CN115974018B - Continuous synthesis process and device for phosphorus pentachloride - Google Patents
Continuous synthesis process and device for phosphorus pentachloride Download PDFInfo
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- CN115974018B CN115974018B CN202310115606.9A CN202310115606A CN115974018B CN 115974018 B CN115974018 B CN 115974018B CN 202310115606 A CN202310115606 A CN 202310115606A CN 115974018 B CN115974018 B CN 115974018B
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- UHZYTMXLRWXGPK-UHFFFAOYSA-N phosphorus pentachloride Chemical compound ClP(Cl)(Cl)(Cl)Cl UHZYTMXLRWXGPK-UHFFFAOYSA-N 0.000 title claims abstract description 157
- 238000000034 method Methods 0.000 title claims abstract description 47
- 238000003786 synthesis reaction Methods 0.000 title claims abstract description 33
- 230000015572 biosynthetic process Effects 0.000 title claims abstract description 32
- FAIAAWCVCHQXDN-UHFFFAOYSA-N phosphorus trichloride Chemical compound ClP(Cl)Cl FAIAAWCVCHQXDN-UHFFFAOYSA-N 0.000 claims abstract description 189
- 239000011552 falling film Substances 0.000 claims abstract description 137
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims abstract description 65
- 239000000460 chlorine Substances 0.000 claims abstract description 65
- 229910052801 chlorine Inorganic materials 0.000 claims abstract description 65
- 239000007788 liquid Substances 0.000 claims abstract description 63
- 239000002002 slurry Substances 0.000 claims abstract description 47
- 239000007790 solid phase Substances 0.000 claims abstract description 42
- 238000006298 dechlorination reaction Methods 0.000 claims abstract description 28
- 239000013078 crystal Substances 0.000 claims abstract description 27
- 238000000926 separation method Methods 0.000 claims abstract description 17
- 239000000203 mixture Substances 0.000 claims abstract description 15
- 239000012071 phase Substances 0.000 claims description 73
- 238000010521 absorption reaction Methods 0.000 claims description 55
- 239000007791 liquid phase Substances 0.000 claims description 38
- 238000010992 reflux Methods 0.000 claims description 23
- 238000006243 chemical reaction Methods 0.000 claims description 20
- 238000009833 condensation Methods 0.000 claims description 19
- 230000005494 condensation Effects 0.000 claims description 19
- 238000003756 stirring Methods 0.000 claims description 14
- 238000004062 sedimentation Methods 0.000 claims description 13
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 claims description 12
- 238000004064 recycling Methods 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 abstract description 20
- 238000012423 maintenance Methods 0.000 abstract description 4
- 230000007613 environmental effect Effects 0.000 abstract description 3
- 239000007789 gas Substances 0.000 description 129
- 239000000543 intermediate Substances 0.000 description 49
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 14
- 239000002826 coolant Substances 0.000 description 10
- 238000010438 heat treatment Methods 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 239000007787 solid Substances 0.000 description 8
- 229910002092 carbon dioxide Inorganic materials 0.000 description 7
- 239000001569 carbon dioxide Substances 0.000 description 7
- 238000007599 discharging Methods 0.000 description 5
- 239000003507 refrigerant Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 239000006096 absorbing agent Substances 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 230000002194 synthesizing effect Effects 0.000 description 4
- 238000010924 continuous production Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000004886 process control Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000005660 chlorination reaction Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- CTSLXHKWHWQRSH-UHFFFAOYSA-N oxalyl chloride Chemical compound ClC(=O)C(Cl)=O CTSLXHKWHWQRSH-UHFFFAOYSA-N 0.000 description 2
- 239000002912 waste gas Substances 0.000 description 2
- SKDHHIUENRGTHK-UHFFFAOYSA-N 4-nitrobenzoyl chloride Chemical compound [O-][N+](=O)C1=CC=C(C(Cl)=O)C=C1 SKDHHIUENRGTHK-UHFFFAOYSA-N 0.000 description 1
- HSHGZXNAXBPPDL-HZGVNTEJSA-N 7beta-aminocephalosporanic acid Chemical compound S1CC(COC(=O)C)=C(C([O-])=O)N2C(=O)[C@@H]([NH3+])[C@@H]12 HSHGZXNAXBPPDL-HZGVNTEJSA-N 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000012320 chlorinating reagent Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000012024 dehydrating agents Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- -1 lithium hexafluorophosphate Chemical compound 0.000 description 1
- 239000011268 mixed slurry Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
A continuous synthesis process of phosphorus pentachloride comprises the following steps: reacting phosphorus trichloride with chlorine in a falling film reactor to obtain phosphorus trichloride and phosphorus pentachloride mixture slurry, settling in a settling vessel, continuously feeding the obtained crystal slurry into a solid-liquid separator through a slurry conveying device for solid-liquid separation, feeding the obtained solid-phase phosphorus pentachloride into a first-stage continuous devolatilizer for removing phosphorus trichloride, feeding the obtained phosphorus pentachloride product into a second-stage continuous devolatilizer for reacting with excessive chlorine, and further removing phosphorus trichloride attached to the surface of phosphorus pentachloride crystal to obtain refined phosphorus pentachloride; and then removing chlorine attached to the surface of the crystal by a continuous dechlorination device to obtain a phosphorus pentachloride product. The process can continuously produce phosphorus pentachloride, has high efficiency and stable and controllable product quality, and can solve the problems of poor process stability, high safety risk in shutdown maintenance and production processes, non-ideal occupational health environment, high environmental protection tail gas treatment operation cost and the like in the existing phosphorus pentachloride production process.
Description
Technical Field
The invention relates to the technical field of phosphorus pentachloride synthesis, in particular to a continuous phosphorus pentachloride synthesis process and a device.
Background
Phosphorus pentachloride is one of phosphorus chlorides with wide application, is widely used as chlorinating agent, catalyst, dehydrating agent and the like in organic synthesis, and has the characteristics of quick reaction, high product yield and the like, and is used for synthesizing medical intermediates 7-ACA, p-nitrobenzoyl chloride, oxalyl chloride and the like. In the field of inorganic chemistry, phosphorus pentachloride is widely used for producing lithium hexafluorophosphate and the like as lithium battery electrolytes.
At present, the main production process of phosphorus pentachloride is an intermittent method, the synthesis method of phosphorus pentachloride takes phosphorus trichloride and chlorine gas as raw materials for reaction, a gas-liquid reaction method of reacting chlorine gas with liquid phosphorus trichloride is generally adopted, liquid phosphorus trichloride is added into a closed reaction kettle, and then chlorine gas is introduced for reaction to obtain the phosphorus pentachloride. However, the phosphorus pentachloride product is solid, and as the conversion rate of the phosphorus trichloride is improved, the system is more and more difficult to stir, and even difficult to stir. In order to complete the reaction of phosphorus trichloride as much as possible, the method of introducing excessive chlorine gas for chlorination and then introducing dry carbon dioxide gas after the reaction is completed to discharge residual chlorine gas is generally adopted. However, even if the content of residual phosphorus trichloride in the product is still high, the content is generally more than 0.05% and even more than 0.1%, and chlorine is not completely discharged, so that the product particles are uneven, the hygroscopicity is strong, the fluidity is poor and the like.
