CN113444121B - Method for removing ethyl dichlorosilane impurities in dimethyl dichlorosilane - Google Patents
Method for removing ethyl dichlorosilane impurities in dimethyl dichlorosilane Download PDFInfo
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Abstract
The invention relates to a method for removing ethyl dichlorosilane impurities in dimethyl dichlorosilane; comprises a reactor and a separation system; adding dimethyl dichlorosilane feed containing ethyl dichlorosilane and a hydrosilylation reaction product into a reactor for reaction, adopting an isopropanol solution of chloroplatinic acid hydrate or a Karstedt catalyst, enabling a product after the reaction to enter a separation system, and separating the surplus reaction product, the dimethyl dichlorosilane and the hydrosilylation reaction product by light-weight removal and heavy-weight removal operation in a rectification mode. And the reacted mixture enters a separation system for separation to obtain a dimethyldichlorosilane product. The method converts the ethyldichlorosilane through reaction, and effectively reduces the difficulty of system separation, the number of theoretical plates for subsequent rectification separation operation and the requirement of reflux ratio by utilizing the characteristic that the boiling point difference between reactants and reaction products and the dimethyldichlorosilane is larger, reduces equipment investment, greatly reduces energy consumption and has higher industrial application value.
Description
Technical Field
The invention belongs to the field of separation and purification in the organic silicon industry, and particularly relates to a refining technology of dimethyldichlorosilane containing ethyldichlorosilane impurities.
Background
Dimethyl dichlorosilane is an important organic silicon monomer, is a main raw material for producing high-performance organic silicon compounds, has high requirement on purity, and must strictly control the content of impurities. At present, the separation and purification of the dimethyl dichlorosilane in the industry mostly adopts a rectification technology, and generally adopts a mode of multiple tower plates and a large reflux ratio. Through analysis, the key impurity influencing the purity of the dimethyldichlorosilane is ethyldichlorosilane, and although the content of the ethyldichlorosilane in a synthesized monomer is less than 0.5%, the influence on the quality of downstream products is very large and must be strictly controlled. The normal pressure boiling point is 74.0 ℃, the dimethyl dichlorosilane is 70.2 ℃, the boiling point difference between the two is 3.8 ℃, when the boiling point difference between the components is small, the relative volatility is close to 1, the separation difficulty is very high, the number of theoretical plates and the reflux ratio required by the rectification process are increased sharply, so the equipment investment and the energy consumption are very high, and the economic is unreasonable.
Chinese patent CN93114384.5 provides a method for removing hydrosilane from methylchlorosilane. In this process, the product mixture obtained in the synthesis of methylchlorosilanes, which contains a fraction of silanes having hydrogen atoms bonded directly to silicon, is reacted with a chlorocarbon in the presence of palladium or platinum as catalyst to convert it into the corresponding chlorosilane, the impurities being removed by chemical reaction.
The method for removing the ethyldichlorosilane in the dimethyldichlorosilane by a chemical method is a feasible method. One important property of the chlorosilane containing Si-H bonds is hydrosilylation reaction, namely the addition reaction of the chlorosilane containing Si-H bonds and compounds with terminal unsaturated bonds, and the catalyst for the reaction can adopt isopropanol solution of chloroplatinic acid hydrate (Speier catalyst) or Karstedt catalyst. For example, the reaction of trichlorosilane with acetylene to synthesize valuable vinyltrichlorosilane is:
C 2 H 2 +HSiCl 3 ——→CH 2 CHSiCl 3
the generated vinyl trichlorosilane can further react with trichlorosilane in an addition reaction formula:
CH 2 CHSiCl 3 +HSiCl 3 ——→Cl 3 SiCH 2 CH 2 CHSiCl 3
at present, the separation and purification of the dimethyldichlorosilane in industrial production are widely performed by still adopting a common rectification technology, and because the boiling point difference of impurities is close, the number of rectification tower plates is high, the reflux ratio is large, and the energy consumption is large. The hydrosilylation reaction process is simple and easy to control, the conditions are mild, the boiling point difference between an impurity reaction product and a target component can be increased by selecting the type of the added reaction medium, the difficulty of subsequent separation and purification is reduced, the method has application value in the reaction separation and purification processes, and is particularly suitable for removing an ethyl dichlorosilane impurity system in dimethyl dichlorosilane.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a method for removing ethyldichlorosilane impurities in dimethyldichlorosilane. By utilizing the principle of hydrosilylation, the ethyl dichlorosilane impurity is converted into an addition product with a larger boiling point difference with dimethyl dichlorosilane, and the subsequent separation difficulty is reduced, so that the efficient separation of the dimethyl dichlorosilane and the ethyl dichlorosilane is realized. The defects of high energy consumption, over-high tower plate number, high reflux ratio, high equipment investment and the like caused by the fact that the traditional separation method only depends on rectification operation are avoided.
