Methyl ethyl ketone (MEK) was preferentially removed from aqueous solutions by pervaporation through a silicalite-l zeolite membrane at 34 degrees C. Feed concentrations between 0.8 and 15.4 wt% MEK were used, and the azeotrope concentration was surpassed in the permeate above 5% MEK in the feed. The MEK fluxes increased from 0.06 to 0.36 kg/(m(2) h) over this range and the separation factors were between 70 and 146. Separation factors for the silicalite membrane were considerably higher than those for single stage distillation. A silicalite membrane that does not have good N-2/SF6 pure gas permeance ratio (equal to 14) is shown to obtain high separation factors for liquids.