Upgrading of Fischer-Tropsch

copyright reserved: Sasol Technology R&D, FTR and C1 Chemistry Research, HCC 19 August 2010

19 August 2010

Upgrading of Fischer-TropschProducts to Produce Diesel

Dieter Leckel Sasol Technology Research and Development

Haldor Topsøe Catalysis Forum 2010

Munkerupgaard, 19- 20 August 2010


The Fischer-Tropsch Process

Hans Tropsch

Franz Fischer and Hans Tropsch produced a liquid fraction at the Kaiser Wilhelm Institute (KWI) that they termed “Synthol”

Reaction conditions: 150 bar, 400– 450 °C, potassium carbonate impregnated iron filings

Work was based on studies by Mittasch and Schneider on conversion of mixtures of CO and H2 in the presence of heterogeneous metal catalysts;such as supported CoO(BASF, German Patent DRP 293,787 (1913); A. Mittasch, C. Schneider, US Patent 1,201,850 (1916).

1925


The beginning of an industry for the production of transportation fuels from synthesis gas (CO/H2)

To test the usefulness of the Synthol products, as transportation fuels, the oil layer was separated from the aqueous layer, de-acidified and fractionated by distillation and then subsequently

road tested using a 1922 model NSU motorbike.

Basic FT reaction: n CO + 2n H2 ≡ (-CH2-)n + nH2O (dHR = - 39.4 kcal/gmol)

…and the rest is history…


Fischer-Tropsch product distribution

α decreases with T or higher H2/CO ratios

HTFT LTFT


0.00

0.05

0.10

0.15

0.20

0 5 10 15 20 25 30 35 40 45

Carbon number

Mas

s fra

ctio

n

0

0.01

0.02

0.03

0.04

HTFT (iron fluidised bed, 340°C)

LTFT (cobalt slurry phase, 220°C)

LTFT (iron slurry phase, 240°C)

Arabian Light Crude

Fischer-Tropsch: HTFT vs LTFT


Representation of synthetic fuels production

Coal

Gas

Biomass

Syngas Production

Fischer-Tropsch

ConversionProduct

Upgrading

Synthetic Fuel


Typical process scheme of the FT plants in 1939-1945 Germany

Reference.: D. Leckel, Diesel Production from Fischer-Tropsch: The Past, the Presence and New Concepts, Energy & Fuels 2009, 23, 2342-2358.

Ruhrchemie AG FT production plant in Oberhausen, Germany, in 1930s

(Source: OXEA Deutschland GmbH)In 1940s: FT liquids production > 1 million tons/a


Sasol 1 integrated HTFT-LTFT plant in Sasolburg, South Africa (1950’s)

1955: Sasol’s first oil

ARGE FT reactors (1954)

Reference: D. Leckel, Diesel Production from Fischer-Tropsch-The Past, the Presence and New Concepts, Energy & Fuels 2009, 23(5), 2342-2358.

Sasol 1 (1953)


Sasol 1 plant Sasolburg, South Africa

The FT Sasol 1 plant built in the 1950s was based on iron catalysts produced in the same Ruhrchemie plant in Oberhausen until the mid-1960s – till 2005 a CTL facility

A.P. Steynberg, M.E. Dry (Eds.), Fischer–Tropsch Technology: Studies in Surface Science and Catalysis, Elsevier, 2004,, p. 152.

Sasol 1 plant in 2010: a NG based LTFT GTL plant (HT ATR)

J. Falbe (Ed.), Fischer–Tropsch-Synthese ausKohle, Stuttgart, Thieme, 1977.


Sasol FT Reactor Development

2.000 - 6.500 bpd

11.000 - 20.000 bpd

500 - 700 bpd

2.500 – 17.000 bpd


HTFT Synfuels Refinery in 2010at Secunda, South Africa

Sasol has produced from 1955 over 1.5 billion barrels of fuel and chemicalsbased on FT

Sasol Advanced

Synthol (SAS™), 1995

CFB-Synthol (1982)

A 160,000 bpd CTL facility (with additional NG intake)Supplies ca. 40% of RSA liquid fuels requirements


3 different Sasol technologies

Reference: P. Gibson, Coal to liquids at Sasol, Kentucky Energy Security Summit, CAER’s 30th Anniversary, 11 October 2007