The technical scheme of the invention is as follows:
a method for removing ethyldichlorosilane impurities in dimethyldichlorosilane comprises a reactor and a separation system; adding dimethyl dichlorosilane feed containing ethyl dichlorosilane and a hydrosilylation reaction product into a reactor for reaction, adopting an isopropanol solution of chloroplatinic acid hydrate or a Karstedt catalyst, enabling a product after the reaction to enter a separation system, and separating the surplus reaction product, the dimethyl dichlorosilane and the hydrosilylation reaction product by light-weight removal and heavy-weight removal operation in a rectification mode.
The molar ratio of the recycled reactant to the dimethyldichlorosilane is preferably in the range of 3.
The reaction pressure is preferably 0 to 1.0MPaG.
The reaction temperature is preferably 50 to 200 ℃.
The reaction residence time is preferably from 0.1 to 1 hour.
An isopropanol solution of chloroplatinic acid hydrate was the Speier catalyst.
The concentration of the catalyst in the raw materials, namely the content of the catalytic active center Pt accounts for the total amount of the reaction raw materials, and is preferably 10-150ppm.
The reactor is in the form of a stirred tank, an external circulation reactor, a bubble column or a reaction rectifying tower.
The separation system comprises light component removal and heavy component removal operations, cuts fractions according to the boiling points of all components and performs matching combination to respectively obtain dimethyldichlorosilane, an addition reactant and fractions of the addition reaction product; the surplus reactant obtained by separation returns to the reactor, and the dimethyldichlorosilane after the ethyldichlorosilane is removed is taken as a product, and simultaneously, a corresponding addition product is also obtained as a byproduct.
The hydrosilylation reaction according to the present invention is preferably any of:
(1) Reaction with alpha olefins, including C2-C20 terminal olefins, diolefins, exemplified by the reaction of ethylene, hydrosilylation to produce diethyldichlorosilane:
EtHSiCl 2 +C 2 H 4 ——→(C 2 H 5 ) 2 SiCl 2
(2) Terminal olefins having a benzene ring, such as styrene, methylstyrene, etc., in the case of styrene, hydrosilylation produces ethylethylethylethylethylethylethylphenyldichlorosilane:
EtHSiCl 2 +PhCH＝CH 2 ——→Et(PhCH 2 CH 2 )SiCl 2
(3) C4-C20 cyclic olefins such as cyclopentene, cyclohexene, cycloheptene, and the like; in the case of cyclohexene, the hydrosilylation reaction produces ethylcyclohexyldichlorosilane:
EtHSiCl 2 +C 6 H 10 ——→EtC 6 H 11 SiCl 2
(4) Compounds having terminal unsaturated bonds containing oxygen and nitrogen groups, such as allylamine, vinylfuran, vinylpyridine, acetone, methyl ethyl ketone, allyl glycidyl ether, and the like, in the case of allylamine, the reaction formula is:
EtHSiCl 2 +CH 2 ＝CHCH 2 NH2——→Et(CH 2 CH 2 CH 2 NH 2 )SiCl 2
(5) A terminal olefin, such as acrylonitrile, substituted with a CN group having the formula:
EtHSiCl 2 +CH 2 ＝CHCN——→Et(CH 2 CH 2 CN)SiCl 2
(6) Alkyne, C 2 -C 10 Terminal alkynes, exemplified by acetylene, hydrosilylation to form ethylvinyldichlorosilane:
EtHSiCl 2 +C 2 H 2 ——→Et(CH 2 CH)SiCl 2
(7) Halogen or chlorosilane groups, oxychlorosilyl group-substituted terminal olefins, such as 3-chloropropene, 4-chlorobutene, vinyl bromide, vinyltrichlorosilane, vinyltriethoxysilane, methylvinyldichlorosilane, methylvinyldiethoxysilane, etc. Taking 3-chloropropene as an example, the hydrosilylation reaction generates chloropropylethyl dichlorosilane, and the reaction formula is as follows:
EtHSiCl 2 +CH 2 ＝CHCH 2 Cl——→Et(CH 2 CH 2 CH 2 Cl)SiCl 2
the boiling point of the various hydrosilylation reactants added in the reaction is lower than that of dimethyldichlorosilane or higher than that of dimethyldichlorosilane; the product of hydrosilylation reaction with ethyl dichlorosilane has certain boiling point difference with dimethyl dichlorosilane, preferably over 10 deg.c.
