A method for the continuous synthesis of phosphorus trifluoride

Abstract

The present application relates to a kind of continuous synthesis of phosphorus trifluoride method, the method includes the following steps: phosphorus source is mixed with fluorination agent, then reaction is carried out, obtains reaction mixture;The reaction mixture is purified to obtain high-purity phosphorus trifluoride.The present application is by continuous flow reactor and reaction rectification cooperation use, and the temperature segmented control of first reaction, second reaction, third reaction synthesis simultaneously separates product and raw material, greatly improves the conversion rate of phosphorus source, HF use amount is greatly reduced, intermediate product is very few, purification is simple, the purity of the obtained phosphorus trifluoride reaches 99.999wt% or more, and it can be continuously prepared phosphorus trifluoride, solves the problems of low conversion rate, poor selectivity, insufficient purity and preparation instability in traditional batch method.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electronic special gas, and relates to a synthesis method of phosphorus trifluoride, in particular to a method for continuously synthesizing phosphorus trifluoride. BACKGROUND

[0002] Phosphorus trifluoride is an important electronic special gas, which is widely used as a doping source in the technical fields of semiconductor manufacturing, ion implantation, solar cell and the like, and is also an important intermediate for synthesizing lithium ion battery electrolyte additives, organic phosphorus ligands and pesticides.

[0003] At present, the main method for synthesizing PF3 in industry includes using phosphorus trichloride (PCl3) and anhydrous hydrogen fluoride (HF) as raw materials, and most of the reactions are carried out in a reaction kettle. The phosphorus trichloride is first laid at the bottom, and then the anhydrous hydrogen fluoride is dropped into the reaction kettle. The main reaction includes:

[0004] PCl3 + 3HF → PF3 + 3HCl;

[0005] The preparation method in the prior art mostly adopts a batch reaction kettle, the reaction temperature is usually 40-60℃, the phosphorus trichloride is first laid at the bottom, and then the anhydrous hydrogen fluoride is dropped into the phosphorus trichloride. Since the HF vaporizes instantly after entering and the contact time between the HF and the phosphorus trichloride is short, the content of the intermediate products PF2Cl and PFCl2 in the production process is high, and it is difficult to purify by rectification. The purity of the obtained product is mostly 99wt%~99.9wt%, and it is difficult to further improve. In addition, the reaction is not completed in one step, but is gradually fluorinated through intermediate products such as PFCl2 and PF2Cl, so the actual reaction is more complex. The reaction temperature in the prior art is higher than the boiling point of hydrogen fluoride, so the hydrogen fluoride vaporizes instantly after being added, which belongs to a gas-liquid contact type reaction mode. In order to improve the purity of the phosphorus trifluoride, the amount of the HF is usually excessive, which is more than 1000 times the molar amount of the PCl3. The hydrogen fluoride vaporization and condensation process causes a large amount of energy waste. The prior art mostly adopts a kettle type reactor or a tower type reactor, which has significant defects, for example: the mixing effect of the traditional reactor is poor, the removal of reaction heat is difficult, local hot spots are easily formed, the number of side reactions increases, the product often contains unreacted fluorochlorophosphorus, which affects the final purity of the PF3, and complex multi-stage rectification purification is required; some reactions use catalysts for reaction, and the commonly used SbCl5 catalyst is easily volatilized and lost or deactivated due to carbon deposition under the reaction conditions, and needs to be supplemented or replaced regularly, which is complicated to operate and high in cost; the strong corrosion of HF and HCl has high requirements for the equipment material, and the intermittent or semi-intermittent operation increases the risk of material leakage.

[0006] Therefore, it is of great significance to develop a method for continuously synthesizing phosphorus trifluoride, which can strengthen mass transfer and heat transfer, improve reaction selectivity and conversion rate, improve the purity of phosphorus trifluoride and realize safe continuous production. SUMMARY

[0007] In view of the deficiencies of the prior art, the present application aims to provide a method for continuously synthesizing phosphorus trifluoride, which uses a continuous flow reactor in combination with reaction rectification, and controls the temperature of the first reaction, the second reaction and the third reaction in sections, and uses three-stage reaction rectification to separate the product and the raw material, so that the raw material continues to enter the next stage of reaction, the conversion rate of the phosphorus source is improved, the reactor pressure is not too high, the intermediate impurities in the product are few, the azeotropic possibility is reduced, the purity of the obtained phosphorus trifluoride reaches more than 99.999wt%, and the continuous preparation of phosphorus trifluoride can be carried out, solving the problems of low conversion rate, poor selectivity, insufficient purity and unstable preparation of the traditional batch method.

