Edible Oils – Intro Oils & Fats (Triglycerides) Hydrogen Concentration Selectivity Effects of changing Temperature & Pressure Impurities that affect the catalyst Filtration

1. Hydrogenation
of Edible Oils

2. Overview
 Edible Oils – Intro
 Oils & Fats (Triglycerides)
 Hydrogen Concentration
 Selectivity
 Effects of changing Temperature & Pressure
 Impurities that affect the catalyst
 Filtration

3. Edible Oils
 Global production of oils and fats
113 million metric ton / year (MMT/yr)
 Average consumption is about 15kg (30lbs) /person
• lower in some countries e.g. 7kg (15lbs) in Sudan
& Bangladesh
• higher in some countries e.g. 40kg (88lbs) in USA

4. • Palm Oil (PO)- Primarily derived from the palm oil plantations
in Malaysia and Indonesia is the major feedstock in Asia.
• Sunflower - Predominantly grown in Eastern Europe.
• Fish oil (FH) - Predominantly used in Chile/Peru.
Was popular in UK, Norway, Japan.
• Canola/Rapeseed - Predominantly grown in Canada and
northern Europe. Typically has higher poisons than soya.
• Soyabean Oil (SO)- Primarily derived from the
major soya states in the US, Brazil and Argentina.
• Tallow - animal fat, usually a by-product of
rendering. Lard from pigs also used.
Where do edible oils come from?

5. Hydrogenation Process
Crushing Refining
Filtration
Blending/
Packaging
/Delivery
Ni catalyst
in
Ni catalyst
out
Oil Seeds
Hydrogenation
Product
Post
bleaching/
Deodorization

6. Where the hydrogenated oils go….

7. What is an oil / fat?
 Fat (triglyceride) molecule
• 3 chains of carbon (C) atoms (green)
• Hydrogen (H) atoms attached to carbon (white)
• C atoms joined by glycerol “backbone” (red OH groups)
 How much hydrogen attached is related to “saturation” of fat

8. Oil / fat types
 Notation CX:Y (e.g. C18:2)
• X = number of carbon atoms in chain (18)
• Y = number of double bonds in chain (2)
 Cis double bond (same side)
…-C-C-C C-C-C-…
C=C
• Trans double bond (opposite side)
…-C-C-C
C-C-C-…
C=C

9. Oleochemicals
 Can “split” the chain off the glycerol backbone
to get glycerin and fatty acids
 Fatty acids main building block of the
oleochemical industry
 Form components of:
• soaps & shampoos
• rubber tires
• Cosmetic cremes
• fabric softeners
• detergents
• lubricants

10. Why Hydrogenate?
 Main objectives of hydrogenation
• improve flavor stability
• adjust melting characteristics

11. Hydrogenation reaction
 Simple reaction - chemically:
Oil + H2 “hardened” Oil
Ni
• Physically difficult
3 components, 3 phases
-Oil Liquid
-H2 Gas
-Ni Solid

12. The “Art” of Hydrogenation….
 ….is getting all 3 components in the same place at
the same time!

13. Key parameters
 Catalyst
• type (e.g. VULCAN VIG Series)
• dosage
 Hydrogen concentration
• Pressure
• Temperature
• Mixing/Agitation

14. Reaction requires: 1 1
In reactor: 1000 1
Not enough hydrogen!
Why is H concentration
important?

15. Hydrogen
Concentration
Why is H concentration
important?
Melting Point
Pressure
Temperature
Catalyst
Dosage
SFI curve
Stability
Trans Content
At given RI / IV
Reaction Time

16. Pressure = Driving force for H2 diff.
 In general, as pressure increases the more H2
available at the catalyst surface for reaction.
In actual fact solubility of H2 is the driving force but this is
proportional to pressure.
H2 gas
H2
liquid

17. Pressure = Driving force for H2 diff.
 In general, as pressure increases the more H2 available at the
catalyst surface for reaction.
gas
H2
H2
liquid

18. Temperature affects rate of reaction
 In general, as temperature increases the less H2 available at
the catalyst surface for reaction.
Hardened OilH2
liquid
Oil +
k

19. Mixing - replaces reacted H2
 Mixing is often over-looked and is the limiting factor in the
hydrogenation reaction in many cases.
H2 H2

20. oil
phase
Nickel
surface
Hydrogenation reactions occur
at Nickel surface
 The amount of nickel is not as important as how it
is distributed
- Nickel Surface area is more relevant than nickel
mass!
adsorbed molecules
C=C
R R
HH
1 2
H H
R
R
H
H
1
2
C
C
H
R R
HH
1 2
C C
R R
HH
1
2C C
H H
cis-
unsaturated
trans-
unsaturated saturated
C=C
R H
H
3
R4
H H

21. Selectivity
in EO Hydrogenation
How to influence product
properties

22. C18:2 C18:1cis C18:0
C18:1 trans
Many chemical reaction - including TG hydrogenation - have
intermediate products and side products:
“Selectivity” means the ability of capturing (desired)
intermediate products ( + , -- )
Selectivity Definition

23. Selectivity in edible oil
hydrogenation
 polyene selectivity
 trans selectivity

24. Polyene selectivity
 More selective
• Reacts C18:3 to C18:2 without reacting too much
C18:1 to C18:0
• Gives good color and oxidative stability without
raising the melting point too much
• Not as much tailing (due to too much C18:0) in SFC
curve
 Less Selective
• Hydrogenates any double bonds
• Some C18:3 remain while C18:0 increase and m.p.
increases
• gives flatter SFC curves
C18:3 C18:2 C18:1 C18:0

25. Polyene Selectivity
 Catalyst choice has a large influence
• Should use a selective catalyst when a very
selective reaction is required
 Hydrogen concentration has a large influence
• lower hydrogen concentration gives better
selectivity
• higher hydrogen concentration gives worse
selectivity but this can be overcome by using a
selective catalyst (e.g. VULCAN VIG)

26. Stability
Resistance to Oxidation
 Oxidation rates are directly linked to unsaturation:
C18:0
C18:1
C18:2
C18:3
=
=
=
=
1
10
100
200
• Oils / fats with higher C18:3 will go rancid and color quicker
• Oils / fats with lower C18:3 can be kept or used for longer

27. "Trans selectivity": (trans-)
isomerisation vs. hydrogenation
adsorbed molecules
C=C
R R
HH
1 2
H H
R
R
H
H
1
2
C
C
H
R R
HH
1 2
C C
R R
HH
1
2C C
H H
cis-
unsaturated
trans-
unsaturated saturated
C=C
R H
H
3
R4
H H
Nickel
surface
oil phase
The desired intermediate products are trans isomers

28. Melting Temperatures
Triglycerides
°C
C 12:0 30
C 16:0 65
C 18:0 73 (163F)
C 18:1 cis 5,5 (41.9F)
C 18:1 trans 42 (108F)
C 18:2 cis -13
C 18:3 cis -24

29. Solid Fat Content Curve
 A typical SFC curve at certain
conditions
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50
Temperature (C)
SolidFatContent(%)

30. Solid Fat Content Curve
 Areas of influence

31. Solid Fat Content Curve
 If H2 concentration decreased
OR
 if Sulfided Ni catalyst used
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50
Temperature (C)
SolidFatContent(%)

32. 0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50
Temperature (C)
SolidFatContent(%)
Solid Fat Content Curve
 If H2 concentration increased
OR
 If less selective catalyst used

33. 0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60
Temperature (C)
SolidFatContent(%)
“Tailing”
 If polyene selectivity poor, tailing will occur

34. Trans Selectivity
 Hydrogen concentration is one of the main
factors in trans selectivity
 Use of a sulfurized catalyst greatly increases
trans selectivity
• High trans products (low H concentration
or sulfurized catalyst)
 have steep melting curves and are often
used in candy or bakery products
• Low trans products (high H concentration)
 Used for “healthier” oils
 low trans products also have less solid
content at room temperature

35. Effects of increasing pressure
 There is a higher hydrogen concentration in the oil
• lowers trans selectivity
 less trans, less solids due to trans, less steep SFC
curve
• reduces polyene selectivity
 more C18:0 and related solids, less stable for
given IV, more tailing on SFC curve
• speeds up reaction
 Reducing the pressure will have opposite effects

36. Effects of increasing temperature
 There is a lower hydrogen concentration in the oil
• increases trans selectivity
 more trans, more solids due to trans, steeper SFC
curve
• increases polyene selectivity
 more stable for given IV, less tailing on SFC
curve, lower formation of C18:0 at given IV
• speeds up reaction
 Reducing the temperature will have opposite effects

