The document discusses improvements in high temperature shift catalysts. It describes the characteristics and operational issues of traditional HTS catalysts and how the new VULCAN Series VSG-F101 catalyst has addressed these issues through modifications to its microstructure and composition. The VSG-F101 has shown improved activity, strength, and resistance to thermal and mechanical stresses during plant upsets compared to previous catalysts.

1. Performance & Operation
Improvements using VULCAN Series
VSG-F101 High Temperature Shift
Catalysts
By:
Gerard B. Hawkins
Managing Director, CEO

2. Improvements in High Temperature
Shift Catalysts
 The high temperature shift duty
 introduction and theory
 HTS catalyst characteristics
 developments over time
 Typical HTS operational problems
 Improved catalysts
 VULCAN Series VSG-F101 Series
 Summary

3. Improvements in High Temperature
Shift Catalysts
 The high temperature shift duty
 Introduction and theory
 HTS catalyst characteristics
 Typical HTS operational problems
 Improved catalysts and loading regimes
 Summary

4. Introduction
What is the Shift Reaction ?
 Water gas shift reaction has two effects:
• generates hydrogen from carbon
monoxide & steam
• converts CO to CO2
CO + H2O <=> CO2 + H2

5. From Steam
Reformer
HTS LTS Methanation
LTS
(optional)
H2
Introduction
How to include a Shift Section ?
Liquid
CO2
Removal
PSAHTS
From Steam
Reformer
H2

6. Theory - Equilibrium
CO + H2O CO2 + H2 (+ heat)
• Reaction is reversible
• Forward reaction - moderately exothermic
– equilibrium at lower temperature favors
• more CO converted
• more H2 produced
• Cannot beat equilibrium !

7. Theory - Reaction Rate
 Reaction Rate depends on
• distance from equilibrium
 further from equilibrium =>
larger driving force
• catalyst formulation/activity
• operating temperature
 Catalyst enables reaction to proceed
 Higher temperature drives rate
Ideal catalyst promotes rate to achieve
equilibrium at low temperature

8. Improvements in High Temperature
Shift Catalysts
 The high temperature shift duty
 HTS catalyst characteristics
 developments over time
 Typical HTS operational problems
 Improved catalysts and loading regimes
 Summary

9. High Temperature Shift
Operating Conditions
 Inlet CO 8 - 15 % / outlet CO 2 - 4 %
(dry)
 Bulk of CO conversion > 75 %
 Typical inlet temp of 335 - 360OC (640 -
680OF)
• recent improvements down to 300oC
(575oF)
 Temperature rise 55 - 65OC (100 - 120OF)
 Typical lives 3 - 5 years

10. High Temperature Shift
Catalyst Issues
 Over-reduction at low steam/dry gas
ratio
 Cr6+ content
 Sulfur content
 Activity
 Strength

11. High Temperature Shift
Modern Catalyst Features
 Iron/chromium/copper oxides catalyst
• typical composition 87 % / 10 % / 3% (wt)
 Active phase is magnetite, Fe3O4
• supplied as haematite, Fe2O3
• requires reduction
 Activity supplemented by Cu
• helps avoid over reduction of Fe3O4
 Low Cr6+ and SO4
2-
• typically < 50 (Cr) & < 300 ppmw (S) or better

12. High Temperature Shift
Catalyst Features
 To overcome the catalyst issues
• Over-reduction
 copper promotion
• Cr6+ content and sulfur content
 production route
• High stable activity & high strength
 dispersion of iron oxide, Cr2O3 and Cu crystallites
 low hexavalent chromium
 copper promotion
 micro-structure, particularly iron oxide
 catalyst pellet size options
VULCAN Series VSG-F101 incorporates all the
required features

13. High Temperature Shift
Catalyst Structure - General
Small crystals of magnetite
high surface area => high activity
Good dispersion of Cr2O3 (Cr3+)
gives strength to resist breakage in process
upsets (eg wetting)
gives high thermal stability
prevents sintering of Cu and Fe3O4
slows activity loss & increases life
Good dispersion of Cu
small crystallites => high Cu surface area =>
high activity
slows Cu sintering

14. 50-700 A pore
o
Chrome Oxide
Crystal
Iron Oxide Crystals
High Temperature Shift
Catalyst Structure
Cu Crystals

15. Amorphous Structure
(achieved in VSG-F101)
Microstructure of HTS Catalysts
Crystalline Structure
(Competitor)

16. HTS Catalyst - Addition of Copper
1. Activity
 Activity increase due to Cu addition
• much higher intrinsic activity than Fe3O4
• increases shift activity
 Benefits are
• at same SOR inlet temperature, maintain
equilibrium for longer - extend life
• achieve equilibrium at lower SOR inlet
temperature - lower CO slip, higher H2 make,
slower sintering (deactivation)
• for same SOR inlet temperature and life -
decrease catalyst volume