[0008] To achieve the purpose of the present application, the following technical solutions are adopted:

[0009] The present application provides a method for continuously synthesizing phosphorus trifluoride, which comprises the following steps:

[0010] The phosphorus source and the fluorinating agent are mixed and then reacted to obtain a reaction mixture; the reaction mixture is subjected to purification treatment to obtain phosphorus trifluoride;

[0011] The reaction comprises a first reaction, a second reaction and a third reaction performed in sequence; the first reaction and the second reaction are subjected to first-stage reaction rectification; the second reaction and the third reaction are subjected to second-stage reaction rectification;

[0012] The first reaction, the second reaction and the third reaction are independently performed in a continuous flow reactor;

[0013] The temperature of the first reaction is 90-100℃;

[0014] The temperature of the second reaction is 110-120℃;

[0015] The temperature of the third reaction is 120-130℃.

[0016] In the present application, the phosphorus source and the fluorinating agent are mixed before the reaction, compared with the liquid raw material mixing method in the traditional method, the microchannel can fully mix gas-gas or gas-liquid mixture, significantly improve the mass transfer efficiency, avoid the problem of insufficient reaction caused by local non-uniform concentration of raw materials, and significantly reduce the amount of fluorinating agent; in combination with the segmented temperature control of the first reaction, the second reaction and the third reaction, and the first rectification and the second rectification, the conversion rate of the phosphorus source can be significantly improved; the uniformly mixed raw material can also avoid side reactions caused by insufficient local fluorinating agent, significantly improve the selectivity of phosphorus trichloride, and improve the purity of the obtained phosphorus trifluoride.

[0017] In some embodiments, the first-stage reactive rectification has a column bottom temperature of 0-10℃, a column top temperature of -40℃ to -10℃, and a pressure of 0.1-1 MPa.

[0018] In some embodiments, the second-stage reactive rectification has a column bottom temperature of 0-10℃, a column top temperature of -40℃ to -10℃, and a pressure of 0.1-1 MPa.

[0019] In some embodiments, the first reaction has a residence time of 1-10 s.

[0020] In some embodiments, the second reaction has a residence time of 1-10 s.

[0021] In some embodiments, the third reaction has a residence time of 1-10 s.

[0022] In some embodiments, the first reaction has a pressure of 3.5-4 MPa.

[0023] In some embodiments, the second reaction has a pressure of 4.5-5 MPa.

[0024] In some embodiments, the third reaction has a pressure of 5.5-6 MPa.

[0025] In some embodiments, the phosphorus source comprises any one or a combination of at least two of phosphorus trichloride (PCl3), phosphorus tribromide (PBr3), or phosphorus triiodide (PI3).

[0026] In some embodiments, the fluorinating agent is hydrogen fluoride (HF).

[0027] In some embodiments, the molar ratio of phosphorus in the phosphorus source to fluorine in the fluorinating agent is 1:3-1:3.2.

[0028] In some embodiments, the purification process comprises molecular sieve adsorption and rectification performed sequentially.

[0029] In some embodiments, the continuous flow reactor comprises a microchannel reactor or a tubular reactor.

[0030] As a preferred technical solution of the method provided by the present application, the method comprises the following steps:

[0031] Phosphorus trichloride and hydrogen fluoride are mixed in a molar ratio of 1:3-1:3.2, and then reacted to obtain a reaction mixture; the reaction mixture is subjected to a purification process to obtain phosphorus trifluoride.

[0032] The reaction comprises a first reaction, a second reaction and a third reaction performed in sequence; a first-stage reaction rectification is performed between the first reaction and the second reaction; a second-stage reaction rectification is performed between the second reaction and the third reaction;

[0033] The first reaction, the second reaction and the third reaction are independently performed in a micro-channel reactor;

[0034] The first reaction has a temperature of 90-100 DEG C, a residence time of 1-10 s and a gauge pressure of 3.5-4 MPa;

[0035] The second reaction has a temperature of 110-120 DEG C, a residence time of 1-10 s and a gauge pressure of 4.5-5 MPa;

[0036] The third reaction has a temperature of 120-130 DEG C, a residence time of 1-10 s and a gauge pressure of 5.5-6 MPa;

[0037] The first-stage reaction rectification has a column bottom temperature of 0-10 DEG C, a column top temperature of -40--10 DEG C and a gauge pressure of 0.1-1 MPa;

[0038] The second-stage reaction rectification has a column bottom temperature of 0-10 DEG C, a column top temperature of -40--10 DEG C and a gauge pressure of 0.1-1 MPa.

