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Fall 2003
Hydrocarbon Processes in the Oil Refinery
Prof. Dr. J.A. Moulijndr.ir. M. Makkee
Industrial CatalysisDelftChemTech
Delft University of TechnologyThe Netherlands
http://www.dct.tudelft.nl/race
TTUUDelftDelft &CER
Hydrocarbon processes in the Oil RefineryContent Lectures
*
CARE, Chemical Process Technology lectures background knowledge
•• Chemical Process Technology, Wiley, 2001Chemical Process Technology, Wiley, 2001J. A. J. A. MoulijnMoulijn, M., M. MakkeeMakkee, A.E. van , A.E. van DiepenDiepen
»» Chapter 2, Crude oil compositions (2.3.3) Chapter 2, Crude oil compositions (2.3.3) »» Chapter 3, Processes in the Oil RefineryChapter 3, Processes in the Oil Refinery»» Chapter 5, Synthesis Gas (5.1, 5.2, and 5.4) Chapter 5, Synthesis Gas (5.1, 5.2, and 5.4) »» Chapter 6, Fischer Chapter 6, Fischer TropschTropsch (6.3) (6.3)
•• Lecturing notes Lecturing notes -- Speakers from IndustrySpeakers from Industry
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Programme
Up to 29 September Lectures Moulijn/Makkee30 September Dr. H.P.A. Calis (Shell)
Fischer Tropsch
6 October ir. A. Rooijmans (ExxonMobil)Flexicoking
7 October dr. F. Plantenga (Akzo-Nobel)Hydrotreating + Alkylation
13 October ir. H. van Wechem (Shell)Upgrading Shell Pernis Refinery (Per+)
14 October Dr. R. Antonelli (UOP)Trends for the future Refinery
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Oil refinery; an overview
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Introduction
•• Chapter 2 Chapter 2 –– Composition crude oilComposition crude oil
•• Chapter 3Chapter 3–– RefineryRefinery
»» Relatively mature optimised plantsRelatively mature optimised plants•• Nevertheless changesNevertheless changes
–– MarketMarket–– LegislationLegislation
»» Some 600 worldwideSome 600 worldwide»» Large volumesLarge volumes»» Very instructive example chemical process Very instructive example chemical process
technologytechnology
TTUUDelftDelft &CER
Modern oil refinery
Crude oil
Straight run gasoline
LPG and Gas
Naphtha
Hydro-treating
Reformate
Middle distillates
Heavy atm. gas oil
Solventextraction
Lube base stocks
Gasoline
Vacuum gas oil
Solventdewaxing
Lube oils
Waxes
Gasoline, Naphtha, Middle distillates
Gasoline, Naphtha, Middle distillates
Gasoline, Naphtha, Middle distillates
Slurry oil
Refinery fuel gas
LPG
Gasoline
Solvents
Kerosene
Diesel
Heating oil
Lube oil
Greases
Asphalt
Industrial fuels
Coke
Trea
ting
and
Blen
ding
Delayed coker / Flexicoker
Propanedeasphalter
Hydro-treating
Catalyticreforming
Catalyticcracking
Visbreaker
Hydro-cracking
Fuel oil
Asphalt
LPG and Gas
Cycle oil
Alkylation AlkylateLPG
Hydro-treating
Vacu
umD
istil
latio
nAt
mos
pher
icD
istil
latio
n
TTUUDelftDelft &CER
Distillation FractionsDistillate fraction Boiling point
(oC) C-atoms/ molecule
Gases <30 1-4 Gasoline 30-210 5-12 Naphtha 100-200 8-12 Kerosine (jet fuel) 150-250 11-13 Diesel, Fuel oil 160-400 13-17 Atmospheric Gasoil
220-345
Heavy Fuel Oil 315-540 20-45 Atmospheric Residue
>540 >30
Vacuum Residue >615 >60
MiddleDestillates
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Chemical processesThermal Catalytic
Visbreaking HydrotreatingDelayed coking Catalytic reformingFlexicoking Catalytic cracking
HydrocrackingCatalytic dewaxingAlkylationPolymerizationIsomerization
Processes in an Oil Refinery
Physical processes
DistillationSolvent extractionPropane deasphaltingSolvent dewaxingBlending
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Physical Processes
TTUUDelftDelft &CER
620 K
C1 - C4
Gases
Gasoline
Kerosene
Gas oil
ResidueCrude oil
steam
steam
steam
reflux water
Fractionator Stripper StripperFurnace
Simple Crude Distillation
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Market Demands
•• Clean products (no S, N, O, metals, etc.)Clean products (no S, N, O, metals, etc.)•• More gasoline (high octane number)More gasoline (high octane number)•• More diesel (high cetane number)More diesel (high cetane number)•• Specific products (Aromatics, alkenes, etc.)Specific products (Aromatics, alkenes, etc.)•• Less residueLess residue
•• How to meet these demands?How to meet these demands?•• More sophisticated distillationMore sophisticated distillation•• Physical separation stepsPhysical separation steps•• Chemical conversion stepsChemical conversion steps
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C1 - C4
Gases
620 K
Gasoline
Kerosene
Gas oil
ResidueCrude oil
steam
steam
steam
reflux water
Fractionator Stripper StripperFurnace
More sophisticated ???Higher T Higher T ddiistillationstillation ????
TTUUDelftDelft &CER
Modern Crude Distillation UnitCrude Oil
Intermediate gas oil
Gases
reflux water
vacuumsteam
vacuum
Heavygas oil
Slops
Gasoline
vacuum residue
Kerosene
Lightgas oil
steam
Mainfractionator
Strippers Mild vacuumcolumn
Driers
circulating reflux
circulating reflux
FurnaceFurnace
TTUUDelftDelft &CER
Modern oil refinery
Crude oil
Straight run gasoline
LPG and Gas
Naphtha
Hydro-treating
Reformate
Middle distillates
Heavy atm. gas oil
Solventextraction
Lube base stocks
Gasoline
Vacuum gas oil
Solventdewaxing
Lube oils
Waxes
Gasoline, Naphtha, Middle distillates
Gasoline, Naphtha, Middle distillates
Gasoline, Naphtha, Middle distillates
Slurry oil
Refinery fuel gas
LPG
Gasoline
Solvents
Kerosene
Diesel
Heating oil
Lube oil
Greases
Asphalt
Industrial fuels
Coke
Trea
ting
and
Blen
ding
Delayed coker / Flexicoker
Propanedeasphalter
Hydro-treating
Catalyticreforming
Catalyticcracking
Visbreaker
Hydro-cracking
Fuel oil
Asphalt
LPG and Gas
Cycle oil
Alkylation AlkylateLPG
Hydro-treating
Vacu
umD
istil
latio
nAt
mos
pher
icD
istil
latio
n
TTUUDelftDelft &CER
Propane DeasphaltingExtraction
ReasonReasonCokeCoke--forming tendencies of forming tendencies of asphaltenicasphaltenic materialsmaterials
How?How?Reduction by Reduction by extraction withextraction with suitable solventsuitable solvent
propane propane butane, pentanebutane, pentane
Why propane?Why propane? Conditions?Conditions? Flow scheme?Flow scheme?Easy separationEasy separationAvailableAvailable......
Modest temperatureHigh pressure
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Propane Deasphalting
Deasphalted oil
Vacuum residue
Liquid propane
Asphalt
Propane recycle
Flash drumDeasphalting tower Strippers
Steam
Steam
Condensers
Steam condenser
Water
Propane storage
Make-up propane
310 - 330 K35 - 40 bar
Steam
Propane evaporatorCond.
