1. Fischer-Tropsch Products
Separation Train
Team #6
Sydney Almeida
Ida Shinder
Emilia Tanu
Noah Wichrowski

2. PROCESS OVERVIEW GASIFICATION FISCHER-TROPSCH REACTION
SEPARATION AND PRODUCT UPGRADING
BIOMASS
COAL
NATURAL GAS
SYNGAS
(CO AND H2)
SYNTHETIC CRUDE OIL
DIESEL
NAPHTHA
JET FUEL 1 2 3
Step 2 results in long chain waxy molecules (to avoid unwanted small hydrocarbons/gas byproducts). From this step, a diesel fraction can be separated (not shown) by vacuum distillation (source: ) the remaining waxy products are then hydroprocessed ( hydro-isomerisation and hydrocracking) to produce the desired, lighter products. (Source: )
Adapted from (de Klerk, 2012).

3. Fischer-Tropsch (FT) Reaction
Catalytic chemical reaction where carbon monoxide (CO) and hydrogen (H2) produced by the gasification of coal (syngas) are converted to hydrocarbons or liquid fuel.
Main Reactions: (2n+1) H2 + n CO CnH(2n+2) + n H2O
2n H2 + n CO CnH2n + n H2O
Side Reactions: CO + H2O H2 + CO2
2n H2 + n CO CnH(2n+2)O + (n-1) H2O
2 CO C + CO2
The process objective is to produce hydrocarbons of larger
molecular weight and thus, products of higher economic value.
The side reaction is generally undesired, this reaction occurs during the gasification of coal, producing carbon dioxide. In gas to liquid processes, methane can be used as an FT reactant.
Time: 1 minute
Besides the hydrocarbons that must be separated - need to also get rid of water and +CO2
(for all reactions listed)
(van der Laan, 1999)

4. FT PRODUCTS
SEPARATION HEURISTICS:
CORROSIVENESS
MOLECULAR WEIGHT
COMPONENT CONDENSING ABILITY
COMPONENT SEPARABILITY
DESIRED PRODUCT IN THE DISTILLATE
COMPONENTS IN EXCESS
HYDROCARBONS
LIGHT (METHANE)
LIQUID (FUEL)
OLEFINS (ALKENES)
PARAFFINS (ALKANES)
LOW AMOUNTS OF OXYGENATES (ALCOHOL AND ORGANIC ACIDS)
DIESEL
GASOLINE
JET FUEL
NAPHTHA
PETROLEUM
FT products should be long/waxy hydrocarbons. Note 1/30 (8:23 PM): Add something about general desired undesired products, then specify for separation train specific.
= Wax and condensate (recovered from overhead vapor) separated from the catalyst in the reactor.
(Ghosh, Hickey, & Jaffe, 2006)
(Towler & Sinnott, 2013)

5. PROCESS FLOW DIAGRAM GASIFICATION FT REACTOR
SEPARATION AND PRODUCT UPGRADING
Note: recycle gases (C1-C4) back to FT reactor (not shown in PFD - could redirect the light recovery stream - there are multiple).
Although this PFD focus on Natural gas as the starting point of syn gas sequence - the choice of feed does not have a huge impact on product separation (?)
(Shuster, 2013)

6. SEPARATION SEQUENCE CO2 REMOVAL FUEL GAS/AQUEOUS OXYGENATES
FRACTIONAL DISTILLATION
(Shuster, 2013)

7. Fractional Distillation
Citation:
(Bowen, Irwin, & Canchi, 2007)

8. Fractional Distillation
Product fractionator divides hydrocarbons into vapor stream (light hydrocarbons) and three liquid streams. The vapor stream is combined with light hydrocarbon recovery from product upgrading into the fuel gas pool.
NAPHTHA
MIDDLE DISTILLATE
WAX
HYDROTREATING
HYDROTREATING
HYDROCRACKING
Naphtha saturates up to 177 degrees C
Middle Distillate saturates between degrees C
Wax (heavy hydrocarbons) saturates after 343 degrees C
(Griesbaum et al., 2005; Cherqaoui & Villemin, 1994)

9. PRODUCT UPGRADING C4, C5/C6 ISOMERIZATION/ALKYLATION
NAPHTHA HYDROTREATING AND REFORMATION
WAX HYDROCRACKING
DISTILLATE HYDROTREATING
(Shuster, 2013)

10. Butane Isomerization and Alkylation
Converts nC4 to iC4 for better usage as a reactant for alkylation
C5/C6 isomerization changes n-paraffins to branched isoparaffins for a higher octane rating
Hydrogen is used to prevent dehydrogenation and coking
(Ophardt, 2003)
(Sie Neftehim, n.d.)

