OJSC “Giredmet”, Moscow, Russia:

A. A. Arkadyev, Leading Researcher, e-mail: aaa560804@yandex.ru
Yu. N. Nazarov, Head of Laboratory
A. A. Kokh, Leading Researcher
A. M. Chapygin, Leading Researcher
A. V. Novikov, Researcher

This article presents the description and results of investigations in the field of technology of trichlorsilane production. Trichlorsilane is the raw material for polycrystalline silicon production. The conducted investigations of influence of pressure effect on the ratio of trichlorosilane and silicon tetrachloride in the synthesized steam-gas mixture are directed on a problem solution of increasing of reactors' individual productivity of trichlorsilane direct synthesis in pseudofluidized layer. While carrying out the synthesis of trichlorosilane in a pseudo-fluidized layer reactor, there is provided a specified narrow temperature range. This range is supported in the reaction zone through the effective heat removal from the reactor surface by water steam condensate. The heat removal is held in the laboratory plant by silicon hydrochlorination in reactor of pseudo-fluidized layer. Its cooling system is improved and pre-race heating of silicon by hot nitrogen is applied. The amount of moisture is minimized for the purpose of using reagents with the stringent requirements for moisture content. The moisture is introduced into the reactor along with the reagents. It is established that with increasing of pressure in the range of 0,18–0,40 MPa, there is a sharp increase of trichlorosilane content in the synthesized steam-gas mixture, explained by improving of a pseudo-fluidized layer structure. This layer contains: creation of a more suitable "boiling" layer of silicon, reducing of probability of stagnant zones generation and, consequently, reducing the possibility of generation of local overheating in the reaction space of the reactor. The occurrence of the reactor favores the passage of an adverse reaction with the formation of silicon tetrachloride. In the range of 0,40–1,97 MPa, the trichlorosilane content in the steam-gas mixture increased slightly, indicating that structure of pseudo-fluidized layer already has not undergone significant changes in this pressure range. In this investigation, there is defined the optimum pressure which allows to raise the content of trichlorsilane in steamgas mixture and to increase its individual productivity. The most reasonable way is to carry out the synthesis of trichlorosilane at a pressure equal to 0.4 MPa. The steam-gas mixture is synthesized at hydrochlorination of crystalline silicon in reactor of pseudo-fluidized layer.

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