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INDUSTRIESChE 313 Industrial Chemistry
LectureEngr. May V. Tampus
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OILS, FATS, & WAXES•
Fats and oils are composed primarily of triglycerides , esters of glycerol and fatty acids.
• Waxes are esters of fatty acids with long-chain
aliphatic alcohols, sterols, tocopherols, orsimilar materials.
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FATS & OILS
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World production of fats & oils
55%40%
5%
vegetable oilsland-animal fats
marine oils
Ullmann’s Encylcopedia of Industrial Chemistry, 6 th ed., 1998
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Classes of Fats & OilsBased on the Rate of Drying
Non-drying Oils Semi-drying Oils Drying OilsCoconut oilButterTallowPalm oilLard
Iodine no. = 9-65
Olive oilPeanut oilRapeseed oilCottonseed oilCorn oilSoybean oilSunflower oilSesame oil
Iodine no. = 85-130
Fish oilTungLinseed oilPerilla oil
Iodine no. = 150-200
Iodine number – a measure of the rate of drying of the oil
A process which results in the solidification of the fat or oil uponexposure to air which is caused by oxidation, or chemicalcombination with oxygen, rather than by evaporation of a solvent
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Common Types of Vegetable Oils
• Rapeseed/canola oil • Safflower oil• Coconut oil • Soybean oil• Corn oil • Sunflower oil• Cottonseed oil • Sesame oil• Olive oil • Peanut oil• Palm oil
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Composition Natural Fats & Oils•
Principal component: – Triglycerides which contain at least two different fatty acid
groups• The chemical, physical, and biological properties of oils and
fats are determined by the type of the fatty acid groups andtheir distribution over the triglyceride molecules.
Component of fats & oils %
triglycerides (triacylglycerides) 97
diglycerides (diacylglycerides) Up to 3
monoglycerides (monoacylglycerides) Up to 1
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Other Components of Fats & OilsMinor components of
Fats & OilsFormed by Found in
Free fatty acids & Partialglycerides (mono- &diglycerides)
Enzymatic cleavage of triglyceridesHydrolysis
Rice bran oil, Palm oil
Phospholipids Esterification of glycerides by fattyacids with phosphoric acid Coconut oilPalm kernel
Sterols derived biologically from terpenes Lard , Tallow, Butterfat ,Milk fat
condensation of isopreneunits
condensation of isoprene units Algae , Coconut oil, Olive oilWheatgerm oil, Soybean oil
Cottonseed oilCarotenoids &XanthophyllsChlorophyll
condensation of eight isoprene units hydroxylation of thecarotenoid skeleton
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Physical Properties of Fats & OilsPhysical property Description
Melting point -increases with increasing chain-length of the even-numbered saturated FA, and decreases witdegree of unsaturation-wide range of temperature-depends on the polymorphic form of the glycerides
Latent heat of fusion -increases with increasing chain length and increasing degree of saturation-Naturally occurring fats generally have a lower heat of fusion than simple glycerides.
Specific heat The specific heat of liquid oils and fats increases with increasing chain length and degree of satuincreases with temperature.
Density -decreases with increasing molecular mass and degree of saturation-A high free fatty acid content tends to decrease the density of a crude oil-Oxidation generally leads to higher densities.
Viscosity -Oils tend to have a relatively high viscosity because of intermolecular attraction between their fatty -Generally, viscosity tends to increase slightly with increasing degree of saturation and increasing chai-approximately linear relationship between log viscosity and temperature-The viscosity of oils tends to increase on prolonged heating due to the formation of dimeric and oligacid groups.
Solubility & miscibility -Nearly all fats and fatty acids are easily soluble in common organic solvents such as hydrocarbhydrocarbons, ether, and acetone.-The water solubility of fats is low and decreases with increasing chain length and with decreasing tem-The solubility of gases in oils generally increases with increase in temperature, the reverse holding dioxide
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RELEVANT CHEMICAL REACTIONS
Fats & Oils
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HydrolysisHydrolysis of glycerides into glycerol and fatty acids
Alkali hydrolysis (saponification) of glycerides
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Hydrolysis Description
• Reversible• Equilibrium can be shifted to the right via:
– Large excess of water – High temperature – High temperature
• Catalysts: – inorganic and organic acids, e.g., sulfonated
hydrocarbons – Enzymes, e.g., pancreatic lipase
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Interesterification
Random interesterificationor
Randomization
Directed interesterification
Transesterification occurs when a carboxylic
acid (acidolysis) or alcohol (alcoholysis)reacts with an ester to produce a different ester.Ester-ester interchange is also a form of transesterification.