In the industrial synthesis process of the dimethyldichlorosilane, a small amount of terminal olefins are generated, but the type and the content are unstable, the small amount of terminal olefins existing in the reaction system also participate in the reaction, and the terminal olefins and the reactants containing terminal C = C double bonds are subjected to hydrosilylation reaction with the ethyldichlorosilane.
The invention has the beneficial effects that: according to the method, the ethyl dichlorosilane is converted through reaction, the boiling point difference between the product and the dimethyldichlorosilane is increased, particularly under the condition of the boiling point difference of more than 10 ℃, the system separation difficulty is effectively reduced, the number of tower plates for subsequent rectification separation operation is reduced, the content of the ethyl dichlorosilane in the product dimethyldichlorosilane can reach below 209ppm, the preferred parameter can be as low as below 10ppm, three wastes are not discharged, the process is continuous and stable, the operation is simple, the processing process is green and environment-friendly, and the industrial application value is high.
Drawings
FIG. 1 is a flow chart of a method for removing ethyldichlorosilane impurities from dimethyldichlorosilane.
In the figure, 1-dimethyldichlorosilane is fed; 2-addition reactant; 3-a reactor; 4-a reaction product; 5-a separation system; 6-recovering the reactant; 7-dimethyldichlorosilane; 8-ethyldichlorosilane addition product;
Detailed Description
The invention is further described with reference to the following detailed description and accompanying drawings:
adding dimethyldichlorosilane feed 1 containing ethyldichlorosilane and a hydrosilylation reactant 2 into a reactor 3 for reaction, controlling the circulating amount of the reactants and the molar ratio of dimethyldichlorosilane within the range of 3-8 2 PtCl 6 ·6H 2 O) or Karstedt catalyst, the concentration of the catalyst in the raw materials (namely the content of Pt in the catalytic activity center accounts for the total amount of the reaction raw materials) is 10-150ppm, and the form of the reactor can be a stirred tank, an external circulation reactor, a bubble column or a reaction rectifying tower.
And (3) the reacted product 4 enters a separation system 5, and the excessive reactant 6, the dimethyldichlorosilane 7 and the hydrosilylation reaction product 8 are separated by adopting a rectification mode through light and heavy removal operation. Generally comprising light and heavy removal operations, in matched combinations according to the boiling points of the reactants added and the products formed. The reactants and the reaction addition product have certain boiling point difference with the dimethyldichlorosilane, and the preferred boiling point difference is more than 10 ℃, which is more beneficial to the rectification separation operation. The surplus reactant obtained by separation returns to the reactor 5, and the dimethyldichlorosilane after the removal of the ethyldichlorosilane is taken as a product, and meanwhile, a corresponding addition product can be obtained as a byproduct.
