Process to control conversion of C4+ and heavier stream to lighter products in oxygenate conversion reactions

• US 6,444,868 B1
• Filed: 03/08/2000
• Issued: 09/03/2002
• Est. Priority Date: 02/17/1999
• Status: Expired due to Term

• Current Assignee: ExxonMobil Chemical Patents Inc. (Exxon Mobil Corporation)
• Original Assignee: ExxonMobil Chemical Patents Inc. (Exxon Mobil Corporation)
• Inventors: Ham, Peter G., Kuechler, Keith H., Vaughn, Stephen N.
• Primary Examiner(s): Dang, Thuan D.
• Application Number:
  US09/521,175
• Time in Patent Office: 909 Days
• Field of Search: 585/311, 585/312, 585/313, 585/324, 585/638, 585/634, 585/640
• US Class Current: 585/640
• CPC Class Codes: B01J 29/04 having base-exchange properties, e.g. crystalline zeolites B01J29/005 takes precedence
• CPC Class Codes: B01J 29/85 Silicoaluminophosphates [SAPO compounds]
• CPC Class Codes: B01J 29/90 Regeneration or reactivation
• CPC Class Codes: B01J 38/12 Treating with free oxygen-containing gas
• CPC Class Codes: C07C 1/20 starting from organic compounds containing only oxygen atoms as heteroatoms
• CPC Class Codes: C07C 11/02 Alkenes
• CPC Class Codes: C07C 2529/85 Silicoaluminophosphates (SAPO compounds)
• CPC Class Codes: C10G 2300/1088 Olefins
• CPC Class Codes: C10G 2300/4093 Catalyst stripping
• CPC Class Codes: C10G 2300/708 Coking aspect, coke content and composition of deposits
• CPC Class Codes: C10G 2400/20 C2-C4 olefins
• CPC Class Codes: C10G 3/49 containing crystalline aluminosilicates, e.g. molecular sieves
• CPC Class Codes: C10G 3/57 according to the fluidised bed technique
• CPC Class Codes: C10G 3/62 Catalyst regeneration
• CPC Class Codes: Y02P 20/584 Recycling of catalysts
• CPC Class Codes: Y02P 30/20 using bio-feedstock
• CPC Class Codes: Y02P 30/40 Ethylene production

Abstract

A method for converting heavy olefins present in a product stream exiting a first reaction zone into light olefins and carbonaceous deposits on a catalyst without separation of the heavy olefins from the product stream exiting the first reaction zone. The method comprises creating the product stream exiting the first reaction zone, the product stream exiting the first reaction zone comprising the heavy olefins, moving the product stream exiting the first reaction zone to a second reaction zone without separation of the heavy olefins from the product stream exiting the first reaction zone, and contacting the product stream exiting the first reaction zone with the catalyst under conditions effective to form the light olefins, the contacting causing the carbonaceous deposits to form on at least a portion of the catalyst.

Claims

1. A method for converting an oxygenate feedstock to an olefin product comprising:

contacting an oxygenate feedstock with silicoaluminophosphate catalysts in a first reaction zone of a reactor system under conditions effective to produce a first olefin product stream comprising light olefins and C₄⁺ olefins;

directing at least a portion of the catalysts from the first reaction zone and the first olefin product stream to a second reaction zone;

directing at least a portion of the catalysts in the second reaction zone to a regenerator;

regenerating the at least a portion of the catalysts in the regenerator to form regenerated catalysts;

directing the regenerated catalysts from the regenerator to the second reaction zone; and

contacting the first olefin product stream with at least a portion of the,regenerated catalysts in the second reaction zone of the reactor system wherein C₄⁺ olefins are converted to light olefins, thereby producing a final olefin product.

2. The method of claim 1, wherein the reactor system is a riser reactor.

3. The method of claim 2, wherein the olefin product stream from the first reaction zone comprises at least 50 wt. % light olefin.

4. The method of claim 3, wherein the olefin product stream from the first reaction zone comprises at least 55 wt. % light olefin.

5. The method of claim 4, wherein the olefin product stream from the first reaction zone comprises at least 60 wt. % light olefin.

6. The method of claim 2, wherein the oxygenate feedstock comprises at least 50 wt. % oxygenate.

7. The method of claim 2, wherein the olefin product stream from the first reaction zone comprises less than 50 wt. % C₄⁺ hydrocarbons.

8. The method of claim 7, wherein the olefin product stream from the first reaction zone comprises less than 40 wt. % C₄⁺ hydrocarbons.

9. The method of claim 8, wherein the olefin product stream from the first reaction zone comprises less than 30 wt. % C₄⁺ hydrocarbons.

10. The method of claim 2, wherein the catalysts directed to the second reaction zone have a coke content of less than 5 wt. %.

11. The method of claim 10, wherein the catalysts directed to the second reaction zone have a coke content of less than 2 wt. %.

12. The method of claim 11, wherein the catalysts directed to the second reaction zone have a coke content of less than 1.0 wt. %.

13. The method of claim 2, further comprising separating light olefins from the final olefin stream.

14. The method of claim 13, further comprising contacting at least a portion of the light olefin with a polyolefin-forming catalyst under conditions effective to form a polyolefin.

15. The method of claim 1, further comprising:

circulating at least a portion of the catalysts from the second reaction zone to the first reaction zone.

16. The method of claim 1, wherein the first and second reaction zones are in separate reactors.

17. The method of claim 1, wherein the first and second reaction zones are in the same reactor.

18. The method of claim 1, wherein the contacting occurs in a fluidized bed reactor including a riser region, and the second reaction zone is located at a point above the riser region.