CN215799248U - Preparation system for methyl phosphorus dichloride - Google Patents
Preparation system for methyl phosphorus dichloride Download PDFInfo
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- CN215799248U CN215799248U CN202121954249.8U CN202121954249U CN215799248U CN 215799248 U CN215799248 U CN 215799248U CN 202121954249 U CN202121954249 U CN 202121954249U CN 215799248 U CN215799248 U CN 215799248U
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Abstract
The utility model discloses a preparation system for methyl phosphorus dichloride, and belongs to the technical field of synthesis of organophosphorus compound intermediates. The device comprises a reaction kettle, a first gas-liquid separator, a condenser and a second gas-liquid separator, wherein the reaction kettle is connected with a yellow phosphorus feeding pipe, a phosphorus trichloride feeding pipe, a chloromethane feeding pipe and a catalyst feeding pipe; the reaction kettle is connected with a first gas-liquid separator, the first gas-liquid separator is connected with a condenser, and the condenser is connected with a product tank; the condenser is connected with the second gas-liquid separator, and the second gas-liquid separator is connected with the product tank. Taking yellow phosphorus, phosphorus trichloride and chloromethane as raw materials, and reacting in a reaction kettle in one step under the action of a catalyst to obtain a product, namely methyl phosphorus dichloride; the method can effectively ensure the reaction conversion rate and the product purity, has reasonable equipment arrangement, can better link up the preparation process, has less related equipment quantity, adopts full-automatic DCS control, and has reliable safety.
Description
Technical Field
The utility model relates to a preparation system for methyl phosphorus dichloride, and belongs to the technical field of synthesis of organophosphorus compound intermediates.
Background
Methyl phosphorus dichloride is an important intermediate for synthesizing an organophosphorus compound, and has extremely wide application. Methyl phosphorus dichloride can directly or indirectly synthesize hundreds of organic phosphorus compounds, and the reaction taking the methyl phosphorus dichloride as an initiator has extremely high conversion rate, and most reactions are carried out quantitatively; in addition, methyl phosphorus dichloride is an important intermediate for synthesizing glufosinate-ammonium, and the yield of the glufosinate-ammonium is directly determined. Therefore, the methyl phosphorus dichloride has very wide market prospect.
At present, the main synthetic methods of methyl phosphorus dichloride include a methyl aluminum sesquichloride method (an aluminum method) and a methane method. The methyl sesquialuminum method is a domestic mainstream method for producing methyl phosphorus dichloride, aluminum powder is used as a raw material and reacts with chloromethane to obtain methyl sesquialuminum, then the methyl sesquialuminum and phosphorus trichloride undergo a complex reaction to obtain a complex, and finally the methyl phosphorus dichloride is obtained after dissociation of substances such as alkali metal salt and the like. The reaction conditions are mild, but the operation is complicated, the problems of transfer of flammable intermediates, conveying of high-viscosity materials and the like are involved, the separation cannot be thorough because the product is subjected to solid-liquid separation, the yield of the obtained product is low, the cost is high, a large amount of solid waste residues (mainly sodium tetrachloroaluminate) are generated, the process environmental protection pressure is high, and certain safety risk is realized;
the preparation method comprises the following steps of (1) reacting aluminum powder with chloromethane to generate methyl sesquialuminum, reacting with phosphorus trichloride to obtain a complex (complex for short) of methyl phosphorus dichloride and aluminum trichloride, and reacting with a decomplexing agent to obtain free methyl phosphorus dichloride, wherein the reaction formula is as follows:
(CH3)3Al2Cl3+3PCl3→3CH3PCl2·2AlCl3
3CH3PCl2·2AlCl3+2NaCl→3CH3PCl2+2NaAlCl4。
the methane method is the best synthesis method reported in the literature at present, and specifically comprises the following steps: phosphorus trichloride and methane are subjected to catalytic reaction at high temperature by a catalyst to obtain methyl phosphorus dichloride. The atom utilization rate is high, the reaction is a gas phase reaction, the process is simple, the whole process can be continuous, but the reaction temperature is as high as 500-600 ℃, the requirement on equipment materials is very high, meanwhile, the concentration of the methyl phosphorus dichloride in a reaction product is only 20-25%, the single-pass conversion rate is low, the separation of the phosphorus trichloride and the methyl phosphorus dichloride is difficult, the process has very strict requirements on safety and operation control in the production process on the whole, and the large-scale production is not successfully formed at home at present;
wherein, methane and phosphorus trichloride react under the condition of high-temperature high-pressure catalyst to obtain methyl phosphorus dichloride, and dimethyl compounds and the like are generated at the same time, and the reaction formula is as follows:
CH4+PCl3→CH3PCl2+(CH3) 2PCl。
in addition, the synthesis method of the methyl phosphorus dichloride further comprises the following steps: using dichloromethane and the like as solvents, reacting chloromethane, aluminum trichloride and phosphorus trichloride at the temperature of 80 ℃ to generate a ligand, dissolving the ligand in diethyl phthalate (DEP), adding aluminum powder at the temperature of 70 ℃, reducing and distilling to obtain a product, namely methyl phosphorus dichloride.
