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 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

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

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 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

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

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

Ploy ethylene – Types Vs Properties 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 PE MW Density Tensile strength Branching Mill. g/cc MPa HDPE 0.2-0.5 > 0.941 43 Low LDPE 0.1 0.91-0.940 24 Med & Short LLDPE 0.1 0.91-0.925 37 Short UHMWPE – MW- 3-6 Million Co-monomers for LLDPE → 1-Butene/1-Hexene/1-Octene

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

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 PP backbone 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 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

Streochemistry of active site P ----------- 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

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

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

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 = 4.0m 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