Research Gate catalyst article

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DOI: 10.13140/RG.2.2.22805.40168
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Ammonia Plant and Catalyst
Fellow of Institution of Engineers (India)
Abstract-
Catalyst is the heart of ammonia plants.
catalyst accelerates reaction by providing
alternate paths to products, the activation energy
of each catalytic step being less than that of no
catalytic reaction, in the reaction cycle, active
centers of catalysis first combine with at least
one reactant and then is reproduced with the
appearance of product. Equilibrium conversion
not altered by catalysts. The
radically alter selectivity. In chemical industry,
catalysts are used in order to bring some chosen
reaction as close as possible to a selected
equilibrium point in the shortest possible time
The rate of reaction is influenced by a substance
that remains chemically unaffected.
Keywords-Catalyst, poison, Reformer, ammonia
converter .HTS, LTS.
Mechanism
Consider the overall reaction,
a+b⇔c
Consider active centers/catalytic sites x1 and x2
which form complexes with
a and b and cycle proceeds like
1. a+x1⇔ax1.
2. b+x2⇔bx2.
3. ax1+bx2⇔c+x1+x2
Catalyst Mechanical properties
A large improvement in diffusion rate can be
achieved by using catalyst sizes and shapes
which expose more outside surface area. In S.R
the effective catalyst activity is proportional to
the exterior S.A per unit volume. Raschig ring
have more external S.A per liter catalyst stability
at reforming conditions. Alpha Alumina is us
as carrier. The Principle Characteristic
efficiency of catalysts depend upon,
Selectivity and Life. The ratio between
for desired and undesired reactions
19th
Sept, 2022
Research Gate is an academic social networking site
Ammonia Plant and Catalyst
By
Prem Baboo
Fellow of Institution of Engineers (India)
Catalyst is the heart of ammonia plants. A
by providing
alternate paths to products, the activation energy
of each catalytic step being less than that of no
catalytic reaction, in the reaction cycle, active
centers of catalysis first combine with at least
reproduced with the
Equilibrium conversion
catalyst can
In chemical industry,
order to bring some chosen
reaction as close as possible to a selected
uilibrium point in the shortest possible time.
The rate of reaction is influenced by a substance
.
Catalyst, poison, Reformer, ammonia
Consider active centers/catalytic sites x1 and x2
A large improvement in diffusion rate can be
zes and shapes
which expose more outside surface area. In S.R
the effective catalyst activity is proportional to
the exterior S.A per unit volume. Raschig ring
have more external S.A per liter catalyst stability
lpha Alumina is used
The Principle Characteristic-The
ciency of catalysts depend upon, Activity,
The ratio between activities
for desired and undesired reactions. Life is the
period during which the catalyst produces the
required product at a space time yield in excess
of or equal to that designated
of catalyst Efficiency-The exposed area in
contact with the fluid The intrinsic chemical
characteristics of surface of the solid
Topography of the surface
electronic structure etc. The occurrence of lattice
defects. When it contains more than one
chemical entity (supports or
stabilizers).Diffusion of reactant and products
within catalyst pellets , Diffusion of products in
to fluid stream.
The Sequence –
1. Transport of reactants from the bulk fluid to
the fluid solid interface.
2. Intra particle transport of reactants into the
catalyst particle.
3. Adsorption of reactants at interior sites of the
catalyst particle.
4. Chemical reaction of adsorbed reactants
adsorbed products (surface reaction
intrinsic chemical step).
5. .Desorption of adsorbed products
6. Transport of products from interior site to the
outer side of the catalyst.
7. Transport of products from the
interface into the bulk stream
1
period during which the catalyst produces the
product at a space time yield in excess
Influencing factor
The exposed area in
The intrinsic chemical
characteristics of surface of the solid The
Topography of the surface i.e., geometry,
The occurrence of lattice
When it contains more than one
chemical entity (supports or
Diffusion of reactant and products
Diffusion of products in
Transport of reactants from the bulk fluid to
Intra particle transport of reactants into the
Adsorption of reactants at interior sites of the
adsorbed reactants to
products (surface reaction-the
.Desorption of adsorbed products.
Transport of products from interior site to the
Transport of products from the fluid solid
interface into the bulk stream.

www.researchgate.net 19th
Sept, 2022
DOI: 10.13140/RG.2.2.22805.40168 Research Gate is an academic social networking site
2
Fig- Ideal catalyst requirements
Why LT Catalyst to be isolated immediately
after tripping? Because of Condensation of
steam on refractory oxides like Alumina
(stabilizer) will be weakened.
What is sintering? Deactivation caused by a
change in the surface structure of the catalyst.
Promoters and Inhibiters- Promoter-a substance
added during the preparation of a catalyst which
improves activity or selectivity or stabilizes the
catalytic agent so as to prolong its life Al2O3,
CaO, K2O.
Inhibitor- opposite to promoter.
Different Types of Poisoning
Deposited poisons: carbon deposition on
catalyst covers the active sites and partially
plugs the pore entrances---partially reversible.
Chemisorbed poisons: chemisorptions of
sulphur on Ni, Cu, Pt catalysts. if adsorption is
great, effect will be permanent.
Selectivity poisons: selectively lower activity of
cats
Stability poisons: effect of water vapor on the
structure of Alumina carrier. if temp increases
sintering ,localized melting leads to structural
failure
Diffusion poisons: blocking the pore mouths
Sulphur Poisoning in Ni Catalyst
Sulphur lowers the activity and decrease of
activity is proportional s content in feed stock.
The poisoning effect is reversible. A poisoned
catalyst soon recovers its full activity when
operated with feed stock containing
concentration below that level. It is always
desirable to keep s content less than 0.5ppm at
all times
Mechanism
3Ni+2H2S =Ni3S2+2H2 is not involved ,For bulk
sulphide formation ph2s/ph20 to exceed 1.0-10.0
but yet occurs at .01 or less. practically a 15% Ni
catalyst operating at 7750
C got poisoned when it
contains only 0.005% steaming for 12-24 hrs
without feed is very good remedy for this.
Arsenic: unlike sulphur as poisoning it is
permanent, source :CO2 removal section (not
applicable to more plants)
Other poisons-Halogens such as chloride and
others

