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ButamerTM Process

Refining

Background

The petroleum industry has witnessed a significant

shift to environmentally superior gasoline blending

components. Motor fuel alkylate is one blending

component that has seen a substantial increase in

demand because of its paraffinic, high octane, low

vapor pressure blending properties. Isobutane is a

primary feedstock for producing motor fuel alkylate.

The widely used Butamer process is a high-efficiency,

cost effective means of meeting the demands for the

production of isobutane by isomerizing normalbutane (nC4) to isobutane (iC4).

The Butamer process has reliably served as the

primary technology for isobutane production since

1959. A continuous development program aimed at

design, operating, and catalyst improvements has

kept this process a state-of-the-art technology.

Process description

The Butamer process is a fixed-bed catalytic process

that uses high-activity chloride-promoted catalysts

to isomerize normal butane to isobutane. The reac-tion is equilibrium limited, and the production of

isobutane is favored by lower temperature (Figure 1).

Highactivity, chlorided-alumina catalysts, such as

I-12TM catalyst and I-120TM catalyst, are used in the

Butamer process. These catalysts are capable of

converting normal butane to isobutane with a close

approach to equilibrium. Volumetric selectivity to

iC4 exceeds 99%.

In almost all applications, unconverted normal

butane is recycled to extinction through the use of

a deisobutanizer column (DIB) or an isostripper

column associated with an alkylation unit.

UOPs innovative hydrogen-once-through (HOT)Butamer process flow scheme (Figure 2) results in

substantial savings in capital equipment and utility

costs by eliminating the need for a product separa-

tor or recycle gas compressor.

Typically, two reactors in series flow are used toachieve high on-stream efficiency. The catalyst can

be replaced in one reactor while operation continues

in the other. The stabilizer separates the light gas

from the reactor effluent.

Because of the dry operating environment, Butamer

units use carbon steel construction, even though HCl

is present.

200(93)

300(149)

400(204)

500(260)

600(316)

100

80

60

40

20

0

iC4

/TotalC4,

mol-%

Isobuta

ne/Butanes,

mol-%

Temperature, F(C)

Gas to Scrubbingand Fuel

Isomerate

Stabilizer

n-Butane

MakeupHydrogen

Reactor

Charge Heater

Dryer

Dryer

Isobutane EquilibriumFigure 1

Isobutane EquilibriumFigure 2

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Butamer Process 2

A Butamer unit can be integrated with an alkylation

unit (Figure 3). In this application, the Butamer unit

feed is a side-cut from an isostripper column, and

the stabilized isomerate is returned to the isostripper

column. Unconverted normal butane is recycled to

the Butamer unit, along with normal butane from

the fresh feed. Virtually complete conversion ofnormal butane to isobutane can be achieved.

Feed stocks

The best feeds for a Butamer unit contain the highest

practical normal butane content, and only small

amounts of isobutane, pentanes, and heavier material.

Natural gas liquids (NGL) from a UOP NGL recovery

unit can be processed in a Butamer unit. To provide

a feed that is rich in normal butane, streams with

large amounts of isobutane or pentanes should be

processed first through an isostripper or DIB column.

Process performance

The stabilized isomerate is a near-equilibrium mixture

of isobutane and normal butane with small amounts

of heavier material. The light-ends yield from cracking

is less than 1 wt-% of the butane feed.

Experience

More than 70 Butamer units have been commis-sioned, and additional units are in design or

construction. Butamer unit feed capacities range

from 800 to more than 35,000 BPSD (74 to 3,250 T/D).

For more information

Butamer technological services are available on

request. For more information, contact your local

UOP representative or our Des Plaines sales office:

e-mail: info@uop.com

fax: +1-847-391-2253

phone: +1-847-391-2000

OlefinFeed

Saturated Butanes

Alkylate

Light Ends

H2

iC4

ButamerUnit

Isostripper

LPG

nC4

Isomerate

Alkylation

ReactorSection

Alkylation process-ButamerProcess Integration

Figure 3

2007 UOP LLC. All rights reserved.The information in this document should not be construed as a representation forwhich UOP assumes legal responsibility, or an authorization or recommendation

to practice a patented invention without a license.UOP 4523-4 0407R0X

UOP LLC

25 East Algonquin Road

Des Plaines, IL 60017-5017

U.S.A.www.uop.com