Chemical Engineering June 2018 - 41

Technology Profile
Sodium Lauryl Ether Sulfate Production
By Intratec Solutions
S
odium lauryl ether sulfate
(also known as SLES and
sodium laureth sulfate) is
a clear and viscous liquid
that is among the most important
anionic surfactants. On an industrial
scale, SLES is mainly produced by
the ethoxylation of dodecanol, followed
by the sulfation of the resulting
ethoxylate and neutralization to
the sodium salt.
Like other fatty alcohol sulfates
and fatty alcohol ether sulfates,
SLES has uses that are basically
related to its surface-active properties.
SLES molecules include both
hydrophilic and hydrophobic functional
groups. In fact, the possibility
of altering those properties allows
chemical processors to tailor these
compounds to be used in a broad
range of applications that demand
good activity (that is, foaming and
detergency),
stability over a wide
pH range, water solubility, chemical
compatibility and so on. With such
versatility, these chemicals are widely
used in cosmetic products and in industrial
cleaners.
The process
The following describes a process for
SLES production from chlorosulfonic
acid, lauryl ethoxylate and sodium
hydroxide. Figure 1 presents a simplified
flow diagram of the process.
Sulfation. Initially, the lauryl ethoxylate
is batch-sulfated by cholorosulfonic
acid. Both reagents are fed to a
glass-lined stirred, jacketed reactor,
with the acid being gradually added
ClSO3H, lauryl
ethoxylate,
NaOH
Sulfation
SLES
Oleum, lauryl
ethoxylate,
NaOH
Sulfation
n Raw material n Process n Main product
to the reaction. The sulfation is carried
out at 25-30°C under vacuum,
over about a period of 2.5 h. The
gaseous HCl byproduct is led off the
sulfation product, and directed to a
scrubber downstream. The sulfation
product is fed to the neutralization.
Neutralization. The sulfation product
is fed to a neutralization vessel,
where it is contacted with a 50 wt.%
caustic soda solution, along with
process water, for adjusting its active
component. The neutralization reaction
is carried out at a temperature
below 45°C, generating a 70 wt.%
sodium lauryl ether sulfate, which is
further routed to packaging.
Scrubbing. The HCl evolved during
the sulfation is fed to a scrubber,
where it is absorbed into process
water, generating a 33 wt.% hydrochloric
acid solution byproduct.
Packing. SLES is packed in drums
and then sent to warehouses for
storage outside the battery limits
(OSBL) of the facility.
Production pathways
SLES production is primarily based
on the sulfation of lauryl ethoxylate,
in such a way that different SLES
manufacturing routes are basically
Process water
3
Lauryl ethoxylate
Chlorosulfonic acid
1
Hydrochloric
acid solution
2
Caustic soda
Process water
FIGURE 1. The diagram shows a process for producing sodium lauryl ether sulfate (SLES)
40
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4
SLES
RW
ST
FIGURE 2. These pathways produce SLES
related to different sulfating agents
employed. Typically,
chlorosulfonic
acid, sulfur trioxide or oleum (SO3
* H2SO4) reagents are used for that
purpose. Figure 2 presents different
pathways for SLES production.
Economic performance
The total operating cost (raw materials,
utilities, fixed costs and depreciation
costs) estimated to produce
SLES was about $2,130 per ton of
SLES in the second quarter of 2014.
The analysis was based on a plant
constructed in the U.S. with the
capacity to produce 15,000 metric
tons per year of SLES.
This column is based on the report
" Sodium Lauryl Ether Sulfate Production
- Cost Analysis, " published by
Intratec. It can be found at the following
URL: www.intratec.us/analysis/
sles-e11a.
n
Edited by Scott Jenkins
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 are prepared on the basis of publicly available
and non-confidential information. The content represents
the opinions of Intratec only. More information about the
methodology for preparing analysis can be found, along with
terms of use, at www.intratec.us/che.
1. Sulfation reactor
2. Neutralization reactor
3. Scrubber
4. Packing
5. Chiller
6. Steam boiler
RW Refrigerated water
ST Steam
5
6
Sulfation
SO3, lauryl
ethoxylate,
NaOH
http://www.intratec.us/analysis/ http://www.intratec.us http://www.intratec.us/che http://WWW.CHEMENGONLINE.COM
Chemical Engineering June 2018

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