A method for effectively removing high boiling point impurities in dimethyldichlorosilane

Abstract

The invention discloses a method for effectively removing high-boiling-point impurities in dimethyldichlorosilane. The method comprises the following steps: preheating and overheating the dimethyl obtained by an organosilicon distillation process, and then introducing the dimethyl into a catalytic reactor together with a promoter for catalytic reaction to convert ethyl hydrochlorosilane impurities into dimethyl; the promoter is hydrogen chloride gas or chlorine gas; the catalyst of the catalytic reaction is an aluminum chloride system, wherein the aluminum chloride is 80-90 parts, the platinum is 3-6 parts, and the rhodium is 3-6 parts.

Description

Technical Field

[0001] The invention belongs to the technical field of organic silicon, and particularly relates to a method for effectively removing high-boiling-point impurities in dimethyldichlorosilane. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] At present, in addition to the target product dimethyldichlorosilane (dimethyl, which accounts for about 85%), there are still many other chlorosilane by-products in the methylchlorosilane monomer mixture (crude monomer) of the silicone monomer industry, including monomethyltrichlorosilane (monomethyl), trimethylmonochlorosilane (trimethyl), methylhydrogendichlorosilane (monomethyl containing hydrogen), dimethylhydrogenmonochlorosilane (dimethyl containing hydrogen), low-boiling substances, high-boiling substances, etc. The crude monomer needs to be further distilled and purified to obtain dimethyl.

[0004] After years of research, the inventors found that the boiling point of an ethylchlorosilane impurity in the crude monomer is close to that of dimethylbenzene, and it is difficult to remove it by distillation, thus affecting the final product quality of the target product dimethylbenzene. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for effectively removing high-boiling-point impurities in dimethyldichlorosilane, that is, the raw material product is heated and vaporized, and after adding a small amount of promoter, it enters a reactor with a catalyst. Under certain temperature and pressure conditions, the impurities are converted into normal products through catalytic reaction and enter a subsequent system, which is beneficial to improve the purity of dimethyldichlorosilane.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A method for effectively removing high boiling point impurities in dimethyldichlorosilane comprises the following steps:

[0008] After preheating and overheating, the dimethylbenzene obtained by the organosilicon distillation process is placed in a catalytic reactor together with a promoter for catalytic reaction, thereby converting the ethyl hydrochlorosilane impurity into a substance with a higher boiling point, which is convenient for separation from the dimethylbenzene;

[0009] The accelerator is hydrogen chloride gas or chlorine gas;

[0010] The catalyst for the catalytic reaction is an aluminum chloride system, wherein the aluminum chloride accounts for 80-90 parts, the platinum accounts for 3-6 parts, and the rhodium accounts for 3-6 parts.

[0011] The beneficial effects of the present invention are as follows:

[0012] The ethylhydrochlorosilane impurity in dimethylformamide can be effectively removed by catalytic reaction to improve the purity of dimethylformamide.

[0013] After research and development, the inventors first converted and removed high-boiling impurities close to dimethyl through catalytic reaction under certain reaction conditions, and finally obtained dimethyl products with higher purity. In this way, the quality of dimethyl products can be improved, and the quality of subsequent products can be correspondingly improved, thereby improving the market competitiveness of products.

[0014] The role of hydrogen chloride gas or chlorine gas promoter is to promote bond breaking and increase the selection of chlorine element. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0016] Figure 1 It is a schematic diagram of the structure of a system for removing high-boiling-point impurities in dimethyldichlorosilane according to one or more embodiments of the present invention.

[0017] In the figure: the distances or sizes between parts are exaggerated to show the positions of the parts, and the schematic diagram is for illustration only;

[0018] Among them, 1-preheater, 2-superheater, 3-catalytic reactor, 4-filter, 5-condenser. DETAILED DESCRIPTION

[0019] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0020] A method for effectively removing high boiling point impurities in dimethyldichlorosilane comprises the following steps:

[0021] After preheating and overheating, the dimethylbenzene obtained by the organosilicon distillation process is placed in a catalytic reactor together with a promoter for catalytic reaction to convert the ethyl hydrochlorosilane impurity into a substance with a higher boiling point;

[0022] The accelerator is hydrogen chloride gas or chlorine gas;

[0023] The catalyst for the catalytic reaction is an aluminum chloride system, wherein the aluminum chloride accounts for 80-90 parts, the platinum accounts for 3-6 parts, and the rhodium accounts for 3-6 parts.

[0024] The functions of each component in the catalyst are:

[0025] Aluminum chloride: As the main carrier of the catalyst, it mainly provides enough chlorine element to achieve ion exchange, generate the target product, and facilitate separation.

[0026] Platinum: Suitable for silicon addition and hydrosilylation reactions.

[0027] Rhodium: Generally used together with platinum to accelerate the catalytic reaction.

[0028] In some embodiments, in the catalyst, the aluminum chloride content is 80-85 parts, the platinum content is 4-5 parts, and the rhodium content is 4-5 parts.

[0029] In some embodiments, the temperature of the dimethylformamide obtained by the organosilicon distillation process after superheat treatment is greater than 120°C.

[0030] In some embodiments, the volume fraction of the accelerator added to the dimethylformamide is less than or equal to 0.1%.

[0031] In some embodiments, the temperature of the catalytic reaction is 125-135° C., and the reaction pressure is 0.1-0.25 MPa.

[0032] Preferably, the temperature of the catalytic reaction is 128-131°C.

