A fractional distillation process for separating ethylbenzene (EB) from a feed mixture C7(+)-cut naphtha, comprising nonaromatics, BTX, EB, styrene, and C8(+) fraction, was used. Primarily, 29.63 wt % EB in the bottom was obtained. Redistillation of the bottom component produced 63.98 wt % EB in the 2nd cut; finally, this cut was used as a feed to distillation process and 83.21 wt % EB was obtained in distillate, and this feed was used directly for dehydrogenation process to produce styrene monomer. All of the distilled fractions were analyzed by gas chromatography instrument. (c) 2006 Wiley Periodicals, Inc.