Aromatics Production Process

• US 20160046544A1
• Filed: 06/18/2015
• Published: 02/18/2016
• Est. Priority Date: 08/15/2014
• Status: Active Grant

• Current Assignee: ExxonMobil Chemical Company (Exxon Mobil Corporation)
• Original Assignee: ExxonMobil Chemical Patents Inc. (Exxon Mobil Corporation)
• Inventors: Molinier, Michel, Knob, Kevin J., Stanley, Dennis J., Vander Pol, Terri S., Cao, Chunshe, Zheng, Xiaobo, Rault, Jacques, Pigourier, Jerome, LeFlour, Thierry, Claudel, Stephane, Prevost, Isabell, Fernandez, Celia
• Granted Patent: US 9,708,233 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: C07C 15/08 Xylenes
• CPC Class Codes: C07C 5/2732 Catalytic processes
• CPC Class Codes: C07C 6/126 of more than one hydrocarbon
• CPC Class Codes: C07C 7/005 Processes comprising at least two steps in series
• CPC Class Codes: C07C 7/04 by distillation

Abstract

In a process for producing para-xylene, at least one feed comprising C₆₊ aromatic hydrocarbons is supplied to a dividing wall distillation column to separate the feed into a C₇₋ aromatic hydrocarbon-containing stream, a C₈ aromatic hydrocarbon-containing stream and a C₉₊ aromatic hydrocarbon-containing stream. At least part of the C₈ aromatic hydrocarbon-containing stream is then supplied to a para-xylene recovery unit to recover para-xylene from the C₈ aromatic hydrocarbon-containing stream and produce a para-xylene depleted stream. The para-xylene depleted stream is contacted with a xylene isomerization catalyst in a xylene isomerization zone under conditions effective to isomerize xylenes in the para-xylene depleted stream and produce an isomerized stream, which is then at least partially recycled to the para-xylene recovery unit.

Claims

1. A process for producing para-xylene, the process comprising:

(a1) supplying at least one feed comprising C₆₊ aromatic hydrocarbons to a dividing wall distillation column to separate the feed into a C₇₋

aromatic hydrocarbon-containing stream, a C₈ aromatic hydrocarbon-containing stream and a C₉₊ aromatic hydrocarbon-containing stream;

(b1) supplying at least part of the C₈ aromatic hydrocarbon-containing stream to a para-xylene recovery unit to recover para-xylene from the C₈ aromatic hydrocarbon-containing stream and produce a para-xylene depleted stream;

(c1) contacting at least part of the para-xylene depleted stream with a xylene isomerization catalyst in a xylene isomerization zone under conditions effective to isomerize xylenes in the para-xylene depleted stream and produce an isomerized stream; and

(d1) recycling at least part of the isomerized stream to the para-xylene recovery unit.

2. The process of claim 1, wherein the at least one feed to (a1) comprises a mixture of C₆₊ aromatic and aliphatic hydrocarbons produced by removing C₅₋

hydrocarbons from a reformate stream.

3. The process of claim 2 and further comprising:

(e1) removing at least part of the aliphatic hydrocarbons from the C₇₋

aromatic hydrocarbon-containing stream to produce a C₇₋

aromatic hydrocarbon-enriched stream.

4. The process of claim 3 and further comprising:

(f1) supplying at least part of the C₇₋

aromatic hydrocarbon-enriched stream to a separation unit to recover benzene therefrom and produce a toluene-containing stream;

(g1) contacting at least part of the toluene-containing stream and at least part of the C₉₊ aromatic hydrocarbon-containing stream with a transalkylation catalyst under conditions effective to produce a transalkylation product containing xylenes; and

(h1) supplying at least part of the transalkylation product to the separation unit in (f1).

5. The process of claim 4, wherein the separation unit in (f1) comprises a further dividing wall distillation column.

6. The process of claim 1 and further comprising:

(i1) supplying at least part of the C₈ aromatic hydrocarbon-containing stream to an ethylbenzene removal zone; and

(j1) contacting the C₈ aromatic hydrocarbon-containing stream with a first catalyst in the ethylbenzene removal zone under conditions effective to remove at least part of the ethylbenzene in the C₈ aromatic hydrocarbon-containing stream.

7. The process of claim 6, wherein the conditions in the ethylbenzene removal zone are effective to maintain the C₈ aromatic hydrocarbon-containing stream substantially in the gas phase.

8. The process of claim 7, wherein the ethylbenzene removal zone is located upstream of the para-xylene recovery unit.

9. The process of claim 8, wherein the ethylbenzene removal zone also contains a second catalyst effective under said conditions to isomerize xylenes in the C₈ aromatic hydrocarbon-containing stream.

10. The process of claim 8, wherein the conditions in the xylene isomerization zone are effective to maintain the para-xylene depleted stream substantially in the liquid phase.

11. The process of claim 7, wherein the ethylbenzene removal zone is located downstream of the para-xylene recovery unit.

12. The process of claim 11, wherein the conditions in the xylene isomerization zone are effective to maintain the para-xylene depleted stream substantially in the gas phase.

13. The process of claim 11, wherein the conditions in the xylene isomerization zone are effective to maintain the para-xylene depleted stream substantially in the liquid phase.

