Confinement and pore shape effects on adsorption, diffusion and reaction in zeolites

Atomistic simulations are used to study the shape effects arising from variation in pore structure on adsorption, diffusion and reaction in zeolites. Siting of single species within the pores is shown to be important in determining macroscopic properties. In some cases, the shape of isotherms and trends in heats of adsorption can be explained through siting effects. A second species adds complexity to the siting and can lead to segregation of the two species into different regions of the structure. Siting and segregation effects are also examined in chiral systems where shape matching between the molecule and environment play an interesting role.; Pore shape effects on diffusion are studied in two systems. Extensive simulations of n-alkanes in the faujasite framework indicate that this relatively open structure allows the adsorbed phase to retain many structural and dynamic properties of the liquid phase. However, interesting transitions in the diffusion mechanism can be observed as a function of chain length. It is the interaction of the chain length scale with the pore shape that produces siting effects and these transitions. Additional siting and segregation effects are studied in an example of Derouane's Molecular Traffic Control effect and are found to be a major contributing cause. Atomistic simulations establish that this effect is reasonable.; Development of improved simulation techniques is also pursued to provide more tools for studying shape effects. We show that it is possible to import widely available liquid-phase potential models into the adsorbed phase, enabling facile incorporation of charges into the simulations. An example of the importance of polarization effects is given and explicit polarization is found to be necessary to correctly predict experimental siting and segregation in sodium mordenite. To investigate environmental shape effects during reaction, a novel method incorporating electronic information through the Fukui function is developed. Testing in the gas phase indicates that it can reproduce substituent and steric effects in various electrophilic aromatic substitution reactions. Further applications in transition state shape selective catalysis should be fruitful.