Process for the production of high purity isobutylene

Patent metadata

Field	Value
Publication number	US-11053177-B2
Application number	US-201916549804-A
Country	US
Kind code	B2
Filing date	Aug 23, 2019
Priority date	Aug 23, 2018
Publication date	Jul 6, 2021
Grant date	Jul 6, 2021

Abstract

Processes for the production of high purity isobutylene are disclosed. The processes may include supplying a mixed C4 feed stream to a catalytic distillation column, which may contain a butene isomerization catalyst. 1-butene is isomerized to 2-butene and concurrently in the catalytic distillation column the 2-butene is separated from the isobutane and isobutylene. The overheads fraction comprising the isobutane and isobutylene is then condensed in an overheads system and fed to a splitter, where the isobutane is separated from the isobutylene. The process further includes operating the catalytic distillation column at an overheads temperature greater than a bottoms temperature of the splitter, and heating a portion of the splitter bottoms stream via indirect heat exchange with at least a portion of the catalytic distillation column overheads fraction, thereby producing a heated bottoms stream (reboil vapor) fed to the splitter and a cooled overheads fraction.

First claim

What is claimed:

1. A process for the production of high purity isobutylene, comprising:
supplying a mixed C4 feed stream, comprising isobutylene, isobutane, and 1-butene, and optionally comprising one or more of butadiene, 2-butene, or n-butanes, to a catalytic distillation column containing a butene isomerization catalyst;
in the catalytic distillation column, concurrently isomerizing 1-butene to 2-butene and separating the 2-butene from the isobutane and isobutylene;
recovering the 2-butene from the catalytic distillation column as a bottoms stream;
recovering an overheads fraction comprising the isobutane and isobutylene from the catalytic distillation column;
condensing the overheads fraction comprising the isobutane and isobutylene in an overheads system comprising at least one condenser;
feeding at least a portion of the condensed overheads fraction to a splitter and separating the isobutane from the isobutylene in the splitter;
recovering a bottoms stream from the splitter comprising the isobutylene; and
recovering an overheads stream from the splitter comprising the isobutane;
wherein the process further comprises:
operating the catalytic distillation column at an overheads temperature greater than a bottoms temperature of the splitter; and
heating a portion of the splitter bottoms stream via indirect heat exchange with at least a portion of the catalytic distillation column overheads fraction, producing a heated bottoms stream fed to a lower portion of the splitter and a cooled overheads fraction; and
feeding the cooled overheads stream via at least one flow line to the overheads system.

2. The process of claim 1 , further comprising an accumulator for receiving the cooled overheads stream, and wherein the at least one flow line for feeding the cooled overheads stream to the overheads system comprises a first flow line and a second flow line, the process further comprising:
feeding a vapor portion of the cooled overhead stream via the first flow line from the accumulator to the overheads system; and
feeding a liquid portion of the cooled overhead stream via the second flow line from the accumulator to the overheads system.

3. The process of claim 1 , further comprising:
heating a second portion of the splitter bottoms stream via indirect heat exchange with at least a portion of the catalytic distillation column bottoms fraction, producing a heated splitter bottoms stream fed to a lower portion of the splitter and a cooled 2-butene fraction.

4. The process of claim 1 , wherein the catalytic distillation column is operated at an overheads temperature in the range from about 42° C. to about 138° C.

5. The process of claim 1 , wherein the catalytic distillation column is operated at an overheads temperature in the range from about 85° C. to about 138° C.

6. The process of claim 1 , wherein the catalytic distillation column is operated at an overheads temperature in the range from about 60° C. to about 65° C.

7. A process for the production of high purity isobutylene, comprising:
supplying a mixed C4 feed stream, comprising isobutylene, isobutane, and 1-butene, and optionally comprising one or more of butadiene, 2-butene, or n-butanes, to a catalytic distillation column containing a butene isomerization catalyst;
in the catalytic distillation column, concurrently isomerizing 1-butene to 2-butene and separating the 2-butene from the isobutane and isobutylene;
recovering the 2-butene from the catalytic distillation column as a bottoms stream;
recovering an overheads fraction comprising the isobutane and isobutylene from the catalytic distillation column;
condensing the overheads fraction comprising the isobutane and isobutylene in an overheads system comprising at least one condenser;
feeding at least a portion of the condensed overheads fraction to a splitter and separating the isobutane from the isobutylene in the splitter;
recovering a bottoms stream from the splitter comprising the isobutylene; and
recovering an overheads stream from the splitter comprising the isobutane;
wherein the process further comprises:
operating the catalytic distillation column at an overheads temperature of greater than 60° C.;
operating the splitter at a bottoms temperature of less than 55° C.; and
heating a portion of the splitter bottoms stream via indirect heat exchange with at least a portion of the catalytic distillation column overheads fraction, producing a heated bottoms stream fed to a lower portion of the splitter and a cooled overheads fraction; and
feeding the cooled overheads stream via at least one flow line to the overheads system.

8. The process of claim 7 , further comprising an accumulator for receiving the cooled overheads stream, and wherein the at least one flow line for feeding the cooled overheads stream to the overheads system comprises a first flow line and a second flow line, the process further comprising:
feeding a vapor portion of the cooled overhead stream via the first flow line from the accumulator to the overheads system; and
feeding a liquid portion of the cooled overhead stream via the second flow line from the accumulator to the overheads system.

9. The process of claim 7 , further comprising:
heating a second portion of the splitter bottoms stream via indirect heat exchange with at least a portion of the catalytic distillation column bottoms fraction, producing a heated splitter bottoms stream fed to a lower portion of the splitter and a cooled 2-butene fraction.

10. The process of claim 7 , wherein the catalytic distillation column is operated at an overheads temperature of greater than 85° C.

Assignees

• Lummus Technology Inc

Inventors

• Almering Martinus Johannes
• Robbins Christopher

Classifications

• Y02P20/10

  Process efficiency · CPC title

• C07C11/09 Primary

  Isobutene · CPC title

• C07C7/20

  Use of additives, e.g. for stabilisation · CPC title

• C07C7/09

  by fractional condensation · CPC title

• C07C7/04 Primary

  by distillation · CPC title