INVESTIGATION ON POTENTIAL IONIC LIQUIDS FOR EXTRACTIVE DESULFURIZATION OF DIESEL

The prospect of ionic liquids (ILs) as industrial solvent for desulfurization process
may be illustrated from several explanations of the solute-solvent interaction point of
view. For the aromatic organosulfur as a solute, the explanations of its miscibility in
ILs are mostly described through n-electron density by means of n-n or CH-n
interaction mechanism. The prediction using COSMO-RS which majorly rely on
hydrogen bonding mechanism, showed inconsistent results against experimental data.
The present study using Raman spectroscopy has led to the same conclusion where n�electron density becomes a vital viewpoint in the process of screening potential ILs
for desulfurization. The use of a new complementary method which estimates the
aromaticity index (AI) for cation and double bond equivalent (DBE) for anion
selection showed good agreement between the literature and experimental results. The
AI and DBE methods were later used to select the appropriate combination of cation
and anion ofiLs for extractive desulfurization study.
From the 407 potential ILs selected based on COSMO-RS database, 25 ILs as
suggested from the complementary method were synthesized for further evaluation.
Out of the 25, some which are commercially available were purchased for validation
purposes. The synthesized ILs were characterized accordingly by 1
H NMR, 13C NMR,
elemental analysis, and halide content including their water contents, densities and
refractive indices. A single batch extraction at room temperature for extracting
benzothiophene (BT) from model oil (n-C12) was well studied to determine the
optimum extracting conditions of stirring speed and extraction time. The effect of
three important process variables (mass ratio, BT concentration and temperature)
were also investigated using Response Surface Methodology (RSM).