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GasificationGasification

Low temperature (200-240°C) and mid pressure (20-30 bar) to promote F-T over methanation reaction

Active catalyst based on IRON or COBALT

Production of high molecular weight linear waxes for further hydroprocessing step to optimize the overall liquid production, because it is impossible to produce directly a well defined range of products (i.e. middle distillates)

Fischer-Tropsch Reaction

nCO + 2nH2 n(-CH2-) + n H2O ΔH=-167 kJ/mole

CO + 3 H2 CH4 + H2O Methanation (ΔH=-206 kJ/mole)CO + H2O CO2 + H2 Water Gas Shift (ΔH=-41 kJ/mole)2CO C + CO2 Boudouard reaction (ΔH=-172 kJ/mole)H2 + CO C + H2O Coke formation (ΔH=-133 kJ/mole)

MainMain featuresfeatures of of modernmodern GTLGTL--FT:FT:

LiquidFuels

Product

upgradingNG

F-T

synthesis

Syngas

Production

Fischer-Tropsch

Gas-to-Liquids (FT) Process

ProductProductUpgradeUpgrade

LPG

Kero/Diesel

NaphthaSyngasSyngas

GenerationGenerationH2

COFischerFischer--TropschTropsch

(CH2)

Technology –FT Process


LPG

Kero/Diesel

NaphthaSyngasSyngas



(CH2)

•Catalyst•Heat removal•Reactor design•Scale-up

Technical challenges

The Sasol Slurry Bed Reactor

The largest commercialThe largest commercial--sized FT reactor sized FT reactor -- SASOL SASOL Pictures Courtesy of Sasol


Technology – Product Upgrade


LPG

Kero/Diesel

NaphthaSyngasSyngas



(CH2)

•Catalyst•Capacity


History

Novocherkassk

History

FT Reactor CapacitiesFT Reactor CapacitiesHistorical overviewHistorical overview

0

2000

4000

6000

8000

10000

12000

14000

16000

1910 1930 1950 1970 1990 2010 2030

Bar

rel /

day

Prof. Franz Fischer Dr. Hans TropschProf. Franz FischerProf. Franz Fischer Dr. Hans TropschDr. Hans Tropsch

Sasol CFBR

Sasol FFBR

Shell SMDSFBR

RuhrchemieFBR

Oryx GTL SBCR

Mechanism

Mechanism: chain growth

Mechanism

Products

Kinetics

Catalysts

Co catalysts

SummarySummary: FT : FT CatalystCatalystActive Phase: Active Phase: CobaltCobalt, , IronIron

PromoterPromoterStructural: Structural: increase metal dispersion (Re, Zr, Hf, Ce) Reduction: Reduction: increase extent of reduction (Ru, Pd, Pt, Cu)Activity: Activity: prevent coke deposition (Noble Metals)Selectivity: Selectivity: alter the product distribution (Na, K, Cs)

Carrier: SiOCarrier: SiO22, Al, Al22OO33, TiO, TiO22, mix, mixStructural promoter itselfInfluence selectivity due to secondary reaction (i.e. acid sites)

Co Co basedbased catalystcatalystExpensiveHigh selectivity to long chainparaffinsLow selectivity to olefins and oxygenatesresistant to deactivationlimited WGS activity

Fe Fe basedbased catalystcatalystEconomicLow selectivity to long chainparaffinsHigh selectivity to olefins and oxygenatesWGS catalystFast deactivation (coke)

Catalysts

Reactors

Catalyst d> 1mm; Effectiveness factor below unity

Reactors

Fluidized beds

Slurry

Operation

Reactor comparison

Technologies

Plants

Sasol Synfuels, Secunda, South Africa, (2008)

SASOL II

Products from GTL-FT process

LPG 3%

Naphtha

Gasoline

Middle Distillates

Fuel Oil 20%

40%

27%

10%

Lubes/Waxes

Middle Distillates

LPG/Naphtha

0 - 30%

20 - 35%

50 - 75%

Refinery Barrel Yield(Brent, vol)

GTL Barrel(vol)

Typical FT product composition after upgrading is: 25% Virgin Naphtha, 25% Jet Fuel and 50% Diesel

and minor amounts of LPG and bottom hydrocracking. The heavier fraction can be usedfor the production of lubricating bases or chemicals.

-1

- 11

55

22

4.5

835

180-360

Blu Blu DieselDieselAgipAgip

0

- 15

> 51

30

50

820 – 845

180-360

ConventionConventionalal DieselDiesel

-15 n.d.Cloud point (°C)

- 20 - 12CFPP* (°C)

> 70 56 Cetane number (CN)

< 0.13Aromatics (% vol)

< 1 6Sulfur (ppm vol)

780805Density @ 15°C (kg/m3 )

150-360180-275Boiling range (°C)

FT FT ––DieselDiesel

##

SWCL1SWCL1QualityQuality

* Cold Filter Plug Point;

ConventionalConventional vs. vs. GtLGtL DieselDieselGtLGtL Technology: Technology: HydrocrakingHydrocraking

# Diesel from waxes produced on pilot runs

G.Olah : Beyond Oil and Gas: The Methanol Economy

- storing energy in the form of methanol

– excellent fuel; easily stored, transported and used

Methanol

CO+2H2 CH3OH, ΔH=-90.8 kJ/mol

CO2+3H2 CH3OH+H2O, ΔH=-49.6 kJ/mol

CO+H2O CO2+H2, ΔH=-41 kJ/mol

T lowBy-products: higher alcohols and hydrocarbons from COPhase: gasCatalyst: selective CuZn/Al2O3

Methanol

Catalyst: sintering possible, thus t< 200-270oCdeactivation by S, C⇒(purification)

Operation policy : pressure increase with deactivation (not T)

Gas composition: 74% H2, 15% CO, 8% CO2, 3% CH4p=50-100 bar, conversion 15-30% in adiabatic reactor

Recycle of gases : recycle/make-up = 3-7 (range to avoid build up of CH4 and Ar)Products : distillationImprovements: 1) remove heat to keep reaction T as low as possible2)removal of methanol to shift equilibrium3) more active catalyst

Methanol

Methanol synthesis

Catalysts

Catalyst Activity

Operation policy: increase pressure, not T

Crude methanol analysis from a modern converter

Reactor: adiabatic

Tandem

Prices

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