Jeasung Park

Separation of CO2 from flue gases using hydroquinone clathrate compounds

Hydroquinone (HQ) samples reacting with (CO2+N2) gas mixtures with various compositions at pressures ranging from 10 to 50 bar are analyzed using spectroscopic methods and an elemental analyzer. The results indicate that while both CO2 and N2 can react with HQ to form clathrate compounds, CO2 has higher selectivity than N2. In particular, at an operating pressure of 20 bar or greater, the CO2 content in the clathrate compound is 85mol% or higher regardless of the feed gas composition. Moreover, if a two-step clathrate-based process is adapted, CO2 at a rate of 93 mol% or higher can be recovered from flue gases. Thus, the clathrate compound described here can be used as a CO2 separation/recovery medium for CO2 in flue gases.

13C NMR analysis of C2H6+C2H4+THF mixed hydrate for an application to separation of C2H4 and C2H6

Mixed hydrates (C2H4+5.56mol% THF, and C2H4+C2H6+5.56mol% THF) were analyzed using 13C MAS NMR spectroscopy. The hydrates were formed using a variety of feed gas compositions (100% C2H4; 20% C2H4+80% C2H6; 40% C2H4+60% C2H6; 60% C2H4+40% C2H6; and 80% C2H4+20% C2H6). According to the peak identification results, C2H4 molecules can occupy both the small and large cavities in the sI and sII hydrate structures, while C2H6 molecules can occupy only the large cavities of sI. Moreover, the mole fraction of C2H4 in the hydrate matrix was found to increase with increasing feed ratio of C2H4. On the basis of the NMR analysis, a hydrate-based process for separating C2H4 and C2H6 by repeated hydrate formation and dissociation was proposed. For cases with a feed-gas mixture with 20% C2H4 and 80% C2H6, a recovery of more than 88% C2H4 in the gas mixture could be achieved after five cycles of hydrate-based separation.