Operating manual for shift
conversion catalysts
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and is given in good faith, but it is for the User to satisfy itself of the suitability of the Product for its own particular purpose. Johnson
Matthey plc (JM) gives no warranty as the fitness of the Product for any particular purpose and any implied warranty or condition (statutory
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information. Freedom under Patent, Copyright and Designs cannot be assumed.
© 2016 Johnson Matthey Group
Contents
Page
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Catalyst details. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Catalyst storage, handling, charging and discharging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Health and safety precautions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Reduction and start-up of KATALCOJM 71-series catalysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Operation of KATALCOJM 71-series catalysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Reduction and start-up of KATALCOJM 83-3 catalysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Operation of KATALCOJM 83-3 catalysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Reduction, start-up and operation of KATALCOJM 83-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
(isothermal shift catalyst)
Reduction, start-up and operation of KATALCOJM 83-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
(medium temperature shift catalyst)
Appendix 1: Product bulletins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Introduction
This manual discusses the principles of start-up, operation
and shut-down of shift converters. The information provided
should be used as the basis for the preparation of the
detailed operating instructions which of necessity will be
plant-specific.
The water-gas shift reaction plays a major role in
ammonia and hydrogen plant design and operation. Good
performance of the shift catalysts, and attainment of a close
approach to equilibrium and hence minimization of the CO
slip from the catalyst system is critical to the efficient and
economic operation of the plant and ensures maximum
hydrogen production from the hydrocarbon feedstock. The
water gas shift (or shift reaction) is highlighted below:
CO + H2O
∏
CO + H2
∆H = -41.1 kJ/mol
The reaction is exothermic and high conversions are
favoured by low temperature and high steam to dry gas ratio.
Ammonia plants usually operate a two-stage system
– a High Temperature Shift (HTS) followed by a Low
Temperature Shift (LTS) – with a suitable form of inter-bed
cooling.
4
Hydrogen plant designs feature a number of differing shift
conversion sections. Commonly there is a high temperature
shift stage followed by a PSA unit to separate the product
hydrogen from other components. On occasions a medium
temperature shift (MTS stage) is used in preference to high
temperature shift. On older hydrogen plants, a two-stage
system is often utilized in which a HTS is followed by a LTS
stage with suitable inter-bed cooling.
Modern catalysts for the high temperature shift stage
operate typically in the temperature range 300-450°C
(570-840°F).
Corresponding operating temperatures for the low
temperature shift section are 180-270°C (355-520°F).
Catalyst details
High temperature shift catalysts
Johnson Matthey supplies its HTS catalyst in two forms,
KATALCOJMTM 71-5 and 71‑6. The catalysts are formulated
from iron oxide, chromia and copper oxide, and provide
efficient operation due to enhanced activity. The catalysts
are also robust at low steam to gas ratios.
For physical properties and typical composition, please refer
to the product bulletin in Appendix 1.
Low temperature shift catalysts
KATALCOJM 83-3 catalysts are based on copper oxide
supported on a matrix of zinc oxide and alumina. The
established product, KATALCOJM 83-3 is also available in a
smaller pellet size designated KATALCOJM 83-3M, to allow
optimization of performance and pressure drop.
Isothermal & medium
temperature shift catalysts
KATALCOJM 83-5 and KATALCOJM 83-6 are supplied
as copper oxide supported on a matrix of zinc oxide and
alumina, and the formulations have been specially optimized
to give stable operation at higher temperatures than typical
LTS catalysts. Before use, the catalysts must be activated
and the same considerations apply as outlined for low
comparative shift catalysts. KATALCOJM 83-5 has been
specifically formulated for use in isothermal converters
whereas KATALCOJM 83-6 is formulated for use in
adiabatic medium temperature converter designs.
Johnson Matthey also offers a premium product with the
added benefits of low by-product methanol formation and
increased chloride resistance: KATALCOJM 83-3X. This is
based on the standard catalyst but is promoted with alkali
oxides to minimize methanol by-product formation. A
smaller pellet size, KATALCOJM 83-3MX, is also available.
In all cases, the copper oxide must be reduced to its active
metal state before use. This critical step in catalyst activation
is highly exothermic and the temperature of the bed must
be strictly controlled to ensure maximum catalyst activity.
An inert gas such as natural gas or nitrogen should be used
to dilute the hydrogen used for the reduction reaction. All
gases used in the reduction must be free of catalyst poisons.
The use of steam as an inert diluent during reduction must
be avoided as steam sinters the copper crystallites and
therefore deactivates the catalyst.
For physical properties and typical composition, please refer
to the product bulletin in Appendix 1.
5
Catalyst storage, handling,
charging and discharging
Before charging, discharging and handling shift catalysts
any potential risk to health during these activities should be
assessed and appropriate precautions taken. In addition the
Johnson Matthey brochure on “Catalyst Handling” should be
consulted.
Drum storage
Shift catalysts are generally supplied in mild steel drums,
fitted with polythene liners, suitable for land, sea or air
transportation and long-term storage at site. The drums
used for shift catalysts have an approximate volume of
240 litres and are filled to an appropriate weight and level
depending on the density of the contents. The precise
information will be recorded in the documentation covering
the goods.
Drums must not be stacked on their sides or stacked more
than four drums high, even when held on pallets. Taller
stacks tend to be unstable and there is the risk that the
top drums may fall off the stack. The lower drums can
be crushed due to the weight of the drums above them.
The metal drums are usually suitable for outside storage
for a few months but should be protected against rain
and standing water. If prolonged storage is expected, they
should be kept under cover and away from damp walls
and floors. The lids should be left on the drums until just
before the catalyst is to be charged. If the lids are removed
it is important that they should be replaced as soon as
possible, so that contamination of the catalyst is avoided. If
the drum lid cannot be replaced, then the catalyst should
be re-drummed without delay. If any contamination occurs
it is difficult to assess the extent of any damage without
full examination of the catalyst. If there is any doubt about
the state of the catalyst it is best not to charge it to the
converter.
6
Drum handling
Catalyst drums should be handled as carefully as possible.
They must not be rolled. Catalyst drums are often supplied
on pallets, which reduces the likelihood of damage in
transit but requires suitable fork-lift trucks and a paved
area to handle the pallets. The fork-lift truck to be used
for unloading the pallets should be fitted with rim or body
clamps to avoid damage to the drums. The use of shipping
containers for either catalyst drums or palleted drums eases
shipment and further reduces the likelihood of damage in
transit. It is important not to use standard forks to lift the
drums under the rolling hoops, as damage to the drums
and catalyst is almost inevitable. Johnson Matthey can also
supply catalysts in Intermediate Bulk Containers (or IBCs) on
pallets. IBCs can be supplied in an Octobox. Typically an IBC
will contain up to 1m3 (35 ft3) of catalyst.
Sieving catalyst
Shift catalysts are screened before they are packed into
drums for dispatch, hence sieving on site is not usually
required, but in some instances attrition can occur in transit
if the drums are roughly handled. In this case some form
of screening is advisable before charging, especially if
the catalyst appears to contain dust on delivery. Johnson
Matthey should be consulted in such situations. A good
method of sieving is to pass the catalyst over a simple
inclined screen. This is often the most satisfactory method,
since vibrating screens can cause additional unnecessary
damage and loss. The screen should contain provision to
collect the dust, and at the same time avoid generating
a dusty atmosphere. The mesh spacing should be about
half the smallest dimension of the catalyst pellet. While
the catalyst is being poured over the screen, the use of a
vacuum system situated close to the sieve will control the
dust effectively.
Pre-charging checks
Discharge of high temperature shift catalyst
Before the catalyst is charged it is important that the
condition of the catalyst support grid in the converter and
any supporting materials such as inert balls is checked. Any
support or hold down material in the HTS converter should
be of a low silica type to prevent the possibility of silica
poisoning of the HTS catalyst. Some form of light metal
shield or ‘spider’ fitted into the discharge manhole prevents
an uncontrolled discharge of catalyst, when the manhole
cover is removed. The converter should be clean, dry and
free from loose scale and debris. It is important to ensure
that the charging level is clearly defined, so as to avoid
under-filling or over-filling. The desired level can be marked
with chalk before charging is commenced.
The catalyst is usually discharged from the converter with
large mobile vacuum extraction units. Occasionally it may be
discharged by gravity flow from the bottom of the converter.
It is strongly recommended that the operation of the
thermocouples is checked and their position is noted to
allow for temperature profile analysis during operation of the
catalyst. This can be done before charging is commenced by
warming them in turn to ensure that the correct indication is
given on the instrument panel.