[0039] The numerical range of the present application includes not only the point values listed above, but also any point values between the above numerical ranges that are not listed, and the present application does not exhaustively list the specific point values included in the range for the sake of brevity and simplicity.

[0040] Compared with the prior art, the present application has the following beneficial effects:

[0041] In the present application, the phosphorus source and the fluorination agent are mixed before the reaction, which can greatly increase the mixing effect of the two raw materials and significantly improve the mass transfer efficiency compared with the gas-liquid raw material kettle mixing method in the traditional method, thereby avoiding the problem of insufficient reaction caused by uneven local raw material concentration and significantly reducing the amount of fluorination agent; in combination with the segmented temperature control of the first reaction, the second reaction and the third reaction and the first-stage reaction rectification and the second-stage reaction rectification, the conversion rate of the phosphorus source can be significantly improved; the micro-channel mixing can also avoid the side reactions caused by the small amount of local fluorination agent, thereby significantly improving the selectivity of phosphorus trichloride and improving the purity of the obtained phosphorus trifluoride. DETAILED DESCRIPTION

[0042] The technical solutions of the present application will be further illustrated below by means of specific embodiments. Those skilled in the art should understand that the embodiments are only used for understanding the present application and should not be regarded as specific limitations of the present application.

[0043] The "ranges" disclosed in the present application can be defined in the form of lower limit and upper limit, a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of the particular range. The ranges defined in this way can be inclusive or exclusive of the end values, either end value can be independently included or excluded, and can be arbitrarily combined, i.e. any lower limit can be combined with any upper limit to form a range. For example, if the ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges of 60-110 and 80-120 are also contemplated. In addition, if the minimum range values of 1 and 2 are listed, and if the maximum range values of 3, 4 and 5 are also listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "a-b" represents a shorthand notation for any real combination of integers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed herein, and "0-5" is just a shorthand notation for these numerical combinations. In addition, when it is stated that a parameter is an integer ≥ 2, it is equivalent to listing the parameter as, for example, integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when it is stated that a parameter is an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9 and 10.

[0044] In the present application, "combination of at least two" means, unless otherwise specified, more than 2 or equal to 2 in number. For example, "any one or a combination of at least two" means one or more than two. It can be understood that, when referring to "combination of at least two", it means a combination of any suitable number of items, i.e. a combination of "at least two" items in a manner that is not conflicting and can implement the present application.

[0045] If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0046] In the present application, "embodiments" means that the specific features, structures or properties described in connection with the embodiments can be included in at least one embodiment or embodiment of the present application. The appearance of this phrase at various places in the specification does not necessarily mean the same embodiment, nor is it an independent or alternative embodiment to other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described in the present application can be combined with other embodiments.

[0047] Those skilled in the art can understand that the order of writing each step in the method of each embodiment does not mean a strict execution order, and the detailed execution order of each step should be determined by its function and possible inherent logic. If not specifically stated, all steps of the present application can be performed sequentially or randomly, and can be preferably performed sequentially. For example, the method comprises step (a) and step (b), which means that the method can comprise sequentially performed step (a) and step (b), or sequentially performed step (b) and step (a). For example, the method mentioned can also comprise step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0048] In the present application, the open technical features or technical solutions described by the words such as "include" do not exclude additional members other than the listed members, and can be regarded as providing both the closed features or technical solutions composed of the listed members and the open features or solutions including additional members in addition to the listed members. For example, A includes a1, a2 and a3, and unless otherwise stated, it can also include other members, or it can not include additional members, and it can be regarded as providing the technical features or technical solutions of "A is composed of a1, a2 and a3" or "A is selected from a1, a2 and a3", and also providing the technical features or technical solutions of "A includes a1, a2 and a3, and also includes other members".

[0049] In the present application, unless otherwise stated, the features or solutions corresponding to "and / or" include any one of two or more related listed items, and also include any and all combinations of related listed items, including any combination of two related listed items, any combination of more related listed items, or a combination of all related listed items. For example, "A and / or B" indicates a group consisting of A, B and a combination of A and B. Wherein "including A and / or B" can mean "including A, including B, and including A and B", and can also mean "including A, including B, or including A and B", which can be understood appropriately according to the sentence.

