A kind of impurity removal process of hydrolyzing dimethyldichlorosilane to produce hydrogen chloride

Abstract

The present invention is an impurity removal process for producing hydrogen chloride by hydrolysis of dimethyldichlorosilane. An impurity removal process for producing hydrogen chloride by hydrolysis of dimethyldichlorosilane, comprising the following steps: after the normal temperature hydrogen chloride gas produced in the dimethyldichlorosilane hydrolysis section reacts with a high temperature saturated zinc chloride solution in a reaction tower, high temperature hydrogen chloride gas is produced at the top of the reaction tower, which is cooled and separated. An impurity removal process for producing hydrogen chloride by hydrolysis of dimethyldichlorosilane described in the present invention uses a high temperature saturated zinc chloride solution to catalyze dehydration polymerization of low molecular weight siloxanes in hydrogen chloride in a reaction tower and then separate them, which can remove most of the siloxane impurities carried in the hydrogen chloride produced by the hydrolysis of dimethyldichlorosilane in the production of organic silicon, and prevent it from clogging equipment and pipelines in the methyl chloride synthesis system.

Description

Technical Field

[0001] The invention specifically relates to an impurity removal process for producing hydrogen chloride by hydrolyzing dimethyldichlorosilane. Background Art

[0002] The hydrolysis and polymerization section of organosilicon dimethyldichlorosilane can produce hydrogen chloride gas with a pressure of 200kPag as a by-product, which can be directly used for methyl chloride synthesis. However, in the actual industrial production process, this part of hydrogen chloride gas contains trace amounts of low-molecular substances such as siloxanes, which cannot be removed by filtration, deep cold condensation and other methods. Therefore, trace amounts of siloxanes and impurity silanes are brought into the organosilicon methyl chloride production process, and there is a situation where siloxanes self-polymerize to form solid impurities that block pipelines, heat exchangers, absorption towers, reactors, etc. As a result, in the existing organosilicon production line, due to the influence of siloxanes carried in hydrogen chloride, the methyl chloride production line is frequently overhauled, which wastes a lot of manpower and material resources, and seriously affects the production capacity of the production system.

[0003] In view of this, the present invention proposes an impurity removal process for hydrolyzing dimethyldichlorosilane to produce hydrogen chloride, which can remove impurities therein and avoid the above-mentioned problems. Summary of the invention

[0004] The object of the present invention is to provide an impurity removal process for producing hydrogen chloride by hydrolysis of dimethyldichlorosilane, which can remove a large amount of low molecular weight siloxane and impurity silane carried in hydrogen chloride to avoid clogging equipment and pipelines in a chloromethane synthesis system, and can extend the continuous operation period of the chloromethane synthesis system to more than three years.

[0005] In order to achieve the above purpose, the technical solution adopted is:

[0006] A process for removing impurities from dimethyldichlorosilane by hydrolysis to produce hydrogen chloride is as follows:

[0007] After the room-temperature hydrogen chloride gas produced in the dimethyldichlorosilane hydrolysis section reacts with the high-temperature saturated zinc chloride solution in the reaction tower, high-temperature hydrogen chloride gas is produced at the top of the reaction tower for cooling and separation.

[0008] Furthermore, the temperature of the high temperature saturated zinc chloride solution is 160±5°C.

[0009] Furthermore, the bottom of the reaction tower is a liquid silicone oil polymer. After stratification, the lower layer of solution is heated to 160±5° C. and then enters the reaction tower.

[0010] Furthermore, after the liquid phase silicone oil polymer is separated into layers in the separator, the lower layer of the solution is transported to the circulation heater through the kettle liquid circulation pump for heating and then enters the reaction tower.

[0011] Furthermore, the solution in the lower layer is heated and then enters the reaction tower from the top of the tower.

[0012] Furthermore, after the high-temperature hydrogen chloride gas is taken out from the top of the tower, it is deep-cooled to -10±10°C and then subjected to gas-liquid separation.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] The technical scheme of the present invention uses a high-temperature saturated zinc chloride solution as a catalyst to dehydrate and polymerize low-molecular siloxane in hydrogen chloride gas in a reaction tower, and a part of the polymerized high-molecular siloxane is mixed with the high-temperature zinc chloride solution and enters a stratifier for stratification, and then the siloxane is discharged from the upper part of the stratifier. Another part of the siloxane with a relatively low molecular weight is extracted from the top of the reaction tower along with the hydrogen chloride gas and enters a condenser for deep cooling. After high-temperature catalytic polymerization, 99% of this part of the siloxane can be liquefied in the condenser, and most of the impurities in the cooled hydrogen chloride gas have been removed, so the siloxane can be used as a reaction raw material in a chloromethane synthesis system, and there will be no system blockage in a short time. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The process flow chart of the technical solution of the present invention; wherein 1 is a reaction tower, 2 is a stratifier, 3 is a kettle liquid circulation pump, 4 is a circulation heater, 5 is a tower top cooler, and 6 is a gas-liquid separation tank. DETAILED DESCRIPTION

[0016] In order to further illustrate the impurity removal process of hydrolyzing dimethyldichlorosilane to produce hydrogen chloride according to the present invention and achieve the intended purpose of the invention, the following is a detailed description of the specific implementation method, structure, characteristics and efficacy of the impurity removal process of hydrolyzing dimethyldichlorosilane to produce hydrogen chloride according to the present invention in combination with the preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0017] The following will further introduce in detail the impurity removal process of hydrolyzing dimethyldichlorosilane to produce hydrogen chloride in combination with specific embodiments of the present invention:

[0018] A process for removing impurities from dimethyldichlorosilane by hydrolysis to produce hydrogen chloride is as follows:

[0019] After the room-temperature hydrogen chloride gas produced in the dimethyldichlorosilane hydrolysis section reacts with the high-temperature saturated zinc chloride solution in the reaction tower, high-temperature hydrogen chloride gas is produced at the top of the reaction tower for cooling and separation.

