Abstract:
Light cycle oil (LCO), which is a product of the catalytic cracking of the vacuum gas oil in the
FCCU, contains a good percentage of aromatics, monocyclic and polycyclic. These compounds
need to be separated from the streams, as these are not very suitable in the further conversion
units or can add value to the specialized streams. In this study, liquid-liquid extraction has been
used to recover the aromatics (p-xylene) and bicyclic aromatics (naphthalene) from model oil.
The efficacies of various solvents have been tested for recovery of aromatics and bicyclic
aromatics. Equilibrium data have been presented for compound p-xylene and naphthalene using
the solvents: dimethyl sulfoxide (DMSO), N-methyl pyrrolidone (NMP) and dimethyl
formamide (DMF). Phase diagrams have been plotted for all these systems at the normal
temperature of industrial separation which are very much important in the industries. Regression
of the experimental points is done by NRTL and UNIQUAC equations. Qualitative analysis is
done on the basis of distribution coefficients and separation factors and graphs are produced for
the same. DMF was found to be very good solvent for recovery of p-xylene and naphthalene.
Various solvents are tested for their suitability for the recovery of aromatics. Quaternary systems
are studied for NMP and DMF systems and their efficiency for the recovery of bicyclic aromatic
compounds is studied. NMP was found to have a very good separation factor and distribution
coefficient for naphthalene. LSER model has been used to correlate the various physiochemical
properties of the solvents to the distribution coefficients and separation factors.