Even after cooling in steam, the catalyst may still be liable
to self-heating when exposed to air. Therefore water hoses
should be available to cool the material in case it overheats.
The normal shut-down procedure for inert discharge
is as follows:
1.Reduce pressure in the converter at a maximum
rate of 1-2bar (15-30psi) per minute, or as
governed by the mechanical design of the
equipment. Purge the converter free of process
gas with steam and cool to 150°C (300°F).
2. Replace steam with inert gas and cool to ambient
temperature, that is to say below 40°C (105°F).
3. Discharge the catalyst under a positive pressure
of inert gas.
Charging the shift converter
The catalyst may be loaded directly from the drums or from
intermediate bulk containers. The general rules for charging
catalysts into converters are:
The catalyst should have a free fall of between
50 and 100cm (20-40inches) to ensure a
suitable packed density is achieved. (More than
100cm/ 40inches may damage the catalyst).
∆
The catalyst must be distributed evenly as the
bed is filled, with a maximum height difference of
15cm (6inches) across the bed when completed.
Special procedures are required for loading
tubular isothermal converters. Johnson Matthey
will advise on these procedures on request.
∆
7
Alternatively the procedure is as follows:
1. Reduce pressure in the converter at a maximum rate
of 1-2bar (15-30psi) per minute. Purge the converter
free of process gas with steam and cool to 150°C
(300°F).
2. Replace steam with inert gas and cool to ambient
temperature. That is to say below 40°C (105°F).
3. Fill converter with water and immediately drain off. Air
can then be allowed to enter the converter as required
in order to achieve an atmosphere where the oxygen
level is high enough to support life, i.e. 21%.
Discharge of medium or low temperature
shift catalyst
The catalyst is usually discharged from the converter with
large mobile vacuum extraction units or by gravity flow from
the bottom of the converter.
Reduced MTS or LTS catalyst is pyrophoric and care must
be taken when it is to be discharged from the converter. The
usual procedure is as follows:
1. Reduce the pressure in the converter at a maximum
rate of 1-2bar (15-30psi) per minute, or as governed
by the mechanical design of the equipment.
2. Purge the converter with nitrogen and cool to less than
40°C (105°F).
3. Discharge the catalyst under a positive pressure of
nitrogen. This may be done by vacuum extraction or
by gravity flow from the bottom of the converter. In the
latter case as catalyst falls from the bottom manhole
it is sprayed with water, collected and dumped on a
suitable site where it is allowed to oxidize slowly.
8
In plants where there is insufficient nitrogen available for it
to be used during catalyst discharge then air must not be
allowed to enter the converter when it contains reduced
catalyst otherwise gross or localized overheating will take
place. In these situations it may be convenient to fill the
converter with water, drain and discharge the wet catalyst.
With this technique catalyst should not be allowed to sit in
water for any length of time otherwise catalyst breakdown
can occur. Under these circumstances it is advisable to drain
the converter as soon as possible after filling to facilitate
easy catalyst discharge.
Also note that when reduced catalyst is wetted hydrogen will
be generated, hence it is important that suitable precautions
are taken to ensure an explosive atmosphere cannot
occur. This can be achieved by ensuring that the vessel is
well ventilated by opening the top man way. All sources of
ignition around the converter must be controlled.
Special procedures are required for the discharge of tubular
isothermal converters. Johnson Matthey will advise on the
procedures on request.
Disposal of discharged catalyst
Through the CATALYST CARESM Programme Johnson
Matthey offers the environmentally safe disposal of its
complete product range.
Health and safety precautions
Before charging, discharging and handling shift conversion
catalysts any potential risk to health during these activities
should be assessed and appropriate precautions taken.
Entry into inert gas atmospheres
Extreme care is needed during a shut-down when an
entry has to be made into a converter containing an inert
gas. Such atmospheres do not support life and personnel
entering must wear suitable breathing apparatus. Failure to
do so will result in loss of consciousness within seconds of
breathing the atmosphere followed within minutes by death.
To avoid accidental entry of the converters, openings must
be kept closed. When personnel have to work inside the
converter, prominent warning notices must be displayed.
Everyone working within the area should be made aware of
the nature and dangers of asphyxia. They should know how
to effect a rescue and resuscitation of anyone who may be
overcome. An integrated life support system is essential with
adequate back-up. If a company has no experience in such
activities then the work is often best done by a specialized
service firm.
Dust exposure
Short term exposure to the metals and metal oxides used
in catalysts may give rise to irritation of the skin, eyes and
respiratory system. Over-exposure can give rise to more
serious effects. Material Safety Data Sheets (MSDS) should
be consulted for information. Catalysts should be handled
as far as possible in well-ventilated areas and in a way
that avoids the excessive formation of dust. Operators
who handle catalyst must wear suitable protective body
clothing, gloves and goggles. Inhalation of dust should be
avoided, and the appropriate occupational exposure limits
should be strictly observed. If these limits are likely to be
exceeded then respiratory protection should be used.
Everyone involved in the handling operation should clean
up afterwards and, in particular, must wash before eating.
Clothing should be changed at the end of each shift, and
more frequently if contamination is heavy.
Note:
The European Union has classified Chromium (VI) trioxide
as a Category 1 carcinogen. Appropriate information is
contained in the Material Safety Data Sheet sent with all
orders.
Discharged pyrophoric catalysts
Catalysts discharged in the pyrophoric state must be kept
separate from flammable materials. Transport of such
catalyst should only be in metal containers or metal-sided
trucks. Dumps of the catalyst should be within reach of
water hoses so that any overheating that occurs can be
controlled. If the pyrophoric catalyst is left in heaps then
high temperatures can develop since the rate of heat
release due to the oxidation is greater than the natural rate
of heat removal. It is therefore a prudent precaution to
spread the catalyst thinly (150-300 mm) over the ground
until the oxidation is complete and under no circumstances
should personnel be allowed to walk over the catalyst
until it has been fully stabilized. In order to test for this,
the temperature of the catalyst should be checked and
compared against the ambient temperature.
Ergonomics
Physical hazards arise from the handling of drums, material
and lifting equipment. Personnel should be aware of these
and appropriate precautions taken.
9
Reduction and start-up of
KATALCOJM 71-series catalysts
When the converter has been charged the high
temperature shift catalyst must be reduced before it can
be used. The reduction of high temperature shift catalyst is
invariably carried out with process gas under conditions that
allow the haematite to be converted to magnetite without
further reduction to metallic iron. Reduction also converts
any of the small quantity of residual hexavalent chromium
(CrO3) to trivalent chromium (Cr2O3).
3Fe2O3 + H2
↓
2Fe3O4 + H2O
3Fe2O3 + CO
↓
2Fe3O4 + CO2
2CrO3 + 3H2
↓
Cr2O3 + 3H2O
2CrO3 + 3CO ↓
Cr2O3 + 3CO2
It is very important that steam should be present during
the reduction procedure in order to prevent over-reduction
of the catalyst. It can be shown that if the H2O/H2 ratio
exceeds 0.18 at 400°C (750°F) or 1.0 at 550°C (1020°F)
then the desired magnetite is the stable phase. Similarly,
the CO2/CO ratio should exceed 1.16 at 400°C (750°F) or
1.0 at 550°C (1020°F). The graph below summarizes the
conditions necessary to prevent the reduction of Fe3O4 to
metallic iron in hydrogen and steam mixtures.
Minimum H2O to H2 ratio for HTS catalyst reduction
Temperature °C
350
400
450
500
550
600
Steam/hydrogen ratio
1.0
0.5
Fe3O4
FeO
Fe
0.1
0
650
750
850
950
Temperature °F
10
1050
1150
It should be noted that reductions are normally carried out
at much lower temperatures, typically starting at 320°C
(610°F) and for some plants rising to 370°C (700°F) or
more by the end of the reduction process.
During catalyst reduction it is preferable to avoid the
condensation of water in the catalyst bed. If possible, the
catalyst should therefore be heated in an inert gas stream
to a temperature that will prevent the condensation of
steam before process gas is admitted to the converter.
It is suggested that the margin between the operating
temperature and the dew point be at least 20°C (36°F) to
prevent condensation.
All HTS catalysts contain a small amount of residual
sulphate that is converted to H2S during the reduction
procedure. The level of residual sulphur is so low in
KATALCOJM 71-series, that no special desulphurization
step is usually needed. However, for some plants the
downstream operations such as the low temperature shift
catalyst and / or the CO2 removal system are sensitive
to sulphur, and therefore it may be advisable to include
an additional desulphurization step during the start-up
of the HTS catalyst. Johnson Matthey will advise on this
desulphurization step on request.
Reduction and start-up
In plants based on steam reforming of hydrocarbons
no separate reduction procedure is required for high
temperature shift catalyst as the introduction of process
gas serves to activate, desulphurize and commission the
catalyst bed. The commissioning of the HTS catalyst can be
performed in the following manner:
1. Purge the converter free of air with an inert gas and heat
the catalyst above the condensation temperature at a
rate of about 50°C (90°F) per hour
2. During the initial start-up of a new or replacement charge
of high temperature shift catalyst (before it is reduced),
care should be taken to ensure that the catalyst is not
dried excessively prior to reduction. This excessive drying
can occur if the catalyst is held in hot nitrogen circulation
for an excessive period (typically more than 12 h) if, for
example, there are delays during start-up or upstream
