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

Abstract

Microporous 3D graphene-like carbons were synthesized in Faujasite (FAU)-, EMT-, and beta-zeolite templates using the recently developed Ca2+ ion-catalyzed synthesis method. The microporous carbons liberated from these large-pore zeolites (0.7-0.9 nm) retain the structural regularity of zeolite. FAU-, EMT-, and beta zeolite-templated carbons (ZTCs) with faithfully constructed pore diameters of 1.2, 1.1, and 0.9 nm, respectively, and very large Brunauer-Emmet-Teller areas (2700-3200 m2 g-1) were obtained. 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 ZTC, 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 breakthrough separation procedure using a C2H4/C2H6 gas mixture (9:1 molar ratio) is demonstrated to produce ethylene with a purity of 99.9%.