Topsøe prereforming catalysts
MRPL Phase-III Refinery Project, Hydrogen Generation Unit
Outline
Topsøe prereforming technology and catalysts for
operational flexibility
Operational precautions
Evaluation of prereforming catalysts
Benefits of prereforming
Feedstock flexibility
– Naphtha
– Butane
– LPG
– LNG / Off-gas
All higher hydrocarbons will be converted
– H2, CO, CH4
Can operate on low S/C to save energy
Long lifetime of primary reformer catalyst
– No risk of carbon formation
– No risk of sulphur poisoning
Longer lifetime of MTS catalyst
Hydrogen plant
H2O
Hydrocarbon
feed
Steam reforming
Hydrogenation
temperature
Pre-reforming
absorption
Medium
Sulphur
shift
Off gas
H2
Pressure swing absorption
CnHm + nH2O → nCO + (n+m/2)H2
CO + H2O ↔ H2 + CO2
CO + 3H2 ↔ CH4 + H2O
Prereformer
1” Alumina balls
½” Alumina balls
RKNGR, 4.3x4.3
1” Alumina balls
Prereforming catalyst and inert material
Catalyst RKNGR
Shape Cylinder
Diameter, mm 4.0-4.5
Height, mm 3.9-4.5
Reduced Ni, wt % >20
Al2O3 + MgO, wt % Balance
Inert material Alumina
Shape Sphere
Diameter, inch ½
Diameter, inch 1
Al2O3, wt % >99
SiO2, wt % <0.2
Structure of Ni crystallite
Terrace site Ni(111),
0.20nm
Ni(200),
Step site 0.18nm
1mbar H2 at 500°C
Nature 427, 426 (2004)
Resistance to sintering
H2, 600°C
Topsøe prereforming catalysts
Catalyst AR-401 RKNGR
Feed NG/LPG/ROG Naphtha
Carrier MgAl2O4 MgO/Al2O3
Nickel, wt% >30 >20
Shapes 7-hole 11×6 and cylinders 4.5×4.5
Topsøe prereforming catalyst references
worldwide
80
70
60
No. of references
50
40
30
20
10
0
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Year
Typical installation H2O (optional)
Tubular
reformer
Prereformer
Waste heat channel
Feed
Steam
Operational precautions
Prevent sulphur poisoning
Prevent carbon formation
Prevent oxidation
Operate above hydration limit
Prevent sulphur poisoning
H2
Chlorine Chlorine
Absorption Absorption
HTG-1 HTG-1
Hydro-
genation Sulphur Sulphur
TK-250 Absorption Absorption
HTZ-3 HTZ-3
RSH + H2 → H2S + RH H2S + ZnO ↔ H2O + ZnS
Sulphur poisoning
Nisurface + H2S ↔ S-Nisurface + H2
Prevent carbon formation
Whisker carbon formation depressed by:
Lower temperatures
High steam/carbon ratios
High H2 recycle
Gum formation depressed by:
High temperatures
High steam/carbon ratios
High H2 recycle
Keep prereforming catalyst reduced
Special risk during start-up/shut-down/trip
1. If the catalyst is oxidized some of the sulphur picked up
on the catalyst in the top will be released
2. This sulphur will be picked up by the catalyst further
down in the bed
3. The overall catalyst activity will decrease when the
sulphur is distributed to a larger part of the bed
Operate above hydration limit
Equilibrium Steam Pressure for
MgO + H2O ↔ Mg(OH)2
Log(PH O ) = -4676/T - 1.54 log(T) + 12.57
2
– P = partial steam pressure (atm)
H2O
– Tiiii = temperature (K)
Operation of Topsøe prereforming catalysts
Simple loading in adiabatic reactor
Prereduced catalysts for easy
start-up
Visual monitoring of performance
with Z90 plot
Measure slip of HHC
Follow ∆P across reactor
Temperature
Naphtha
T
LPG
Natural gas
0 Bed depth, % 100
Prereformer evaluation
Check pressure drop across the prereformer
– Evaluate the trend
Deactivation rate evaluation
– Use Z90 method
Remaining catalyst life time estimation
– Based on Z90 plot
The Z90 method gives a quick warning if sulphur leakage
from the desulfurization section should increase
Natural gas based plant – evolution in profiles
520
500
Temperature, °C
0 Days
137 Days
480 601 Days
1115 Days
T90
460 Z90
440
0 20 40 60 80 100
Bed height, %
Natural gas based plant – temperature profile
540
TInlet
520
Temperature (°C)
500
480 TExit
T90
460
0 20 Z90 40 60 80 100
Height of bed, %
Natural gas based plant – evaluation with Z90
80
60
Z90, %
40
20
0
0 20 40 60
Age, months
Temperature profiles in a naphtha prereformer
using RKNGR
500
490
1 9 13 22
Temperature (°C)
480
470
460
1 Time on-stream (months)
450
440
0.0 0.2 0.4 0.6 0.8 1.0
Relative distance in catalyst bed
Temperature profile for the prereformer in a
naphtha based plant
495
T90
TExit
490
∆T90
Temperature (°C)
∆T
485
480
TMin
475
Z90
470
0 20 40 60 80 100
Naphtha based plant – evaluation with Z90
80
60
Z90, %
40
20
0
0 20 40 60
Summary
Topsøe prereforming catalysts are high activity nickel
catalysts with excellent carbon resistance
Stable carrier material limits sintering
Deactivation is diminished by avoiding poisoning of the
catalyst – caution against sulphur poisoning is essential
Following the development in temperature profiles with
Z90 plot enables actions against poisoning