refractory is being cured. The extent of drying is also
influenced by the HTS catalyst temperature during
nitrogen circulation with a higher temperature leading
to a more de-hydrated surface for a given heating gas
circulation time.
When process steam is introduced to dried oxidic catalyst
which has not previously been in service, re‑hydration
of the catalyst occurs and this can lead to an exotherm,
which can generate temperatures in excess of
450°C (840°F).
To avoid this phenomenon, minimize the duration of
nitrogen circulation by heating the bed quickly (50°C /
90°F per hour), and suspending circulation across the
HTS catalyst should plant start-up be delayed. Also, add
a small amount of steam to the gas used for heating as
soon as possible during plant start-up.
Once all bed temperatures are more than 30°C (54°F)
above the dew point, replace the flow of heating gas
with a once through flow of process steam or reformed
process gas.
Should an exotherm occur when process steam is
admitted, continue introducing steam at a high flow rate
to remove the heat generated through the bed, and
maintain the converter at low pressure.
If excessive drying is suspected, it is possible to rehydrate
the catalyst by controlled addition of steam, obviously
monitoring temperatures carefully whilst small amounts
of steam are introduced.
Once again, note that this phenomenon occurs on
the initial start-up of a new or replacement HTS
catalyst charge.
3. Establish a flow of process gas or steam through
the converter at a wet gas space velocity in the
range 200-1000 h -1. Allow any water that does
condense on the catalyst to drain from the converter.
KATALCOJM 71-series reduction will start at about
150°C (300°F) if hydrogen is present and so process gas
can be utilized at an early stage during heating.
4. Increase the catalyst inlet temperature at a rate of 50°C
(90°F) per hour until the bed temperature reaches
300°C (570°F). Reduction will continue gradually until
the normal operating temperature is reached.
5. The high temperature shift reaction will gradually begin
at temperatures in the range 300-320°C (570-610°F)
and a temperature profile will develop through the bed.
The temperature rise will be about 13.5°C (24°F) for
every 1% of carbon monoxide (in wet process gas) that
is converted. It is important, therefore, to restrict the
concentration of carbon monoxide and/or the bed inlet
temperature to prevent the bed outlet temperature
exceeding 500°C (930°F) during the reduction
procedure.
6. Increase the process gas rates and adjust bed inlet
temperature to the start of run operating value.
11
The above procedure is chosen as a reasonable
compromise between energy use and stress on the plant
equipment. It should be used during the first reduction of a
new catalyst in order to avoid condensation on the catalyst,
which can leach any soluble chromium (Vl) from the
catalyst, weakening its structure and reducing its life.
Subsequent start-up
During subsequent start-ups, plant equipment permitting,
normal process gas, or if not available then superheated
steam, can be used to warm up the catalyst from cold, and
heating rates of 100-150°C/ h (180-270°F/ h) can be
employed without any detrimental effect to the catalyst.
Greater care must be taken if the catalyst has been wetted
during the shut-down, and in this case the catalyst must
be warmed up slowly (at a rate of 50°C per hour (90°F/
h)) at first to allow the pellets to dry out. Once the bed
temperature reaches the prevailing dew point, the bed
should be maintained at this temperature for approximately
four hours to ensure complete dry-out of the catalyst (the
inlet gas temperature being 10-20°C (18-36°F) above the
dew point). Once this has been achieved, heating rates can
be increased to 100-150°C/h (180-270°F/ h).
12
Operation of KATALCOJM 71-series catalysts
Plants that make hydrogen by steam reforming (whether
an ammonia plant or a hydrogen plant) usually incorporate
a HTS stage followed either by a PSA unit or a LTS, CO2
removal and methanation stages. Whatever the plant
design, it is usual to operate the HTS catalyst to give
maximum carbon monoxide conversion. In plants with
more than one shift converter, a more flexible operation is
possible and bed temperatures must be carefully optimized.
Optimum conditions can usually be determined by trial and
error. When requested, Johnson Matthey will give advice
based on calculations using its own specialized computer
programs for shift catalyst performance optimization.
The HTS converter is integrated with the process heat
recovery system. It is usually preceded by, and in many
modern plants is also followed by, a waste heat boiler. The
flexibility of the HTS inlet temperature can therefore be
limited by steam requirements and boiler performance so
that operation under optimum conditions will not always
be possible.
The normal life of HTS catalysts in ammonia and hydrogen
plants is three to five years although in some cases it can
be longer. End of life may be indicated by an increase in
carbon monoxide slip and by the end of the temperature
profile moving towards and through the end of the bed. It
is normal practice, at the start of life, to take advantage of
the high initial activity of these catalysts by running at a low
inlet temperature (around 300°C/570°F in some plants),
although in some cases this cannot be achieved due to
limitations with the upstream or downstream heat recovery
requirements. As the catalyst ages and loses activity over its
operational life, it is necessary to raise the inlet temperature
gradually to maintain the minimum CO slip, which
corresponds to the maximum CO conversion and maximum
temperature rise across the bed. Over the life of the
catalyst, the inlet temperature would typically rise 30-40°C
(54-72°F) depending on the initial inlet bed temperature.
Catalyst operating life may also be shortened as a result of
high pressure drop caused by the accumulation of deposits
on the top of the catalyst bed.
In such cases it is possible to remove these deposits by
using a vacuum device during a convenient plant shut‑down.
If the deposits are in the top section of the bed then
this technique can be very effective, and an extension
of the operating life may be achieved. If the deposits
have migrated down into the main body of the bed, then
vacuuming will be of limited use.
Loss of activity under normal conditions is usually caused by
slow thermal sintering, in which the small magnetite crystals
agglomerate together in spite of the stabilizing effect of the
chromia. The larger magnetite crystals have a lower active
surface area, and hence the catalyst activity decreases.
Greater rates of sintering are seen at higher temperatures.
However, the more open structure of KATALCOJM 71-series
helps to minimize this effect. In addition, the effects of
certain poisons such as silica can reduce catalyst activity
and life.
Temperature profile
Performance of the catalyst may be monitored during
operation by the slope of the temperature profile together
with the corresponding increase of outlet carbon monoxide
concentration towards the end of life. The foot of the
temperature profile will not move, however, the gradient
of the profile will slowly reduce due to catalyst sintering. A
rapid change in gradient indicates that there is an unusual
problem. This may be due to deposition of solids such as
soda, silica, potash etc. from upstream equipment (such as a
waste heat boiler leak or high silica refractory), which block
the bed and interfere with the gas flow. The most common
symptom of blockage is increasing pressure drop. If the
plant rate is variable or there are large variations in inlet
temperature then the analysis of the slope of the profile has
to be suitably corrected for these variations.
Common problems can usually be identified from routine
measurement of bed temperatures, pressure drop
through the bed and analysis of outlet carbon monoxide
concentration. Advice should be requested from your
Johnson Matthey representative as soon as any unusual
conditions are experienced.
13
Deposition of solids in the catalyst bed
If any solids are deposited on the top of the catalyst bed
there will be an increase in pressure drop across the bed.
During a shut-down the bed can be skimmed by purging
the reactor with an inert gas and then vacuuming any
contaminated catalyst together with the deposit from the
top of the bed. The pressure drop should return to a more
normal value.
Caution: great care should be taken and procedures well
defined before a person enters a vessel containing an inert
atmosphere. Depending on the quantity of catalyst that
has been contaminated by the deposit it may be necessary
to replace with an equivalent volume of new catalyst. No
special reduction procedure will be required for the new
catalyst.
Sulphur
During use the catalyst will establish an equilibrium with any
sulphur which is present in the inlet gas. Any unexpected
sulphur entering the converter will be retained by the
catalyst as iron sulphide and then slowly released as normal
conditions are resumed. In steam reforming flowsheets the
inlet sulphur level should be much less than 1ppm. However,
a HTS catalyst may be used downstream of coal‑based
or partial oxidation units where the sulphur levels may
be significantly higher. For concentrations of sulphur
compounds less than 200ppm in the inlet gas there should
generally be no significant effect on the catalyst. Above this
level bulk iron sulphide will be formed which has only about
half the activity of magnetite and allowance for this must
be made in the initial design calculations. Frequent cycling
between sulphiding and non-sulphiding conditions should be
avoided, although the catalyst is strong enough to withstand
occasional cycling during plant mal-operation.
14
Johnson Matthey can also offer KATALCOJM K8-11, cobalt
molybdenum catalyst, which has been developed for shift
conversion in a high sulphur environment. Details are
available from Johnson Matthey.
Shut-down
During a short shut-down KATALCOJM 71-series may be
left in an atmosphere of process gas or steam at operating
pressure and temperature. This can result in a partial
oxidation of the catalyst that will be reduced rapidly during
restart. If the converter is likely to cool during the shut-down
period it should be purged with an inert gas to prevent
condensation of water. In addition the converter drains
should be checked and any accumulation of condensate
within the converter drained off.
Reduction and start-up