37. Effect of process changes on hydrogen
concentration and subsequent effects
 *In general, the lower the hydrogen concentration at the
catalyst surface the greater the probability of forming trans.
However, there is also a time effect - longer reaction generate
more trans. This column only is considering the hydrogen effect.
 ** This refers to agitation “improving”, i.e. a better gas liquid
mass transfer and a better dispersion of hydrogen into the
liquid.
Process parameter Hydrogen
concentration
at catalyst
surface
Probability of
more trans
forming*
Hydrogenation
time
Pressure ⇑ ⇑ ⇓ ⇓
Temperature ⇑ ⇓ ⇑ ⇓
Agitation ⇑** ⇑ ⇓ ⇓
Catalyst dosage ⇑ ⇓ ⇑ ⇓
Catalyst activity ⇑ ⇓ ⇑ ⇓
Sulphur promotion, re-using
catalyst ⇑
⇓⇓ ⇑⇑ ⇑

38. Summary of Catalysis (EO)
 Need to get Oil, H2 and Ni at same place!
 Different catalysts for different needs
 Hydrogen concentration is often limiting
factor in reaction
 Hydrogen concentration influences
selectivity
 Hydrogen concentration determined by:
• Pressure
• Temperature
• Mixing
• Catalyst activity & dosage

39. Impurities to consider and effect on
catalyst
 Sulfur
• occurs in the plant and varies seasonally
• can also occur as a result of pre-processing (e.g.
copra)
• “sits” on Ni surface and blocks the active sites.
• Can deactivate catalyst and promotes trans
formation
 Phosphorous
• occurs in oils as lecithin and other phosphotides
• “gums” up the catalyst pores, thereby
deactivating it.
• Can also “gum up” the filter causing blockages.

40. Impurities …..
 FFA
• is present in crude oil (hence
neutralization or steam stripping step)
• being an acid, it will begin to dissolve
nickel metal, thereby deactivating some of
the catalyst if the FFA level is high.
 Water
• oil can become contaminated with water in
pretreatments and transport and storage
• it affects the nickel surface area and
lowers the activity of the catalyst
• if water is present the TG can be split in a
hydrolysis reaction, and form FFAs.

41. Impurities …..
 Soap
• ion exchange with Ni can occur
• Na+ can block Ni surface area too
 Pigment
• Chlorophyll, gossypol (in cottonseed oil), can
impart colours to the oil and this colour can
change after hydrogenation
 Oxidized fat
• Oil can oxidise in storage and this deactivates
catalyst

42. Filtration
 Reactor mix is filtered to remove the catalyst
 There is usually a maximum allowed residual
nickel content in the product
 2 types of residual nickel
• (a) Particulate nickel - small black particles
• (b) Dissolved nickel - soluble nickel soaps,
salts, etc
 Identifying which type:
• Can check if it is (a) by using a filter paper
check and particle analysis
• If no black dots on filter paper and still Ni in
ICP reading it is probably dissolved nickel

43. Removal of Residual Nickel
 (a) Particulate Nickel removed with
• Improved filter system
• use of filteraid
• stronger catalyst particles
 (b) Dissolved Nickel removed with
• post bleaching with citric or phosphoric acid
• use of bleaching earth
• reduction in FFAs and/or water in feed oil
• reduction in contact time without hydrogen

44. Glossary of terms
 C = carbon
 double bond = a C=C bond where there are two
links between two C atoms
 H = hydrogen
 kLa = gas-liquid mass transfer coefficient; a
measure of the agitation in the reactor
 lauric = C12:0
 LEL = lower explosive limit
 linoleic = C18:2
 linolenic = C18:3
 mono-unsaturates = triglyceride with just one
double bond e.g. C18:1
 myristic = C14:0
 Ni = nickel
 O = oxygen
 oleic = C18:1
 oleochemical = a chemical or material derived
from a triglyceride generally

45. Glossary of terms
 P = Pressure
 palmitic = C16:0
 polyene selectivity = the ability to
hydrogeante the higher unsaturated
compunds first
 poly-unsaturates = triglycerides with
more than one double bond e.g. C18:2,
C18:3
 saturated bond = a C-C bond where
there is only one link between the two
C atoms
 saturates= triglycerides with no
double bonds e.g. C18:0
 stearic = C18:0

46. Glossary of terms
 T = temperature
 t = time
 trans selectivity = the ability to
increase the trans isomerisation effect
and end trans level
 trans-fatty acid (TFA) = a fatty acid
chain with trans double bond, one
where the chain links are on opposite
sides of the double bond
 triglyceride = a molecule of part of a
fat or oil
 UEL = upper explosive limit
 unsaturated bond = double bond