Processes for converting aromatic hydrocarbons via alkyl-demethylation

Patent metadata

Field	Value
Publication number	US-11198659-B2
Application number	US-202016903009-A
Country	US
Kind code	B2
Filing date	Jun 16, 2020
Priority date	Jul 19, 2019
Publication date	Dec 14, 2021
Grant date	Dec 14, 2021

Abstract

Alkyl-demethylation of C2+-hydrocarbyl substituted aromatic hydrocarbons can be utilized to treat one or more of a heavy naphtha reformate stream, a hydrotreated SCN stream, a C8 aromatic hydrocarbon isomerization feed stream, a C9+ aromatic hydrocarbon transalkylation feed stream, and similar hydrocarbon streams to produce additional quantity of xylene products.

First claim

What is claimed is:

1. A process for making xylenes, the process comprising:
(I) providing a C6+ aromatic hydrocarbon-containing stream comprising a C2+-hydrocarbyl-substituted aromatic hydrocarbon, wherein the C2+-hydrocarbyl-substituted aromatic hydrocarbon has (i) a C2+ alkyl substitute attached to an aromatic ring therein and/or (ii) an aliphatic ring annelated to an aromatic ring therein;
(II) optionally contacting the C6+ aromatic hydrocarbon-containing stream with a first alkyl-demethylation catalyst in a first alkyl-demethylation zone under a first set of alkyl-demethylation conditions to convert at least a portion of the C2+-hydrocarbyl-substituted aromatic hydrocarbon to an alkyl-demethylated aromatic hydrocarbon to obtain an optional first alkyl-demethylated effluent exiting the first alkyl-demethylation zone;
(III) separating at least a portion of the C6+ aromatic hydrocarbon-containing stream and/or the first alkyl-demethylated effluent in a first separation apparatus to obtain a C6-C7 hydrocarbons-rich stream and a first C8+ aromatic hydrocarbons-rich stream;
(IV) optionally contacting the first C8+ aromatic hydrocarbons-rich stream with a second alkyl-demethylation catalyst in a second alkyl-demethylation zone under a second set of alkyl-demethylation conditions to convert at least a portion of the C2+-hydrocarbyl-substituted aromatic hydrocarbon, if any, contained in the first C8+ aromatic hydrocarbons-rich stream to an alkyl-demethylated aromatic hydrocarbon to obtain an optional second alkyl-demethylated effluent exiting the second alkyl-demethylation zone;
(V) separating at least a portion of the first C8+ aromatic hydrocarbons-rich stream and/or the second alkyl-demethylated effluent in a second separation apparatus to obtain a xylenes-rich stream and a C9+ aromatic hydrocarbons-rich stream; and
(VI) optionally separating the xylenes-rich stream in a first p-xylene recovery sub-system to obtain a first p-xylene product stream and a first p-xylene depleted stream;
wherein at least one of steps (II) and (IV) is carried out.

2. The process of claim 1 , wherein the C2+-hydrocarbyl substituted aromatic hydrocarbon has a total concentration in a range from 2 to 70 wt %, based on the total weight of the C6+ aromatic hydrocarbons contained in the C6+ aromatic hydrocarbon-containing stream.

3. The process of claim 1 , wherein step (VI) is carried out, and the process further comprises:
(VII) optionally contacting at least a portion of the first p-xylene-depleted stream with a third alkyl-demethylation catalyst in a third alkyl-demethylation zone under a third set of alkyl-demethylation conditions to convert at least a portion of the C2+-hydrocarbyl-substituted aromatic hydrocarbon, if any, contained in the first p-xylene-depleted stream to an alkyl-demethylated aromatic hydrocarbon to obtain an optional third alkyl-demethylated effluent exiting the third alkyl-demethylation zone;
(VIII) contacting at least a portion of the first p-xylene-depleted stream and/or at least a portion of the third alkyl-demethylated effluent with an isomerization catalyst in a first isomerization zone under isomerization conditions to produce a first isomerization effluent exiting the first isomerization zone comprising p-xylene at a concentration higher than the first p-xylene-depleted stream; and
(IX) separating at least a portion of the first isomerization effluent in a second p-xylene recovery sub-system to obtain a second p-xylene product stream and a second p-xylene depleted stream.

4. The process of claim 3 , wherein step (VII) is carried out, and the first isomerization zone is downstream of the third alkyl-demethylation zone, or the first isomerization zone at least partly overlaps with the third alkyl-demethylation zone.

