Preparation Of NaY Zeolite Membrane And Its Application In Separation Of Benzene/Cyclohexane By Pervaporation

The preparation of NaY zeolite membranes can be as follows. First, crystal seeds were prepared. Second, the supporter was pretreated before use. Third, the synthesis solution was prepared. Last, the NaY zeolite membranes were synthesized.NaY zeolites were synthesized by hydrothermal method. The influence of synthesis conditions such as gel composition and alkalinity were discussed in this thesis. XRD and SEM analysis on zeolite powers showed that the best crystallization solution was Ak₂O₃:SiO₂:Na₂O:H₂O=1:10:14:840, the best crystallization temperature was 100℃and the crystallization time was 24h. The crystal of NaY zeolites were 2μmNaY zeolite membranes in out surface ofα-Al₂O₃ ceramic tube were synthesized by first forming a seeding layer via hot dip-coated method, followed by secondary crystallization method. Then XRD, SEM and N2 permeation were used to characterize the as-synthesized NaY zeolite membranes. The influence of synthesis conditions such as seeding method, gel composition, aging time, synthesis temperature, synthesis time and synthesis stages on the membrane performance were discussed. The optimized condition was as follows:gel composition of Al₂O₃:SiO₂:Na₂O:H₂O=1:10:14:840, ageing time of 12h, synthesis temperature of 100℃, synthesis tme of 6h, synthesis stages of 4. XRD analysis on membrane prepared confirmed formation of a layer of NaY zeolite structure. SEM analysis indicated well intergrown 10～15μm thick NaY zeolite membranes, as well as smoothness. The permeance of N₂ was 4.47×10^-7mol·m^-2·s^-1·Pa^-1 through membranes.NaY zeolite membranes were used to separate the mixture of benzene and cyclohexane by pervaporation. The influence of operation temperature, operation pressure difference, feed flow rate and content of benzene in feed was studied thoroughly. The NaY zeolite membranes showed benzene permselective in pervaporation experiments (benzene-cyclohexane). With mass fraction of benzene 50% in benzene-cyclohexane mixture, separation factor of the membrane was 13.6, permeation flux was 0.173 kg·m²Â·h^-1 at 70℃.