Carbon molecular sieving membranes for butane isomer separation

Abstract Membrane‐based separations of hydrocarbon isomers are major challenges for the petrochemical industry. Herein, high quality carbon molecular sieving membranes (CMSMs) were prepared on γ‐alumina substrates from pyrolysis of P84 polymer membranes. Targeting at butane isomer separations, we tailored the slit‐like ultramicropores of CMSMs at angstrom level by rational manipulations of the pyrolysis temperature. The crack‐free CMSMs were obtained at 600°C with the narrow and uniform ultramicropores centered at 6.0 å. A clear molecular size/shape discrimination was achieved successfully and remarkable n ‐butane permeance (384 GPU) and n ‐butane/ iso ‐butane separation factor (74) was observed, which transcends the upper limit of well‐intergrown crystalline zeolite membranes. Fine‐tuning of the membrane thickness at sub‐micron level, the n ‐butane permeance and n ‐butane/ iso ‐butane separation factor were further optimized, which shows a great potential for petrochemical separation.