Optimization of synthesis conditions for preparation of ceramic (A-type zeolite) membranes in dehydration of ethylene glycol

High quality ceramic (A-type zeolite) membranes were synthesized on α-Al2O3 as substrate with the aid of sub-micro zeolite powder as seeds. The zeolite membranes and seeds were synthesized via hydrothermal process. The influences of synthesis conditions including synthesis time and synthesis temperature on structure and permeation properties of the A-type zeolite membranes were investigated. The synthesized membranes were characterized using X-ray diffraction (XRD) and scanning electron microscope (SEM). Sub-micro seeds of A-type zeolite with high crystallinity and crystallite size ranging from 150 to 350 nm were synthesized successfully. The best A-type zeolite membranes with the aid of sub-micro seeds were obtained for synthesis time of 2 h and at synthesis temperature of 100 °C, exhibiting permeation flux of 4.03 kg m−2 h−1 and separation factor of more than 10,000 for dehydration of the 10:90 (wt%) water/ethylene glycol (EG) mixture at 70 °C. Moreover, the separation performance of membranes for dehydration of 10:90 (wt%) water/ethanol at 70 °C showed total flux and separation factor of 11.14 kg m−2 h−1 and 10,000, respectively. It was observed that synthesis of high quality A-type zeolite membranes need optimization of time and temperature during synthesis of zeolite layers.