of KATALCOJM 83-3 catalysts
LTS catalysts must be reduced with hydrogen before use.
This procedure converts the stable copper oxide component
of the new catalyst into reactive copper metal. During
reduction and operation both the zinc oxide and alumina
components are unchanged and act as a support which
stabilizes the copper metal crystallites, and also act as a
reservoir for poisons.
CuO + H2
↓
Cu + H2O
∆H = -81 kJ/mol
Since the reaction is exothermic, the reduction procedure
generates large quantities of heat and relies on having
equipment available to pass diluent inert gas through the
LTS converter to minimize the temperature rise.
The easiest procedure is to pass a continuous stream of
inert gas, usually methane or nitrogen, through the catalyst
bed on a “once through” basis. Although this method can
be relatively expensive it has the advantage of allowing a
high space velocity during reduction, which will complete the
procedure in about 12-24 hours. The alternative procedure
is to recycle inert gas, usually nitrogen, through the catalyst
bed via a special reduction loop, which also includes a
recycle compressor and start-up heater. Space velocity will
be limited by the capacity of the recycle compressor but
should preferably be at least 300h-1.
Care should be taken to ensure that the inert carrier gas is
free from reducing components (such as hydrogen or CO)
and oxidizing components (oxygen). In the event that natural
gas is used as the inert carrier the quantity of heavier
hydrocarbons should be minimized as these hydrocarbons
can react to reduce copper oxide and generate an
exotherm larger than observed with hydrogen. The carrier
gas should also be free of catalyst poisons such as sulphur
or chloride.
With recycle systems there are several important points
to remember:
1. If the reformer is being used as the start-up heater, then
carbon dioxide, evolved from residual carbonates in the
LTS catalyst, may methanate and the product methane
c an crack on the nickel based reforming catalyst in the
reformer and thereby deposit carbon. There are various
procedures to prevent this from happening and Johnson
Matthey can provide recommendations if required.
2. The concentration of hydrogen entering the LTS catalyst
bed should not exceed 1.0% v/v during the early stages
of reduction in order to limit the temperature rise if unreacted hydrogen builds up in the recycle loop.
3. In some cases the ‘minimum gas density limit’
(commonly referred to as surging) of the compressor
may restrict the maximum hydrogen concentration in
recycle gas during the final stages of reduction.
4. Water evolved from the catalyst during reduction must
be removed from the closed recycle loop and not be
recycled through the catalyst bed.
5. Hydrogen and nitrogen streams need to be free from
water and oxygen that will interfere with the reduction.
Nitrogen should be free of hydrogen as this can lead to
excess hydrogen being fed to the catalyst.
Reduction procedure
The following reduction procedure is recommended for
use in plants with facilities for either ‘once-through’ or
‘circulating recycle’ systems for catalyst reduction:
1. Purge the converter with inert gas until all oxygen has
been removed. Establish a flow of inert gas and heat the
catalyst bed to 120°C (250°F) at a rate of 50°C (90°F)
per hour or as governed by the mechanical design of the
equipment. Any convenient pressure, up to operating
pressure, may be chosen for the catalyst reduction. In a
circulating system a high pressure is normally preferred
as it allows a higher gas flow to be achieved in the
system, and the higher partial pressure of hydrogen
helps the reduction.
Exception: if natural gas is used as a carrier gas, then
the reduction pressure should be lower than 7 barg
(100 psig). This is because higher pressures reduce the
initiation temperature of hydrocarbon reduction.
15
Experience has shown that reduction in natural gas can
be safely carried out at a maximum pressure of 7 barg
(100 psig) when the peak temperature in the bed is kept
below 230°C (445°F).
2. Increase the inert gas flow rate to the maximum
space velocity possible. Ensure that both the hydrogen
flowmeter and analyzer are operating satisfactorily as
the temperature approaches 130°C (265°F). Continue
heating the catalyst until the top of the bed is at 180°C
(355°F). The temperature of the inert gas should not
exceed 210°C (410°F) during the initial heating. If the
inert gas space velocity is less than 300h-1 more care is
necessary as there can be poor gas distribution, which
can lead to localized overheating. Start recording bed
temperatures during warm-up to confirm that all the
thermocouples are responding correctly and that the gas
is well-distributed through the bed.
3. When at least the top third of the catalyst bed has
reached 160°C (320°F) hydrogen should be introduced
into the carrier gas entering the bed up to a maximum
of 1.0% v/v. Once the reduction reaction has started it
will be necessary to record the temperature at different
points in the catalyst bed to determine the progress of
the temperature profile at regular time intervals. If the
reduction reaction is slow with a bed inlet temperature
of 180°C (355°F) then the inlet temperature should be
raised cautiously to 190-200°C (375-390°F) and held
steady at the temperature which gives a satisfactory
reduction rate.
4. Once reduction has started and a steady temperature
profile has been established, the hydrogen concentration
should be increased. With nitrogen as carrier gas the
hydrogen concentration can be increased to 1.5%
v/v and with natural gas as carrier gas the hydrogen
concentration may be increased to 2.0-2.5% v/v. The
peak temperature in the bed should not, however,
exceed 230°C (445°F) and the hydrogen concentration
should be changed as necessary to control the
temperature rise and thereby limit the peak bed
temperature.
nce reduction has started it may be possible to
O
decrease the temperature of inlet gas entering the
catalyst bed to 180°C (355°F) or less. The temperature
rise for 1% hydrogen is typically 30°C (54°F) in nitrogen
and 20°C (36°F) in natural gas.
16
5. As the reduction proceeds, the temperature profile
will move down the catalyst bed. The temperature rise
will decrease when most of the copper oxide has been
converted to copper. At this point the catalyst bed inlet
temperature may be raised to 200°C (390°F). The
inlet hydrogen concentration can also be increased to
3-5% v/v provided that the maximum temperature limit
of 230°C (445°F) in the catalyst bed is not exceeded.
6. When the catalyst reduction appears to be complete
the catalyst bed inlet temperature should be raised
and held at 225-230°C (435-445°F) and then if
possible, the inlet hydrogen concentration in the
inert gas should also be increased to 20% v/v. This
holding state should be for a minimum of two hours.
No temperature rise should be observed and the
maximum catalyst temperature should not exceed
230°C (445°F). Analysis should indicate that the
hydrogen concentration inlet and exit of the catalyst
bed are within 0.2% of each other. If mal‑distribution
is suspected, for example, if the space velocity is
too low, then more attention should be paid to any
decrease in hydrogen concentration as this may
indicate that there is still unreduced catalyst within
the converter. Similarly, the temperatures throughout
the converter should be monitored to check for
an exotherm, which again indicates the presence
of unreduced catalyst within the converter.
If an exotherm is observed during this soak period, then
the hydrogen source should be shut off immediately and
the inlet temperature of the converter reduced such that
the peak temperature is reduced to less than 230°C
(445°F).
Once the peak temperature is less than 230°C (445°F),
the bed inlet temperature can be raised to 190°C
(375°F) and the reduction restarted as per step 3 above.
Under no circumstances should the gas flow to the bed
be stopped since this is the only means of ensuring that
the exotherm can be reduced.
7. The catalyst reduction is complete and the converter
should be commissioned.
Controlling the catalyst reduction
The reduction procedure has been designed to limit the
temperature rise in the catalyst bed by restricting the
hydrogen concentration. This ensures that the maximum
temperature in the bed does not exceed 230°C (445°F)
and the maximum catalyst activity is achieved. The
reduction reaction is indicated by the temperature profile
which moves from the inlet to exit of the catalyst bed at a
rate which depends on inert gas space velocity, hydrogen
concentration and bed inlet temperature. The same
principles also apply to radial flow beds.
During the whole of the reduction period it is important
that operators should determine the inlet and exit
hydrogen concentration at regular intervals. The difference
between these two measurements during the time of the
reduction represents the volume of hydrogen consumed.
Any oxygen present in carrier gas will also react with
hydrogen to form water. Normally the volume of hydrogen
required for the reduction is 185Nm3/ m3 (195scf/ ft3)
for KATALCOJM 83-series catalysts. A comparison of the
hydrogen consumed against the theoretical consumption
should be made as a cross check against the progress of
the reduction.
The volume of water forming during the reduction
procedure will also provide an indication of the progress.
Measurement of water produced should only be
used as an approximate check on hydrogen uptake.
KATALCOJM 83-series catalysts will produce an amount
of water corresponding to 10-15% of the installed catalyst
weight, from the reduction process.
Catalyst reduction is virtually completed when the inlet
and outlet hydrogen concentrations are the same and the
whole bed is above a temperature of 230°C (445°F). The
volume of hydrogen consumed should confirm this. It may
be difficult to achieve exactly equal hydrogen concentrations
at inlet and outlet of the bed and reduction may be
considered complete when the difference between the two
measurements has been less than 0.2% v/v for more than
four hours.
Any complex copper-zinc basic carbonates present in
the catalyst decompose during reduction and release
carbon dioxide. Carbon dioxide can be purged from the
recycle system but if for any reason the catalyst reduction
procedure is halted, or the catalyst bed isolated at reduction
temperature, then any further carbon dioxide evolution will
lead to an increase in converter pressure. Pressure should
therefore be monitored during the time that a converter
