A green synthesis of MOR zeolite membranes by wet gel conversion for dehydration of water-acetic acid mixtures

High performance mordenite (MOR) membranes were successfully synthesized by wet gel conversion (WGC) route using organic template-free and fluoride-free gels on seeded macroporous Al2O3 tubes. The seeded Al2O3 tubes were dipped into the gel solution with a composition of SiO2: 0.0045Al2O3: 0.19 Na2O: 27.76 H2O and then directly crystallized at 150 °C for 8 h without any extra solvent or solution in autoclave. The concentration of MOR seeds, crystallization time, composition of gels and crystallization way (hydrothermal growth or WGC) significantly influenced the membrane performance for dehydration of acetic acid (AA) mixtures by pervaporation. The prepared MOR membranes displayed a high water flux and good selectivity in long-term dehydration of 90 wt.% AA/H2O at 75 °C with the steay-state flux of 0.70 kg m−2 h−1 and separation factor increasing to 5000 after 200 h test. The WGC approach reduced the consumption of gel by about 96% with almost “zero” waste liquid. This WGC method is demonstrated as an efficient, green route to synthesze zeolite membranes and to possess potentiality for industrial dehydration applications.