Professor Sean Rigby

The requirement to characterise the structure of porous solids arises in a number of fields of study, such as catalysis, fuel cells, soil remediation, water resources management, hydrothermal vents, oil recovery and bone diseases, to name but a few. It is important to determine the nature of the structure of a porous solid in order to fully understand transport processes that may be taking place within those materials (see below).

My work has focussed on employing a synergistic combination of different characterisation techniques in order to provide a more comprehensive description of porous media than is possible using one method alone. This is because each experimental technique has its own set of strengths and weaknesses. I have combined the traditional techniques of gas sorption and mercury porosimetry with tomographic methods such as MRI and MFX. Much of the work involves developing more sophisticated models for the interpretation of gas sorption and mercury porosimetry. A variety of different modelling methodologies have been adopted, which include employing concepts from fractal physics, for example.

The different applications of porous media mentioned above involve a variety of transport phenomena. Another area of my research work focuses on the study of the physical processes involved, and the influence of the pore structure, on pore diffusion, the surface diffusion of molecules, the permeation of liquids, the sintering of dispersed supported metal catalysts, and the displacement of wetting by non-wetting fluids (and vice-versa). The structural architecture of porous media will significantly influence the rates of the various transport processes that occur within them. This work involves the construction of models for the transport processes and porous structures, and the subsequent validation of the model predictions against experimental data. The experimental techniques that I employ for studying transport include MRI, Pulsed-field Gradient Spin-Echo NMR and deuterium NMR. A greater understanding of the transport processes and the factors that influence their rates will allow us to design more effective catalysts that are more resistant to deactivation, or improve the recovery efficiency of oil, for example.

This work is carried out in collaboration with Professor Malcolm Greaves of the Chemical Engineering Department at the University of Bath, and Dr Joseph Wood, of the University of Birmingham. My interests in EOR include the development of experimental techniques and theoretical analysis methods for structural characterisation of oil reservoir rock cores, using methods such as magnetic resonance imaging (MRI), pulsed-field gradient (PFG) NMR, mercury porosimetry, gas sorption and microscopy. I am also interested in transport phenomena in reservoir rocks. The particular processes that I study are gas and/or liquid phase permeation and adsorption, and the entrapment of non-wetting phases (such as oil) within porous solids. These studies are both theoretical (eg molecular dynamics simulations of flows of non-wetting fluids) and experimental (eg gas permeation, and mercury intrusion and extrusion). The purpose of these studies is to predict key characteristic parameters for reservoir rocks, such as the bound volume index (BVI), that are used in reservoir economic evaluation and reservoir simulations. I also work on reservoir simulations of various EOR methods, such as THAI and CAPRI.

This work is carried out in collaboration with Drs. Karen Edler, John Lowe and Marianne Ellis of the University of Bath, Dr Chris Van der Walle of the University of Strathclyde, and Dr. Jim Raistrick of the University of Keele. A greater understanding of the physical processes involved in the release of drugs from polymeric vehicles is essential for the design of new controlled release devices. My work in this area focuses on using MFX imaging and NMR (PGSE and DOSY) techniques to study the drug spatial distribution and structural evolution within polymeric vehicles during the drug release process. These data are used to construct mathematical models of controlled drug release.

This work is carried out in collaboration with Drs. Karen Edler, Andrew Burrows and Mary Mahon from the Department of Chemistry at Bath. My work in this area concerns the synthesis and characterisation of novel, structured porous solids for use as gas storage media, catalyst supports, and model systems to study transport phenomena in porous solids. Projects involve the experimental synthesis and characterisation of new structured, mesoporous silicas and silica films, experimental synthesis and characterisation of new microporous metal-organic framework materials, and computer simulation of the various synthesis processes involved.