A Na-ZSM-5 zeolite membrane was effective for separating 1,3-propanediol from glycerol and glucose in water by pervaporation. Binary, ternary, and quaternary mixtures were studied as a function of temperature. At 308 K, the total flux for the quaternary feed was 0.21 kg/m(2) h. The 1,3-propanediol/glycerol selectivity decreased from 54 to 21 over the temperature range 308-328 K, whereas for the same range 1,3-propanediol/glucose selectivity increased from 330 to 2100. The 1,3-propanediol/glycerol selectivity was controlled by both preferential adsorption and differences in diffusion rates. The 1,3-propanediol/glucose selectivity was mainly controlled by differences in diffusion rates, with the larger glucose diffusing through non-zeolite pores. Glycerol inhibited glucose permeation and thus increased the 1,3-propanediol/glucose selectivity. The presence of glucose decreased the total flux but increased the 1,3-propanediol/glycerol selectivity.