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1. WO2020197888 - PROCESSES AND SYSTEMS FOR CONVERTING BENZENE AND/OR TOLUENE VIA METHYLATION

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[ EN ]

CLAIMS

What is claimed is:

1. A process for converting benzene and/or toluene, the process comprising:

(a) feeding an aromatic hydrocarbon feed and a methylating agent feed into a methylation reactor, wherein the aromatic hydrocarbon feed comprises benzene and/or toluene, and the methylating agent feed comprises methanol and/or dimethyl ether;

(b) contacting the aromatic hydrocarbon feed with the methylating agent feed in the presence of a methylation catalyst in the methylation reactor under methylation reaction conditions effective to produce a methylation product mixture effluent exiting the methylation reactor, wherein the methylation catalyst comprises a zeolite of the MWW framework type, and the methylation product mixture effluent comprise toluene, p-xylene, methanol, and dimethyl ether;

(c) obtaining a dimethyl ether-rich stream from at least a portion of the methylation product mixture effluent; and

(d) recycling at least a portion of the dimethyl ether-rich stream obtained in (c) to (a) as at least a portion of the methylating agent feed.

2. The process of claim 1, wherein in (a), the methylation catalyst is present in the methylation reactor in a fixed bed.

3. The process of claim 1 or claim 2, wherein in (b), the methylation reaction conditions comprise a temperature in a range from 200 to 500 °C, and an absolute pressure in the range from 100 to 8,500 kPa.

4. The process of claim 3, wherein in (b), the methylation reaction conditions comprise a temperature in a range from 250 to 400 °C.

5. The process of any of the preceding claims, wherein the molar ratio of the aromatic hydrocarbon feed to the methylating agent feed is R(a/m),

M(tol)+2-M(bz)

M(methanol)+2-M(DME)’

where M(tol) and M(bz) are the moles of toluene and benzene in the aromatic hydrocarbon feed, respectively, and M(methanol) and M(DME) are the moles of methanol and dimethyl ether in the methylating agent feed, respectively, and wherein 1 < R(a/m) < 5.

6. The process of claim 5, wherein 2 < R(a/m) < 4.

7. The process of any of the preceding claims, wherein in (b), the methylation reaction conditions comprise a weight hourly space velocity based on the total flow rate of the aromatic hydrocarbon feed and the methylating agent feed in a range from 0.5 to 50 hour1.

8. The process of claim 7, wherein in (b), the methylation reaction conditions comprise a weight hourly space velocity in a range from 5 to 10 hour1.

9. The process of any of the preceding claims, wherein (c) comprises:

(cl) separating the methylation product mixture effluent to obtain an aqueous phase and an oil phase;

(c2) separating the oil phase to obtain the dimethyl ether-rich stream of (c) and an aromatics-rich stream comprising p-xylene and toluene.

10. The process of claim 9, wherein (c2) comprises distilling the oil phase in a distillation column at an absolute overhead pressure in a range from 300 to 800 kPa.

11. The process of claim 9 or claim 10, wherein (c) further comprises:

(c3) separating the aromatics-rich stream to obtain a toluene-rich stream and a xylenes-rich stream; and

(c4) recycling at least a portion of the toluene-rich stream obtained in (c3) to (a) as at least a portion of the aromatic hydrocarbon feed.

12. The process of claim 9 or claim 10, wherein the xylenes-rich stream comprises at least 30 wt% of p-xylene, based on the total weight of all xylenes in the xylenes-rich stream.

13. The process of any of claims 9 to 12, further comprising:

(c5) distilling the aqueous phase to obtain a methanol-rich stream and a water-rich stream; and

(c6) recycling at least a portion of the methanol-rich stream obtained in (c5) to (a) as at least a portion of the methylating agent feed.

14. The process of any of the preceding claims, wherein the aromatic hydrocarbon feed comprises at least 90 wt% of toluene, based on the total weight of the aromatic hydrocarbon feed.

15. The process of any of the preceding claims, wherein the zeolite is selected from MCM-22, PSH-3, SSZ-25, ERB-1, ITQ-1, ITQ-2, MCM-36, MCM-49, MCM-56, EMM-10, EMM-12, EMM-13, UZM-8, UZM-8HS, UZM-37, UCB-3, and mixtures of two or more thereof.

