Carbon Dioxide (CO2) Solubility in New Synthesized Ionic Liquid, 1,10-bis (trioctylphosphonium-1-yl) decane dioctylsulfosuccinate

Due to the potential of ionic liquids (ILs) for industrial application in carbon dioxide
(CO2) capture and gas separation processes, solubility of near or supercritical CO2 in
ionic liquids has beenan extensive research during the lastfew years. This work studies
the solubility of CO2 in phosphonium-based ionic liquids that, unlike imidazolium-based
ILs, have received little attention in spite oftheir interesting characteristics.
This work addresses the study of solubility of CO2 in phosphonium-based ionic liquid,
at temperature (298.15, 303.15 and 308.15) K and pressure ranging from 15-25 bars.
Phosphonium-based ionic liquids have attractive characteristics such as negligible vapor
pressures, high thermal stability, large liquidus range and nonflammability, high
solvation capacity, compatibility with strong alkaline solutes, stabilizing effect on
palladium catalysts, effective media for Heck and Suzuki reactions and their low cost.
[4]
Removal of CO2 in natural gas and other gas sources commonly used chemical solvents
comprise amine solutions. Commercial amine solutions useable for this purpose include
monoethanolamine (MEA), N-methyldiethanolamine (MDEA), and diethanolamine
(DEA). Although an effective CO2 separation process, amine treating presents several
issues and challenges. The present invention provides new data ofthe alternative solvent
for CO2 removal process which is phosphonium-based ionic liquid.
The solubility measurement is using experimental approach. The experimental setup is
established and leakage test is run to confirm the setup is really efficient. 2.00 g of the
ionic liquid was put in the pressure cell directly from the oven, and immediately the
pressure cell is closed and attached to the unit. Valve a, Va is closed while valve b, Vb
and valve c, Vc are opened. The unit was connected to a vacuum pump and the system is
evacuated for 30 minutes. CO2 gas is introduced to the system by opening Va. (The
equilibrium condition was judged when the pressure was unchanged). The amount of
gas introduced is determined using PVT relation by pressure measurement. Vb is opened so that ionic liquid sample could be in contact with CO2 gas. After equilibrium as
indicated by negligible pressure change, the pressure is measured again to determine the
amount of CO2gas left in vapor phase. The different in the amount of CO2 gas is taken
as the amount ofCO2 dissolves.
Solubility of CO2 gas in ionic liquid is determined based on CO2 gas molality and the
mole fraction between the number of moles of CO2 gas absorbed in ionic liquid and the
number of moles of ionic liquid used in the experiment. The relationship between
pressure and mole fraction of CO2 gas in ionic liquid is analyzed. Henry's constant of
C02 in this phosphonium-based ionic liquid also was determined and graph of Henry's
constant versus inverse temperature is plotted.
Finally, new experimental results for the solubility of C02 in thenew synthesized ionic
liquid [PmCioPgss] docusate are presented for temperatures 298.15 K, 303.15 K, and
308.15 K and pressures ranging from 15 to 25 bars. Henry's law constants are
determined from that solubility pressure data. The solubility pressures were correlated
by meansofextendedHenry's law.