Separation of ethane-ethylene and propane-propylene by Ag(I) doped and sulfurized microporous carbon

Separation of light olefins from their respective paraffins by adsorption is an attractive strategy due to the sustainable and inexpensive nature of adsorption process. It is well understood that the presence of Ag(I) in the adsorbent favors the adsorption of ethylene and propylene (olefins) over ethane and propane (paraffins) owing to the 𝜋 -𝜋 complexation between Ag(I) and 𝜋 bond present in olefins. In this research, Ag(I) doped microporous carbons were synthesized from furfuryl alcohol as carbon source. It is also shown that prior sulfurization of the carbon greatly favored Ag(I) content owing to the affinity of sulfur to Ag(I). All the carbons were successfully characterized with pore textural properties, SEM-EDX imaging and x-ray photoelectron spectroscopy (XPS). Only the carbon with highest Ag(I) content (2.5 at.%) and BET specific area (1193 m2/g) favored the adsorption of ethylene and propylene over ethane and propane, respectively. IAST-based selectivity values were also employed to calculate binary adsorption isotherms for ethane-ethylene and propane-propylene mixtures. The IAST-based selectivity values of ethylene/ethane and propylene/propane were in the range of 4.5 to 2.5 and 5 to 2.4, respectively. Finally, column breakthrough and pulse chromatographic peaks were simulated to confirm the separation of paraffin-olefin pairs on thus carbon. To the best of our knowledge, it is the first report of the separation of light paraffin and olefins in a carbon-based adsorbent and by harnessing the 𝜋 -𝜋 complexation.