A hybrid zeolitic imidazolate framework Co-IM-mIM membrane for gas separation

A zeolitic imidazolate hybrid membrane (Co-IM-mIM) containing two imidazolate ligands deposited on a macroporous α-alumina support was prepared by pre-depositing and secondary growth technique. XRD, TGA and SEM characterizations demonstrate that a stable and thin, but dense and pure-phase Co-IM-mIM membrane can be obtained on the macroporous-alumina discs in Teflon-lined autoclave at 120 °C after pre-depositing by dip-coating at room temperature. No visible cracks, pinholes or other defects were observed on the membrane layer. The gas separation studies of Co-IM-mIM membrane were carried out at 25 °C and 1×105 Pa, showing ideal selectivity of 6.95, 5.25, 3.40 for H2/CO2, H2/N2 and H2/CH4, respectively, and a permeance of 17.37× 10−6 mol/(m2·s·Pa) for H2. The influence of temperature and trans-membrane pressure on hydrogen separation and permeation was also carried out. The gas permeation and selectivity demonstrate that this membrane may have potential applications for efficient H2 separation.