Patent ID: 9089788
Filing Date: 2015-07-28
Classification: B01D,C01B

Abstract:
1. A process for purifying chlorosilanes by distillation, which comprises providing a boron-containing mixture of chlorosilanes containing trichlorosilane (TCS), dichlorosilane (DCS) and silicon tetrachloride (STC) and purifying the mixture of chlorosilanes by distillation in a plurality of distillation columns, wherein the mixture of chlorosilanes is fed to a separation column in which column parameters are selected so that less than 10 ppm of STC are present in a first fraction from the separation column and less than 10 ppm of TCS are present in a second fraction from the separation column, wherein the first fraction from the separation column is fed to a third column and separated by distillation into a bottom stream containing TCS and a boron-enriched overhead stream containing TCS together with low boilers such as DCS, wherein the second fraction from the separation column is fed to a second column and separated by distillation into an overhead stream containing STC and a boron-enriched bottom stream containing high boilers, in order to branch off low-boiling boron compounds from the distillation columns via overhead streams containing boron-enriched DCS and high-boiling boron compounds via a boron-enriched bottom stream containing high boilers.