Preparation of highly graphitized porous carbon and its ethane/ethylene separation performance
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Abstract
Efficient separation of ethane (C2H6) and ethylene (C2H4) is crucial for the preparation of polymer-grade C2H4, necessitating the development of highly selective and stable C2H6/C2H4 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 FeCl3 as the iron source. VASP calculations confirmed higher binding energy between C2H6 molecules and graphitized porous carbon surfaces. The increase in graphitization degree effectively enhanced the adsorption capacity of porous carbon for C2H6, but the catalytic graphitization process of Fe at high temperatures could disrupt the microporous structure of porous carbon, thereby reducing the separation ability of C2H6/C2H4. 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 sp2 C content as high as 73%. Low-temperature N2 physical adsorption measurements estimated the specific surface area of GC-800 to be as high as 574 m2·g−1. At 298 K and 1 bar, GC-800 exhibited an equilibrium adsorption capacity of 2.16 mmol·g−1 for C2H6, with C2H6/C2H4 (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 C2H6 selective adsorbents. Dynamic breakthrough experiments demonstrated that GC-800 could obtain high-purity C2H4 in a single step from a mixture of C2H6 and C2H4. Dynamic cycle tests confirmed the good cyclic stability of GC-800 exhibited good cyclic stability, which could efficiently separate C2H6/C2H4 even under humid conditions.
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