Preparation and characterization of high performance CHA zeolite membranes from clear solution

CHA zeolite membranes with Si/Al ratio of 2–3 have been successfully synthesized on the outer surface of yttria-stabilized zirconia (YSZ) hollow fibers from clear solution for the first time. The influence of synthesis parameters, such as precursor alkalinity, crystallization time and temperature, on the morphologies and dehydration performance of CHA zeolite membrane, were extensively investigated. Pervaporation (PV) results indicated that the separation performances of obtained CHA membranes were strongly influenced by the morphology of the membranes. The optimal synthesis condition was 140 °C for 16 h in the precursor of 22 SiO₂: 1 Al₂O₃: 15 K₂O: 1 Na₂O: 4400 H₂O. The as-synthesized membranes composed of flake-like grains exhibited a water permeation flux of 13.3 kg m⁻²h⁻¹with separation factor of 6000 for the PV dehydration of 90 wt% ethanol/water mixture at 75 °C. The long-term (>550 h) acid resistance of the as-synthesized CHA zeolite membranes ensures them the most promising candidate for PV dehydration of organic solvents containing acids.