Method for preparing high purity alkoxysilanes from polysilicon byproduct silicon tetrachloride

A technology of high-purity alkoxysilane and silicon tetrachloride, applied in the direction of chlorine/hydrogen chloride, silicon organic compounds, etc., can solve the problems of blocked pipelines, silicon tetrachloride is volatile, etc., and achieves increased productivity and stable product quality , the effect of reducing dosage

Active Publication Date: 2011-10-26
SICHUAN YINBANG SILICON IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0018] The first purpose of the present invention is to improve the above method, effectively solve the problem that silicon tetrachloride is extremely volatile, and forms solid silicon dioxide with moisture in the air to block the pipeline

Method used

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  • Method for preparing high purity alkoxysilanes from polysilicon byproduct silicon tetrachloride
  • Method for preparing high purity alkoxysilanes from polysilicon byproduct silicon tetrachloride

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0053] Embodiment 1 Utilizes polysilicon by-product silicon tetrachloride to prepare high-purity tetraethoxysilane

[0054] A small amount of ethanol is pre-added in the packed reaction tower, and the molar ratio of silicon tetrachloride and ethanol is 1.0:4.1 and simultaneously passed into the reaction tower. Reaction material of ethoxysilane and hydrogen chloride. The hydrogen chloride gas generated by the reaction is absorbed by water in a graphite absorber to obtain industrial hydrochloric acid.

[0055] Press the reaction material into the acid catcher, slowly heat to the bottom temperature of 130°C, distill off the unreacted raw materials and part of hydrogen chloride; add the acid catcher ethanol for the first time, the dosage is 1.0 times the mole of silicon tetrachloride, Heating to the bottom temperature of 130°C, distilling off the acid dispersing agent and hydrogen chloride; adding the acid catching agent ethanol for the second time, the dosage is 1.0 times the mo...

Embodiment 2

[0066] A small amount of recovering agent was pre-added in the packed reaction tower, and silicon tetrachloride and the recovering agent recovered in Example 1 (calculated as pure ethanol) were simultaneously passed into the reaction tower at a molar ratio of 1.0:4.1. Other conditions are with embodiment 1.

[0067] The purity of the tetraethoxysilane product is 99.6%, and the yield is over 96%. Each batch of finished tetraethoxysilane is a colorless transparent liquid, specific gravity 0.934 (20°C), acidity (HCl) ≤ 10ppm, boiling point 169°C, kinematic viscosity 0.7mm 2 / s.

[0068] Each batch of finished polyethoxysilane is a colorless transparent liquid with a purity of 98%, an acidity (HCl) ≤ 10ppm, a specific gravity of 0.96-1.00 (20°C), and a kinematic viscosity of 1-1.6mm 2 / s, the content of silicon in polyethoxysilane is SiO 2 Calculated as 30 to 34%.

Embodiment 3

[0070] Ethanol and recovering agent (in terms of pure ethanol) are passed into the ethanol batching tank in a molar ratio of 1.0: 1.0, a small amount of ethanol mixed solution is added in advance in the packed reaction tower, and then the molar ratio of silicon tetrachloride and ethanol mixed solution is 1.0:4.1 is passed into the reaction tower at the same time. Other conditions are with embodiment 1.

[0071] The purity of the tetraethoxysilane product is 99.7%, and the yield is over 95%. Each batch of finished tetraethoxysilane is a colorless transparent liquid, specific gravity 0.934 (20°C), acidity (HCl) ≤ 10ppm, boiling point 169°C, kinematic viscosity 0.7mm 2 / s.

[0072] Each batch of finished polyethoxysilane is a colorless transparent liquid with a purity of 98%, an acidity (HCl) ≤ 10ppm, a specific gravity of 0.96-1.00 (20°C), and a kinematic viscosity of 1-1.6mm 2 / s, the content of silicon in polyethoxysilane is SiO 2 Calculated as 30 to 34%.

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Abstract

The invention which relates to a method for preparing high purity alkoxysilanes from a polysilicon byproduct silicon tetrachloride belongs to the technical field of polysilicon production. The technical scheme of the invention comprises the following steps: silicon tetrachloride is reacted with lower fatty alcohol under conditions of normal temperature and normal pressure to obtain a reaction material containing tetraalkoxysilanes and hydrogen chloride; an acid removing agent is added for several times to remove hydrogen chloride to make the PH to be equal to or more than 4, an alkaline substance is added to neutralize to make the PH value to achieve 6 to 9, and rectification is carried out with controlling a reflux ratio of not less than 3:1 to obtain alkoxysilane products with the purity of equal to or more than 99% and the hydrogen chloride content of equal to or less than 10 ppm. The method of the present invention allows comprehensive recycling of the polysilicon byproduct silicon tetrachloride to be realized, the productivity to be large, the cost to be low, system equipment to be simple, the hydrogen chloride content in the prepared alkoxysilane products to be equal to or less than 10 ppm, and the purity to be more than 99.9%.

Description

technical field [0001] The invention relates to a method for preparing high-purity alkoxysilane from polysilicon by-product silicon tetrachloride, and belongs to the technical field of polysilicon production. Background technique [0002] Tetraalkoxysilane is an important organic silicon intermediate, which can be used in the fields of antirust zinc-rich coatings, precision casting and refractory materials, and is a class of fine chemicals with a wide range of uses. There are many preparation methods of tetraalkoxysilane, but so far there are only two routes for real industrialization, namely the silicon powder method and the silicon tetrachloride method. The silicon powder method needs to be reacted under the conditions of high temperature, high pressure and catalyst, which requires large equipment investment and high energy consumption; this method uses silicon powder as a raw material, which has high cost and high purity requirements for raw materials. In contrast, the s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07F7/04C01B7/01
Inventor 牟浩斌易家宝邹振
Owner SICHUAN YINBANG SILICON IND
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