Method for step-by-step purification of electronic-grade yellow phosphorus by microreactor-rectification-adsorption system

Abstract

The invention discloses a method for step-by-step purification of electronic-grade yellow phosphorus through a microreactor-rectification-adsorption system, and belongs to the technical field of phosphorus chemical industry. Industrial yellow phosphorus is used as a raw material, an enhanced oxidation reaction is performed through a micro-channel reactor, and a high-purity phosphorus chemical product is prepared by coupling continuous extraction, rectification purification and adsorption refining processes. According to the invention, the excellent mass and heat transfer performance of the microchannel reactor is utilized to realize accurate temperature control and safe operation of the oxidation reaction; and a multi-stage separation and purification unit is combined to form an efficient and integrated continuous production process. The process has the advantages of high reaction efficiency, low energy consumption, safe and controllable process, high impurity removal rate and the like, and can realize efficient and clean conversion of yellow phosphorus resources.

Description

Technical Field

[0001] The present invention belongs to the technical field of phosphorus chemical industry and relates to a production method for purifying electronic-grade yellow phosphorus. The method uses yellow phosphorus-high pure water as raw materials, hydrogen peroxide-oxidation enhancer (potassium dichromate) as oxidants, and performs enhanced oxidation reaction and halogenated hydrocarbon extraction in a microchannel reactor. Subsequently, the obtained product is subjected to water washing, rectification, and adsorption steps to remove impurities. The purification method of the present invention has low cost, safe operation, is conducive to industrialization, and has good economic benefits. Background Art

[0002] Yellow phosphorus is a basic chemical raw material, which is a white or light yellow semi-transparent solid. It is mainly used for the production of phosphoric acid, phosphates, red phosphorus, phosphorus trichloride, diphosphorus pentasulfide, etc., and is widely used in the chemical industry, national defense industry and other industries. According to the different impurity contents, yellow phosphorus is divided into industrial grade and high-purity grade. The purity of industrial yellow phosphorus is generally 99.8%. The most impurities in yellow phosphorus are arsenic and organic matter, followed by iron, nickel, copper, zinc, antimony, and the total content of other impurities is at the -9 order of magnitude. The too high impurity content affects its application in the semiconductor industry and the electronics industry. High-purity grade yellow phosphorus is mainly used for the production of high-purity phosphoric acid and other high-quality downstream products, and is widely used in the integrated circuit field. Especially in recent years, although China's chip industry has developed rapidly, high-end chips still highly rely on imports.

[0003] The main methods reported for yellow phosphorus purification in the existing processes are: (1) Chemical method, generally used for the refining and purification of low-arsenic yellow phosphorus, with high arsenic and antimony removal rates, but it is difficult to remove the impurity ions brought in by the reagents during the refining process. Among them, the most rapidly developed chemical refining method in China is the aqueous phase oxidation method; (2) Physical method, which separates based on the physical properties between phosphorus and arsenic, including zone melting method, distillation method, and adsorption method.

[0004] Patent CN 109607501 A discloses a purification process for yellow phosphorus, which uses yellow phosphorus as a raw material, then oxidizes it with hydrogen peroxide, removes arsenic with a composite material of iron and manganese oxides and mesoporous silica molecular sieve, then deeply oxidizes it with nickel sulfate, amphiphilic anionic polyacrylamide emulsifier, and nitric acid, and finally removes iron with nitrogen-rich lotus root-based carbon material.

[0005] Patent CN 112875661 A discloses a production method for removing impurities from yellow phosphorus and purifying it into electronic-grade yellow phosphorus. The method includes mixing and stirring industrial yellow phosphorus and polyphosphoric acid under oxygen isolation conditions, and settling and separating to obtain electronic-grade yellow phosphorus, where one or more of strong oxidants such as hydrogen peroxide, nitric acid, and sulfuric acid are added to the polyphosphoric acid.

[0006] The following main scientific problems exist in the traditional processes for purifying electronic-grade yellow phosphorus at home and abroad: (1) The mechanism of directional migration of arsenic elements is unclear, and the impurity removal efficiency is low. Arsenic and phosphorus will form As-P covalent bonds, resulting in only about 30% of arsenic impurities being removed by the traditional pickling method; (2) The mechanism of multi-metal synergistic pollution is complex. Metals form Fe-P intermetallic compounds during the gas-liquid-solid three-phase migration process, and the d-p orbital hybridization of transition metals and phosphorus seriously restricts their application in semiconductors; (3) The entrainment effect of organic solvents is prominent. Organic pollutants pyrolyze to produce phosphorus carbide in high-temperature processes, causing lattice defects.

