Process for controlling the yield of an isomerization zone

Patent metadata

Field	Value
Publication number	US-9302957-B2
Application number	US-201414267742-A
Country	US
Kind code	B2
Filing date	May 1, 2014
Priority date	May 1, 2014
Publication date	Apr 5, 2016
Grant date	Apr 5, 2016

Abstract

A process for controlling a yield of an isomerization zone. Prior to entering the isomerization zone, C 6 cyclic hydrocarbons are removed from a feed stream. Disproportionation reaction selectivity is observed which produces valuable C 3 hydrocarbons and C 4 hydrocarbons. Also, a higher ring opening conversion of C 5 cyclic hydrocarbons is observed. The disproportionation reactions and the ring opening reactions may be selectively controlled by adjusting an amount of C 6 cyclic hydrocarbons passed into the isomerization zone.

First claim

What is claimed is:

1. A process for the isomerization of isoparaffins to normal paraffins, the process comprising:
separating a portion of C6 cyclic hydrocarbons from a naphtha stream comprising C5+hydrocarbons to provide a C6 cyclic hydrocarbons lean stream;
separating iC5 paraffinic hydrocarbons and iC6 paraffinic hydrocarbons from the C6 cyclic hydrocarbons lean stream; and,
passing a feed stream comprising at least one stream being rich in iC5 paraffinic hydrocarbons, iC6 paraffinic hydrocarbons, or both to an isomerization zone containing a chlorided alumina catalyst to isomerize isoparaffins to normal paraffins, disproportionate at least some isoparaffins, and ring open some cyclopentane; and,
controlling an amount of C6 cyclic hydrocarbons passed into the isomerization zone to from about 0.1 to about 5 wt. % of the feed stream by at least one of the following:
selectively adding a stream of C6 cyclic hydrocarbons to the isomerization zone; and,
controlling an operating parameter of a separation zone used to separate the C6 cyclic hydrocarbons from the naphtha stream.

2. The process of claim 1 wherein controlling the amount of C6 cyclic hydrocarbons passed into the isomerization zone comprises:
selectively adding a stream of C6 cyclic hydrocarbons to the isomerization zone; and,
controlling an operating parameter of a separation zone used to separate the C6 cyclic hydrocarbons from the naphtha stream.

3. The process of claim 1 further comprising:
passing the naphtha stream to a first separation zone; and,
separating the naphtha stream in the first separation zone into an overhead stream and a bottoms stream, the overhead stream being the C6 cyclic hydrocarbons lean stream and the bottoms stream being rich in n-hexane and C6 cyclic hydrocarbons.

4. The process of claim 3 further comprising:
passing the overhead stream from the first separation zone to a second separation zone; and,
separating the overhead stream from the first separation zone in the second separation zone into the at least one stream being rich in iC5 paraffinic hydrocarbons, iC6 paraffinic hydrocarbons, or both.

5. The process of claim 4 wherein the second separation zone comprises at least two separator columns and the process further comprises:
separating the overhead stream from the first separation zone in a first separator column of the second separation zone into an overhead stream, an intermediate stream, a bottoms stream,
the overhead stream from the first separator column of the second separation zone being rich in C5 hydrocarbons, and,
the intermediate stream of the first separator column of the second separation zone being rich in iC6 paraffinic hydrocarbons; and,
separating the overhead stream from the first separator column of the second separation zone in a second separator column of the second separation zone into an overhead stream and a bottoms stream,
the overhead stream of the second separator column of the second separation zone being rich in iC5 paraffinic hydrocarbons.

6. The process of claim 4 further comprising:
recovering a stream comprising n-pentane and n-hexane from the isomerization zone; and,
passing the stream comprising n-pentane and n-hexane to the first separator of the second separation zone.

7. The process of claim 4 wherein the second separation zone comprises at least one adsorption zone, and the process further comprises:
separating the overheads stream from the first separation zone in the at least one absorption zone into a first stream and a second stream,
the first stream being rich in iC5 paraffinic hydrocarbons and iC6 paraffinic hydrocarbons and,
the second stream being rich in n-pentane.

8. The process of claim 7 further comprising:
recovering a stream comprising n-pentane and n-hexane from the isomerization zone; and,
passing the stream comprising n-pentane and n-hexane to the first separation zone.

9. The process of claim 1 further comprising:
converting the C6 cyclic hydrocarbons to straight chain hydrocarbons in a ring opening reactor.

10. The process of claim 9 further comprising:
separating a reactor effluent from the ring opening reactor into a plurality of streams, at least one stream from the plurality of streams comprising n-pentane, iC5 hydrocarbons, n-hexane, and iC6 hydrocarbons;
combining the at least one stream from the plurality of streams comprising n-pentane, iC5paraffinic hydrocarbons, n-hexane, and iC6 paraffinic hydrocarbons with the C6 cyclic hydrocarbons lean stream; and,
adjusting an operating parameter of the ring opening reactor to adjust an amount of C6cyclic hydrocarbons combined with the C6 cyclic hydrocarbons lean stream.

11. The process of claim 1 further comprising:
recovering a C3−hydrocarbon stream from the isomerization zone.

12. The process of claim 11 further comprising:
recovering a second stream from the isomerization zone.

13. The process of claim 12 further comprising:
passing the second stream from the isomerization zone back to the second separation zone.

14. The process of claim 13 wherein the second separation zone comprises:
a plurality of separator columns.

15. The process of claim 12 further comprising:
passing the second stream from the isomerization reaction back to the first separation zone.

16. The process of claim 15 wherein the second separation zone comprises:
an adsorption zone.

17. The process of claim 16 wherein n-pentane and n-hexane are separated in an adsorption zone.

Assignees

• Uop Llc

Inventors

• Lapinski Mark P
• Lippmann Matthew
• Funk Gregory
• Shecterle David James
• Mokka Lakshmi P

Classifications

• C07C5/00

  Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms · CPC title

• C07C7/005 Primary

  Processes comprising at least two steps in series · CPC title

• C07C5/27

  Rearrangement of carbon atoms in the hydrocarbon skeleton · CPC title

• C07C4/06 Primary

  Catalytic processes {(C07C4/025 takes precedence)} · CPC title

• C07C7/04

  by distillation · CPC title