Alan Ritzer

Catalysis of the Rochow Direct Process

Abstract The synthesis of dimethyldichlorosilane by the “Direct Process” is at the heart of the silicone industry. The Direct Process has been the object of intensive research and development over the past 40 years, yet there are aspects of the reaction that remain in an elementary state of understanding. The goal of this work was the discovery of previously unknown variables, including trace elements, which affect product distribution and rate. Fluidized and stirred bed reactors were used. Trace quantities of tin were found to affect the Direct Process profoundly, and the effects of tin and zinc were synergistic. A catalyst system consisting of copper, zinc, and tin was discovered which yielded 90% dimethyldichlorosilane with nearly complete silicon utilization. This is a major improvement over the best previously reported performance.