[0050] In the present application, in the terms "first aspect", "second aspect", "third aspect", "fourth aspect" and the like, the terms "first", "second", "third", "fourth" and the like are only for description purpose, and cannot be understood as indicating or implying relative importance or quantity, nor can be understood as implying the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth" and the like only serve the purpose of non-exhaustive enumeration description, and should be understood as not constituting a closed limitation on the quantity.

[0051] The application provides a method for continuously synthesizing phosphorus trifluoride, which comprises the following steps:

[0052] The phosphorus source is mixed with the fluorinating agent, and then a reaction is performed to obtain a reaction mixture; the reaction mixture is purified to obtain phosphorus trifluoride;

[0053] The reaction comprises a first reaction, a second reaction and a third reaction performed in sequence; a first-stage reaction rectification is performed between the first reaction and the second reaction; and a second-stage reaction rectification is performed between the second reaction and the third reaction;

[0054] The first reaction, the second reaction and the third reaction are independently performed in a continuous flow reactor;

[0055] The temperature of the first reaction is 90-100 DEG C, for example, can be 90 DEG C, 95 DEG C or 100 DEG C, but is not limited to the listed values, and the remaining values in the value range are also applicable;

[0056] The temperature of the second reaction is 110-120 DEG C, for example, can be 110 DEG C, 115 DEG C or 120 DEG C, but is not limited to the listed values, and the remaining values in the value range are also applicable;

[0057] The temperature of the third reaction is 120-130 DEG C, for example, can be 120 DEG C, 125 DEG C or 130 DEG C, but is not limited to the listed values, and the remaining values in the value range are also applicable.

[0058] The application mixes the phosphorus source with the fluorinating agent before the reaction, compared with the gas-liquid mixing method in the traditional method, the micro-channel mixing gas can greatly increase the contact area of the two, significantly improve the mass transfer efficiency, avoid the problem of insufficient reaction caused by local non-uniform concentration of raw materials, and can significantly reduce the amount of fluorinating agent; in cooperation with the segmented temperature control of the first reaction, the second reaction and the third reaction and the first reaction rectification and the second reaction rectification, the conversion rate of the phosphorus source can be significantly improved; sufficient mixing can also avoid the side reaction caused by local lack of fluorinating agent, so that the selectivity of phosphorus trichloride is significantly improved, and the purity of the obtained phosphorus trifluoride is improved.

[0059] In the method provided by the application, the first reaction is carried out at 90-100°C, higher temperature can accelerate the metathesis reaction of the phosphorus source and the fluorination agent, so that the reaction rate constant is increased by several times, and higher conversion rate is achieved in a shorter time; the second reaction is carried out at 110-120°C, and the third reaction is carried out at 120-130°C, which can further convert the unreacted phosphorus source in this temperature range; and the first-stage reaction rectification and the second-stage reaction rectification can separate and transfer the product in time, inhibit the reverse reaction, and reduce the pressure to ensure that the microchannel can be suitable for the synthesis reaction. In addition, the rapid heat removal capacity of the continuous flow reactor avoids the decomposition of PCl3 caused by local overheating, thereby achieving higher total conversion rate.

[0060] In some embodiments, the column bottom temperature of the first-stage reaction rectification is 0-10°C, the column top temperature is -40--10°C, and the gauge pressure is 0.1-1 MPa.

[0061] In some embodiments, the column bottom temperature of the second-stage reaction rectification is 0-10°C, the column top temperature is -40--10°C, and the gauge pressure is 0.1-1 MPa.

[0062] In some embodiments, the residence time of the first reaction is 1-10 s, for example, it can be 1 s, 3 s, 5 s, 8 s or 10 s, but is not limited to the listed values, and the remaining values not listed in the value range are also applicable.

[0063] In some embodiments, the residence time of the second reaction is 1-10 s, for example, it can be 1 s, 3 s, 5 s, 8 s or 10 s, but is not limited to the listed values, and the remaining values not listed in the value range are also applicable.

[0064] In some embodiments, the residence time of the third reaction is 1-10 s, for example, it can be 1 s, 3 s, 5 s, 8 s or 10 s, but is not limited to the listed values, and the remaining values not listed in the value range are also applicable.

[0065] In some embodiments, the gauge pressure of the first reaction is 3.5-4 MPa, for example, it can be 3.5 MPa, 3.8 MPa or 4 MPa, but is not limited to the listed values, and the remaining values not listed in the value range are also applicable.

[0066] In some embodiments, the gauge pressure of the second reaction is 4.5-5 MPa, for example, it can be 4.5 MPa, 4.8 MPa or 5 MPa, but is not limited to the listed values, and the remaining values not listed in the value range are also applicable.

