Conversion of non-aromatic hydrocarbon

Patent metadata

Field	Value
Publication number	US-10059641-B2
Application number	US-201615240793-A
Country	US
Kind code	B2
Filing date	Aug 18, 2016
Priority date	Sep 25, 2015
Publication date	Aug 28, 2018
Grant date	Aug 28, 2018

Abstract

Systems and methods are provided for converting alkane while generating improved yields of desirable aromatics and/or improved selectivity for forming desired aromatics, such as para-xylene (p-xylene). Aromatics generated during the aromatic formation process can be alkylated to form xylenes with improved yield and/or improved selectivity.

First claim

The invention claimed is:

1. A method for forming aromatic compounds, comprising:
providing a feed comprising non-aromatic hydrocarbon, the feed's non-aromatic hydrocarbon comprising C 1 -C 9 alkane, at least 50 wt. % of the feed's non-aromatic hydrocarbon comprising C 1 -C 2 alkane;
producing an aromatic formation effluent comprising benzene, C 7 aromatic hydrocarbon, and ≤10 wt. % of C 8 aromatic hydrocarbon from at least a portion of the feed's non-aromatic hydrocarbon in an aromatic formation process carried out under effective aromatic formation conditions, the aromatic formation process including converting at least 20 wt. % of the feed's C 1 -C 9 alkane;
separating from the aromatic formation effluent a first C 8 intermediate stream and a first lower boiling intermediate stream, the first C 8 intermediate stream having a C 8 aromatic hydrocarbon concentration (weight percent) greater than that of the aromatic formation effluent, the first lower boiling intermediate stream having 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;
reacting at least a portion of the first lower boiling intermediate stream with a methylating agent in the presence of a zeolite catalyst to form a methylated intermediate stream, the methylated intermediate stream having a 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 C 8 intermediate stream and a second lower boiling intermediate stream, the second C 8 intermediate stream having a C 8 aromatic hydrocarbon concentration (weight percent) greater than that of the methylated intermediate stream;
separating from the first C 8 intermediate stream, the second C 8 intermediate stream, or a combination thereof (a) a first para-xylene enriched fraction from the first C 8 intermediate stream, the first para-xylene enriched fraction having a para-xylene concentration (weight percent) greater than that of the first C 8 intermediate stream, (b) a second para-xylene enriched fraction from the second C 8 intermediate stream, the second para-xylene enriched fraction having a para-xylene concentration (weight percent) greater than that of the second C 8 intermediate stream, and (c) a para-xylene depleted fraction, the separations (a), (b), and (c) being carried out in a common separation process;
isomerizing at least a portion of the para-xylene depleted fraction to form an isomerized product stream, wherein the portion of the para-xylene depleted fraction 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.

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

3. 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.

4. The method of claim 1 , wherein (a) benzene and C 7 aromatic hydrocarbon together constitute at least 50 wt. % of the total aromatic hydrocarbon in the aromatic formation effluent and/or (b) the aromatic formation effluent comprises 10 wt. % or less of C 8 aromatic hydrocarbon.

5. The method of claim 1 , wherein the aromatic formation process includes at least one of (a) at least 5 wt. % of the non-aromatic hydrocarbon converted in the aromatic formation process is methane, (b) at least 10 wt. % of the non-aromatic hydrocarbon converted in the aromatic formation process is ethane, at least 20 wt. % of the non-aromatic hydrocarbon converted in the aromatic formation process is C 1 -C 4 alkane, and (d) 50 wt. % or less of the non-aromatic hydrocarbon converted in the aromatic formation process is C 5 -C 9 alkane.

6. The method of claim 1 , further comprising determining a first relative valuation of toluene to benzene, and determining a second relative valuation of the feed's non-aromatic hydrocarbon to the methylation agent.

7. The method of claim 6 , further comprising preselecting the effective aromatic formation conditions to produce an aromatic formation effluent having a toluene to benzene molar ratio ≥1.4 when the first relative valuation is greater than 1.0 and/or the second relative valuation is less than 1.0.

8. The method of claim 1 , wherein (a) the separating of (i) the first C 8 intermediate stream and the first lower boiling intermediate stream from the aromatic formation effluent and (ii) the second C 8 intermediate stream and the second lower boiling intermediate stream from the methylated intermediate stream, are carried out in a divided wall separator, (b) the second lower boiling intermediate stream is combined with the first lower boiling intermediate stream before the reacting at least a portion of the first lower boiling intermediate stream with the methylating agent, and (c) the first C 8 intermediate stream is not combined with the second C 8 intermediate stream before the common separation process.

9. The method of claim 8 , wherein the common separation process comprises a common simulated moving bed separation process.

10. The method of claim 9 , wherein the separation of the third para-xylene enriched fraction from the isomerized product stream is carried out in the common separation process.

11. The method of claim 10 , wherein at least a portion of the first C 8 intermediate stream and/or at least a portion of the second C 8 intermediate stream is introduced into the common simulated moving bed separator at a different location than that of the isomerized product stream.

12. The method of claim 10 , wherein at least a portion of the first C 8 intermediate stream, at least a portion of the second C 8 intermediate stream, or a combination thereof is introduced into the common simulated moving bed separator as a flushing stream.

13. The method of claim 1 , wherein (a) the methylated intermediate stream's C 8 aromatic hydrocarbon concentration (weight percent) is ≥Z 1 times the aromatic formation effluent's C 8 aromatic hydrocarbon concentration (weight percent) and (b) Z 1 is equal to 0.7, or 0.9, or 1.0, or 1.5, or 2.0.

14. The method of claim 1 , wherein ≥90 wt. % of the portion of the para-xylene depleted product subjected to the isomerizing is in the liquid phase during the isomerizing.

15. The method of claim 1 , wherein the aromatic formation effluent includes ≤10 wt. % ethylbenzene based on the total weight of aromatic hydrocarbon in the aromatic formation effluent, and/or the aromatic formation effluent includes ≤20 wt. % ethylbenzene based on the weight of C 6 -C 8 aromatic hydrocarbon in the aromatic formation effluent.

16. The method of claim 1 , further comprising:
separating a C 9+ intermediate stream from the aromatic formation effluent;
exposing at least a portion of the C 9+ intermediate stream to a transalkylation catalyst under effective transalkylation conditions to form a transalkylation effluent, the transalkylation effluent having C 8 aromatic hydrocarbon concentration (weight percent) that is great

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Salciccioli Michael
• Wood Glenn C

Classifications

• C07C15/08

  Xylenes · CPC title

• C07C5/2732

  Catalytic processes · CPC title

• C07C7/04

  by distillation · CPC title

• C07C15/04

  Benzene · CPC title

• C07C7/14

  by crystallisation; Purification or separation of the crystals · CPC title