Integrated aromatics formation and methylation

Patent metadata

Field	Value
Publication number	US-11377402-B2
Application number	US-201816605387-A
Country	US
Kind code	B2
Filing date	Apr 19, 2018
Priority date	May 22, 2017
Publication date	Jul 5, 2022
Grant date	Jul 5, 2022

Abstract

Systems and methods are provided for integration of an aromatic formation process for converting non-aromatic hydrocarbon to an aromatic product and subsequent methylating of a portion of the aromatic product to produce a methylated product, with improvements in the aromatic formation process and/or the methylation process based on integrating portions of the secondary processing trains associated with the aromatic formation process and the methylation process. The aromatic formation process and methylation process can be used, for example, for integrated production of specialty aromatics or gasoline blending components.

First claim

The invention claimed is:

1. A method for forming aromatic compounds, comprising:
providing a feed comprising a non-aromatic hydrocarbon, at least a portion of the non-aromatic hydrocarbon being obtained from each of a recycle portion of a first light ends stream and a recycle portion of a second light ends stream;
aromatizing at least a portion of the feed's non-aromatic hydrocarbon to produce an aromatic formation effluent comprising benzene, a C 7 aromatic hydrocarbon, and a C 8 aromatic hydrocarbon, the aromatization being carried out in an aromatic formation process under effective aromatic formation conditions;
separating from the aromatic formation effluent a first higher boiling intermediate stream, a first lower boiling intermediate stream, and a first light ends stream which includes the recycle portion of the first light ends stream, wherein the first higher boiling intermediate stream has a C 7 aromatic hydrocarbon concentration (weight percent), a C 8 aromatic hydrocarbon concentration (weight percent) or a combined C 7 -C 8 aromatic hydrocarbon concentration (weight percent) greater than those of the aromatic formation effluent, wherein the first lower boiling intermediate stream has a benzene concentration (weight percent), a C 7 aromatic hydrocarbon concentration (weight percent) or a combined C 6 -C 7 aromatic hydrocarbon concentration (weight percent) greater than those of the aromatic formation effluent, and wherein the first light ends stream comprises a C 2 -C 5 hydrocarbon;
methylating at least a portion of the first lower boiling intermediate stream with a methylating agent to form a methylated intermediate stream, the methylated intermediate stream having a C 7 -C 8 aromatic hydrocarbon concentration (weight percent) greater than that of the portion of the first lower boiling intermediate stream which reacts to form the methylated intermediate stream;
separating from the methylated intermediate stream a second higher boiling intermediate stream, a second lower boiling intermediate stream, and a second light ends stream which includes the recycle portion of the second light ends stream, wherein the second higher boiling intermediate stream has a C 7 -C 8 aromatic hydrocarbon concentration (weight percent) greater than that of the methylated intermediate stream, and wherein the second light ends stream comprises a C 2 -C 5 hydrocarbon;
and
transferring the recycle portion of the first light ends stream and the recycle portion of the second light ends stream to the feed.

2. The method of claim 1 , the method further comprising:
separating a first para-xylene enriched fraction and a first para-xylene depleted fraction from the first higher boiling intermediate stream, the first para-xylene enriched fraction having a para-xylene concentration (weight percent) greater than that of the first higher boiling intermediate stream;
separating a second para-xylene enriched fraction and a second para-xylene depleted fraction from the second higher boiling intermediate stream, the second para-xylene enriched fraction having a para-xylene concentration (weight percent) greater than that of the second higher boiling intermediate stream;
isomerizing at least a portion of the first para-xylene depleted fraction, the second para-xylene depleted fraction, or a combination thereof to form an isomerized product stream, wherein the portion of the first para-xylene depleted fraction, the second para-xylene depleted fraction, or a combination thereof subjected to the isomerization has a para-xylene concentration (weight percent) less than that of the isomerized product stream; and
separating a third para-xylene enriched fraction from the isomerized product stream, the third para-xylene enriched fraction having a para-xylene concentration (weight percent) greater than that of the isomerized product stream.

