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

• US 10,246,387 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
• Primary Examiner(s): Dang, Thuan D
• Application Number:
  US15/702,469
• Publication Number:
  US 20180099915A1
• 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 15/04 Benzene
• CPC Class Codes: C07C 15/06 Toluene
• CPC Class Codes: C07C 15/08 Xylenes
• 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. The alkylation catalyst may be selectivated to produce a higher than equilibrium amount of paraxylene by using a molar ratio of alkylating agent to aromatic of at least 1:4.

Claims

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

(a) selectivating an alkylation catalyst consisting essentially of MCM-49 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 benzene and/or 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. to produce an alkylated aromatic product comprising xylenes;

wherein the molar ratio of the alkylating reagent to benzene and/or toluene of at least 1;

4 is used at least until the amount of paraxylene as a percentage of the total xylenes produced is equal to or greater than 23 wt. %; and

(b) recovering paraxylene from the alkylated aromatic product.

2. The process of claim 1, wherein the amount of paraxylene as a percentage of the total xylenes produced is at least 35 wt % of paraxylene, based on the total amount of xylenes.

3. The process of claim 1, wherein the molar ratio of the alkylating reagent to benzene and/or toluene is 1:

2.

4. The process of claim 3, wherein the aromatic hydrocarbon feed comprises toluene.

5. The process of claim 4, wherein the aromatic hydrocarbon feed comprises at least 90 wt % toluene.

6. The process of claim 5, wherein the alkylating reagent comprises methanol.

7. The process of claim 6, wherein the alkylation conditions comprise a temperature of at least 250°

C.

8. The process of claim 7, wherein the alkylation conditions comprise a temperature from 300°

C. to 450°

C.

9. The process of claim 8, wherein the alkylation conditions comprise a pressure from 700 kPa-a to 7000 kPa-a.

10. The process of claim 9, wherein the alkylation conditions comprise a weight hourly space velocity based on the aromatic hydrocarbon feed of 50 to 0.5 hr⁻

1.

11. The process of claim 10, wherein the alkylated aromatic product comprises at least 70 wt % xylenes.

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

13. The process of claim 1, wherein the alkylation conditions comprise a pressure in the range from 2,000 to 5,000 kPa-a.

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