Effects of Zeolite Membrane Structure on the Separation of 1,3-Propanediol from 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, whereas the larger pore membranes (MOR, FAU) were prepared by a template-free method. These membranes were used in pervaporation to separate 1,3-propanediol from glycerol and glucose in an aqueous solution. All membranes had 1,3-propanediol/glycerol selectivities higher than 27, and zeolite pore size did not have a large influence on membrane selectivity, which was mainly due to preferential adsorption of 1,3-propanediol. The 1,3-propanediol/glucose selectivities were higher than 1600 for all membranes because the selectivities were mainly controlled by molecular sieving. Zeolite structure had a significant effect on the pervaporation flux; the larger pore membranes had higher 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.