Large-area, high-permeance and acid-resistant zeolite SSZ-13 membranes for efficient pervaporative separation of water/acetic acid mixtures

The development of acid-stable zeolite membrane is still a great challenge for pervaporative dehydration of water/acetic acid mixtures. Herein, we reported the fabrication of high-quality zeolite SSZ-13 membranes on the 50-cm-long tubular alumina supports via vacuum seeding method. The uniform seed layer by vacuum seeding method resulted in a uniform and intergrown zeolite membrane with thickness of 8.0–9.0 μm. The typical membrane with membrane area of 180 cm² and Si/Al ratio of 12 displayed extremely high water permeance of 2.4 × 10⁻⁶ mol m⁻² s⁻¹ Pa⁻¹ and high selectivity of 7700 in a 40/60 wt% water/AcOH mixture at 363 K. The corresponding water flux and separation index were 7.0 kg m⁻² h⁻¹ and 1.95 mol m⁻² s⁻¹, respectively. The overall separation performance (for example separation index) of the large-area SSZ-13 membrane was the highest one among the reported membranes for water/acetic acid separation. The effects of feed concentration and temperature on membrane performances were investigated for the separation of H₂O/AcOH mixtures. Water flux increased greatly but water permeance decreased a little with increasing water content in the mixture and temperature. Permeance is a driving force normalized form and reflects the inherent property of the membrane only. Stability of the membrane in aqueous AcOH solutions was also studied in the 10-d continuous test.