Fischer-Tropsch vs. Crude oil

Compound classes

Compound class Crude oil HTFT syncrude LTFT syncrude

Linear paraffins major product > 20% > 60%

Naphthenes major product < 1% < 1%

Olefins none > 60% > 20%

Oxygenates < 1% O (heavies) 5-15% 5-15%

Sulfur compounds 0.1-5% S none none

Nitrogen compounds < 1% N none none

Metal containing compounds phorphyrines carboxylates carboxylates

Water 0-2% major by-product major by-product

Aromatics major product 5-10% none


High-Temperature Fischer-Tropsch (HTFT)

Synfuels CTL Refinery, Secunda, RSA, 2010


Synfuels HTFT CTL Refinery, Secunda, RSA


High-Temperature Fischer-Tropsch (HTFT) process (Synfuels Refinery, Secunda, RSA)

Sasol® FBDB™Gasification(LT)

Coal syngas

H2, CO

Col

dse

para

tion

ADU

VDU

SLO

Ethylene recovery

Propylene recovery

Olefin oligomerisation

DO

α-olefin recovery (chemicals)

Naphtha hydrogenation / reforming

Distillate Hydrotreater

Hydrodewaxing

Lightdistillate

Heavydistillate

Aqueous PhaseChemical Work-up

Condensate

Tar

Tar/Oil Hydrotreater

Tar Naphtha Hydrotreater

Tar distillate

Poly Petrol

TarPetrol

PE

HTFTPP


Fischer-Tropsch: Oxygenate and Olefin composition (no sulfur)

1. Alcohols

2. Carboxylic acids

3. Aldehydes

4. Ketones

5. Other oxygenates

6. Olefins

R-OH

R-C=OH

R-C-OHO

R-C-R`O

HTFT LTFT5.5% 0.9%

1.4% 0.1%

0.6%

3.5% 0.2%

1.8%

>60% > 20%


Typical component classes present in a HTFT straight-run distillate (GC-MS)

Component class Structure

n-Paraffins R1 R2

α-Olefins (linear) R1

Branched

internal olefins R1 R2

Oxygenates R1 OH R2 R3

O

R4

O

OH

Aromatics R1

Reference: D. Leckel, Diesel production in coal-based high-temperature Fischer-Tropsch plants using fixed bed dry bottom gasification technology, submitted to Fuel Proc. Technololgy.


Most common FT distillate hydrotreating reactions: Hydrodeoxygenation (HDO) and olefin saturation

Reaction ∆H° (kJ/mol) C12 olefin + H2 C12H26 -127 C12-OH +H2 C12-H + H2O -108 C9H19-COOH + 3H2 C10H22 + 2H2O -301 C9 ketone + 2H2 C9H20 + H2O -164 methyl undecanoate + 3H2 C11H24 + CH4 + 2H2O -265 (appr)


HTFT Distillate Refining:(Effect of oxygenates in feed) Loss of Olefin conversion during hydrogenation at low H2S tail gas levels

Sulfided CoMo/Al2O3 catalyst operated at 297-316 °C, 5.8 MPa and LHSV of 1.2 h-1

Stable operation

Reference: Lamprecht, D. Hydrogenation of Fischer-Tropsch synthetic crude. Energy Fuels 2007, 21, 2509

Constant addition of S to feed!


Typical properties of a hydrogenated HTFT distillate and standard crude oil diesel

Property HTFTa Crude oil derived

dieselb

T95 boiling point, °C 363 360

cetane number 60 55

viscosity at 40 °C, cSt 2.2 2.8

density at 15 °C, kg m-3 808 842

total aromatics (HPLC),

wt%

25 39

a Distillate Hydrotreater (DHT) product (Synfuels

refinery Secunda)

b Hart’s Diesel Fuel News, Vol 11, 12 March 2007



High-Temperature Fischer-TropschHTFT distillate lacks density

d20 °C 808 kg m-3


(EN 590/2004 spec.: d20°C 816.5 kg m-3)


High-Temperature Fischer-Tropsch (HTFT) process (Synfuels Refinery, Secunda, RSA)

2007-01-0029

Sasol® FBDB™Gasification(LT)

Coal

syngas

H2, CO

Col

dse

para

tion

ADU

VDU

SLO

Ethylene recovery

Propylene recovery

Olefin oligomerisation

DO

α-olefin recovery

Naphtha hydrogenation / reforming

Distillate Hydrotreater

Hydrodewaxing

Lightdistillate

Heavydistillate

Aqueous PhaseChemical Work-up

Condensate

Tar


Tar Naphtha Hydrotreater

Tar distillate

PolyPetrol& PP

TarPetrol

PE


Sasol® Fixed bed dry bottom (FBDB™) coal gasification

Pyrolysis zone500- 600 °C

Pyrolysis zone: Vaporization of volatiles from coal (2-3% tar)


