed product is passed into a packed tower for distillation at a temperature of -20℃ and a vacuum of 0.08MPa to remove light component impurities such as nitrogen and obtain phosphorus trifluoride product. According to GC-MS analysis, the conversion rate of nitrogen trifluoride in this example was 85%, the selectivity of phosphorus trifluoride was 90%, and the purity of phosphorus trifluoride was 99.90%.
[0022] The method for preparing phosphorus trifluoride by ultraviolet light-initiated reaction of nitrogen trifluoride and phosphorus is characterized by mild and readily available raw materials, mild and easily controllable reaction conditions, low equipment requirements, high product selectivity, and simple subsequent separation and purification. It can achieve large-scale continuous production, and the high-purity phosphorus trifluoride prepared can meet the application requirements of semiconductor etching, fluorinating agent preparation and other fields, with significant industrial practicality and economic benefits.
[0023] Without causing conflict, those skilled in the art can freely combine and use the above-mentioned additional technical features.
[0024] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.
Claims
1. A method for preparing phosphorus trifluoride by initiating the reaction of nitrogen trifluoride with phosphorus under ultraviolet light, characterized in that: Phosphorus trifluoride was prepared by gas-solid phase photocatalytic reaction using nitrogen trifluoride and elemental phosphorus as raw materials in a closed, corrosion-resistant photochemical reactor under ultraviolet light irradiation. The reaction equation is as follows: 。 2. The method for preparing phosphorus trifluoride by ultraviolet light-initiated reaction of nitrogen trifluoride and phosphorus according to claim 1, characterized in that: The elemental phosphorus is red phosphorus or white phosphorus, with a particle size of 50-200 mesh.
3. The method for preparing phosphorus trifluoride by ultraviolet light-initiated reaction of nitrogen trifluoride and phosphorus according to claim 1, characterized in that: The molar ratio of nitrogen trifluoride to elemental phosphorus is 1:1 to 2.
4. The method for preparing phosphorus trifluoride by ultraviolet light-initiated reaction of nitrogen trifluoride and phosphorus according to claim 1, characterized in that: The ultraviolet light source used for ultraviolet irradiation has a wavelength of 200–300 nm, a power of 50–500 W, an irradiation distance of 5–30 cm, and an irradiation reaction time of 2–10 h.
5. The method for preparing phosphorus trifluoride by ultraviolet light-initiated reaction of nitrogen trifluoride with phosphorus according to claim 1, characterized in that: The pressure of the gas-solid phase photocatalytic reaction is atmospheric pressure or slightly positive pressure, and the temperature is room temperature.
6. The method for preparing phosphorus trifluoride by ultraviolet light-initiated reaction of nitrogen trifluoride with phosphorus according to claim 5, characterized in that: The micro-positive pressure is 0.1–0.3 MPa.
7. The method for preparing phosphorus trifluoride by ultraviolet light-initiated reaction of nitrogen trifluoride with phosphorus according to claim 1, characterized in that: This also includes introducing argon or nitrogen gas into the corrosion-resistant photochemical reactor before the reaction to remove oxygen.
8. The method for preparing phosphorus trifluoride by ultraviolet light-initiated reaction of nitrogen trifluoride and phosphorus according to claim 1, characterized in that: The photocatalytic reaction is carried out in a reactor made of polytetrafluoroethylene or Hastelloy, which is equipped with a quartz glass window for ultraviolet light transmission, a raw material inlet, a product outlet, and a temperature monitoring port.
9. The method for preparing phosphorus trifluoride by ultraviolet light-initiated reaction of nitrogen trifluoride and phosphorus according to claim 1, characterized in that: The reaction product is purified by condensation and distillation to obtain high-purity phosphorus trifluoride, wherein the condensation temperature is -80 to -40°C, the distillation temperature is -60 to -20°C, and the vacuum degree is 0.08 to 0.098 MPa.