In summary, the existing process for producing phosphorus pentachloride has the defects of high content of residual phosphorus trichloride, uneven granularity, poor fluidity and the like in the product, particularly in an intermittent reaction system, the reactor is easy to be blocked due to the existence of solids, the safety risk is caused by manual cleaning, meanwhile, the production efficiency of producing phosphorus pentachloride by intermittent reaction is low, and the occupational sanitation cannot be guaranteed.
Patent CN201520190018.2 and patent CN212222426U both disclose phosphorus pentachloride production devices, liquid phosphorus trichloride is prepared by adding chlorine into a chlorination kettle, and mixing, reacting, drying and replacing the liquid phosphorus trichloride, but the problems in the analysis are more or less existed in the methods and devices of the technical proposal. Patent CN202110261875.7 discloses a method and apparatus for continuously preparing high-purity phosphorus pentachloride, and preparing mixed gas composed of chlorine and inert gas; atomizing liquid phosphorus trichloride, and then carrying out a mixing reaction with the mixed gas to obtain solid high-purity phosphorus pentachloride; however, the device used in the method has the problems of large equipment occupation, unsatisfactory stability of process control, high occupational health risk, high tail gas treatment cost, difficult device parking, inspection and maintenance and the like.
Therefore, the traditional phosphorus pentachloride production process, the stability of the device, the safety of the production process and the high-efficiency and continuous process are important guarantees of the phosphorus pentachloride production process, intermittent process control is guaranteed, but the production efficiency is low, the spray process production efficiency is high, but the stable control requirement of the process control is high, and the two traditional methods have the problem of high safety risks.
Disclosure of Invention
In view of the above, the invention aims to provide a continuous phosphorus pentachloride synthesis process and device, which can remarkably improve the production efficiency of phosphorus pentachloride, improve the control reliability of the device, reduce the risk of safe production of the device and reduce the occupational health risk of the phosphorus pentachloride production process.
The invention provides a continuous phosphorus pentachloride synthesis process, which comprises the following steps:
a) Reacting phosphorus trichloride with chlorine in a falling film reactor to obtain phosphorus trichloride and phosphorus pentachloride mixture slurry, condensing generated gas phase and then refluxing to the falling film reactor for reuse;
b) Settling the phosphorus trichloride and phosphorus pentachloride mixture slurry obtained in the step a) in a settling vessel, continuously feeding the obtained crystal slurry into a solid-liquid separator through a slurry conveying device for solid-liquid separation to respectively obtain liquid-phase phosphorus trichloride which flows back to a falling film reactor, and flows back to the falling film reactor for reuse after gas-phase condensation, and solid-phase phosphorus pentachloride; condensing the gas phase obtained by sedimentation and then refluxing to the falling film reactor for reuse;
c) Allowing the solid-phase phosphorus pentachloride obtained in the step b) to enter a first-stage continuous devolatilizer to remove phosphorus trichloride, condensing the obtained gas phase, refluxing to a falling film reactor for recycling, allowing the obtained phosphorus pentachloride product to enter a second-stage continuous devolatilizer to react with excessive chlorine, and further removing phosphorus trichloride attached to the surface of phosphorus pentachloride crystals to obtain refined phosphorus pentachloride; unreacted chlorine is absorbed by a falling film absorption tower, a small amount of phosphorus pentachloride is generated to flow back to a phosphorus trichloride middle tank along with phosphorus trichloride, and the phosphorus trichloride is conveyed to a falling film reactor for reuse by a phosphorus trichloride circulating pump;
d) Removing chlorine attached to the crystal surface of the refined phosphorus pentachloride obtained in the step c) through a continuous dechlorination device to obtain a phosphorus pentachloride product;
e) And c) condensing the tail gas generated after the condensation of the steps a), b) and c) through a tail gas condenser to recover phosphorus trichloride, and absorbing the phosphorus trichloride through a tail gas absorption tower.
Preferably, the molar ratio of phosphorus trichloride to chlorine in step a) is 1: (0.4-4.5).
Preferably, the temperature of the reaction in step a) is from 40℃to 75℃and the pressure is from 0.1KPa to 20KPa.
Preferably, the temperature of the sedimentation in step b) is 40-75 ℃, the pressure is 0.1 KPa-20 KPa, and the stirring speed is 3-60 rpm.
Preferably, the flow rate of the solid-liquid separation in the step b) is 3L/h to 15L/h, the temperature is 40 ℃ to 75 ℃, and the pressure is 0.1KPa to 1KPa.
Preferably, in the step c), the temperature for removing the phosphorus trichloride in the first-stage continuous devolatilizer is 75-90 ℃, the pressure is 0.4 KPa-20 KPa, and the residence time is 5-10 min.
Preferably, the temperature of the reaction of the chlorine gas entering the secondary continuous devolatilizer and the excessive chlorine gas in the step c) is 40-75 ℃, the pressure is-5 KPa-10 KPa, and the residence time is 1-5 min.
Preferably, the temperature of absorption by the falling film absorption tower in the step c) is 5-25 ℃, and the pressure is-5 KPa to-0.1 KPa.
Preferably, in the step d), the temperature for removing chlorine attached to the crystal surface by a continuous dechlorination device is 30-55 ℃ and the pressure is 1 KPa-8 KPa.
The invention also provides a continuous phosphorus pentachloride synthesizing device, which comprises:
a falling film reactor; the falling film reactor is provided with a chlorine inlet and a phosphorus trichloride inlet; the phosphorus trichloride inlet is also connected with an intermediate condenser;
a settler with a feed inlet connected with a discharge outlet of the falling film reactor;
The slurry conveying device is connected with the discharge port of the settler;
The solid-liquid separator is connected with the discharge port of the slurry conveying device; the liquid phase outlet of the solid-liquid separator is connected with the phosphorus trichloride inlet of the falling film reactor, and the gas phase outlet is connected with the phosphorus trichloride inlet of the falling film reactor through the intermediate condenser;
a first-stage continuous devolatilizer with a feed inlet connected with a solid-phase outlet of the solid-liquid separator; the gas phase outlet of the first-stage continuous devolatilizer is connected with the phosphorus trichloride inlet of the falling film reactor through an intermediate condenser;
a second-stage continuous devolatilizer with a feed inlet connected with a solid phase outlet of the first-stage continuous devolatilizer; the secondary continuous devolatilizer is provided with a chlorine inlet, a chlorine outlet and a phosphorus pentachloride outlet; the chlorine outlet is also connected with a falling film absorption tower; the phosphorus pentachloride outlet is sequentially connected with an upper rotary valve, a continuous dechlorination device and a lower rotary valve;
A phosphorus trichloride middle tank with a feed inlet connected with a liquid phase outlet of the falling film absorption tower; the phosphorus trichloride intermediate tank is connected with a phosphorus trichloride inlet of the falling film reactor through a phosphorus trichloride circulating pump;
The tail gas condenser is connected with the tail gas outlet of the intermediate condenser through the gas inlet; the liquid phase outlet of the tail gas condenser is connected with the feeding port of the phosphorus trichloride middle tank, and the gas phase outlet is also connected with a tail gas absorption tower.
