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A PhD Studentship available early 2006 at the Royal Institution/University College of London Molecular Simulation of CO Gas Adsorption in Hybrid Metal-Organic Materials 2 An EU-funded PhD studentship is available in the Davy Faraday Research Laboratory of the Royal Institution to work on molecular simulations of CO 2 adsorption in novel nanoporous metal-organic framework materials. Metal-organic frameworks (MOFs) form a recently developed class of porous materials with open architectures built from metal ions linked together by organic bridging ligands. The project will involve the use of a wide range of computational tools, including forcefield-based Monte Carlo modelling techniques and quantum chemical methods, to elucidate the atomic-scale mechanisms of gas adsorption in such materials. Attention will be especially focussed on flexible materials which possess the ability to expand and contract their pore volume during the adsorption process. The project forms part of a larger EU-funded STREP programme and the work will be carried out in close collaboration with experimental groups specializing in adsorption measurements and crystallography, both located in France. Further scientific details of the host Institution and the project are available at /www.ri.ac.uk/DFRL/ and /www.ri.ac.uk/DFRL/postgrad_pages/abstract.htm respectively. The studentship will be based at the Royal Institution in London under the supervision of Dr Robert Bell ...
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A PhD Studentship available early 2006 at the
Royal Institution/University College of London
Molecular Simulation of CO
2
Gas Adsorption in Hybrid Metal-Organic Materials
An EU-funded PhD studentship is available in the Davy Faraday Research Laboratory of the Royal
Institution to work on molecular simulations of CO 2 adsorption in novel nanoporous metal-organic
framework materials.
Metal-organic frameworks (MOFs) form a recently developed class of porous materials with open
architectures built from metal ions linked together by organic bridging ligands. The project will involve
the use of a wide range of computational tools, including forcefield-based Monte Carlo modelling
techniques and quantum chemical methods, to elucidate the atomic-scale mechanisms of gas
adsorption in such materials. Attention will be especially focussed on flexible materials which possess
the ability to expand and contract their pore volume during the adsorption process.
The project forms part of a larger EU-funded STREP programme and the work will be carried out in
close collaboration with experimental groups specializing in adsorption measurements and
crystallography, both located in France.
Further scientific details of the host Institution and the project are available at
/www.ri.ac.uk/DFRL/
and
/www.ri.ac.uk/DFRL/postgrad_pages/abstract.htm
respectively.
The studentship will be based at the Royal Institution in London under the supervision of Dr Robert
Bell (Fellow at the RI) and Dr. Caroline Mellot-Draznieks (Chargée de Recherche au CNRS), with the
student registered for the degree of PhD at University College London.
Applications are sought from EU students with a good Master's degree (2:1 MSci or equivalent) in
Chemistry or Physics. The studentship provides full university fees for UK and EU residents and a tax-
free stipend of £14,000 per annum.
The studentship is due to start as soon as possible in 2006
and will be for 3 years.
Applications, including a covering letter and full CV with the names of at least 2 referees, should be
sent to
Dr. Caroline Mellot-Draznieks, Royal Institution, 21 Albemarle Street, London W1S
4BS, UK. Email:
caroline@ri.ac.uk
.
Tel: 00 44 (0) 207 670 2927.
ABSTRACT
Carbon dioxide is the most important greehouse gas implicated in global warming, and enormous effort
is being put into finding new methods of separating, capturing and/or storing CO
2
, which are both
economical and environment friendly. Hybrid materials are interesting alternatives to other media such
as zeolites, due to their low framework density, excellent thermal stability and inexpensive synthesis.
Some of the key aspects governing the performance of such materials for CO
2
adsorption are (i) the
chemical nature of the organic ligands, especially grafted ligands, which can affect selectivity towards
CO
2
adsorption, (ii) the pore structure and (iii) the framework flexibility, all of which influence adsorption
capacity.
Metal-organic frameworks (MOFs) form a new
class of hybrid materials with open architectures
built from metal ions linked together by organic
bridging ligands, commonly carboxylate ions.
Recently, new types of MOFs have been
discovered that possess flexible frameworks,
able to expand and contract their pore volume,
depending on the nature and polarity of the
guest molecules (See Figure). Typically, some
metal carboxylates exhibit very unusual swelling
behaviour upon adsorption-desorption. Unlike
zeolitic materials that are characterized by a
relatively rigid framework under adsorption
conditions, such flexible frameworks may offer
the unique advantage of performing the
adsorption of guest molecules in a more specific
fashion by simply adapting their framework
structure accordingly.
Flexible
framework
of
MIL-88,
a
chromium
carboxylate, upon dehydration/adsorption process.
The
current
project
tackles
the
simulation
of
the
adsorption
of
CO
2
in
flexible
hybrid
frameworks
using
Monte
Carlo
based
techniques
in
the
grand
canonical
(P,V,T)
and
canonical
(N,V,T)
ensembles
together
with
forcefield
based
ener
gy
minimization
techniques.
The
work
aims
at
simulating
isotherms
and
isosteric
heats
of
adsorption
as
a
function
of
loading,
while
taking
into
account
the
dynamical
response
of
the
framewor
k
to
the
adsorption
of
CO
2
.
Unlike
similar
rigid
metal-organic
frameworks,
proper
modelling
of
the
flexibility
of
the
hybrid
framework
during
the
simulated
adsorption
process
is
an
essential
and
new
facet
of
the
present
proposed
work.
Indeed,
a
crucial
part
of
the
work
relates
to
the
correct
description
of
coulombic
interactions
and
the
use
of
appropriate
forcefield
for
desc
ribing
the
flexibili
ty
of
the
framework.
None
existing
methods
are
available
in
this
field,
and
it
will
be
a
c
ritical
challenge for simulating these systems accurately.
We
expect
the
simulation
wor
k
to
allow
us
to
understand
the
very
unusual
shapes
of
CO
2
isotherms
(hysteresis,
steps,
maximum
capaci
ty,
curvature)
and
the
evolution
of
CO
2
adsorption
enthalpies
as
a
function
of
loading.
In
order
to
ensure
the
significance
of
our
simulations,
we
expect
important
interactions with
the
simulation group
in
Montpellier and
experimental partne
rs,
typical
ly
thermodynamic
measurements in Ma
rseilles, and
synchrotron data from Versailles/ESRF.
Another
challenging
aspect
of
the
project
relates
to
the
simulation
of
CO
2
in
ve
ry
large
pore
mate
rials,
such
as
the
ve
ry
recent
MIL-100
and
MIL-101
hybrids.
1,2
These
materials
possess
a
rigid
a
rchitecture
that
is
reminiscent
of
the
MTN
zeolite
topology
and
exhibit
a
hierarc
hy
of
micro-
(Ø
≈
6.5-8.5
Å)
and
mesopo
res
(Ø
≈
25-30
Å)
with
ve
ry
large
surface
areas
(3000-5000
m
2
.g
-1
).
Indeed
the
simulation
of
CO
2
adsorption will aim at interpreting the adsorption capacities of these unusual materials.
References
1.
C. Mellot-
Draznieks et
al.
Angew. Chem. Int. Ed.
2004
, 43
(46) 6296-6301.
2.
C. Mellot-
Draznieks et
al.
Science
2005
, 309 , 2040-2042.
3.
G. Maurin, P. Llewellyn & R.G. Bell,
J. Phys. Chem. B
,
2005
, 109, 16084.
