Granted Patent B2

US 8,119,849 · App. 12/317,794 · Granted Feb 21, 2012

Abstract

Claims (16)

1. A process for producing propylene comprising

(a) reacting a feed stream comprising isobutene in the presence of a skeletal isomerization catalyst to obtain an isomerized stream of isobutene comprising C 4 olefins; and

(b) reacting the isomerized stream with ethylene in the presence of a metathesis catalyst to form a metathesis product stream comprising propylene, C 4 olefins, and C 5 and higher olefins;

wherein step (b) is performed at an equal or lower pressure than step (a).

2. The process of claim 1 wherein step (a) is performed at 20 to 60 psig.

3. The process of claim 2 wherein step (b) is performed at 20 to 60 psig.

4. The process of claim 1 wherein the feed stream comprises greater than 95 wt % of C 4 olefins.

5. The process of claim 1 wherein the feed stream is produced by dehydration of tert-butyl alcohol.

6. The process of claim 1 further comprising separating the metathesis product stream into an ethylene stream, a propylene product stream, a C 4 olefins stream, and C 5 and higher olefins stream.

7. The process of claim 6 wherein step (a) is performed at 20 to 60 psig.

8. The process of claim 7 wherein step (b) is performed at 20 to 60 psig.

9. The process of claim 6 wherein the ethylene stream is recycled to step (b).

10. The process of claim 6 wherein the C 4 olefins stream is recycled to step (a).

11. The process of claim 6 wherein the feed stream comprises greater than 95 wt % C 4 olefins.

12. The process of claim 6 wherein the feed stream is produced by dehydration of tert-butyl alcohol.

13. The process of claim 1 wherein heat integration of the process is reduced compared to a process where step (b) is performed at a higher pressure than step (a).

Assignments (14)