1. Metallocene based Polymerization
Catalysts

2. Metallocenes Key aspects Why metallocenes ?
Metallocenes - Structure & Features
Methyl Aluminoxane (MAO) – Structure & Features
Activation of Metallocenes by MAO
Polymerization with Metallocenes

3. Why Metallocenes ?
Need for homogeneous catalyst system- Well-defined structure-activity correlations
Metallocenes- Well known organometallics- Can function as Single site catalyst
Tunable structure- rings, substituents, ligands
High degree of stereoregulation –Isotactic / Syndiotactic
High productivity
Narrow molecular weight distribution
Better co-monomer distribution
Chain termination by β- Hydrogen elimination→ Vinyl end group→ Facile grafting of functional monomers
Pathway to designer catalysts

4. PE- Molecular weight distribution - Effect of metallocene

5. PE- Density Vs Co-monomer content :
Effect of metallocene

9. Metallocene-The race for supremacy

10. Organometallics- Vital components in polymerization catalysts
Polymerization- Controlled making & breaking metal-alkyl bonds

11. Polyolefins catalysts- Phenomenal growth

12. Propylene polymerization cycle on metallocene catalyst

13. Ferrocene Discovered in 1951 by reaction between
Cyclopentadienyl Magnesium bromide & FeCl3
With 6 lectrons from each ring & six fron Fe,
a totall of 18 electrons ensures stable noble
gas configuration
Bond distance between sandwiched Fe & CPD
rings is 2.04Å
Nickelocene,Cobaltocene & Titanocene were
synthesized later

14. Metallocenes- Structural features
Orientation of CPD rings
Zr may be replaced with Ti,Hf &
CPD with Indenyl / Fluorenyl rings
with or without substituents
Ethylene bridge holds both rings rigid
retarding swiveling – helps in proper
approach of monomer to metal centre
Ethylene Bis-Indenyl Zirconocene

15. Search for homogeneous Z-N catalysts
Bis (cyclopentadienyl) Ti4+
Tetrabenzyl Titanium
Tetraallyl Zr & Hf
Low PE yields +
AlClEt2
Al alkyls are not effective as co-catalysts for metallocenes
Methyl aluminoxane was discovered by Kaminski in
as the most effective co- catalyst for metallocenes

16. Methyl Aluminoxane - MAO- Co-catalyst for Metallocenes
MAO- Formed by controlled hydrolysis of Al(CH3)3
with water, with evolution of methane
Mixed oligomers with Mol.mass – g/mol
Gen formula Me2-Al-O[AlMeO]n-OAlMe2- n= 5-20
Highly reactive, stored & transported as solution
in toulene
Structures in solution

17. Activation of Metallocene by MAO
Substitution of Cls with methyl groups followed by ion-pair formation &
creation of a vacant site

24. 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