[0007] To address the above scientific problems, the present invention uses microchannel process intensification oxidation, extraction technology, and rectification-adsorption deep impurity removal technology to remove main impurities such as arsenic, metals, and organic substances, meeting the purity requirements of electronic-grade phosphoric acid for chips. It has incomparable advantages over traditional batch production methods, providing an important way for the improvement of industrial continuous production, realizing the continuous, safe, efficient, and stable production of this product. In addition, the product purity and quality have also been significantly improved. Summary of the Invention

[0008] The purpose of the present invention is to solve the technical problems in the existing yellow phosphorus purification technology, such as high danger, large investment, high cost, and difficult operation, and to provide a method for gradually purifying electronic-grade yellow phosphorus using a microreactor-rectification-adsorption system.

[0009] A method for gradually purifying electronic-grade yellow phosphorus using a microreactor-rectification-adsorption system is carried out according to the following steps:

[0010] (1) At room temperature, industrial yellow phosphorus containing various impurities such as arsenic, metal compounds, and organic substances is melted and mixed with high-purity water in a certain proportion, and continuously stirred to form material A. Hydrogen peroxide and potassium dichromate as an oxidation enhancer are mixed in a certain proportion and continuously stirred and mixed evenly to form material B. The two materials are respectively fed into the microreactor through metering pumps for mixing and reaction. The mixing temperature is controlled by an external heat exchanger, and the heat transfer medium is thermal oil;

[0011] (2) The reaction product and the extractant are fully mixed in a microchannel mixer. The mixed product flows out from the reactor outlet. Then, the organic phase in the product collection area is separated and washed with water to obtain refined yellow phosphorus, which then enters the rectification column;

[0012] (3) After purging the rectification column with nitrogen, add yellow phosphorus that has been intensively oxidized with hydrogen peroxide and purified by extraction into the rectification column. After heating, pump the bottom material of the column to the falling film evaporator through a circulating pump, and conduct the top condenser water circulation and bottom heating. After the temperature stabilizes, start refluxing. The gaseous yellow phosphorus drawn out comes into full contact with the adsorbent in the adsorption column, and impurities are further removed. After condensation, it enters the product collector, which is the required product. Through content analysis, the removal rate of arsenic impurities in industrial yellow phosphorus impurities reaches 99.9952%, the removal rate of metal impurities is 99.11%, the removal rate of organic impurities is 99.9995%, the yield of yellow phosphorus is 76.03%, and the purity of yellow phosphorus is 99.9999913% (i.e., 7N grade).

[0013] Among them, in step (1), the temperature of the microchannel reactor is 45°C to 65°C, preferably 55°C; the concentration of hydrogen peroxide is 22% to 28%, preferably 26%; the mass ratio of hydrogen peroxide to yellow phosphorus is (2 - 5):1, preferably 4:1; among them, potassium dichromate is in a volume ratio of 1500:1 to yellow phosphorus, and high-purity water and yellow phosphorus are heated to 45°C and fully mixed according to a liquid-solid ratio of 1:5.

[0014] Among them, in step (2), the extraction agents involved include halogenated hydrocarbons (chloroform, carbon tetrachloride, chloroethane, chlorobenzene, etc.), alcohols (isoamyl alcohol, sec-octanol, isobutanol, etc.), esters (ethyl acetate, amyl acetate, butyl acetate, etc.), etc.

[0015] Among them, in step (2), the reaction product and the extraction agent are mixed in a microchannel at a volume ratio of 1:3, and the statically separated material is used to separate the organic solvent from yellow phosphorus. The separated yellow phosphorus is washed 3 times with water and once with alkali.

[0016] Among them, in step (3), the number of trays in the rectification column is 50 to 90, preferably 90; the number of feed trays is 20 to 35, preferably 34; the reflux ratio is (10 - 6):1, preferably 8:1; the specific surface area of the activated carbon is 800 m 2 / g to 1200 m 2 / g, preferably 1000 m 2 / g; among them, the vacuum degree is 11 kPa.

