Enhanced propylene/propane separation by carbonaceous membrane derived from poly (aryl ether ketone)/2,6-bis(4-azidobenzylidene)-4-methyl-cyclohexanone interpenetrating network

Abstract An innovative combination of a photosensitive crosslinker, 2,6-bis(4-azidobenzylidene)-4-methyl-cyclohexanone (Azide) with poly (aryl ether ketone) (PAEK) is utilized to form a semi-interpenetrating network (IPN) as the precursor for carbon membranes. Low temperature pyrolysis (450–650 °C) of this precursor produces carbon membranes with excellent olefin/paraffin separation performance that surpasses the conventional trade-off line. The carbon membranes have reasonably good flexibility since excessive closure of the micropores is avoided. This is evident from the mechanical properties of the carbon membranes obtained from nanoindention to the pore size distribution derived from CO 2 adsorption. By varying the composition of Azide/PAEK and optimizing the low-temperature pyrolysis protocol, it was found that PAEK/Azide (80:20) pyrolysed at 550 °C exhibits the best propane/propylene separation performance with C 3 H 6 permeability of 48 barrer and ideal C 3 H 6 /C 3 H 8 selectivity of 44. Due to strong competitive sorption of propane and propylene molecules, the C 3 H 6 permeability is lowered to 3.6 barrer and the C 3 H 6 /C 3 H 8 selectivity to 32 in mixed gas experiments. However, this separation performance is still above the trade-off line. Even though both Azide and PAEK cannot form useful carbon membranes, their IPN is a unique precursor that can produce carbon membranes with comparable performance.