The invention provides a continuous synthesis process and a device of phosphorus pentachloride; the process comprises the following steps: a) Reacting phosphorus trichloride with chlorine in a falling film reactor to obtain phosphorus trichloride and phosphorus pentachloride mixture slurry, condensing generated gas phase and then refluxing to the falling film reactor for reuse; b) Settling the phosphorus trichloride and phosphorus pentachloride mixture slurry obtained in the step a) in a settling vessel, continuously feeding the obtained crystal slurry into a solid-liquid separator through a slurry conveying device for solid-liquid separation to respectively obtain liquid-phase phosphorus trichloride which flows back to a falling film reactor, and flows back to the falling film reactor for reuse after gas-phase condensation, and solid-phase phosphorus pentachloride; condensing the gas phase obtained by sedimentation and then refluxing to the falling film reactor for reuse; c) Allowing the solid-phase phosphorus pentachloride obtained in the step b) to enter a first-stage continuous devolatilizer to remove phosphorus trichloride, condensing the obtained gas phase, refluxing to a falling film reactor for recycling, allowing the obtained phosphorus pentachloride product to enter a second-stage continuous devolatilizer to react with excessive chlorine, and further removing phosphorus trichloride attached to the surface of phosphorus pentachloride crystals to obtain refined phosphorus pentachloride; unreacted chlorine is absorbed by a falling film absorption tower, a small amount of phosphorus pentachloride is generated to flow back to a phosphorus trichloride middle tank along with phosphorus trichloride, and the phosphorus trichloride is conveyed to a falling film reactor for reuse by a phosphorus trichloride circulating pump; d) Removing chlorine attached to the crystal surface of the refined phosphorus pentachloride obtained in the step c) through a continuous dechlorination device to obtain a phosphorus pentachloride product; e) And c) condensing the tail gas generated after the condensation of the steps a), b) and c) through a tail gas condenser to recover phosphorus trichloride, and absorbing the phosphorus trichloride through a tail gas absorption tower. Compared with the prior art, the phosphorus pentachloride continuous synthesis process and the device provided by the invention realize better overall interaction through specific process steps under specific structures and continuous relations, can realize continuous production, have high efficiency and stable and controllable product quality, and can solve the problems of poor process stability, high safety risks in shutdown maintenance and production processes, non-ideal occupational health environment, high environmental protection tail gas treatment operation cost and the like in the existing phosphorus pentachloride production process.
Drawings
FIG. 1 is a flow chart of a continuous synthesis process of phosphorus pentachloride provided by an embodiment of the invention;
Fig. 2 is a schematic structural diagram of a continuous synthesis device for phosphorus pentachloride according to an embodiment of the present invention.
Detailed Description
The technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention provides a continuous phosphorus pentachloride synthesis process, which comprises the following steps:
a) Reacting phosphorus trichloride with chlorine in a falling film reactor to obtain phosphorus trichloride and phosphorus pentachloride mixture slurry, condensing generated gas phase and then refluxing to the falling film reactor for reuse;
b) Settling the phosphorus trichloride and phosphorus pentachloride mixture slurry obtained in the step a) in a settling vessel, continuously feeding the obtained crystal slurry into a solid-liquid separator through a slurry conveying device for solid-liquid separation to respectively obtain liquid-phase phosphorus trichloride which flows back to a falling film reactor, and flows back to the falling film reactor for reuse after gas-phase condensation, and solid-phase phosphorus pentachloride; condensing the gas phase obtained by sedimentation and then refluxing to the falling film reactor for reuse;
c) Allowing the solid-phase phosphorus pentachloride obtained in the step b) to enter a first-stage continuous devolatilizer to remove phosphorus trichloride, condensing the obtained gas phase, refluxing to a falling film reactor for recycling, allowing the obtained phosphorus pentachloride product to enter a second-stage continuous devolatilizer to react with excessive chlorine, and further removing phosphorus trichloride attached to the surface of phosphorus pentachloride crystals to obtain refined phosphorus pentachloride; unreacted chlorine is absorbed by a falling film absorption tower, a small amount of phosphorus pentachloride is generated to flow back to a phosphorus trichloride middle tank along with phosphorus trichloride, and the phosphorus trichloride is conveyed to a falling film reactor for reuse by a phosphorus trichloride circulating pump;
d) Removing chlorine attached to the crystal surface of the refined phosphorus pentachloride obtained in the step c) through a continuous dechlorination device to obtain a phosphorus pentachloride product;
e) And c) condensing the tail gas generated after the condensation of the steps a), b) and c) through a tail gas condenser to recover phosphorus trichloride, and absorbing the phosphorus trichloride through a tail gas absorption tower.
Firstly, reacting phosphorus trichloride and chlorine in a falling film reactor to obtain phosphorus trichloride and phosphorus pentachloride mixture slurry, condensing generated gas phase and then refluxing to the falling film reactor for reuse.
In the present invention, the phosphorus trichloride and chlorine may be commercially available sources well known to those skilled in the art, and the present invention is not particularly limited thereto.
In the invention, the feeding mole ratio of the phosphorus trichloride to the chlorine is preferably 1: (0.4 to 4.5); in certain embodiments of the invention, the molar ratio of liquid phosphorus trichloride to chlorine is 1:2.2 to 4.5, in certain embodiments of the invention, the molar ratio of liquid phosphorus trichloride to chlorine is 1:0.4 to 2.2.
In the present invention, the temperature of the reaction is preferably 40 to 75℃and the pressure is preferably 0.1 to 20KPa.
In the invention, the upper part of the falling film reactor is provided with two phosphorus trichloride liquid inlets and a chlorine gas feed inlet, the heat transfer area is preferably 120m 2, and the coolant is phase-change coolant; the cooling medium of the falling film reactor is water, and the temperature of the cooling water is 25-60 ℃.
In the present invention, the gas phase condensation produced is preferably carried out using an intermediate condenser well known to those skilled in the art.
Secondly, the obtained phosphorus trichloride and phosphorus pentachloride mixture slurry is subjected to preliminary separation by sedimentation in a sedimentation device, and the obtained crystal slurry (lower layer) continuously enters a solid-liquid separator through a slurry conveying device to carry out solid-liquid separation, so that liquid-phase phosphorus trichloride is respectively obtained to flow back to a falling film reactor, flow back to the falling film reactor for reuse after gas-phase condensation, and solid-phase phosphorus pentachloride is obtained; and condensing the gas phase obtained by sedimentation and then refluxing to the falling film reactor for reuse.
