Spring 2012 Issue - University of Central Lancashire

24 Professors in Profile
Can I start by asking you what your
research is about? I know it is about
catalysis, but can you tell me in a bit
more detail.
Since the start of my research career, I have
been interested in catalysis, which is the
acceleration of a chemical reaction or
enabling a chemical reaction to take place at
a lower temperature. Catalysis is of huge
commercial and environmental importance,
not only providing financial savings to the
chemical industry but also enabling the
clean-up of environmental pollutants in, for
example, vehicle exhaust emissions. Initially
I worked with ICI Polymers Division on the
hydrogenation of nitriles (a nitrile is a
compound that contains the chemical group
-CN), which is important industrially in the
production of nylon and a variety of other
common chemical products.
Can I interrupt and clarify what happens
in catalysis? For catalysis to occur you
need a material, such as platinum to be
present, to enable the reaction to go
faster or take place at a lower
temperature?
That is right. The active catalyst, we are
talking generally about metal catalysts such
as platinum, needs to be present but you
don’t have a big solid piece of platinum. It is
just not effective. The catalyst is produced by
dispersing the metal in atomic or very small
ensembles of atoms on the surface of an
inert substrate, such as silica or alumina.
By dispersing them, you increase the surface
area and the effectiveness of the catalyst.
How did your interest in microwave
catalysis develop?
It was through our work with ICI that I
developed an interest in microwave catalysis.
There was a lot of early work, and early
reports in the literature, of microwaves being
used to give rapid reactions and vastly
enhanced rates. There appeared to be this
wonderful microwave effect! Therefore, we
set about a programme of work involving
ICI and EPSRC to look at the possible
advantageous effects of microwaves on
catalysts. Since those initial studies, I have
had a number of EPSRC awards in the area
of microwaves. I have developed the
technique of microwave thermal analysis in
conjunction with Professor Phil Barnes from
the University of Huddersfield, and have
worked with groups throughout the UK.
I have had visiting professorship at the
University of Technology of Compiègne
where we have developed specialised
reactors for studying catalysts under
microwave conditions. Currently I am a
member of the AMPERE Committee –
the Association for Microwave Power in
Education and Research in Europe.
I know a few years ago you were
working with companies like Jaguar on
microwave catalysis of exhaust fumes.
Can you tell me about that?
We have a strong track record of working
with industry. With Jaguar we had an
extensive research and development
programme. What we were looking at were
systems for the removal of diesel particulate
matter from vehicle exhaust streams. This
material is mainly made up of carbon, which
is deposited in the exhaust filter leading to
the filter eventually becoming ineffective.
The idea was to design a system, which used
microwaves to oxidise the carbon particles to
carbon dioxide and water so the filter had a
much longer life. Whilst allowing
combustion, it could not produce any back
pressure in the exhaust system, and had to
have a very minimum size in terms of the
effect on the floor pan of the vehicle. We
started developing a microwave induced
plasma to perform the oxidation reaction.
While we took this to vehicle trials, it was
apparent at a relatively early stage that the
exhaust velocities required and the available
power on board the vehicle were
incompatible. We therefore changed tactic
slightly, and started to look at systems for
the re-generation of diesel particulate filters.
We developed two patents on a prototype
system, which Jaguar currently holds. These
have been vehicle tested but given the
current legislation, it is not cost effective for
them to change the system they have.
Microwaves give a clean and efficient
alternative, but it is a case of whether or not
the consumer will pay the extra cost that is
required. Currently manufacturers can stay
within current EU legislation for emissions
using existing technologies. It is all based on
finance, and not always using the best
technology that is available.
What is currently engaging you in
your research?
Currently I am looking at microwave induced
plasma. I am part of a European partnership,
which is looking at its beneficial effects in
the production, and regeneration of
heterogeneous catalysts. A microwave
induced plasma is what is known as a
“cold” plasma; it has a high energy but low
thermal temperature. You can produce very
reactive species in that plasma, so in terms of
preparing catalysts, we can de-compose
catalyst pre-cursors at very low thermal
temperatures. This means that effects such
as the sintering of catalytic particles into
larger clumps is reduced. Usually you want
to keep your active particles as far apart as
possible giving the maximum catalytic
surface area. We already have companies
interested in this process.
For efficient catalysis to occur, you want
the catalytic surfaces to be separated
from each other?
The very small particles of catalytic material
such as platinum are active and can migrate
across the surface of the substrate, the
support, very easily. Therefore, you want to
expose your catalyst to the lowest possible
temperature during preparation to reduce
sintering or clumping. A cold plasma allows
you to do that.
“Since the start of my research career,
I have been interested in catalysis,
which is the acceleration of a chemical
reaction or enabling a chemical reaction
to take place at a lower temperature.”
Can I ask you about a cold plasma,
because it won’t be a concept that
many people are familiar with.
What is a cold plasma?
Most people describe plasma as probably the
fourth state of matter. In a plasma, generated
from a gas, the atoms have been ionised into
their component charges i.e. electrons and
atoms carrying an electric charge. Argon is
an easily ionised gas so it is a good base, but
then we also need a reactive component, so