Interesterification occurs when acyl
groups of glycerides are exchangedinter- and intramolecularly withoutaddition of acids or alcohols
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Interesterification in LARDH2 C – O – C – R1
HC – O – C – R2
H2 C – O – C – R3
O
O
O
+ NaK + H2O (trace)
H2 C – O – Na
HC – O – C – R2
H2 C – O – C – R3
O
O
KOCR1
O
+ H2+
Intramolecular interesterification
H2 C – O – C – R4
HC – O – C – R5
H2 C – O – C – R6
O
O
O
+
H2 C – O – C – R2
HC – O – Na
H2 C – O – C – R3
O
OIntermolecular interesterification
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Interesterification in LARD
H2 C – O – C – R4
HC – O – C – R5
H2 C – O – Na
O
OH2 C – O – C – R2
HC – O – C – R6
H2 C – O – C – R3
O
O
O+ , etc.
In directed interesterification, a molecule crystallizes when its three fatty acids are saturated.
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Interesterification Description
• Fats must contain only 0.1 % FFA and dried toavoid excessive deactivation of the catalyst
• Catalyst: 0.1-0.3 %sodium ethoxide, sodiummethoxide or Na-K alloy
• Temperature: 80 – 100 °C• Operating mode: batch or continuous
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Transesterification
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Transesterification: Acidolysis
• Example: transesterification of coconut oilwith acetic acid and subsequent esterificationof excess acetic acid with glycerol
• Catalysts: base (e.g., NaOH) or acid (HCl)• No catalyst is required at temperatures of 260
– 300 °C!
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Transesterification: Alcoholysis
• Example: transesterification of fats withmethanol as the first step in the continuousproduction of soap – Bradshaw process
• Catalysts: 0.1 – 0.5 % caustic soda• Temperature: ca. 80 °C
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Hydrogenation Description• Also termed as “hardening”• always leads to an increase in melting point• Partial hydrogenation can lead to isomerization of
cis double bonds to trans double bonds.• Catalysts: nickel , platinum, copper, or palladium• An exothermic process• Neither absolute selectivity nor complete
isomerization (or complete suppression of isomerization) can be achieved.• Operating mode: batch or continuous
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Batch Hydrogenation
• Scale of production: normally on a scale of 5 –25 t
• Catalyst: 0.01 – 0.1 % active nickel• Operating temperature: 100-180 oC• Usual working pressure: 0.15 – 0.3 MPa (1.5 –
3 bar)
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Production Ni catalyst from Nickel formate
• Methods:1. Liquid-reduced process2. Wet-reduced process
• Operating temperature: 160-240 oC (though 160 oC is more
common)• Operating pressure: 200-700 kPa• Chemical Reaction:
O H H CO NiO H HCOO Ni 22222 222
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Isomerization• Naturally occurring fatty acids exist predominantly in the cis form.• An equilibrium mixture in which the higher melting trans form predominates can
be formed by heating to 100 – 200 °C in the presence of catalysts such as nickel,selenium, sulfur, iodine, nitrogen oxides, or sulfur dioxide.
• If reaction times and temperatures (above 200 oC) are extended, linolenic acid canbe converted into cyclohexadiene and benzene derivatives :
Isomerization can occur if oils and fats are heated attemperatures above 100 °C in the presence ofbleaching earth, kieselguhr, or activated charcoal.