Example 1
The content of ethyldichlorosilane in the feed is 1000ppm, ethylene is used as a reactant for reaction, an isopropanol solution of chloroplatinic acid hydrate is used as a catalyst, and the concentration of the catalyst is 15ppm. The reactor is a stirred tank reactor, the reaction volume is 5L, the operation pressure is 0.1MPaG, and the reaction temperature is 90 ℃. Controlling the molar ratio of the recycled reactant to the dimethyldichlorosilane to be 8:1, the reaction residence time is 0.2 hour, and the reaction kettle is provided with a jacket, an external circulation or an internal coil heater. The heating quantity is adjusted to stabilize the liquid level of the reaction kettle, reactants are continuously added, and reaction products enter a rectification system. And returning the light component ethylene after light component removal to the reactor in a gas phase mode, refining the rest mixture of the dimethyldichlorosilane and the diethyldichlorosilane through heavy component removal treatment to obtain a dimethyldichlorosilane product, and extracting the diethyldichlorosilane as a heavy component.
The addition reaction involved is
EtHSiCl 2 +C 2 H 4 ——→(C 2 H 5 ) 2 SiCl 2
The atmospheric boiling point of the main components of the material to be separated in the separation system is as follows: ethylene-103.9 deg.C, dimethyldichlorosilane 70.2 deg.C, diethyldichlorosilane 127.8 deg.C. The three can be easily separated by a rectification method.
The content of ethyldichlorosilane in dimethyldichlorosilane obtained by the above reaction and purification was 86.2ppm. And the generated diethyldichlorosilane is a chemical product with high value and has certain economic benefit.
Example 2
This example uses acetylene as the hydrosilylation reactant, an ethyldichlorosilane content of 1000ppm in the feed, a procedure similar to that using ethylene, an isopropanol solution of chloroplatinic acid hydrate as the catalyst, and a catalyst concentration of 150ppm. The reactor is a stirred tank reactor, the reaction volume is 5L, the operation pressure is 0MPaG, and the reaction temperature is 120 ℃. Controlling the molar ratio of the circulating amount of the reactants to the dimethyldichlorosilane to be 8:1, the reaction residence time is 1 hour, and the reaction kettle is provided with a jacket, an external circulation or an internal coil heater. The heating quantity is adjusted to stabilize the liquid level of the reaction kettle, reactants are continuously added, and reaction products enter a rectification system. The light acetylene component after light component removal returns to the reactor in a gas phase mode, the rest dimethyldichlorosilane, ethylvinyldichlorosilane and the double addition reaction mixture are refined through heavy component removal to obtain a dimethyldichlorosilane product Et (CH) 2 ＝CH)SiCl 2 And Et [ EtSiCl ] 2 (CHCH 3 )]SiCl 2 Withdrawn as heavies.
The reaction involved is an addition reaction of acetylene and ethyldichlorosilane:
EtHSiCl 2 +C 2 H 2 ——→Et(CH 2 ＝CH)SiCl 2
the ethyl vinyl dichlorosilane produced can be further subjected to a double addition reaction:
EtHSiCl 2 +Et(CH 2 ＝CH)SiCl 2 ——→Et[EtSiCl 2 (CHCH 3 )]SiCl 2
the atmospheric boiling point of the main components of the material to be separated in the separation system is as follows: acetylene-83.8 ℃, dimethyldichlorosilane 70.2 ℃, ethylvinyldichlorosilane 118 ℃ and the bis-addition product has a higher boiling point. These components can be separated relatively easily by rectification.
The content of ethyldichlorosilane in dimethyldichlorosilane obtained by the above reaction and purification was 3.5ppm. And the acetylene has high activity and double addition reaction, so that the acetylene has stronger capability of removing the ethyldichlorosilane than the ethylene.