TTUUDelftDelft &CER
Modern oil refinery
Crude oil
Straight run gasoline
LPG and Gas
Naphtha
Hydro-treating
Reformate
Middle distillates
Heavy atm. gas oil
Solventextraction
Lube base stocks
Gasoline
Vacuum gas oil
Solventdewaxing
Lube oils
Waxes
Gasoline, Naphtha, Middle distillates
Gasoline, Naphtha, Middle distillates
Gasoline, Naphtha, Middle distillates
Slurry oil
Refinery fuel gas
LPG
Gasoline
Solvents
Kerosene
Diesel
Heating oil
Lube oil
Greases
Asphalt
Industrial fuels
Coke
Trea
ting
and
Blen
ding
Delayed coker / Flexicoker
Propanedeasphalter
Hydro-treating
Catalyticreforming
Catalyticcracking
Visbreaker
Hydro-cracking
Fuel oil
Asphalt
LPG and Gas
Cycle oil
Alkylation AlkylateLPG
Hydro-treating
Vacu
umD
istil
latio
nAt
mos
pher
icD
istil
latio
n
TTUUDelftDelft &CER
Thermal Processes
TTUUDelftDelft &CER
Thermal Processes
Feedgasoilcoke
Furnace
T, tres
Visbreaking•mild conditions
Delayed Coking•long residence time (24 h)
Flexicoking•combination thermal cracking and coke gasification/combustion
Steam Cracking•production lower olefins
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Thermal Processes
•• VISBREAKINGVISBREAKING–– Mild thermal crackingMild thermal cracking–– Reduction of viscosityReduction of viscosity
•• DELAYED COKINGDELAYED COKING–– Long residence times (24 h)Long residence times (24 h)–– Heavy feed Heavy feed →→ coke + oil + gascoke + oil + gas
•• FLEXICOKINGFLEXICOKING–– Combination of thermal cracking and Combination of thermal cracking and –– coke gasification / combustioncoke gasification / combustion
TTUUDelftDelft &CER
~ 10 wt%
~ 80 wt%
Vacuum residue
Cracked residue
Heavy gas oil
Fractionator Vacuum fractionator
Gasoline
FlashReactor
Light gas oil
730 K20 bar
Furnace
Visbreaking
TTUUDelftDelft &CER
UnstabilizedNaphtha
Gas
Furnace Fractionator
CokeFeed
Coke drums Gas oil stripper
Gas oil
2 bar
770 K
710 K
Delayed Coking
TTUUDelftDelft &CER
Catalytic Processes
TTUUDelftDelft &CER
Market Demands
•• Clean products (no S, N, O, metals, etc.)Clean products (no S, N, O, metals, etc.)•• More gasoline (high octane number)More gasoline (high octane number)•• More diesel (high cetane number)More diesel (high cetane number)•• Specific products (Aromatics, alkenes, etc.)Specific products (Aromatics, alkenes, etc.)•• Less residueLess residue
•• How to meet these demands?How to meet these demands?•• More sophisticated distillationMore sophisticated distillation•• Physical separation stepsPhysical separation steps•• Chemical conversion stepsChemical conversion steps
TTUUDelftDelft &CER
Octane Numbers, Boiling Points•• nn--pentanepentane 6262 309 K309 K•• 22--methyl butanemethyl butane 9090 301301•• cyclopentanecyclopentane 8585 322322•• nn--hexanehexane 2626 342342•• 2,22,2--dimethylbutanedimethylbutane 9393 323323•• benzenebenzene >100>100 353353•• cyclohexanecyclohexane 7777 354354•• nn--octaneoctane 00 399399•• 2,2,32,2,3--trimethylpentanetrimethylpentane 100100 372372•• methylmethyl--tertiarytertiary--butylbutyl--etherether 118118 328328
•• straight run gasolinestraight run gasoline 6868 67 (MON)67 (MON)•• FCC light gasolineFCC light gasoline 9393 8282•• alkylatealkylate 9595 9292•• reformate reformate (CCR)(CCR) 9999 8888
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Cetane Numbers•• nn--alkanesalkanes 100100--110110•• nn--hexadecane (cetane)hexadecane (cetane) 100100•• isoiso--alkanesalkanes 3030--7070•• alkenesalkenes 4040--6060•• cycloalkanescycloalkanes 4040--7070•• alkylbenzenesalkylbenzenes 2020--6060•• naphtalenesnaphtalenes 00--2020•• αα--methyl methyl naphtalenenaphtalene 00
•• straight run gas oilstraight run gas oil 4040--5050•• FCC cycle oilFCC cycle oil 00--2525•• thermal gas oilthermal gas oil 3030--5050•• hydrocracking gas oilhydrocracking gas oil 5555--6060
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Fluid Catalytic Cracking (FCC)
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CH2 C CH3C+H3CCH3 CH3
CH3
H3C CCH3
CH2 + C CH3
CH3
CH3+
Catalytic Cracking
•• World capacity: > 500 million metric ton/yearWorld capacity: > 500 million metric ton/year
•• Reactions:Reactions:–– CC--C bond cleavage:C bond cleavage:–– IsomerizationIsomerization–– ProtonationProtonation//deprotonationdeprotonation–– AlkylationAlkylation–– PolymerizationPolymerization–– CyclizationCyclization, condensation , condensation coke formationcoke formation
“β scission”
TTUUDelftDelft &CER
+ H + o rC H C H 2R C H 2 C +RH
HR C + C H 3
H
Alkenes:
via carbenium ions
Stability: tertiary > secondary > primary > ethyl > methyl
+ H+ C +RH
HHC H3 + H2C H2 C H3R R C + C H3
H
Alkanes:
via carbonium ions
Or, if carbenium ions are present:
C H 2 C H 2 C H 3C +H 3CC H 3
H 3C C C H 2 C H 2 C H 2 C H 3
H
H
+
+
H 3C C C H 2 C H 2 C H 2 C H 3
H
C H 2 C H 2 C H 3C HC H 3
H 3C+
Cracking Mechanism
TTUUDelftDelft &CER
+
H3C CH2 CH2 CH2 CH2 CH2 CH3
H3C CH CH3
CH3
H3C CH CH2 CH2 CH2 CH2 CH3
H3C CHCH2
CH CH3CH2CH2
H+
CH CH3H2C
H3C CH CH3
CH3
H3C CH CH CH2 CH2 CH3
CH3
+
hydride shifts +C-C bond breaking
hydride transfer
Isomerization
etc.
Protonated cyclopropane
Classical carbenium ion
Initation
n-Alkene
n-Alkane
iso-Alkane
+
+
Mechanism of cracking of alkanes
Count the Hs! What is wrong??
TTUUDelftDelft &CER
Product DistributionThermal versus Catalytic Cracking
0
20
40
60
80
100
120
140
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Carbon Number
mol
per
100
mol
cra
cked
n-C
16 Thermal
Catalytic
TTUUDelftDelft &CER
Modern oil refinery
Crude oil
Straight run gasoline
LPG and Gas
Naphtha
Hydro-treating
Reformate
Middle distillates
Heavy atm. gas oil
Solventextraction
Lube base stocks
Gasoline
Vacuum gas oil
Solventdewaxing
Lube oils
Waxes
Gasoline, Naphtha, Middle distillates
Gasoline, Naphtha, Middle distillates
Gasoline, Naphtha, Middle distillates
Slurry oil
Refinery fuel gas
LPG
Gasoline
Solvents
Kerosene
Diesel
Heating oil
Lube oil
Greases
Asphalt
Industrial fuels
Coke
Trea
ting
and
Blen
ding
Delayed coker / Flexicoker
Propanedeasphalter
Hydro-treating
Catalyticreforming
Catalyticcracking
Visbreaker
Hydro-cracking
Fuel oil
Asphalt
LPG and Gas
Cycle oil
Alkylation AlkylateLPG
Hydro-treating
Vacu
umD
istil
latio
nAt
mos
pher
icD
istil
latio
n
TTUUDelftDelft &CER
Mechanism: HMechanism: H++ donor or Hdonor or H-- acceptor acceptor acid sitesacid sites
Catalysts for FCC
OriginallyOriginally•• AlClAlCl33 solution:solution:
–– corrosioncorrosion–– waste streamswaste streams
SubsequentlySubsequently•• Clays (acidClays (acid--treated)treated)•• Amorphous silicaAmorphous silica--aluminaalumina
–– more stable and more selectivemore stable and more selective–– better pore structurebetter pore structure–– better attrition stabilitybetter attrition stability
•• ZeolitesZeolites–– even more active and stableeven more active and stable
»» less coke, higher thermal stabilityless coke, higher thermal stability
TTUUDelftDelft &CER
-
-
silica-alumina:
silica:
SiO
OO
Si
Si
Si SiO
OOO
Si
Si
SiOH H++
OO
O
Si
Si
SiO
OOO
Si
Si
Si H++Al HO Si Al Si
Weak acid
Strong acid
Cracking Catalysts
TTUUDelftDelft &CER
• Large number found and/or synthesized
• Total porosity up to 0.5 ml/g
• Examples
Supercage0.8 nm
Sodalite cage
FAU
SOD
LTA
Y (Faujasite)Zeolite A
Sodalite
Zeolites
TTUUDelftDelft &CER
FCC process
•• Catalyst Catalyst zeolitezeolite–– Small poresSmall pores–– Particle size??Particle size??–– Reactor?Reactor?
•• Product distributionProduct distribution–– Broad mixture, including Broad mixture, including cokcokee
•• ThermodynamicsThermodynamics–– Exothermal, Exothermal, endothermalendothermal??–– Temperature?, pressure?Temperature?, pressure?
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RECl3, NH4Cl
Wash liquor
Sodium silicate
Sodium aluminate
Water
NaOH
Al2O3 source
SiO2 source
Water
NaOH
Na zeolitecrystallization
Silica-aluminasynthesis
Filter Dryer
Mixer
Ion exchange
FCC catalyst particles
Spray dryer
Matrix material
Zeolite
matrixzeolite (dp = 2-10 µm)
50-70 µm
Micro pores < 3 nmMeso pores 3 - 50 nmMacro pores > 50 nm
Production of FCC catalyst
TTUUDelftDelft &CERRegeneration by coke combustion
provides heat
0
20
40
60
80
100
1950s 1960s 1970s 1980s
% w
t on
feed
Gas
LPG
Gasoline
LCO
HCO/slurry
Coke
Amorphous ZeoliteLow Al High Al REY USY
Product Distribution of Gas Oil Cracking
• Coke– Carbon deposited
– Catalyst poisoned on s scale
Coke“Mixed Blessing”
Process Design?
TTUUDelftDelft &CER
FCC: Fluidized-bed Reactor and Regenerator
Latermuch moreactive catalyst
Consequencesfor process?
Cracking
C + O2→ CO / CO2
Air
Flue gas
Spent catalyst
Regenerated catalyst
Feed
To fractionation
970 K
775 K
SteamGrid
2-stage Cyclones
Regenerator Reactor
Riser
Fluidized bed
Fluidized bed
2-stage Cyclones
Pros and cons fluid beds??
TTUUDelftDelft &CER
Modern FCC Unit: Riser Reactor
waste heat boiler
compression
expansion
catalyst fines
propane
propene
butane
butene
L/L sep.water
G/L sep.gas (C2 and lighter)
slurry oil
light cycle oil
heavy cycle oil
flue gas
spent cat.
regenerated cat.
steam
riser
steam
cyclones
FeedAir
Gasoline
Regenerator Reactor Fractionator Absorber Debu-tanizer
Depro-panizer
TTUUDelftDelft &CER
Reactor Regenerator
Temperature (K) 775 973
Pressure (bar) 1 2
Residence time 1-5 s minutes/half hour
Typical Conditions in Riser FCC
TTUUDelftDelft &CER
0 20Time (s)
Cat
alys
t fra
ctio
n (a
.u)
Total area = 1
Riser Reactor: Plug flow Reactor??Residence Time Distribution ?
TTUUDelftDelft &CER
4.5
5
5.5
6
6.5
7
1960 1965 1970 1975 1980 1985 1990 1995
Year
Feed
thro
ughp
ut (m
illion
bar
rels
/day
)Capacity required with amorphous catalysts(extrapolated)
Capacity with zeolitic catalysts(actual situation)
Catalytic Cracking Capacity in the US
TTUUDelftDelft &CER
Sulfur Distribution in FCC Products•• Capacity: Capacity: 50000 barrels /day50000 barrels /day•• catalyst / oil ratio: catalyst / oil ratio: •• Catalyst inventory: Catalyst inventory: •• Catalyst Catalyst recirculationrecirculation rate: rate: •• feedstockfeedstock sulfursulfur content:content: 2 wt%2 wt%
6 kg/kg6 kg/kg500 ton500 ton50000 ton/day50000 ton/day
121277CokeCoke
72724343LiquidsLiquids
84845050HH22SS
ton S/dayton S/day% of % of sulfur sulfur in in feedfeed
productproduct
Do we have a problem?
TTUUDelftDelft &CER
1
10
100
1000
10000
0 0.5 1 1.5 2
FCC feedstock sulfur, wt.%
FCC
gas
olin
e su
lfur,
ppm
w
untreated feed
Effect of HDS of FCC feedstock on gasoline sulfur content
TTUUDelftDelft &CER
How to avoid SO2 emission FCC unitwithout capital investment???
2 SO2 + O2 → 2 SO3
SO3 + MO → MSO4
Trapping SO2 in regenerator by the formation of sulfate
What happens in the riser??
Dependent on the metal the sulfate is not stable in riser (or stripper)
Stable in regeneratorNot in riserSulfates of Ce, Mg,..