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AutoxidationAutoxidation – oxidation of olefins withoxygen; involves the formation of ahydroperoxide on a methylene groupadjacent to a double bond ; this stepproceeds via a free-radical mechanism
Photooxygenation - light-induced oxidation leads to a fast buildup of radicals
The intermediate hydroperoxides are labilecompounds that decompose into a number of different products : epoxides, alcohols, diols, ketocompounds, dicarboxylic acids, aldehydes, andisomerization and polymerization products. Thevolatile carbonyl compounds formed in thisprocess are responsible for the taste and odor of oxidized oils and fats.When the radical concentration has reached acertain limit, the chain reaction is gradually
stopped by mutual combination of radicals.
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Industrial Uses of Fats & Oils
Fats & Oils Uses
Animal Fats Soaps, greases, paints, varnishes, syndets, fatty acids, & plasticizers
Coconut oil Fatty alcohols, soaps, & detergents
Linseed oil Paints, varnishes, floor coverings, lubricants, & greases
Soybean oil Paints, varnishes, floor coverings, lubricants, & greasesCastor oil Protective coatings, plastics, plasticizers, lubricants, hydraulic fluids
Tung oil Paints & varnishes
Tall oil Soaps, leather, paint, emulsifiers, adhesives, ink
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WAXES
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What are WAXES?• According to German Association for Fat Science waxes must have :1. A drop point (mp) >40 °C2. Their melt viscosity must not exceed 10 000 mPa · s at 10 °C above the drop
point3. They should be polishable under slight pressure and have a strongly
temperature-dependent consistency and solubility4. At 20 °C they must be kneadable or hard to brittle, coarse to finely
crystalline, transparent to opaque, but not glassy, or highly viscous or liquid5. Above 40 °C they should melt without decomposition6. Above the mp the viscosity should exhibit a strongly negative temperature
dependence and the liquid should not tend to stringiness7. Waxes should normally melt between ca. 50 and 90 °C (in exceptional cases up
to 200 °C)8. Waxes generally burn with a sooting flame after ignition9. Waxes can form pastes or gels and are poor conductors of heat and electricity
(i.e., they are thermal and electrical insulators).
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Waxes are characterized bythe following:1. Composition: Complex mixtures of compounds2. Melting point: may vary over a wide range, usually above of the harder
fats & fatty acids.3. Phase: Solid at ambient temperature while liquid at 38o C to 93o C.4. Solubility: Insoluble in water 5. Combustibility: combustible6. Thermoplastic in nature7. Some waxes have very good wetting or penetrating qualities8. Most waxes exhibit low surface tensions9. Most waxes are non-adhesive and slippery10. Certain waxes are incompatible with other waxes, resins and other
materials11. Admixtures of higher melting materials does not necessarily raise the
melting pint of waxes proportionally
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Classes of Waxes
Natural Waxes Partially SyntheticWaxes
Fully Synthetic Waxes
Fossil waxesNonfossil or recent
natural waxesModified natural waxes
Esterified waxesAmide waxesAlcohol (lanette) waxesWool wax (Lanolin)
C1Building BlocksPolyolefin waxes
Waxes can also be classified as:a. Vegetable waxesb. Animal waxes
c. Insect waxes
d. Mineral waxese. Synthetic waxes
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Vegetable WaxesVegetable Wax Carnauba wax Candelilla wax Japan wax Jojoba oil
Source fronds of palm tree almostexclusively grown in the semiaridregion of Brazil
stalks and leaf stems of plants,which grow as bushes or shrubs:Euphorbia (E. cerifera, E.
