Microporous 3D Graphene-like Zeolite-Templated Carbons for Preferential Adsorption of Ethane

Abstract

Microporous 3D graphene-like carbons were synthesized using the recently developed Ca²⁺ ion-catalyzed synthesis method in Faujasite (FAU)-, EMT-, and beta-zeolite templates. The microporous carbons liberated from these large-pore zeolites (0.7–0.9 nm) retain the structural regularity of zeolite. Currently, FAU-, EMT-, and beta zeolite-templated carbons with respective faithfully constructed pore diameters of 1.2, 1.1, and 0.9 nm and very large surface areas (2,700–3,200 m² g^-1) are available. We have discovered that these schwarzite-like carbons exhibit preferential adsorption of ethane over ethylene at pressures in the range of 1–10 bar. The curved graphene structure, consisting of a diverse range of carbon polygons with a narrow pore size of ~1 nm, provides abundant adsorption sites in micropores and retains its ethane selectivity at pressures up to 10 bar. After varying the oxygen content in the beta zeolite-templated carbon, the ethane and ethylene adsorption isotherms show that the separation ability is not significantly affected by surface oxygen groups. Based on these adsorption results, a simple breakthrough separation procedure using a C₂H₄/C₂H₆ gas mixture (9:1 molar ratio) is demonstrated to produce ethylene with a purity of 99.9%.