Extraction of propane and ethane from natural gas on ultramicroporous carbon adsorbent with record selectivity

The separation of light hydrocarbon mixtures and the extraction of C3H8 and C2H6 from natural gas are of significant importance in natural gas purification and upgrading. Microporous carbon adsorbents are promising in light hydrocarbon separation. However, the fabrication of uniform ultramicropores to boost separation selectivity remains challenging. Herein, we fabricated a series of poly(vinylidene chloride)-resin-derived ultramicroporous carbon adsorbents with a relatively uniform pore size (5.2–5.3 Å) by activator-free pyrolysis. The optimal C-PVDC-800 exhibited record-high ideal adsorption solution theory (IAST) selectivity for C3H8/CH4 (3387) and C2H6/CH4 (75) and Henry’s selectivity for C3H8/CH4 (369) among all reported adsorbents under ambient conditions, combined with ultrahigh uptake of C3H8 (3.9 mmol g−1, 0.05 bar) and C2H6 (2.67 mmol g−1, 0.10 bar) at low partial pressures and 298 K. More importantly, fast gas adsorption kinetics favorable for fixed-bed adsorption applications was realized. Breakthrough experiments and cycling tests further confirm the superb separation performance of the extraction of C3H8 and C2H6 from natural gas.