A Ge-substituted ZSM-5 zeolite membrane for the separation of acetic acid from water

A Ge-substituted ZSM-5 membrane prepared on a porous, tubular, stainless steel support was effective for the separation of acetic acid from water by pervaporation. The Ge-ZSM-5 membrane had higher acetic acid fluxes and lower pure water fluxes than a silicalite-1 membrane because it is more hydrophobic than silicalite-1. The Ge-ZSM-5 membrane was selective because of the preferential adsorption of acetic acid, and both the flux and selectivity increased with temperature. The total flux decreased slightly as the acetic acid feed concentration increased from 0.33 to 5 wt %, and the separation selectivity decreased to one-half its initial value. For a 5 wt % acetic acid feed, the Ge-ZSM-5 membrane had a total flux of 0.43 kg/(m(2.)h) at 363 K with an acetic acid/water separation selectivity of 14.