Synthesis of dimethyldichlorosilane by fluidized bed membrane reactor

A fluidized bed reactor was coupled with a ceramic membrane to construct a integrated fluidized bed membrane reactor for synthesis of dimethyldichlorosilane. The effects of catalyst concentration, back flush on reaction and membrane separation performance were studied. The ceramic membrane and the contact mass before and after reaction were characterized. Selectivity of dimethyldichlorosilane could be maintained above 85% and conversion ratio of silicon increased with increasing catalyst concentration, when catalyst concentration was less than 4%(mass). When catalyst concentration was in the range of 4%-8%, selectivity of dimethyldichlorosilane decreased slightly, but decreased obviously when catalyst concentration was above 8%. The particle size of the contact mass decreased after reaction. The carbon that deposited on the surface of silicon increased with increasing catalyst concentration. Two layers of filter cake formed on the membrane surface during the reaction process. The inner cake was copper, and the outer one was carbon. Under different catalyst concentrations, rejection of dust by the ceramic membrane could reach 100%. The change of trans-membrane pressure was little in the reaction process and back flush could increase silicon conversion.