The project is funded by Air Products under a strategic alliance agreement. The aim is to study the structure and cation location in the zeolite chabazite, and the influence of these on the physical adsorption of nitrogen and oxygen.
This is a CEC funded project in partnership with scientific and industrial groups from France, Germany and Greece. The overall aim of the project is to investigate and develop the use of heulandite type zeolites for the purpose of methane/nitrogen and methane/carbon dioxide separations. The part of this work with which we are most closely associated is to model the physical adsorption and transport properties of the relevant systems.
This work has several strands. It was initiated in the early 90's as part of a CEC funded BRITE project, when a method for carrying out NEMD (non-equilibrium molecular dynamics) was developed in collaboration with Dr. Roger Cracknell and Nick Quirke. To date most effort has been directed towards studying the density dependence of adsorbate transport in idealised slit pore models, and to gaining an understanding of the complex molecular mechanisms underlying the phenomenological coefficients. New work is now being initiated to use these methods to investigate transport in buckytubes with cylindrical cross sections.
Computer simulation methods are being developed to carry out grand ensemble Monte Carlo in ionic solutions. These methods will subsequently be extended to confined spaces, and linked to NEMD methods.
The importance of nitrogen as an adsorbate in carbonaceous adsorbents has led to a large number of theoretical and experimental studies, nevertheless uncertainty remains about the precise form of the nitrogen graphite interaction potential. The first aim of this work is to exploit powerful local computing resources to obtain benchmark values for the potential energy at selected positions from high quality quantum mechnical calculations. Density functional theory and perturbation theory will also be used to study the problem. The final goal being a model which accurately reflects the interaction and is at the same time tractable as an input for simulations.
Differential heats of adsorption reflect the interaction between adsorbate
molecules and between adsorbate and the adsorbent. They are extremely sensitive
to pore size when this approaches molecular dimensions. Simulation studies
afford an opportunity to explore the effects of pore size distribution
and will lead to an improved interpretatuion of this experimental property.