[0017] All the above purification processes are carried out in a multi-stage series microreactor, rectification column, and adsorption column. The reaction system includes different functional areas such as a feed zone, preheating zone, reaction zone, extraction zone, water washing zone, rectification zone, adsorption zone, and discharge zone. Among them, the preheating zone, reaction zone, and extraction zone are all arranged by arranging n series-connected microchannel reactor modules, and the module arrangement method is in series.

[0018] The microreactor channel structure adopted by the microchannel reactor module includes a chain type, an enhanced mixed type circular cake type rectangular flat pipe structure, and a heart shape structure.

[0019] The present invention has the following main features compared with the prior art:

[0020] 1. Aiming at the problems of easy decomposition of hydrogen peroxide at high temperature, fast oxidation heat release, high explosion risk, etc., the present invention adopts a hydrogen peroxide enhanced oxidation method - chloroform extraction microchannel reaction process. The reaction time is short, shortened from several hours in the traditional method to several minutes, significantly improving the purification efficiency.

[0021] 2. Aiming at the difficulty that it is difficult for hydrogen peroxide to remove metal and organic impurities in industrial-grade yellow phosphorus to meet the requirements of electronic-grade yellow phosphorus, the rectification - adsorption method is used to further remove impurities from the oxidized and refined yellow phosphorus. The operation is simple, the cost is low, and the safety is high. While greatly improving the purity of yellow phosphorus, it effectively solves the safety hazards such as spontaneous combustion and explosion in traditional yellow phosphorus production, and is applicable to large-scale industrial production.

[0022] 3. The present invention adopts microchannel reactors with different structures, which can enhance the mass transfer and heat transfer performance, keep the reaction temperature constant, and improve the safety of the reaction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the process flow chart of purifying yellow phosphorus according to the present invention;

[0024] Figure 2 is the chain structure adopted in the process of the present invention;

[0025] Figure 3 is the enhanced hybrid circular cake - type rectangular flat pipe structure adopted in the process of the present invention;

[0026] Figure 4 is the heart - shaped structure adopted in the process of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention will be described in detail below with reference to the embodiments. However, the following embodiments are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

[0028] Example 1

[0029] A method for gradually purifying electronic - grade yellow phosphorus by a micro - reactor - rectification - adsorption system, comprising the following steps:

[0030] (1) Device: Refer to Figure 1 Determine a connection mode of a micro - reactor - rectification - adsorption system. The pipeline type is chain pipeline + heart - shaped pipeline. The inner diameter of the pipeline and the holdup are determined according to the flow rate and the reaction residence time, and the heat - transfer medium is heat - conducting oil.

[0031] (2) At 45 °C, hydrogen peroxide with a mass concentration of 26% is fully mixed with an oxidation enhancer (potassium dichromate), denoted as material A, where the amount of potassium dichromate is added according to a volume ratio of 1500:1 to yellow phosphorus. At the same time, industrial-grade yellow phosphorus with a purity of over 99.5% and high-purity water are fully mixed at a ratio of 1:5 at 45 °C, denoted as material B. The flow pumps of materials A and B are adjusted according to the mass ratio of hydrogen peroxide to yellow phosphorus of 4:1 and fed into a microchannel reactor, and fully reacted at 45 °C. Then it is fed into a microchannel mixer and fully mixed with an extractant (chloroform) at a volume ratio of 1:3 to extract organic impurities, and the organic solvent and water are separated by 3 times of water washing and 1 time of alkali washing. First, nitrogen is used to purge the distillation column to create an inert environment, and then a vacuum pump is used to evacuate the distillation system to a vacuum, with a vacuum degree of 11 kPa. Refined yellow phosphorus is added to the distillation column. The total number of trays in the distillation column is 90, and the feeding position is at the 34th tray. The yellow phosphorus vapor is condensed by the top condenser of the column and refluxed into the column at a reflux ratio of 8:1. The yellow phosphorus liquid refluxed from the top of the column and the yellow phosphorus vapor rising from the bottom of the column are in full contact in the column for vapor-liquid exchange. The gas phase passes through an adsorption column with activated carbon having a specific surface area of 1200 m 2 / g to obtain high-purity yellow phosphorus. Through content analysis, the purity of yellow phosphorus is 99.999842% and the yield is 90.58%.