Example 3
The content of ethyl dichlorosilane in the feed is 1000ppm, 1-octene is used as a reactant for reaction, karstedt catalyst is adopted, and the concentration of the catalyst is 10ppm. The reactor is a stirred tank reactor, the reaction volume is 5L, the operation pressure is 1.0MPaG, and the reaction temperature is 120 ℃. Controlling the molar ratio of the reactant circulation amount to the dimethyldichlorosilane to be 3:1, the reaction residence time is 0.1 hour, and the reaction kettle is provided with a jacket, an external circulation or an internal coil heater. The heating quantity is adjusted to stabilize the liquid level of the reaction kettle, reactants are continuously added, and reaction products enter a rectification system. Extracting a small amount of light component impurities after light component removal, performing heavy component removal treatment to obtain a dimethyldichlorosilane product, continuously rectifying and separating 1-octene and ethyloctyldichlorosilane serving as heavy components, and respectively obtaining incompletely reacted 1-octene which returns to a reactor and an ethyloctyldichlorosilane byproduct.
The addition reactions involved are:
EtHSiCl 2 +CH 2 ＝CH(C 5 H 10 )CH 3 ——→EtCH 2 (C 6 H 12 )CH 3 SiCl 2
the atmospheric boiling point of the main components of the material to be separated in the separation system is as follows: 1-octene at 122 deg.C, dimethyldichlorosilane at 70.2 deg.C, and ethyloctyldichlorosilane at boiling point above 180 deg.C. The three can be easily separated by a rectification method.
The content of ethyldichlorosilane in dimethyldichlorosilane obtained by the above reaction and purification was 209ppm. And the 1-octene is adopted as the hydrosilylation reactant, and has the additional advantages of higher boiling point, high content in liquid phase and relatively larger reaction driving force.
Example 4
The content of ethyldichlorosilane in the feed is 1000ppm, cyclohexene is used as a reactant for reaction, an isopropanol solution of chloroplatinic acid hydrate is used as a catalyst, and the concentration of the catalyst is 150ppm. The reactor is a stirred tank reactor, the reaction volume is 5L, the operation pressure is 0.5MPaG, and the reaction temperature is 100 ℃. Controlling the molar ratio of the circulating amount of the reactants to the dimethyldichlorosilane to be 3:1, the reaction residence time is 1 hour, and the reaction kettle is provided with a jacket, an external circulation or an internal coil heater. The heating quantity is adjusted to stabilize the liquid level of the reaction kettle, reactants are continuously added, and reaction products enter a rectification system. And removing light components, extracting a small amount of light component impurities, removing heavy components to obtain a dimethyldichlorosilane product, continuously rectifying and separating cyclohexene and cyclohexylethyldichlorosilane serving as heavy components to respectively obtain incompletely reacted cyclohexene, returning the incompletely reacted cyclohexene to the reactor, and a byproduct cyclohexylethyldichlorosilane.
The addition reactions involved are:
the atmospheric boiling point of the main components of the material to be separated in the separation system is as follows: cyclohexene 83 deg.C, dimethyl dichlorosilane 70.2 deg.C, and ethyl cyclohexyl dichlorosilane boiling point above 150 deg.C. The three can be easily separated by a rectification method.
The dimethyldichlorosilane that had been purified by the above reaction had an ethyldichlorosilane content of 6.9ppm.
Example 5
The content of ethyldichlorosilane in the feed is 1000ppm, acrylonitrile is used as a reactant for reaction, an isopropanol solution of chloroplatinic acid hydrate is used as a catalyst, and the concentration of the catalyst is 150ppm. The reactor is a stirred tank reactor, the reaction volume is 5L, the operation pressure is 0.4MPaG, and the reaction temperature is 150 ℃. Controlling the molar ratio of the circulating amount of the reactants to the dimethyldichlorosilane to be 4:1, the reaction residence time is 0.8 hour, and the reaction kettle is provided with a jacket, an external circulation or an internal coil heater. The heating quantity is adjusted to stabilize the liquid level of the reaction kettle, reactants are continuously added, and reaction products enter a rectification system. And removing light components, extracting a small amount of light component impurities, removing heavy components to obtain a dimethyldichlorosilane product, continuously rectifying and separating acrylonitrile and cyanopropyl cyclohexyl dichlorosilane serving as heavy components to respectively obtain incompletely reacted acrylonitrile, returning the incompletely reacted acrylonitrile to the reactor, and obtaining a byproduct cyanopropyl cyclohexyl dichlorosilane.
