Dow Corning Corporation

David Harold Bramer

Larry Herbert Wood

Steven K Freeburne

Andrew L Ault

A process for continuously reducing the amount of cyclic organosiloxane in a recirculating process stream. The process comprises washing a process stream in a wash step to reduce chloride content of the process stream, distilling the process stream into a low-boiling fraction comprising low molecular weight cyclic organosiloxanes and an inert solvent and a high-boiling fraction comprising linear organosiloxanes and high molecular weight cyclic organosiloxanes, and reequilibrating the overhead low-boiling fraction in the presence of a reequilibration catalyst to form a reequilibration mixture comprising high molecular weight cyclic organosiloxanes and the inert solvent, and recycling the reequilibration mixture to the wash step.

Reducing low molecular weight cyclic organosiloxanes in a recirculating process stream

A process for treating a by-product stream, resulting from the commercial manufacture of methylchlorosilanes, to remove residual silanes where the residual silanes comprise low-boiling hydrosilanes. The process comprises a first step where the by-product stream is contacted with hydrogen chloride in the presence of a chlorination catalyst to convert the low-boiling hydrosilanes to chlorosilanes. In a second step, the modified by-product stream comprising the chlorosilanes is contacted with activated carbon which adsorbs higher-boiling silanes including chlorosilanes, thereby forming a final by-product stream reduced in lower-boiling hydrosilanes and in total silanes. The present process is especially useful for removing silanes from by-product streams intended for incineration, thus reducing silica during combustion of the by-product stream in the incinerator.

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Hanover, IN, United States of America

David Harold Bramer