Chemical Engineering August 2020 - 16

Technology Profile
Cumene Production from Benzene
By Intratec Solutions
C
umene (also known as isopropylbenzene)
is an organic
compound of the aromatic
hydrocarbon class.
It is a colorless liquid, insoluble in
water, but soluble in most organic
solvents. The production of cumene
grew rapidly during World War II,
when this aromatic compound was
used as a component of aviation fuel.
Today, cumene is mainly employed
as an organic solvent in pharmaceutical
manufacturing and as a flow-control
agent for thermoplastic elastomer
processing. Cumene derivatives
(mainly phenol, acetone, and methyl
styrene) are compounds with many
chemical and industrial uses. Currently,
the production of cumene is
largely associated with the demand
for phenol and phenol derivatives.
The process
The present analysis discusses an industrial
process for cumene production.
The process has two main sections:
(1) reaction; and (2) distillation.
Reaction. In the reaction section,
there are two reactors: the alkylation
reactor and the transalkylation reactor.
Fresh refinery-grade (RG) propylene
and recycled benzene are mixed and
fed to the alkylation reactor. In addition
to the cumene product, the alkylation
reactor effluent comprises unreacted
benzene, non-reactive propane (present
in the propylene feed), side products
polyisopropylebenzenes (PIPB)
and heavy ends. The effluent is routed
to the depropanizer column in the
distillation section. The transalkylation
reactor, in turn, is fed with recycled
Benzene
RG Propylene
Benzene, RG
propylene
Alkylation
Steam cracking,
extraction/
alkylation
Propane
Propane,
benzene
Dehydrogenation,
alkylation
FIGURE 2. Multiple pathways exist for cumene production
benzene and PIPB recovered in the
distillation section. In the transalkylation
reaction, PIPBs are reacted with
benzene to form cumene. The transalkylation
reactor effluent is routed to the
benzene recovery column in the distillation
section.
Distillation. In the distillation section,
a depropanizer column removes nonreactive
propane from the alkylation
reactor effluent. The propane-free
reaction effluent is routed to the benzene-recovery
column, while propane
is purged from the process. The benzene-recovery
column is also fed with
fresh benzene and the product of the
transalkylation reactor. Benzene is
separated and recycled to the reaction
section of the process, while a
crude cumene stream, obtained from
the bottom of the column, is routed
to the cumene-purification column,
from which high-purity product is obtained.
The impurities rejected in the
cumene column are treated in a further
column, which recovers PIPB for
the transalkylation reaction.
Production pathways
The two main starting materials for
cumene manufacture are benzene
and propylene. Benzene and propylene
are reacted via alkylation to
produce cumene. Polyisopropylbenzene
byproducts can be reacted
with additional benzene via transalkylation
to enhance cumene yield.
Figure 2 presents different pathways
for the production of cumene.
Economic performance
The total operating cost (raw materials,
utilities, fixed costs and depreciation
costs) estimated to produce
cumene was about $750 per ton of
cumene in the third quarter of 2016.
The analysis was based on a plant
constructed in the U.S. with the capacity
to produce 300,000 metric
tons per year of cumene.
This column is based on " Cumene
from Benzene and RG Propylene
(Zeolite Catalyst) - Cost Analysis, " a
report published by Intratec. It can be
found at: www.intratec.us/analysis/
cumene-production-cost.
■
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.
Cumene
Propane
1
2
3
4
5
6
CW Cooling Water
ST Steam
ST
CW
FIGURE 1. The diagram show cumene production from benzene and propylene
16
Heavies
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AUGUST 2020
7
8
1. Alkylation reactor
2. Transalkylation reactor
3. Depropanizer
4. Benzene recovery
5. Cumene purification
6. PIPB recovery
7. Cooling tower
8. Boiler
Cumene
Ethylene, mixed
C4, fuel, raffinate
Metathesis,
alkylation
Ethylene,
butenes,
benzene
■ Raw material ■ Process ■ Main product ■ Byproducts
Naphtha
07_CHE_0820_TechProfile_p16.indd 16
7/20/20 12:21 PM
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