[0032] Example 2

[0033] A method for gradually purifying electronic-grade yellow phosphorus by a microreactor-distillation-adsorption system, comprising the following steps:

[0034] (1) Equipment: Refer to Figure 1 Determine a connection mode of a microreactor-distillation-adsorption system. The pipeline type is a chain pipeline + a circular cake-shaped rectangular flat pipeline. The inner diameter of the pipeline and the holdup are determined according to the flow rate and the reaction residence time, and the heat transfer medium is heat-conducting oil.

[0035] (2) At 45 °C, hydrogen peroxide with a mass concentration of 28% is fully mixed with an oxidation enhancer (potassium dichromate), denoted as material A, where the amount of potassium dichromate is added according to a volume ratio of 1:1500 to white phosphorus. At the same time, industrial-grade white phosphorus with a purity of over 99.5% and high-purity water are fully mixed at a ratio of 1:5 at 45 °C, denoted as material B. The flow pumps of materials A and B are adjusted according to the mass ratio of hydrogen peroxide to white phosphorus of 4:1 and fed into a microchannel reactor, and fully reacted at 55 °C. Then it is fed into a microchannel mixer and fully mixed with an extractant (chloroform) at a volume ratio of 1:3 to extract organic impurities, and the organic solvent and water are separated by 3 times of water washing and 1 time of alkali washing. First, nitrogen is used to purge the distillation column to create an inert environment, and then a vacuum pump is used to pump the distillation system to a vacuum with a vacuum degree of 11 kPa. Refined white phosphorus is added to the distillation column. The total number of trays in the distillation column is 90, and the feed position is at the 34th tray. The white phosphorus vapor is condensed by the top condenser of the column and refluxed into the column at a reflux ratio of 8:1. The white phosphorus liquid refluxed from the top of the column and the white phosphorus vapor rising from the bottom of the column are in full contact in the column for vapor-liquid exchange. The gas phase passes through an adsorption column with activated carbon having a specific surface area of 1000 m 2 / g to obtain high-purity white phosphorus. Through content analysis, the purity of white phosphorus is 99.999989% and the yield is 91.23%.

[0036] Example 3

[0037] A method for gradually purifying electronic-grade white phosphorus by a microreactor-distillation-adsorption system, comprising the following steps:

[0038] (1) Device: Refer to Figure 1 to determine a connection mode of a microreactor-distillation-adsorption system. The pipeline type is a round cake-shaped rectangular flat pipeline + heart-shaped pipeline. The inner diameter of the pipeline and the holdup are determined according to the flow rate and the reaction residence time, and the heat transfer medium is heat-conducting oil.

[0039] (2) At 45 °C, hydrogen peroxide with a mass concentration of 26% is fully mixed with an oxidation enhancer (potassium dichromate), denoted as material A, where the amount of potassium dichromate is added according to a volume ratio of 1:1500 to yellow phosphorus. At the same time, industrial-grade yellow phosphorus with a purity of over 99.5% and high-purity water are fully mixed at a ratio of 1:5 at 45 °C, denoted as material B. The flow pumps of materials A and B are adjusted according to the mass ratio of hydrogen peroxide to yellow phosphorus of 5:1 and introduced into a microchannel reactor, and fully reacted at 55 °C. Then it is introduced into a microchannel mixer and fully mixed with an extractant (chloroform) at a volume ratio of 1:3 to extract organic impurities, and the organic solvent and water are separated by 3 times of water washing and 1 time of alkali washing. First, nitrogen is used to purge the distillation column to create an inert environment, and then the distillation system is evacuated to a vacuum with a vacuum degree of 11 kPa using a vacuum pump. Refined yellow phosphorus is added to the distillation column. The total number of trays in the distillation column is 90, and the feeding position is at the 34th tray. The yellow phosphorus vapor is condensed by the top condenser of the column and refluxed into the column at a reflux ratio of 8:1. The yellow phosphorus liquid refluxed from the top of the column and the yellow phosphorus vapor rising from the bottom of the column are in full contact in the column for vapor-liquid exchange. The gas phase passes through an adsorption column with activated carbon having a specific surface area of 800 m 2 / g to obtain high-purity yellow phosphorus. After content analysis, the purity of yellow phosphorus is 99.99997% and the yield is 89.95%.

