Effects of zeolite membrane structure on the separation of 1,3-propanediolfrom glycerol and glucose by pervaporation

Seven types of zeolite membranes were synthesized on the inside surfaces of alumina and stainless steel supports. The medium-pore membranes (MFI, MEL, and a MFI + MEL composite) were prepared by using organic templates, where as the larger pore membranes (MOR, FAU) were prepared by a template-free me thod. These membranes were used in pervaporation to separate 1,3-propanedio l from glycerol and glucose in an aqueous solution. All membranes had 1,3-p ropanediol/glycerol selectivities higher than 27, and zeolite pore size did not have a large influence on membrane selectivity, which was mainly due t o preferential adsorption of 1,3-propanediol. The 1,3-propanediol/glucose s electivities were higher than 1600 for all membranes because the selectivit ies were mainly controlled by molecular sieving. Zeolite structure had a si gnificant effect on the pervaporation flux; the larger pore membranes had h igher fluxes. At 308 K, the X-type membrane had the largest 1,3-propanediol flux of 62 g/(m(2) h), with a 1,3-propanediol/glycerol selectivity of 59.