Invited Paper MG-WeM12
Insights on the CO2 Reduction Mechanism on Bio-inspired Iron Sulphide
Wednesday, November 12, 2014, 11:40 am, Room 302
| Session: |
Design of New Materials |
| Presenter: |
Alberto Roldan, University College London, UK |
| Authors: |
A. Roldan, University College London, UK
N.H. de Leeuw, University College London, UK
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| Correspondent: |
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Carbon dioxide capture and utilisation is gaining attention, driven not only by environmental factors but also by the potential to use it as chemical feedstock. One plausible utilisation route is its conversion to form small organic molecules, however, CO2 is thermodynamically very stable and its reduction is energy intensive. The CO2 conversion takes place under mild conditions in chemoautotrophic bacteria catalysed by enzymes.1 These enzymes often contain Fe4S4 clusters (cubanes), which have been shown to act as electron-transfer sites2,3 but they can also be catalytically active centres for molecule transformations.4 An iron thiospinel mineral is structurally similar to the cubane,5 fact that brings us to suggest it as a novel heterogeneous catalyst. We present a theoretical investigation using the iron sulphide greigite mineral (Fe3S4) as a catalyst to transform CO2 into small organic molecules. In agreement with the experiments, the adsorbed species depends on the solution pH as well as both concentration and actual products formed. The reduction consists of a sequential hydrogenation steps that we studied by the common Langmuir-Hinshelwood mechanism. We have identified ~170 steady states describing the different reaction pathways where the most favourable ones lead to formate and carboxyl intermediates yielding two different products, HCOOH and CH3OH, also identified experimentally under conditions of room temperature and pressure. References
(1) Huber, C.; Wachtershauser, G. Science 1997, 276, 245.
(2) Nicolet, Y.; Amara, P.; Mouesca, J. M.; Fontecilla-Camps, J. C. Proc. Natl. Acad. Sci. U. S. A. 2009, 106, 14867.
(3) Hayashi, T.; Stuchebrukhov, A. Abstracts of Papers of the American Chemical Society 2012, 243.
(4) Seino, H.; Hidai, M. Chemical Science 2011, 2, 847.
(5) Martin, W.; Russell, M. J. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences 2003, 358, 59.