Retrofitting of extractive distillation columns with high flux, low separation factor membranes: A way to reduce the energy demand?

tIn the context of the production of n-butyl acetate, acetic acid or ethyl acetate from methylacetate, a pervaporation module was employed in order to retrofit the extractive distilla-tion unit used to recover methyl acetate from a methanol/methyl acetate industrial wastestream. The PolyAl TypM1®membrane (from PolyAnTM) was first tested using a wide feedconcentration range (11–90 mol% methanol) and three temperatures (30, 36, 44◦C). Then,it was compared with other commercial membranes reported in literature (at 40–45◦C) atthe methanol/methyl acetate azeotropic composition, resulting in a medium/low separationfactor and with the highest flux. This ensured the simulation of a very challenging conditionfor the retrofitting from an energetic point of view (i.e., for moderate or low separation factormembranes: the higher the flux, the higher the process energy requirement).The retrofitting permits to avoid the use of a solvent during azeotropic separation. More-over, during comparison of the retrofitted hybrid pervaporation-distillation unit with thesource industrial extractive distillation unit, an overall energy saving up to ∼38% wasdemonstrated (∼23% when only the energy consumed by the heaters is taken into account).In addition, major hydraulic modifications could be avoided employing structured packingand membranes of higher separation factors