Process for producing paraxylene by methylation of benzene and/or toluene

• US 10,246,383 B2
• Filed: 09/12/2017
• Issued: 04/02/2019
• Est. Priority Date: 10/06/2016
• Status: Active Grant

• Current Assignee: ExxonMobil Chemical Patents Inc. (Exxon Mobil Corporation)
• Original Assignee: ExxonMobil Chemical Patents Inc. (Exxon Mobil Corporation)
• Inventors: Chen, Tan-Jen, Washburn, Seth M.
• Primary Examiner(s): Dang, Thuan D
• Application Number:
  US15/702,337
• Publication Number:
  US 20180099913A1
• Time in Patent Office: 567 Days
• Field of Search: 585467, 585469
• CPC Class Codes: B01J 29/0308 Mesoporous materials not having base exchange properties, e.g. Si-MCM-41
• CPC Class Codes: B01J 29/70 of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
• CPC Class Codes: B01J 29/7038 MWW-type, e.g. MCM-22, ERB-1, ITQ-1, PSH-3 or SSZ-25
• CPC Class Codes: C07C 15/08 Xylenes
• CPC Class Codes: C07C 2/66 Catalytic processes
• CPC Class Codes: C07C 2/864 the non-hydrocarbon is an alcohol
• CPC Class Codes: C07C 2529/70 of types characterised by their specific structure not provided for in groups C07C2529/08 - C07C2529/65
• CPC Class Codes: Y02P 20/52 using catalysts, e.g. selective catalysts

Abstract

A process is described for producing paraxylene, in which an aromatic hydrocarbon feedstock comprising benzene and/or toluene is contacted with an alkylating reagent comprising methanol and/or dimethyl ether in an alkylation reaction zone under alkylation conditions in the presence of an alkylation catalyst to produce an alkylated aromatic product comprising xylenes. The alkylation catalyst comprises a molecular sieve having a Constraint Index ≤5, and the alkylation conditions comprise a temperature less than 500° C. Paraxylene may then be recovered from the alkylated aromatic product.

Claims

1. A process for producing paraxylene, the process comprising:

(a) selectivating an alkylation catalyst consisting essentially of MCM-49 zeolite and alumina binder by contacting the alkylation catalyst with a selectivating agent selected from the group consisting of silicon, steam, and a combination of silicon and steam;

(b) contacting an aromatic hydrocarbon feed comprising toluene with an alkylating reagent comprising methanol and/or dimethyl ether in at least one alkylation reaction zone in the presence of the alkylation catalyst under alkylation conditions comprising a temperature less than 500°

C. and a pressure of 700 kPa-a to 7000 kPa-a to produce an alkylated aromatic product comprising xylenes, wherein the at least one alkylation reaction zone comprises a fixed bed of the alkylation catalyst; and

(c) recovering paraxylene from the alkylated aromatic product.

2. The process of claim 1, wherein the aromatic hydrocarbon feed comprises at least 90 wt % toluene.

3. The process of claim 2, wherein the alkylating reagent comprises methanol.

4. The process of claim 3, wherein the alkylation conditions comprise a temperature of at least 250°

C.

5. The process of claim 4, wherein the alkylation conditions comprise a temperature from 250°

C. to 450°

C.

6. The process of claim 5, wherein the alkylation conditions comprise a pressure from 3000 kPa-a to 7000 kPa-a.

7. The process of claim 6, wherein the alkylation conditions comprise a weight hourly space velocity based on the aromatic hydrocarbon feed of 50 to 0.5 hr⁻

1.

8. The process of claim 7, wherein the alkylated aromatic product comprises at least 80 wt % xylenes.

9. The process of claim 1, wherein the alkylation conditions comprise a pressure in the range from 2,000 to 7,000 kPa-a.

10. The process of claim 1, wherein the alkylation conditions comprise a pressure in the range from 3,000 to 5,000 kPa-a.

11. The process of claim 1, wherein the alkylation conditions comprise a temperature in the range from 300 to 450°

C.

12. A process for producing paraxylene, the process comprising:

(a) selectivating an alkylation catalyst consisting essentially of MCM-49 zeolite and alumina binder by contacting the alkylation catalyst with a selectivating agent selected from the group consisting of silicon, steam, and a combination of silicon and steam;

(b) contacting an aromatic hydrocarbon feed comprising toluene with an alkylating reagent comprising methanol in at least one alkylation reaction zone in the presence of the alkylation catalyst under alkylation conditions comprising a temperature from about 250°

C. to less than about 500°

C. and a pressure of 700 kPa-a to 7000 kPa-a to produce an alkylated aromatic product comprising xylenes, wherein the at least one alkylation reaction zone comprises a fixed bed of the alkylation catalyst; and

(c) recovering paraxylene from the alkylated aromatic product.

13. The process of claim 12, wherein the aromatic hydrocarbon feed comprises at least 90 wt % toluene.

14. The process of claim 13, wherein the alkylation conditions comprise a temperature from 250°

C. to 450°

C.

15. The process of claim 14, wherein the alkylation conditions comprise a pressure from 3000 kPa-a to 7000 kPa-a.

16. The process of claim 15, wherein the alkylation conditions comprise a weight hourly space velocity based on the aromatic hydrocarbon feed of 50 to 0.5 hr⁻

1.

17. The process of claim 16, wherein the alkylated aromatic product comprises at least 80 wt % xylenes.

18. The process of claim 12, wherein the alkylation conditions comprise a pressure in the range from 2,000 to 7,000 kPa-a.

19. The process of claim 12, wherein the alkylation conditions comprise a pressure in the range from 3,000 to 5,000 kPa-a.

20. The process of claim 12, wherein the alkylation conditions comprise a temperature in the range from 300 to 450°

C.