antisyphilitica) and Pedilanthus (P. pavonis, P. aphyllus) species
berries of a small treenative to Japan and Chinacultivated for its wax
seeds of the jojoba plant grownin semiarid regions of CostaRica, Israel, Mexico, and the
United States
Composition aliphatic and aromatic esters oflong-chain alcohols and acids, withsmaller amounts of free fattyacids (FFAs) and alcohols, andresins
hydrocarbons, esters of long-chainalcohols and acids, long-chainalcohols, sterols, and neutralresins, and long-chain acids
triglycerides, primarilytripalmitin
ca 80 wt % of esters of eicos-11-enoic and docos-13-enoiacids, and eicos-11-en-1-ol, andocos-13-en-1-ol, ca 17 wt % oother liquid esters, with thebalance being free alcohols,free acids, and steroids
Importantproperties
one of the hardest and highest-melting natural waxesreadily soluble in most nonpolarsolvents on warming but partiallysoluble in polar solventshas a weakly aromatic odor and a
characteristic haylike scent(similar to coumarin) in themolten stateacid number of 8, and asaponification number of 80
hard, brittle wax that is very similarto carnaúba wax with regard tosolubility in polar and nonpolarorganic solventsmelting point of 70°C, a penetrationof 3 dmm at 25°C, an acid number
of 14, and a saponification numberof 55
• melting point of 53°C, anacid number of 18, and asaponification number of 217
virtually colorless to goldenyellow, odorless, unsaturatedoilMelting point of 6.8– 7.0 °C;saponification number of 92and acid number of 2
Uss & applicatios Pigments, inks, gels, polishes,solvent and oil paste formulation,cosmetics, castings and food
cosmetics, foods, andpharmaceuticals
candles, polishes, lubricants,and as an additive tothermoplastic resins & food-related applications
Cosmetics, candles and lowvolume specialty applications
Insect & Animal Waxes
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Insect & Animal WaxesInsect/animal wax Beeswax Spermaceti Shellac wax Wool wax
Source end product of the metabolism of ahoneybee class (Apis mellifica, A.carnica), which belongs to the Apis genus secreted by bees and is used toconstruct the combs in which beesstore their honey
head oil & parts of theblubber of the spermwhale
resinous exudate of the scaleinsect Laccifer lacca (formerly Tachardia lacca) of the Coccidae family
Raw wool from sheep
Composition major components are esters of C30and C32 alcohols with C16 acids, freeC25 to C31 carboxylic acids, and C25 toC31 hydrocarbons
Largely cetyl palmitate Total acid: essentially of a mixtureof even-numbered fatty acids (C12–C18, 21– 26 % of the total acid) andwaxy acids (C28
– C34 , mainly C32and C34)
Alcohols: (C28 – C32) the C28component predominates (62– 65% of the total alcohol).Hydrocarbon: paraffins with 27, 29,and 31 carbon atoms.
ca. 48 % wax esters, 33 % sterol ester6 % free sterols, 3.5 % free acids, 6 lactones, and 1–2 % hydrocarbons
Important properties can have a yellow, orange, or darkbrown colormelting point of 64°C, a penetration
(hardness) of 20 dmm at 25°C and 76dmm at 43.3°C (ASTM D1321), aviscosity of 1470 mm2/s at 98.9°C, anacid number of 20, and asaponification number of 84moderately hard
Translucent, odorless, &tasteless
hard, yellow to brown Crude wool wax is a greasy, glubrown-yellow to brown-black substawith a penetrating goatlike odor (mp 3–
38 °C). Neutral wool wax is yellow tobrown in color (mp 38– 42 °C), with amilder odor, whereas Adeps lanae ipale yellow, almost odorless substan(mp 40–42 °C).
Uses & applications Cosmetics, pharmaceuticals, candleproduction
Base for ointments Surface coating leather polishes, cosmetics (e.g.baby-care products, and toilet soapharmaceuticals (e.g., plasterointments, and suppositories), alubricants; purified form known as lan
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Mineral WaxesMineral wax Montan wax Paraffin wax Microcrystalline wax Ozoc(or k)erite
Ceresin wax
Source/derivation solvent extraction of ligniteforms part of the extractable, bituminouscomponents of lignite and peat
From petroleum (macrocrystallinewax) obtained from light andmiddle lubricating oil cuts ofvacuum distillation; also includewaxes from heavy lubricating oildistillates
from the residual fraction of crudeoil distillation or from crude oil tankbottoms
Earth wax mined in Euro(Poland) but now apetroleum-derived paraffiwax
Composition a mixture of long-chain (C24-C30) esters(62-68 wt %), long-chain acids (22-26 wt%), and long-chain alcohols, ketones, andhydrocarbons (7-15 wt %)
composed of 40-90 wt % normalalkanes, with the remainder C18-C36 isoalkanes and cycloalkanes
a mixture of saturated hydrocarbonsthat are predominantly solid at roomtemperature, such asn- and isoalkanes, naphthenes, and alkyl- and naphthene-substituted aromatics
araffin wax of very narrowmolecular weightdistribution or blend opetroleum waxes
Important properties black-brown, hard, brittle product with aconchoidal fracture patternA melting point of 80°C, an acid number of32, and a saponification number of 92
insoluble in water and sparinglysoluble in low molar massaliphatic alcohols and ethersextremely unreactive undernormal conditions.
