1. Chemical Industry-The Fact Sheet
70000 products
10 Million direct employees
50 Million indirect employees
Wide range of products/processes
/ feed-stocks
Enabling better quality of life
Annual growth rate 2.4 %
Global enterprise valued at $2.2 Trillion …… and growing

2. Chemical Industry- Products pattern
Polymers constitute 20 % of Mega Chemical Industry

3. Polymers -Types
Single Polymer chains as seen by AFM

4. Polymerization-Types
Mode of formation
Addition Polymerization - Polyethylene, Polypropylene
Condensation Polymerization - PET, Nylon 66
Mechanism of formation
Free radical - LDPE, PVC
Co-ordination - PP,PBR
Ionic - Cationic, Anionic- Poly acrylonitrile

5. Addition Polymers-Types

6. Block
Random
ABS- Acrylonitrile-Butadiene-Styrene co-polymer
PAN-Strong fibre character
PBR- Rubber-Elasticity-shock absorber
PS - Tough & hard
The co-polymer has very high strength & toughness
Graft

7. Polymers- Finger prints
Catalyst & Process controlled Reflected in
Regioselectivity Melting point
Cis/Trans Isomerism Crystallization temp.
Stereoselectivity Glass Transition temp.
Mol. Wt distributuion Modulus
Polydispersity Crystallinity
Viscosity
Morpohology
Hardness
Stiffness
Transparency
Catalysts & process dictate the property of polymer

8. Polymers-The journey End Product Monomer Co-monomer(s)
Type of polymerization
Co-catalysts
Donors etc.
Type of catalyst
Type of process/reactor
Type of Processing, Processing aids,
Machinery
Reaction conditions
Polymer resin
Processing
End Product

9. Ziegler & Natta awarded Nobel prize in 1963
History of PE & PP
(1933)
(1955)
Propylene polymerization on similar catalysts by Natta (1956)
- 3 generations of catalysts
Silica supported chromia catalyst for ethylene polymerization
Banks & Hogan- Phillips (1958)- Low pressure/Temp process
Metallocene catalysts- Kaminsky (1989)
Post metallocene catalysts
Ziegler & Natta awarded Nobel prize in 1963
Global consumption- PP Mill.MT; Value- $65 Billn. (2007)
PE Mill.MT (2008)

10. Free radical ploymerization- Ethylene
Ethylene (C2H4) forms polyethylene (PE)
in the presence of free radical R• (catalyst or initiator)
monomer
initiation
propagation

11. Ploy ethylene – Types Vs Properties
PE by free radical route
Extensive branching
Long and short branches
Lower crystallinity %
Density
Vary P, T during synthesis
PE MW Density Tensile strength Branching
Mill g/cc MPa
HDPE > Low
LDPE Med & Short
LLDPE Short
UHMWPE – MW- 3-6 Million
Co-monomers for LLDPE → 1-Butene/1-Hexene/1-Octene

12. Surface structure of Chromium based PE catalysts
1.CrO3/ Silica- Phillips
Choice of silica (~300 m2/g), Cr loading (1%), promoters & pretreatment
(calcination, pre-reduction) of the catalysts are crucial
30-40 % of PE is produced by Phillips process
2.Chromocene/Silica- Union Carbide

13. Z-N- Polymerization of ethylene

14. Catalytic cycle for polymerization of ethylene - Cossee-Arlman mechanism
- Direct insertion of olefin across M-alkyl bond

15. Processes for Polyethylene

16. Processes for PE production
High Pressure
Autoclave
Tubular
Low Pressure
Slurry phase
Gas phase
Solution phase

17. Conventional Ziegler-Natta Catalyst
Catalyst components TiCl4 & AlEt3
Organo aluminium compound reduces TiCl4 to generate TiCl3
Active phase TiCl3
Different crystalline forms- α , β, γ , & δ
β Chain structure; α , γ , & δ have layer structure
Activity & Isotacticity differs
α – Hexagonal Close packed – hcp of Cl ions
γ - Cubic close packed –ccp of Cl ions
Ti ions occupy Octahedral holes of Cl- matrix

18. Stereochemistry of PP- a) Three different orientation of methyl groups in PP
backbone b) Stereo chemical relationship between two adjacent methyl groups

19. Z-N Polymerization-Stereochemistry

20. PP Stereochemistry- Effect of metal & ligand

21. PP- Streochemistry Vs Properties
PP Elastic Hardness MP Mech.props
Modulus-Gpa Mpa ° C
Isotactic Stiff/Brittle
Syndiotactic Robust, transparent
Atactic < 0

22. Polymerization of propylene- Reaction scheme

23. Polymerization of propylene- Steps
Replacement of one Cl by alkyl group of Al alkyl
Bonding of Propylene to a vacant site
Insertion of propylene into Metal-alkyl bond- Initiation
Creation of vacant site for propylene adsorption
Repetition of steps 2,3 & 4 leading to chain growth/propagation
Catalyst configuration decides the configuration of added propylene
Termination of polymer chain with hydrogen- Termination

24. Streochemistry of active siteP Cl
CH3 Cl Ti Cl
1.501Å
CH3 H C 
124.3° Cl
1.336Å
4 Bridging Cl
1Terminal Cl replaced by alkyl
1 Vacant site for propylene adsorption C H H

25. Polypropylene- Stereoregulation
Methyl group of the incoming propylene prefers a trans position vis-à-vis
the polymer chain-p – Right ; cis orientation as shown on left is not favoured

26. Possible insertion modes for Propylene across Metal-Alkyl bond- Different orientations of methyl group 1 2 3 P M
1,2 Insertion 2 M
P + 3 1 3
2,1 Insertion P 2 M 1 1 3 M 2 P
3,1 Insertion

27. Z-N catalysts- Generations catalyst
First
TiCl3 and AlEt2Cl
Second
TiCl3 + AlEt2Cl + Mono/Di ethers, Mono/Di esters
Third
TiCl4 supported on MgCl2 + Al-Alkyl + Phthalate esters -3rd component
MgCl2 has layered structure; Ionic radii of Mg2+ & Ti3+ similar
Structural compatibility
Polymer yield > 30 Kg/g ; Isotacticity index %
Fourth
Morphology controlled catalysts
Spherical polymer product-No extrusion
High activity catalyst → Elimination of catalyst removal deashing & extrusion

30. Vessel A
Vessel B
Diameter = 4.0m
Length = 20.0 m
Diameter = 4.0m  
Material of Construction = Carbon Steel
Design Pressure = 1 atm
Design Pressure = 400 atm
Installed Cost = $228,700
Installed Cost = $1,840,000