Exploiting thermodynamic-kinetic synergetic effect for C3H6/C3H8
separation in pillar-layer MOFs
Abstract
Efficient adsorption separation of propylene (C3H6) and propane (C3H8)
can largely lower the energy consumption compared to the current
energy-intensive cryogenic distillation. Herein, we report an
isoreticular family of pillar-layer metal-organic frameworks (MOFs),
M(AIP)(BPY)0.5 (M = Co, Ni, and Zn), for efficient C3H6/C3H8 separation
by exploiting thermodynamic and kinetic effects, circumventing
disadvantages of each separation mechanism. The three MOFs feature an
open metal site for each metal node and uniform but narrow
one-dimensional (1D) channels, offering strong binding sites toward C3H6
via π-complexations while obstructing the diffusion of bulkier C3H8. The
Ni-MOF shows the best separation performance based on the highest
thermodynamic and kinetic C3H6/C3H8 selectivity, further verified by
computational simulations. Ni(AIP)(BPY)0.5 has a moderate C3H6 uptake of
1.94 mmol/g but a remarkably high C3H6/C3H8 uptake ratio of 4.26 at 298
K and 1 bar. Efficient C3H6/C3H8 separation, good recyclability,
moisture and water stability of Ni(AIP)(BPY)0.5 are confirmed.