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 (CH) from propane (CH) is highly demanded for CH purification. However, delicate control over aperture size to achieve both high CH uptake and CH/CH 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) compared to CALF-20 (5.2 × 5.7 Å), which enables molecular sieving of CH (4.16 × 4.65 Å) from CH (4.20 × 4.80 Å). Notably, NCU-20 exhibits record-high CH adsorption capacity (94.41 cm cm) at 298 K and 1.0 bar, outperforming all CH/CH molecular sieving adsorbents. The sieving performances of CH/CH are well maintained at elevated temperatures. Therefore, a delicate balance between CH adsorption capacity (91.62 cm cm) and CH/CH 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 cm for high-purity CH (>99.5%) from an equimolar CH/CH gas-mixture.