Synthesis and characterization of ZIF-69 membranes and separation for CO2/CO mixture

Continuous and c-oriented ZIF-69 membranes were successfully synthesized on porous α-alumina substrates by an in situ solvothermal method. The membranes were characterized by XRD, SEM and single-gas permeation tests. The BET measurements on crystals taken from the same mother liquor that was used for membrane synthesis yield a Langmuir surface area of 1138 m2/g. The stability of the membrane towards heat and different solvents were studied. Single-gas permeation experiments through ZIF-69 membranes were carried out by a vacuum method at room temperature using H2, CH4, CO, CO2 and SF6, respectively. The permeances were in the order of H2 > CO2 > CH4 > CO > SF6. The separation of CO2/CO gas mixture was investigated by gas chromatograph (GC) and the permselectivity of CO2/CO was 3.5 ± 0.1 with CO2 permeance of 3.6 ± 0.3 × 10−8 mol m−2 s−1 Pa−1 at room temperature.