Process for distillation of styrenes

In a process for distillation of styrenes by distilling a liquid mixture of styrenes obtained by dehydrogenation of ethylbenzenes and separating styrenes from ethylbenzenes, the improvement which comprises

• feeding said liquid mixture of styrenes into a middle portion of a distillation column of a packed column type which is operated under reduced pressure;
• withdrawing from the top of said distillation column a vapor of low boiling components consisting mainly of ethylbenzenes and withdrawing from the bottom of said distillation column a liquid of high boiling components consisting mainly of styrenes;
• leading a large part of said vapor of low boiling components to a compressor to elevate the temperature of said vapor by adiabatic compression and leading the remaining part of said vapor of low boiling components to a condenser;
• introducing said compressed vapor of low boiling components to a reboiler of said distillation column wherein a part of said compressed vapor of low boiling components is condensed and the latent heat thereby released is used as a heat source for said reboiler;
• leading the condensed liquid of low boiling components condensed in said reboiler and the uncondensed vapor of low boiling components uncondensed in said reboiler to a vapor-liquid separation tank and separating said uncondensed vapor from said condensed liquid;
• returning said uncondensed vapor of low boiling components separated in said separation tank to said condenser;
• introducing said condensed liquid of low boiling components separated in said separation tank into a preheater wherein the condensed liquid of low boiling components undergo heat exchange with the vapor of low boiling components fed into the compressor through the preheater;
• thereafter refluxing a part of said condensed liquid of low boiling components condensed in said condenser and said reboiler to the upper portion of said distillation column via a refluxing line thereof;
• and
• withdrawing the remaining condensed liquid of low boiling components from the distillation system.