[0040] Example 4

[0041] A method for gradually purifying electronic-grade yellow phosphorus by a microreactor-distillation-adsorption system, comprising the following steps:

[0042] (1) Device: Refer to Figure 1 to determine a connection mode of a microreactor-distillation-adsorption system. The pipeline type is heart-shaped pipeline + heart-shaped pipeline. The inner diameter of the pipeline and the holdup are determined according to the flow rate and the reaction residence time, and the heat transfer medium is heat-conducting oil.

[0043] (2) At 45 °C, hydrogen peroxide with a mass concentration of 26% is fully mixed with an oxidation enhancer (potassium dichromate), denoted as material A, where the amount of potassium dichromate is added according to a volume ratio of 1:1500 to yellow phosphorus. Meanwhile, at 45 °C, industrial-grade yellow phosphorus with a purity of over 99.5% and high-purity water are fully mixed at a ratio of 1:5, denoted as material B. The flow pumps of materials A and B are adjusted according to the mass ratio of hydrogen peroxide to yellow phosphorus of 3:1 and introduced into a microchannel reactor, and fully reacted at 55 °C. Then it is introduced into a microchannel mixer and fully mixed with an extractant (chloroform) at a volume ratio of 1:3 to extract organic impurities, and the organic solvent and water are separated by 3 times of water washing and 1 time of alkali washing. First, nitrogen is used to purge the distillation column to create an inert environment, and then a vacuum pump is used to pump the distillation system to a vacuum, with a vacuum degree of 11 kPa. Refined yellow phosphorus is added to the distillation column. The total number of trays in the distillation column is 90, and the feeding position is at the 34th tray. The yellow phosphorus vapor is condensed by the top condenser of the column and refluxed into the column according to a reflux ratio of 8:1. The yellow phosphorus liquid refluxed from the top of the column and the yellow phosphorus vapor rising from the bottom of the column are in full contact in the column for vapor-liquid exchange. The gas phase passes through an adsorption column with activated carbon having a specific surface area of 1000 m 2 / g to obtain high-purity yellow phosphorus. Through content analysis, the purity of yellow phosphorus is 99.999576% and the yield is 90.04%.

[0044] Example 5

[0045] A method for gradually purifying electronic-grade yellow phosphorus by a microreactor-distillation-adsorption system, comprising the following steps:

[0046] (1) Equipment: Refer to Figure 1 Determine a connection mode of a microreactor-distillation-adsorption system. The pipe type is round cake-shaped rectangular flat pipe + round cake-shaped rectangular flat pipe. The inner diameter of the pipe and the holdup are determined according to the flow rate and the reaction residence time, and the heat exchange medium is heat-conducting oil.

[0047] (2) At 45 °C, hydrogen peroxide with a mass concentration of 22% is fully mixed with an oxidation enhancer (potassium dichromate), denoted as material A, where the amount of potassium dichromate is added according to a volume ratio of 1:1500 to yellow phosphorus. At the same time, industrial-grade yellow phosphorus with a purity of over 99.5% and high-purity water are fully mixed at a ratio of 1:5 at 45 °C, denoted as material B. The flow pumps of materials A and B are adjusted according to the mass ratio of hydrogen peroxide to yellow phosphorus of 4:1 and fed into a microchannel reactor, and fully reacted at 55 °C. Then it is fed into a microchannel mixer and fully mixed with an extractant (chloroform) at a volume ratio of 1:3 to extract organic impurities, and the organic solvent and water are separated by 3 times of water washing and 1 time of alkali washing. First, nitrogen is used to purge the distillation column to create an inert environment, and then a vacuum pump is used to evacuate the distillation system to a vacuum, with a vacuum degree of 11 kPa. Refined yellow phosphorus is added to the distillation column. The total number of trays in the distillation column is 90, and the feeding position is at the 34th tray. The yellow phosphorus vapor is condensed by the top condenser of the column and refluxed into the column at a reflux ratio of 10:1. The yellow phosphorus liquid refluxed from the top of the column and the yellow phosphorus vapor rising from the bottom of the column are in full contact in the column for vapor-liquid exchange. The gas phase passes through an adsorption column with an activated carbon specific surface area of 1000 m 2 / g to obtain high-purity yellow phosphorus. Through content analysis, the purity of yellow phosphorus is 99.9999902%, and the yield is 90.56%.

