Synthesis of Cu(I) doped mesoporous carbon for selective capture of ethylene from reaction products of oxidative coupling of methane (OCM)

Abstract

There is a growing industrial interest in the recovery of ethylene from the gaseous products obtained in oxidative coupling of methane (OCM). The key challenge of employing OCM is the separation of ethylene from the product mixture that usually consists of ethylene, ethane, methane, carbon dioxide, carbon monoxide and hydrogen. In this work, we have synthesized Cu(I) doped mesoporous carbons as ethylene selective adsorbents to separate ethylene from the product mixture of OCM. The pristine mesoporous carbon was synthesized from resorcinol as carbon precursor and F127 as surfactant template. Cu(I) doping on mesoporous carbon was performed by CuCl as the precursor of Cu(I) with total Cu content of 0.3–3.3at.% in the resultant carbon. The structural identity of carbons was confirmed by pore textural properties, scanning electron microscopy (SEM), Energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). It was revealed that the selectivity towards ethylene is a function of Cu content of the mesoporous carbon indicating a possible π-complexation between ethylene and Cu(I). Pure component adsorption isotherms confirmed that ethylene adsorption is the highest followed by carbon dioxide, ethane, methane, carbon monoxide and hydrogen. IAST-based selectivity values for C2H4/C2H6, C2H4/CH4, C2H4/CO2, C2H4/CO and C2H4/H2 were calculated as 8-4, 80-48, 22-4, 251-36, 7644-18120767, respectively. The isosteric heat of adsorption of ethylene was in the range of 54-26 kJ/mol and it was higher than that of the other gases. The adsorbent also demonstrated good cyclability of ethylene adsorption. Finally, the simulated dynamic breakthrough results for fixed bed adsorption column demonstrated a large interval between the breakthrough times of ethylene and other gases, confirming its separation. The overall results confirm that Cu(I)-doped mesoporous carbons have a high potential for ethylene separation from OCM gas mixtures.