DOI: 10.13140/RG.2.2.22805.40168
Must quality of catalyst
High activity, High selectivity, High
resistivity, High mechanical strength
resistance to poisons, Robust to plant
Long life.
Dream quality of Catalyst
1. Equilibrium approach-zero;
theoretical conversion
2. Life-very long: related mechanical
strength and activity
Fig- Ammonia Block diagram
Start up
1. Heat up Catalyst In Reducing N2/NG
To Normal Operating Temp 250
Rate Of 50O
c/hr
2. Pressure Is Maintained Between 5
15kg/cm2
3. Addition of Steam/H2
4. Hydrocarbon Feedstock is Added before
Temp is 250O
c is Reached In Catalyst
Bed. If H2 Is Used as A Heating Media.
19th
Sept, 2022
High thermal
mechanical strength, High
to plant upsets,
indicating
related mechanical
3. Required catalyst volume
stable activity
4. Mechanical strength-sufficient:
withstand handling and plant upset
5. Thermal stability-High:
sintering during service
6. Poison effect- Nil: for sustained activity
7. Effect of plant upset-
impair activity and stability
8. Steam/carbon ratio-theoretical:
energy consumption
Ammonia Process
Heat up Catalyst In Reducing N2/NG
To Normal Operating Temp 250O
c at A
Pressure Is Maintained Between 5-
Hydrocarbon Feedstock is Added before
c is Reached In Catalyst
Bed. If H2 Is Used as A Heating Media.
NG HDS
Catalyst features
Catalyst is suitable for hydroca
carbon oxides, due to low tendency of temporary
deactivationCO2 + 4H2 = CH
hydrogenates Olefins to saturated Hydrocarbons
and Organic Nitrogen compounds to Ammonia
and saturated hydrocarbons,C2
3
Required catalyst volume- minimum:
sufficient: To
withstand handling and plant upset
High: To prevent
for sustained activity
-nil: should not
impair activity and stability
theoretical: to reduce
Catalyst is suitable for hydrocarbons containing
carbon oxides, due to low tendency of temporary
= CH4 + 2H2O,Catalyst
hydrogenates Olefins to saturated Hydrocarbons
and Organic Nitrogen compounds to Ammonia
2H4+ H2 = C2H6

DOI: 10.13140/RG.2.2.22805.40168
Fig- Ammonia Plant
Start up
Heat up Catalyst In Reducing N2/NG To
Normal Operating Temp 250O
c at A Rate Of
50O
c/hr, Pressure is Maintained Between 5
kg/cm2
,Addition of Steam/H2,
Feedstock is Added before Temp is 250
Reached In Catalyst Bed. If H2 Is Used as a
Heating Media.
ZnO absorber
Reactor Filling: 1.200 mm Layer of
Balls Above The Catalyst Bed 2.100 mm Layer
of
½” Ceramic Balls Below the Catalyst Bed
Composition
ZnO = More than 99%, Al2O3 = Less than 1%
As = Less than 5ppm.,Size
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Sept, 2022
Heat up Catalyst In Reducing N2/NG To
c at A Rate Of
s Maintained Between 5-15
,Hydrocarbon
Temp is 250O
c is
Is Used as a
mm Layer of ½ “ Ceramic
.100 mm Layer
Catalyst Bed.
= Less than 1%,
Dia.= 3 to
4mm,Length=4 to 8mm,Shape
Extrudates, Volume = 30.0 m³ + 27m³ + ST
3m³,Operating temperature
400°C,Bulk Density=1.35kg/l,
Catalyst features
It is used for removal of hydrogen sulfide and to
some extent organic compounds depending upon
the operating temperature,
H2S+ZnO=ZnS+H2O, H2S reacts at ambient
temperature where as higher temperature is
required for heavier sulfur compounds
Sulfur pick up 39 kg/100 kg of c
ST-101
Placed at the bottom of R-3202B
Composition-Copper based, Size
Shape Tablets, Volume = 3.0 m³
4
Shape Cylindrical
= 30.0 m³ + 27m³ + ST-101
= 350°C to
,
hydrogen sulfide and to
some extent organic compounds depending upon
reacts at ambient
temperature where as higher temperature is
required for heavier sulfur compounds, Max.
pick up 39 kg/100 kg of catalyst.
3202B
based, Size 4X2.5 mm,
= 3.0 m³