[0048] Example 6

[0049] A method for gradually purifying electronic-grade yellow phosphorus by a microreactor-distillation-adsorption system, comprising the following steps:

[0050] (1) Equipment: Refer to Figure 1 Determine a connection method for a microreactor-distillation-adsorption system. The pipeline type is chain pipeline + chain pipeline. The inner diameter of the pipeline and the holdup are determined according to the flow rate and the reaction residence time, and the heat exchange medium is heat-conducting oil.

[0051] (2) At 45 °C, hydrogen peroxide with a mass concentration of 26% is fully mixed with an oxidation enhancer (potassium dichromate), denoted as material A, where the amount of potassium dichromate is added according to a volume ratio of 1:1500 to yellow phosphorus. At the same time, industrial-grade yellow phosphorus with a purity of over 99.5% and high-purity water are fully mixed at a ratio of 1:5 at 45 °C, denoted as material B. The flow pumps of materials A and B are adjusted according to the mass ratio of hydrogen peroxide to yellow phosphorus of 4:1 and introduced into a microchannel reactor, and fully reacted at 55 °C. Then it is introduced into a microchannel mixer and fully mixed with an extractant (chlorobenzene) at a volume ratio of 1:3 to extract organic impurities, and the organic solvent and water are separated by 3 times of water washing and 1 time of alkali washing. First, nitrogen is used to purge the distillation column to create an inert environment, and then the distillation system is evacuated to a vacuum with a vacuum degree of 11 kPa using a vacuum pump. Refined yellow phosphorus is added to the distillation column. The total number of trays in the distillation column is 90, and the feed position is at the 34th tray. The yellow phosphorus vapor is condensed by the top condenser of the column and refluxed into the column at a reflux ratio of 6:1. The yellow phosphorus liquid refluxed from the top of the column and the yellow phosphorus vapor rising from the bottom of the column are in full contact in the column for vapor-liquid exchange. The gas phase passes through an adsorption column with an activated carbon specific surface area of 1200 m 2 / g to obtain high-purity yellow phosphorus. After content analysis, the purity of yellow phosphorus is 99.999988% and the yield is 91.10%.

[0052] Example 7

[0053] A method for gradually purifying electronic-grade yellow phosphorus by a microreactor-distillation-adsorption system, comprising the following steps:

[0054] (1) Device: Refer to Figure 1 Determine a connection mode of a microreactor-distillation-adsorption system. The pipeline type is a round cake-shaped rectangular flat pipeline + heart-shaped pipeline. The inner diameter of the pipeline and the holdup are determined according to the flow rate and the reaction residence time, and the heat transfer medium is heat-conducting oil.

[0055] (2) At 45 °C, hydrogen peroxide with a mass concentration of 26% is fully mixed with an oxidation enhancer (potassium dichromate), denoted as material A, where the amount of potassium dichromate is added according to a volume ratio of 1:1500 to yellow phosphorus. At the same time, industrial-grade yellow phosphorus with a purity of over 99.5% and high-purity water are fully mixed at a ratio of 1:5 at 45 °C, denoted as material B. The flow pumps of materials A and B are adjusted according to the mass ratio of hydrogen peroxide to yellow phosphorus of 4:1 and introduced into a microchannel reactor, and fully reacted at 60 °C. Then it is introduced into a microchannel mixer and fully mixed with an extractant (butyl acetate) at a volume ratio of 1:3 to extract organic impurities, and the organic solvent and water are separated by 3 times of water washing and 1 time of alkali washing. First, nitrogen is used to purge the distillation column to create an inert environment, and then a vacuum pump is used to pump the distillation system to a vacuum with a vacuum degree of 11 kPa. Refined yellow phosphorus is added to the distillation column. The total number of trays in the distillation column is 90, and the feeding position is at the 34th tray. The yellow phosphorus vapor is condensed by the top condenser of the distillation column and refluxed into the column according to a reflux ratio of 6:1. The yellow phosphorus liquid refluxed from the top of the column and the yellow phosphorus vapor rising from the bottom of the column are in full contact in the column for vapor-liquid exchange. The gas phase passes through an adsorption column with activated carbon specific surface area of 1000 m 2 / g to obtain high-purity yellow phosphorus. Through content analysis, the purity of yellow phosphorus is 99.999979% and the yield is 89.82%.

