HYDROGEN CYANIDE (HCN) AND CARBONYL
SULPHIDE (COS) HYDROLYSIS
Cost-effective catalytic conversion for the treatment of synthesis gas (syngas)
Shell Global Solutions
PROCESS DESCRIPTION
The HCN and COS in syngas are converted in a fixed-bed
reactor filled with a catalyst system according to:
HCN + H2O ⇔ NH3 + CO
COS + H2O ⇔ H2O + CO2
AT A GLANCE
Customer driver: Conventional amine treating solvents
are unable to remove COS from syngas and off-gas streams,
and HCN causes severe degradation of the amine solvent.
Solution: A hydrolysis process that catalytically converts
HCN and COS
The syngas is fed to the guard reactor where partial
conversion of HCN and COS takes place. The guard
reactor’s primary function is to collect soot and debris on
top of the bed and protect the main reactor, where full
conversion of HCN and COS occurs.
After passing through the catalyst beds, the syngas is
cooled and the water is knocked out. Most of the ammonia
(NH3), traces of formate and some of the carbon dioxide
(CO2) and hydrogen sulphide (H2S) will dissolve in the
knocked-out water, which is then typically routed to a sour
water stripper or other water treating facility.
Value delivered: Cost-effective removal of HCN and
COS, more selective solvent use and reduced solvent
degradation
Guard reactor
Proof point: Four reference units worldwide
Gasification processes produce syngas that is composed mainly
of hydrogen and carbon monoxide (CO). However, contaminants
such as COS and HCN are also formed. Failure to remove HCN
leads to amine degradation in the downstream amine unit, and
COS compromises the total sulphur specification of the treated
gas. Deep removal of both these contaminants is impossible using
conventional amine treating solvents.
ABOUT THE TECHNOLOGY
The catalytic conversion of HCN and COS is a cost-effective
process for reducing the harmful effects of these components in
gas streams. This hydrolysis technology has two main fields of
application:
n syngas treatment upstream of an amine unit for coal or oil
gasification processes; and
n syngas treatment where the presence of HCN or COS is
unacceptable to downstream processing units such as gas to
liquid processes.
Catalyst bed
Bypass
Main reactor
From
soot
scrubber
Catalyst bed
Catalyst bed
To H2S removal unit
To sour
water
stripper
Figure 1: Simplified process flow scheme.
HCN/COS hydrolysis enables more
selective solvent use and can help
to reduce solvent degradation.
PROOF POINTS
WILLEM-ALEXANDER POWER PLANT
The acid gas removal unit at Nuon’s integrated
gasification combined-cycle (IGCC) showpiece
power station in Buggenum, the Netherlands,
applies HCN/COS hydrolysis and the Sulfinol®
process to cut the syngas’s sulphur content to less
than 20 ppmv.
BUSINESS VALUE
Shell Global Solutions HCN/COS hydrolysis technology
cost-effectively removes HCN and COS. Catalytic conversion
creates NH3 and H2S, which can be removed easily in
downstream processes.
In addition, HCN/COS hydrolysis enables more selective
solvent use and can help to reduce solvent degradation.
Our services include:
n basis of design;
n proprietary catalysts;
n process warranties;
n operating manuals;
n performance monitoring methods;
n plant optimisation; and
n advice on unit operation.
High-performance gas-treating solutions series
HCN/COS
hydrolysis
TREATED
SYNGAS
Acid gas
removal
unit
H2S RECYCLE
ACID
GAS
Claus
AIR
Eni’s refinery near Pavia, Italy, creates syngas from
heavy residues, which it supplies to the nearby
EniPower power plant. The plant features cutting-edge
technologies, including Shell Global Solutions residue
gasification and HCN/COS hydrolysis technologies.
REFERENCES
Client
Location
Capacity,
×106 Nm3/d
Feedstock
Urea plant
Australia
9.4
Coal
Korea
4.2
Coal
Eni refinery
Sannazzaro,
Italy
~3.7
Oil
Nuon IGCC
power plant
Buggenum,
the
Netherlands
3.4
Coal
IGCC power
plant
Catalysts can be sourced through CRI/Criterion Inc., the global
catalyst technology company of the Shell Group.
RAW
SYNGAS
SANNAZZARO REFINERY
TREATED GAS
SO2
AND CO2
SCOT® and EMISSIONS
incinerator
H2S CONVERSION
TO SULPHUR
C2 treating
Elemental
sulphur
degasser
SCOT and Sulfinol are Shell trademarks.
HAVE YOU CONSIDERED HOW YOU CAN
n
cost-effectively remove HCN and COS from gas streams?
n
enable more selective solvent use?
n
reduce solvent degradation?
For further information, please visit our website at www.shell.com/globalsolutions
Shell Global Solutions is a network of independent technology companies in the Shell Group. In this
material, the expressions “the Shell Group”, “Shell” and “Shell Global Solutions” are sometimes used
for convenience where reference is made to these companies in general, or where no useful purpose
is served by identifying a particular company.
The information contained in this material is intended to be general in nature and must not be relied
on as specific advice in connection with any decisions you may make. Shell Global Solutions is not
liable for any action you may take as a result of you relying on such material or for any loss or
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Copyright © 2011 Shell Global Solutions International BV. All rights reserved. No part of this
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GS33801211 En(A)