Preparation And Pervaporation Application Of High Performance NaA Zeolite Membrane

Pervaporation has received widely attention as a new type membrane separation in recent years, because it is an effective and energy-efficient technology compared with conventional separation process.NaA zeolite membranes have become ideal materials on dehydration of organic by pervaporation due to its high hydrophilicity and small pore size which range between most organic solvents and water molecules.NaA zeolite membrane has good ethanol/water separation performance, which is expected to be utilized in a hybrid distillation/pervaporation system for bio-ethanol dehydration.In this thesis, the characterization methods of SEM,XRD and pervaporation were utilized to seek preparation methods of high performance NaA zeolite membrane on macro-porous support. First of all, high performance NaA zeolite membranes with the length of 25 cm were prepared by second repair method and two-step seeding method. NaA zeolite membranes were enlarged preparation on the basis of the previous two methods, which had good pervaporation performance and met the requirements of industrial application. The main conclusions obtained in this thesis were as follows:(1)NaA zeolite membrane with the defects was repaired well by another high concentration formulation 1Al2O3:2SiO2:2Na2O:120H2O,which was dynamic hydrothermally synthesized one time with the formulation 1Al2O3:5SiO2= 50Na2O: 1000H2O.Pervaporation (PV) experiments were carried out at 70℃and 200～300 Pa using a 90 wt.% water/ethanol mixture with a laboratory scale apparatus to test the performance of as-synthesized membranes. They showed the high performance with the water flux up to 1.9210 kg·m-2·h-1 and the separation factor more than 5000.(2) High performance NaA zeolite membrane was prepared by two-step seeding method, which was dynamic hydrotherrmally synthesized just one time with the formulation 1Al2O3:5SiO2:50Na2O:1000H2O.Pervaporation (PV) experiments were carried out at 70℃and 200～300 Pa using a 90 wt.% water/ethanol mixture with a laboratory scale apparatus to test the performance of as-synthesized membranes.They showed the high performance with the water flux up to 1.8510 kg·m-2·h-1 and the separation factor more than 10000.(3)NaA zeolite membranes with the length of 80 cm were successfully prepared on the macro-porousα-Al2O3 support. Pervaporation (PV) experiments were carried out using a 90 wt. % water/ethanol mixture with a pilot scale apparatus to test the performance of as-synthesized membranes, maintain the feed flow rate was 200 L·h-1,when the feed temperature was increased to 120℃,the permeation flux could reach 8.6781 kg·m-2·h-1 and the separation factor>1000, which had met the requirements of industrial application.