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

Abstract

Molecular sieving of propylene (C3H6) from propane (C3H8) is highly demanded for C3H6 purification. However, delicate control over aperture size to achieve both high C3H6 uptake and C3H6/C3H8 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 (4.2×4.7Å2) compared to CALF-20 (5.2×5.7Å2), which enables molecular sieving of C3H6 (4.16×4.65Å2) from C3H8 (4.20×4.80Å2). Notably, NCU-20 exhibits record-high C3H6 adsorption capacity (94.41 cm3cm-3) at 298K and 1.0bar, outperforming all C3H6/C3H8 molecular sieving adsorbents. The sieving performances of C3H6/C3H8 are well maintained at elevated temperatures. Therefore, a delicate balance between C3H6 adsorption capacity (91.62 cm3cm-3) and C3H6/C3H8 selectivity (uptake ratio of 22.2) is obtained on NCU-20 at 298K and 0.5bar. Furthermore, dynamic breakthrough experiments demonstrate a high productivity of 65.39 cm3cm-3 for high-purity C3H6 (>99.5%) from an equimolar C3H6/C3H8 gas-mixture.