In certain embodiments of the invention, the phosphorus trichloride and phosphorus pentachloride are separated by sedimentation in a settler, the solid-to-liquid ratio of the phosphorus trichloride and the phosphorus pentachloride under-slurry is controlled by stirring in the settler, and in certain embodiments of the invention, the phosphorus pentachloride content at the lower bottom of the settler is preferably 18-25%.
In the present invention, the temperature of the sedimentation is preferably 40 to 75 ℃, the pressure is preferably 0.1 to 20KPa, and the stirring speed is preferably 3 to 60rpm, more preferably 20 to 50rpm.
In the present invention, the flow rate of the solid-liquid separation is preferably 3L/h to 15L/h, the temperature is preferably 40 ℃ to 75 ℃, and the pressure is preferably 0.1KPa to 1KPa.
In the present invention, the vapor phase condensation obtained by the sedimentation is preferably performed using an intermediate condenser well known to those skilled in the art.
Then, the obtained solid-phase phosphorus pentachloride enters a first-stage continuous devolatilizer to remove phosphorus trichloride, the obtained gas phase is condensed and then flows back to a falling film reactor for reuse, the obtained phosphorus pentachloride product enters a second-stage continuous devolatilizer to react with excessive chlorine, and phosphorus trichloride attached to the surface of phosphorus pentachloride crystals is further removed, so that refined phosphorus pentachloride is obtained; unreacted chlorine is absorbed by the falling film absorption tower, a small amount of phosphorus pentachloride is generated and flows back to the phosphorus trichloride middle tank along with the phosphorus trichloride, and the phosphorus trichloride is conveyed to the falling film reactor for reuse by the phosphorus trichloride circulating pump.
In the invention, the solid phosphorus pentachloride preferably contains about 5% -19% of phosphorus trichloride, and can remove excessive phosphorus trichloride in a first-stage continuous devolatilizer; the primary continuous devolatilizer is preferably a horizontal reactor with double stirring, the stirring speed is preferably 80-140 rpm, the upper part is provided with a material inlet, a gas phase outlet and a solid phase material outlet, the jacket is heated, the heat source is heated by steam or electricity, namely, the heating mode of the primary continuous devolatilizer is preferably steam heating, and the steam pressure is 0.02-0.4 MPa or electricity heating.
In the invention, the temperature for removing phosphorus trichloride in the primary continuous devolatilizer is preferably 75-90 ℃, the pressure is preferably 0.4 KPa-20 KPa, and the residence time is preferably 5-10 min.
In the present invention, the gas phase condensation obtained is preferably carried out using an intermediate condenser well known to those skilled in the art.
In the invention, the two-stage continuous devolatilizer is preferably a horizontal reactor with double stirring, the stirring speed is preferably 60 rpm-140 rpm, the upper part is provided with a material inlet formed by the one-stage continuous devolatilizer, a gas phase outlet, a solid phase material outlet, a jacket is used for cooling, and a phase-change coolant is selected as the coolant; the reaction temperature of the chlorine entering the secondary continuous devolatilizer and the excessive chlorine is preferably 40-75 ℃, the pressure is preferably-5 KPa-10 KPa, and the residence time is preferably 1-5 min.
In the invention, the temperature absorbed by the falling film absorption tower is preferably 5-25 ℃, and the pressure is preferably-5 KPa to-0.1 Kpa; the circulating amount of the phosphorus trichloride in the falling film absorption tower is preferably 100-200L/h, and the cooling medium in the absorption tower is preferably low-temperature water or chilled water.
In the invention, the phosphorus trichloride middle tank is a conventional carbon steel tank, preferably three feed inlets are arranged, and the lower part of the phosphorus trichloride middle tank is provided with a discharge outlet; the phosphorus trichloride circulating pump can adopt a magnetic pump or a shielding pump, and the lift is 20-60 meters.
Finally, the chlorine attached to the crystal surface of the refined phosphorus pentachloride is removed by a continuous dechlorination device, and a phosphorus pentachloride product is obtained.
In the invention, the temperature for removing chlorine attached to the crystal surface by a continuous dechlorination device is preferably 30-55 ℃, and the pressure is preferably 1 KPa-8 KPa; the displacement gas of the continuous dechlorination device is preferably carbon dioxide or nitrogen, more preferably carbon dioxide.
Meanwhile, the tail gas generated after condensation in the steps is condensed and recovered by a tail gas condenser and then absorbed by a tail gas absorption tower.
In the invention, the phosphorus trichloride tail gas generated by the settler is condensed by an intermediate condenser (preferably a conventional tubular condenser, the design area is preferably 30m 2～70m2, the coolant is preferably a phase-change coolant), the condensation temperature is preferably 6-20 ℃, the pressure is preferably normal pressure, and the phosphorus trichloride flows back to the falling film reactor for reuse; the phosphorus trichloride tail gas generated by the falling film reactor is condensed by an intermediate condenser, the condensation temperature is preferably 6-20 ℃, the pressure is preferably normal pressure, the phosphorus trichloride is refluxed to the falling film reactor for reutilization, and the refrigerant is preferably low temperature water at 5-12 ℃; the phosphorus trichloride tail gas generated in the first-stage continuous devolatilization device is condensed by an intermediate condenser, the condensation temperature is preferably 6-20 ℃, the pressure is preferably normal pressure, the phosphorus trichloride is refluxed to a falling film reactor for reutilization, and the refrigerant is preferably low temperature water at 5-12 ℃; and the tail gas of the intermediate condenser and the falling film absorption tower is condensed by the tail gas condenser, the condensation temperature is preferably-3 ℃ to-18 ℃, the pressure is preferably normal pressure, the recycled phosphorus trichloride is returned to the phosphorus trichloride intermediate tank for reuse, and the refrigerant is preferably a refrigerating fluid at-5 ℃ to-20 ℃.
The invention also provides a continuous phosphorus pentachloride synthesizing device, which comprises:
a falling film reactor; the falling film reactor is provided with a chlorine inlet and a phosphorus trichloride inlet; the phosphorus trichloride inlet is also connected with an intermediate condenser;
a settler with a feed inlet connected with a discharge outlet of the falling film reactor;
The slurry conveying device is connected with the discharge port of the settler;
The solid-liquid separator is connected with the discharge port of the slurry conveying device; the liquid phase outlet of the solid-liquid separator is connected with the phosphorus trichloride inlet of the falling film reactor, and the gas phase outlet is connected with the phosphorus trichloride inlet of the falling film reactor through the intermediate condenser;
a first-stage continuous devolatilizer with a feed inlet connected with a solid-phase outlet of the solid-liquid separator; the gas phase outlet of the first-stage continuous devolatilizer is connected with the phosphorus trichloride inlet of the falling film reactor through an intermediate condenser;
a second-stage continuous devolatilizer with a feed inlet connected with a solid phase outlet of the first-stage continuous devolatilizer; the secondary continuous devolatilizer is provided with a chlorine inlet, a chlorine outlet and a phosphorus pentachloride outlet; the chlorine outlet is also connected with a falling film absorption tower; the phosphorus pentachloride outlet is sequentially connected with an upper rotary valve, a continuous dechlorination device and a lower rotary valve;
A phosphorus trichloride middle tank with a feed inlet connected with a liquid phase outlet of the falling film absorption tower; the phosphorus trichloride intermediate tank is connected with a phosphorus trichloride inlet of the falling film reactor through a phosphorus trichloride circulating pump;
The tail gas condenser is connected with the tail gas outlet of the intermediate condenser through the gas inlet; the liquid phase outlet of the tail gas condenser is connected with the feeding port of the phosphorus trichloride middle tank, and the gas phase outlet is also connected with a tail gas absorption tower.