The prior art "CN 111909201A a method for synthesizing methyl phosphorus dichloride" discloses: mainly aiming at the problems of high reaction temperature, certain reaction pressure, easy generation of solid impurities, low continuous production capacity, high cost, large environmental pressure and the like in the process of synthesizing the methyl phosphorus dichloride by the high-temperature method at present, the method for synthesizing the methyl phosphorus dichloride by using methane and phosphorus trichloride as raw materials and reacting under the action of ultraviolet illumination is provided, the method maintains the reaction selectivity and yield, does not add a toxic initiator, reduces the conditions of pressure, temperature and the like required by the reaction, avoids the problem of reduction of reaction conversion rate caused by inactivation due to the fact that the surface of a solid catalyst is covered, has higher continuous degree, can synthesize and obtain a product with the content of the methyl phosphorus dichloride of more than 17wt%, and can obtain the methyl phosphorus dichloride product with the content of more than 99wt% and the phosphorus trichloride with the content of more than 98.5wt% after the product is rectified. In the technical scheme, methane and phosphorus trichloride are used as raw materials, and methyl phosphorus dichloride is synthesized under the catalysis of ultraviolet light, although parameters such as reaction pressure, temperature and the like are reduced, the concentration of a reaction product is not high, the mixture of phosphorus trichloride and methyl phosphorus dichloride needs to be further rectified and separated, the process is complex, the energy consumption is high, and the requirement on equipment is very high.
The preparation method and the preparation system for synthesizing the methyl phosphorus dichloride by the one-step method of CN112028937A are disclosed in the specification: the preparation method and the preparation system for synthesizing the methyl phosphorus dichloride through the one-step method comprise the following steps: aluminum powder, phosphorus trichloride, sodium chloride, a reaction solvent and a catalyst are put into a reaction device, air in the reaction device is replaced by nitrogen, chloromethane is introduced into the reaction device for mixed reaction, and the methyl phosphorus dichloride is obtained after a reaction product is distilled and condensed. The utility model discloses a preset reaction raw materials Al, PCl3 and NaCl in reaction unit, then carry out nitrogen gas replacement, stir the abundant dispersion suspension after, let in the gaseous reaction that reacts of methyl chloride, according to the flow that lets in of reaction temperature control methyl chloride, control is convenient, and the security is high, and whole production efficiency and product yield are higher. After the reaction is finished, a methyl phosphorus dichloride product is obtained by condensation. In the technical scheme, aluminum powder, chloromethane and phosphorus trichloride are used as raw materials to react and distill to obtain methyl phosphorus dichloride, after multi-step reaction is changed into one-step reaction, the aluminum powder, the phosphorus trichloride, the methyl sesquialuminum and the methyl phosphorus dichloride exist in the same system in the reaction process, the activity of the side reaction of the methyl phosphorus dichloride and the methyl sesquialuminum is higher than that of the phosphorus trichloride, and the methyl sesquialuminum generated in the middle and later stages of the reaction is easy to continuously react with the methyl phosphorus dichloride generated in the earlier stage to generate impurities such as dimethyl phosphorus chloride and the like; the patent needs further verification on the reaction mechanism and the industrial value; on the other hand, the patent scheme also generates solid waste slag such as sodium tetrachloroaluminate and the like finally, and the solid waste slag needs further treatment, so that the atom economy is not high.
