Reactive Distillation-Aided Ultrapure Silane Production from Trichlorosilane: Process Simulation and Optimization

Reactive distillation (RD) was applied for manufacturing silane from trichlorosilane (TCS). The previous studies resorted to a single RD column to attain a silane purity of 99% and to intermediate condensers to alleviate the cryogenic refrigeration load of the overhead condenser. In this paper, we present an extended scheme with the RD column assisted by two purification columns, which adopted a lowered silane purity at the RD column and achieved an ultra high purity of 99.9999% at the final column. Comparative simulation was conducted for three configurations of the RD column with one, two, and no intermediate condensers at different operating conditions for an optimal economy of operation. The cost dependency on the configuration was elucidated by the fluid flow rates and reaction efficiency in the RD column. The results showed that pursuing a silane purity over 99% at RD overhead was unadvisible due to the enormous cost for cryogenic refrigeration. Inserting two intermediate condensers was also unnecessary because it would interfere the reaction and eventually increase the overall operation cost. The optimal configuration was to insert a single intermediate condenser in between the reaction and rectifying sections, with an overhead silane content in the order of 82% at an overhead condensing temperature of about -40 degrees C and an intermediate condensing temperature in the range of 7-10 degrees C.