Studies on Hydrochlorination of Silicon in a Fixed Bed Reactor

Abstract

The work presented here pertains to the study of hydrochlorination of silicon in a fixed bed reactor to produce primarily trichlorosilane. Most of the data on this reaction system is patented. Reaction takes place between hydrogen chloride gas and dry silicon powder in a fixed bed condition. The optimum temperature for this reaction was determined by changing the reaction temperature and collecting the condensed product of this reaction, i.e. trichlorosilane, and was found to be 321°C at atmospheric pressure. Using the reaction kinetics theory, fixed bed reaction rate constants were determined for 124, 141, 160, 208 and 438 µm average silicon particle sizes at 321°C and atmospheric pressure. It was observed that the fixed bed reaction rate constant values were of the same order and around 0.7 s−1. The conversion of HCl increases with a decrease in particle size of silicon and lowering of the superficial velocity of HCl gas.