MSO4 + H2 → MSO3 + H2OMO + H2S
orMS + H2O
H2
H2O
MO
TTUUDelftDelft &CER
Novel Developments in FCC0.51 - 0.55 nm
Production of light alkenes (CProduction of light alkenes (C33==, C, C44
==))–– addition of ZSMaddition of ZSM--55–– aapplicationpplication
»» petrochemical feedstockpetrochemical feedstock»» isobutene for MTBE, ETBEisobutene for MTBE, ETBE
Processing of heavier feedstocksProcessing of heavier feedstocks–– improved reactors, strippers, feed injection, gas/solid separaimproved reactors, strippers, feed injection, gas/solid separationtion–– application of catalyst cooling and high application of catalyst cooling and high TT
»» much higher coke production, metal deposits, more much higher coke production, metal deposits, more sulfursulfur
TTUUDelftDelft &CER
Hydroprocessing
TTUUDelftDelft &CER
Modern oil refinery
Crude oil
Straight run gasoline
LPG and Gas
Naphtha
Hydro-treating
Reformate
Middle distillates
Heavy atm. gas oil
Solventextraction
Lube base stocks
Gasoline
Vacuum gas oil
Solventdewaxing
Lube oils
Waxes
Gasoline, Naphtha, Middle distillates
Gasoline, Naphtha, Middle distillates
Gasoline, Naphtha, Middle distillates
Slurry oil
Refinery fuel gas
LPG
Gasoline
Solvents
Kerosene
Diesel
Heating oil
Lube oil
Greases
Asphalt
Industrial fuels
Coke
Trea
ting
and
Blen
ding
Delayed coker / Flexicoker
Propanedeasphalter
Hydro-treating
Catalyticreforming
Catalyticcracking
Visbreaker
Hydro-cracking
Fuel oil
Asphalt
LPG and Gas
Cycle oil
Alkylation AlkylateLPG
Hydro-treating
Vacu
umD
istil
latio
nAt
mos
pher
icD
istil
latio
n
TTUUDelftDelft &CER
Hydrotreating and HydrocrackingHYDROTREATINGHYDROTREATING•• Conversion with hydrogenConversion with hydrogen•• Reactions: hydrogenation &Reactions: hydrogenation & hydrogenolysishydrogenolysis•• Removal of heteroRemoval of hetero--atoms (S, N, O)atoms (S, N, O)•• Some hydrogenation of double bonds & Some hydrogenation of double bonds &
aromatic ringsaromatic rings•• Molecular size not drastically alteredMolecular size not drastically altered•• Also termedAlso termed hydropurificationhydropurification
HYDROCRACKINGHYDROCRACKING•• Similar to hydrotreatingSimilar to hydrotreating•• Drastic reduction in molecular sizeDrastic reduction in molecular size
TTUUDelftDelft &CER
Hydrotreating
TTUUDelftDelft &CER
Why Hydrotreating ?
•• Protection of the environmentProtection of the environment–– reduction acid rainreduction acid rain
•• Protection of downstream catalystsProtection of downstream catalysts–– in further processingin further processing–– SS--compounds in Diesel fuel give difficulties in catalytic compounds in Diesel fuel give difficulties in catalytic
cleaning of exhaust gasescleaning of exhaust gases
•• Improvement of gasoline properties Improvement of gasoline properties –– odour, colour, stability, corrosionodour, colour, stability, corrosion
TTUUDelftDelft &CER
Hydrotreating Reactions
5) Phenols
4) Pyridines
3) Benzothiophenes
2) Thiophenes
1) Mercaptans
5
5
3
RSH +
+
+
+
+
+
+
+
+
H2
H2
H2
H2
H2
RH
S
S
H2S
H2S
H2S
+ NH3
H2O
N
OH
HDSHDS
HDSHDS
HDSHDS
HDNHDN
HDOHDO
TTUUDelftDelft &CER
0 1 2 3 4 5
1000/Temperature (1/K)
0
10
20
30
40
50
60
70
80
90
100
S
S
CH3SH
lnK e
q
Industrial conditions600-650 K
Equilibrium data
TTUUDelftDelft &CER
Naphtha Gas OilTemperature (K) 590 - 650 600 - 670Pressure (bar) 15 - 40 40 - 100H2/oil (Nm3/kg) 0.1 - 0.3 0.15 - 0.3 WHSV (kg feed/(m3 catalyst)/h) 2000 - 5000 500 - 3000
Catalyst: mixed metal sulfides (CoS and MoS2 or NiS and WS2 on Al2O3)
γ-Al2O3
‘CoMoS’S
CoMo
Typical process conditions
Process design ???
�
�
�
�
�
TTUUDelftDelft &CER
Inert beads
Catalyst bed
Distributor
Support grid
Product
Gas + liquid
Catalyst particle with liquid film
Gas
DeflectorGas
Liquid
Complete wetting
Incomplete wetting
Trickle-bed Reactor
TTUUDelftDelft &CER
steam
Hydrogen
Feed
hydrogen recycle to H2S removal
Sour water
Product
SeparatorStripperHot HP separator
ReactorFurnace
Gas (C3
-)
Recycle gas scrubbing
NaphthaCold HP separator
H2S
water
Hot LP separator
Hydrotreating Process (trickle bed)
TTUUDelftDelft &CER
Development of maximum Sulfur Content in automotive Diesel in Europe
Year
1 2 3 4
3000
500 35050
0
500
1000
1500
2000
2500
3000
3500
1996 2000 2005< 1996
Max S in Dieselppm
TTUUDelftDelft &CER
Activity of Various Catalysts for HDS ofPretreated Gas Oil
CoMo/γ-Al2O3260 ppm
NiW/γ-Al2O3
PtPd/ASA (I)
Pt/ASA
Feed 760 ppm
NiMo/γ-Al2O3230 ppm
200 ppm
140 ppm
60 ppm
S
CH3
S
CH3
SCH3
C2H5
SCH3
What catalyst do you select for
Deep desulphiding
???
NaphtaHeavy gasoil ???
Retention time
TTUUDelftDelft &CER
Hydrocracking
TTUUDelftDelft &CER
Silica-alumina
‘NiMoS’S
NiMo
Hydrocracking
Similar to FCCSimilar to FCC–– but Hbut H22 inhibits some secondary reactions inhibits some secondary reactions
»» e.g. coke formation e.g. coke formation
Catalyst ???Catalyst ???
•• Acid sitesAcid sites–– SiOSiO22, Al, Al22OO33, silica, silica--alumina, zeolitesalumina, zeolites
•• Hydrogenation sitesHydrogenation sites–– NiSNiS//MoSMoS, , NiSNiS/WS/WS22, Pt, Pt
»» NHNH33 inhibits reactioninhibits reaction»» HH22S inhibits reactionS inhibits reaction
TTUUDelftDelft &CER
Reactions during Hydrocracking
Hetero-atom removal
Aromatics hydrogenation
Hydrodecyclization
Alkanes hydrocracking
Hydro-isomerization
+
+ 2 H2 + 3 H2
NH
+ NH3+ 6 H2
+ H2
+ 3 H2
+
∆ H0208 (kJ/mol)
- 374
- 326
- 119
- 44
- 4
TTUUDelftDelft &CER
Process Configurations for Hydrocracking
Feed HT
Gas
NaphthaMD
HC
Two stage
Gas
GasNaphtha
FeedMD
Series flow
HCHT
Feed
NaphthaMD
Hydrowax
Single stage / once through
HT/HC
HT = hydrotreating
HC = hydrocracking
MD = middle distillates
low investmentinhibition
high investmenthigh rates
TTUUDelftDelft &CER
Two-stage Hydrocracker
Fresh hydrogen
Feed
Hydrogen recycle
to acid gas and NH3 removal
FractionatorHigh/Low pressure separators
ReactorFurnace
C1 − C4
Naphtha
Middle distillates
Purge
Quench H2
ReactorFurnace
Quench H2
TTUUDelftDelft &CER
Summary of Processing Conditions
Mild single stage /first stage
second stage
Temperature (K)Hydrogen pressure (bar)Total pressure (bar)Catalyst
670 – 70050 – 8070 – 100Ni/Mo/S/γ-Al2O3 +P*
610 – 71080 – 130100 – 150Ni/Mo/S/γ-Al2O3+P*
530 – 65080 – 130100 – 150Ni/W/S/USY zeolite
TTUUDelftDelft &CER
Modern oil refinery
Crude oil
Straight run gasoline
LPG and Gas
Naphtha
Hydro-treating
Reformate
Middle distillates
Heavy atm. gas oil
Solventextraction
Lube base stocks
Gasoline
Vacuum gas oil
Solventdewaxing
Lube oils
Waxes
Gasoline, Naphtha, Middle distillates
Gasoline, Naphtha, Middle distillates
Gasoline, Naphtha, Middle distillates
Slurry oil
Refinery fuel gas
LPG
Gasoline
Solvents
Kerosene
Diesel
Heating oil
Lube oil
Greases
Asphalt
Industrial fuels
Coke
Trea
ting
and
Blen
ding
Delayed coker / Flexicoker
Propanedeasphalter
Hydro-treating
Catalyticreforming
Catalyticcracking
Visbreaker
Hydro-cracking
Fuel oil
Asphalt
LPG and Gas
Cycle oil
Alkylation AlkylateLPG
Hydro-treating
Vacu
umD
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TTUUDelftDelft &CER
Catalytic Reforming
TTUUDelftDelft &CER
Catalytic Reforming
•• Important for gasoline productionImportant for gasoline production–– Increases octane number Increases octane number
•• Important for base chemicals productionImportant for base chemicals production–– aromaticsaromatics–– HH22
TTUUDelftDelft &CER
Octane Numbers, Boiling Points•• nn--pentanepentane 6262 309 K309 K•• 22--methyl butanemethyl butane 9090 301301•• cyclopentanecyclopentane 8585 322322•• nn--hexanehexane 2626 342342•• 2,22,2--dimethylbutanedimethylbutane 9393 323323•• benzenebenzene >100>100 353353•• cyclohexanecyclohexane 7777 354354•• nn--octaneoctane 00 399399•• 2,2,32,2,3--trimethylpentanetrimethylpentane 100100 372372•• methylmethyl--tertiarytertiary--butylbutyl--etherether 118118 328328
•• straight run gasolinestraight run gasoline 6868 67 (MON)67 (MON)•• FCC light gasolineFCC light gasoline 9393 8282•• alkylatealkylate 9595 9292•• reformate reformate (CCR)(CCR) 9999 8888
What reactions would you carry out??
