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US 11,691,933 B2Granted
Processes and systems for converting benzene and/or toluene via methylation
AssigneeExxonMobil Chemical Patents Inc.
InventorsSeth M. Washburn, Hsu Chiang, Catherine M. Dorsi, Tan-Jen Chen
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Abstract
This disclosure provides an improved process for converting benzene/toluene via methylation with methanol/dimethyl ether for producing, e.g., p-xylene, comprising separating and recycling dimethyl ether from the methylation reaction product mixture effluent to the methylation reactor. High selectivity toward p-xylene, among others, can be achieved.
Claims26
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 comprises 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, wherein (c) comprises:
- (c1) separating the methylation product mixture effluent to obtain an aqueous phase and an oil phase;
- and
- (c2) separating the oil phase to obtain the dimethyl ether-rich stream of (c) and an aromatics-rich stream comprising p-xylene and toluene;
- 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.
5 more elements
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),
- R
-
- (
- a
- /
- m
- )
- =
- M
-
- (
- tol
- )
- +
- 2
- ·
- M
-
- (
- bz
- )
- M
-
- (
- methanol
- )
- +
- 2
- ·
- M
-
- (
- DME
- )
- ,
- where M(tol) and M(hz) 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 comprises 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, wherein (III) comprises:
- (IIIa) separating the methylation product mixture effluent to obtain an aqueous phase and an oil phase;
- and
- (IIIb) separating the oil phase to obtain the dimethyl ether-rich stream of (III) and an aromatics-rich stream comprising p-xylene and toluene;
- and
- (IV) recycling at least a portion of the dimethyl ether-rich stream obtained in (IIIb) to (I) as at least a portion of the methylating agent feed.
41 more elements
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, wherein the separation subsystem comprises:
- (IIa) 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 first separation unit configured to separate the methylation product mixture effluent into the aqueous phase and the oil phase;
- and
- (IIb) a second separation unit comprising a distillation column having an inlet for receiving the oil phase, a first outlet for discharging the dimethyl ether-rich stream, and a second outlet for discharging an aromatics-rich stream;
- and
- (III) a first recycling channel connecting the first outlet of the distillation column 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.
4 more elements
Dependencies are inferred from the claim text.