DOI: 10.13140/RG.2.2.22805.40168
Fig-ZnO Absorber
A higher activity will result in close to CH
equilibrium at reformer exit or will maintain an
already close to eqm performance for longer
period, Higher activity can result in lower TWT
and hence longer tube lives
Q/A=U(tow-tg) radial temp profile heat transfer
equation
Carbon formation by CH4 crackin
operates with S/C less than 1.2-1.4
designed to take care of that. but in practical
conditions during plant upset carbon formation
occurs. common causes are , Low S/C ratio
Slugs of heavy HC in the feed
poisoning, Temp excursions resulting from
firing , control malfunctions. To counter this
19th
Sept, 2022
A higher activity will result in close to CH4
at reformer exit or will maintain an
already close to eqm performance for longer
Higher activity can result in lower TWT
and hence longer tube lives ,Consider
) radial temp profile heat transfer
cracking if plant
1.4 –plants are
but in practical
conditions during plant upset carbon formation
Low S/C ratio,
Slugs of heavy HC in the feed, Severe s
Temp excursions resulting from
To counter this
problem K2O has been added as promoter.
reduces c formation over standard Ni on
Alumina catalyst at temp above 450
speeds up the removal of any C
thermal cracking or other sources by catalyzing
the reaction- C+H2O→CO+H
disadvantage also. It reduces the catalyst
activity.
Pre-Reformer
Catalyst features
It converts all higher hydrocarbons in feed stock
into mixture of H2, CO,CO2
can be used with final boiling point up to 200°C
and aromatics below 30%,It is pre
passivated, therefore stable in air up to
5
has been added as promoter. it
reduces c formation over standard Ni on
Alumina catalyst at temp above 4500
C.K2O also
speeds up the removal of any C formed from
l cracking or other sources by catalyzing
→CO+H2, It has
reduces the catalyst
It converts all higher hydrocarbons in feed stock
and CH4,Naphtha
can be used with final boiling point up to 200°C
It is pre-reduced and
passivated, therefore stable in air up to

DOI: 10.13140/RG.2.2.22805.40168
70°C,under certain conditions MgO reacts with
MgO + H2O = Mg (OH)2 ,Conditions depends on
partial pressure of steam and temp.
temp. at 35kg/cm² is less than 400°C
Fig- PR Catalyst
Pre-Reformer
Endothermic reforming reactions are followed
by exothermic Methanation and shift reactions.
Overall reaction is endothermic if feed stock is
NG. Overall reaction is exothermic or thermo
neutral if feed stock is Naphtha. At temp.
490°C(around 470°) gum is formed as a result of
polymerization of hydrocarbons.
above max. Temp. (520°C) there i
formation of Olefins in the pre
Olefins prone to form Carbon in the coil or on
the catalyst.
Benefits of Pre-Reformer
It converts all higher hydrocarbons to CH
CO2 and H2 reducing the risk of Carbon
Natural gas 100
Naphtha 0
Min Nm3
,H2/kg HC Feed 0.03
Table –Gas/Naphtha ratio
In general, it is recommended to operate with as
high a hydrogen recycle rate as possible with
due consideration for the overall plant economy
1. Recycle gas is automatically added to the
pre reformer along with a minimum flow of
steam in case of a plant trip.
19th
Sept, 2022
certain conditions MgO reacts with steam to form Mg(OH)2
Conditions depends on
partial pressure of steam and temp. Hydration
at 35kg/cm² is less than 400°C
Endothermic reforming reactions are followed
by exothermic Methanation and shift reactions.
reaction is endothermic if feed stock is
Overall reaction is exothermic or thermo
At temp. Below
490°C(around 470°) gum is formed as a result of
. At temp.
. (520°C) there is risk of
formation of Olefins in the pre-heater coil.
Olefins prone to form Carbon in the coil or on
It converts all higher hydrocarbons to CH4, CO,
reducing the risk of Carbon
formation in Primary Reformer.
guard for the Primary Reformer Catalyst.
capacity can be increased if tube skin
temperature is the limiting factor.
consumption decreases if exit gas from the pre
reformer is re-heated before entering primary
reformer.
Activators
Catalyst is Delivered In Pre reduced Form
Heating up Catalyst with N
400o
C (Above The hydration limit) with primary
reformer. Steam with H2O/H2 <10 has been
Introduced. Hydrocarbon Should
without Delay to avoid the Oxidation of
Catalyst.
Minimum temperature
The minimum recommended temperature in the
RKNGR-7H pre reformer catalyst is related to
the temperature below which
will take place.
Gum is formed as a result of polymerization of
hydrocarbons. Gum formation is enhanced by
low temperature, low S/C ratio
recycle rate ,and heavy feed stocks.
of gum formation furthermore depends on the
composition of the naphtha feedstock there is
not only one limit to watch.
Hydrogen Recycle-In continuation of the above,
a minimum hydrogen recycle is required to
depress gum formation. The minimum recycle
rate depends on the natural gas/naphtha ratio as
shown in the below table.
80 60 40 20
20 40 60 90
0.08 0.11 0.14 0.17
In general, it is recommended to operate with as
high a hydrogen recycle rate as possible with
for the overall plant economy.
Recycle gas is automatically added to the
reformer along with a minimum flow of
2. A recycle gas flow rate corresponding to a
molar H2O/H2 ratio of < 10 is sufficient for
keeping RKNGR-7H reduced.
6
Reformer. It act as Sulfur
guard for the Primary Reformer Catalyst. Plant
capacity can be increased if tube skin
temperature is the limiting factor. Fuel
consumption decreases if exit gas from the pre-
heated before entering primary
Catalyst is Delivered In Pre reduced Form
Heating up Catalyst with N2/NG up to 350-
Above The hydration limit) with primary
/H2 <10 has been
Hydrocarbon Should be Added
without Delay to avoid the Oxidation of
The minimum recommended temperature in the
reformer catalyst is related to
the temperature below which Gum formation
f polymerization of
hydrocarbons. Gum formation is enhanced by,
low S/C ratio, low hydrogen
and heavy feed stocks. As the risk
of gum formation furthermore depends on the
composition of the naphtha feedstock there is
In continuation of the above,
a minimum hydrogen recycle is required to
depress gum formation. The minimum recycle
rate depends on the natural gas/naphtha ratio as
0
100
0.20
A recycle gas flow rate corresponding to a
10 is sufficient for
7H reduced.