Disclosure of Invention
The utility model aims to overcome the defects of the prior art and provides a preparation system for methyl phosphorus dichloride. In the technical scheme, through the arrangement of a preparation system comprising a reaction kettle, a first gas-liquid separator, a condenser and a second gas-liquid separator, yellow phosphorus, phosphorus trichloride and methyl chloride are taken as raw materials and are subjected to one-step reaction in the reaction kettle under the action of a catalyst to obtain a product, namely methyl phosphorus dichloride; the method can effectively ensure the reaction conversion rate and the product purity, and simultaneously ensures that the preparation method has no solid waste residue and harmful tail gas, is green and environment-friendly, and has reliable safety.
In order to achieve the technical purpose, the following technical scheme is proposed:
a preparation system of methyl phosphorus dichloride comprises a reaction kettle for material reaction, a first gas-liquid separator for separating yellow phosphorus, a condenser and a second gas-liquid separator for separating methyl chloride, wherein the reaction kettle is connected with a yellow phosphorus feeding pipe, a phosphorus trichloride feeding pipe, a methyl chloride feeding pipe and a catalyst feeding pipe;
the reaction kettle is connected with a first gas-liquid separator through an external discharge pipe, a liquid phase outlet on the first gas-liquid separator is connected with the reaction kettle through a return pipe, and a yellow phosphorus recycling passage is formed among the external discharge pipe, the first gas-liquid separator and the return pipe;
a gas phase outlet on the first gas-liquid separator is connected with a condenser, and a liquid phase outlet on the condenser is connected with a product tank for collecting the methyl phosphorus dichloride product through a discharge pipe;
and a gas-phase outlet on the condenser is connected with a second gas-liquid separator, and a liquid-phase outlet on the second gas-liquid separator is connected with the product tank through a discharge pipe.
Preferably, the gas-phase outlet of the second gas-liquid separator is connected with a methyl chloride recovery tank through a recovery pipe.
Preferably, a pressure transmitter is arranged on the reaction kettle, and a stirrer is arranged in the reaction kettle.
Preferably, the number of the condensers is at least two, and the condensers are arranged in series. The specific number of condensers and the corresponding pipeline arrangement can be set according to actual requirements, and then the efficiency and the purity of product recovery are guaranteed.
Preferably, the return pipe is provided with a U-shaped liquid seal pipe I to prevent gas phases of phosphorus trichloride, methyl phosphorus dichloride, dimethyl phosphorus chloride and methyl chloride from overflowing into the reaction kettle from the return pipe.
Preferably, be provided with on the discharging pipe and be U type liquid seal pipe II, prevent that chloromethane gaseous phase from overflowing to the product jar in the discharging pipe.
Preferably, the preparation system is controlled by DCS.
The positional relationships such as "between" and "on" in the present technical solution are defined according to the actual usage state, and are conventional terms in the technical field and also conventional terms in the actual usage process by those skilled in the art.
In the description of the present technical solution, it should be noted that, unless explicitly stated or limited otherwise, the terms "disposed" and "connected" should be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
By adopting the technical scheme, the beneficial technical effects brought are as follows:
in the utility model, a corresponding preparation system is designed according to the characteristics of reaction materials (yellow phosphorus, phosphorus trichloride and chloromethane) and a product (methyl phosphorus dichloride), and the preparation system can be better matched with a preparation process, so that the simple reaction process and the high reaction speed are ensured, and the preparation cycle time is one third of that of the prior art (the traditional aluminum method);
in the preparation process, no intermediate with high activity is generated, no solid waste residue or tail gas is generated, the green level of the preparation process is greatly improved, and the environment-friendly level is high;
in the preparation system, equipment is reasonably arranged, the preparation process can be better linked, the number of related equipment is small, and the safety is reliable by adopting full-automatic DCS control;
in the utility model, the related product of methyl phosphorus dichloride is not rectified, and the content can reach more than 94 percent.
Drawings
FIG. 1 is a schematic diagram of the working principle of the present invention;
in the figure, 1, a reaction kettle, 2, a first gas-liquid separator, 3, a condenser, 4, a second gas-liquid separator, 5, a yellow phosphorus feeding pipe, 6, a phosphorus trichloride feeding pipe, 7, a chloromethane feeding pipe, 8, a catalyst feeding pipe, 9, an external discharge pipe, 10, a return pipe, 11, a discharge pipe, 12, a pressure transmitter, 13, a stirrer, 14, a liquid seal pipe I, 15, a liquid seal pipe II, 16, a recovery pipe, 17, a chloromethane recovery tank, 18 and a product tank.
