Towards ZIF-8 membranes with superb C3H6/C3H8 separation performances under varying conditions: Necessity of precise temperature control

Despite their huge potential in C3H6 refinement, ZIF-8 membranes still struggle to achieve stable production of high-purity C3H6, owing to their fluctuant performances under changing operating conditions. In this study, a previous low-temperature synthetic protocol was further optimized to improve the microstructure of ZIF-8 membranes for pressure-resistent C3H6/C3H8 separation through precisely regulating the reaction temperature between -15 degrees C and 5 degrees C. The elevation of reaction temperature gave rise to reduced grain boundary defects at the cost of increased membrane thickness. Of particular note, carrying out reaction between -2.5 degrees C and 2.5 degrees C assured an exact balance between upward intergrowth and inner penetration and thus, the formation of wellintergrown semi-confined ZIF-8 membrane featuring pressure-resistant C3H6/C3H8 separation even at operating temperature as high as 125 degrees C. At feed pressure of 7 bar, our membrane remained a separation factor approaching 190 with C3H6 permeance up to 2.9x10-8 mol m-2 s-1 Pa-1, thus demonstrating the best separation performance under similar test conditions. Moreover, our membrane could maintain a stable separation capacity at C3H6 feed fraction of 1%-99%, which has never been addressed in previous literature. The above stable and outstanding separation performance recommend our membrane a superb choice for reliable batch production of high-purity C3H6.