»

ACS Spring Meeting, New Orleans, 8 April 2008

Thomas E. Müller CAT Catalytic CenterRWTH AachenGermany

CO2 Fixation in Polymers

» Agenda

Current options concerning CO2 » Trend in CO2 Emission» CCS Technologies» Substitution potential

CO2 as C1 building block» Activation of CO2» Energy balance

Synthesis of building blocks for polymers» Reduction of CO2» Cyclic carbonates» Acrylic acid

Direct synthesis of polymers» Polycarbonates

Conclusions and outlook

» Current trend in CO2 emissions

Current status» Global CO2 emissions 28 192 Mio t/a (2005)» Tendency increasing» Correlation with global warming appears likely

Possible measures for reduction» Avoid CO2 production (regenerative energies)» Development and introduction of CCS technologies» Use of CO2 as building block in chemical industry

0

5.000

10.000

15.000

20.000

25.000

30.000

1980 1990 2000 2010

YearC

O 2 E

mis

sion

/ M

io t/

ahttp://www.eia.doe.gov/iea/carbon.html

http://www.cutco2.org/

» CCS Technologies (Carbon capture and storage)

Industrial uses

Mineral carbonation

Geological storage

Ocean storage

» Substitution potential for CO2 in chemical industry

Pharmaceutics (Aspirin)Solvent

Fertilizer, melamine, Formaldehyde, acetic acid

Food industry, cleaning, extraction, inert gas

Use

2000178Substitution potential0.070.0812730

Mio t/a

(2005)0.03Salicylic acid(2005)0.04Cyclic carbonates200472Urea20053Methanol2005~80Raw material

200220Industrial gas

200528 192CO2 Emissions Anthropogeneous

YearMio tCO2/a

C&EN June 26 (2000) 48

BTXGasoline Lightalkenes

MethanolAmmonia

Prod

uctio

n (m

illio

n t/a

)

230 Mio t/a (2005)Shift to oxidized

materials required

PPPELD PEHD PVC PS PA PC PET PUR

10

0

20

30

40

60 in Mio t/a

» Sources of clean CO2

Amine based adsorption» Monoethanolamine» Methyldiethanolamine

CO2 rich stream

CO2 poor stream

» Properties of CO2

Colorless and tasteless gasNon-toxic Low supercritical pointUnique properties as solvent

Pre

ssur

e p

Temperature T

solid

gaseous

liquid

Tc = 31.0 °Cpc = 73.75 bar

Critical point

supersuper--criticalcritical

GasViscosity

Mass transfer

LiquidSolvent

Heat capacity

scCompressibility

Adjustable

Courtesy of Prof. Leitner

» Activation of CO2

T. Sakakura et al. Chem. Rev. 107 (2007) 2365

J. E. Gready et al, JACS 123 (2001) 10821

Ribulose bisphosphate carboxylase (RubisCo)• One of the most abundant enzymes on this planet.• This enzyme takes solar energy. • Converts carbon dioxide into carbohydrate.

Lewis base

π-Complexes

Lewis acid

Reactive positions

MgO

MgO

M. Chiesa, E. GiamelloChem. Eur. J. 13 (2007) 1261

Oxidative cycloaddition

Reaction with nucleophiles

» Reversible coordination of CO2

H. Xu, E. M. Hampe, D. M. Rudkevich, Chem. Commun. (2003) 2828

» Energy balance of CO2 conversion

Sakakura et al. Chem. Rev. 107 (2007) 2365

CO2 is the energetic end product of combustion

»Use high-energy starting materials, such as H2, alkenes, strained rings, organometallics

Note: Reduction requires more energy than released by combustion of the products so produced

»Choose oxidized low-energy synthetic targets

»Shift equilibrium to products

»Supply physical energy, such as light or electricity

Konuma, React. Func. Polym. 67 (2007) 1129

» Typical transformations of CO2

T. Sakakura et al. Chem. Rev. 107 (2007) 2365

€

€

€€

€

€

» Synthesis gas

Dry reforming of methane

Base chemical for synthesis of»Olefines»Paraffins»Methanol»Dimethylcarbonate

CH4 + CO2 2 CO + 2 H2 ΔH0298= +247 kJ/mol

endothermal

» Hydrogenation

Methanol (20 Mio t/a in 2000)

Formic acid (0.4 Mio t/a in 2000)

CO + 2 H2 CH3OH ΔH0298= -90,8 kJ/mol

CO2 + 3 H2 CH3OH + H2O ΔH0298= -49,6 kJ/mol

CO + H2O CO2 + H2 ΔH0298= -41 kJ/mol

CO + CH3OH HC(O)OMe HC(O)OH + CH3OH

CO2 + H2 HCO2H ΔH0298= -31.6 kJ/mol

NaOMe H+

Source of H2 ?

» Hydrogenation

Methanol (20 Mio t/a in 2000)CO + 2 H2 CH3OH ΔH0

298= -90,8 kJ/mol

CO2 + 3 H2 CH3OH + H2O ΔH0298= -49,6 kJ/mol

CO + H2O CO2 + H2 ΔH0298= -41 kJ/mol

Source of H2 ?