Detailed Description
In the following, the technical solutions in the embodiments of the present invention are clearly and completely described, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The embodiment provides a preparation system of methyl phosphorus dichloride (as shown in fig. 1), which adopts DCS control and comprises a reaction kettle 1 for material reaction, a first gas-liquid separator 2 for separating yellow phosphorus, a condenser 3 and a second gas-liquid separator 4 for separating methyl chloride, wherein the reaction kettle 1 is connected with a yellow phosphorus feeding pipe 5, a phosphorus trichloride feeding pipe 6, a methyl chloride feeding pipe 7 and a catalyst feeding pipe 8;
the reaction kettle 1 is connected with the first gas-liquid separator 2 through an external discharge pipe 9, a liquid phase outlet on the first gas-liquid separator 2 is connected with the reaction kettle 1 through a return pipe 10, and a yellow phosphorus recycling passage is formed among the external discharge pipe 9, the first gas-liquid separator 2 and the return pipe 10;
a gas phase outlet on the first gas-liquid separator 2 is connected with a condenser 3, and a liquid phase outlet on the condenser 3 is connected with a product tank 18 for collecting the methyl phosphorus dichloride product through a discharge pipe 11;
the gas phase outlet of the condenser 3 is connected with the second gas-liquid separator 4, the liquid phase outlet of the second gas-liquid separator 4 is connected with the product tank 18 through the discharge pipe 11, and the gas phase outlet of the second gas-liquid separator 4 is connected with the methyl chloride recovery tank 17 through the recovery pipe 16.
Wherein, a pressure transmitter 12 is arranged on the reaction kettle 1, and a stirrer 13 is arranged in the reaction kettle 1.
The number of the condensers 3 is three, and the condensers 3 are arranged in series. Wherein, the specific quantity and the corresponding pipeline arrangement of condenser 3 still can set up according to actual demand, and then guarantees the efficiency and the purity of product recovery.
A U-shaped liquid seal pipe I14 is arranged on the return pipe 10 to prevent gas phases of phosphorus trichloride, methyl phosphorus dichloride, dimethyl phosphorus chloride and methyl chloride from overflowing from the return pipe 10 into the reaction kettle 1.
The discharge pipe 11 is provided with a U-shaped liquid seal pipe II 15 to prevent the gas phase of the chloromethane from overflowing from the discharge pipe 11 to the product tank 18.
According to the actual demand, yellow phosphorus inlet pipe 5, phosphorus trichloride inlet pipe 6, chloromethane inlet pipe 7 and catalyst inlet pipe 8 are provided with flowmeter and governing valve, and the flowmeter interlocks with the governing valve, guarantees that the feeding process is controllable, stable going on, and then improves methyl phosphorus dichloride conversion efficiency and quality.
Example 2
Based on example 1, this example provides a method for preparing methylphosphorus dichloride, including:
A. according to the measurement, catalyst is introduced into the reaction kettle 1 through a catalyst feeding pipe 8; liquid yellow phosphorus is introduced into the reaction kettle 1 through a yellow phosphorus feeding pipe 5, and liquid phosphorus trichloride is introduced into the reaction kettle 1 through a phosphorus trichloride feeding pipe 6; wherein, the catalyst, the yellow phosphorus and the phosphorus trichloride do not react after being mixed;
wherein the molar ratio of the yellow phosphorus to the phosphorus trichloride is 1: 0.24-0.55, and the molar ratio of the yellow phosphorus to the chloromethane is 1: 0.75-1.5. Wherein, the molar ratio between the materials is set, so that higher yield can be obtained. Such as: the molar amount of phosphorus trichloride is low, and the content of the byproduct dimethyl phosphorus chloride in the reaction system is higher, namely an ideal reaction effect cannot be achieved; the dosage of phosphorus trichloride is higher, which affects the subsequent separation and purification. For another example: the dosage of chloromethane is low, the reaction is incomplete, and the conversion rate is low (namely, the reaction is not continued after the conversion rate of the system reaches a certain degree); the dosage of the chloromethane is higher, and the chloromethane does not contribute to the reaction obviously;
the catalyst is transition metal or compound thereof, or mixture of any two or more, such as: any one or more of copper powder, copper oxide, cuprous oxide and ruthenium chloride. Wherein, the catalyst and a material or a certain reaction intermediate form a transition metal organic complex intermediate which is easy to react, namely, the reaction activation energy is reduced and the reaction speed is accelerated; the catalyst D90 is 300 mesh, wherein, the particle size is limited, mainly the comprehensive production cost and the reaction effect. Such as: the catalyst can be more uniformly dispersed in a mixed system of yellow phosphorus and phosphorus trichloride; and ensures large specific surface and high catalytic activity.