TTUUDelftDelft &CER
C + 3 H2C
C C C C C C C C + H2
C C C C C C C C C C C C CC
CC
C + 3 H2C
Isomerization
Cyclization
Aromatization
Combination
∆ H0208 (kJ/mol)
- 4
+ 33
+ 205
+ 177
73
~ 100
~ 50
26
~ 40
Octane number
Reactions for Increase of Octane Number
TTUUDelftDelft &CER
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
500 550 600 650 700 750 800
Temperature (K)
Cyc
lohe
xane
con
vers
ion
(-)
1 bar 5 bar 25 bar10 bar
Aromatization of CyclohexaneEffect of T and p
FavourableFavourable–– low pressurelow pressure–– high temperaturehigh temperature
TTUUDelftDelft &CER
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
500 550 600 650 700 750 800
Temperature (K)
Cyc
lohe
xane
con
vers
ion
(-)
H2/cyclohexane (mol/mol)
0 105
Aromatization of CyclohexaneEffect of T and H2/CH feed ratio
TTUUDelftDelft &CER
Conceptual process design?
Catalyst stability highest forCatalyst stability highest for–– low Tlow T–– excess Hexcess H22–– low S impuritylow S impurity
Catalyst regeneration possibleCatalyst regeneration possible–– removal coke by combustionremoval coke by combustion–– restoring acidity by Clrestoring acidity by Cl22 treatmenttreatment–– Redispersion Redispersion of noble metal
ThermodynamicsThermodynamics–– high Thigh T–– low plow p–– ∆∆H >>0H >>0
of noble metal
Time scale stability dependent on conditions• months• days
How to handle deactivation?? Reactor ???
Fixed Bed and Moving Bed are used
TTUUDelftDelft &CER
Axial-flow reactor Radial-flow reactor
Gas flow Gas flow
Catalyst bed
Reactors for Catalytic Reforming
TTUUDelftDelft &CER
Catalytic reforming section Stabilizer
Reformate
C4-
Hydrogen separator
Hydrogen recycle
Reactor
Furnace
Pretreated naphtha feed
Net hydrogen
770 K 780 K 790 K
720 K 780 K760 K
Semi-Regenerative Catalytic Reforming (SRR)
TTUUDelftDelft &CER
Hydrogen (fresh & recycle)
Air
Cl2
Lift gas
Collectors
Lift pots
Regenerator ReactorsReactor 3 Reactor 4
Naphtha (desulfurized)
Catalyst recycle
Reformate
buffer drum
Reactor 1 Reactor 2
Continuously-Regenerative Catalytic Reforming (CRR)
TTUUDelftDelft &CER
semi fully continuous
H2/HC (mol/mol) 10 4-8 4-8
Pressure (bar) 15-35 7-15 3-4
Temperature (K) 740-780 740-780 770-800
Catalyst life 0.5-1.5 y days-weeks days-weeks
γ-Al2O3
-Al-O-Al-O-Al-O-Al-O-Al-
HO Cl
Pt
Operating conditions in catalytic reforming
TTUUDelftDelft &CER
Catalytic ReformingTypical Feedstock and Product Composition
(vol%)
Component Feed ProductAlkanesAlkenesNaphthenesAromatics
45 – 550 – 230 – 405 – 10
30 – 5005 – 1045 – 60
TTUUDelftDelft &CER
Alkylation
TTUUDelftDelft &CER
Modern oil refinery
Crude oil
Straight run gasoline
LPG and Gas
Naphtha
Hydro-treating
Reformate
Middle distillates
Heavy atm. gas oil
Solventextraction
Lube base stocks
Gasoline
Vacuum gas oil
Solventdewaxing
Lube oils
Waxes
Gasoline, Naphtha, Middle distillates
Gasoline, Naphtha, Middle distillates
Gasoline, Naphtha, Middle distillates
Slurry oil
Refinery fuel gas
LPG
Gasoline
Solvents
Kerosene
Diesel
Heating oil
Lube oil
Greases
Asphalt
Industrial fuels
Coke
Trea
ting
and
Blen
ding
Delayed coker / Flexicoker
Propanedeasphalter
Hydro-treating
Catalyticreforming
Catalyticcracking
Visbreaker
Hydro-cracking
Fuel oil
Asphalt
LPG and Gas
Cycle oil
Alkylation AlkylateLPG
Hydro-treating
Vacu
umD
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latio
nAt
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icD
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latio
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TTUUDelftDelft &CER
Alkylation
AimAim•• Conversion of alkenes &Conversion of alkenes & alkanesalkanes to higher branched to higher branched alkanesalkanes
–– alkylatealkylate: high octane number gasoline: high octane number gasoline
PastPast–– Thermal process ( 770 K, 200Thermal process ( 770 K, 200--300 bar)300 bar)
NowadaysNowadays–– Catalytic process ( 298 K, 8 bar)Catalytic process ( 298 K, 8 bar)–– H2SO4 / HF / AlClH2SO4 / HF / AlCl33--HClHCl
TTUUDelftDelft &CER
+ small amounts of other products
4 %
25 %
16 %
38 %
CC C C CC C
C
CC C
CC C C CC C
CC C+CC CC
CC C C CC C
Example of Alkylation
TTUUDelftDelft &CER
Initiation
Propagation
+
+
+
+
+ +
Etc.
C C C
C C C C C
C C
C C C C CC
C C C C C C C CC
C C
C
C C C C CC
CC C
C C C CC
CC C C
H+ C+
C+ C+
C+C+
C+
C+
C
C C
Reaction via Carbenium Ions
Alkylation Mechanism
TTUUDelftDelft &CER
Feedstocks?
Heterogeneous catalyst would be a breakthrough
Alkylation
FCC, Hydrocracking, Distillation, ....
FCC, coking
ii--butanebutane
CC--C=CC=CCC--CC--C=CC=C
Practical (Practical (disdis)advantages two common catalyst systems)advantages two common catalyst systemsHH22SOSO44 HFHF10 10 ooCC 30 30 ooCC100100 0.50.5 kg acid consumption/tkg acid consumption/t alkylatealkylate
TTUUDelftDelft &CER
Alkylation, summary•• ii--C4/C4/alkenealkene should be large (5 should be large (5 -- 15)15)•• Inorganic acid phase: accumulation CInorganic acid phase: accumulation C--C=CC=C
mixing essentialmixing essential•• Acid catalystsAcid catalysts HH22SOSO44 (95%, 1% H(95%, 1% H22O)O)•• HFHF (90%, 1% H(90%, 1% H22O)O)•• Highly exothermic reactionsHighly exothermic reactions
What catalyst do you prefer??What catalyst do you prefer??
•• HH22SOSO44 most active, but bymost active, but by--productsproducts•• HF less active, but hazardousHF less active, but hazardous
TTUUDelftDelft &CER
Recycle acid
Reject acid
Reactor & Acid settler
Fresh acidIsobutane
Alkene
caustic
spent caustic
Recycle isobutane
Caustic scrubber
De-isobutanizerDebutanizer
Propane
Depropanizer
Receiver
Economizer
n-Butane
Alkylatewaste water
water
Vapor (i-C4 / C3)
Alkylation with H2SO4 in Cascade of CSTRs
TTUUDelftDelft &CER
Alkylation with H2SO4 in Stratcocontactor with autorefrigeration
PC
Recycle acid
Alkylate & C3 + C4
Recycle C3 + C4Alkene & isobutane feed
To condenser and separator
Reactor
Settler
Emulsion (HCs/acid)
TTUUDelftDelft &CER
Comparison of H2SO4 and HF Alkylation
H2SO4 process HF processTemperature (K)Pressure (bar)Residence time (min)Isobutane/butene feed ratioAcid strength (wt%)Acid in emulsion (vol%)Acid consumption per mass ofalkylate (kg/t)
277 – 2832 – 620 – 308 – 1288 – 9540 – 6070 – 100
298 – 3138 – 205 – 2010 – 2080 – 9525 – 800.4 – 1
TTUUDelftDelft &CER
Conversion of heavy residues
TTUUDelftDelft &CER
Modern oil refinery
Crude oil
Straight run gasoline
LPG and Gas
Naphtha
Hydro-treating
Reformate
Middle distillates
Heavy atm. gas oil
Solventextraction
Lube base stocks
Gasoline
Vacuum gas oil
Solventdewaxing
Lube oils
Waxes
Gasoline, Naphtha, Middle distillates
Gasoline, Naphtha, Middle distillates
Gasoline, Naphtha, Middle distillates
Slurry oil
Refinery fuel gas
LPG
Gasoline
Solvents
Kerosene
Diesel
Heating oil
Lube oil
Greases
Asphalt
Industrial fuels
Coke
Trea
ting
and
Blen
ding
Delayed coker / Flexicoker
Propanedeasphalter
Hydro-treating
Catalyticreforming
Catalyticcracking
Visbreaker
Hydro-cracking
Fuel oil
Asphalt
LPG and Gas
Cycle oil
Alkylation AlkylateLPG
Hydro-treating
Vacu
umD
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latio
nAt
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icD
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latio
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TTUUDelftDelft &CER
Conversion of Heavy Residues
How?How?Why?Why?
•• Carbon outCarbon out–– Coking processesCoking processes
•• Hydrogen inHydrogen in–– Hydrotreating
•• Product distribution not rightProduct distribution not right–– Demand for lighter productsDemand for lighter products–– Demand for cleaner productsDemand for cleaner products
»» low/zero low/zero sulfursulfur gasoline and gasoline and dieseldiesel
•• Heavier, moreHeavier, more sulfursulfurcontaining,containing, crudes crudes are are processedprocessed
•• Stricter regulations on refinery Stricter regulations on refinery emissions
Hydrotreating
emissions
TTUUDelftDelft &CER
Light Crude Oil Product Distribution
Gasoline
Kerosene /Gas oil
Fuel oil(3.5% sulfur)
Own use
LPG 4%
28%
39%
22%
7%
Complex refinery
Gasoline
Kerosene /Gas oil
Fuel oil(3.5% sulfur)
Own use
LPG 2%15%
35.5%
44%
3.5%
Hydroskimming refinery
TTUUDelftDelft &CER
Impact on refinery
Deep conversion: whitening of the barrelDeep conversion: whitening of the barrel–– MoreMore hydrotreatinghydrotreating facilitiesfacilities–– Production capacity for HProduction capacity for H22 productionproduction–– Production of refinery fuel gas for heating (instead of Production of refinery fuel gas for heating (instead of
using heavy oil fraction)using heavy oil fraction)–– Production capacity for conversion HProduction capacity for conversion H22SS–– EndEnd--ofof--pipe solutionspipe solutions
TTUUDelftDelft &CER
•• “Carbon Out”“Carbon Out”
•• Thermal crackingThermal cracking–– Residual oilResidual oil →→ gas, liquid, cokegas, liquid, coke
•• Coke gasification / combustionCoke gasification / combustion–– C + C + ½½ OO22 →→ COCO exoexo–– C + HC + H22OO →→ CO + HCO + H22 endoendo–– C + COC + CO22 →→ 2 CO2 CO endoendo
Flexicoking
Process scheme?