I. Chorkendorff, J. W. Niemantsverdriet, Concepts of Modern Catalysis and Kinetics, Wiley-VCH, 2003

Commercial catalyst Cu/ZnO/Al2O3

H2 H2 : H2O = 1 : 3 H2 : CO = 95 : 5

» Methanol synthesis

formate

Cu

Cu

Cu

Cu

CO2

OC

O

H

O

CO

H2

H2

H HH2

H

H3C

O H

CH3OH

O H H

methoxy

I. Chorkendorff, J. W. Niemantsverdriet, Concepts of Modern Catalysis and Kinetics, Wiley-VCH, 2003

Microkinetic model Adsorption• H2(g) + 2* 2H*• CO (g) + * CO*• CO2 (g) + * CO2*Surface reaction• CO2* + H* HCOO* + *• HCOO* + H* H2COO* + *• H2COO* + H* H3CO* + O*• H3CO* + H* CH3OH* + *• H3CO* + H* CH3OH + *Regeneration of catalyst• CO* + O* CO2* + *• 2H* + O* H2O* + 2*

r.d.s.

Cu(100)

r.d.s. = Hydrogenation dioxomethylener.d.s. = Hydrogenation formateExperiment

» Synthesis of cyclic carbonates

Bimetallic catalyst for reaction of propylene oxide with CO2

R. Eberhard, M. Allmendinger, M. Zintl, C. Troll, G. A. Luinstra, B. Rieger, Macromol. Chem. Phys. 205 (2004) 42

Bu4N+Br- as co-catalystSelective reaction at 0-25°CTOF 18 h-1 at 0°CE. K. Noh, S. J. Na, S. Sujith, S.-W. Kim, B. Y. Lee, JACS 129 (2007) 8082

T. Sakakura et al. Chem. Rev. 107 (2007) 2365

CatCO2

Review on use of CO2: D. Walther, Nachrichten Chemie 55 (2007) 1188

» Synthesis of carbonates

Direct methoxylation of CO2

D. Ballivet-Tkatchenko, Appl. Cat. A: Gen. 255 (2003) 93

To be solved: removal of water

Mechanism

D. Walther, Nachrichten Chemie 55 (2007) 1188

Cat

» Synthesis of acrylates

Synthesis of acrylic acid from ethene and CO2

» Hypothetical cycle based on known model compounds

Red: isolated model compoundsBlue: fast reacting intermediates

D. Walther, Nachrichten Chemie 55 (2007) 1188

» Synthesis of aliphatic polycarbonates

Inoue et al. Macromol. Chem. 130 (1969) 210Macromol. Chem. C21 (1981) 135

Heterogeneous Zn-salts» Diethylzinc-water» Zn-glutarates

Soga et al. Polym. J. 13 (1981) 407

Darensbourgh et al. J. Mol Cat. A 104 (1995) L1Zheng et al. Z. Kristallogr. 215 (2000) 535Rieger et al. Chem. Eur. J. 11 (2005) 6298

Cat

» Synthesis of aliphatic polycarbonates

Zn-ß-diiminato complexes

Coates et al JACS 120 (1998) 11018; JACS 124 (2002) 14284; JACS 125 (2003) 11911; Angew. Chem. Int. Ed. 43 (2004) 6618

Bimetallic mechanism

Rieger et al. Chem. Eur. J. 11 (2005) 6298

» Synthesis of aliphatic polycarbonates

Cr, Co, Zn - Salen complexes

Darensbourgh et al. Coord. Chem. Rev. 153 (1996) 155; JACS 121 (1999) 107; Coord. Chem. Rev. 107 (2007) 2388

Rieger et al. Chem. Eur. J. 11 (2005) 6298

D. Walther, NachrichtenChemie 55 (2007) 1188

Cocatalyst:Imminium saltsPropyleneoxideTOF (22°C) 1100/h

Cocatalyst:Imminium saltsPropyleneoxideTOF (22°C) 1100/h

No cocatalyst:Selective alternatingPolymerisationTOF (80°C) 3500/h

No cocatalyst:Selective alternatingPolymerisationTOF (80°C) 3500/h

No cocatalyst:SelectiveBlock-Copolymerisation

No cocatalyst:SelectiveBlock-Copolymerisation

» Status of CO2 as building block

Thermal energy requiredlow yields, not efficientHet. (Pd, Rh)+MethaneAcetic acidC-C

Low yields, slow reactionElectron donors, hνCO, MeOH, CH4, …---First applicationsHom. (Co, Zn, Cr)-EpoxidePolycarbonates

No solution for economic removal of waterHom. + het.~0MethanolDimethylcarbonate

C-OC-N

C-H

--

-

-

ΔH

Commercial productionTechnical productionOnly stoichiometric

High TON and TOFnot competitive

Technical productionExcellent selectivity

Evaluation

EpoxideAmmoniaEthylene

Hydrogen

Hydrogen

Starting compound

Hom.Cyclic carbonatesNoneUreaHom. (Mo, Ni)Acrylic acid

Hom. (Ru, Rh)Formic acid

Het. (Zn-CuO)Methanol

CatalystProducts

Table adapted from D. Walther, Nachrichten Chemie 55 (2007) 1188

Chemical energy source

Artificial photosynthesis with Ru(bpy)3

2+

H. Arakawa et al, Chem. Rev. 2001, 101, 953-996Light as energy source

» Conclusions and outlook

The use of CO2 is an attractive option in global CO2 management

» C1 building block for chemical syntheses» Fixation in polymers particularly attractive» Energetically low level

» Reaction with reactive molecules» Equilibrium limited reactions» External energy source

» Inert molecule requiring activation The use of CO2 can not provide a single solution for the reduction of CO2 emissionsOverall energy balance needs to be considered

» Acknowledgements

Walter Leitner

Johannes LercherHerui Dou

EU TOPCOMBIDeutsche ForschungsgemeinschaftFonds der Chemischen IndustrieDr. Ing. Leonhard Lorenz Stiftung

» CO2 Fixation in Polymers

CAT Catalytic CenterRWTH AachenWorringerweg 152074 Aachen, Germany

www.catalyticcenter.rwth-aachen.deNew Orleans, 8 April 2008