B. Sealing the reaction kettle 1, and controlling the temperature in the reaction kettle 1 to be 250-350 ℃; introducing methyl chloride gas into the reaction kettle 1 through a methyl chloride feed pipe 7 until the pressure in the reaction kettle 1 is 4-10 Mpa, and reacting for 3-6 h;
wherein, when the temperature in the reaction kettle 1 is 200 ℃, the pressure of the chloromethane can reach 14.64 MPa; the reaction pressure is controlled by the introduction amount and pressure of the chloromethane, and the reaction temperature is controlled by the heat-conducting oil; the further limitation of temperature, pressure and reaction time promotes complete material conversion in the reaction process, improves the controllability and safety of the working procedures and controls the duration of the preparation period.
C. After the reaction is finished, stopping introducing the chloromethane into the reaction kettle 1; flash evaporation and discharge are carried out to obtain a gas phase I (wherein, a small amount of yellow phosphorus liquid film, raw material phosphorus trichloride and byproduct dimethyl phosphorus chloride are contained, and a large amount of raw material methyl chloride and product methyl phosphorus dichloride are contained);
introducing the gas phase I into the first gas-liquid separator 2 through an outer discharge pipe 9; separating by a first gas-liquid separator 2 to obtain yellow phosphorus liquid and a gas phase II (wherein, the yellow phosphorus liquid may contain a small amount of raw material phosphorus trichloride and a byproduct dimethyl phosphorus chloride, and contains a large amount of raw material methyl chloride and a product methyl phosphorus dichloride);
wherein, the yellow phosphorus liquid is led into the reaction kettle 1 through the return pipe 10 to be recycled, thereby improving the utilization rate of resources.
D. Introducing the gas phase II into a condenser 3, and performing heat exchange action by the condenser 3 to obtain a methyl phosphorus dichloride liquid (wherein a small amount of raw material phosphorus trichloride and a byproduct dimethyl phosphorus chloride may be contained) and a gas phase III (mainly comprising raw material methyl chloride, and a small amount of raw material phosphorus trichloride, a byproduct dimethyl phosphorus chloride and a product methyl phosphorus dichloride may be contained); introducing the methyl phosphorus dichloride liquid into a product tank 18 through a discharge pipe 11, and storing for later use;
wherein the temperature of the cooling circulating liquid in the condenser 3 is-5-40 ℃.
E. Introducing the gas phase III into a second gas-liquid separator 4, and separating by the second gas-liquid separator 4 to obtain methyl phosphorus dichloride liquid (wherein the liquid may contain a small amount of raw material phosphorus trichloride and a byproduct dimethyl phosphorus chloride) and methyl chloride gas; introducing the methyl phosphorus dichloride liquid into a product tank 18 through a discharge pipe 11, and storing for later use;
wherein, the chloromethane gas is introduced into the chloromethane recovery tank 17 and then recovered and reused, thereby realizing the recovery and reuse of resources.
According to the limitation of the production working condition and environment, the liquid yellow phosphorus and the phosphorus trichloride can be mixed and then input by adopting a feeding pipe; or, after mixing the catalyst and the liquid yellow phosphorus, inputting the mixture by adopting a feeding pipe; or, after mixing the catalyst and the phosphorus trichloride, inputting the mixture by adopting a feeding pipe; or after mixing the liquid yellow phosphorus, the phosphorus trichloride and the catalyst, inputting the mixture by adopting a feeding pipe, and further flexibly arranging pipelines according to the production space.