Sept, 2022
7
3. If the plant is ready for an immediate restart
after the trip, the pre reformer can be kept on
line. However, the inlet temperature to the pre
reformer should not be allowed to drop below
the hydration limit of RKNGR-7H. In that case,
the pre reformer should be bypassed,
depressurized and purged with nitrogen as per
the normal shutdown procedure.
Primary Reformer
Composition (wt %)
Ni > 10%,SiO2 < 0.2%,K2O > 1.0 %,Carrier =
Balance (CaMgAl2O3) ,Shape& size=
Cylindrical with 7 holes,16/7H*18,Volume
Charged= 42.8m3,
operating temperature = 490°C
to 520°C,Bulk Density= 0.97kg/l.
Benefits
It is pre-reduced catalyst. It has unmatched
mechanical resistance to condensing steam and
liquid carry over. It has protection against
carbon lay down throughout catalyst life. It is
specially designed to minimize migration of
potassium promoter from ceramic carrier
RKNR
Composition (wt%)-Ni = 25%, Balance = MgO
& Al2O3, Size = 16X16 mm, Shape Rings,
Steam/Gas Ratio =0.85
Catalyst features
It is used in combination with R-67-7H to
reform hydrocarbons, It can reform Naphtha
with final boiling point below 200°C and
aromatics below 20%.RKNR is pre-reduced and
stable in open air up to 60°C.Does Not Loose
Strength And Activity When Subjected to
Steaming. Easily Reducible Hence Do Not Take
Time For Startup. High and Stable Activity Due
To Efficient Dispersion of Ni On Specially
Alumina Carrier. Top 10 to 20 cms layer of
porous alumina rings are placed to protect
against small droplets of water along with steam.
RKNR contains MgO which under certain
conditions may react with steam to form Mg
(OH)2.MgO + H2O = Mg (OH)2,If RKNR is
steamed at high temp. NiO will react with MgO
to form NiMgO which can be fully reduced only
at above 800°C. R-67R-7H (Pre reduced)
R-67-7H (unreduced)
Composition (wt %),NiO = 16 to 18% (Ni= 13
to 15% on reduction),Balance = MgAl2O3 (as
carrier),SiO2 < 0.2%.Size = 16x11 mm, Shape =
Cylindrical with 7 holes, Volume = 34.2 m³
Features
R-67R-7H catalyst which is in pre-reduced form
is charged above the unreduced catalyst R-67-
7H to speed up the reduction process. MgAl2O3
carrier is extremely stable at high and low
temperature. Final composition of the gas
leaving the reformer is largely determined by
S/C ratio, temperature and pressure.
Fig-Next generation catalyst

DOI: 10.13140/RG.2.2.22805.40168
Fig-Primary Reformer Tub
Reforming Reactions
CnHm+nH2O g nCO+(n+m/2)H2+Heat
CH4+H2O  CO+3H2-Heat
CO+H2O  CO2 +H2 +Heat
Catalyst poisons
Sulfur, Arsenic, Chlorides and Lead are the
poisons for the reformer catalyst whereas the
carbon formation on the catalyst surface
deactivates it.
Carbon forming Reaction
(A) Boudouard reaction
2CO  C + CO2
This reaction may occur in the temperature zone
of 450 to 800°C and depend on concentration
CO2 and CO.
(B) Methane cracking (Thermal cracking)
CH4  C + 2H2
19th
Sept, 2022
+Heat
Sulfur, Arsenic, Chlorides and Lead are the
poisons for the reformer catalyst whereas the
carbon formation on the catalyst surface
This reaction may occur in the temperature zone
on concentration of
(B) Methane cracking (Thermal cracking)
This reaction is possible in case of mal
or very low S/C ratio.
Reason for Carbon Lay down
If the catalyst is not properly reduced carbon
formation on the catalyst surface will take place.
If the catalyst is contaminated with sulphur, the
activity of catalyst is reduced to such an extent
that carbon is formed. Low S/C
also leads to carbon formation. Too
temp or too high violent firing in the top part of
the reformer will give high radial and axial
temp. Gradients which favors thermal cracking.
The higher the load, the higher will be the part
pressure of higher hydrocarbons at a given
temperature and consequently the risk of thermal
cracking. (Excessive load
formation).Prolonged use of catalyst
> Reduced activity of catalyst
formation
Lower CH4 equilibrium is
Higher exit temp, Higher s/c ratio
pressure
Start up-
Heating up Catalyst with NG/N
400o
C to 600o
C at a rate of 20o
temp is obtained it is allowed to get
Maintain these conditions for 12 hrs
temp to normal level .Stop synthesis gas
Pre-reformer is now on line.
Secondary Reformer
Reactor Filling: 200 mm Layer of 25
Alumina Lumps & 100 mm Layer of Alumina
Tiles above the Bed.
Alumina Lumps below the Bed
SCIL-C14-2
Composition (wt%),Ni = 8 to 10%
to 90%,SiO2 < 0.05%,S < 0.05%
< 0.1%,Size = 16x16x6 mm,
Rings, Volume = 39 m³,
1100kg/m3
, Radial Crush Strength
(DWL).CH4-H2O Equilibrium Approach
Expected Guarantee Life = 7-
Drop Normalized =0.94kg/cm
Expected =0.23 kg/cm2
, Steam
8
This reaction is possible in case of mal-operation
ay down
If the catalyst is not properly reduced carbon
formation on the catalyst surface will take place.
If the catalyst is contaminated with sulphur, the
activity of catalyst is reduced to such an extent
S/C ratio in reformer
formation. Too high feed
temp or too high violent firing in the top part of
give high radial and axial
which favors thermal cracking.
The higher the load, the higher will be the partial
pressure of higher hydrocarbons at a given
temperature and consequently the risk of thermal
cracking. (Excessive load -> carbon
Prolonged use of catalyst -> Ageing-
> Reduced activity of catalyst -> Carbon
Lower CH4 equilibrium is favoured by-
Higher s/c ratio, Lower exit
Catalyst with NG/N2 from 350-
o
C/hr, When 600o
c
temp is obtained it is allowed to get stabilize.
for 12 hrs, Reduce the
synthesis gas flow.
mm Layer of 25-50 mm
Alumina Lumps & 100 mm Layer of Alumina
Alumina Lumps below the Bed.
Ni = 8 to 10%,Al2O3 = 87
S < 0.05%,Heavy metals
, Shape = Ribbed
Bulk Density =
Crush Strength= 50kg
Equilibrium Approach =44o
C,
-8 Years, Pressure
=0.94kg/cm2
, Pressure Drop
Steam/Gas Ratio =0.6

