Chemical Engineering September 2014 - 45

1,4-Butanediol from
Bio-Succinic Acid
By Intratec Solutions
T
he compound 1,4-butanediol
(BDO) is a
versatile intermediate
for the chemical industry. Its
largest derivative product is
tetrahydrofuran (THF), which
is used to make spandex
fibers, resins, solvents and
printing inks. The second largest
product is polybutylene
terephthalate (PBT), which
is used to make high-performance
materials, electronics
and automotive equipment.
Biomass source unit
Sugarcane
Milling,
treatment and
sugar inversion
or
Corn
Milling and
saccharification
Water
Heavies
FIGURE 2. It is possible to integrate 1,4-butanediol and bio-succinic-acid production units
BDO can be produced from different technologies
and raw materials. The conventional
method for manufacturing BDO is the Reppe
process, starting from acetylene. Other processes
use propylene oxide, maleic anhydride,
1,3-butadiene or n-butane as starting points.
The newest technologies being developed for
BDO are bio-based pathways, which mostly
rely on bio-based succinic acid derived from
biomass or a sugar substrate.
Succinic acid is a platform chemical that can
be used to produce many products. However,
its high cost of production from petroleum raw
sources limits its use to specific applications
(such as pharmaceuticals and food additives).
According to the U.S. Dept. of Energy (DOE),
bio-succinic acid is a renewable building-block
chemical with great potential for the future.
The process
The process depicted in Figure 1 was compiled
based on a U.S. patent published by BioAmber
Inc. (Montreal, Canada; www.bio-amber.com;
U.S. patent no. 2011/0245515). The patent
discloses details about the initial reaction,
while the separation process was conceived by
Intratec and is based on well-known practices.
Hydrogenation reaction. A solution of biosuccinic
acid in water is pre-heated and sent to
the fixed-bed hydrogenation reactor. Hydrogen
is compressed and also fed in excess to the
reactor. The process uses a bimetallic catalyst
consisting of metals (including ruthenium, rhenium,
tin and others) on a carbon support.
The exothermic reaction product is mostly
BDO (selectivities to BDO of more than 90%
Hydrogen
are reported in literature). Side products include
THF, gamma-butyrolactone (GBL), and linear
alcohols (n-butanol, n-propanol). The amount
of each product depends on the catalyst and
operational conditions used.
The bio-succinic acid is totally reacted,
and the unreacted hydrogen is compressed
and recycled back to the reactor. The product
stream is cooled and sent to flash vessels to
recover unreacted hydrogen and eliminate
volatile materials.
Purification. The product from the flash vessels
is sent to a series of distillation columns to
separate BDO from side products. In the first
column, BDO, GBL and water are removed
from the bottoms and then sent to the drying
column, where most of the water is removed.
The column's top fraction is sent to a lights
column, to recover side-products as fuel.
The recovered water is sent to a tank for further
disposal or to be recycled to an integrated
bio-succinic acid production unit (see Figure
2). The drying column's bottoms are sent to a
BDO recovery column and further to a heavies
column, where a stream of 99.5 wt.% BDO is
finally achieved.
Economic performance
An economic evaluation of the process was
conducted based on data from the fourth quarter
of 2013. The following assumptions were
taken into consideration.
* A 55,000-ton/yr BDO production unit (the
process equipment is represented in Figure 1)
* Storage capacity equal to 20 days of operation
for BDO and no storage for bio-succinic
acid
CW
Lights
as fuel
1
ST
2
Bio-succinic acid in water
CW
9
ST
10
3
4
ST
6
ST
FIGURE 1. The 1,4-butanediol process from bio-succinic acid that is shown here
is based on patent disclosures from BioAmber and well-known practices
7
ST
8
ST
Heavies
CW Cooling water
ST Steam
CW
5
CW
ST
CW
CW
CW
Water for
disposal or
recycle
CW
BDO
The estimated capital investment (including
total fixed investment, working capital and
other capital expenses) to build a plant would
be $100 million in the U.S. Gulf Coast region
and $140 million in Brazil.
Process perspective
It may be an interesting consideration to
control the entire supply chain through the
integration of a bio-succinic-acid production
unit with a BDO unit (see Figure 2). Also, the
bio-BDO produced must include a premium
price over its petrochemical counterpart. Both
measures are important to make the venture
economically feasible.
In addition, it is also an important researchand-development
goal to find hydrogenation
catalysts that have the following qualities:
* Improved tolerance to impurities generated in
the fermentation process (that produces biosuccinic
acid). This can help reduce the costs
of bio-succinic acid purification
* Increased selectivity of bio-succinic acid to
BDO, reducing the formation of side products
and the costs with BDO purification
Both achievements can reduce investment and
production costs. n
Editor's Note: The content for this column is
supplied by Intratec Solutions LLC (Houston; www.
intratec.us) and edited by Chemical Engineering.
The analyses and models presented herein are
prepared on the basis of publicly available and
non-confidential information. The information and
analysis are the opinions of Intratec and do not
represent the point of view of any third parties.
More information about the methodology for
preparing this type of analysis can be found, along
with terms of use, at www.intratec.us/che.
Offgas
1 ) Hydrogenation reactor
2 ) High-pressure vessel
3 ) Low-pressure vessel
4 ) High-pressure column
5 ) Light-ends column
6 ) Drying column
7 ) BDO recovery column
8 ) Heavies column
9 ) Cooling tower
10) Boiler
Glucose Fermentation
Cell separation,
recovery and
purification
Biosuccinic
acid
Bio-succinic
acid unit
1,4-Butanediol unit
Hydrogen
Hydrogenation
reaction
Purification
Lights
BDO

http://www.bio-amber.com http://www.intratec.us http://www.intratec.us/che

Chemical Engineering September 2014

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