is isolated, when it contains partially or freshly reduced
catalyst, and any increase in pressure should be controlled
by venting.
In addition, if the converter is to remain isolated for any
length of time after the reduction is completed but before
it is commissioned, catalyst bed temperatures should be
monitored frequently. If any increase in temperature is
detected the converter should be immediately purged with
inert gas to avoid any rapid temperature rise.
17
Hydrogen source
Almost any gas containing hydrogen is suitable for the
reduction e.g. methanator gas, carbon dioxide removal or
high temperature shift converter effluent gas. Hydrogen
should be free of sulphur or chlorine and, if any carbon
monoxide is present, allowance should be made for the
extra temperature rise during reduction.
Natural gas
In some circumstances natural gas is favoured as the inert
carrier gas during reduction, due to its availability and low
cost. In the event that natural gas is used as the inert carrier,
the quantity of heavier hydrocarbons should be considered
as these hydrocarbons can react to reduce copper oxide
and generate an exotherm larger than observed with
hydrogen. The carrier gas should also be free from known
LTS catalyst poisons such as sulphur or chloride.
The risk with using natural gas for LTS reductions is the
potential that the hydrocarbons can act as reducing
agents at elevated temperature. High temperatures in the
catalyst bed can lead to undesirable hydrocarbon reduction
reactions, which are much more exothermic than hydrogen
reduction reactions. The result of these reactions can
be irreparable damage to the catalyst and potentially to
the reactor itself. This risk is present for any natural gas
reduction. Strict control of catalyst bed temperature is a
necessity in natural gas reduction to prevent hydrocarbon
reduction and temperature runaway. If a once-through
reduction scheme is being used, an increasing temperature
can be controlled by shutting off the hydrogen supply.
In the recirculation scheme, there is no ability to instantly cut
off the hydrogen supply to stop the reduction and help cool
the reactor, hence the risk is greater.
The impact of pressure on the hydrocarbon reduction
initiation temperature is also a concern. Higher pressure
reduces the initiation temperature, and it should be noted
that the hydrocarbon reduction initiation temperature for
higher hydrocarbons is lower than methane (methane >
ethane > propane etc.).
18
Whichever reduction configuration is being used (once
through or recycle), if natural gas is used as a carrier gas,
the pressure should be lower than 7 barg (100 psig), and
the peak temperature lower than 230°C (445°F).
Steam
Steam should never be used as the inert carrier gas during
the reduction procedure. Use of steam as a carrier will
deactivate the catalyst and shorten the subsequent life of
the charge.
Start-up
If the catalyst has already been reduced but is cold, the
bed should be warmed to a temperature above the dew
point with inert gas before process gas is introduced to the
converter. During the initial start-up following reduction
of the catalyst, the bed temperatures will usually increase
rapidly as the reaction comes to equilibrium with process
conditions.
The peak temperature may reach 260°C (500°F) or higher
at this stage but there will be no damage to the catalyst
because the peak will quickly pass through the bed. The
high temperature can be moved quickly through the
bed by increasing the flow of process gas to design rates
as soon as possible. The catalyst bed inlet temperature
should also be held as low as possible provided that it is at
least 20°C (36°F) above the dew point. For most duties
this corresponds to an inlet temperature of about 200°C
(390°F). If there are particular reasons for avoiding a
temperature peak there are several ways by which it can be
minimized:
1. By increasing converter pressure to design level with
inert gas before introducing process gas.
2. Introducing process gas at low pressure while venting
gas at the converter exit. This is particularly easy after
reducing catalyst with a ‘once-through’ flow of natural
gas by gradually replacing the flow of natural gas by
process gas and then opening the inlet and exit valves
fully while closing the vent to commission the converter.
Operation of KATALCOJM 83-3 catalysts
It is important to operate the LTS catalyst under optimum
conditions to achieve the potential savings in plant costs.
The LTS catalyst is sensitive to changes in operating
conditions but it is not difficult to maintain fixed steam ratio,
pressure and gas composition so that the only real variable
is the catalyst inlet temperature. During the commissioning
procedure the bed inlet temperature is gradually increased
until the carbon monoxide concentration in exit gas falls to
the minimum level for the conditions. This is the optimum
level for maximum CO conversion and at higher inlet
temperatures the carbon monoxide level will again increase.
As the catalyst ages or is poisoned it will be necessary to
increase the inlet temperature to maintain the minimum
carbon monoxide concentration in the exit gas.
LTS catalysts often operate close to condensation
conditions during the early part of the catalyst life. To avoid
condensation of water either in the catalyst pores or onto
the bed the inlet temperature should be at least 20°C
(36°F) above the dew-point at all times. This may mean
that operation will be at temperatures higher than the
optimum until catalyst activity has fallen sufficiently for the
actual and optimum operating temperatures to correspond.
This is not a problem because at temperatures in the
range 200-205°C (390-400°F) the difference between
the equilibrium outlet carbon monoxide concentration
and the optimum will be very small and the actual outlet
concentration will remain constant for a long period.
During the normal operating life of the catalyst, optimum
operating conditions can be maintained by a gradual
increase of the bed inlet temperature as soon as the carbon
monoxide level increases slightly. Whenever changes in
steam ratio or gas composition occur the bed inlet should
be checked to ensure that it is still at the optimum level. This
should be done by increasing or decreasing the bed inlet
temperature by 2°C (4°F) and then checking the carbon
monoxide concentration at the bed outlet when conditions
have stabilized. If a decrease in the carbon monoxide
concentration is detected the procedure is repeated until
the minimum level has been reached.
A simple way of determining CO slip is to observe the
methanator temperature rise if the flowsheet features this
converter. Minimum CO slip from the low temperature shift
will correspond to the minimum temperature rise across the
methanator. PSA based plants rarely use an LTS but when
they do declines in PSA recovery could indicate a rise in CO
slip exit the LTS.
Towards the end of the catalyst life the bed exit temperature
may reach the maximum allowable catalyst operating
temperature of 250°C (480°F). This is, however, a
conservative figure and short-term operation up to 270°C
(520°F) is allowable although this will reduce the long term
catalyst activity.
At higher temperatures, however, the deactivation rate for
partially poisoned catalyst is faster and the carbon monoxide
equilibrium level becomes increasingly unfavorable.
Operation with high outlet carbon monoxide concentrations
will become increasingly expensive. It is usually more
economic to plan a catalyst change before the performance
deteriorates beyond the design level.
By-product formation
Methanol and, to a lesser extent amines (formed from
methanol and nitrogen compounds such as ammonia
produced in the upstream reformers), are formed in low
temperature shift catalyst beds, particularly in the early
stages of life when catalyst activity is at its maximum.
By‑product formation is very sensitive to temperature and
can be minimized by running with a low inlet temperature.
This is consistent with maximizing CO conversion. As ageing
occurs, by-product formation is reduced.
If operators require ultra-low methanol
by‑product formation, then KATALCOJM 83-3X or
KATALCOJM 83‑3MX should be used.
19
Temperature profile
Shut-down
The temperature profile through the catalyst bed is a useful
indicator to follow changes in catalyst activity especially
when the outlet carbon monoxide concentration is at the
equilibrium level. For a fresh catalyst most of the reaction
and the corresponding temperature rise will be at the top
of the bed. Loss of catalyst activity (or catalyst deactivation)
during operation is largely due to poisoning. Because the
catalysts are ‘self-guarding’ poisons accumulate at the top
of the catalyst bed. The temperature profile will therefore
gradually move from the inlet towards the exit of the catalyst
bed as more poisons are absorbed. Towards the end of the
catalyst life when the reaction zone has reached the bottom
of the bed and the outlet carbon monoxide level has started
to increase from the equilibrium concentration, the catalyst
should be changed.
During an extended plant shut-down, when the converter
can cool down, process gas must be purged from the
converter to avoid the condensation of water on to the
catalyst. This could damage the catalyst by washing poisons
from the top to the bottom part of the catalyst bed on to
fresh un-poisoned catalyst lower down the bed. Pressure
should therefore be decreased to atmospheric, before the
temperature falls below the dew-point, and the converter
purged with an inert gas to remove all steam.
Any variation from a typical temperature profile will indicate
abnormal conditions.
1. A slow increase in bed temperature giving a flatter than
average profile can indicate that the whole catalyst bed
has been partially deactivated. This may be due to the
presence of liquid water in the bed which would block
the catalyst pores and wash poisons from the top of
the catalyst down to the middle or bottom levels. The
catalyst may also have been overheated. (This flatter than
average profile could also be due to higher plant rates
than normal).
2. If the temperature profile appears to be normal but the
outlet carbon monoxide is higher than expected then gas
may be bypassing part of the catalyst bed through bed
channelling or leaks in by pass piping if this exists.
Steam
The use of steam alone should be avoided as far as possible
to prevent condensation of water in the catalyst bed. During
plant upsets, short periods of steaming may be unavoidable
