Dow Corning Corporation

Regie H Zapp

Roland L Halm

Charles S Kuivila

Brian M Naasz

Oliver K Wilding, Jr

Rick D Streu

The present invention is an improvement of the Direct Process for the manufacture of alkylhalosilanes by the contact of powdered metallurgical grade silicon with an alkyl halide in the presence of a copper catalyst. The improvement reduces lot-to-lot variations in silicon conversion to desired dialkyldihalosilanes. The improvement comprises alloying 0.01 to nine weight percent copper with the silicon to be used in the process and separating slag. In a preferred embodiment of the present process, silicon-copper alloy is pulverized to a powder and mixed with additional copper and other catalysts to form a contact mass reactive with alkylhalides.

Process for manufacture of alkylhalosilanes

The present invention is a process for the production of silanes from the contact of silicon metal or a silicon containing material with hydrogen chloride. The described process employs a metal or metal compound on a solid support as a catalyst which increases the production of tetrachlorosilane. The metal or metal compound is selected from a group consisting of palladium and palladium compounds, rhodium and rhodium compounds, platinum and platinum compounds, iridium and iridium compounds, tin and tin compounds, nickel and nickel compounds, and aluminum and aluminum compounds. The process is run at a temperature of about 250.degree. C. to 500.degree. C.

Supported metal catalyzed production of tetrachlorosilane

The present invention is a process for the production of silanes from the contact of hydrogen chloride with silicon. The silicon may be in the form of silicon metal or a silicon containing material. The described process employs a catalyst which increases the yield of tetrachlorosilane. The catalyst is selected from a group consisting of tin and tin compounds, nickel and nickel compounds, arsenic and arsenic compounds, palladium and palladium compounds, and mixtures thereof. The process is run at a temperature of about 250.degree. C. to 500.degree. C.

Metal catalyzed production of tetrachlorosilane

The present invention provides a method for increasing the yield of methyldichlorosilane obtained from the reaction of silicon metal with methyl chloride without substantially decreasing the combined yield of methyldichlorosilane and dimethyldichlorosilane. This is achieved by blending the methyl chloride with an amount of hydrogen chloride sufficient to accomplish this without forming significant amounts of undesirable SiCl.sub.4 and/or HSiCl.sub.3. In accordance with a preferred embodiment of the present method the concentration of hydrogen chloride is from 0.1 to about 3 weight percent, based on methyl chloride. Most preferably the hydrogen chloride is present only from the first 50% to about 90% of the methyl chloride addition.

Method for preparing organohalosilanes

The present invention provides a method for reducing the concentration of methyltrichlorosilane obtained during the reaction of silicon metal with methyl chloride without substantially decreasing the combined yield of methyldichlorosilane, dimethylchlorosilane and dimethyldichlorosilane. The methyl chloride is blended with from 0.05 up to about 44 mole percent of hydrogen, based on combination of methyl chloride and hydrogen. At hydrogen concentrations above about 12 mole percent there is a substantial increase in the methyldichlorosilane content of the reaction product while the concentration of methyltrichlorosilane in the reaction product is maintained below about 4 percent by weight.

The present invention provides a method for reducing the concentration of methyltrichlorosilane in the mixture of methylchlorosilanes obtained from the direct process reaction of silicon metal with a mixture of methyl chloride and hydrogen chloride. The method comprises blending the methyl chloride/hydrogen chloride mixture with from 0.1 up to about 5 weight percent of hydrogen, based on the methyl chloride.

What is disclosed is a method of controlling a process for the preparation of alkylhalosilanes from silicon and alkylhalides where phosphorous or certain phosphorous compounds are used as promoters to enhance selectivity, overall yields of useable silanes and enhanced silicon metal conversion.

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Carrollton, KY, United States of America

Regie H Zapp