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US 9,809,509 B2Granted
Process for xylenes isomerization
AssigneeExxonMobil Chemical Patents Inc.
InventorsBrian M. Weiss, Darryl D. Lacy, Scott J. Weigel
Life of this patent
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Abstract
A process for the isomerization of a para-xylene depleted, meta-xylene rich stream under at least partially liquid phase conditions using ZSM-23 with an external surface area of at least 75 m2/g (indicating a small crystallite size), and a SiO2/Al2O3 ratio between 15 and 75 that produces a higher than equilibrium amount of para-xylene, i.e., more than about 24 wt % of para-xylene, based on the total amount of xylenes.
Claims11
A process for producing para-xylene from a C8 aromatic hydrocarbon mixture, the process comprising:
- (a) providing a C8 aromatic hydrocarbon mixture comprising para-xylene, ortho-xylene and meta-xylene to an ortho-xylene splitter to produce a first stream comprising para-xylene and meta-xylene and a second stream comprising ortho-xylene;
- (b) passing the first stream comprising para-xylene and meta-xylene to a para-xylene recovery unit to recover a para-xylene product stream and produce a para-xylene-depleted stream consisting essentially of meta-xylene;
- (c) contacting the para-xylene-depleted stream comprising meta-xylene with a catalyst under at least partially liquid phase conditions effective to produce a first isomerized stream having a para-xylene content of more than 24 wt.%, based on the total amount of xylenes in the first isomerized stream;
- and first isomerized stream, wherein the catalyst comprises ZSM-23 with a SiO2/A12O3 ratio between 15 and 50 and an external surface area of 75-115 m2/g;
- and
- (d) recycling at least a portion of the first isomerized stream back to the para-xylene recovery unit.
3 more elements
Dependencies are inferred from the claim text.