The addition reactions involved are:
EtHSiCl 2 +CH 2 ＝CHCN——→Et(CH 2 CH 2 CN)SiCl 2
the atmospheric boiling point of the main components of the material to be separated in the separation system is as follows: acrylonitrile 77.3 deg.c, dimethyl dichlorosilane 70.2 deg.c, and cyanopropyl cyclohexyl dichlorosilane with boiling point over 130 deg.c. The three can be separated easily by rectification.
The content of ethyldichlorosilane in dimethyldichlorosilane obtained by the above reaction and purification was 20.2ppm.
Example 6
The content of ethyldichlorosilane in the feed is 1000ppm, 3-chloropropene is used as a reactant for reaction, an isopropanol solution of chloroplatinic acid hydrate is used as a catalyst, and the concentration of the catalyst is 150ppm. The reactor is a stirred tank reactor, the reaction volume is 5L, the operation pressure is 0.5MPaG, and the reaction temperature is 150 ℃. Controlling the molar ratio of the circulating amount of the reactants to the dimethyldichlorosilane to be 4:1, the reaction residence time is 1 hour, and the reaction kettle is provided with a jacket, an external circulation or an internal coil heater. The heating quantity is adjusted to stabilize the liquid level of the reaction kettle, reactants are continuously added, and reaction products enter a rectification system in a gas phase. And returning the light component chloropropene subjected to light component removal to the reactor in a gas phase manner, and refining the rest dimethyldichlorosilane and chloropropylethyldichlorosilane through heavy component removal to obtain a dimethyldichlorosilane product and chloropropylethyldichlorosilane.
The addition reactions involved are:
EtHSiCl 2 +CH 2 ＝CHCH 2 Cl——→Et(CH 2 CH 2 CH 2 Cl)SiCl 2
the atmospheric boiling point of the main components of the material to be separated in the separation system is as follows: chloropropene 44.96 deg.C, dimethyldichlorosilane 70.2 deg.C, chloropropylethyldichlorosilane boiling point about 155 deg.C. The three can be separated easily by rectification.
The content of ethyldichlorosilane in dimethyldichlorosilane obtained by the above reaction and purification was 5.1ppm.
Example 7
The content of ethyldichlorosilane in the feed is 1000ppm, allylamine is used as a reactant for reaction, karstedt catalyst is adopted, and the catalyst concentration is 10ppm. The reactor is a stirred tank reactor, the reaction volume is 5L, the operation pressure is 0.2MPaG, and the reaction temperature is 120 ℃. Controlling the molar ratio of the recycled reactant to the dimethyldichlorosilane to be 4:1, the reaction residence time is 0.2 hour, and the reaction kettle is provided with a jacket, an external circulation or an internal coil heater. The heating quantity is adjusted to stabilize the liquid level of the reaction kettle, reactants are continuously added, and reaction products enter a rectification system. And (3) returning light component allyl amine after light component removal to the reactor in a gas phase mode, and refining the remaining mixture of dimethyldichlorosilane and propylaminoethyldichlorosilane through heavy component removal treatment to obtain dimethyldichlorosilane products and propylaminoethyldichlorosilane.
The addition reactions involved are:
EtHSiCl 2 +CH 2 ＝CHCH 2 NH2——→Et(CH 2 CH 2 CH 2 NH 2 )SiCl 2
the atmospheric boiling point of the main components of the material to be separated in the separation system is as follows: allyl amine 53.3 deg.C, dimethyl dichlorosilane 70.2 deg.C, and propylamino ethyl dichlorosilane boiling point greater than 90 deg.C. The three can be separated easily by rectification.
The ethyldichlorosilane content in the dimethyldichlorosilane obtained by the above-mentioned reaction and purification was 87.4ppm.
