Pervaporation of water/THF mixtures using zeolite membranes

Four types of hydrophilic zeolite membranes (A-type, Al-ZSM-5, mordenite, a nd Y-type) were used to dehydrate water/THF mixtures by pervaporation. At 3 03 K, the total fluxes increased with zeolite pore size, and membranes with lower Si/Al ratios had higher water/THF separation selectivities. The Y-ty pe membrane, which was prepared using a template-free seeding technique, ha d the highest flux and selectivity; at 333 K, the total flux was 2.4 kg m(- 2) h(-1) with a water/ THY selectivity of 290. The total flux increased wit h water feed concentration, but the selectivity decreased. Separation was b ased on both preferential adsorption of water and differences in diffusion rates. During continuous operation, the water permeate concentrations were higher than 95 wt %. Hydrophobic silicalite-1 and Ge-ZSM-5 membranes were u sed to remove THF from water. The Ge-ZSM-5 membrane had a total flux of 0.3 kg m(-2) h(-1) and a THF/water separation selectivity of 890 at 333 K for a 5 wt % THF aqueous solution.