Green and Scalable Preparation of an Isomeric CALF-20 Adsorbent with Tailored Pore Size for Molecular Sieving of Propylene from Propane.

Molecular sieving of propylene (C 3 H 6 ) from propane (C 3 H 8 ) is highly demanded for C 3 H 6 purification. However, delicate control over aperture size to achieve both high C 3 H 6 uptake and C 3 H 6 /C 3 H 8 selectivity with low cost remains a significant challenge. Herein, a green and scalable approach is reported for preparing an isomeric CALF-20 adsorbent, termed as NCU-20, using water as the only solvent with a cost of $10 per kilogram. NCU-20 features a contracted pore size (4.2 × 4.7 Å 2 ) compared to CALF-20 (5.2 × 5.7 Å 2 ), which enables molecular sieving of C 3 H 6 (4.16 × 4.65 Å 2 ) from C 3 H 8 (4.20 × 4.80 Å 2 ). Notably, NCU-20 exhibits record-high C 3 H 6 adsorption capacity (94.41 cm 3  cm -3 ) at 298 K and 1.0 bar, outperforming all C 3 H 6 /C 3 H 8 molecular sieving adsorbents. The sieving performances of C 3 H 6 /C 3 H 8 are well maintained at elevated temperatures. Therefore, a delicate balance between C 3 H 6 adsorption capacity (91.62 cm 3  cm -3 ) and C 3 H 6 /C 3 H 8 selectivity (uptake ratio of 22.2) is obtained on NCU-20 at 298 K and 0.5 bar. Furthermore, dynamic breakthrough experiments demonstrate a high productivity of 65.39 cm 3  cm -3 for high-purity C 3 H 6 (>99.5%) from an equimolar C 3 H 6 /C 3 H 8 gas-mixture.