Utilization of chlorosilane high boiling compound

What are the ingredients of these high boiling substances? Hexachlorodisilane (Si2Cl6)? Hexachlorodisiloxane (Si2OCl6)? After reading some literatures, it is said that hexachlorodisilane purified from the high boiling residue is still very useful. Hexachlorodisilane (Si2Cl6) is a highly efficient deoxidizer and a raw material for the production of ethane, which can be used to produce amorphous silicon films, optical fiber raw materials, glass, MoSi2, etc. Among them, the manufacturing of silicon nitride films is the most important use. Compared with the traditional silicon nitride films prepared by dichlorosilane and silane vapor deposition, the hexachlorodisilane vapor deposition method has low deposition temperature, low deposition pressure, high efficiency, and better density, insulation, corrosion resistance, and compatibility of the obtained films. At present, its market price is expensive, with a purity of more than 98% reaching 370 dollars/kg, which is the most valuable part of the residue. However, it is said that this is rarely purified in China.

Previously, a group of high boiling materials were directly hydrolyzed to produce metasilicic acid, and then dissolved in liquid alkali to produce sodium metasilicate, but the same preparation effect was not good. First, there is no obvious crystallization of sodium metasilicate; second, the yield is very low, and the amount of liquid alkali is not easy to control.

The purification cost of hexachlorosilane is very high, and three additional towers are needed. And the current output is far from the goal of purification. Due to the limited analytical instruments in the factory, I only used the thermal conductivity cell gas chromatography to do an analysis. The content of silicon tetrachloride in the clear liquid distilled at high temperature from the high boiling point was more than 50%, and the content of low boiling point was about 1%. Other components were used as standard samples. According to the literature, there are other metal chloride impurities such as phosphorus trichloride, titanium tetrachloride, aluminum trichloride, etc. The content of hexachlorosilane is in the range of 10%.