[0056] Example 8

[0057] A method for gradually purifying electronic-grade yellow phosphorus by a microreactor-distillation-adsorption system, comprising the following steps:

[0058] (1) Device: Refer to Figure 1 Determine a connection mode of a microreactor-distillation-adsorption system. The pipeline type is round cake-shaped rectangular flat pipeline + chain pipeline. The inner diameter of the pipeline and the holdup are determined according to the flow rate and reaction residence time, and the heat transfer medium is heat-conducting oil.

[0059] (2) At 45 °C, hydrogen peroxide with a mass concentration of 28% is fully mixed with an oxidation enhancer (potassium dichromate), denoted as material A, where the amount of potassium dichromate is added according to a volume ratio of 1:1500 to yellow phosphorus. At the same time, industrial-grade yellow phosphorus with a purity of over 99.5% and high-purity water are fully mixed at a ratio of 1:5 at 45 °C, denoted as material B. Adjust the flow pumps of material A and material B according to the mass ratio of hydrogen peroxide to yellow phosphorus of 4:1, and introduce them into a microchannel reactor, where they react fully at 45 °C. Then, it is introduced into a microchannel mixer and fully mixed with an extractant (n-butanol) at a volume ratio of 1:3 to extract organic impurities. The organic solvent and water are separated through 3 times of water washing and 1 time of alkali washing. First, nitrogen is used to purge the distillation column to create an inert environment, and then a vacuum pump is used to evacuate the distillation system to a vacuum with a vacuum degree of 11 kPa. The refined yellow phosphorus is added to the distillation column. The total number of trays in the distillation column is 90, and the feed position is at the 34th tray. The yellow phosphorus vapor is condensed by the condenser at the top of the column and refluxed into the column at a reflux ratio of 8:1. The yellow phosphorus liquid refluxed from the top of the column and the yellow phosphorus vapor rising from the bottom of the column come into full contact in the column for vapor-liquid exchange. The gas phase passes through an adsorption column with activated carbon having a specific surface area of 1000 m 2 / g to obtain high-purity yellow phosphorus. Through content analysis, the purity of yellow phosphorus is 99.999875% and the yield is 90.58%.

[0060] Example 9

[0061] A method for gradually purifying electronic-grade yellow phosphorus by a microreactor-distillation-adsorption system, comprising the following steps:

[0062] (1) Equipment: Refer to Figure 1 Determine a connection mode of a microreactor-distillation-adsorption system. The pipeline type is a chain pipeline + a heart-shaped pipeline. The inner diameter of the pipeline and the holdup are determined according to the flow rate and the reaction residence time. The heat exchange medium is thermal oil.

[0063] (2) At 45 °C, hydrogen peroxide with a mass concentration of 26% is fully mixed with an oxidation enhancer (potassium dichromate), denoted as material A, where the amount of potassium dichromate is added according to a volume ratio of 1:1500 to yellow phosphorus. At the same time, industrial-grade yellow phosphorus with a purity of over 99.5% and high-purity water are fully mixed at a ratio of 1:5 at 45 °C, denoted as material B. The flow pumps of materials A and B are adjusted according to a mass ratio of hydrogen peroxide to yellow phosphorus of 4:1 and introduced into a microchannel reactor, and the reaction is carried out fully at 55 °C. Then it is introduced into a microchannel mixer and fully mixed with an extractant (chloroform) at a volume ratio of 1:3 to extract organic impurities, and the organic solvent and water are separated by 3 times of water washing and 1 time of alkali washing. First, nitrogen is used to purge the distillation column to create an inert environment, and then the distillation system is evacuated to a vacuum with a vacuum pump, and the vacuum degree is 11 kPa. Refined yellow phosphorus is added to the distillation column. The total number of trays in the distillation column is 90, and the feed position is at the 34th tray. The yellow phosphorus vapor is condensed by the top condenser of the tower and refluxed into the tower at a reflux ratio of 8:1. The yellow phosphorus liquid refluxed at the top of the tower and the yellow phosphorus vapor rising from the bottom of the tower are in full contact in the tower for vapor-liquid exchange. The gas phase passes through an adsorption tower with activated carbon specific surface area of 1000 m 2 / g to obtain high-purity yellow phosphorus. Through content analysis, the purity of yellow phosphorus is 99.9999913% and the yield is 91.41%.