TTUUDelftDelft &CER
Coke fines
Sulfur
Sulfur removal
Cyclone
Coke slurry
Venturiscrubber
Air
Steam
Steam
Liquid productsto fractionator Low calorific
gas
Feed
750 - 800 K
1000 -1100 K
1200 - 1300 K
Reactor Heater Gasifier
Scrubber
Water Separator
Purge coke
Thermal cracking Heat exchange Combustion/Gasification
Flexicoking
Product yields
Gas and LPG 10 - 15 %Naphtha,Gasoil 55 - 65 %Coke 25 - 30 %
Composition?
TTUUDelftDelft &CER
Catalytic Hydrogenation of ResiduesWhat are the differences with thermal processes??
•• Catalytic ProcessesCatalytic Processes–– Catalyst deactivationCatalyst deactivation
»» Metal depositionMetal deposition»» Coke depositionCoke deposition
–– Molecular size largeMolecular size large»» Diffusion limitations to be expectedDiffusion limitations to be expected
–– High hydrogen pressureHigh hydrogen pressure
Process design?Process design?
•• Technology based on (semi)continuous catalyst Technology based on (semi)continuous catalyst replacementreplacement
–– FluidizedFluidized--bed reactors, small catalyst particlesbed reactors, small catalyst particles–– MovingMoving--bed reactors, catalyst particles with wide poresbed reactors, catalyst particles with wide pores–– Slurry reactors, very small catalyst particlesSlurry reactors, very small catalyst particles
TTUUDelftDelft &CER
Catalyst Deactivation
Deposition of poisonsDeposition of poisons
–– AsphaltenesAsphaltenes, coke, coke
–– Metals as metal Metals as metal sulfidessulfides
NiNi--porphyrin porphyrin + H+ H22 NiS NiS + hydrocarbons+ hydrocarbons
VV--porphyrin porphyrin + H+ H22 VV22SS33 + hydrocarbons+ hydrocarbons
TTUUDelftDelft &CER
Catalyst Deactivationduring hydrotreating
....... .
.
...
..
.
.
.
.
.
....... .
.
.
....
..
.
.
.
.
.
. ..
.
. . .
. . ..
..
.
. .
.
... .. .
. . . .... ..
..
... ..... .. ...
.
.
.. ..
.
.
. .
..
.
time on stream
catalystpellet
fresh catalyst active sitepoisoning
pore plugging
.
.
.. . . . .
....
.. ..
.... . ... . .
.
.. .
.. ..microscale .
.
.. . . . .
....
.. ..
.... . ... . .
.
.. .
.. ..
.
.
.. . . . .
....
.. ..
.... . ... . .
.
.. .
.. ..
active site
pore
metal sulfidedeposit
TTUUDelftDelft &CER
Reactors for Hydroconversion of Residues
Fixed-bed reactor (trickle flow)
Inert beads
Distributor
Support grid
Product
Gas + liquid
Catalyst bed
Slurry reactor
Gas bubble
Catalyst in suspensionGas
Liquid +cat.
Product (+ cat.)
Fluidized-bed reactor (three phase)
Catalyst in suspension
Level of fluidized bed
Product
Gas bubble
Gas
Liquid
TTUUDelftDelft &CER
ProductsFractionation
Hydrogen rich gas
Low pressure separator
High pressure separators
Off gasCatalyst addition
Catalyst removal
Hydrogen
Feed
Heaters Reactors Separation
Purification700 - 740 K150 - 200 bar
Process with Fluidized-bed Reactors (Lummus)
TTUUDelftDelft &CER
Products to separation
Stationary catalyst bed
Stationary catalyst bed
Hydrogen
Hydrogen
Spent catalyst
Catalyst rejuvenation
Moving catalyst bed
Fresh catalyst
Feed
HDMbunker reactor
HCON fixed-bed reactor
620 - 710 K100 - 200 bar
HYCON Process
TTUUDelftDelft &CER
Sulfurremoval Extraction Drying
Classification
Rejuvenatedcatalyst
Used catalyst
HDM Catalyst Rejuvenation
TTUUDelftDelft &CER
Processes with Fixed-bed Reactors
HDM catalyst HDS catalystwide pores
HDS catalystnarrow pores
Residual feed
Metal content(ppmw)
Fixed bed< 25
25 - 50
50 - 100
> 100
>> 100
Fixed bed, dual catalyst system
Fixed bed, threefold catalyst system
Fixed bed, HDS catalystsMoving bedBunker HDM
Fixed bed, HDS catalystsBunker HDM
Cat. rejuvenation
TTUUDelftDelft &CER
Products
Hydrogen
Feed
CatalystFractionationLP
separator
Heaters Slurry reactor
Cold LP separator
700 - 740 K150 - 300 bar
HP separator
Off gasPurification
Residue
Fixed-bed reactor
Veba Combi-Cracking Process (Slurry Reactor)
TTUUDelftDelft &CER
Treatment refinery gas streams
TTUUDelftDelft &CER
•• Removal of HRemoval of H22SS–– Exhaust from hydrotreatingExhaust from hydrotreating–– Exhaust from FCCExhaust from FCC
•• Removal of NORemoval of NOxx, SO, SO22–– Exhaust from burnersExhaust from burners–– Exhaust from FCC regeneratorExhaust from FCC regenerator
•• Recovery of HRecovery of H22–– Exhaust from hydrotreatingExhaust from hydrotreating–– Exhaust from FCCExhaust from FCC
Treatment of Refinery Gas Streams
TTUUDelftDelft &CER
H2S Removal and Conversion
•• Removal by absorption in Removal by absorption in regenerable regenerable liquid solventsliquid solvents
AlkanolaminesAlkanolamines
MEA (monoMEA (mono--ethanol amine)ethanol amine)
DIPA (DIPA (didi--isoiso--propanol propanol amine)amine)
•• Conversion of HConversion of H22S to elemental S:S to elemental S:–– Claus processClaus process–– SCOT process (SSCOT process (S--compounds compounds →→ HH22SS →→ Claus plant)Claus plant)–– SuperClausSuperClaus processprocess
CH2HO CH2 NH2
CH3 CH CH2 N CH2 CH CH3OH OHH
TTUUDelftDelft &CER
LP steam
Absorber Regenerator
Feed gas
Rich solution
Lean alkanolaminesolution
H2Sto sulfur recovery
Purified gas
315 K 385 K
H2S removal by amine absorption
TTUUDelftDelft &CER
Sulfur recovery limited by equilibriumClaus: About 95% H2S converted to SSCOT & SuperClaus: nearly 100% recovery
2 H2S + O2 S2 + 2 H2O ∆ H0298 = - 444 kJ/mol
H2S oxidized to elemental S:
Claus Process
TTUUDelftDelft &CER
Claus Process
H2S + 3/2 O2 SO2 + H2O
2 H2S + SO2 3/2 S2 + 2 H2O
Reheater
Air
Tail gas
Sulfur pit
Boiler feed water
LP steam
Sulfur pump
QC
H2S :SO22 :1
520 K
HP steam
> 1300 K
Boiler feed waterAcid
gas
Liquid sulfur
Claus reactor 2 Claus reactor 3Reaction furnace
Waste heat boiler
Claus reactor 1
Condenser 4Condenser 1 Condenser 2 Condenser 3
TTUUDelftDelft &CER
SCOT Process
SO2, CS2, COS + H2 H2S
LP steam
LP steam
Treated gas to incinerator
Acid gas recycle to Claus plant
Purge
AirFuel gas
Reducing gas570 KClaus tail gas
Line burner SCOT reactor Cooling tower Absorber Regenerator
TTUUDelftDelft &CER
SuperClaus Process
SuperClaus reaction: H2S + 1/2 O2 1/2 S2 + H2O
Reheater
Air
Acid gas
Tail gas
Boiler feed water
LP steam
Boiler feed water
HP steam
Reaction furnace
Waste heat boiler
Claus reactor 1
> 1300 K
Condenser 1 Condenser 2 Condenser 3 Condenser 4
Claus reactor 2 Selective oxidation reactor
S S S S
QCH2S
0.8-3 vol%
TTUUDelftDelft &CER
Methods:Methods:–– Cryogenic distillationCryogenic distillation
»» Energy intensiveEnergy intensive–– AbsorptionAbsorption
»» High purity can not be obtainedHigh purity can not be obtained–– AdsorptionAdsorption
»» TSA (Temperature Swing Adsorption)TSA (Temperature Swing Adsorption)»» PSA (Pressure Swing Adsorption)PSA (Pressure Swing Adsorption)
–– Membrane separationMembrane separation
Recovery of Hydrogen from Refinery Gas Streams
TTUUDelftDelft &CER
•• Applications:Applications:–– Air dryingAir drying–– NN22 productionproduction–– HH22 purification: Hpurification: H22 hardly adsorbshardly adsorbs
•• Transient process: cyclicTransient process: cyclic–– Adsorption of impuritiesAdsorption of impurities–– Regeneration of adsorbent bedRegeneration of adsorbent bed
»» by raising T: TSAby raising T: TSA»» by reducing p: PSAby reducing p: PSA
Adsorption
TTUUDelftDelft &CER
Adsorber 1 Adsorber 2 Adsorber 3 Adsorber 4
Purified hydrogen
Purge gasFeed
Adsorption Pressurization Regeneration / purge
Depressurization
10 - 40 bar 1 - 10 bar
Depressurization / Pressurization
Depressurization / Purge
Hydrogen purification using PSA
TTUUDelftDelft &CER
Adsorber 1
Time
Adsorption
Adsorption
Adsorption
Adsorption
Regeneration
Regeneration
Regeneration
Regeneration
Pres
sure
Step 1 Step 2 Step 3 Step 4
Adsorber 2
Adsorber 3
Adsorber 4
Cycle-sequence in PSA
TTUUDelftDelft &CER
•• High selectivityHigh selectivity•• High permeabilityHigh permeability•• High mechanical stabilityHigh mechanical stability•• Thermal stabilityThermal stability•• Chemical resistanceChemical resistance
Membranes: important properties
TTUUDelftDelft &CER
•• DialysisDialysis•• Seawater desalinationSeawater desalination•• Membrane distillationMembrane distillation•• Concentration of proteins in food industryConcentration of proteins in food industry•• Separation of gas mixturesSeparation of gas mixtures
Membranes: Applications
TTUUDelftDelft &CER
