AlPO-18 membranes for CO2/CH4 and N2/CH4 separations

Microporous aluminophosphates are promising materials for gas separation, but their industrial applications are still challenging due to the permeability-selectivity “trade-off” behavior. A new approach is now reported by the addition of single novel template N, N-diisopropylethylamine (DIPEA) into the gel precursor to prepare the pure AlPO-18 membrane with both high permeance and selectivity. It was identified that the AlPO-18 membrane possessed small plate-like crystals on support surface. The single and mixed CO2/CH4 and N2/CH4 gas separations were measured. The best membrane exhibited high CO2 and N2 permeances of 9.2, 0.91 × 10−7 mol m−2 s−1∙Pa−1 under the two-component gas mixture, and the mixture selectivities in CO2/CH4 and N2/CH4 were 93 and 6.0 at 303 K and 0.2 MPa, respectively. This strategy not only demonstrated a potential zeolite membrane material for gas separation but also furnished ideas for the preparation of high permeable thin films.