The involved reaction formula is as follows:
the involved principles include:
the boiling point of the methyl chloride is-23.7 ℃, namely, when the temperature is-5 ℃, the methyl chloride still has positive pressure of about 100KPa and is still in a gas phase, and after the reaction temperature (250-350 ℃) exceeds the critical temperature of the methyl chloride by 143.8 ℃, the methyl chloride always exists in the gas phase in the preparation system, so the pressure in the reaction kettle 1 can reach 10Mpa (even higher);
the boiling point of the phosphorus trichloride is 76 ℃, the critical temperature of the phosphorus trichloride is 290 ℃, and the pressure is 9.3Mpa when the reaction temperature reaches 350 ℃; therefore, it exists in a gas phase in the first gas-liquid separator 2 and in a liquid phase in the subsequent condenser 3, the second gas-liquid separator 4;
the boiling point of the methyl phosphorus dichloride is 80-82 ℃, the methyl phosphorus dichloride exists in a gas phase in the first gas-liquid separator 2 and exists in a liquid phase in the subsequent condenser 3 and the second gas-liquid separator 4;
the melting point of yellow phosphorus is 44.1 deg.C, and therefore, it exists in the liquid phase in reaction tank 1.
Example 3
Based on example 1, this example provides a method for preparing methylphosphorus dichloride, comprising the following steps:
1. 1.28g of a catalyst (a mixture of copper oxide and cuprous oxide) is put into the reaction kettle 1, and the reaction kettle 1 is closed; then, replacing the preparation system with methyl chloride, and starting a stirrer 13 in the reaction kettle 1; 8.2368mol of yellow phosphorus is put into the reaction kettle 1 through a metering pump, and 1.9562mol of phosphorus trichloride is put into the reaction kettle 1 through the metering pump; adjusting the temperature in the reaction kettle 1 to 250 ℃, then introducing methyl chloride into the reaction kettle 1 until the pressure is 7MPa, and starting the reaction; the temperature of the preparation system is maintained at 250 ℃ and the pressure is maintained at 7MPa, the reaction is carried out for 3h, and the cumulative introduction amount of the chloromethane reaches 6.1776 mol.
2. Stopping introducing chloromethane, discharging by flash evaporation, and sequentially introducing a gas phase into a first gas-liquid separator 2, a first-stage condenser 3 (the temperature of cooling circulating liquid is 40 ℃), a second-stage condenser 3 (the temperature of cooling circulating liquid is 5 ℃), a third-stage condenser 3 (the temperature of cooling circulating liquid is-5 ℃) and a second gas-liquid separator 4; the liquid (yellow phosphorus) separated in the first gas-liquid separator 2 flows back to the reaction kettle 1, and the cooling liquid of the three condensers 3 is methyl phosphorus dichloride and flows to a product tank 18; the gas phase passing through the three condensers 3 is chloromethane which is recycled;
in addition, the mixture of the yellow phosphorus and the catalyst which is not flashed in the reaction kettle 1 can be reused.
3. 686.12g of methyl phosphorus dichloride is collected, and the content of the methyl phosphorus dichloride is 96.66 percent by gas phase detection after the product is derived; the conversion rate of yellow phosphorus is 47.5 percent, and the selectivity of methyl phosphorus dichloride is 96.67 percent.
The data calculations are illustrated below:
1) the content of the methyl phosphorus dichloride and the content of the phosphorus trichloride are obtained through a gas phase detection atlas;
2）
the yellow phosphorus conversion for this example was calculated as follows:
(6.1776: (95%/3: (2)/(8.2368): 100% =47.5% (wherein 95% is the conversion of the raw material chloromethane)
3）
The methyl phosphorus dichloride selectivity of this example was calculated as follows:
(686.12 × 96.66%/116.91)/(8.2368 × 47.5%/2 × 3) = 100% =96.67% (wherein 96.66% is the content of methyl phosphorus dichloride in the product, and 47.5% is the conversion of the raw material yellow phosphorus.)