Polymeric membranesPolymeric membranes–– AdvantageAdvantage
»» high selectivityhigh selectivity–– DisadvantagesDisadvantages
»» limited thermal stability (180 limited thermal stability (180 ooC)C)»» prone to degradationprone to degradation
Inorganic membranesInorganic membranes•• Pd, porous layersPd, porous layers
–– AdvantagesAdvantages»» stable at high temperaturestable at high temperature»» large variety of materialslarge variety of materials
–– DisadvantageDisadvantage»» generally low selectivitygenerally low selectivity
Membranes
TTUUDelftDelft &CER
Membrane ProcessesAdvantages and Disadvantages
•• AdvantagesAdvantages
–– Low energy consumptionLow energy consumption»» no phase transfer no phase transfer
–– Mild conditionsMild conditions–– Low pressure dropLow pressure drop–– No additional phase requiredNo additional phase required–– Continuous separationContinuous separation–– Easy operationEasy operation
»» No moving partsNo moving parts
•• DisadvantagesDisadvantages
–– FoulingFouling–– Low lifetimeLow lifetime–– Often low selectivityOften low selectivity–– No economy of scale (scaleNo economy of scale (scale--up up
factor ~ 1)factor ~ 1)
TTUUDelftDelft &CER
Feed (pmax = 148 bar)
RetentatePermeate
Fiber bundle end seal
Potted open end Fiber bundle
D = 0.1 - 0.2 m
L = 3 m
Monsanto hollow-fiber Module
TTUUDelftDelft &CER
Feed gas Application Total capacity(m3 (STP) h-1)
H2-N2, CH4, Ar Ammonia synthesis gas 390400H2-CH4, N2 Methanol synthesis gas 6100H2-CO Synthesis gas in the
Chemical industry 12540H2-enriched gas refineries, chemical industry 164300CO2-CH4 Natural gas 34100
Biogas 310N2-concentration Inertization 800
Applications in Gas Separation
TTUUDelftDelft &CER
Catalytic Reformer
Naphtha Hydrodesulfurization
Refinery products Hydrodesulfurization
Gas oil Hydrodesulfurization
Cracking products Hydrodesulfurization
Permeate6.4 Nm3 h-1
17 bar92% H2
Membrane units
Heating gas
Retentate13.6 Nm3 h-1
48 bar55% H2
Feed20 Nm3 h-1
48 bar60% H2
Hydrogen Recovery in Oil Refineries
TTUUDelftDelft &CER
Novel processes for high-quality gasoline and diesel
TTUUDelftDelft &CER
Reformulated Gasoline
•• Prior to 1973Prior to 1973–– reformatereformate + tops + lead+ tops + lead
•• From 1973 onFrom 1973 on–– leadlead--free gasolinefree gasoline
»» enhance ON by catalytic reforming, enhance ON by catalytic reforming, isomerizationisomerization, …, …•• Maximum Maximum sulfursulfur, , alkenealkene, benzene content, benzene content•• Minimum oxygenate contentMinimum oxygenate content
•• Best gasolineBest gasoline–– alkylate alkylate
»» but not attractive processbut not attractive process
TTUUDelftDelft &CER
Source* Sulfur (wt%) Aromatics (wt%) Cetane numberStraight-run gas oilLight cycle oil from FCCGas oil from thermal processesGas oil from hydrocrackingFischer-Tropsch gas oil
1 – 1.52 – 2.82 – 3< 0.010
20 – 40> 7040 – 70< 10≈ 0
40 – 50< 2530 – 50> 55> 70
* Before hydrodesulfurization
Diesel
TTUUDelftDelft &CER
0.0
0.2
0.4
0.6
0.8
1.0n-
buta
ne
iso-
buta
ne
neop
enta
ne
benz
ene
p-xy
lene
o-xy
lene
amm
onia
wat
er
hydr
ogen
carb
on m
onox
ide
carb
on d
ioxi
de
oxyg
en
nitro
gen
Dia
met
er (n
m) X,Y
4A
ZSM-5
(C4H
9)3N
(C4F
9)3N
Shape Selectivity
TTUUDelftDelft &CER
+
CH3OH H2O
Reactant selectivity
Transition-state selectivity
Product selectivity
Shape Selectivity
TTUUDelftDelft &CER
CH3CCH3
OCH3
CH2CH3C CH2H3CCH3
+ CH3CH2OH
+ CH3OHC CH2H3CCH3
CH3CCH3
O CH3
CH3
MTBE
ETBE
Routes to MTBE and ETBE
TTUUDelftDelft &CER
C C CC
iso-butane iso-buteneC C C
C
C C C Cn-butane n-butene
C C C C
Isomerization Isomerization
Dehydrogenation
Routes to Isobutene
TTUUDelftDelft &CER
C C C C+
C C C CC C C C
C C C CCC
CC+
C C C CC
CC C+
+C C C
CC C CC
C C C CC
CC
C +
skeletalisomerization
C C CC
C C CC
+
C C C C C C C Cdouble bond isomerization
+
C C CcH+
C C CC
skeletalisom.
C C CC
Ferrierite
Butene Isomerization in Ferrierite
TTUUDelftDelft &CER
C4 feed
ReactorHeater
C4 product
DistillationCompressor
C5+
620 K1 − 2 bar
Butene Isomerization
TTUUDelftDelft &CER
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
300 350 400 450 500 550 600 650 700
Temperature (K)
Mol
frac
tion
C6
isom
ers
in to
tal h
exan
es (-
)
C-C-C-C-C-C
C-C-C-C-CC
C-C-C-C-CC
C-C-C-CC
C
C-C-C-CC
C
Isomerization of Hexanes - Equilibrium Composition
TTUUDelftDelft &CER
80
82
84
86
88
90
92
300 350 400 450 500 550 600
Temperature (K)
RO
N
once through process
with recycle of normal alkanes
Feed:Pentanes 60%Hexanes 30%Cyclics 10%
Pt/Cl/Al2O3 Pt/H-Mordenite
Effect of n-Alkane Recycle on Octane Number
TTUUDelftDelft &CER
TIP (Total Isomerization Package) ProcessHYSOMER lead
C4 −
HYSOMER ISOSIVC5/C6 feed
iso-alkanesnormal alkanes recycle
ISOSIV HYSOMERC5/C6 feed
normal + iso alkanes recycle
C4 −
iso-alkanesISOSIV lead
TTUUDelftDelft &CER
ocess via Main product(s)GO
ischer-Tropsch
methanolmethanolalkenessynthesis gas
gasolinealkenes for MOGD processdistillates/gasolinedistillates
From Synthesis Gas to Gasoline and Diesel
PrMTMTMOGDF
TTUUDelftDelft &CER
2 CH3OH ←→ H3C-O-CH3 + H2O H3C-O-CH3 → Light alkenes + H2O Light alkenes + H3C-O-CH3 → Heavy alkenes + H2O Heavy alkenes → Aromatics + Alkanes Aromatics + H3C-O-CH3 → Higher aromatics + H2O
MTG (Methanol to Gasoline) Process
TTUUDelftDelft &CER
10-4 10-3 10-2 10-1 1 10
Space time (h⋅m3reac/m3
liq)
70
60
50
40
30
20
10
0
Methanol
DME
Water
C2-C5 alkenes
Alkanes (+ C6+ alkenes)
Aromatics
Prod
uct d
istri
butio
n (w
t%)
MTG (Methanol to Gasoline) Process
TTUUDelftDelft &CER
Gasoline to fractionation
Purge gas to fractionation
Water
Crude methanol
DME Reactor Conversion reactors (ZSM-5)
Swing reactor being regenerated
580 K
690 K
620 K
690 K
22 bar
Mobil MTG Process
TTUUDelftDelft &CER
Distillate to hydrotreating
Adiabatic oligomerization reactors SeparatorsFurnace
Gasoline
LPG
Gasoline recycle
Alkene feed
470 - 530 K30 - 100 bar
Mobil MOGD (Methanol to Gasoline and Distillates) Process
TTUUDelftDelft &CER
Gas-to-LiquidSyngas & Fischer Tropsch
TTUUDelftDelft &CER
Gas-to-Liquid Conversion
SyngasSyngasgenerationgeneration
FischerFischer--TropschTropschsynthesissynthesis
Fuel Fuel upgradingupgrading
•• FeedFeed–– Coal, oil, natural gas, biomassCoal, oil, natural gas, biomass
»» Remote natural gas resourcesRemote natural gas resources»» Associated gas crude oil rigsAssociated gas crude oil rigs
•• Flexible technologyFlexible technology–– MonetisingMonetising alternative to flaring, realternative to flaring, re--injectioninjection–– Political drivePolitical drive–– New productsNew products–– Chemicals source in future?Chemicals source in future?
•• Lower environmental impact Lower environmental impact –– HighHigh--quality clean fuelsquality clean fuels–– More efficient utilization fossil resourcesMore efficient utilization fossil resources–– Renewable, contributes to sustainable society Renewable, contributes to sustainable society
TTUUDelftDelft &CER
Production Synthesis Gas5.1, 5.2, 5.4
Important base chemical for variety of applicationsImportant base chemical for variety of applications
Mixtures Main uses
H2 Refinery hydrotreating and hydrocracking3 H2 : 1 N2 Ammonia plant feed2 H2 : 1 CO Alkenes (Fischer-Tropsch reaction)2 H2 : 1 CO Methanol plant feed1 H2 : 1 CO Aldehydes and alcohols (Oxo reactions)CO Acids (formic and acetic)
Feedstock??Feedstock??
Process??
Hydrocarbons•natural gas, oil,coal•biomass
Future for H2Solar??
Process?? Steam reformingPartial oxidation
TTUUDelftDelft &CER
Reactions starting from CH4
Steam reformingSteam reforming CHCH44 + H+ H22O O ↔↔ CO + 3 HCO + 3 H22
‘Water gas shift’‘Water gas shift’ CO + HCO + H22OO ↔↔ COCO22 + H+ H22
‘CO‘CO22 reforming’reforming’ CHCH44 + CO+ CO22 ↔↔ 2 CO + 2 H2 CO + 2 H22
Thermal crackingThermal cracking CHCH44 ↔↔ C + 2 HC + 2 H22
BoudouardBoudouard reactionreaction 2 CO2 CO ↔↔ C + COC + CO22
Partial oxidationPartial oxidation CHCH44 + ½ O+ ½ O22 →→ CCΟ + 2 ΗΟ + 2 Η22
Complete combustionComplete combustion CHCH44 + 2 O+ 2 O22 → → CCΟΟ22 + 2 Η+ 2 Η22ΟΟ
∆∆ HHrr = = 206 kJ/mol206 kJ/mol
∆ Hr = - 41 kJ/mol
∆ Hr = 247 kJ/mol
∆ Hr = 75 kJ/mol
∆ Hr = -173 kJ/mol
∆ Hr = -36 kJ/mol
∆ Hr = -803 kJ/mol
What reaction(s) are most attractive??