Comparison of properties of hydrotreatedtar oil distillate and HTFT distillate

Property

Tar oil distillate

HTFT distillate

density at 15 °C, kg m-3 887.3 804.1 viscosity at 40 °C, cSt 2.33 2.23 HPLC-aromatics, mass % monoaromatics diaromatics polycondensed aromatics

25.50 24.0 1.20 0.30

22.45 22.2 0.24

<0.01 cetane number 38 63 CFPP, °C -7 -2 cloud point, °C -2 -1 phenolics, mg kg-1 58 <1 nitrogen, mg kg-1 6 <1 sulfur, mg kg-1 <1 <1

Hydroprocessing of tar distillate: 18.5 MPa, 350-400 °C, 0.25 h-1 lhsv

Hydroprocessing of HTFT distillate: 5.0 MPa, 290-350 °C, 1.5 h-1 lhsv



The integration and blending performance of hydroprocessed tar pyrolysis products from coal gasification with HTFT products provides a way to produce a finalon-specification CTL diesel blend


790

800

810

820

830

840

850

860

870

880

890

900

0 10 20 30 40 50 60 70 80 90 100vol% tar distillate added

dens

ity a

t 15°

C, k

g m

-3

EN 590:2005 minimum diesel density specification

HTFT dist.

Pyrolysis tar dist.


Blended Sasol Synfuels HTFT diesel

Reference: Leckel, D., Diesel Production from Fischer-Tropsch-The Past, the Presence and New Concepts, Energy & Fuels 2009, 23(5), 2342-2358.

Analysis Units Method Blended Synfuels

diesel Density @ 15 °C kg m-3 ASTM D4052 829 Distillation IBP °C ASTM D86 178 T10 °C 200 T50 °C 240 T95 °C 361 FBP °C 374 Flash point °C ASTM D93 70 Viscosity @ 40 °C cSt ASTM D445 2.23 CFPP °C IP 309 -1 Sulfur mg kg-1 ASTM D5453 <1 Cetane number ASTM D613 53 oxidation stability mg · (100ml)-1 ASTM D2274 0.4

MJ kg-1 42.8 net heating value MJ l-1

ASTM D240 35.3

total aromatics mass % ASTM D6591 36.8


Representation of synthetic fuels production: LTFT

Coal

Gas

Biomass

Syngas Production

Fischer-Tropsch

ConversionProduct

Upgrading

Synthetic Fuel

Sasol Oryx 34.000 bpsd Co-LTFT GTL PlantRas Laffan, Qatar


Sasol Slurry Phase DistillateTM (SPDTM)Low-Temperature Fischer-Tropsch (LTFT) process

33.5MJ/ℓNet heating value

0.14mass-%Aromatics

< 1vol-%Olefins80ppmOxygen

m

mg/100mℓ

cStkg/ℓ

Units

651HFRR WSD

0.21O2 stability

>72Cetane number1.97Viscosity @ 40°C

0.765Density @ 20 °C

Sasol SPDTM

LTFT distillateProperty

2007-01-0029

NaturalGas

Haldor TopsøeATR Reformer

syngas

H2, CO

CondensateWax &

Chevron Iso-cracking™

Recycle

LPG

Naphtha

Distillate

Ref.: D. Lamprecht, SAE International Fuels and Emissions Conference, 23 January 2007

Air


FT Product Work-up: HydrocrackingProcess Conditions (T, P, LHSV, H2/wax),Catalyst (Pt, NiMo-S) and Feed affect FT wax hydrocracking

Reference: Leckel, D., Noble Metal Wax Hydrocracking Catalysts Supported on High-Siliceous Alumina, Ind. Eng. Chem. Res. 2007, 46, 3505-3512.


Temperature

Conversion, yields and selected product properties from hydrocrackinga C15-C45 slurry Fe-LTFT wax fraction over a PtMo/SiO2-Al2O3 catalyst at 3.5 MPa, LHSV of 1.0 h-1 and a H2 to wax ratio of 1200 normal m3·m-3 wax

Yield (mass %) Temperature (°C)

Conversion (mass %) C1-C4 C5-C9 C10-C22

Distillate : Naphtha

iso-/n-paraffin

Distillate cloud point (°C)

360 35 0.6 6.1 28 4.6 4 -7 365 51 0.9 10 40 3.9 4.1 -11 370 81 2 19 60 3.1 5.1 -17

Reference: Leckel, D. O.; Liwanga-Ehumbu, M. Diesel-selective hydrocracking of an iron-based Fischer-Tropsch wax fraction (C15-C45) using a MoO3-modified noble metal catalyst. Energy & Fuels 2006, 20, 2330-2336.