insoluble in water and most organicsolvents at room temperaturemore reactive than paraffin waxesbecause of the higher concentrationof complex branched hydrocarbonswith tertiary and quaternary carbonatomsHas a great affinity for oil
Insoluble in water
Uses & applications component in one-time hot-melt carbon-paper inks, polishes , plastic lubricantsBuilding industries, wood & metalprocessingCosmetics, pharmaceuticals, adhesives,resins & office equipment
Chewing gums, protectivecoatings for fruits, vegetables &cheesesFood & paper packagingRubber industries, lubricants ,adhesives, candles
Cosmetics & pharmaceuticals
Petroleum jelly, polishes, adhesives,cheese wax, chewing gum base,cosmetic preparations, sealing &cable compounds, plastics & paper,candles, casting and dentalcompounds, foam regulator,
explosives & propellants
Electrical insulationswaterproofing, &impregnating
S h i W
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Synthetic Waxes
Synthetic wax Polyethylene waxes Fischer-Tropsch waxes
Source /derivation made either by high pressure (free-radical)polymerization or low pressure (Zeigler-type catalysts)polymerization
Derived from liquefaction of coal via Fischer-Trsynthesis by polymerization of carbon monoxide high pressure and over special catalysts
Composition HP-PE wax: consist mainly of branched molecular chains inwhich shorter side chains, such as ethyl and butyl,predominate; generally have low densities (low-densitypolyethylene waxes, LDPE waxes)
essentiallyn-paraffins with chain lengths between 20 50 carbon atoms
Important properties For waxes, an upper limit to the melt viscosity of ca. 20000 mm2/s at 120 °C is defined, which corresponds to an
average molar mass (weight-average molar massM w ) of ca. 37 000 g/mol HP-PE wax: colorless, white to transparent and form clearmelts; dissolve in nonpolar solvents (e.g., aliphatic,aromatic, and chlorinated hydrocarbons) on heating andgenerally crystallize as very fine particles on cooling; formmobile dispersions or paste-like gels, which frequentlyexhibit thixotropic properties
have a fine crystalline structure and, because ofnarrow molar mass distribution, a small melting rang
very low melt viscositiesfully compatible with refined waxes, polyolefin waxmost vegetable waxessoluble at elevated temperature in the usual wax sol(e.g., naphtha, turpentine, and toluene) to give solutions
Uses & applications additives for inks and coatings, pigment dispersions,plastics, rubbers, polishes, cosmetics, toners, adhesives,and corrosion protection:Wash and wear finishes for textilesRelease agents in building industries, plastic processingand rubber industriesSurface finishing agents in paper productsProtective coating of citrus fruits
Used in plastics processing as lubricants for poly(chloride) and polystyrene, as well as mold-release agas melting point improvers, hardeners, and viscreducers in hot melts and candles ; and, because of good polishability, for the production of cleaning aand polishes; improve the abrasion resistance of pand printing inks
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RELEVANT CHEMICAL REACTIONS
WAXES
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POLETHYLENE WAXES PRODUCTION
Chemical Reactions in
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Free-Radical Polymerization(High-pressure Polymerization)
MECHANISMS:In initiating (start) reactions (Eq. 2), radicals R· formed from the decomposition (Eq. 1) of initiatomolecules I react with monomer molecules M. The resulting "monomer radicals" R– M· addfurther monomer molecules in the propagation reaction (Eq. 3) until the growing polymer radicalsR~~~M· are terminated by recombination (Eq. 4) or disproportionation (Eq. 5) with other polymerradicals or by addition of initiator radicals (Eq. 6) :• I 2 R· (1)• R· + M R – M· (2)• R – M· + M R – M – M·, etc. R – Mn– 1
– M· (3)• R – Mn– 1
– M· + ·M – Mm– 1– R R – Mn+m
– R (4)• R – Mn– 1
– M· + ·M – Mm– 1– R R – Mn
