densities between the crude oil and the ionic liquid. The ionic
liquid has a density of 1.06 g mLÀ1 compared to the crude oil,
which has a density of 1.03 g mLÀ1 as determined using a
pycnometer. After separating the phases, the top phase was
decanted and the bottom phase was heated at 120 1C for
2 hours to reverse. After reversal, filtration may be needed to
remove inorganic salts or other contaminants, but for our oil
sample this was not necessary. The cycle can then be repeated
by reintroducing oil. Table 1 shows the impurity of the
product phase, as determined by 1H NMR over the course
of the three recycles. The hydrocarbon phase has only small
amounts of TESAC dissolved. These results also demonstrate
that the separation has not changed considerably over the
course of three recycles. We expect the separation to improve
on a larger scale. Also, the TESAC phase has a substantial
amount of dissolved hydrocarbon, but this phase will be
saturated after the first cycle and recycled. The TESAC
phase is expected to contain other impurities such as sulfur,
water, and heavy metals like arsenic that are common to
crude oil.
Notes and references
1 P. G. Jessop, D. J. Heldebrant, L. Xiaowant, C. A. Eckert and
C. L. Liotta, Nature, 2005, 436, 1102.
2 T. Yamada, P. J. Lukac, M. George and R. G. Weiss, Chem.
Mater., 2007, 19, 967.
3 D. Vinci, M. Donaldson, J. P. Hallett, E. A. John, P. Pollet,
C. A. Thomas, J. D. Grilly, P. G. Jessop, C. L. Liotta and
C. A. Eckert, Chem. Commun., 2007, 1427–1429.
4 L. Phan, D. Chiu, D. Heldebrant, H. Huttenhower, E. John, X. Li,
P. Pollet, R. Wang, C. A. Eckert, C. L. Liotta and P. G. Jessop,
Ind. Eng. Chem. Res., 2008, 47, 539–545.
5 E. Bates, R. Mayton, I. Ntai and J. Davis, J. Am. Chem. Soc.,
2002, 124, 926–927.
6 M. Soutullo, C. Odom, B. Wicker, C. Henderson, A. Stenson and
J. Davis, Chem. Mater., 2007, 19, 3581–3583.
7 K. Gutowski and E. Maginn, J. Am. Chem. Soc., 2008, 130,
14690–14704.
8 NMR spectra were run at room temperature using a Varian-
Mercury VX400 MHz spectrometer. Neat NMR spectra were
run using a capillary tube inside the NMR tube.
9
13C NMR for TMSAC dppm: 50.0 (OCH3), 43.9 (CH2N), 42.8
(CH2N), 23.8 (CH2), 23.2 (CH2), 5.8 (CH2Si); for TMSA dppm
:
1
49.7 (OCH3), 45.0 (CH2N), 27.1 (CH2), 6.1 (CH2Si). H NMR for
TMSAC dppm: 6.0 (3H, br, NH3+), 4.5 (1H, br, NH), 3.5 (18H, br,
OCH3), 3.0 (2H, br, CH2N), 2.6 (2H, br, CH2N), 1.6 (2H, br, CH2),
1.5 (2H, br, CH2), 0.6 (4H, br, CH2Si); for TMSA dppm: 3.9 (9H, s,
OCH3), 2.9 (2H, t, CH2N), 1.8 (2H, m, CH2), 0.9 (2H, t, CH2Si).
In conclusion, we have developed a new class of one-
component, reversible, ionic liquid solvents. These solvents
have advantageous properties that can be tuned by varying
their chemical structure. As presented here, TESAC has been
successfully used to remove hydrocarbons from contaminated
crude oil with a built-in separation technique. We are currently
looking at this class of solvents for CO2 capture from flue
gas streams. These molecules can act as both physical and
chemical adsorption agents for selective carbon capture. In
addition, their properties, such as reversal energy require-
ments, can be tuned to improve process economics. Further,
we are developing one-component ionic liquids able to operate
better in the presence of water.
10 13C NMR for TESAC dppm: 57.7 (OCH2), 44.1 (CH2NH), 41.5
(CH2NH), 23.7 (CH2), 21.3 (CH2), 17.9 (CH3), 7.6 (CH2Si), 7.4
(CH2Si); for TESA dppm: 58.1 (OCH2), 45.3 (CH2NH2), 27.6
(CH2), 18.3 (CH3), 7.8 (CH2Si). 1H NMR for TESAC dppm: 9.6
(3H, br, NH3+), 6.0 (1H, br, NH), 4.0 (12H, br, OCH2), 3.2 (2H,
br, CH2NH), 3.0 (2H, br, CH2NH), 1.9 (2H, br, CH2), 1.7 (2H, br,
CH2),1.4 (18H, br, CH3), 0.8 (4H, br, CH2Si); for TESA dppm: 4.1
(6H, m, OCH2), 2.9 (2H, t, CH2NH2), 1.8 (2H, m, CH2),1.5 (9H, t,
CH3), 0.9 (2H, t, CH2Si).
11 TGA on the ionic liquids was run from 20 to 500 1C at 20 1C minÀ1 on
a Q50 TA Instruments machine. Residual mass left at the end of the
run (B10 wt%) is due to decomposition products. Nitrogen flow was
at 40 mL minÀ1. DSC was run from 20 to 300 1C at 20 1C minÀ1 on a
Q20 TA Instruments machine. Nitrogen flow was at 50 mL minÀ1
.
12 A. J. Carmichael and K. R. Seddon, J. Phys. Org. Chem., 2000, 13,
591–595.
13 J. F. Deye, T. A. Berger and A. G. Anderson, Anal. Chem., 1990,
62, 615–622.
14 Viscosity measurements were made on a 1 mL cup and bob Anton
Paar MCR 300 viscometer with the temperature controlled at
25 1C. Shear rates increased from 0 to 500 sÀ1 and then decreased
from 500 to 0 sÀ1. The solvents are both Newtonian fluids and no
shear thinning is evident.
We acknowledge our collaborator Dr Phillip Jessop
from the Department of Chemistry at Queen’s University for
providing the crude oil sample. Also, we thank Dr Victor
Breedveld and Jae Cho from Georgia Institute of Technology
for use of and assistance with their viscosity equipment and
Dr Paul Kohl and Jose Vega, also from Georgia Institute of
Technology, for use of their laboratory’s pycnometer.
ꢀc
This journal is The Royal Society of Chemistry 2009
118 | Chem. Commun., 2009, 116–118