4th EucheMs chemistry congress

Monday, 27-Aug 2012
s808
chem. Listy 106, s587–s1425 (2012)
Physical, theoretical and Computational Chemistry
Novel Materials – i
o - 0 9 8
CAtALytiC StudieS of feS towArdS AMMoniA
2
SyntheSiS under AMBient ConditionS
i. teMPrAno 1 , t. Liu 1 , S. JenKinS 1 , S. driver 1 ,
d. KinG 1
1 University of Cambridge, Chemistry, Cambridge,
United Kingdom
The synthesis of ammonia over an iron catalyst, via the
Haber-Bosch process, is one of the most important large-scale
industrial reactions underlying the modern global economy.
Essential for the manufacture of artificial fertilisers, this single
process is reckoned to be responsible for feeding up to one sixth
of the world population. On the other hand, such high
temperatures and pressures are necessary to achieve economic
performance that the Haber-Bosch process alone is thought to
consume up to one percent of all man-made energy production. [1]
At this scale, even a marginal improvement in efficiency would
imply enormous environmental benefits, not to mention inevitable
economic rewards. Of all the industrial processes, ammonia
synthesis is arguably the instance for which tuning catalytic
efficiency is most urgently required.
In nature, by way of contrast to the Haber-Bosch process,
the enzyme nitrogenase achieves much the same end under
ambient conditions. Efforts of protein crystallography have
gradually unveiled that the active sites of nitrogenase are
composed of three distinct FeS nanoclusters which cooperatively
x
accomplish the electron transfer and the N reduction processes. [2, 3]
2
In the light of the above understanding, we are investigating
NH -related reactions on Iron sulfide surfaces. In the presentation,
3
we will discuss the surface chemistry of N , H and NH on a
2 2 3
pyrite single crystal surface. The gas-surface interactions are
investigated by a combination of spatially averaging and localized
surface science techniques to ascertain whether NH synthesis is
3
favourable iron sulphide, with a view to establishing their
corresponding reaction mechanisms.
references:
1. Schlögl, R. Angewandte Chemie International Edition
2003, 42, 2004.
2. Howard, J. B.; Rees, D. C. Proceedings of the National
Academy of Sciences 2006, 103, 17088.
3. Einsle, O.; Tezcan, F. A.; Andrade, S. L. A.; Schmid, B.;
Yoshida, M.; Howard, J. B.; Rees, D. C. Science 2002,
297, 1696.
Keywords: Ammonia synthesis; Iron sulphide; Surface science;
Novel Materials – i
4 th EucheMs chemistry congress
o - 0 9 9
uv PhotodiSSoCiAtion dynAMiCS of
thioAniSoLeS: the effeCt of SuBStitution
d. K. zAouriS 1 , A. M. wenGe 1 , t. n. v. KArSiLi 1 ,
S. J. hArriS 1 , M. CottereLL 1 , M. n. r. AShfoLd 1
1 University of Bristol, School of Chemistry, Bristol,
United Kingdom
In this work, both experimental and theoretical, results from
the UV photodissociation of thioanisole [1] in the gas phase are
reported. The effect of substitution on the dynamics of the
photodissociation has also been studied, by introducing a methyl
(CH ) group, as a substituent, in para- position. The dissociation
3
has been studied using Velocity Map Imaging (VMI) technique
and detecting the produced, after the S-CH bond fission, methyl
3
fragments in their ground vibrational state (v = 0). Both velocity
and angular information are presented. The experimental results
are accompanied by high accuracy ab initio calculations, which
give the shape of the Potential Energy Cuts (PECs) of the ground
and the first two excited electronic states, along the S-CH3 coordinate. Such gas phase studies are an essential precursor to
on-going ultrafast pump-probe investigations of the
photochemistry of these molecules in solution.
references:
1. J.S. Lim and S.K. Kim, Nature Chemistry 2, 627 (2010).
Keywords: Photochemistry; Ab initio calculations; Substituent
effects; UV/Vis spectroscopy; Laser spectroscopy;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc