P-Xylene-Recovery by Adsorption

Abstract

The UOP Parex process was the first commercial process. It is a continuous process using a fixed bed of adsorbent. All process streams are in the liquid phase at constant temperature in the bed. Feed is introduced and p-xylene is se 1ect i ve 1y adsorbed. The adsorbed p-xylene is recovered from the pores of the adsorbent by displacement with another liquid hydrocarbon. The stream leaves the adsorbent bed with both the p-xylene product and the rejected raffinate streams The desorbent is recovered from these two streams by fractionation and is recycled to the adsorbent bed. A rotary valve is employed in the process to stimulate countercurrent flow of solid and liquid without actual movement of the solid adsorbent.