In the invention, the continuous phosphorus pentachloride synthesis process and device comprise the following steps:
the device comprises a falling film reactor, a settler connected with a liquid phase outlet of the falling film reactor, an intermediate condenser connected with a liquid phase inlet of the falling film reactor, a solid-liquid separator connected with a liquid phase inlet of the falling film reactor, a phosphorus trichloride intermediate tank connected with a liquid phase inlet of the falling film reactor, a slurry conveying device connected with a liquid phase outlet of the settler, an intermediate condenser connected with a gas phase outlet of the settler, a slurry conveying device connected with a liquid phase inlet of the solid-liquid separator, a first-stage continuous devolatilizer connected with a solid phase outlet of the solid-liquid separator, an intermediate condenser connected with a gas phase outlet of the first-stage continuous devolatilizer, a second-stage continuous devolatilizer connected with a solid phase outlet of the first-stage continuous devolatilizer, a falling film absorber connected with a solid phase outlet of the second-stage continuous devolatilizer, an intermediate condenser connected with a gas phase outlet of the falling film absorber, a phosphorus trichloride intermediate tank connected with a liquid phase inlet of the falling film absorber, an intermediate condenser connected with a gas phase outlet of the second-stage continuous devolatilizer, and a tail gas condenser connected with a gas phase outlet of the intermediate condenser connected with a tail gas absorber.
In the invention, the falling film reactor is provided with a phosphorus trichloride feeding distributor, a chlorine gas inlet, a chlorine gas distributor, a cooling jacket, a coolant inlet and a coolant outlet, a phosphorus trichloride reflux port and a discharge port; the phosphorus trichloride feeding distributor is sequentially connected with a phosphorus trichloride circulating pump and a phosphorus trichloride middle tank; the phosphorus trichloride reflux port is connected with a reflux intermediate condenser; and a discharge hole arranged on the falling film reactor is connected with the settler.
In the invention, the settler is provided with a feed inlet, a discharge outlet, a stirrer and a gas phase outlet; a feed inlet arranged on the settler is connected with the falling film reactor; a discharge hole arranged on the settler is connected with a slurry discharge device; the gas phase outlet arranged on the settler is connected with an intermediate condenser.
In the invention, the solid-liquid separator is provided with a liquid phase inlet and a solid phase outlet; the liquid phase inlet arranged on the solid-liquid separator is connected with the first-stage continuous devolatilizer.
In the invention, the primary continuous devolatilization gas is provided with a solid phase feed inlet, a gas phase outlet, a solid phase outlet, a cooling jacket and a cold and hot medium inlet and outlet; a solid feed inlet arranged on the first-stage continuous devolatilizer is connected with the falling film reactor; a gas phase outlet arranged on the first-stage continuous devolatilizer is connected with a reflux intermediate condenser; and a solid phase outlet arranged on the first-stage continuous devolatilizer is connected with the second-stage continuous devolatilizer.
In the invention, the two-stage continuous devolatilizer is provided with a feed inlet, a gas phase outlet, a solid phase outlet and a chlorine inlet; the feeding hole arranged on the secondary continuous devolatilizer is connected with the primary continuous devolatilizer; a gas phase outlet arranged on the secondary continuous devolatilizer is connected with an intermediate condenser; the solid phase outlet arranged on the two-stage continuous devolatilizer is connected with the upper rotary valve.
In the invention, the dechlorination device is provided with a feed inlet, a solid-phase discharge outlet, a carbon dioxide gas inlet, a carbon dioxide and other waste gas outlets; a feed inlet arranged on the dechlorination device is connected with the upper rotary valve; a solid-phase discharge hole arranged on the dechlorination device is connected with the lower rotary valve; and an exhaust gas outlet such as carbon dioxide arranged on the dechlorination device is connected with the tail gas absorption tower.
In the invention, the falling film absorption tower is provided with a phase inlet, a gas phase outlet, a liquid phase inlet and a liquid phase outlet, and a refrigerant inlet and a refrigerant outlet; a gas phase inlet arranged on the falling film absorption tower is connected with a secondary continuous devolatilizer; a gas phase outlet arranged on the falling film absorption tower is sequentially connected with a tail gas fan and a tail gas condenser; a liquid phase inlet arranged on the falling film absorption tower is sequentially connected with a phosphorus trichloride circulating pump and a phosphorus trichloride middle tank; and a liquid phase outlet arranged on the falling film absorption tower is connected with a phosphorus trichloride middle tank.
In the invention, a gas distributor and a liquid distributor are arranged in the cylinder of the falling film reactor.
In the invention, a parallel main shaft is arranged in the cylinder body of the primary continuous devolatilizer, and the main shaft is driven by a main motor to drive a main shaft speed reducer; the main shaft is provided with a composite gas stirring structure with combined paddles, and the combined stirring is suitable for dispersing slurry materials; a cooling jacket is arranged around the cylinder body, and a cold and hot medium inlet and a cold medium outlet are arranged on the jacket; the cylinder body is provided with 1-4 gas phase outlets and one feeding inlet.
In the invention, a parallel main shaft is arranged in the barrel of the secondary continuous devolatilizer, and the main shaft is driven by a main motor to drive a main shaft speed reducer; the main shaft is provided with a composite stirring structure of a combined blade; a heating jacket is arranged around the cylinder body, and a heating carrier agent inlet and a heating carrier agent outlet are arranged on the jacket; the cylinder body is provided with 1-4 gas phase outlets, one inlet and one solid phase outlet.
In the invention, an upper rotary valve is arranged on the dechlorination device, a lower rotary valve is arranged at the outlet, 5-10 groups of baffle plates are arranged in the cylinder body of the dechlorination device, and the baffle plates form an included angle of 45-60 degrees with the horizontal line.