17. HTS Catalyst - Addition of Copper
1. Activity
 Cu issues - overcome by catalyst design
• Cu sinters rapidly at HTS operating
temperatures
• high Cu levels weaken catalyst structure
 => stabilize by the Fe3O4/Cr2O3 micro-
structure
• Pore diffusion controls overall reaction rate
 cannot achieve full benefit of Cu intrinsic
activity
 => optimize pore structure to maximize
benefit

18. HTS Catalyst - Addition of Copper
2. Over-reduction
 Fe3O4 => FeO => Fe
• causes increased Fischer-Tropsch activity
• C laydown (2CO <=> C + CO2)
 For over-reduction to occur
• need R ~ 1.5 or higher
• corresponds to S/C approx 2.8 in reformer
Reducing (CO)+ (H2)
Oxidising (CO2) + (H2O)
= Pc = R

19. HTS Catalyst - Addition of Copper
2. Over-reduction
 CO2/CO phase equilibrium
 Cu increases activity
• rapidly increases p[CO2]/decreases p[CO]
300 350 400 450 500 550
0.5
0.7
0.9
1.1
1.3
1.5
1.7
1.9
Temperature (oC)
P[CO2]/P[CO]
Fe
Fe3O4

20. HTS Catalyst - Addition of Copper
2. Over-reduction
 H2O/H2 phase equilibrium
• rarely close to boundary
• Cu tends towards lower temperature
operation
300 350 400 450 500 550
0.1
0.2
0.3
0.5
0.7
1
Temperature (oC)
P[H2O]/P[H2]
Fe
Fe3O4
FeO

21. High Temperature Shift
Chromium (VI) Issues
 Cr6+ content must be low
• Cr6+ can form during manufacture
 means less Cr2O3 so affects stability
• Cr6+ is a Category 1 carcinogen
• Cr6+ is water soluble
 can be washed out of catalyst into
condensate system (particularly during
start-ups)
 loss of catalyst strength
• upon reduction, Cr6+ gives an exotherm
 40OC (72OF) per 1%
 danger of over-temperature (catalyst;
vessel)

22. Low Cr6+ High Cr6+
High Temperature Shift
Chromium (VI) Issues
High Cr6+Low Cr6+
Boiling water testWater soak test
Low Cr6+ : typically < 10 ppmw

23. High Temperature Shift
Sulfur Removal Issue
 Sulfur source
• residual sulfate from metal salts used in
catalyst manufacture
 Sulfur problem during initial reduction
• liberate H2S during initial catalyst reduction
• poison for LTS catalyst or PSA absorbent
 vent exit gas to prevent poisoning
 if not, consumes up to 1 volume LTS catalyst
per 20 volumes HTS catalyst
• duration depends on catalyst sulfate level
• prolongs commissioning

24. High Temperature Shift
Sulfur Removal Issue
 Sulfur level
• depends on manufacturing route
 sulfate route (older) ~ 5000 ppmw
 nitrate route (newer) ~ 200 ppmw
 Effect of de-sulfiding on reduction time
• duration depends on catalyst type
 nitrate route: complete in ~4 hours
after process gas
 sulphate route: hold for 5 - 10 hours
extra

25. Improvements in High
Temperature Shift Catalysts
 The high temperature shift duty
 HTS catalyst characteristics
 Typical HTS operational problems
 Improved catalysts and loading
regimes
 Summary

26. HTS Operational Problems
Catalyst Start Up
 Exotherm on steam addition
• Temperature “spike” sometimes observed
 new HTS catalyst; all vendors
• often 100 oC (180 oF) and up to 250oC (450oF)
 Root cause analysis
• not understood for many years
• correlated with long hold on N2 flow at >> 200 oC
• catalyst surface becomes “super dry”
• steam re-hydrates surface (heat of hydration)

27. 1st Steam
Introduced
0 20 40 60 80 100
250
300
350
400
450
500
600
700
800
Time, minutes
Temperature(°C)
Temperature(°F)
Inlet
Top
Mid
Bot
Exotherm on Steam
New HTS Catalyst
Large European Plant

28. HTS Operational Problems
Catalyst Start Up
 Exothermic Rehydration Case Study
• VSG-F101 Series installed
• subsequent performance unaffected
• demonstrates good catalyst thermal
stability
 Rehydration phenomenon
• avoid by controlling drying conditions
during start-up

29. HTS Operational Problems
Catalyst Start Up
 Exotherm due to H2 ingress
• passing valve allowed H2 entry
 before reduction started
 on hold at 200+ oC
• new VSG-F101 Series installed
• significant exotherm
• subsequent performance unaffected
 on line > 4 years
• demonstrates good catalyst thermal
stability

