Process and apparatus for the production of para-xylene

摘要

A process for producing para-xylene (PX) comprises supplying a hydrocarbon feed comprising xylenes and ethylbenzene (EB) to a PX recovery unit, where a PX-rich stream and at least one PX-depleted stream are recovered from the feed. The PX-depleted stream is then separated into an EB-rich stream and an EB-depleted stream in a divided wall column. The EB-depleted stream is then isomerized under at least partial liquid phase conditions to produce a first isomerized stream having a higher PX concentration than the PX-depleted stream, and the EB-rich stream is isomerized under at least partial vapor phase conditions to produce a second isomerized stream having a higher PX concentration than the PX-depleted stream. The first and second isomerized streams are then recycled to the PX recovery unit to recover additional PX and the process is repeated to define a so-called xylene isomerization loop.

主权项

1. A process for producing para-xylene, the process comprising:
(a) providing a hydrocarbon feed comprising para-xylene, meta-xylene, ortho-xylene, and ethylbenzene to a para-xylene recovery unit; (b) recovering a para-xylene-rich stream and at least one para-xylene-depleted stream from the hydrocarbon feed in the para-xylene recovery unit; (c) separating the at least one para-xylene-depleted stream into an ethylbenzene-rich stream, which contains a majority portion of the ethylbenzene from the at least one para-xylene-depleted stream, and an ethylbenzene-depleted stream, which contains a minor portion of the ethylbenzene from the at least one para-xylene-depleted stream, in a divided wall column; (d) isomerizing at least a portion of the ethylbenzene-depleted stream at least partially in the liquid phase back towards an equilibrium concentration of the xylenes isomers to produce a first isomerized stream having a higher para-xylene concentration than the para-xylene-depleted stream; (e) isomerizing meta-xylene, ortho-xylene, and ethylbenzene in at least a portion of the ethylbenzene-rich stream at least partially in the vapor phase back towards to an equilibrium concentration of xylene isomers to produce a second isomerized stream having a higher para-xylene concentration than the para-xylene-depleted stream; and (f) recycling at least a portion of the first and second isomerized streams to the para-xylene recovery unit.