Non-aromatic compound removal systems for para-xylene production

Patent metadata

Field	Value
Publication number	US-11999692-B2
Application number	US-202318363360-A
Country	US
Kind code	B2
Filing date	Aug 1, 2023
Priority date	Aug 14, 2019
Publication date	Jun 4, 2024
Grant date	Jun 4, 2024

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 through a membrane unit, the membrane unit producing a non-aromatics rich stream and a membrane unit product stream;
feeding the membrane unit product stream into a xylene splitter, the xylene splitter producing a mixed xylene stream, the mixed xylene stream comprising para-xylene, ortho-xylene, and meta-xylene;
processing the mixed xylene stream in a para-xylene recovery unit, the para-xylene recovery unit producing a para-xylene lean stream;
processing the para-xylene lean stream in an isomerization unit, the isomerization unit producing an isomerization unit product stream;
feeding the isomerization unit product stream into a deheptanizer unit, the deheptanizer unit producing a xylene rich stream;
processing the xylene rich stream through a clay treater, the clay treater producing a clay treated stream; and
feeding the clay treated stream into the xylene splitter.

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 , further comprising producing, via the deheptanizer unit, a hydrocarbon stream.

4. The method of claim 3 , wherein the isomerization unit product stream comprises 50 wt % meta-xylene, 24 wt % para-xylene, and 26 wt % ortho-xylene.

5. The method of claim 3 , wherein the hydrocarbon stream comprises C6 aromatic compounds, C7 aromatic compounds, and non-aromatic compounds.

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

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

8. 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.

9. The method of claim 1 , wherein the reformate stock stream is fed into the membrane unit at a constant pressure between 200 to 2000 psig.

Assignees

• Exxonmobil Technology & Engineering Company
• Exxonmobil Engineering & Tech Company

Inventors

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

Classifications

• C07C7/144 Primary

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

• B01D61/007 Primary

  Separation by stereostructure, steric separation · CPC title

• C07C7/005 Primary

  Processes comprising at least two steps in series · CPC title

• B01D2317/025

  Permeate series · CPC title

• C07C7/04

  by distillation · CPC title