[0067] In some embodiments, the second reaction is carried out at a pressure of 5.5 MPa to 6 MPa, for example, 5.5 MPa, 5.8 MPa or 6 MPa, but not limited to the listed values, and the remaining values in the range are also applicable.

[0068] In some embodiments, the mixing is carried out in a static mixer, and the present application does not specifically limit the structure of the static mixer, as long as it can uniformly mix the phosphorus source and the fluorinating agent.

[0069] In some embodiments, the material of the continuous flow reactor includes any one or a combination of at least two of Hastelloy, Inconel, Monel, PTFE, PFA, PVDF, silicon carbide, glass or graphite.

[0070] In some embodiments, the phosphorus source includes any one or a combination of at least two of phosphorus trichloride (PCl3), phosphorus tribromide (PBr3) or phosphorus triiodide (PI3), and typical but non-limiting combinations include a combination of phosphorus trichloride and phosphorus tribromide, a combination of phosphorus tribromide and phosphorus triiodide, or a combination of phosphorus trichloride, phosphorus tribromide and phosphorus triiodide.

[0071] In some embodiments, the fluorinating agent is hydrogen fluoride (HF).

[0072] In some embodiments, the molar ratio of phosphorus in the phosphorus source to fluorine in the fluorinating agent is 1:3 to 1:3.2, for example, 1:3, 1:3.1 or 1:3.2, but not limited to the listed values, and the remaining values in the range are also applicable.

[0073] In some embodiments, the purification process includes molecular sieve adsorption and rectification in sequence.

[0074] In some embodiments, the molecular sieve used in the molecular sieve adsorption includes any one of 3A molecular sieve, 4A molecular sieve or 13X molecular sieve.

[0075] In some embodiments, the continuous flow reactor includes a microchannel reactor or a tubular reactor.

[0076] As a preferred technical solution of the method provided by the present application, the method includes the following steps:

[0077] Phosphorus trichloride and hydrogen fluoride are mixed according to a molar ratio of 1:3 to 1:3.2, and then a reaction is carried out to obtain a reaction mixture; the reaction mixture is subjected to a purification process to obtain phosphorus trifluoride;

[0078] The reaction comprises a first reaction, a second reaction and a third reaction performed in sequence; a first-stage reaction rectification is performed between the first reaction and the second reaction; a second-stage reaction rectification is performed between the second reaction and the third reaction;

[0079] The first reaction, the second reaction and the third reaction are independently performed in a micro-channel reactor;

[0080] The first reaction has a temperature of 90-100 DEG C, a residence time of 1-10 s and a gauge pressure of 3.5-4 MPa;

[0081] The second reaction has a temperature of 110-120 DEG C, a residence time of 1-10 s and a gauge pressure of 4.5-5 MPa;

[0082] The third reaction has a temperature of 120-130 DEG C, a residence time of 1-10 s and a gauge pressure of 5.5-6 MPa;

[0083] The first-stage rectification has a column bottom temperature of 0-10 DEG C, a column top temperature of -40--10 DEG C and a gauge pressure of 0.1-1 MPa;

[0084] The second-stage rectification has a column bottom temperature of 0-10 DEG C, a column top temperature of -40--10 DEG C and a gauge pressure of 0.1-1 MPa.

[0085] Embodiment 1

[0086] The embodiment provides a method for continuously synthesizing phosphorus trifluoride, comprising the following steps:

[0087] Phosphorus trichloride and hydrogen fluoride are mixed according to a molar ratio of 1:3.1, and then a reaction is performed to obtain a reaction mixture; the reaction mixture is subjected to molecular sieve adsorption and rectification (a column bottom temperature is -50 DEG C, a column top temperature is -60 DEG C and a gauge pressure is 0.5 MPa) in sequence to obtain phosphorus trifluoride;

[0088] The reaction comprises a first reaction, a second reaction and a third reaction performed in sequence; a first-stage reaction rectification is performed between the first reaction and the second reaction; a second-stage reaction rectification is performed between the second reaction and the third reaction;

[0089] The first reaction, the second reaction and the third reaction are independently performed in a micro-channel reactor;

[0090] The first reaction has a temperature of 95 DEG C, a residence time of 5 s and a gauge pressure of 3.8 MPa;

[0091] The second reaction has a temperature of 115 DEG C, a residence time of 5 s and a gauge pressure of 4.8 MPa;

[0092] The temperature of the third reaction is 125℃, the residence time is 5s, and the gauge pressure is 5.8MPa;

[0093] The column bottom temperature of the first reaction rectification is 10℃, the column top temperature is -20℃, and the gauge pressure is 0.5MPa;

[0094] The column bottom temperature of the second reaction rectification is 10℃, the column top temperature is -20℃, and the gauge pressure is 0.5MPa.

