Chemical Engineering October 2019 - 30

Technology Profile
Production of 2-propylheptanol
By Intratec Solutions
A
lso known as 2-PH and
2-propylheptyl alcohol,
2-propylheptanol is a
branched fatty alcohol,
primarily used in the production of
plasticizers and surfactants applied
in detergents or industrial cleaning
agents, as well as in the manufacture
of lubricants and acrylates in adhesives
applications.
This fatty alcohol is produced at
commercial scale mainly by the hydroformylation
of n-butenes to aldehyde
(oxo synthesis), followed by aldol
condensation and hydrogenation
steps. In the process under analysis,
2-propylheptanol is produced from
butenes and synthesis gas (syngas).
The process examined is similar
to the LP Oxo technology jointly licensed
by Johnson Matthey Davy
(London, U.K.; www.matthey.com)
and Dow Chemical (Midland, Mich.;
www.dow.com).
The process
The process comprises three major
sections: hydroformylation; aldolization;
and hydrogenation (Figure 1).
Hydroformylation. Syngas and
raffinate-2 (C4 residual containing
butenes and butane) are purified in
order to protect the biophosphitemodified
rhodium catalyst. A stirredtank
reactor receives the raw material
feed and a catalyst solution. The
butylenes react with carbon monoxide
and hydrogen at mild temperatures
and low pressures, yielding
valeraldehyde. The crude reaction
product is fed to a degasser, where
dissolved lights vaporize. The vapor
stream is mixed with reactor vent
gases and is recycled to the reac1
Syngas
2
Raffinate-2
Rhodium
catalyst
3
5
7
6
Heavy
impurities
2-Propylheptanol
FIGURE
1. The diagram shows the production of 2-propylheptanol via Oxo synthesis
30
ST
CW
12
11
Light ends
4
8
9
10
Wastewater
Naphtha, syngas,
hydrogen
Steam cracking/
hydroformulation/
cond./hydrog.
Ethylene, propylene,
pyrolysis gas,
fuel
Valeraldehydes,
hydrogen
Condensation/
hydrogenation
(cond./hydrog.)
n Raw material n Process n Main product n Byproducts
FIGURE 2. Several production pathways exist for 2-propylheptanol
tor after pressurization. The liquid is
heated in a vaporizer and then fed
to a flash vessel, where a concentrated
catalyst solution is separated
from a vapor phase containing hydroformylation
products and remaining
reactants.
Aldolization. The vapor stream from
the flash vessel is freed from residual
butenes and butanes (which are sold
as fuel). The resulting valeraldehyderich
liquid is fed to a stirred tank
along with a caustic soda solution
catalyst. An aldolization reaction occurs,
yielding 2-propyl-2-heptenal
and water. The effluent is sent to a
reactive column, which strips off light
ends and unreacted valeraldehyde
from the reactor effluent. In a decanter,
the liquid stream is separated into
caustic soda solution and 2-propyl2-heptenal.
Hydrogenation.
The 2-propyl2-heptenal
solution is distilled from
heavy ends, which are separated
from the 2-propyl-2-heptenal stream
in the column bottom. The overhead
outlet is condensed and is submitted
to a liquid-phase hydrogenation
in two steps, carried out over heterogeneous
catalysts, yielding 2-propylheptanol.
The products are then
submitted to a fractional distillation
step, in which pure 2-propylheptanol
is separated from light-ends and
other impurities.
Production pathways
Commercial production of 2-propylheptanol
is based on valeraldehyde
raw material, in such a way that different
manufacturing routes are related
to different sources of such raw
material. Valeraldehyde, in turn, is
obtained primarily from butylenes via
oxo processes. Different pathways
for 2-propylheptanol production are
presented in Figure 2.
Economic performance
The total operating cost (raw materials,
utilities, fixed costs and depreciation
costs) estimated to produce
2-propylheptanol was about $850
per ton of 2-propylheptanol in the
fourth quarter of 2015. The analysis
was based on a plant constructed
in the U.S. with the capacity to produce
120,000 metric ton per year of
2-propylheptanol.
This column is based on " 2-Propylheptanol
Production Process -
Cost Analysis, " a report published
by Intratec. It can be found at: www.
intratec.us/analysis/2-propylheptanol-production-cost.
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.
Purge gas
1. Hydroformylation
2. Aldehydes vaporization
3. Impurities stripper
4. Condensation reactor
5. Reactive column
6. Caustic removal
7. Distillation column
8. Condensator
9. Hydrogenation reactors
10. Product column
11. Cooling tower
12. Steam boiler
CW Cooling water
ST Steam
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
OCTOBER 2019
2-PH
Hydroformulation/
cond./hydrog.
Raffinate-2,
syngas,
hydrogen
http://www.matthey.com http://www.dow.com http://www.intratec.us/analysis/2-propylhepta http://www.intratec.us http://www.intratec.us/che http://WWW.CHEMENGONLINE.COM
Chemical Engineering October 2019

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