11. Naphtha Hydrotreating And Reformation
Uses hydrogen to convert olefins → paraffins
Reformation
Improves octane number by increasing aromatic content and decreasing olefin content
Produces hydrogen used in hydrotreating
Primary Reactions:
Dehydrogenation: naphthenes → aromatics
Isomerization: paraffins → branched paraffins
(first paragraph is good)
(Jechura, 2016)

12. WAX HYDROCRACKING TWO MAIN REACTIONS:
CATALYTIC CRACKING OF LONG CARBON CHAINS (WAX AND OILS) INTO LIGHTER, MORE VALUABLE HYDROCARBONS
SATURATING THE NEW HYDROCARBONS WITH HYDROGEN
Hydrocracking
-“Cracks” or fractionates gas oil, which has a higher boiling point, into the distillate molecules used in gasoline (with hydrogen and a catalyst)
-Reaction 1: catalytic cracking of long carbon chains into unsaturated hydrocarbons
-Reaction 2: saturation of these new hydrocarbons with hydrogen
-Hydrogen is also used to control the temperature of the process, as high temperatures are needed into hydrocracking but within safe limits
-Energy is consumed when the hydrocarbons are broken and released when the carbon hydrogen bonds are made
(“Hydrocracking …”, U.S. Energy Information Administration)

13. Distillate Hydrotreating
Improves quality of distillate products like:
Kerosene
Jet fuel
diesel oil
Product properties:
Smoke Point
Stability
Color
Odor
Aromatic Composition
(“Hydrotreating,” Shell Global)

14. QUESTIONS? COMMENTS? Summary?

15. References
Ansorge, J. “Shell Middle Distillate Synthesis: Fischer-Tropsch Catalysis in Natural Gas Conversion to High Quality Products,” Shell International Oil Products B.V (n.d.)
Bacha, J. et al. “Diesel Fuels Technical Review,” Chevron (2007).
Bowen, B. H.; Irwin, H. W.; Canchi, D. “Coal-to-Liquids (CTL) & Fischer-Tropsch Processing (FT),” Purdue University (2007).
Cherqaoui, D.; Villemin, D. “Use of a Neural Network to Determine the Boiling Point of Alkanes,” J. Chem. Soc. Faraday Trans., 1994, 90(1),
de Klerk, A. “Gas-to-Liquids Conversion,” US Department of Energy (2012).
"Distillate Hydrotreating." Honeywell UOP, Honeywell International Inc., 2017, Accessed 31 Jan
Ghosh, P.; Hickey, K. J.; Jaffe, S. B. “Development of a Detailed Gasoline Composition-Based Octane Model,” Ind. Eng. Chem. Res. 2006, 45,
Griesbaum, K et al. "Hydrocarbons" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim.
"Hydrocracking is an important Source of Diesel and Jet Fuel." U.S. Energy Information Administration, 18 Jan. 2013, Accessed 31 Jan
"Hydrotreating." Shell Global, Accessed 31 Jan
Jechura, J. "Gasoline Upgrading: Catalytic Reforming, Isomerization, and Alkylation." Colorado School of Mines (2016).
Accessed 31 Jan
Rockwell, J. “Gas-to-Liquids,” ConocoPhillips (2003).
Shuster, E. “Analysis of Natural Gas-to-Liquid Transportation Fuels via Fischer-Tropsch,” US Department of Energy (2013).
Sie Neftehim, LLC “Butane Isomerization Isomalk-3” (n.d.). Accessed 31 Jan
Towler, G. T.; Sinnott, R. Chemical Engineering Design: Principles, Practice, and Economics of Plant and Process Design, Butterworth-Heinemann: Waltham, MA (2013).
van der Laan, G. P. “Kinetics, Selectivity, and Scale-up of the Fischer-Tropsch Synthesis,” University of Groningen (1999).
“What is Gasoline?” Elmhurst College (2003), Accessed 31 Jan