Pressure

Distillate properties Pressure (MPa) Distillate : Naphtha iso-/n-paraffin Cloud point (°C) Cetane number

3.5 2.5 5.9 -28 71 5 4 4.8 -19 74 7 6 3.9 -8 78

Influence of hydrogen pressure on isomerisation. Hydrocracking of a slurry Fe-LTFT wax over a PtMo/SiO2-Al2O3 catalyst at 380 °C, LHSV of 1 h-1 and a H2 to wax ratio of 1200 normal m3·m-3 wax

Reference: Leckel, D. Low-pressure hydrocracking of coal-derived Fischer-Tropsch waxes to diesel. Energy Fuels 2007, 21, 1425-1431


Iso/n-paraffin ratio determines distillate cold flow properties

Reference: Leckel, D. Low-pressure hydrocracking of coal-derived Fischer-Tropsch waxes to diesel. Energy Fuels 2007, 21, 1425-1431


Feed Impacting Hydrocracking of Fe-LTFT wax (Oxygenate effects)

40

45

50

55

60

65

70

75

80

355 360 365 370 375 380 385Temperature, °C

Die

sel s

elec

tivity

, %

Unhydrogenated Fe-LTFT wax

Hydrogenated Fe-LTFT wax

Reference: Leckel, D. Selectivity effect of oxygenates in hydrocracking of Fischer-Tropsch waxes. Energy Fuels 2007, 21, 662.


Hydrocracking of Hydrogenated (H) andUnhydrogenated (UnH) Fe-LTFT

Sulfided NiMo/SiO2-Al2O3 Catalyst at 7.0 MPa, 0.55 h-1 LHSV, H2-to-Wax Ratio of 1500:1 m3/m3



Effect of Carboxylic acids and Alcohols on Hydrocracking of Fe-LTFT C80 Wax

PtW75 noble metal catalyst, 370 °C and 7.0 MPa

Possibility to manipulate product spectrum by selective addition of oxygenates

Bouchy, C., Hastoy, G., Guillon, E., Martens, J.A. Oil Gas Science and Technology – Rev. IFP, Vol. 64 (2009), No. 1, pp. 91-112



Properties of LTFT Distillates

42<5<5<5sulfur, mg kg-1

363

165

64

60

22.6

808.2

SasolHTFT

39.40.70.3total aromatics, mass%

360353-T95, °C

-154210IBP, °C

>556072flash point, °C

55>70>70cetane no.

841.7772.1784.5density at 15 °C, kg m-3

standard Crude diesel

SasolLTFT

ShellLTFT

Reference: Hart’s Diesel Fuel News, Vol 11, 12 March 2007.


LTFT distillate lacks density

d20 °C 770 kg m-3

(EN 590/2004 spec.: d20°C 816.5 kg m-3)


LTFT GTL/CTL applications using SASOL® fixed bed dry bottom™ (FBDB™) coal gasification and NG Reforming


NaturalGas

HT ATRReformer

syngas

H2, CO

WaxCondensate Hydro-

cracker

Recycle

LPG

Naphtha

Coal Sasol®FBDB™gasification

syngas

H2, CO

Distillate

Diesel

Distillate


Tar - LTFT GTL/CTL diesel fuel blend density

With diesel density blending linearly, the highly aromatic tar diesel not increases the density, but also the net volumetric heating value and viscosity of a LTFT GTL/CTL diesel blend

Linear density and cetane number response of a LTFT CTL diesel blend

0.76

0.78

0.80

0.82

0.84

0.86

0.88

0.90

0 20 40 60 80 100vol-% tar distillate

Den

sity

@ 1

5 °C

(kg/

L)

0

10

20

30

40

50

60

70

80

Cet

ane

num

ber

Density @ 15 °C Cetane number

Density

Cetane number

Reference: Lamprecht, D.Nel, R., Leckel, D., Production of on-specification fuels in Coal-to-Liquids (CTL) Fischer-Tropsch plants based on fixed bed dry bottom coal gasification, Energy & Fuels 2010, 24, 1479-1486


Thanks for your attention

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Upgrading of Fischer-Tropsch