– 2 – M=M + X – Mm– R (5)
•
R – Mn– 1 – M· + R· R – Mn – R (6)
Where: X = an atom or a group that is transferred from the ultimate monomeric unit of one
polymer radical to another polymer radical
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Free-Radical Polymerization(High-pressure Polymerization)
• Termination of chain growth in PE waxes by reaction with a regulator moleculesuch as propene
R –CH2CH2 + CH2 = CH –CH3 R –CH=CH2 + CH3 –CH –CH3
• Termination of polymerization in PE waxes by recombination or disproportionationof two macroradicals
• Long-chain branching occurs by intermolecular chain-transfer reactions
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Free-Radical Polymerization(High-pressure Polymerization)
• UNIQUE FEATURE:increased formation of short ethyl and butyl side chains thatare formed by intramolecular radical transfer
Side reaction: Depolymerization of chain radicals at high reactiontemperature
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High-pressure Polymerization ProcessDescription
• Monomer: ethylene is in a supercritical state• Polymerization takes place in a one-phase system.• The wax remains as a melt and the unreacted ethylene vapor is recycled.• Reaction pressure:
Homo- & copolymerization – usually 150 – 320 MPa; 70 MPa (max.) withisopropanol as the molar mass regulator
• Reactors: autoclaves & tubular reactors• Reaction temperature:
Homopoymerization - 200 – 350 °CCopolymerization - 200 – 300 °C
• Initiators: Organic peroxides and molecular oxygen (the latter exclusively
in tubular reactors)• Molar mass regulators: Hydrogen, lower alkanes (e.g., propane), lower
alkenes (e.g., propene or butene), alkyl aromatics, lower aldehydes (e.g.,propionaldehyde), and lower alcohols (e.g., isopropanol) or mixtures of these substances are mainly employed.
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Ziegler-Natta Polymerization for PEWaxes
• Same chemistry as in polymerization of polyolefins
• Modified catalysts: – Supported catalysts, which contain titanium atoms
as the active species and magnesium compoundsas the carrier material
– Catalysts derived from titanium tetrachloride andmagnesium chloride, oxide, hydroxide, or alkoxide
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FISCHER-TROPSCH WAXESPRODUCTION
Chemical Reactions in
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Fischer-Tropsch Synthesis Mechanisms
• Reaction scheme 1
Carbon monoxide dissociates at thecatalyst surface (M) to carbon andoxygen atoms. Chemisorbed hydrogenreacts with the carbon to form CHxentities, which combine into hydrocarbonchains. Chain termination produces a-olefins or alkanes. To account for theformation of oxygen compounds, aparallel mechanism postulates their production on oxide components of thecatalyst surface.
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Fischer-Tropsch Synthesis Mechanisms
• Reaction scheme 2
Carbon monoxide does notdissociate, but is hydrogenated toform oxymethylene species, whichcondense on the catalyst surface topropagate the hydrocarbon chain.
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Fischer-Tropsch Synthesis Mechanisms
• Reaction scheme 3
Carbon monoxide CO moleculedoes not dissociate, but insertsin an M – H or an M – C bond .This is observed inhomogeneous catalysts.
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Fischer-Tropsch Process Description
• Catalysts: – iron-based catalysts promoted with potassium and copper (SASOL) – alkali-promoted catalyst prepared by sodium carbonate precipitation of a
solution of iron and copper nitrate ARGE (Arbeitsgemeinschaft) – fused-iron catalyst(Synthol)
• Catalyst lifetime: ca. 6 months• Reaction temperature:
– 220 °C - 225°C (ARGE) – 320 – 340 o C (Synthol)
• Reaction pressure: – 2.5 MPa (ARGE) – 2.3 MPa (Synthol)
• H2 : CO feed ratio: 1.7 (ARGE) and 2.54 (Synthol)• CO + H2 conversion, %: 60-66 (ARGE) and 85 (Synthol)• Extremely exothermic