5. The process of claim 4 , further comprising:
(VIIIa) contacting at least a portion of the first p-xylene-depleted stream and/or at least a portion of the third alkyl-demethylated effluent with a fourth alkyl-demethylation catalyst in the first isomerization zone under a fourth set of alkyl-demethylation conditions to convert at least a portion of the C2+-hydrocarbyl-substituted aromatic hydrocarbon, if any, contained in the first p-xylene-depleted stream and/or the third alkyl-demethylated effluent to an alkyl-demethylated aromatic hydrocarbon.

6. The process of claim 3 , wherein liquid-phase isomerization is conducted in the first isomerization zone.

7. The process of claim 6 , wherein in step (VIII), substantially all of the third alkyl-demethylated effluent is fed to the first isomerization zone.

8. The process of claim 1 , further comprising:
(X) optionally contacting at least a portion of the C9+ aromatic hydrocarbons-rich stream with a fifth alkyl-demethylation catalyst in a fifth alkyl-demethylation zone under a fifth set of alkyl-demethylation conditions to convert at least a portion of the C2+-hydrocarbyl-substituted aromatic hydrocarbon, if any, contained in the C9+ aromatic hydrocarbons-rich stream to an alkyl-demethylated hydrocarbon to produce a fifth alkyl-demethylated effluent exiting the fifth alkyl-demethylation zone;
(XI) optionally separating the C9+ aromatic hydrocarbons-rich stream and/or the fifth alkyl-demethylated effluent in a third separation apparatus to obtain a C9-C10 aromatic hydrocarbons-rich stream and a C11+ aromatic hydrocarbons-rich stream;
(XII) optionally contacting at least a portion of the C9+ aromatic hydrocarbon stream, and/or at least a portion of the fifth alkyl-demethylated effluent, and/or at least a portion of the C9-C10 aromatic hydrocarbons-rich stream with a sixth alkyl-demethylation catalyst in a sixth alkyl-demethylation zone under a sixth set of alkyl-demethylation conditions to convert at least a portion of the C2+-hydrocarbyl-substituted aromatic hydrocarbon, if any, contained in the C9+ aromatic hydrocarbon stream, and/or the fifth alkyl-demethylated effluent, and/or the C9-C10 aromatic hydrocarbons-rich stream to an alkyl-demethylated hydrocarbon to produce a sixth alkyl-demethylated effluent exiting the sixth alkyl-demethylation zone;
(XIII) feeding at least a portion of the C9+ aromatic hydrocarbons-rich stream, and/or at least a portion of the fifth alkyl-demethylated effluent, and/or at least a portion of the C9-C10 aromatic hydrocarbons-rich stream, and/or at least a portion of the sixth alkyl-demethylated effluent, and optionally a benzene/toluene stream to a transalkylation zone;
(XIV) contacting C9+ aromatic hydrocarbons with benzene/toluene in the presence of a transalkylation catalyst under transalkylation conditions to produce a transalkylation effluent exiting the transalkylation zone; and
(XV) separating the transalkylation effluent in a fourth separation apparatus to obtain an optional first benzene product stream, a toluene-rich stream, and a second C8+ aromatic hydrocarbons-rich stream.

9. The process of claim 8 , further comprising:
(XVI) feeding the second C8+ aromatic hydrocarbons-rich stream, along with the first C8+ aromatic hydrocarbons-rich stream, to the second separation apparatus.

10. The process of claim 8 , further comprising:
(XVII) feeding at least a portion of the first benzene product stream and/or at least a portion of the toluene-rich stream to the transalkylation zone as at least a portion of the benzene/toluene stream.

11. The process of claim 8 , wherein the sixth alkyl-demethylation zone is upstream of the transalkylation zone or at least partly overlaps with the transalkylation zone.

12. The process of claim 1 , further comprising:
(XVIII) obtaining a first C6-C7 aromatic hydrocarbons-rich stream from the C6-C7 hydrocarbons-rich stream; and
(XIX) sepa

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Nair Hari
• Rungta Meha
• Molinier Michel
• Levin Doron
• Weigel Scott J
• Salciccioli Michael
• Brody John F

Classifications

• C07C5/2791

  with metals · CPC title

• C07C2523/36

  Rhenium · CPC title

• C07C2523/63

  with rare earths or actinides · CPC title

• C07C2523/46

  Ruthenium, rhodium, osmium or iridium · CPC title

• C07C4/18 Primary

  Catalytic processes · CPC title