Homogeneous Catalysis HMC-6- 2010 Dr. K.R.Krishnamurthy National Centre for Catalysis Research Indian Institute of Technology,Madras Chennai-600036 1

DIMERIZATION & OILGOMERIZATION

Homogeneous Catalysis- Major Industrial Processes Processes/Products Terephthalic acid & Poly(Ethylene Terephthalate) Acetic acid & acetyl chemicals Aldehydes and alcohols- Hydroformylation Adiponitrile- Hydrocyanation Detergent-range alkenes- SHOP- Oligomerization Alpha Olefins (C4- C20)- Dimerization & Oligomerization Total fine chemicals manufacture Olefins Polymerization (60% uses Ziegler-Natta) 9 ( 7 6 1 4 < 1 60 Production, MTA Oligomerization & Dimerization – Key homogeneous processes

Dimerization & Oligomerization Processes Dimerization of ethylene to Butene-1- Co-monomer in LLDPE- IFP & SABIC processes Dimerization of propylene- Methyl pentenes & Hexenes- Gasoline additives- DIMERSOL- IFP Sumitomo & BP processes Dimerization of Butadiene- 1,5 Cyclo-octadiene-Cyclooctene- (ROP)- Vestenamer-Hulls process Trimerization of Butadiene-Cyclododecatriene- (ROP)- Vestamid-Hulls process Butadiene+ Ethylene co-polymerization-EPDM rubber- DuPont-Process Oligomerization of ethylene to Linear Alpha Olefins- LAO - Chevron-Phillips,(Gulf Oil)-GULFTENE, Ineos (Ethyl), Idemitsu, Conaco, Shell (SHOP), SABIC (-SABLIN) Basis for the production of wide range of useful olefins & monomers

Dimerization of Propylene & Butadiene, Trimerization of Butadiene & Co-polymerization of Butadiene & ethylene to yield EPDM rubber

Conversions with butadiene

Alpha Olefins-Applications C4 to C6        Poly butenes, Co-monomers in polyethylene (4-12%) C6 to C10      Plasticizer alcohols C8 to C10    Trimers, as Synthetic lubricants- C10 to C14    Detergents - Linear Alkyl Benzene (LAB) Alpha Olefin Sulphonates (LAO,AOS) C16 to C18     Lube oils, Surfactants C20 to C30+  Oil field Chemicals, Wax replacements

Alpha Olefins -Processes Thermal cracking of wax Paraffins dehydrogenation Alcohol dehydration Ethylene oligomerization F-T synthesis

Alpha Olefins via Ziegler Process Alfen Process Two steps 100ºC,10 MPa pressure ethylene 300ºC,1 MPa Gulf/Chevron & Ethyl Processes

Gulf/Chevron Process Ethyl Process Idemitsu One step process, with chain growth & elimination occur simultaneously Solvent—Heptane, 200ºC, 25 MPa ethylene pressure 0.4 % Al Et3 is used as catalyst Schulz-Flory distribution of alpha olefins- Broad distribution of carbon No Ethyl Process Oligomerization at 160-275ºC, 13-27 MPa pressure Separation into, C4-C10 & C12 –C18 Higher Al alkyls produced at 100ºC & 20 MPa Transalkylation of C4-C10 olefins with higher alkyls at 300º C & 10 Mpa to get higher olefins Idemitsu Zr based catalyst

Processes for  - Olefins - Comparison of product quality Processes → Products↓ Wax Cracking Chevron Ethyl SHOP -Olefins 83-89 91-97 63-98 96-98 Branched olefins 3-12 2-8 2-29 1-3 Paraffins 1-2 1.4 0.1-0.8 0.1 Dienes 3-6 - Mono olefins 92-95 99 >99 99.9

Shell Higher Olefins Process (SHOP) Involves four processes Oligomerization of ethylene to C4-C20+ α- olefins 80 to 120 °C and 70 to 140 bar (7 to 14 MPa) with a nickel phsophine complex (C6H5)2P(CH2)2COONi- Homogeneous Isomerization of α-olefins to internal olefins- Heterogeneous Metathesis of C20+olefins with C4-C8 olefins- Heterogeneous Isomerization, hydroformylation & hydrogenation to α-alcohols- Homogeneous Reaction carried out in polar solvents (1.4 Butane diol) in which α-olefins are insoluble Bi-phasic liquid-liquid reaction with Ni concn.0.001-0.005 mole%, at 80-140ºC, 7-14 Mpa Exothermic heat removed by exchangers