The invention provides a phosphorus pentachloride continuous synthesis device, which comprises: a phosphorus trichloride intermediate tank; the lower outlet of the phosphorus trichloride middle tank is connected with the inlet of the phosphorus trichloride circulating pump; the outlet of the phosphorus trichloride circulating pump is respectively connected with the liquid phase inlet of the falling film absorption tower and the liquid phase inlet of the falling film reactor, the falling film reactor is provided with a chlorine inlet, and the liquid phase inlet of the falling film reactor is respectively connected with the liquid phase outlets of the solid-liquid separator and the intermediate condensers 1 and 2; the solid phase outlet of the solid-liquid separator is connected with the solid phase inlet of the primary continuous devolatilizer through a rotary valve; the outlet of the falling film reactor is connected with a settler, the lower outlet of the settler is connected with the inlet of a slurry conveying device, and the outlet of the slurry conveying device is connected with the inlet of a solid-liquid separator; the solid phase outlet of the first-stage continuous devolatilizer is connected with the inlet of the downstream second-stage continuous devolatilizer, the gas phase outlet of the second-stage continuous devolatilizer is connected with the gas phase inlet of the falling film absorption tower, and the gas phase outlet of the falling film absorption tower is connected with the inlet of the tail gas fan; the solid phase outlet of the secondary continuous devolatilizer is connected with the inlet of the continuous devolatilizer through an upper rotary valve; the gas phase outlets of the falling film reactor, the first-stage continuous devolatilizer and the settler are connected with the gas phase inlets of the intercondensers 1 and 2; the gas phase outlets of the intermediate condensers 1 and 2, the outlet of the tail gas fan and the dechlorination device are connected with the gas phase inlet of the tail gas condenser; and a gas phase outlet of the tail gas condenser is connected with the tail gas absorption tower. The continuous phosphorus pentachloride synthesizing device provided by the invention can improve the production efficiency of phosphorus pentachloride, improve the control reliability of the device, reduce the risk of safe production of the device and reduce the occupational health risk of the phosphorus pentachloride production process.
Referring to fig. 2, fig. 2 is a schematic structural diagram of a continuous synthesis device for phosphorus pentachloride according to an embodiment of the present invention; wherein, (1) is a slurry conveying device, (2) is a settler, (3) is a falling film reactor, (4) is a solid-liquid separator, (5) is an intermediate condenser 1, (6) is an intermediate condenser 2, (7) is a primary continuous devolatilizer, (8) is a tail gas fan, (9) is a secondary continuous devolatilizer, (10) is a continuous dechlorination device, (11) is a phosphorus trichloride circulating pump, (12) is a phosphorus trichloride intermediate tank, (13) is a falling film absorption tower, (14) is a tail gas condenser, (15) is a tail gas absorption tower, (16) is an upper rotary valve, (17) is a lower rotary valve, and (18) is a solid-liquid separation discharging rotary valve.
The main connection relation of the device is as follows: the device is provided with a phosphorus trichloride middle tank (12), the lower outlet of the phosphorus trichloride middle tank (12) is connected with the inlet of a phosphorus trichloride circulating pump (11), the outlet of the phosphorus trichloride circulating pump (11) is respectively connected with the liquid phase inlet of a falling film absorption tower (13) and the liquid phase inlet of a falling film reactor (3), the falling film reactor (3) is provided with a chlorine gas inlet, the liquid phase inlet of the falling film reactor (3) is respectively connected with the liquid phase outlets of a solid-liquid separator (4) and intermediate condensers 1 and 2, and the solid phase outlet of the solid-liquid separator (4) is connected with the solid phase inlet of a first-stage continuous devolatilizer (7) through a solid-liquid separation discharging rotary valve (18); the outlet of the falling film reactor (3) is connected with the settler (2), the lower outlet of the settler (2) is connected with the inlet of the slurry conveying device (1), and the outlet of the slurry conveying device (1) is connected with the inlet of the solid-liquid separator (4); the solid phase outlet of the first-stage continuous devolatilizer (7) is connected with the inlet of the downstream second-stage continuous devolatilizer (9), the gas phase outlet of the second-stage continuous devolatilizer (9) is connected with the gas phase inlet of the falling film absorption tower (13), and the gas phase outlet of the falling film absorption tower (13) is connected with the inlet of the tail gas fan; the solid phase outlet of the second-stage continuous devolatilizer (9) is connected with the inlet of the continuous dechlorination device (10) through an upper rotary valve (16), and the outlet of the continuous dechlorination device (10) is unpacked through a lower rotary valve; the falling film reactor (3), the first-stage continuous devolatilizer (7) and the gas phase outlet of the settler (2) are connected with the gas phase inlets of the intermediate condensers (5) and (6), the gas phase outlets of the intermediate condensers (5) and (6), the outlet of the tail gas fan (8), the dechlorination device (10) is connected with the gas phase inlet of the tail gas condenser (14), and the gas phase outlet of the condenser (14) is connected with the tail gas absorption tower (15).
The main working process of the device is as follows: the phosphorus trichloride and the chlorine continuously enter a falling film reactor (3) for reaction, the mixture automatically flows into a settler (2), phosphorus pentachloride crystals are settled in the settler (2), the phosphorus pentachloride crystals are conveyed into a solid-liquid separator (4) for solid-liquid separation by a slurry conveying device (1), phosphorus trichloride liquid flows back to the falling film reactor (3), the solid phosphorus pentachloride enters a first-stage continuous devolatilizer (7) through a solid-liquid separation discharging rotary valve (18) to remove phosphorus trichloride attached to the surface of the phosphorus pentachloride, the first-stage continuous devolatilizer (7) discharges to a second-stage continuous devolatilizer (9) to further remove phosphorus trichloride in the phosphorus pentachloride, the second-stage continuous devolatilizer (9) discharges to a continuous antichlor (10) through an upper rotary valve (16) to remove the chlorine attached to the surface of the phosphorus pentachloride, and the phosphorus pentachloride is discharged through a lower rotary valve (17) to obtain qualified phosphorus pentachloride products.
The invention provides a continuous synthesis process and a device of phosphorus pentachloride; the process comprises the following steps: a) Reacting phosphorus trichloride with chlorine in a falling film reactor to obtain phosphorus trichloride and phosphorus pentachloride mixture slurry, condensing generated gas phase and then refluxing to the falling film reactor for reuse; b) Settling the phosphorus trichloride and phosphorus pentachloride mixture slurry obtained in the step a) in a settling vessel, continuously feeding the obtained crystal slurry into a solid-liquid separator through a slurry conveying device for solid-liquid separation to respectively obtain liquid-phase phosphorus trichloride which flows back to a falling film reactor, and flows back to the falling film reactor for reuse after gas-phase condensation, and solid-phase phosphorus pentachloride; condensing the gas phase obtained by sedimentation and then refluxing to the falling film reactor for reuse; c) Allowing the solid-phase phosphorus pentachloride obtained in the step b) to enter a first-stage continuous devolatilizer to remove phosphorus trichloride, condensing the obtained gas phase, refluxing to a falling film reactor for recycling, allowing the obtained phosphorus pentachloride product to enter a second-stage continuous devolatilizer to react with excessive chlorine, and further removing phosphorus trichloride attached to the surface of phosphorus pentachloride crystals to obtain refined phosphorus pentachloride; unreacted chlorine is absorbed by a falling film absorption tower, a small amount of phosphorus pentachloride is generated to flow back to a phosphorus trichloride middle tank along with phosphorus trichloride, and the phosphorus trichloride is conveyed to a falling film reactor for reuse by a phosphorus trichloride circulating pump; d) Removing chlorine attached to the crystal surface of the refined phosphorus pentachloride obtained in the step c) through a continuous dechlorination device to obtain a phosphorus pentachloride product; e) And c) condensing the tail gas generated after the condensation of the steps a), b) and c) through a tail gas condenser to recover phosphorus trichloride, and absorbing the phosphorus trichloride through a tail gas absorption tower. Compared with the prior art, the phosphorus pentachloride continuous synthesis process and the device provided by the invention realize better overall interaction through specific process steps under specific structures and continuous relations, can realize continuous production, have high efficiency and stable and controllable product quality, and can solve the problems of poor process stability, high safety risks in shutdown maintenance and production processes, non-ideal occupational health environment, high environmental protection tail gas treatment operation cost and the like in the existing phosphorus pentachloride production process.