but it is far better to isolate the low temperature shift
converter and reduce pressure to depress the dew point.
The converter should then be purged with an inert gas.
20
Catalyst poisons
Sulphur and chloride are the most serious poisons
for LTS catalysts. Of the two, chlorides are the more
virulent, however, sulphur tends to be present in greater
concentrations in the process gas and therefore often
determines the catalyst life.
Chlorine compounds are often present in process gas
streams in extremely small concentrations that cannot be
detected by typical analytical procedures. The poisoning
effect is cumulative so that any concentration of chlorine
in process gas will eventually poison the catalyst bed and
detection is only possible by the analysis of samples taken
from discharged catalyst.
The formulation of Johnson Matthey to provide thermally
stable structures also enhances the ability of these catalysts
to absorb poisons. KATALCOJM 83-series catalysts can
absorb chlorides at the top of the bed and guard active
catalyst in lower layers, and so extend operating time. Strict
attention is necessary, however, to maintain steam purity
and to avoid contamination of feedstocks or process air by
chlorine compounds. Solvents containing chlorine should
not be used for cleaning any items of plant equipment
as well as the use of chlorine and low sulphur containing
synthetic lubricants for compressors. If chloride poisoning is
an issue then the use of KATALCOJM 83-3X or MX should
be considered as these catalysts have a greater resistance
to halide poisoning.
Sulphur compounds also affect the operation of
KATALCOJM 83-series catalysts but are much less virulent
poisons than chlorine compounds. Johnson Matthey
catalysts are selfguarding against sulphur compounds
provided that the typical levels found in ammonia or
hydrogen plants based on steam reforming are not
exceeded for long periods.
Silica is also present in some process gas streams, for
example by leaching from high silica balls installed in the
secondary reformer or HTS bed, and is absorbed by the
catalyst bed and gradually deactivates the catalyst. Small
amounts of silica are deposited on the catalyst surface but
larger quantities react with the catalyst to form zinc silicate.
Silica is not a typical catalyst poison but has the effect of
decreasing the catalyst’s capacity for other poisons and
therefore allows chlorine and sulphur to pass further into
the catalyst bed.
21
Reduction, start-up and operation
of KATALCOJM 83-5 (isothermal shift catalyst)
KATALCOJM 83-5 is a member of the
KATALCOJM 83-series of catalysts and many of the
same principles apply as for KATALCOJM 83-3 catalysts.
KATALCOJM 83-5 is specifically designed for use in
isothermal (steam-raising) shift converters. Before use the
catalyst must be reduced with hydrogen in exactly the same
way as for LTS catalysts. The reduction is exothermic and
must be controlled to prevent excessively high temperatures
and subsequent catalyst damage.
Care should be taken to ensure the hydrogen content of the
reduction gas is well controlled to prevent excessive heat
release that could cause problems with control of the steam
generation and lead to overheating of the catalyst bed.
In an isothermal converter heat is rapidly removed from the
catalyst and transferred to the water-side circuit. Compared
with the exotherm arising from a catalyst reduction in
a typical adiabatic shift converter, that observable in an
‘isothermal’ shift converter is less marked. However, a
temperature peak is usually observable and its movement
through the bed does give some indication as to how
the reduction is progressing. Furthermore, by observing
hydrogen concentrations inlet and exit the bed, as well as
heat release/ steam generation on the water-side, good
control of the reduction can be achieved.
1. Purge the converter with an inert gas to remove oxygen.
Establish a flow of inert gas that is sufficient to ensure
even gas distribution through the catalyst and heat
the bed at a rate of around 50°C (90°F) per hour. For
this heating stage (and also for other heating stages
in this procedure), the pressure of the steam side,
and hence the temperature has to be controlled in
order to achieve the required temperature changes.
Reduction procedure
The basic philosophy of the reduction is to warm up
the catalyst in an inert atmosphere at a steady rate
to a temperature where reduction will start. Once
this temperature is reached hydrogen is carefully
introduced at low concentrations to control the rate of
reduction. As the reduction proceeds the temperature
and hydrogen concentration are steadily increased to
maintain the pace of the reduction without causing
local overheating. Once reduction is completed
the converter is commissioned as normal.
If a recycle system is used the same points should be borne
in mind as with the LTS around potential carbon laydown
in the primary reformer, hydrogen accumulation in the
reduction loop, minimum gas density and water evolution.
The pressure in the catalyst bed can be any convenient
value, higher pressures tend to help the reduction
by increasing the partial pressure of hydrogen.
Exception: if natural gas is used as a carrier gas, then
the reduction pressure should be lower than 7 barg
(100 psig). This is because higher pressures reduce
the initiation temperature of hydrocarbon reduction.
Experience has shown that reduction in natural gas
can be safely carried out at a maximum pressure
of 7 barg (100 psig) when the peak temperature
in the bed is kept below 230°C (445°F).
2. Check the hydrogen analyzer and flowmeter
are operating satisfactorily as the temperature
approaches 130°C (265°F). During heat-up
keep the inlet gas temperature within about 30°C
(55°F) of the top of catalyst bed temperature.
3. When at least the top third of the catalyst
bed has reached 160°C (320°F) hydrogen
should be introduced into the carrier gas at a
concentration of 0.5-1.0% v/v inlet the bed.
22
4. Monitor the hydrogen concentration exit the
bed and the steam raising on the boiler side as
indicators of the reduction rate. If no hydrogen is
consumed and there is no evidence of heat release
cautiously increase the bed temperature towards
190-200°C (375-390°F). Hold the temperature
once a steady reduction rate is achieved.
5. Once reduction has started the aim is to carry
out the reduction at a steady rate by adjusting
hydrogen concentration and bed temperature.
In the early stages of reduction, once it has been
established that reduction is under way, the
inlet hydrogen concentration can be increased
to around 2.0% v/v. Keep monitoring the
bed temperatures, and ensure the maximum
temperature does not exceed 230°C (445°F).
6. As the reduction nears completion, the steam
raising rate will reduce and the hydrogen content
exit the bed will rise towards the inlet concentration.
The catalyst temperature can then be steadily
increased to 200°C (390°F) and then the hydrogen
concentration should be carefully increased to 5%.
7. Once the reduction appears to be finished a hydrogen
‘soak’ is carried out to complete the procedure. Raise
the catalyst temperature to 225-230°C (435‑445°F)
and then increase the hydrogen content to 20%
v/v. This procedure should be carried out steadily,
monitoring the progress of the reduction closely
and should take a minimum of two hours. The
hydrogen concentration exit the bed should be the
same as the inlet, indicating reduction is complete. (If
hydrogen begins to be consumed return to step 6).
Start-up
The main problem during start-up is to prevent condensation
on the catalyst. This is achieved by heating the catalyst to a
temperature of approximately 20°C (36°F) above the dewpoint (usually by feeding steam into the steam side of the
converter) before process gas is introduced.
Operation
The normal operating temperature for an isothermal shift
converter is typically 240-260°C (465-500°F) at inlet and
exit of the bed although there will be a peak temperature of
280-300°C (535-570°F) in the reaction zone.
To avoid condensation of water either in the catalyst pores
or onto the bed both inlet and outlet temperatures should
be at least 20°C (36°F) above the dew point at all times.
The main mechanism for catalyst de-activation is poisoning.
During the life of the catalyst charge, the reaction zone
will move slowly down the bed as catalyst at the top of
the bed is poisoned. In contrast to an adiabatic bed, the
inlet temperature has very little effect on the converter
performance. Heat transfer in the converter ensures that
the exit temperature is usually close to the boiling water
(steam) temperature, and the boiling temperature can be
adjusted to give the minimum CO slip. This is carried out
on a trial and error basis by raising or lowering the steam
temperature by 2°C (4°F) and monitoring the CO slip.
8. The catalyst is now reduced and the converter
can be commissioned as required.
23
Reduction, start-up and operation
of KATALCOJM 83-6 (medium
temperature shift catalyst)
KATALCOJM 83-6 is also a member of the
KATALCOJM 83-series of catalysts and is specifically
designed for use in adiabatic medium temperature shift
(MTS) converters.
Reduction procedure
The reduction procedure is the same as that described
earlier for the KATALCOJM 83-3 LTS catalysts.
Start-up
The start-up considerations given for the KATALCOJM LTS
catalysts also apply to KATALCOJM 83-6.
Care should be taken to prevent condensation of steam on
the catalyst during the start-up procedure.
24
Operation
Introduction of process gas should follow the usual
procedure for LTS catalysts. Normal operating temperatures
for KATALCOJM 83-6 are in the range 200-230°C (390445°F) at bed inlet.
To avoid condensation of water either in the catalyst pores
or onto the bed, the bed temperature should be at least
20°C (36°F) above the dew point at all times.
The inlet CO level for a MTS converter is higher than for a
LTS converter and thus the exit temperature will typically
approach 300°C (570°F). The optimum inlet temperature
must be established on line by carefully adjusting the inlet
temperature to establish the minimum CO slip. In order to
maintain the minimum CO slip, the inlet temperature will
need adjustment over the operational life of the catalyst.
However, it is important that the exit temperature should be
controlled to a maximum of 330°C (625°F) otherwise the
rate of deactivation through thermal sintering will become
unacceptably high.
Appendix 1: Product bulletins
25
PRODUCT BULLETIN
KATALCOJM 71-5
High temperature shift catalyst
Product benefits