[0095] Example 2

[0096] The present example provides a method for continuously synthesizing phosphorus trifluoride, comprising the following steps:

[0097] Phosphorus trichloride and hydrogen fluoride are mixed according to a molar ratio of 1:3, and then reacted to obtain a reaction mixture; the reaction mixture is subjected to molecular sieve adsorption and rectification (the column bottom temperature is -50℃, the column top temperature is -60℃, and the gauge pressure is 0.5MPa) in sequence to obtain phosphorus trifluoride;

[0098] The reaction comprises a first reaction, a second reaction, and a third reaction performed in sequence; the first reaction rectification is performed between the first reaction and the second reaction; the second reaction rectification is performed between the second reaction and the third reaction;

[0099] The first reaction, the second reaction, and the third reaction are independently performed in a micro-channel reactor;

[0100] The temperature of the first reaction is 90℃, the residence time is 10s, and the gauge pressure is 3.5MPa;

[0101] The temperature of the second reaction is 110℃, the residence time is 10s, and the gauge pressure is 4.5MPa;

[0102] The temperature of the third reaction is 120℃, the residence time is 10s, and the gauge pressure is 5.5MPa;

[0103] The column bottom temperature of the first reaction rectification is 0℃, the column top temperature is -40℃, and the gauge pressure is 0.1MPa;

[0104] The column bottom temperature of the second reaction rectification is 0℃, the column top temperature is -40℃, and the gauge pressure is 0.1MPa.

[0105] Example 3

[0106] The present example provides a method for continuously synthesizing phosphorus trifluoride, comprising the following steps:

[0107] The phosphorus trichloride and hydrogen fluoride are mixed according to a molar ratio of 1:3.2, and then a reaction is carried out to obtain a reaction mixture; the reaction mixture is subjected to molecular sieve adsorption and rectification (the column bottom temperature is -50℃, the column top temperature is -60℃, and the gauge pressure is 0.5MPa) in sequence to obtain phosphorus trifluoride;

[0108] The reaction comprises a first reaction, a second reaction and a third reaction carried out in sequence; the first reaction and the second reaction are subjected to first-stage reaction rectification; the second reaction and the third reaction are subjected to second-stage reaction rectification;

[0109] The first reaction, the second reaction and the third reaction are independently carried out in a micro-channel reactor;

[0110] The temperature of the first reaction is 100℃, the residence time is 1s, and the gauge pressure is 4MPa;

[0111] The temperature of the second reaction is 120℃, the residence time is 1s, and the gauge pressure is 5MPa;

[0112] The temperature of the third reaction is 130℃, the residence time is 1s, and the gauge pressure is 6MPa;

[0113] The column bottom temperature of the first-stage reaction rectification is 5℃, the column top temperature is -10℃, and the gauge pressure is 1MPa;

[0114] The column bottom temperature of the second-stage reaction rectification is 5℃, the column top temperature is -10℃, and the gauge pressure is 1MPa.

[0115] Comparative Example 1

[0116] The present comparison provides a method for continuously synthesizing phosphorus trifluoride, which is the same as Example 1 except that the first reaction and the first-stage reaction rectification are not carried out, and comprises the following steps:

[0117] The phosphorus trichloride and hydrogen fluoride are mixed according to a molar ratio of 1:3.1, and then a reaction is carried out to obtain a reaction mixture; the reaction mixture is subjected to molecular sieve adsorption and rectification (the column bottom temperature is -50℃, the column top temperature is -60℃, and the gauge pressure is 0.5MPa) in sequence to obtain phosphorus trifluoride;

[0118] The reaction comprises a second reaction and a third reaction carried out in sequence; the second reaction and the third reaction are subjected to second-stage reaction rectification;

[0119] The second reaction and the third reaction are independently carried out in a micro-channel reactor;

[0120] The temperature of the second reaction is 115℃, the residence time is 5s, and the gauge pressure is 4.8MPa;

[0121] The temperature of the third reaction is 125℃, the residence time is 5s, and the gauge pressure is 5.8MPa;

[0122] The column bottom temperature of the second-stage reaction rectification is 10℃, the column top temperature is -20℃, and the gauge pressure is 0.5MPa.

