Synthesis Of SUZ-4 Zeolite Membrane And Its Separation Performance For Dehydration Of Ethyl Acetate

Pervaporation as a new separation technology,has attracted close attention from researchers in the field of environmental protection at home and abroad due to its low energy consumption and environmental friendliness.The choice of membrane materials is the key to pervaporation separation technology.Among them,the zeolite membrane has been widely used in the separation of pervaporation membrane because of its well chemical stability,high flux,and adjustable silicon-aluminum ratio.It has been reported that the coating method during preparation of the zeolite membrane play an extremely important role in pervaporation performance of the zeolite membrane.In this paper,SUZ-4 zeolite membrane with 10μm was synthesized on the surface of porous tubularα-Al₂O₃ support by a new method,dynamic dip coating method.The structure and morphology of the zeolite membrane were characterized by X-ray diffraction（XRD）and scanning electron microscopy（SEM）,respectively.The influences of coating method,dynamic coating conditions,crystallization time,crystallization temperature,rotation speed of the system and other parameters on membrane formation of SUZ-4 zeolite membrane and its pervaporation separation performance of binary and ternary azeotrope systems in crude ethyl acetate were systematically investigated.The main contents and research results are as follows:（1）The dynamic dip coating method adopts dynamic rotation to coat SUZ-4seed slurry on the surface of porous tubularα-Al₂O₃ support.In this part,the effects of two kinds of coating methods,such as ordinary dip coating method and dynamic dip coating method,on the membrane formation of the prepared SUZ-4zeolite membrane and its pervaporation performance are studied.The results indicated that,compared with the normal dip coating method,the SUZ-4 zeolite membrane synthesized by dynamic dip coating method is thinner and more uniform,which showed the better performance in pervaporation dehydration performance for ethyl acetate.（2）In order to select the optimal dynamic dip coating conditions,the effects of different dynamic dip coating conditions on the membrane formation of SUZ-4 zeolite membrane and its pervaporation performance were investigated.It was found that the SUZ-4 zeolite membrane synthesized under the dynamic coating conditions of coating 5 min,20 rpm and three times had the best pervaporation separation effect of ethyl acetate.（3）The effects of crystallization time,crystallization temperature and rotation speed on the membrane formation of SUZ-4 zeolite membrane and its pervaporation performance were investigated under optimal dynamic dip coating conditions.The results show that the separation effect of pervaporation dehydration of SUZ-4 zeolite membrane synthesized at 20 rpm and 150℃for 24h is the best.The flux and separation factor reached 0.42 kg/（m²·h）and 286,respectively,for the ethyl acetate（90 wt%）-water（10 wt%）solution at 50℃.（4）The effects of pervaporation process conditions,which are feed liquid temperature and feed liquid pressure,on the pervaporation separation performance of ethyl acetate-water system and ethanol-water system were investigated.The results show that as the temperature of the feed liquid（30-110℃）and the feed liquid pressure increases,the flux and separation factor shows increasing and decreasing trend respectively.In summary,the most suitable feed liquid temperature for pervaporation performance is 50℃and the feed liquid pressure is 300 Pa.（5）The pervaporation separation effect of SUZ-4 zeolite membrane synthesized under optimized conditions on ethanol-water and ethyl acetate-ethanol-water system was studied.The research indicates that for the ethanol（90wt%）-water（10 wt%）system,the flux and separation factor are 0.31 kg/（m²·h）and 205,respectively.For the ethyl acetate-ethanol-water ternary system,the flux is 0.88 kg/（m²·h）,and the separation factor reaches 272 of SUZ-4 zeolite membrane.