Non-aromatic compound removal systems for para-xylene production

Patent metadata

Field	Value
Publication number	US-11760706-B2
Application number	US-202017634956-A
Country	US
Kind code	B2
Filing date	Jul 2, 2020
Priority date	Aug 14, 2019
Publication date	Sep 19, 2023
Grant date	Sep 19, 2023

Abstract

Selective removal of non-aromatic hydrocarbons from a xylene isomerization process for para-xylene production is accomplished using a membrane unit positioned within a xylene recovery loop. The membrane unit may include a one-stage or multi-stage (e.g., two-stage) membrane system and may be configured to separate a membrane unit product stream from a non-aromatics rich stream, which can be removed from the xylene recovery loop. The membrane unit may have a xylene permeance of about 60 gm/m2/hr/psi and a xylene to non-aromatic permeance ratio of about 15.

First claim

What is claimed is:

1. A method for removing non-aromatic compounds from a para-xylene production process, comprising:
feeding a reformate stock stream into a xylene recycle loop comprising a xylene splitter, a para-xylene recovery unit, a membrane unit, an isomerization unit, a deheptanizer unit, and a clay treater;
producing, via the xylene splitter configured to receive the reformate stock stream, a mixed xylene stream comprising para-xylene, ortho-xylene, and meta-xylene;
producing, via the para-xylene recovery unit configured to receive the mixed xylene stream, a para-xylene lean stream;
permeating xylene in the para-xylene lean stream via the membrane unit to separate a non-aromatics rich stream from a membrane unit product stream;
processing the membrane unit product stream in the isomerization unit to produce an isomerization unit product stream;
producing, via the deheptanizer unit configured to receive the isomerization unit product stream, a xylene rich stream;
processing the xylene rich stream through the clay treater to produce a clay treated stream; and
feeding the clay treated stream into the xylene splitter for recirculation within the xylene recycle loop.

2. The method of claim 1 , wherein the reformate stock stream comprises non-aromatic compounds, mixed xylenes, C6 aromatic compounds, and C7 aromatic compounds.

3. The method of claim 1 , wherein preferentially permeating the xylenes from the para-xylene lean stream via the membrane unit further comprises feeding the para-xylene lean stream into the membrane unit at a constant pressure between 200 to 2000 psig.

4. The method of claim 1 , wherein the membrane unit comprises a one-stage membrane system.

5. The method of claim 1 , wherein the membrane unit comprises a multi-stage membrane system.

6. The method of claim 1 , wherein the membrane unit presents a xylene permeance of 60 gm/m 2 /hr/psi and a xylene to non-aromatic permeance ratio of 15.

7. The method of claim 1 , further comprising producing, via the deheptanizer unit, a hydrocarbon stream.

8. The method of claim 7 , wherein the isomerization unit product stream comprises 50 wt % meta-xylene, 24 wt % para-xylene, and 26 wt % ortho-xylene.

9. The method of claim 7 , wherein the hydrocarbon stream comprises C6 aromatic compounds, C7 aromatic compounds, and non-aromatic compounds.

Assignees

• Exxonmobil Technology & Engineering Company

Inventors

• Minhas Bhupender S
• Abichandani Jeevan S
• Van Nuland Marcus L H
• Cheng Wai Kit
• Wang Chong-Jhoo
• Tinger Robert G

Classifications

• C07C7/005 Primary

  Processes comprising at least two steps in series · CPC title

• B01D61/007 Primary

  Separation by stereostructure, steric separation · CPC title

• C07C7/144 Primary

  using membranes, e.g. selective permeation · CPC title

• C07C7/04

  by distillation · CPC title

• B01D2317/022

  Reject series · CPC title