Abstract:
Efficient separation of ethane (C
2H
6) and ethylene (C
2H
4) is crucial for the preparation of polymer-grade C
2H
4, necessitating the development of highly selective and stable C
2H
6/C
2H
4 adsorbent. In this study, highly graphitized porous carbon, denoted as GC-800, was synthesized via room temperature polymerization followed by carbonization at 800 ºC using phenolic resin as the precursor and FeCl
3 as the iron source. VASP calculations confirmed higher binding energy between C
2H
6 molecules and graphitized porous carbon surfaces. The increase in graphitization degree effectively enhanced the adsorption capacity of porous carbon for C
2H
6, but the catalytic graphitization process of Fe at high temperatures could disrupt the microporous structure of porous carbon, thereby reducing the separation ability of C
2H
6/C
2H
4. By controlling the carbonization temperature, the graphitization degree and pore structure of the porous carbon were synergistically optimized. Raman spectra and XPS spectra revealed that GC-800 exhibited high graphitization degree, with a sp
2 C content as high as 73%. Low-temperature N
2 physical adsorption measurements estimated the specific surface area of GC-800 to be as high as 574 m
2·g
−1. At 298 K and 1 bar, GC-800 exhibited an equilibrium adsorption capacity of 2.16 mmol·g
−1 for C
2H
6, with C
2H
6/C
2H
4 (1∶1 and 1∶9,
v/v) IAST selectivity respectively reaching 2.4 and 3.8, significantly higher than those of most reported high-performance C
2H
6 selective adsorbents. Dynamic breakthrough experiments demonstrated that GC-800 could obtain high-purity C
2H
4 in a single step from a mixture of C
2H
6 and C
2H
4. Dynamic cycle tests confirmed the good cyclic stability of GC-800 exhibited good cyclic stability, which could efficiently separate C
2H
6/C
2H
4 even under humid conditions.