High activity due to the use of a structural promoter to increase
gas diffusion rates
Improved strength and robustness, especially in the reduced
state, to give increased tolerance for upstream boiler leaks
Provides flexibility to operate at low steam ratio without
concern for side reactions (Fischer Tropsch)
A range of sizes to allow optimization of activity and pressure
drop in customized loading
Meets the most stringent of environmental requirements
Product uses

Used in the shift stage of ammonia, hydrogen and Towns Gas
plants to react CO with steam to produce H2 and CO2
General description

KATALCOJM™ 71-5 is a high activity copper promoted ironchrome catalyst
Physical properties
(typical)
KATALCOJM
71-5M
Pellet
5.4mm
3.6mm
3
1220kg/m
Form
Diameter
Length
Typical loaded density
Shipping & handling


KATALCOJM
71-5
Pellet
8.5mm
4.9mm
3
1190kg/m
Chemical composition
(Loss free basis, typical)
Fe2O3
Cr2O3
CuO
S
86wt%
9wt%
2.6wt%
<0.025wt%
Avoid contact with skin and clothing. Avoid breathing dust. Do
not take internally. Please refer to the relevant Material Safety
Data Sheet for further information
KATALCOJM 71-5 is available in non-returnable polythene
lined mild steel drums or bulk bags for easy loading
Note: This product bulletin provides typical physical and chemical properties of the above product. The
information in this document does not constitute a product specification.
PRODUCT BULLETIN
KATALCOJM 71-6
High temperature shift catalyst
Product benefits