Claims

1. A method for gradually purifying electronic-grade yellow phosphorus by a microreactor - rectification - adsorption system, characterized in that Proceed as follows: (1) At room temperature, melt industrial yellow phosphorus containing various impurities such as arsenic, metal compounds, and organic substances, mix it with high-purity water in a certain proportion, and continuously stir to make material A. Mix hydrogen peroxide and potassium dichromate as an oxidation enhancer in a certain proportion and continuously stir to mix evenly to make material B. Feed the two materials into a microreactor through metering pumps respectively for mixing and reaction. The mixing temperature is controlled by an external heat exchanger, and the heat exchange medium is heat-conducting oil; (2) The reaction product and the extractant are fully mixed in a microchannel mixer. The mixed product flows out from the reactor outlet. Then, the organic phase in the product collection area is separated and washed with water to obtain refined yellow phosphorus, and then it enters the distillation column; (3) After purging the distillation column with nitrogen, add yellow phosphorus that has been strengthened and oxidized with hydrogen peroxide and purified by extraction into the distillation column. After heating, pump the bottom material of the column to a falling film evaporator through a circulating pump, and carry out top condenser water circulation and bottom heating. After the temperature stabilizes, start refluxing. The gaseous yellow phosphorus drawn out is in full contact with the adsorbent in the adsorption column, and impurities are further removed. After condensation, it enters the product collector, which is the required product.

2. The method for stepwise purification of electronic-grade yellow phosphorus by a microreactor-rectification-adsorption system according to the claim, characterized in that Among them, in step (1), the temperature of the microchannel reactor is 45°C to 65°C, preferably 55°C; the concentration of hydrogen peroxide is 22% to 28%, preferably 26%; the mass ratio of hydrogen peroxide to yellow phosphorus is (2 to 5):1, preferably 4:1; among them, potassium dichromate is in a volume ratio of 1500:1 to yellow phosphorus, and high-purity water and yellow phosphorus are heated to 45°C and fully mixed according to a liquid-solid ratio of 1:

5.

3. The method for stepwise purification of electronic-grade yellow phosphorus by a microreactor-rectification-adsorption system according to the claim is characterized in that Among them, the extractants involved in step (2) include halogenated hydrocarbons (chloroform, carbon tetrachloride, chloroethane, chlorobenzene, etc.), alcohols (isoamyl alcohol, sec-octanol, isobutanol, etc.), esters (ethyl acetate, amyl acetate, butyl acetate, etc.), etc.

4. The method for gradually purifying electronic-grade yellow phosphorus by a microreactor-rectification-adsorption system according to the claim is characterized in that Among them, in step (2), the reaction product and the extractant are mixed in a microchannel according to a volume ratio of 1:3, and the statically flowing material separates the organic solvent from the yellow phosphorus. The separated yellow phosphorus is washed 3 times with water and 1 time with alkali.

5. The method for stepwise purification of electronic-grade yellow phosphorus by a microreactor - rectification - adsorption system according to the claim is characterized in that Among them, in step (3), the number of distillation column trays is 50 to 90, preferably 90; the number of feed trays is 20 to 35, preferably 34; the reflux ratio is (10 to 6):1, preferably 8:1; the specific surface area of the activated carbon is 800 m 2 / g to 1200 m 2 / g, preferably 1000 m 2 / g; the vacuum degree is 11 kPa.

6. The method for gradually purifying electronic-grade yellow phosphorus by a microreactor - rectification - adsorption system according to the claim is characterized in that All the above purification processes are carried out in a multi-stage series microreactor, distillation column, and adsorption column. The reaction system includes different functional areas such as a feed area, a preheating area, a reaction area, an extraction area, a water washing area, a distillation area, an adsorption area, and a discharge area. Among them, the preheating area, the reaction area, and the extraction area are all arranged by n series-connected microchannel reactor modules, and the module arrangement method is in series.

7. A method for stepwise purification of electronic-grade yellow phosphorus by a microreactor - rectification - adsorption system according to the claim, characterized in that The microreactor channel structure adopted by the microchannel reactor module includes a chain type, an enhanced mixed type circular cake type rectangular flat pipe structure, and a heart-shaped structure.

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