Abstract: Trichlorosilane is dismutated to dichlorosilane in the presence, as catalyst, of a tetraalkylurea.

Abstract: Trichlorosilane is dismutated into dichlorosilane in the presence of an .alpha.-pyrrolidone which is N-substituted by a hydrocarbon radical as catalyst.

Abstract: A process for removal of fluoride compounds from spent alkylation catalyst containing fluorosulfonic acid and sulfuric acid wherein hydrogen fluoride and fluorosulfonic acid, in the presence of water, are removed by vacuum distillation following which the remaining sulfuric acid rich fraction of the spent catalyst is reacted with a silica containing material to convert most of the remaining residual hydrogen fluoride to silicon fluoride which is volatilized from the mixture to thereby provide a sulfuric acid effluent free of substantial amounts of fluoride compounds. The hydrogen fluoride recovered is reacted with sulfur trioxide to form fresh fluorosulfonic acid which is combined with sulfuric acid to provide fresh alkylation catalyst.

Abstract: There is disclosed a process for the hydrogen reduction of silicon tetrachloride to produce trichlorosilane. In accordance with the process, hydrogen and silicon tetrachloride vapors are passed through a reaction chamber at relatively high flow rates with approximately 50 mole percent silicon tetrachloride in the mixture. The reaction vessel is held at a temperature of between 900.degree. and 1200.degree. C. This process is a part of an overall system for the production of polycrystalline silicon for the semiconductor industry.