DOI: 10.13140/RG.2.2.22805.40168
Risk of carbon formation during cooling
exit gas from Sec. Ref. Contains about 13mole%
CO and 7.3mole %CO2. Consequently there is a
theoretical risk of carbon formation according to
Boudouard reaction. 2CO  CO2
Fig- Secondary Reformer
Heating Up-Heating Up is Carried
Simultaneously with PR in Series
Introduced When Min Temp In SR Is 200
is Further Heated up with steam From Pr Up to
650-750 0
C At a Pressure. Of 5-15kg/cm
19th
Sept, 2022
Risk of carbon formation during cooling-The
exit gas from Sec. Ref. Contains about 13mole%
Consequently there is a
theoretical risk of carbon formation according to
+ C, to avoid
carbon formation the primary reformer
temperature should be maintained >721
Sec Ref outlet temperature should be maintained
>7760
C due to equilibrium conditions
s Carried out
PR in Series, Steam Is
uced When Min Temp In SR Is 2000
C, SR
is Further Heated up with steam From Pr Up to
15kg/cm2
,It Is
Reduced With Hot Effluent Gases PG & Steam
Mix From PR, During Reduction of SR,PR Load
Is Maintained 10-30%.,Process Air Is Introduced
In Secondary Reformer & Ensu
PR Load Shall Be Increased To 60% To Ensure
Complete Removal Of Sulphur
9
carbon formation the primary reformer Outlet
temperature should be maintained >7210
C and
Sec Ref outlet temperature should be maintained
C due to equilibrium conditions.
Reduced With Hot Effluent Gases PG & Steam
During Reduction of SR,PR Load
Process Air Is Introduced
In Secondary Reformer & Ensuring condition of
PR Load Shall Be Increased To 60% To Ensure
Complete Removal Of Sulphur.

DOI: 10.13140/RG.2.2.22805.40168
Fig- Secondary Reformer study and catalyst loading/unloading
HT Shift Converter
Catalyst Composition (wt%)
Fe2O3 = 85-90%, Cr2O3 = 7-9%, CuO
Al2O3 < 1.0 %,Cl < 0.01%,S = 0.015
Reactor Filling: 1.100 mm Layer of ½ ceramic
Balls below The Catalyst Bed, 2.100
Of ½” Ceramic Balls Above the Bed
Size = 6X6 mm, Shape = Solid cylindrical
tablet, Volume = 92 m³, Bulk Density
1.15kg/l, Radial Crush Load = 10 kg (DWL)
Specific Surface Area = 65-75 m2
/gm
Pore Volume = 0.23-0.25 ml/gm,
Approach = 0-10o
C, Expected Life = 5
Steam/Gas Ratio = 0.4-0.8, Space Velocity
4500 hr-,
Sintering Temp = >600o
C,
Ratio =0.49
19th
Sept, 2022
Secondary Reformer study and catalyst loading/unloading
, CuO = 1-2%,
< 1.0 %,Cl < 0.01%,S = 0.015
mm Layer of ½ ceramic
2.100 mm Layer
he Bed
= Solid cylindrical
Bulk Density =
= 10 kg (DWL),
/gm, Specific
, Equilibrium
= 5 -7 Years
Space Velocity =
C, Steam/Gas
Reaction-CO + H2O = CO2 + H
Features
It can take up to 200ppm of sulfur with no effect
on normal operation of the catalyst. Absorbed
sulfur releases slowly, leading to de
of LT shift catalyst. It contains Copper to avoid
over reduction.
Remarkable for Inhibition of Fisher Tropsch
Reaction at low S/G Ratio.
Lower Temperature, even as l
Poisoned By Sulphur in HTS feed Because Of
Low Sulphur Content-High Apparent
Excellent Thermal And Mechanical Stability
10
+ H2 + Heat
It can take up to 200ppm of sulfur with no effect
on normal operation of the catalyst. Absorbed
sulfur releases slowly, leading to de-activation
yst. It contains Copper to avoid
Remarkable for Inhibition of Fisher Tropsch
S/G Ratio. Can Operate at
as low As 300o
C, Not
Poisoned By Sulphur in HTS feed Because Of
High Apparent Activity,
Excellent Thermal And Mechanical Stability.

