Synthesis Of Type A Zeolite Membrane And Its Separation Performance For Ethyl Acetate-water

In order to separate the water in ethyl acetate raw products with low energy consumption and high efficiency,uniform and compact type A zeolite membrane was synthesized on the surface of macroporous tubular ?-Al₂O₃ carrier by two-seed hot dipping method.The dehydration performances for ethyl acetate-water,ethyl acetate-ethanol-water system were investigated,which contributed to reveal the rugulation effects of the synthesis conditions of type A zeolite membrane on the membrane structure and its effect on the separation performance.Firstly,seed L with a diameter of 2.0 ?m close to the pore size of macroporous ?-Al₂O₃ carrier was synthesized by hydrothermal method to modify the defects of the carrier surface.At the same time,seed S with a diameter of 0.4 ?m was synthesized as the active site for the growth of type A zeolite membranes.The structure and performance of the type A zeolite membrane was controlled by optimizing the process of hot dipping coating method,the composition of synthetic solution,the crystallization time and the crystallization times.High crystallinity and dense type A zeolite membrane with the thickness of 10 ?m was synthsized in the synthetic solution with n?Al₂O₃?:n?SiO₂?:n?Na₂O?:n?SiO2?:n?H2O?= 1:5:50:1000 at the crystallization temperature of 70? for 6h under optimized conditions.The synthetic membranes were used to separate ethyl acetate?97wt%?-water?3wt%?system by pervaporation.The effects of feed rate and operating temperature on the permeation flux and separation factor of water were investigated.When the operating temperature was 110?,the water content in penetrant was 99.68%and the water flux was 1.72 kg/?m²·h?.The separation factor was about 10000.The water content in raffinate could reach 0.02%after circulation,which meets the state standard for superior ethyl acetate product.At this conditions,the water content in the penetrant was 99.23%,and the separation factor was up to 210000.With the increase of the zeolite membrane thickness,the permeation flux decreased and the separation factor improved.The type A zeolite membrane with high crystallinity always showed excellent separation performance for ethyl acetate-water system.Finally,type A zeolite membranes were applied for pervaporation separation of ethanol-water and ethyl acetate-ethanol-water system.Compared with ethyl acetate,ethanol was easier to pass the zeolite membrane due to its smallar kinetic diameter.Synthesized zeolite membrane also showed good separation performance on ethyl acetate-ethanol-water ternary azeotropic system.The water flux was 1.97 kg/?m²·h?,and the separation factor was up to 8500.