co2 fixation: iron complexes for...
TRANSCRIPT
CO2 Fixation: Iron Complexes for Catalysis
Alexander J. Kendall – Tyler Lab Group Meeting – 4/16/2014
Why Fix CO2?
• Convenient C1 source • 0.04% Earth’s atmosphere v/v
• Common industrial byproduct• Often excellent quality (>99%
pure)
• Limited uses of CO2
• Super-critical CO2
• Cooling agent
• Industrial pollutant (combustion)• Greenhouse gas
• Move towards carbon neutral processes
Don’t Fix CO2?
• Difficult to isolate out of gas mixtures
• Very thermodynamically stable
• Kinetically fairly inert
• Difficult to use compared to CO as a C1 source
• Carbon neutral process• Low energy input
• Generally requires noble or rare-earth metals
Global Industrial CO2 Stream
• Industrial CO2 emissions = 29 billion metric tons per year
• Less than 1% is reused
• CO2 contributes to rising levels of greenhouse gasses
• 1820 = 280 ppm• 1981 = 340 ppm• 2013 = 395 ppm
• CO2 contributes to ocean acidification
• 35% of all CO2 generated re-dissolves in bodies of water
Emissions, 2.90E+10
Chemical Capture, 1.10E+08
Neat Capture, 1.80E+07
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E+09
1.0E+10
1.0E+11
Emissions Chemical Capture Neat Capture
Metr
ic T
ons o
f C
O2
Industrial CO2 Emissions vs Consumption 2010
http://www.noaa.gov/ Beller, M.; Bornscheuer, U. T. Angew.
Chem. Int. Ed. 2014, 53, 2–4.
Two Approaches to CO2
• Carbon(IV) to Carbon(IV)• Thermodynamically favorable
• Energetically neutral or exothermic
• Narrow window of chemically useful compounds
Beller, M.; Bornscheuer, U. T. Angew. Chem. Int. Ed. 2014, 53, 2–4. ; Tolman, W. B. Activation of Small Molecules: Organometallic and Bioinorganic Perspectives; 1 edition.; Wiley-VCH: Weinheim, 2006.
Two Approaches to CO2
• Carbon(IV) reduction (fixation)• Require input energy to reduce carbon(IV)
• Energy intensive processes can generate more CO2 than they fix
• Extensive range of useful compounds (varying degrees of cost/benefit)
• Hydrogen storage
Beller, M.; Bornscheuer, U. T. Angew. Chem. Int. Ed. 2014, 53, 2–4. ; Tolman, W. B. Activation of Small Molecules: Organometallic and Bioinorganic Perspectives; 1 edition.; Wiley-VCH: Weinheim, 2006.
4+ 3+
3+2+ 2+ 0 2- 4-
Thermodynamic Considerations
• ∆𝐻𝑓𝑜 (kJ/mol)
CO2(g)-393.5
CH4(g)-74.4
H2(g)0.0
H2O(g)-241.8
∆Ho= -164 kJ/mol
• Carbon(IV) reduction• Use high energy reagents to become exothermic
• Net systemic energy loss • Hydrogen production (endothermic)
• Generate heat/pressure
• Net CO2 gain
Kinetic Considerations
• Activating CO2
• Non-polar
• Electrophilic
• Generally requires dual activation• Nucleophile to attack C
• Electrophile to attack O
• Requires geometry change
Ansari, M. B.; Park, S.-E. Energy Environ. Sci. 2012, 5, 9419.
Kinetic Considerations
Ansari, M. B.; Park, S.-E. Energy Environ. Sci. 2012, 5, 9419.
HOMO
LUMO
133-135o
The First Isolated Metal-CO2 Complex
Aresta, M.; Nobile, C. F.; Albano, V. G.; Forni, E.; Manassero, M. J. Chem. Soc. Chem. Commun. 1975, 636–637.
The First Fe-CO2 Reduction
Gao, Y.; Holah, D. G.; Hughes, A. N.; Spivak, G. J.; Havighurst, M. D.; Magnuson, V. R.; Polyakov, V. Polyhedron 1997, 16, 2797–
2807.
Early FeII-H Reduction of CO2
Field, L. D.; Lawrenz, E. T.; Shaw, W. J.; Turner, P. Inorg. Chem. 2000, 39, 5632–5638.
FeII-H Disproportionation of CO2
Allen, O. R.; Dalgarno, S. J.; Field, L. D. Organometallics 2008, 27, 3328–3330.
CO2 Reduction to Oxalate at FeI
Lu, C. C.; Saouma, C. T.; Day, M. W.; Peters, J. C. J. Am. Chem. Soc. 2007, 129, 4–5.
CO2 Reduction to Oxalate at FeI
Lu, C. C.; Saouma, C. T.; Day, M. W.; Peters, J. C. J. Am. Chem. Soc. 2007, 129, 4–5.
CO2 Reduction to Oxalate at FeI
Saouma, C. T.; Lu, C. C.; Day, M. W.; Peters, J. C. Chem. Sci. 2013, 4, 4042–4051.
FeI-Mediated CO2 Disproportionation
Sadique, A. R.; Brennessel, W. W.; Holland, P. L. Inorg. Chem. 2008, 47, 784–786.
FeI-Mediated CO2 Disproportionation
Sadique, A. R.; Brennessel, W. W.; Holland, P. L. Inorg. Chem. 2008, 47, 784–786.
CO2 Reduction to SynGas at FeII
Thammavongsy, Z.; Seda, T.; Zakharov, L. N.; Kaminsky, W.; Gilbertson, J. D. Inorg. Chem. 2012, 51, 9168–9170.
Catalytic CO2 Hydrogenation to Formic Acid
Ziebart, C.; Federsel, C.; Anbarasan, P.; Jackstell, R.; Baumann, W.; Spannenberg, A.; Beller, M. J. Am. Chem. Soc. 2012, 134, 20701– 20704.
Catalytic CO2
Hydrogenation to Formic Acid
Ziebart, C.; Federsel, C.; Anbarasan, P.; Jackstell, R.; Baumann, W.; Spannenberg, A.; Beller, M. J. Am. Chem. Soc. 2012, 134, 20701– 20704.
Summary & CO2nclusions
• CO2 is an industrial byproduct that has use as a feedstock chemical
• Requires development of inexpensive CO2
reduction catalysts
• Activating CO2 at Fe requires hydrides (reduction) or disproportionation (CO & CO3
2-)
• Catalytic hydrogenation of CO2 is possible, but requires H2, 60 Atm and is low yielding.
• Better CO2 catalysts are needed to utilize as a general C1 synthetic building block
• Materials & biological CO2 fixation also lacking
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E+09
1.0E+10
1.0E+11
Emissions ChemicalCapture
Neat CaptureMetr
ic T
ons o
f C
O2
Industrial CO2 Emissions vs Consumption 2010
Questions