TRICHLOROSILANE PRODUCTION PROCESS Russian patent published in 2006 - IPC C01B33/107 

FIELD: silicon compounds technology.

SUBSTANCE: invention relates to processes of producing trichlorosilane from silicon tetrachloride and can be used for utilization of silicon tetrachloride formed in production of polycrystalline silicon via hydrogen reduction of trichlorosilane. Starting mixture of components for hydrogenation of silicon tetrachloride is prepared in vaporizer by bubbling hydrogen through silicon tetrachloride bed at temperature and pressure assuring formation of vapor-gas mixture at hydrogen-to-silicon tetrachloride molar ratio (1-3):1. The vapor-gas mixture is passed to hydrogenation reactor wherein heating elements and screens, used as reaction surfaces and made from graphite and/or carbon-carbon composites, are installed inside reaction space. Hydrogenation is carried out in closed recirculation circuit. Vapor-gas mixture leaving hydrogenation reactor contains trichlorosilane, silicon tetrachloride, hydrogen chloride, and hydrogen. Silicon tetrachloride, trichlorosilane, hydrogen chloride, and hydrogen are consecutively isolated into separate products. Silicon tetrachloride is separated by condensation and resulting condensate is subjected to rectification to produce pure silicon tetrachloride, which is returned into vaporizer. After that, remaining vapor-gas mixture containing trichlorosilane, hydrogen chloride, hydrogen, and chlorosilanes are compressed to obtain trichlorosilane condensate containing some amount of other chlorosilanes, which condensate is then rectified and resulting pure trichlorosilane is also sent to vaporizer. Hydrogen chloride is isolated from remaining mixture in adsorber filled with trichlorosilane. Hydrogen chloride dissolves in the latter, after which liquid phase is introduced into desorber to recover hydrogen chloride into gas phase on heating. Hydrogen chloride is then used in trichlorosilane synthesis and leaving vapor-gas mixture is treated by activated carbon to adsorb hydrogen, which is returned into vaporizer.

EFFECT: improved technical and economical characteristics of process, increased degree of conversion due to uniform optimal temperature conditions, increased yield of trichlorosilane due to chemical recycling, and prolonged service time of equipment.

4 cl, 1 dwg