Patent ID: 9522863
Filing Date: 2016-12-20
CPC Classification: C07C

Claim Text:
1. A process for separating paraxylene from at least one multicomponent feed by simulated countercurrent adsorptive separation in an apparatus comprising at least one column comprising multiple adsorbent bed chambers comprising adsorbent beds stacked one on too of the other, wherein a circulating bulk fluid flows into the top of an adsorbent bed chamber, through the adsorbent bed and down to the top of the next adsorbent bed chamber, said process comprising the steps of: (a) passing said multicomponent feed through a conduit into an absorbent bed in an adsorbent bed chamber to adsorb paraxylene on said adsorbent, wherein the multicomponent feed comprises a C8 aromatic mixture of paraxylene, orthoxylene, metaxylene, and ethylbenzene, said C8 aromatic mixture comprising from 15 to 30 volume percent of paraxylene, (b) passing at least one first flushing medium into conduit of step (a) in fluid communication with the adsorbent bed chamber to flush residue of the multicomponent feed from the conduit and into the adsorbent bed of the adsorbent bed chamber comprising adsorbed paraxylene, wherein the first flushing medium comprises from 10 to 95 volume percent, based on the total volume of the first flushing medium, of a C8 aromatic mixture and from 5 to 70 volume percent of a non-C8 aromatic liquid, which is miscible with C8 aromatics, and wherein the C8 aromatic mixture in the first flushing medium comprises from 75 to 98 volume percent of paraxylene; (c) passing at least one second flushing medium into the conduit of step (b) in fluid communication with the adsorbent bed chamber to flush residue of the first flushing medium from the conduit into the adsorbent bed of the adsorbent bed chamber, wherein the second flushing medium comprises less than 1 volume percent of ethylbenzene, less than 2 volume percent of orthoxylene, and less than 2 volume percent of metaxylene; and (d) withdrawing an extract stream comprising paraxylene from the conduit of step (c) after the second adsorbent bed has been subjected to said second flushing step (c).