TY - JOUR
T1 - Tuning task-specific ionic liquids for the extractive desulfurization of liquid fuel
AU - Zhao, Hua
AU - Baker, Gary A.
AU - Wagle, Durgesh V.
AU - Ravula, Sudhir
AU - Zhang, Qi
N1 - Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/9/6
Y1 - 2016/9/6
N2 - Extractive desulfurization of liquid fuel is a simple process that requires minimum energy input and can be operated via existing liquid-liquid extraction apparatuses. In particular, to achieve deep desulfurization, the conventional hydrodesulfurization (HDS) process has shown limitations in the removal of aromatic sulfur compounds. Recently, extractive desulfurization using a new type of nonvolatile solvent, ionic liquids (ILs), has yielded promising results. However, there is a lack of systematic evaluation of the effect of IL structure on desulfurization efficiency, and a lack of mechanistic understanding regarding how ILs lead to the partition of aromatic sulfur compounds from fuel to the IL phase. The present study examines a total of 71 ILs and two deep eutectic solvents (DESs) with combinations representing various cations and anions. We identify a number of ILs that yield high partition coefficients [up to 1.85 mg(S) kg (IL)-1/mg(S) kg (oil)-1] for the partition of aromatic sulfur compounds between ILs and n-octane or n-dodecane as surrogates for gasoline or diesel, respectively. We find that the high sulfur partition coefficient correlates with a high dipolarity/polarizability (π∗) or a low solvent polarizability (SP) of ILs carrying the same cation and different anions, but correlates with a low dipolarity/polarizability (π∗) for ILs carrying the same anion paired to cations bearing different alkyl chain lengths. We further demonstrate that a four-step extraction using ILs can achieve 99% dibenzothiophene (DBT) removal (i.e., an initial sulfur content of 500 ppm is reduced to <5 ppm following extraction).
AB - Extractive desulfurization of liquid fuel is a simple process that requires minimum energy input and can be operated via existing liquid-liquid extraction apparatuses. In particular, to achieve deep desulfurization, the conventional hydrodesulfurization (HDS) process has shown limitations in the removal of aromatic sulfur compounds. Recently, extractive desulfurization using a new type of nonvolatile solvent, ionic liquids (ILs), has yielded promising results. However, there is a lack of systematic evaluation of the effect of IL structure on desulfurization efficiency, and a lack of mechanistic understanding regarding how ILs lead to the partition of aromatic sulfur compounds from fuel to the IL phase. The present study examines a total of 71 ILs and two deep eutectic solvents (DESs) with combinations representing various cations and anions. We identify a number of ILs that yield high partition coefficients [up to 1.85 mg(S) kg (IL)-1/mg(S) kg (oil)-1] for the partition of aromatic sulfur compounds between ILs and n-octane or n-dodecane as surrogates for gasoline or diesel, respectively. We find that the high sulfur partition coefficient correlates with a high dipolarity/polarizability (π∗) or a low solvent polarizability (SP) of ILs carrying the same cation and different anions, but correlates with a low dipolarity/polarizability (π∗) for ILs carrying the same anion paired to cations bearing different alkyl chain lengths. We further demonstrate that a four-step extraction using ILs can achieve 99% dibenzothiophene (DBT) removal (i.e., an initial sulfur content of 500 ppm is reduced to <5 ppm following extraction).
KW - Cation-π interaction
KW - Desulfurization
KW - Extraction
KW - Ionic liquid
KW - Partition coefficient
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U2 - 10.1021/acssuschemeng.6b00972
DO - 10.1021/acssuschemeng.6b00972
M3 - Article
AN - SCOPUS:84985987317
SN - 2168-0485
VL - 4
SP - 4771
EP - 4780
JO - ACS Sustainable Chemistry and Engineering
JF - ACS Sustainable Chemistry and Engineering
IS - 9
ER -