[0020] Preferably, the temperature of the high temperature saturated zinc chloride solution is 160±5°C.

[0021] Preferably, the bottom of the reaction tower is a liquid silicone oil polymer. After stratification, the lower layer of solution is heated to 160±5° C. and then enters the reaction tower.

[0022] Further preferably, after the liquid phase silicone oil polymer is separated into layers in the separator, the lower layer of the solution is transported to the circulation heater through a kettle liquid circulation pump for heating and then enters the reaction tower.

[0023] Further preferably, the solution in the lower layer is heated and then enters the reaction tower from the top of the tower.

[0024] Preferably, the high-temperature hydrogen chloride gas is extracted from the top of the tower, deep-cooled to -10±10°C, and then subjected to gas-liquid separation.

[0025] Example 1.

[0026] Combination Figure 1 , the specific steps are as follows:

[0027] The room temperature hydrogen chloride gas (A) produced in the dimethyldichlorosilane hydrolysis section enters the reaction tower 1, and the top of the tower enters the high temperature saturated zinc chloride solution. The high temperature saturated zinc chloride solution is: the zinc chloride solution delivered by the kettle liquid circulation pump 3 passes through the circulation heater 4, is heated to 160±5°C, and a high temperature saturated zinc chloride solution (about 75wt%) is obtained.

[0028] After the hydrogen chloride gas entering the reaction tower 1 contacts the high-temperature zinc chloride solution in the tower to polymerize the siloxane, part of the high-molecular siloxane becomes a liquid silicone oil polymer, which is carried to the tower kettle along with the high-temperature zinc chloride solution. Then, after stratification in the stratifier 2, the oil-phase polymerized siloxane (B) is discharged from the upper part of the stratifier 2. The stratified zinc chloride solution is transported to the circulation heater 4 through the kettle liquid circulation pump 3 to be heated to 160±5°C before entering the reaction tower.

[0029] The high-temperature hydrogen chloride gas generated at the top of the reaction tower 1 is extracted from the top of the tower and enters the top cooler 5 for deep cooling to -10±10°C. The deep-cooled hydrogen chloride gas enters the gas-liquid separation tank 6 for separation, and the high-purity hydrogen chloride gas (C) is extracted from the top of the gas-liquid separation tank, and the condensed siloxane cold oil (D) produced after deep cooling is extracted from the bottom of the gas-liquid separation tank.

[0030] During the production of organosilicon, dimethyldichlorosilane is hydrolyzed to produce siloxane impurities carried in hydrogen chloride. During the next reaction of hydrogen chloride, these siloxane impurities may cause gelling and blockage of pipelines and equipment, seriously affecting the operation cycle of the organosilicon methyl chloride production unit.

[0031] In order to solve the above problems, the present invention proposes a new process for removing impurities from hydrogen chloride gas produced by the hydrolysis of dimethyldichlorosilane in the production process of organic silicon. The low molecular weight siloxane in the hydrogen chloride is catalytically dehydrated and polymerized in the reaction tower using a high-temperature saturated zinc chloride solution and then separated. This can remove most of the siloxane impurities carried in the hydrogen chloride produced by the hydrolysis of dimethyldichlorosilane in the production of organic silicon. The hydrogen chloride impurity removal process in the technical solution of the present invention can remove a large amount of low molecular weight siloxane and impurity silane carried in the hydrogen chloride, avoiding clogging of equipment and pipelines in the methyl chloride synthesis system, and extending the continuous operation period of the methyl chloride synthesis system from 3-6 months to more than 3 years.

[0032] The above is only a preferred embodiment of the embodiment of the present invention, and does not impose any form of limitation on the embodiment of the present invention. Any simple modification, equivalent changes and modifications made to the above embodiment based on the technical essence of the embodiment of the present invention are still within the scope of the technical solution of the embodiment of the present invention.

Claims

1. An impurity removal process for producing hydrogen chloride by hydrolysis of dimethyldichlorosilane, characterized in that: The following steps are involved: After the room temperature hydrogen chloride gas produced in the dimethyldichlorosilane hydrolysis stage reacts with the high temperature saturated zinc chloride solution in the reaction tower, the hydrogen chloride gas is taken out from the top of the reaction tower, cooled and separated; The temperature of the high-temperature saturated zinc chloride solution is 160±5°C.

2. The impurity removal process according to claim 1, characterized in that: The reactor of the reaction tower is a liquid silicone oil polymer. After stratification, the lower layer of solution is heated to 160±5° C. and then enters the reaction tower.

3. The impurity removal process according to claim 2, characterized in that: After the liquid phase silicone oil polymer is separated into layers in the separator, the lower layer of the solution is transported to the circulation heater through the kettle liquid circulation pump for heating and then enters the reaction tower.

4. The impurity removal process according to claim 3, characterized in that: After the solution in the lower layer is heated, it enters the reaction tower from the top of the tower.

5. The impurity removal process according to claim 1, characterized in that: After the high-temperature hydrogen chloride gas is taken out from the top of the tower, it is deep-cooled to -10±10°C and then separated into gas and liquid.

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