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

Chemical Industry- Products pattern

Polymers constitute 20 % of Mega Chemical Industry

Polymers -Types

POLYMERS

BIO-POLYMERSProteins, Nucleic

acid

NATURAL POLYMERS

Rubber, Starch,Cellulose

SYNTHETIC POLYMERSPolyethyleneNylon,PVC

Elastomers &Plastics

Thermosets &Thermoplastics

Single Polymer chains as seen by AFM

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

Addition Polymers-Types

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

Block

Random

Graft

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

Polymers-The journey

Monomer

Type of polymerization

Type of process/reactor

Reaction conditions

Type of catalyst

Polymer resin Processing

End Product

Type of Processing, Processing aids,Machinery

Co-monomer(s)

Co-catalystsDonors etc.

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 - 45 Mill.MT; Value- $65 Billn. (2007) PE - 65 Mill.MT (2008)

monomer

initiation

Ethylene (C2H4) forms polyethylene (PE)in the presence of free radical R• (catalyst or initiator)

propagation

Free radical ploymerization- Ethylene

Ploy ethylene – Types Vs Properties

PE MW Density Tensile strength Branching Mill. g/cc MPaHDPE 0.2-0.5 > 0.941 43 LowLDPE 0.1 0.91-0.940 24 Med & ShortLLDPE 0.1 0.91-0.925 37 Short

Co-monomers for LLDPE → 1-Butene/1-Hexene/1-Octene

PE by free radical route

• Extensive branching

• Long and short branches

• Lower crystallinity 30-60%

• Density 0.91-0.925

• Vary P, T during synthesis

UHMWPE – MW- 3-6 Million

Surface structure of Chromium based PE catalysts

1.CrO3/ Silica- Phillips

2.Chromocene/Silica- Union Carbide

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

Z-N- Polymerization of ethylene

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

Processes for Polyethylene

Processes for PE production

High Pressure

Autoclave

Tubular

Low Pressure

Slurry phase

Gas phase

Solution phase

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

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

Z-N Polymerization-Stereochemistry

PP Stereochemistry- Effect of metal & ligand

PP- Streochemistry Vs Properties

PP Elastic Hardness MP Mech.props

Modulus-Gpa Mpa ° C

Isotactic 1.09 125 160-170 Stiff/Brittle

Syndiotactic 125-131 Robust, transparent

Atactic 0.15 1.4 < 0

Polymerization of propylene- Reaction scheme

Polymerization of propylene- Steps

1. Replacement of one Cl by alkyl group of Al alkyl

2. Bonding of Propylene to a vacant site

3. Insertion of propylene into Metal-alkyl bond- Initiation

4. Creation of vacant site for propylene adsorption

5. Repetition of steps 2,3 & 4 leading to chain growth/propagation

6. Catalyst configuration decides the configuration of added propylene

7. Termination of polymer chain with hydrogen- Termination

Streochemistry of active site

TiCl

Cl

Cl CH3

P

Cl

4 Bridging Cl1Terminal Cl replaced by alkyl 1 Vacant site for propylene adsorption

--------

----

-----------

-----------

--------

---

----------

C

C

CH3

HH

124.3°

1.336Å

1.501ÅH

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

M P +

1

3

2

1

2P

3

M

M

3 1

P2

M

3

12

P

1,2 Insertion

2,1 Insertion

3,1 Insertion

Possible insertion modes for Propylene across Metal-Alkyl bond- Different orientations of methyl group

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 -96-99%

Fourth• Morphology controlled catalysts• Spherical polymer product-No extrusion

High activity catalyst → Elimination of catalyst removal deashing & extrusion

Vessel A Vessel B

Diameter = 4.0mLength = 20.0 m

Diameter = 4.0m   Length = 20.0 m

Material of Construction = Carbon Steel

Material of Construction = Carbon Steel

Design Pressure = 1 atm

Design Pressure = 400 atm

Installed Cost = $228,700

Installed Cost = $1,840,000