Technical Evaluation of Ionic Liquid-Extractive Processing
of Ultra Low Sulfur Diesel
Fuel
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Abstract
Recent
trends in legislation across the world are aimed toward
the reduction of the levels of sulfur in fuel oils to less than 10
ppm (ultra low sulfur diesel, ULSD) due to its toxic and environmental
effects. Hydrodesulfurization (HDS) is the current method used for
desulfurization and faces technical challenges, due to the extreme
conditions and energy consumption necessary to reach low sulfur levels.
Recently, ionic liquid (IL) technology has been proposed as a possible
solution toward achieving ULSD. ILs represent a new class of “green”
solvents that are gaining popularity due to their favorable properties
and have recently been shown to be effective extractants for desulfurization
on a laboratory scale. In this work, the feasibility of industrial
scale IL-extractive processing of ULSD has been examined via the simulation
and optimization of a conceptual process in ASPEN Plus. The widely
used [C<sub>n</sub>mim] [NTF<sub>2</sub>] series of ionic liquids
have been employed, due to their favorable properties and the availability
of experimental data in literature. User-defined ionic liquid components
have been created within ASPEN Plus, incorporating several thermodynamic
and physical property parameters derived from literature, to allow
the process to be simulated via the UNIFAC thermodynamic method. On
the basis of the technical analysis, it is proposed that the most
feasible process configuration consists of HDS as a preliminary treatment,
followed by IL extraction as intermediate treatment to reduce the
sulfur content to 50 ppm, with adsorption as the final treatment to
achieve ULSD levels