3. The method of claim 1 , wherein the separating from the aromatic formation effluent a first higher boiling intermediate stream, a first lower boiling intermediate stream, and a first light ends stream comprises:
separating from the aromatic formation effluent a hydrogen-containing stream comprising at least 50 wt. % of methane, hydrogen, and carbon oxides relative to a weight of the hydrogen-containing stream and a demethanized stream comprising the first higher boiling intermediate stream, the first lower boiling intermediate stream, and the first light ends stream;
separating from the demethanized stream a demethanized aliphatic hydrocarbon stream comprising the first light ends stream and an aromatics-containing stream comprising the first higher boiling intermediate stream and the first lower boiling intermediate stream, the demethanized aliphatic hydrocarbon stream being enriched in C 2 -C 3 hydrocarbons relative to the demethanized stream; and
separating from at least a portion of the aromatics-containing stream the first higher boiling intermediate stream and the first lower boiling intermediate stream.

4. The method of claim 1 , wherein separating from the aromatic formation effluent a first higher boiling intermediate stream, a first lower boiling intermediate stream, and a first light ends stream comprises:
separating an aromatics-containing stream and an aliphatic hydrocarbon stream from the aromatic formation effluent;
separating from at least a portion of the aromatics-containing stream the first higher boiling intermediate stream and the first lower boiling intermediate stream; and
separating from the aliphatic hydrocarbon stream a hydrogen-containing stream comprising at least 50 wt. % of methane, hydrogen, and carbon oxides relative to a weight of the hydrogen-containing stream and a demethanized aliphatic hydrocarbon stream comprising the first light ends stream, the demethanized aliphatic hydrocarbon stream being enriched in C 2 -C 3 hydrocarbons relative to the aliphatic hydrocarbon stream.

5. The method of claim 4 , wherein the demethanized aliphatic hydrocarbon stream is enriched in C 2 -C 5 hydrocarbons relative to at least one of the demethanized stream and the aliphatic hydrocarbon stream.

6. The method of claim 1 , wherein the first lower boiling intermediate stream is a C 6 aromatics stream, and/or wherein the second higher boiling intermediate stream is a C 7 aromatics stream.

7. The method of claim 1 , wherein the effective aromatic formation conditions comprise conversion of less than 10 wt. % of methane relative to a weight of methane in the feed.

8. The method of claim 1 , further comprising separating at least a portion of the second light ends stream and a stream comprising dimethyl ether from the second light ends stream.

9. The method of claim 1 , further comprising separating a deoxygenated light ends stream and a stream comprising dimethyl ether from the second light ends stream; and
separating the recycle portion of the second light ends stream from the deoxygenated light ends stream.

10. The method of claim 1 , wherein the recycle portion of the second light ends stream comprises a C 2 -C 3 olefin stream, a C 2 -C 3 hydrocarbon stream, or a combination thereof.

11. The method of claim 1 , wherein the aromatic formation effluent comprises≤20 wt. % of C 8 aromatic hydrocarbon.

12. The method of claim 1 , wherein the first lower boiling intermediate stream is a C 6 -C 7 aromatics stream.

13. The method of claim 1 , wherein the first lower boiling intermediate stream is a C 7 aromatics stream, the method further comprising separating a C 6 aromatics stream from the aromatic formation effluent.

14. The method of claim 1 , wherein the aromatic formation process includes

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Dorsi Catherine M
• Detjen Todd E
• Shekhar Mayank
• Go Anthony

Classifications

• C07C15/073

  Ethylbenzene · CPC title

• C07C2/76

  by condensation of hydrocarbons with partial elimination of hydrogen · CPC title

• C07C5/2737

  with crystalline alumino-silicates, e.g. molecular sieves · CPC title

• C07C15/08

  Xylenes · CPC title

• C07C15/04

  Benzene · CPC title