[0033] In some embodiments, the gas velocity in the catalytic reactor is 0.2-0.5 m / s, and the reaction time is 5-30 s.

[0034] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0035] Example 1

[0036] like Figure 1 As shown, in the dimethyl material, the impurity peak detected by chromatography accounts for about 0.0015%. After being vaporized by steam preheater 1, it is superheated to about 129°C by superheater 2. The laboratory hydrogen chloride gas cylinder supplies hydrogen chloride as a promoter and enters the catalytic reactor 3 together with the overheated dimethyl gas phase. The amount of hydrogen chloride added is 0.1% of the volume of the dimethyl material. The reactor is heated by a jacket, the reaction temperature is controlled between 128-131°C, and the reaction pressure is 0.2MPa. In the catalyst, the number of aluminum chloride is 85 parts, the number of platinum is 5 parts, and the number of rhodium is 5 parts.

[0037] The reactor uses porcelain balls as catalyst supports, and the catalyst is dried and dehydrated before being put into operation. In addition, the catalyst cannot be packed too tightly and must have a certain degree of looseness. The reaction time is not less than 30s, and the impurities are filtered out from the bottom of the reactor through the filter 4, and then condensed and recovered by the condenser 5 to obtain pure liquid dimethyl material. Finally, the dimethyl product is obtained, and the impurity peak (ethyl hydrochlorosilane) is shown to be 0.000% by chromatographic detection.

[0038] Example 2

[0039] The difference from Example 1 is that in the catalyst, the number of aluminum chloride is 81 parts, the number of platinum is 4 parts, the number of rhodium is 6 parts, and the rest is the same as Example 1. The impurity peak (ethyl hydrochlorosilane) of the finally obtained dimethyl product is 0.000% by chromatographic detection.

[0040] Example 3

[0041] The difference from Example 1 is that in the catalyst, the number of aluminum chloride is 90 parts, the number of platinum is 6 parts, the number of rhodium is 3 parts, and the rest is the same as Example 1. The impurity peak (ethyl hydrochlorosilane) of the finally obtained dimethyl product is 0.000% by chromatographic detection.

[0042] Comparative Example 1

[0043] The difference from Example 1 is that platinum is omitted from the catalyst, and the rest is the same as Example 1. The impurity peak (ethyl hydrochlorosilane) of the finally obtained dimethyl product is 0.0012% after chromatographic detection.

[0044] Comparative Example 2

[0045] The difference from Example 1 is that the catalyst is free of rhodium, and the rest is the same as Example 1. Finally, the obtained dimethyl product has an impurity peak (ethyl hydrochlorosilane) of 0.001% as detected by chromatography.

[0046] Comparative Example 3

[0047] The difference from Example 1 is that the catalyst is omitted from platinum and rhodium, and the rest is the same as Example 1. The impurity peak (ethyl hydrochlorosilane) of the finally obtained dimethyl product is 0.0014% after chromatographic detection.

[0048] Comparative Example 4

[0049] The difference from Example 1 is that the promoter hydrogen chloride is omitted, and the rest is the same as Example 1. The impurity peak (ethyl hydrochlorosilane) of the finally obtained dimethyl product is 0.0011% after chromatographic detection.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for effectively removing high boiling point impurities in dimethyldichlorosilane, characterized in that: The steps include: The dimethylbenzene obtained by the organic silicon distillation process is preheated and overheated, and then put into a catalytic reactor together with a promoter for catalytic reaction to convert the ethyl hydrochlorosilane impurity into dimethylbenzene; The accelerator is hydrogen chloride gas or chlorine gas; The catalyst for the catalytic reaction is an aluminum chloride system, wherein the aluminum chloride is 80-90 parts, the platinum is 3-6 parts, and the rhodium is 3-6 parts; The volume fraction of the accelerator added to the dimethylformamide is less than or equal to 0.1%; The gas velocity in the catalytic reactor is 0.2-0.5 m / s, and the reaction time is 5-30 s.

2. The method for effectively removing high boiling point impurities in dimethyldichlorosilane according to claim 1, characterized in that: In the catalyst, the proportion of aluminum chloride is 80-85 parts, the proportion of platinum is 4-5 parts, and the proportion of rhodium is 4-5 parts.

3. The method for effectively removing high boiling point impurities in dimethyldichlorosilane according to claim 1, characterized in that: The temperature of the dimethylformamide obtained by the organosilicon distillation process after superheat treatment is greater than 120°C.

4. The method for effectively removing high boiling point impurities in dimethyldichlorosilane according to claim 1, characterized in that: The temperature of the dimethylformamide obtained by the organosilicon distillation process after superheat treatment is 125-140°C.

5. The method for effectively removing high boiling point impurities in dimethyldichlorosilane according to claim 1, characterized in that: The volume fraction of the accelerator added to dimethylbenzene is 0.01%-0.1%.

6. The method for effectively removing high boiling point impurities in dimethyldichlorosilane according to claim 5, characterized in that: The volume fraction of the accelerator added to dimethylbenzene is 0.05%-0.1%.

7. The method for effectively removing high boiling point impurities in dimethyldichlorosilane according to claim 1, characterized in that: The temperature of the catalytic reaction is 125-135°C, and the reaction pressure is 0.1-0.25MPa.

8. The method for effectively removing high boiling point impurities in dimethyldichlorosilane according to claim 7, characterized in that: The temperature of the catalytic reaction is 128-131°C.

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