In order to further illustrate the present invention, the following examples are provided. The raw materials used in the following examples of the present invention are all generally commercially available.
Examples
Referring to fig. 1-2, fig. 1 is a flow chart of a continuous synthesis process of phosphorus pentachloride provided by an embodiment of the invention, and fig. 2 is a schematic structural diagram of a continuous synthesis device of phosphorus pentachloride provided by an embodiment of the invention; in fig. 2, (1) is a slurry transporting device, (2) is a settler, (3) is a falling film reactor, (4) is a solid-liquid separator, (5) is an intermediate condenser 1, (6) is an intermediate condenser 2, (7) is a primary continuous devolatilizer, (8) is a tail gas fan, (9) is a secondary continuous devolatilizer, (10) is a continuous dechlorination device, (11) is a phosphorus trichloride circulating pump, (12) is a phosphorus trichloride intermediate tank, (13) is a falling film absorption tower, (14) is a tail gas condenser, (15) is a tail gas absorption tower, (16) is an upper rotary valve, (17) is a lower rotary valve, and (18) is a solid-liquid separation discharging rotary valve.
The test was carried out according to the continuous synthesis process and apparatus of phosphorus pentachloride described in fig. 1 to 2, and the specific process is as follows:
Preparing 400Kg (steel bottle) of raw material chlorine, and adding 200Kg of phosphorus trichloride into a phosphorus trichloride intermediate tank (12);
adding phosphorus trichloride and chlorine into the falling film reactor (3) for reaction at the same time, wherein the continuous adding speed of the phosphorus trichloride is controlled to be 20Kg/h (12.8L/h) by a phosphorus trichloride circulating pump (11), the continuous introducing flow of the chlorine is controlled to be 2.2m 3/h, and the temperature of the falling film reactor (3) is controlled to be 55 ℃ and the reaction pressure is controlled to be 0.5KPa;
The obtained phosphorus trichloride and phosphorus pentachloride mixture slurry is settled in a settler (2), the temperature of the settler (2) is 55 ℃, the pressure is 0.5KPa, and the stirring speed is 35rpm; after the obtained gas phase is condensed by the intermediate condenser 2 (6), the condensing temperature of the intermediate condenser 2 (6) is 12 ℃, the pressure is 0KPa, the liquid phase flows back to the falling film reactor (3), the tail gas flows back to the phosphorus trichloride intermediate tank (12) after passing through the tail gas condenser (14), and the waste gas is discharged into the tail gas absorption tower (15) and absorbed by the absorption liquid;
The mixed slurry of the phosphorus trichloride and the phosphorus pentachloride continuously enters a solid-liquid separator (4) through a slurry conveying device (1), the feeding flow is controlled to be 9-14L/h, the temperature of the solid-liquid separator (4) is 55 ℃, and the pressure is 0.3KPa; separating by a solid-liquid separator (4), and refluxing the separated liquid-phase phosphorus trichloride to a falling film reactor (3) (the refluxing phosphorus trichloride contains a small amount of phosphorus pentachloride), wherein the separated solid phosphorus pentachloride enters a first-stage continuous devolatilizer (7) through a solid-liquid separation discharging rotary valve (18) by a solid-phase outlet (the solid phosphorus pentachloride also contains a small amount of phosphorus trichloride);
The phosphorus pentachloride product obtained in the steps enters a first-stage continuous devolatilizer (7), phosphorus trichloride in the phosphorus pentachloride is distilled by heating, the heating temperature of the first-stage continuous devolatilizer (7) is 81 ℃, the pressure in the device is 0.5KPa, materials stay in the first-stage continuous devolatilizer (7) for 6min, the distilled phosphorus trichloride is condensed by an intermediate condenser 1 (5) and then flows back to a falling film reactor (3), the condensing temperature of the intermediate condenser 1 (5) is 12 ℃, and the pressure is 0KPa;
the phosphorus pentachloride product obtained in the steps is sent to a secondary continuous devolatilizer (9), a certain amount of chlorine is introduced, the flow rate of the introduced chlorine is 200L/h, the phosphorus pentachloride product reacts with a small amount of phosphorus trichloride contained in the phosphorus pentachloride to remove the phosphorus trichloride, and the phosphorus pentachloride is further refined to obtain a high-quality phosphorus pentachloride product; the temperature in the secondary continuous devolatilizer (9) is controlled at 55 ℃, the pressure is 0-2 KPa, and the materials stay in the secondary continuous devolatilizer (9) for 3min;
In the step two-stage continuous devolatilizer (9), redundant chlorine is discharged to a falling film absorption tower (13) from a gas phase outlet of the step two-stage continuous devolatilizer (9), a small amount of phosphorus pentachloride is generated by the absorption of phosphorus trichloride in the falling film absorption tower (13) and is returned to the falling film reactor (3) for reutilization, the temperature of the falling film absorption tower (13) is 15 ℃, the pressure is-0.2 KPa, the circulating flow of the phosphorus trichloride is 124L/h, and the gas phase obtained by the falling film absorption tower (13) enters the same tail gas condenser (14) after passing through a tail gas fan (8);
The obtained phosphorus pentachloride product is conveyed into a continuous dechlorination device (10) through an upper rotary valve (16) by a second-stage continuous devolatilizer (9), a small amount of impurities such as chlorine and the like are removed by carbon dioxide, the dechlorination temperature is controlled at 45 ℃, the pressure is controlled at 5KPa, and a qualified phosphorus pentachloride product is obtained and is output through a lower rotary valve and then packaged; the exhaust gas is discharged into an exhaust gas absorption tower (15) and absorbed by the absorption liquid.
The phosphorus pentachloride continuous synthesis process and the device provided by the embodiment of the invention have good continuity in the test process, the problems of unsmooth transportation of blocked materials and the like do not occur in the middle, and particularly in the shutdown process, the system basically has no chlorine; through testing, the obtained phosphorus pentachloride has the content of more than 99.5 percent, the phosphorus trichloride content is less than or equal to 0.05 percent, the crystal granularity is uniform, and the product yield is more than 95 percent, which is shown in the following table 1.