14. A process for producing para-xylene and benzene, the process comprising:

(a2) supplying a feed comprising a mixture of C₆₊ aliphatic and aromatic hydrocarbons to a dividing wall distillation column to separate the feed into a C₇₋

hydrocarbon-containing stream, a C₈ hydrocarbon-containing stream and a C₉₊ hydrocarbon-containing stream;

(b2) removing at least part of the aliphatic hydrocarbons from the C₇₋

hydrocarbon-containing stream to produce a C₇₋

aromatic hydrocarbon-enriched stream;

(c2) supplying at least part of the C₇−

aromatic-enriched stream to a separation unit to separate the C₇−

aromatic-enriched stream into a benzene-containing stream and a toluene-containing stream;

(d2) supplying at least part of the C₈ hydrocarbon-containing stream to a para-xylene recovery unit to recover para-xylene from the C₈ hydrocarbon-containing stream and produce a para-xylene depleted stream;

(e2) contacting at least part of the para-xylene depleted stream with a xylene isomerization catalyst in a xylene isomerization zone under conditions effective to isomerize xylenes in the para-xylene depleted stream and produce an isomerized stream;

(f2) recycling at least part of the isomerized stream to the para-xylene recovery unit;

(g2) contacting at least part of the toluene-containing stream and at least part of the C₉₊ hydrocarbon-containing stream with a transalkylation catalyst under conditions effective to produce a transalkylation product containing xylenes; and

(h2) supplying at least part of the xylenes in the transalkylation product to the para-xylene recovery unit.

15. The process of claim 14, wherein the feed to (a2) is produced by removing C₅−

hydrocarbons from a reformate stream.

16. The process of claim 14 and further comprising:

(i2) supplying at least part of the C₈ aromatic hydrocarbon-containing stream from (a2) to an ethylbenzene removal zone which is located upstream of the para-xylene recovery unit; and

(j2) contacting the C₈ aromatic hydrocarbon-containing stream with a first catalyst in the ethylbenzene removal zone under conditions effective to remove at least part of the ethylbenzene in the C₈ aromatic hydrocarbon-containing stream prior to (d2).

17. The process of claim 16, wherein the ethylbenzene removal zone also contains a second catalyst effective under said conditions to isomerize xylenes in the C₈ aromatic hydrocarbon-containing stream.

18. The process of claim 16, wherein the conditions in the ethylbenzene removal zone are effective to maintain the C₈ aromatic hydrocarbon-containing stream substantially in the gas phase.

19. The process of claim 18, wherein the conditions in the xylene isomerization zone are effective to maintain the para-xylene depleted stream substantially in the liquid phase.

20. The process of claim 14 and further comprising:

(k2) supplying at least part of the para-xylene depleted stream from (d2) to an ethylbenzene removal zone which is located upstream of the xylene isomerization zone; and

(l2) contacting the para-xylene depleted stream with a first catalyst in the ethylbenzene removal zone under conditions effective to remove at least part of the ethylbenzene in the para-xylene depleted stream prior to (e2).

21. The process of claim 19, wherein the conditions in the ethylbenzene removal zone are effective to maintain the para-xylene depleted stream substantially in the gas phase.

22. The process of claim 20, wherein the conditions in the xylene isomerization zone are effective to maintain the para-xylene depleted stream substantially in the liquid phase.

23. The process of claim 14, wherein at least part of the transalkylation product from (g2) is supplied to the separation unit in (c2) and the separation unit is effective to separate xylenes from the transalkylation product and to separate the C₇−

aromatic-enriched stream into the benzene-containing stream and the toluene-containing stream.

24. The process of claim 14, wherein the separation unit in (c2) comprises a further dividing wall distillation column.

25. The process of claim 24 and further comprising:

(m2) removing a C₈₊ hydrocarbon residue stream from the further dividing wall distillation column; and

(n2) supplying at least part of the C₈₊ hydrocarbon residue stream to the para-xylene recovery unit.

27. The process of claim 25, wherein the separation system in (c3) comprises a further dividing wall distillation column.

26. A process for producing para-xylene and benzene, the process comprising:

(a3) supplying a feed comprising a mixture of C₆₊ aliphatic and aromatic hydrocarbons to a distillation column to separate the feed into a C₇₋

hydrocarbon-containing stream and a C₈₊ hydrocarbon-containing stream;

(b3) removing at least part of the aliphatic hydrocarbons from the C₇₋

hydrocarbon-containing stream to produce a C₇₋

aromatic hydrocarbon-enriched stream;

(c3) supplying at least part of the C₇₋

aromatic hydrocarbon-enriched stream to a separation system to recover benzene therefrom and produce a toluene-containing stream;

(d3) contacting at least part of the C₈₊ hydrocarbon-containing stream with an ethylbenzene dealkylation catalyst under conditions effective to dealkylate ethylbenzene in the C₈₊ hydrocarbon-containing stream and produce a dealkylation effluent comprising benzene and C₈₊ hydrocarbons;

(e3) supplying the dealkylation effluent to a dividing wall distillation column to separate the dealkylation effluent into a C₇₋

aromatic hydrocarbon-containing stream, a C₈ aromatic hydrocarbon-containing stream and a C₉₊ aromatic hydrocarbon-containing stream;

(f3) supplying at least part of the C₈ aromatic hydrocarbon-containing stream to a para-xylene recovery unit to recover para-xylene from the C₈ aromatic hydrocarbon-containing stream and produce a para-xylene depleted stream;

(g3) contacting at least part of the para-xylene depleted stream with a xylene isomerization catalyst under conditions effective to isomerize xylenes in the para-xylene depleted stream and produce an isomerized stream;

(h3) recycling at least part of the isomerized stream to the dividing wall distillation column;

(i3) contacting at least part of the toluene-containing stream and at least part of the C₉₊ hydrocarbon-containing stream with a transalkylation catalyst under conditions effective to produce a transalkylation product containing xylenes; and

(j3) supplying at least part of the transalkylation product to the separation system in (c3), wherein the separation system is also effective to separate xylenes from the transalkylation product from (i3).