Improved operational flexibility at reduced steam to carbon
ratios
High activity and high CO conversion at low operating
temperatures from enhanced pore structure
No strength loss during reduction and normal operation
Unrivalled resistance to boiler leaks through the highest inservice strength
Virtually zero shrinkage; the ultimate choice for radial flow
reactors and activity challenged reactors
Product uses

Used in the shift stage of ammonia plants to react CO with
steam to produce H2 and CO2
General description

KATALCOJM 71-6 is a high activity copper promoted ironchrome catalyst
Physical properties
(typical)
KATALCOJM
71-6M
Pellet
5.2mm
3.3mm
3
1365kg/m
Form
Diameter
Length
Typical loaded density
Shipping & handling


KATALCOJM
71-6
Pellet
8.3mm
4.8mm
3
1315kg/m
Chemical composition
(Loss free basis, typical)
Fe2O3
Cr2O3
CuO
S
88wt%
9wt%
2.6wt%
<0.025wt%
Avoid contact with skin and clothing. Avoid breathing dust. Do
not take internally. Please refer to the relevant material safety
data sheet for further information
KATALCOJM 71-6 is available in non-returnable polythene
lined mild steel drums or bulk bags for easy loading
Note: This product bulletin provides typical physical and chemical properties of the above product. The
information in this document does not constitute a product specification.
PRODUCT BULLETIN
KATALCOJM 83-3
Low temperature shift catalyst
Product benefits







High stable activity gives long lives with minimum slip of CO
Improved strength and robustness, especially in the reduced
state, gives greater resistance to the effects of plant upsets
Good poison resistance ensures the longest life possible and
avoids the need for low activity guard catalysts
High selectivity minimizes by-product methanol and amine
formation
Easy to activate and start-up
Expert reduction assistance minimizes reduction time and cost
Available in three sizes to allow optimization of activity and
pressure drop in customized loading
Product uses

Used in the shift stage of ammonia and hydrogen plants to
react CO with steam to produce H2 and CO2
General description

KATALCOJMTM 83-3 is a high activity catalyst based on
copper, zinc and alumina
Physical properties
(typical)
Form
Diameter
Length
Typical loaded density
Average crush strength
(axial)
Shipping & handling
Chemical composition
(Loss free basis, typical)
KATALCOJM
83-3
Pellet
5.2mm
3.0mm
1360kg/m³
KATALCOJM
83-3M
Pellet
3.1mm
3.1mm
1360kg/m³
KATALCOJM
83-3L
Pellet
8.2mm
5.6mm
1330kg/m³
220kgf
55kgf
380kgf


CuO
ZnO
Al2O3
51wt%
31wt%
Balance
Avoid contact with skin and clothing. Avoid breathing dust. Do
not take internally. Please refer to the relevant material safety
data sheet for further information
KATALCOJM 83-3 is available in non-returnable polythene
lined mild steel drums or bulk bags for easy loading
Note: This product bulletin provides typical physical and chemical properties of the above product. The
information in this document does not constitute a product specification.
PRODUCT BULLETIN
KATALCOJM 83-3X
Low temperature shift catalyst
Product benefits







Modified version of proven KATALCOJMTM 83-3 catalyst to
give extremely low methanol by-product
High activity gives long lives with minimum slip of CO
Good poisons resistance ensures the longest life possible and
avoids the need for low activity guard catalysts
High strength, especially in the reduced state, gives greater
resistance to the effects of plant upsets
Easy to activate and start-up
Choice of pellet sizes for optimum performance
Expert reduction assistance minimizes reduction time and cost
Product uses

Used in the shift stage of ammonia and hydrogen plants to
react CO with steam to produce hydrogen and CO2
General description

KATALCOJM 83-3X is a high activity catalyst based on
copper, zinc and alumina. It is promoted with alkali metals to
minimize by-product methanol and improve poison resistance
Physical properties
(typical)
Form
Diameter
Length
Typical loaded density
Average crush strength
(axial)
Shipping & handling


KATALCOJM
83-3X
Pellets
5.2mm
3.0mm
1360kg/m³
KATALCOJM
83-3MX
Pellets
3.1mm
3.1mm
1360kg/m³
190kgf
50kgf
Chemical composition
(Loss free basis, typical)
CuO
ZnO
Promoters
Al2O3
51wt%
31wt%
1.0wt%
Balance
Avoid contact with skin and clothing. Avoid breathing dust. Do
not take internally. Please refer to the relevant Material Safety
Data Sheet for further information
KATALCOJM 83-3X is available in non-returnable polythene
lined mild steel drums or bulk bags for easy loading
Note: This product bulletin provides typical physical and chemical properties of the above product. The
information in this document does not constitute a product specification.
PRODUCT BULLETIN
KATALCOJM 83-5
Isothermal shift catalyst
Product benefits





Enables the steam reformer to operate at low steam to carbon
ratio than possible with commercially available high
temperature shift catalysts
Good thermal stability allows stable operation of the Cu based
catalyst at temperatures in excess of 250oC (482oF) while
maintaining a close approach to equilibrium
High poisons capacity provides self-guarding capability
against trace poisons such as sulphur and chloride avoiding
the need for low activity guard catalysts
High strength, especially in the reduced state, provides
resistance to the effects of plant upsets
Simple activation procedure minimizes reduction time and
cost
Product uses

Used in the isothermal shift reactors, such as that used in the
LCA Ammonia Process
General description

KATALCOJMTM 83-5 is a high activity catalyst based on
copper, zinc and alumina
Physical properties
(typical)
KATALCOJM
83-5
Pellets
5.2mm
3.0mm
3
1300kg/m
210kgf
Form
Diameter
Length
Typical loaded density
Average crush strength
(axial)
Shipping & handling


KATALCOJM
83-5M
Pellets
3.1mm
3.1mm
3
1300kg/m
55kgf
Chemical composition
(Loss free basis, typical)
CuO
ZnO
Al2O3
52wt%
31wt%
Balance
Avoid contact with skin and clothing. Avoid breathing dust. Do
not take internally. Please refer to the relevant Material Safety
Data Sheet for further information
KATALCOJM 83-5 is available in non-returnable polythene
lined mild steel drums or bulk bags for easy loading
Note: This product bulletin provides typical physical and chemical properties of the above product. The
information in this document does not constitute a product specification.
PRODUCT BULLETIN
KATALCOJM 83-6
Adiabatic medium temperature shift catalyst
Product benefits





Enables the steam reformer to operate at low steam:carbon
ratio than possible with commercially available high
temperature shift catalysts.
Good thermal stability allows stable operation of the Cu based
catalyst even at the temperature experienced due to the
reaction exotherm.
High poisons capacity provides self-guarding capability
against trace poisons such as sulphur and chloride avoiding
the need for low activity guard catalysts.
High strength, especially in the reduced state, provides
resistance to the effects of plant upsets and condensing
conditions.
Simple activation procedure analogous to that for LTS
catalyst.
Product uses

Catalysis of the water gas shift reaction at medium
(intermediate) temperature in adiabatic reactors.
General description

KATALCOJMTM 83-6 is a high activity catalyst based on
copper, zinc and aluminium oxides.
Physical properties
(typical)
KATALCOJM 83-6
Pellets
5.4mm
3.6mm
1500kg/m³
250kgf
Form
Diameter
Length
Typical loaded density
Average crush strength
(axial)
Shipping & handling


Chemical composition
(Loss free basis, typical)
CuO
ZnO
Promoter
Al2O3
64wt%
24wt%
1.4wt%
Balance
Avoid contact with skin and clothing. Avoid breathing dust.
Do not take internally. Please refer to the relevant Material
Safety Data Sheet for further information.
KATALCOJM 83-6 is available in non-returnable polythene
lined mild steel drums or bulk bags for easy loading.
Note: This product bulletin provides typical physical and chemical properties of the above product. The
information in this document does not constitute a product specification.
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1098JM/0216/5/AMG