DOI: 10.13140/RG.2.2.22805.40168
Over reduction of catalyst
The catalyst is active magnetite Fe3
with 10% chromia. In HT shift catalyst there is a
possibility of over reduction of Fe3
to metallic iron. This will result in
Fig- HT Catalyst inspection & unloading
This results in side reactions for forming higher
hydrocarbons. Olefinic hydrocarbons are also
formed which tends to decompose leading to
carbon formation. This over reduction will result
in high pressure drop. D/S LT catalyst is also
affected by olefins and it also causes foaming in
CO2 scrubber and may contaminate the CO
stream. The amount of over reduction of the
catalyst is a function of the relative
concentration of the reducing components (
H2) to the oxidizing components (CO
19th
Sept, 2022
3O4 stabilized
with 10% chromia. In HT shift catalyst there is a
3O4 to FeO or
to metallic iron. This will result in degradation,
weakening and fracture of catalyst pellets and
will increase the pressure drop. If over reduction
takes place the iron oxide will get reduced to
iron carbides by the Fischer Tropsch reaction.
5Fe3O4+32CO  3Fe5C2 + 26 CO
HT Catalyst inspection & unloading
This results in side reactions for forming higher
Olefinic hydrocarbons are also
formed which tends to decompose leading to
over reduction will result
in high pressure drop. D/S LT catalyst is also
affected by olefins and it also causes foaming in
scrubber and may contaminate the CO2
The amount of over reduction of the
catalyst is a function of the relative
components (CO+
(CO2 + H2O) in
the gas phase, temp and pr. At lower S/C ratio at
primary Reformer will produce a higher conc. of
CO in the feed to HT and will lead to catalyst
over-reduction. To suppress the over reduction
Copper was incorporated with iron and chromia.
The presence of copper significantly increases
the relative rates around the surface of the
catalyst, thereby lowering the partial pressure o
CO and alleviating the possibility of over
reduction of catalyst.
11
weakening and fracture of catalyst pellets and
will increase the pressure drop. If over reduction
takes place the iron oxide will get reduced to
iron carbides by the Fischer Tropsch reaction.
+ 26 CO2
d pr. At lower S/C ratio at
will produce a higher conc. of
CO in the feed to HT and will lead to catalyst
ss the over reduction
Copper was incorporated with iron and chromia.
The presence of copper significantly increases
the relative rates around the surface of the
ereby lowering the partial pressure of
CO and alleviating the possibility of over

DOI: 10.13140/RG.2.2.22805.40168
Fig- HT catalyst loading
Start up - Heating Up with N2 or Natural
Further heating Up with Steam & Reducing
Agent
Addition of Hydrocarbon Feed.
LT CO Shift Converter
Ist
Bed Catalyst – PDIL: CDLT-21B
Composition (wt%)
19th
Sept, 2022
or Natural Gas,
Up with Steam & Reducing
21B
CuO = 35-37%, ZnO
(Al2O3 + Fe2O3) = Balances = 0.03% max.
= 6 dia*4 ht mm, Shape =Cylindrical
Volume = 66 m³
Reactor Filling:
100 mm Layer of ½ ceramic Balls below The
Catalyst Bed, 100 mm Layer o
Balls on the top of 1 bed only.
12
= 35-37%, R2O3
= 0.03% max. Size
=Cylindrical Tablets,
100 mm Layer of ½ ceramic Balls below The
Layer of ½ “Ceramic

DOI: 10.13140/RG.2.2.22805.40168
Fig- LT Catalyst unloading & Inspection
Specific Surface Area =85-90 M2
/gm
Specific Pore Volume =0.24-0.26ml/gm
Sintering Temp = >300 0
C
Space Velocity = up to 4000 hr-
Equilibrium Approach =5-25o
C
Pressure Drop =0.39 kg/cm2
2nd
Bed catalyst – SCIL : C18-7
Composition (wt%)
CuO= 35-45%, ZnO = 40-50%,
%, Graphite Synthetic = 1-5 %, S = 0.03% max.
Size = .8 X2.4 mm, Shape = Tablets
56 m³, Equilibrium Approach
Pressure Drop =0.50 kg/cm2
Operating Temperature - around 200°C
(Above condensing temperature of steam)
19th
Sept, 2022
LT Catalyst unloading & Inspection
/gm
0.26ml/gm
Al2O3 = 8-15
S = 0.03% max.
= Tablets, Volume =
Approach =6-29o
C,
around 200°C,
Above condensing temperature of steam)
Reaction-CO + H2O = CO
Poisons, Sulfur, Chlorides and Condensate
Steam/Gas Ratio= 0.45
Chloride contamination
Sources--Quality of steam (Quench System)
Feed gas,-Process Air (CW leakage)
of PAC.Special Features-High Activity With
Close Equilibrium Approach
Resistivity Towards Catalyst Poison Like
Sulphur, Chlorine Thermal
Crystal Growth Can Be Prevented With Special
Carrier Material, Superior In Mechanical
Stability, More Resistance T
Deactivation On Account o
Condensation.
13
O = CO2 + H2 + Heat,
Sulfur, Chlorides and Condensate,
Quality of steam (Quench System),-
Process Air (CW leakage),-Lubricants
High Activity With
Approach, Posses Greater
Resistivity Towards Catalyst Poison Like
Chlorine Thermal Sintering And
Crystal Growth Can Be Prevented With Special
Superior In Mechanical
More Resistance Towards
Deactivation On Account of Steam

DOI: 10.13140/RG.2.2.22805.40168
Fig- LT Catalyst Loading
Catalyst failure.
Probable reasons for catalyst failure 1
Failure – Chloride contamination
analysis after failure.1st
failure :
Pressure drop increased to >
1.5kg/cm2.
,Shutdown taken on 18th
April”03.Top
bed 1st
one meter found powdered , next on
meter was found sintered and the rest was in
original shape .LT 1st
bed catalyst was replaced
with C18-7.Ht’s top 15m3
catalyst was
19th
Sept, 2022
Probable reasons for catalyst failure 1st
Chloride contamination, Catalyst
failure : Date.-
Pressure drop increased to >
April”03.Top
one meter found powdered , next one
meter was found sintered and the rest was in
bed catalyst was replaced
catalyst was
replaced.5m3
chlorine guard catalyst was
charged at the top of ZnO bed.
Sr.
No.
Location
1 ZnO
2 HT 1st
bed top
3 HT at depth of 700mm
4 LT 1st
bed
5 LT 2nd bed
2nd
Failure : January,2004
started increasing by approx 0.01kg/cm
14
chlorine guard catalyst was
charged at the top of ZnO bed.
Chloride
173 ppm
0.64%
HT at depth of 700mm 0.08%
0.22-0.31%
320 ppm
Failure : January,2004,Pressure drop
started increasing by approx 0.01kg/cm2
per day ,