16. The process of claim 15, wherein the zeolite is selected from MCM-22, MCM-49, MCM-56, and mixtures thereof.

17. A process for converting benzene and/or toluene, the process comprising:

(I) feeding an aromatic hydrocarbon feed and a methylating agent feed into a methylation reactor, wherein the aromatic hydrocarbon feed comprises benzene and/or toluene, and the methylating agent comprises methanol and/or dimethyl ether, wherein the molar ratio of the aromatic hydrocarbon feed to the methylating agent feed is R(a/m),

fa/m) M(methanol)+2-M(DME)’

where M(tol) and M(bz) are the moles of toluene and benzene in the aromatic hydrocarbon feed, respectively, and M(methanol) and M(DME) are the moles of methanol and dimethyl ether in the methylating agent feed, respectively, and wherein 1 < R(a/m) < 5 ;

(II) contacting the aromatic hydrocarbon feed with the methylating agent feed in the presence of a methylation catalyst in the methylation reactor under methylation reaction conditions effective to produce a methylation product mixture effluent exiting the methylation reactor, wherein the methylation catalyst comprises a zeolite, and the methylation product mixture effluent comprise toluene, p-xylene, methanol, and dimethyl ether;

(III) obtaining a dimethyl ether-rich stream from at least a portion of the methylation product mixture effluent; and

(IV) recycling at least a portion of the dimethyl ether-rich stream obtained in (c) to (a) as at least a portion of the methylating agent feed.

18. The process of claim 17, wherein the methylation reaction conditions comprise a weight hourly space velocity based on the total flow rate of the aromatic hydrocarbon feed and the methylating agent feed is in a range from 5 to 10 hour1.

19. The process of claim 17 or claim 18, wherein 2 < R( a/m) < 4.

20. The process of any of claims 17 to 19, wherein the zeolite is a MWW framework type zeolite.

21. The process of any of claims 17 to 20, wherein the methylation catalyst is present in a fixed bed, and the methylation reaction conditions comprise a temperature in a range from 200 to 500 °C, and an absolute pressure in the range from 100 to 8,500 kPa.

22. A system for converting benzene and/or toluene to xylenes, comprising:

(I) a methylation reactor adapted for receiving a methylation catalyst comprising a zeolite of the MWW framework type comprising at least one reactor inlet adapted for receiving an aromatic hydrocarbon feed and a methylating agent feed and a reactor outlet adapted for discharging a methylation product mixture effluent comprising xylenes, methanol, and dimethyl ether, the methylation reactor further configured to allow contacting the aromatic hydrocarbon feed and the methylating agent feed with the methylation catalyst under methylation reaction conditions effective to produce the methylation product mixture effluent;

(II) a separation subsystem in fluid communication with the reactor outlet adapted for obtaining from the methylation product mixture effluent a dimethyl ether-rich stream; and

(III) a first recycling channel connecting the separation subsystem and the at least one reactor inlet of the methylation reactor, the first recycling channel adapted for recycling at least a portion of the dimethyl ether-rich stream to the methylation reactor.

23. The system of claim 22, wherein the separation subsystem in (II) comprises:

(Ila) a first separation unit comprising an inlet for receiving the methylation product mixture effluent, an outlet for discharging an aqueous phase, and an outlet for discharging an oil phase, the separation unit configured to separate the methylation product mixture effluent to the aqueous phase and the oil phase; and

(Ilb) a second separation unit comprising an inlet for receiving the oil phase, an first outlet for discharging the dimethyl ether-rich stream, and a second outlet for discharging an aromatics-rich stream.

24. The system of claim 22 or claim 23, wherein the separation subsystem further comprises:

(He) a third separation unit comprising an inlet for receiving the aromatics-rich stream, a first outlet for discharging a toluene -rich stream, and a second outlet for discharging a xylenes-rich stream; and

(lid) a second recycling channel connecting the lower outlet in (He) and the at least one reactor inlet of the methylation reactor, the second recycling channel adapted for recycling at least a portion of the toluene-rich stream to the methylation reactor.

25. The system of claim 23 or claim 24, wherein the separation subsystem further comprises:

(He) a fourth separation unit in fluid communication with the first separation unit, comprising an inlet for receiving the aqueous phase, an first outlet for discharging a methanol-rich stream, and a second outlet for discharging a water-rich stream; and

(Ilf) a third recycling channel connecting the fourth separation unit and the at least one inlet of the methylation reactor, the third recycling channel configured to recycle at least a portion of the methanol-rich stream to the methylation reactor.