Computer simulation of the adsorption of chlorinated organics in zeolites
Computer modelling techniques have been used to study the adsorption of three chlorinated hydrocarbons Dichloromethane, 1,2-Dichloroethane, and Trichloroethene in three different zeolite frameworks MFI, MOR and FAU. Calculations have been performed using both classical methods based on inter-atomic potentials, quantum mechanical Density Functional Theory (DFT) and combined QM/MM embedded methods. The first section of this thesis presents results of DFT calculations on purely siliceous and aluminosilicate gas-phase clusters. The results obtained are compared to experimental data and are found to differ significantly from experimental results. The reasons for this are rationalised and alternative methods suggested. The second section investigates some of these alternative approaches. Results of a Periodic DFT study and cluster calculations using a hybrid functional are presented. The QMPot embedded cluster method is then employed as an alternative to the cluster and periodic DFT approaches. The results of these different approaches are compared and rationalised. The thesis then moves on to describe atomistic simulations of the adsorption and diffusion of the molecules in the framework structures. The third section of this thesis uses the Grand Canonical Monte Carlo method to simulate adsorption isotherms and isosteric heat plots. The simulated data is found to be in good agreement to that in the literature. The final chapter describes results of a Molecular Dynamics simulation which models the diffusion of the molecules in the FAU framework at different temperatures.