TTUUDelftDelft &CER
Carbon monoxide, methanol, ammonia, hydrogen, etc.
Pulverization
Coal
H2OO2/air
Heavy oil fractionH2OO2/air
Desulfurization
Natural gas
H2O Air/O2/(H2O)
Autothermicreforming
Steamreforming
PurificationAdjustment
Partialoxidation
PurificationAdjustment
PurificationAdjustment
Sulfur removal
Sulfur removal
GasificationCarbonremoval
Conversion Routes to Synthesis Gas
TTUUDelftDelft &CER
H2/CO = 3
Steam Reforming ThermodynamicsH2O/CH4 = 1
Heat required ???
Temperature
?
TTUUDelftDelft &CER
Steam reformingH2O/CH4 = 1
Partial oxidationO2/CH4 = 0.5
H2/CO = 3 H2/CO = 2
Equilibrium Compositionssteam reforming versus partial oxidation
TTUUDelftDelft &CER
H2O/CH4 = 1
Thermodynamics steam reformingEffect of Temperature and Pressure
With increasing pressurelower conversionmore CH4
TTUUDelftDelft &CER
Process Design
•• T, p ????T, p ????•• Heat management?Heat management?•• Full conversion?Full conversion?
TTUUDelftDelft &CER
Typical Allothermal Steam Reforming Process
Superheated HP Steam
Fuel
Air
Natural gasCO2
Process steam
Reformer Desulfurizer
BFW
Flue gas to stack
Steam BFWCooling water
Condensate
Raw syngas
Knock-out drum
Radiation section
Convection section
Tubes filled with catalystL = 7 - 12 mdt = 70 - 130 mm500 - 600 tubes
Material tubes•Ni-Cr alloy up to 1150 oC (Tm = 1370 oC)• More expensive materials at higher T
•Heat transfer ↓ with dt ↑• Pressure drop ↓ with dt ↑
Optimal tube diameter??
TTUUDelftDelft &CER
Radiantsection
FRONT ELEVATIONISO VIEW
ConvectionsectionAir preheater
Steam Reformer
TTUUDelftDelft &CER
ocess H2O/C(mol/mol)
Texit (K) pexit (bar) Composition (vol%)2)
H2 CO CO2 CH4
ydrogenydrogen1)
moniathanol
ldehydes/ alcoholseducing gas
2.54.53.73.01.81.15
112310731073112311381223
2727331717 5
48.6 9.2 5.2 5.934.6 5.3 8.0 2.439.1 5.0 6.0 5.550.3 9.5 5.4 2.628.0 25.9 19.7 1.170.9 22.4 0.9 1.5
rom naphthaRest is H2O
Typical Reformer ConditionsIndustrial Processes
Pr
HHAmMeAR
1) F2)
Critical points??? Excess H2OCH4 slip
TTUUDelftDelft &CER
Methane slip
Temperature (K)
Met
hane
slip
(% u
ncon
verte
d)
0
10
20
30
40
50
60
1000 1050 1100 1150 1200
1 bar
10 bar
20 bar
30 barH2O/CH4 = 3
Temperature (K)
Met
hane
slip
(% u
ncon
verte
d)
1050 1100 1150 12000
10
20
30
40
50
60
70
80
1000
H2O/CH4 = 1
H2O/CH4 = 2
H2O/CH4 = 3
H2O/CH4 = 5
p = 30 bar
Practical conditions H2O/CH4 = 2.5 - 4.5T: 1090 - 1150 KP: 7 - 30 bar
TTUUDelftDelft &CER
New Processes
Coke problem, in particular for heavy feed stocksCoke problem, in particular for heavy feed stocks–– prepre--reformer at low temperaturereformer at low temperature
Investment largeInvestment large–– ““autothermicautothermic” reforming” reforming
Exergy Exergy loss enormousloss enormous–– membrane reactormembrane reactor
»» equilibrium is shifted (palladium for Hequilibrium is shifted (palladium for H22 permeation)permeation)»» OO22 plant avoided (Oplant avoided (O22 permeation from air)permeation from air)
Other chemical routesOther chemical routes–– methane (catalytic partial oxidation, CPO)methane (catalytic partial oxidation, CPO)–– ethane (catalytic partial oxidation)ethane (catalytic partial oxidation)–– methanol (catalytic decomposition)methanol (catalytic decomposition)
TTUUDelftDelft &CERCnHm + H2O → CH4 + CO2/CO
Steam Reformer with Prereformer
770 K
Superheated HP Steam
Fuel
Air
Feed
Process steam
Reformer
Desulfurizer
BFW
Flue gas to stack
Hot raw syngas
Pre-reformer
TTUUDelftDelft &CER
CH4 + O2 → CO + 2 H2
CH4 + 2 O2 → CO2 + 2 H2O
CH4 + H2O ↔ CO + 3 H2
CH4 + CO2 ↔ 2 CO + 2 H2
Syngas
Natural gas Steam
Oxygen
Burner
Catalyst bed
Combustion zone ≈ 2200 K
Reforming zone 1200 - 1400 K
20 - 100 bar
Molar feed ratio
H2O/CH4 = 1 - 2
O2/CH4 ≈ 0.6
“Autothermal” Reforming
Composition syngas?Why O2, not air?Investment high or low?T-profile in reactor?
TTUUDelftDelft &CER
ICI Combined Reforming Exxon CAR
Gas-heated reformer
Autothermicreformer
Oxygen
Syngas
Natural gas Steam
Combined autothermicreformer
Catalyst
Dense phase with catalyst
Natural gas Steam
Syngas
Oxygen
Catalyst
Heat-integrated ReformersHot gas from the Hot gas from the autothermal autothermal reformer used for steam reformingreformer used for steam reforming
TTUUDelftDelft &CER
Exergy •• Quality of energy in > quality of energy out Quality of energy in > quality of energy out
–– (quantity remains the same: first law)(quantity remains the same: first law)
•• ExergyExergy losses in processlosses in process–– External lossesExternal losses
»» emissions to environment (e.g. in offemissions to environment (e.g. in off--gas), similar to energy gas), similar to energy losses (‘spills’)losses (‘spills’)
–– Internal lossesInternal losses»» physical (heat exchange, compression) & chemical (depend on physical (heat exchange, compression) & chemical (depend on
process and reaction conditions)process and reaction conditions)
reformer29%
methanol synthesis
24%
distillation38%
rest9%
reformer78%
methanol synthesis
7%
distillation8%
rest7%
Energy spill Exergy loss
ExergyExergy analysis analysis methanol methanol production (ICI)production (ICI)
TTUUDelftDelft &CER
Methane (Hydrocarbon) Partial Oxidation
•• NonNon--catalytic partial oxidation (SGP process)catalytic partial oxidation (SGP process)–– Very high temperature (1650 K)Very high temperature (1650 K)–– Small amounts of soot are producedSmall amounts of soot are produced
»» →→ extensive extensive gasgas--cleanclean--upup
•• Catalytic partial oxidation (CPO) Catalytic partial oxidation (CPO) –– Relatively low temperature (900 Relatively low temperature (900 –– 1300 K)1300 K)
»» Less loss of Less loss of exergyexergy»» Less severity for materialsLess severity for materials
–– No soot formationNo soot formation–– Very fast reaction (residence time, 0.5 Very fast reaction (residence time, 0.5 –– 4 ms)4 ms)
»» →→ small equipmentsmall equipment–– No commercial process yet existsNo commercial process yet exists
•• Both processes require pure oxygen (capital intensive Both processes require pure oxygen (capital intensive cryogenic distillation)cryogenic distillation)
TTUUDelftDelft &CER
Mechanism and Thermodynamics (CPO)O2
CH4 CO + H2
CO2 + H2OO2
CH4
O2
Mildly exothermal
Highly exothermalEn
doth
erm
al
•• Dominant pathway depends on: Dominant pathway depends on: –– Catalyst (and support)Catalyst (and support)
RhodiumRhodiumdirect CO + Hdirect CO + H22 formationformation
RutheniumRutheniumcombustioncombustion--reformingreforming
–– Oxygen partial pressureOxygen partial pressure•• Coke formation occurs at low OCoke formation occurs at low O22
partial pressurepartial pressure
•• Synthesis gas formation is favored by: Synthesis gas formation is favored by: –– Low pressureLow pressure–– High temperatureHigh temperature–– CHCH44:O:O22 ≤≤ 22
TTUUDelftDelft &CER
Considered Reactor Types
•• Immobile catalystImmobile catalyst–– Fixed bedFixed bed–– (Foam) Monolith(Foam) Monolith–– GauzeGauze–– Coated wallCoated wall
•• Reactant feedingReactant feeding–– Continuous flowContinuous flow–– Reverse flowReverse flow–– Alternating flowAlternating flow
»» OO22 CHCH44 OO22–– OO22 membrane
Synthesis gas
MethaneOxygen
FluidizedFluidized bedbedreactorreactor
Synthesis gas
Reduced cat.