DOI: 10.13140/RG.2.2.22805.40168
HT catalyst was replaced with PDIL catalyst
catalyst was replaced with PDIL catalyst and
SCIL catalyst.
Probable reasons for catalyst failure (cont.)
2nd
Failure :-
No conclusive reason could be drawn as every
parameter was found normal :-
Pressure drop of 2nd
bed remained constant at
0.24kg/cm 2
,Cl-
at I/L LT< 0.01ppm
LT catalyst Poisoning
Poison Possible sources
Sulphur HC, Feed stock/Steam/Quench water low /New HTS
Catalyst
Chloride Air to Secondary reformer
Low
Silica Steam/Quench Low/Upstream catalyst bricks/Catalyst
support material
Table-Poisoning effect
Activation-
Catalyst is Activated by Reducing CuO
Heating with either N2 or NG to 170
pressure from 5-15kg/cm2
.& Allowed to
Stabilize. Flow Of H2 At a rate 0.5mole % Per
Step is Added, Inlet H2 Concentration is 2 mole
% should not be Exceed 2.2 mole %
This Condition for 22-24hrs,Increase The Top
Bed Temp to 220o
c at a rate of 15
Stabilize, Reduction will complete when H2
Consumption of 0.2 mole % is Verified For 2
hrs.
Methanator
Catalyst-
PK-5, Composition (wt %), Ni = 27%
Balance, Size = 5 to 6 mm, Shape
Volume = 30 m³, Bulk Density
19th
Sept, 2022
HT catalyst was replaced with PDIL catalyst, LT
catalyst was replaced with PDIL catalyst and
Probable reasons for catalyst failure (cont.)
No conclusive reason could be drawn as every
bed remained constant at
< 0.01ppm,S, Silica,
Phosphate at LT I/L-NIL,LT temp > dew point
(195degC),No indication from water ,steam and
PC balance, Cu and Zn = 45%
due to some side reactions in HT
acids, higher alcohols and higher aldehydes
could not be analyzed due to lack of provision.
At HT O/L Methanol = 50ppm
Formaldehyde =15ppm.
Effects
Feed stock/Steam/Quench water low /New HTS Cover active Copper Surface
Secondary reformer /HC feed stock/Steam/Quench Promote growth of Copper
crystals
Steam/Quench Low/Upstream catalyst bricks/Catalyst Physical blocking
surface.
alyst is Activated by Reducing CuO to cu by
Heating with either N2 or NG to 170o
c at a
.& Allowed to
At a rate 0.5mole % Per
Concentration is 2 mole
% should not be Exceed 2.2 mole %,Maintained
Increase The Top
c at a rate of 15o
c/hr and
will complete when H2
tion of 0.2 mole % is Verified For 2
= 27%, Al2O3 =
Shape = Rings,
Density= 0.56kg/l,
Carrier = Alumina, Operating Temp.
350°C,Reactor Filling: 1.100 mm Layer of ½
ceramic Balls Below The Catalyst Bed, 2.100
mm Layer Of ½ “Ceramic Balls o
Bed Only. Attrition loss - <5%
7500 hr-,Bulk Density-0.6 kg/Lit
Crush strength >8 Kg
SurfaceArea-50Kg/m2
,Co+CO
5/10,Colour , Grey/Black, S
0.005
Reaction--CO + 3H2 = CH4 + H
4H2 = CH4 +2H2O
Features-Low pressure drop, Surface area per
unit volume of catalyst is very high (250m²/gm)
Good resistance against poisoning
15
LT temp > dew point
No indication from water ,steam and
Cu and Zn = 45%.Failure may be
due to some side reactions in HT -Carboxylic
acids, higher alcohols and higher aldehydes
could not be analyzed due to lack of provision.
At HT O/L Methanol = 50ppm,At HT O/L
Cover active Copper Surface
Promote growth of Copper
Physical blocking of the catalyst
Operating Temp. = 300 to
1.100 mm Layer of ½
ceramic Balls Below The Catalyst Bed, 2.100
mm Layer Of ½ “Ceramic Balls on The top of 1
<5%,Space Velocity -
0.6 kg/Lit, Average
>8 Kg ,DWL, Specific
Co+CO2,Leakage(ppm)-
Steam/Gas Ratio -
+ H2O and CO2 +
Surface area per
unit volume of catalyst is very high (250m²/gm),
resistance against poisoning.

