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ZIEGLER-NATTA CATALYST

PRESENTED BY:

LISAMONI KALITA

M.SC 2ND SEM

ID: BS14MC0229

DEPT. OF CHEMISTRY

ASSAM KAZIRANGA UNIVERSITY

2Table of Contents

Introduction

Brief History of Ziegler Natta Catalyst

Mechanism of Ziegler Natta Polymerization

Importance of Ziegler Natta Catalyst

Applications of Ziegler Natta Catalyst

Conclusion

Reference

3Introduction

Karl Ziegler in 1953 polymerized ethylene catalytically to polyethylene. Giulio Natta utilized Ziegler's catalyst to produce polypropylene in 1954. In 1963, both Karl Ziegler and Giulio Natta were awarded the Nobel Prize for their discoveries.

In 1973 the 2nd generation Ziegler-Natta catalysts were introduced with β-TiCl3 at lower

temperatures.

In 1980 3rd generation catalysts supported on MgCl2 were commercialized by many

companies. In 1991 4th generation Ziegler-Natta catalysts based on aluminoxane activated metallocene

complexes were used. Two broad classes:

Heterogeneous Catalyst: Based on Ti compounds Homogeneous Catalyst: Based on complexes of Ti, Zr and Hf

4Ziegler’s Discovery (Germany,1953)

Co-catalyst catalyst

Karl Ziegler-the last Al-Chemist “...because he turned aluminium into gold.”

TiCl4 1 atm20-70 C

Al(Et)3 + CH2CH2"linear"

Mw = 10,000 - 20,00,000

5Natta’s Discovery (Italy,1954)

isotactic

syndiotactic

CH3

VCl4Al(iBu)2Cl

- 78 CCH3CH3 CH3

CH3CH3 CH3

CH3TiCl3

Al(Et)2Cl

6Mechanism of Ziegler-Natta Polymerization: The Cossee Mechanism

Ti CH2CH3

Ti CH2CH3

CH2H2C

Ti

CH2

Polymer

Catalyst acceptsethylene as a ligand

1,2- Migratory insertion [Ethyl migration]

Ti CH2CH3

H2C CH2

ligandassociation

Ti CH2CH2

CH2H2C

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Termination Step: Chain Transfer

Ti

CH2

Polymer

Ti HTi

CH2CH3

Ti H

H2PolymerH+

8Kaminsky Catalyst System

M = Ti, Zr, Hf

Linear

Atactic polypropylene

M

X

X

+ Al O

CH3

n

M

X

X

+ Al O

CH3

n

CH3

MAO

MAO

MAO=methylaluminoxane

Homogeneous Ziegler Natta Catalyst

9Brintzinger System

Brintzinger developed these catalysts which when activated with MAO catalysed the stereoselective polymerizations of propylene with very high activities. Thus for the first time isotactic polyolefins were obtained using homogeneous Ziegler-Natta catalyst

Si

R

R

MX

X

ansa-metallocene

R= CH3, C2H5

X= Cl, Br, CH3

M= Ti, Zr

10Importance of Ziegler Natta Catalyst High Selectivity

High Efficiency

High Stereoregularity (99% tacticity)

Longer Lifetime

High concentration of polymer product

Lower cost in production

Easy regeneration of catalyst

Controls growth and formation of polymer product

Control of polymer particle morphology in spherical shape

Higher stability

11Example:

Propene can polymerize in three ways:

TiCl4 + Al(C2H5)3

CH3

Highly selective towards isotactic productHighly stable product

CH3CH3 CH3 CH3 CH3 CH3CH3 CH3 CH3 CH3

CH3CH3 CH3 CH3 CH3

CH3CH3 CH3 CH3 CH3

Atactic Isotactic Syndiotactic

MgCl2

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Applications of Ziegler-Natta CatalystProduction of:

High density polyethylene (HDPE)

Linear low density polyethylene (LDPE)

Ultra-high molecular weight polyethylene (UHMWPE)

Thermoplastic polyolefins (TPO’s)

Polybutylene (PB)

Shiny lustrous polyacetylene film which have semiconducting properties

Crystalline polypropylene

Carbon nanotubes nanocomposites

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14Conclusion

Ziegler Natta are mainly used to polymerize 1-alkenes.

Ziegler Natta catalyst is composed of a catalyst and co-catalyst.

Ziegler-Natta catalysts can be categorized into heterogeneous and homogenous by their form in catalysis process. The heterogeneous one is widely used in industry.

Only Ziegler-Natta catalysts can produce highly stereoregular and linear unbranched polyolefins.

15References Pokasermsong P. and Praserthdam P.; Comparison of Activity Of Ziegler-Natta

Catalysts; Engineering Journal; Vol. 13; 2009; 57

Ahmad A.; Propylene Polymerization Using 4th Generation Ziegler-Natta Catalysts:

Polymerization Kinetics and Polymer Microstructural Investigation; A thesis

presented to the University of Waterloo; 2011

Cerruti L.; Historical and Philosophical Remarks on Ziegler-Natta Catalysts; HYLE –

An International Journal for the Philosophy of Chemistry; Vol. 5; 1999; 3.

Bajgur C. S. and Sivaram S.; The evolution of new generation ‘single-site’ Ziegler–

Natta polymerization catalysts; Current Science; Vol. 78; 2000; 1325

Busico V., Cipullo R., Pellecchia R., Ronca S., Roviello G., and Talarico G.; Design of

stereoselective Ziegler–Natta propene polymerization catalysts; PNAS; vol. 103;

2006; 15321

16References Contd. Lewin M.; Handbook of Fiber Chemistry; CRC Press; Third Edition; ISBN 1420015273

Gross E., Liu J. H, Toste F. D. and Somorjai G. A.; Control of selectivity in heterogeneous

catalysis by tuning nanoparticle properties and reactor residence time; Nature

Chemistry ; Vol. 4; 2012; 947

Clayden J., Greeves N. and Warren S.; Organic Chemistry; Oxford; Second Edition; ISBN

978-0-19-927029-3

Gupta B. D., Elias A. J.; Basic Organometallic Chemistry Concepts, Syntheses and

Applications; University Press; Second Edition; ISBN 978-81-7371-874-8

Ramakrishnan S; Conducting Polymers; RESONANCE ; Vol.2; 2011; 48

http://en.wikipedia.org/wiki/Ziegler%E2%93Natta_catalyst

http://www.chemheritage.org/discover/online-resources/chemistry-in-history/themes/

petrochemistry-and-synthetic-polymers/ziegler-and-natta.aspx

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