Molecular Simulations
This project involves the application of a wide variety of molecular simulation techniques to problems in industry, such as catalysis. The focus is on a close collaboration between experimentalists and theorists such that computational methods can provide atomistic interpretations and rationalisation of experimental data to stimulate new directions for experiment.
We have concentrated on microporous materials such as zeolites, which find use as ion-exchangers and dessicants, as well as in many industrially important catalytic processes such as fluid-catalytic cracking and the methanol-to-gasoline process. Zeolites are also used extensively for non-cryogenic gas separation.
In the catalysis area, we are particularly interested in the use of transition-metal substituted systems for deNOx treatment of gasoline exhausts and also for partial oxidation reactions.
To investigate properties such as sorption and self-diffusion atomistic methods involving the use of forcefields have been the method of choice for studying microporous systems. We employ Born-model potentials to represent the zeolite framework, as there have been numerous parameter sets developed to handle both aluminosilicate and aluminophosphate systems. The development of potentials to represent the interactions between the zeolite framework and sorbed species is an active area of research.
Once realistic parameter sets have been derived, many statistical mechanically based simulation methods may be employed which can provide information that can usefully be compared to experiment. For example, the Monte Carlo docking technique can be used to probe the pore structure for preferred binding sites for the sorbate, and classical Grand-Canonical Monte Carlo simulations can be performed to calculate sorption isotherms. To investigate the transport properties of sorbates in zeolite pores, molecular dynamics simulations may be carried out. However, there are many cases in which the transport processes occur over time scales that are too long to be considered with classical molecular dynamics methods (especially for metal-exchanged zeolite systems). In these cases, constrained energy minimisations can be performed to calculate activation energies for the fundamental diffusion processes.
Electronic structure calculations have an important role in the investigation of the dominant factors which determine catalytic activity at the active site in a zeolite. We are using both Hartree-Fock and density functional methods to examine systems in which a transition metal has been substituted into the microporous structure and acts as a catalytic centre. The mechanisms of catalytical activity at the atomic level are often difficult to elucidate using experimental techniques and therefore these class of simulation methods have a vital role to play in furthering the understanding in this area.
People in T-12 working on this project include:
Last modified: Thu Nov 14 18:10:22 MST