Shell’s SHOP Process-Stepwise conversions Step. 1- Oligomerization H2C=CH2 -----------→ H (CH2-CH2)n-CH=CH2 n= 1 to 19 Ni complex Step.2- Fractionation of alpha-olefins C4-C10 - Olefins C10-C14 - Olefins C16-C40 - Olefins Step.3 – Hydroformylation of C10-C14 Olefins C10-C14 Olefins ------------→C11-C15 alcohols H2+CO CH3(CH2)7-CH=CH2-------------→CH3(CH2)7-CH2- CH2 –CHO Co(Co)4 ↓ H2 CH3(CH2)7-CH2- CH2 –CH2- OH

Shell’s SHOP Process-Stepwise Conversions Step.4 – Isomerization Catalyst Na/K on Al2O3 or MgO C4-C10 - Olefins ------------→ C4-C10 Internal olefins C16 –C40 - Olefins ------------→ C16 –C40 Internal olefins CH3-CH2-CH=CH2 ------------→ CH3-CH=CH-CH3 CH3 (CH2)17 -CH=CH2-------------→ CH3-(CH2)8-CH=CH-(CH2)8-CH3 Step.5- Metathesis of C4-C10and C16-C40 internal olefins Catalyst Mo/W/Re on Al2O3 CH3-CH=CH-CH3 + CH3-(CH2)8-CH=CH-(CH2)8-CH3 (i-C4) ↓ (iC20) 2 CH3-CH=CH –(CH2)8-CH3 Step.6 – Fractionation of internal olefins C10-C14 Internal Olefins C4-C10 Internal Olefins C16-C40 Internal Olefins Separation of C10-C14 olefins & Hydroformylation to alcohols

Shell’s SHOP Process- Stepwise conversions Step.7 – Hydroformylation of C10-C14 Olefins C10-C14 Olefins ------------→C11-C15 alcohols H2+CO CH3(CH2)7-CH=CH2-------------→CH3(CH2)7-CH2- CH2 –CHO Co(Co)6 ↓ H2 CH3(CH2)7-CH2- CH2 –CH2- OH Step.8 – Repeat of steps 5,6 & 7 to exhaustion

SHOP Process- Isomerization & Metathesis

Shell’s SHOP Process- Block flow diagram

SHOP Process Scheme & Catalyst

Flow scheme of Shell’s SHOP Process

Ethylene Oligomerization- Ni Complex catalyst

Oligomerization-Addition of ethylene Initiation- Formation of Ni hydride- active centre for ethylene co-ordination Model compound

SHOP Process- Chain growth & Termination Process parameters /control the temperature; note that the reaction is highly exothermic, • ethene concentration • but-1-ene concentration • composition of the medium • catalyst activity • process operation; e.g. mixing, settling of the two phases, pressure release, cooling. Ethylene pressure to be maintained high so as to promote chain growth and avoid insertion of butene, which ends up in branched products The catalyst odes not display any isomerization activity

SHOP Process- Chain growth & Termination Growth factor –γ – Concn. of each alkene is a certain fraction of the preceding alkene Product distribution determined by rate of growth kg and rate of termination, kt Rate constants are the same for all intermediate Ni alkyls, except for the first 2 or 3 members

SHOP Process- Chain growth Schultz Flory distribution Vs Growth factor K K= n(Cn+2 /n(Cn) . K adjusted at 0.75- 0.80

SHOP Process- Product distribution

A,B,C &D four different pathways A,B &C- Chain termination Pathways D- Chain propagation pathway

Metathesis Bimolecular process involving exchange /redistribution of bonds in the reactants Yves Chauvin, Richard R. Schrock & R.H Grubbs, awarded Nobel prize in 2005 for pioneering work on metathesis Metathesis – Grubbs illustration as Dancing partners- Exchanging of partners AX +BY → BX +AY Olefin metathesis- Exchange of double bonds Alkane metathesis- Higher alkane to shorter and longer alkane Alkyne metathesis- Redistribution of triple bonds Intra-molecular metathesis of 4 -methyl 1,7 Octadiene

Olefin Metathesis- Mechanism

Olefin metathesis-Process steps Formation of metal alkylidene complexes Step.2 Formation of metallocyclobutanes Step.3 Opening of metallocyclobutane to form products Majority of metathesis reactions involve heterogeneous catalysis, Mo/W/Re supported on alumina Homogeneous systems are also known

Alkene Metathesis-General cycle

Different types of Olefin metathesis reactions

Topics for assignment –September 2012 Heterogenized homogeneous catalysts Applications of ionic liquids in homogeneous catalysis Challenges in catalytic processes for manufacture of pharmaceuticals Developments in olefins epoxidation processes in homogeneous phase Heterogeneous catalytic routes for oxidation of p-Xylene to PTA Continuous homogeneous catalytic processes

Assignments in Homogeneous catalysis Green processes for conversion of cyclohexane to adipic acid P- Xylene oxidation without Bromide as the initiator Alternative routes for methyl methacrylate production Homogeneous process for epoxidation of ethylene Alternative processes for propylene oxide