Dehydration performance of a hydrophobic DD3R zeolite membrane

The all silica DDR membrane turns out to be well suited to separate water from organic solvents under pervaporation conditions, despite its hydrophobic character. All-silica zeolites are chemically and hydrothermally more stable than aluminum containing ones and are therefore preferred for membrane applications, including for dehydration, even though these type of membranes are hydrophobic. Permeation of water, ethanol and methanol through an all-silica DDR membrane has been measured at temperatures ranging from 344 to 398 K. The hydrophobic membrane shows high water fluxes (up to 20 kg m(-2) h(-1)). The pure water permeance is insensitive to temperature and is well described assuming weak adsorption. Excellent performance in dewatering ethanol (N = 2 kg m(-2) h(-1) and alpha(w) = 1500 at 373 K and x(w) 0.18) is observed and the membrane is also able to selectively remove water from methanol (N = 5 kg m(-2) h(-1) and alpha(w) = 9). Water could also be removed from methanol/ethanol/water (alpha(water/EtOH) = 1500, alpha(MeOH/EtOH) = 70 at 373 K) mixtures, even at water feed concentrations below 1.5 mol%. (C) 2008 Elsevier B.V. All rights reserved.