[0123] Comparative Example 2

[0124] This comparative example provides a method for continuously synthesizing phosphorus trifluoride, which is the same as Example 1 except that the second reaction and the second-stage reaction rectification are not performed, and includes the following steps:

[0125] Phosphorus trichloride and hydrogen fluoride are mixed in a molar ratio of 1:3.1, and then reacted to obtain a reaction mixture; the reaction mixture is sequentially subjected to molecular sieve adsorption and rectification (the column bottom temperature is -50℃, the column top temperature is -60℃, and the gauge pressure is 0.5MPa) to obtain phosphorus trifluoride;

[0126] The reaction includes sequentially performed first and third reactions; the first reaction and the third reaction are subjected to first-stage reaction rectification therebetween;

[0127] The first reaction and the third reaction are independently performed in a micro-channel reactor, respectively;

[0128] The temperature of the first reaction is 95℃, the residence time is 5s, and the gauge pressure is 3.8MPa;

[0129] The temperature of the third reaction is 125℃, the residence time is 5s, and the gauge pressure is 5.8MPa;

[0130] The column bottom temperature of the first-stage reaction rectification is 10℃, the column top temperature is -20℃, and the gauge pressure is 0.5MPa.

[0131] Comparative Example 3

[0132] This comparative example provides a method for continuously synthesizing phosphorus trifluoride, which is the same as Example 1 except that the second-stage reaction rectification and the third reaction are not performed, and includes the following steps:

[0133] Phosphorus trichloride and hydrogen fluoride are mixed in a molar ratio of 1:3.1, and then reacted to obtain a reaction mixture; the reaction mixture is sequentially subjected to molecular sieve adsorption and rectification (the column bottom temperature is -50℃, the column top temperature is -60℃, and the gauge pressure is 0.5MPa) to obtain phosphorus trifluoride;

[0134] The reaction includes sequentially performed first and second reactions; the first reaction and the second reaction are subjected to first-stage reaction rectification therebetween;

[0135] The first reaction and the second reaction are independently carried out in a microchannel reactor;

[0136] The temperature of the first reaction is 95℃, the residence time is 5s, and the gauge pressure is 3.8MPa;

[0137] The temperature of the second reaction is 115℃, the residence time is 5s, and the gauge pressure is 4.8MPa;

[0138] The column bottom temperature of the first-stage reaction rectification is 10℃, the column top temperature is -20℃, and the gauge pressure is 0.5MPa.

[0139] Comparative Example 4

[0140] This comparative example provides a method for continuously synthesizing phosphorus trifluoride, which is the same as Example 1 except that only the first reaction is carried out, including the following steps:

[0141] Phosphorus trichloride and hydrogen fluoride are mixed in a molar ratio of 1:3.1, and then reacted to obtain a reaction mixture; the reaction mixture is sequentially subjected to molecular sieve adsorption and rectification (column bottom temperature -50℃, column top temperature -60℃, gauge pressure 0.5MPa) to obtain phosphorus trifluoride;

[0142] The reaction includes the first reaction;

[0143] The first reaction is carried out in a microchannel reactor;

[0144] The temperature of the first reaction is 95℃, the residence time is 5s, and the gauge pressure is 3.8MPa.

[0145] Comparative Example 5

[0146] This comparative example provides a method for continuously synthesizing phosphorus trifluoride, which is the same as Example 1 except that only the second reaction is carried out, including the following steps:

[0147] Phosphorus trichloride and hydrogen fluoride are mixed in a molar ratio of 1:3.1, and then reacted to obtain a reaction mixture; the reaction mixture is sequentially subjected to molecular sieve adsorption and rectification (column bottom temperature -50℃, column top temperature -60℃, gauge pressure 0.5MPa) to obtain phosphorus trifluoride;

[0148] The reaction includes the second reaction;

[0149] The second reaction is carried out in a microchannel reactor;

[0150] The temperature of the second reaction is 115℃, the residence time is 5s, and the gauge pressure is 4.8MPa.

[0151] Comparative Example 6

[0152] The comparative example provides a method for continuously synthesizing phosphorus trifluoride, which is the same as example 1 except that only the third reaction is performed, and includes the following steps:

[0153] The phosphorus trichloride and hydrogen fluoride are mixed in a molar ratio of 1:3.1, and then reacted to obtain a reaction mixture; the reaction mixture is subjected to molecular sieve adsorption and rectification (the column bottom temperature is -50 DEG C, the column top temperature is -60 DEG C, and the gauge pressure is 0.5 MPa) in sequence to obtain phosphorus trifluoride;

[0154] The reaction includes a third reaction;

[0155] The third reaction is performed in a micro-channel reactor;

[0156] The third reaction has a temperature of 125 DEG C, a residence time of 5 s, and a gauge pressure of 5.8 MPa.