30. HTS Operational Problems
Upstream Boiler Leaks
 Boiler leaks
• relatively common
• more likely at high plant rates
 Effects
• possible catastrophic catalyst failure due
to thermal shock
• pressure drop increase due to
 boiler solids fouling of the catalyst
 catalyst breakage (droplet
impingement)

31. HTS Operational Problems
Upstream Boiler Leaks
 Boiler leak case study - background
• large new Syngas plant
• Vulcan Series catalysts throughout
 including VSG-F101
• observed increase in HTS pressure drop
• data consistency check indicated showed
high steam ratio in the shift section
• boiler leak suspected

32. HTS Operational Problems
Upstream Boiler Leaks
 Boiler leak case study - actions/outcome
• catalyst inspected
• boiler leak confirmed
• catalyst skimmed
• plant restarted at 100% rate with 40%
less HTS catalyst
 space velocity increased to 9000 h-1
• catalyst still achieved maximum
conversion

33. HTS Operational Problems
Unplanned Catalyst Oxidation
 Exothermic Catalyst Oxidation
• activated (reduced) catalysts
 reacts with air rapidly and exothermically
 catalyst oxidizes with possible thermal
damage
 Case Study from a large syngas plant
• air machine delivery valve failed
• huge HTS catalyst temperatures increase
 middle = 635oC (1175oF) and exit = 540oC
(1100oF)
• temperatures stayed high ~30 minutes

34. HTS Operational Problems
Unplanned Catalyst Oxidation
 Catalyst Oxidation Case Study - outcomes
• catalyst activity impaired
 flatter reaction profile
 CO slip has increased from < 3% to
>4%
• VSG-F101 remains operable
 capable of an acceptable
performance until a convenient
change is planned
 despite significant over-temperature

35. Improvements in High Temperature
Shift Catalysts
 The high temperature shift duty
 HTS catalyst characteristics
 Typical HTS operational problems
 Improved catalysts
 VSG-F101 Series
 Summary

36. VSG-F101 Series
Step change improvement for HTS
 Launched almost three years ago
 Reformulated catalyst
• similar bulk composition to previous grades
• modified iron oxide pore structure
 patented use of acicular iron oxide
 Increased activity by 20%
• reduced diffusion limitation
 Increased in-service strength +100%

37. VSG-F101 Series
Properties
 Composition
 Fe
 Ni
 Cu
 (+ Al2O3 )
 Form
 VSG-F101 9 mm (dia) x 5 mm pellets
 VSG-F101 5 mm (dia) x 8 mm spheres
 Charged bulk density
 0.8-1.1 kg/l (50-69 lb /ft3)

38. VSG-F101 Series
Improved HTS Catalyst
 Structural promoter
• Improves strength
 better able to withstand plant upsets such
as boiler leaks
 higher strength through life
• Modifies pore structure
 wider pore distribution
 allows easier diffusion through wide pores
to high surface area active sites in small
pores
 increases activity

39. Structural
promoter
Micrograph showing catalyst enlarged x140,000
VSG-F101 Series
Modified Microstructure

40. RadialCrushStrength
(Kg/cm)
VSG-F101 Competitor A Competitor B Competitor C
0
2
4
6
8
10
12
VSG-F101 Series Reduced Strength
Crush strength after 2
weeks operation

41. Months on Line
0
0
10
20
30
40
50
10 20 30
Start of Leak
Comp. A
VSG-F101
Limit
VSG-F101 Comparison
Boiler Leak

42. Months in Operation
CatalystActivity
2
3
4
5
6
7
8
9
10 20 30 400
Design for
VSG-F101
Expected for
VSG-F101
Measured
Activity
VSG-F101 in a
Large Syngas Plant in China

43. VSG-F101 Large Size for Low Pressure
Drop
 VSG-F101DG
• 14 mm dia x 5 mm height domed pellets
• pressure drop is 40 % lower than VSG-
F101
• larger pellet => stronger
 better resistance to plant upsets
• activity ~90 % that of VSG-F101 at 360 oC
 THUS exceeds that of VSG-F101

44. Improvements in High Temperature
Shift Catalysts
 The high temperature shift duty
 HTS catalyst characteristics
 Typical HTS operational problems
 Improved catalysts and loading regimes
 Summary

45. Summary
 Fundamentals of HTS Catalysis
 HTS catalysts have improved
• VULCAN Series VSG-F101
 Operational issues still affect HTS
catalysts
• start up exotherms; boiler leaks;
catalyst breakage; reoxidation
 Active and robust VSG-F101 Series