As a result of our current and on-going research efforts, we will be
examining a variety of adsorption related areas in the future and welcome
interested post-graduate and post-doctoral applicants to contact
us for more information. The following are future potential
research areas:
Pressure
Swing adsorption relies on cycling the system pressure to produce separate a
mixture of gases.
The amount of adsorbent required to produce a given quantity of product
is directly related to the frequency of the pressure swing – high frequency
gives high throughput.
Unfortunately, high frequency switching of valves as well as void losses
leads to rapid mechanical failure and low recoveries.
In this project, we want to explore new ways of rapidly changing system
pressure without the need for mechanical switching of valves – examples might
be piston based systems or acoustic wave processes.
This is a highly innovative project in which both theory and practice
must be developed from the ground up.
The
use of adsorbents to separate gases is dependent on the rate at which the gas
can enter and escape the adsorbent.
The pore structure of the adsorbent pellet plays a dominant role in
determining the rate of mass transfer and it is very important that this rate is
quantified before large scale processes are developed.
Thus, measurement of kinetics of adsorption is important in the overall
adsorption engineering process.
Unfortunately, current adsorbents are too “fast” for conventional
kinetic tests to work and hence new tests must be developed.
This project will develop new testing methodologies and equipment for
characterising the rate of mass transfer in adsorbents and also develop
modelling techniques to enable the data obtained from the new test unit to be
used in process modelling simulators.
Adsorption
processes such as pressure swing adsorption (PSA), vacuum swing adsorption (VSA)
and temperature swing adsorption (TSA) are unsteady-state, non-linear, coupled,
batch-like processes that are difficult to build and run.
Since there are many design and process parameters which govern the
operation of an adsorption process, designing an “optimal” process is time
consuming and costly.
For example, an experimental PSA system can have up to 15 variables which
could be adjusted – each experiment can take a day to complete and hence
several months (even years) may be needed to determine an “optimal” set of
process conditions.
As a results, mathematical models have been developed to simulate
adsorption cycles with the hope that that these models will enable rapid
determination of optimal designs.
Unfortunately, these models often take as long to run as the experiment
itself.
This project will examine radical new approaches to adsorption simulation
to enable order of magnitude reduction in computer time for adsorption
simulation
New adsorption technology is driven by customer demand (new
applications) as well as the development of new adsorbents which show greater
selectivity than old adsorbents. One
group of adsorbents – zeolites – are known to be excellent adsorbents and
are used commercially to separate gases. In
the drive to improve separation efficiency, there is a need to understand the
fundamental reason for the selectivity of zeolites and thereby synthesize
improved zeolitic adsorbents called more generally metallosilicates. This
project will examine the synthesis and mechanisms behind the use of zeolites for
gas separation. See a related
project for more details.
Agricultural
residues, especially rice husk, the by-product of the rice milling industry is
produced in large quantities as a waste, creating environmental problems. Rice
husk mainly consists of hemicellulose(HC), lignin(L), cellulose(C) and silica.
Based on the molecular composition of rice husk, the silica and organic content
can be advantageously exploited for the production of nanoporous carbon by using
the silica as a natural template and a renewable silica source. The present
project proposes to consider the rice husk waste as a resource base for
production of technologically important materials like nanoporous carbon and
silica rather than a problematic waste, by using environmentally friendly
processing methodologies. The salient features of the proposal are the
sequential depolymerisation with acidic gas and organic acids as pretreatment
with increasing severity to sequentially remove alkali, hemicellulose, lignin
and cellulose from rice husk. In turn these are precursors for derivatives of
furan, phenol etc. The pretreatment will alter the rice husk C/Si ratio and
composition, which will have a large influence on evolution of pore structure,
surface area, pore volume etc. The second part of the study is the pyrolysis of
rice husk and the pretreated husk to produce a carbon-silica composite in
different activating conditions and removal of the silica component by selective
leaching. The physico-chemical characteristics of the samples will be determined
using spectroscopic and adsorption methods.
The final part of the investigation is the study of gas storage(H2,CO2,
CH4) and separation characteristics of the resultant materials.
PSA (pressure swing adsorption) is widely used to
produce oxygen from air. Since air
contains 1% argon, and argon and oxygen adsorb to the same degree on current
adsorbents, it is not possible to separate the oxygen from the argon.
As a result, O2 PSA processes can produce a maximum purity of 96% oxygen
only (the remainder is argon). PSA
is therefore limited to “low purity” applications such as combustion – if
a way could be found to produce >99% oxygen, significant inroads into
conventional distillation techniques can be made.
In this project, it is proposed to combine aspects of equilibrium
separations (conventional adsorbents) with kinetic separations (molecular sieve
carbon - MSC) to produce a multi-layered system that can separate both nitrogen
and argon from air.
Separation and purification of mixtures are
process operations of great importance in the chemical and biological
industries. Adsorbents play a major role in separation technologies due to their
ability to selectively adsorb one or more components from a mixture. One
particular feature of adsorbents of great importance is their internal porous
structure. In this project, we will develop a new suite of nano-engineering
techniques to create adsorbents with an ordered, well connected internal pore
network at length scales from microscopic to macroscopic. This approach will
lead to advanced materials with unprecedented separation performance
significantly improving existing separations and offering new options for
difficult separations.
The efficient storage of hydrogen for transport
applications represents one of the largest hurdles in transitioning to the
hydrogen economy. Current methods simply do not meet the required volumetric
and gravimetric densities. Research into new materials to achieve these high
storage densities is a very active area of study internationally with most major
automobile and energy companies supporting their own in-house R&D efforts. The
proposed study has the direct goal of achieving high volumetric and gravimetric
storage densities of hydrogen through novel synthetic approaches to a newly
recognized but, as yet, unrealized family of intercalated, pillared carbon
structures.