Distillation with nanoporous or coated hollow fibers

Distillation of methanol–ethanol solutions in a small column containing hollow fibers is independent of whether the fibers are nanoporous or covered with a thin, highly permeable coating. The hollow fibers do not provide selectivity but serve as a form of structured packing, so that the fluid mechanics in the column is not constrained by loading and flooding. The overall mass transfer coefficient based on a vapor side driving force and measured across the fibers is around 0.03 cm/s, the result of roughly equal mass transfer resistances in the condensate, the membrane, and the vapor. Further improvements in this form of distillation will require significant changes in module design, which reduce each of these three resistances.