Comparative example 1
Based on the preparation system in example 1, this comparative example is a preparation method of a conventional methylphosphorus dichloride, in which methylphosphorus dichloride is prepared using aluminum powder as a raw material:
1. replacing the reaction kettle with nitrogen, adding 160g of aluminum powder and 0.4g of iodine elementary substance into the reaction kettle, replacing the preparation system with chloromethane, and starting a stirrer in the reaction kettle; heating the reaction kettle to 100 ℃, and introducing methyl chloride into the reaction kettle to start reaction; controlling the reaction temperature to be 100-120 ℃, controlling the reaction pressure to be 2KPa at normal pressure, and reacting for 16-18 h; after completion of the reaction, the reaction mixture (aluminum sesquichloride) was stored in an air-free condition, and 612g in total was obtained.
2. Adding 4200g of phosphorus trichloride into a reaction kettle, replacing with nitrogen, starting a stirrer, adjusting the internal temperature of the reaction kettle to 25 ℃, starting to add aluminum sesqui-chloride into the reaction kettle under normal pressure, and maintaining the internal temperature of a reaction system at 30 ℃; the feeding time is 12h, and after the feeding is finished, the stirring reaction is continued for 1h at the temperature of 30 ℃; after the heat preservation reaction is finished, decompressing and steaming to remove phosphorus trichloride, and ending the distillation when the pressure is reduced to-0.09 MPa and the internal temperature is 70 ℃; 2905.2g of phosphorus trichloride was recovered to obtain 1872.69g of a complex.
3. 385g of sodium chloride is added into the obtained complex, and a stirrer and a heating device are started; distilling out the methyl phosphorus dichloride under normal pressure while dissociating, starting reduced pressure distillation after the internal temperature reaches 140 ℃, gradually increasing the negative pressure to-0.09 MPa, and ending the distillation when the internal temperature is increased to 145 ℃, wherein the total time is about 4 hours; 899.22g of methyl phosphorus dichloride is distilled out, and the content of the methyl phosphorus dichloride is 95.92 percent and the content of the phosphorus trichloride is 3.2 percent through gas phase detection after derivatization; the residual solid in the reaction kettle is waste residue of sodium tetrachloroaluminate as a main component.
Claims (7)
1. A preparation system for methyl phosphorus dichloride is characterized in that: the device comprises a reaction kettle (1) for material reaction, a first gas-liquid separator (2) for separating yellow phosphorus, a condenser (3) and a second gas-liquid separator (4) for separating methyl chloride, wherein the reaction kettle (1) is connected with a yellow phosphorus feeding pipe (5), a phosphorus trichloride feeding pipe (6), a methyl chloride feeding pipe (7) and a catalyst feeding pipe (8);
the reaction kettle (1) is connected with the first gas-liquid separator (2) through an external discharge pipe (9), a liquid phase outlet on the first gas-liquid separator (2) is connected with the reaction kettle (1) through a return pipe (10), and a yellow phosphorus recycling passage is formed among the external discharge pipe (9), the first gas-liquid separator (2) and the return pipe (10);
a gas phase outlet on the first gas-liquid separator (2) is connected with a condenser (3), and a liquid phase outlet on the condenser (3) is connected with a product tank (18) for collecting a methyl phosphorus dichloride product through a discharge pipe (11);
and a gas phase outlet on the condenser (3) is connected with the second gas-liquid separator (4), and a liquid phase outlet on the second gas-liquid separator (4) is connected with the product tank (18) through a discharge pipe (11).
2. A production system for methyldichlorophosphorus according to claim 1, characterized in that: and a gas phase outlet on the second gas-liquid separator (4) is connected with a chloromethane recovery tank (17) through a recovery pipe (16).
3. A production system for methyldichlorophosphorus according to claim 1, characterized in that: a pressure transmitter (12) is arranged on the reaction kettle (1), and a stirrer (13) is arranged in the reaction kettle (1).
4. A production system for methyldichlorophosphorus according to claim 1, characterized in that: the number of the condensers (3) is at least two, and the condensers (3) are arranged in series.
5. A production system for methyldichlorophosphorus according to claim 1, characterized in that: the return pipe (10) is provided with a U-shaped liquid seal pipe I (14).
6. A production system for methyldichlorophosphorus according to claim 1, characterized in that: and a U-shaped liquid seal pipe II (15) is arranged on the discharge pipe (11).
7. A production system for methyldichlorophosphorus according to claim 1, characterized in that: the preparation system is controlled by DCS.
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