DOI: 10.13140/RG.2.2.22805.40168
Fig- Methanator
Temperature increase with 1% CO2 =
60°C,1% CO = 75°C,Poisons,Sulfur, Arsenic ,
K2CO3(physically blocks the catalyst) and
chlorine. Activation
Activation of PK5 Catalyst Consists of
Reduction of NiO-Ni, It Is Very Sensitive To S
so Check S Concentration <0.05ppm
Reduced By Getting Up in Normal PG At
Higher Possible Space
19th
Sept, 2022
1% CO2 =
Sulfur, Arsenic ,
blocks the catalyst) and
yst Consists of
Is Very Sensitive To S
so Check S Concentration <0.05ppm,
Reduced By Getting Up in Normal PG At
Velocity Rate of Heating is 50
From Ambient to 50 kg.cm2
.
3200
C.Activation completed within 8 hrs
Ammonia Synthesis Converter
KM-1 (Un-Reduced), Composition
Oxides = 93%,K2O+Al2O3
%,KM-1R (Pre-Reduced),Composition (wt%)
Fe + FeO = 91%,K2O+Al2O3+CaO+ SiO
Catalyst -Size = 1.5 to 3.0
Irregular granules, Volume = 29 +
80.3m³,Operating Temp., First Bed = 360 to
525°C,Second Bed = 370 to 460°C,Reaction
3H2 + N2 = 2NH3 + Heat
Bulk Density Kg/Lit - 2.15(KM1R), 2.75(KM1),
Space Velocity hr –
1500, Pressure Drop Kg/m
0.03/0.02for 1 & 2 Bed.
Features-KM-1R is pre-reduced and passivated
so it is stable in air up to 90 to 100°C
Sulfur, Phosphorous and Chlorides are
permanent poisons-Oxygen compound and
Water are temporary poisons
Activated By Heating In Normal Synthesis Gas
The Reduction Starts At 370
390o
C For KM1,Requires A Temp of 400
for a Couple If Days in order to complete the
catalyst reduction.
Handling & Using Catalyst on the Plants.
Catalysts to be handled as gently as possib
Drums contain cats should not be rolled, Care to
be taken during charging to avoid irregular
packing, Don’t allow to fall from height(> 1 m)
Precautions during Reduction Process
16
eating is 50o
C/hr & press.
.Reduction start at
Activation completed within 8 hrs.
Ammonia Synthesis Converter
Composition (wt%),Fe
3+CaO+ SiO2 =
Composition (wt%),
+CaO+ SiO2 = 9%
Size = 1.5 to 3.0 mm, Shape =
Volume = 29 +
First Bed = 360 to
525°C,Second Bed = 370 to 460°C,Reaction-
2.15(KM1R), 2.75(KM1),
1500, Pressure Drop Kg/m2
reduced and passivated
so it is stable in air up to 90 to 100°C,Poisons-
Sulfur, Phosphorous and Chlorides are
Oxygen compound and
Water are temporary poisons.Km/KMR Are
Normal Synthesis Gas,
The Reduction Starts At 370o
c for KM2 &
Requires A Temp of 400-425o
C
for a Couple If Days in order to complete the
Handling & Using Catalyst on the Plants.-
Catalysts to be handled as gently as possible,
Drums contain cats should not be rolled, Care to
be taken during charging to avoid irregular
packing, Don’t allow to fall from height(> 1 m)
Precautions during Reduction Process-

DOI: 10.13140/RG.2.2.22805.40168
Fig- S-200 along with S-50
PR catalyst, NiO----->Ni, HTS F
>fe3O4 HT cat should not be exposed to H
the absence steam even when they have been
reduced to fe2o3 as further reduction is
Its CuO with supports ----->cu temp max
Fig- Catalyst loading activities
19th
Sept, 2022
HTS Fe2O3------
HT cat should not be exposed to H2 in
the absence steam even when they have been
as further reduction is possible,
>cu temp max
2300
C sintering starts at 250
2800
C,Methanator -NiO---
200
C-300
Cper hr. Synthesis fe
special procedure.
17
ntering starts at 2500
C-
--->Ni heating rate
fe3O4----->Fe needs

DOI: 10.13140/RG.2.2.22805.40168
Fig Catalyst loading
What is pyrophoric?
It is thirsty nature for oxygen,
reduced state cats should be blanketed by an
inert gas preferably by N2.If N2 contains more
than 100ppm O2 care should be needed bed to be
cooled to 500
Cto before using such a Quality N
When the vessels contain nitrogen or some other
blanketing gas it is most important to ensure that
no person enters without proper breathing
equipment. Warning notices should be put at all
open manholes.
Safety Precautions
Hazards associated with the use of catalyst
1. Catalyst containing metallics Ni must not be
exposed to gases contain co at temp below.
Because it forms nickel carbonyl an extremely
toxic, odorless gas, which is stable at normal
temp. Possibility is in methanation reactors.
2. Physical hazards: during handling.
19th
Sept, 2022
thirsty nature for oxygen, So in their
reduced state cats should be blanketed by an
contains more
care should be needed bed to be
Cto before using such a Quality N2.
ogen or some other
blanketing gas it is most important to ensure that
no person enters without proper breathing
equipment. Warning notices should be put at all
Hazards associated with the use of catalyst
g metallics Ni must not be
exposed to gases contain co at temp below.
Because it forms nickel carbonyl an extremely
which is stable at normal
temp. Possibility is in methanation reactors.
3. Entering into the blanketed reactor without
breathing apparatus the end will come within
minutes.
4. Pyrophoric nature catalysts to be handled
carefully.
5. Some cats contain chrome .so dust mask is must.
But it must be made clear that a dust mask is not
a breathing apparatus, and is useless as a
protection against poisonous gases or in an
atmosphere lacking oxygen.
Conclusion
Day by day the ammonia plant for different
vessels catalysts are developing. New
technologies are coming. Ammonia catalysts
must enable more efficient
synthesis today than ever before. The revised
plant design is focusing more on ammonia
production and on-site delivery than originally
anticipated. The ammonia industry currently
18
o the blanketed reactor without
breathing apparatus the end will come within
Pyrophoric nature catalysts to be handled
Some cats contain chrome .so dust mask is must.
But it must be made clear that a dust mask is not
a breathing apparatus, and is useless as a
protection against poisonous gases or in an
Day by day the ammonia plant for different
vessels catalysts are developing. New
Ammonia catalysts
must enable more efficient ammonia
today than ever before. The revised
plant design is focusing more on ammonia
site delivery than originally
The ammonia industry currently

Sept, 2022
19
utilizes an energy-intensive production pathway.
With a growing demand on ammonia for the
production of chemical fertilizers, and increasing
volatility of feedstock prices and energy
resources, ammonia producers need reliable
solutions to succeed in this highly competitive
market. Both marginal and major improvements
can offer and will provide significant savings in
terms of increased production, efficiency, and
operational reliability.
************************************************************************************

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