Oxidised cat.riser
AirMethane
Riser reactorRiser reactor
Synthesis gas
MethaneOxygen
membrane
TTUUDelftDelft &CER
Reactor Temperature Profile
Hot spot formationHot spot formation–– ∆∆T up to 600 KT up to 600 K–– promotespromotes
»» Catalyst sinteringCatalyst sintering»» Active metal evaporationActive metal evaporation»» Migration of active metal into Migration of active metal into »» supportsupport»» Coke formationCoke formation
–– Detrimental to catalyst stabilityDetrimental to catalyst stability
•• Solution?Solution?–– increase heatincrease heat--transfertransferCatalytic bed length (-)
10
1000
600
1400
Tem
pera
tur e
(o C)
Adiabatic Temperature
mainly total oxidation
mainly reforming
> pO2 < pO2
TTUUDelftDelft &CER
Commercial CPO Process
•• Requirements: Requirements: –– Good catalyst stabilityGood catalyst stability
Mechanical (fluid bed and riser reactor)Mechanical (fluid bed and riser reactor)Activity and selectivityActivity and selectivity
–– Cheap oxygen supply (oxygen separation membrane)Cheap oxygen supply (oxygen separation membrane)Inside or outside reactorInside or outside reactor
–– High flow rate (small equipment)High flow rate (small equipment)»» High catalyst activityHigh catalyst activity»» Limited mass transfer limitation (catalyst utilization, Limited mass transfer limitation (catalyst utilization,
expensive noble metals)expensive noble metals)–– Suppression of total oxidation reactions (hotSuppression of total oxidation reactions (hot--spots)spots)
»» Good conductive heatGood conductive heat--transfertransfer»» Internal heatInternal heat--exchangeexchange
TTUUDelftDelft &CER
CPO (Fuel Cell Application)
VaporizerHydrocarbons (Petrol, Diesel)
CPO WGS CO ox
H2 + CO2
Fuel Cell
Exothermal processesOxygen
or
Natural Gas
WaterH2O + CO2
Air
TTUUDelftDelft &CER
Production Raw Syngas for NH3 synthesisN2 + 3 H2 ↔ 2 NH3
BackgroundO-containing molecules poison ammonia synthesis catalyst (Fe)
purification steps; CO removal, CO2 removal
Component (mol%)H2N2COCO2CH4Ar
56.3422.2012.768.180.220.30
60.0220.163.33
15.850.210.25
61.1519.770.40
18.240.200.24
74.6824.100.490.200.240.29
74.0624.69
< 5 ppm< 5 ppm
0.950.30
HT CO Shift57 m3
LT CO Shift61 m3
CO2removal
Methanation25 m3
640 K 710 K 490 K 510 K 590 K 640 KTo compression & ammonia synthesis
(61 m3)
Desulfurization24 + 27 m3
Steam reforming
17 m3
Autothermicreforming
33 m3
670 K 660 K 770 K 1020 K 1020 K 1270 K
CH4
H2
Steam Air
TTUUDelftDelft &CER
CO conversion: Water-gas shiftCO + H2O ↔ CO2 + H2
Temperature (K)
KpOHCO
COHp pp
ppK
2
22=640 K
710 K
490 K
510 K
HT shift LT shift
13 mol% CO
0.4 mol% COtoo high for Fe catalystModerately exothermal
Favourable: low T
TTUUDelftDelft &CER
CO conversion
•• Remaining CO removed byRemaining CO removed by methanationmethanationCO + 3 HCO + 3 H2 2 ↔↔ CHCH44 + H+ H22OO
–– But first COBut first CO22 removed by absorptionremoved by absorption
Removal system GJ/mol CO2
MEA 210
MEA with inhibitors 93-140
K2CO3 with additives 62-107
MDEA with additives 40-60
TTUUDelftDelft &CER
Fischer-Tropsch
TTUUDelftDelft &CER
Main reactionsAlkanesAlkenesWater-gas shift
n CO + (2n + 1) H2 → Cn H2n + 2 + n H2On CO + 2n H2 → CnH2n + n H2OCO + H2O ←→ CO2 + H2
Side reactionsAlcoholsBoudouard reaction
n CO + 2n H2 → H(-CH2-)nOH + (n-1) H2O2 CO → C + CO2
Fischer-Tropsch Process Product distribution
par 6.3
•• Product distribution depends onProduct distribution depends on»» CatalystCatalyst»» ConditionsConditions
•• T, T, ppCOCO, p, pH2H2, , pptottot
»» ReactorReactor»» Process designProcess design
Large variety: CH4. CO, CO2, H2O, alkanes, alkenes
TTUUDelftDelft &CER
Fischer-Tropsch Process - Mechanism
Product probability
initiation
1-αC2H4 C2H6
αpropagation
αpropagation
1-αCH4
termination
CO + H2
CH2 1-α
α(1-α)
1-αCnH2n CnH2n+2
αpropagation
αn -1 (1-α)
TTUUDelftDelft &CER
Fischer-Tropsch synthesis Kinetic schemeKinetic scheme
CO + 2HCO + 2H22 CCnnHH2n+22n+2 + H+ H22OO
00,10,20,30,40,50,60,70,80,9
1
0 0,2 0,4 0,6 0,8 1chain growth probability
mas
s fr
actio
n
methanemethane
ethaneethane
propanepropanebutanebutane
gasolinegasoline dieseldiesel
waxwax
αα
CC22HH44
CC33HH66
CC44HH66
CHCH44
CC22HH66
CC33HH88
CC44HH1010
C*C*
CC22**
CC33**
CC44**
CC55**
......
......
αα11--αα
•• What products would you try to synthesize?What products would you try to synthesize?•• αα, , Process?Process?
TTUUDelftDelft &CER
Anderson-Schulz-Flory Distribution
00.10.20.30.40.50.60.70.80.9
1
0 0.2 0.4 0.6 0.8 1
chain growth probability
mas
s fr
actio
nmethanemethane
ethaneethane
propanepropanebutanebutane
gasolinegasoline dieseldiesel
waxwax
•• Maximum diesel selectivity 39.4% with Maximum diesel selectivity 39.4% with αα = 0.87= 0.87
How to maximise diesel???
high high αα catalyst and subsequent cracking of waxcatalyst and subsequent cracking of wax
TTUUDelftDelft &CER
Reactor design??
•• Reaction highly exothermalReaction highly exothermal•• Temperature influences product distributionTemperature influences product distribution
–– Highly dependent on catalyst, roughlyHighly dependent on catalyst, roughly»» > 530 K carbon deposition> 530 K carbon deposition»» < 570 K wax deposition< 570 K wax deposition»» Viscosity product mixture increases at lower TViscosity product mixture increases at lower T
•• HH22/CO ratio influences product distribution/CO ratio influences product distribution•• Paraffins Paraffins do not react furtherdo not react further•• Olefins do reactOlefins do react
–– To To paraffinsparaffins–– InsertionInsertion
TTUUDelftDelft &CER
Fischer-Tropsch Process - Reactors
Gaseous products
Syngas
Liquid products
Steam
Multi-tubular fixed-bed reactor
Products
Slide valves
Riser
Standpipe
Cooling oil in
Cooling oil out
Syngas
Riser reactor
Syngas
Liquid products
Gaseous products
Cooling water
Steam
Slurry reactor
Cooling water
TTUUDelftDelft &CER
Multi-tubular fixed-bed reactor
Riser reactor Slurry reactor
ConditionsInlet T (K)Outlet T (K)Pressure (bar)H2/CO feed ratioConversion (%)
496509251.760 − 66
593598232.5485
533538150.68*
87Products (wt%)CH4C2H4C2H6C3H6C3H8C4H8C4H10C5 – C11 (gasoline)C12 – C18 (diesel)C19
+ (waxes)Oxygenates
2.00.11.82.71.72.81.7
18.014.052.0
3.2
10.04.04.0
12.01.79.41.9
40.07.04.06.0
6.81.62.87.51.86.21.8
18.614.337.6
1.0
Fischer-Tropsch Process - Comparison of Reactors
TTUUDelftDelft &CER
Separation Separation
Fixed-bed FT
Alcohols Ketones
Aqueous phaseWax
Gasoline Diesel
Oil work-up
GasolineDieselFuel oil
Oligo-merization
Oil OilC3, C4
Off-gas
Oil work-up
Purification
Separation
Lurgi gasifiers
To towngas,ammonia
Oxygen plant
Power plant
Coal Coal WaterAir
O2
N2
H2O Electricity
Raw syngasCO2, H2S
Tar & oil work-up
Road primeCreosotePitch
Naphtha
Phenols
Hydro-genation
Waxes
Hydro-genation
NaphthaBTXLight NaphthaHeavy Naphtha
AutothermalreformerH2O
O2
Oxygenateswork-up
Riser FT
To towngas,ammonia
Off-gas
LPG Gasoline
Fischer-Tropsch Process - Sasol I
TTUUDelftDelft &CER
Separation
Slurry FT
Oxygenateswork-up
Hydro-dewaxing
Catalytic reforming
Isomerization
Diesel
Gasoline
Gasoline
H2O
C12+
C7 - C11
C5 - C6
C1 - C4 CO2removal
Cryogenic separation
Oligo-merization
LPGC3 - C4
Ethene
Autothermalreformer
CH4
Syngas
Purified syngas
Gasoline
Alcohols
Ketones
F-T Process - Sasol II and III Product Work-up
TTUUDelftDelft &CER
Wax synthesis Flash
Wax conversion
H2
Distillation
Fuel gas (including LPG)
NaphthaKeroseneGas oil
Syngas
F-T Process - Shell Middle Distillate Synthesis (SMDS)
TTUUDelftDelft &CER
Most favourite FTS reactorsSlurry bubble column reactorSlurry bubble column reactor
Gas Liquid
GasLiquid
Coolant in
Coolant out
Multi tubular fixed bed reactorMulti tubular fixed bed reactor
Liquid
Liquid
Gas
Gas
Coolant in
Coolant out
ConvenientConvenientSimple to scaleSimple to scale--up
Nearly isothermal conditionsNearly isothermal conditionsLow pressure dropLow pressure dropHigh catalyst efficiencyHigh catalyst efficiencyCatalyst renewal
up
Catalyst renewalBackmixingBackmixingCatalyst attritionCatalyst attritionModerate G/L mass transferModerate G/L mass transferLiquid Liquid –– solid separation
Low catalyst efficiencyLow catalyst efficiencyHeat exchange Heat exchange -- TT--profilesprofilesPressure dropPressure dropEven distributionsolid separation Even distribution
TTUUDelftDelft &CER
Fischer Tropsch Technology
•• Still room for improvementsStill room for improvements•• Systematic approachSystematic approach•• Structure in catalyst and reactorStructure in catalyst and reactor
–– MonolithsMonoliths–– StagingStaging–– Decoupling cooling Decoupling cooling -- reactionreaction
Staged slurry bubble column reactorStaged slurry bubble column reactor‘Air’‘Air’--lift recycle reactorlift recycle reactorMonolith loop reactorMonolith loop reactorStructured internalsStructured internalsSubcoolingSubcooling
Kinetics very importantKinetics very important
TTUUDelftDelft &CER
Proton-Exchange-Membrane (PEM) Fuel Cell
Negative bus plateHydrogen frame
Air frame
Anode
Cathode
Platinum catalyst
O2
H2
H2O
PEM
Positive bus plate
e- e- e- e- e- e- e-
e- e- e- e- e- e- e-
e-
e-
e-
e-
e-
e-
e-
e-O2
H2 H2
H+ H+ H+ H+Electricity
e-
e-