TABLE 1 repeated experimental results of continuous synthesis process and apparatus for phosphorus pentachloride provided by the examples of the invention
| Sample numbering | Phosphorus trichloride content | Phosphorus pentachloride content | Remarks (quality standard) |
| 1 | Not detected | 99.52％ | Phosphorus trichloride is less than or equal to 0.05 percent |
| 2 | Not detected | 99.57％ | Phosphorus trichloride is less than or equal to 0.05 percent |
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A continuous synthesis process of phosphorus pentachloride comprises the following steps:
a) Reacting phosphorus trichloride with chlorine in a falling film reactor to obtain phosphorus trichloride and phosphorus pentachloride mixture slurry, condensing generated gas phase and then refluxing to the falling film reactor for reuse;
b) Settling the phosphorus trichloride and phosphorus pentachloride mixture slurry obtained in the step a) in a settling vessel, continuously feeding the obtained crystal slurry into a solid-liquid separator through a slurry conveying device for solid-liquid separation to respectively obtain liquid-phase phosphorus trichloride which flows back to a falling film reactor, and flows back to the falling film reactor for reuse after gas-phase condensation, and solid-phase phosphorus pentachloride; condensing the gas phase obtained by sedimentation and then refluxing to the falling film reactor for reuse;
c) Allowing the solid-phase phosphorus pentachloride obtained in the step b) to enter a first-stage continuous devolatilizer to remove phosphorus trichloride, condensing the obtained gas phase, refluxing to a falling film reactor for recycling, allowing the obtained phosphorus pentachloride product to enter a second-stage continuous devolatilizer to react with excessive chlorine, and further removing phosphorus trichloride attached to the surface of phosphorus pentachloride crystals to obtain refined phosphorus pentachloride; unreacted chlorine is absorbed by a falling film absorption tower, a small amount of phosphorus pentachloride is generated to flow back to a phosphorus trichloride middle tank along with phosphorus trichloride, and the phosphorus trichloride is conveyed to a falling film reactor for reuse by a phosphorus trichloride circulating pump;
d) Removing chlorine attached to the crystal surface of the refined phosphorus pentachloride obtained in the step c) through a continuous dechlorination device to obtain a phosphorus pentachloride product;
e) And c) condensing the tail gas generated after the condensation of the steps a), b) and c) through a tail gas condenser to recover phosphorus trichloride, and absorbing the phosphorus trichloride through a tail gas absorption tower.
2. The continuous synthesis process of phosphorus pentachloride according to claim 1, wherein the feed molar ratio of phosphorus trichloride to chlorine in step a) is 1: (0.4-4.5).
3. The continuous synthesis process of phosphorus pentachloride according to claim 1, wherein the temperature of the reaction in step a) is 40 ℃ to 75 ℃ and the pressure is 0.1KPa to 20KPa.
4. The continuous synthesis process of phosphorus pentachloride according to claim 1, wherein in step b), the sedimentation temperature is 40 to 75 ℃, the pressure is 0.1 to 20KPa, and the stirring speed is 3 to 60rpm.
5. The continuous synthesis process of phosphorus pentachloride according to claim 1, wherein the flow rate of the solid-liquid separation in the step b) is 3-15L/h, the temperature is 40-75 ℃, and the pressure is 0.1-1 KPa.
6. The continuous synthesis process of phosphorus pentachloride according to claim 1, wherein in the step c), the temperature for removing phosphorus trichloride in the primary continuous devolatilizer is 75-90 ℃, the pressure is 0.4-20 KPa, and the residence time is 5-10 min.
7. The continuous synthesis process of phosphorus pentachloride according to claim 1, wherein in step c), the temperature of the reaction of the excess chlorine gas with the secondary continuous devolatilizer is 40 ℃ to 75 ℃, the pressure is-5 KPa to 10KPa, and the residence time is 1min to 5min.
8. The continuous synthesis process of phosphorus pentachloride according to claim 1, wherein in step c), the temperature absorbed by the falling film absorption tower is 5 ℃ to 25 ℃ and the pressure is-5 KPa to-0.1 KPa.
9. The continuous synthesis process of phosphorus pentachloride according to claim 1, wherein in the step d), the temperature for removing chlorine attached to the crystal surface through the continuous dechlorination device is 30-55 ℃, and the pressure is 1-8 KPa.
10. A phosphorus pentachloride continuous synthesis device, comprising:
a falling film reactor; the falling film reactor is provided with a chlorine inlet and a phosphorus trichloride inlet; the phosphorus trichloride inlet is also connected with an intermediate condenser;
a settler with a feed inlet connected with a discharge outlet of the falling film reactor;
The slurry conveying device is connected with the discharge port of the settler;
The solid-liquid separator is connected with the discharge port of the slurry conveying device; the liquid phase outlet of the solid-liquid separator is connected with the phosphorus trichloride inlet of the falling film reactor, and the gas phase outlet is connected with the phosphorus trichloride inlet of the falling film reactor through the intermediate condenser;
a first-stage continuous devolatilizer with a feed inlet connected with a solid-phase outlet of the solid-liquid separator; the gas phase outlet of the first-stage continuous devolatilizer is connected with the phosphorus trichloride inlet of the falling film reactor through an intermediate condenser;
a second-stage continuous devolatilizer with a feed inlet connected with a solid phase outlet of the first-stage continuous devolatilizer; the secondary continuous devolatilizer is provided with a chlorine inlet, a chlorine outlet and a phosphorus pentachloride outlet; the chlorine outlet is also connected with a falling film absorption tower; the phosphorus pentachloride outlet is sequentially connected with an upper rotary valve, a continuous dechlorination device and a lower rotary valve;
A phosphorus trichloride middle tank with a feed inlet connected with a liquid phase outlet of the falling film absorption tower; the phosphorus trichloride intermediate tank is connected with a phosphorus trichloride inlet of the falling film reactor through a phosphorus trichloride circulating pump;
The tail gas condenser is connected with the tail gas outlet of the intermediate condenser through the gas inlet; the liquid phase outlet of the tail gas condenser is connected with the feeding port of the phosphorus trichloride middle tank, and the gas phase outlet is also connected with a tail gas absorption tower.
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| CN102320584A (en) * | 2011-10-26 | 2012-01-18 | 核工业理化工程研究院华核新技术开发公司 | Method for preparing phosphorus pentafluoride |
| CN202246070U (en) * | 2011-06-16 | 2012-05-30 | 江苏大明科技有限公司 | Production system for synthesizing orthophosphorous acid by hydrolyzing phosphorus trichloride |
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| DE3008194A1 (en) * | 1980-03-04 | 1981-09-17 | Hoechst Ag, 6000 Frankfurt | METHOD FOR PRODUCING PHOSPHORPENTACHLORIDE |
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| CN202246070U (en) * | 2011-06-16 | 2012-05-30 | 江苏大明科技有限公司 | Production system for synthesizing orthophosphorous acid by hydrolyzing phosphorus trichloride |
| CN102320584A (en) * | 2011-10-26 | 2012-01-18 | 核工业理化工程研究院华核新技术开发公司 | Method for preparing phosphorus pentafluoride |
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