Example 8
The content of ethyldichlorosilane in the feed is 1000ppm, styrene is used as a reactant for reaction, an isopropanol solution of chloroplatinic acid hydrate is used as a catalyst, the concentration of the catalyst is 100ppm, the reactor is a stirred tank reactor, the reaction volume is 5L, the operation pressure is 0.5MPaG, and the reaction temperature is 200 ℃. Controlling the molar ratio of the recycled reactant to the dimethyldichlorosilane to be 4:1, the reaction residence time is 1 hour, and the reaction kettle is provided with a jacket, an external circulation or an internal coil heater. The heating quantity is adjusted to stabilize the liquid level of the reaction kettle, reactants are continuously added, and reaction products enter a rectification system. And (3) extracting a small amount of light component impurities after light component removal, removing heavy components to obtain a dimethyldichlorosilane product, continuously rectifying and separating styrene and ethyl phenyl dichlorosilane serving as heavy components to respectively obtain incompletely reacted styrene which returns to the reactor and a byproduct ethyl phenyl dichlorosilane.
The addition reactions involved are:
EtHSiCl 2 +PhCH＝CH 2 ——→Et(PhCH 2 CH 2 )SiCl 2
the atmospheric boiling point of the main components of the material to be separated in the separation system is as follows: styrene 145 ℃, dimethyl dichlorosilane 70.2 ℃ and ethyl phenyl dichlorosilane boiling point more than 200 ℃. The three can be easily separated by a rectification method.
The content of ethyldichlorosilane in dimethyldichlorosilane obtained by the above reaction and purification was 2.3ppm.
While the methods and techniques of the present invention have been described in terms of preferred embodiments, it will be apparent to those of ordinary skill in the art that variations and/or modifications of the methods and techniques described herein may be made without departing from the spirit and scope of the invention. It is expressly intended that all such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and content of the invention.
Claims (9)
1. A method for removing ethyldichlorosilane impurities in dimethyldichlorosilane is characterized by comprising a reactor and a separation system; adding dimethyl dichlorosilane feed containing ethyldichlorosilane and a hydrosilylation reaction product into a reactor for reaction, adopting an isopropanol solution of chloroplatinic acid hydrate or a Karstedt catalyst, enabling a product after the reaction to enter a separation system, and separating excessive reactants, the dimethyl dichlorosilane and the hydrosilylation reaction product by light and heavy removal operations in a rectification mode;
the hydrosilylation reactant is any one of the following:
(1) C2-C20 terminal olefins and diolefins;
(2) Terminal olefins with benzene rings;
(3) A C4-C20 cyclic olefin;
(4) A terminal unsaturated bond compound containing a nitrogen atom group;
(5) Terminal olefins substituted with CN-containing groups;
(6)C 2 -C 10 terminal alkyne;
(7) Terminal olefins substituted with halogen groups.
2. The process of claim 1 wherein the molar ratio of recycled reactant to dimethyldichlorosilane is in the range of 3.
3. The process as claimed in claim 1, wherein the reaction pressure is from 0 to 1.0MPaG.
4. The process as claimed in claim 1, wherein the reaction temperature is from 50 to 200 ℃.
5. The process as claimed in claim 1, wherein the reaction residence time is from 0.1 to 1 hour.
6. The process as claimed in claim 1, wherein the catalyst concentration is from 10 to 150ppm.
7. The process as claimed in claim 1, wherein the reactor is in the form of a stirred tank, an external loop reactor, a bubble column or a reactive rectification column.
8. The method of claim 1 wherein the separation system comprises light and heavy removal operations, wherein cuts are made and matched according to the boiling points of the components to produce dimethyldichlorosilane, addition reactant, and a fraction of the addition reaction product; the surplus reactant obtained by separation returns to the reactor, and the dimethyldichlorosilane after the ethyldichlorosilane is removed is taken as a product, and simultaneously, a corresponding addition product is also obtained as a byproduct.
9. The method of claim 1 wherein each type of hydrosilylation reactant added to the reaction has a boiling point lower than dimethyldichlorosilane or higher than dimethyldichlorosilane; the product of hydrosilylation reaction with ethyl dichlorosilane has boiling point difference between reactant and dimethyl dichlorosilane over 10 deg.c.
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