[0157] Performance characterization

[0158] The conversion rate of phosphorus trichloride and the purity of phosphorus trifluoride are determined in the method provided in the above comparative example and example, and the obtained results are shown in Table 1.

[0159] Table 1

[0160] In summary, in the present application, the phosphorus source and the fluorinating agent are mixed before the reaction, compared with the mixing mode of liquid gas raw materials in the traditional method, the micro-channel mixing can greatly increase the contact area of the two, significantly improve the mass transfer efficiency, and avoid the problem of insufficient reaction caused by local non-uniform raw material concentration; the segmented temperature control of the first reaction, the second reaction and the third reaction, and the first-stage reaction rectification and the second-stage reaction rectification can significantly improve the conversion rate of the phosphorus source; the micro-channel mixing can also avoid the side reactions caused by the local lack of fluorinating agent, and significantly improve the selectivity of phosphorus trichloride, thereby improving the purity of the obtained phosphorus trifluoride.

[0161] The applicant declares that the above description is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and those skilled in the art should understand that any changes or replacements within the technical scope disclosed by the present application can be easily thought of by those skilled in the art, and all fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for the continuous synthesis of phosphorus trifluoride, characterized in that, The method comprises the following steps: The phosphorus source is mixed with the fluorinating agent, and then reacted to obtain a reaction mixture; the reaction mixture is subjected to a purification treatment to obtain phosphorus trifluoride; The reaction comprises sequentially performed first, second and third reactions; first-stage reaction rectification is performed between the first reaction and the second reaction; second-stage reaction rectification is performed between the second reaction and the third reaction; The first, second and third reactions are independently performed in continuous flow reactors; The temperature of the first reaction is 90-100 DEG C; The temperature of the second reaction is 110-120 DEG C; The temperature of the third reaction is 120-130 DEG C; The phosphorus source comprises any one or a combination of at least two of phosphorus trichloride, phosphorus tribromide or phosphorus triiodide; The fluorinating agent is hydrogen fluoride.

2. The method of claim 1, wherein, The residence time of the first reaction is 1-10 s; The residence time of the second reaction is 1-10 s; The residence time of the third reaction is 1-10 s.

3. The method according to claim 1 or 2, characterized in that, The first reaction is performed at a gauge pressure of 3.5-4 MPa; The second reaction is performed at a gauge pressure of 4.5-5 MPa; The third reaction is performed at a gauge pressure of 5.5-6 MPa.

4. The method of claim 1, wherein, The first-stage reaction rectification is performed at a column bottom temperature of 0-10 DEG C, a column top temperature of -40--10 DEG C and a gauge pressure of 0.1-1 MPa; The second-stage reaction rectification is performed at a column bottom temperature of 0-10 DEG C, a column top temperature of -40--10 DEG C and a gauge pressure of 0.1-1 MPa.

5. The method of claim 1, wherein, The molar ratio of phosphorus in the phosphorus source to fluorine in the fluorinating agent is 1:3-1:3.

2.

6. The method of claim 1, wherein, The purification treatment comprises sequentially performed molecular sieve adsorption and rectification.

7. The method of claim 1, wherein, The continuous flow reactor comprises a microchannel reactor or a tubular reactor.

8. The method of claim 1, wherein, The method comprises the following steps: Phosphorus trichloride and hydrogen fluoride are mixed at a molar ratio of 1:3-1:3.2, and then introduced into a three-stage continuous flow reactor and reaction rectification combined complete reactor to react, to obtain a reaction mixture; the reaction mixture is subjected to a purification treatment to obtain phosphorus trifluoride; The reaction comprises sequentially performed first, second and third reactions; first-stage reaction rectification is performed between the first reaction and the second reaction; second-stage reaction rectification is performed between the second reaction and the third reaction; The first, second and third reactions are independently performed in microchannel reactors; The first reaction is performed at a temperature of 90-100 DEG C, a residence time of 1-10 s and a gauge pressure of 3.5-4 MPa; The second reaction is performed at a temperature of 110-120 DEG C, a residence time of 1-10 s and a gauge pressure of 4.5-5 MPa; The third reaction is performed at a temperature of 120-130 DEG C, a residence time of 1-10 s and a gauge pressure of 5.5-6 MPa; The purification treatment comprises sequentially performed molecular sieve adsorption and rectification.

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